fall phytoplankton bloom: Topics by WorldWideScience.org

Sample records for fall phytoplankton bloom

Sedimentation of phytoplankton during a diatom bloom : Rates and mechanisms

DEFF Research Database (Denmark)

Kiørboe, Thomas; Hansen, J.L.S.; Alldredge, A.L.

1996-01-01

Phytoplankton blooms are uncoupled from grazing and are normally terminated by sedimentation. There are several potential mechanisms by which phytoplankton cells may settle out of the photic zone: sinking of individual cells or chains, coagulation of cells into aggregates with high settling...... velocities, settling of cells attached to marine snow aggregates formed from discarded larvacean houses or pteropod feeding webs, and packaging of cells into rapidly falling zooplankton fecal pellets. We quantified the relative significance of these different mechanisms during a diatom bloom in a temperate...... to marine snow aggregates formed from discarded larvacean houses, whereas settling of unaggregated cells was insignificant. Formation rates of phytoplankton aggregates by physical coagulation was very low, and losses by this mechanism were much less than 0.07 d(-1); phytoplankton aggregates were neither...
A multiomics approach to study the microbiome response to phytoplankton blooms.

Science.gov (United States)

Song, Liyan

2017-06-01

Phytoplankton blooms are predictable features of marine and freshwater habitats. Despite a good knowledge base of the environmental factors controlling blooms, complex interactions between the bacterial and archaeal communities and phytoplankton bloom taxa are only now emerging. Here, the current research on bacterial community's structural and functional response to phytoplankton blooms is reviewed and discussed and further research is proposed. More attention should be paid on structure and function of autotrophic bacteria and archaea during phytoplankton blooms. A multiomics integration approach is needed to investigate bacterial and archaeal communities' diversity, metabolic diversity, and biogeochemical functions of microbial interactions during phytoplankton blooms.
Phytoplankton-Associated Bacterial Community Composition and Succession during Toxic Diatom Bloom and Non-Bloom Events.

Science.gov (United States)

Sison-Mangus, Marilou P; Jiang, Sunny; Kudela, Raphael M; Mehic, Sanjin

2016-01-01

Pseudo-nitzschia blooms often occur in coastal and open ocean environments, sometimes leading to the production of the neurotoxin domoic acid that can cause severe negative impacts to higher trophic levels. Increasing evidence suggests a close relationship between phytoplankton bloom and bacterial assemblages, however, the microbial composition and succession during a bloom process is unknown. Here, we investigate the bacterial assemblages before, during and after toxic and non-toxic Pseudo-nitzschia blooms to determine the patterns of bacterial succession in a natural bloom setting. Opportunistic sampling of bacterial community profiles were determined weekly at Santa Cruz Municipal Wharf by 454 pyrosequencing and analyzed together with domoic acid levels, phytoplankton community and biomass, nutrients and temperature. We asked if the bacterial communities are similar between bloom and non-bloom events and if domoic acid or the presence of toxic algal species acts as a driving force that can significantly structure phytoplankton-associated bacterial communities. We found that bacterial diversity generally increases when Pseudo-nitzschia numbers decline. Furthermore, bacterial diversity is higher when the low-DA producing P. fraudulenta dominates the algal bloom while bacterial diversity is lower when high-DA producing P. australis dominates the algal bloom, suggesting that the presence of algal toxin can structure bacterial community. We also found bloom-related succession patterns among associated bacterial groups; Gamma-proteobacteria, were dominant during low toxic P. fraudulenta blooms comprising mostly of Vibrio spp., which increased in relative abundance (6-65%) as the bloom progresses. On the other hand, Firmicutes bacteria comprising mostly of Planococcus spp. (12-86%) dominate during high toxic P. australis blooms, with the bacterial assemblage showing the same bloom-related successional patterns in three independent bloom events. Other environmental
Phytoplankton-associated bacterial community composition and succession during toxic diatom bloom and non-bloom events

Directory of Open Access Journals (Sweden)

Marilou P. Sison-Mangus

2016-09-01

Full Text Available Pseudo-nitzschia blooms often occur in coastal and open ocean environments, sometimes leading to the production of the neurotoxin domoic acid that can cause severe negative impacts to higher trophic levels. Increasing evidence suggests a close relationship between phytoplankton bloom and bacterial assemblages, however, the microbial composition and succession during a bloom process is unknown. Here, we investigate the bacterial assemblages before, during and after toxic and non-toxic Pseudo-nitzschia blooms to determine the patterns of bacterial succession in a natural bloom setting. Opportunistic sampling of bacterial community profiles were determined weekly at Santa Cruz Municipal Wharf by 454 pyrosequencing and analyzed together with domoic acid levels, phytoplankton community and biomass, nutrients and temperature. We asked if the bacterial communities are similar between bloom and non-bloom events and if domoic acid or the presence of toxic algal species acts as a driving force that can significantly structure phytoplankton-associated bacterial communities. We found that bacterial diversity generally increases when Pseudo-nitzschia numbers decline. Furthermore, bacterial diversity is higher when the low-DA producing P. fraudulenta dominates the algal bloom while bacterial diversity is lower when high-DA producing P. australis dominates the algal bloom, suggesting that the presence of algal toxin can structure bacterial community. We also found bloom-related succession patterns among associated bacterial groups; Gamma-proteobacteria, were dominant during low toxic P. fraudulenta blooms comprising mostly of Vibrio spp., which increased in relative abundance (6%-65% as the bloom progresses. On the other hand, Firmicutes bacteria comprising mostly of Planococcus spp. (12%- 86% dominate during high toxic P. australis blooms, with the bacterial assemblage showing the same bloom-related successional patterns in 3 independent bloom events. Other
Subsurface phytoplankton blooms fuel pelagic production in the North Sea

DEFF Research Database (Denmark)

Richardson, Kathrine; Visser, Andre; Pedersen, Flemming

2000-01-01

The seasonal phytoplankton biomass distribution pattern in stratified temperate marine waters is traditionally depicted as consisting of spring and autumn blooms. The energy source supporting pelagic summer production is believed to be the spring bloom. However, the spring bloom disappears...... relatively quickly from the water column and a large proportion of the material sedimenting to the bottom following the spring bloom is often comprised of intact phytoplankton cells. Thus, it is easy to argue that the spring bloom is fueling the energy demands of the benthos, but more difficult to argue...... convincingly that energy fixed during the spring bloom is fueling the pelagic production occurring during summer months. We argue here that periodic phytoplankton blooms are occurring during the summer in the North Sea at depths of >25 m and that the accumulated new production [sensu (Dugdale and Goering...
Eddy-driven stratification initiates North Atlantic spring phytoplankton blooms.

Science.gov (United States)

Mahadevan, Amala; D'Asaro, Eric; Lee, Craig; Perry, Mary Jane

2012-07-06

Springtime phytoplankton blooms photosynthetically fix carbon and export it from the surface ocean at globally important rates. These blooms are triggered by increased light exposure of the phytoplankton due to both seasonal light increase and the development of a near-surface vertical density gradient (stratification) that inhibits vertical mixing of the phytoplankton. Classically and in current climate models, that stratification is ascribed to a springtime warming of the sea surface. Here, using observations from the subpolar North Atlantic and a three-dimensional biophysical model, we show that the initial stratification and resulting bloom are instead caused by eddy-driven slumping of the basin-scale north-south density gradient, resulting in a patchy bloom beginning 20 to 30 days earlier than would occur by warming.
Bacterial community transcription patterns during a marine phytoplankton bloom.

Science.gov (United States)

Rinta-Kanto, Johanna M; Sun, Shulei; Sharma, Shalabh; Kiene, Ronald P; Moran, Mary Ann

2012-01-01

Bacterioplankton consume a large proportion of photosynthetically fixed carbon in the ocean and control its biogeochemical fate. We used an experimental metatranscriptomics approach to compare bacterial activities that route energy and nutrients during a phytoplankton bloom compared with non-bloom conditions. mRNAs were sequenced from duplicate bloom and control microcosms 1 day after a phytoplankton biomass peak, and transcript copies per litre of seawater were calculated using an internal mRNA standard. Transcriptome analysis revealed a potential novel mechanism for enhanced efficiency during carbon-limited growth, mediated through membrane-bound pyrophosphatases [V-type H(+)-translocating; hppA]; bloom bacterioplankton participated less in this metabolic energy scavenging than non-bloom bacterioplankton, with possible implications for differences in growth yields on organic substrates. Bloom bacterioplankton transcribed more copies of genes predicted to increase cell surface adhesiveness, mediated by changes in bacterial signalling molecules related to biofilm formation and motility; these may be important in microbial aggregate formation. Bloom bacterioplankton also transcribed more copies of genes for organic acid utilization, suggesting an increased importance of this compound class in the bioreactive organic matter released during phytoplankton blooms. Transcription patterns were surprisingly faithful within a taxon regardless of treatment, suggesting that phylogeny broadly predicts the ecological roles of bacterial groups across 'boom' and 'bust' environmental backgrounds. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.
Pronounced daily succession of phytoplankton, archaea and bacteria following a spring bloom.

Science.gov (United States)

Needham, David M; Fuhrman, Jed A

2016-02-29

Marine phytoplankton perform approximately half of global carbon fixation, with their blooms contributing disproportionately to carbon sequestration(1), and most phytoplankton production is ultimately consumed by heterotrophic prokaryotes(2). Therefore, phytoplankton and heterotrophic community dynamics are important in modelling carbon cycling and the impacts of global change(3). In a typical bloom, diatoms dominate initially, transitioning over several weeks to smaller and motile phytoplankton(4). Here, we show unexpected, rapid community variation from daily rRNA analysis of phytoplankton and prokaryotic community members following a bloom off southern California. Analysis of phytoplankton chloroplast 16S rRNA demonstrated ten different dominant phytoplankton over 18 days alone, including four taxa with animal toxin-producing strains. The dominant diatoms, flagellates and picophytoplankton varied dramatically in carbon export potential. Dominant prokaryotes also varied rapidly. Euryarchaea briefly became the most abundant organism, peaking over a few days to account for about 40% of prokaryotes. Phytoplankton and prokaryotic communities correlated better with each other than with environmental parameters. Extending beyond the traditional view of blooms being controlled primarily by physics and inorganic nutrients, these dynamics imply highly heterogeneous, continually changing conditions over time and/or space and suggest that interactions among microorganisms are critical in controlling plankton diversity, dynamics and fates.
Rising CO2 levels will intensify phytoplankton blooms in eutrophic and hypertrophic lakes.

Directory of Open Access Journals (Sweden)

Jolanda M H Verspagen

Full Text Available Harmful algal blooms threaten the water quality of many eutrophic and hypertrophic lakes and cause severe ecological and economic damage worldwide. Dense blooms often deplete the dissolved CO2 concentration and raise pH. Yet, quantitative prediction of the feedbacks between phytoplankton growth, CO2 drawdown and the inorganic carbon chemistry of aquatic ecosystems has received surprisingly little attention. Here, we develop a mathematical model to predict dynamic changes in dissolved inorganic carbon (DIC, pH and alkalinity during phytoplankton bloom development. We tested the model in chemostat experiments with the freshwater cyanobacterium Microcystis aeruginosa at different CO2 levels. The experiments showed that dense blooms sequestered large amounts of atmospheric CO2, not only by their own biomass production but also by inducing a high pH and alkalinity that enhanced the capacity for DIC storage in the system. We used the model to explore how phytoplankton blooms of eutrophic waters will respond to rising CO2 levels. The model predicts that (1 dense phytoplankton blooms in low- and moderately alkaline waters can deplete the dissolved CO2 concentration to limiting levels and raise the pH over a relatively wide range of atmospheric CO2 conditions, (2 rising atmospheric CO2 levels will enhance phytoplankton blooms in low- and moderately alkaline waters with high nutrient loads, and (3 above some threshold, rising atmospheric CO2 will alleviate phytoplankton blooms from carbon limitation, resulting in less intense CO2 depletion and a lesser increase in pH. Sensitivity analysis indicated that the model predictions were qualitatively robust. Quantitatively, the predictions were sensitive to variation in lake depth, DIC input and CO2 gas transfer across the air-water interface, but relatively robust to variation in the carbon uptake mechanisms of phytoplankton. In total, these findings warn that rising CO2 levels may result in a marked
Rising CO2 Levels Will Intensify Phytoplankton Blooms in Eutrophic and Hypertrophic Lakes

Science.gov (United States)

Verspagen, Jolanda M. H.; Van de Waal, Dedmer B.; Finke, Jan F.; Visser, Petra M.; Van Donk, Ellen; Huisman, Jef

2014-01-01

Harmful algal blooms threaten the water quality of many eutrophic and hypertrophic lakes and cause severe ecological and economic damage worldwide. Dense blooms often deplete the dissolved CO2 concentration and raise pH. Yet, quantitative prediction of the feedbacks between phytoplankton growth, CO2 drawdown and the inorganic carbon chemistry of aquatic ecosystems has received surprisingly little attention. Here, we develop a mathematical model to predict dynamic changes in dissolved inorganic carbon (DIC), pH and alkalinity during phytoplankton bloom development. We tested the model in chemostat experiments with the freshwater cyanobacterium Microcystis aeruginosa at different CO2 levels. The experiments showed that dense blooms sequestered large amounts of atmospheric CO2, not only by their own biomass production but also by inducing a high pH and alkalinity that enhanced the capacity for DIC storage in the system. We used the model to explore how phytoplankton blooms of eutrophic waters will respond to rising CO2 levels. The model predicts that (1) dense phytoplankton blooms in low- and moderately alkaline waters can deplete the dissolved CO2 concentration to limiting levels and raise the pH over a relatively wide range of atmospheric CO2 conditions, (2) rising atmospheric CO2 levels will enhance phytoplankton blooms in low- and moderately alkaline waters with high nutrient loads, and (3) above some threshold, rising atmospheric CO2 will alleviate phytoplankton blooms from carbon limitation, resulting in less intense CO2 depletion and a lesser increase in pH. Sensitivity analysis indicated that the model predictions were qualitatively robust. Quantitatively, the predictions were sensitive to variation in lake depth, DIC input and CO2 gas transfer across the air-water interface, but relatively robust to variation in the carbon uptake mechanisms of phytoplankton. In total, these findings warn that rising CO2 levels may result in a marked intensification of
Spatio-temporal interdependence of bacteria and phytoplankton during a Baltic Sea spring bloom

Directory of Open Access Journals (Sweden)

Carina eBunse

2016-04-01

Full Text Available In temperate systems, phytoplankton spring blooms deplete inorganic nutrients and are major sources of organic matter for the microbial loop. In response to phytoplankton exudates and environmental factors, heterotrophic microbial communities are highly dynamic and change their abundance and composition both on spatial and temporal scales. Yet, most of our understanding about these processes comes from laboratory model organism studies, mesocosm experiments or single temporal transects. Spatial-temporal studies examining interactions of phytoplankton blooms and bacterioplankton community composition and function, though being highly informative, are scarce. In this study, pelagic microbial community dynamics (bacteria and phytoplankton and environmental variables were monitored during a spring bloom across the Baltic Proper (two cruises between North Germany to Gulf of Finland. To test to what extent bacterioplankton community composition relates to the spring bloom, we used next generation amplicon sequencing of the 16S rRNA gene, phytoplankton diversity analysis based on microscopy counts and population genotyping of the dominating diatom Skeletonema marinoi. Several phytoplankton bloom related and environmental variables were identified to influence bacterial community composition. Members of Bacteroidetes and Alphaproteobacteria dominated the bacterial community composition but the bacterial groups showed no apparent correlation with direct bloom related variables. The less abundant bacterial phyla Actinobacteria, Planctomycetes, and Verrucomicrobia, on the other hand, were strongly associated with phytoplankton biomass, diatom:dinoflagellate ratio and colored dissolved organic matter (cDOM. Many bacterial operational taxonomic units (OTUs showed high niche specificities. For example, particular Bacteroidetes OTUs were associated with two distinct genetic clusters of S. marinoi. Our study revealed the complexity of interactions of bacterial
Modelling the production of dimethylsulfide during a phytoplankton bloom

Science.gov (United States)

Gabric, Albert; Murray, Nicholas; Stone, Lewi; Kohl, Manfred

1993-12-01

Dimethylsulfide (DMS) is an important sulfur-containing atmospheric trace gas of marine biogenic origin. DMS emitted from the oceans may be a precursor of tropospheric aerosols and cloud condensation nuclei (CCN), thereby affecting the Earth's radiative balance and possibly constituting a negative feedback to global warming, although this hypothesis is still somewhat controversial. The revised conceptual model of the marine pelagic food web gives a central role to planktonic bacteria. Recent experiments have shown that consumption of dissolved DMS by microbial metabolism may be more important than atmospheric exchange in controlling its concentration in surface waters and hence its ventilation to the atmosphere. In this paper we investigate the effect of the marine food web on cycling of dissolved DMS in surface waters during a phytoplankton bloom episode. A nitrogen-based flow network simulation model has been used to analyze the relative importance of the various biological and chemical processes involved. The model predictions suggest that the concentration of DMS in marine surface waters is indeed governed by bacterial metabolism. Environmental factors that affect the bacterial compartment are thus likely to have a relatively large influence on dissolved DMS concentrations. The ecological succession is particularly sensitive to the ratio of phytoplankton to bacterial nutrient uptake rates as well the interaction between herbivore food chain and the microbial loop. Importantly for the design of field studies, the model predicts that peak DMS concentrations are achieved during the decline of the phytoplankton bloom with a typical time lag between peak DMS and peak phytoplankton biomass of 1 to 2 days. Significantly, the model predicts a relatively high DMS concentration persisting after the phytoplankton bloom due to excretion from large protozoa and zooplankton, which may be an additional explanation for the lack of correlation between DMS and chlorophyll a
Phytoplankton blooms in estuarine and coastal waters: Seasonal patterns and key species

Science.gov (United States)

Carstensen, Jacob; Klais, Riina; Cloern, James E.

2015-01-01

Phytoplankton blooms are dynamic phenomena of great importance to the functioning of estuarine and coastal ecosystems. We analysed a unique (large) collection of phytoplankton monitoring data covering 86 coastal sites distributed over eight regions in North America and Europe, with the aim of investigating common patterns in the seasonal timing and species composition of the blooms. The spring bloom was the most common seasonal pattern across all regions, typically occurring early (February–March) at lower latitudes and later (April–May) at higher latitudes. Bloom frequency, defined as the probability of unusually high biomass, ranged from 5 to 35% between sites and followed no consistent patterns across gradients of latitude, temperature, salinity, water depth, stratification, tidal amplitude or nutrient concentrations. Blooms were mostly dominated by a single species, typically diatoms (58% of the blooms) and dinoflagellates (19%). Diatom-dominated spring blooms were a common feature in most systems, although dinoflagellate spring blooms were also observed in the Baltic Sea. Blooms dominated by chlorophytes and cyanobacteria were only common in low salinity waters and occurred mostly at higher temperatures. Key bloom species across the eight regions included the diatoms Cerataulina pelagica and Dactyliosolen fragilissimus and dinoflagellates Heterocapsa triquetra and Prorocentrum cordatum. Other frequent bloom-forming taxa were diatom genera Chaetoceros, Coscinodiscus, Skeletonema, and Thalassiosira. Our meta-analysis shows that these 86 estuarine-coastal sites function as diatom-producing systems, the timing of that production varies widely, and that bloom frequency is not associated with environmental factors measured in monitoring programs. We end with a perspective on the limitations of conclusions derived from meta-analyses of phytoplankton time series, and the grand challenges remaining to understand the wide range of bloom patterns and
Host-Specificity and Dynamics in Bacterial Communities Associated with Bloom-Forming Freshwater Phytoplankton

Science.gov (United States)

Bagatini, Inessa Lacativa; Eiler, Alexander; Bertilsson, Stefan; Klaveness, Dag; Tessarolli, Letícia Piton; Vieira, Armando Augusto Henriques

2014-01-01

Many freshwater phytoplankton species have the potential to form transient nuisance blooms that affect water quality and other aquatic biota. Heterotrophic bacteria can influence such blooms via nutrient regeneration but also via antagonism and other biotic interactions. We studied the composition of bacterial communities associated with three bloom-forming freshwater phytoplankton species, the diatom Aulacoseira granulata and the cyanobacteria Microcystis aeruginosa and Cylindrospermopsis raciborskii. Experimental cultures incubated with and without lake bacteria were sampled in three different growth phases and bacterial community composition was assessed by 454-Pyrosequencing of 16S rRNA gene amplicons. Betaproteobacteria were dominant in all cultures inoculated with lake bacteria, but decreased during the experiment. In contrast, Alphaproteobacteria, which made up the second most abundant class of bacteria, increased overall during the course of the experiment. Other bacterial classes responded in contrasting ways to the experimental incubations causing significantly different bacterial communities to develop in response to host phytoplankton species, growth phase and between attached and free-living fractions. Differences in bacterial community composition between cyanobacteria and diatom cultures were greater than between the two cyanobacteria. Despite the significance, major differences between phytoplankton cultures were in the proportion of the OTUs rather than in the absence or presence of specific taxa. Different phytoplankton species favoring different bacterial communities may have important consequences for the fate of organic matter in systems where these bloom forming species occur. The dynamics and development of transient blooms may also be affected as bacterial communities seem to influence phytoplankton species growth in contrasting ways. PMID:24465807
Under Sea Ice phytoplankton bloom detection and contamination in Antarctica

Science.gov (United States)

Zeng, C.; Zeng, T.; Xu, H.

2017-12-01

Previous researches reported compelling sea ice phytoplankton bloom in Arctic, while seldom reports studied about Antarctic. Here, lab experiment showed sea ice increased the visible light albedo of the water leaving radiance. Even a new formed sea ice of 10cm thickness increased water leaving radiance up to 4 times of its original bare water. Given that phytoplankton preferred growing and accumulating under the sea ice with thickness of 10cm-1m, our results showed that the changing rate of OC4 estimated [Chl-a] varied from 0.01-0.5mg/m3 to 0.2-0.3mg/m3, if the water covered by 10cm sea ice. Going further, varying thickness of sea ice modulated the changing rate of estimating [Chl-a] non-linearly, thus current routine OC4 model cannot estimate under sea ice [Chl-a] appropriately. Besides, marginal sea ice zone has a large amount of mixture regions containing sea ice, water and snow, where is favorable for phytoplankton. We applied 6S model to estimate the sea ice/snow contamination on sub-pixel water leaving radiance of 4.25km spatial resolution ocean color products. Results showed that sea ice/snow scale effectiveness overestimated [Chl-a] concentration based on routine band ratio OC4 model, which contamination increased with the rising fraction of sea ice/snow within one pixel. Finally, we analyzed the under sea ice bloom in Antarctica based on the [Chl-a] concentration trends during 21 days after sea ice retreating. Regardless of those overestimation caused by sea ice/snow sub scale contamination, we still did not see significant under sea ice blooms in Antarctica in 2012-2017 compared with Arctic. This research found that Southern Ocean is not favorable for under sea ice blooms and the phytoplankton bloom preferred to occur in at least 3 weeks after sea ice retreating.
Comment on "Does the fall phytoplankton blooom control recruitment of Georges Bank, haddock, Melanogrammus aeglefinus, through parental condition?"

DEFF Research Database (Denmark)

Payne, Mark; Dickey-Collas, Mark; Nash, Richard D.M.

2009-01-01

In the paper "Does the fall phytoplankton bloom control recruitment of Georges Bank haddock, Melanogrammus aeglefinus, through parental condition?", Friedland et al. (Can. J. Fish. Aquat. Sci. 65(6): 1076-1086, 2008) examine a sizable number of hypotheses aiming to explain the recruitment patterns...... observed in Georges Bank haddock. The authors focus on a correlation between the size of the autumnal phytoplankton bloom and the survivor ratio (recruitment), concluding this to be the main factor determining recruitment, via the mechanism of adult condition at the time of spawning. Here we examine......, and that in performing the analysis in the chosen manner, Friedland et al. have overlooked alternative hypotheses....
Parameter constraints of grazing response functions. Implications for phytoplankton bloom initiation

Directory of Open Access Journals (Sweden)

Jordi Solé

2016-09-01

Full Text Available Phytoplankton blooms are events of production and accumulation of phytoplankton biomass that influence ecosystem dynamics and may also have effects on socio-economic activities. Among the biological factors that affect bloom dynamics, prey selection by zooplankton may play an important role. Here we consider the initial state of development of an algal bloom and analyse how a reduced grazing pressure can allow an algal species with a lower intrinsic growth rate than a competitor to become dominant. We use a simple model with two microalgal species and one zooplankton grazer to derive general relationships between phytoplankton growth and zooplankton grazing. These relationships are applied to two common grazing response functions in order to deduce the mathematical constraints that the parameters of these functions must obey to allow the dominance of the lower growth rate competitor. To assess the usefulness of the deduced relationships in a more general framework, the results are applied in the context of a multispecies ecosystem model (ERSEM.
Increasing phytoplankton-available phosphorus and inhibition of macrophyte on phytoplankton bloom.

Science.gov (United States)

Dai, Yanran; Wu, Juan; Ma, Xiaohang; Zhong, Fei; Cui, Naxin; Cheng, Shuiping

2017-02-01

We assembled mesocosms to address the coherent mechanisms that an increasing phosphorus (P) concentration in water columns coupled with the phytoplankton bloom and identify the performance gap of regulating phytoplankton growth between two macrophyte species, Ceratophyllum demersum L. and Vallisneria spiralis L. Intense alkaline phosphatase activities (APA) were observed in the unplanted control, with their predominant part, phytoplankton APA (accounting for up to 44.7% of the total APA), and another large share, bacterial APA. These correspond with the large average concentration of total phosphorus (TP), total dissolved phosphorus (TDP) and soluble reactive (SRP) as well as high phytoplankton density in the water column. The consistency among P concentrations, phytoplankton density and APA, together with the positive impact of phytoplankton density on total APA revealed by the structural equation modelling (SEM), indicates that facilitated APA levels in water is an essential strategy for phytoplankton to enhance the available P. Furthermore, a positive interaction between phytoplankton APA and bacteria APA was detected, suggesting a potential collaboration between phytoplankton and bacteria to boost available P content in the water column. Both macrophyte species had a prominent performance on regulating phytoplankton proliferation. The phytoplankton density and quantum yield in C. demersum systems were all significantly lower (33.8% and 24.0%) than those in V. spiralis systems. Additionally, a greater decoupling effect of C. demersum on the relationship between P, APA, phytoplankton density, bacteria dynamic and quantum yield was revealed by SEM. These results imply that the preferred tactic of different species could lead to the performance gap. Copyright © 2016 Elsevier B.V. All rights reserved.
The development and decline of phytoplankton blooms in the southern Benguela upwelling region

International Nuclear Information System (INIS)

Brown, P.C.

1986-10-01

Productivity/chlorophyll a relationship are investigated with a view to estimating phytoplankton productivity from extensive chlorophyll a measurements in the southern Benguela region. Phytoplankton bloom dynamics in newly upwelled water off the Cape Peninsula are investigated on five different occasions during the upwelling season. A drogue was used to tag a 'parcel' of upwelled water which was monitored for between 4 and 8 days. In upwelling source water, mean chlorophyll a concentrations were typically low (0.7 mg.m -3 ) and nutrient concentrations were high (nitrates, silicates and phosphates were 20.8, 16.6 and 1.88 mmol.m -3 respectively). Along the drogue tracks nutrients decreased rapidly in the euphotic zone as chlorophyll increased to peak at concentrations of up to 26 mg.m -3 . Elemental changes in nitrates, silicates, phosphates and oxygen were used to estimate primary productivity. These 'Redfield productivity estimates' were similar to 14 C-uptake productivity but lower than estimates obtained from changes in particle volume. Daily rates of 14 C-uptake water column productivity ranged between 0.94 and 14.01 g C.m -2 .d -1 (mean 3.80 g C.m -2 .d -1 ) and were similar to or higher than productivity estimates reported for other upwelling areas. Phytoplankton biomass in the upper 50 metres ranged between 8 and 506 mg chll a. m -2 (mean 208 mg chll a.m -2 ). The temporal scale of phytoplankton bloom development was investigated in terms of changes in chlorophyll a concentrations in the euphotic zone. The build up and decline of the primary phytoplankton (diatom) bloom in newly upwelled water occurred within 6-8 days. The initiation of blooming was controlled by the stability of the water body. The decline of the bloom was associated with reduced nutrient levels and is considered to result mainly from phytoplankton cells sinking out of the surface layers
Factors controlling the development of phytoplankton blooms in the Antarctic Ocean

International Nuclear Information System (INIS)

Sakshaug, Egil; Holm-Hansen, Osmund

1991-01-01

A mathematical model describing the development of phytoplankton blooms as a function of the depth of the wind-mixed layer, spectral distribution of light, passage of atmospheric low-pressure systems, size of the initial phytoplankton stock and loss rates is presented. Model runs represent shade-adapted, large-celled, bloom-forming diatoms Periodic deep mixing caused by strong winds may severely retard the development of blooms and frequently abort them before macronutrients are completely exhausted. Moderate depths of mixing (40-50 m) in combination with a moderately large total loss rate (about 0.013h -1 ) can prevent blooms from developing during the brightest time of the year. Complete exhaustion of macronutrients in the upper waters is likely only if the wind-mixed layer is less than 10 m deep, i.e. in very sheltered waters, and also in the marginal ice zone when ice is melting. The authors do not exclude the possibility of control of phytoplankton biomass by iron in ice-free, deep-sea parts of the Antarctic Ocean, but the implied enhancement of export production through addition of iron might be restricted because of limitation by light, i.e. vertical mixing. (author). 32 ref.; 5 figs.; 2 tabs

Shallow water processes govern system-wide phytoplankton bloom dynamics: A modeling study

Science.gov (United States)

Lucas, L.V.; Koseff, Jeffrey R.; Monismith, Stephen G.; Thompson, J.K.

2009-01-01

A pseudo-two-dimensional numerical model of estuarine phytoplankton growth and consumption, vertical turbulent mixing, and idealized cross-estuary transport was developed and applied to South San Francisco Bay. This estuary has two bathymetrically distinct habitat types (deep channel, shallow shoal) and associated differences in local net rates of phytoplankton growth and consumption, as well as differences in the water column's tendency to stratify. Because many physical and biological time scales relevant to algal population dynamics decrease with decreasing depth, process rates can be especially fast in the shallow water. We used the model to explore the potential significance of hydrodynamic connectivity between a channel and shoal and whether lateral transport can allow physical or biological processes (e.g. stratification, benthic grazing, light attenuation) in one sub-region to control phytoplankton biomass and bloom development in the adjacent sub-region. Model results for South San Francisco Bay suggest that lateral transport from a productive shoal can result in phytoplankton biomass accumulation in an adjacent deep, unproductive channel. The model further suggests that turbidity and benthic grazing in the shoal can control the occurrence of a bloom system-wide; whereas, turbidity, benthic grazing, and vertical density stratification in the channel are likely to only control local bloom occurrence or modify system-wide bloom magnitude. Measurements from a related field program are generally consistent with model-derived conclusions. ?? 2008 Elsevier B.V.
Identification of Phytoplankton Blooms under the Index of Inherent Optical Properties (IOP Index in Optically Complex Waters

Directory of Open Access Journals (Sweden)

Jesús A. Aguilar-Maldonado

2018-01-01

Full Text Available Phytoplankton blooms are sporadic events in time and are isolated in space. This complex phenomenon is produced by a variety of both natural and anthropogenic causes. Early detection of this phenomenon, as well as the classification of a water body under conditions of bloom or non-bloom, remains an unresolved problem. This research proposes the use of Inherent Optical Properties (IOPs in optically complex waters to detect the bloom or non-bloom state of the phytoplankton community. An IOP index is calculated from the absorption coefficients of the colored dissolved organic matter (CDOM, the phytoplankton (phy and the detritus (d, using the wavelength (λ 443 nm. The effectiveness of this index is tested in five bloom events in different places and with different characteristics from Mexican seas: 1. Dzilam (Caribbean Sea, Atlantic Ocean, a diatom bloom (Rhizosolenia hebetata; 2. Holbox (Caribbean Sea, Atlantic Ocean, a mixed bloom of dinoflagellates (Scrippsiella sp. and diatoms (Chaetoceros sp.; 3. Campeche Bay in the Gulf of Mexico (Atlantic Ocean, a bloom of dinoflagellates (Karenia brevis; 4. Upper Gulf of California (UGC (Pacific Ocean, a diatom bloom (Coscinodiscus and Pseudo-nitzschia and 5. Todos Santos Bay, Ensenada (Pacific Ocean, a dinoflagellate bloom (Lingulodinium polyedrum. The diversity of sites show that the IOP index is a suitable method to determine the phytoplankton bloom conditions.
Bacterial and protist community changes during a phytoplankton bloom

KAUST Repository

Pearman, John K.

2015-10-01

The present study aims to characterize the change in the composition and structure of the bacterial and microzooplankton planktonic communities in relation to the phytoplankton community composition during a bloom. High-throughput amplicon sequencing of regions of the 16S and 18S rRNA gene was undertaken on samples collected during a 20 day (d) mesocosm experiment incorporating two different nutrient addition treatments [Nitrate and Phosphate (NPc) and Nitrate, Phosphate and Silicate (NPSc)] as well as a control. This approach allowed us to discriminate the changes in species composition across a broad range of phylogenetic groups using a common taxonomic level. Diatoms dominated the bloom in the NPSc treatment while dinoflagellates were the dominant phytoplankton in the control and NPc treatment. Network correlations highlighted significant interactions between OTUs within each treatment including changes in the composition of Paraphysomonas OTUs when the dominant Chaetoceros OTU switched. The microzooplankton community composition responded to changes in the phytoplankton composition while the prokaryotic community responded more to changes in ammonia concentration.
A major seasonal phytoplankton bloom in the Madagascar Basin

Science.gov (United States)

Longhurst, Alan

2001-11-01

A hitherto-unnoticed phytoplankton bloom, of dimension 3000×1500 km, occupies the Madagascar Basin in late austral summer, being a prominent feature in SeaWiFS images. A first-order interpretation of the bloom mechanism invokes the seasonal deepening of the mixed layer within a strong mesoscale eddy-field and the consequent entrainment of nutrients into the photic zone. Features of the bloom correspond closely and appropriately with features of the eddy-field as observed by TOPEX-POSEIDON sea level anomalies. The bloom failed to develop in 1998, the second year of a two-year ENSO episode, when anomalously weak Southeast Trades will have failed to deepen the mixed layer as in other years.
Distribution and recurrence of phytoplankton blooms around South Georgia, Southern Ocean

Directory of Open Access Journals (Sweden)

I. Borrione

2013-01-01

Full Text Available South Georgia phytoplankton blooms are amongst the largest of the Southern Ocean and are associated with a rich ecosystem and strong atmospheric carbon drawdown. Both aspects depend on the intensity of blooms, but also on their regularity. Here we use data from 12 yr of SeaWiFS (Sea-viewing Wide Field-of-view Sensor ocean colour imagery and calculate the frequency of bloom occurrence (FBO to re-examine spatial and temporal bloom distributions. We find that upstream of the island and outside the borders of the Georgia Basin, blooms occurred in less than 4 out of the 12 yr (FBO < 4. In contrast, FBO was mostly greater than 8 downstream of the island, i.e., to the north and northwest, and in places equal to 12, indicating that blooms occurred every year. The typical bloom area, defined as the region where blooms occurred in at least 8 out of the 12 yr, covers the entire Georgia Basin and the northern shelf of the island. The time series of surface chlorophyll a (Chl a concentrations averaged over the typical bloom area shows that phytoplankton blooms occurred in every year between September 1997 and September 2010, and that Chl a values followed a clear seasonal cycle, with concentration peaks around December followed in many years by a second peak during late austral summer or early autumn, suggesting a bi-modal bloom pattern. The bloom regularity we describe here is in contrast with results of Park et al. (2010 who used a significantly different study area including regions that almost never exhibit bloom conditions.
Margalef's mandala and phytoplankton bloom strategies

Science.gov (United States)

Wyatt, Timothy

2014-03-01

Margalef's mandala maps phytoplankton species into a phase space defined by turbulence (A) and nutrient concentrations (Ni); these are the hard axes. The permutations of high and low A and high and low Ni divide the space into four domains. Soft axes indicate some ecological dynamics. A main sequence shows the normal course of phytoplankton succession; the r-K axis of MacArthur and Wilson runs parallel to it. An alternative successional sequence leads to the low A-high Ni domain into which many red tide species are mapped. Astronomical and biological time are implicit. A mathematical transformation of the mandala (rotation) links it to the classical bloom models of Sverdrup (time) and Kierstead and Slobodkin (space). Both rarity and the propensity to form red tides are considered to be species characters, meaning that maximum population abundance can be a target of natural selection. Equally, both the unpredictable appearance of bloom species and their short-lived appearances may be species characters. There may be a correlation too between these features and long-lived dormant stages in the life-cycle; then the vegetative planktonic phase is the 'weak link' in the life-cycle. Red tides are thus due to species which have evolved suites of traits which result in specific demographic strategies.
The plankton community on Sukkertop and Fylla Banks off West Greenland during a spring bloom and post-bloom period: Hydrography, phytoplankton and protozooplankton

DEFF Research Database (Denmark)

Poulsen, Louise K.; Reuss, N.

2002-01-01

The plankton community structure was investigated on Sukkertop and Fylla Banks off West Greenland during the spring bloom in May 2000 and the post-bloom period in June 1999. In May a small change in density, clearly illustrated by the profile of potential energy, was sufficient to support a spring...... the phytoplankton community. Heterotrophic biomass was low (5 +/- 1 mg C m(-3)) and an important part was comprised by heterotrophic nanoflagellates (24 +/- 1%). Protozooplankters (heterotrophic dinoflagellates and ciliates) were important grazers of the phytoplankton community in the post-bloom period (estimated...
Under-Ice Phytoplankton Blooms Inhibited by Spring Convective Mixing in Refreezing Leads

Science.gov (United States)

Lowry, Kate E.; Pickart, Robert S.; Selz, Virginia; Mills, Matthew M.; Pacini, Astrid; Lewis, Kate M.; Joy-Warren, Hannah L.; Nobre, Carolina; van Dijken, Gert L.; Grondin, Pierre-Luc; Ferland, Joannie; Arrigo, Kevin R.

2018-01-01

Spring phytoplankton growth in polar marine ecosystems is limited by light availability beneath ice-covered waters, particularly early in the season prior to snowmelt and melt pond formation. Leads of open water increase light transmission to the ice-covered ocean and are sites of air-sea exchange. We explore the role of leads in controlling phytoplankton bloom dynamics within the sea ice zone of the Arctic Ocean. Data are presented from spring measurements in the Chukchi Sea during the Study of Under-ice Blooms In the Chukchi Ecosystem (SUBICE) program in May and June 2014. We observed that fully consolidated sea ice supported modest under-ice blooms, while waters beneath sea ice with leads had significantly lower phytoplankton biomass, despite high nutrient availability. Through an analysis of hydrographic and biological properties, we attribute this counterintuitive finding to springtime convective mixing in refreezing leads of open water. Our results demonstrate that waters beneath loosely consolidated sea ice (84-95% ice concentration) had weak stratification and were frequently mixed below the critical depth (the depth at which depth-integrated production balances depth-integrated respiration). These findings are supported by theoretical model calculations of under-ice light, primary production, and critical depth at varied lead fractions. The model demonstrates that under-ice blooms can form even beneath snow-covered sea ice in the absence of mixing but not in more deeply mixed waters beneath sea ice with refreezing leads. Future estimates of primary production should account for these phytoplankton dynamics in ice-covered waters.
Phytoplankton bloom and subpolar gyre induced dynamics in the North Atlantic

DEFF Research Database (Denmark)

Ferreira, Ana Sofia; Hátún, H.; Counillon, F.

Several hypotheses have been promoted for phytoplankton bloom onset in the North Atlantic. First we show that the bloom dynamics in the northeastern corner stand out from the rest of the subpolar Atlantic, and thus warrants focused attention. We hypothesized that, for this region, late and weak...... blooms are expected in years of a strong subpolar gyre, i.e. strong atmospheric forcing, and cold and low saline conditions. We apply novel phenology algorithms to satellite ocean colour data, and analyse the outcome together with the subpolar gyre index. We find that the relationship between the bloom...
Seasonal phytoplankton blooms in the Gulf of Aden revealed by remote sensing

KAUST Repository

Gittings, John

2016-11-25

The Gulf of Aden, situated in the northwest Arabian Sea and linked to the Red Sea, is a relatively unexplored ecosystem. Understanding of large-scale biological dynamics is limited by the lack of adequate datasets. In this study, we analyse 15 years of remotely-sensed chlorophyll-a data (Chl-a, an index of phytoplankton biomass) acquired from the Ocean Colour Climate Change Initiative (OC-CCI) of the European Space Agency (ESA). The improved spatial coverage of OC-CCI data in the Gulf of Aden allows, for the first time, an investigation into the full seasonal succession of phytoplankton biomass. Analysis of indices of phytoplankton phenology (bloom timing) reveals distinct phytoplankton growth periods in different parts of the gulf: a large peak during August (mid-summer) in the western part of the gulf, and a smaller peak during November (mid-autumn) in the lower central gulf and along the southern coastline. The summer bloom develops rapidly at the beginning of July, and its peak is approximately three times higher than that of the autumnal bloom. Remotely-sensed sea-surface temperature (SST), wind-stress curl, vertical nutrient profiles and geostrophic currents inferred from the sea-level anomaly, were analysed to examine the underlying physical mechanisms that control phytoplankton growth. During summer, the prevailing southwesterlies cause upwelling along the northern coastline of the gulf (Yemen), leading to an increase in nutrient availability and enhancing phytoplankton growth along the coastline and in the western part of the gulf. In contrast, in the central region of the gulf, lowest concentrations of Chl-a are observed during summer, due to strong downwelling caused by a mesoscale anticyclonic eddy. During autumn, the prevailing northeasterlies enable upwelling along the southern coastline (Somalia) causing local nutrient enrichment in the euphotic zone, leading to higher levels of phytoplankton biomass along the coastline and in the lower central gulf
Mesoscale Eddies Control the Timing of Spring Phytoplankton Blooms: A Case Study in the Japan Sea

Science.gov (United States)

Maúre, E. R.; Ishizaka, J.; Sukigara, C.; Mino, Y.; Aiki, H.; Matsuno, T.; Tomita, H.; Goes, J. I.; Gomes, H. R.

2017-11-01

Satellite Chlorophyll a (CHL) data were used to investigate the influence of mesoscale anticyclonic eddies (AEs) and cyclonic eddies (CEs) on the timing of spring phytoplankton bloom initiation around the Yamato Basin (133-139°E and 35-39.5°N) in the Japan Sea, for the period 2002-2011. The results showed significant differences between AEs and CEs in the timing and initiation mechanism of the spring phytoplankton bloom. Blooms were initiated earlier in CEs which were characterized by shallow mixed-layer depths (mixed-layer depth. Conversely, blooms appeared in the AEs despite deeper mixed-layer depth (> 100 m) but close to the commencement of positive Q0. This suggests that the relaxation of turbulent mixing is crucial for the bloom initiation in AEs.
Rapid bacterial mineralization of organic carbon produced during a phytoplankton bloom induced by natural iron fertilization in the Southern Ocean

Science.gov (United States)

Obernosterer, Ingrid; Christaki, Urania; Lefèvre, Dominique; Catala, Philippe; Van Wambeke, France; Lebaron, Philippe

2008-03-01

The response of heterotrophic bacteria ( Bacteria and Archaea) to the spring phytoplankton bloom that occurs annually above the Kerguelen Plateau (Southern Ocean) due to natural iron fertilization was investigated during the KErguelen Ocean and Plateau compared Study (KEOPS) cruise in January-February 2005. In surface waters (upper 100 m) in the core of the phytoplankton bloom, heterotrophic bacteria were, on an average, 3-fold more abundant and revealed rates of production ([ 3H] leucine incorporation) and respiration (bacterial metabolic activities were attributable to high-nucleic-acid-containing cells that dominated (≈80% of total cell abundance) the heterotrophic bacterial community associated with the phytoplankton bloom. Bacterial growth efficiencies varied between 14% and 20% inside the bloom and were bacterial activity, due to the stimulation by phytoplankton-derived dissolved organic matter. Within the Kerguelen bloom, bacterial carbon demand accounted for roughly 45% of gross community production. These results indicate that heterotrophic bacteria processed a significant portion of primary production, with most of it being rapidly respired.
Variability in the mechanisms controlling Southern Ocean phytoplankton bloom phenology in an ocean model and satellite observations

Science.gov (United States)

Rohr, Tyler; Long, Matthew C.; Kavanaugh, Maria T.; Lindsay, Keith; Doney, Scott C.

2017-05-01

A coupled global numerical simulation (conducted with the Community Earth System Model) is used in conjunction with satellite remote sensing observations to examine the role of top-down (grazing pressure) and bottom-up (light, nutrients) controls on marine phytoplankton bloom dynamics in the Southern Ocean. Phytoplankton seasonal phenology is evaluated in the context of the recently proposed "disturbance-recovery" hypothesis relative to more traditional, exclusively "bottom-up" frameworks. All blooms occur when phytoplankton division rates exceed loss rates to permit sustained net population growth; however, the nature of this decoupling period varies regionally in Community Earth System Model. Regional case studies illustrate how unique pathways allow blooms to emerge despite very poor division rates or very strong grazing rates. In the Subantarctic, southeast Pacific small spring blooms initiate early cooccurring with deep mixing and low division rates, consistent with the disturbance-recovery hypothesis. Similar systematics are present in the Subantarctic, southwest Atlantic during the spring but are eclipsed by a subsequent, larger summer bloom that is coincident with shallow mixing and the annual maximum in division rates, consistent with a bottom-up, light limited framework. In the model simulation, increased iron stress prevents a similar summer bloom in the southeast Pacific. In the simulated Antarctic zone (70°S-65°S) seasonal sea ice acts as a dominant phytoplankton-zooplankton decoupling agent, triggering a delayed but substantial bloom as ice recedes. Satellite ocean color remote sensing and ocean physical reanalysis products do not precisely match model-predicted phenology, but observed patterns do indicate regional variability in mechanism across the Atlantic and Pacific.
Satellite Evidence that E. huxleyi Phytoplankton Blooms Weaken Marine Carbon Sinks

Science.gov (United States)

Kondrik, D. V.; Pozdnyakov, D. V.; Johannessen, O. M.

2018-01-01

Phytoplankton blooms of the coccolithophore Emiliania huxleyi are known to produce CO2, causing less uptake of atmospheric CO2 by the ocean, but a global assessment of this phenomenon has so far not been quantified. Therefore, here we quantify the increase in CO2 partial pressure (ΔpCO2) at the ocean surface within E. huxleyi blooms for polar and subpolar seas using an 18 year ocean color time series (1998-2015). When normalized to pCO2 in the absence of bloom, the mean and maximum ΔpCO2 values within the bloom areas varied between 21.0%-43.3% and 31.6%-62.5%, respectively. These results might have appreciable implications for climatology, marine chemistry, and ecology.
Heterotrophic bacterial responses to the winter–spring phytoplankton bloom in open waters of the NW Mediterranean

KAUST Repository

Gomes, Ana

2014-12-03

The response of planktonic heterotrophic prokaryotes to the NW Mediterranean winter–spring offshore phytoplankton bloom was assessed in 3 cruises conducted in March, April–May and September 2009. Bulk measurements of phytoplankton and bacterioplankton biomass and production were complemented with an insight into bacterial physiological structure by single-cell analysis of nucleic acid content [low (LNA) vs. high (HNA)] and membrane integrity (“Live” vs. “Dead” cells). Bacterial production empirical conversion factors (0.82±0.25 SE kg C mol leucine−1) were almost always well below the theoretical value. Major differences in most microbial variables were found among the 3 periods, which varied from extremely high phytoplankton biomass and production during the bloom in March (>1 g C m−2 d−1 primary production) to typically oligotrophic conditions during September stratification (<200 mg C m−2 d−1). In both these periods bacterial production was ~30 mg C m−2 d−1 while very large bacterial production (mean 228, with some stations exceeding 500 mg C m−2 d−1) but low biomass was observed during the April–May post-bloom phase. The contribution of HNA (30–67%) and “Live” cells (47–97%) were temporally opposite in the study periods, with maxima in March and September, respectively. Different relationships were found between physiological structure and bottom-up variables, with HNA bacteria apparently more responsive to phytoplankton only during the bloom, coinciding with larger average cell sizes of LNA bacteria. Moderate phytoplankton–bacterioplankton coupling of biomass and activity was only observed in the bloom and post-bloom phases, while relationships between both compartments were not significant under stratification. With all data pooled, bacteria were only weakly bottom-up controlled. Our analyses show that the biomass and production of planktonic algae and bacteria followed opposite paths in the transition from bloom to
Phytoplankton ice-edge blooms in the marginal ice zone at Princess Astrid Coast in Antarctica

Digital Repository Service at National Institute of Oceanography (India)

Verlecar, X.N.; Dhargalkar, V.K.; Goswami, S.C.; Mhamal, N.P.

dominated the bloom conditions and nannoplankton (5 to 20 mu m) prevail the non-bloom periods while the picoplankton (less than 5 mu m) constituted a minor fraction during most of the period. Weekly changes in phytoplankton showed inverse relationship...
Effects of increase glacier discharge on phytoplankton bloom dynamics and pelagic geochemistry in a high Arctic fjord

Science.gov (United States)

Calleja, Maria Ll.; Kerhervé, P.; Bourgeois, S.; Kędra, M.; Leynaert, A.; Devred, E.; Babin, M.; Morata, N.

2017-12-01

Arctic fjords experience extremely pronounced seasonal variability and spatial heterogeneity associated with changes in ice cover, glacial retreat and the intrusion of continental shelf's adjacent water masses. Global warming intensifies natural environmental variability on these important systems, yet the regional and global effects of these processes are still poorly understood. In the present study, we examine seasonal and spatial variability in Kongsfjorden, on the western coast of Spitsbergen, Svalbard. We report hydrological, biological, and biogeochemical data collected during spring, summer, and fall 2012. Our results show a strong phytoplankton bloom with the highest chlorophyll a (Chla) levels ever reported in this area, peaking 15.5 μg/L during late May and completely dominated by large diatoms at the inner fjord, that may sustain both pelagic and benthic production under weakly stratified conditions at the glacier front. A progressively stronger stratification of the water column during summer and fall was shaped by the intrusion of warm Atlantic water (T > 3 °C and Sal > 34.65) into the fjord at around 100 m depth, and by turbid freshwater plumes (T carbon fractions and isotopic signatures of the particulate organic material (POM) revealed very fresh and labile material produced during the spring bloom (13C enriched, with values up to -22.7‰ at the highest Chl a peak, and high in carbohydrates and proteins content - up to 167 and 148 μg/L, respectively-), and a clear and strong continental signature of the POM present during late summer and fall (13C depleted, with values averaging -26.5‰, and high in lipid content - up to 92 μg/L-) when freshwater melting is accentuated. Our data evidence the importance of combining both physical (i.e. water mass dominance) and geochemical (i.e. characteristics of material released by glacier runoff) data in order to understand the timing, intensity and characteristics of the phytoplankton bloom in
Aggregation and sedimentation processes during a spring phytoplankton bloom: A field experiment to test coagulation theory

DEFF Research Database (Denmark)

Kiørboe, Thomas; Lundsgaard, Claus; Olesen, Michael

1994-01-01

Spring diatom blooms in temperate waters are often terminated by aggregation of the cells into large floes and subsequent mass sedimentation of the phytoplankton to the sea floor. The rate of aggregate formation by physical coagulation depends on the concentration of suspended particles, on the t......Spring diatom blooms in temperate waters are often terminated by aggregation of the cells into large floes and subsequent mass sedimentation of the phytoplankton to the sea floor. The rate of aggregate formation by physical coagulation depends on the concentration of suspended particles...
Emergence of Algal Blooms: The Effects of Short-Term Variability in Water Quality on Phytoplankton Abundance, Diversity, and Community Composition in a Tidal Estuary

Directory of Open Access Journals (Sweden)

Todd A. Egerton

2014-01-01

Full Text Available Algal blooms are dynamic phenomena, often attributed to environmental parameters that vary on short timescales (e.g., hours to days. Phytoplankton monitoring programs are largely designed to examine long-term trends and interannual variability. In order to better understand and evaluate the relationships between water quality variables and the genesis of algal blooms, daily samples were collected over a 34 day period in the eutrophic Lafayette River, a tidal tributary within Chesapeake Bay’s estuarine complex, during spring 2006. During this period two distinct algal blooms occurred; the first was a cryptomonad bloom and this was followed by a bloom of the mixotrophic dinoflagellate, Gymnodinium instriatum. Chlorophyll a, nutrient concentrations, and physical and chemical parameters were measured daily along with phytoplankton abundance and community composition. While 65 phytoplankton species from eight major taxonomic groups were identified in samples and total micro- and nano-phytoplankton cell densities ranged from 5.8 × 106 to 7.8 × 107 cells L−1, during blooms, cryptomonads and G. instriatum were 91.6% and 99.0%, respectively, of the total phytoplankton biomass during blooms. The cryptomonad bloom developed following a period of rainfall and concomitant increases in inorganic nitrogen concentrations. Nitrate, nitrite and ammonium concentrations 0 to 5 days prior were positively lag-correlated with cryptomonad abundance. In contrast, the G. insriatum bloom developed during periods of low dissolved nitrogen concentrations and their abundance was negatively correlated with inorganic nitrogen concentrations.
Identification of non-indigenous phytoplankton species dominated bloom off Goa using inverted microscopy and pigment (HPLC) analysis

Digital Repository Service at National Institute of Oceanography (India)

Bhaskar, P.V.; Roy, R.; Gauns, M.; Shenoy, D.M.; Rao, V.D.; Mochemadkar, S.

site and sampling The mixed phytoplankton bloom was observed during one of the monthly sampling at the Can- dolim time series (CaTS) transect (figure 1) in the near-shore waters oﬀ Goa, west coast of India. Sea- water was sampled on two days (27 and 29... January, Figure 1. Map showing the CaTS (Candolim time-series) stations G1 to G5 and one station oﬀ Morjim north of CaTS. The approximate spread of the bloom is indicated by the shaded portion. Identification of non-indigenous phytoplankton oﬀ Goa 1147...

Effects of increase glacier discharge on phytoplankton bloom dynamics and pelagic geochemistry in a high Arctic fjord

KAUST Repository

Calleja, Maria Ll.; Kerhervé , P.; Bourgeois, S.; Kędra, M.; Leynaert, A.; Devred, E.; Babin, M.; Morata, N.

2017-01-01

Arctic fjords experience extremely pronounced seasonal variability and spatial heterogeneity associated with changes in ice cover, glacial retreat and the intrusion of continental shelf’s adjacent water masses. Global warming intensifies natural environmental variability on these important systems, yet the regional and global effects of these processes are still poorly understood. In the present study, we examine seasonal and spatial variability in Kongsfjorden, on the western coast of Spitsbergen, Svalbard. We report hydrological, biological, and biogeochemical data collected during spring, summer, and fall 2012. Our results show a strong phytoplankton bloom with the highest chlorophyll a (Chla) levels ever reported in this area, peaking 15.5 µg/L during late May and completely dominated by large diatoms at the inner fjord, that may sustain both pelagic and benthic production under weakly stratified conditions at the glacier front. A progressively stronger stratification of the water column during summer and fall was shaped by the intrusion of warm Atlantic water (T > 3°C and Sal > 34.65) into the fjord at around 100 m depth, and by turbid freshwater plumes (T < 1°C and Sal < 34.65) at the surface due to glacier meltwater input. Biopolymeric carbon fractions and isotopic signatures of the particulate organic material (POM) revealed very fresh and labile material produced during the spring bloom (13C enriched, with values up to -22.7‰ at the highest Chl a peak, and high in carbohydrates and proteins content -up to 167 and 148 µg/L, respectively-), and a clear and strong continental signature of the POM present during late summer and fall (13C depleted, with values averaging -26.5 ‰, and high in lipid content –up to 92 µg/L-) when freshwater melting is accentuated. Our data evidence the importance of combining both physical (i.e. water mass dominance) and geochemical (i.e. characteristics of material released by glacier runoff) data in order to
Effects of increase glacier discharge on phytoplankton bloom dynamics and pelagic geochemistry in a high Arctic fjord

KAUST Repository

Calleja, Maria Ll.

2017-07-26

Arctic fjords experience extremely pronounced seasonal variability and spatial heterogeneity associated with changes in ice cover, glacial retreat and the intrusion of continental shelf’s adjacent water masses. Global warming intensifies natural environmental variability on these important systems, yet the regional and global effects of these processes are still poorly understood. In the present study, we examine seasonal and spatial variability in Kongsfjorden, on the western coast of Spitsbergen, Svalbard. We report hydrological, biological, and biogeochemical data collected during spring, summer, and fall 2012. Our results show a strong phytoplankton bloom with the highest chlorophyll a (Chla) levels ever reported in this area, peaking 15.5 µg/L during late May and completely dominated by large diatoms at the inner fjord, that may sustain both pelagic and benthic production under weakly stratified conditions at the glacier front. A progressively stronger stratification of the water column during summer and fall was shaped by the intrusion of warm Atlantic water (T > 3°C and Sal > 34.65) into the fjord at around 100 m depth, and by turbid freshwater plumes (T < 1°C and Sal < 34.65) at the surface due to glacier meltwater input. Biopolymeric carbon fractions and isotopic signatures of the particulate organic material (POM) revealed very fresh and labile material produced during the spring bloom (13C enriched, with values up to -22.7‰ at the highest Chl a peak, and high in carbohydrates and proteins content -up to 167 and 148 µg/L, respectively-), and a clear and strong continental signature of the POM present during late summer and fall (13C depleted, with values averaging -26.5 ‰, and high in lipid content –up to 92 µg/L-) when freshwater melting is accentuated. Our data evidence the importance of combining both physical (i.e. water mass dominance) and geochemical (i.e. characteristics of material released by glacier runoff) data in order to
Nitrogen utilization during spring phytoplankton bloom development in the southeast Bering Sea

International Nuclear Information System (INIS)

Sambrotto, R.N.

1983-01-01

Interactions beween a high latitude, continental shelf, spring phytoplankton bloom and water column physics and chemistry were studied using 15 N measured rates of nitrogen uptake. Peak bloom conditions commenced when the mixed layer shallowed and minimized respirational losses. Integrative light-mixing growth models were accurate during early bloom stages. An advection-diffusion model associated peak bloom nitrate uptake with pycnocline mixing rates of 2.1 m d -1 in an 18 m mixed layer. Maximum nitrogen specific uptake rates (hr -1 ), unlike those of carbon, coincided with peak bloom conditions. Although species compositions among peak bloom periods were similar, particulate C/N ratios were not. Apparently, both intercellular factors and prevailing mixing conditions influence specific uptake rates and cell composition. A large proportion of new (nitrate) to total productivity was associated with the dominance of the early bloom forming diatoms in the mixed layer. In the absence of these net plankton the residual nanoplankton dominated community exhibited a greater dependence on regenerated nitrogen. Nitrate uptake averaged 700 mg-at m -2 during the spring bloom and 1 g-at m -2 year -1 . The yearly f factor was 0.40. Nitrogen uptake based carbon productivity was 188 g C m -2 year -1
Phytoplankton bloom dynamics in coastal ecosystems: A review with some general lessons from sustained investigation of San Francisco Bay, California

Science.gov (United States)

Cloern, James E.

1996-05-01

Phytoplankton blooms are prominent features of biological variability in shallow coastal ecosystems such as estuaries, lagoons, bays, and tidal rivers. Long-term observation and research in San Francisco Bay illustrates some patterns of phytoplankton spatial and temporal variability and the underlying mechanisms of this variability. Blooms are events of rapid production and accumulation of phytoplankton biomass that are usually responses to changing physical forcings originating in the coastal ocean (e.g., tides), the atmosphere (wind), or on the land surface (precipitation and river runoff). These physical forcings have different timescales of variability, so algal blooms can be short-term episodic events, recurrent seasonal phenomena, or rare events associated with exceptional climatic or hydrologic conditions. The biogeochemical role of phytoplankton primary production is to transform and incorporate reactive inorganic elements into organic forms, and these transformations are rapid and lead to measurable geochemical change during blooms. Examples include the depletion of inorganic nutrients (N, P, Si), supersaturation of oxygen and removal of carbon dioxide, shifts in the isotopic composition of reactive elements (C, N), production of climatically active trace gases (methyl bromide, dimethylsulfide), changes in the chemical form and toxicity of trace metals (As, Cd, Ni, Zn), changes in the biochemical composition and reactivity of the suspended particulate matter, and synthesis of organic matter required for the reproduction and growth of heterotrophs, including bacteria, zooplankton, and benthic consumer animals. Some classes of phytoplankton play special roles in the cycling of elements or synthesis of specific organic molecules, but we have only rudimentary understanding of the forces that select for and promote blooms of these species. Mounting evidence suggests that the natural cycles of bloom variability are being altered on a global scale by human
Localization and Tracking of Submerged Phytoplankton Bloom Patches by an Autonomous Underwater Vehicle

Science.gov (United States)

Godin, M. A.; Ryan, J. P.; Zhang, Y.; Bellingham, J. G.

2012-12-01

Observing plankton in their drifting frame of reference permits effective studies of marine ecology from the perspective of microscopic life itself. By minimizing variation caused simply by advection, observations in a plankton-tracking frame of reference focus measurement capabilities on the processes that influence the life history of populations. Further, the patchy nature of plankton populations motivates use of sensor data in real-time to resolve patch boundaries and adapt observing resources accordingly. We have developed capabilities for population-centric plankton observation and sampling by autonomous underwater vehicles (AUVs). Our focus has been on phytoplankton populations, both because of their ecological significance - as the core of the oceanic food web and yet potentially harmful under certain bloom conditions, as well as the accessibility of their signal to simple optical sensing. During the first field deployment of these capabilities in 2010, we tracked a phytoplankton patch containing toxigenic diatoms and found that their toxicity correlated with exposure to resuspended sediments. However, this first deployment was labor intensive as the AUV drove in a pre-programmed pattern centered around a patch-marking drifter; it required a boat deployment of the patch-marking drifter and required full-time operators to periodically estimate of the position of the patch with respect to the drifter and adjust the AUV path accordingly. In subsequent field experiments during 2011 and 2012, the Tethys-class long-range AUVs ran fully autonomous patch tracking algorithms which detected phytoplankton patches and continually updated estimates of each patch center by driving adaptive patterns through the patch. Iterations of the algorithm were generated to overcome the challenges of tracking advecting and evolving patches while minimizing human involvement in vehicle control. Such fully autonomous monitoring will be necessary to perform long-term in
Reduced river discharge intensifies phytoplankton bloom in Godavari estuary, India

Digital Repository Service at National Institute of Oceanography (India)

Acharyya, T.; Sarma, V.V.S.S.; Sridevi, B.; Venkataramana, V.; Bharathi, M.D.; Naidu, S.A.; Kumar, B.S.K.; Prasad, V.R.; Bandyopadhyay, D.; Reddy, N.P.C.; DileepKumar, M.

et al., 2009; Sarma et al., 2011), behaviour of different 3 elements (Sarma et al., 1993) and heavy metals (Somayajulu et al., 1993).Virtually no systematic studies have been undertaken so far in these estuaries focussing on spatial and... their class specific marker pigment fucoxanthin (Jeffry et al., 1997; Mantoura and Llewellyn, 1983; Wright et al., 1991). To confirm the influence of SPM and flushing time on phytoplankton bloom a laboratory- based incubation experiment was conducted...
Physical and Biogeochemical Controls of the Phytoplankton Blooms in North Western Mediterranean Sea: A Multiplatform Approach Over a Complete Annual Cycle (2012-2013 DEWEX Experiment)

Science.gov (United States)

Mayot, Nicolas; D'Ortenzio, Fabrizio; Taillandier, Vincent; Prieur, Louis; de Fommervault, Orens Pasqueron; Claustre, Hervé; Bosse, Anthony; Testor, Pierre; Conan, Pascal

2017-12-01

The North Western Mediterranean Sea exhibits recurrent and significant autumnal and spring phytoplankton blooms. The existence of these two blooms coincides with typical temperate dynamics. To determine the potential control of physical and biogeochemical factors on these phytoplankton blooms, data from a multiplatform approach (combining ships, Argo and BGC-Argo floats, and bio-optical gliders) were analyzed in association with satellite observations in 2012-2013. The satellite framework allowed a simultaneous analysis over the whole annual cycle of in situ observations of mixed layer depth, photosynthetical available radiation, particle backscattering, nutrients (nitrate and silicate), and chlorophyll-a concentrations. During the year 2012-2013, satellite ocean color observations, confirmed by in situ data, have revealed the existence of two areas (or bioregions) with comparable autumnal blooms but contrasting spring blooms. In both bioregions, the ratio of the euphotic zone (defined as the isolume 0.415 mol photons m-2 d-1, Z0.415) and the MLD identified the initiation of the autumnal bloom, as well as the maximal annual increase in [Chl-a] in spring. In fact, the autumnal phytoplankton bloom might be initiated by mixing of the summer shallowing deep chlorophyll maximum, while the spring restratification (when Z0.415/MLD ratio became >1) might induce surface phytoplankton production that largely overcomes the losses. Finally, winter deep convection events that took place in one of the bioregions induced higher net accumulation rate of phytoplankton in spring associated with a diatom-dominated phytoplankton community principally. We suggest that very deep winter MLD lead to an increase in surface silicates availability, which favored the development of diatoms.
Phytoplankton dynamics in contrasting early stage North Atlantic spring blooms: composition, succession, and potential drivers

DEFF Research Database (Denmark)

Daniels, C.J.; Poulton, A. J.; Esposito, M.

2015-01-01

The spring bloom is a key annual event in the phenology of pelagic ecosystems, making a major contribution to the oceanic biological carbon pump through the production and export of organic carbon. However, there is little consensus as to the main drivers of spring bloom formation, exacerbated......) of the 2012 North Atlantic spring bloom. The plankton composition and characteristics of the initial stages of the bloom were markedly different between the two basins. The Iceland Basin (ICB) appeared well mixed to > 400 m, yet surface chlorophyll a (0.27–2.2 mg m–3) and primary production (0.06–0.66 mmol C...... suggest micro-zooplankton grazing, potentially coupled with the lack of a seed population of bloom forming diatoms, was restricting diatom growth in the NWB, and that large diatoms may be absent in NWB spring blooms. Despite both phytoplankton communities being in the early stages of bloom formation...
Retention time generates short-term phytoplankton blooms in a shallow microtidal subtropical estuary

Science.gov (United States)

Odebrecht, Clarisse; Abreu, Paulo C.; Carstensen, Jacob

2015-09-01

In this study it was hypothesised that increasing water retention time promotes phytoplankton blooms in the shallow microtidal Patos Lagoon estuary (PLE). This hypothesis was tested using salinity variation as a proxy of water retention time and chlorophyll a for phytoplankton biomass. Submersible sensors fixed at 5 m depth near the mouth of PLE continuously measured water temperature, salinity and pigments fluorescence (calibrated to chlorophyll a) between March 2010 and 12th of December 2011, with some gaps. Salinity variations were used to separate alternating patterns of outflow of lagoon water (salinity 24; 35% of the time). The two transition phases represented a rapid change from lagoon water outflow to marine water inflow and a more gradually declining salinity between the dominating inflow and outflow conditions. During the latter of these, a significant chlorophyll a increase relative to that expected from a linear mixing relationship was observed at intermediate salinities (10-20). The increase in chlorophyll a was positively related to the duration of the prior coastal water inflow in the PLE. Moreover, chlorophyll a increase was significantly higher during austral spring-summer than autumn-winter, probably due to higher light and nutrient availability in the former. Moreover, the retention time process operating on time scales of days influences the long-term phytoplankton variability in this ecosystem. Comparing these results with monthly data from a nearby long-term water quality monitoring station (1993-2011) support the hypothesis that chlorophyll a accumulations occur after marine inflow events, whereas phytoplankton does not accumulate during high water outflow, when the water residence time is short. These results suggest that changing hydrological pattern is the most important mechanism underlying phytoplankton blooms in the PLE.
The 1987–1989 Phytoplankton Bloom in Kaneohe Bay

Directory of Open Access Journals (Sweden)

Edward Laws

2018-06-01

Full Text Available A remarkable bloom of phytoplankton occurred in the southeast sector (SE of Kaneohe Bay from 1987 through 1989. During the bloom, concentrations of chlorophyll a at the former site of the Kaneohe municipal wastewater treatment plant outfall averaged a little more than 2 mg m–3 for a period of 40 months. The increase of chl a was accompanied by a roughly twofold increase in the percentage of chl a accounted for by cells retained on a 35-micron filter, a drawdown of silicate concentrations from roughly 10 μM to 3–4 μM, an increase of nitrate concentrations from roughly 0.5 to more than 3 μM, and an increase of phosphate concentrations from roughly 0.2 to 0.5 μM. Extraordinarily heavy rains on 31 December 1987 led to flooding and land runoff that briefly raised chl a concentrations in the bay to as high as 17 mg m–3, but the bloom in question developed more than one year before the 1987 New Year’s Eve flood. It was not caused by unusually heavy rainfall: the average rainfall during 1987–1989 was only 10% above the long-term average. Instead, the bloom appears to have been caused by a leak in the sanitary sewer line that was previously used to discharge secondary treated sewage into Kaneohe Bay. Ultimately, leaks in the sanitary sewer lines maintained by the City and County of Honolulu led to legal action and a consent decree that required upgrading and the renovation of the wastewater collection system.
Coupling of heterotrophic bacteria to phytoplankton bloom development at different pCO2 levels: a mesocosm study

Directory of Open Access Journals (Sweden)

R. Thyrhaug

2008-07-01

Full Text Available The predicted rise in anthropogenic CO2 emissions will increase CO2 concentrations and decrease seawater pH in the upper ocean. Recent studies have revealed effects of pCO2 induced changes in seawater chemistry on a variety of marine life forms, in particular calcifying organisms. To test whether the predicted increase in pCO2 will directly or indirectly (via changes in phytoplankton dynamics affect abundance, activities, and community composition of heterotrophic bacteria during phytoplankton bloom development, we have aerated mesocosms with CO2 to obtain triplicates with three different partial pressures of CO2 (pCO2: 350 μatm (1×CO2, 700 μatm (2×CO2 and 1050 μatm (3×CO2. The development of a phytoplankton bloom was initiated by the addition of nitrate and phosphate. In accordance to an elevated carbon to nitrogen drawdown at increasing pCO2, bacterial production (BPP of free-living and attached bacteria as well as cell-specific BPP (csBPP of attached bacteria were related to the C:N ratio of suspended matter. These relationships significantly differed among treatments. However, bacterial abundance and activities were not statistically different among treatments. Solely community structure of free-living bacteria changed with pCO2 whereas that of attached bacteria seemed to be independent of pCO2 but tightly coupled to phytoplankton bloom development. Our findings imply that changes in pCO2, although reflected by changes in community structure of free-living bacteria, do not directly affect bacterial activity. Furthermore, bacterial activity and dynamics of heterotrophic bacteria, especially of attached bacteria, were tightly correlated to phytoplankton development and, hence, may also potentially depend on changes in pCO2.
ESA-MERIS 10-Year Mission Reveals Contrasting Phytoplankton Bloom Dynamics in Two Tropical Regions of Northern Australia

Directory of Open Access Journals (Sweden)

David Blondeau-Patissier

2014-04-01

Full Text Available The spatial and temporal variability of phytoplankton blooms was investigated in two tropical coastal regions of northern Australia using the MEdium Resolution Imaging Spectrometer (MERIS full mission (2002–2012 reduced resolution dataset. Satellite-derived proxies for phytoplankton (Chlorophyll-a (Chl, Fluorescence Line Height (FLH, Maximum Chlorophyll Index (MCI and suspended sediment (Total Suspended Matter (TSM were jointly analyzed for two clusters of the Great Barrier Reef Wet tropics (GBRW; 15°–19.5°S; Queensland and the Van Diemen Gulf (VDG; 9°–13°S; Northern Territory. The analysis of time-series and Hovmöller diagrams of the four MERIS products provided a unique perspective on the processes linking phytoplankton blooms and river runoff, or resuspension, across spatio-temporal scales. Both regions are characterized by a complex oceanography and seasonal inflows of sediment, freshwater and nutrients during the tropical wet season months (November to April. The GBRW is characterized by a great variability in water clarity (Secchi depth 0–25 m. A long history of agricultural land use has led to a large increase in the seasonal discharge of sediments and nutrients, triggering seasonal phytoplankton blooms (>0.4 mg∙m−3 between January and April. In contrast, the VDG is a poorly flushed, turbid (Secchi depth <5 m environment with strong tidal-energy (4–8 m and very limited land use. Phytoplankton blooms here were found to have higher Chl concentrations (>1.0 mg∙m−3 than in the GBRW, occurring up to twice a year between January and April. Over the 10-year MERIS mission, a weak decline in Chl and TSM was observed for the VDG (Sen slope: −2.85%/decade, τ = −0.32 and −3.57%/decade, τ = −0.24; p 0.05, while no significant trend in those two satellite products was observed in the GBRW. Cyanobacteria surface algal blooms occur in both regions between August and October. The MCI and FLH products were found to
Key role of organic complexation of iron in sustaining phytoplankton blooms in the Pine Island and Amundsen Polynyas (Southern Ocean)

NARCIS (Netherlands)

Thuroczy, Charles-Edouard; Alderkamp, Anne-Carlijn; Laan, Patrick; Gerringa, Loes J. A.; Mills, Matthew M.; Van Dijken, Gert L.; De Baar, Hein J. W.; Arrigo, Kevin R.

2012-01-01

Primary productivity in the Amundsen Sea (Southern Ocean) is among the highest in Antarctica. The summer phytoplankton bloom in 2009 lasted for > 70 days in both the Pine Island and Amundsen Polynyas. Such productive blooms require a large supply of nutrients, including the trace metal iron (Fe).
Variation of particulate organic carbon and its relationship with bio-optical properties during a phytoplankton bloom in the Pearl River estuary

International Nuclear Information System (INIS)

Wang Guifen; Zhou Wen; Cao Wenxi; Yin Jianping; Yang Yuezhong; Sun Zhaohua; Zhang Yuanzhi; Zhao Jun

2011-01-01

Highlights: → A study about relationship between POC and optical properties during a phytoplankton bloom. → Empirical algorithms for retrieving POC concentration from optical data were developed. → Phytoplankton carbon and it's ratio to Chl-a are estimated and discussed. → Demonstrates that marine optical buoy can be a new platform for monitoring biogeochemical cycle. - Abstract: In this study, variations in the particulate organic carbon (POC) were monitored during a phytoplankton bloom event, and the corresponding changes in bio-optical properties were tracked at one station (114.29 o E, 22.06 o N) located in the Pearl River estuary. A greater than 10-fold increase in POC (112.29-1173.36 mg m -3 ) was observed during the bloom, with the chlorophyll a concentration (Chl-a) varying from 0.984 to 25.941 mg m -3 . A power law function is used to describe the relationship between POC and Chl-a, and the POC:Chl-a ratio tends to change inversely with Chl-a. Phytoplankton carbon concentration is indirectly estimated using the conceptual model proposed by , and this carbon is found to contribute 47.21% (±10.65%) to total POC. The estimated carbon-to-chlorophyll ratio of phytoplankton in diatom-dominated waters is found to be comparable with results reported in the literature. Empirical algorithms for determining the concentrations of Chl-a and POC were developed based on the relationships of these variables with the blue-to-green reflectance ratio. With these bio-optical models, the levels of particulate organic carbon and Chl-a could be predicted from the radiometric data measured by a marine optical buoy, which showed much more detailed information about the variability in biogeochemical parameters during this bloom event.
The effect of environmental parameters and cyanobacterial blooms on phytoplankton dynamics of a Portuguese temperate lake

DEFF Research Database (Denmark)

De Figueiredo, Daniela R.; P. S. Reboleira, Ana Sofia; Antunes, Sara C.

2006-01-01

The increasing occurrence of cyanobacterial blooms in freshwaters is of great concern due to the ability of many cyanobacteria to produce cyanotoxins. In the present work, the eutrophied Vela Lake (Central Portugal), used for recreational purposes and as a water source for agriculture, was monito...... for the phytoplanktonic assemblage during the study period was increased in about 7% achieving a total of 61.0%, indicating a correlation that may be due to the known competitive advantage and/or allelopathy of the bloom-forming cyanobacteria towards microalgae....
Basin-wide seasonal evolution of the Indian Ocean's phytoplankton blooms

Digital Repository Service at National Institute of Oceanography (India)

Levy, M.; Shankar, D.; Andre, J.M.; Shenoi, S.S.C.; Durand, F.; De

OF GEOPHYSICAL RESEARCH, VOL. ???, XXXX, DOI:10.1029/, Basin-wide seasonal evolution of the Indian Ocean’s1 phytoplankton blooms2 M. L´evy 1,2 ,D.Shankar 2 , J.-M. Andr´e 1,2 , S. S. C. Shenoi 2 ,F.Durand 2,3 and C. de Boyer Mont´egut 4 M. L´evy, LOCEAN....2. The physical model We used outputs from the NEMO OGCM in its global configuration ORCA0595 (http://www.locean-ipsl.upmc.fr/NEMO). The model run that we used is an updated96 version of the simulation validated by de Boyer Mont´egut et al. (in press) over...
Effects of pulsed nutrient inputs on phytoplankton assemblage structure and blooms in an enclosed coastal area

Science.gov (United States)

Spatharis, Sofie; Tsirtsis, George; Danielidis, Daniel B.; Chi, Thang Do; Mouillot, David

2007-07-01

The response of phytoplankton assemblage structure to terrestrial nutrient inputs was examined for the Gulf of Kalloni in the Northern Aegean Sea, a productive semi-enclosed coastal marine ecosystem. The study was focused on a typical annual cycle, and emphasis was placed on the comparative analysis between blooms developing after significant nutrient inputs from the watershed, and naturally occurring blooms. Baseline information was collected on a monthly basis from a network of stations located in the oligotrophic open sea and the interior and more productive part of the embayment. Intensive sampling was also carried out along a gradient in the vicinity of a river which was the most important source of freshwater and nutrient input for the Gulf. Phytoplankton assemblage structure was analyzed from 188 samples using diversity indices (Shannon and Average Taxonomic Distinctness), multivariate plotting methods (NMDS), multivariate statistics (PERMANOVA), and canonical correspondence analysis (CCA). Three characteristic assemblages were recognized: (1) an autumn assemblage developed under nutrient depleted conditions, having low diversity due to the dominance of two small diatoms, (2) a winter bloom of the potentially toxic species Pseudo-nitzschia calliantha occurring immediately after a nutrient peak and characterized by very low diversity, and (3) a naturally occurring early summer bloom of centric diatoms with relatively high diversity. The results of the study support the view that moderate nutrient inputs may have a beneficial effect on the functioning of coastal ecosystems, stimulating the taxonomic diversity through the growth of different taxonomic groups and taxa. On the other hand, a sudden pulse of high nutrient concentrations may greatly affect the natural succession of organisms, have a negative effect on the diversity through the dominance of a single species, and can increase the possibility of a harmful algal bloom development.
Seasonal phytoplankton blooms associated with monsoonal influences and coastal environments in the sea areas either side of the Indochina Peninsula

Science.gov (United States)

Tang, Dan Ling; Kawamura, Hiroshi; Shi, Ping; Takahashi, Wataru; Guan, Lei; Shimada, Teruhisa; Sakaida, Futoki; Isoguchi, Osamu

2006-03-01

The Gulf of Thailand (GoT) is a semienclosed sea on the west and southwest side of the Indochina Peninsula and connects with the near-coastal waters of the South China Sea (SCS) on the east and northeast side of the Malay Peninsula. The objective of the present study is to understand dynamic features of the phytoplankton biology in the GoT and the nearby SCS, on both sides of the Indochina Peninsula, using remote-sensing measurements of chlorophyll-a (Chl a), sea surface temperature (SST), and surface vector winds obtained during the period from September 1997 to March 2003. Results show that seasonal variations of the phytoplankton blooms are primarily controlled by the monsoonal winds and related coastal environments. The GoT and the near-coastal SCS have a peak in the averaged monthly Chl a in December and January, which is associated with the winter northeaster monsoon. The near-coastal SCS have another big peak in the averaged monthly Chl a in summer (July to September), which is associated with the summer southwest monsoon. The offshore bloom in the GoT occurs in its southern part and enhances the December-January peak of averaged monthly Chl a. By contrast, the offshore bloom in the nearby SCS is observed northeast of the Peninsula, and represents the primary source of the July-September peak Chl a. Here the coastal upwelling associated with the offshore Ekman transport caused by the coastal surface winds parallel to the Vietnam east coast gives physical conditions favorable to the development of offshore phytoplankton blooms. The Mekong River discharge waters flow in different directions, depending on the monsoon winds, and contributes to seasonal blooms on both sides of the Peninsula.
Further Studies on the Physical and Biogeochemical Causes for Large Interannual Changes in the Patagonian Shelf Spring-Summer Phytoplankton Bloom Biomass

Science.gov (United States)

Signorini, Sergio R.; Garcia, Virginia M.T.; Piola, Alberto R.; Evangelista, Heitor; McClain, Charles R.; Garcia, Carlos A.E.; Mata, Mauricio M.

2009-01-01

A very strong and persistent phytoplankton bloom was observed by ocean color satellites during September - December 2003 along the northern Patagonian shelf. The 2003 bloom had the highest extent and chlorophyll a (Chl-a) concentrations of the entire Sea-viewing Wide Field-of-view Sensor (SeaWiFS) period (1997 to present). SeaWiFS-derived Chl-a exceeded 20 mg/cu m in November at the bloom center. The bloom was most extensive in December when it spanned more than 300 km across the shelf and nearly 900 km north-south (35degS to 43degS). The northward reach and the deep penetration on the shelf of the 2003 bloom were quite anomalous when compared with other years, which showed the bloom more confined to the Patagonian shelf break (PSB). The PSB bloom is a conspicuous austral spring-summer feature detected by ocean color satellites and its timing can be explained using the Sverdrup critical depth theory. Based on high-resolution numerical simulations, in situ and remote sensing data, we provide some suggestions for the probable mechanisms responsible for that large interannual change of biomass as seen by ocean color satellites. Potential sources of macro and micro (e.g., Fe) nutrients that sustain the high phytoplankton productivity of the Patagonian shelf waters are identified, and the most likely physical processes that maintain the nutrient balance in the region are discussed.
Nutrients and toxin producing phytoplankton control algal blooms - a spatio-temporal study in a noisy environment.

Science.gov (United States)

Sarkar, Ram Rup; Malchow, Horst

2005-12-01

A phytoplankton-zooplankton prey-predator model has been investigated for temporal, spatial and spatio-temporal dissipative pattern formation in a deterministic and noisy environment, respectively. The overall carrying capacity for the phytoplankton population depends on the nutrient level. The role of nutrient concentrations and toxin producing phytoplankton for controlling the algal blooms has been discussed. The local analysis yields a number of stationary and/or oscillatory regimes and their combinations. Correspondingly interesting is the spatio-temporal behaviour, modelled by stochastic reaction-diffusion equations. The present study also reveals the fact that the rate of toxin production by toxin producing phytoplankton (TPP) plays an important role for controlling oscillations in the plankton system. We also observe that different mortality functions of zooplankton due to TPP have significant influence in controlling oscillations, coexistence, survival or extinction of the zoo-plankton population. External noise can enhance the survival and spread of zooplankton that would go extinct in the deterministic system due to a high rate of toxin production.

How the Subpolar gyre strength influences phytoplankton blooms dynamics in the North Atlantic

DEFF Research Database (Denmark)

Ferreira, Ana Sofia; Payne, Mark; MacKenzie, Brian

2012-01-01

height (SSH, from the AVISO project) as a proxy of current strength. Three regions were strategically chosen to characterize positions relative to the NASPG, describing: region 1—the northern part of NASPG, including the Irminger Current (IC); region 2—the North Atlantic Current (NAC), its northwards......Changes in the North Atlantic Subpolar gyre (NASPG) have been linked to the interannual variability of primary production. However, little is known about the mechanisms behind both environmental processes, and how the NASPG strength may extend its potential impacts to higher trophic levels......, including early life stages of commercial fish species. We assess NASPG strength effect on North Atlantic phytoplankton bloom dynamics. We analyse time‐series (from 1998 to 2010) of chlorophyll a (Chl a, from the Globcolour project) annual anomaly as a proxy of phytoplankton abundance, and of sea surface...
Effects of CO2 on particle size distribution and phytoplankton abundance during a mesocosm bloom experiment (PeECE II

Directory of Open Access Journals (Sweden)

M. Schartau

2008-04-01

Full Text Available The influence of seawater carbon dioxide (CO2 concentration on the size distribution of suspended particles (2–60 μm and on phytoplankton abundance was investigated during a mesocosm experiment at the large scale facility (LFS in Bergen, Norway, in the frame of the Pelagic Ecosystem CO2 Enrichment study (PeECE II. In nine outdoor enclosures the partial pressure of CO2 in seawater was modified by an aeration system to simulate past (~190 μatm CO2, present (~370 μatm CO2 and future (~700 μatm CO2 CO2 conditions in triplicates. Due to the initial addition of inorganic nutrients, phytoplankton blooms developed in all mesocosms and were monitored over a period of 19 days. Seawater samples were collected daily for analysing the abundance of suspended particles and phytoplankton with the Coulter Counter and with Flow Cytometry, respectively. During the bloom period, the abundance of small particles (2 levels. At that time, a direct relationship between the total-surface-to-total-volume ratio of suspended particles and DIC concentration was determined for all mesocosms. Significant changes with respect to the CO2 treatment were also observed in the phytoplankton community structure. While some populations such as diatoms seemed to be insensitive to the CO2 treatment, others like Micromonas spp. increased with CO2, or showed maximum abundance at present day CO2 (i.e. Emiliania huxleyi. The strongest response to CO2 was observed in the abundance of small autotrophic nano-plankton that strongly increased during the bloom in the past CO2 mesocosms. Together, changes in particle size distribution and phytoplankton community indicate a complex interplay between the ability of the cells to physiologically respond to changes in CO2 and size selection. Size of cells is of general importance for a variety of processes in marine systems such as diffusion-limited uptake of substrates, resource allocation, predator-prey interaction, and gravitational settling
El Niño-related offshore phytoplankton bloom events around the Spratley Islands in the South China Sea

Science.gov (United States)

Isoguchi, Osamu; Kawamura, Hiroshi; Ku-Kassim, Ku-Yaacob

2005-11-01

Satellite chlorophyll-a (Chl-a) observations reveal offshore phytoplankton bloom events with high Chl-a (>1 mg m-3) spreading over 300 km off the coasts around the Spratley Islands in the South China Sea (SCS) during the spring of 1998. The bloom entails anomalous wind jet and sea surface temperature (SST) cooling, suggesting that the wind jet-induced mixing and/or offshore upwelling bring about the cooling and the bloom through the supply of nutrient-rich waters into the euphotic zone. The strong wind jet is orographically formed responding to shifts in wind direction over the eastern SCS. The wind shift is connected with the Philippine Sea anomalous anticyclone that is established during El Niño, indicating the El Niño-related offshore bloom. The long-term reanalysis winds over the eastern SCS demonstrates that wind jet formation and associated offshore cooling/bloom are expected to occur in most cases of the subsequent El Niño years.
Succession and fate of the spring diatom bloom in Disko Bay, western Greenland

DEFF Research Database (Denmark)

Dünweber, Michael; Swalethorp, Rasmus; Kjellerup, Sanne

2010-01-01

Phytoplankton and copepod succession was investigated in Disko Bay, western Greenland from February to July 2008. The spring phytoplankton bloom developed immediately after the breakup of sea ice and reached a peak concentration of 24 mg chl a m–3 2 wk later. The bloom was analyzed during 3 phases...... from the initiation of the bloom but only had a small grazing impact on the phytoplankton. Consequently, there was a close coupling between the spring phytoplankton bloom and sedimentation of particulate organic carbon (POC). Out of 1836 ± 180 mg C m–2 d–1 leaving the upper 50 m, 60% was phytoplankton...... and fate of the phytoplankton spring bloom was controlled by nitrogen limitation and subsequent sedimentation, while grazing-mediated flux by the Calanus-dominated copepod community played a minor role in the termination of the spring bloom of Disko Bay....
Challenges in modelling spatiotemporally varying phytoplankton blooms in the Northwestern Arabian Sea and Gulf of Oman

Science.gov (United States)

Sedigh Marvasti, S.; Gnanadesikan, A.; Bidokhti, A. A.; Dunne, J. P.; Ghader, S.

2015-07-01

We examine interannual variability of phytoplankton blooms in northwestern Arabian Sea and Gulf of Oman. Satellite data (SeaWIFS ocean color) shows two climatological blooms in this region, a wintertime bloom peaking in February and a summertime bloom peaking in September. A pronounced anti-correlation between the AVISO sea surface height anomaly (SSHA) and chlorophyll is found during the wintertime bloom. On a regional scale, interannual variability of the wintertime bloom is thus dominated by cyclonic eddies which vary in location from one year to another. These results were compared against the outputs from three different 3-D Earth System models. We show that two coarse (1°) models with the relatively complex biogeochemistry (TOPAZ) capture the annual cycle but neither eddies nor the interannual variability. An eddy-resolving model (GFDL CM2.6) with a simpler biogeochemistry (miniBLING) displays larger interannual variability, but overestimates the wintertime bloom and captures eddy-bloom coupling in the south but not in the north. The southern part of the domain is a region with a much sharper thermocline and nutricline relatively close to the surface, in which eddies modulate diffusive nutrient supply to the surface (a mechanism not previously emphasized in the literature). We suggest that for the model to simulate the observed wintertime blooms within cyclones, it will be necessary to represent this relatively unusual nutrient structure as well as the cyclonic eddies. This is a challenge in the Northern Arabian Sea as it requires capturing the details of the outflow from the Persian Gulf.
Large Scale Variability of Phytoplankton Blooms in the Arctic and Peripheral Seas: Relationships with Sea Ice, Temperature, Clouds, and Wind

Science.gov (United States)

Comiso, Josefino C.; Cota, Glenn F.

2004-01-01

Spatially detailed satellite data of mean color, sea ice concentration, surface temperature, clouds, and wind have been analyzed to quantify and study the large scale regional and temporal variability of phytoplankton blooms in the Arctic and peripheral seas from 1998 to 2002. In the Arctic basin, phytoplankton chlorophyll displays a large symmetry with the Eastern Arctic having about fivefold higher concentrations than those of the Western Arctic. Large monthly and yearly variability is also observed in the peripheral seas with the largest blooms occurring in the Bering Sea, Sea of Okhotsk, and the Barents Sea during spring. There is large interannual and seasonal variability in biomass with average chlorophyll concentrations in 2002 and 2001 being higher than earlier years in spring and summer. The seasonality in the latitudinal distribution of blooms is also very different such that the North Atlantic is usually most expansive in spring while the North Pacific is more extensive in autumn. Environmental factors that influence phytoplankton growth were examined, and results show relatively high negative correlation with sea ice retreat and strong positive correlation with temperature in early spring. Plankton growth, as indicated by biomass accumulation, in the Arctic and subarctic increases up to a threshold surface temperature of about 276-277 degree K (3-4 degree C) beyond which the concentrations start to decrease suggesting an optimal temperature or nutrient depletion. The correlation with clouds is significant in some areas but negligible in other areas, while the correlations with wind speed and its components are generally weak. The effects of clouds and winds are less predictable with weekly climatologies because of unknown effects of averaging variable and intermittent physical forcing (e.g. over storm event scales with mixing and upwelling of nutrients) and the time scales of acclimation by the phytoplankton.
Early spawning of Antarctic krill in the Scotia Sea is fuelled by “superfluous” feeding on non-ice associated phytoplankton blooms

Science.gov (United States)

Schmidt, Katrin; Atkinson, Angus; Venables, Hugh J.; Pond, David W.

2012-01-01

The spawning success of Antarctic krill ( Euphausia superba) is generally assumed to depend on substantial winter sea ice extent, as ice biota can serve as a food source during winter/spring and the seasonal ice melt conditions the upper water column for extensive phytoplankton blooms. However, direct observations during spring are rare. Here we studied krill body condition and maturity stage in relation to feeding (i.e. stomach fullness, diet, absorption of individual fatty acids and defecation rate) across the Scotia Sea in November 2006. The phytoplankton concentrations were low at the marginal ice zone (MIZ) in the southern Scotia Sea (Stn. 1, 2, and 3), high in open waters of the Southern Antarctic Circumpolar Current Front (SACCF) in the central Scotia Sea (Stn. 5), and moderate further north (Stn. 6 and 7). Krill had low lipid reserves (˜6.5% of dry mass, DM), low mass:length ratios (˜1.7 mg DM mm -1), and small digestive glands (˜7% of total DM) near the ice edge. The stomachs contained lithogenic particles, diatom debris, and bacterial fatty acids, but low proportions of diatom-indicating fatty acids, which suggest that these krill were feeding on detritus rather than on fresh ice algae. In the SACCF, krill had higher lipid reserves (˜10% of DM), high mass:length ratios (˜2.2 mg DM mm -1), and large digestive glands (˜16% of total DM). Stomach content and tissue composition indicate feeding on diatoms. In the north, moderate food concentrations co-occurred with low lipid reserves in krill, and moderate mass:length ratios and digestive gland sizes. Only in the phytoplankton bloom in the SACCF had the mating season already started and some females were about to spawn. Based on the way krill processed their food at the different stations, we indicate two mechanisms that can lead to fast regeneration of body reserves and oocyte maturation in E. superba. One is "superfluous" feeding at high food concentrations, which maximises the overall nutrient gain
Risk associated with toxic blooms of marine phytoplankton functional groups on Artemia franciscana

Directory of Open Access Journals (Sweden)

Ana D’ors

2014-08-01

Full Text Available Objective: To study mortality of copepod Artemia franciscana against the occurrence of harmful marine algae and possible toxicological changes exhibited by binary and tertiary combinations of these harmful algae toxins. Methods: Tweenty four hours acute toxicity assays were performed with selected concentrations of Alexandrium minutum, Prorocentrum lima and Nitzschia N1c1 living cells. Additionally, the results were analyzed using the median-effect/combination index (CI-isobologram equation to assess possible changes in the toxic effect induced by phytoplankton functional groups. Results: Biotoxin equivalent values obtained by immunodetection were (2.12±0.10, (8.60±1.30 and (4.32±1.67 pg/cell for saxitoxin, okadaic acid and domoic acid, respectively. The 24-h LC50 values estimated to saxitoxin and okadaic acid equivalents were 4.06 and 6.27 µg/L, significantly below the value obtained for Nitzschia N1c1, which was established at 467.33 µg/L. CI analysis applied on phytoplankton assemblages showed that both ternary mixture as the binary combinations exhibited antagonic action on toxic effects in Artemia nauplii, which were significantly lower than the toxic effect exhibited by each species studied. Conclusions: These results show that, although these harmful algae represent a serious risk to estuarine zooplankton community, the presence of phytoplankton functional groups within the same bloom can reduce the potential risk compared to the expected risk when each of the phytoplankton groups are evaluated individually.
Export of a Winter Shelf Phytoplankton Bloom at the Shelf Margin of Long Bay (South Atlantic Bight, USA)

Science.gov (United States)

Nelson, J.; Seim, H.; Edwards, C. R.; Lockhart, S.; Moore, T.; Robertson, C. Y.; Amft, J.

2016-02-01

A winter 2012 field study off Long Bay (seaward of Myrtle Beach, South Carolina) investigated exchange processes along the shelf margin. Topics addressed included mechanisms of nutrient input (upper slope to outer shelf), phytoplankton blooms and community characteristics (mid-to-outer shelf), and possible export of shelf bloom material (transport to and across the shelf break to the upper slope). Observations utilized three moorings (mid-shelf, shelf break, upper slope), two gliders and ship operations (repeat cruises with profiling, water sampling and towed body surveys) along with satellite SST and ocean color imagery and near-by NOAA buoy records. Here we focus on the late January to early February period, when a mid-shelf bloom of Phaeocystis globosa (which forms large gelatinous colonies) was transported to the shelf break. The presence of Phaeocystis colonies resulted in strong spiking in chlorophyll (chl) fluorescence profiles. A partitioning approach was adapted to estimate chl in colonies (spikes) and small forms (baseline signal) and to account for an apparent difference in measured in vivo fluorescence per unit chl (lower in colonies). Up to 40-50% of chl in the bloom (surface to bottom on the mid-shelf) was estimated to be in the colonies. In late January, there a pronounced seaward slumping of relatively dense mid-shelf water along the bottom under warmer surface water derived from the inshore edge of a broad jet of Gulf Stream water flowing southwestward along the upper slope. We describe the evolution of this event and the conditions which set up this mechanism for episodic near-bed transport of fresh bloom material produced on the shelf to the upper slope off Long Bay. Down-slope transport may have been enhanced in this case by the high phytoplankton biomass in gelatinous colonies, which appeared to be settling in the water column on the shelf prior to the transport event.
Dynamics of particulate and dissolved organic and inorganic phosphorus during the peak and declining phase of an iron-induced phytoplankton bloom in the eastern subarctic Pacific

Science.gov (United States)

Yoshimura, Takeshi; Nishioka, Jun; Ogawa, Hiroshi; Tsuda, Atsushi

2018-01-01

Phosphorus (P) is an essential element for all organisms and thus the P cycle plays a key role in determining the dynamics of lower trophic levels in marine ecosystems. P in seawater occurs conceptually in particulate and dissolved organic and inorganic (POP, PIP, DOP, and DIP, respectively) pools and clarification of the dynamics in these P pools is the basis to assess the biogeochemical cycle of P. Despite its importance, behaviors of each P pool with phytoplankton dynamics have not been fully examined. We measured the four operationally defined P pools (POPop, PIPop, DOPop, and SRP) during an iron-induced phytoplankton bloom (as part of the subarctic ecosystem response to iron enrichment study (SERIES)) in the eastern subarctic Pacific in summer 2002. During our observations of the iron-enriched patch from day 15 to day 26 after the iron infusion, chlorophyll-a concentration in the surface layer decreased from 6.3 to 1.2 μg L- 1, indicating the peak through decline phase of the phytoplankton bloom. At the bloom peak, P was partitioned into POPop, PIPop, and DOPop in proportions of 60, 27, and 13%, respectively. While chlorophyll-a and POPop showed similar temporal variations during the declining phase, PIPop showed a different peak timing with a 2 day delay compared to POPop, resulting in a rapid change in the relative proportion of PIPop to total particulate P (TPP = POPop + PIPop) at the peak (25%) and during the declining phase of the bloom (50%). A part of POPop was replaced by PIPop just after slowing down of phytoplankton growth. This process may have a significant role in the subsequent regeneration of P. We conclude that measurement of TPP alone is insufficient to show the interaction between P and phytoplankton dynamics and fractionation of TPP into POPop and PIPop provides useful insights to clarify the biogeochemical cycle of P.
Challenges in modeling spatiotemporally varying phytoplankton blooms in the Northwestern Arabian Sea and Gulf of Oman

Science.gov (United States)

Sedigh Marvasti, S.; Gnanadesikan, A.; Bidokhti, A. A.; Dunne, J. P.; Ghader, S.

2016-02-01

Recent years have shown an increase in harmful algal blooms in the Northwest Arabian Sea and Gulf of Oman, raising the question of whether climate change will accelerate this trend. This has led us to examine whether the Earth System Models used to simulate phytoplankton productivity accurately capture bloom dynamics in this region - both in terms of the annual cycle and interannual variability. Satellite data (SeaWIFS ocean color) show two climatological blooms in this region, a wintertime bloom peaking in February and a summertime bloom peaking in September. On a regional scale, interannual variability of the wintertime bloom is dominated by cyclonic eddies which vary in location from one year to another. Two coarse (1°) models with the relatively complex biogeochemistry (TOPAZ) capture the annual cycle but neither eddies nor the interannual variability. An eddy-resolving model (GFDL CM2.6) with a simpler biogeochemistry (miniBLING) displays larger interannual variability, but overestimates the wintertime bloom and captures eddy-bloom coupling in the south but not in the north. The models fail to capture both the magnitude of the wintertime bloom and its modulation by eddies in part because of their failure to capture the observed sharp thermocline and/or nutricline in this region. When CM2.6 is able to capture such features in the Southern part of the basin, eddies modulate diffusive nutrient supply to the surface (a mechanism not previously emphasized in the literature). For the model to simulate the observed wintertime blooms within cyclones, it will be necessary to represent this relatively unusual nutrient structure as well as the cyclonic eddies. This is a challenge in the Northern Arabian Sea as it requires capturing the details of the outflow from the Persian Gulf - something that is poorly done in global models.
Wind-driven marine phytoplank blooms: Satellite observation and analysis

Science.gov (United States)

Tang, DanLing

2016-07-01

Algal bloom is defined as a rapid increase or accumulation in biomass in an aquatic system. It not only can increase the primary production but also could result in negative ecological consequence, e.g.,Harmful Algal Blooms (HABs). According to the classic theory for the formation of algal blooms "critical depth" and "eutrophication", oligotrophic sea area is usually difficult to form a large area of algal blooms, and actuallythe traditional observation is only sporadic capture to the existence of algal blooms.Taking full advantage of multiple data of satellite remote sensing , this study introduces "Wind-driven algal blooms in open oceans: observation and mechanisms" It explained except classic coastal Ekman transport, the wind through a variety of mechanisms affecting the formation of algal blooms. Proposed a conceptual model of "Strong wind -upwelling-nutrient-phytoplankton blooms" in Western South China Sea (SCS) to assess role of wind-induced advection transport in phytoplankton bloom formation. It illustrates the nutrient resources that support long-term offshore phytoplankton blooms in the western SCS; (2)Proposal of the theory that "typhoons cause vertical mixing, induce phytoplankton blooms", and quantify their important contribution to marine primary production; Proposal a new ecological index for typhoon. Proposed remote sensing inversion models. (3)Finding of the spatial and temporaldistributions pattern of harmful algal bloom (HAB)and species variations of HAB in the South Yellow Sea and East China Sea, and in the Pearl River estuary, and their oceanic dynamic mechanisms related with monsoon; The project developed new techniques and generated new knowledge, which significantly improved understanding of the formation mechanisms of algal blooms. The proposed "wind-pump" mechanism integrates theoretical system combined "ocean dynamics, development of algal blooms, and impact on primary production", which will benefit fisheries management. These
Application of the Hyperspectral Imager for the Coastal Ocean to Phytoplankton Ecology Studies in Monterey Bay, CA, USA

Directory of Open Access Journals (Sweden)

John P. Ryan

2014-01-01

Full Text Available As a demonstrator for technologies for the next generation of ocean color sensors, the Hyperspectral Imager for the Coastal Ocean (HICO provides enhanced spatial and spectral resolution that is required to understand optically complex aquatic environments. In this study we apply HICO, along with satellite remote sensing and in situ observations, to studies of phytoplankton ecology in a dynamic coastal upwelling environment—Monterey Bay, CA, USA. From a spring 2011 study, we examine HICO-detected spatial patterns in phytoplankton optical properties along an environmental gradient defined by upwelling flow patterns and along a temporal gradient of upwelling intensification. From a fall 2011 study, we use HICO’s enhanced spatial and spectral resolution to distinguish a small-scale “red tide” bloom, and we examine bloom expansion and its supporting processes using other remote sensing and in situ data. From a spectacular HICO image of the Monterey Bay region acquired during fall of 2012, we present a suite of algorithm results for characterization of phytoplankton, and we examine the strengths, limitations, and distinctions of each algorithm in the context of the enhanced spatial and spectral resolution.
Early Spring Phytoplankton Dynamics in the Western Antarctic Peninsula

Science.gov (United States)

Arrigo, Kevin R.; van Dijken, Gert L.; Alderkamp, Anne-Carlijn; Erickson, Zachary K.; Lewis, Kate M.; Lowry, Kate E.; Joy-Warren, Hannah L.; Middag, Rob; Nash-Arrigo, Janice E.; Selz, Virginia; van de Poll, Willem

2017-12-01

The Palmer Long-Term Ecological Research program has sampled waters of the western Antarctic Peninsula (wAP) annually each summer since 1990. However, information about the wAP prior to the peak of the phytoplankton bloom in January is sparse. Here we present results from a spring process cruise that sampled the wAP in the early stages of phytoplankton bloom development in 2014. Sea ice concentrations were high on the shelf relative to nonshelf waters, especially toward the south. Macronutrients were high and nonlimiting to phytoplankton growth in both shelf and nonshelf waters, while dissolved iron concentrations were high only on the shelf. Phytoplankton were in good physiological condition throughout the wAP, although biomass on the shelf was uniformly low, presumably because of heavy sea ice cover. In contrast, an early stage phytoplankton bloom was observed beneath variable sea ice cover just seaward of the shelf break. Chlorophyll a concentrations in the bloom reached 2 mg m-3 within a 100-150 km band between the SBACC and SACCF. The location of the bloom appeared to be controlled by a balance between enhanced vertical mixing at the position of the two fronts and increased stratification due to melting sea ice between them. Unlike summer, when diatoms overwhelmingly dominate the phytoplankton population of the wAP, the haptophyte Phaeocystis antarctica dominated in spring, although diatoms were common. These results suggest that factors controlling phytoplankton abundance and composition change seasonally and may differentially affect phytoplankton populations as environmental conditions within the wAP region continue to change.
Can Asian Dust Trigger Phytoplankton Blooms in the Oligotrophic Northern South China Sea?

Science.gov (United States)

Wang, Sheng Hsiang; Hsu, Nai-Yung Christina; Tsay, Si-Chee; Lin, Neng-Huei; Sayer, Andrew M.; Huang, Shih-Jen; Lau, William K. M.

2012-01-01

Satellite data estimate a high dust deposition flux (approximately 18 g m(exp-2 a(exp-1) into the northern South China Sea (SCS). However, observational evidence concerning any biological response to dust fertilization is sparse. In this study, we combined long-term aerosol and chlorophyll-a (Chl-a) measurements from satellite sensors (MODIS and SeaWiFS) with a 16-year record of dust events from surface PM10 observations to investigate dust transport, flux, and the changes in Chl-a concentration over the northern SCS. Our result revealed that readily identifiable strong dust events over this region, although relatively rare (6 cases since 1994) and accounting for only a small proportion of the total dust deposition (approximately 0.28 g m(exp-2 a(exp-1), do occur and could significantly enhance phytoplankton blooms. Following such events, the Chl-a concentration increased up to 4-fold, and generally doubled the springtime background value (0.15 mg m(exp-3). We suggest these heavy dust events contain readily bioavailable iron and enhance the phytoplankton growth in the oligotrophic northern SCS.
Improved monitoring of phytoplankton bloom dynamics in a Norwegian fjord by integrating satellite data, pigment analysis, and Ferrybox data with a coastal observation network

Science.gov (United States)

Volent, Zsolt; Johnsen, Geir; Hovland, Erlend K.; Folkestad, Are; Olsen, Lasse M.; Tangen, Karl; Sørensen, Kai

2011-01-01

Monitoring of the coastal environment is vitally important as these areas are of economic value and at the same time highly exposed to anthropogenic influence, in addition to variation of environmental variables. In this paper we show how the combination of bio-optical data from satellites, analysis of water samples, and a ship-mounted automatic flow-through sensor system (Ferrybox) can be used to detect and monitor phytoplankton blooms both spatially and temporally. Chlorophyll a (Chl a) data and turbidity from Ferrybox are combined with remotely sensed Chl a and total suspended matter from the MERIS instrument aboard the satellite ENVISAT (ENVIronmental SATellite) European Space Agency. Data from phytoplankton speciation and enumeration obtained by a national coastal observation network consisting of fish farms and the Norwegian Food Safety Authority are supplemented with data on phytoplankton pigments. All the data sets are then integrated in order to describe phytoplankton bloom dynamics in a Norwegian fjord over a growth season, with particular focus on Emiliania huxleyi. The approach represents a case example of how coastal environmental monitoring can be improved with existing instrument platforms. The objectives of the paper is to present the operative phytoplankton monitoring scheme in Norway, and to present an improved model of how such a scheme can be designed for a large part of the world's coastal areas.
Identification of non-indigenous phytoplankton species dominated bloom off Goa using inverted microscopy and pigment (HPLC) analysis

Science.gov (United States)

Bhaskar, P. V.; Roy, Rajdeep; Gauns, Mangesh; Shenoy, D. M.; Rao, V. D.; Mochemadkar, S.

2011-12-01

An unusual phytoplankton bloom dominated by unidentified green coloured spherical algal cells (˜5μm diameter) and dinoflagellates ( Heterocapsa, Scripsiella and Gymnodinium) was encountered along the coast of Goa, India during 27 and 29 January, 2005. Pigment analysis was carried out using both fluorometric and HPLC methods. Seawater samples collected from various depths within the intense bloom area showed high concentrations of Chl a (up to 106 mg m - 3) associated with low bacterial production (0.31 to 0.52 mg C m - 3 h - 1) and mesozooplankton biomass (0.03 ml m - 3). Pigment analyses of the seawater samples were done using HPLC detected marker pigments corresponding to prasinophytes, dinoflagellates and diatoms. Chlorophyll b (36-56%) followed by peridinin (15-30%), prasinoxanthin (11-17%) and fucoxanthin (7-15%) were the major diagnostic pigments while pigments of cryptophytes and cyanobacteria including alloxanthin and zeaxanthin formed <10%. Although microscopic analysis indicated a decline in the bloom, pheaophytin concentrations in the water column measured by both techniques were very low, presumably due to fast recycling and/or settling rate. The unique composition of the bloom and its probable causes are discussed in this paper.
Wintertime phytoplankton bloom in the Subarctic Pacific supported by continental margin iron

International Nuclear Information System (INIS)

Lam, Phoebe J.; Bishop, James K.B.; Henning, Cara C.; Marcus, Matthew A.; Waychunas, Glenn A.; Fung, Inez

2004-01-01

Heightened biological activity was observed in February 1996 in the high-nutrient low-chlorophyll (HNLC) subarctic North Pacific Ocean, a region that is thought to be iron-limited. Here we provide evidence supporting the hypothesis that Ocean Station Papa (OSP) in the subarctic Pacific received a lateral supply of particulate iron from the continental margin off the Aleutian Islands in the winter, coincident with the observed biological bloom. Synchrotron X-ray analysis was used to describe the physical form, chemistry, and depth distributions of iron in size fractionated particulate matter samples. The analysis reveals that discrete micron-sized iron-rich hotspots are ubiquitous in the upper 200m at OSP, more than 900km from the closest coast. The specifics of the chemistry and depth profiles of the Fe hot spots trace them to the continental margins. We thus hypothesize that iron hotspots are a marker for the delivery of iron from the continental margin. We confirm the delivery of continental margin iron to the open ocean using an ocean general circulation model with an iron-like tracer source at the continental margin. We suggest that iron from the continental margin stimulated a wintertime phytoplankton bloom, partially relieving the HNLC condition
Multi-Spectral Remote Sensing of Phytoplankton Pigment Absorption Properties in Cyanobacteria Bloom Waters: A Regional Example in the Western Basin of Lake Erie

Directory of Open Access Journals (Sweden)

Guoqing Wang

2017-12-01

Full Text Available Phytoplankton pigments absorb sunlight for photosynthesis, protect the chloroplast from damage caused by excess light energy, and influence the color of the water. Some pigments act as bio-markers and are important for separation of phytoplankton functional types. Among many efforts that have been made to obtain information on phytoplankton pigments from bio-optical properties, Gaussian curves decomposed from phytoplankton absorption spectrum have been used to represent the light absorption of different pigments. We incorporated the Gaussian scheme into a semi-analytical model and obtained the Gaussian curves from remote sensing reflectance. In this study, a series of sensitivity tests were conducted to explore the potential of obtaining the Gaussian curves from multi-spectral satellite remote sensing. Results showed that the Gaussian curves can be retrieved with 35% or less mean unbiased absolute percentage differences from MEdium Resolution Imaging Spectrometer (MERIS and Moderate Resolution Imaging Spectroradiometer (MODIS-like sensors. Further, using Lake Erie as an example, the spatial distribution of chlorophyll a and phycocyanin concentrations were obtained from the Gaussian curves and used as metrics for the spatial extent of an intense cyanobacterial bloom occurred in Lake Erie in 2014. The seasonal variations of Gaussian absorption properties in 2011 were further obtained from MERIS imagery. This study shows that it is feasible to obtain Gaussian curves from multi-spectral satellite remote sensing data, and the obtained chlorophyll a and phycocyanin concentrations from these Gaussian peak heights demonstrated potential application to monitor harmful algal blooms (HABs and identification of phytoplankton groups from satellite ocean color remote sensing semi-analytically.
The Role of Phytoplankton Dynamics in the Seasonal and Interannual Variability of Carbon in the Subpolar North Atlantic - a Modeling Study

Science.gov (United States)

Signorini, Sergio; Hakkinen, Sirpa; Gudmundsson, K.; Olsen, A.; Omar, A. M.; Olafsson, J.; Reverdin, G.; Henson, S. A.; McClain, C. R.; Worthen, D. L.

2014-01-01

We developed an ecosystem/biogeochemical model system, which includes multiple phytoplankton functional groups and carbon cycle dynamics, and applied it to investigate physical-biological interactions in Icelandic waters. Satellite and in situ data were used to evaluate the model. Surface seasonal cycle amplitudes and biases of key parameters (DIC, TA, pCO2, air-sea CO2 flux, and nutrients) are significantly improved when compared to surface observations by prescribing deep water values and trends, based on available data. The seasonality of the coccolithophore and "other phytoplankton" (diatoms and dinoflagellates) blooms is in general agreement with satellite ocean color products. Nutrient supply, biomass and calcite concentrations are modulated by light and mixed layer depth seasonal cycles. Diatoms are the most abundant phytoplankton, with a large bloom in early spring and a secondary bloom in fall. The diatom bloom is followed by blooms of dinoflagellates and coccolithophores. The effect of biological changes on the seasonal variability of the surface ocean pCO2 is nearly twice the temperature effect, in agreement with previous studies. The inclusion of multiple phytoplankton functional groups in the model played a major role in the accurate representation of CO2 uptake by biology. For instance, at the peak of the bloom, the exclusion of coccolithophores causes an increase in alkalinity of up to 4 µmol kg(sup -1) with a corresponding increase in DIC of up to 16 µmol kg(sup -1). During the peak of the bloom in summer, the net effect of the absence of the coccolithophores bloom is an increase in pCO2 of more than 20 µatm and a reduction of atmospheric CO2 uptake of more than 6 mmolm(sup -2) d(sup -1). On average, the impact of coccolithophores is an increase of air-sea CO2 flux of about 27 %. Considering the areal extent of the bloom from satellite images within the Irminger and Icelandic Basins, this reduction translates into an annual mean of nearly 1500

Remote sensing observations of phytoplankton increases triggered by successive typhoons

Science.gov (United States)

Huang, Lei; Zhao, Hui; Pan, Jiayi; Devlin, Adam

2017-12-01

Phytoplankton blooms in the Western North Pacific, triggered by two successive typhoons with different intensities and translation speeds under different pre-existing oceanic conditions, were observed and analyzed using remotely sensed chlorophyll-a (Chl-a), sea surface temperature (SST), and sea surface height anomaly (SSHA) data, as well as typhoon parameters and CTD (conductivity, temperature, and depth) profiles. Typhoon Sinlaku, with relatively weaker intensity and slower translation speed, induced a stronger phytoplankton bloom than Jangmi with stronger intensity and faster translation speed (Chl-a>0.18 mg·m‒3 versus Chl-aTaiwan Island. Translation speed may be one of the important mechanisms that affect phytoplankton blooms in the study area. Pre-existing cyclonic circulations provided a relatively unstable thermodynamic structure for Sinlaku, and therefore cold water with rich nutrients could be brought up easily. The mixed-layer deepening caused by Typhoon Sinlaku, which occurred first, could have triggered an unfavorable condition for the phytoplankton bloom induced by Typhoon Jangmi which followed afterwards. The sea surface temperature cooling by Jangmi was suppressed due to the presence of the thick upper-ocean mixed-layer, which prevented the deeper cold water from being entrained into the upper-ocean mixed layer, leading to a weaker phytoplankton augment. The present study suggests that both wind (including typhoon translation speed and intensity) and pre-existing conditions (e.g., mixed-layer depths, eddies, and nutrients) play important roles in the strong phytoplankton bloom, and are responsible for the stronger phytoplankton bloom after Sinlaku's passage than that after Jangmi's passage. A new typhoon-influencing parameter is introduced that combines the effects of the typhoon forcing (including the typhoon intensity and translation speed) and the oceanic pre-condition. This parameter shows that the forcing effect of Sinlaku was stronger than
Phytoplankton blooms induced/sustained by cyclonic eddies during the Indian Ocean Dipole event of 1997 along the southern coasts of Java and Sumatra

Science.gov (United States)

Reddy, P. Rahul Chand; Salvekar, P. S.

2008-09-01

The Indonesian archipelago is the gateway in the tropics connecting two oceans (Pacific and the Indian Ocean) and two continents (Asia and Australia). During the Indian Ocean Dipole 1997, record anomalous and unanticipated upwelling had occurred along the southern coasts of Java and Sumatra causing massive phytoplankton blooms. But the method/mode/process for such anomalous upwelling was not known. Using monthly SeaWifs chlorophyll-a anomalies, TOPEX Sea Surface Height (SSH) anomalies, Sea Surface Temperatures (SST) and currents from a state-of-the-art OGCM, we report the presence of a series of cyclonic eddies along southern coasts of Sumatra and Java during November, December 1997 and January 1998. Upwelling caused by these cyclonic eddies, as also supported by the SSH and SST anomalies, has been responsible for the phytoplankton blooms to persist and dissipate during the 3 months (November, December 1997 and January 1998).
Competition for inorganic and organic forms of nitrogen and phosphorous between phytoplankton and bacteria during an Emiliania huxleyi spring bloom

Directory of Open Access Journals (Sweden)

V. Martin-Jézéquel

2008-03-01

Full Text Available Using 15N and 33P, we measured the turnover of organic and inorganic nitrogen (N and phosphorus (P substrates, and the partitioning of N and P from these sources into two size fractions of marine osmotrophs during the course of a phytoplankton bloom in a nutrient manipulated mesocosm. The larger size fraction (>0.8 μm, mainly consisting of the coccolithophorid Emiliania huxleyi, but also including an increasing amount of large particle-associated bacteria as the bloom proceeded, dominated uptake of the inorganic forms NH4+, NO3−, and PO43−. The uptake of N from leucine, and P from ATP and dissolved DNA, was initially dominated by the 0.8–0.2 μm size fraction, but shifted towards dominance by the >0.8 μm size fraction as the system turned to an increasing degree of N-deficiency. Normalizing uptake to biomass of phytoplankton and heterotrophic bacteria revealed that organisms in the 0.8–0.2 μm size fraction had higher specific affinity for leucine-N than those in the >0.8 μm size fraction when N was deficient, whereas the opposite was the case for NH4+. There was no such difference regarding the specific affinity for P substrates. Since heterotrophic bacteria seem to acquire N from organic compounds like leucine more efficiently than phytoplankton, our results suggest different structuring of the microbial food chain in N-limited relative to P-limited environments.
Impacts of sea ice retreat, thinning, and melt-pond proliferation on the summer phytoplankton bloom in the Chukchi Sea, Arctic Ocean

Science.gov (United States)

Palmer, Molly A.; Saenz, Benjamin T.; Arrigo, Kevin R.

2014-07-01

In 2011, a massive phytoplankton bloom was observed in the Chukchi Sea under first-year sea ice (FYI), an environment in which primary productivity (PP) has historically been low. In this paper, we use a 1-D biological model of the Chukchi shelf ecosystem, in conjunction with in situ chemical and physiological data, to better understand the conditions that facilitated the development of such an unprecedented bloom. In addition, to assess the effects of changing Arctic environmental conditions on net PP (NPP), we perform model runs with varying sea ice and snow thickness, timing of melt, melt ponds, and biological parameters. Results from model runs with conditions similar to 2011 indicate that first-year ice (FYI) with at least 10% melt pond coverage transmits sufficient light to support the growth of shade-adapted Arctic phytoplankton. Increasing pond fraction by 20% enhanced peak under-ice NPP by 26% and produced rates more comparable to those measured during the 2011 bloom, but there was no effect of further increasing pond fraction. One of the important consequences of large under-ice blooms is that they consume a substantial fraction of surface nutrients such that NPP is greatly diminished in the marginal ice zone (MIZ) following ice retreat, where NPP has historically been the highest. In contrast, in model runs with ultraviolet radiation and zooplankton grazers reduce peak open water NPP but have little impact on under-ice NPP, which has important implications for the relative proportion of NPP concentrated in pelagic vs. benthic food webs. Finally, the shift in the relative amount of NPP occurring in under-ice vs. open-water environments may affect total ecosystem productivity.
Uncertainty Analysis of Phytoplankton Dynamics in Coastal Waters

NARCIS (Netherlands)

Niu, L.

2015-01-01

There is an increasing concern about the interactions between phytoplankton and coastal ecosystems, especially on the negative effects from coastal eutrophication and phytoplankton blooms. As the key indicator of the coastal ecosystem, phytoplankton plays an important role in the whole impact-effect
Hydrodynamic control of microphytoplankton bloom in a coastal sea

Science.gov (United States)

Murty, K. Narasimha; Sarma, Nittala S.; Pandi, Sudarsana Rao; Chiranjeevulu, Gundala; Kiran, Rayaprolu; Muralikrishna, R.

2017-08-01

The influence of hydrodynamics on phytoplankton bloom occurrence/formation has not been adequately reported. Here, we document diurnal observations in the tropical Bay of Bengal's mid-western shelf region which reveal microphytoplankton cell density maxima in association with neap tide many times more than what could be accounted for by solar insolation and nutrient levels. When in summer, phytoplankton cells were abundant and the cell density of Guinardia delicatula reached critical value by tide caused zonation, aggregation happened to an intense bloom. Mucilaginous exudates from the alga due to heat and silicate stress likely promoted and stable water column and weak winds left undisturbed, the transient bloom. The phytoplankton aggregates have implication as food resource in the benthic region implying higher fishery potential, in carbon dioxide sequestration (carbon burial) and in efforts towards improving remote sensing algorithms for chlorophyll in the coastal region.
The dynamics of temperature and light on the growth of phytoplankton.

Science.gov (United States)

Chen, Ming; Fan, Meng; Liu, Rui; Wang, Xiaoyu; Yuan, Xing; Zhu, Huaiping

2015-11-21

Motivated by some lab and field observations of the hump shaped effects of water temperature and light on the growth of phytoplankton, a bottom-up nutrient phytoplankton model, which incorporates the combined effects of temperature and light, is proposed and analyzed to explore the dynamics of phytoplankton bloom. The population growth model reasonably captures such observed dynamics qualitatively. An ecological reproductive index is defined to characterize the growth of the phytoplankton which also allows a comprehensive analysis of the role of temperature and light on the growth and reproductive characteristics of phytoplankton in general. The model provides a framework to study the mechanisms of phytoplankton dynamics in shallow lake and may even be employed to study the controlled phytoplankton bloom. Copyright © 2015 Elsevier Ltd. All rights reserved.
The role of phytoplankton dynamics in the seasonal and interannual variability of carbon in the subpolar North Atlantic – a modeling study

Directory of Open Access Journals (Sweden)

S. R. Signorini

2012-05-01

Full Text Available We developed an ecosystem/biogeochemical model system, which includes multiple phytoplankton functional groups and carbon cycle dynamics, and applied it to investigate physical-biological interactions in Icelandic waters. Satellite and in situ data were used to evaluate the model. Surface seasonal cycle amplitudes and biases of key parameters (DIC, TA, pCO₂, air-sea CO₂ flux, and nutrients are significantly improved when compared to surface observations by prescribing deep water values and trends, based on available data. The seasonality of the coccolithophore and "other phytoplankton" (diatoms and dinoflagellates blooms is in general agreement with satellite ocean color products. Nutrient supply, biomass and calcite concentrations are modulated by light and mixed layer depth seasonal cycles. Diatoms are the most abundant phytoplankton, with a large bloom in early spring and a secondary bloom in fall. The diatom bloom is followed by blooms of dinoflagellates and coccolithophores. The effect of biological changes on the seasonal variability of the surface ocean pCO₂ is nearly twice the temperature effect, in agreement with previous studies. The inclusion of multiple phytoplankton functional groups in the model played a major role in the accurate representation of CO₂ uptake by biology. For instance, at the peak of the bloom, the exclusion of coccolithophores causes an increase in alkalinity of up to 4 μmol kg⁻¹ with a corresponding increase in DIC of up to 16 μmol kg⁻¹. During the peak of the bloom in summer, the net effect of the absence of the coccolithophores bloom is an increase in pCO₂ of more than 20 μatm and a reduction of atmospheric CO₂ uptake of more than 6 mmol m⁻² d⁻¹. On average, the impact of coccolithophores is an increase of air-sea CO₂ flux of about 27%. Considering the areal
Dynamics of phytoplankton blooms in turbulent vortex cells

DEFF Research Database (Denmark)

Lindemann, Christian; Visser, Andre; Mariani, Patrizio

2017-01-01

the effects of turbulent transport on the phytoplankton population growth and its spatial structure in a vertical two-dimensional vortex flow field. In particular, we focus on how turbulent flow velocities and sinking influence phytoplankton growth and biomass aggregation. Our results indicate that conditions...... can be maintained with increasing turbulent flow velocities, allowing the apparently counter-intuitive persistence of fast sinking phytoplankton populations in highly turbulent and deep mixed layers. These dynamics demonstrate the role of considering advective transport within a turbulent vortex...
Deep-Learning-Based Approach for Prediction of Algal Blooms

Directory of Open Access Journals (Sweden)

Feng Zhang

2016-10-01

Full Text Available Algal blooms have recently become a critical global environmental concern which might put economic development and sustainability at risk. However, the accurate prediction of algal blooms remains a challenging scientific problem. In this study, a novel prediction approach for algal blooms based on deep learning is presented—a powerful tool to represent and predict highly dynamic and complex phenomena. The proposed approach constructs a five-layered model to extract detailed relationships between the density of phytoplankton cells and various environmental parameters. The algal blooms can be predicted by the phytoplankton density obtained from the output layer. A case study is conducted in coastal waters of East China using both our model and a traditional back-propagation neural network for comparison. The results show that the deep-learning-based model yields better generalization and greater accuracy in predicting algal blooms than a traditional shallow neural network does.
Impacts of warming on phytoplankton abundance and phenology in a typical tropical marine ecosystem

KAUST Repository

Gittings, John; Raitsos, Dionysios E.; Krokos, George; Hoteit, Ibrahim

2018-01-01

In the tropics, thermal stratification (during warm conditions) may contribute to a shallowing of the mixed layer above the nutricline and a reduction in the transfer of nutrients to the surface lit-layer, ultimately limiting phytoplankton growth. Using remotely sensed observations and modelled datasets, we study such linkages in the northern Red Sea (NRS) - a typical tropical marine ecosystem. We assess the interannual variability (1998-2015) of both phytoplankton biomass and phenological indices (timing of bloom initiation, duration and termination) in relation to regional warming. We demonstrate that warmer conditions in the NRS are associated with substantially weaker winter phytoplankton blooms, which initiate later, terminate earlier and are shorter in their overall duration (~ 4 weeks). These alterations are directly linked with the strength of atmospheric forcing (air-sea heat fluxes) and vertical stratification (mixed layer depth [MLD]). The interannual variability of sea surface temperature (SST) is found to be a good indicator of phytoplankton abundance, but appears to be less important for predicting bloom timing. These findings suggest that future climate warming scenarios may have a two-fold impact on phytoplankton growth in tropical marine ecosystems: 1) a reduction in phytoplankton abundance and 2) alterations in the timing of seasonal phytoplankton blooms.
Impacts of warming on phytoplankton abundance and phenology in a typical tropical marine ecosystem

KAUST Repository

Gittings, John

2018-01-29

In the tropics, thermal stratification (during warm conditions) may contribute to a shallowing of the mixed layer above the nutricline and a reduction in the transfer of nutrients to the surface lit-layer, ultimately limiting phytoplankton growth. Using remotely sensed observations and modelled datasets, we study such linkages in the northern Red Sea (NRS) - a typical tropical marine ecosystem. We assess the interannual variability (1998-2015) of both phytoplankton biomass and phenological indices (timing of bloom initiation, duration and termination) in relation to regional warming. We demonstrate that warmer conditions in the NRS are associated with substantially weaker winter phytoplankton blooms, which initiate later, terminate earlier and are shorter in their overall duration (~ 4 weeks). These alterations are directly linked with the strength of atmospheric forcing (air-sea heat fluxes) and vertical stratification (mixed layer depth [MLD]). The interannual variability of sea surface temperature (SST) is found to be a good indicator of phytoplankton abundance, but appears to be less important for predicting bloom timing. These findings suggest that future climate warming scenarios may have a two-fold impact on phytoplankton growth in tropical marine ecosystems: 1) a reduction in phytoplankton abundance and 2) alterations in the timing of seasonal phytoplankton blooms.
The Gulf of Aden Intermediate Water Intrusion Regulates the Southern Red Sea Summer Phytoplankton Blooms

KAUST Repository

Dreano, Denis; Raitsos, Dionysios E.; Gittings, John; Krokos, George; Hoteit, Ibrahim

2017-01-01

Knowledge on large-scale biological processes in the southern Red Sea is relatively limited, primarily due to the scarce in situ, and satellite-derived chlorophyll-a (Chl-a) datasets. During summer, adverse atmospheric conditions in the southern Red Sea (haze and clouds) have long severely limited the retrieval of satellite ocean colour observations. Recently, a new merged ocean colour product developed by the European Space Agency (ESA)-the Ocean Color Climate Change Initiative (OC-CCI)-has substantially improved the southern Red Sea coverage of Chl-a, allowing the discovery of unexpected intense summer blooms. Here we provide the first detailed description of their spatiotemporal distribution and report the mechanisms regulating them. During summer, the monsoon-driven wind reversal modifies the circulation dynamics at the Bab-el-Mandeb strait, leading to a subsurface influx of colder, fresher, nutrient-rich water from the Indian Ocean. Using satellite observations, model simulation outputs, and in situ datasets, we track the pathway of this intrusion into the extensive shallow areas and coral reef complexes along the basin's shores. We also provide statistical evidence that the subsurface intrusion plays a key role in the development of the southern Red Sea phytoplankton blooms.
The Gulf of Aden Intermediate Water Intrusion Regulates the Southern Red Sea Summer Phytoplankton Blooms.

Science.gov (United States)

Dreano, Denis; Raitsos, Dionysios E; Gittings, John; Krokos, George; Hoteit, Ibrahim

2016-01-01

Knowledge on large-scale biological processes in the southern Red Sea is relatively limited, primarily due to the scarce in situ, and satellite-derived chlorophyll-a (Chl-a) datasets. During summer, adverse atmospheric conditions in the southern Red Sea (haze and clouds) have long severely limited the retrieval of satellite ocean colour observations. Recently, a new merged ocean colour product developed by the European Space Agency (ESA)-the Ocean Color Climate Change Initiative (OC-CCI)-has substantially improved the southern Red Sea coverage of Chl-a, allowing the discovery of unexpected intense summer blooms. Here we provide the first detailed description of their spatiotemporal distribution and report the mechanisms regulating them. During summer, the monsoon-driven wind reversal modifies the circulation dynamics at the Bab-el-Mandeb strait, leading to a subsurface influx of colder, fresher, nutrient-rich water from the Indian Ocean. Using satellite observations, model simulation outputs, and in situ datasets, we track the pathway of this intrusion into the extensive shallow areas and coral reef complexes along the basin's shores. We also provide statistical evidence that the subsurface intrusion plays a key role in the development of the southern Red Sea phytoplankton blooms.
The Gulf of Aden Intermediate Water Intrusion Regulates the Southern Red Sea Summer Phytoplankton Blooms

KAUST Repository

Dreano, Denis

2017-01-09

Knowledge on large-scale biological processes in the southern Red Sea is relatively limited, primarily due to the scarce in situ, and satellite-derived chlorophyll-a (Chl-a) datasets. During summer, adverse atmospheric conditions in the southern Red Sea (haze and clouds) have long severely limited the retrieval of satellite ocean colour observations. Recently, a new merged ocean colour product developed by the European Space Agency (ESA)-the Ocean Color Climate Change Initiative (OC-CCI)-has substantially improved the southern Red Sea coverage of Chl-a, allowing the discovery of unexpected intense summer blooms. Here we provide the first detailed description of their spatiotemporal distribution and report the mechanisms regulating them. During summer, the monsoon-driven wind reversal modifies the circulation dynamics at the Bab-el-Mandeb strait, leading to a subsurface influx of colder, fresher, nutrient-rich water from the Indian Ocean. Using satellite observations, model simulation outputs, and in situ datasets, we track the pathway of this intrusion into the extensive shallow areas and coral reef complexes along the basin\\'s shores. We also provide statistical evidence that the subsurface intrusion plays a key role in the development of the southern Red Sea phytoplankton blooms.
Individual Cell Based Traits Obtained by Scanning Flow-Cytometry Show Selection by Biotic and Abiotic Environmental Factors during a Phytoplankton Spring Bloom

Science.gov (United States)

Pomati, Francesco; Kraft, Nathan J. B.; Posch, Thomas; Eugster, Bettina; Jokela, Jukka; Ibelings, Bas W.

2013-01-01

In ecology and evolution, the primary challenge in understanding the processes that shape biodiversity is to assess the relationship between the phenotypic traits of organisms and the environment. Here we tested for selection on physio-morphological traits measured by scanning flow-cytometry at the individual level in phytoplankton communities under a temporally changing biotic and abiotic environment. Our aim was to study how high-frequency temporal changes in the environment influence biodiversity dynamics in a natural community. We focused on a spring bloom in Lake Zurich (Switzerland), characterized by rapid changes in phytoplankton, water conditions, nutrients and grazing (mainly mediated by herbivore ciliates). We described bloom dynamics in terms of taxonomic and trait-based diversity and found that diversity dynamics of trait-based groups were more pronounced than those of identified phytoplankton taxa. We characterized the linkage between measured phytoplankton traits, abiotic environmental factors and abundance of the main grazers and observed weak but significant correlations between changing abiotic and biotic conditions and measured size-related and fluorescence-related traits. We tested for deviations in observed community-wide distributions of focal traits from random patterns and found evidence for both clustering and even spacing of traits, occurring sporadically over the time series. Patterns were consistent with environmental filtering and phenotypic divergence under herbivore pressure, respectively. Size-related traits showed significant even spacing during the peak of herbivore abundance, suggesting that morphology-related traits were under selection from grazing. Pigment distribution within cells and colonies appeared instead to be associated with acclimation to temperature and water chemistry. We found support for trade-offs among grazing resistance and environmental tolerance traits, as well as for substantial periods of dynamics in which
Nutrients and toxin producing phytoplankton control algal blooms

Indian Academy of Sciences (India)

A phytoplankton-zooplankton prey-predator model has been investigated for temporal, spatial and spatio-temporal dissipative pattern formation in a deterministic and noisy environment, respectively. The overall carrying capacity for the phytoplankton population depends on the nutrient level. The role of nutrient ...
In situ phytoplankton distributions in the Amundsen Sea Polynya measured by autonomous gliders

Directory of Open Access Journals (Sweden)

Oscar Schofield

2015-10-01

Full Text Available Abstract The Amundsen Sea Polynya is characterized by large phytoplankton blooms, which makes this region disproportionately important relative to its size for the biogeochemistry of the Southern Ocean. In situ data on phytoplankton are limited, which is problematic given recent reports of sustained change in the Amundsen Sea. During two field expeditions to the Amundsen Sea during austral summer 2010–2011 and 2014, we collected physical and bio-optical data from ships and autonomous underwater gliders. Gliders documented large phytoplankton blooms associated with Antarctic Surface Waters with low salinity surface water and shallow upper mixed layers (< 50 m. High biomass was not always associated with a specific water mass, suggesting the importance of upper mixed depth and light in influencing phytoplankton biomass. Spectral optical backscatter and ship pigment data suggested that the composition of phytoplankton was spatially heterogeneous, with the large blooms dominated by Phaeocystis and non-bloom waters dominated by diatoms. Phytoplankton growth rates estimated from field data (≤ 0.10 day−1 were at the lower end of the range measured during ship-based incubations, reflecting both in situ nutrient and light limitations. In the bloom waters, phytoplankton biomass was high throughout the 50-m thick upper mixed layer. Those biomass levels, along with the presence of colored dissolved organic matter and detritus, resulted in a euphotic zone that was often < 10 m deep. The net result was that the majority of phytoplankton were light-limited, suggesting that mixing rates within the upper mixed layer were critical to determining the overall productivity; however, regional productivity will ultimately be controlled by water column stability and the depth of the upper mixed layer, which may be enhanced with continued ice melt in the Amundsen Sea Polynya.
Seasonal variations of phytoplankton dynamics in Nunatsiavut fjords (Labrador, Canada) and their relationships with environmental conditions

Science.gov (United States)

Simo-Matchim, Armelle-Galine; Gosselin, Michel; Blais, Marjolaine; Gratton, Yves; Tremblay, Jean-Éric

2016-04-01

We assessed phytoplankton dynamics and its environmental control in four Labrador fjords (Nachvak, Saglek, Okak, and Anaktalak) during summer, early fall and late fall. Primary production and chlorophyll a (chl a) biomass were measured at seven optical depths, including the depth of subsurface chl a maximum (SCM). Phytoplankton abundance, size structure and taxonomy were determined at the SCM. Principal component analysis and non-metric multidimensional scaling were used to analyze relationships between production, biomass and community composition in relation to environmental variables. We observed a marked seasonal variability, with significant differences in phytoplankton structure and function between summer and fall. Surprisingly, primary production and chl a biomass were not significantly different from one fjord to another. The highest values of primary production (1730 mg C m- 2 day- 1) and chl a biomass (96 mg chl a m- 2) were measured during the summer bloom, and those high values indicate that Labrador fjords are highly productive ecosystems. The summer community showed relatively high abundance of nanophytoplankton (2-20 μm) while the fall community was characterized by low primary production and chl a biomass as well as relatively high abundance of picophytoplankton (< 2 μm). The low value of carbon potentially exported out of the euphotic zone throughout the study (≤ 31% of total primary production) suggests that phytoplankton production was mainly grazed by microzooplankton rather than being exported to greater depths. We observed a mixed assemblage of diatoms and flagellates in summer, whereas the fall community was largely dominated by flagellates. Seasonal variations in phytoplankton dynamics were mainly controlled by the strength of the vertical stratification and by the large differences in day length due to the northerly location of Labrador fjords. This study documents for the very first time phytoplankton structure and function in
Remote Sensing Marine Ecology: Wind-driven algal blooms in the open oceans and their ecological impacts

Science.gov (United States)

Tang, DanLing

2016-07-01

Algal bloom not only can increase the primary production but also could result in negative ecological consequence, e.g., Harmful Algal Blooms (HABs). According to the classic theory for the formation of algal blooms "critical depth" and "eutrophication", oligotrophic sea area is usually difficult to form a large area of algal blooms, and actually the traditional observation is only sporadic capture to the existence of algal blooms. Taking full advantage of multiple data of satellite remote sensing, this study: 1), introduces "Wind-driven algal blooms in open oceans: observation and mechanisms" It explained except classic coastal Ekman transport, the wind through a variety of mechanisms affecting the formation of algal blooms. Proposed a conceptual model of "Strong wind -upwelling-nutrient-phytoplankton blooms" in Western South China Sea (SCS) to assess role of wind-induced advection transport in phytoplankton bloom formation. It illustrates the nutrient resources that support long-term offshore phytoplankton blooms in the western SCS; 2), Proposal of the theory that "typhoons cause vertical mixing, induce phytoplankton blooms", and quantify their important contribution to marine primary production; Proposal a new ecological index for typhoon. Proposed remote sensing inversion models. 3), Finding of the spatial and temporaldistributions pattern of harmful algal bloom (HAB)and species variations of HAB in the South Yellow Sea and East China Sea, and in the Pearl River estuary, and their oceanic dynamic mechanisms related with monsoon; The project developed new techniques and generated new knowledge, which significantly improved understanding of the formation mechanisms of algal blooms. 1), It proposed "wind-pump" mechanism integrates theoretical system combing "ocean dynamics, development of algal blooms, and impact on primary production", which will benefit fisheries management. 2), A new interdisciplinary subject "Remote Sensing Marine Ecology"(RSME) has been

DMSP synthesis and exudation in phytoplankton : a modeling approach

NARCIS (Netherlands)

Laroche, D; Vézina, A.F; Levasseur, M; Gosselin, M; Stefels, J.; Keller, M.D; Matrai, P.A; Kwint, R.L J

1999-01-01

In the marine environment, phytoplankton are the fundamental producers of dimethylsulfoniopropionate (DMSP), the precursor of the climatically active gas dimethylsulfide (DMS). DMSP is released by exudation, cell autolysis, and zooplankton grazing during phytoplankton blooms. In this study, we
Harmful Freshwater Algal Blooms, With an Emphasis on Cyanobacteria

Directory of Open Access Journals (Sweden)

Hans W. Paerl

2001-01-01

Full Text Available Suspended algae, or phytoplankton, are the prime source of organic matter supporting food webs in freshwater ecosystems. Phytoplankton productivity is reliant on adequate nutrient supplies; however, increasing rates of nutrient supply, much of it manmade, fuels accelerating primary production or eutrophication. An obvious and problematic symptom of eutrophication is rapid growth and accumulations of phytoplankton, leading to discoloration of affected waters. These events are termed blooms. Blooms are a prime agent of water quality deterioration, including foul odors and tastes, deoxygenation of bottom waters (hypoxia and anoxia, toxicity, fish kills, and food web alterations. Toxins produced by blooms can adversely affect animal (including human health in waters used for recreational and drinking purposes. Numerous freshwater genera within the diverse phyla comprising the phytoplankton are capable of forming blooms; however, the blue-green algae (or cyanobacteria are the most notorious bloom formers. This is especially true for harmful toxic, surface-dwelling, scum-forming genera (e.g., Anabaena, Aphanizomenon, Nodularia, Microcystis and some subsurface bloom-formers (Cylindrospermopsis, Oscillatoria that are adept at exploiting nutrient-enriched conditions. They thrive in highly productive waters by being able to rapidly migrate between radiance-rich surface waters and nutrient-rich bottom waters. Furthermore, many harmful species are tolerant of extreme environmental conditions, including very high light levels, high temperatures, various degrees of desiccation, and periodic nutrient deprivation. Some of the most noxious cyanobacterial bloom genera (e.g., Anabaena, Aphanizomenon, Cylindrospermopsis, Nodularia are capable of fixing atmospheric nitrogen (N2, enabling them to periodically dominate under nitrogen-limited conditions. Cyanobacteria produce a range of organic compounds, including those that are toxic to higher-ranked consumers, from
Timing of migratory baleen whales at the Azores in relation to the North Atlantic spring bloom

NARCIS (Netherlands)

Visser, F.; Hartman, K.L.; Pierce, G.J.; Valavanis, V.D.; Huisman, J.

2011-01-01

Each year, a phytoplankton spring bloom starts just north of the North Atlantic Subtropical Gyre, and then expands northwards across the entire North Atlantic. Here, we investigate whether the timing of the spring migration of baleen whales is related to the timing of the phytoplankton spring bloom,
Harmful Algal Blooms of the West Florida Shelf and Campeche Bank: Visualization and Quantification using Remote Sensing Methods

Science.gov (United States)

Soto Ramos, Inia Mariel

% false negatives, similar to those from more complex techniques. The first chapter concludes with a series of recommendations on how to improve the detection techniques and how to take these results a step further into a Gulf wide observing systems for HABs. In chapter two, ocean color techniques were used to examine the extension, evolution and displacement of four Karenia spp. events that occurred in the WFS between 2004 and 2011. Blooms were identified in the imagery using the new Rrs-FLH method and validated using in situ phytoplankton cell counts. The spatial extension of each event was followed in time by delineating the blooms. In 2004 and 2005, the WFS was affected by a series of hurricanes that led to high river discharge and intense sediment resuspension events. Both processes had an impact on HAB occurrence. For example, I tracked a Karenia spp. bloom found in late December 2004 approximately 40-80 km offshore Saint Petersburg, which then expanded reaching an extension of >8000 km2 in February 2005. The bloom weakened in spring 2005 and intensified again in summer reaching >42,000 km 2 after the passage of hurricane Katrina in August 2005. This bloom covered the WFS from Charlotte Harbor to the Florida Panhandle. Two other cases were studied in the WFS. The results of the Hybrid Coordinate Ocean Model from the U.S. Navy aid understanding the dispersal of the blooms. During fall 2011, three field campaigns to study HABs in Mexico were conducted to do an analysis of optical properties and explore the possibility of using ocean color techniques to distinguish between the main phytoplankton blooms in that region. Three main bloom scenarios were observed in the Campeche Bank region: massive diatom blooms, blooms dominated by Scrippsiella spp., and Karenia spp. blooms. The normalized specific phytoplankton absorption spectra were found to be different for Karenia spp. and Scrippsiella sp. blooms. A new technique that combines phytoplankton absorption derived from
Deep carbon export from a Southern Ocean iron-fertilized diatom bloom

Digital Repository Service at National Institute of Oceanography (India)

Smetacek, V.; Klaas, C.; Strass, V.H.; Assmy, P.; Montresor, M.; Cisewski, B.; Savoye, N.; Webb, A.; d’Ovidio, F.; Arrieta, J.M.; Bathmann, U.; Bellerby, R.; Berg, G.M.; Croot, P.; Gonzalez, S.; Henjes, J.; Herndl, G.J.; Hoffmann, L.J.; Leach, H.; Losch, M.; Mills, M.M.; Neill, C.; Peeken, I.; Rottgers, R.; Sachs, O.; Sauter, E.; Schmidt, M.M.; Schwarz, J.; Terbruggen, A.; Wolf-Gladrow, D.

Fertilization of the ocean by adding iron compounds has induced diatom-dominated phytoplankton blooms accompanied by considerable carbon dioxide drawdown in the ocean surface layer. However, because the fate of bloom biomass could not be adequately...
The community composition and production of phytoplankton in fish pens of Cape Bolinao, Pangasinan: a field study

International Nuclear Information System (INIS)

Yap, Leni G.; Azanza, Rhodora V.; Talaue-McManus, Liana

2004-01-01

From 1995 up to the present, fish pens proliferated in the municipal waters of Bolinao, northern Philippines. Since then, fish kills and phytoplankton blooms have been recurrent. Have fishpens altered the phytoplankton community composition and production of these waters? The phytoplankton community in Cape Bolinao, Lingayen Gulf is typical of a tropical coastal area where diatoms alternate with dinoflagellates during the dry and wet seasons. In the nutrient-rich fish pens, phytoplankton in this study showed a lower diatom/dinoflagellate ratio and unusually high phytoplankton counts of 10 4 cells/l and even as high as 10 5 cells/l. Correlations between physico-chemical parameters, phytoplankton production and community composition were made in 2001. This paper tried to explain the occurrence of a Cylindrotheca closterium bloom (10 5 cells/l), during the dry season of the same year and a Prorocentrum minimum bloom (4.7 x 10 5 cells/l), which accompanied a massive fish kill during January 2002
Phytoplankton Assemblage Patterns in the Southern Mid-Atlantic Bight

Science.gov (United States)

Makinen, Carla; Moisan, Tiffany A. (Editor)

2012-01-01

As part of the Wallops Coastal Oceans Observing Laboratory (Wa-COOL) Project, we sampled a time-series transect in the southern Mid-Atlantic Bight (MAB) biweekly. Our 2-year time-series data included physical parameters, nutrient concentrations, and chlorophyll a concentrations. A detailed phytoplankton assemblage structure was examined in the second year. During the 2-year study, chlorophyll a concentration (and ocean color satellite imagery) indicated that phytoplankton blooms occurred in January/February during mixing conditions and in early autumn under stratified conditions. The chlorophyll a concentrations ranged from 0.25 microgram 1(exp -1) to 15.49 microgram 1(exp -1) during the 2-year period. We were able to discriminate approximately 116 different species under phase contrast microscopy. Dominant phytoplankton included Skeletonema costatum, Rhizosolenia spp., and Pseudo-nitzschia pungens. In an attempt to determine phytoplankton species competition/succession within the assemblage, we calculated a Shannon Weaver diversity index for our diatom microscopy data. Diatom diversity was greatest during the winter and minimal during the spring. Diatom diversity was also greater at nearshore stations than at offshore stations. Individual genera appeared patchy, with surface and subsurface patches appearing abruptly and persisting for only 1-2 months at a time. The distribution of individual species differed significantly from bulk variables of the assemblage (chlorophyll a ) and total phytoplankton assemblage (cells), which indicates that phytoplankton species may be limited in growth in ways that differ from those of the total assemblage. Our study demonstrated a highly diverse phytoplankton assemblage throughout the year, with opportunistic species dominating during spring and fall in response to seasonal changes in temperature and nutrients in the southern MAB.
Influence of the Phytoplankton Community Structure on the Spring and Annual Primary Production in the Northwestern Mediterranean Sea

Science.gov (United States)

Mayot, Nicolas; D'Ortenzio, Fabrizio; Uitz, Julia; Gentili, Bernard; Ras, Joséphine; Vellucci, Vincenzo; Golbol, Melek; Antoine, David; Claustre, Hervé

2017-12-01

Satellite ocean color observations revealed that unusually deep convection events in 2005, 2006, 2010, and 2013 led to an increased phytoplankton biomass during the spring bloom over a large area of the northwestern Mediterranean Sea (NWM). Here we investigate the effects of these events on the seasonal phytoplankton community structure, we quantify their influence on primary production, and we discuss the potential biogeochemical impact. For this purpose, we compiled in situ phytoplankton pigment data from five ship surveys performed in the NWM and from monthly cruises at a fixed station in the Ligurian Sea. We derived primary production rates from a light photosynthesis model applied to these in situ data. Our results confirm that the maximum phytoplankton biomass during the spring bloom is larger in years associated with intense deep convection events (+51%). During these enhanced spring blooms, the contribution of diatoms to total phytoplankton biomass increased (+33%), as well as the primary production rate (+115%). The occurrence of a highly productive bloom is also related to an increase in the phytoplankton bloom area (+155%) and in the relative contribution of diatoms to primary production (+63%). Therefore, assuming that deep convection in the NWM could be significantly weakened by future climate changes, substantial decreases in the spring production of organic carbon and of its export to deep waters can be expected.
Initial growth of phytoplankton in turbid estuaries: a simple model

NARCIS (Netherlands)

de Swart, H.E.; Schuttelaars, H.; Talke, S.A.

2009-01-01

An idealised model is presented and analysed to gain more fundamental understanding about the dynamics of phytoplankton blooms in well-mixed, suspended sediment dominated estuaries. The model describes the behaviour of subtidal currents, suspended sediments, nutrients and phytoplankton in a channel
Distribution of calcifying and silicifying phytoplankton in relation to environmental and biogeochemical parameters during the late stages of the 2005 North East Atlantic Spring Bloom

Directory of Open Access Journals (Sweden)

K. Leblanc

2009-10-01

Full Text Available The late stage of the North East Atlantic (NEA spring bloom was investigated during June 2005 along a transect section from 45 to 66° N between 15 and 20° W in order to characterize the contribution of siliceous and calcareous phytoplankton groups and describe their distribution in relation to environmental factors. We measured several biogeochemical parameters such as nutrients, surface trace metals, algal pigments, biogenic silica (BSi, particulate inorganic carbon (PIC or calcium carbonate, particulate organic carbon, nitrogen and phosphorus (POC, PON and POP, respectively, as well as transparent exopolymer particles (TEP. Results were compared with other studies undertaken in this area since the JGOFS NABE program. Characteristics of the spring bloom generally agreed well with the accepted scenario for the development of the autotrophic community. The NEA seasonal diatom bloom was in the late stages when we sampled the area and diatoms were constrained to the northern part of our transect, over the Icelandic Basin (IB and Icelandic Shelf (IS. Coccolithophores dominated the phytoplankton community, with a large distribution over the Rockall-Hatton Plateau (RHP and IB. The Porcupine Abyssal Plain (PAP region at the southern end of our transect was the region with the lowest biomass, as demonstrated by very low Chla concentrations and a community dominated by picophytoplankton. Early depletion of dissolved silicic acid (DSi and increased stratification of the surface layer most likely triggered the end of the diatom bloom, leading to coccolithophore dominance. The chronic Si deficiency observed in the NEA could be linked to moderate Fe limitation, which increases the efficiency of the Si pump. TEP closely mirrored the distribution of both biogenic silica at depth and prymnesiophytes in the surface layer suggesting the sedimentation of the diatom bloom in the form of aggregates, but the relative contribution of diatoms and
Friend or Foe: Variability in How Sea Ice Can Both Hinder and Enhance Phytoplankton Blooms Across the Southern Ocean

Science.gov (United States)

Rohr, T.

2016-02-01

Globally, a suite of physical and biogeochemical controls govern the structure, size, and timing of seasonal phytoplankton blooms. In the Southern Ocean, the introduction of seasonal sea ice provides an additional constraining factor. From a bottom-up perspective, a reduction in sea ice can both enhance bloom development by permitting greater levels of surface PAR uninhibited by ice and suppress a bloom when reduced fresh melt-water inputs and increased vulnerability to wind stress combine to create deeper mixed layers and decrease depth integrated light availability. Regions along the Western Antarctic Peninsula have already seen a contradictory response to reduced ice cover, with enhanced summertime chlorophyll concentrations in the South, and large declines to the North. This dichotomy is thought to arise from differences in the interannual mean sea ice state, with extensively ice covered regions benefiting from reduced coverage and more sparsely covered regions hindered by further reductions. The questions arises: 1) At what threshold does a reduction in sea ice transition from amplifying blooms to suppressing them? 2) How do additional environmental considerations such as nutrient availability and trophic interactions complicate this transition? Here, we combine remote sensing observations and in-situ data (from PAL LTER) with a hierarchy of 1-D water column and global general circulation (CESM) models to access the variability in how regional differences in mean ice state combine with other environmental forcings to dictate how interannual variability (or long term trends) in ice coverage will affect bloom structure, size and dynamics. In doing so we will gain a better understanding of how predicted changes in sea ice will effect Southern Ocean productivity, which of course will have important consequences in the global carbon cycle and sustainability of healthy marine ecosystems.
Environmental controls on phytoplankton community composition in the Thames plume, U.K.

Science.gov (United States)

Weston, Keith; Greenwood, Naomi; Fernand, Liam; Pearce, David J.; Sivyer, David B.

2008-11-01

The aim of this study was to investigate controls on the phytoplankton community composition and biogeochemistry of the estuarine plume zone of the River Thames, U.K. using an instrumented moored buoy for in situ measurements and preserved sample collection, and laboratory-based measurements from samples collected at the same site. Instrumentation on the moored buoy enabled high frequency measurements of a suite of environmental variables including in situ chlorophyll, water-column integrated irradiance, macronutrients throughout an annual cycle for 2001 e.g. nitrate and silicate, and phytoplankton biomass and species composition. The Thames plume region acts as a conduit for fluvial nutrients into the wider southern North Sea with typical winter concentrations of 45 μM nitrate, 17 μM silicate and 2 μM phosphate measured. The spring bloom resulted from water-column integrated irradiance increasing above 60 W h m - 2 d - 1 and was initially dominated by a diatom bloom mainly composed of Nitzschia sp. and Odontella sinesis. The spring bloom then switched after ˜ 30 days to become dominated by the flagellate Phaeocystis reaching a maximum chlorophyll concentration of 37.8 μg L - 1 . During the spring bloom there were high numbers of the heterotrophic dinoflagellates Gyrodinium spirale and Katodinium glaucum that potentially grazed the phytoplankton bloom. This diatom-flagellate switch was predicted to be due to a combination of further increasing water-column integrated irradiance > 100 W h m - 2 d - 1 and/or silicate reaching potentially limiting concentrations (nutrient and phytoplankton processing and transport to the southern North Sea. The use of a combination of moorings and ship-based sampling was essential in understanding the factors influencing nutrient transport, phytoplankton biomass and species composition in this shelf sea plume region.
Monitoring and prediction of phytoplankton dynamics in the North Sea

NARCIS (Netherlands)

Blauw, A.N.

2015-01-01

Phytoplankton forms the base of the marine food web, but when concentrations get too high, algal blooms can have adverse effects on ecosystems and aquaculture. Phytoplankton concentrations vary strongly in space and time. However, the nature and drivers of this variability are not yet well
Effects of nutrients and zooplankton on the phytoplankton community structure in Marudu Bay

Science.gov (United States)

Tan, Kar Soon; Ransangan, Julian

2017-07-01

Current study was carried out to provide a better understanding on spatial and temporal variations in the phytoplankton community structure in Marudu Bay, an important nursery ground for fishery resources within the Tun Mustapha Marine Park and Coral Triangle Initiative, and their relationship with environmental variables. Samplings were conducted monthly from April 2014 to April 2015 in Marudu Bay, Malaysia. Water samples were collected for nutrients analysis, zooplankton and phytoplankton counting. Moreover, the in situ environmental parameters were also examined. The field study showed a total of forty seven phytoplankton genera, representative of 33 families were identified. The nutrient concentrations in Marudu Bay was low (mesotrophic) throughout the year, where the phytoplankton community was often dominated by Chaetoceros spp. and Bacteriastrum spp. In general, increase in nitrate concentration triggered the bloom of centric diatom, Chaetoceros spp. and Bacteriastrum spp. in Marudu Bay. However, the bloom of these phytoplankton taxa did not occur in the presence of high ammonia concentration. In addition, high abundance of zooplankton also a limiting factor of the phytoplankton blooms particularly at end of southwest monsoon. High silica concentration promoted the growth of pennate diatoms, Proboscia spp. and Thallassionema spp., but the depletion of silica quickly terminated the bloom. Interestingly, our study showed that Chaetoceros spp., tolerated silica depletion condition, but the average cell size of this taxon reduced significantly. In summary, the phytoplankton community structure in mesotrophic environment is more sensitive to the changes in zooplankton abundance, nutrient concentration and its ratio than that in nutrient rich environments. This study also recommends that bivalve farming at industrial scale is not recommended in Marudu Bay because it potentially depletes the primary productivity hence jeopardizing the availability of live food for
Drivers of phytoplankton dynamics in old Tampa Bay, FL (USA), a subestuary lagging in ecosystem recovery

Science.gov (United States)

Corcoran, Alina A.; Wolny, Jennifer; Leone, Erin; Ivey, James; Murasko, Susan

2017-02-01

In the past four decades, consistent and coordinated management actions led to the recovery of Tampa Bay, FL (USA) - an estuary that was declared dead in the 1970s. An exception to this success story is Old Tampa Bay, the northernmost subestuary of the system. Compared to the other bay segments, Old Tampa Bay is characterized by poorer water quality and spring and summer blooms of cyanobacteria, picoplankton, diatoms, and the saxitoxin-producing dinoflagellate Pyrodinium bahamense. Together, these blooms contribute to light attenuation and lagging recovery of seagrass beds. Yet, studies of phytoplankton dynamics within Old Tampa Bay have been limited - both in number and in their spatiotemporal resolution. In this study, we used field sampling and continuous monitoring to (1) characterize temporal and spatial variability in phytoplankton biomass and community composition and (2) identify key drivers of the different phytoplankton blooms in Old Tampa Bay. Overall, temporal variability in phytoplankton biomass (using chlorophyll a as a proxy) and community composition surpassed spatial variability of these parameters. We found a base community of small diatoms and flagellates, as well as certain dinoflagellates, that persisted year round in the system. Seasonally, freshwater runoff stimulated phytoplankton growth, specifically that of chlorophytes, cyanobacteria and other dinoflagellates - consistent with predictions based on ecological theory. On shorter time scales, salinity, visibility, and freshwater inflows were important predictors of phytoplankton biomass. With respect to P. bahamense, environmental drivers including salinity, temperature and dissolved nutrient concentrations explained ∼24% of the variability in cell abundance, indicating missing explanatory parameters in our study for this taxon, such as cyst density and location of cyst beds. Spatially, we found differences in community trajectories across north-south and west-east gradients, with the
Environmental dynamics of red Noctiluca scintillans bloom in tropical coastal waters.

Science.gov (United States)

Baliarsingh, S K; Lotliker, Aneesh A; Trainer, Vera L; Wells, Mark L; Parida, Chandanlal; Sahu, Biraja K; Srichandan, Suchismita; Sahoo, Subhashree; Sahu, K C; Kumar, T Sinivasa

2016-10-15

An intense bloom of red Noctiluca scintillans (NS) occurred off the Rushikulya estuarine region along the east coast of India, an important site for mass nesting events of the vulnerable Olive Ridley sea turtle. At its peak, densities of NS were 3.3×10(5) cells-l(-1), with low relative abundance of other phytoplankton. The peak bloom coincided with high abundance of gelatinous planktivores which may have facilitated bloom development by their grazing on other zooplankton, particularly copepods. Ammonium concentrations increased by approximately 4-fold in the later stages of bloom, coincident with stable NS abundance and chlorophyll concentrations in the nano- and microplankton. This increase likely was attributable to release of intracellular ammonium accumulated through NS grazing. Dissolved oxygen concentrations decreased in sub-surface waters to near hypoxia. Micro-phytoplankton increasingly dominated chlorophyll-a biomass as the bloom declined, with diminishing picoplankton abundance likely the result of high predation by the ciliate Mesodinium rubrum. Together, these data illustrate factors that can disrupt ecosystem balance in this critically important Indian coastal region. Copyright © 2016 Elsevier Ltd. All rights reserved.
Numerical Modeling of the Effects of Nutrient-rich Coastal-water Input on the Phytoplankton in the Gulf of California

Science.gov (United States)

Bermudez, A.; Rivas, D.

2015-12-01

Phytoplankton bloom dynamics depends on the interactions of favorable physical, chemical, and biotic conditions, particularly on the available nutrients that enhance phytoplankton growth, like nitrogen. Costal and estuarine environments are heavily influenced by exogenous sources of nitrogen; the anthropogenic inputs include urban and rural wastewater coming from agricultural activities (i.e., fertilizers and animal waste). In response, new production is often enhanced, leading eutrophication and phytoplankton blooms, including harmful taxa. These events have become more frequent, and with it the interest to evaluate their effects on marine ecosystems and the impact on human health. In the Gulf of California the harmful algal blooms (HABs) had affected aquaculture, fisheries, and even tourism, thereby it is important to generate information about biological and physical factors that can influence their appearance. A numerical model is a tool that may bring key information about the origin and distribution of phytoplankton blooms. Herein the analysis is based on a three-dimensional, hydrodynamical numerical model, coupled to a Nitrogen-Phytoplankton-Zooplankton-Detritus (NPZD) model. Several numerical simulations using different forcing and scenarios are carried out in order to evaluate the processes that influence the phytoplankton growth. These numerical results are compared to available observations. Thus, the main environmental factors triggering the generation of HABs can be identified.
Phytoplankton Regulation in a Eutrophic Tidal River (San Joaquin River, California

Directory of Open Access Journals (Sweden)

Alan D. Jassby

2005-03-01

Full Text Available As in many U.S. estuaries, the tidal San Joaquin River exhibits elevated organic matter production that interferes with beneficial uses of the river, including fish spawning and migration. High phytoplankton biomass in the tidal river is consequently a focus of management strategies. An unusually long and comprehensive monitoring dataset enabled identification of the determinants of phytoplankton biomass. Phytoplankton carrying capacity may be set by nitrogen or phosphorus during extreme drought years but, in most years, growth rate is light-limited. The size of the annual phytoplankton bloom depends primarily on river discharge during late spring and early summer, which determines the cumulative light exposure in transit downstream. The biomass-discharge relationship has shifted over the years, for reasons as yet unknown. Water diversions from the tidal San Joaquin River also affect residence time during passage downstream and may have resulted in more than a doubling of peak concentration in some years. Dam construction and accompanying changes in storage-and-release patterns from upstream reservoirs have caused a long-term decrease in the frequency of large blooms since the early 1980s, but projected climate change favors a future increase. Only large decreases in nonpoint nutrient sources will limit phytoplankton biomass reliably. Growth rate and concentration could increase if nonpoint source management decreases mineral suspensoid load but does not decrease nutrient load sufficiently. Small changes in water storage and release patterns due to dam operation have a major influence on peak phytoplankton biomass, and offer a near-term approach for management of nuisance algal blooms.
Phytoplankton blooms: an overlooked marine source of natural endocrine disrupting chemicals.

Science.gov (United States)

Gong, Yinhan; Wang, Xiaochong; Indran, Inthrani Raja; Zhang, Shi-Jun; Lv, Zhengbing; Li, Jun; Holmes, Michael; Tang, Ying Zhong; Yong, E L

2014-09-01

We had previously reported high androgenic and estrogenic activities in seawaters in confined clusters close to Singapore. Further investigations revealed a hitherto unsuspected link between estrogenic/androgenic activity and net phytoplankton count. The primary objective of this study was to investigate the cause of a correlation between net phytoplankton and endocrine activity, and corroborate this observation, and rule out other possible confounding factors. Our secondary objective was to study if these estrogenic secretions can impact human health. Five species of phytoplankton, Gymnodinium catenatum, Prorocentrum minimum, Alexandrium leei, Chattonella marina, and Fibrocapsa japonica, were isolated from Singapore waters and mass cultured and the cells and culture media screened for estrogenic and androgenic activity using human cell-based bioassays. The raphidophytes C. marina and F. japonica displayed significant estrogenic activity whilst the dinoflagellates G. catenatum and P. minimum displayed significant androgenic activity in both the cell extracts and the cell culture media extract. Our data shows that selected phytoplankton isolates are potent secretors of estrogenic and androgenic substances, which are potential endocrine disrupting chemicals (EDCs). As the harmful nature of EDCs is largely due to their bioaccumulation in the aquatic food chain our findings imply that the impact of these phytoplankton secretions needs to be investigated especially for seafoods, which are only a single trophic level away from phytoplankton. Alternatively, should these phytoplankton-origin EDCs not accumulate through marine food chains to significantly impact humans or marine mammals, our results indicate that functional assays could greatly over-estimate the risk from naturally occurring EDCs produced by marine phytoplankton. It remains to be determined if these EDCs affect zooplankton and other organisms that directly feed on marine phytoplankton, or if the secreted
Importance of deep mixing for initiating the North Atlantic spring bloom

DEFF Research Database (Denmark)

Riisgaard, Karen; Paulsen, Maria Lund; Thingstad, T. Frede

The phytoplankton spring bloom is one of the most important recurrent events in the sup-polar part of the Atlantic Ocean. The classical idea is that the bloom is controlled by nutrients and light, but recent observations challenge this hypothesis. During repeated visits to stations in the deep...

Comparison of biochemical compositions of phytoplankton during spring and fall seasons in the northern East/Japan Sea

Science.gov (United States)

Kang, Jae Joong; Joo, HuiTae; Lee, Jae Hyung; Lee, Jang Han; Lee, Ho Won; Lee, Dabin; Kang, Chang Keun; Yun, Mi Sun; Lee, Sang Heon

2017-09-01

The East/Japan Sea (EJS) where is surrounded by the Korean peninsula, the Japanese islands, and the Russian coast has been experiencing a large change in physicochemical properties. Based on biochemical composition analysis (carbohydrates, proteins, and lipids), the current qualitative status of phytoplankton was identified in the northern EJS from two different sampling seasons (fall and spring in 2012 and 2015, respectively). The average chlorophyll-a (chl-a) concentration integrated from the euphotic depths was significantly higher in 2015 (99.3 ± 69.2 mg m-2) than 2012 (21.5 ± 6.7 mg m-2). Large phytoplankton (> 2 μm) were predominant in 2015 accounting for 64.5 ± 19.7% whereas small-size phytoplankton (0.7-2 μm) were dominant (49.1 ± 17.5%) in 2012. The biochemical compositions of phytoplankton were predominated by lipids (42.6 ± 7.8%) in 2012 whereas carbohydrate composition largely contributed (53.2 ± 11.7%) to the total biochemical composition in 2015, which is mainly due to different nutrient availabilities and growth stages. Interestingly, the averaged FM concentrations and calorific values for phytoplankton based on the biochemical compositions had similar values between the two years, although the integrated chl-a concentrations were substantially different between 2012 and 2015. In terms of different cell sizes of phytoplankton, we found that small phytoplankton assimilate more FM and calorific energy per unit of chl-a concentration than total phytoplankton. Our results are meaningful for the understanding of future marine ecosystems where small phytoplankton will become dominant at a scenario of ongoing warmer oceans.
Extensive Chaetoceros curvisetus bloom in relation to water quality in Port Blair Bay, Andaman Islands.

Science.gov (United States)

Begum, Mehmuna; Sahu, Biraja Kumar; Das, Apurba Kumar; Vinithkumar, Nambali Valsalan; Kirubagaran, Ramalingam

2015-05-01

Blooming of diatom species Chaetoceros curvisetus (Cleve, 1889) was observed in Junglighat Bay and Haddo Harbour of Port Blair Bay of Andaman and Nicobar Islands during June 2010. Physico-chemical parameters, nutrient concentrations and phytoplankton composition data collected from five stations during 2010 were classified as bloom area (BA) and non-bloom area (NBA) and compared. Elevated values of dissolved oxygen were recorded in the BA, and it significantly varied (p NBA. Among the nutrient parameters studied, nitrate concentration indicated significant variation in BA and NBA (p NBA, indicating its utilization. In Junglighat Bay, the C. curvisetus species constituted 93.4 and 69.2% composition of total phytoplankton population during day 1 and day 2, respectively. The bloom forming stations separated out from the non-bloom forming station in non-parametric multidimensional scaling (nMDS) ordinations; cluster analysis powered by SIMPROF test also grouped the stations as BA and NBA.
Bloom of the Yessotoxin producing dinoflagellate Protoceratium reticulatum (Dinophyceae) in Northern Chile

Science.gov (United States)

Álvarez, Gonzalo; Uribe, Eduardo; Díaz, Rosario; Braun, Mauricio; Mariño, Carmen; Blanco, Juan

2011-05-01

In summer 2007, a dinoflagellate preliminarily identified as Protoceratium reticulatum bloomed in Bahía Mejillones, northern Chile. Phytoplankton samples were analyzed in detail by light and scanning electron microscopy revealing the presence of resting cyst and motile cells of P. reticulatum. Oceanographic and phytoplankton data suggest that the bloom was initiated offshore by motile cells and germinated cysts during an upwelling pulse. These cells were advected into the bay when upwelling relaxed and grew without any relevant competitor. Phytoplankton net samples were found to contain yessotoxin as the only toxin in an estimated proportion of 0.2 and 0.4 pg cell - 1 , thus confirming that P. reticulatum is a source of yessotoxin in northern Chilean waters and consequently that it poses a risk for human health and mollusk exploitation in the area.
Phytoplankton models and life history strategies | Eilertsen | African ...

African Journals Online (AJOL)

Phytoplankton models and life history strategies. ... Chaetoceros bloom of the growth season usually starts in mid March, initiated by C. socialis. ... in some species, inoculation events are controlled by endogenous biological clocks.
Why large cells dominate estuarine phytoplankton

Science.gov (United States)

Cloern, James E.

2018-01-01

Surveys across the world oceans have shown that phytoplankton biomass and production are dominated by small cells (picoplankton) where nutrient concentrations are low, but large cells (microplankton) dominate when nutrient-rich deep water is mixed to the surface. I analyzed phytoplankton size structure in samples collected over 25 yr in San Francisco Bay, a nutrient-rich estuary. Biomass was dominated by large cells because their biomass selectively grew during blooms. Large-cell dominance appears to be a characteristic of ecosystems at the land–sea interface, and these places may therefore function as analogs to oceanic upwelling systems. Simulations with a size-structured NPZ model showed that runs of positive net growth rate persisted long enough for biomass of large, but not small, cells to accumulate. Model experiments showed that small cells would dominate in the absence of grazing, at lower nutrient concentrations, and at elevated (+5°C) temperatures. Underlying these results are two fundamental scaling laws: (1) large cells are grazed more slowly than small cells, and (2) grazing rate increases with temperature faster than growth rate. The model experiments suggest testable hypotheses about phytoplankton size structure at the land–sea interface: (1) anthropogenic nutrient enrichment increases cell size; (2) this response varies with temperature and only occurs at mid-high latitudes; (3) large-cell blooms can only develop when temperature is below a critical value, around 15°C; (4) cell size diminishes along temperature gradients from high to low latitudes; and (5) large-cell blooms will diminish or disappear where planetary warming increases temperature beyond their critical threshold.
Consequences of inhibition of mixed-layer deepening by the West India coastal current for winter phytoplankton bloom in the northeastern Arabian Sea

Digital Repository Service at National Institute of Oceanography (India)

Vijith, V.; Vinayachandran, P.N.; Thushara, V.; Amol, P.; Shankar, D; Anil, A.C.

Consequences of inhibition of mixed-layer deepening by the1 West India Coastal Current for winter phytoplankton bloom in2 the northeastern Arabian Sea3 V. Vijith1, P. N. Vinayachandran 1, V. Thushara 1, P. Amol 1, D. Shankar 2, A. C. Anil 24 1Centre... m in375 February (Figure 5h). As the ML deepens in the north, cold sub-surface water376 that is rich in NO3 and PO4 entrains to the ML (Figures 4a,d and e). Vertical sec-377 tions of the nutrients (Figure 4d-e) resemble the temperature sections...
Par Pond phytoplankton in association with refilling of the pond: Final Report for sampling from February 1995 -- September 1996

International Nuclear Information System (INIS)

Wilde, E.W.; Johnson, M.A.; Cody, W.C.

1996-01-01

This report describes the results of phytoplankton analyses from Par Pond samples collected between February 1995 and September 1996. The principal objective of the study was to determine the effect of refilling of Par Pond following repair of the dam on the phytoplankton community. Algal blooms are often responsible for fish kills and other detrimental effects in ponds and lakes, and it was postulated that decaying vegetation from formerly exposed sediments might trigger algal blooms that could result in fish kills in Par Pond following the refill. Sporadic algal blooms involving blue-green algae were detected, especially during the summer of 1996. However, the data derived from the study demonstrates that overall, the refilling effort caused no significant negative impact to the pond attributable to phytoplankton dynamics
Par Pond phytoplankton in association with refilling of the pond: Final Report for sampling from February 1995 -- September 1996

Energy Technology Data Exchange (ETDEWEB)

Wilde, E.W.; Johnson, M.A.; Cody, W.C.

1996-12-31

This report describes the results of phytoplankton analyses from Par Pond samples collected between February 1995 and September 1996. The principal objective of the study was to determine the effect of refilling of Par Pond following repair of the dam on the phytoplankton community. Algal blooms are often responsible for fish kills and other detrimental effects in ponds and lakes, and it was postulated that decaying vegetation from formerly exposed sediments might trigger algal blooms that could result in fish kills in Par Pond following the refill. Sporadic algal blooms involving blue-green algae were detected, especially during the summer of 1996. However, the data derived from the study demonstrates that overall, the refilling effort caused no significant negative impact to the pond attributable to phytoplankton dynamics.
Bloom of Gymnodinium catenatum in Bahía Santiago and Bahía Manzanillo, Colima, Mexico.

Science.gov (United States)

Quijano-Scheggia, Sonia; Olivos-Ortiz, Aramis; Bustillos-Guzmán, José J; Garcés, Esther; Gaviño-Rodríguez, Juan H; Galicia-Pérez, Marco A; Patiño-Barragan, Manuel; Band-Schmidt, Christine J; Hernández-Sandoval, Francisco J; López-Cortés, David J

2012-03-01

Gymnodinium bloom events are of concern, since they produce toxins, which have unfavorable consequences to marine ecosystems, human health and the economy. This report describes the physico-chemical conditions that were present during the algal bloom event on May 2010 in Bahía Manzanillo and Bahía Santiago, Colima, Mexico. For this, seawater nutrient analysis, phytoplankton counts, identification, and toxicity tests were undertaken. Nutrients in seawater were determined using colorimetric techniques, the higher concentrations (8.88 microM DIN, 0.78 microM PO4 and 24.34 microM SiO2) were related with upwelling waters that promoted the algal bloom that began after registering the year lowest sea-surface temperature, favoring the rapid growth of G. catenatum (up to 1.02 x 10(7) cells/L). Phytoplankton counting was carried out using sedimentation chambers and cells enumerated on appropriated area. The bloom persisted in the bays for approximately two weeks and was associated with toxicity (determined with HPLC) in local oysters (1525.8 microg STXeq/100g), and in phytoplankton (10.9 pg STXeq/cells) samples. Strong variations in cell toxicity (1.4 to 10.9pg STXeq/cells), most likely reflected the availability of inorganic nutrients. The toxin profile of the phytoplankton samples consisted of 11 toxins and resembled those recorded for several strains of G. catenatum isolated from other coastal areas of Mexico.
Controlling cyanobacterial blooms in hypertrophic Lake Taihu, China: will nitrogen reductions cause replacement of non-N2 fixing by N2 fixing taxa?

Directory of Open Access Journals (Sweden)

Hans W Paerl

Full Text Available Excessive anthropogenic nitrogen (N and phosphorus (P inputs have caused an alarming increase in harmful cyanobacterial blooms, threatening sustainability of lakes and reservoirs worldwide. Hypertrophic Lake Taihu, China's third largest freshwater lake, typifies this predicament, with toxic blooms of the non-N2 fixing cyanobacteria Microcystis spp. dominating from spring through fall. Previous studies indicate N and P reductions are needed to reduce bloom magnitude and duration. However, N reductions may encourage replacement of non-N2 fixing with N2 fixing cyanobacteria. This potentially counterproductive scenario was evaluated using replicate, large (1000 L, in-lake mesocosms during summer bloom periods. N+P additions led to maximum phytoplankton production. Phosphorus enrichment, which promoted N limitation, resulted in increases in N2 fixing taxa (Anabaena spp., but it did not lead to significant replacement of non-N2 fixing with N2 fixing cyanobacteria, and N2 fixation rates remained ecologically insignificant. Furthermore, P enrichment failed to increase phytoplankton production relative to controls, indicating that N was the most limiting nutrient throughout this period. We propose that Microcystis spp. and other non-N2 fixing genera can maintain dominance in this shallow, highly turbid, nutrient-enriched lake by outcompeting N2 fixing taxa for existing sources of N and P stored and cycled in the lake. To bring Taihu and other hypertrophic systems below the bloom threshold, both N and P reductions will be needed until the legacy of high N and P loading and sediment nutrient storage in these systems is depleted. At that point, a more exclusive focus on P reductions may be feasible.
A numerical investigation of phytoplankton and Pseudocalanus elongatus dynamics in the spring bloom time in the Gdańsk Gulf

Science.gov (United States)

Dzierzbicka-Głowacka, Lidia

2005-01-01

A nutrient-phytoplankton-zooplankton-detritus (1D-NPZD) `phytoplankton {Phyt} and Pseudocalanus elongatus {Zoop} dynamics in the spring bloom time in the Gdańsk Gulf. The 1D-NPZD model consists of three coupled, partial second-order differential equations of the diffusion type for phytoplankton {Phyt}, zooplankton {Zoop}, nutrients {Nutr} and one ordinary first-order differential equation for benthic detritus pool {Detr}, together with initial and boundary conditions. In this model, the {Zoop} is presented by only one species of copepod ( P. elongatus) and {Zoop} is composed of six cohorts of copepods with weights ( Wi) and numbers ( Zi); where Zoop= limit∑i=16W iZ i. The calculations were made for 90 days (March, April, May) for two stations at Gdańsk Gulf with a vertical space step of 0.5m and a time step of 900 s. The flow field and water temperature used as the inputs in the biological model 1D-NPZD were reproduced by the prognostic numerical simulation technique using hydrographic climatological data. The results of the numerical investigations described here were compared with the mean observed values of surface chlorophyll- a and depth integrated P. elongatus biomass for 10 years, 1980-1990. The slight differences between the calculated and mean observed values of surface chlorophyll- a and zooplankton biomass are ca. 10-60 mg C m -3 and ca. 5-23 mg C m -2, respectively, depending on the location of the hydrographic station. The 1D-NPZD model with a high-resolution zooplankton module for P. elongatus can be used to describe the temporal patterns for phytoplankton biomass and P. elongatus in the centre of the Gdańsk Gulf.
Spatial and temporal patterns of phytoplankton composition in Burullus Lagoon, Southern Mediterranean Coast, Egypt

Directory of Open Access Journals (Sweden)

Mohamed Zein Alabedin Nassar

2014-01-01

Full Text Available Burullus Lagoon is a shallow, turbid, and nutrient replete system, suffering from high level of aquatic plants, expansion in fish farming and agricultural drainage discharges. Phytoplankton was evaluated based on four years monitoring seasonally from summer 2009 to spring 2013 at 12 stations representing the eastern, central and western basins of the lagoon. Over the 4-year study period, a total of 283 taxa from 96 genera and eight classes were recorded. The lagoon showed a pronounced algal periodicity. Phytoplankton community was generally dominated by Chlorophyceae, Bacillariophyceae and Cyanobacteria. The western basin had the lowest mean salinity values and highest phytoplankton abundance, in which, blooms of Chlorophyceae, Bacillariophyceae and Cyanobacteria were common. The eastern basin had lowest phytoplankton density and chlorophytes were dominant followed by Bacillariophyceae and/or Cyanobacteria. Euglenophyceae strongly appeared in the eastern basin especially at the second station, which is located in front of El Burullus Drain. The central basin is subjecting to high loading of phosphorus and nitrogen from agricultural drains and had a prevalence of chlorophyte blooms which constituted more than 50% of the total abundance. This study has provided substantial evidence that the phytoplankton abundance and community are governed by the environmental conditions which vary each year, so does the phytoplankton seasonal succession. Generally, about 25-50% reduction was recorded in the phytoplankton densities between 2009 and 2013 and a dramatic decrease in the abundance of many nuisance and eutrophic species was evident. No sign of eutrophication was observed, and recession of Cyanobacteria blooming suggests a major improvement in the water quality of Burullus Lagoon.
A winter dinoflagellate bloom drives high rates of primary production in a Patagonian fjord ecosystem

Science.gov (United States)

Montero, P.; Pérez-Santos, I.; Daneri, G.; Gutiérrez, M. H.; Igor, G.; Seguel, R.; Purdie, D.; Crawford, D. W.

2017-12-01

A dense winter bloom of the dinoflagellate Heterocapsa triquetra was observed at a fixed station (44°35.3‧S; 72°43.6‧W) in the Puyuhuapi Fjord in Chilean Patagonia during July 2015. H. triquetra dominated the phytoplankton community in the surface waters between 2 and 15 m (13-58 × 109 cell m-2), with abundances some 3 to 15 times higher than the total abundance of the diatom assemblage, which was dominated by Skeletonema spp. The high abundance of dinoflagellates was reflected in high rates of gross primary production (GPP; 0.6-1.6 g C m-2 d-1) and chlorophyll-a concentration (Chl-a; 70-199.2 mg m-2) that are comparable to levels reported in spring diatom blooms in similar Patagonian fjords. We identify the main forcing factors behind a pulse of organic matter production during the non-productive winter season, and test the hypothesis that low irradiance levels are a key factor limiting phytoplankton blooms and subsequent productivity during winter. Principal Component Analysis (PCA) indicated that GPP rates were significantly correlated (r = -0.8, p bloom. The bloom occurred under low surface irradiance levels characteristic of austral winter and was accompanied by strong northern winds, associated with the passage of a low-pressure system, and a water column dominated by double diffusive layering. To our knowledge, this is the first report of a dense dinoflagellate bloom during deep austral winter in a Patagonian fjord, and our data challenge the paradigm of light limitation as a factor controlling phytoplankton blooms in this region in winter.
Aragonite saturation state in a tropical coastal embayment dominated by phytoplankton blooms (Guanabara Bay - Brazil).

Science.gov (United States)

Cotovicz, Luiz C; Knoppers, Bastiaan A; Brandini, Nilva; Poirier, Dominique; Costa Santos, Suzan J; Abril, Gwenaël

2018-04-01

The dynamics of the aragonite saturation state (Ω arag ) were investigated in the eutrophic coastal waters of Guanabara Bay (RJ-Brazil). Large phytoplankton blooms stimulated by a high nutrient enrichment promoted the production of organic matter with strong uptake of dissolved inorganic carbon (DIC) in surface waters, lowering the concentrations of dissolved carbon dioxide (CO 2aq ), and increasing the pH, Ω arag and carbonate ion (CO 3 2- ), especially during summer. The increase of Ω arag related to biological activity was also evident comparing the negative relationship between the Ω arag and the apparent utilization of oxygen (AOU), with a very close behavior between the slopes of the linear regression and the Redfield ratio. The lowest values of Ω arag were found at low-buffered waters in regions that receive direct discharges from domestic effluents and polluted rivers, with episodic evidences of corrosive waters (Ω arag <1). This study showed that the eutrophication controlled the variations of Ω arag in Guanabara Bay. Copyright © 2017 Elsevier Ltd. All rights reserved.
Dynamic modelling of five different phytoplankton groups in the River Thames (UK)

Science.gov (United States)

Bussi, Gianbattista; Whitehead, Paul; Bowes, Michael; Read, Daniel; Dadson, Simon

2015-04-01

Phytoplankton play a vital role in fluvial ecosystems, being a major producer of organic carbon, a food source for primary consumers and a relevant source of oxygen for many low-gradient rivers, but also a producer of potentially harmful toxins (e.g. cyanobacteria). For these reasons, the forecast and prevention of algal blooms is fundamental for the safe management of river systems. In this study, we developed a new process-based phytoplankton model for operational management and forecast of algal and cyanobacteria blooms subject to environmental change. The model is based on a mass-balance and it reproduces phytoplankton growth and death, taking into account the controlling effect played by water temperature, solar radiation, self-shading and dissolved phosphorus and silicon concentrations. The model was implemented in five reaches of the River Thames (UK) with a daily time step over a period of three years, and its results were compared to a novel dataset of cytometric data which includes community cell abundance of chlorophytes, diatoms, cyanobacteria, microcystis-like cyanobacteria and picoalgae. The model results were satisfactory in terms of fitting the observed data. A Multi-Objective General Sensitivity Analysis was also carried out in order to quantify model sensitivity to its parameters. It showed that the most influential parameters are phytoplankton growth and death rates, while phosphorus concentration showed little influence on phytoplankton growth, due to the high levels of phosphorus in the River Thames. The model was demonstrated to be a reliable tool to be used in algal bloom forecasting and management.
Phytoplankton variation and its relation to nutrients and allochthonous organic matter in a coastal lagoon on the Gulf of Mexico

Science.gov (United States)

Aké-Castillo, José A.; Vázquez, Gabriela

2008-07-01

In tropical and subtropical zones, coastal lagoons are surrounded by mangrove communities which are a source of high quantity organic matter that enters the aquatic system through litter fall. This organic matter decomposes, becoming a source of nutrients and other substances such as tannins, fulvic acids and humic acids that may affect the composition and productivity of phytoplankton communities. Sontecomapan is a coastal lagoon located in the southern Gulf of Mexico, which receives abundant litter fall from mangrove. To study the phytoplankton composition and its variation in this lagoon from October 2002 to October 2003, we evaluated the concentrations of dissolved folin phenol active substances (FPAS) as a measure of plant organic matter, salinity, temperature, pH, O 2, N-NH 4+, N-NO 3-, P-PO 43-, Si-SiO 2, and phytoplanktonic cell density in different mangrove influence zones including the three main rivers that feed the lagoon. Nutrients concentrations depended on freshwater from rivers, however these varied seasonally. Concentrations of P-PO 43-, N-NH 4+ and FPAS were the highest in the dry season, when maximum mangrove litter fall is reported. Variation of these nutrients seemed to depend on the internal biogeochemical processes of the lagoon. Blooms of diatoms ( Skeletonema spp., Cyclotella spp. and Chaetoceros holsaticus) and dinoflagellates ( Peridinium aff. quinquecorne, Prorocentrum cordatum) occurred seasonally and in the different mangrove influence zones. The high cell densities in these zones and the occurrence of certain species and its ordination along gradient of FPAS in a canonical correspondence analysis, suggest that plant organic matter (i.e. mangrove influence) may contribute to phytoplankton dynamics in Sontecomapan lagoon.
A Remote Sensing Approach to Estimate Vertical Profile Classes of Phytoplankton in a Eutrophic Lake

Directory of Open Access Journals (Sweden)

Kun Xue

2015-10-01

Full Text Available The extension and frequency of algal blooms in surface waters can be monitored using remote sensing techniques, yet knowledge of their vertical distribution is fundamental to determine total phytoplankton biomass and understanding temporal variability of surface conditions and the underwater light field. However, different vertical distribution classes of phytoplankton may occur in complex inland lakes. Identification of the vertical profile classes of phytoplankton becomes the key and first step to estimate its vertical profile. The vertical distribution profile of phytoplankton is based on a weighted integral of reflected light from all depths and is difficult to determine by reflectance data alone. In this study, four Chla vertical profile classes (vertically uniform, Gaussian, exponential and hyperbolic were found to occur in three in situ vertical surveys (28 May, 19–24 July and 10–12 October in a shallow eutrophic lake, Lake Chaohu. We developed and validated a classification and regression tree (CART to determine vertical phytoplankton biomass profile classes. This was based on an algal bloom index (Normalized Difference algal Bloom Index, NDBI applied to both in situ remote sensing reflectance (Rrs and MODIS Rayleigh-corrected reflectance (Rrc data in combination with data of local wind speed. The results show the potential of retrieving Chla vertical profiles information from integrated information sources following a decision tree approach.
Toxic phytoplankton in San Francisco Bay

Science.gov (United States)

Rodgers, Kristine M.; Garrison, David L.; Cloern, James E.

1996-01-01

The Regional Monitoring Program (RMP) was conceived and designed to document the changing distribution and effects of trace substances in San Francisco Bay, with focus on toxic contaminants that have become enriched by human inputs. However, coastal ecosystems like San Francisco Bay also have potential sources of naturally-produced toxic substances that can disrupt food webs and, under extreme circumstances, become threats to public health. The most prevalent source of natural toxins is from blooms of algal species that can synthesize metabolites that are toxic to invertebrates or vertebrates. Although San Francisco Bay is nutrient-rich, it has so far apparently been immune from the epidemic of harmful algal blooms in the world’s nutrient-enriched coastal waters. This absence of acute harmful blooms does not imply that San Francisco Bay has unique features that preclude toxic blooms. No sampling program has been implemented to document the occurrence of toxin-producing algae in San Francisco Bay, so it is difficult to judge the likelihood of such events in the future. This issue is directly relevant to the goals of RMP because harmful species of phytoplankton have the potential to disrupt ecosystem processes that support animal populations, cause severe illness or death in humans, and confound the outcomes of toxicity bioassays such as those included in the RMP. Our purpose here is to utilize existing data on the phytoplankton community of San Francisco Bay to provide a provisional statement about the occurrence, distribution, and potential threats of harmful algae in this Estuary.
Bloom of Gymnodinium catenatum in Bahía Santiago and Bahía Manzanillo, Colima, Mexico

Directory of Open Access Journals (Sweden)

Sonia Quijano-Scheggia

2012-03-01

Full Text Available Gymnodinium bloom events are of concern, since they produce toxins, which have unfavorable consequences to marine ecosystems, human health and the economy. This report describes the physico-chemical conditions that were present during the algal bloom event on May 2010 in Bahía Manzanillo and Bahía Santiago, Colima, Mexico. For this, seawater nutrient analysis, phytoplankton counts, identification, and toxicity tests were undertaken. Nutrients in seawater were determined using colorimetric techniques, the higher concentrations (8.88μM DIN, 0.78μM PO4 and 24.34μM SiO2 were related with upwelling waters that promoted the algal bloom that began after registering the year lowest sea-surface temperature, favoring the rapid growth of G. catenatum (up to 1.02 x10(7cells/L. Phytoplankton counting was carried out using sedimentation chambers and cells enumerated on appropriated area. The bloom persisted in the bays for approximately two weeks and was associated with toxicity (determined with HPLC in local oysters (1525.8μg STXeq/100g, and in phytoplankton (10.9pg STXeq/cells samples. Strong variations in cell toxicity (1.4 to 10.9pg STXeq/cells, most likely reflected the availability of inorganic nutrients. The toxin profile of the phytoplankton samples consisted of 11 toxins and resembled those recorded for several strains of G. catenatum isolated from other coastal areas of Mexico.
Phytoplankton assemblage of a small, shallow, tropical African reservoir.

Science.gov (United States)

Mustapha, Moshood K

2009-12-01

I measured physico-chemical properties and phytoplankton in the small, shallow tropical reservoir of Oyun (Offa, Nigeria) between January 2002 and December 2003. I identified 25 phytoplankton genera in three sampling stations. Bacillariophyceae dominated (75.3%), followed by Chlorophyceae (12.2%), Cyanobacteria (11.1%) and Desmidiaceae (0.73%). The high amount of nutrients (e.g. nitrate, phosphate, sulphate and silica) explain phytoplankton heterogeneity (p<0.05). Phytoplankton was abundant during the rainy season, but the transition period had the richest assemblage and abundance. Fluctuations in phytoplankton density were a result of seasonal changes in concentration of nutrients, grazing pressure and reservoir hydrology. The reservoir is eutrophic with excellent water quality and a diverse phytoplankton assemblage: fish production would be high. These conditions resulted from strategies such as watershed best management practices (BMPs) to control eutrophication and sedimentation, and priorities for water usage established through legislation. Additional measures are recommended to prevent oligotrophy, hypereutrophy, excessive phytoplankton bloom, toxic cyanobacteria, and run-off of organic waste and salts.

Spring Blooms Observed with Biochemical Profiling Floats from a Chemical and Biological Perspective

Science.gov (United States)

Plant, J. N.; Johnson, K. S.; Sakamoto, C.; Jannasch, H. W.; Coletti, L. J.; Elrod, V.

2015-12-01

Recently there has been renewed interest in the mechanisms which control the seasonal increases in plankton biomass (spring blooms). Changes in physical and chemical forcing (light, wind, heat and nutrients) may increase the specific growth rate of phytoplankton. These changes may also shift the predator - prey relationships within the food web structure, which can alter the balance between plankton growth and loss rates. Biogeochemical profiling floats provide a means to observe the seasonal evolution of spring blooms from a physical, chemical and biological perspective in near real time. Floats equipped with optical sensors to measure nitrate, oxygen, chlorophyll fluorescence, and optical backscatter now have a presence in many ocean regions including the North Pacific, Subarctic Pacific, North Atlantic, South Atlantic and the Southern Ocean. Data from these regions are used to compare and contrast the evolution of spring blooms. The evolution of the bloom is examined using both chemical (oxygen, nitrate) and biooptical (phytoplankton from chlorophyll fluorescence and particulate organic carbon from optical backscatter) sensors under vastly different environmental conditions.
A prospective study of marine phytoplankton and reported illness among recreational beachgoers in Puerto Rico, 2009

Science.gov (United States)

BACKGROUND: Blooms of marine phytoplankton may adversely affect human health. The potential public health impact of low-level exposures is not well established, and few prospective cohort studies of recreational exposures to marine phytoplankton have been conducted.OBJECTIVE: We ...
Variations in phytoplankton community in a monsoon-influenced tropical estuary

Digital Repository Service at National Institute of Oceanography (India)

Patil, J.S.; Anil, A.C.

. The break period in monsoon altered the phytoplankton community leading to mixed species bloom of large-sized diatoms and harmful dinoflagellates (Gymnodinium catenatum and Cochlodinium polykrikoides) under high-saline, nutrient-poor, non...
Climate warming and interannual variability of phytoplankton phenology in the Northern Red Sea

KAUST Repository

Gittings, John

2016-12-01

In agreement with global patterns of climate change and increasing temperatures in the tropical oceans, the Northern Red Sea (NRS) has been warming over the last few decades. Using 18 years of remotely-sensed chlorophyll-a data (Chl-a, an index of phytoplankton biomass), we investigate the potential impacts of climate warming on phytoplankton abundance and phenology in the Northern Red Sea by exploring the mechanistic links with the regional physical environment. The results of the analysis reveal that, in accordance with other tropical ecosystems, phytoplankton biomass in the NRS will decrease in response to warmer climate scenarios. This is attributed to lower heat fluxes (heat loss to the atmosphere) during the bloom period, and enhanced vertical stratification, which prevents vertical mixing of nutrients into the euphotic layer. In addition, we show that during warmer conditions (when heat fluxes are weakened), the winter bloom initiates significantly later (by up to 10 weeks) and its duration is considerably reduced. The biological implications of alterations to phytoplankton phenology may include increased larval mortality of pelagic species, reduced recruitment, fisheries impacts and changes to community structure.
Plankton bloom controlled by horizontal stirring

Science.gov (United States)

McKiver, W.; Neufeld, Z.; Scheuring, I.

2009-10-01

Here we show a simple mechanism in which changes in the rate of horizontal stirring by mesoscale ocean eddies can trigger or suppress plankton blooms and can lead to an abrupt change in the average plankton density. We consider a single species phytoplankton model with logistic growth, grazing and a spatially non-uniform carrying capacity. The local dynamics have multiple steady states for some values of the carrying capacity that can lead to localized blooms as fluid moves across the regions with different properties. We show that for this model even small changes in the ratio of biological timescales relative to the flow timescales can greatly enhance or reduce the global plankton productivity. Thus, this may be a possible mechanism in which changes in horizontal mixing can trigger plankton blooms or cause regime shifts in some oceanic regions. Comparison between the spatially distributed model and Lagrangian simulations considering temporal fluctuations along fluid trajectories, demonstrates that small scale transport processes also play an important role in the development of plankton blooms with a significant influence on global biomass.
Effects of increased atmospheric CO2 on small and intermediate sized osmotrophs during a nutrient induced phytoplankton bloom

Directory of Open Access Journals (Sweden)

A. Larsen

2008-05-01

Full Text Available We report the transient population dynamic response of the osmotrophic community initiated by a nutrient pulse in mesocosms exposed to different pCO2 levels. Differences in phytoplankton and heterotrophic bacteria abundances associated with the CO2 treatment are also described. Coastal seawater was enclosed in floating mesocosms (27 m3 and nutrients were supplied initially in order to stimulate growth of microbial organisms, including the coccolitophorid Emiliania huxleyi. The mesocosms were modified to achieve 350 μatm (1×CO2, 700 μatm (2×CO2 and 1050 μatm (3×CO2 CO2 pressure. The temporal dynamics was related to nutrient conditions in the enclosures. Numerically small osmotrophs (picoeukaryotes and Synechoccocus sp. dominated initially and towards the end of the experiment, whereas intermediate sized osmotrophs bloomed as the initial bloom of small sized osmotrophs ceased. Maximum concentrations of E. huxleyi were approximately 4.6×103 cells ml−1 whereas other intermediate sized osmotrophs reached approximately twice as high concentrations. The osmotrophic succession pattern did not change, and neither were we able to detect differences with regard to presence or absence of specific osmotrophic taxa as a consequence of altered pCO2. Towards the end of the experiment we did, however, record significantly higher picoeukaryotic- and lower Synechococcus-abundances in the higher CO2 treatments. Slightly increased cell concentrations of E. huxleyi and other nanoeukaryotes were also recorded at elevated pCO2 on certain days.
MODEL OF PHYTOPLANKTON COMPETITION FOR LIMITING AND NONLIMITING NUTRIENTS: IMPLICATIONS FOR DEVELOPMENT OF ESTUARINE AND NEARSHORE MANAGEMENT SCHEMES

Science.gov (United States)

The global increase of noxious bloom occurrences has increased the need for phytoplankton management schemes. Such schemes require the ability to predict phytoplankton succession. Equilibrium Resources Competition theory, which is popular for predicting succession in lake systems...
Nutrients and toxin producing phytoplankton control algal blooms ...

Indian Academy of Sciences (India)

Unknown

capacity for the phytoplankton population depends on the nutrient level. The role of nutrient ..... irregular oscillations with time, gives rise to rich class of models ..... the Indian river lagoon, Florida, USA; J. Plankton Res. 26. 1229– ... Sea Res. 18 82–96. Graneli E et al 1989 From anoxia to fish poisoning: The last ten years of ...
New Coccolithophore Bloom in Bering Sea

Science.gov (United States)

2002-01-01

For the fourth year in a row it appears as if there is a bloom of coccolithophores-marine single-celled plants with calcite scales-in the Bering Sea off the coast of Alaska. Similar blooms were rare before 1997, but they have appeared every year since then. Scientists believe the coccolithophore blooms are the result of changing wind patterns in the region. Weaker than normal winds fail to mix the water of the Bering Sea, resulting in the growth of coccolithophores instead of other types of phytoplankton. Seabird populations have also been changing as a result of this climate change. The Sea-Viewing Wide Field-of-View Sensor (SeaWiFS), flying aboard the OrbView-2 satellite, saw the coccolith-brightened waters of the Bering Sea in 1997, 1998, and 1999. The waters have looked fairly bright again this winter and spring, as seen in this SeaWiFS image acquired April 29, 2000. But scientists are unsure whether this year's phenomenon is caused by living coccolithophorids, re-suspended coccoliths, or something else. Like all phytoplankton, coccolithophores contain chlorophyll and have the tendency to multiply rapidly near the surface. Yet, in large numbers, coccolithophores periodically shed their tiny scales, called 'coccoliths,' by the bucketful into the surrounding waters. The calcium-rich coccoliths turn the normally dark water a bright, milky aquamarine, making coccolithophore blooms easy to spot in satellite imagery. The edge of the whitish cloud in the water seen in this image is roughly 50 kilometers off the West Coast of Alaska. For more information see: SeaWiFS home page Changing Currents Color the Bering Sea a New Shade of Blue Image courtesy SeaWiFS project
Un inusual bloom de Tetraselmis sp. en la Bahía de Valparaíso, Chile

OpenAIRE

PIZARRO, MARLENE; ITURRIAGA, RODOLFO; SILVA, ALEJANDRO; GALLEGOS, SONIA

2012-01-01

A bloom of Tetraselmis sp. was observed during the first days of January of 2006 in the Valparaiso Bay (32° 57'S; 71° 33'W), producing green coloration of sea and exclusion of phytoplankton species. Previous blooms of Tetraselmis sp. have not been observed in this bay.
Bacterial and protist community changes during a phytoplankton bloom

KAUST Repository

Pearman, John K.; Casas, Laura; Merle, Tony; Michell, Craig; Irigoien, Xabier

2015-01-01

)] as well as a control. This approach allowed us to discriminate the changes in species composition across a broad range of phylogenetic groups using a common taxonomic level. Diatoms dominated the bloom in the NPSc treatment while dinoflagellates were
Diversity and dynamics of a widespread bloom of the toxic dinoflagellate Alexandrium fundyense.

Directory of Open Access Journals (Sweden)

Deana L Erdner

Full Text Available Historically, cosmopolitan phytoplankton species were presumed to represent largely unstructured populations. However, the recent development of molecular tools to examine genetic diversity have revealed differences in phytoplankton taxa across geographic scales and provided insight into the physiology and ecology of blooms. Here we describe the genetic analysis of an extensive bloom of the toxic dinoflagellate Alexandrium fundyense that occurred in the Gulf of Maine in 2005. This bloom was notable for its intensity and duration, covering hundreds of kilometers and persisting for almost two months. Genotypic analyses based on microsatellite marker data indicate that the open waters of the northeastern U.S. harbor a single regional population of A. fundyense comprising two genetically distinct sub-populations. These subpopulations were characteristic of early- and late-bloom samples and were derived from the northern and southern areas of the bloom, respectively. The temporal changes observed during this study provide clear evidence of succession during a continuous bloom and show that selection can act on the timescale of weeks to significantly alter the representation of genotypes within a population. The effects of selection on population composition and turnover would be magnified if sexual reproduction were likewise influenced by environmental conditions. We hypothesize that the combined effects of differential growth and reproduction rates serves to reduce gene flow between the sub-populations, reinforcing population structure while maintaining the diversity of the overall regional population.
Multi-nutrient, multi-group model of present and future oceanic phytoplankton communities

Directory of Open Access Journals (Sweden)

E. Litchman

2006-01-01

Full Text Available Phytoplankton community composition profoundly affects patterns of nutrient cycling and the dynamics of marine food webs; therefore predicting present and future phytoplankton community structure is crucial to understand how ocean ecosystems respond to physical forcing and nutrient limitations. We develop a mechanistic model of phytoplankton communities that includes multiple taxonomic groups (diatoms, coccolithophores and prasinophytes, nutrients (nitrate, ammonium, phosphate, silicate and iron, light, and a generalist zooplankton grazer. Each taxonomic group was parameterized based on an extensive literature survey. We test the model at two contrasting sites in the modern ocean, the North Atlantic (North Atlantic Bloom Experiment, NABE and subarctic North Pacific (ocean station Papa, OSP. The model successfully predicts general patterns of community composition and succession at both sites: In the North Atlantic, the model predicts a spring diatom bloom, followed by coccolithophore and prasinophyte blooms later in the season. In the North Pacific, the model reproduces the low chlorophyll community dominated by prasinophytes and coccolithophores, with low total biomass variability and high nutrient concentrations throughout the year. Sensitivity analysis revealed that the identity of the most sensitive parameters and the range of acceptable parameters differed between the two sites. We then use the model to predict community reorganization under different global change scenarios: a later onset and extended duration of stratification, with shallower mixed layer depths due to increased greenhouse gas concentrations; increase in deep water nitrogen; decrease in deep water phosphorus and increase or decrease in iron concentration. To estimate uncertainty in our predictions, we used a Monte Carlo sampling of the parameter space where future scenarios were run using parameter combinations that produced acceptable modern day outcomes and the
Dominance patterns in macroalgal and phytoplankton biomass under different nutrient loads in subtropical coastal lagoons of the SE Gulf of California

International Nuclear Information System (INIS)

Páez-Osuna, F.; Piñón-Gimate, A.; Ochoa-Izaguirre, M.J.

2013-01-01

Highlights: • Nine macroalgal blooms were examined in five lagoons from SE Gulf of California. • Shrimp farms were the main point source of nutrients loads to the lagoons. • Biomass as phytoplankton ranged 40–792 mg m −2 and macroalgal of 1–296 g m −2 . • Biomass (phytoplankton + macroalgae) was the same tendency that nutrient loads. • Phytoplankton and macroalgal biomass were a significant correlation with N:P ratio. -- Abstract: Nine macroalgal blooms were studied in five coastal lagoons of the SE Gulf of California. The nutrient loads from point and diffuse sources were estimated in the proximity of the macroalgal blooms. Chlorophyll a and macroalgal biomass were measured during the dry, rainy and cold seasons. Shrimp farms were the main point source of nitrogen and phosphorus loads for the lagoons. High biomasses were found during the dry season for phytoplankton at site 6 (791.7 ± 34.6 mg m −2 ) and during the rainy season for macroalgae at site 4 (296.0 ± 82.4 g m −2 ). Depending on the season, the phytoplankton biomass ranged between 40.0 and 791.7 mg m −2 and the macroalgal biomass between 1 and 296.0 g m −2 . The bulk biomass (phytoplankton + macroalgal) displayed the same tendency as the nutrient loads entering the coastal lagoons. Phytoplankton and macroalgal biomass presented a significant correlation with the atomic N:P ratio
Temporal and spatial variability of phytoplankton pigment concentrations in the Indian Ocean, derived from the CZCS time series images

Directory of Open Access Journals (Sweden)

2005-01-01

Full Text Available A total of 93 monthly global composite remotely sensed ocean color images from the Coastal Zone Color Scanner (CZCS on board the Nimbus-7 satellite were extracted for the Indian Ocean region (35ºN–55ºS; 30–120ºE to examine the seasonal variations in phytoplankton pigment concentrations, resulting from large-scale changes in physical oceanographic processes. The CZCS data sets were analyzed with the PC-SEAPAK software, and revealed large phytoplankton blooms in the northwest Arabian Sea and off the Somali coast. The blooms were triggered by wind-driven upwelling during the southwest monsoonal months of August and September. In the northern Arabian Sea, phytoplankton blooms, detected from January to March, appeared to be associated with nutrient enhancement resulting from winter convective mixing. In the Bay of Bengal, higher pigment concentrations were confined to the coastal regions but varied only marginally between seasons both in the coastal and offshore regions. Phytoplankton pigment concentrations were consistently low in the open Indian Ocean. Analysis of pigment concentrations extracted from the monthly-accumulated images revealed that the Arabian Sea sustained a greater biomass of phytoplankton compared with any other region of the Indian Ocean. Overall, the coastal regions of the Indian Ocean are richer in phytoplankton pigment than the open Indian Ocean. The number of images in individual areas was highly variable throughout the region due to varying cloud cover.
Seasonal development of phytoplankton populations in offshore Lake Michigan in 1975

International Nuclear Information System (INIS)

Parker, J.I.; Conway, H.L.; Yaguchi, E.M.

1975-01-01

Relationships between phytoplankton bloom sequences and environmental factors that may account for seasonal variations have not been thoroughly evaluated in Lake Michigan. We investigated the seasonal periodicity of phytoplankton in the offshore water from April to December, 1975. The seasonal distributions of phytoplankton biomass, chlorophyll a, and primary productivity per unit of lake surface area were measured at station 5. These measurements demonstrated a bimodal seasonal distribution, with maxima occurring in June and October. Previous investigators have shown that the seasonal periodicity was unimodal, with a summer maximum. Our observations demonstrated year to year variations in this abundance pattern
A seasonal diary of phytoplankton in the North Atlantic

DEFF Research Database (Denmark)

Lindemann, Christian; St. John, Michael

2014-01-01

In recent years new biological and physical controls have been suggested to drive phytoplankton bloom dynamics in the North Atlantic. A better understanding of the mechanisms driving primary production has potentially important implications for the understanding of the biological carbon pump...... are not mutually exclusive, but rather complementary. Thus, moving beyond the “single mechanism” point of view, here we present an integrated conceptual model of the physical and biological controls on phytoplankton dynamics in the North Atlantic. Further we believe that the acclimation of physiological rates can...... play an important role in mediating phytoplankton dynamics. Thus, this view emphasizes the occurrence of multiple controls and relates their variations in impact to climate change...
WATER BLOOM OF BLUEGREEN ALGE IN CARP FISHPOUNDS

Directory of Open Access Journals (Sweden)

Melita Mihaljević

1996-03-01

Full Text Available The massive development of bluegreen algae (Cyanophyta/Cyanobacteria, the so--called water bloom, is a frequent phenomenon in fishpond ecosystems. This study analyses water bloom development in three carp fishponds owned by a fishbreeding company at Donji Miholjac (Croatia, where one-year-old carps (Cyprinus carpio , were bred in defferent fishstock densities. Analyses of physicallychemical properties of water and phytoplankton biomass were per- formed in fortnight intervals from May till October, 1992. In all there investigated fishponds the water bloom of bluegreen algae developed, but at a different time and showing a different qualitative composition. In the fishpond with fishstock density of 250 kg/ha water bloom consisted of the species Aphanizomenon flos-aquae, and the biggest biomass (131.92 mg/I was found in August. In the fishpond with fishstock density of 437 kg/ha a water bloom consisting of species from the genues Anabaena and species Aphanizomenon flos-aquae developed at the end of July. In the fishpond with the so--called intensive breeding (fishstock density of 750 kg/ha water bloom of the species Microcystis aeruginosa developed as late as September. The beginning of water bloom development was caused by the low value (lower than 7 of the ratio between the quantities of total phosphorus and total nitrogen. However, the qualitative composition of water bloom was influenced by one-year-old carp fingerlings density.
Impact of multispecies diatom bloom on plankton community structure in Sundarban mangrove wetland, India

International Nuclear Information System (INIS)

Biswas, Sejuti Naha; Rakshit, Dibyendu; Sarkar, Santosh Kumar; Sarangi, Ranjit Kumar; Satpathy, Kamala Kanta

2014-01-01

Highlights: • A multispecies algal bloom was studied in coastal regions of Sundarban wetland. • Sharp changes in plankton community structure and hydrological parameters observed. • Chlorophyll a showed highest cell density (11.4 × 10 5 cells l −1 ) during bloom phase. • MODIS Aqua derived chlorophyll maps have been interpreted. - Abstract: A multispecies bloom caused by the centric diatoms, viz. Coscinodiscus radiatus, Chaetoceros lorenzianus and the pennate diatom Thalassiothrix frauenfeldii was investigated in the context of its impact on phytoplankton and microzooplankton (the loricate ciliate tintinnids) in the coastal regions of Sagar Island, the western part of Sundarban mangrove wetland, India. Both number (15–18 species) and cell densities (12.3 × 10 3 cells l −1 to 11.4 × 10 5 cells l −1 ) of phytoplankton species increased during peak bloom phase, exhibiting moderately high species diversity (H′ = 2.86), richness (R′ = 6.38) and evenness (E′ = 0.80). The diatom bloom, which existed for a week, had a negative impact on the tintinnid community in terms of drastic changes in species diversity index (1.09–0.004) and population density (582.5 × 10 3 to 50 × 10 3 ind m −3 ). The bloom is suggested to have been driven by the aquaculture activities and river effluents resulting high nutrient concentrations in this region. An attempt has been made to correlate the satellite remote sensing-derived information to the bloom conditions. MODIS-Aqua derived chlorophyll maps have been interpreted
Phytoplankton diversity and their succession in water bodies of the Lednice park during 2002 season

Directory of Open Access Journals (Sweden)

Zohreh Ramezanpoor

2004-01-01

Full Text Available Phytoplankton communities of three water bodies in the Lednice park were studied from 22nd April till 1st October 2002. These water bodies are the Zámecký pond, Růžový pond and the Dyje River, which is water source of both ponds.Phytoplankton samples were taken every two weeks between 8 - 9 am. Collected phytoplankton samples were preserved with 4% formalin solution and Lugol solution (JJK and transported to the laboratory. They were determined and counted using inverted microscope. Water temperature, pH and dissolved oxygen were measured in the field using digital portable instruments. Total of 317 phytoplankton species were determined in this study.Heavy algal bloom was observed in the Zámecký pond in mid-summer coinciding with increase in water temperature. Fish diseases and partial mortality occurred during the period of algal bloom and unpleasant smell was dominant feature. A light algal bloom was also observed in the Růžový pond and the Dyje River nearly by the end of summer.The main algae species responsible for blue-green algae bloom were Anabaena flos-aquae, Microcystis aeruginosa, M. ichtyoblabe, M. flos-aquae and M. wesenbergii. Dissolved oxygen values varied between 3.4 - 19.5 mg l-1, pH ranged from 7.6 - 9.7. Secchi depth varied from 0- 65 cm in the Zámecký pond, 15-45 cm in the Růžový pond and 35-65 cm in the Dyje River. Concentration of total phosphate, nitrate and chlorophyll-a in the Dyje River before drainage into the Zámecký and Růžový pond verified heavy nutrient load (Total-P = 0.3, NO3- = 12 mg.l-1 of the river. Although the Dyje River is main water source for both ponds, presence of relatively different phytoplankton communities in these two ponds suggest that probably different nutrient sources might be responsible for differences in phytoplankton communities and eutrophication patterns in the Zámecký pond as compared to the Růžový pond.

Mesoscale features and phytoplankton biomass at the GoodHope ...

African Journals Online (AJOL)

The observations provide evidence to show that the fronts act to both enhance phytoplankton biomass as well as to delimit regions of similar chlorophyll concentrations, although the front–chlorophyll relationships become obscure towards the end of the growing season due to bloom advection and 'patchy' Chl a behaviour.
A Satellite-Based Lagrangian View on Phytoplankton Dynamics

Science.gov (United States)

Lehahn, Yoav; d'Ovidio, Francesco; Koren, Ilan

2018-01-01

The well-lit upper layer of the open ocean is a dynamical environment that hosts approximately half of global primary production. In the remote parts of this environment, distant from the coast and from the seabed, there is no obvious spatially fixed reference frame for describing the dynamics of the microscopic drifting organisms responsible for this immense production of organic matter—the phytoplankton. Thus, a natural perspective for studying phytoplankton dynamics is to follow the trajectories of water parcels in which the organisms are embedded. With the advent of satellite oceanography, this Lagrangian perspective has provided valuable information on different aspects of phytoplankton dynamics, including bloom initiation and termination, spatial distribution patterns, biodiversity, export of carbon to the deep ocean, and, more recently, bottom-up mechanisms that affect the distribution and behavior of higher-trophic-level organisms. Upcoming submesoscale-resolving satellite observations and swarms of autonomous platforms open the way to the integration of vertical dynamics into the Lagrangian view of phytoplankton dynamics.
A Satellite-Based Lagrangian View on Phytoplankton Dynamics.

Science.gov (United States)

Lehahn, Yoav; d'Ovidio, Francesco; Koren, Ilan

2018-01-03

The well-lit upper layer of the open ocean is a dynamical environment that hosts approximately half of global primary production. In the remote parts of this environment, distant from the coast and from the seabed, there is no obvious spatially fixed reference frame for describing the dynamics of the microscopic drifting organisms responsible for this immense production of organic matter-the phytoplankton. Thus, a natural perspective for studying phytoplankton dynamics is to follow the trajectories of water parcels in which the organisms are embedded. With the advent of satellite oceanography, this Lagrangian perspective has provided valuable information on different aspects of phytoplankton dynamics, including bloom initiation and termination, spatial distribution patterns, biodiversity, export of carbon to the deep ocean, and, more recently, bottom-up mechanisms that affect the distribution and behavior of higher-trophic-level organisms. Upcoming submesoscale-resolving satellite observations and swarms of autonomous platforms open the way to the integration of vertical dynamics into the Lagrangian view of phytoplankton dynamics.
A prospective study of marine phytoplankton and reported ...

Science.gov (United States)

BACKGROUND: Blooms of marine phytoplankton may adversely affect human health. The potential public health impact of low-level exposures is not well established, and few prospective cohort studies of recreational exposures to marine phytoplankton have been conducted.OBJECTIVE: We evaluated the association between phytoplankton cell counts and subsequent illness among recreational beachgoers.METHODS:We recruited beachgoers at Boquer6n Beach, Puerto Rico, during the summer of 2009. We conducted interviews at three time points to assess baseline health, water activities, and subsequent illness. Daily water samples were quantitatively assayed for phytoplankton cell count. Logistic regression models, adjusted for age and sex, were used to assess the association between exposure to three categories of phytoplankton concentration and subsequent illness.RESULTS: During 26 study days, 15,726 individuals successfully completed all three interviews. Daily total phytoplankton cell counts ranged from 346 to 2,012 cells/ml (median, 712 cells/ml). The category with the highest (≥75th percentile) total phytoplankton cell count was associated with eye irritation [adjusted odds ratio (OR) = 1.30; 95% confidence interval (Cl): 1.01, 1.66], rash (OR = 1.27; 95% Cl: 1.02, 1.57), and earache (OR = 1.25; 95% Cl: 0.88, 1.77). In phytoplankton group-specific analyses, the category with the highest Cyanobacteria counts was associated with respiratory illness (OR = 1.37; 95% Cl: 1.12, 1
Does temperature structure phytoplankton community composition in the Ross Sea, Antarctica?

Science.gov (United States)

The Ross Sea polynya experiences one of the largest phytoplankton blooms in the Southern Ocean. Energy flow potential within the Ross Sea food web is primarily set by diatoms and prymnesiophytes, the latter dominated by Phaeocystis antarctica. We investigated physical, chemical,...
Spatio-temporal changes in the distribution of phytopigments and phytoplanktonic groups at the Porcupine Abyssal Plain (PAP) site

Science.gov (United States)

Smythe-Wright, Denise; Boswell, Stephen; Kim, Young-Nam; Kemp, Alan

2010-08-01

We have made a comprehensive study of pigment distributions and microscopically determined phytoplankton abundances within the Porcupine Abyssal Plain (PAP) location in the North Atlantic to better understand phytoplankton variability, and make some suggestions regarding the composition of the material falling to the sea bed and its impacts on benthic organisms such as Amperima rosea. The area has been the focus of many studies of ocean fluxes and benthic communities over recent years, but little attention has been given to the spatio-temporal variability in the surface waters. Dawn casts over a 12-day period at the PAP mooring site (48.83°N 16.5°W) revealed the presence of only one species, the diatom Actinocyclus exiguus, at bloom concentrations for just 5 days. Smaller populations of other diatoms and the dinoflagellates Gymnodinium and Gyrodinium were also present at this time. Following this 5-day interval, a mixed population of small-sized dinoflagellates, prymnesiophytes, prasinophytes, chrysophytes and cyanobacteria occurred. It is clear from concomitant CTD/bottle surveys that rapid changes in phytoplankton community structure at a fixed time series position do not necessarily reflect a degradation or manifestation of one particular species but rather represent the movement of eddies and other water masses within very short timescales. These cause substantial variability in the species class and size fraction that may explain the variability in carbon export that has been seen at the PAP site. We also make some suggestions on the variable composition of the material falling to the seabed and its impact on benthic organisms such as Amperima rosea.
BIOMARKER LIPIDS IN RED TIDE (GYMNODINIUM BREVE) BLOOMS ALONG THE NORTHWEST FLORIDA COAST

Science.gov (United States)

The ability to characterize phytoplankton communities and algal blooms using lipids as biomarkers requires knowledge of their distribution and taxonomic significance. Such an approach would have application, for example, in distinguishing and tracking certain dinoflagellates suc...
Improving estimation of phytoplankton isotopic values from bulk POM samples in rivers

Science.gov (United States)

Background/Questions/MethodsResponses of phytoplankton to excessive nutrients in rivers cause many ecological problems, including harmful algal blooms, hypoxia and even food web collapse, posing serious risks to fish and human health. Successful remediation requires identificati...
Testing the Metabolic Theory of Ecology with marine bacteria: Different temperature sensitivity of major phylogenetic groups during the spring phytoplankton bloom

KAUST Repository

Arandia-Gorostidi, Nestor

2017-08-24

Although temperature is a key driver of bacterioplankton metabolism, the effect of ocean warming on different bacterial phylogenetic groups remains unclear. Here, we conducted monthly short-term incubations with natural coastal bacterial communities over an annual cycle to test the effect of experimental temperature on the growth rates and carrying capacities of four phylogenetic groups: SAR11, Rhodobacteraceae, Gammaproteobacteria and Bacteroidetes. SAR11 was the most abundant group year-round as analysed by CARD-FISH, with maximum abundances in summer, while the other taxa peaked in spring. All groups, including SAR11, showed high temperature-sensitivity of growth rates and/or carrying capacities in spring, under phytoplankton bloom or post-bloom conditions. In that season, Rhodobacteraceae showed the strongest temperature response in growth rates, estimated here as activation energy (E, 1.43 eV), suggesting an advantage to outcompete other groups under warmer conditions. In summer E values were in general lower than 0.65 eV, the value predicted by the Metabolic Theory of Ecology (MTE). Contrary to MTE predictions, carrying capacity tended to increase with warming for all bacterial groups. Our analysis confirms that resource availability is key when addressing the temperature response of heterotrophic bacterioplankton. We further show that even under nutrient-sufficient conditions, warming differentially affected distinct bacterioplankton taxa. This article is protected by copyright. All rights reserved.
Fine-scale distribution of zooplankton is linked to phytoplankton species composition and abundance in a North Norwegian fjord system

Science.gov (United States)

Norrbin, F.; Priou, P. D.; Varela, A. P.

2016-02-01

We studied the influence of dense layers of phytoplankton and aggregates on shaping the vertical distribution of zooplankton in a North Norwegian fjord using a Video Plankton Recorder (VPR). This instrument provided fine-scale vertical distribution (cm-m scale) of planktonic organisms as well as aggregates of marine snow in relation to environmental conditions. At the height - later stage of the spring phytoplankton bloom in May, the outer part of the fjord was dominated by Phaeocystis pouchetii, while diatoms (Chaetoceros spp.) were dominating in the innermost basin. Small copepods species like Pseudocalanus spp., Microsetella norvegica, and Oithona spp. prevailed over larger copepod species in the inner part of the fjord whereas the outer part was dominated by large copepods like Calanus finmarchicus. While the zooplankton where spread out over the water column during the early stage of the bloom, in May they were linked to the phytoplankton vertical distribution and in the winter situation they were found in deeper waters. Herbivorous zooplankton species were affected by phytoplankton species composition; C. finmarchicus and Pseudocalanus spp. avoided the dense layer of P. pouchetii while herbivorous zooplankton matched the distribution of the diatom-dominated bloom. Small, omnivorous copepod species like Microsetella sp., Oithona sp. and Pseudocalanus sp. were often associated with dense layers of snow aggregates. This distribution may provide a shelter from predators as well as a food source. Natural or anthropogenic-induced changes in phytoplankton composition and aggregate distribution may thus influence food-web interactions.
Study of Under-ice Blooms In the Chukchi Ecosystem (SUBICE) (HLY1401, EM122)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The primary objectives of SUBICE were to determine the spatial distribution of large under-ice phytoplankton blooms on the Chukchi Shelf and the physical mechanisms...
Seasonal Dynamics of Sublittoral Meiobenthos in Relation to Phytoplankton Sedimentation in the Baltic Sea

Science.gov (United States)

Ólafsson, E.; Elmgren, R.

1997-08-01

Meiobenthic metazoans (40-500) μm were sampled monthly at a 37 m deep station in the north-western Baltic Sea proper. Nematodes dominated the meiofauna, ranging from 67% of total abundance in February to 91% in September. Harpacticoid copepods were the second most common group, ranging from 2% in September to 15% in February. Total meiofauna shell-free dry weight biomass was lowest in winter (0·9 mg 10 cm -2in January), and increased rapidly following the spring bloom, to high values in May-July (peak 1·7 mg 10 cm -2in July). As an annual average, ostracods contributed most to biomass, 38%, while nematodes and harpacticoids made up 24 and 15%, respectively. Only nematodes were common below 2 cm depth in the sediment, and few nematodes penetrated below 4 cm. Of Wieser's morphologically based nematode feeding groups, epistrate feeders dominated the surface sediment, and non-selective deposit feeders dominated the deeper layer in May. Total nematode abundance was significantly different among dates, with lowest numbers in winter and spring (October-April), and almost doubled within about 2 months after the spring phytoplankton bloom in March. There was a significant increase in selective deposit feeders and epistrate feeders after the spring bloom. Harpacticoid copepods were almost all of two species, Pseudobradyasp. and Microarthridion littorale, both of which differed significantly in abundance among months, and displayed continuous reproduction throughout the year, with a peak in pairs in precopula in winter for Pseudobradyasp. and in ovigerous females in M. littoraleafter the spring bloom. Pseudobradyawas significantly more numerous in winter than in other seasons. Microarthridion littoralehad its highest abundance from July to October. Three species of ostracods were common throughout the year and all differed significantly in numbers among months. Turbellaria, Kinorhyncha were found in lowest numbers during winter and peaked in summer. The peak of newly
Long-term allelopathic control of phytoplankton by the submerged macrophyte Elodea nuttallii

NARCIS (Netherlands)

Vanderstukken, M.; Declerck, S.A.J.; Decaestecker, E.; Muylaert, K.

2014-01-01

Keywords: allelochemicals; chemical ecology; competition; nutrient limitation; shallow lakes Summary 1.It is well known that submerged macrophytes can suppress phytoplankton blooms in lakes and thus promote water quality and biodiversity. One of the possible mechanisms through which submerged
Influence of Vitamin B Auxotrophy on Nitrogen Metabolism in Eukaryotic Phytoplankton

Directory of Open Access Journals (Sweden)

Erin M Bertrand

2012-10-01

Full Text Available While nitrogen availability is known to limit primary production in large parts of the ocean, vitamin starvation amongst eukaryotic phytoplankton is becoming increasingly recognized as an oceanographically relevant phenomenon. Cobalamin (B12 and thiamine (B1 auxotrophy are widespread throughout eukaryotic phytoplankton, with over 50% of cultured isolates requiring B12 and 20% requiring B1. The frequency of vitamin auxotrophy in harmful algal bloom species is even higher. Instances of colimitation between nitrogen and B vitamins have been observed in marine environments, and interactions between these nutrients have been shown to impact phytoplankton species composition. This review evaluates the potential for interactive effects of nitrogen and vitamin B12 and B1 starvation in eukaryotic phytoplankton. B12 plays essential roles in amino acid and one-carbon metabolism, while B1 is important for primary carbohydrate and amino acid metabolism and likely useful as an anti-oxidant. Here we will focus on three potential metabolic interconnections between vitamin, nitrogen and sulfur metabolism that may have ramifications for the role of vitamin and nitrogen scarcities in driving ocean productivity and species composition. These include: (1 B12, B1, and N starvation impacts on osmolyte and antioxidant production, (2 B12 and B1 starvation impacts on polyamine biosynthesis, and (3 influence of B12 and B1 starvation on the diatom urea cycle and amino acid recycling through impacts on the citric acid cycle. We evaluate evidence for these interconnections and identify oceanographic contexts in which each may impact rates of primary production and phytoplankton community composition. Major implications include that B12 and B1 deprivation may impair the ability of phytoplankton to recover from nitrogen starvation and that changes in vitamin and nitrogen availability may synergistically impact harmful algal bloom formation.
Dinoflagellate blooms in upwelling systems: Seeding, variability, and contrasts with diatom bloom behaviour

Science.gov (United States)

Smayda, T. J.; Trainer, V. L.

2010-04-01

disassociation suggests unrecognized upwelling system factors that fall within the physical-chemical-biological domain are more important than life cycle in selecting dinoflagellates species having the survival-seeding strategies and ecophysiological adaptations required for growth in physically robust upwelling systems. It is conjectured that diatom life cycles, as a group, are geared towards exploiting seeding opportunities, whereas dinoflagellates have evolved life-cycle behaviour more attuned to survival. The role of ecological dormancy and ecological release from bloom inhibition underlying dinoflagellate bloom irregularity is considered. The expectation that the dinoflagellate species selected to bloom from among the common upwelling flora would be the same in all eastern boundary upwelling systems is not realized.
Thermal Thresholds of Phytoplankton Growth in Polar Waters and Their Consequences for a Warming Polar Ocean

KAUST Repository

Coello-Camba, Alexandra

2017-06-02

Polar areas are experiencing the steepest warming rates on Earth, a trend expected to continue in the future. In these habitats, phytoplankton communities constitute the basis of the food web and their thermal tolerance may dictate how warming affects these delicate environments. Here, we compiled available data on thermal responses of phytoplankton growth in polar waters. We assembled 53 growth-vs.-temperature curves (25 from the Arctic, 28 from the Southern oceans), indicating the limited information available for these ecosystems. Half of the data from Arctic phytoplankton came from natural communities where low ambient concentrations could limit growth rates. Phytoplankton from polar waters grew faster under small temperature increases until reaching an optimum (TOPT), and slowed when temperatures increased beyond this value. This left-skewed curves were characterized by higher activation energies (Ea) for phytoplankton growth above than below the TOPT. Combining these thermal responses we obtained a community TOPT of 6.5°C (±0.2) and 5.2°C (±0.1) for Arctic and Southern Ocean phytoplankton communities, respectively. These threshold temperatures were already exceeded at 70°N during the first half of August 2013, evidenced by sea surface temperatures (SSTs, satellite data, http://www.ncdc.noaa.gov). We forecasted SSTs for the end of the twenty-first century by assuming an overall 3°C increase, equivalent to a low emission scenario. Our forecasts show that SSTs at 70°N are expected to exceed TOPT during summer by 2100, and during the first half of August at 75°N. While recent Arctic spring temperatures average 0.5°C and −0.7°C at 70°N and 75°N, respectively, they could increase to 2.8°C at 70°N and 2.2°C at 75°N as we approach 2100. Such temperature increases could lead to intense phytoplankton blooms, shortened by fast nutrient consumption. As SSTs increase, thermal thresholds for phytoplankton growth would be eventually exceeded during bloom
Thermal Thresholds of Phytoplankton Growth in Polar Waters and Their Consequences for a Warming Polar Ocean

Directory of Open Access Journals (Sweden)

Alexandra Coello-Camba

2017-06-01

Full Text Available Polar areas are experiencing the steepest warming rates on Earth, a trend expected to continue in the future. In these habitats, phytoplankton communities constitute the basis of the food web and their thermal tolerance may dictate how warming affects these delicate environments. Here, we compiled available data on thermal responses of phytoplankton growth in polar waters. We assembled 53 growth-vs.-temperature curves (25 from the Arctic, 28 from the Southern oceans, indicating the limited information available for these ecosystems. Half of the data from Arctic phytoplankton came from natural communities where low ambient concentrations could limit growth rates. Phytoplankton from polar waters grew faster under small temperature increases until reaching an optimum (TOPT, and slowed when temperatures increased beyond this value. This left-skewed curves were characterized by higher activation energies (Ea for phytoplankton growth above than below the TOPT. Combining these thermal responses we obtained a community TOPT of 6.5°C (±0.2 and 5.2°C (±0.1 for Arctic and Southern Ocean phytoplankton communities, respectively. These threshold temperatures were already exceeded at 70°N during the first half of August 2013, evidenced by sea surface temperatures (SSTs, satellite data, http://www.ncdc.noaa.gov. We forecasted SSTs for the end of the twenty-first century by assuming an overall 3°C increase, equivalent to a low emission scenario. Our forecasts show that SSTs at 70°N are expected to exceed TOPT during summer by 2100, and during the first half of August at 75°N. While recent Arctic spring temperatures average 0.5°C and −0.7°C at 70°N and 75°N, respectively, they could increase to 2.8°C at 70°N and 2.2°C at 75°N as we approach 2100. Such temperature increases could lead to intense phytoplankton blooms, shortened by fast nutrient consumption. As SSTs increase, thermal thresholds for phytoplankton growth would be eventually exceeded
Thermal Thresholds of Phytoplankton Growth in Polar Waters and Their Consequences for a Warming Polar Ocean

KAUST Repository

Coello-Camba, Alexandra; Agusti, Susana

2017-01-01

Polar areas are experiencing the steepest warming rates on Earth, a trend expected to continue in the future. In these habitats, phytoplankton communities constitute the basis of the food web and their thermal tolerance may dictate how warming affects these delicate environments. Here, we compiled available data on thermal responses of phytoplankton growth in polar waters. We assembled 53 growth-vs.-temperature curves (25 from the Arctic, 28 from the Southern oceans), indicating the limited information available for these ecosystems. Half of the data from Arctic phytoplankton came from natural communities where low ambient concentrations could limit growth rates. Phytoplankton from polar waters grew faster under small temperature increases until reaching an optimum (TOPT), and slowed when temperatures increased beyond this value. This left-skewed curves were characterized by higher activation energies (Ea) for phytoplankton growth above than below the TOPT. Combining these thermal responses we obtained a community TOPT of 6.5°C (±0.2) and 5.2°C (±0.1) for Arctic and Southern Ocean phytoplankton communities, respectively. These threshold temperatures were already exceeded at 70°N during the first half of August 2013, evidenced by sea surface temperatures (SSTs, satellite data, http://www.ncdc.noaa.gov). We forecasted SSTs for the end of the twenty-first century by assuming an overall 3°C increase, equivalent to a low emission scenario. Our forecasts show that SSTs at 70°N are expected to exceed TOPT during summer by 2100, and during the first half of August at 75°N. While recent Arctic spring temperatures average 0.5°C and −0.7°C at 70°N and 75°N, respectively, they could increase to 2.8°C at 70°N and 2.2°C at 75°N as we approach 2100. Such temperature increases could lead to intense phytoplankton blooms, shortened by fast nutrient consumption. As SSTs increase, thermal thresholds for phytoplankton growth would be eventually exceeded during bloom
Ocean acidification with (de)eutrophication will alter future phytoplankton growth and succession

DEFF Research Database (Denmark)

Flynn, Kevin J.; Darren, Clark R.; Mitra, Aditee

2015-01-01

Human activity causes ocean acidification (OA) though the dissolution of anthropogenically generated CO2 into seawater, and eutrophication through the addition of inorganic nutrients. Eutrophication increases the phytoplankton biomass that can be supported during a bloom, and the resultant uptake...
The sedimentary record of dinoflagellate cysts: looking back into the future of phytoplankton blooms

Directory of Open Access Journals (Sweden)

Barrie Dale

2001-12-01

Full Text Available Marine systems are not as well understood as terrestrial systems, and there is still a great need for more primary observations, in the tradition of the old-time naturalists, before newer methods such as molecular genetics and modeling can be fully utilized. The scientific process whereby the smaller, detailed building blocks of observation are ultimately linked towards better understanding natural systems is illustrated from my own career experience, especially with regard to the dinoflagellates and plankton blooms. Some dinoflagellates produce a fossilizable resting stage (cyst in their life cycle, and dinoflagellate cysts have become one of the most important groups of microfossils used in geological exploration (e.g. oil and gas. This has stimulated both paleontological and biological research producing detailed building blocks of information, currently scattered throughout the respective literature. Here, I attempt to bring together the present day perspective, from biology, with the past, from paleontology, as the most comprehensive basis for future work on the group. This shows the cysts to be the critical link needed for focusing future molecular genetics studies towards a more verifiable view of evolutionary pathways, and it also suggests new integrated methods for studying past, present, and future blooms. The large, rapidly growing field of harmful algal bloom studies is producing many different building blocks, but plankton blooms as episodic phenomena are still poorly understood. This is largely due to the general lack of long-term datasets allowing identification of the changing environmental factors that permit certain species to bloom at unpredictable intervals of time. Cysts in sediments are useful environmental indicators today, e.g. reflecting aspects of climate and pollution, and provide information directly relevant to some dinoflagellate blooms. They therefore may be used for obtaining retrospective information from the

Massive outbreaks of Noctiluca scintillans blooms in the Arabian Sea due to spread of hypoxia.

Digital Repository Service at National Institute of Oceanography (India)

Gomes, H.R.; Goes, J.I.; Matondkar, S.G.P.; Buskey, E.J.; Basu, S.; Parab, S.G.; Thoppil, P.G.

In the last decade, the northern Arabian Sea has witnessed a radical shift in the composition of winter phytoplankton blooms, which previously comprised mainly of diatoms, the unicellular, siliceous photosynthetic organisms favoured by nutrient...
Determination of phytoplankton abundances (Chlorophyll-a) in the optically complex inland water - The Baltic Sea.

Science.gov (United States)

Zhang, Daoxi; Lavender, Samantha; Muller, Jan-Peter; Walton, David; Karlson, Bengt; Kronsell, Johan

2017-12-01

A novel approach, termed Summed Positive Peaks (SPP), is proposed for determining phytoplankton abundances (Chlorophyll-a or Chl-a) and surface phytoplankton bloom extent in the optically complex Baltic Sea. The SPP approach is established on the basis of a baseline subtraction method using Rayleigh corrected top-of-atmosphere data from the Medium Resolution Imaging Spectrometer (MERIS) measurements. It calculates the reflectance differences between phytoplankton related signals observed in the MERIS red and near infrared (NIR) bands, such as sun-induced chlorophyll fluorescence (SICF) and the backscattering at 709nm, and considers the summation of the positive line heights for estimating Chl-a concentrations. The SPP algorithm is calibrated against near coincident in situ data collected from three types of phytoplankton dominant waters encountered in the Baltic Sea during 2010 (N=379). The validation results show that the algorithm is capable of retrieving Chl-a concentrations ranging from 0.5 to 3mgm -3 , with an RMSE of 0.24mgm -3 (R 2 =0.69, N=264). Additionally, the comparison results with several Chl-a algorithms demonstrates the robustness of the SPP approach and its sensitivity to low to medium biomass waters. Based on the red and NIR reflectance features, a flagging method is also proposed to distinguish intensive surface phytoplankton blooms from the background water. Copyright © 2017 Elsevier B.V. All rights reserved.
Potentially harmful microalgae and algal blooms in a eutrophic estuary in Turkey

Directory of Open Access Journals (Sweden)

S. TAS

2015-07-01

Full Text Available Distribution of potentially harmful microalgae and algal blooms were investigated at monthly and weekly time scales between October 2009 and September 2010 in the Golden Horn, a eutrophic estuary in the Sea of Marmara (Turkey. Several physical and chemical parameters were analysed together with phytoplankton composition and abundance. A total number of 23 potentially harmful and/or bloom-forming microalgae (14 dinoflagellates, 4 diatoms and 5 phytoflagellates were identified throughout this study period, of which nine taxa have been confirmed to be toxic elsewhere in the world. Most harmful species and algal blooms were observed in late spring and summer particularly in the middle and upper estuaries, and nine taxa formed dense and successive algal blooms causing water discoloration. Nutrient concentrations increased significantly from the lower to the upper estuary. Additionally, high organic matter loads in the upper estuary could also have benefited by mixotrophic species. The increasing number of potentially harmful and bloom-forming species and algal blooms indicated that the GHE is a potential risk area for future HABs.
Simultaneous elimination of cyanotoxins and PCBs via mechanical collection of cyanobacterial blooms: An application of "green-bioadsorption concept".

Science.gov (United States)

Chen, Wei; Jia, Yunlu; Liu, Anyue; Zhou, Qichao; Song, Lirong

2017-07-01

In this study, the distribution, transfer and fate of both polychlorinated biphenyls (PCBs) and cyanotoxins via phytoplankton routes were systematically investigated in two Chinese lakes. Results indicated that PCB adsorption/bioaccumulation dynamics has significantly positive correlations with the biomass of green alga and diatoms. Total lipid content of phytoplankton is the major factor that influences PCB adsorption/bioaccumulation. Cyanobacterial blooms with relatively lower lipid content could also absorb high amount of PCBs due to their high cell density in the water columns, and this process was proposed as major route for the transfer of PCBs in Chinese eutrophic freshwater. According to these findings, a novel route on fates of PCBs via phytoplankton and a green bioadsorption concept were proposed and confirmed. In the practice of mechanical collections of bloom biomass from Lake Taihu, cyanotoxin/cyanobacteria and PCBs were found to be removed simultaneously very efficiently followed this theory. Copyright © 2016. Published by Elsevier B.V.
An Ephemeral Dinoflagellate Bloom during Summer Season in Nearshore Water of Puri, East Coast of India

Science.gov (United States)

Baliarsingh, Sanjiba Kumar; Dwivedi, Rashmin; Lotliker, Aneesh A.; Jayashankar, Reeta; Sahu, Biraja Kumar; Srichandan, Suchismita; Samanta, Alakes; Parida, Chandanlal; Srinivasakumar, Tummala; Sahu, Kali Charan

2018-03-01

The present paper reports on the phenomenon of pinkish-red discoloration of the nearshore water of Puri, Odisha on 12th May 2016. Many local newspapers covered this event, as Puri city is a major tourist and pilgrimage place on the east coast of India. Field observations were carried out in order to provide a scientific basis to the event and to elicit possible causes of this discoloration. Taxonomic analysis of the phytoplankton samples revealed the dominance of red colored dinoflagellate species Gonyaulax polygramma, contributing 90% to total phytoplankton population. The localized concentration of G. polygramma was responsible for the pinkish-red discoloration of nearshore water. The exact factor that lay behind the genesis of this bloom could not be delineated due to the short period of its persistence. But two factors - upwelling and anthropogenic nutrient influx - can be viewed as the main cause for this ephemeral bloom. Non-hypoxic conditions in the coastal water following the ephemeral bloom event indicated no significant risk of ecological deterioration to the ambient medium.
Oceanic and atmospheric influences on the variability of phytoplankton bloom in the southwestern Indian Ocean

Digital Repository Service at National Institute of Oceanography (India)

Raj, R.P.; Peter, B.N.; Pushpadas, D.

in the Mozambique Basin and inside the Mozambique Channel (MC). For a detailed inspection, we characterized the entire process of the development of this large dendritic bloom into two stages, early stage... period was in March. During 2001 and 2003, traces of the bloom (low concentration of chl-a) are observed in the MC and Mozambique Basin but not in the Madagascar basin. A weak bloom developed in the Madagascar Basin, Mozambique Basin and inside the MC...
Interannual variation of spring phytoplankton bloom and response to turbulent energy generated by atmospheric forcing in the central Southern Yellow Sea of China: Satellite observations and numerical model study

Science.gov (United States)

Shi, Jie; Liu, Yi; Mao, Xinyan; Guo, Xinyu; Wei, Hao; Gao, Huiwang

2017-07-01

The interannual variations of the start timing, magnitude and duration of the spring phytoplankton bloom (SPB) in the central southern Yellow Sea (SYS) were studied using the satellite-derived surface chlorophyll-a concentrations (Chl-a) from 2000 to 2014. The correlations between the characteristics of SPB and the generation rate of turbulent kinetic energy (TKERT) supplied from the atmosphere to the ocean were examined. The start timing of SPB was delayed in years with high TKERT supplied to the ocean before SPB. The TKERT during SPB had no relationship with the magnitude of SPB, but had positive correlation with the duration. A 1-D physical-biological model was used to examine the influencing mechanisms of the TKERT on the characteristics of SPB quantitatively. The wind speeds and related TKERT before the start of SPB were stronger in 2010 than in 2008. Comparison of the model results forced by winds in the two years suggested that the enhanced physical dilution of phytoplankton caused by the stronger TKERT in 2010 induced a later start timing of SPB. When increasing the winds during SPB period, more phytoplankton was taken downward from the surface layer by the enhanced vertical mixing. Meanwhile, more nutrients were pumped upward to the surface layer and supported more net growth of phytoplankton. These two contrary processes led to the independence of the magnitude of SPB on the TKERT during the SPB period. However, larger TKERT along with stronger wind resulted in a longer duration of SPB because of more nutrients supply by stronger vertical mixing.
Photosynthetic pigment fingerprints as indicators of phytoplankton biomass and development in different water masses of the Southern Ocean during austral spring

Science.gov (United States)

Peeken, Ilka

The development of phytoplankton biomass and composition was investigated on three occasions along a longitudinal transect (6°W) between 60°S and 47°S from October 13 to November 21, 1992 by measurement of photosynthetic pigments with high performance liquid chromatography (HPLC). Measured accessory pigment concentrations were multiplied by conversion factors to derive the proportions of phytoplankton groups contributing to the biomass indicator chlorophyll a. Phytoplankton blooms developed in the Polar Frontal region (PFr) and were dominated (80%) by diatoms. Other groups contributing to the phytoplankton included prymnesiophytes, green algae, autotrophic dinoflagellates, cryptophytes, pelagophytes and micromonadophytes, and their distributions varied with time. In contrast, phytoplankton biomass remained low in the southern Antarctic Circumpolar Current (ACC) and was dominated by flagellates, particularly green algae and prymnesiophytes. Green algae contributed more to total biomass than in previous investigations, partly attributed to "Chlorella-like" type organisms rather than prasinophytes. Cryptophytes decreased during the investigation, possibly due to salp grazing. No bloom was observed at the retreating ice-edge, presumably due to strong wind mixing. Only a slight increase in phytoplankton biomass, composed primarily of diatoms, was found at the ACC-Weddell Gyre front. Cluster analysis revealed that different phytoplankton communities characterised the different water masses of the PFr and southern ACC; the history of different water masses in the PFr could be reconstructed on this basis.
Comparative study of hydrographic conditions for algal bloom formation in the coastal waters of east and west of Hong Kong during 1998

Science.gov (United States)

Fang, Hongda; Tang, Senming

2009-02-01

Phytoplankton abundance was found to be positively correlated with seasonal changes of seawater temperature in Port Shelter and Lamma Channel, Hong Kong in 1998. Rising water temperature from around 20°C to 25°C coincided with an increase in phytoplankton abundance at both locations. Heavy rains from June to September reduced salinity from 30 to 20, but the decrease in salinity was not correlated with a decline in phytoplankton abundance. In spring 1998, over 0.6×106 cells dm-3 and 0.1×106 cells dm-3 of the dinoflagellate, Gymnodinium mikimotoi Miyake et Kominami ex Oda occurred in the coastal waters of Port Shelter and Lamma Channel, respectively. High abundance of the dinoflagellate Ceratium furca (Ehr.) Claparede et Lachmann (>1×106 cells dm-3) produced long-lasting blooms in the waters of Port Shelter from September to October in 1998. The abundances of both diatoms and dinoflagellates were significantly lower in the waters of Lamma Channel than those in Port Shelter due to the less frequent blooms in 1998. Hydrographic conditions such as stable water masses and water column stratification were the main reasons for the differences in the algal abundance and bloom frequency found between the two locations since neither of the two areas appeared to be nutrient-limited. This type water condition for the formation of algal bloom in Port Shelter has not been reported previously and it is not a general case for many bays along China’s coast where algal bloom occurs as well.
Warming accelerates termination of a phytoplankton spring bloom by fungal parasites

NARCIS (Netherlands)

Frenken, Thijs; Velthuis, M.; De Senerpont Domis, Lisette; Stephan, Susanne; Aben, Ralf Cornelis; Kosten, S.; van Donk, E.; Van de Waal, D.B.

2016-01-01

Climate change is expected to favour infectious diseases across ecosystems worldwide. In freshwater and marine environments, parasites play a crucial role in controlling plankton population dynamics. Infection of phytoplankton populations will cause a transfer of carbon and nutrients into parasites,
Warming accelerates termination of a phytoplankton spring bloom by fungal parasites

NARCIS (Netherlands)

Frenken, Thijs; Velthuis, Mandy; Senerpont Domis, de L.N.; Stephan, Susanne; Aben, Ralf; Kosten, Sarian; Donk, van Ellen; Waal, Van de D.B.

2016-01-01

Climate change is expected to favour infectious diseases across ecosystems worldwide. In freshwater and marine environments, parasites play a crucial role in controlling plankton population dynamics. Infection of phytoplankton populations will cause a transfer of carbon and nutrients into
Differential effects of ocean acidification on carbon acquisition in two bloom-forming dinoflagellate species

NARCIS (Netherlands)

Eberlein, T.; Van de Waal, D.B.; Rost, B.

2014-01-01

Dinoflagellates represent a cosmopolitan group of phytoplankton with the ability to form harmful algal blooms. Featuring a Ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) with very low CO2-affinities, photosynthesis of this group may be particularly prone to carbon limitation and thus
Evaluating the Addition of a Dinoflagellate Phytoplankton Functional Type Using Radiance Anomalies for Monterey Bay, CA

Science.gov (United States)

Houskeeper, H. F.; Kudela, R. M.

2016-12-01

Ocean color sensors have enabled daily, global monitoring of phytoplankton productivity in the world's oceans. However, to observe key structures such as food webs, or to identify regime shifts of dominant species, tools capable of distinguishing between phytoplankton functional types using satellite remote sensing reflectance are necessary. One such tool developed by Alvain et al. (2005), PHYSAT, successfully linked four phytoplankton functional types to chlorophyll-normalized remote sensing spectra, or radiance anomalies, in case-1 waters. Yet this tool was unable to characterize dinoflagellates because of their ubiquitous background presence in the open ocean. We employ a radiance anomaly technique based on PHYSAT to target phytoplankton functional types in Monterey Bay, a region where dinoflagellate populations are larger and more variable than in open ocean waters, and thus where they may be viable targets for satellite remote sensing characterization. We compare with an existing Santa Cruz Wharf photo-pigment time series spanning from 2006 to the present to regionally ground-truth the method's predictions, and we assess its accuracy in characterizing dinoflagellates, a phytoplankton group that impacts the region's fish stocks and water quality. For example, an increase in dinoflagellate abundance beginning in 2005 led to declines in commercially important fish stocks that persisted throughout the following year. Certain species of dinoflagellates in Monterey Bay are also responsible for some of the harmful algal bloom events that negatively impact the shellfish industry. Moving toward better tools to characterize phytoplankton blooms is important for understanding ecosystem shifts, as well as protecting human health in the surrounding areas.
Iron from melting glaciers fuels phytoplankton blooms in the Amundsen Sea (Southern Ocean): Phytoplankton characteristics and productivity

NARCIS (Netherlands)

Alderkamp, A.C.; Mills, M.M.; van Dijken, G.L.; Laan, P.; Thuróczy, C.-E.; Gerringa, L.J.A.; de Baar, H.J.W.; Payne, C.D.; Visser, R.J.W.; Buma, A.G.J.; Arrigo, K.R.

2012-01-01

The phytoplankton community composition and productivity in waters of the Amundsen Sea and surrounding sea ice zone were characterized with respect to iron (Fe) input from melting glaciers. High Fe input from glaciers such as the Pine Island Glacier, and the Dotson and Crosson ice shelves resulted
Elemental analysis of single phytoplankton cells using the Lund nuclear microprobe

International Nuclear Information System (INIS)

Pallon, Jan; Elfman, Mikael; Kristiansson, Per; Malmqvist, Klas; Graneli, Edna; Sellborn, Anders; Karlsson, Chatarina

1999-01-01

The occurrence of annual marine phytoplankton blooms is becoming a global problem. In Europe, the NUTOX project supported by the EC investigates if unbalanced nutrient compositions in the water promote the dominance of harmful phytoplankton species. One of the tasks is the determination of the elemental composition of single phytoplankton cells. This is carried out using the Lund Nuclear Microprobe with a special focus on C, N, P and K. The overall aim is to understand the mechanism leading to toxin production, model it and eventually propose a counteracting method. The preparative method, used to isolate single living cells while reducing their salt environment, is an important part of the analytical procedure. A comparison of light element detection using backscattering from protons and nuclear reaction analysis using deuterons is made
Infection of phytoplankton by aerosolized marine viruses

Science.gov (United States)

Sharoni, Shlomit; Trainic, Miri; Schatz, Daniella; Lehahn, Yoav; Flores, Michel J.; Bidle, Kay D.; Ben-Dor, Shifra; Rudich, Yinon; Vardi, Assaf

2015-01-01

Marine viruses constitute a major ecological and evolutionary driving force in the marine ecosystems. However, their dispersal mechanisms remain underexplored. Here we follow the dynamics of Emiliania huxleyi viruses (EhV) that infect the ubiquitous, bloom-forming phytoplankton E. huxleyi and show that EhV are emitted to the atmosphere as primary marine aerosols. Using a laboratory-based setup, we showed that the dynamic of EhV aerial emission is strongly coupled to the host–virus dynamic in the culture media. In addition, we recovered EhV DNA from atmospheric samples collected over an E. huxleyi bloom in the North Atlantic, providing evidence for aerosolization of marine viruses in their natural environment. Decay rate analysis in the laboratory revealed that aerosolized viruses can remain infective under meteorological conditions prevailing during E. huxleyi blooms in the ocean, allowing potential dispersal and infectivity over hundreds of kilometers. Based on the combined laboratory and in situ findings, we propose that atmospheric transport of EhV is an effective transmission mechanism for spreading viral infection over large areas in the ocean. This transmission mechanism may also have an important ecological impact on the large-scale host–virus “arms race” during bloom succession and consequently the turnover of carbon in the ocean. PMID:25964340
Dynamic Changes in Bacterial Population and Corresponding Exoenzyme Activity in Response to a Tropical Phytoplankton Bloom Chattonella marina

Directory of Open Access Journals (Sweden)

Anit M. Thomas

2014-01-01

Full Text Available The raphidophyte Chattonella marina (Subrahmanyan Hara & Chihara bloom which causes lethal effects on marine ecosystem has been reported intermittently from Indian waters. In the present study, periodic samplings were made in a Chattonella marina bloom area, off Mahe, on 27 and 29 October and 1 November 2011 (in different phases of the bloom to assess the associated bacterial population and their exoenzyme activity. Microbial community composition of Chattonella marina bloom revealed a twentyfold increase in bacterial load over the nonbloom area. The bacterial genera, Micrococcus, Flavobacterium, Vibrio, and Pseudomonas, increased significantly during the declining phase of the bloom. An assessment of the extracellular enzyme production also showed a marked increase in percentage of bacterial strains, potent in protease production, suggesting the possible role of proteolytic bacteria in bloom crash. This study reveals the bacterial community succession during the bloom and indicates that bacteria play an important role in bloom regulation.
Seasonal changes in nutrients, chlorophyll a and the phytoplankton assemblage of the western subarctic gyre in the Pacific Ocean

Science.gov (United States)

Mochizuki, Mamiko; Shiga, Naonobu; Saito, Masaru; Imai, Keiri; Nojiri, Yukihiro

The standing stock and species composition of phytoplankton (>10 μm) were studied using monthly water samples collected at Stn KNOT (Kyodo North Pacific Ocean Time Series; 44°N, 155°E) in the western subarctic gyre in the Pacific Ocean through June 1998 to June 1999 (except for January-April 1999) and January-February 2000. One-liter water samples were preserved in 1% neutrally buffered formalin. Identification and enumeration of phytoplankton were made with an inverted microscope. Nutrients did not appear to be depleted for phytoplakton growth during any season. The vertical distribution of phytoplankton was primarily restricted by the pycnocline, and the bulk of phytoplankton assemblage existed within the surface mixed layer. In July, however, some senescent cells were observed at 200 m. Phytoplankton abundance clearly showed a spring maximum (i.e. spring bloom) in May. The seasonal change in cell numbers, however, did not coincide closely with the change in chlorophyll a concentration. Centric diatoms, which were composed of Thalassiosira, Chaetoceros, and Coscinodiscus, dominated all year round, and showed temporal succession. Pennate diatoms (mostly Neodenticula seminae and Fragilariopsis) increased only during the spring bloom. Dinoflagellates (mostly Gymnodinium and Prorocentrum) were low in abundance, although they increased in summer when the phytoplankton standing stock was low. Silicoflagellate abundance was extremely low. Comparing the annual species composition of phytoplankton between Stn KNOT and Stn P (50°N, 145°W) in the Alaskan Gyre, there was a remarkable difference between the two sites. The phytoplankton assemblage at Stn P is characterized by a high abundance of Rhizosolenia alata and low abundance of Thalassiosira. In contrast, Thalassiosira dominates at Stn KNOT during most seasons.
Estimation of Phytoplankton Responses to Hurricane Gonu over the Arabian Sea Based on Ocean Color Data

Directory of Open Access Journals (Sweden)

Hui Zhao

2008-08-01

Full Text Available In this study the authors investigated phytoplankton variations in the Arabian Sea associated with Hurricane Gonu using remote-sensing data of chlorophyll-a (Chl-a, sea surface temperature (SST and winds. Additional data sets used for the study included the hurricane and Conductivity-Temperature-Depth data. Hurricane Gonu, presenting extremely powerful wind intensity, originated over the central Arabian Sea (near 67.7Ã‚ÂºE, 15.1Ã‚ÂºN on June 2, 2007; it traveled along a northwestward direction and made landfall in Iran around June 7. Before Hurricane Gonu, Chl-a data indicated relatively low phytoplankton biomass (0.05-0.2 mg m-3, along with generally high SST (>28.5 Ã‚ÂºC and weak wind (<10 m s-1 in the Arabian Sea. Shortly after GonuÃ¢Â€Â™s passage, two phytoplankton blooms were observed northeast of Oman (Chl-a of 3.5 mg m-3 and in the eastern central Arabian Sea (Chl-a of 0.4 mg m-3, with up to 10-fold increase in surface Chl-a concentrations, respectively. The Chl-a in the two post-hurricane blooms were 46% and 42% larger than those in June of other years, respectively. The two blooms may be attributed to the storm-induced nutrient uptake, since hurricane can influence intensively both dynamical and biological processes through vertical mixing and Ekman Pumping.
Effect of acidification on an Arctic phytoplankton community from Disko Bay, West Greenland

DEFF Research Database (Denmark)

Thoisen, Christina; Riisgaard, Karen; Lundholm, Nina

2015-01-01

. Our findings show that coastal phytoplankton from Disko Bay is naturally exposed to pH fluctuations exceeding the experimental pH range used in most ocean acidification studies. We emphasize that studies on ocean acidification should include in situ pH before assumptions on the effect of acidification...... on marine organisms can be made. KEY WORDS: Ocean acidification · Coastal · Arctic phytoplankton · Growth rate · pH · CO2 · DIC......ABSTRACT: Long-term measurements (i.e. months) of in situ pH have not previously been reported from the Arctic; this study shows fluctuations between pH 7.5 and 8.3 during the spring bloom 2012 in a coastal area of Disko Bay, West Greenland. The effect of acidification on phytoplankton from...

Associations between marine phytoplankton and symptoms of illness among recreational beachgoers in Puerto Rico, 2009

Science.gov (United States)

While phytoplankton generally have crucial roles in marine ecosystems, a small subset can release toxins and produce harmful algal blooms (HABs). HABs can be a threat to human health as symptoms from exposure range from neurological impairment to gastrointestinal (GI), dermal, a...
Implementation of New Technologies to Monitor Phytoplankton Blooms in the South of Chile

Science.gov (United States)

Rodríguez-Benito, C.; Haag, C.; Alvial, A.

2004-05-01

A pilot project has been carried out to demonstrate the applicability of remote sensing in the Xth region of Chile, related to the monitoring of algal blooms. Most of the fish farms of the country are located in this area, where considerable economic losses for this activity are the consequence of algal blooms. The implementation of new technologies to monitor this natural disaster is one of the main goals of local institutions. The project has been developed using ENVISAT/MERIS and AATSR images and oceanographic instrumentation in order to improve the information of the ongoing coastal monitoring programs.
Enhanced crude oil biodegradative potential of natural phytoplankton-associated hydrocarbonoclastic bacteria.

Science.gov (United States)

Thompson, Haydn; Angelova, Angelina; Bowler, Bernard; Jones, Martin; Gutierrez, Tony

2017-07-01

Phytoplankton have been shown to harbour a diversity of hydrocarbonoclastic bacteria (HCB), yet it is not understood how these phytoplankton-associated HCB would respond in the event of an oil spill at sea. Here, we assess the diversity and dynamics of the bacterial community associated with a natural population of marine phytoplankton under oil spill-simulated conditions, and compare it to that of the free-living (non phytoplankton-associated) bacterial community. While the crude oil severely impacted the phytoplankton population and was likely conducive to marine oil snow formation, analysis of the MiSeq-derived 16S rRNA data revealed dramatic and differential shifts in the oil-amended communities that included blooms of recognized HCB (e.g., Thalassospira, Cycloclasticus), including putative novel phyla, as well as other groups with previously unqualified oil-degrading potential (Olleya, Winogradskyella, and members of the inconspicuous BD7-3 phylum). Notably, the oil biodegradation potential of the phytoplankton-associated community exceeded that of the free-living community, and it showed a preference to degrade substituted and non-substituted polycyclic aromatic hydrocarbons. Our study provides evidence of compartmentalization of hydrocarbon-degrading capacity in the marine water column, wherein HCB associated with phytoplankton are better tuned to degrading crude oil hydrocarbons than that by the community of planktonic free-living bacteria. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.
Applications of MODIS Fluorescent Line Height Measurements to Monitor Water Quality Trends and Algal Bloom Activity

Science.gov (United States)

Fischer, Andrew; Moreno-Mardinan, Max; Ryan, John P.

2012-01-01

Recent advances in satellite and airborne remote sensing, such as improvements in sensor and algorithm calibrations, processing techniques and atmospheric correction procedures have provided for increased coverage of remote-sensing, ocean-color products for coastal regions. In particular, for the Moderate Resolution Imaging Spectrometer (MODIS) sensor calibration updates, improved aerosol retrievals and new aerosol models has led to improved atmospheric correction algorithms for turbid waters and have improved the retrieval of ocean color in coastal waters. This has opened the way for studying ocean phenomena and processes at finer spatial scales, such as the interactions at the land-sea interface, trends in coastal water quality and algal blooms. Human population growth and changes in coastal management practices have brought about significant changes in the concentrations of organic and inorganic, particulate and dissolved substances entering the coastal ocean. There is increasing concern that these inputs have led to declines in water quality and have increase local concentrations of phytoplankton, which cause harmful algal blooms. In two case studies we present MODIS observations of fluorescence line height (FLH) to 1) assess trends in water quality for Tampa Bay, Florida and 2) illustrate seasonal and annual variability of algal bloom activity in Monterey Bay, California as well as document estuarine/riverine plume induced red tide events. In a comprehensive analysis of long term (2003-2011) in situ monitoring data and satellite imagery from Tampa Bay we assess the validity of the MODIS FLH product against chlorophyll-a and a suite of water quality parameters taken in a variety of conditions throughout a large optically complex estuarine system. A systematic analysis of sampling sites throughout the bay is undertaken to understand how the relationship between FLH and in situ chlorophyll-a responds to varying conditions and to develop a near decadal trend in
A dinoflagellate Cochlodinium geminatum bloom in the Zhujiang (Pearl) River estuary in autumn 2009

Science.gov (United States)

Ke, Zhixin; Huang, Liangmin; Tan, Yehui; Song, Xingyu

2012-05-01

A severe Cochlodinium geminatum red tide (>300 km2) was observed in the Zhujiang (Pearl) River estuary, South China Sea in autumn 2009. We evaluated the environmental conditions and phytoplankton community structure during the outbreak. The red tide water mass had significantly higher dissolved inorganic phosphate (DIP), ammonia, and temperature, but significantly lower nitrite, nitrate, dissolved inorganic nitrogen (DIN), and DIN/DIP relative to the non-red-tide zones. The phytoplankton assemblage was dominated by dinoflagellates and diatoms during the red tide. C. geminatum was the most abundant species, with a peak density of 4.13×107 cell/L, accounting for >65% of the total phytoplankton density. The DIN/DIP ratio was the most important predictor of species, accounting for 12.45% of the total variation in the phytoplankton community. Heavy phosphorus loading, low precipitation, and severe saline intrusion were likely responsible for the bloom of C. geminatum.
How many Coccolithovirus genotypes does it take to terminate an Emiliania huxleyi bloom?

Science.gov (United States)

Highfield, Andrea; Evans, Claire; Walne, Anthony; Miller, Peter I; Schroeder, Declan C

2014-10-01

Giant viruses are known to be significant mortality agents of phytoplankton, often being implicated in the terminations of large Emiliania huxleyi blooms. We have previously shown the high temporal variability of E. huxleyi-infecting coccolithoviruses (EhVs) within a Norwegian fjord mesocosm. In the current study we investigated EhV dynamics within a naturally-occurring E. huxleyi bloom in the Western English Channel. Using denaturing gradient gel electrophoresis and marker gene sequencing, we uncovered a spatially highly dynamic Coccolithovirus population that was associated with a genetically stable E. huxleyi population as revealed by the major capsid protein gene (mcp) and coccolith morphology motif (CMM), respectively. Coccolithoviruses within the bloom were found to be variable with depth and unique virus populations were detected at different stations sampled indicating a complex network of EhV-host infections. This ultimately will have significant implications to the internal structure and longevity of ecologically important E. huxleyi blooms. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.
High export via small particles before the onset of the North Atlantic spring bloom

DEFF Research Database (Denmark)

Giering, S. L. C.; Sanders, R.; Martin, A. P.

2016-01-01

Sinking organic matter in the North Atlantic Ocean transfers 1-3 Gt carbon yr-1 from the surface ocean to the interior. The majority of this exported material is thought to be in form of large, rapidly sinking particles that aggregate during or after the spring phytoplankton bloom. However, recent...
Dinoflagellate community structure from the stratified environment of the Bay of Bengal, with special emphasis on harmful algal bloom species

Digital Repository Service at National Institute of Oceanography (India)

Naik, R.K.; Hegde, S.; Anil, A.C.

the total marine phytoplankton species, approximately 7% are capable of forming algal blooms (red tides) (Sournia 1995); dinoflagellates are the most important group producing toxic and harmful algal blooms (Steidinger 1983, 1993; Anderson 1989... Taxonomic identification revealed 134 species of dinoflagellates in surface waters of the BOB during the observation period (Table 2). Further grouping of these identified species based on their nutritional mode, revealed 40 autotrophic, 50 mixotrophic...
Algal blooms increase heterotrophy at the base of boreal lake food webs-Evidence from fatty acid biomarkers

NARCIS (Netherlands)

Johansson, K.S.L.; Trigal, C.; Vrede, T.; van Rijswijk, P.; Goedkoop, W.; Johnson, R.K.

2016-01-01

Physical defenses and grazer avoidance of the bloom-forming microalga Gonyostomum semen may reduce the direct coupling between phytoplankton and higher trophic levels and result in an increased importance of alternative basal food resources such as bacteria and heterotrophic protozoans. To assess
Phytoplankton chytridiomycosis: fungal parasites of phytoplankton and their imprints on the food web dynamics

Directory of Open Access Journals (Sweden)

Télesphore eSIME - NGANDO

2012-10-01

Full Text Available Parasitism is one of the earlier and common ecological interactions in the nature, occurring in almost all environments. Microbial parasites typically are characterized by their small size, short generation time, and high rates of reproduction, with simple life cycle occurring generally within a single host. They are diverse and ubiquitous in aquatic ecosystems, comprising viruses, prokaryotes and eukaryotes. Recently, environmental 18S-rDNA surveys of microbial eukaryotes have unveiled major infecting agents in pelagic systems, consisting primarily of the fungal order of Chytridiales (chytrids. Chytrids are considered the earlier branch of the Eumycetes and produce motile, flagellated zoospores, characterized by a small size (2-6 µm and a single, posterior flagellum. The existence of these dispersal propagules includes chytrids within the so-called group of zoosporic fungi, which are particularly adapted to the plankton lifestyle where they infect a wide variety of hosts, including fishes, eggs, zooplankton, algae, and other aquatic fungi but primarily freshwater phytoplankton. Related ecological implications are huge because chytrids can killed their hosts, release substrates for microbial processes, and provide nutrient-rich particles as zoospores and short fragments of filamentous inedible hosts for the grazer food chain. Furthermore, based on the observation that phytoplankton chytridiomycosis preferentially impacts the larger size species, blooms of such species (e.g. filamentous cyanobacteria may not totally represent trophic bottlenecks. Besides, chytrid epidemics represent an important driving factor in phytoplankton seasonal successions. In this review, I summarize the knowledge on the diversity, community structure, quantitative importance, and functional roles of fungal chytrids, primarily those who are parasites of phytoplankton, and infer the ecological implications and potentials for the food web dynamics and properties.
Dynamics and genotypic composition of Emiliania huxleyi and their co-occurring viruses during a coccolithophore bloom in the North Sea.

Science.gov (United States)

Martínez, Joaquín Martínez; Schroeder, Declan C; Wilson, William H

2012-08-01

We studied the temporal succession of vertical profiles of Emiliania huxleyi and their specific viruses (EhVs) during the progression of a natural phytoplankton bloom in the North Sea in June 1999. Genotypic richness was assessed by exploiting the variations in a gene encoding a protein with calcium-binding motifs (GPA) for E. huxleyi and in the viral major capsid protein gene for EhVs. Using denaturing gradient gel electrophoresis and sequencing analysis, we showed at least three different E. huxleyi and EhV genotypic profiles during the period of study, revealing a complex, and changing assemblage at the molecular level. Our results also indicate that the dynamics of EhV genotypes reflect fluctuations in abundance of potential E. huxleyi host cells. The presence and concentration of specific EhVs in the area prior to the bloom, or EhVs transported into the area by different water masses, are significant factors affecting the structure and intraspecific succession of E. huxleyi during the phytoplankton bloom. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.
Biological control of phytoplankton by the subtropical submerged macrophytes Egeria densa and Potamogeton illinoensis: a mesocosm study

NARCIS (Netherlands)

Vanderstukken, M.; Mazzeo, N.; Colen, W.; Declerck, S.A.J.; Muylaert, K.

2011-01-01

1. In temperate regions, submerged macrophytes can hamper phytoplankton blooms. Such an effect could arise directly, for instance via allelopathy, or indirectly, via competition for nutrients or the positive interaction between submerged macrophytes and zooplankton grazing. However, there is some
Light limitation of phytoplankton biomass and macronutrient utilization in the Southern Ocean

International Nuclear Information System (INIS)

Mitchell, B.G.; Brody, E.A.; Holm-Hansen, O.; McClain, C.; Bishop, J.

1991-01-01

The Antarctic Circumpolar Current (ACC) is unique in that it has continually high concentrations of major plant nutrients but low phytoplankton biomass. This enigmatic phenomenon is the focus of significant speculation that trace nutrients, including Fe, may limit phytoplankton crop size. Global climatologies indicate that the ACC is a region with low surface temperatures, weak density stratification, little summertime surface solar irradiance, and strong wind stress. These physical phenomena act to limit growth rates of the phytoplankton community. Using a photo-physiological description of phytoplankton growth in a simple one-dimensional ecosystem model forced by observations or climatologies of mixing depth and surface irradiance, the authors make an evaluation of the potential for massive, nutrient-exhausting, phytoplankton blooms forming in the ACC. The ACC has persistent mixed layers in excess of 50 m. Literature values and model optimization indicate that the minimal aggregate specific loss rate and typical physical conditions of stratification and surface irradiance, the model predicts that phytoplankton in the ACC would not utilize >10% of the available macronutrients. Without a mechanism for increasing the strength of stratification, the authors predict that massive Fe additions to the Southern Ocean would fail to significantly mitigate the atmospheric CO 2 derived from fossil fuel
Seasonal phytoplankton blooms in the Gulf of Aden revealed by remote sensing

KAUST Repository

Gittings, John; Raitsos, Dionysios E.; Racault, Marie-Fanny; Brewin, Robert J.W.; Pradhan, Yaswant; Sathyendranath, Shubha; Platt, Trevor

2016-01-01

of remotely-sensed chlorophyll-a data (Chl-a, an index of phytoplankton biomass) acquired from the Ocean Colour Climate Change Initiative (OC-CCI) of the European Space Agency (ESA). The improved spatial coverage of OC-CCI data in the Gulf of Aden allows
Effects of the 1982-1983 El Niño on the marine phytoplankton off northern Chile

Science.gov (United States)

Avaria, Sergio; MuñOz, Pablo

1987-12-01

The evolution of phytoplankton was studied between December 1980 and August 1985. A total of 1269 net and water samples were obtained in 11 cruises as part of the Estudio Regional del Fenómeno El Niño-Chile Program covering the area extending from Arica (18°30'S) to Chañaral (26°20'S) from the coast to 200 n. mi (370 km) westward. In the period which preceded the 1982-1983 El Niño event, the coastal phytoplankton consisted predominantly of blooming diatom species which support a large phytoplanktonic biomass. The cell density up to 20 n. mi (37 km) off the coast was over 100 cells mL-1, with a maximum density nucleus near the coast, where values over 1000 cells mL-1 were found. With the anomalous conditions produced by El Niño in December 1982, changes were detected in the phytoplankton biomass and composition. There was a marked decrease in the biomass, the diatom dominance was restricted to a narrow coast band of 2 to 3 n. mi (3.7-5.5 km), and warm water species of diatoms and dinoflagellates reached the coast. These conditions reached their maximum intensity in May 1983. Phytoplankton started to return to normal conditions in December 1983 with a predominance of large diatoms, which support a biomass somewhat larger than that during El Niño. Small diatoms returned as the dominant species in large blooms in 1985. The cell numbers reached values similar to those during pre-Niño conditions, with a normal neritic and oceanic phytoplankton distribution. Red tides caused by the ciliate Mesodinium rubrum were common during normal conditions before and after El Niño.
Effects of ocean acidification on primary production in a coastal North Sea phytoplankton community.

Directory of Open Access Journals (Sweden)

Tim Eberlein

Full Text Available We studied the effect of ocean acidification (OA on a coastal North Sea plankton community in a long-term mesocosm CO2-enrichment experiment (BIOACID II long-term mesocosm study. From March to July 2013, 10 mesocosms of 19 m length with a volume of 47.5 to 55.9 m3 were deployed in the Gullmar Fjord, Sweden. CO2 concentrations were enriched in five mesocosms to reach average CO2 partial pressures (pCO2 of 760 μatm. The remaining five mesocosms were used as control at ambient pCO2 of 380 μatm. Our paper is part of a PLOS collection on this long-term mesocosm experiment. Here, we here tested the effect of OA on total primary production (PPT by performing 14C-based bottle incubations for 24 h. Furthermore, photoacclimation was assessed by conducting 14C-based photosynthesis-irradiance response (P/I curves. Changes in chlorophyll a concentrations over time were reflected in the development of PPT, and showed higher phytoplankton biomass build-up under OA. We observed two subsequent phytoplankton blooms in all mesocosms, with peaks in PPT around day 33 and day 56. OA had no significant effect on PPT, except for a marginal increase during the second phytoplankton bloom when inorganic nutrients were already depleted. Maximum light use efficiencies and light saturation indices calculated from the P/I curves changed simultaneously in all mesocosms, and suggest that OA did not alter phytoplankton photoacclimation. Despite large variability in time-integrated productivity estimates among replicates, our overall results indicate that coastal phytoplankton communities can be affected by OA at certain times of the seasonal succession with potential consequences for ecosystem functioning.
Microplanktonic community structure in a coastal system relative to a Phaeocystis bloom inferred from morphological and tag pyrosequencing methods.

Directory of Open Access Journals (Sweden)

Sébastien Monchy

Full Text Available BACKGROUND: Massive phytoplankton blooms, like the recurrent Phaeocystis proliferation observed every year in the Eastern English Channel (EEC, have a significant influence on the overall planktonic community structure and their food web dynamics. As well as being an important area for local fisheries, the EEC is an ideal ecosystem for work on microbial diversity. This is because, although its environmental context is relatively complex, it is reasonably well understood due to several years of monitoring and morphological observations of its planktonic organisms. The objective of our study was to better understand the under-explored microbial eukaryotic diversity relative to the Phaeocystis bloom. METHODOLOGY AND PRINCIPAL FINDINGS: The community structure of microplankton (diatoms, haptophytes, ciliates and dinoflagellates was studied through morphological observations and tag pyrosequencing. During the annual Phaeocystis spring bloom, the phytoplankton biomass increased by 34-fold, while the microzooplankton biomass showed a 4-fold increase, representing on average about 4.6% of the biomass of their phytoplankton prey. Tag pyrosequencing unveiled an extensive diversity of Gymnodiniaceae, with G. spirale and G. fusiformis representing the most abundant reads. An extended diversity of Phaeocystales, with partial 18S rDNA genes sequence identity as low as 85% was found, with taxa corresponding to P. globosa, but also to unknown Phaeocystaceae. CONCLUSIONS: Morphological analyses and pyrosequencing were generally in accordance with capturing frequency shifts of abundant taxa. Tag pyrosequencing allowed highlighting the maintenance of microplankton diversity during the Phaeocystis bloom and the increase of the taxa presenting low number of reads (minor taxa along with the dominant ones in response to biotic and/or abiotic changing conditions. Although molecular approaches have enhanced our perception on diversity, it has come to light that the
Effect of flow rate on environmental variables and phytoplankton dynamics: results from field enclosures

Science.gov (United States)

Zhang, Haiping; Chen, Ruihong; Li, Feipeng; Chen, Ling

2015-03-01

To investigate the effects of flow rate on phytoplankton dynamics and related environment variables, a set of enclosure experiments with different flow rates were conducted in an artificial lake. We monitored nutrients, temperature, dissolved oxygen, pH, conductivity, turbidity, chlorophyll- a and phytoplankton levels. The lower biomass in all flowing enclosures showed that flow rate significantly inhibited the growth of phytoplankton. A critical flow rate occurred near 0.06 m/s, which was the lowest relative inhibitory rate. Changes in flow conditions affected algal competition for light, resulting in a dramatic shift in phytoplankton composition, from blue-green algae in still waters to green algae in flowing conditions. These findings indicate that critical flow rate can be useful in developing methods to reduce algal bloom occurrence. However, flow rate significantly enhanced the inter-relationships among environmental variables, in particular by inducing higher water turbidity and vegetative reproduction of periphyton ( Spirogyra). These changes were accompanied by a decrease in underwater light intensity, which consequently inhibited the photosynthetic intensity of phytoplankton. These results warn that a universal critical flow rate might not exist, because the effect of flow rate on phytoplankton is interlinked with many other environmental variables.
From intermittent to persistent cyanobacterial blooms: identifying the main drivers in an urban tropical reservoir

Directory of Open Access Journals (Sweden)

Cleber C. Figueredo

2016-04-01

Full Text Available Eutrophication has impacted water bodies around the world. Knowledge on how to manage and restore these systems is urgently needed in order to maintain adequate water quality. However, causes and consequences of eutrophication may differ among lakes located in tropical and temperate regions. The eutrophication process is better understood for temperate lakes due to the availability of a larger number of studies and longer time-series of data sets. In tropical regions, long-term studies are rare, but could exemplify the particularities of eutrophication speed under conditions of higher temperatures. The purpose of this work was to analyze the evolution of the eutrophication process in an urban tropical reservoir, using a 15-year time series (with occasional interruptions. The dataset comprised monthly sampling of several environmental variables and the phytoplankton community. We found a continuous process of water quality deterioration, mainly related to increasing levels of nutrient and phytoplankton biomass, as well as decreasing water transparency, even after the installation of a municipal wastewater treatment plant. The ongoing eutrophication resulted in a steep trend of increasing cyanobacteria biomass that turned from a seasonal appearance into more persistent blooms in the most recent decades, while the relative contribution of other algal phyla to total phytoplankton biomass declined, which resulted in a loss of phytoplankton diversity. Phosphorus was the major determinant of the persistent blooms. Even though nitrogen concentrations were very high in this system, they were not significantly correlated with phytoplankton or cyanobacteria biomass. Total-P concentrations increased about three times during the study period, indicating that the reservoir did not respond to recent restoration efforts. The average water temperature, always sufficiently high to allow phytoplankton growth all year round, is an additional factor that makes
Sensitivity of Ocean Reflectance Inversion Models for Identifying and Discriminating Between Phytoplankton Functional Groups

Science.gov (United States)

Werdell, P. Jeremy; Ooesler, Collin S.

2012-01-01

The daily, synoptic images provided by satellite ocean color instruments provide viable data streams for observing changes in the biogeochemistrY of marine ecosystems. Ocean reflectance inversion models (ORMs) provide a common mechanism for inverting the "color" of the water observed a satellite into marine inherent optical properties (lOPs) through a combination of empiricism and radiative transfer theory. lOPs, namely the spectral absorption and scattering characteristics of ocean water and its dissolved and particulate constituents, describe the contents of the upper ocean, information critical for furthering scientific understanding of biogeochemical oceanic processes. Many recent studies inferred marine particle sizes and discriminated between phytoplankton functional groups using remotely-sensed lOPs. While all demonstrated the viability of their approaches, few described the vertical distributions of the water column constituents under consideration and, thus, failed to report the biophysical conditions under which their model performed (e.g., the depth and thickness of the phytoplankton bloom(s)). We developed an ORM to remotely identifY Noctiluca miliaris and other phytoplankton functional types using satellite ocean color data records collected in the northern Arabian Sea. Here, we present results from analyses designed to evaluate the applicability and sensitivity of the ORM to varied biophysical conditions. Specifically, we: (1) synthesized a series of vertical profiles of spectral inherent optical properties that represent a wide variety of bio-optical conditions for the northern Arabian Sea under aN Miliaris bloom; (2) generated spectral remote-sensing reflectances from these profiles using Hydrolight; and, (3) applied the ORM to the synthesized reflectances to estimate the relative concentrations of diatoms and N Miliaris for each example. By comparing the estimates from the inversion model to those from synthesized vertical profiles, we were able to

Succession of phytoplankton assemblages in response to large-scale reservoir operation: a case study in a tributary of the Three Gorges Reservoir, China.

Science.gov (United States)

Xiao, Yan; Li, Zhe; Guo, Jinsong; Fang, Fang; Smith, Val H

2016-03-01

The Three Gorges Dam (TGD) has greatly altered ecological and environmental conditions within the reservoir region, but it is not known how these changes affect phytoplankton structure and dynamics. Here, a bimonthly monitoring program was implemented from 2007 to 2009 to study the impact of damming on phytoplankton assemblages in the backwater area of the Pengxi River (PBA). By application of the phytoplankton functional group (C strategists, competitive species; S strategists, stress-tolerant species; R strategists, rapid propagation species), seasonal changes in phytoplankton relative to environmental variations were evaluated using ordination analysis. Seasonal patterns of phytoplankton dynamics were detected during this study, with CS/S strategists causing algal blooms from mid-spring to early summer, CS/CR strategists often observed during flood season, and CS strategists dominant during mid-autumn. CR/R groups dominated during winter and caused algal blooms in February. Our results indicated that phytoplankton assemblages were directly related to reservoir operation effects. Generally, the TGD had a low water level during flood season, resulting in a relatively short hydraulic retention time and intensive variability, which supported the cooccurrence of CS and CR species. During the winter drought season, water storage in the TGD increased the water level and the hydraulic retention time in the PBA, enabling R/CR strategists to overcome the sedimentation effect and to out-compete S/CS species in winter. As expected, these diversity patterns were significantly correlated with the hydraulic retention time and nutrient limitation pattern in the PBA. This study provides strategic insight for evaluating the impacts of reservoir operations on phytoplankton adaptation.
Which offers more scope to suppress river phytoplankton blooms: reducing nutrient pollution or riparian shading?

Science.gov (United States)

Hutchins, M G; Johnson, A C; Deflandre-Vlandas, A; Comber, S; Posen, P; Boorman, D

2010-10-01

River flow and quality data, including chlorophyll-a as a surrogate for river phytoplankton biomass, were collated for the River Ouse catchment in NE England, which according to established criteria is a largely unpolluted network. Against these data, a daily river quality model (QUESTOR) was setup and successfully tested. Following a review, a river quality classification scheme based on phytoplankton biomass was proposed. Based on climate change predictions the model indicated that a shift from present day oligotrophic/mesotrophic conditions to a mesotrophic/eutrophic system could occur by 2080. Management options were evaluated to mitigate against this predicted decline in quality. Reducing nutrient pollution was found to be less effective at suppressing phytoplankton growth than the less costly option of establishing riparian shading. In the Swale tributary, ongoing efforts to reduce phosphorus loads in sewage treatment works will only reduce peak (95th percentile) phytoplankton by 11%, whereas a reduction of 44% is possible if riparian tree cover is also implemented. Likewise, in the Ure, whilst reducing nitrate loads by curtailing agriculture in the headwaters may bring about a 10% reduction, riparian shading would instead reduce levels by 47%. Such modelling studies are somewhat limited by insufficient field data but offer a potentially very valuable tool to assess the most cost-effective methods of tackling effects of eutrophication. Copyright 2010 Elsevier B.V. All rights reserved.
Ocean acidification impacts bacteria-phytoplankton coupling at low-nutrient conditions

Science.gov (United States)

Hornick, Thomas; Bach, Lennart T.; Crawfurd, Katharine J.; Spilling, Kristian; Achterberg, Eric P.; Woodhouse, Jason N.; Schulz, Kai G.; Brussaard, Corina P. D.; Riebesell, Ulf; Grossart, Hans-Peter

2017-01-01

The oceans absorb about a quarter of the annually produced anthropogenic atmospheric carbon dioxide (CO2), resulting in a decrease in surface water pH, a process termed ocean acidification (OA). Surprisingly little is known about how OA affects the physiology of heterotrophic bacteria or the coupling of heterotrophic bacteria to phytoplankton when nutrients are limited. Previous experiments were, for the most part, undertaken during productive phases or following nutrient additions designed to stimulate algal blooms. Therefore, we performed an in situ large-volume mesocosm ( ˜ 55 m3) experiment in the Baltic Sea by simulating different fugacities of CO2 (fCO2) extending from present to future conditions. The study was conducted in July-August after the nominal spring bloom, in order to maintain low-nutrient conditions throughout the experiment. This resulted in phytoplankton communities dominated by small-sized functional groups (picophytoplankton). There was no consistent fCO2-induced effect on bacterial protein production (BPP), cell-specific BPP (csBPP) or biovolumes (BVs) of either free-living (FL) or particle-associated (PA) heterotrophic bacteria, when considered as individual components (univariate analyses). Permutational Multivariate Analysis of Variance (PERMANOVA) revealed a significant effect of the fCO2 treatment on entire assemblages of dissolved and particulate nutrients, metabolic parameters and the bacteria-phytoplankton community. However, distance-based linear modelling only identified fCO2 as a factor explaining the variability observed amongst the microbial community composition, but not for explaining variability within the metabolic parameters. This suggests that fCO2 impacts on microbial metabolic parameters occurred indirectly through varying physicochemical parameters and microbial species composition. Cluster analyses examining the co-occurrence of different functional groups of bacteria and phytoplankton further revealed a separation of
The history of cyanobacterial blooms in the Baltic Sea.

Science.gov (United States)

Finni, T; Kononen, K; Olsonen, R; Wallström, K

2001-08-01

Long-term information on possible changes in cyanobacterial blooms in the Baltic Sea, formed mainly by Nodularia spumigena and Aphanizomenon sp., was sought in published records in historical (years 1887-1938) and modern (years 1974-1998) phytoplankton data sets. Old and new sampling methods and fixatives were tested to improve the comparison of data that had been collected and analyzed in different ways. A hundred years ago, plankton was mainly of interest as a source of fish food; eutrophication problems were only locally reported from the coast, mainly in southern haffs and the receiving waters of larger cities. There were few recordings of open-sea blooms before World War II. Abundances of Nodularia spumigena and Aphanizomenon sp. were low in the old material, and 137 summer samples from 1887-1938 showed no peak abundance. High abundances are common in the new material, and the range of the numbers of both taxa has increased markedly relative to the old material. Since the 1960s, cyanobacterial blooms have been common in the open sea in both the Baltic proper and the Gulf of Finland, indicating high availability of nutrients.
Peculiarities of the Woody Plants Re-Bloom

Directory of Open Access Journals (Sweden)

Opalko Olga Anatolievna

2015-09-01

Full Text Available The data of literary sources concerning the bloom of angiosperm plants and deviation in the development of a flower and inflorescence, in particular untimely flowering, was generalized; our observation results of some peculiarities of re-bloom of woody plants in the National Dendrological Park “Sofiyivka” of NAS of Ukraine (NDP “Sofiyivka” were discussed. The flowering process was formed during a long-term evolution of a propagation system of angiosperm plants as a basis of fertilization and further fruit and seed development. As a result of vernalization and photoperiodism reactions, flowering (under regular conditions occurs in the most favorable period for pollination and fertilization of every plant. However, various deviations, in particular, the untimely (most frequently double, sometimes three- and four-fold flowering occurs in this perfect process of generative organ formation of angiosperm plants. An increased number of reports about re-bloom (at the end of summer – at the beginning of fall of the representatives of various woody plant species whose flowers usually blossom in May-June prompts the analysis of the available information concerning the mechanisms of flowering and the causes which lead to deviation of flowering processes. Flowering of the woody plant representatives of the collection fund of the NDP “Sofiyivka” was studied; statistics about re-bloom in different cities of Ukraine were monitored. The classification of re-bloom facts was carried out according to V.L. Vitkovskiy (1984. Although this classification has mostly a stated nature, it was good enough when being formulated and, with certain conditions, it can be applied nowadays. Accordingly, using this classification, abnormal cases can include facts of early summer-fall flowering and early winter flowering. A late spring flowering can be adaptive response of damaged plants to exogenous stresses, due to which the probability of sexual propagation remains
Inter- and intra-specific diurnal habitat selection of zooplankton during the spring bloom observed by Video Plankton Recorder

DEFF Research Database (Denmark)

Sainmont, Julie; Gislason, Astthor; Heuschele, Jan

2014-01-01

Recorder (VPR), a tool that allows mapping of vertical zooplankton distributions with a far greater spatial resolution than conventional zooplankton nets. The study took place over a full day–night cycle in Disko Bay, Greenland, during the peak of the phytoplankton spring bloom. The sampling revealed...
Heterogeneous distribution of plankton within the mixed layer and its implications for bloom formation in tropical seas

KAUST Repository

Calbet, Albert; Agersted, Mette Dalgaard; Kaartvedt, Stein; Mø hl, Malene; Mø ller, Eva Friis; Enghoff-Poulsen, Sø ren; Paulsen, Maria Lund; Solberg, Ingrid; Tang, Kam W.; Tonnesson, Kajsa; Raitsos, Dionysios E.; Nielsen, Torkel Gissel

2015-01-01

Intensive sampling at the coastal waters of the central Red Sea during a period of thermal stratification, prior to the main seasonal bloom during winter, showed that vertical patches of prokaryotes and microplankton developed and persisted for several days within the apparently density uniform upper layer. These vertical structures were most likely the result of in situ growth and mortality (e.g., grazing) rather than physical or behavioural aggregation. Simulating a mixing event by adding nutrient-rich deep water abruptly triggered dense phytoplankton blooms in the nutrient-poor environment of the upper layer. These findings suggest that vertical structures within the mixed layer provide critical seeding stocks that can rapidly exploit nutrient influx during mixing, leading to winter bloom formation.
Heterogeneous distribution of plankton within the mixed layer and its implications for bloom formation in tropical seas

KAUST Repository

Calbet, Albert

2015-06-11

Intensive sampling at the coastal waters of the central Red Sea during a period of thermal stratification, prior to the main seasonal bloom during winter, showed that vertical patches of prokaryotes and microplankton developed and persisted for several days within the apparently density uniform upper layer. These vertical structures were most likely the result of in situ growth and mortality (e.g., grazing) rather than physical or behavioural aggregation. Simulating a mixing event by adding nutrient-rich deep water abruptly triggered dense phytoplankton blooms in the nutrient-poor environment of the upper layer. These findings suggest that vertical structures within the mixed layer provide critical seeding stocks that can rapidly exploit nutrient influx during mixing, leading to winter bloom formation.
Heterogeneous distribution of plankton within the mixed layer and its implications for bloom formation in tropical seas

DEFF Research Database (Denmark)

Calbet, Albert; Agersted, Mette Dalgaard; Kaartvedt, Stein

2015-01-01

Intensive sampling at the coastal waters of the central Red Sea during a period of thermal stratification, prior to the main seasonal bloom during winter, showed that vertical patches of prokaryotes and microplankton developed and persisted for several days within the apparently density uniform...... upper layer. These vertical structures were most likely the result of in situ growth and mortality (e.g., grazing) rather than physical or behavioural aggregation. Simulating a mixing event by adding nutrient-rich deep water abruptly triggered dense phytoplankton blooms in the nutrient-poor environment...... of the upper layer. These findings suggest that vertical structures within the mixed layer provide critical seeding stocks that can rapidly exploit nutrient influx during mixing, leading to winter bloom formation...
Swarming of pelagic tunicates associated with phytoplankton bloom in the Bay of Bengal

Digital Repository Service at National Institute of Oceanography (India)

Madhupratap, M.; Devassy, V.P.; Nair, S.R.S.; Rao, T.S.S.

During the 40th cruise of R V Gaveshani, a large swarm pelagic tunicates associated with a bloom of diatoms and blue green algae was observed off Nagapattinam. The doliolid Dolioletta gegenbauri, Uljanin, the salp Thalia democratica Forskal...
Qualitative importance of the microbial loop and plankton community structure in a eutropic lake during a bloom of Cyanobacteria

DEFF Research Database (Denmark)

Christoffersen, K.

1990-01-01

Plankton community structure and m~or pools and fluxes of carbon were observed before and after culmination of a bloom of cyanobacteria in eutrophic Frederiksborg Slotsso, Denmark. Biomass changes of heterotrophic nanoflagellates, ciliates, microzooplankton (50 to 140 urn), and macrozooplankton...... smaller than 20 um replaced Aphanizornenon after the culmination of cyanobacteria. Bacterial net production peaked shortly after the culmination of the bloom (510 ug C liter- 1 d-') and decreased thereafter to a level of approximately 124 gg C liter-' d -~. Phytoplankton extracellular release of organic...
Importance of a winter dinoflagellate-microflagellate bloom in the Patuxent River estuary

Science.gov (United States)

Sellner, K. G.; Lacouture, R. V.; Cibik, S. J.; Brindley, A.; Brownlee, S. G.

1991-01-01

A dense bloom of Katodinium rotundatum was observed in the Patuxent River estuary from December to February 1989. The dinoflagellate dominated phytoplankton densities reaching 10 8 cells l -1 and contributed up to 1900 μgC l -1 in near-surface depths. The bloom maintained a distinct patch extending over 10-25 km of the estuary or approximately one-third to one-half of the total estuary (salinities from 5-13 ppt) and was restricted to regions immediately upriver of the transition between the shallow upriver (3-4 m) and deeper lower estuary (10 m). Daily measurements collected in the primary bloom area at the same time each day in the study area indicated 80- and 120-fold variations in chlorophyll and cell densities from day to day. Densities of potential grazers in the region were high with rotifers, primarily Synchaeta baltica, reaching densities of 1000 l -1 in early winter, and the copepod Eurytemora affinis reaching levels exceeding 1·15 × 10 5 m -3 in February. Estimates of grazing pressure by these planktonic herbivores indicated substantial grazing losses for the bloom, with up to 67% of bloom biomass consumed day -1 in February. Nutrient concentrations and ratios of N/P during the bloom suggested potentially N-limited conditions; bloom demise was coincident with a shift to high N/P ratios and high river flows. These data as well as other historical data suggest that dinoflagellate blooms in the lower Patuxent River estuary could be the primary source of carbon to the system during the winter and supply a large reservoir of labile organic matter to planktonic secondary producers prior to annual spring diatom blooms in the region.
Presence of microcystin during events of algal blooms in Araruama Lagoon

Directory of Open Access Journals (Sweden)

Manildo Marcião de Oliveira

2012-04-01

Full Text Available Algal blooms are phenomena produced by anthropogenic activities, despite the possible natural causes. In Araruama Lagoon, blooms occurred in 2005 and in subsequent years, causing profound changes in phytoplankton communities. These episodes triggered events of extensive fish mortality associated with low levels of dissolved oxygen. Another adverse effect associated with blooms is the production of harmful toxins such as phycotoxins produced by eukaryotic microalgae and cyanotoxins produced by cyanobacteria. Samples of fish (mullet and menhaden and seston showed levels of microcystin by enzyme-linked immunosorbent assay (ELISA, also a seston sample (São Pedro d'Aldeia on 08/22/2007, in a period not related to fish mortality, showed cells which contained genes encoding microcystin synthetase, an enzyme responsible for the synthesis of microcystin. The succession of microalgae with the concomitant presence of potentially toxic cyanobacteria draws attention to the risk of chronic exposure by the population that uses fish as their main protein source.
Changes in phytoplankton composition in response to tides, wind-induced mixing conditions, and freshwater outflows in an urbanised estuarine complex.

Science.gov (United States)

Moser, G A O; Ciotti, A M; Giannini, M F C; Tonini, R T; Harari, J

2012-02-01

Recent reports have shown an increase in potentially harmful phytoplankton in Santos bay (Southeastern Brazilian Coast), located in a highly urbanised estuarine complex. Prediction of blooms is, thus, essential but the phytoplankton community structure in very dynamic regions is difficult to determine. In the present work, we discriminate bloom forming microphytoplankton dominance and their relationship to physical and meteorological variables to look for patterns observed in different tides and seasons. Comparing 8 distinct situations, we found five scenarios of dominance that could be related to winds, tides and rainfall: i) Surfers, diatoms occurring during high surf zone energies; ii) Sinkers, represented by larger celled diatoms during spring tide, after periods of high precipitation rates; iii) Opportunistic mixers, composed of chain forming diatoms with small or elongate cells occurring during neap tides; iv) Local mixers, microplanktonic diatoms and dinoflagellates which occurred throughout the 298 sampling stations; and v) Mixotrophic dinoflagellates, after intense estuarine discharges. Results suggest alterations in the temporal patterns for some bloom-forming species, while others appeared in abundances above safe limits for public health. This approach can also illustrate possible impacts of changes in freshwater discharge in highly urbanised estuaries.
Effects of nutrients, temperature and their interactions on spring phytoplankton community succession in Lake Taihu, China.

Directory of Open Access Journals (Sweden)

Jianming Deng

Full Text Available We examined the potential effects of environmental variables, and their interaction, on phytoplankton community succession in spring using long-term data from 1992 to 2012 in Lake Taihu, China. Laboratory experiments were additionally performed to test the sensitivity of the phytoplankton community to nutrient concentrations and temperature. A phytoplankton community structure analysis from 1992 to 2012 showed that Cryptomonas (Cryptophyta was the dominant genus in spring during the early 1990s. Dominance then shifted to Ulothrix (Chlorophyta in 1996 and 1997. However, Cryptomonas again dominated in 1999, 2000, and 2002, with Ulothrix regaining dominance from 2003 to 2006. The bloom-forming cyanobacterial genus Microcystis dominated in 1995, 2001 and 2007-2012. The results of ordinations indicated that the nutrient concentration (as indicated by the trophic state index was the most important factor affecting phytoplankton community succession during the past two decades. In the laboratory experiments, shifts in dominance among phytoplankton taxa occurred in all nutrient addition treatments. Results of both long term monitoring and experiment indicated that nutrients exert a stronger control than water temperature on phytoplankton communities during spring. Interactive effect of nutrients and water temperature was the next principal factor. Overall, phytoplankton community composition was mediated by nutrients concentrations, but this effect was strongly enhanced by elevated water temperatures.
Fungal parasitism: life cycle, dynamics and impact on cyanobacterial blooms.

Directory of Open Access Journals (Sweden)

Mélanie Gerphagnon

Full Text Available Many species of phytoplankton are susceptible to parasitism by fungi from the phylum Chytridiomycota (i.e. chytrids. However, few studies have reported the effects of fungal parasites on filamentous cyanobacterial blooms. To investigate the missing components of bloom ecosystems, we examined an entire field bloom of the cyanobacterium Anabaena macrospora for evidence of chytrid infection in a productive freshwater lake, using a high resolution sampling strategy. A. macrospora was infected by two species of the genus Rhizosiphon which have similar life cycles but differed in their infective regimes depending on the cellular niches offered by their host. R. crassum infected both vegetative cells and akinetes while R. akinetum infected only akinetes. A tentative reconstruction of the developmental stages suggested that the life cycle of R. crassum was completed in about 3 days. The infection affected 6% of total cells (and 4% of akinètes, spread over a maximum of 17% of the filaments of cyanobacteria, in which 60% of the cells could be parasitized. Furthermore, chytrids may reduce the length of filaments of Anabaena macrospora significantly by "mechanistic fragmentation" following infection. All these results suggest that chytrid parasitism is one of the driving factors involved in the decline of a cyanobacteria blooms, by direct mortality of parasitized cells and indirectly by the mechanistic fragmentation, which could weaken the resistance of A. macrospora to grazing.
Development of Phaeocystis globosa blooms in the upwelling waters of the South Central coast of Viet Nam

Science.gov (United States)

Hai, Doan-Nhu; Lam, Nguyen-Ngoc; Dippner, Joachim W.

2010-11-01

Blooms of haptophyte algae in the south central coastal waters of Viet Nam often occur in association with upwelling phenomenon during the southwest (SW) monsoon. Depending on the magnitude of the blooms, damage to aquaculture farms may occur. Based on two years of data on biology, oceanography, and marine chemistry, the present study suggests a conceptual model of the growth of the haptophyte Phaeocystis globosa. At the beginning of the bloom, low temperature and abundant nutrient supply, especially nitrate from rain and upwelling, favour bloom development. Diatoms utilize available nitrate and phosphate; subsequently, higher ammonium concentration allows P. globosa to grow faster than the diatoms. At the end of the Phaeocystis bloom, free cells may become available as food for a heterotrophic dinoflagellate species, Noctiluca scintillans. During and after the phytoplankton bloom, remineralization by bacteria reduces dissolved oxygen to a very low concentration at depth, and favors growth of nitrate-reducing bacteria.A Lagrangian Harmful Algal Bloom (HAB) model, driven by a circulation model of the area, realistically simulates the transport of microalgae in surface waters during strong and weak SW monsoon periods, suggesting that it may be a good tool for early warning of HABs in Vietnamese coastal waters.
Allelopathic and Bloom-Forming Picocyanobacteria in a Changing World

Directory of Open Access Journals (Sweden)

Sylwia Śliwińska-Wilczewska

2018-01-01

Full Text Available Picocyanobacteria are extremely important organisms in the world’s oceans and freshwater ecosystems. They play an essential role in primary production and their domination in phytoplankton biomass is common in both oligotrophic and eutrophic waters. Their role is expected to become even more relevant with the effect of climate change. However, this group of photoautotrophic organisms still remains insufficiently recognized. Only a few works have focused in detail on the occurrence of massive blooms of picocyanobacteria, their toxicity and allelopathic activity. Filling the gap in our knowledge about the mechanisms involved in the proliferation of these organisms could provide a better understanding of aquatic environments. In this review, we gathered and described recent information about allelopathic activity of picocyanobacteria and occurrence of their massive blooms in many aquatic ecosystems. We also examined the relationships between climate change and representative picocyanobacterial genera from freshwater, brackish and marine ecosystems. This work emphasizes the importance of studying the smallest picoplanktonic fractions of cyanobacteria.
Blooms of phytoplankton along the west coast of India associated with nutrient enrichment and the response of zooplankton

Digital Repository Service at National Institute of Oceanography (India)

Nair, S.R.S.; Devassy, V.P.; Madhupratap, M.

and dinoflagellates are also common Spectacular bloom formations of Trichodesmium is a regular phenomenon during the later part of the NE monsoon season At times, these blooms cover hundreds of kilometres Very often successions of phyto- and zooplankton communities...
Applications of MODIS Fluorescence Line Height Measurements to Monitor Water Quality Trends and Algal Bloom Activity in Coastal and Estuarine Waters

Science.gov (United States)

Fischer, A.; Ryan, J. P.; Moreno-Madriñán, M. J.

2012-12-01

Recent advances in satellite and airborne remote sensing, such as improvements in sensor and algorithm calibrations and atmospheric correction procedures have provided for increased coverage of remote-sensing, ocean color products for coastal regions. In particular, for the Moderate Resolution Imaging Spectrometer (MODIS), calibration updates, improved aerosol retrievals, and new aerosol models have led to improved atmospheric correction algorithms for turbid waters and have improved the retrieval of ocean-color. This has opened the way for studying coastal ocean phenomena and processes at finer spatial scales. Human population growth and changes in coastal management practices have brought about significant changes in the concentrations of organic and inorganic, particulate and dissolved substances entering the coastal ocean. There is increasing concern that these inputs have led to declines in water quality and increases in local concentrations of phytoplankton, which could result in harmful algal blooms. In two case studies we present improved and validated MODIS coastal observations of fluorescence line height (FLH) to: (1) assess trends in water quality for Tampa Bay, Florida; and (2) illustrate seasonal and annual variability of algal bloom activity in Monterey Bay, California, as well as document estuarine/riverine plume induced red tide events. In a comprehensive analysis of long term (2003-2011) in situ monitoring data and imagery from Tampa Bay, we assess the validity of the MODIS FLH product against chlorophyll-a and a suite of water quality parameters taken in a variety of conditions throughout this large, optically complex estuarine system. A systematic analysis of sampling sites throughout the bay illustrates that the correlations between FLH and in situ chlorophyll-a are influenced by water quality parameters of total nitrogen, total phosphorous, turbidity and biological oxygen demand. Sites that correlated well with satellite imagery were in depths

Numerical studies of the influence of food ingestion on phytoplankton and zooplankton biomasses

Directory of Open Access Journals (Sweden)

Lidia Dzierzbicka-G³owacka

2002-03-01

Full Text Available This paper presents the numerical simulations of the influence of food ingestion by a herbivorous copepod on phytoplankton and zooplankton biomasses (PZB in the sea. The numerical studies were carried out using the phytoplankton-zooplankton-nutrient-detritus PhyZooNuDe biological upper layer model. This takes account both of fully developed primary production and regeneration mechanisms and of daily migration of zooplankton. In this model the zooplankton is treated not as a 'biomass' but as organisms having definite patterns of growth, reproduction and mortality. Assuming also that {Zoop} is composed ofi cohorts of copepods with weights Wi and numbers Zi, then {Zoop} = WiZi. The PhyZooNuDe model consists of three coupled, partial second-order differential equations of the diffusion type for phytoplankton, zooplankton and nutrients, and one ordinary first-order differential equation for the benthic detritus pool, together with initial and boundary conditions. The calculations were made during 90 days (April, May and June for the study area P1 (Gdansk Deep in an area 0z<=20 m with a vertical space step of 0.1 m and a time step of 300 s. The simulation given here demonstrated the importance of food ingestion by zooplankton in that it can alter the nature of the interactions of plants and herbivores. The analysis of these numerical studies indicate that the maximal ingestion rate and the half-saturation constant for grazing strongly affect the magnitude of the spring bloom and the cyanobacterial bloom, and also the total zooplankton biomass.
Carbon and nitrogen burial in a plateau lake during eutrophication and phytoplankton blooms.

Science.gov (United States)

Huang, Changchun; Zhang, Linlin; Li, Yunmei; Lin, Chen; Huang, Tao; Zhang, Mingli; Zhu, A-Xing; Yang, Hao; Wang, Xiaolei

2018-03-01

Organic carbon (OC) buried in lake sediment is an important component of the global carbon cycle. The impact of eutrophication on OC burial in lakes should be addressed due to worldwide lake eutrophication. Fourteen 210 Pb- and 137 Cs-dated sediment cores taken in Dianchi Lake (China) in August 2006 (seven cores) and July 2014 (seven cores) were analyzed to evaluate the response of the organic carbon accumulation rate (OCAR) to eutrophication and algal blooms over the past hundred years. The mean value of OCAR before eutrophication occurred in 1979, 16.62±7.53 (mean value±standard deviation), increased to 54.33±27.29gm -2 yr -1 after eutrophication. It further increased to 61.98±28.94gm -2 yr -1 after algal blooms occurred (1989). The accumulation rate of organic nitrogen (ONAR) is coupled with OCAR. The high loss rate of OC and organic nitrogen (ON) leads to a long-term burial efficiency of only 10% and 5% of OC and ON. However, this efficiency can still lead to an increase in OCAR by a factor of 4.55 during algal blooms in Dianchi Lake. Dianchi Lake stored 1.26±0.32 Tg carbon and 0.071±0.018 Tg nitrogen, including 0.94±0.23 Tg OC and 0.32±0.14 Tg inorganic carbon, 0.066±0.018 Tg ON, 0.002±0.001 Tg nitrate nitrogen (NO 3 -N) and 0.003±0.001 Tg ammonium nitrogen (NH 4 -N) between 1900 and 2012. Copyright © 2017 Elsevier B.V. All rights reserved.
Oligotrophication and Metabolic Slowing-Down of a NW Mediterranean Coastal Ecosystem

KAUST Repository

Agusti, Susana; Martinez Ayala, Juan; Regaudie-de-Gioux, Aurore; Duarte, Carlos M.

2017-01-01

temperate area, there were seasonal patterns associated to changes in the broad temperature range (12.0–28.4°C), with a primary phytoplankton bloom in late winter and a secondary one in the fall. Community respiration (R) rates peaked during summers
Cyanobacterial water bloom of Limnoraphis robusta in the Lago Mayor of Lake Titicaca. Can it develop?

Czech Academy of Sciences Publication Activity Database

Komárková, Jaroslava; Montoya, H.; Komárek, J.

2016-01-01

Roč. 764, č. 1 (2016), s. 249-258 ISSN 0018-8158. [Workshop of the International Association for Phytoplankton Taxonomy and Ecology (IAP) /17./. Kastoria, 14.09.2014-21.09.2014] Institutional support: RVO:60077344 Keywords : Titicaca Lake * cyanobacterial water bloom * Limnoraphis robusta * Diazocytes * Atitlán Lake * N:P ratio Subject RIV: DA - Hydrology ; Limnology Impact factor: 2.056, year: 2016
A harmful algal bloom of Karenia brevis in the northeastern Gulf of Mexico as revealed by MODIS and VIIRS: a comparison.

Science.gov (United States)

Hu, Chuanmin; Barnes, Brian B; Qi, Lin; Corcoran, Alina A

2015-01-28

The most recent Visible Infrared Imager Radiometer Suite (VIIRS) is not equipped with a spectral band to detect solar-stimulated phytoplankton fluorescence. The lack of such a band may affect the ability of VIIRS to detect and quantify harmful algal blooms (HABs) in coastal waters rich in colored dissolved organic matter (CDOM) because of the overlap of CDOM and chlorophyll absorption within the blue-green spectrum. A recent HAB dominated by the toxin-producing dinoflagellate Karenia brevis in the northeastern Gulf of Mexico, offshore of Florida's Big Bend region, allowed for comparison of the capacities of VIIRS and Moderate Resolution Imaging Spectroradiometer (MODIS) to detect blooms in CDOM-rich waters. Both VIIRS and MODIS showed general consistency in mapping the CDOM-rich dark water, which measured a maximum area of 8900 km2 by mid-July 2014. However, within the dark water, only MODIS allowed detection of bloom patches-as indicated by high normalized fluorescence line height (nFLH). Field surveys between late July and mid-September confirmed Karenia brevis at bloom abundances up to 20 million cells·L(-1) within these patches. The bloom patches were well captured by the MODIS nFLH images, but not by the default chlorophyll a concentration (Chla) images from either MODIS or VIIRS. Spectral analysis showed that VIIRS could not discriminate these high-phytoplankton water patches within the dark water due to its lack of fluorescence band. Such a deficiency may be overcome with new algorithms or future satellite missions such as the U.S. NASA's Pre-Aerosol-Clouds-Ecology mission and the European Space Agency's Sentinel-3 mission.
Fish Kill Incidents and Harmful Algal Blooms in Omani Waters

Directory of Open Access Journals (Sweden)

Hamed Mohammed Al Gheilani

2011-01-01

Full Text Available Red tide, one of the harmful algal blooms (HABs is a natural ecological phenomenon and often this event is accompanied by severe impacts on coastal resources, local economies, and public health. The occurrence of red tides has become more frequent in Omani waters in recent years. Some of them caused fish kill, damaged fishery resources and mariculture, threatened the marine environment and the osmosis membranes of desalination plants. However, a number of them have been harmless. The most common dinoflagellate Noctiluca scintillans is associated with the red tide events in Omani waters. Toxic species like Karenia selliformis, Prorocentrum arabianum, and Trichodesmium erythraeum have also been reported recently. Although red tides in Oman have been considered a consequence of upwelling in the summer season (May to September, recent phytoplankton outbreaks in Oman are not restricted to summer. Frequent algal blooms have been reported during winter (December to March. HABs may have contributed to hypoxia and/or other negative ecological impacts.
The smell of the sea : Production of dimethylsulphoniopropionate and its conversion into dimethylsulphide by the marine phytoplankton genus Phaeocystis

NARCIS (Netherlands)

Stefels, Jacqueline

1997-01-01

The smell of the sea is caused by the volatile organic sulphur compound dimethylsulphide (DMS). Low concentrations of DMS in the water (low nM range) and the atmosphere can be found in all marine areas. High concentrations (high nM range) often coincide with blooms of specific marine phytoplankton
Competition between a nonallelopathic phytoplankton and an allelopathic phytoplankton species under predation.

Science.gov (United States)

Kengwoung-Keumo, Jean-Jacques

2016-08-01

We propose a model of two-species competition in the chemostat for a single growth-limiting, nonreproducing resource that extends that of Roy [38]. The response functions are specified to be Michaelis-Menten, and there is no predation in Roy's work. Our model generalizes Roy's model to general uptake functions. The competition is exploitative so that species compete by decreasing the common pool of resources. The model also allows allelopathic effects of one toxin-producing species, both on itself (autotoxicity) and on its nontoxic competitor (phytotoxicity). We show that a stable coexistence equilibrium exists as long as (a) there are allelopathic effects and (b) the input nutrient concentration is above a critical value. The model is reconsidered under instantaneous nutrient recycling. We further extend this work to include a zooplankton species as a fourth interacting component to study the impact of predation on the ecosystem. The zooplankton species is allowed to feed only on the two phytoplankton species which are its perfectly substitutable resources. Each of the models is analyzed for boundedness, equilibria, stability, and uniform persistence (or permanence). Each model structure fits very well with some harmful algal bloom observations where the phytoplankton assemblage can be envisioned in two compartments, toxin producing and non-toxic. The Prymnesium parvum literature, where the suppressing effects of allelochemicals are quite pronounced, is a classic example. This work advances knowledge in an area of research becoming ever more important, which is understanding the functioning of allelopathy in food webs.
Occurrence of toxin-producing cyanobacteria blooms in a Brazilian semiarid reservoir

Directory of Open Access Journals (Sweden)

I. A. S. Costa

Full Text Available We report the occurrence of cyanobacterial blooms and the presence of cyanotoxins in water samples from the Armando Ribeiro Gonçalves reservoir (06° 08’ S and 37° 07’ W, located in the state of Rio Grande do Norte, in the semiarid region of northeastern Brazil. The cyanobacterial species were identified and quantified during the rainy and dry seasons in the year 2000. Cyanotoxins such as microcystins, saxitoxins and cylindrospermopsins were analyzed and quantified using HPLC and ELISA methods. The mixed toxic blooms of Cylindrospermopsis raciborskii, Microcystis spp (M. panniformis, M. protocystis, M. novacekii and Aphanizomenon spp (Aphanizomenon gracile, A. cf. manguinii, A. cf. issastschenkoi were persistent and represented 90-100% of the total phytoplankton species. Toxic cyanobacterial blooms from the Armando Ribeiro Gonçalves reservoir were analyzed and found to have three phases in relation to the annual cycle. During the rainy season, an intense toxic bloom of Cylindrospermopsis raciborskii was recorded along with saxitoxins (3.14 µg.L-1. During the transition period, between the rainy and dry seasons, different species of Microscytis occurred and microcystin as high as 8.8 µg.L-1 was recorded. In the dry season, co-dominance of Cylindrospermopsis raciborskii, Microcystis spp and Aphanizomenon spp occurred and the concentrations of saxitoxin remained very low. Our results indicate the presence of microcystins (8.8 µg.L-1 and saxitoxins (3.14 µg.L-1 into the crude water, with increasing concentrations from the second fortnight of April to late May 2000. The occurrence of toxic blooms in this reservoir points to a permanent risk of cyanotoxins in supply waters, indicating the need for the implementation of bloom control measures to improve the water quality. Exposure of the local population to cyanotoxins through their potential accumulation in fish muscle must also be considered.
Phytoplankton dynamics and periodicity in two cascading warm ...

African Journals Online (AJOL)

In addition to annual patterns, changes in chlorophyll content implied progressive long-term changes in trophic status, especially in Albert Falls, with the emergence of various 'new' taxa (and/or higher peak densities of others). Consideration of phytoplankton dynamics in terms of functional groups offers certain advantages ...
Phytoplankton community structure in local water types at a coastal site in north-western Bay of Bengal.

Science.gov (United States)

Baliarsingh, S K; Srichandan, Suchismita; Lotliker, Aneesh A; Sahu, K C; Srinivasa Kumar, T

2016-07-01

A comprehensive analysis on seasonal distribution of phytoplankton community structure and their interaction with environmental variables was carried out in two local water types (type 1 30 m isobath) at a coastal site in north-western Bay of Bengal. Phytoplankton community was represented by 211 taxa (146 marine, 37 fresh, 2 brackish, 20 marine-fresh, and 6 marine-brackish-fresh) belonging to seven major groups including 45 potential bloom forming and 22 potential toxin producing species. The seasonal variability depicted enrichment of phytoplankton during pre-monsoon in both water types. Total phytoplankton abundance pattern observed with inter-annual shift during monsoon and post-monsoon period at both water types. In both water types, diatom predominance was observed in terms of species richness and abundance comprising of centric (82 sp.) and pennate (58 sp.) forms. Pennate diatoms, Thalassiothrix longissima and Skeletonema costatum preponderated in both the water types. The diatom abundance was higher in type 1 in comparison to type 2. In general, SiO4 found to fuel growth of the dominant phytoplankton group, diatom in both the water types despite comparative lower concentration of other macronutrients in type 2.
Phytoplankton can actively diversify their migration strategy in response to turbulent cues.

Science.gov (United States)

Sengupta, Anupam; Carrara, Francesco; Stocker, Roman

2017-03-23

Marine phytoplankton inhabit a dynamic environment where turbulence, together with nutrient and light availability, shapes species fitness, succession and selection. Many species of phytoplankton are motile and undertake diel vertical migrations to gain access to nutrient-rich deeper layers at night and well-lit surface waters during the day. Disruption of this migratory strategy by turbulence is considered to be an important cause of the succession between motile and non-motile species when conditions turn turbulent. However, this classical view neglects the possibility that motile species may actively respond to turbulent cues to avoid layers of strong turbulence. Here we report that phytoplankton, including raphidophytes and dinoflagellates, can actively diversify their migratory strategy in response to hydrodynamic cues characteristic of overturning by Kolmogorov-scale eddies. Upon experiencing repeated overturning with timescales and statistics representative of ocean turbulence, an upward-swimming population rapidly (5-60 min) splits into two subpopulations, one swimming upward and one swimming downward. Quantitative morphological analysis of the harmful-algal-bloom-forming raphidophyte Heterosigma akashiwo together with a model of cell mechanics revealed that this behaviour was accompanied by a modulation of the cells' fore-aft asymmetry. The minute magnitude of the required modulation, sufficient to invert the preferential swimming direction of the cells, highlights the advanced level of control that phytoplankton can exert on their migratory behaviour. Together with observations of enhanced cellular stress after overturning and the typically deleterious effects of strong turbulence on motile phytoplankton, these results point to an active adaptation of H. akashiwo to increase the chance of evading turbulent layers by diversifying the direction of migration within the population, in a manner suggestive of evolutionary bet-hedging. This migratory behaviour
Effect of monsoonal perturbations on the occurrence of phytoplankton blooms in a tropical bay

Digital Repository Service at National Institute of Oceanography (India)

Patil, J.S.; Anil, A.C.

. Bloom duration of 1-6 d was recorded, indicating that such events are widespread and can significantly influence the system’s metabolic balance. The average net photic zone production of the season was positive (0.11 ± 0.67 g O₂ m^-2
Contrasting Patterns of Phytoplankton Assemblages in Two Coastal Ecosystems in Relation to Environmental Factors (Corsica, NW Mediterranean Sea

Directory of Open Access Journals (Sweden)

Marie Garrido

2014-04-01

Full Text Available Corsica Island is a sub-basin of the Northwestern Mediterranean Sea, with hydrological features typical of both oligotrophic systems and eutrophic coastal zones. Phytoplankton assemblages in two coastal ecosystems of Corsica (the deep Bay of Calvi and the shallow littoral of Bastia show contrasting patterns over a one-year cycle. In order to determine what drives these variations, seasonal changes in littoral phytoplankton are considered together with environmental parameters. Our methodology combined a survey of the physico-chemical structure of the subsurface water with a characterization of the phytoplankton community structure. Sampling provided a detailed record of the seasonal changes and successions that occur in these two areas. Results showed that the two sampled stations presented different phytoplankton abundance and distribution patterns, notably during the winter–spring bloom period. Successions in pico-, nano-, and microphytoplankton communities appeared mainly driven by differences in the ability to acquire nutrients, and in community-specific growth rates. Phytoplankton structure and dynamics are discussed in relation to available data on the Northwestern Mediterranean Sea. These results confirm that integrated monitoring of coastal areas is a requisite for gaining a proper understanding of marine ecosystems.
Effects of increased zooplankton biomass on phytoplankton and cyanotoxins: A tropical mesocosm study.

Science.gov (United States)

Dos Santos Severiano, Juliana; Dos Santos Almeida-Melo, Viviane Lúcia; Bittencourt-Oliveira, Maria do Carmo; Chia, Mathias Ahii; do Nascimento Moura, Ariadne

2018-01-01

Zooplankton are important biocontrol agents for algal blooms in temperate lakes, while their potential in tropical and subtropical environments is not well understood. The aim of the present study was to evaluate the influence of increased zooplankton biomass on phytoplankton community and cyanotoxins (microcystins and saxitoxin) content of a tropical reservoir (Ipojuca reservoir, Brazil) using in situ mesocosms. Mesocosms consisted of 50L transparent polyethylene bags suspended in the reservoir for twelve days. Phytoplankton populations were exposed to treatments having 1 (control), 2, 3 and 4 times the biomass of zooplankton found in the reservoir at the beginning of the experiment. Filamentous cyanobacteria such as Planktothrix agardhii and Cylindrospermopsis raciborskii were not negatively influenced by increasing zooplankton biomass. In contrast, the treatments with 3 and 4 times zooplankton biomass negatively affected the cyanobacteria Aphanocapsa sp., Chroococcus sp., Dolichospermum sp., Merismopedia tenuissima, Microcystis aeruginosa and Pseudanabaena sp.; the diatom Cyclotella meneghiniana; and the cryptophyte Cryptomonas sp. Total microcystin concentration both increased and decreased at different times depending on zooplankton treatment, while saxitoxin level was not significantly different between the treatments and control. The results of the present study suggest that zooplankton biomass can be manipulated to control the excessive proliferation of non-filamentous bloom forming cyanobacteria (e.g. M. aeruginosa) and their associated cyanotoxins. Copyright © 2017 Elsevier B.V. All rights reserved.
Mitigating Harmful Cyanobacterial Blooms in a Human- and Climatically-Impacted World

Directory of Open Access Journals (Sweden)

Hans W. Paerl

2014-12-01

Full Text Available Bloom-forming harmful cyanobacteria (CyanoHABs are harmful from environmental, ecological and human health perspectives by outcompeting beneficial phytoplankton, creating low oxygen conditions (hypoxia, anoxia, and by producing cyanotoxins. Cyanobacterial genera exhibit optimal growth rates and bloom potentials at relatively high water temperatures; hence, global warming plays a key role in their expansion and persistence. CyanoHABs are regulated by synergistic effects of nutrient (nitrogen:N and phosphorus:P supplies, light, temperature, vertical stratification, water residence times, and biotic interactions. In most instances, nutrient control strategies should focus on reducing both N and P inputs. Strategies based on physical, chemical (nutrient and biological manipulations can be effective in reducing CyanoHABs; however, these strategies are largely confined to relatively small systems, and some are prone to ecological and environmental drawbacks, including enhancing release of cyanotoxins, disruption of planktonic and benthic communities and fisheries habitat. All strategies should consider and be adaptive to climatic variability and change in order to be effective for long-term control of CyanoHABs. Rising temperatures and greater hydrologic variability will increase growth rates and alter critical nutrient thresholds for CyanoHAB development; thus, nutrient reductions for bloom control may need to be more aggressively pursued in response to climatic changes globally.
Phytoplankton of the North Sea and its dynamics: A review

Science.gov (United States)

Reid, P. C.; Lancelot, C.; Gieskes, W. W. C.; Hagmeier, E.; Weichart, G.

Phytoplankton is the major contributor to algal biomass and primary production of the North Sea, although crops of macroalgae can locally be up to 2000 g C.m -2 along the coast of the U.K. and Norway, and microphytobenthos dominates production in the shallow tidal flat areas bordering the coasts of England, the Netherlands, Germany and Denmark. Data collected since 1932 during the Continuous Plankton Recorder Survey show consistent patterns of geographical, seasonal and annual variation in the distribution of phytoplankton and its major taxonomic components. There is a trend of increased colouration in Recorder silks in the southern North Sea until approximately 1975 since when Colour levels (assumed to be indicative of algal biomass) have declined. In the eutrophic Dutch Wadden Sea the algal crop continued to increase; in Dutch coastal North Sea waters a trend of biomass increase reversed since 1984, apparently due to a reduction in Rhine river outflow. Long-term observations made at Helgoland since the 60's also show trends of increasing nutrients and phytoplankton biomass only to 1984. Adverse effects such as deoxygenation, foam formation and toxin production have been linked to mass concentrations of algae known as blooms. There is no evidence from existing reports for an increase in their frequency, although some years stand out with larger numbers. Occurrence of blooms can partly be explained by hydrographic conditions. More than 30 taxa are recognised as occurring in bloom proportions in the North Sea, approximately one third of which can be toxic. The crop of Bacillariophyceae (diatoms) is not likely to increase with eutrophication due to silicate limitation. An extensive subsurface maximum of armoured dinoflagellates, its abundance gouverned by hydrographic conditions, is the most characteristic feature of the central and northern North Sea in the summer months. Abundance, sometimes dominance, of picoplankton and of species that are not readily detected by
In-situ production of humic-like fluorescent dissolved organic matter during Cochlodinium polykrikoides blooms

Science.gov (United States)

Kwon, Hyeong Kyu; Kim, Guebuem; Lim, Weol Ae; Park, Jong Woo

2018-04-01

We investigated phytoplankton pigments, dissolved organic carbon (DOC), and fluorescent dissolved organic matter (FDOM) during the summers of 2013 and 2016 in the coastal area of Tongyeong, Korea, where Cochlodinium polykrikoides blooms often occur. The density of red tides was evaluated using a dinoflagellate pigment, peridinin. The concentrations of peridinin and DOC in the patch areas were 15- and 4-fold higher than those in the non-patch areas. The parallel factor analysis (PARAFAC) model identified one protein-like FDOM (FDOMT) and two humic-like FDOM, classically classified as marine FDOM (FDOMM) and terrestrial FDOM (FDOMC). The concentrations of FDOMT in the patch areas were 5-fold higher than those in the non-patch areas, likely associated with biological production. In general, FDOMM and FDOMC are known to be dependent exclusively on salinity in any surface waters of the coastal ocean. However, in this study, we observed strikingly enhanced FDOMC concentration over that expected from the salinity mixing, whereas FDOMM increases were not clear. These FDOMC concentrations showed a significant positive correlation against peridinin, indicating that the production of FDOMC is associated with the red tide blooms. Our results suggest that FDOMC can be naturally enriched by some phytoplankton species, without FDOMM enrichment. Such naturally produced FDOM may play a critical role in biological production as well as biogeochemical cycle in red tide regions.
The role of phytoplankton in the modulation of dissolved and oyster cadmium concentrations in Deep Bay, British Columbia, Canada

International Nuclear Information System (INIS)

Cassis, David; Lekhi, Priyanka; Pearce, Christopher M.; Ebell, Nadene; Orians, Kristin; Maldonado, Maria T.

2011-01-01

We previously identified dissolved cadmium (Cd diss ) as the main source of this metal in cultured Pacific oysters, Crassostrea gigas, in Deep Bay, British Columbia, Canada (Lekhi et al., 2008). Total suspended particulate Cd (Cd part ) was not found to be a significant source of oyster Cd (Cd oys ), with Cd part > 20 μm negatively correlated with Cd oys concentration. High phytoplankton abundance in spring and summer was hypothesized to reduce Cd oys indirectly by drawing down Cd diss and increasing oyster growth. In the present study we expanded on these results by examining specifically how the phytoplankton community composition modulates both Cd diss and Cd oys concentrations in Deep Bay. Based on calculations of nutrients and Cd diss drawdown, phytoplankton accounted for approximately 90% of the overall summer reduction in Cd diss in the bay. Diatoms were the dominant phytoplankton group, being correlated negatively with Cd oys and positively with Cd part . This suggests that diatom growth mediates the transfer of Cd from the dissolved to the particulate phase, resulting in lower Cd oys . Spring blooms and sporadic harmful algal blooms may mediate a large flux of Cd part to the sediments. Thus, phytoplankton act as a sink, rather than a source, of Cd to oysters in Deep Bay and have a crucial role in the seasonality of Cd oys by reducing the concentration of Cd diss during the summer. Based on environmental variables, two descriptive models for annual Cd oys concentrations were developed using multiple linear regression. The first model (R 2 = 0.870) was created to explain the maximum variability in Cd oys concentrations throughout the year, while the second (R 2 = 0.806) was based on parameters that could be measured easily under farm conditions. Oyster age heavily affected both models, with the first model being secondarily affected by temperature and the second one being more sensitive to changes in salinity. - Highlights: → Phytoplankton and
Microzooplankton grazing and phytoplankton growth in marine mesocosms with increased CO2 levels

Directory of Open Access Journals (Sweden)

Y. Carotenuto

2008-08-01

Full Text Available Microzooplankton grazing and algae growth responses to increasing pCO2 levels (350, 700 and 1050 μatm were investigated in nitrate and phosphate fertilized mesocosms during the PeECE III experiment 2005. Grazing and growth rates were estimated by the dilution technique combined with taxon specific HPLC pigment analysis. Microzooplankton composition was determined by light microscopy. Despite a range of up to 3 times the present CO2 levels, there were no clear differences in any measured parameter between the different CO2 treatments. During days 3–9 of the experiment the algae community standing stock, measured as chlorophyll a (Chl-a, showed the highest instantaneous grow rates (k=0.37–0.99 d−1 and increased from ca. 2–3 to 6–12 μg l−1, in all mesocosms. Afterwards the phytoplankton standing stock decreased in all mesocosms until the end of the experiment. The microzooplankton standing stock, that was mainly constituted by dinoflagellates and ciliates, varied between 23 and 130 μg C l−1 (corresponding to 1.9 and 10.8 μmol C l−1, peaking on day 13–15, apparently responding to the phytoplankton development. Instantaneous Chl-a growth rates were generally higher than the grazing rates, indicating only a limited overall effect of microzooplankton grazing on the most dominant phytoplankton. Diatoms and prymnesiophytes were significantly grazed (12–43% of the standing stock d−1 only in the pre-bloom phase when they were in low numbers, and in the post-bloom phase when they were already affected by low nutrients and/or viral lysis. The cyanobacteria populations appeared more affected by microzooplankton grazing which generally removed 20–65% of the standing stock per day.

Mitigating cyanobacterial harmful algal blooms in aquatic ecosystems impacted by climate change and anthropogenic nutrients.

Science.gov (United States)

Paerl, Hans W; Gardner, Wayne S; Havens, Karl E; Joyner, Alan R; McCarthy, Mark J; Newell, Silvia E; Qin, Boqiang; Scott, J Thad

2016-04-01

Mitigating the global expansion of cyanobacterial harmful blooms (CyanoHABs) is a major challenge facing researchers and resource managers. A variety of traditional (e.g., nutrient load reduction) and experimental (e.g., artificial mixing and flushing, omnivorous fish removal) approaches have been used to reduce bloom occurrences. Managers now face the additional effects of climate change on watershed hydrologic and nutrient loading dynamics, lake and estuary temperature, mixing regime, internal nutrient dynamics, and other factors. Those changes favor CyanoHABs over other phytoplankton and could influence the efficacy of control measures. Virtually all mitigation strategies are influenced by climate changes, which may require setting new nutrient input reduction targets and establishing nutrient-bloom thresholds for impacted waters. Physical-forcing mitigation techniques, such as flushing and artificial mixing, will need adjustments to deal with the ramifications of climate change. Here, we examine the suite of current mitigation strategies and the potential options for adapting and optimizing them in a world facing increasing human population pressure and climate change. Copyright © 2015 Elsevier B.V. All rights reserved.
Oil Spills and Dispersants Can Cause the Initiation of Potentially Harmful Dinoflagellate Blooms ("Red Tides").

Science.gov (United States)

Almeda, Rodrigo; Cosgrove, Sarah; Buskey, Edward J

2018-04-25

After oil spills and dispersant applications the formation of red tides or harmful algal blooms (HABs) has been observed, which can cause additional negative impacts in areas affected by oil spills. However, the link between oil spills and HABs is still unknown. Here, we present experimental evidence that demonstrates a connection between oil spills and HABs. We determined the effects of oil, dispersant-treated oil, and dispersant alone on the structure of natural plankton assemblages in the Northern Gulf of Mexico. In coastal waters, large tintinnids and oligotrich ciliates, major grazers of phytoplankton, were negatively affected by the exposure to oil and dispersant, whereas bloom-forming dinoflagellates ( Prorocentrum texanum, P. triestinum, and Scrippsiella trochoidea) notably increased their concentration. The removal of key grazers due to oil and dispersant disrupts the predator-prey controls ("top-down controls") that normally function in plankton food webs. This disruption of grazing pressure opens a "loophole" that allows certain dinoflagellates with higher tolerance to oil and dispersants than their grazers to grow and form blooms when there are no growth limiting factors (e.g., nutrients). Therefore, oil spills and dispersants can act as disrupters of predator-prey controls in plankton food webs and as indirect inducers of potentially harmful dinoflagellate blooms.
Coastal upwelling linked to toxic Pseudo-nitzschia australis blooms in Los Angeles coastal waters, 2005-2007

KAUST Repository

Schnetzer, Astrid; Jones, Burton; Schaffner, Rebecca A.; Cetinić, Ivona; Fitzpatrick, Elizabeth; Miller, Peter E.; Seubert, Erica L.; Caron, David A.

2013-01-01

Harmful algal blooms dominated by the diatom Pseudo-nitzschia spp. have become a perennial but variable event within surface waters near the greater Los Angeles area. Toxic blooms during spring seasons from 2005 to 2007 varied strongly in their overall toxicity and duration. Differences in bloom dynamics were linked to differences in storm-induced river discharge following episodic rain events and coastal upwelling, both major coastal processes that led to the injection of nutrients into coastal surface waters. Heavy river runoff during early 2005, a record-rainfall year, favored a phytoplankton community mainly comprised of algal taxa other than Pseudo-nitzschia. The spring bloom during 2005 was associated with low domoic acid surface concentrations and minor contributions of (mainly) P. delicatissima to the diatom assemblage. In contrast, highly toxic P. australis-dominated blooms during spring seasons of 2006 and 2007 were linked to strong upwelling events. River discharge quotas in 2006 and 2007, in contrast to 2005, fell well below annual averages for the region. Surface toxin levels were linked to colder, more saline (i.e. upwelled) water over the 3-year study, but no such consistent relationship between domoic acid levels and other physiochemical parameters, such as macronutrient concentrations or nutrient ratios, was observed. © The Author 2013. Published by Oxford University Press. All rights reserved.
Coastal upwelling linked to toxic Pseudo-nitzschia australis blooms in Los Angeles coastal waters, 2005-2007

KAUST Repository

Schnetzer, Astrid

2013-06-10

Harmful algal blooms dominated by the diatom Pseudo-nitzschia spp. have become a perennial but variable event within surface waters near the greater Los Angeles area. Toxic blooms during spring seasons from 2005 to 2007 varied strongly in their overall toxicity and duration. Differences in bloom dynamics were linked to differences in storm-induced river discharge following episodic rain events and coastal upwelling, both major coastal processes that led to the injection of nutrients into coastal surface waters. Heavy river runoff during early 2005, a record-rainfall year, favored a phytoplankton community mainly comprised of algal taxa other than Pseudo-nitzschia. The spring bloom during 2005 was associated with low domoic acid surface concentrations and minor contributions of (mainly) P. delicatissima to the diatom assemblage. In contrast, highly toxic P. australis-dominated blooms during spring seasons of 2006 and 2007 were linked to strong upwelling events. River discharge quotas in 2006 and 2007, in contrast to 2005, fell well below annual averages for the region. Surface toxin levels were linked to colder, more saline (i.e. upwelled) water over the 3-year study, but no such consistent relationship between domoic acid levels and other physiochemical parameters, such as macronutrient concentrations or nutrient ratios, was observed. © The Author 2013. Published by Oxford University Press. All rights reserved.
Multi-sensor satellite and in situ monitoring of phytoplankton development in a eutrophic-mesotrophic lake.

Science.gov (United States)

Dörnhöfer, Katja; Klinger, Philip; Heege, Thomas; Oppelt, Natascha

2018-01-15

Phytoplankton indicated by its photosynthetic pigment chlorophyll-a is an important pointer on lake ecology and a regularly monitored parameter within the European Water Framework Directive. Along with eutrophication and global warming cyanobacteria gain increasing importance concerning human health aspects. Optical remote sensing may support both the monitoring of horizontal distribution of phytoplankton and cyanobacteria at the lake surface and the reduction of spatial uncertainties associated with limited water sample analyses. Temporal and spatial resolution of using only one satellite sensor, however, may constrain its information value. To discuss the advantages of a multi-sensor approach the sensor-independent, physically based model MIP (Modular Inversion and Processing System) was applied at Lake Kummerow, Germany, and lake surface chlorophyll-a was derived from 33 images of five different sensors (MODIS-Terra, MODIS-Aqua, Landsat 8, Landsat 7 and Sentinel-2A). Remotely sensed lake average chlorophyll-a concentration showed a reasonable development and varied between 2.3±0.4 and 35.8±2.0mg·m -3 from July to October 2015. Match-ups between in situ and satellite chlorophyll-a revealed varying performances of Landsat 8 (RMSE: 3.6 and 19.7mg·m -3 ), Landsat 7 (RMSE: 6.2mg·m -3 ), Sentinel-2A (RMSE: 5.1mg·m -3 ) and MODIS (RMSE: 12.8mg·m -3 ), whereas an in situ data uncertainty of 48% needs to be respected. The temporal development of an index on harmful algal blooms corresponded well with the cyanobacteria biomass development during summer months. Satellite chlorophyll-a maps allowed to follow spatial patterns of chlorophyll-a distribution during a phytoplankton bloom event. Wind conditions mainly explained spatial patterns. Integrating satellite chlorophyll-a into trophic state assessment resulted in different trophic classes. Our study endorsed a combined use of satellite and in situ chlorophyll-a data to alleviate weaknesses of both approaches and
Bloom of Gymnodinium catenatum in Bahía Santiago and Bahía Manzanillo, Colima, Mexico

Directory of Open Access Journals (Sweden)

Sonia Quijano-Scheggia

2012-03-01

Full Text Available Gymnodinium bloom events are of concern, since they produce toxins, which have unfavorable consequences to marine ecosystems, human health and the economy. This report describes the physico-chemical conditions that were present during the algal bloom event on May 2010 in Bahía Manzanillo and Bahía Santiago, Colima, Mexico. For this, seawater nutrient analysis, phytoplankton counts, identification, and toxicity tests were undertaken. Nutrients in seawater were determined using colorimetric techniques, the higher concentrations (8.88μM DIN, 0.78μM PO4 and 24.34μM SiO2 were related with upwelling waters that promoted the algal bloom that began after registering the year lowest sea-surface temperature, favoring the rapid growth of G. catenatum (up to 1.02 x10(7cells/L. Phytoplankton counting was carried out using sedimentation chambers and cells enumerated on appropriated area. The bloom persisted in the bays for approximately two weeks and was associated with toxicity (determined with HPLC in local oysters (1525.8μg STXeq/100g, and in phytoplankton (10.9pg STXeq/cells samples. Strong variations in cell toxicity (1.4 to 10.9pg STXeq/cells, most likely reflected the availability of inorganic nutrients. The toxin profile of the phytoplankton samples consisted of 11 toxins and resembled those recorded for several strains of G. catenatum isolated from other coastal areas of Mexico.La proliferación de Gymnodinium son motivo de preocupación, debido a que en algunas circunstancias producen toxinas, que tienen consecuencias desfavorables para los ecosistemas marinos, la salud humana y la economía. Este trabajo describe las condiciones fisicoquímicas presentes durante una proliferación algal detectado en mayo de 2010 en la Bahía de Santiago y Bahía Manzanillo (Colima, México. La proliferación algal inició poco tiempo después de registrarse las temperaturas oceánicas superficiales más bajas del año, las cuales permitieron un aumento de las
Iron from melting glaciers fuels the phytoplankton blooms in Amundsen Sea (Southern Ocean): Iron biogeochemistry

NARCIS (Netherlands)

Gerringa, L.J.A.; Alderkamp, A.C.; Laan, P.; Thuróczy, C.E.; de Baar, H.J.W.; Mills, M.M.; van Dijken, G.L.; van Haren, H.; Arrigo, K.R.

2012-01-01

Dissolved iron (DFe) and total dissolvable Fe (TDFe) were measured in January-February 2009 in Pine Island Bay, as well as in the Pine Island and Amundsen polynyas (Amundsen Sea, Southern Ocean). Iron (Fe) has been shown to be a limiting nutrient for phytoplankton growth, even in the productive
Iron from melting glaciers fuels the phytoplankton blooms in Amundsen Sea (Southern Ocean) : Iron biogeochemistry

NARCIS (Netherlands)

Gerringa, Loes J. A.; Alderkamp, Anne-Carlijn; Laan, Patrick; Thuroczy, Charles-Edouard; De Baar, Hein J. W.; Mills, Matthew M.; van Dijken, Gert L.; van Haren, Hans; Arrigo, Kevin R.

2012-01-01

Dissolved iron (DFe) and total dissolvable Fe (TDFe) were measured in January-February 2009 in Pine Island Bay, as well as in the Pine Island and Amundsen polynyas (Amundsen Sea, Southern Ocean). Iron (Fe) has been shown to be a limiting nutrient for phytoplankton growth, even in the productive
Petal Thicknesses and Shape Transformations in Blooming Lilies

Energy Technology Data Exchange (ETDEWEB)

Portet, Thomas; Holmes, Peter N.; Bowden, Mark E.; Stephens, Sean A.; Varga, Tamas; Keller, Sarah L.

2013-01-29

During blooming, flower petals undergo significant shape changes. For lilies, various different mechanisms responsible for the change have been suggested [1,2]. One is that cell growth along the edge of a petal, or, more generally, a tepal, drives a transition from a cup shape (within a bud) to a saddle shape (within a bloom). This mechanism has been previously considered for tepals modeled as shallow elliptical shells whose thickness from the center, t, falls off at least as fast as t = t0 (1 - x2/a2 - y2/b2 ) [1]. Here t0 is the maximum thickness of the shell, a and b are the semimajor and semiminoraxes, x and y are the coordinates along the longitudinal and lateral axes. By measuring tepal thicknesses from images collected by x-ray tomography of intact buds and by photography of microtomed buds, we find that this condition is indeed met for both Lilium casablanca and Lilium lancifolium. [1] Liang and Mahadevan. Growth, geometry, and mechanics of a blooming lily.
Size Class Dependent Relationships between Temperature and Phytoplankton Photosynthesis-Irradiance Parameters in the Atlantic Ocean

Directory of Open Access Journals (Sweden)

Alex Robinson

2018-01-01

exhibited a wider temperature range compared to those derived from the Sathyendranath et al. (2009 method. The differences arise from the classification of mixed populations. Based on these patterns, we therefore recommend using the Sathyendranath et al. (2009 method to derive micro-phytoplankton PE parameters at sea water temperatures up to 8°C during monospecific blooms and the Uitz et al. (2008 method to derive PE parameters of mixed populations over the temperature range from 8 to 18°C. Both methods exhibited similar relationships between pico-phytoplankton PE parameters and temperatures >18°C.
Development of a coupled physical-biological ecosystem model ECOSMO - Part I: Model description and validation for the North Sea

DEFF Research Database (Denmark)

Schrum, Corinna; Alekseeva, I.; St. John, Michael

2006-01-01

A 3-D coupled biophysical model ECOSMO (ECOSystem MOdel) has been developed. The biological module of ECOSMO is based on lower trophic level interactions between two phyto- and two zooplankton components. The dynamics of the different phytoplankton components are governed by the availability...... of the macronutrients nitrogen, phosphate and silicate as well as light. Zooplankton production is simulated based on the consumption of the different phytoplankton groups and detritus. The biological module is coupled to a nonlinear 3-D baroclinic model. The physical and biological modules are driven by surface...... showed that the model, based on consideration of limiting processes, is able to reproduce the observed spatial and seasonal variability of the North Sea ecosystem e.g. the spring bloom, summer sub-surface production and the fall bloom. Distinct differences in regional characteristics of diatoms...
Mesopelagic Prokaryotes Alter Surface Phytoplankton Production during Simulated Deep Mixing Experiments in Eastern Mediterranean Sea Waters

Directory of Open Access Journals (Sweden)

Or Hazan

2018-01-01

Full Text Available Mesopelagic prokaryotes (archaea and bacteria, which are transported together with nutrient-rich intermediate-water to the surface layer by deep convection in the oceans (e.g., winter mixing, upwelling systems, can interact with surface microbial populations. This interaction can potentially affect production rates and biomass of surface microbial populations, and thus play an important role in the marine carbon cycle and oceanic carbon sequestration. The Eastern Mediterranean Sea (EMS is one of the most oligotrophic and warm systems in the world's oceans, with usually very shallow winter mixing (<200 m and lack of large-size spring algal blooms. In this study, we collected seawater (0–1,500 m in 9 different cruises at the open EMS during both the stratified and the mixed seasons. We show that the EMS is a highly oligotrophic regime, resulting in low autotrophic biomass and primary productivity and relatively high heterotrophic prokaryotic biomass and production. Further, we simulated deep water mixing in on-board microcosms using Levantine surface (LSW, ~0.5 m and intermediate (LIW, ~400 m waters at a 9:1 ratio, respectively and examined the responses of the microbial populations to such a scenario. We hypothesized that the LIW, being nutrient-rich (e.g., N, P and a “hot-spot” for microbial activity (due to the warm conditions that prevail in these depths, may supply the LSW with not only key-limiting nutrients but also with viable and active heterotrophic prokaryotes that can interact with the ambient surface microbial population. Indeed, we show that LIW heterotrophic prokaryotes negatively affected the surface phytoplankton populations, resulting in lower chlorophyll-a levels and primary production rates. This may be due to out-competition of phytoplankton by LIW populations for resources and/or by a phytoplankton cell lysis via viral infection. Our results suggest that phytoplankton in the EMS may not likely form blooms, even after
Nitrogen cycling in Sandusky Bay, Lake Erie: oscillations between strong and weak export and implications for harmful algal blooms

Science.gov (United States)

Salk, Kateri R.; Bullerjahn, George S.; McKay, Robert Michael L.; Chaffin, Justin D.; Ostrom, Nathaniel E.

2018-05-01

Recent global water quality crises point to an urgent need for greater understanding of cyanobacterial harmful algal blooms (cHABs) and their drivers. Nearshore areas of Lake Erie such as Sandusky Bay may become seasonally limited by nitrogen (N) and are characterized by distinct cHAB compositions (i.e., Planktothrix over Microcystis). This study investigated phytoplankton N uptake pathways, determined drivers of N depletion, and characterized the N budget in Sandusky Bay. Nitrate (NO3-) and ammonium (NH4+) uptake, N fixation, and N removal processes were quantified by stable isotopic approaches. Dissimilatory N reduction was a relatively modest N sink, with denitrification, anammox, and N2O production accounting for 84, 14, and 2 % of sediment N removal, respectively. Phytoplankton assimilation was the dominant N uptake mechanism, and NO3- uptake rates were higher than NH4+ uptake rates. Riverine N loading was sometimes insufficient to meet assimilatory and dissimilatory demands, but N fixation alleviated this deficit. N fixation made up 23.7-85.4 % of total phytoplankton N acquisition and indirectly supports Planktothrix blooms. However, N fixation rates were surprisingly uncorrelated with NO3- or NH4+ concentrations. Owing to temporal separation in sources and sinks of N to Lake Erie, Sandusky Bay oscillates between a conduit and a filter of downstream N loading to Lake Erie, delivering extensively recycled forms of N during periods of low export. Drowned river mouths such as Sandusky Bay are mediators of downstream N loading, but climate-change-induced increases in precipitation and N loading will likely intensify N export from these systems.
Optical Modeling of Spectral Backscattering and Remote Sensing Reflectance From Emiliania huxleyi Blooms

Directory of Open Access Journals (Sweden)

Griet Neukermans

2018-05-01

Full Text Available In this study we develop an analytical model for spectral backscattering and ocean color remote sensing of blooms of the calcifying phytoplankton species Emiliania huxleyi. Blooms of this coccolithophore species are ubiquitous and particularly intense in temperate and subpolar ocean waters. We first present significant improvements to our previous analytical light backscattering model for E. huxleyi coccoliths and coccospheres by accounting for the elliptical shape of coccoliths and the multi-layered coccosphere architecture observed on detailed imagery of E. huxleyi liths and coccospheres. Our new model also includes a size distribution function that closely matches measured E. huxleyi size distributions. The model for spectral backscattering is then implemented in an analytical radiative transfer model to evaluate the variability of spectral remote sensing reflectance with respect to changes in the size distribution of the coccoliths and during a hypothetical E. huxleyi bloom decay event in which coccospheres shed their liths. Our modeled remote sensing reflectance spectra reproduced well the bright milky turquoise coloring of the open ocean typically associated with the final stages of E. huxleyi blooms, with peak reflectance at a wavelength of 0.49 μm. Our results also show that the magnitude of backscattering from coccoliths when attached to or freed from the coccosphere does not differ much, contrary to what is commonly assumed, and that the spectral shape of backscattering is mainly controlled by the size and morphology of the coccoliths, suggesting that they may be estimated from spectral backscattering.
Lidar fluorosensor system for remote monitoring phytoplankton blooms in the Swedish marine campaign

Energy Technology Data Exchange (ETDEWEB)

Barbini, Roberto; Colao, Francesco; Fantoni, Roberta; Palucci, Antonio; Ribezzo, Sergio [ENEA, Centro Ricerche Frascati, Rome (Italy); Micheli, Carla [ENEA, Centro Ricerche Casaccia, Rome (Italy)

1997-09-01

The National Agency for New Technologies and the Environments group participated to the ICES/IOC workshop at Kristineberg Marine Research Station (Sweden, 9 - 15 September 1996) with instrumentation suitable to local and remote analysis of phytoplankton. The laser induced fluorescence (LIF) emission of natural communities and cultures has been monitored in vivo allowing to obtain information on the algae species, characterized by different pigments content, and on their photosynthetic activity, the latter differentially measured at different light levels in the presence of a saturating laser pulse. Chemical methods have been used for calibration purposes.
Greener on the Other Side: How Increased Urea Use may Promote Cyanobacterial Blooms

Science.gov (United States)

Erratt, K. J.; Creed, I. F.; Trick, C. G.

2017-12-01

The frequency of freshwater cyanobacterial blooms is on the rise in temperate regions around the world. The widespread use of chemical fertilizers linked to modern agricultural practices has enhanced the fertility of surface waters promoting the expansion of cyanobacteria dominated harmful algal blooms. While phosphorus (P) has been recognized as the principal agent regulating phytoplankton productivity in inland waters, elevated P is not the universal trigger for bloom initiation. P fertilizer applications across the globe have been outpaced by nitrogen (N) fertilizer use. Not only has the load of N entering surface waters increased, but its chemical composition has been altered. The use of inorganic-N fertilizers has been waned in favor of urea-based products, with urea now accounting for more than half of total N-fertilizer applications worldwide. This contemporary shift in fertilizer usage has coincided with the rise of cyanobacteria dominated harmful algal blooms in freshwaters. Here, we examined the relative success of urea as a N-source relative to inorganic N forms (NO3-, NH4+) for three common bloom-forming species of cyanobacteria: Microcystis aeruginosa, Dolichospermum flos-aque, and Synechococcus sp. We found that (1) urea was consistently drawdown more rapidly relative to inorganic N substrates, suggesting that cyanobacteria exhibit a preference for urea over inorganic N forms; (2) cyanobacteria consume urea in excess of cellular requirements; and (3) urea may offer cyanobacteria a competitive edge over eukaryotic algae by enhancing light absorption capabilities. As we push forward into the 21st century, our reliance on urea-based fertilizers is projected to escalate and it is critical that we understand the unintended consequences urea discharge could be having on receiving freshwaters.
The role of phytoplankton in the modulation of dissolved and oyster cadmium concentrations in Deep Bay, British Columbia, Canada

Energy Technology Data Exchange (ETDEWEB)

Cassis, David, E-mail: dcassis@telus.net [Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC, Canada V6T 1Z3 (Canada); Lekhi, Priyanka [Department of Chemistry, University of British Columbia, Vancouver, BC, Canada V6T 1Z3 (Canada); Pearce, Christopher M. [Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, BC, Canada V9T 6N7 (Canada); Ebell, Nadene [Ministry of Agriculture, Nanaimo, BC, Canada V9T 6J9 (Canada); Orians, Kristin [Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC, Canada V6T 1Z3 (Canada); Department of Chemistry, University of British Columbia, Vancouver, BC, Canada V6T 1Z3 (Canada); Maldonado, Maria T. [Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC, Canada V6T 1Z3 (Canada)

2011-09-15

We previously identified dissolved cadmium (Cd{sub diss}) as the main source of this metal in cultured Pacific oysters, Crassostrea gigas, in Deep Bay, British Columbia, Canada (Lekhi et al., 2008). Total suspended particulate Cd (Cd{sub part}) was not found to be a significant source of oyster Cd (Cd{sub oys}), with Cd{sub part} > 20 {mu}m negatively correlated with Cd{sub oys} concentration. High phytoplankton abundance in spring and summer was hypothesized to reduce Cd{sub oys} indirectly by drawing down Cd{sub diss} and increasing oyster growth. In the present study we expanded on these results by examining specifically how the phytoplankton community composition modulates both Cd{sub diss} and Cd{sub oys} concentrations in Deep Bay. Based on calculations of nutrients and Cd{sub diss} drawdown, phytoplankton accounted for approximately 90% of the overall summer reduction in Cd{sub diss} in the bay. Diatoms were the dominant phytoplankton group, being correlated negatively with Cd{sub oys} and positively with Cd{sub part}. This suggests that diatom growth mediates the transfer of Cd from the dissolved to the particulate phase, resulting in lower Cd{sub oys}. Spring blooms and sporadic harmful algal blooms may mediate a large flux of Cd{sub part} to the sediments. Thus, phytoplankton act as a sink, rather than a source, of Cd to oysters in Deep Bay and have a crucial role in the seasonality of Cd{sub oys} by reducing the concentration of Cd{sub diss} during the summer. Based on environmental variables, two descriptive models for annual Cd{sub oys} concentrations were developed using multiple linear regression. The first model (R{sup 2} = 0.870) was created to explain the maximum variability in Cd{sub oys} concentrations throughout the year, while the second (R{sup 2} = 0.806) was based on parameters that could be measured easily under farm conditions. Oyster age heavily affected both models, with the first model being secondarily affected by temperature and the
A Stable-Isotope Mass Spectrometry-Based Metabolic Footprinting Approach to Analyze Exudates from Phytoplankton

Directory of Open Access Journals (Sweden)

Mark R. Viant

2013-10-01

Full Text Available Phytoplankton exudates play an important role in pelagic ecology and biogeochemical cycles of elements. Exuded compounds fuel the microbial food web and often encompass bioactive secondary metabolites like sex pheromones, allelochemicals, antibiotics, or feeding attractants that mediate biological interactions. Despite this importance, little is known about the bioactive compounds present in phytoplankton exudates. We report a stable-isotope metabolic footprinting method to characterise exudates from aquatic autotrophs. Exudates from 13C-enriched alga were concentrated by solid phase extraction and analysed by high-resolution Fourier transform ion cyclotron resonance mass spectrometry. We used the harmful algal bloom forming dinoflagellate Alexandrium tamarense to prove the method. An algorithm was developed to automatically pinpoint just those metabolites with highly 13C-enriched isotope signatures, allowing us to discover algal exudates from the complex seawater background. The stable-isotope pattern (SIP of the detected metabolites then allowed for more accurate assignment to an empirical formula, a critical first step in their identification. This automated workflow provides an effective way to explore the chemical nature of the solutes exuded from phytoplankton cells and will facilitate the discovery of novel dissolved bioactive compounds.
Decomposition of lake phytoplankton. 2

International Nuclear Information System (INIS)

Hansen, L.; Krog, G.F.; Soendergaard, M.

1986-01-01

The lysis process of phytoplankton was followed in 24 h incubations in three Danish lakes. By means of gel-chromatography it was shown that the dissolved carbon leaching from different algal groups differed in molecular weight composition. Three distinct molecular weight classes (>10,000; 700 to 10,000 and < 700 Daltons) leached from blue-green algae in almost equal proportion. The lysis products of spring-bloom diatoms included only the two smaller size classes, and the molecules between 700 and 10,000 Daltons dominated. Measurements of cell content during decomposition of the diatoms revealed polysaccharides and low molecular weight compounds to dominate the lysis products. No proteins were leached during the first 24 h after cell death. By incubating the dead algae in natural lake water, it was possible to detect a high bacterial affinity towards molecules between 700 and 10,000 Daltons, although the other size classes were also utilized. Bacterial transformation of small molecules to larger molecules could be demonstrated. (author)
Winter−spring transition in the subarctic Atlantic: microbial response to deep mixing and pre-bloom production

DEFF Research Database (Denmark)

Paulsen, Maria Lund; Riisgaard, Karen; Thingstad, T. Frede

2015-01-01

In temperate, subpolar and polar marine systems, the classical perception is that diatoms initiate the spring bloom and thereby mark the beginning of the productive season. Contrary to this view, we document an active microbial food web dominated by pico- and nanoplankton prior to the diatom bloom......, a period with excess nutrients and deep convection of the water column. During repeated visits to stations in the deep Iceland and Norwegian basins and the shallow Shetland Shelf (26 March to 29 April 2012), we investigated the succession and dynamics of photo - synthetic and heterotrophic microorganisms....... We observed that the early phytoplankton production was followed by a decrease in the carbon:nitrogen ratio of the dissolved organic matter in the deep mixed stations, an increase in heterotrophic prokaryote (bacteria) abundance and activity (indicated by the high nucleic acid:low nucleic acid...

Links between phytoplankton dynamics and shell growth of Arctica islandica on the Faroe Shelf

Science.gov (United States)

Bonitz, Fabian Georg Wulf; Andersson, Carin; Trofimova, Tamara; Hátún, Hjálmar

2018-03-01

The phytoplankton dynamics on the Faroe Shelf are strongly connected to higher trophic levels, and their inter-annual variability has great importance for many organisms, including the principal fish stocks. Hence, information on the marked phytoplankton variability is scientifically and economically valuable. We show here that the shell growth variability in Arctica islandica shells has the potential to identify periods of increased and decreased phytoplankton concentrations on the Faroe Shelf and in the wider Faroese region in previous centuries. The growth of A. islandica has often been linked to changes in phytoplankton concentrations, i.e., food availability. By cross-matching life-collected and sub-fossil A. islandica shells from two separate locations on the Faroe Shelf, we have built a master chronology, which reaches back to the 17th century. This master chronology correlates well with a Primary Production index for the Faroe Shelf (r = 0.65; p phytoplankton concentrations over the wider Faroese Channel Region, as represented in the Continuous Plankton Recorder surveys, especially for the months June-September (r = 0.39; p < 0.01). In addition, an inverse relationship is observed between the master chronology and on-shelf water temperatures from June-September (r = - 0.29; p < 0.01), which is likely associated with a previously reported inverse relationship between temperatures and the on-shelf primary production. An analysis of the δ18O in the shells shows that the main growing season of the shells presumably occurs during the spring and summer months, which concurs with the main spring bloom.
Laboratory LiF characterization of different phytoplankton species originating harmful blooms

Energy Technology Data Exchange (ETDEWEB)

Barbini, R.; Colao, F.; Fantoni, R.; Palucci, A.; Ribezzo, S. [ENEA, Centro Ricerche Frascati, Rome (Italy). Dip. Innovazione; Micheli, C. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Innovazione

1997-11-01

A systematic laboratory characterization of different phytoplankton cultures has been performed in combination with LiF (Laser Induced Fluorescence) measurements aimed to investigate the possibility of their remote monitoring by means of lidar fluoro sensor systems. Cultures of microalgae characterized by different pigment contents have been analyzed in the visible region upon UV laser excitation. High resolution laboratory spectra have been measured in order to obtain the fingerprint of each species. Emission wavelength related to the main pigments contribution have been identified. Detection limits of the emitted red chlorophyll signal have been evaluated for the different species after dilution in the culture medium and in real sea water. Prior to the LiF excitation aimed to the remote characterization the algal cultures were morphologically analyzed by fluorescence and scanning electron microscopy. Furthermore the relevant cell number was counted for biomass estimation, and the chlorophylls content was determined by different chemical methods.
Glophymed: an index to establish the ecological status for the Water Framework Directive based on phytoplankton in coastal waters.

Science.gov (United States)

Romero, I; Pachés, M; Martínez-Guijarro, R; Ferrer, J

2013-10-15

Phytoplankton and its attributes (biomass, abundance, composition, and frequency and intensity of phytoplankton blooms) are essential to establish the ecological status in the Water Frame Directive. The aim of this study is to develop an index "Glophymed" based on all phytoplankton attributes for coastal water bodies according to the directive requirements. It is also developed an anthropogenic pressure index that takes into account population density, tourism, urbanization, industry, agriculture, fisheries and maritime transport for Comunitat Valenciana (Spain). Both indexes (Glophymed and human pressure index) based on a multisampling dataset collected monthly during several years, show a significant statistical correlation (r2 0.75 α<0.01) for typology IIA and (r2 0.93 α<0.01) for typology III-W. The relation between these indexes provides suitable information about the integrated management plans and protection measures of water resources since the Glophymed index is very sensitive to human pressures. Copyright © 2013 Elsevier Ltd. All rights reserved.
Seasonal and Inter-Annual Patterns of Phytoplankton Community Structure in Monterey Bay, CA Derived from AVIRIS Data During the 2013-2015 HyspIRI Airborne Campaign

Science.gov (United States)

Palacios, S. L.; Thompson, D. R.; Kudela, R. M.; Negrey, K.; Guild, L. S.; Gao, B. C.; Green, R. O.; Torres-Perez, J. L.

2015-12-01

There is a need in the ocean color community to discriminate among phytoplankton groups within the bulk chlorophyll pool to understand ocean biodiversity, to track energy flow through ecosystems, and to identify and monitor for harmful algal blooms. Imaging spectrometer measurements enable use of sophisticated spectroscopic algorithms for applications such as differentiating among coral species, evaluating iron stress of phytoplankton, and discriminating phytoplankton taxa. These advanced algorithms rely on the fine scale, subtle spectral shape of the atmospherically corrected remote sensing reflectance (Rrs) spectrum of the ocean surface. As a consequence, these algorithms are sensitive to inaccuracies in the retrieved Rrs spectrum that may be related to the presence of nearby clouds, inadequate sensor calibration, low sensor signal-to-noise ratio, glint correction, and atmospheric correction. For the HyspIRI Airborne Campaign, flight planning considered optimal weather conditions to avoid flights with significant cloud/fog cover. Although best suited for terrestrial targets, the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) has enough signal for some coastal chlorophyll algorithms and meets sufficient calibration requirements for most channels. However, the coastal marine environment has special atmospheric correction needs due to error that may be introduced by aerosols and terrestrially sourced atmospheric dust and riverine sediment plumes. For this HyspIRI campaign, careful attention has been given to the correction of AVIRIS imagery of the Monterey Bay to optimize ocean Rrs retrievals for use in estimating chlorophyll (OC3 algorithm) and phytoplankton functional type (PHYDOTax algorithm) data products. This new correction method has been applied to several image collection dates during two oceanographic seasons - upwelling and the warm, stratified oceanic period for 2013 and 2014. These two periods are dominated by either diatom blooms (occasionally
Subsurface seeding of surface harmful algal blooms observed through the integration of autonomous gliders, moored environmental sample processors, and satellite remote sensing in southern California

KAUST Repository

Seegers, Bridget N.

2015-04-01

An observational study was performed in the central Southern California Bight in Spring 2010 to understand the relationship between seasonal spring phytoplankton blooms and coastal processes that included nutrient input from upwelling, wastewater effluent plumes, and other processes. Multi-month Webb Slocum glider deployments combined with MBARI environmental sample processors (ESPs), weekly pier sampling, and ocean color data provided a multidimensional characterization of the development and evolution of harmful algal blooms (HABs). Results from the glider and ESP observations demonstrated that blooms of toxic Pseudo-nitzschia sp. can develop offshore and subsurface prior to their manifestation in the surface layer and/or near the coast. A significant outbreak and surface manifestation of the blooms coincided with periods of upwelling, or other processes that caused shallowing of the pycnocline and subsurface chlorophyll maximum. Our results indicate that subsurface populations can be an important source for “seeding” surface Pseudo-nitzschia HAB events in southern California.
UV-Visible Spectroscopic Method and Models for Assessment and Monitoring of Harmful Algal Blooms

Science.gov (United States)

Mitchell, B. Greg

2000-01-01

The development of an enhanced predictive and early warning capability for the occurrence and impact of harmful algal blooms (HABs) would be of great benefit to coastal communities. A critical issue for early detection and monitoring of HABs is the need to detect harmful algal species within a mixed-species phytoplankton assemblage. Possession of UV-absorbing compounds called mycosporine-like amino acids (MAAs) may be one factor that allows HAB species to out-compete their phytoplankton neighbors. Possession of MAAs, which we believe can be inferred from strong UV-absorption signals in phytoplankton absorption coefficients, can be used as a flag for potential HAB outbreak. The goal of this project was to develop a solar simulating UV-visible incubator to grow HAB dinoflagellates, to begin MAA analysis of samples collected on global cruises, and to carry out initial experiments on HAB dinoflagellate species in pure culture. Our scientific objectives are to quantify MAA production and spectral induction mechanisms in HAB species, to characterize spectral absorption of MAAs, and to define the ecological benefit of MAAs (i.e. photoprotection). Data collected on cruises to the global oceans will be used to parameterize phytoplankton absorption in the UV region, and this parameterization could be incorporated into existing models of seawater optical properties in the UV spectral region. Data collected in this project were used for graduate fellowship applications by Elizabeth Frame. She has been awarded an EPA STAR fellowship to continue the work initiated by this project.
Discriminating Phytoplankton Functional Types (PFTs) in the Coastal Ocean Using the Inversion Algorithm Phydotax and Airborne Imaging Spectrometer Data

Science.gov (United States)

Palacios, Sherry L.; Schafer, Chris; Broughton, Jennifer; Guild, Liane S.; Kudela, Raphael M.

2013-01-01

There is a need in the Biological Oceanography community to discriminate among phytoplankton groups within the bulk chlorophyll pool to understand energy flow through ecosystems, to track the fate of carbon in the ocean, and to detect and monitor-for harmful algal blooms (HABs). The ocean color community has responded to this demand with the development of phytoplankton functional type (PFT) discrimination algorithms. These PFT algorithms fall into one of three categories depending on the science application: size-based, biogeochemical function, and taxonomy. The new PFT algorithm Phytoplankton Detection with Optics (PHYDOTax) is an inversion algorithm that discriminates taxon-specific biomass to differentiate among six taxa found in the California Current System: diatoms, dinoflagellates, haptophytes, chlorophytes, cryptophytes, and cyanophytes. PHYDOTax was developed and validated in Monterey Bay, CA for the high resolution imaging spectrometer, Spectroscopic Aerial Mapping System with On-board Navigation (SAMSON - 3.5 nm resolution). PHYDOTax exploits the high spectral resolution of an imaging spectrometer and the improved spatial resolution that airborne data provides for coastal areas. The objective of this study was to apply PHYDOTax to a relatively lower resolution imaging spectrometer to test the algorithm's sensitivity to atmospheric correction, to evaluate capability with other sensors, and to determine if down-sampling spectral resolution would degrade its ability to discriminate among phytoplankton taxa. This study is a part of the larger Hyperspectral Infrared Imager (HyspIRI) airborne simulation campaign which is collecting Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) imagery aboard NASA's ER-2 aircraft during three seasons in each of two years over terrestrial and marine targets in California. Our aquatic component seeks to develop and test algorithms to retrieve water quality properties (e.g. HABs and river plumes) in both marine and in
Heterosigma bloom and associated fish kill

Science.gov (United States)

Hershberger, P.K.; Rensel, J.E.; Postel, J.R.; Taub, F.B.

1997-01-01

A bloom of the harmful marine phytoplankton, Heterosigma carterae occurred in upper Case Inlet, south Puget Sound, Washington in late September, 1994, correlating with the presence of at least 35 dead salmon. This marks the first time that this alga has been closely correlated with a wild fish kill; in the past it was thought to be associated with kills of penned fish at fish farms only. We were informed of the presence of a possible harmful algal bloom and dead salinois Ilear the town of Allyn on 27 September and a team was formed to investigate. We arrived at the Allyn waterfront at 17:30 hours the same day. Prior to our arrival, state agency personnel walked approximatcly two miles of shoreline from the powerlines north of the dock, to the mouth of Sherwood Creek and conducted the only official count of dead fish present along the shore consisting of 12 coho salmon (Oncorhynchus kisutch), 11 chum salmon (Oncorhynchus keta), 12 chinook salmon (Oncorhynchus tschawytscha), one flat fish, and one sculpin on the morning of 9/27. Since previous harmful blooms of Heterosigma have resultedin the majority of net penreared salmon sinking to the bottom of pens, and only approximately two miles of shoreline were sampled, it is suspected that many more exposed fish may have succumbed than were counted. Witnesses who explored the east side of the bay reported seeing many dead salmon there as well, but no counts were made. State agency personnel who observed the fish kill reported seeing “dying fish coming to the beach, gulping at the surface, trying to get out of the water” Scavengers were seen consuming the salmon carcasses; these included two harbor seals, a house cat, and Hymenopteran insects. None suffered any noticeable acute ill effects. Although precise cause of death has not been ascertained, visual inspection of the reproductive organs from a deceased male chum salmon found on the shore at Allyn confirmed that the fish was not yet reproductively mature and
Winter atmospheric circulation signature for the timing of the spring bloom of diatoms in the North Sea

Science.gov (United States)

Lohmann, Gerrit; Wiltshire, Karen

2015-04-01

Analysing long-term diatom data from the German Bight and observational climate data for the period 1962-2005, we found a close connection of the inter-annual variation of the timing of the spring bloom with the boreal winter atmospheric circulation. We examined the fact that high diatom counts of the spring bloom tended to occur later when the atmospheric circulation was characterized by winter blocking over Scandinavia. The associated pattern in the sea level pressure showed a pressure dipole with two centres located over the Azores and Norway and was tilted compared to the North Atlantic Oscillation. The bloom was earlier when the cyclonic circulation over Scandinavia allowed an increased inflow of Atlantic water into the North Sea which is associated with clearer, more marine water, and warmer conditions. The bloom was later when a more continental atmospheric flow from the east was detected. At Helgoland Roads, it seems that under turbid water conditions (= low light) zooplankton grazing can affect the timing of the phytoplankton bloom negatively. Warmer water temperatures will facilitate this. Under clear water conditions, light will be the main governing factor with regard to the timing of the spring bloom. These different water conditions are shown here to be mainly related to large-scale weather patterns. We found that the mean diatom bloom could be predicted from the sea level pressure one to three months in advance. Using historical pressure data, we derived a proxy for the timing of the spring bloom over the last centuries, showing an increased number of late (proxy-) blooms during the eighteenth century when the climate was considerably colder than today. We argue that these variations are important for the interpretation of inter-annual to centennial variations of biological processes. This is of particular interest when considering future scenarios, as well to considerations on past and future effects on the primary production and food webs.
Cyanobacterial blooms in stratified and destratified eutrophic reservoirs in semi-arid region of Brazil.

Science.gov (United States)

Dantas, Enio W; Moura, Ariadne N; Bittencourt-Oliveira, Maria do Carmo

2011-12-01

This study investigated the dynamics of cyanobacteria in two deep, eutrophic reservoirs in a semi-arid region of Brazil during periods of stratification and destratification. Four collections were carried out at each reservoir at two depths at three-month intervals. The following abiotic variables were analyzed: water temperature, dissolved oxygen, pH, turbidity, water transparency, total phosphorus, total dissolved phosphorus, orthophosphate and total nitrogen. Phytoplankton density was quantified for the determination of the biomass of cyanobacteria. The data were analyzed using CCA. Higher mean phytoplankton biomass values (29.8 mm(3).L(-1)) occurred in the period of thermal stratification. A greater similarity in the phytoplankton communities also occurred in this period and was related to the development of cyanobacteria, mainly Cylindrospermopsis raciborskii (>3.9 mm(3).L(-1)). During the period of thermal destratification, this species co-dominated the environment with Planktothrix agardhii, Geitlerinema amphibium, Microcystis aeruginosa and Merismopedia tenuissima, as well as with diatoms and phytoflagellates. Environmental instability and competition among algae hindered the establishment of blooms more during the mixture period than during the stratification period. Thermal changes in the water column caused by climatologic events altered other physiochemical conditions of the water, leading to changes in the composition and biomass of the cyanobacterial community in tropical reservoirs.
Particulate Trace Element Cycling in a Diatom Bloom at Station ALOHA

Science.gov (United States)

Weisend, R.; Morton, P. L.; Landing, W. M.; Fitzsimmons, J. N.; Hayes, C. T.; Boyle, E. A.

2014-12-01

Phytoplankton in oligotrophic marine deserts depend on remote sources to supply trace nutrients. To examine these sources, marine particulate matter samples from the central North Pacific (Station ALOHA) were collected during the July-August 2012 HOE-DYLAN cruises and analyzed for a suite of trace (e.g., Fe, Mn) and major (e.g. Al, P) elements. Daily surface SPM samples were examined for evidence of atmospheric deposition and biological uptake, while five vertical profiles were examined for evidence of surface vertical export and subsurface horizontal transport from nearby sources (e.g., margin sediments, hydrothermal plumes). Maxima in surface particulate P (a biological tracer) corresponded with a diatom bloom, and surprisingly also coincided with maxima in particulate Al (typically a tracer for lithogenic inputs). The surface particulate Al distributions likely result from the adsorption of dissolved Al onto diatom silica frustules, not from atmospheric dust deposition. In addition, a subsurface maximum in particulate Al and P was observed four days later at 75m, possibly resulting from vertical export of the surface diatom bloom. The distributions of other bioactive trace elements (e.g. Cd, Co, Cu) will be presented in the context of the diatom bloom and other biological, chemical and physical features. A second, complementary poster is also being presented which examines the cycling of trace elements in lithogenic particles (Morton et al., "Trace Element Cycling in Lithogenic Particles at Station ALOHA").
Spatio-temporal variability of the phytoplankton biomass in the Levantine basin between 2002 and 2015 using MODIS products

Directory of Open Access Journals (Sweden)

Roy El Hourany

2017-04-01

Full Text Available The Levantine basin in the Eastern Mediterranean Sea is subject to spatial and seasonal variations in primary production and physical-chemical properties both on a short and long-term basis. In this study, the monthly means of daily MODIS product images were averaged between 2002 and 2015, and used to characterize the phytoplankton blooms in different bioregions of the Levantine basin. The selected products were the sea surface temperature (SST, the chlorophyll-a concentration (Chl-a, the diffuse attenuation coefficient for downwelling irradiance at 490 nm (Kd_490 and the colored dissolved organic matter index (CDOM_index. Our results showed that phytoplankton blooms were spatially and temporally variable. They occurred in late autumn at the Nile Delta, in early spring and late summer at the eastern coastline, and in spring at the northeastern coastline. The northern coastline and the open water had a common bloom occurring in winter. The Nile Delta was found to be the most productive area of the Levantine basin showing high Chl-a. Kd_490 and Chl-a present a parallel co-variation indicating a dominance of Case 1 waters in the Levantine basin. The CDOM_index shows a phase shift with the Chl-a fluctuation. A strong inverse correlation was observed between both Chl-a and CDOM_index with SST, connoting an indirect relation represented by a depression of CDOM in summer by photobleaching, and a suppression of the chlorophyll-a concentration due to water stratification, together with nutrient stress. An overestimation of the Chl-a values had been signaled by the use of the CDOM_index, suggesting a correction plan in a latter study.
Catchment-fed cyanobacterial blooms in brownified temperate lakes

Science.gov (United States)

Senar, O.; Creed, I. F.

2017-12-01

One of the most significant impacts of global atmospheric change is the alteration of hydrological regimes and the associated disruption of hydrological connectivity within watersheds. We show how changes in the frequency, magnitude, and duration of hydrological connectivity and disconnectivity is compromising the capacity of forest soils to store organic carbon, and increasing its export to both aquatic and atmospheric systems. Increases in dissolved organic matter (DOM) loads from forested landscapes to aquatic systems and the shift of the DOM pool to a more refractory mixture of organic compounds, a process known as brownification, alters the physical and chemical characteristics of lake environments. Furthermore, by characterizing the stages of brownification (from low to high concentrations of refractory DOM), we show a shift in the limiting factors for phytoplankton growth from macronutrients (nitrogen -N- and phosphorus -P) to micronutrients (iron -Fe) and light availability. This shift is driven by the low concentrations of DOM supplying N and P in early stages of brownification, to the strong Fe-binding capacity of refractory DOM in brownified lakes. As lakes undergo brownification, cyanobacteria adapted to scavenge Fe from DOM-Fe complexes have a competitive advantage leading to the formation of cyanobacterial blooms. Our findings provide evidence that brownification is a driving force leading to cyanobacterial blooms in lakes on forested landscapes, with expected cascading consequences to lake food webs.
Phytoplankton Group Identification Using Simulated and In situ Hyperspectral Remote Sensing Reflectance

Directory of Open Access Journals (Sweden)

Hongyan Xi

2017-08-01

Full Text Available In the present study we investigate the bio-geo-optical boundaries for the possibility to identify dominant phytoplankton groups from hyperspectral ocean color data. A large dataset of simulated remote sensing reflectance spectra, Rrs(λ, was used. The simulation was based on measured inherent optical properties of natural water and measurements of five phytoplankton light absorption spectra representing five major phytoplankton spectral groups. These simulated data, named as C2X data, contain more than 105 different water cases, including cases typical for clearest natural waters as well as for extreme absorbing and extreme scattering waters. For the simulation the used concentrations of chlorophyll a (representing phytoplankton abundance, Chl, are ranging from 0 to 200 mg m−3, concentrations of non-algal particles, NAP, from 0 to 1,500 g m−3, and absorption coefficients of chromophoric dissolved organic matter (CDOM at 440 nm from 0 to 20 m−1. A second, independent, smaller dataset of simulated Rrs(λ used light absorption spectra of 128 cultures from six phytoplankton taxonomic groups to represent natural variability. Spectra of this test dataset are compared with spectra from the C2X data in order to evaluate to which extent the five spectral groups can be correctly identified as dominant under different optical conditions. The results showed that the identification accuracy is highly subject to the water optical conditions, i.e., contribution of and covariance in Chl, NAP, and CDOM. The identification in the simulated data is generally effective, except for waters with very low contribution by phytoplankton and for waters dominated by NAP, whereas contribution by CDOM plays only a minor role. To verify the applicability of the presented approach for natural waters, a test using in situ Rrs(λ dataset collected during a cyanobacterial bloom in Lake Taihu (China is carried out and the approach predicts blue cyanobacteria to be dominant
A consistent structure of phytoplankton communities across the warm-cold regions of the water mass on a meridional transect in the East/Japan Sea

Science.gov (United States)

Kwak, Jung Hyun; Han, Eunah; Lee, Sang Heon; Park, Hyun Je; Kim, Kyung-Ryul; Kang, Chang-Keun

2017-09-01

Three cruises were undertaken along a meridional transect in the East/Japan Sea (EJS) in spring (May 2007), summer (July 2009), and fall (October 2012) to determine the geographic variations in phytoplankton biomass and community composition. This study revealed a gradient of surface temperature and a fluctuation of hydrographic conditions along the transect. Although a subpolar front (SPF) formed between the warm- and cold-water masses (37-40°N), no significant differences in phytoplankton biomass and community composition were detected between the southern and northern parts of the EJS. These results disprove our initial hypothesis that different water masses may contain differently structured phytoplankton communities. In the present study, isothermal layers (≤ 12 °C) fluctuated over a depth of 50 m in both warm- and cold-water masses, depending on the SPF. In contrast, the nitracline (i.e. 2.5 μM nitrate isopleth) depth was recorded within a limited range of 20-40 m in spring, 30-50 m in summer, and 40-60 m in fall. The chlorophyll a concentrations at the subsurface chlorophyll maxima (SCM) were significantly higher in spring and summer (356 ± 233 and 270 ± 182 ng L-1, respectively) than in fall (117 ± 89 ng L-1). The relative contributions of individual phytoplankton groups to the depth-integrated chlorophyll a concentration conformed to the composition of the phytoplankton community in the SCM layer, showing a dominance of diatoms (58 ± 19% in spring, 48 ± 11% in summer, and 30 ± 20% in fall). Canonical correspondence analysis revealed that the geographic structures of phytoplankton communities were strongly associated with the vertical structures of water temperature and nutrient concentration in the water column rather than with horizontal gradients of hydrographic conditions. Finally, our findings suggest that water column stability and light-nutrient availability in the euphotic zone play a key role in determining geographical consistency of
Wintertime pytoplankton bloom in the Subarctic Pacific supportedby continental margin iron

Energy Technology Data Exchange (ETDEWEB)

Lam, Phoebe J.; Bishop, James K.B.; Henning, Cara C.; Marcus,Matthew A.; Waychunas, Glenn A.; Fung, Inez

2004-06-08

Heightened biological activity was observed in February 1996in the high-nutrient low-chlorophyll (HNLC) subarctic North PacificOcean, a region that is thought to beiron-limited. Here we provideevidence supporting the hypothesis that Ocean Station Papa (OSP) in thesubarctic Pacific received a lateral supply of particulate iron from thecontinental margin off the Aleutian Islands in the winter, coincidentwith the observed biological bloom. Synchrotron X-ray analysis was usedto describe the physical form, chemistry, and depth distributions of ironin size fractionated particulate matter samples. The analysis revealsthat discrete micron-sized iron-rich hotspots are ubiquitous in the upper200m at OSP, more than 900km from the closest coast. The specifics of thechemistry and depth profiles of the Fe hot spots trace them to thecontinental margins. We thus hypothesize that iron hotspots are a markerfor the delivery of iron from the continental margin. We confirm thedelivery of continental margin iron to the open ocean using an oceangeneral circulation model with an iron-like tracer source at thecontinental margin. We suggest that iron from the continental marginstimulated a wintertime phytoplankton bloom, partially relieving the HNLCcondition.
Dynamics of late spring and summer phytoplankton communities on Georges Bank, with emphasis on diatoms, Alexandrium spp., and other dinoflagellates

Science.gov (United States)

Gettings, Rachel M.; Townsend, David W.; Thomas, Maura A.; Karp-Boss, Lee

2014-05-01

We analyzed the distribution, abundance, and succession patterns of major phytoplankton taxa on Georges Bank in relation to hydrography, nutrients, and size-fractionated chlorophyll concentrations (>20 μm; Gymnodinium spp., and Prorocentrum spp., had become more abundant. Patches of regenerated silicate during the June-July period appeared to support a post-spring-bloom diatom community on the central crest of the Bank (total diatom cell densities >180,000 cellsl-1) of Leptocylindrus spp., Dactyliosolen spp., and Guinardia flaccida. Multivariate statistical analyses of phytoplankton taxa and station locations revealed distinct assemblages of diatom and dinoflagellate taxa on the Bank throughout the late spring and summer. Results are interpreted in the ecological context of earlier-reported laboratory culture experiments on the competitive interactions between Alexandrium fundyense and diatoms.
Spatial-temporal distribution of phytoplankton pigments in relation to nutrient status in Jiaozhou Bay, China

Science.gov (United States)

Yao, Peng; Yu, Zhigang; Deng, Chunmei; Liu, Shuxia; Zhen, Yu

2010-10-01

We conducted studies of phytoplankton and hydrological variables in a semi-enclosed bay in northern China to understand the spatial-temporal variability and relationship between these variables. Samples were collected during seven cruises in Jiaozhou Bay from November 2003 to October 2004, and were analyzed for temperature, nutrients and phytoplankton pigments. Pigments from eight possible phytoplankton classes (Diatoms, Dinoflagellates, Chlorophyceae, Prasinophyceae, Chrysophyceae, Haptophyceae, Cryptophyceae and Caynophyceae) were detected in surface water by high performance liquid chromatography (HPLC). Phytoplankton pigment and nutrient concentrations in Jiaozhou Bay were spatially and temporally variable, and most of them were highest in the northern and eastern parts of the sampling regions in spring (May) and summer (August), close to areas of shellfish culturing, river estuaries, dense population and high industrialization, reflecting human activities. Chlorophyll a was recorded in all samples, with an annual mean concentration of 1.892 μg L -1, and fucoxanthin was the most abundant accessory pigment, with a mean concentration of 0.791 μg L -1. The highest concentrations of chlorophyll a (15.299 μg L -1) and fucoxanthin (9.417 μg L -1) were observed in May 2004 at the station close to the Qingdao Xiaogang Ferry, indicating a spring bloom of Diatoms in this area. Although chlorophyll a and other biomarker pigments showed significant correlations, none of them showed strong correlations with temperature and nutrients, suggesting an apparent de-coupling between the pigments and these hydrological variables. The nutrient composition and phytoplankton community composition of Jiaozhou Bay have changed significantly in the past several decades, reflecting the increasing nutrient concentrations and decline of phytoplankton cell abundance. The unchanged total chlorophyll a levels indicated that smaller species have filled the niche vacated by the larger
Spatio-temporal variability of the phytoplankton biomass in the Levantine basin between 2002 and 2015 using MODIS products

OpenAIRE

Roy El Hourany; Ali Fadel; Elissar Gemayel; Marie Abboud-Abi Saab; Ghaleb Faour

2017-01-01

The Levantine basin in the Eastern Mediterranean Sea is subject to spatial and seasonal variations in primary production and physical-chemical properties both on a short and long-term basis. In this study, the monthly means of daily MODIS product images were averaged between 2002 and 2015, and used to characterize the phytoplankton blooms in different bioregions of the Levantine basin. The selected products were the sea surface temperature (SST), the chlorophyll-a concentration (Chl-a), the d...
Viral attack exacerbates the susceptibility of a bloom-forming alga to ocean acidification.

Science.gov (United States)

Chen, Shanwen; Gao, Kunshan; Beardall, John

2015-02-01

Both ocean acidification and viral infection bring about changes in marine phytoplankton physiological activities and community composition. However, little information is available on how the relationship between phytoplankton and viruses may be affected by ocean acidification and what impacts this might have on photosynthesis-driven marine biological CO2 pump. Here, we show that when the harmful bloom alga Phaeocystis globosa is infected with viruses under future ocean conditions, its photosynthetic performance further decreased and cells became more susceptible to stressful light levels, showing enhanced photoinhibition and reduced carbon fixation, up-regulation of mitochondrial respiration and decreased virus burst size. Our results indicate that ocean acidification exacerbates the impacts of viral attack on P. globosa, which implies that, while ocean acidification directly influences marine primary producers, it may also affect them indirectly by altering their relationship with viruses. Therefore, viruses as a biotic stressor need to be invoked when considering the overall impacts of climate change on marine productivity and carbon sequestration. © 2014 John Wiley & Sons Ltd.

Bloom dynamics of the genus Pseudo-nitzschia (Bacillariophyceae in two coastal bays (NW Mediterranean Sea

Directory of Open Access Journals (Sweden)

Sonia Quijano-Scheggia

2008-09-01

Full Text Available The spatial and temporal variations in the composition of Pseudo-nitzschia during bloom events from August 2005 to February 2006 were characterised in two bays of the NW Mediterranean Sea (Alfacs and Fangar Bay by means of scanning electron microscopy (SEM. The study provides detailed records of the Pseudo-nitzschia community at the species level and describes its relationship with both the surrounding environmental conditions and biotic factors such as the accompanying phytoplankton community. The size distributions of several species of Pseudo-nitzschia were monitored during the bloom events. These measurements may serve as indicators of the physiological status of the cells. The species observed in the two bays were Pseudo-nitzschia calliantha, P. delicatissima, P. fraudulenta, P. multistriata, and P. pungens. In Alfacs Bay, a mixed species bloom of P. calliantha and P. delicatissima began in late August 2005 and lasted 11 weeks. In Fangar Bay, the Pseudo-nitzschia bloom was limited to the period from early August to late September 2005 and comprised P. calliantha and P. delicatissima. Commonly, the proliferation of Pseudo-nitzschia was mono-specific or was accompanied by other diatoms. Two objectively defined groups were identified by the statistical analysis in Alfacs bay; the first was made up only of winter samples and the second of summer and autumn samples. The first group was defined by a high concentration of NO3¯ and low concentrations of NH4+, conditions associated with a high abundance of P. delicatissima and a low abundance of P. calliantha. The second group expressed the opposite characteristics. A succession of different blooming species of Pseudo-nitzschia lasting months in Alfacs Bay is described.
Network of interactions between ciliates and phytoplankton during spring

Directory of Open Access Journals (Sweden)

Thomas ePosch

2015-11-01

Full Text Available The annually recurrent spring phytoplankton blooms in freshwater lakes initiate pronounced successions of planktonic ciliate species. Although there is considerable knowledge on the taxonomic diversity of these ciliates, their species-specific interactions with other microorganisms are still not well understood. Here we present the succession patterns of 20 morphotypes of ciliates during spring in Lake Zurich, Switzerland, and we relate their abundances to phytoplankton genera, flagellates, heterotrophic bacteria, and abiotic parameters. Interspecific relationships were analyzed by contemporaneous correlations and time-lagged co-occurrence and visualized as association networks. The contemporaneous network pointed to the pivotal role of distinct ciliate species (e.g., Balanion planctonicum, Rimostrombidium humile as primary consumers of cryptomonads, revealed a clear overclustering of mixotrophic / omnivorous species, and highlighted the role of Halteria / Pelagohalteria as important bacterivores. By contrast, time-lagged statistical approaches (like local similarity analyses, LSA proved to be inadequate for the evaluation of high-frequency sampling data. LSA led to a conspicuous inflation of significant associations, making it difficult to establish ecologically plausible interactions between ciliates and other microorganisms. Nevertheless, if adequate statistical procedures are selected, association networks can be powerful tools to formulate testable hypotheses about the autecology of only recently described ciliate species.
Effects of Phytoplankton Growth Phase on the Formation and Properties of Marine Snow

Science.gov (United States)

Montgomery, Q. W.; Proctor, K. W.; Prairie, J. C.

2016-02-01

Marine snow aggregates often dominate carbon export from the upper mixed layer to the deep ocean. Thus, understanding the formation and the properties of these aggregates is essential to the study of the biological pump. Aggregate formation is determined by both the encounter rate and the stickiness of the particles that they are composed of. Stickiness of phytoplankton has been linked to production of transparent exopolymer particles (TEP), which has been previously shown to vary in concentration throughout different parts of the phytoplankton growth cycle. The objective of this study is to determine the effects of the growth phase of the diatom Thalassiosira weissflogii to both TEP production and the properties of the resulting aggregates produced. Cultures of T. weissflogii were stopped at separate phases of the phytoplankton growth curve and incubated in rotating cylindrical tanks to form aggregates. Aggregate properties such as size, density, and porosity were measured at the end of each period of roller incubation. Preliminary results describe little variation in the size of the aggregates formed from different parts of the growth phase, but show a significant effect of growth phase on aggregate density. Density is an important factor in the settling of marine aggregates. Therefore, variations in aggregate density during different growth phases may have large implications for the efficiency of the biological pump during different stages of a phytoplankton bloom. Further examination will be performed on the potential effects of TEP abundance on the properties of the aggregates formed at separate growth phases and the resulting implications for carbon flux.
Effects of a surfacing effluent plume on a coastal phytoplankton community

KAUST Repository

Reifel, Kristen M.

2013-06-01

Urban runoff and effluent discharge from heavily populated coastal areas can negatively impact water quality, beneficial uses, and coastal ecosystems. The planned release of treated wastewater (i.e. effluent) from the City of Los Angeles Hyperion Wastewater Treatment Plant, located in Playa del Rey, California, provided an opportunity to study the effects of an effluent discharge plume from its initial release until it could no longer be detected in the coastal ocean. Non-metric multi-dimensional scaling analysis of phytoplankton community structure revealed distinct community groups based on salinity, temperature, and CDOM concentration. Three dinoflagellates (Lingulodinium polyedrum, Cochlodinium sp., Akashiwo sanguinea) were dominant (together >50% abundance) prior to the diversion. Cochlodinium sp. became dominant (65-90% abundance) within newly surfaced wastewater, and A. sanguinea became dominant or co-dominant as the effluent plume aged and mixed with ambient coastal water. Localized blooms of Cochlodinium sp. and A. sanguinea (chlorophyll a up to 100mgm-3 and densities between 100 and 2000cellsmL-1) occurred 4-7 days after the diversion within the effluent plume. Although both Cochlodinium sp. and A. sanguinea have been occasionally reported from California waters, blooms of these species have only recently been observed along the California coast. Our work supports the hypothesis that effluent and urban runoff discharge can stimulate certain dinoflagellate blooms. All three dinoflagellates have similar ecophysiological characteristics; however, small differences in morphology, nutrient preferences, and environmental requirements may explain the shift in dinoflagellate composition. © 2013 Elsevier Ltd.
Nutrient and Phytoplankton Analysis of a Mediterranean Coastal Area

Science.gov (United States)

Sebastiá, M. T.; Rodilla, M.

2013-01-01

Identifying and quantifying the key anthropogenic nutrient input sources are essential to adopting management measures that can target input for maximum effect in controlling the phytoplankton biomass. In this study, three systems characterized by distinctive main nutrient sources were sampled along a Mediterranean coast transect. These sources were groundwater discharge in the Ahuir area, the Serpis river discharge in the Venecia area, and a submarine wastewater outfall 1,900 m from the coast. The study area includes factors considered important in determining a coastal area as a sensitive area: it has significant nutrient sources, tourism is a major source of income in the region, and it includes an area of high water residence time (Venecia area) which is affected by the harbor facilities and by wastewater discharges. We found that in the Ahuir and the submarine wastewater outfall areas, the effects of freshwater inputs were reduced because of a greater water exchange with the oligotrophic Mediterranean waters. On the other hand, in the Venecia area, the highest levels of nutrient concentration and phytoplankton biomass were attributed to the greatest water residence time. In this enclosed area, harmful dinoflagellates were detected ( Alexandrium sp. and Dinophysis caudata). If the planned enlargement of the Gandia Harbor proceeds, it may increase the vulnerability of this system and provide the proper conditions of confinement for the dinoflagellate blooms' development. Management measures should first target phosphorus inputs as this is the most potential-limiting nutrient in the Venecia area and comes from a point source that is easier to control. Finally, we recommend that harbor environmental management plans include regular monitoring of water quality in adjacent waters to identify adverse phytoplankton community changes.
Nutrient and phytoplankton analysis of a Mediterranean coastal area.

Science.gov (United States)

Sebastiá, M T; Rodilla, M

2013-01-01

Identifying and quantifying the key anthropogenic nutrient input sources are essential to adopting management measures that can target input for maximum effect in controlling the phytoplankton biomass. In this study, three systems characterized by distinctive main nutrient sources were sampled along a Mediterranean coast transect. These sources were groundwater discharge in the Ahuir area, the Serpis river discharge in the Venecia area, and a submarine wastewater outfall 1,900 m from the coast. The study area includes factors considered important in determining a coastal area as a sensitive area: it has significant nutrient sources, tourism is a major source of income in the region, and it includes an area of high water residence time (Venecia area) which is affected by the harbor facilities and by wastewater discharges. We found that in the Ahuir and the submarine wastewater outfall areas, the effects of freshwater inputs were reduced because of a greater water exchange with the oligotrophic Mediterranean waters. On the other hand, in the Venecia area, the highest levels of nutrient concentration and phytoplankton biomass were attributed to the greatest water residence time. In this enclosed area, harmful dinoflagellates were detected (Alexandrium sp. and Dinophysis caudata). If the planned enlargement of the Gandia Harbor proceeds, it may increase the vulnerability of this system and provide the proper conditions of confinement for the dinoflagellate blooms' development. Management measures should first target phosphorus inputs as this is the most potential-limiting nutrient in the Venecia area and comes from a point source that is easier to control. Finally, we recommend that harbor environmental management plans include regular monitoring of water quality in adjacent waters to identify adverse phytoplankton community changes.
Stirring of the northeast Atlantic spring bloom: A Lagrangian analysis based on multisatellite data

Science.gov (United States)

Lehahn, Y.; D'Ovidio, F.; LéVy, M.; Heifetz, E.

2007-08-01

The effect of the geostrophic stirring on phytoplankton variability during the northeast Atlantic spring bloom is studied by analyzing satellite derived surface chlorophyll, sea surface temperature, and sea surface height. The calculation of unstable manifolds is used as a diagnostic of the transport properties of the geostrophic velocity field (calculated from the sea surface height). We identify two mechanisms by which the geostrophic velocity field acts on chlorophyll patterns. The first mechanism is a direct effect of the horizontal transport on already formed chlorophyll. By acting as "sticking" transport barriers, the unstable manifolds are shown to (1) modulate the fronts of already formed phytoplankton in lobular structures, (2) create spiralling chlorophyll anomalies within eddies, and (3) produce chlorophyll filaments. The second mechanism is an indirect effect on in situ chlorophyll production mediated by nutrient upwelling. Supported by a recent study on the vertical velocities of the northeast Atlantic (Legal et al., 2006), we argue that the horizontal unstable manifolds also shape the filamentary, vertical velocity cells, and hence the patterns of in situ produced chlorophyll through submesoscale vertical nutrient injection.
The extended Kalman filter for forecast of algal bloom dynamics.

Science.gov (United States)

Mao, J Q; Lee, Joseph H W; Choi, K W

2009-09-01

A deterministic ecosystem model is combined with an extended Kalman filter (EKF) to produce short term forecasts of algal bloom and dissolved oxygen dynamics in a marine fish culture zone (FCZ). The weakly flushed FCZ is modelled as a well-mixed system; the tidal exchange with the outer bay is lumped into a flushing rate that is numerically determined from a three-dimensional hydrodynamic model. The ecosystem model incorporates phytoplankton growth kinetics, nutrient uptake, photosynthetic production, nutrient sources from organic fish farm loads, and nutrient exchange with a sediment bed layer. High frequency field observations of chlorophyll, dissolved oxygen (DO) and hydro-meteorological parameters (sampling interval Deltat=1 day, 2h, 1h, respectively) and bi-weekly nutrient data are assimilated into the model to produce the combined state estimate accounting for the uncertainties. In addition to the water quality state variables, the EKF incorporates dynamic estimation of algal growth rate and settling velocity. The effectiveness of the EKF data assimilation is studied for a wide range of sampling intervals and prediction lead-times. The chlorophyll and dissolved oxygen estimated by the EKF are compared with field data of seven algal bloom events observed at Lamma Island, Hong Kong. The results show that the EKF estimate well captures the nonlinear error evolution in time; the chlorophyll level can be satisfactorily predicted by the filtered model estimate with a mean absolute error of around 1-2 microg/L. Predictions with 1-2 day lead-time are highly correlated with the observations (r=0.7-0.9); the correlation stays at a high level for a lead-time of 3 days (r=0.6-0.7). Estimated algal growth and settling rates are in accord with field observations; the more frequent DO data can compensate for less frequent algal biomass measurements. The present study is the first time the EKF is successfully applied to forecast an entire algal bloom cycle, suggesting the
Dynamics of cyanobacterial bloom formation during short-term hydrodynamic fluctuation in a large shallow, eutrophic, and wind-exposed Lake Taihu, China.

Science.gov (United States)

Wu, Tingfeng; Qin, Boqiang; Zhu, Guangwei; Luo, Liancong; Ding, Yanqing; Bian, Geya

2013-12-01

Short-term hydrodynamic fluctuations caused by extreme weather events are expected to increase worldwide because of global climate change, and such fluctuations can strongly influence cyanobacterial blooms. In this study, the cyanobacterial bloom disappearance and reappearance in Lake Taihu, China, in response to short-term hydrodynamic fluctuations, was investigated by field sampling, long-term ecological records, high-frequency sensors and MODIS satellite images. The horizontal drift caused by the dominant easterly wind during the phytoplankton growth season was mainly responsible for cyanobacterial biomass accumulation in the western and northern regions of the lake and subsequent bloom formation over relatively long time scales. The cyanobacterial bloom changed slowly under calm or gentle wind conditions. In contrast, the short-term bloom events within a day were mainly caused by entrainment and disentrainment of cyanobacterial colonies by wind-induced hydrodynamics. Observation of a westerly event in Lake Taihu revealed that when the 30 min mean wind speed (flow speed) exceeded the threshold value of 6 m/s (5.7 cm/s), cyanobacteria in colonies were entrained by the wind-induced hydrodynamics. Subsequently, the vertical migration of cyanobacterial colonies was controlled by hydrodynamics, resulting in thorough mixing of algal biomass throughout the water depth and the eventual disappearance of surface blooms. Moreover, the intense mixing can also increase the chance for forming larger and more cyanobacterial colonies, namely, aggregation. Subsequently, when the hydrodynamics became weak, the cyanobacterial colonies continuously float upward without effective buoyancy regulation, and cause cyanobacterial bloom explosive expansion after the westerly. Furthermore, the results of this study indicate that the strong wind happening frequently during April and October can be an important cause of the formation and expansion of cyanobacterial blooms in Lake Taihu.
Phytoplankton of the Boguchany reservoir in 2016-2017 at the stations in front of the hydroelectric dam

Directory of Open Access Journals (Sweden)

M. V. Usoltseva

2017-12-01

Full Text Available The species structure and seasonal dynamics of the phytoplankton of the dam area of the Boguchany Reservoir were studied in the first years of operation of the hydroelectric power station in 2016-2017. Two peaks of algal bloom are noted in spring and summer. Mass species were: diatom Stephanodiscus minutulus and dinophyte Gymnodinium baicalense in spring; diatoms Asterionella formosa and Fragilaria crotonensis, blue-green Dolichospermum lemmermannii, D. flosaquae, D. flosaquae f. spiroides and Aphanizomenon flosaquae; green Sphaerocystis planctonica and dinophyte Ceratium hirundinella in summer; diatoms F. crotonensis and A. formosa, cryptophytic Rhodomonas pusilla and Cryptomonas ovata in autumn. The cryptophyte R. pusilla and the Cryptomonas species were dominated under the ice. The maximum number of phytoplankton (9 million cells in liter was recorded in the spring. According to the indixes of saprobity, the purity of water corresponded to II-III quality classes (pure and moderately polluted water.
Promotion Effect of Asian Dust on Phytoplankton Growth and Potential Dissolved Organic Phosphorus Utilization in the South China Sea

Science.gov (United States)

Chu, Qiang; Liu, Ying; Shi, Jie; Zhang, Chao; Gong, Xiang; Yao, Xiaohong; Guo, Xinyu; Gao, Huiwang

2018-03-01

Dust deposition is an important nutrient source to the South China Sea (SCS), but few in situ experiments were conducted on phytoplankton response to the deposition. We conducted onboard incubation experiments at three stations near Luzon Strait in the SCS, with addition of multiple dissolved inorganic nutrients, Asian dust, and rainwater. From our results, nitrogen and phosphorus were both urgently needed for phytoplankton growth in the SCS, indicated by the evident Chl a response to the addition of nitrogen and phosphorus together. Almost no evident response was observed by adding phosphorus or iron alone to incubation waters, although a delayed response of Chl a in mass concentration was observed by adding nitrogen alone. The latter implied a possible utilization of dissolved organic phosphorus because of insufficient dissolved inorganic phosphorus in incubation waters. Under such nutrient condition, Asian dust showed an apparent promotion effect on phytoplankton growth by providing sufficient amounts of nitrogen but low phosphorus. Meanwhile, it was found that large sized (> 5 μm) phytoplankton community showed different responses to dust addition at different stations. At stations A3 and A6, Chaetoceros spp. became the dominant species during the bloom period, while at station WG2, Nitzschia spp. became dominant. In combination with different initial nutrients and Chl a levels at the three stations, the different phytoplankton community evolution implied the response difference to external inputs between oligotrophic (stations A3 and A6) and ultraoligotrophic (station WG2) conditions in the SCS.
Pan genome of the phytoplankton Emiliania underpins its global distribution.

Science.gov (United States)

Read, Betsy A; Kegel, Jessica; Klute, Mary J; Kuo, Alan; Lefebvre, Stephane C; Maumus, Florian; Mayer, Christoph; Miller, John; Monier, Adam; Salamov, Asaf; Young, Jeremy; Aguilar, Maria; Claverie, Jean-Michel; Frickenhaus, Stephan; Gonzalez, Karina; Herman, Emily K; Lin, Yao-Cheng; Napier, Johnathan; Ogata, Hiroyuki; Sarno, Analissa F; Shmutz, Jeremy; Schroeder, Declan; de Vargas, Colomban; Verret, Frederic; von Dassow, Peter; Valentin, Klaus; Van de Peer, Yves; Wheeler, Glen; Dacks, Joel B; Delwiche, Charles F; Dyhrman, Sonya T; Glöckner, Gernot; John, Uwe; Richards, Thomas; Worden, Alexandra Z; Zhang, Xiaoyu; Grigoriev, Igor V

2013-07-11

Coccolithophores have influenced the global climate for over 200 million years. These marine phytoplankton can account for 20 per cent of total carbon fixation in some systems. They form blooms that can occupy hundreds of thousands of square kilometres and are distinguished by their elegantly sculpted calcium carbonate exoskeletons (coccoliths), rendering them visible from space. Although coccolithophores export carbon in the form of organic matter and calcite to the sea floor, they also release CO2 in the calcification process. Hence, they have a complex influence on the carbon cycle, driving either CO2 production or uptake, sequestration and export to the deep ocean. Here we report the first haptophyte reference genome, from the coccolithophore Emiliania huxleyi strain CCMP1516, and sequences from 13 additional isolates. Our analyses reveal a pan genome (core genes plus genes distributed variably between strains) probably supported by an atypical complement of repetitive sequence in the genome. Comparisons across strains demonstrate that E. huxleyi, which has long been considered a single species, harbours extensive genome variability reflected in different metabolic repertoires. Genome variability within this species complex seems to underpin its capacity both to thrive in habitats ranging from the equator to the subarctic and to form large-scale episodic blooms under a wide variety of environmental conditions.
A comparison of ship and Coastal Zone Color Scanner mapped distribution of phytoplankton in the southeastern Bering Sea

Science.gov (United States)

Mcclain, C. R.; Sambrotto, R. N.; Ray, G. C.; Muller-Karger, F. E.

1990-01-01

Twenty-one Coastal Zone Color Scanner (CZCS) images of the southeastern Bering Sea are examined in order to map the near-surface distribution of phytoplankton during 1979 and 1980. The information is compared with the mesoscale (100-1000 km) distribution of phytoplankton inferred from pooled ship sampling obtained during the Processes and Resources of the Bering Shelf (PROBES) intensive field study during the late 1970s and early 1980s. The imagery indicates that open-water phytoplankton blooms occur first in late April in coastal waters, peak in early May over the middle shelf, and decay rapidly afterwards, reaching concentration minima in June in both regions. These patterns show that the earlier ship observations are valid for most of the eastern Bering shelf. A very tight correlation is found between the PROBES surface chlorophyll a concentrations and mean mixed-layer chlorophyll concentrations. The significant discrepancies between CZCS and ship-based chlorophyll estimates may be due to aliasing in time by the CZCS. It is concluded that neither satellite nor ship alone can do an adequate job of characterizing the physics or biological dynamics of the ocean.
Spatial dynamics of a nutrient-phytoplankton system with toxic effect on phytoplankton.

Science.gov (United States)

Chakraborty, Subhendu; Tiwari, P K; Misra, A K; Chattopadhyay, J

2015-06-01

The production of toxins by some species of phytoplankton is known to have several economic, ecological, and human health impacts. However, the role of toxins on the spatial distribution of phytoplankton is not well understood. In the present study, the spatial dynamics of a nutrient-phytoplankton system with toxic effect on phytoplankton is investigated. We analyze the linear stability of the system and obtain the condition for Turing instability. In the presence of toxic effect, we find that the distribution of nutrient and phytoplankton becomes inhomogeneous in space and results in different patterns, like stripes, spots, and the mixture of them depending on the toxicity level. We also observe that the distribution of nutrient and phytoplankton shows spatiotemporal oscillation for certain toxicity level. Copyright © 2015 Elsevier Inc. All rights reserved.
Satellite and ship studies of phytoplankton in the Northeastern Arabian during 2000 – 2006 period

Digital Repository Service at National Institute of Oceanography (India)

Matondkar, S.G.P.; Dwivedi, R.M.; Parab, S.G.; Pednekar, S.; Desa, E.S.; Mascarenhas, A.A.M.Q.; Raman, M.; Singh, S.K.

month (fall intermonsoon) average chlorophyll a (Chl a) by fluorometer was (0.799 mgm-3) and by OCM it was 0.584 mgm-3. The higher chlorophyll a observed was due to Trichodesmium (cyanobacteria) blooms. During December the average chlorophyll a was 0...
Volcanism, Iron, and Phytoplankton in the Heard and McDonald Islands Region, Southern Indian Ocean

Science.gov (United States)

Coffin, M. F.; Arculus, R. J.; Bowie, A. R.; Chase, Z.; Robertson, R.; Trull, T. W.; Heobi in2016 v01 Shipboard Party, T.

2016-12-01

Phytoplankton supply approximately half of the oxygen in Earth's atmosphere, and iron supply limits the growth of phytoplankton in the anemic Southern Ocean. Situated entirely within the Indian Ocean sector of the Southern Ocean are Australia's only active subaerial volcanoes, Heard and McDonald islands (HIMI) on the central Kerguelen Plateau, a large igneous province. Widespread fields of submarine volcanoes, some of which may be active, extend for distances of up to several hundred kilometers from the islands. The predominantly eastward-flowing Antarctic Circumpolar Current sweeps across the central Kerguelen Plateau, and extensive blooms of phytoplankton are observed on the Plateau down-current of HIMI. The goal of RV Investigator voyage IN2016_V01, conducted in January/February 2016, is to test the hypothesis that hydrothermal fluids, which cool active submarine volcanoes in the HIMI region, ascend from the seafloor and fertilise surface waters with iron, thereby enhancing biological productivity beginning with phytoplankton. Significant initial shipboard results include: Documentation, for the first time, of the role of active HIMI and nearby submarine volcanoes in supplying iron to the Southern Ocean. Nearshore waters had elevated dissolved iron levels. Although biomass was not correspondingly elevated, fluorescence induction data indicated highly productive resident phytoplankton. Discovery of >200 acoustic plumes emanating from the seafloor and ascending up to tens of meters into the water column near HIMI. Deep tow camera footage shows bubbles rising from the seafloor in an acoustic plume field north of Heard Island. Mapping 1,000 km2 of uncharted seafloor around HIMI. Submarine volcanic edifices punctuate the adjacent seafloor, and yielded iron-rich rocks similar to those found on HIMI, respectively. Acoustic plumes emanating from some of these features suggest active seafloor hydrothermal systems.
Alterations in Location, Magnitude, and Community Composition of Discrete Layers of Phytoplankton in Cold, Deep Waters Near the 1% Isolume of the Laurentian Great Lake Michigan Among Years With Dramatically Different Meteorological Conditions

Science.gov (United States)

Cuhel, R. L.; Aguilar, C.

2016-02-01

Phytoplankton deep populations have dominated both biomass and productivity in deep basins of Lake Michigan for much of the anthropocene. In recent decades, chronically phosphorus-deficient waters have progressed from lower thermocline diatom assemblages in the 2000s to much deeper picocyanobacterial dominance in the late 2000s. Overwhelming establishment of benthic filter-feeding quagga mussels was instrumental in selection for picoplankton in the 2003-2007 time frame, but in 2008 a return to diatom dominance occurred in conjunction with monumental runoff from the Storm of the Century. Picoplankton gradually returned to significance in ensuing years, but suffered after lakewide ice cover and extremely slow spring warming of winters 2013-2015. Extremely calm summer conditions favored the picoplankton, and a decade of 1% light penetration of 50-60m has consistently enabled very deep productivity by several different divisions of algae. An unusual persistent south wind with basin-scale upwelling stimulated a return of fall diatom bloom for the first time in 2015. Repeated expeditions to offshore deep stations (100-150m) with detailed water sampling based on hydrographic observations often include thin peaks of biogenic silica (diatoms, chrysophytes) offset from one or more distinct layers of picocyanobacteria and mixed eucaryotic phytoplankton. In 2014 large, stable populations of the diatom Tabellaria sp. flourished at 50-60m with highly shade-adapted photosynthetic characteristics but assimilation numbers >1. In 2014-2015, picocyanobacterial maxima moved up in the water column and were dissociated from signals in either in vivo fluorescence or transmission. Physical structure, within-year basin physics sequence timing, and now seemingly ammonium availability may each contribute to phytoplankton ecology in this ocean-scale freshwater ecosystem.
Detection of a Planktothrix agardhii Bloom in Portuguese Marine Coastal Waters

Directory of Open Access Journals (Sweden)

Catarina Churro

2017-12-01

Full Text Available Cyanobacteria blooms are frequent in freshwaters and are responsible for water quality deterioration and human intoxication. Although, not a new phenomenon, concern exists on the increasing persistence, scale, and toxicity of these blooms. There is evidence, in recent years, of the transfer of these toxins from inland to marine waters through freshwater outflow. However, the true impact of these blooms in marine habitats has been overlooked. In the present work, we describe the detection of Planktothrix agardhii, which is a common microcystin producer, in the Portuguese marine coastal waters nearby a river outfall in an area used for shellfish harvesting and recreational activities. P. agardhii was first observed in November of 2016 in seawater samples that are in the scope of the national shellfish monitoring system. This occurrence was followed closely between November and December of 2016 by a weekly sampling of mussels and water from the sea pier and adjacent river mouth with salinity ranging from 35 to 3. High cell densities were found in the water from both sea pier and river outfall, reaching concentrations of 4,960,608 cells·L−1 and 6810.3 × 106 cells·L−1 respectively. Cultures were also established with success from the environment and microplate salinity growth assays showed that the isolates grew at salinity 10. HPLC-PDA analysis of total microcystin content in mussel tissue, water biomass, and P. agardhii cultures did not retrieve a positive result. In addition, microcystin related genes were not detected in the water nor cultures. So, the P. agardhii present in the environment was probably a non-toxic strain. This is, to our knowledge, the first report on a P. agardhii bloom reaching the sea and points to the relevance to also monitoring freshwater harmful phytoplankton and related toxins in seafood harvesting and recreational coastal areas, particularly under the influence of river plumes.
Seasonal and Inter-Annual Patterns of Chlorophyll and Phytoplankton Community Structure in Monterey Bay, CA Derived from AVIRIS Data During the 2013-2015 HyspIRI Airborne Campaign

Science.gov (United States)

Palacios, S. L.; Thompson, D. R.; Kudela, R. M.; Negrey, K.; Guild, L. S.; Gao, B. C.; Green, R. O.; Torres-Perez, J. L.

2016-02-01

There is a need in the ocean color community to discriminate among phytoplankton groups within the bulk chlorophyll pool to understand ocean biodiversity, track energy flow through ecosystems, and identify and monitor for harmful algal blooms. Imaging spectrometer measurements enable the use of sophisticated spectroscopic algorithms for applications such as differentiating among coral species and discriminating phytoplankton taxa. These advanced algorithms rely on the fine scale, subtle spectral shape of the atmospherically corrected remote sensing reflectance (Rrs) spectrum of the ocean surface. Consequently, these algorithms are sensitive to inaccuracies in the retrieved Rrs spectrum that may be related to the presence of nearby clouds, inadequate sensor calibration, low sensor signal-to-noise ratio, glint correction, and atmospheric correction. For the HyspIRI Airborne Campaign, flight planning considered optimal weather conditions to avoid flights with significant cloud/fog cover. Although best suited for terrestrial targets, the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) has enough signal for some coastal chlorophyll algorithms and meets sufficient calibration requirements for most channels. The coastal marine environment has special atmospheric correction needs due to error introduced by aerosols and terrestrially sourced atmospheric dust and riverine sediment plumes. For this HyspIRI campaign, careful attention has been given to the correction of AVIRIS imagery of the Monterey Bay to optimize ocean Rrs retrievals to estimate chlorophyll (OC3) and phytoplankton functional type (PHYDOTax) data products. This new correction method has been applied to several image collection dates during two oceanographic seasons in 2013 and 2014. These two periods are dominated by either diatom blooms or red tides. Results to be presented include chlorophyll and phytoplankton community structure and in-water validation data for these dates during the two seasons.
Cyanobacterial carbon concentrating mechanisms facilitate sustained CO2 depletion in eutrophic lakes

Science.gov (United States)

Morales-Williams, Ana M.; Wanamaker, Alan D., Jr.; Downing, John A.

2017-06-01

Phytoplankton blooms are increasing in frequency, intensity, and duration in aquatic ecosystems worldwide. In many eutrophic lakes, these high levels of primary productivity correspond to periods of CO2 depletion in surface waters. Cyanobacteria and other groups of phytoplankton have the ability to actively transport bicarbonate (HCO3-) across their cell membrane when CO2 concentrations are limiting, possibly giving them a competitive advantage over algae not using carbon concentrating mechanisms (CCMs). To investigate whether CCMs can maintain phytoplankton bloom biomass under CO2 depletion, we measured the δ13C signatures of dissolved inorganic carbon (δ13CDIC) and phytoplankton particulate organic carbon (δ13Cphyto) in 16 mesotrophic to hypereutrophic lakes during the ice-free season of 2012. We used mass-balance relationships to determine the dominant inorganic carbon species used by phytoplankton under CO2 stress. We found a significant positive relationship between phytoplankton biomass and phytoplankton δ13C signatures as well as a significant nonlinear negative relationship between water column ρCO2 and isotopic composition of phytoplankton, indicating a shift from diffusive uptake to active uptake by phytoplankton of CO2 or HCO3- during blooms. Calculated photosynthetic fractionation factors indicated that this shift occurs specifically when surface water CO2 drops below atmospheric equilibrium. Our results indicate that active HCO3- uptake via CCMs may be an important mechanism in maintaining phytoplankton blooms when CO2 is depleted. Further increases in anthropogenic pressure, eutrophication, and cyanobacteria blooms are therefore expected to contribute to increased bicarbonate uptake to sustain primary production.

Cyanobacterial carbon concentrating mechanisms facilitate sustained CO2 depletion in eutrophic lakes

Directory of Open Access Journals (Sweden)

A. M. Morales-Williams

2017-06-01

Full Text Available Phytoplankton blooms are increasing in frequency, intensity, and duration in aquatic ecosystems worldwide. In many eutrophic lakes, these high levels of primary productivity correspond to periods of CO2 depletion in surface waters. Cyanobacteria and other groups of phytoplankton have the ability to actively transport bicarbonate (HCO3− across their cell membrane when CO2 concentrations are limiting, possibly giving them a competitive advantage over algae not using carbon concentrating mechanisms (CCMs. To investigate whether CCMs can maintain phytoplankton bloom biomass under CO2 depletion, we measured the δ13C signatures of dissolved inorganic carbon (δ13CDIC and phytoplankton particulate organic carbon (δ13Cphyto in 16 mesotrophic to hypereutrophic lakes during the ice-free season of 2012. We used mass–balance relationships to determine the dominant inorganic carbon species used by phytoplankton under CO2 stress. We found a significant positive relationship between phytoplankton biomass and phytoplankton δ13C signatures as well as a significant nonlinear negative relationship between water column ρCO2 and isotopic composition of phytoplankton, indicating a shift from diffusive uptake to active uptake by phytoplankton of CO2 or HCO3− during blooms. Calculated photosynthetic fractionation factors indicated that this shift occurs specifically when surface water CO2 drops below atmospheric equilibrium. Our results indicate that active HCO3− uptake via CCMs may be an important mechanism in maintaining phytoplankton blooms when CO2 is depleted. Further increases in anthropogenic pressure, eutrophication, and cyanobacteria blooms are therefore expected to contribute to increased bicarbonate uptake to sustain primary production.
Phytoplankton biomass and composition in a well-flushed, sub-tropical estuary: The contrasting effects of hydrology, nutrient loads and allochthonous influences.

Science.gov (United States)

Hart, J A; Phlips, E J; Badylak, S; Dix, N; Petrinec, K; Mathews, A L; Green, W; Srifa, A

2015-12-01

The primary objective of this study was to examine trends in phytoplankton biomass and species composition under varying nutrient load and hydrologic regimes in the Guana Tolomato Matanzas estuary (GTM), a well-flushed sub-tropical estuary located on the northeast coast of Florida. The GTM contains both regions of significant human influence and pristine areas with only modest development, providing a test case for comparing and contrasting phytoplankton community dynamics under varying degrees of nutrient load. Water temperature, salinity, Secchi disk depth, nutrient concentrations and chlorophyll concentrations were determined on a monthly basis from 2002 to 2012 at three representative sampling sites in the GTM. In addition, microscopic analyses of phytoplankton assemblages were carried out monthly for a five year period from 2005 through 2009 at all three sites. Results of this study indicate that phytoplankton biomass and composition in the GTM are strongly influenced by hydrologic factors, such as water residence times and tidal exchanges of coastal waters, which in turn are affected by shifts in climatic conditions, most prominently rainfall levels. These influences are exemplified by the observation that the region of the GTM with the longest water residence times but lowest nutrient loads exhibited the highest phytoplankton peaks of autochthonous origin. The incursion of a coastal bloom of the toxic dinoflagellate Karenia brevis into the GTM in 2007 demonstrates the potential importance of allochthonous influences on the ecosystem. Copyright © 2015 Elsevier Ltd. All rights reserved.
Toxic cyanobacteria strains isolated from blooms in the Guadiana River (southwestern Spain

Directory of Open Access Journals (Sweden)

ISABEL M MORENO

2004-01-01

Full Text Available This paper describes the occurrence of toxic cyanobacteria along the Guadiana River over its course between Mérida and Badajoz (Extremadura, Spain. Water sampling for phytoplankton quantification and toxin analysis was carried out regularly between 1999 and 2001 in six different locations, including two shallow, slow-flowing river sites, two streamed river sites and two drinking water reservoirs. The cyanobacterial community differed significantly between these locations, especially during the summer. The predominant genera were Microcystis, Oscillatoria, Aphanizomenon and Anabaena. Using an ELISA assay the total microcystin contents of natural water samples from the most eutrophic locations ranged from 0.10 _ 21.86 mg mcyst-LR equivalent·L-1 in Valdelacalzada and 0.10-11.3 µg mcyst-LR equivalent·L-1 in Vitonogales, and a seasonal variation of toxin content was observed. The amount of microcystins produced by each strain was determined by ELISA assay and the detection and identification of microcystin variants of three toxic strains of Microcystis aeruginosa was performed by high performance liquid chromatography (HPLC. The analysis of microcystins of the cultured strains revealed that toxin production was variable among different strains of M. aeruginosa isolated either from different blooms or from the same bloom.
Advanced characterization of dissolved organic matter released by bloom-forming marine algae

KAUST Repository

Rehman, Zahid Ur

2017-06-01

Algal organic matter (AOM), produced by marine phytoplankton during bloom periods, may adversely affect the performance of membrane processes in seawater desalination. The polysaccharide fraction of AOM has been related to (bio)fouling in micro-filtration and ultrafiltration, and reverse osmosis membranes. However, so far, the chemical structure of the polysaccharides released by bloom-forming algae is not well understood. In this study, dissolved fraction of AOM produced by three algal species (Chaetoceros affinis, Nitzschia epithemoides and Hymenomonas spp.) was characterized using liquid chromatography–organic carbon detection (LC-OCD) and fluorescence spectroscopy. Chemical structure of polysaccharides isolated from the AOM solutions at stationary phase was analyzed using proton nuclear magnetic resonance (H-NMR). The results showed that production and composition of dissolved AOM varied depending on algal species and their growth stage. AOM was mainly composed of biopolymers (BP; i.e., polysaccharides and proteins [PN]), but some refractory substances were also present.H-NMR spectra confirmed the predominance of carbohydrates in all samples. Furthermore, similar fingerprints were observed for polysaccharides of two diatom species, which differed considerably from that of coccolithophores. Based on the findings of this study,H-NMR could be used as a method for analyzing chemical profiles of algal polysaccharides to enhance the understanding of their impact on membrane fouling.
Dissection of Microbial Community Functions during a Cyanobacterial Bloom in the Baltic Sea via Metatranscriptomics

Directory of Open Access Journals (Sweden)

Carlo Berg

2018-02-01

Full Text Available Marine and brackish surface waters are highly dynamic habitats that undergo repeated seasonal variations in microbial community composition and function throughout time. While succession of the various microbial groups has been well investigated, little is known about the underlying gene-expression of the microbial community. We investigated microbial interactions via metatranscriptomics over a spring to fall seasonal cycle in the brackish Baltic Sea surface waters, a temperate brackish water ecosystem periodically promoting massive cyanobacterial blooms, which have implications for primary production, nutrient cycling, and expansion of hypoxic zones. Network analysis of the gene expression of all microbes from 0.22 to 200 μm in size and of the major taxonomic groups dissected the seasonal cycle into four components that comprised genes peaking during different periods of the bloom. Photoautotrophic nitrogen-fixing Cyanobacteria displayed the highest connectivity among the microbes, in contrast to chemoautotrophic ammonia-oxidizing Thaumarchaeota, while heterotrophs dominated connectivity among pre- and post-bloom peaking genes. The network was also composed of distinct functional connectivities, with an early season balance between carbon metabolism and ATP synthesis shifting to a dominance of ATP synthesis during the bloom, while carbon degradation, specifically through the glyoxylate shunt, characterized the post-bloom period, driven by Alphaproteobacteria as well as by Gammaproteobacteria of the SAR86 and SAR92 clusters. Our study stresses the exceptionally strong biotic driving force executed by cyanobacterial blooms on associated microbial communities in the Baltic Sea and highlights the impact cyanobacterial blooms have on functional microbial community composition.
Open-ocean convection process: A driver of the winter nutrient supply and the spring phytoplankton distribution in the Northwestern Mediterranean Sea

Science.gov (United States)

Severin, Tatiana; Kessouri, Faycal; Rembauville, Mathieu; Sánchez-Pérez, Elvia Denisse; Oriol, Louise; Caparros, Jocelyne; Pujo-Pay, Mireille; Ghiglione, Jean-François; D'Ortenzio, Fabrizio; Taillandier, Vincent; Mayot, Nicolas; Durrieu De Madron, Xavier; Ulses, Caroline; Estournel, Claude; Conan, Pascal

2017-06-01

This study was a part of the DeWEX project (Deep Water formation Experiment), designed to better understand the impact of dense water formation on the marine biogeochemical cycles. Here, nutrient and phytoplankton vertical and horizontal distributions were investigated during a deep open-ocean convection event and during the following spring bloom in the Northwestern Mediterranean Sea (NWM). In February 2013, the deep convection event established a surface nutrient gradient from the center of the deep convection patch to the surrounding mixed and stratified areas. In the center of the convection area, a slight but significant difference of nitrate, phosphate and silicate concentrations was observed possibly due to the different volume of deep waters included in the mixing or to the sediment resuspension occurring where the mixing reached the bottom. One of this process, or a combination of both, enriched the water column in silicate and phosphate, and altered significantly the stoichiometry in the center of the deep convection area. This alteration favored the local development of microphytoplankton in spring, while nanophytoplankton dominated neighboring locations where the convection reached the deep layer but not the bottom. This study shows that the convection process influences both winter nutrients distribution and spring phytoplankton distribution and community structure. Modifications of the convection's spatial scale and intensity (i.e., convective mixing depth) are likely to have strong consequences on phytoplankton community structure and distribution in the NWM, and thus on the marine food web.Plain Language SummaryThe deep open-ocean convection in the Northwestern Mediterranean Sea is an important process for the formation and the circulation of the deep waters of the entire Mediterranean Sea, but also for the local spring phytoplankton bloom. In this study, we showed that variations of the convective mixing depth induced different supply in nitrate
Pan Genome of the Phytoplankton Emiliania Underpins its Global Distribution

Energy Technology Data Exchange (ETDEWEB)

Read, Betsy A. [California State Univ. (CalState), San Marcos, CA (United States); Kegel, Jessica [Alfred Wegener Inst. for Polar and Marine Research, Bremerhaven (Germany); Klute, Mary J. [Univ. of Alberta, Edmonton, AB (Canada); Kuo, Alan [USDOE Joint Genome Inst., Walnut Creek, CA (United States); Lefebvre, Stephane C. [J. Craig Venter Inst., San Diego, CA (United States); Maumus, Florian [National Institute of Agricultural Research, Versailles (France); Mayer, Christoph [Alexander Koenig Research Museum, Bonn (Germany); Ruhr Univ., Bochum (Germany); Miller, John [Univ. of Maryland, College Park, MD (United States); Monier, Adam [Monterey Bay Aquarium Research Inst., Moss Landing, CA (United States); Salamov, Asaf [USDOE Joint Genome Inst., Walnut Creek, CA (United States); Young, Jeremy [Univ. College London (United Kingdom); Aguilar, Maria [Univ. of Alberta, Edmonton, AB (Canada); Claverie, Jean-Michel [Aix-Marseille Univ. (France); Frickenhaus, Stephan [Alfred Wegener Inst. for Polar and Marine Research, Bremerhaven (Germany); Univ. of Bremerhaven (Germany); Gonzalez, Karina [Harvard Medical School, Boston, MA (United States); Herman, Emily K. [Univ. of Alberta, Edmonton, AB (Canada); Lin, Yao-Cheng [Ghent Univ. (Belgium); Napier, Johnathan [Rothamstead Research, Harpenden (United Kingdom); Ogata, Hiroyuki [Aix-Marseille Univ. (France); Sarno, Analissa F. [California State Univ. (CalState), San Marcos, CA (United States); Schmutz, Jeremy [USDOE Joint Genome Inst., Walnut Creek, CA (United States); HudsonAlpha Genome Sequencing Center, Huntsville, AL (United States); Schroeder, Declan [Marine Biological Association of the UK, Plymouth (United Kingdom); de Vargas, Columban [CNRS. Univ. Pierre and Marie Curie (France).; Verret, Frederic [Univ. of Essex, Colchester (United Kingdom); von Dassow, Peter [Pontifical Catholic University of Chile, Santiago (Chile); Valentin, Klaus [Alfred Wegener Inst. for Polar and Marine Research, Bremerhaven (Germany); Van de Peer, Yves [Ghent Univ. (Belgium); Wheeler, Glen [Marine Biological Association of the UK, Plymouth (United Kingdom); Plymouth Marine Lab. (United Kingdom); Annotation Consortium, Emiliania huxleyi; Dacks, Joel B. [Univ. of Alberta, Edmonton, AB (Canada); Delwiche, Charles F. [Univ. of Maryland, College Park, MD (United States); Dyhrman, Sonya T. [Woods Hole Oceanographic Inst., MA (United States); Columbia Univ., Palisades, NY (United States); Glockner, Gernot [Univ. of Cologne (Germany); John, Uwe [Alfred Wegener Inst. for Polar and Marine Research, Bremerhaven (Germany); Richards, Thomas [National History Museum, London (United Kingdom); Worden, Alexandra Z. [Monterey Bay Aquarium Research Inst., Moss Landing, CA (United States); Zhang, Xiaoyu [California State Univ. (CalState), San Marcos, CA (United States); Grigoriev, Igor V. [USDOE Joint Genome Inst., Walnut Creek, CA (United States)

2012-06-18

Coccolithophores have influenced the global climate for over 200 million years1. These marine phytoplankton can account for 20 per cent of total carbon fixation in some systems2. They form blooms that can occupy hundreds of thousands of square kilometres and are distinguished by their elegantly sculpted calcium carbonate exoskeletons (coccoliths), rendering themvisible fromspace3.Although coccolithophores export carbon in the form of organic matter and calcite to the sea floor, they also release CO₂ in the calcification process. Hence, they have a complex influence on the carbon cycle, driving either CO₂ production or uptake, sequestration and export to the deep ocean4. Here we report the first haptophyte reference genome, from the coccolithophore Emiliania huxleyi strain CCMP1516, and sequences from 13 additional isolates. Our analyses reveal a pan genome (core genes plus genes distributed variably between strains) probably supported by an atypical complement of repetitive sequence in the genome. Comparisons across strains demonstrate thatE. huxleyi, which has long been considered a single species, harbours extensive genome variability reflected in different metabolic repertoires. Genome variability within this species complex seems to underpin its capacity both to thrive in habitats ranging from the equator to the subarctic and to form large-scale episodic blooms under a wide variety of environmental conditions.
Effect of toxic substance on delayed competitive allelopathic phytoplankton system with varying parameters through stability and bifurcation analysis

International Nuclear Information System (INIS)

Pal, D.; Mahapatra, G.S.

2016-01-01

Highlights: • We study a delayed two species competitive system with imprecise biological parameters. • We consider impreciseness in the form of interval number. • We introduce parametric functional form of interval number to study the model. • We study the effect of toxicant and time delay under impreciseness. • We discuss the chaotic behavior of the model. - Abstract: We have studied the combined effect of toxicant and fluctuation of the biological parameters on the dynamical behaviors of a delayed two-species competitive system with imprecise biological parameters. Due to the global increase of harmful phytoplankton blooms, the study of dynamic interactions between two competing phytoplankton species in the presence of toxic substances is an active field of research now days. The ordinary mathematical formulation of models for two competing phytoplankton species, when one or both the species liberate toxic substances, is unable to capture the oscillatory and highly variable growth of phytoplankton populations. The deterministic model never predicts the sudden localized behavior of certain species. These obstacles of mathematical modeling can be overcomed if we include interval variability of biological parameters in our modeling approach. In this investigation, we construct imprecise models of allelopathic interactions between two competing phytoplankton species as a parametric differential equation model. We incorporate the effect of toxicant on the species in two different cases known as toxic inhibition and toxic stimulatory system. We have discussed the existence of various equilibrium points and stability of the system at these equilibrium points. In case of toxic stimulatory system, the delay model exhibits a stable limit cycle oscillation. Analytical findings are supported through exhaustive numerical simulations.
Phytoplankton and Climate

Science.gov (United States)

Moisan, John R.

2009-01-01

Ocean phytoplankton supply about half of the oxygen that humans utilize to sustain life. In this lecture, we will explore how phytoplankton plays a critical role in modulating the Earth's climate. These tiny organisms are the base of the Ocean's food web. They can modulate the rate at which solar heat is absorbed by the ocean, either through direct absorption or through production of highly scattering cellular coverings. They take up and help sequester carbon dioxide, a key greenhouse gas that modulated the Earth's climate. They are the source of cloud nucleation gases that are key to cloud formation/processes. They are also able to modify the nutrient budgets of the ocean through active uptake of inert atmospheric nitrogen. Climate variations have a pronounced impact on phytoplankton dynamics. Long term variations in the climate have been studied through geological interpretations on its influence on phytoplankton populations. The presentation will focus on presenting the numerous linkages that have been observed between climate and phytoplankton and further discuss how present climate change scenarios are likely to impact phytoplankton populations as well as present findings from several studies that have tried to understand how the climate might react to the feedbacks from these numerous climate-phytop|ankton linkages.
Assimilating bio-optical glider data during a phytoplankton bloom in the southern Ross Sea

Science.gov (United States)

Kaufman, Daniel E.; Friedrichs, Marjorie A. M.; Hemmings, John C. P.; Smith, Walker O., Jr.

2018-01-01

The Ross Sea is a region characterized by high primary productivity in comparison to other Antarctic coastal regions, and its productivity is marked by considerable variability both spatially (1-50 km) and temporally (days to weeks). This variability presents a challenge for inferring phytoplankton dynamics from observations that are limited in time or space, which is often the case due to logistical limitations of sampling. To better understand the spatiotemporal variability in Ross Sea phytoplankton dynamics and to determine how restricted sampling may skew dynamical interpretations, high-resolution bio-optical glider measurements were assimilated into a one-dimensional biogeochemical model adapted for the Ross Sea. The assimilation of data from the entire glider track using the micro-genetic and local search algorithms in the Marine Model Optimization Testbed improves the model-data fit by ˜ 50 %, generating rates of integrated primary production of 104 g C m-2 yr-1 and export at 200 m of 27 g C m-2 yr-1. Assimilating glider data from three different latitudinal bands and three different longitudinal bands results in minimal changes to the simulations, improves the model-data fit with respect to unassimilated data by ˜ 35 %, and confirms that analyzing these glider observations as a time series via a one-dimensional model is reasonable on these scales. Whereas assimilating the full glider data set produces well-constrained simulations, assimilating subsampled glider data at a frequency consistent with cruise-based sampling results in a wide range of primary production and export estimates. These estimates depend strongly on the timing of the assimilated observations, due to the presence of high mesoscale variability in this region. Assimilating surface glider data subsampled at a frequency consistent with available satellite-derived data results in 40 % lower carbon export, primarily resulting from optimized rates generating more slowly sinking diatoms. This
Harmful algal blooms

Digital Repository Service at National Institute of Oceanography (India)

Bhat, S.R.; PrabhaDevi; DeSouza, L.; Verlecar, X.N.; Naik, C.G.

as harmful algal bloom. Bloom formation is a natural process and it enhances biological productivity, but turns worrisome when caused by toxic species, leading to massive fish mortalities and hazards to human health. Incidences of'red tide' are increasing...
A new bio-optical algorithm for the remote sensing of algal blooms in complex ocean waters

Science.gov (United States)

Shanmugam, Palanisamy

2011-04-01

A new bio-optical algorithm has been developed to provide accurate assessments of chlorophyll a (Chl a) concentration for detection and mapping of algal blooms from satellite data in optically complex waters, where the presence of suspended sediments and dissolved substances can interfere with phytoplankton signal and thus confound conventional band ratio algorithms. A global data set of concurrent measurements of pigment concentration and radiometric reflectance was compiled and used to develop this algorithm that uses the normalized water-leaving radiance ratios along with an algal bloom index (ABI) between three visible bands to determine Chl a concentrations. The algorithm is derived using Sea-viewing Wide Field-of-view Sensor bands, and it is subsequently tuned to be applicable to Moderate Resolution Imaging Spectroradiometer (MODIS)/Aqua data. When compared with large in situ data sets and satellite matchups in a variety of coastal and ocean waters the present algorithm makes good retrievals of the Chl a concentration and shows statistically significant improvement over current global algorithms (e.g., OC3 and OC4v4). An examination of the performance of these algorithms on several MODIS/Aqua images in complex waters of the Arabian Sea and west Florida shelf shows that the new algorithm provides a better means for detecting and differentiating algal blooms from other turbid features, whereas the OC3 algorithm has significant errors although yielding relatively consistent results in clear waters. These findings imply that, provided that an accurate atmospheric correction scheme is available to deal with complex waters, the current MODIS/Aqua, MERIS and OCM data could be extensively used for quantitative and operational monitoring of algal blooms in various regional and global waters.
Heat-Wave Effects on Oxygen, Nutrients, and Phytoplankton Can Alter Global Warming Potential of Gases Emitted from a Small Shallow Lake.

Science.gov (United States)

Bartosiewicz, Maciej; Laurion, Isabelle; Clayer, François; Maranger, Roxane

2016-06-21

Increasing air temperatures may result in stronger lake stratification, potentially altering nutrient and biogenic gas cycling. We assessed the impact of climate forcing by comparing the influence of stratification on oxygen, nutrients, and global-warming potential (GWP) of greenhouse gases (the sum of CH4, CO2, and N2O in CO2 equivalents) emitted from a shallow productive lake during an average versus a heat-wave year. Strong stratification during the heat wave was accompanied by an algal bloom and chemically enhanced carbon uptake. Solar energy trapped at the surface created a colder, isolated hypolimnion, resulting in lower ebullition and overall lower GWP during the hotter-than-average year. Furthermore, the dominant CH4 emission pathway shifted from ebullition to diffusion, with CH4 being produced at surprisingly high rates from sediments (1.2-4.1 mmol m(-2) d(-1)). Accumulated gases trapped in the hypolimnion during the heat wave resulted in a peak efflux to the atmosphere during fall overturn when 70% of total emissions were released, with littoral zones acting as a hot spot. The impact of climate warming on the GWP of shallow lakes is a more complex interplay of phytoplankton dynamics, emission pathways, thermal structure, and chemical conditions, as well as seasonal and spatial variability, than previously reported.
Phytoplankton growth and herbivory in the subarctic Pacific: A chemotaxonomic analysis

International Nuclear Information System (INIS)

Welschmeyer, N.; Goericke, R.; Strom, S.; Peterson, W.

1991-01-01

Chlorophyll crops in the subarctic Pacific are low and relatively constant throughout the year; however, net growth of phytoplankton occurs when natural water is enclosed in incubation containers and exposed to adequate irradiance. Pigment-based measurements of taxon-specific growth rates and taxon-specific grazing pressure were made in an attempt to understand the dynamic processes leading to the net growth of phytoplankton in bottles. Specific growth rates, determined from 14 C labeling of chromatographically separated pigments showed that fucoxanthin-containing cells (diatoms) were the fastest growing microalgae; a rapid net accumulation of fucoxanthin also occurred. Independent measurements of specific growth rates, determined from chromatographic analysis of microzooplankton dilution experiments, also showed that fucoxanthin-containing cells had the highest specific growth rates. Importantly, microzooplankton grazing rates on fucoxanthin-containing cells were only about half the specific growth rate; hence, the resultant bloom of fucoxanthin. The authors speculate that the lag in chlorophyll growth that has been reported previously is an artifact of subculturing; fast-growing, but dilute, fucoxanthin-containing cells do not become a significant portion of the total chlorophyll signal until late in the experiment. Other diagnostic carotenoids, such as 19'-hexanoyloxyfucoxanthin and 19'-butanoyloxyfucoxanthin, remained nearly constant through long-term incubations. However, they became actively 14 C labeled and showed positive specific rates of growth. Dilution experiments showed that their specific growth rate was compensated by microzooplankton grazing
sxtA-based quantitative molecular assay to identify saxitoxin-producing harmful algal blooms in marine waters.

Science.gov (United States)

Murray, Shauna A; Wiese, Maria; Stüken, Anke; Brett, Steve; Kellmann, Ralf; Hallegraeff, Gustaaf; Neilan, Brett A

2011-10-01

The recent identification of genes involved in the production of the potent neurotoxin and keystone metabolite saxitoxin (STX) in marine eukaryotic phytoplankton has allowed us for the first time to develop molecular genetic methods to investigate the chemical ecology of harmful algal blooms in situ. We present a novel method for detecting and quantifying the potential for STX production in marine environmental samples. Our assay detects a domain of the gene sxtA that encodes a unique enzyme putatively involved in the sxt pathway in marine dinoflagellates, sxtA4. A product of the correct size was recovered from nine strains of four species of STX-producing Alexandrium and Gymnodinium catenatum and was not detected in the non-STX-producing Alexandrium species, other dinoflagellate cultures, or an environmental sample that did not contain known STX-producing species. However, sxtA4 was also detected in the non-STX-producing strain of Alexandrium tamarense, Tasmanian ribotype. We investigated the copy number of sxtA4 in three strains of Alexandrium catenella and found it to be relatively constant among strains. Using our novel method, we detected and quantified sxtA4 in three environmental blooms of Alexandrium catenella that led to STX uptake in oysters. We conclude that this method shows promise as an accurate, fast, and cost-effective means of quantifying the potential for STX production in marine samples and will be useful for biological oceanographic research and harmful algal bloom monitoring.
Toxic Cyanobacterial Bloom Triggers in Missisquoi Bay, Lake Champlain, as Determined by Next-Generation Sequencing and Quantitative PCR

Directory of Open Access Journals (Sweden)

Nathalie Fortin

2015-05-01

Full Text Available Missisquoi Bay (MB is a temperate eutrophic freshwater lake that frequently experiences toxic Microcystis-dominated cyanobacterial blooms. Non-point sources are responsible for the high concentrations of phosphorus and nitrogen in the bay. This study combined data from environmental parameters, E. coli counts, high-throughput sequencing of 16S rRNA gene amplicons, quantitative PCR (16S rRNA and mcyD genes and toxin analyses to identify the main bloom-promoting factors. In 2009, nutrient concentrations correlated with E. coli counts, abundance of total cyanobacterial cells, Microcystis 16S rRNA and mcyD genes and intracellular microcystin. Total and dissolved phosphorus also correlated significantly with rainfall. The major cyanobacterial taxa were members of the orders Chroococcales and Nostocales. The genus Microcystis was the main mcyD-carrier and main microcystin producer. Our results suggested that increasing nutrient concentrations and total nitrogen:total phosphorus (TN:TP ratios approaching 11:1, coupled with an increase in temperature, promoted Microcystis-dominated toxic blooms. Although the importance of nutrient ratios and absolute concentrations on cyanobacterial and Microcystis dynamics have been documented in other laboratories, an optimum TN:TP ratio for Microcystis dominance has not been previously observed in situ. This observation provides further support that nutrient ratios are an important determinant of species composition in natural phytoplankton assemblages.
Connecting pigment composition and dissolved trace elements to phytoplankton population in the southern Benguela Upwelling zone (St. Helena Bay)

Science.gov (United States)

Das, Supriyo Kumar; Routh, Joyanto; Roychoudhury, Alakendra N.; Veldhuis, Marcel J. W.; Ismail, Hassan E.

2017-12-01

Rich in upwelled nutrients, the Southern Benguela is one of the most productive ecosystems in the world ocean. However, despite its ecological significance the role of trace elements influencing phytoplankton population in the Southern Benguela Upwelling System (SBUS) has not been thoroughly investigated. Here, we report pigment composition, macronutrients (nitrate, phosphate and silicate) and concentrations of dissolved Cd, Co, Fe and Zn during late austral summer and winter seasons in 2004 to understand the relationship between the selected trace elements and phytoplankton biomass in St. Helena Bay (SHB), which falls within the southern boundary of the SBUS. Chlorophyll a concentrations indicate higher phytoplankton biomass associated with high primary production during late summer in SHB where high diatom population is inferred from the presence of fucoxanthin. Diminished phytoplankton biomass and a shift from diatoms to dinoflagellates as the dominant phytoplankton taxa are indicated by diagnostic pigments during late winter. Dissolved trace elements (Cd, Co and Zn) and macronutrients play a significant role in phytoplankton biomass, and their distribution is affected by biological uptake and export of trace elements. Continuous uptake of Zn by diatoms may cause an onset of Zn depletion leading to a period of extended diatom proliferation during late summer. Furthermore, the transition from diatom to dinoflagellate dominated phytoplankton population is most likely facilitated by depletion of trace elements (Cd and Co) in the water column.
Climate Variability and Oceanographic Settings Associated with Interannual Variability in the Initiation of Dinophysis acuminata Blooms

Directory of Open Access Journals (Sweden)

Henrick Berger

2013-08-01

Full Text Available In 2012, there were exceptional blooms of D. acuminata in early spring in what appeared to be a mesoscale event affecting Western Iberia and the Bay of Biscay. The objective of this work was to identify common climatic patterns to explain the observed anomalies in two important aquaculture sites, the Galician Rías Baixas (NW Spain and Arcachon Bay (SW France. Here, we examine climate variability through physical-biological couplings, Sea Surface Temperature (SST anomalies and time of initiation of the upwelling season and its intensity over several decades. In 2012, the mesoscale features common to the two sites were positive anomalies in SST and unusual wind patterns. These led to an atypical predominance of upwelling in winter in the Galician Rías, and increased haline stratification associated with a southward advection of the Gironde plume in Arcachon Bay. Both scenarios promoted an early phytoplankton growth season and increased stability that enhanced D. acuminata growth. Therefore, a common climate anomaly caused exceptional blooms of D. acuminata in two distant regions through different triggering mechanisms. These results increase our capability to predict intense diarrhetic shellfish poisoning outbreaks in the early spring from observations in the preceding winter.
Retrieval of phytoplankton cell size from chlorophyll a specific absorption and scattering spectra of phytoplankton.

Science.gov (United States)

Zhou, Wen; Wang, Guifen; Li, Cai; Xu, Zhantang; Cao, Wenxi; Shen, Fang

2017-10-20

Phytoplankton cell size is an important property that affects diverse ecological and biogeochemical processes, and analysis of the absorption and scattering spectra of phytoplankton can provide important information about phytoplankton size. In this study, an inversion method for extracting quantitative phytoplankton cell size data from these spectra was developed. This inversion method requires two inputs: chlorophyll a specific absorption and scattering spectra of phytoplankton. The average equivalent-volume spherical diameter (ESD v ) was calculated as the single size approximation for the log-normal particle size distribution (PSD) of the algal suspension. The performance of this method for retrieving cell size was assessed using the datasets from cultures of 12 phytoplankton species. The estimations of a(λ) and b(λ) for the phytoplankton population using ESD v had mean error values of 5.8%-6.9% and 7.0%-10.6%, respectively, compared to the a(λ) and b(λ) for the phytoplankton populations using the log-normal PSD. The estimated values of C i ESD v were in good agreement with the measurements, with r 2 =0.88 and relative root mean square error (NRMSE)=25.3%, and relatively good performances were also found for the retrieval of ESD v with r 2 =0.78 and NRMSE=23.9%.
Copepod grazing and their impact on phytoplankton standing stock and production in a tropical coastal water during the different seasons.

Science.gov (United States)

Jagadeesan, L; Jyothibabu, R; Arunpandi, N; Parthasarathi, S

2017-03-01

of the seasons, dominant calanoid copepods showed a negative selection of pico-phytoplankton fraction. The cyclopoid O. similis and Poecilostomatoid Corycaeus danae showed a positive selection of nano- and pico-phytoplankton fractions rather than micro-fraction. The grazing pressure of copepod community ingestion on micro-fraction was less (0.56% of the phytoplankton biomass and 1.06% of the phytoplankton production) during the PKSWM. This study provides, for the first time, clear findings on the seasonal variation in the top-down control of phytoplankton by copepods in a tropical coastal water ecosystem and discusses its implications on phytoplankton blooming, plankton food web, and biogeochemistry.

Seasonal variation of absorption by particles and colored dissolved organic matter (CDOM) in Funka Bay, southwestern Hokkaido, Japan

Science.gov (United States)

Sasaki, Hiroaki; Miyamura, Tsuyoshi; Saitoh, Sei-ichi; Ishizaka, Joji

2005-08-01

Between November 2000 and October 2001, the seasonal variation in absorption by particles (phytoplankton and detritus) and colored dissolved organic matter (CDOM) was measured in Funka Bay (a subarctic coastal region of Japan). In autumn-winter, chlorophyll a concentration (Chl a) near the euphotic zone remained very low (summer and low during the spring bloom. This is because the package effect was greater during the spring bloom due to the presence of large diatoms, while small phytoplankton dominated during summer. Absorption at 440 nm by CDOM was higher than that of phytoplankton and detritus, except during the spring bloom, and the relative contribution of CDOM absorption to the total absorption coefficient was >50%. CDOM and detritus absorption did not increase with increasing Chl a, but it showed a time lag between the spring bloom. It is suggested that phytoplankton degradation started after the spring bloom; detritus absorption increased and, then, CDOM absorption increased. River runoff was not a significant influence in Funka Bay, therefore, CDOM production may be mainly related to microbial activity.
Response of phytoplankton and enhanced biogeochemical activity to an episodic typhoon event in the coastal waters of Japan

Science.gov (United States)

Tsuchiya, Kenji; Kuwahara, Victor S.; Yoshiki, Tomoko M.; Nakajima, Ryota; Shimode, Shinji; Kikuchi, Tomohiko; Toda, Tatsuki

2017-07-01

Daily field surveys were conducted at a coastal-shelf station in Sagami Bay, Japan after the passage of typhoon Malou in 2010 to evaluate the after-effect of a typhoon passage on the physical-chemical environment, phytoplankton bloom formation and microbial processes within and below the euphotic layer. The passage of Malou induced an abrupt decrease in salinity and increased loading of nutrients to the euphotic layer. Dinoflagellates dominated the phytoplankton community at the surface, whereas diatoms dominated below the surface just after the passage of Malou. Four days later, the dominant dinoflagellate taxa at the surface changed from Protoperidinium spp. to Prorocentrum spp. and Ceratium spp., indicating a dinoflagellate community succession from heterotrophic to autotrophic functional groups. Five days after passage, the dominant phytoplankton taxa shifted from dinoflagellates to diatom groups of Chaetoceros spp. and Cerataulina spp. throughout the water column. Below the euphotic layer, there were increases in diatom frustules, mainly composed of Chaetoceros spp. and Cerataulina spp., bacterial abundance and NH4+ concentrations. Diatom carbon biomass contributed to approximately half of particulate organic carbon (POC) below the euphotic layer, suggesting a significant contribution of diatoms to POC sinking flux after the passage of a typhoon. Bacterial abundance was positively correlated to both phaeopigment concentrations (p affect biogeochemical activities within and below the euphotic layer in temperate coastal waters.
Seasonal cooling and blooming in tropical oceans

Science.gov (United States)

Longhurst, Alan

1993-11-01

The relative importance of tropical pelagic algal blooms in not yet fully appreciated and the way they are induced not well understood. The tropical Atlantic supports pelagic blooms together equivalent to the North Atlantic spring bloom. These blooms are driven by thermocline tilting, curl of wind stress and eddy upwelling as the ocean responds to intensified basin-scale winds in boreal summer. The dimensions of the Pacific Ocean are such that seasonal thermocline tilting does not occur, and nutrient conditions are such that tilting might not induce bloom, in any case. Divergence at the equator is a separate process that strengthens the Atlantic bloom, is more prominent in the eastern Pacific, and in the Indian Ocean induces a bloom only in the western part of the ocean. Where western jet currents are retroflected from the coast off Somalia and Brazil, eddy upwelling induces prominent blooms. In the eastward flow of the northern equatorial countercurrents, positive wind curl stress induces Ekman pumping and the induction of algal blooms aligned with the currents. Some apparent algal bloom, such as that seen frequently in CZCS images westwards from Senegal, must be due to interference from airborne dust.
Seasonal and interannual variabilities of coccolithophore blooms in the Bay of Biscay and the Celtic Sea observed from a 18-year time-series of non-algal Suspended Particulate Matter images

Science.gov (United States)

Perrot, Laurie; Gohin, Francis; Ruiz-Pino, Diana; Lampert, Luis

2016-04-01

Coccolithophores belong to the nano-phytoplankton size-class and produce CaCO3 scales called coccoliths which form the «shell» of the algae cell. Coccoliths are in the size range of a few μm and can also be detached from the cell in the water. This phytoplankton group has an ubiquitous distribution in all oceans but blooms only in some oceanic regions, like the North East Atlantic ocean and the South Western Atlantic (Patagonian Sea). At a global scale coccolithopore blooms are studied in regard of CaCO3 production and three potential feedback on climate change: albedo modification by the way of dimethylsulfide (DMS) production and atmospheric CO2 source by calcification and a CO2 pump by photosynthesis. As the oceans are more and more acidified by anthropogenic CO2 emissions, coccolithophores generally are expected to be negatively affected. However, recent studies have shown an increase in coccolithophore occurrence in the North Atlantic. A poleward expansion of the coccolithophore Emiliana Huxleyi has also been pointed out. By using a simplified fuzzy method applied to a 18-year time series of SeaWiFS (1998-2002) and MODIS (2003-2015) spectral reflectance, we assessed the seasonal and inter-annual variability of coccolithophore blooms in the vicinity of the shelf break in the Bay of Biscay and the Celtic Sea After identification of the coccolith pixels by applying the fuzzy method, the abundance of coccoliths is assessed from a database of non-algal Suspended Particulate Matter (SPM). Although a regular pattern in the phenology of the blooms is observed, starting south in April in Biscay and moving northwards until July in Ireland, there is a high seasonal and interannual variability in the extent of the blooms. Year 2014 shows very low concentrations of detached coccoliths (twice less than average) from space and anomalies point out the maximum level in 2001. Non-algal SPM, derived from a procedure defined for the continental shelf, appears to be well
The light absorption by suspended particles, phytoplankton and dissolved organic matter in deep-and coastal waiters of the Black Sea impact on algorithms for remote sensing of chlorophyll -a-.

Science.gov (United States)

Churilova, T.; Suslin, V.; Berseneva, G.; Georgieva, L.

At present time for the analysis and prediction of marine ecosystem state Chlorophyll and Primary production models based on optical satellite data are widely used. However, the SeaWiFS algorithms providing the transformation of color images to chlorophyll maps give inaccurate estimation of chlorophyll "a" (Chl "a") concentration in the Black Sea - an overestimation approximately two times in summer and an underestimation - ~1,5 times during the large diatom bloom in winter-spring. A development of the regional Chl "a" algorithm requires an estimation of spectral characteristics of all light absorbing components and their relationships with Chl "a" concentration. With this aim bio-optical monitoring was organized in two fixed stations in deep-water central western part of the Black Sea and in shelf waters near the Crimea. The weekly monitoring in deep-waters region allowed to determine phytoplankton community succession: seasonal dynamics of size and taxonomic structure, development of large diatoms blooming in March and coccolithophores - in June. The significant variability in pigment concentration and species content of phytoplankton is accompanied by high variability in shape of the phytoplankton absorption spectra and in values of chl a-specific absorption coefficients. This variability had seasonal character depending mostly on the optical status of phytoplankton cells and partly on taxonomic structure of phytoplankton. The pigment packaging parameter fluctuated from 0.64-0.68 (October-December) to 0.95-0.97 (April-May). The package effect depended on intracellular pigment concentration and the size and geometry of cells, which change significantly over the year, because of extremely different environmental conditions. The relationships between phytoplankton specific absorption coefficients (at 412, 443, 490, 510, 555, 678 nm) and Chl "a" concentration have been described by power functions. The contribution of detritus to total particulate absorption
Spatial dynamics of a nutrient-phytoplankton system with toxic effect on phytoplankton

DEFF Research Database (Denmark)

Chakraborty, Subhendu; Tiwari, P. K.; Misra, A. K.

2015-01-01

The production of toxins by some species of phytoplankton is known to have several economic, ecological, and human health impacts. However, the role of toxins on the spatial distribution of phytoplankton is not well understood. In the present study, the spatial dynamics of a nutrient-phytoplankto...... patterns, like stripes, spots, and the mixture of them depending on the toxicity level. We also observe that the distribution of nutrient and phytoplankton shows spatiotemporal oscillation for certain toxicity level. (C) 2015 Elsevier Inc. All rights reserved....
An Inverse Modeling Approach to Estimating Phytoplankton Pigment Concentrations from Phytoplankton Absorption Spectra

Science.gov (United States)

Moisan, John R.; Moisan, Tiffany A. H.; Linkswiler, Matthew A.

2011-01-01

Phytoplankton absorption spectra and High-Performance Liquid Chromatography (HPLC) pigment observations from the Eastern U.S. and global observations from NASA's SeaBASS archive are used in a linear inverse calculation to extract pigment-specific absorption spectra. Using these pigment-specific absorption spectra to reconstruct the phytoplankton absorption spectra results in high correlations at all visible wavelengths (r(sup 2) from 0.83 to 0.98), and linear regressions (slopes ranging from 0.8 to 1.1). Higher correlations (r(sup 2) from 0.75 to 1.00) are obtained in the visible portion of the spectra when the total phytoplankton absorption spectra are unpackaged by multiplying the entire spectra by a factor that sets the total absorption at 675 nm to that expected from absorption spectra reconstruction using measured pigment concentrations and laboratory-derived pigment-specific absorption spectra. The derived pigment-specific absorption spectra were further used with the total phytoplankton absorption spectra in a second linear inverse calculation to estimate the various phytoplankton HPLC pigments. A comparison between the estimated and measured pigment concentrations for the 18 pigment fields showed good correlations (r(sup 2) greater than 0.5) for 7 pigments and very good correlations (r(sup 2) greater than 0.7) for chlorophyll a and fucoxanthin. Higher correlations result when the analysis is carried out at more local geographic scales. The ability to estimate phytoplankton pigments using pigment-specific absorption spectra is critical for using hyperspectral inverse models to retrieve phytoplankton pigment concentrations and other Inherent Optical Properties (IOPs) from passive remote sensing observations.
Journal of Earth System Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

Identification of non-indigenous phytoplankton species dominated bloom off Goa using inverted microscopy and pigment (HPLC) analysis · P V Bhaskar Rajdeep Roy Mangesh Gauns D M Shenoy V D Rao S Mochemadkar · More Details Abstract Fulltext PDF. An unusual phytoplankton bloom dominated by unidentified ...
Multicellular Features of Phytoplankton

Directory of Open Access Journals (Sweden)

Adi Abada

2018-04-01

Full Text Available Microscopic marine phytoplankton drift freely in the ocean, harvesting sunlight through photosynthesis. These unicellular microorganisms account for half of the primary productivity on Earth and play pivotal roles in the biogeochemistry of our planet (Field et al., 1998. The major groups of microalgae that comprise the phytoplankton community are coccolithophores, diatoms and dinoflagellates. In present oceans, phytoplankton individuals and populations are forced to rapidly adjust, as key chemical and physical parameters defining marine habitats are changing globally. Here we propose that microalgal populations often display the characteristics of a multicellular-like community rather than a random collection of individuals. Evolution of multicellularity entails a continuum of events starting from single cells that go through aggregation or clonal divisions (Brunet and King, 2017. Phytoplankton may be an intermediate state between single cells and aggregates of physically attached cells that communicate and co-operate; perhaps an evolutionary snapshot toward multicellularity. In this opinion article, we journey through several studies conducted in two key phytoplankton groups, coccolithophores and diatoms, to demonstrate how observations in these studies could be interpreted in a multicellular context.
Remote sensing the phytoplankton seasonal succession of the Red Sea.

Science.gov (United States)

Raitsos, Dionysios E; Pradhan, Yaswant; Brewin, Robert J W; Stenchikov, Georgiy; Hoteit, Ibrahim

2013-01-01

The Red Sea holds one of the most diverse marine ecosystems, primarily due to coral reefs. However, knowledge on large-scale phytoplankton dynamics is limited. Analysis of a 10-year high resolution Chlorophyll-a (Chl-a) dataset, along with remotely-sensed sea surface temperature and wind, provided a detailed description of the spatiotemporal seasonal succession of phytoplankton biomass in the Red Sea. Based on MODIS (Moderate-resolution Imaging Spectroradiometer) data, four distinct Red Sea provinces and seasons are suggested, covering the major patterns of surface phytoplankton production. The Red Sea Chl-a depicts a distinct seasonality with maximum concentrations seen during the winter time (attributed to vertical mixing in the north and wind-induced horizontal intrusion of nutrient-rich water in the south), and minimum concentrations during the summer (associated with strong seasonal stratification). The initiation of the seasonal succession occurs in autumn and lasts until early spring. However, weekly Chl-a seasonal succession data revealed that during the month of June, consistent anti-cyclonic eddies transfer nutrients and/or Chl-a to the open waters of the central Red Sea. This phenomenon occurs during the stratified nutrient depleted season, and thus could provide an important source of nutrients to the open waters. Remotely-sensed synoptic observations highlight that Chl-a does not increase regularly from north to south as previously thought. The Northern part of the Central Red Sea province appears to be the most oligotrophic area (opposed to southern and northern domains). This is likely due to the absence of strong mixing, which is apparent at the northern end of the Red Sea, and low nutrient intrusion in comparison with the southern end. Although the Red Sea is considered an oligotrophic sea, sporadic blooms occur that reach mesotrophic levels. The water temperature and the prevailing winds control the nutrient concentrations within the euphotic zone
Remote Sensing the Phytoplankton Seasonal Succession of the Red Sea

KAUST Repository

Raitsos, Dionysios E.

2013-06-05

The Red Sea holds one of the most diverse marine ecosystems, primarily due to coral reefs. However, knowledge on large-scale phytoplankton dynamics is limited. Analysis of a 10-year high resolution Chlorophyll-a (Chl-a) dataset, along with remotely-sensed sea surface temperature and wind, provided a detailed description of the spatiotemporal seasonal succession of phytoplankton biomass in the Red Sea. Based on MODIS (Moderate-resolution Imaging Spectroradiometer) data, four distinct Red Sea provinces and seasons are suggested, covering the major patterns of surface phytoplankton production. The Red Sea Chl-a depicts a distinct seasonality with maximum concentrations seen during the winter time (attributed to vertical mixing in the north and wind-induced horizontal intrusion of nutrient-rich water in the south), and minimum concentrations during the summer (associated with strong seasonal stratification). The initiation of the seasonal succession occurs in autumn and lasts until early spring. However, weekly Chl-a seasonal succession data revealed that during the month of June, consistent anti-cyclonic eddies transfer nutrients and/or Chl-a to the open waters of the central Red Sea. This phenomenon occurs during the stratified nutrient depleted season, and thus could provide an important source of nutrients to the open waters. Remotely-sensed synoptic observations highlight that Chl-a does not increase regularly from north to south as previously thought. The Northern part of the Central Red Sea province appears to be the most oligotrophic area (opposed to southern and northern domains). This is likely due to the absence of strong mixing, which is apparent at the northern end of the Red Sea, and low nutrient intrusion in comparison with the southern end. Although the Red Sea is considered an oligotrophic sea, sporadic blooms occur that reach mesotrophic levels. The water temperature and the prevailing winds control the nutrient concentrations within the euphotic zone
Sea Soup: Phytoplankton.

Science.gov (United States)

Cerullo, Mary M.

This guide, designed for students in grades 3-7, answers intriguing questions about phytoplankton, tiny drifters that have shaped our world. Invisible to the naked eye, phytoplankton are the source of our atmosphere, our climate, our ocean food chain, much of our oil supply, and more. They're also food for zooplankton. Photomicroscopy serves up…
Dancing with the Tides: Fluctuations of Coastal Phytoplankton Orchestrated by Different Oscillatory Modes of the Tidal Cycle

Science.gov (United States)

Blauw, Anouk N.; Benincà, Elisa; Laane, Remi W. P. M.; Greenwood, Naomi; Huisman, Jef

2012-01-01

Population fluctuations are often driven by an interplay between intrinsic population processes and extrinsic environmental forcing. To investigate this interplay, we analyzed fluctuations in coastal phytoplankton concentration in relation to the tidal cycle. Time series of chlorophyll fluorescence, suspended particulate matter (SPM), salinity and temperature were obtained from an automated measuring platform in the southern North Sea, covering 9 years of data at a resolution of 12 to 30 minutes. Wavelet analysis showed that chlorophyll fluctuations were dominated by periodicities of 6 hours 12 min, 12 hours 25 min, 24 hours and 15 days, which correspond to the typical periodicities of tidal current speeds, the semidiurnal tidal cycle, the day-night cycle, and the spring-neap tidal cycle, respectively. During most of the year, chlorophyll and SPM fluctuated in phase with tidal current speed, indicative of alternating periods of sinking and vertical mixing of algal cells and SPM driven by the tidal cycle. Spring blooms slowly built up over several spring-neap tidal cycles, and subsequently expanded in late spring when a strong decline of the SPM concentration during neap tide enabled a temporary “escape” of the chlorophyll concentration from the tidal mixing regime. Our results demonstrate that the tidal cycle is a major determinant of phytoplankton fluctuations at several different time scales. These findings imply that high-resolution monitoring programs are essential to capture the natural variability of phytoplankton in coastal waters. PMID:23166639
A biogeochemical model of Lake Pusiano (North Italy and its use in the predictability of phytoplankton blooms: first preliminary results

Directory of Open Access Journals (Sweden)

Alessandro OGGIONI

2006-02-01

Full Text Available This study reports the first preliminary results of the DYRESM-CAEDYM model application to a mid size sub-alpine lake (Lake Pusiano North Italy. The in-lake modelling is a part of a more general project called Pusiano Integrated Lake/Catchment project (PILE whose final goal is to understand the hydrological and trophic relationship between lake and catchment, supporting the restoration plan of the lake through field data analysis and numerical models. DYRESM is a 1D-3D hydrodynamics model for predicting the vertical profile of temperature, salinity and density. CAEDYM is multi-component ecological model, used here as a phytoplankton-zooplankton processes based model, which includes algorithms to simulate the nutrient cycles within the water column as well as the air-water gas exchanges and the water-sediments fluxes. The first results of the hydrodynamics simulations underline the capability of the model to accurately simulate the surface temperature seasonal trend and the thermal gradient whereas, during summer stratification, the model underestimates the bottom temperature of around 2 °C. The ecological model describes the epilimnetic reactive phosphorus (PO4 depletion (due to the phytoplankton uptake and the increase in PO4 concentrations in the deepest layers of the lake (due to the mineralization processes and the sediments release. In terms of phytoplankton dynamics the model accounts for the Planktothrix rubescens dominance during the whole season, whereas it seems to underestimate the peak in primary production related to both the simulated algal groups (P. rubescens and the rest of the other species aggregated in a single class. The future aims of the project are to complete the model parameterization and to connect the in-lake and the catchment modelling in order to gain an integrated view of the lake-catchment ecosystem as well as to develop a three dimensional model of the lake.
sxtA-Based Quantitative Molecular Assay To Identify Saxitoxin-Producing Harmful Algal Blooms in Marine Waters ▿ †

Science.gov (United States)

Murray, Shauna A.; Wiese, Maria; Stüken, Anke; Brett, Steve; Kellmann, Ralf; Hallegraeff, Gustaaf; Neilan, Brett A.

2011-01-01

The recent identification of genes involved in the production of the potent neurotoxin and keystone metabolite saxitoxin (STX) in marine eukaryotic phytoplankton has allowed us for the first time to develop molecular genetic methods to investigate the chemical ecology of harmful algal blooms in situ. We present a novel method for detecting and quantifying the potential for STX production in marine environmental samples. Our assay detects a domain of the gene sxtA that encodes a unique enzyme putatively involved in the sxt pathway in marine dinoflagellates, sxtA4. A product of the correct size was recovered from nine strains of four species of STX-producing Alexandrium and Gymnodinium catenatum and was not detected in the non-STX-producing Alexandrium species, other dinoflagellate cultures, or an environmental sample that did not contain known STX-producing species. However, sxtA4 was also detected in the non-STX-producing strain of Alexandrium tamarense, Tasmanian ribotype. We investigated the copy number of sxtA4 in three strains of Alexandrium catenella and found it to be relatively constant among strains. Using our novel method, we detected and quantified sxtA4 in three environmental blooms of Alexandrium catenella that led to STX uptake in oysters. We conclude that this method shows promise as an accurate, fast, and cost-effective means of quantifying the potential for STX production in marine samples and will be useful for biological oceanographic research and harmful algal bloom monitoring. PMID:21841034
Assimilation of diazotrophic nitrogen into pelagic food webs.

Science.gov (United States)

Woodland, Ryan J; Holland, Daryl P; Beardall, John; Smith, Jonathan; Scicluna, Todd; Cook, Perran L M

2013-01-01

The fate of diazotrophic nitrogen (N(D)) fixed by planktonic cyanobacteria in pelagic food webs remains unresolved, particularly for toxic cyanophytes that are selectively avoided by most herbivorous zooplankton. Current theory suggests that N(D) fixed during cyanobacterial blooms can enter planktonic food webs contemporaneously with peak bloom biomass via direct grazing of zooplankton on cyanobacteria or via the uptake of bioavailable N(D) (exuded from viable cyanobacterial cells) by palatable phytoplankton or microbial consortia. Alternatively, N(D) can enter planktonic food webs post-bloom following the remineralization of bloom detritus. Although the relative contribution of these processes to planktonic nutrient cycles is unknown, we hypothesized that assimilation of bioavailable N(D) (e.g., nitrate, ammonium) by palatable phytoplankton and subsequent grazing by zooplankton (either during or after the cyanobacterial bloom) would be the primary pathway by which N(D) was incorporated into the planktonic food web. Instead, in situ stable isotope measurements and grazing experiments clearly documented that the assimilation of N(D) by zooplankton outpaced assimilation by palatable phytoplankton during a bloom of toxic Nodularia spumigena Mertens. We identified two distinct temporal phases in the trophic transfer of N(D) from N. spumigena to the plankton community. The first phase was a highly dynamic transfer of N(D) to zooplankton with rates that covaried with bloom biomass while bypassing other phytoplankton taxa; a trophic transfer that we infer was routed through bloom-associated bacteria. The second phase was a slowly accelerating assimilation of the dissolved-N(D) pool by phytoplankton that was decoupled from contemporaneous variability in N. spumigena concentrations. These findings provide empirical evidence that N(D) can be assimilated and transferred rapidly throughout natural plankton communities and yield insights into the specific processes underlying
Assimilation of diazotrophic nitrogen into pelagic food webs.

Directory of Open Access Journals (Sweden)

Ryan J Woodland

Full Text Available The fate of diazotrophic nitrogen (N(D fixed by planktonic cyanobacteria in pelagic food webs remains unresolved, particularly for toxic cyanophytes that are selectively avoided by most herbivorous zooplankton. Current theory suggests that N(D fixed during cyanobacterial blooms can enter planktonic food webs contemporaneously with peak bloom biomass via direct grazing of zooplankton on cyanobacteria or via the uptake of bioavailable N(D (exuded from viable cyanobacterial cells by palatable phytoplankton or microbial consortia. Alternatively, N(D can enter planktonic food webs post-bloom following the remineralization of bloom detritus. Although the relative contribution of these processes to planktonic nutrient cycles is unknown, we hypothesized that assimilation of bioavailable N(D (e.g., nitrate, ammonium by palatable phytoplankton and subsequent grazing by zooplankton (either during or after the cyanobacterial bloom would be the primary pathway by which N(D was incorporated into the planktonic food web. Instead, in situ stable isotope measurements and grazing experiments clearly documented that the assimilation of N(D by zooplankton outpaced assimilation by palatable phytoplankton during a bloom of toxic Nodularia spumigena Mertens. We identified two distinct temporal phases in the trophic transfer of N(D from N. spumigena to the plankton community. The first phase was a highly dynamic transfer of N(D to zooplankton with rates that covaried with bloom biomass while bypassing other phytoplankton taxa; a trophic transfer that we infer was routed through bloom-associated bacteria. The second phase was a slowly accelerating assimilation of the dissolved-N(D pool by phytoplankton that was decoupled from contemporaneous variability in N. spumigena concentrations. These findings provide empirical evidence that N(D can be assimilated and transferred rapidly throughout natural plankton communities and yield insights into the specific processes
The Dimethylsulfide Cycle in the Eutrophied Southern North Sea: A Model Study Integrating Phytoplankton and Bacterial Processes

Science.gov (United States)

Gypens, Nathalie; Borges, Alberto V.; Speeckaert, Gaelle; Lancelot, Christiane

2014-01-01

We developed a module describing the dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) dynamics, including biological transformations by phytoplankton and bacteria, and physico-chemical processes (including DMS air-sea exchange). This module was integrated in the MIRO ecological model and applied in a 0D frame in the Southern North Sea (SNS). The DMS(P) module is built on parameterizations derived from available knowledge on DMS(P) sources, transformations and sinks, and provides an explicit representation of bacterial activity in contrast to most of existing models that only include phytoplankton process (and abiotic transformations). The model is tested in a highly productive coastal ecosystem (the Belgian coastal zone, BCZ) dominated by diatoms and the Haptophyceae Phaeocystis, respectively low and high DMSP producers. On an annual basis, the particulate DMSP (DMSPp) production simulated in 1989 is mainly related to Phaeocystis colonies (78%) rather than diatoms (13%) and nanoflagellates (9%). Accordingly, sensitivity analysis shows that the model responds more to changes in the sulfur:carbon (S:C) quota and lyase yield of Phaeocystis. DMS originates equally from phytoplankton and bacterial DMSP-lyase activity and only 3% of the DMS is emitted to the atmosphere. Model analysis demonstrates the sensitivity of DMS emission towards the atmosphere to the description and parameterization of biological processes emphasizing the need of adequately representing in models both phytoplankton and bacterial processes affecting DMS(P) dynamics. This is particularly important in eutrophied coastal environments such as the SNS dominated by high non-diatom blooms and where empirical models developed from data-sets biased towards open ocean conditions do not satisfactorily predict the timing and amplitude of the DMS seasonal cycle. In order to predict future feedbacks of DMS emissions on climate, it is needed to account for hotspots of DMS emissions from coastal
Biological data assimilation for parameter estimation of a phytoplankton functional type model for the western North Pacific

Science.gov (United States)

Hoshiba, Yasuhiro; Hirata, Takafumi; Shigemitsu, Masahito; Nakano, Hideyuki; Hashioka, Taketo; Masuda, Yoshio; Yamanaka, Yasuhiro

2018-06-01

Ecosystem models are used to understand ecosystem dynamics and ocean biogeochemical cycles and require optimum physiological parameters to best represent biological behaviours. These physiological parameters are often tuned up empirically, while ecosystem models have evolved to increase the number of physiological parameters. We developed a three-dimensional (3-D) lower-trophic-level marine ecosystem model known as the Nitrogen, Silicon and Iron regulated Marine Ecosystem Model (NSI-MEM) and employed biological data assimilation using a micro-genetic algorithm to estimate 23 physiological parameters for two phytoplankton functional types in the western North Pacific. The estimation of the parameters was based on a one-dimensional simulation that referenced satellite data for constraining the physiological parameters. The 3-D NSI-MEM optimized by the data assimilation improved the timing of a modelled plankton bloom in the subarctic and subtropical regions compared to the model without data assimilation. Furthermore, the model was able to improve not only surface concentrations of phytoplankton but also their subsurface maximum concentrations. Our results showed that surface data assimilation of physiological parameters from two contrasting observatory stations benefits the representation of vertical plankton distribution in the western North Pacific.
Distribution of Cd, Pb and Cu between dissolved fraction, inorganic particulate and phytoplankton in seawater of Terra Nova Bay (Ross Sea, Antarctica) during austral summer 2011-12.

Science.gov (United States)

Illuminati, S; Annibaldi, A; Romagnoli, T; Libani, G; Antonucci, M; Scarponi, G; Totti, C; Truzzi, C

2017-10-01

During the austral summer 2011-2012, the metal quotas of Cd, Pb and Cu in the phytoplankton of Terra Nova Bay (TNB, Antarctica) were measured for the first time. Evolution of all the three metal distributions between dissolved and particulate fractions during the season was also evaluated. Metal concentrations were mainly affected by the dynamic of the pack ice melting and phytoplankton activity. In mid-December when TNB area was covered by a thick pack ice layer and phytoplankton activity was very low, all the three metals were present mainly in their dissolved species. When the pack ice started to melt and the water column characteristics became ideal (i.e. moderate stratification, ice free area), the phytoplankton bloom occurred. Cd showed a nutrient-type behaviour with dissolved and particulate fractions mainly influenced by phytoplankton activity. Cd quota showed a mean value of 0.12 ± 0.07 nmol L -1 (30-100% of the total particulate). Also Cu showed a nutrient-type behaviour, with its quota in phytoplankton varying between 0.08 and 2.1 nmol L -1 (20-100% of the total particulate). Pb features the typical distribution of a scavenged element with very low algal content (0.03 ± 0.02 nmol L -1 , representing 20-50% of the total particulate). The vertical distribution of this element was influenced by several factors (e.g. pack ice melting, atmospheric inputs), the phytoplankton activity affecting Pb behaviour only partially. Metal:C ratios provide valuable information on the biological requirements for Cd, Pb and Cu, leading us to better understand their biogeochemical cycles. Copyright © 2017 Elsevier Ltd. All rights reserved.

How Bigelow Laboratory Measured Broader Impacts: The Case Study of the Evaluation of the Keller BLOOM Program (Invited)

Science.gov (United States)

Fowler, R. A.; Repa, J.

2010-12-01

In this presentation we discuss the impetus for, the results of the short and long term effects, and the impacts of the Keller BLOOM Program, hosted by Bigelow Laboratory for Ocean Sciences of West Boothbay Harbor, Maine. Each May, for the last 21 years, 16 bright high school juniors, one from each county in Maine, have been invited to spend five days with the research scientists at the lab conducting and reporting research on the bottom layers of the ocean’s food chain: phytoplankton and zooplankton. Bigelow has chosen to evaluate BLOOM through a series of questionnaires delivered during the program, and long term tracking of participants after the program, in order to better understand the impact of the program on participants. The short term effect of the experience, measured at the end of the week, found that participants are able to: 1) develop testable research questions, 2) collect multiple water samples from a local estuary, 3) measure various characteristics of those samples with the sophisticated instruments in Bigelow’s labs assisted by their research scientists, 4) analyze and integrate the results from the various labs, and 5) present their findings to a non-scientific audience. To measure long term participation effects, a random sample of 40 of the 332 participants were interviewed resulting in the following findings: 100% attend college; 62% have STEM majors; 88% graduate from college; 57% pursue STEM careers; and 60% live and work in Maine. Bigelow scientists include a description of the BLOOM Program and the evaluation results in their NSF Broader Impacts statements to demonstrate that their research activities are being integrated into a successful STEM education program. Evaluation results are also used by Bigelow scientists and program administrators to refine program content and delivery, to promote the program to potential applicants, and to strengthen proposals to funding agencies when seeking financial support for BLOOM.
Assimilating bio-optical glider data during a phytoplankton bloom in the southern Ross Sea

Directory of Open Access Journals (Sweden)

D. E. Kaufman

2018-01-01

Full Text Available The Ross Sea is a region characterized by high primary productivity in comparison to other Antarctic coastal regions, and its productivity is marked by considerable variability both spatially (1–50 km and temporally (days to weeks. This variability presents a challenge for inferring phytoplankton dynamics from observations that are limited in time or space, which is often the case due to logistical limitations of sampling. To better understand the spatiotemporal variability in Ross Sea phytoplankton dynamics and to determine how restricted sampling may skew dynamical interpretations, high-resolution bio-optical glider measurements were assimilated into a one-dimensional biogeochemical model adapted for the Ross Sea. The assimilation of data from the entire glider track using the micro-genetic and local search algorithms in the Marine Model Optimization Testbed improves the model–data fit by ∼ 50 %, generating rates of integrated primary production of 104 g C m−2 yr−1 and export at 200 m of 27 g C m−2 yr−1. Assimilating glider data from three different latitudinal bands and three different longitudinal bands results in minimal changes to the simulations, improves the model–data fit with respect to unassimilated data by ∼ 35 %, and confirms that analyzing these glider observations as a time series via a one-dimensional model is reasonable on these scales. Whereas assimilating the full glider data set produces well-constrained simulations, assimilating subsampled glider data at a frequency consistent with cruise-based sampling results in a wide range of primary production and export estimates. These estimates depend strongly on the timing of the assimilated observations, due to the presence of high mesoscale variability in this region. Assimilating surface glider data subsampled at a frequency consistent with available satellite-derived data results in 40 % lower carbon export, primarily
The relationship between volatile halocarbons and phytoplankton pigments during a Trichodesmium bloom in the coastal eastern Arabian Sea

Digital Repository Service at National Institute of Oceanography (India)

Roy, R.; Pratihary, A.; Narvenkar, G.; Mochemadkar, S.; Gauns, M.; Naqvi, S.W.A.

and 5 th April 2007 during regular visits to the Candolim Time Series (CaTS) station G3 located in the eastern Arabian Sea off Goa, India (Figure 1a). In order to investigate the phenomenon in detail and to extend the observations further offshore.... Chemosphere 45, 371-377. 14 Figure Captions Figure 1. a) Sampling locations in the eastern Arabian Sea off Goa; b) picture showing patchy Trichodesmium bloom observed at CaTS station G3. April. Figure 2. MODIS satellite observations from (showing...
An Automatic Monitoring System for High-Frequency Measuring and Real-Time Management of Cyanobacterial Blooms in Urban Water Bodies

Directory of Open Access Journals (Sweden)

Viet Tran Khac

2018-01-01

Full Text Available Urban lakes mitigate the negative impacts on the hydrological cycle and improve the quality of life in cities. Worldwide, the concern increases for the protection and management of urban water bodies. Since the physical-chemical and biological conditions of a small aquatic ecosystem can vary rapidly over time, traditional low frequency measurement approaches (weekly or monthly sampling limits the knowledge and the transfer of research outcomes to management decision-making. In this context, this paper presents an automatic monitoring system including a full-scale experimental site and a data transfer platform for high-frequency observations (every 5 min in a small and shallow urban lake (Lake Champs-sur-Marne, Paris, France, 10.3 ha. Lake stratification and mixing periods can be clearly observed, these periods are compared with the dynamic patterns of chlorophyll-a, phycocyanin, dissolved oxygen and pH. The results indicate that the phytoplankton growth corresponds with dissolved oxygen cycles. However, thermal stratification cannot totally explain the entire dynamic patterns of different physical-chemical and ecological variables. Besides, the cyanobacteria is one of the dominating groups of phytoplankton blooms during the lake stratification periods (8 August–29 September 2016. During the cooling mixed period (29 September–19 October 2016, the high concentration of chlorophyll-a is mainly caused by the other phytoplankton species, such as diatoms. Perspectives are discussed in order to apply this observation system for real-time management of water bodies and lakes.
Phytoplankton and nutrient dynamics in Winyah Bay, SC.

Science.gov (United States)

Boneillo, G. E.; Brooks, S. S.; Brown, S. L.; Woodford, K. M.; Wright, C. R.

2016-02-01

Winyah Bay is a coastal plain estuary located in South Carolina that has been classified for a moderate risk of Eutrophication by NOAA. Winyah Bay receives freshwater input from four rivers, the Waccamaw, Sampit, Black, and Pee Dee Rivers. The Waccamaw, Sampit and Black River are blackwater systems that discharge elevated amounts of colored dissolved organic matter. During the summer and fall of 2015, bioassay experiments were performed to simultaneously examine both light and nutrient (nitrogen & phosphate) limitation throughout Winyah Bay. Sampling stations near the mouth of the Waccamaw and Sampit Rivers showed that phytoplankton were light limited in the late summer instead of nutrient limited. These stations were located in the industrialized area of the bay and typically had the highest nutrient concentrations and highest turbidity, with Secchi depths typically less than 0.5 meters. Results indicated that phytoplankton may be nitrogen limited near the mouth of Winyah Bay, where nutrient concentrations and turbidity were observed to be lower than locations further upstream. There was also an observed dissolved oxygen and pH gradient during the summer of 2015. Dissolved oxygen levels less than 4.0 mg/L were routinely observed near the industrialized head of the estuary and corresponded with lower pH values.
Blooming Artifact Reduction in Coronary Artery Calcification by A New De-blooming Algorithm: Initial Study.

Science.gov (United States)

Li, Ping; Xu, Lei; Yang, Lin; Wang, Rui; Hsieh, Jiang; Sun, Zhonghua; Fan, Zhanming; Leipsic, Jonathon A

2018-05-02

The aim of this study was to investigate the use of de-blooming algorithm in coronary CT angiography (CCTA) for optimal evaluation of calcified plaques. Calcified plaques were simulated on a coronary vessel phantom and a cardiac motion phantom. Two convolution kernels, standard (STND) and high-definition standard (HD STND), were used for imaging reconstruction. A dedicated de-blooming algorithm was used for imaging processing. We found a smaller bias towards measurement of stenosis using the de-blooming algorithm (STND: bias 24.6% vs 15.0%, range 10.2% to 39.0% vs 4.0% to 25.9%; HD STND: bias 17.9% vs 11.0%, range 8.9% to 30.6% vs 0.5% to 21.5%). With use of de-blooming algorithm, specificity for diagnosing significant stenosis increased from 45.8% to 75.0% (STND), from 62.5% to 83.3% (HD STND); while positive predictive value (PPV) increased from 69.8% to 83.3% (STND), from 76.9% to 88.2% (HD STND). In the patient group, reduction in calcification volume was 48.1 ± 10.3%, reduction in coronary diameter stenosis over calcified plaque was 52.4 ± 24.2%. Our results suggest that the novel de-blooming algorithm could effectively decrease the blooming artifacts caused by coronary calcified plaques, and consequently improve diagnostic accuracy of CCTA in assessing coronary stenosis.
Pleurochrysis pseudoroscoffensis (Prymnesiophyceae) blooms on the surface of the Salton Sea, California

Science.gov (United States)

Reifel, K.M.; McCoy, M.P.; Tiffany, M.A.; Rocke, T.E.; Trees, C.C.; Barlow, S.B.; Faulkner, D.J.; Hurlbert, S.H.

2001-01-01

Dense populations of the coccolithophore Pleurochrysis pseudoroscoffensis were found in surface films at several locations around the Salton Sea in February-August, 1999. An unidentified coccolithophorid was also found in low densities in earlier studies of the lake (1955-1956). To our knowledge, this is the first record of this widespread marine species in any lake. Samples taken from surface films typically contained high densities of one or two other phytoplankton species as well as high densities of the coccolithophore. Presence or absence of specific algal pigments was used to validate direct cell counts. In a preliminary screen using a brine shrimp lethality assay, samples showed moderate activity. Extracts were then submitted to a mouse bioassay, and no toxic activity was observed. These results indicate that blooms of P. pseudoroscoffensis are probably not toxic to vertebrates and do not contribute to the various mortality events of birds and fish that occur in the Salton Sea.
The Haber Bosch-harmful algal bloom (HB-HAB) link

Science.gov (United States)

Glibert, Patricia M.; Maranger, Roxane; Sobota, Daniel J.; Bouwman, Lex

2014-10-01

Large-scale commercialization of the Haber-Bosch (HB) process is resulting in intensification of nitrogen (N) fertilizer use worldwide. Globally N fertilizer use is far outpacing that of phosphorus (P) fertilizer. Much of the increase in N fertilizers is also now in the form of urea, a reduced form of N. Incorporation of these fertilizers into agricultural products is inefficient leading to significant environmental pollution and aquatic eutrophication. Of particular concern is the increased occurrence of harmful algal blooms (HABs) in waters receiving nutrient enriched runoff. Many phytoplankton causing HABs have physiological adaptive strategies that make them favored under conditions of elevated N : P conditions and supply of chemically reduced N (ammonium, urea). We propose that the HB-HAB link is a function of (1) the inefficiency of incorporation of N fertilizers in the food supply chain, the leakiness of the N cycle from crop to table, and the fate of lost N relative to P to the environment; and (2) adaptive physiology of many HABs to thrive in environments in which there is excess N relative to classic nutrient stoichiometric proportions and where chemically reduced forms of N dominate. The rate of HAB expansion is particularly pronounced in China where N fertilizer use has escalated very rapidly, where soil retention is declining, and where blooms have had large economic and ecological impacts. There, in addition to increased use of urea and high N : P based fertilizers overall, escalating aquaculture production adds to the availability of reduced forms of N, as does atmospheric deposition of ammonia. HABs in both freshwaters and marginal seas in China are highly related to these overall changing N loads and ratios. Without more aggressive N control the future outlook in terms of HABs is likely to include more events, more often, and they may also be more toxic.
The Haber Bosch–harmful algal bloom (HB–HAB) link

International Nuclear Information System (INIS)

Glibert, Patricia M; Maranger, Roxane; Sobota, Daniel J; Bouwman, Lex

2014-01-01

Large-scale commercialization of the Haber–Bosch (HB) process is resulting in intensification of nitrogen (N) fertilizer use worldwide. Globally N fertilizer use is far outpacing that of phosphorus (P) fertilizer. Much of the increase in N fertilizers is also now in the form of urea, a reduced form of N. Incorporation of these fertilizers into agricultural products is inefficient leading to significant environmental pollution and aquatic eutrophication. Of particular concern is the increased occurrence of harmful algal blooms (HABs) in waters receiving nutrient enriched runoff. Many phytoplankton causing HABs have physiological adaptive strategies that make them favored under conditions of elevated N : P conditions and supply of chemically reduced N (ammonium, urea). We propose that the HB-HAB link is a function of (1) the inefficiency of incorporation of N fertilizers in the food supply chain, the leakiness of the N cycle from crop to table, and the fate of lost N relative to P to the environment; and (2) adaptive physiology of many HABs to thrive in environments in which there is excess N relative to classic nutrient stoichiometric proportions and where chemically reduced forms of N dominate. The rate of HAB expansion is particularly pronounced in China where N fertilizer use has escalated very rapidly, where soil retention is declining, and where blooms have had large economic and ecological impacts. There, in addition to increased use of urea and high N : P based fertilizers overall, escalating aquaculture production adds to the availability of reduced forms of N, as does atmospheric deposition of ammonia. HABs in both freshwaters and marginal seas in China are highly related to these overall changing N loads and ratios. Without more aggressive N control the future outlook in terms of HABs is likely to include more events, more often, and they may also be more toxic. (paper)
Review of suspended sediment in lower South Bay relevant to light attenuation and phytoplankton blooms

Science.gov (United States)

Schoellhamer, David H.; Shellenbarger, Gregory; Downing-Kunz, Maureen; Manning, Andrew J.

2016-01-01

Lower South Bay (LSB), a shallow subembayment of San Francisco Bay (SFB), is situated south of the Dumbarton Bridge, and is surrounded by, and interconnected with, a network of sloughs, marshes, and former salt ponds undergoing restoration (Figure ES.1). LSB receives 120 million gallons per day of treated wastewater effluent from three publicly owned treatment works (POTWs) that service San Jose and the densely populated surrounding region. During the dry season, when flows from creeks and streams are at their minimum, POTW effluent comprises the majority of freshwater flow to Lower South Bay. Although LSB has a large tidal prism, it experiences limited net exchange with the surrounding Bay, because much of the water that leaves on ebb tides returns during the subsequent flood tides. The limited exchange leads to distinctly different biogeochemical conditions in LSB compared to other SFB subembayments, including LSB having the highest nutrient concentrations and highest phytoplankton biomass.
Algal Blooms and Cyanotoxins in Jordan Lake, North Carolina

Directory of Open Access Journals (Sweden)

Daniel Wiltsie

2018-02-01

Full Text Available The eutrophication of waterways has led to a rise in cyanobacterial, harmful algal blooms (CyanoHABs worldwide. The deterioration of water quality due to excess algal biomass in lakes has been well documented (e.g., water clarity, hypoxic conditions, but health risks associated with cyanotoxins remain largely unexplored in the absence of toxin information. This study is the first to document the presence of dissolved microcystin, anatoxin-a, cylindrospermopsin, and β-N-methylamino-l-alanine in Jordan Lake, a major drinking water reservoir in North Carolina. Saxitoxin presence was not confirmed. Multiple toxins were detected at 86% of the tested sites and during 44% of the sampling events between 2014 and 2016. Although concentrations were low, continued exposure of organisms to multiple toxins raises some concerns. A combination of discrete sampling and in-situ tracking (Solid Phase Adsorption Toxin Tracking [SPATT] revealed that microcystin and anatoxin were the most pervasive year-round. Between 2011 and 2016, summer and fall blooms were dominated by the same cyanobacterial genera, all of which are suggested producers of single or multiple cyanotoxins. The study’s findings provide further evidence of the ubiquitous nature of cyanotoxins, and the challenges involved in linking CyanoHAB dynamics to specific environmental forcing factors are discussed.
Algal Blooms and Cyanotoxins in Jordan Lake, North Carolina.

Science.gov (United States)

Wiltsie, Daniel; Schnetzer, Astrid; Green, Jason; Vander Borgh, Mark; Fensin, Elizabeth

2018-02-24

The eutrophication of waterways has led to a rise in cyanobacterial, harmful algal blooms (CyanoHABs) worldwide. The deterioration of water quality due to excess algal biomass in lakes has been well documented (e.g., water clarity, hypoxic conditions), but health risks associated with cyanotoxins remain largely unexplored in the absence of toxin information. This study is the first to document the presence of dissolved microcystin, anatoxin-a, cylindrospermopsin, and β- N -methylamino-l-alanine in Jordan Lake, a major drinking water reservoir in North Carolina. Saxitoxin presence was not confirmed. Multiple toxins were detected at 86% of the tested sites and during 44% of the sampling events between 2014 and 2016. Although concentrations were low, continued exposure of organisms to multiple toxins raises some concerns. A combination of discrete sampling and in-situ tracking (Solid Phase Adsorption Toxin Tracking [SPATT]) revealed that microcystin and anatoxin were the most pervasive year-round. Between 2011 and 2016, summer and fall blooms were dominated by the same cyanobacterial genera, all of which are suggested producers of single or multiple cyanotoxins. The study's findings provide further evidence of the ubiquitous nature of cyanotoxins, and the challenges involved in linking CyanoHAB dynamics to specific environmental forcing factors are discussed.
Algal Blooms and Cyanotoxins in Jordan Lake, North Carolina

Science.gov (United States)

Wiltsie, Daniel; Schnetzer, Astrid; Green, Jason; Vander Borgh, Mark; Fensin, Elizabeth

2018-01-01

The eutrophication of waterways has led to a rise in cyanobacterial, harmful algal blooms (CyanoHABs) worldwide. The deterioration of water quality due to excess algal biomass in lakes has been well documented (e.g., water clarity, hypoxic conditions), but health risks associated with cyanotoxins remain largely unexplored in the absence of toxin information. This study is the first to document the presence of dissolved microcystin, anatoxin-a, cylindrospermopsin, and β-N-methylamino-l-alanine in Jordan Lake, a major drinking water reservoir in North Carolina. Saxitoxin presence was not confirmed. Multiple toxins were detected at 86% of the tested sites and during 44% of the sampling events between 2014 and 2016. Although concentrations were low, continued exposure of organisms to multiple toxins raises some concerns. A combination of discrete sampling and in-situ tracking (Solid Phase Adsorption Toxin Tracking [SPATT]) revealed that microcystin and anatoxin were the most pervasive year-round. Between 2011 and 2016, summer and fall blooms were dominated by the same cyanobacterial genera, all of which are suggested producers of single or multiple cyanotoxins. The study’s findings provide further evidence of the ubiquitous nature of cyanotoxins, and the challenges involved in linking CyanoHAB dynamics to specific environmental forcing factors are discussed. PMID:29495289
Photoreception in Phytoplankton.

Science.gov (United States)

Colley, Nansi Jo; Nilsson, Dan-Eric

2016-11-01

In many species of phytoplankton, simple photoreceptors monitor ambient lighting. Photoreceptors provide a number of selective advantages including the ability to assess the time of day for circadian rhythms, seasonal changes, and the detection of excessive light intensities and harmful UV light. Photoreceptors also serve as depth gauges in the water column for behaviors such as diurnal vertical migration. Photoreceptors can be organized together with screening pigment into visible eyespots. In a wide variety of motile phytoplankton, including Chlamydomonas, Volvox, Euglena, and Kryptoperidinium, eyespots are light-sensitive organelles residing within the cell. Eyespots are composed of photoreceptor proteins and typically red to orange carotenoid screening pigments. This association of photosensory pigment with screening pigment allows for detection of light directionality, needed for light-guided behaviors such as positive and negative phototaxis. In Chlamydomonas, the eyespot is located in the chloroplast and Chlamydomonas expresses a number of photosensory pigments including the microbial channelrhodopsins (ChR1 and ChR2). Dinoflagellates are unicellular protists that are ecologically important constituents of the phytoplankton. They display a great deal of diversity in morphology, nutritional modes and symbioses, and can be photosynthetic or heterotrophic, feeding on smaller phytoplankton. Dinoflagellates, such as Kryptoperidinium foliaceum, have eyespots that are used for light-mediated tasks including phototaxis. Dinoflagellates belonging to the family Warnowiaceae have a more elaborate eye. Their eye-organelle, called an ocelloid, is a large, elaborate structure consisting of a focusing lens, highly ordered retinal membranes, and a shield of dark pigment. This complex eye-organelle is similar to multicellular camera eyes, such as our own. Unraveling the molecular makeup, structure and function of dinoflagellate eyes, as well as light-guided behaviors in
Evolving Phytoplankton Stoichiometry Fueled Diversification of the Marine Biosphere

Directory of Open Access Journals (Sweden)

Antonietta Quigg

2012-05-01

Full Text Available The availability of nutrients and the quantity and quality of food at the base of food webs have largely been ignored in discussions of the Phanerozoic record of biodiversity. We examine the role of nutrient availability and phytoplankton stoichiometry (the relative proportions of inorganic nutrients to carbon in the diversification of the marine biosphere. Nutrient availability and phytoplankton stoichiometry played a critical role in the initial diversification of the marine biosphere during the Neoproterozoic. Initial biosphere expansion during this time resulted in the massive sequestration of nutrients into biomass which, along with the geologically slow input of nutrients from land, set the stage for severe nutrient limitation and relatively constant marine biodiversity during the rest of the Paleozoic. Given the slow nutrient inputs from land and low recycling rates, the growth of early-to-middle Paleozoic metazoans remained limited by their having to expend energy to first “burn off” (respire excess carbon in food before the associated nutrients could be utilized for growth and reproduction; the relative equilibrium in marine biodiversity during the Paleozoic therefore appears to be real. Limited nutrient availability and the consequent nutrient imbalance may have delayed the appearance of more advanced carnivores until the Permo-Carboniferous, when widespread orogeny, falling sea level, the spread of forests, greater weathering rates, enhanced ocean circulation, oxygenation, and upwelling all combined to increase nutrient availability. During the Meso-Cenozoic, rising oxygen levels, the continued nutrient input from land, and, especially, increasing rates of bioturbation, enhanced nutrient availability, increasing the nutrient content of phytoplankton that fueled the diversification of the Modern Fauna.
Phospholipid-derived fatty acids as chemotaxonomic markers for phytoplankton: application for inferring phytoplankton composition

NARCIS (Netherlands)

Dijkman, N.A.; Kromkamp, J.C.

2006-01-01

Phospholipid-derived fatty acids (PLFA) are widely used as chemotaxonomic markers in microbial ecology. In this paper we explore the use of PLFA as chemotaxonomic markers for phytoplankton species. The PLFA composition was determined for 23 species relevant to estuarine phytoplankton. The taxonomic
The dispersal of phytoplankton populations by enhanced turbulent mixing in a shallow coastal sea

Science.gov (United States)

Cross, Jaimie; Nimmo-Smith, W. Alex M.; Hosegood, Philip J.; Torres, Ricardo

2014-08-01

A single tidal cycle survey in a Lagrangian reference frame was conducted in autumn 2010 to evaluate the impact of short-term, episodic and enhanced turbulent mixing on large chain-forming phytoplankton. Observations of turbulence using a free-falling microstructure profiler were undertaken, along with near-simultaneous profiles with an in-line digital holographic camera at station L4 (50° 15‧ N 4° 13‧ W, depth 50 m) in the Western English Channel. Profiles from each instrument were collected hourly whilst following a drogued drifter. Results from an ADCP attached to the drifter showed pronounced vertical shear, indicating that the water column structure consisted of two layers, restricting interpretation of the Lagrangian experiment to the upper ~ 25 m. Atmospheric conditions deteriorated during the mid-point of the survey, resulting in values of turbulent dissipation reaching a maximum of 10- 4 W kg- 1 toward the surface in the upper 10 m. Chain-forming phytoplankton > 200 μm were counted using the data from the holographic camera for the two periods, before and after the enhanced mixing event. As mixing increased phytoplankton underwent chain breakage, were dispersed by advection through their removal from the upper to lower layer and subjected to aggregation with other suspended material. Depth averaged counts of phytoplankton were reduced from a maximum of around 2050 L- 1 before the increased turbulence, to 1070 L- 1 after, with each of these mechanisms contributing to this reduction. These results demonstrate the sensitivity of phytoplantkon populations to moderate increases in turbulent activity, yielding consequences for accurate forecasting of the role played by phytoplankton in climate studies and also for the ecosystem in general in their role as primary producers.
Ocean-Atmosphere Coupling associated with Typhoons/ Hurricane and their impacts on marine ecosystem (Invited)

Science.gov (United States)

Tang, D. L.

2010-12-01

DanLing TANG South China Sea Institute of Oceanology, Chinese Academy of Sciences,Guangzhou, China Phone (86) 13924282728; Fax/Tel: (86) 020 89023203 (off), 020 89023191 (Lab),Email,lingzistdl@126.com, Typhoon / hurricane activities and their impacts on environments have been strengthening in both intensity and spatial coverage, along with global changes in the past several decades; however, our knowledge about impact of typhoon on the marine ecosystem is very scarce. We have conducted a series studies in the South China Sea (SCS), investigating phytoplankton, sea surface temperature (SST), fishery data and related factors before, during, and after typhoon. Satellite remote sensing and in situ observation data obtained from research cruise were applied. Our study showed that typhoon can support nutrients to surface phytoplankton by inducing upwelling and vertical mixing, and typhoon rain can also nourish marine phytoplankton; both typhoon winds and rain can enhance production of marine phytoplankton. Slow-moving typhoon induced phytoplankton blooms of higher Chlorophyll-a (Chl-a), the strong typhoon induced phytoplankton blooms of a large area. We conservatively estimate that typhoon periods may account for 3.5% of the annual primary production in the oligotrophic SCS. It indicated that one typhoon may induce transport of nutrient-rich water from depth and from the coast to offshore regions, nourishing phytoplankton biomass. More observations confirmed that typhoon can induce cold eddy, and cold eddy can support eddy-shape phytoplankton bloom by upwelling. We have suggested a new index to evaluate typhoon impact on marine ecosystem and environment. This is the first time to report moving eddies and eddy-shape phytoplankton blooms associated with tropical cyclone, the relationship among tropical cyclone, cold eddy upwelling and eddy-shape phytoplankton bloom may give some viewpoint on the tropical cyclone's affection on the mesoscale circulation. Those studies may
Trophic role of Protozooplankton in northern marine ecosystems

DEFF Research Database (Denmark)

Riisgaard, Karen

by a strong top-down control by protozooplankton. The data further suggests that deep ocean convection control the protozooplankton community prior to the bloom, which may induce or accelerate the onset of the phytoplankton spring bloom (Paper II & III). 3) In the Arctic Disko Bay, pH was documented...... to increase from 7.5 to 8.5 due to CO2 uptake from phytoplankton as the bloom developed. Microcosm experiments demonstrated that most protists were unaffected by the seasonal changes in pH, even during the massive phytoplankton spring bloom (Paper IV). 4) In a sub-Arctic fjord, field data indicated....... The importance of protozooplankton as grazers increased over a transect going from open-ocean to the inner part of the fjord (Paper V & VI). In conclusion, protozooplankton contributed significantly to the area-specific biomass at all investigated sub-Arctic and Arctic localities with a tendency towards high...
Microcystin in cyanobacterial blooms in a Chilean lake.

Science.gov (United States)

Campos, V; Cantarero, S; Urrutia, H; Heinze, R; Wirsing, B; Neumann, U; Weckesser, J

1999-05-01

Cyanobacterial blooms dominated by Microcystis sp. occurred in lake Rocuant ("marisma", near Concepción/Chile) in February 1995 and 1996. In the bloom samples collected in both years the hepatotoxin microcystin was detected by RP-HPLC in both samples and in the sample of 1995 also by a toxicity assay using primary rat hepatocytes. In the bloom of 1995, the microcystin content of the dry bloom biomass was determined to be 130 micrograms/g on the basis of the RP-HPLC peak area and 800 micrograms/g on the basis of the rat hepatotoxicity assay, respectively. In the bloom of 1996, RP-HPLC analysis revealed a microcystin content of 8.13 micrograms/g bloom material dry weight. In this year no hepatotoxicity was measured using a concentration range up to 0.8 mg (d. w.) of bloom material per ml in the rat hepatotoxicity assay. This is the first report on the detection of microcystins in Chilean water bodies.

A New Bloom: Transforming Learning

Science.gov (United States)

Cochran, David; Conklin, Jack

2007-01-01

This article discusses a new design for the classic Bloom's Taxonomy developed by Anderson, L. W. & Krathwohl, D. (2001), which can be used to evaluate learners' technology-enhanced experience in more powerful and critical ways. The New Bloom's Taxonomy incorporates contemporary research on learning and human cognition into its model. The…
Triclosan alterations of estuarine phytoplankton community structure.

Science.gov (United States)

Pinckney, James L; Thompson, Laura; Hylton, Sarah

2017-06-15

Antimicrobial additives in pharmaceutical and personal care products are a major environmental concern due to their potential ecological impacts on aquatic ecosystems. Triclosan (TCS) has been used as an antiseptic, disinfectant, and preservative in various media. The sublethal and lethal effects of TCS on estuarine phytoplankton community composition were investigated using bioassays of natural phytoplankton communities to measure phytoplankton responses to different concentrations of TCS ranging from 1 to 200μgl -1 . The EC 50 (the concentration of an inhibitor where the growth is reduced by half) for phytoplankton groups (diatoms, chlorophytes, cryptophytes) examined in this ranged from 10.7 to 113.8μg TCS l -1 . Exposures resulted in major shifts in phytoplankton community composition at concentrations as low as 1.0μg TCS l -1 . This study demonstrates estuarine ecosystem sensitivity to TCS exposure and highlights potential alterations in phytoplankton community composition at what are typically environmental concentrations of TCS in urbanized estuaries. Copyright © 2017 Elsevier Ltd. All rights reserved.
Dynamics of a cyanobacterial bloom in a hypereutrophic reservoir ...

African Journals Online (AJOL)

Blooming and non-blooming periods between 2004 and 2006 in a hypereutrophic reservoir, where cyanobacterial blooms have previously been reported to be permanent, presented an opportunity to characterise factors that may favour cyanobacterial dominance. As a bloom developed in May 2004, a shift to dominance by ...
Response patterns of phytoplankton growth to variations in resuspension in the German Bight revealed by daily MERIS data in 2003 and 2004

Directory of Open Access Journals (Sweden)

Jian Su

2015-10-01

Full Text Available Chlorophyll (chl a concentration in coastal seas exhibits variability on various spatial and temporal scales. Resuspension of particulate matter can somewhat limit algal growth, but can also enhance productivity because of the intrusion of nutrient-rich pore water from sediments or bottom water layers into the whole water column. This study investigates whether characteristic changes in net phytoplankton growth can be directly linked to resuspension events within the German Bight. Satellite-derived chl a were used to derive spatial patterns of net rates of chl a increase/decrease (NR in 2003 and 2004. Spatial correlations between NR and mean water column irradiance were analysed. High correlations in space and time were found in most areas of the German Bight (R2 > 0.4, suggesting a tight coupling between light availability and algal growth during spring. These correlations were reduced within a distinct zone in the transition between shallow coastal areas and deeper offshore waters. In summer and autumn, a mismatch was found between phytoplankton blooms (chl a > 6 mg m−3 and spring-tidal induced resuspension events as indicated by bottom velocity, suggesting that there is no phytoplankton resuspension during spring tides. It is instead proposed here that frequent and recurrent spring-tidal resuspension events enhance algal growth by supplying remineralized nutrients. This hypothesis is corroborated by a lag correlation analysis between resuspension events and in-situ measured nutrient concentrations. This study outlines seasonally different patterns in phytoplankton productivity in response to variations in resuspension, which can serve as a reference for modelling coastal ecosystem dynamics.
Effect of Phytoplankton Richness on Phytoplankton Biomass Is Weak Where the Distribution of Herbivores is Patchy.

Science.gov (United States)

Weis, Jerome J

2016-01-01

Positive effects of competitor species richness on competitor productivity can be more pronounced at a scale that includes heterogeneity in 'bottom-up' environmental factors, such as the supply of limiting nutrients. The effect of species richness is not well understood in landscapes where variation in 'top-down' factors, such as the abundance of predators or herbivores, has a strong influence competitor communities. I asked how phytoplankton species richness directly influenced standing phytoplankton biomass in replicate microcosm regions where one patch had a population of herbivores (Daphnia pulicaria) and one patch did not have herbivores. The effect of phytoplankton richness on standing phytoplankton biomass was positive but weak and not statistically significant at this regional scale. Among no-Daphnia patches, there was a significant positive effect of phytoplankton richness that resulted from positive selection effects for two dominant and productive species in polycultures. Among with-Daphnia patches there was not a significant effect of phytoplankton richness. The same two species dominated species-rich polycultures in no- and with-Daphnia patches but both species were relatively vulnerable to consumption by Daphnia. Consistent with previous studies, this experiment shows a measurable positive influence of primary producer richness on biomass when herbivores were absent. It also shows that given the patchy distribution of herbivores at a regional scale, a regional positive effect was not detected.
Grazing, egg production, and biochemical evidence of differences in the life strategies of Calanus finmarchicus, C. glacialis and C. hyperboreus in Disko Bay, western Greenland

DEFF Research Database (Denmark)

Swalethorp, Rasmus; Kjellerup, Sanne; Dünweber, Michael

2011-01-01

. glacialis ascended to the surface layer at the onset of the spring phytoplankton bloom, followed by C. hyperboreus 2 wk later. C. finmarchicus spawning occurred during the bloom and post-bloom period, partially fueled by wax esters. C. glacialis commenced spawning before the bloom, yet it was greatly...
Global Ocean Phytoplankton

Science.gov (United States)

Franz, B. A.; Behrenfeld, M. J.; Siegel, D. A.; Werdell, P. J.

2014-01-01

Marine phytoplankton are responsible for roughly half the net primary production (NPP) on Earth, fixing atmospheric CO2 into food that fuels global ocean ecosystems and drives the ocean's biogeochemical cycles. Phytoplankton growth is highly sensitive to variations in ocean physical properties, such as upper ocean stratification and light availability within this mixed layer. Satellite ocean color sensors, such as the Sea-viewing Wide Field-of-view Sensor (SeaWiFS; McClain 2009) and Moderate Resolution Imaging Spectroradiometer (MODIS; Esaias 1998), provide observations of sufficient frequency and geographic coverage to globally monitor physically-driven changes in phytoplankton distributions. In practice, ocean color sensors retrieve the spectral distribution of visible solar radiation reflected upward from beneath the ocean surface, which can then be related to changes in the photosynthetic phytoplankton pigment, chlorophyll- a (Chla; measured in mg m-3). Here, global Chla data for 2013 are evaluated within the context of the 16-year continuous record provided through the combined observations of SeaWiFS (1997-2010) and MODIS on Aqua (MODISA; 2002-present). Ocean color measurements from the recently launched Visible and Infrared Imaging Radiometer Suite (VIIRS; 2011-present) are also considered, but results suggest that the temporal calibration of the VIIRS sensor is not yet sufficiently stable for quantitative global change studies. All MODISA (version 2013.1), SeaWiFS (version 2010.0), and VIIRS (version 2013.1) data presented here were produced by NASA using consistent Chla algorithms.
Bacterial community composition of size-fractioned aggregates within the phycosphere of cyanobacterial blooms in a eutrophic freshwater lake.

Directory of Open Access Journals (Sweden)

Haiyuan Cai

Full Text Available Bacterial community composition of different sized aggregates within the Microcystis cyanobacterial phycosphere were determined during summer and fall in Lake Taihu, a eutrophic lake in eastern China. Bloom samples taken in August and September represent healthy bloom biomass, whereas samples from October represent decomposing bloom biomass. To improve our understanding of the complex interior structure in the phycosphere, bloom samples were separated into large (>100 µm, medium (10-100 µm and small (0.2-10 µm size aggregates. Species richness and library coverage indicated that pyrosequencing recovered a large bacterial diversity. The community of each size aggregate was highly organized, indicating highly specific conditions within the Microcystis phycosphere. While the communities of medium and small-size aggregates clustered together in August and September samples, large- and medium-size aggregate communities in the October sample were grouped together and distinct from small-size aggregate community. Pronounced changes in the absolute and relative percentages of the dominant genus from the two most important phyla Proteobacteria and Bacteroidetes were observed among the various size aggregates. Bacterial species on large and small-size aggregates likely have the ability to degrade high and low molecular weight compounds, respectively. Thus, there exists a spatial differentiation of bacterial taxa within the phycosphere, possibly operating in sequence and synergy to catalyze the turnover of complex organic matters.
Jellyfish blooms in China: Dominant species, causes and consequences

International Nuclear Information System (INIS)

Dong Zhijun; Liu Dongyan; Keesing, John K.

2010-01-01

Three jellyfish species, Aurelia aurita, Cyanea nozakii and Nemopilema nomurai, form large blooms in Chinese seas. We report on the distribution and increasing incidence of jellyfish blooms and their consequences in Chinese coastal seas and analyze their relationship to anthropogenically derived changes to the environment in order to determine the possible causes. A. aurita, C. nozakii and N. nomurai form blooms in the temperate Chinese seas including the northern East China Sea, Yellow Sea and Bohai Sea. N. nomurai forms offshore blooms while the other two species bloom mainly in inshore areas. Eutrophication, overfishing, habitat modification for aquaculture and climate change are all possible contributory factors facilitating plausible mechanisms for the proliferation of jellyfish blooms. In the absence of improvement in coastal marine ecosystem health, jellyfish blooms could be sustained and may even spread from the locations in which they now occur.
Spatial and temporal variability of chlorophyll and primary productivity in surface waters of southern Chile (41.5 43° S)

Science.gov (United States)

Iriarte, J. L.; González, H. E.; Liu, K. K.; Rivas, C.; Valenzuela, C.

2007-09-01

The southern fjord region of Chile is a unique ecosystem characterized by complex marine-terrestrial-atmospheric interactions that result in high biological production. Since organic nitrogen from terrestrial and atmospheric compartments is highly significant in this region (>40%), as is the low NO 3:PO 4 ratio in surface waters, it is suggested that fertilization from inorganic and organic nitrogen sources has a strong influence on both phytoplankton biomass/primary production and harmful algae bloom dynamics. The data presented in this paper provide an opportunity to improve our knowledge of phytoplankton dynamics on temporal and spatial mesoscales. Ocean color data from NASA (SeaWiFS) for chlorophyll and primary production estimates and in situ surface measurement of inorganic nutrients, phytoplankton biomass, and primary productivity revealed that the coastal waters of southern Chile have a classical spring and autumn chlorophyll bloom cycle in which primary production is co-limited by strong seasonal changes in light and nitrate. During spring blooms, autotrophic biomass (such as chlorophyll a, Chl- a) and primary production estimates reached 25 mg Chl- a m -3 and 23 mg C m -3 h -1, respectively, and micro-phytoplankton accounted for a significant portion of the biomass (60%) in spring. The contribution of phytoplankton size classes to total chlorophyll a revealed the dominance of nanoplankton (>50%) in winter and post-bloom periods (<1.0 mg Chl- a m -3).
Towards an Understanding of the Interactions between Freshwater Inflows and Phytoplankton Communities in a Subtropical Estuary in the Gulf of Mexico.

Directory of Open Access Journals (Sweden)

Samuel Dorado

Full Text Available Subtropical estuaries worldwide face increased pressure on their ecosystem health and services due to increasing human population growth and associated land use/land cover changes, expansion of ports, and climate change. We investigated freshwater inflows (river discharge and the physico-chemical characteristics of Galveston Bay (Texas, USA as mechanisms driving variability in phytoplankton biomass and community composition between February 2008 and December 2009. Results of multivariate analyses (hierarchical cluster analysis, PERMANOVA, Mantel test, and nMDS ordination coupled to environmental vector fitting revealed that temporal and spatial differences in phytoplankton community structure correlate to differences in hydrographic and water quality parameters. Spatially, phytoplankton biomass and community composition responded to nutrient loading from the San Jacinto River in the northwest region of the bay (consistent with nutrient limitation while hydraulic displacement (and perhaps other processes resulted in overall lower biomass in the Trinity River delta (northeast region. The influence of inflows on phytoplankton diminished along a north to south gradient in the bay. Temporally, temperature and variables associated with freshwater inflow (discharge volume, salinity, inorganic nitrogen and phosphorus concentrations were major influences on phytoplankton dynamics. Dissolved inorganic nitrogen: phosphorus (DIN:DIP ratios suggest that phytoplankton communities will be predominately nitrogen limited. Diatoms dominated during periods of moderate to high freshwater inflows in winter/spring and were more abundant in the upper bay while cyanobacteria dominated during summer/fall when inflow was low. Given the differential influences of freshwater inflow on the phytoplankton communities of Galveston Bay, alterations upstream (magnitude, timing, frequency will likely have a profound effect on downstream ecological processes and corresponding
Occurrence and biosynthesis of carotenoids in phytoplankton.

Science.gov (United States)

Huang, Jim Junhui; Lin, Shaoling; Xu, Wenwen; Cheung, Peter Chi Keung

2017-09-01

Naturally occurring carotenoids are important sources of antioxidants, anti-cancer compounds and anti-inflammatory agents and there is thus considerable market demand for their pharmaceutical applications. Carotenoids are widely distributed in marine and freshwater organisms including microalgae, phytoplankton, crustaceans and fish, as well as in terrestrial plants and birds. Recently, phytoplankton-derived carotenoids have received much attention due to their abundance, rapid rate of biosynthesis and unique composition. The carotenoids that accumulate in particular phytoplankton phyla are synthesized by specific enzymes and play unique physiological roles. This review focuses on studies related to the occurrence of carotenoids in different phytoplankton phyla and the molecular aspects of their biosynthesis. Recent biotechnological advances in the isolation and characterization of some representative carotenoid synthases in phytoplankton are also discussed. Copyright © 2017 Elsevier Inc. All rights reserved.
Is reduced benthic flux related to the Diporeia decline? Analysis of spring blooms and whiting events in Lake Ontario

Science.gov (United States)

Watkins, James M.; Rudstam, Lars G.; Crabtree, Darran L.; Walsh, Maureen

2013-01-01

Benthic monitoring by USGS off the southern shore of Lake Ontario from October 1993 to October 1995 provides a detailed view of the early stages of the decline of the native amphipod Diporeia. A loss of the 1994 and 1995 year classes of Diporeia preceded the disappearance of the native amphipod at sites near Oswego and Rochester at depths from 55 to 130 m. In succeeding years, Diporeia populations continued to decline in Lake Ontario and were nearly extirpated by 2008. Explanations for Diporeia 's decline in the Great Lakes include several hypotheses often linked to the introduction and expansion of exotic zebra and quagga mussels (Dreissena sp.). We compare the timeline of the Diporeia decline in Lake Ontario with trends in two sources of organic matter to the sediments — spring diatom blooms and late summer whiting events. The 1994–95 decline of Diporeia coincided with localized dreissenid effects on phytoplankton in the nearshore and a year (April 1994 to May 1995) of decreased flux of organic carbon recorded by sediment traps moored offshore of Oswego. Later declines of profundal (> 90 m) Diporeia populations in 2003 were poorly associated with trends in spring algal blooms and late summer whiting events. Lake Ontario/Diporeia/Dreissena/remote sensing.
The Community Structure of Phytoplankton in Seagrass Ecosystem and its Relationship with Environmental Characterstics

Directory of Open Access Journals (Sweden)

Gede Iwan Setiabudi

2016-12-01

Full Text Available The aimed of this study was to determine the plankton communities and its relationship with the chemical and physical condition in seagrass ecosystem at Pegametan Bay. The composition and abundance of plankton were observed in the sea water underneath the surface and were identified based on the guideline of Illustration of the Marine Plankton of Japan. The water quality was measured in situ using WQC HI 9829. The water sample was measured using closed reflux spectrometry for COD, TOC analyzer for DOC and APHA 2102 (4500 method for Nt and Pt. There are 27 species of plankton identified, which can be classified into three groups. Diatom group consists of 18 species with a 74.56% abundance. The non-litoral group consists of 6 species with a 23.35% abundance. Moreover, dinoflagellate group consist of 3 species with a 2.09% abundance. An abundance of plankton greater than 104 cell.L-1 was found in diatome group (Nitzschia sp., Thalassiosira sp., Chaetoceros sp., Flagillaria sp., Thalassiothrix sp., and Melosira sp. and non-litoral group (Oscillatoria sp. and Spirogyra sp.. The abundance of those species indicated the algae bloom phenomenon. Dinophysis sp. was also identified, which was harmful algal blooms.How to CiteSetiabudi, G. I., Bengen, D. G., Effendi, H., & Radjasa, O. K. (2016. The Community Structure of Phytoplankton in Seagrass Ecosystem and its Relationship with Environmental Characterstics. Biosaintifika: Journal of Biology & Biology Education, 8(3, 257-269.
State of Climate 2011 - Global Ocean Phytoplankton

Science.gov (United States)

Siegel, D. A.; Antoine, D.; Behrenfeld, M. J.; d'Andon, O. H. Fanton; Fields, E.; Franz, B. A.; Goryl, P.; Maritorena, S.; McClain, C. R.; Wang, M.;

2012-01-01

Phytoplankton photosynthesis in the sun lit upper layer of the global ocean is the overwhelmingly dominant source of organic matter that fuels marine ecosystems. Phytoplankton contribute roughly half of the global (land and ocean) net primary production (NPP; gross photosynthesis minus plant respiration) and phytoplankton carbon fixation is the primary conduit through which atmospheric CO2 concentrations interact with the ocean s carbon cycle. Phytoplankton productivity depends on the availability of sunlight, macronutrients (e.g., nitrogen, phosphorous), and micronutrients (e.g., iron), and thus is sensitive to climate-driven changes in the delivery of these resources to the euphotic zone

Optical assessment of phytoplankton nutrient depletion

DEFF Research Database (Denmark)

Heath, M.R.; Richardson, Katherine; Kiørboe, Thomas

1990-01-01

The ratio of light absorption at 480 and 665 nm by 90% acetone extracts of marine phytoplankton pigments has been examined as a potential indicator of phytoplankton nutritional status in both laboratory and field studies. The laboratory studies demonstrated a clear relationship between nutritiona......-replete and nutrient-depleted cells. The field data suggest that the absorption ratio may be a useful indicator of nutritional status of natural phytoplankton populations, and can be used to augment the interpretation of other data....
Are Low Salinity Waters the Remedy to Noctiluca scintillans Blooms in the Arabian Sea?

Science.gov (United States)

Gibson, J.

2017-12-01

Noctiluca scintillans (Noctiluca) is a mixotrophic, green dinoflagellate that for the past two decades has been producing problematic algal blooms in the Arabian Sea (AS). As a mixotroph, Noctiluca obtains energy from both consumption of phytoplankton as well as its intracellular photosynthesizing endosymbionts named, Pedinomonas noctilucae. It is this autotrophic and heterotrophic dual capability that has largely enabled Noctiluca to be a highly dominant species at the planktonic trophic layer in the AS. Exacerbated by non-point source/point-source pollution in the AS, ocean acidification, and intensified monsoons, Noctiluca currently algal blooms can be as big as three times the size of Texas. By depleting the AS of oxygen, clogging the gills of fish, and altering the AS food web, these algal blooms result in mass fish die offs. In turn this propagates financial and food insecurity issues in countless coastal communities. However, through satellite imaging over the years, it has been observed that the proliferation of Noctiluca is precluded or encounters a "wall" about mid-way along the west coast of India. It is theorized that this "wall" is due to a significant change in salinity. Snow from atop the Himalayan Mountains melts and adds fresh water to the Bay of Bengal (BB), and in winter the East Indian Coastal Current (EICC) carries this fresher water around the southern tip of India and towards the AS. It is believed that this dilution effect impedes the growth of Noctiluca further south. Ultimately, in this study the salinity gradient from the Bay of Bengal (BB) around the horn of India into the AS was replicated in six pairs of culture bottles. Noctiluca was grown in six different salinities including 26, 28, 30, 32, 34, and 38 psu. Algae grown in the 34 and 38 psu bottles, were healthier and 38 psu treated Noctiluca provided optimal conditions for its photosynthesizing endosymbionts. Noctiluca does not grow well at lower salinities, thus applications of low
Photosynthetic parameters and primary production, with focus on large phytoplankton, in a temperate mid-shelf ecosystem

KAUST Repository

Moran, Xose Anxelu G.

2015-01-09

Annual variability of photosynthetic parameters and primary production (PP), with a special focus on large (i.e. >2μm) phytoplankton was assessed by monthly photosynthesis-irradiance experiments at two depths of the southern Bay of Biscay continental shelf in 2003. Integrated chl a (22-198mgm-2) was moderately dominated by large cells on an annual basis. The March through May dominance of diatoms was replaced by similar shares of dinoflagellates and other flagellates during the rest of the year. Variability of photosynthetic parameters was similar for total and large phytoplankton, but stratification affected the initial slope αB [0.004-0.049mgCmg chl a-1h-1 (μmol photons m-2s-1)-1] and maximum photosynthetic rates PmB (0.1-10.7mgCmg chl a-1h-1) differently. PmB, correlated positively with αB only for the large fraction. PmB tended to respond faster to ambient irradiance than αB, which was negatively correlated with diatom abundance in the >2μm fraction. Integrated PP rates were relatively low, averaging 387 (132-892) for the total and 207 (86-629) mg C m-2d-1 for the large fraction, probably the result of inorganic nutrient limitation. Although similar mean annual contributions of large phytoplankton to total values were found for biomass and PP (~58%), water-column production to biomass ratios (2-26mgCmg chl-1d-1) and light utilization efficiency of the >2μm fraction (0.09-0.84gCg chl-1mol photons-1m2) were minimum during the spring bloom. Our results indicate that PP peaks in the area are not necessarily associated to maximum standing stocks.
Photosynthetic parameters and primary production, with focus on large phytoplankton, in a temperate mid-shelf ecosystem

KAUST Repository

Moran, Xose Anxelu G.; Scharek, Renate

2015-01-01

Annual variability of photosynthetic parameters and primary production (PP), with a special focus on large (i.e. >2μm) phytoplankton was assessed by monthly photosynthesis-irradiance experiments at two depths of the southern Bay of Biscay continental shelf in 2003. Integrated chl a (22-198mgm-2) was moderately dominated by large cells on an annual basis. The March through May dominance of diatoms was replaced by similar shares of dinoflagellates and other flagellates during the rest of the year. Variability of photosynthetic parameters was similar for total and large phytoplankton, but stratification affected the initial slope αB [0.004-0.049mgCmg chl a-1h-1 (μmol photons m-2s-1)-1] and maximum photosynthetic rates PmB (0.1-10.7mgCmg chl a-1h-1) differently. PmB, correlated positively with αB only for the large fraction. PmB tended to respond faster to ambient irradiance than αB, which was negatively correlated with diatom abundance in the >2μm fraction. Integrated PP rates were relatively low, averaging 387 (132-892) for the total and 207 (86-629) mg C m-2d-1 for the large fraction, probably the result of inorganic nutrient limitation. Although similar mean annual contributions of large phytoplankton to total values were found for biomass and PP (~58%), water-column production to biomass ratios (2-26mgCmg chl-1d-1) and light utilization efficiency of the >2μm fraction (0.09-0.84gCg chl-1mol photons-1m2) were minimum during the spring bloom. Our results indicate that PP peaks in the area are not necessarily associated to maximum standing stocks.
Importance of climate change-physical forcing on the increase of cyanobacterial blooms in a small, stratified lake

Directory of Open Access Journals (Sweden)

Dolores Planas

2016-03-01

Full Text Available The community structure of planktonic cyanobacteria was studied in a dimictic lake in which recurrent summer surface algal blooms have frequently occurred since the beginning of this millennium. In eutrophic-hypereutrophic lakes, epilimnetic cyanobacterial blooms are promoted by increased ambient temperatures and water column thermal stability, which favour the vertical migration of buoyancy-regulating cyanobacteria. Here we propose that intensified external energy (wind that alters thermocline stability could explain the occurence of heavy blooms in the surface of lakes with low external nutrient loading. Specifically, we hypothesized that: i in small stratified lakes with low external nutrient sources, cyanobacterial growth primarily occurs near the lake bottom, where phosphorus is more abundant and light is available; ii we additionally hypothesized that turbulence induced by strong winds increases the amplitude and energy of metalimnetic internal waves and entrains meta- and hypolimnetic water, rich in nutrients and cyanobacteria, into the epilimnion. The study was done in a small lake (45 Ha, maximum and mean depth 7.2 m and 4.3 m, respectively with mean epilimnetic dissolved phosphorus concentrations ≈ 4 μg L-1 and chlorophyll α ≈ 8 μg L-1. Vertical temperature profiles during the open season were continuously registered using thermistors. Weekly vertical profiles of light transmission, phytoplankton distribution and water chemistry were also taken. On one occasion, these variables were measured throughout a continuous 24 h cycle. Results demonstrated that summer cyanobacterial blooms were dominated by Plankthotrix spp., which began their cycle in late spring at the bottom of the lake, and grew to form dense metalimnetic biomass peaks. Time series analysis of isotherms and the Lake number indicated that internal metalimnetic waves (seiches were present through the summer. During the diel sampling cycle, we found that medium to

Tolerance of polar phytoplankton communities to metals

International Nuclear Information System (INIS)

Echeveste, P.; Tovar-Sánchez, A.; Agustí, S.

2014-01-01

Large amounts of pollutants reach polar regions, particularly the Arctic, impacting their communities. In this study we analyzed the toxic levels of Hg, Cd and Pb to natural phytoplankton communities of the Arctic and Southern Oceans, and compared their sensitivities with those observed on phytoplankton natural communities from temperate areas. Mercury was the most toxic metal for both Arctic and Antarctic communities, while both Cd and Pb were toxic only for the Antarctic phytoplankton. Total cell abundance of the populations forming the Arctic community increased under high Cd and Pb concentrations, probably due to a decrease of the grazing pressure or the increase of the most resistant species, although analysis of individual cells indicated that cell death was already induced at the highest levels. These results suggest that phytoplankton may have acquired adapting mechanisms to face high levels of Pb and Cd in the Arctic Ocean. Highlights: • First study analyzing the toxicity of Hg, Cd or Pb to natural polar phytoplankton. • Arctic Ocean communities highly resistant to Cd and Pb, but not to Hg. • Southern Ocean communities sensitive to Cd, Pb and Hg. • Both communities incorporated Pb at a similar level. • Arctic phytoplankton may have acquired adapting mechanisms against Cd and Pb. -- Polar phytoplankton communities are tolerant to Cd and Pb, specially the Arctic ones, suggesting the acquisition of adapting mechanisms to face metals' toxicity
Phytoplankton Monitoring Network - Phytoplankton Analysis with Associated Collection Information

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A qualitative collection of data that includes salinity, temperature, phytoplankton counts and abundance ratios obtained from surface tows in the estuarine and...
Indicators: Phytoplankton

Science.gov (United States)

Phytoplankton are free-floating, microscopic algae that inhabit the sunlit, upper layer of most freshwater and marine environments. They are usually responsible for the color and clarity of lakes, wetlands, rivers, streams and estuaries.
Succession of phytoplankton assemblages in relation to estuarine hydrodynamics in the Ría de Vigo: a box-model approach

Directory of Open Access Journals (Sweden)

Belén Martín Miguez

2001-07-01

Full Text Available Two phytoplankton succession events (September-October 1993 and March 1994 in the Ría de Vigo were studied in relation to their hydrodynamic context. By means of a circulation box model we calculated horizontal and vertical residual fluxes as well as budgets of phytoplankton associated with them. This allowed us to assess the importance of the two factors involved in the selection processes: one hydrodynamic (dependent upon physical dispersion and one biogeochemical (involving all other processes such as growth, mortality and grazing. The first period was characterised by a downwelling event which produced a reversal of the estuarine circulation pattern (horizontal velocity = 4 km d-1 and downward velocities up to 9 m d-1. This provided suitable conditions for the blooming of Gymnodinium catenatum favoured by its capacity to swim, while the diatom community almost disappeared. The second period corresponded to an upwelling Æ relaxation sequence. During upwelling (horizontal velocity = 6 km d-1; upward velocities up to 12 m d-1, Thalassiosira spp. was dominant. It is suggested that the less energetic conditions associated with the relaxation event (horizontal velocity=1 km d-1; upward velocities < 1 m d-1 favoured the selection of Chatoceros spp. due to its lower sinking rate.
Deep winter convection and phytoplankton dynamics in the NW Mediterranean Sea under present climate and future (horizon 2030) scenarios.

Science.gov (United States)

Macias, Diego; Garcia-Gorriz, Elisa; Stips, Adolf

2018-04-26

Deep water convection (DC) in winter is one of the major processes driving open-ocean primary productivity in the Northwestern Mediterranean Sea. DC is highly variable in time, depending on the specific conditions (stratification, circulation and ocean-atmosphere interactions) of each specific winter. This variability also drives the interannual oscillations of open-ocean primary productivity in this important region for many commercially-important fish species. We use a coupled model system to 1) understand to what extent DC impacts phytoplankton seasonality in the present-day and 2) to explore potential changes in future scenarios (~2030). Our model represents quite accurately the present-day characteristics of DC and its importance for open-ocean phytoplankton blooms. However, for the future scenarios the importance of deep nutrients in fertilizing the euphotic layer of the NW Mediterranean decreases. The model simulates changes in surface density and on the levels of kinetic energy that make mesoscale activity associated with horizontal currents to become a more important fertilization mechanism, inducing subsequently phenological changes in seasonal plankton cycles. Because of our focus on the open-sea, an exact quantification of the impact of those changes on the overall biological production of the NW Mediterranean cannot be made at the moment.
The paradox of algal blooms in oligotrophic waters

Science.gov (United States)

Sundareshwar, P. V.; Upadhyay, S.; Abessa, M. B.; Honomichl, S.; Berdanier, B.; Spaulding, S.; Sandvik, C.; Trennepohl, A.

2010-12-01

Nutrient inputs to streams and lakes, primarily from anthropogenic sources, lead to eutrophic conditions that favor algal blooms with undesirable consequences. In contrast, low nutrient or oligotrophic waters rarely support algal blooms; such ecosystems are typically lower in productivity. Since the mid-1980’s however, the diatom Didymosphenia geminata has dramatically expanded its range colonizing oligotrophic rivers worldwide with blooms appearing as thick benthic mats. This recent global occurrence of Didymosphenia geminata blooms in temperate rivers has been perplexing in its pace of spread and the paradoxical nature of the nuisance growths. The blooms occur primarily in oligotrophic flowing waters, where phosphorus (P) availability often limits primary production. We present a biogeochemical process by which D. geminata mats adsorb both P and iron (Fe) from flowing waters and make P available for cellular uptake. The adsorbed P becomes bioavailable through biogeochemical processes that occur within the mat. The biogeochemical processes observed here while well accepted in benthic systems are novel for algal blooms in lotic habits. Enzymatic and bacterial processes such as Fe and sulfate reduction can release the adsorbed P and increase its bioavailability, creating a positive feedback between total stalk biomass and nutrient availability. Stalk affinity for Fe, Fe-P biogeochemistry, and interaction between watershed processes and climatic setting explain the paradoxical blooms, and the recent global spread of this invasive aquatic species. At a broader scale the study also implies that such algal blooms in oligotrophic environments can fundamentally alter the retention and longitudinal transfer of important nutrients such as P in streams and rivers.
On the offshore dispersal of the Amazon's Plume in the North Atlantic: Comments on the paper by A. Longhurst, ``Seasonal cooling and blooming in tropical oceans''

Science.gov (United States)

Muller-Karger, F. E.; Richardson, P. L.; Mcgillicuddy, D.

1995-11-01

Coastal Zone Color Scanner (CZCS) satellite images show extensive plumes of discolored water extending from South America into the western tropical Atlantic. The most conspicuous plumes originate at the mouths of the Amazon and Orinoco Rivers, and plumes originating at smaller rivers can also be seen from space. In a recent paper by Longhurst (1993), the plume associated with the Amazon River was attributed to phytoplankton blooms stimulated by nutrients supplied via eddy upwelling. We revisit the argument that this plume is of riverine origin, and offer evidence that material present near continental margins can be advected offshore and trace circulation patterns in the adjacent ocean.
PHYTOPLANKTON OF CASPIAN

Directory of Open Access Journals (Sweden)

Aysha Sharapatinovna Gasanova

2015-01-01

Full Text Available Aim. The composition of the species of the phytoplankton in the Russian sector of the Caspian Sea in conditions of transgression, anthropogenic and chemical contamination has been studied.Location.The Russian sector of the Caspian SeaMethods. The phytoplankton samples were collected at the depths of 8 – 50m by the use of the Nansen bathometer and subsequently were fixed in 4% formalin. The office processing was carried out in a box of Nozhotta type, which has the volume of 0.1 ml and the triplicate surface, under the light microscope of Biolam P15. The system of domestic diamotologists was used during the classification of Bacillariaphyta, as for the classification of Dinophyta, the Dodge scheme was applied. Cyanophyta algae were classified according to the system of A.A. Elenkina with the amendments adopted by A.I. Proshkin-Lavrenko and V.V. Makarova. The classification of the Chlorophyta division has been done according to the Smith system.Results, main conclusions. Presented the taxonomic structure and the lists of species of the phytoplankton community in the sea coastal shallow waters Russian sector of the Caspian Sea have been presented. A high floristic diversity and domination of small cell forms are characteristics of the modern structure of the coastal shoal waters of the Dagestan part of the Caspian Sea. The auttaclimatizant of 1934, Pseudosolenia calcaravis, has not been discovered in the plankton of the researched water area. The phytoplankton community has been represented by 58 species of six groups: Cyanophyta, Bacillariaphyta, Dinophyta, Euglenophyta, Chlorophyta and the small flagellate. Bacillariaphyta were the basis of both the taxonomic diversity and the biomass. Cyanophita prevailed in number.
Response of the phytoplankton community to water quality in a local alpine glacial lake of Xinjiang Tianchi, China: potential drivers and management implications.

Science.gov (United States)

Lu, Xiaotian; Song, Shuai; Lu, Yonglong; Wang, Tieyu; Liu, Zhaoyang; Li, Qifeng; Zhang, Meng; Suriyanarayanan, Sarvajayakesavalu; Jenkins, Alan

2017-10-18

Eutrophication has become one of the most serious threats to aquatic ecosystems in the world. With the combined drivers of climate change and human activities, eutrophication has expanded from warm shallow lakes to cold-water lakes in relatively high latitude regions and has raised greater concerns over lake aquatic ecosystem health. A two-year field study was carried out to investigate water quality, phytoplankton characteristics and eutrophication status in a typical alpine glacial lake of Tianchi, a scenic area and an important drinking water source in the Xinjiang Autonomous Region of China, in 2014 and 2015. Clear seasonal and annual variations of nutrients and organic pollutants were found especially during rainy seasons. For the phytoplankton community, Bacillariophyta held the dominant position in terms of both species and biomass throughout the year, suggesting the dominant characteristics of diatoms in the phytoplankton structure in such a high-altitude cold-water lake. This was quite different from plain and warm lakes troubled with cyanobacterial blooming. Moreover, the dominant abundance of Cyclotella sp. in Tianchi might suggest regional warming caused by climate change, which might have profound effects on the local ecosystems and hydrological cycle. Based on water quality parameters, a comprehensive trophic level index TLI (Σ) was calculated to estimate the current status of eutrophication, and the results inferred emerging eutrophication in Tianchi. Results from Canonical Correspondence Analysis (CCA) and correlation analysis of phytoplankton genera and physico-chemical variables of water indicated that abiotic factors significantly influenced the phytoplankton community and its succession in Tianchi Lake. These abiotic factors could explain 77.82% of the total variance, and ammonium was identified as the most discriminant variable, which could explain 41% of the total variance followed by TP (29%). An estimation of annual nutrient loadings to
Phytoplankton Assessment in Danube Delta Biosphere Reserve

Directory of Open Access Journals (Sweden)

SPIRIDON Cosmin

2016-12-01

Full Text Available The term ”plankton” refers to those microscopic aquatic forms having little or no resistance to currents and living free-floating and suspended, in open or pelagic waters. Phytoplankton development has different consequences depending on biomass quality and quantity, the overgrowth result being eutrophication process. The eutrophication intensity can cause both a lower water transparency, by excessive algal growth, to fish death in the area. In this study, it was presented the ecological status and phytoplankton biomass dynamic, in the Danube branches from upstream to downstream. The measurements have been made in 2013, in March, June, September and November, using spectrofluorometer for algal biomass determination and a microscope for qualitative analyses of phytoplankton species. Shannon-Wiener index was calculated to compare phytoplankton species diversity. Also, the biodegradable organic matter loading the ecosystem was determined by computing the Saprobic index. The values obtained do not exceed the eutrophication limits according to the Water Framework Directive, transposed into Romanian legislation by Order 161/2006, with normal concentrations for rheophile ecosystems, as Danube's branches. In this area, water currents and high water turbidity inhibit phytoplankton growth, in contrast to lacustrine ecosystems, where light penetration to depths favors the development of different phytoplankton groups.
Bivalve grazing can shape phytoplankton communities

Science.gov (United States)

Lucas, Lisa; Cloern, James E.; Thompson, Janet K.; Stacey, Mark T.; Koseff, Jeffrey K.

2016-01-01

The ability of bivalve filter feeders to limit phytoplankton biomass in shallow waters is well-documented, but the role of bivalves in shaping phytoplankton communities is not. The coupled effect of bivalve grazing at the sediment-water interface and sinking of phytoplankton cells to that bottom filtration zone could influence the relative biomass of sinking (diatoms) and non-sinking phytoplankton. Simulations with a pseudo-2D numerical model showed that benthic filter feeding can interact with sinking to alter diatom:non-diatom ratios. Cases with the smallest proportion of diatom biomass were those with the fastest sinking speeds and strongest bivalve grazing rates. Hydrodynamics modulated the coupled sinking-grazing influence on phytoplankton communities. For example, in simulations with persistent stratification, the non-sinking forms accumulated in the surface layer away from bottom grazers while the sinking forms dropped out of the surface layer toward bottom grazers. Tidal-scale stratification also influenced vertical gradients of the two groups in opposite ways. The model was applied to Suisun Bay, a low-salinity habitat of the San Francisco Bay system that was transformed by the introduction of the exotic clam Potamocorbula amurensis. Simulation results for this Bay were similar to (but more muted than) those for generic habitats, indicating that P. amurensis grazing could have caused a disproportionate loss of diatoms after its introduction. Our model simulations suggest bivalve grazing affects both phytoplankton biomass and community composition in shallow waters. We view these results as hypotheses to be tested with experiments and more complex modeling approaches.
Algal blooms: a perspective from the coasts of India

Digital Repository Service at National Institute of Oceanography (India)

DeSilva, M.S.; Anil, A.C.; Naik, R.K.; DeCosta, P.M.

Algal blooms have been documented along the west and east coasts of India. A review of bloom occurrences in Indian waters from 1908 to 2009 points out that a total of 101 cases have been reported. A comparison of the bloom cases reported before...
Influence of river influx on phytoplankton community during fall inter–monsoon in the coastal waters off Kakinada, east coast of India

Digital Repository Service at National Institute of Oceanography (India)

Sooria, P.M.; Reny, P.D.; Jagadeesan, L.; Nair, M.

of phytoplankton species abundance showed two well separated clusters (similarity less than or equal to 10%) for 2006 and 2007. It reveals the variation in community structure between the two periods of observation. Multidimensional scaling of species abundance...
Phytoplankton chlorophyll

NARCIS (Netherlands)

van de Poll, W.H.; Kulk, G.; Timmermans, K.R.; Brussaard, C.P.D.; van der Woerd, H.J.; Kehoe, M.J.; Mojica, K.D.A.; Visser, R.J.W.; Rozema, P.D.; Buma, A.G.J.

2013-01-01

Relationships between sea surface temperature (SST, > 10 m) and vertical density stratification, nutrient concentrations, and phytoplankton biomass, composition, and chlorophyll a (Chl a) specific absorption were assessed in spring and summer from latitudes 29 to 63 degrees N in the northeast
Estimation of new production in the North Sea: consequences for temporal and spatial variability of phytoplankton

DEFF Research Database (Denmark)

Richardson, Katherine; Bo Pedersen, Flemming

1998-01-01

By coupling knowledge of oceanographic processes and phytoplankton responses to light and nutrient availability, we estimate a total potential new (sensu Dugdale and Goering,1967) production for the North Sea of approximately 15.6 million tons C per year. In a typical year, about 40......% of this production will be associated with the spring bloom in the surface waters of the seasonally stratified (central and northern) North Sea. About 40% is predicted to occur in the coastal waters while the remaining new production is predicted to take place in sub-surface chlorophyll peaks occuring in association...... with fronts in the North Sea during summer month. By considering the inter-annual variation in heat, wind and nutrient availability (light and tidal energy input are treated as non-varying from year to year), the inter-annual variability in the new production occuring in these different regions is estimated...
Water flux management and phytoplankton communities in a Mediterranean coastal lagoon. Part II: Mixotrophy of dinoflagellates as an adaptive strategy?

International Nuclear Information System (INIS)

Cecchi, P.; Garrido, M.; Collos, Y.; Pasqualini, V.

2016-01-01

Dinoflagellate proliferation is common in coastal waters, and trophic strategies are often advanced to explain the success of these organisms. The Biguglia lagoon is a Mediterranean brackish ecosystem where eutrophication has long been an issue, and where dominance of dinoflagellates has persisted for several years. Monthly monitoring of fluorescence-based properties of phytoplankton communities carried out in 2010 suggested that photosynthesis alone could not support the observed situation all year round. Contrasting food webs developed depending on the hydrological season, with a gradual shift from autotrophy to heterotrophy. Progressively, microphytoplankton assemblages became unequivocally dominated by a Prorocentrum minimum bloom, which exhibited very weak effective photosynthetic performance, whereas paradoxically its theoretical capacities remained fully operational. Different environmental hypotheses explaining this discrepancy were examined, but rejected. We conclude that P. minimum bloom persistence is sustained by mixotrophic strategies, with complex compromises between phototrophy and phagotrophy, as evidenced by fluorescence-based observations. - Highlights: •Dinoflagellate proliferation is now common in Mediterranean coastal waters. •Trophic strategies are advanced to explain the success of these organisms. •Prorocentrum minimum exhaustively dominated in the Biguglia lagoon (Corsica) in 2010. •Photosynthesis alone did not sustain the observed situation all year round. •Mixotrophy is hypothesized as an alternative driver of the process.
MODELING AND ANALYSIS OF ALGAL BLOOMS IN ARAS DAM BY ARTIFICIAL NEURAL NETWORK

Directory of Open Access Journals (Sweden)

JAHANGIRI-RAD MAHSA

2015-03-01

Full Text Available Man made practices have contributed to large-scale algal blooms that have caused serious ecological, aesthetic, water purification and water distribution problems. Aras Dam, which provides Arasful city with drinking water, has chronic algal blooms since 1990. This study addresses the use of artificial neural network (ANN model to anticipate the chlorophyll-a concentration in water of dam reservoir. Operation tests carried out by collecting water samples from 5 stations and examined for physical quality parameters namely: water temperature, total suspended solids (TSS, biochemical oxygen demands (BOD, ortophosphate, total phosphorous and nitrate concentrations using standard methods. Chlorophyll-a was also checked separately in order to investigate the accuracy of the predicted results by ANN. The results showed that a network was highly accurate in predicting the Chl-a concentration. A good agreement between actual data and the ANN outputs for training was observed, indicating the validation of testing data sets. The initial results of the research indicate that the dam is enriched with nutrients (phosphorus and nitrogen. The Chl-a concentration that were predicted by the model were beyond the standard levels; indicating the possibility of eutrophication especially during fall season.
Zooplankton excretion metabolites stimulate Southern Ocean phytoplankton growth

KAUST Repository

Coello-Camba, A.; Llabré s, M.; Duarte, Carlos M.; Agusti, Susana

2017-01-01

Warming over Antarctica is leading to changes in the zooplankton communities inhabiting the Southern Ocean. It has been observed that zooplankton not only regulates phytoplankton through grazing, but also through the recycling of nutrients that are essential for phytoplankton growth. In this way, the effects of warming on zooplankton populations will change the amount or proportion at which recycled nutrients are restored. To estimate how the recycled nutrients released by zooplankton populations, dominated by krill (Euphausia superba), amphipods or copepods, affect the phytoplankton uptake and communities, we performed four incubation experiments: two close to the Antarctic Peninsula and two at the Southern Atlantic Ocean. Our results showed a stimulating effect of the addition of metabolites on ammonia removal rates and on the net growth of phytoplankton communities, with different responses amongst the different phytoplankton groups. According to our results, phytoplankton net growth and community composition may be altered if this relevant source of nutrients is lost due to projected changes in the abundance or distribution of these zooplankton populations.
Amplified Arctic warming by phytoplankton under greenhouse warming.

Science.gov (United States)

Park, Jong-Yeon; Kug, Jong-Seong; Bader, Jürgen; Rolph, Rebecca; Kwon, Minho

2015-05-12

Phytoplankton have attracted increasing attention in climate science due to their impacts on climate systems. A new generation of climate models can now provide estimates of future climate change, considering the biological feedbacks through the development of the coupled physical-ecosystem model. Here we present the geophysical impact of phytoplankton, which is often overlooked in future climate projections. A suite of future warming experiments using a fully coupled ocean-atmosphere model that interacts with a marine ecosystem model reveals that the future phytoplankton change influenced by greenhouse warming can amplify Arctic surface warming considerably. The warming-induced sea ice melting and the corresponding increase in shortwave radiation penetrating into the ocean both result in a longer phytoplankton growing season in the Arctic. In turn, the increase in Arctic phytoplankton warms the ocean surface layer through direct biological heating, triggering additional positive feedbacks in the Arctic, and consequently intensifying the Arctic warming further. Our results establish the presence of marine phytoplankton as an important potential driver of the future Arctic climate changes.
Climate Variability and Phytoplankton in the Pacific Ocean

Science.gov (United States)

Rousseaux, Cecile

2012-01-01

The effect of climate variability on phytoplankton communities was assessed for the tropical and sub-tropical Pacific Ocean between 1998 and 2005 using an established biogeochemical assimilation model. The phytoplankton communities exhibited wide range of responses to climate variability, from radical shifts in the Equatorial Pacific, to changes of only a couple of phytoplankton groups in the North Central Pacific, to no significant changes in the South Pacific. In the Equatorial Pacific, climate variability dominated the variability of phytoplankton. Here, nitrate, chlorophyll and all but one of the 4 phytoplankton types (diatoms, cyanobacteria and coccolithophores) were strongly correlated (pphytoplankton groups (chlorophytes and coccolithophores). Ocean biology in the South Pacific was not significantly correlated with MEI. During La Nina events, diatoms increased and expanded westward along the cold tongue (correlation with MEI, r=-0.81), while cyanobacteria concentrations decreased significantly (r=0.78). El Nino produced the reverse pattern, with cyanobacteria populations increasing while diatoms plummeted. The diverse response of phytoplankton in the different major basins of the Pacific suggests the different roles climate variability can play in ocean biology.

Zooplankton excretion metabolites stimulate Southern Ocean phytoplankton growth

KAUST Repository

Coello-Camba, A.

2017-04-24

Warming over Antarctica is leading to changes in the zooplankton communities inhabiting the Southern Ocean. It has been observed that zooplankton not only regulates phytoplankton through grazing, but also through the recycling of nutrients that are essential for phytoplankton growth. In this way, the effects of warming on zooplankton populations will change the amount or proportion at which recycled nutrients are restored. To estimate how the recycled nutrients released by zooplankton populations, dominated by krill (Euphausia superba), amphipods or copepods, affect the phytoplankton uptake and communities, we performed four incubation experiments: two close to the Antarctic Peninsula and two at the Southern Atlantic Ocean. Our results showed a stimulating effect of the addition of metabolites on ammonia removal rates and on the net growth of phytoplankton communities, with different responses amongst the different phytoplankton groups. According to our results, phytoplankton net growth and community composition may be altered if this relevant source of nutrients is lost due to projected changes in the abundance or distribution of these zooplankton populations.
Detection of surface algal blooms using the newly developed algorithm surface algal bloom index SABI)

OpenAIRE

Alawadi, Fahad

2010-01-01

Quantifying ocean colour properties has evolved over the past two decades from being able to merely detect their biological activity to the ability to estimate chlorophyll concentration using optical satellite sensors like MODIS and MERIS. The production of chlorophyll spatial distribution maps is a good indicator of plankton biomass (primary production) and is useful for the tracing of oceanographic currents, jets and blooms, including harmful algal blooms (HABs). Depending on the type of HA...
Phytoplankton and the Macondo oil spill: A comparison of the 2010 phytoplankton assemblage to baseline conditions on the Louisiana shelf.

Science.gov (United States)

Parsons, M L; Morrison, W; Rabalais, N N; Turner, R E; Tyre, K N

2015-12-01

The Macondo oil spill was likely the largest oil spill to ever occur in United States territorial waters. We report herein our findings comparing the available baseline phytoplankton data from coastal waters west of the Mississippi River, and samples collected monthly from the same sampling stations, during and after the oil spill (May-October, 2010). Our results indicate that overall, the phytoplankton abundance was 85% lower in 2010 versus the baseline, and that the species composition of the phytoplankton community moved towards diatoms and cyanobacteria and away from ciliates and phytoflagellates. The results of this study reaffirm the view that phytoplankton responses will vary by the seasonal timing of the oil spill and the specific composition of the spilled oil. The trophic impacts of the purported lower abundance of phytoplankton in 2010 coupled with the observed assemblage shift remain unknown. Copyright © 2015 Elsevier Ltd. All rights reserved.
Physicochemical Flux and Phytoplankton diversity in Shagari ...

African Journals Online (AJOL)

USER

2007-03-20

Mar 20, 2007 ... distribution of phytoplankton species were also determined. Phytoplankton classes ... could have a significant impact on water quality. (Carpenter and Kitchell ..... Environmental Impact assessment Report on proposed Shagari ...
What Controls Seasonal Variation of Phytoplankton Growth in the East China Sea?

Science.gov (United States)

Liu, K.; Chao, S.; Lee, H.; Gong, G.; Teng, Y.

2009-05-01

The seasonal variation of phytoplankton growth in the East China Sea (ECS) is simulated with a three- dimensional coupled physical-biogeochemical model, which includes discharges from Changjiang (aka the Yangtze River). The purpose is to determine the main control on the seasonality of primary productivity in the ECS shelf, which nurtures rich biological resources. The model has a horizontal resolution of 1/6 degree in the domain from 23N to 41N and from 116E to 134E, excluding the Japan/East Sea, and 33 layers in the vertical. The nitrogen-based biogeochemical model has four compartments: dissolved inorganic nitrogen (DIN), phytoplankton, zooplankton and detritus. The chlorophyll to phytoplankton ratio depends on light and DIN availability. The model is driven by monthly climatological winds with the sea surface temperature, salinity and DIN relaxed towards the climatological mean values. It successfully reproduces the observed seasonal variation of phytoplankton growth over the ECS shelf with a strong peak in later spring and summer. The modeled annual mean primary production over the entire ECS shelf is 439 mg C m-2 d-1, which falls within the reported range of 390-529 mg C m-2 d-1. It also reproduces the marked gradient of DIN across the shelf decreasing away from the Changjiang River plume. An alternative model run, Free-N, which deviates from the standard run by essentially removing nudging on DIN, generates the same seasonal pattern of primary productivity but somewhat reduced productivity. In yet another alternative run, Fix-PAR, which deviates from Free-N by removing the seasonal cycle of photosynthetically active radiation, the seasonality of primary productivity almost vanishes. These model results demonstrate that light availability is the major control on the seasonality of primary productivity. However, nutrient supply from vertical nutrient pumping and from Changjiang discharges is still important. It is the insufficient nutrient pumping that leads
Bacterial succession across seasonal transitions in the coastal waters of the western Antarctic Peninsula

Science.gov (United States)

Luria, C.; Rich, J. J.; Amaral-Zettler, L. A.; Ducklow, H. W.

2016-02-01

The marine ecosystem west of the Antarctic Peninsula (WAP) undergoes a dramatic seasonal transition every spring, from almost total darkness to almost continuous sunlight, resulting in a cascade of environmental changes, including the intense phytoplankton blooms that support a highly productive food web. Despite having important implications for the microbial loop and the biological carbon pump, the degree of trophic coupling between phytoplankton and bacteria is unclear. In particular, due to the difficulties inherent in sampling this remote system during the Antarctic winter and spring, little is known about how phytoplankton blooms may or may not drive bacterial seasonal succession. Using 16S rRNA gene amplicon sequencing, we assessed bacterial community composition in 68 samples from 24 dates that spanned the cold, dark winter, spring transitional period, and summer phytoplankton bloom. Our analysis resulted in 15 million sequences and 12,000 Operational Taxonomic Units (OTUs). We found that mid-winter bacterial communities had the highest richness ( 1,800 observed OTUs in rarefied libraries) and a greater abundance of oligotrophic and potentially chemoautolithotrophic taxa. The bacterial community changed only gradually up until the onset of a mid-summer phytoplankton bloom, which coincided with a 100-fold increase in bacterial production, a rapid decline in richness to 700 OTUs, and a shift in community composition toward copiotrophic taxa. This period lasted only a few weeks, at the end of which the bacterial community had largely reverted to its mid-winter state. Our findings provide new evidence of trophic coupling between bacteria and phytoplankton and highlight the importance of higher-resolution time series sampling in order to capture rapid seasonal changes.
Community structure characteristics of phytoplankton in zhalong wetland, china

International Nuclear Information System (INIS)

Zhang, N.; Zang, S.S.

2015-01-01

In autumn 2010, the phytoplankton samples were collected in Zhalong Wetland. A total of 347 species belonging to 78 genera,6 phyla were identified, Chlorophyta and Bacillariophyta were dominated phytoplankton communities, including 143 species of Chlorophyta, 116 species of Bacillariophyta, 45 species of Cyanophyta, 39 species of Euglenophyta, 3 species of Pyrrophyta, 1 species of Chrysophyta. In the core area 66 genera, 222 species were identified, in the buffer area 63 genera, 210 species were identified, in the experiment area 63 genera, 167 species were identified. The dominant species in Zhalong Wetland included Cyclotella meneghiniana, Chlorella vulgaris, Trachelomonas volvocina, Nitzschia sp.. The average phytoplankton density was 12.13*10/sup 6/ in Zhalong Wetland, the phytoplankton density of Bacillariophyta was highest (32.82*10/sup 6/ ind L/sup -1/), and then Chlorophyta (23.73*10/sup 6/ ind L/sup -1/) and Cyanophyta (11.43*106 ind L-1), respectively. The results of cluster analysis showed that phytoplankton community structure could be divided into three types, and within-group similarities of phytoplankton community structure was not high, but inter-group non-similarity was high. Based on the species composition, phytoplankton density, phytoplankton pollution indicator, it suggested that Zhalong Wetland was mesotrophic state. (author)
Dazzled by ice and snow: improving medium ocean color images in Arctic waters

Science.gov (United States)

Babin, M.; Goyens, C.; Belanger, S.

2016-02-01

The importance of phytoplankton blooms for the Arctic marine ecosystem is well recognized but studies disagree as the consequences of sea ice melt on the phytoplankton distribution and growth. This limited understanding in actual and future Arctic phytoplankton dynamics mostly results from a lack of accurate data at the receding ice-edges where phytoplankton blooms are known to occur. Ocean color sensors on-board satellites represent therefore a crucial tool providing a synoptic view of the ocean systems over broad spatio-temporal scales. However, today the use of ocean color data in Arctic environments remains strongly compromised due to, among others, sea ice contamination. Indeed, medium ocean color data along the receding ice edge are "dazzled" by nearby and/or sub-pixel highly reflective ice floes. Standard ocean color data methods ignore ice-contamination during data processing which deteriorates the quality of the radiometric data and subsequent satellite derived bio-geochemical products. Moreover, since Arctic phytoplankton spring blooms typically develop along the receding ice-edges, ignoring ice-contaminated pixels may lead to wrong interpretation of satellite data. The present study shows how adjacent and sub-pixel sea-ice floes affect the retrieved ocean color data. A correction approach is also suggested to improve the "dazzled" ocean color pixels along the receding ice edge in the aim to provide additional support to better understand current and future trends in phytoplankton dynamics.
Ecotoxicology of bromoacetic acid on estuarine phytoplankton

International Nuclear Information System (INIS)

Gordon, Ana R.; Richardson, Tammi L.; Pinckney, James L.

2015-01-01

Bromoacetic acid is formed when effluent containing chlorine residuals react with humics in natural waters containing bromide. The objective of this research was to quantify the effects of bromoacetic acid on estuarine phytoplankton as a proxy for ecosystem productivity. Bioassays were used to measure the EC 50 for growth in cultured species and natural marine communities. Growth inhibition was estimated by changes in chlorophyll a concentrations measured by fluorometry and HPLC. The EC 50 s for cultured Thalassiosira pseudonana were 194 mg L −1 , 240 mg L −1 for Dunaliella tertiolecta and 209 mg L −1 for Rhodomonas salina. Natural phytoplankton communities were more sensitive to contamination with an EC 50 of 80 mg L −1 . Discriminant analysis suggested that bromoacetic acid additions cause an alteration of phytoplankton community structure with implications for higher trophic levels. A two-fold EC 50 decrease in mixed natural phytoplankton populations affirms the importance of field confirmation for establishing water quality criteria. - Highlights: • Bromoacetic acid exposure resulted in lethal impacts to estuarine phytoplankton. • Cultured phytoplankton were less sensitive to bromoacetic acid than natural communities. • Lab results should be confirmed with field experiments whenever possible. - The toxicology of haloacetic acids has been studied in freshwater ecosystems, and urbanization of the coastal zone is making effects in marine ecosystems equally relevant.
Monitoring natural phytoplankton communities

DEFF Research Database (Denmark)

Haraguchi, L.; Jakobsen, H. H.; Lundholm, Nina

2017-01-01

-consuming and/or expensive, limiting sampling frequency. The use of faster methods, such as flow cytometry, has become more frequent in phytoplankton studies, although comparisons between this technique and traditional ones are still scarce. This study aimed to assess if natural phytoplankton communities...... carbon biomass with PFCM, applying the same conversion factors as for microscopy. Biomasses obtained with PFCM, estimated from live cells, were higher than microscopy for natural samples. We conclude that PFCM results are comparable to classical techniques, yet the data from PFCM had poor taxonomic...
Transfer of seston lipids during a flagellate bloom from the surface to the benthic community in the Weddell Sea

Directory of Open Access Journals (Sweden)

Sergio Rossi

2013-09-01

Full Text Available Total lipid and fatty acid concentrations were studied in a late spring-early summer flagellate-dominated bloom in the Weddell Sea. These indicators were considered a good tool for assessing the quality of organic matter settling from surface to deep-water layers (epibenthic water layers. The results showed different patterns between the early (11-15 December 2003 and the late sampling period (18-27 December 2003 at all studied depths (5 m, 50 m and near-bottom water layers. Low phytoplankton biomass (mainly flagellates in the first half of the study corresponded to low total lipid and fatty acid concentrations. In the second sampling period a spring bloom (mainly flagellates and diatoms was detected, increasing the total lipid and fatty acid concentrations in the water column. The amount of settling organic matter from surface waters to the near-bottom water layers was high, especially in the late sampling period. Trophic markers showed evidence of a sink of available organic matter rich in quality and quantity, especially in terms of polyunsaturated fatty acids, for benthic organisms from surface layers to bottom layers in only a few days. The importance of studying short-time cycles in order to detect organic matter availability for benthic biota in view of the pulse-like dynamics of primary production in Antarctic waters is discussed.
Long-term seasonal nutrient limiting patterns at Meiliang Bay in a large, shallow and subtropical Lake Taihu, China

Directory of Open Access Journals (Sweden)

Rui Ye

2015-04-01

Full Text Available Lake Taihu has undergone severe eutrophication in the past three decades, and harmful cyanobacteria blooms occur nearly every year in Meiliang Bay at the north end of the lake. To elucidate the potential relationship between seasonal nutrient limitation and phytoplankton proliferation, a 20-year (1991-2012 time series of nutrient limitation in Meiliang Bay was analyzed for deviations between trophic state index (TSI parameters. Results showed that patterns of nutrient limitation in Meiliang Bay were distinctly seasonal, where phytoplankton growth was generally phosphorus (P-limited in winter and spring, but nitrogen (N-limited mainly occurred in summer and fall. This general pattern, however, shifted into N limitation across the four seasons during the mid-1990s because a rapid increase in industrialization led to a significant rise in the input of N and P from inflowing tributaries. The initial patterns were restored by environmental regulation in the end of 1990s, including the Zero Actions plan. Using routine monitoring data, a generalised additive model (GAM with time and deviations between trophic state indexes for nitrogen and phosphorus (TSIN-TSIP as explanatory variables was used to explore which nutrient was responsible for limitation of phytoplankton chlorophyll-a (Chl-a in different seasons. Surprisingly, the model revealed a weak N limitation (TSIN-TSIP = -10 corresponded to peak values of Chl-a in summer-autumn season, which is probably because the phytoplankton community is co-limited by N & P during the period. The shift of nutrition limitation during winter-spring would partially explain high values of Chl-a throughout 1996. This study suggests that seasonal patterns of nutrient limitation must be considered to develop effective management measures to control cyanobacterial blooms.
Spatio-temporal patterns of Ulva prolifera blooms and the corresponding influence on chlorophyll-a concentration in the Southern Yellow Sea, China.

Science.gov (United States)

Sun, Xiao; Wu, Mengquan; Xing, Qianguo; Song, Xiaodong; Zhao, Deheng; Han, Qianqian; Zhang, Guangzong

2018-06-04

The world's largest macroalgal blooms (MABs) caused by the Ulva prolifera outbreaks have occurred every summer since 2007 in the Southern Yellow Sea, China. Accumulating evidence showed that MABs may deteriorate the regional marine environment and influence the growth of some primary producers such as phytoplankton. In this study, we investigated the spatio-temporal patterns of U. prolifera green tides and chlorophyll-a concentration in the Southern Yellow Sea in 2015 using satellite images obtained from HJ-1 CCD, MODIS, and GOCI. The correlation between the distributions of U. prolifera abundance and chlorophyll-a concentration was analyzed quantitatively by setting up a series of 5 × 5 km experimental grids, and we also discussed the possible mechanisms about the influence of U. prolifera blooms on the other floating microalgae. The results showed that the development of U. prolifera blooms in the Southern Yellow Sea in 2015 could be featured as "appearance - development - outbreak - decline - disappearance", while the concentration of chlorophyll-a showed "increase - sharp decline - slow recovery - stabilization" from April to August. We also found that the concentration of chlorophyll-a had the following relationships with U. prolifera temporally: (1) the concentration of chlorophyll-a increased with the growth of U. prolifera from April to mid-May; (2) the chlorophyll-a concentration decreased sharply with the dramatically increased coverage of U. prolifera in June; and (3) the chlorophyll-a concentration slowly recovered and finally stabilized as U. prolifera decreased in July. Generally, there was a negative correlation between the occurrence of U. prolifera and chlorophyll-a concentration in the Southern Yellow Sea, China. Our results showed that the outbreak of U. prolifera does have a certain impact on the growth and reproduction of planktonic microalgae, and it suggests that U. prolifera blooms have potentially altered the ecological balance in
Chytrid parasitism facilitates trophic transfer between bloom-forming cyanobacteria and zooplankton (Daphnia).

Science.gov (United States)

Agha, Ramsy; Saebelfeld, Manja; Manthey, Christin; Rohrlack, Thomas; Wolinska, Justyna

2016-10-13

Parasites are rarely included in food web studies, although they can strongly alter trophic interactions. In aquatic ecosystems, poorly grazed cyanobacteria often dominate phytoplankton communities, leading to the decoupling of primary and secondary production. Here, we addressed the interface between predator-prey and host-parasite interactions by conducting a life-table experiment, in which four Daphnia galeata genotypes were maintained on quantitatively comparable diets consisting of healthy cyanobacteria or cyanobacteria infected by a fungal (chytrid) parasite. In four out of five fitness parameters, at least one Daphnia genotype performed better on parasitised cyanobacteria than in the absence of infection. Further treatments consisting of purified chytrid zoospores and heterotrophic bacteria suspensions established the causes of improved fitness. First, Daphnia feed on chytrid zoospores which trophically upgrade cyanobacterial carbon. Second, an increase in heterotrophic bacterial biomass, promoted by cyanobacterial decay, provides an additional food source for Daphnia. In addition, chytrid infection induces fragmentation of cyanobacterial filaments, which could render cyanobacteria more edible. Our results demonstrate that chytrid parasitism can sustain zooplankton under cyanobacterial bloom conditions, and exemplify the potential of parasites to alter interactions between trophic levels.
Prevention of Cyanobacterial Blooms Using Nanosilica: A Biomineralization-Inspired Strategy.

Science.gov (United States)

Xiong, Wei; Tang, Yiming; Shao, Changyu; Zhao, Yueqi; Jin, Biao; Huang, Tingting; Miao, Ya'nan; Shu, Lei; Ma, Weimin; Xu, Xurong; Tang, Ruikang

2017-11-07

Cyanobacterial blooms represent a significant threat to global water resources because blooming cyanobacteria deplete oxygen and release cyanotoxins, which cause the mass death of aquatic organisms. In nature, a large biomass volume of cyanobacteria is a precondition for a bloom, and the cyanobacteria buoyancy is a key parameter for inducing the dense accumulation of cells on the water surface. Therefore, blooms will likely be curtailed if buoyancy is inhibited. Inspired by diatoms with naturally generated silica shells, we found that silica nanoparticles can be spontaneously incorporated onto cyanobacteria in the presence of poly(diallyldimethylammonium chloride), a cationic polyelectrolyte that can simulate biosilicification proteins. The resulting cyanobacteria-SiO 2 complexes can remain sedimentary in water. This strategy significantly inhibited the photoautotrophic growth of the cyanobacteria and decreased their biomass accumulation, which could effectively suppress harmful bloom events. Consequently, several of the adverse consequences of cyanobacteria blooms in water bodies, including oxygen consumption and microcystin release, were significantly alleviated. Based on the above results, we propose that the silica nanoparticle treatment has the potential for use as an efficient strategy for preventing cyanobacteria blooms.
Environmental controls on spatial variability of summer phytoplankton structure and biomass in the Bering Sea

Science.gov (United States)

Wang, Yu; Xiang, Peng; Kang, Jian-hua; Ye, You-yin; Lin, Geng-ming; Yang, Qing-liang; Lin, Mao

2018-01-01

the community was mainly dominated by Thalassiosira nordenskiöldii, Leptocylindrus danicus, Chaetoceros socialis, Chaetoceros debilis, Fragilariopsis oceanica, Nitzschia closterium and Chaetoceros furcellatus. A diatom bloom was observed near the Bering Strait in the summer of 2010 induced by high availability of nitrate particularly in the Bering Shelf, while water mass transportation mainly influenced communities in the Bering Basin and Slope. The observed fluctuation in both biomass and summer phytoplankton communities in the Bering Sea were mostly influenced by events related to the spring sea ice retreat in 2010.
Harmful Algal Blooms

Science.gov (United States)

Graham, Jennifer L.

2007-01-01

What are Harmful Algal Blooms (HABs)? Freshwater and marine harmful algal blooms (HABs) can occur anytime water use is impaired due to excessive accumulations of algae. HAB occurrence is affected by a complex set of physical, chemical, biological, hydrological, and meteorological conditions making it difficult to isolate specific causative environmental factors. Potential impairments include reduction in water quality, accumulation of malodorous scums in beach areas, algal production of toxins potent enough to poison both aquatic and terrestrial organisms, and algal production of taste-and-odor compounds that cause unpalatable drinking water and fish. HABs are a global problem, and toxic freshwater and (or) marine algae have been implicated in human and animal illness and death in over 45 countries worldwide and in at least 27 U.S. States (Yoo and others, 1995; Chorus and Bartram, 1999; Huisman and others, 2005).
The ocean response to volcanic iron fertilisation after the eruption of Kasatochi volcano: a regional-scale biogeochemical ocean model study

Directory of Open Access Journals (Sweden)

A. Lindenthal

2013-06-01

Full Text Available In high-nutrient–low-chlorophyll regions, phytoplankton growth is limited by the availability of water-soluble iron. The eruption of Kasatochi volcano in August 2008 led to ash deposition into the iron-limited NE Pacific Ocean. Volcanic ash released iron upon contact with seawater and generated a massive phytoplankton bloom. Here we investigate this event with a one-dimensional ocean biogeochemical column model to illuminate the ocean response to iron fertilisation by volcanic ash. The results indicate that the added iron triggered a phytoplankton bloom in the summer of 2008. Associated with this bloom, macronutrient concentrations such as nitrate and silicate decline and zooplankton biomass is enhanced in the ocean mixed layer. The simulated development of the drawdown of carbon dioxide and increase of pH in surface seawater is in good agreement with available observations. Sensitivity studies with different supply dates of iron to the ocean emphasise the favourable oceanic conditions in the NE Pacific to generate massive phytoplankton blooms in particular during July and August in comparison to other months. By varying the amount of volcanic ash and associated bio-available iron supplied to the ocean, model results demonstrate that the NE Pacific Ocean has higher, but limited capabilities to consume CO2 after iron fertilisation than those observed after the volcanic eruption of Kasatochi.
Niche of harmful alga Aureococcus anophagefferens revealed through ecogenomics

Energy Technology Data Exchange (ETDEWEB)

Gobler, C J; Grigoriev, I V; Berry, D L; Dyhrman, S T; Wilhelm, S W; Salamov, A; Lobanov, A V; Zhang, Y; Collier, J L; Wurch, L L; Kustka, A B; Dill, B D; Shah, M; VerBerkomes, N C; Kuo, A; Terry, A; Pangilinan, J; Lindquist, E A; Lucas, S; Paulsen, I; Hattenrath-Lehmann, T K; Talmage, S; Walker, E A; Koch, F; Burson, A M; Marcoval, M A; Tang, Y; LeCleir, G R; Coyne, K J; Berg, G M; Bertrand, E M; Saito, M A; Gladyshev, V N

2011-03-02

Harmful algal blooms (HABs) cause significant economic and ecological damage worldwide. Despite considerable efforts, a comprehensive understanding of the factors that promote these blooms has been lacking because the biochemical pathways that facilitate their dominance relative to other phytoplankton within specific environments have not been identified. Here, biogeochemical measurements demonstrated that the harmful alga Aureococcus anophagefferens outcompeted co-occurring phytoplankton in estuaries with elevated levels of dissolved organic matter and turbidity and low levels of dissolved inorganic nitrogen. We subsequently sequenced the first HAB genome (A. anophagefferens) and compared its gene complement to those of six competing phytoplankton species identified via metaproteomics. Using an ecogenomic approach, we specifically focused on the gene sets that may facilitate dominance within the environmental conditions present during blooms. A. anophagefferens possesses a larger genome (56 mbp) and more genes involved in light harvesting, organic carbon and nitrogen utilization, and encoding selenium- and metal-requiring enzymes than competing phytoplankton. Genes for the synthesis of microbial deterrents likely permit the proliferation of this species with reduced mortality losses during blooms. Collectively, these findings suggest that anthropogenic activities resulting in elevated levels of turbidity, organic matter, and metals have opened a niche within coastal ecosystems that ideally suits the unique genetic capacity of A. anophagefferens and thus has facilitated the proliferation of this and potentially other HABs.
Niche of harmful alga Aureococcus anophagefferens revealed through ecogenomics

Energy Technology Data Exchange (ETDEWEB)

Grigoriev, Igor; Gobler, Christopher; Salamov, Asaf; Kuo, Alan; Terry, Astrid; Pangillian, Jasmyn; Lindquist, Erika; Lucas, Susan; Berry, Dianna; Dyhrman, Sonya; Wilhelm, Steven; Lobanov, Alexei; Zhang, Yan; Collier, Jackie; Wurch, Louie; Kusta, Adam; Dill, Brian; Shsh, Manesh; VerBerkmoes, Nathan; Paulsen, Ian; Hattenrath-Lehmann, Theresa; Talmage, Stephanie; Walker, Elyse; Koch, Florian; Burson, Amanda; Marcoval, Maria; Tang, Yin-Zhong; LeCleir, Gary; Coyne, Kathyrn; Berg, Gry; Bertrand, Erin; Saito, Mak; Gladyshev, Vadim

2011-02-18

Harmful algal blooms (HABs) cause significant economic and ecological damage worldwide. Despite considerable efforts, a comprehensive understanding of the factors that promote these blooms has been lacking, because the biochemical pathways that facilitate their dominance relative to other phytoplankton within specific environments have not been identified. Here, biogeochemical measurements showed that the harmful alga Aureococcus anophagefferens outcompeted co-occurring phytoplankton in estuaries with elevated levels of dissolved organic matter and turbidity and low levels of dissolved inorganic nitrogen. We subsequently sequenced the genome of A. anophagefferens and compared its gene complement with those of six competing phytoplankton species identified through metaproteomics. Using an ecogenomic approach, we specifically focused on gene sets that may facilitate dominance within the environmental conditions present during blooms. A. anophagefferens possesses a larger genome (56 Mbp) and has more genes involved in light harvesting, organic carbon and nitrogen use, and encoding selenium- and metal-requiring enzymes than competing phytoplankton. Genes for the synthesis of microbial deterrents likely permit the proliferation of this species, with reduced mortality losses during blooms. Collectively, these findings suggest that anthropogenic activities resulting in elevated levels of turbidity, organic matter, and metals have opened a niche within coastal ecosystems that ideally suits the unique genetic capacity of A. anophagefferens and thus, has facilitated the proliferation of this and potentially other HABs.

The Blooming Anatomy Tool (BAT): A Discipline-Specific Rubric for Utilizing Bloom's Taxonomy in the Design and Evaluation of Assessments in the Anatomical Sciences

Science.gov (United States)

Thompson, Andrew R.; O'Loughlin, Valerie D.

2015-01-01

Bloom's taxonomy is a resource commonly used to assess the cognitive level associated with course assignments and examination questions. Although widely utilized in educational research, Bloom's taxonomy has received limited attention as an analytical tool in the anatomical sciences. Building on previous research, the Blooming Anatomy Tool (BAT)…
Cyanobacterial blooms in stratified and destratified eutrophic reservoirs in semi-arid region of Brazil

Directory of Open Access Journals (Sweden)

Ênio W. Dantas

2011-12-01

Full Text Available This study investigated the dynamics of cyanobacteria in two deep, eutrophic reservoirs in a semi-arid region of Brazil during periods of stratification and destratification. Four collections were carried out at each reservoir at two depths at three-month intervals. The following abiotic variables were analyzed: water temperature, dissolved oxygen, pH, turbidity, water transparency, total phosphorus, total dissolved phosphorus, orthophosphate and total nitrogen. Phytoplankton density was quantified for the determination of the biomass of cyanobacteria. The data were analyzed using CCA. Higher mean phytoplankton biomass values (29.8 mm³.L-1 occurred in the period of thermal stratification. A greater similarity in the phytoplankton communities also occurred in this period and was related to the development of cyanobacteria, mainly Cylindrospermopsis raciborskii (>3.9 mm³.L-1. During the period of thermal destratification, this species co-dominated the environment with Planktothrix agardhii, Geitlerinema amphibium, Microcystis aeruginosa and Merismopedia tenuissima, as well as with diatoms and phytoflagellates. Environmental instability and competition among algae hindered the establishment of blooms more during the mixture period than during the stratification period. Thermal changes in the water column caused by climatologic events altered other physiochemical conditions of the water, leading to changes in the composition and biomass of the cyanobacterial community in tropical reservoirs.Este estudo investigou a dinâmica das cianobactérias em dois reservatórios eutróficos e profundos localizados na região semi-árida do Brasil durante períodos de estratificação e desestratificação térmica. Quatro coletas foram feitas em cada reservatório em duas profundidades em intervalo de três meses. As variáveis abióticas analisadas foram: temperatura da água, oxigênio dissolvido, pH, turbidez, transparência da água, fósforo total, f
Satellite-detected fluorescence reveals global physiology of ocean phytoplankton

Directory of Open Access Journals (Sweden)

M. J. Behrenfeld

2009-05-01

Full Text Available Phytoplankton photosynthesis links global ocean biology and climate-driven fluctuations in the physical environment. These interactions are largely expressed through changes in phytoplankton physiology, but physiological status has proven extremely challenging to characterize globally. Phytoplankton fluorescence does provide a rich source of physiological information long exploited in laboratory and field studies, and is now observed from space. Here we evaluate the physiological underpinnings of global variations in satellite-based phytoplankton chlorophyll fluorescence. The three dominant factors influencing fluorescence distributions are chlorophyll concentration, pigment packaging effects on light absorption, and light-dependent energy-quenching processes. After accounting for these three factors, resultant global distributions of quenching-corrected fluorescence quantum yields reveal a striking consistency with anticipated patterns of iron availability. High fluorescence quantum yields are typically found in low iron waters, while low quantum yields dominate regions where other environmental factors are most limiting to phytoplankton growth. Specific properties of photosynthetic membranes are discussed that provide a mechanistic view linking iron stress to satellite-detected fluorescence. Our results present satellite-based fluorescence as a valuable tool for evaluating nutrient stress predictions in ocean ecosystem models and give the first synoptic observational evidence that iron plays an important role in seasonal phytoplankton dynamics of the Indian Ocean. Satellite fluorescence may also provide a path for monitoring climate-phytoplankton physiology interactions and improving descriptions of phytoplankton light use efficiencies in ocean productivity models.
Byatt versus Bloom

DEFF Research Database (Denmark)

Børch, Marianne

2016-01-01

Antonia Byatt's Possession takes issue with Harold Bloom's famous claim that creation - including an author's creative reading of an intertext - entails a violent encounter. Byatt's book suggests a more positive Construction of the process by which tradition is transformed in transmission....
Aerial Images and Convolutional Neural Network for Cotton Bloom Detection.

Science.gov (United States)

Xu, Rui; Li, Changying; Paterson, Andrew H; Jiang, Yu; Sun, Shangpeng; Robertson, Jon S

2017-01-01

Monitoring flower development can provide useful information for production management, estimating yield and selecting specific genotypes of crops. The main goal of this study was to develop a methodology to detect and count cotton flowers, or blooms, using color images acquired by an unmanned aerial system. The aerial images were collected from two test fields in 4 days. A convolutional neural network (CNN) was designed and trained to detect cotton blooms in raw images, and their 3D locations were calculated using the dense point cloud constructed from the aerial images with the structure from motion method. The quality of the dense point cloud was analyzed and plots with poor quality were excluded from data analysis. A constrained clustering algorithm was developed to register the same bloom detected from different images based on the 3D location of the bloom. The accuracy and incompleteness of the dense point cloud were analyzed because they affected the accuracy of the 3D location of the blooms and thus the accuracy of the bloom registration result. The constrained clustering algorithm was validated using simulated data, showing good efficiency and accuracy. The bloom count from the proposed method was comparable with the number counted manually with an error of -4 to 3 blooms for the field with a single plant per plot. However, more plots were underestimated in the field with multiple plants per plot due to hidden blooms that were not captured by the aerial images. The proposed methodology provides a high-throughput method to continuously monitor the flowering progress of cotton.
Summer heatwaves promote blooms of harmful cyanobacteria

NARCIS (Netherlands)

K.D Joehnk; J. Huisman; J. Sharples; B.P. Sommeijer (Ben); P.M. Visser (Petra); J.M. Stroom

2008-01-01

htmlabstractDense surface blooms of toxic cyanobacteria in eutrophic lakes may lead to mass mortalities of fish and birds, and provide a serious health threat for cattle, pets, and humans. It has been argued that global warming may increase the incidence of harmful algal blooms. Here, we report on a
Summer heatwaves promote blooms of harmful cyanobacteria

NARCIS (Netherlands)

Jöhnk, K.D.; Huisman, J.; Sharples, J.; Sommeijer, B.; Visser, P.M.; Stroom, J.M.

2008-01-01

Dense surface blooms of toxic cyanobacteria in eutrophic lakes may lead to mass mortalities of fish and birds, and provide a serious health threat for cattle, pets, and humans. It has been argued that global warming may increase the incidence of harmful algal blooms. Here, we report on a lake
The necessity of management in a lake of the Atlantic Forest biodiversity hotspot: nitrogen levels connected to a persistent bloom of Cylindrospermopsis raciborskii

Directory of Open Access Journals (Sweden)

Cleber Cunha Figueredo

2016-01-01

Full Text Available ABSTRACT Conservational studies of the threatened Atlantic Forest biome are frequently restricted to terrestrial ecosystems. We know little about the water bodies, specially considering that this biome covers the third largest system of lakes in Brazil. Some of these lakes are located inside the protected "Rio Doce State Park", but many others are found outside this reserve. These external lakes are seldom studied, but understanding their response to human activities is essential for the conservation and the protection of the lakes inside the Park. We evaluated the effects of degradation in a lake outside the Park, which shows a constant bloom of the toxic invasive cyanobacteria Cylindrospermopsis raciborskii. Phytoplankton, climate and physico-chemical variables were assessed from 2011 to 2013 to evaluate which were the major determinants of the lake dynamics. Despite the seasonal changes, the lake was always eutrophic, and cyanobacteria, transparency and nutrients were the major indicators of water characteristics. The lake seems to be nitrogen-limited and cyanobacteria were negatively correlated with nitrogen levels, since the constantly dominant C. raciborskii is a superior competitor for N. We suggest that the monitoring of nitrogen levels is fundamental to establish management strategies to avoid harmful algae blooms in this Atlantic Forest lake.
Dynamics of living phytoplankton: Implications for paleoenvironmental reconstructions

Energy Technology Data Exchange (ETDEWEB)

Barbosa, A B [Centre for Marine and Environmental Research (CIMA), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro (Portugal)], E-mail: abarbosa@ualg.pt

2009-01-01

Phytoplankton is the dominant primary producer in aquatic ecosystems and is considered a gauge of ecological condition and change. Some phytoplankton groups, namely diatoms, dinoflagellates, and coccolithophores, produce morphological or chemical fossils that can be used for paleoenvironmental reconstruction. This study aims to review the processes that regulate dynamics in living phytoplankton and to highlight how this knowledge is used in paleoecological studies. The distribution patterns of phytoplankton in present-day aquatic ecosystems are shaped by the interplay between processes that regulate cell growth and cell death. Cell growth and cell death are regulated by the internal environment of phytoplankton (e.g., specific environmental tolerances, resource uptake properties, cell size, density and morphology, alternative nutritional strategies such as mixotrophy or N{sub 2} uptake, motility, intracellular storage capacities, grazing resistance properties), and by its external environment. The external environment includes variables dependent on the availability of resources (e.g., light intensity, concentration of CO{sub 2} and dissolved inorganic macronutrients and micronutrients, availability of living prey in case of mixotrophs) and variables independent of resources (e.g., temperature, salinity, turbulence, ultraviolet radiation, bioactive compounds, activity of grazers, viruses, and eukaryotic parasites). The importance of recently described loss processes, such as grazing by phagotrophic protists, viral lyses, and programmed cell death, is discussed in the context of its potential impact upon phytoplankton vertical fluxes. Examples of the use of different phytoplankton metrics (e.g. abundance, species composition, species morphology, and elemental composition) to infer contemporaneous as well as past environmental and ecological conditions are critically evaluated.
Dynamics of living phytoplankton: Implications for paleoenvironmental reconstructions

International Nuclear Information System (INIS)

Barbosa, A B

2009-01-01

Phytoplankton is the dominant primary producer in aquatic ecosystems and is considered a gauge of ecological condition and change. Some phytoplankton groups, namely diatoms, dinoflagellates, and coccolithophores, produce morphological or chemical fossils that can be used for paleoenvironmental reconstruction. This study aims to review the processes that regulate dynamics in living phytoplankton and to highlight how this knowledge is used in paleoecological studies. The distribution patterns of phytoplankton in present-day aquatic ecosystems are shaped by the interplay between processes that regulate cell growth and cell death. Cell growth and cell death are regulated by the internal environment of phytoplankton (e.g., specific environmental tolerances, resource uptake properties, cell size, density and morphology, alternative nutritional strategies such as mixotrophy or N 2 uptake, motility, intracellular storage capacities, grazing resistance properties), and by its external environment. The external environment includes variables dependent on the availability of resources (e.g., light intensity, concentration of CO 2 and dissolved inorganic macronutrients and micronutrients, availability of living prey in case of mixotrophs) and variables independent of resources (e.g., temperature, salinity, turbulence, ultraviolet radiation, bioactive compounds, activity of grazers, viruses, and eukaryotic parasites). The importance of recently described loss processes, such as grazing by phagotrophic protists, viral lyses, and programmed cell death, is discussed in the context of its potential impact upon phytoplankton vertical fluxes. Examples of the use of different phytoplankton metrics (e.g. abundance, species composition, species morphology, and elemental composition) to infer contemporaneous as well as past environmental and ecological conditions are critically evaluated.
The Importance of Phytoplankton Biomolecule Availability for Secondary Production

Directory of Open Access Journals (Sweden)

Elina T. Peltomaa

2017-10-01

Full Text Available The growth and reproduction of animals is affected by their access to resources. In aquatic ecosystems, the availability of essential biomolecules for filter-feeding zooplankton depends greatly on phytoplankton. Here, we analyzed the biochemical composition, i.e., the fatty acid, sterol and amino acid profiles and concentrations as well as protein, carbon, nitrogen, and phosphorus content of 17 phytoplankton monocultures representing the seven most abundant phytoplankton classes in boreal and sub-arctic lakes. To examine how the differences in the biochemical composition between phytoplankton classes affect their nutritional quality for consumers, we assessed the performance of Daphnia, on these diets. Furthermore, we defined the most important biomolecules regulating the somatic growth and reproduction of Daphnia, expecting that higher concentrations of certain biomolecules are needed for reproduction than for growth. Finally, we combined these results with phytoplankton field data from over 900 boreal and sub-arctic lakes in order to estimate whether the somatic growth of Daphnia is sterol-limited when the natural phytoplankton communities are cyanobacteria-dominated. Our analysis shows that Daphnia grows best with phytoplankton rich in sterols, ω-3 fatty acids, protein, and amino acids. Their reproduction follows food sterol and ω-3 concentration as well as C:P-ratio being two times higher in Daphnia feeding on cryptophytes than any other diet. Interestingly, we found that a high dietary ω-6 fatty acid concentration decreases both somatic growth and reproduction of Daphnia. When combined with phytoplankton community composition field data, our results indicate that zooplankton is constantly limited by sterols in lakes dominated by cyanobacteria (≥40% of total phytoplankton biomass, and that the absence of cryptophytes can severely hinder zooplankton production in nature.
Effects of fertilizers used in agricultural fields on algal blooms

Science.gov (United States)

Chakraborty, Subhendu; Tiwari, P. K.; Sasmal, S. K.; Misra, A. K.; Chattopadhyay, Joydev

2017-06-01

The increasing occurrence of algal blooms and their negative ecological impacts have led to intensified monitoring activities. This needs the proper identification of the most responsible factor/factors for the bloom formation. However, in natural systems, algal blooms result from a combination of factors and from observation it is difficult to identify the most important one. In the present paper, using a mathematical model we compare the effects of three human induced factors (fertilizer input in agricultural field, eutrophication due to other sources than fertilizers, and overfishing) on the bloom dynamics and DO level. By applying a sophisticated sensitivity analysis technique, we found that the increasing use of fertilizers in agricultural field causes more rapid algal growth and decreases DO level much faster than eutrophication from other sources and overfishing. We also look at the mechanisms how fertilizer input rate affects the algal bloom dynamics and DO level. The model can be helpful for the policy makers in determining the influential factors responsible for the bloom formation.
Empirical relationships between phytoplankton and zooplankton biomass in Indian Ocean

Digital Repository Service at National Institute of Oceanography (India)

Jayalakshmy, K.V.

and temperature, zooplankton and phytoplankton, zooplankton and PO sub(4)-P and phytoplankton and PO sub(4)-P. Linear regression model is found to be significant at 1% level of significance. Since zooplankton and phytoplankton are significantly positively...
Bloom's Taxonomy: Improving Assessment and Teaching-Learning Process

Science.gov (United States)

Chandio, Muhammad Tufail; Pandhiani, Saima Murtaza; Iqbal, Rabia

2016-01-01

This research study critically analyzes the scope and contribution of Bloom's Taxonomy in both assessment and teaching-learning process. Bloom's Taxonomy consists of six stages, namely; remembering, understanding, applying, analyzing, evaluating and creating and moves from lower degree to the higher degree. The study applies Bloom's Taxonomy to…
Microbial activity during a coastal phytoplankton bloom on the Western Antarctic Peninsula in late summer.

Science.gov (United States)

Alcamán-Arias, María E; Farías, Laura; Verdugo, Josefa; Alarcón-Schumacher, Tomás; Díez, Beatriz

2018-05-01

Phytoplankton biomass during the austral summer is influenced by freezing and melting cycles as well as oceanographic processes that enable nutrient redistribution in the West Antarctic Peninsula (WAP). Microbial functional capabilities, metagenomic and metatranscriptomic activities as well as inorganic 13C- and 15N-assimilation rates were studied in the surface waters of Chile Bay during two contrasting summer periods in 2014. Concentrations of Chlorophyll a (Chla) varied from 0.3 mg m-3 in February to a maximum of 2.5 mg m-3 in March, together with a decrease in nutrients; however, nutrients were never depleted. The microbial community composition remained similar throughout both sampling periods; however, microbial abundance and activity changed with Chla levels. An increased biomass of Bacillariophyta, Haptophyceae and Cryptophyceae was observed along with night-grazing activity of Dinophyceae and ciliates (Alveolates). During high Chla conditions, HCO3- uptake rates during daytime incubations increased 5-fold (>2516 nmol C L-1 d-1), and increased photosynthetic transcript numbers that were mainly associated with cryptophytes; meanwhile night time NO3- (>706 nmol N L-1 d-1) and NH4+ (41.7 nmol N L-1 d-1) uptake rates were 2- and 3-fold higher, respectively, due to activity from Alpha-/Gammaproteobacteria and Bacteroidetes (Flavobacteriia). Due to a projected acceleration in climate change in the WAP, this information is valuable for predicting the composition and functional changes in Antarctic microbial communities.
Suffocating phytoplankton, suffocating waters - red tides and anoxia

Directory of Open Access Journals (Sweden)

Grant Colborne Pitcher

2016-09-01

Full Text Available The dynamics of O2 depletion in exceptional dinoflagellate blooms, often referred to as red tides or harmful algal blooms (HABs, was investigated in St Helena Bay in the southern Benguela upwelling system in 2013. The transition to bloom decay and anoxia was examined through determination of O2-based productivity and respiration rates. Changes in O2 concentrations in relation to bloom metabolism were tracked by fast response optical sensors following incubation of red tide waters in large volume light-and-dark polycarbonate carboys. Concurrent measurements of nutrients and nutrient uptake rates served to assess the role of nutrient stressors in community metabolism and bloom mortality. The estimates of community productivity and respiration are among the highest values recorded. Nutrient concentrations were found to be low and were unlikely to meet the demands of the bloom as dictated by the rates of nutrient uptake. Ratios of community respiration to gross production were particularly high ranging from 0.6 – 0.73 and are considered to be a function of the inherently high cellular respiration rates of dinoflagellates. Nighttime community respiration was shown to be capable of removing as much as 17.34 ml O2 l-1 from surface waters. These exceptional rates of O2 utilization are likely in some cases to exceed the rate of O2 replenishment via air-water exchange thereby leading overnight to conditions of anoxia. These conditions of nighttime anoxia and nutrient starvation are likely triggers of cell death and bloom mortality further fueling the microbial foodweb and consumption of O2.
Predicting potentially toxigenic Pseudo-nitzschia blooms in the Chesapeake Bay

Science.gov (United States)

Anderson, Clarissa R.; Sapiano, Mathew R. P.; Prasad, M. Bala Krishna; Long, Wen; Tango, Peter J.; Brown, Christopher W.; Murtugudde, Raghu

2010-11-01

Harmful algal blooms are now recognized as a significant threat to the Chesapeake Bay as they can severely compromise the economic viability of important recreational and commercial fisheries in the largest estuary of the United States. This study describes the development of empirical models for the potentially domoic acid-producing Pseudo-nitzschia species complex present in the Bay, developed from a 22-year time series of cell abundance and concurrent measurements of hydrographic and chemical properties. Using a logistic Generalized Linear Model (GLM) approach, model parameters and performance were compared over a range of Pseudo-nitzschia bloom thresholds relevant to toxin production by different species. Small-threshold blooms (≥10 cells mL -1) are explained by time of year, location, and variability in surface values of phosphate, temperature, nitrate plus nitrite, and freshwater discharge. Medium- (100 cells mL -1) to large- threshold (1000 cells mL -1) blooms are further explained by salinity, silicic acid, dissolved organic carbon, and light attenuation (Secchi) depth. These predictors are similar to other models for Pseudo-nitzschia blooms on the west coast, suggesting commonalities across ecosystems. Hindcasts of bloom probabilities at a 19% bloom prediction point yield a Heidke Skill Score of ~53%, a Probability of Detection ˜ 75%, a False Alarm Ratio of ˜ 52%, and a Probability of False Detection ˜9%. The implication of possible future changes in Baywide nutrient stoichiometry on Pseudo-nitzschia blooms is discussed.
Distance Sensitive Bloom Filters Without False Negatives

DEFF Research Database (Denmark)

Goswami, Mayank; Pagh, Rasmus; Silvestri, Francesco

2017-01-01

A Bloom filter is a widely used data-structure for representing a set S and answering queries of the form “Is x in S?”. By allowing some false positive answers (saying ‘yes’ when the answer is in fact ‘no’) Bloom filters use space significantly below what is required for storing S. In the distanc...
Phytoplankton composition of Sazlidere Dam lake, Istanbul, Turkey

Directory of Open Access Journals (Sweden)

Nese Yilmaz

2013-05-01

Full Text Available The phytoplankton composition of Sazlidere Dam lake was studied at 5 sampling sites between December 2003 - November 2005. A total of 67 taxa were recorded, representing Bacillariophyta (31, Chlorophyta (18, Cyanophyta (9, Chrysophyta (1, Cryptophyta (1, Dinophyta (3 and Euglenophyta (4. Bacillariophyta members constituted the dominant phytoplankton group in terms of species number. Nygaard’s compound index value and composition of phytoplankton indicate that the trophic state of Sazlidere Dam lake was changing from oligotrophic to mesotrophic.
Function assessment of coastal ecosystem based on phytoplankton community structure

DEFF Research Database (Denmark)

Haraguchi, Lumi

2018-01-01

on phytoplankton community structure; and 3) investigating the role of planktonic communities on the cycling of dissolved organic matter. Those objectives were addressed focusing the temperate mesohaline estuary of Roskilde Fjord (Denmark). Paper I, explores the use of Pulse-shape recording flow cytometry (PFCM...... as an energy reservoir, buffering changes in the nutrient supply. Finally, the results embedded in this thesis demonstrate the importance of integrating different time scales to understand functioning of phytoplankton communities. Phytoplankton dynamics should not be regarded just in light of inorganic......This Ph.D. project aimed to improve the knowledge on phytoplankton community structure and its influence in the carbon transfer and nutrient cycling in coastal waters, by: 1) assessing the importance of phytoplankton

Phytoplankton responses to aluminum enrichment in the South China Sea.

Science.gov (United States)

Zhou, Linbin; Liu, Jiaxing; Xing, Shuai; Tan, Yehui; Huang, Liangmin

2018-04-01

Compared to extensive studies reporting the aluminum (Al) toxicity to terrestrial plants and freshwater organisms, very little is known about how marine phytoplankton responds to Al in the field. Here we report the marine phytoplankton responses to Al enrichment in the South China Sea (SCS) using on-deck bottle incubation experiments during eight cruises from May 2010 to November 2013. Generally, Al addition alone enhanced the growth of diatom and Trichodesmium, and nitrogen fixation, but it inhibited the growth of dinoflagellates and Synechococcus. Nevertheless, Al addition alone did not influence the chlorophyll a concentration of the entire phytoplankton assemblages. By adding nitrate and phosphate simultaneously, Al enrichment led to substantial increases in chlorophyll a concentration (especially that of the picophytoplanktonenrichment. Further, by simultaneously adding different macronutrients and/or sufficient trace metals including iron, we found that the phytoplankton responses to Al enrichment were relevant to nutrients coexisting in the environment. Al enrichment may give some phytoplankton a competitive edge over using nutrients, especially the limited ones. The possible influences of Al on the competitors and grazers (predators) of some phytoplankton might indirectly contribute to the positive responses of the phytoplankton to Al enrichment. Our results indicate that Al may influence marine carbon cycle by impacting phytoplankton growth and structure in natural seawater. Copyright © 2017 Elsevier Inc. All rights reserved.
Phytoplankton diversity in the bioremediation pool in PTAPB-BATAN Yogyakarta

International Nuclear Information System (INIS)

Wijiyono; Artiningsih, Sri

2013-01-01

Research has been done on Phytoplankton Diversity in Bioremediation Pool in PTAPB-BATAN Yogyakarta. This study aims to determine the diversity of phytoplankton and phytoplankton species are numerous in the bioremediation pool in PTAPB BATAN. This study is an observational study conducted from September to November 2012. The population in this study is all kinds of phytoplankton that live in the bioremediation pool. The sample was filtered with all phytoplankton plankton net at each sampling point. This study was conducted to determine the point of sampling as much as 3 points, namely at the inlet, the center of the pond, and exit channel, with each point done 3 times repetition. Sampling was done by taking as much as 50 liters of water at each sample point, the water sample is filtered directly into the plankton net. Filtered water put into flakon bottles. Observation and identification of plankton were done in the laboratory. The research found as many as 21 species of phytoplankton consisting of Scenedesmus acuminatus, Scenedesmus quadricauda, Closterium moniiferum, Pleurosigma sp., Rivularia bullata, Chroococcus sp., Cocconeis sp., Pinnularia viridis, Navicula sp., Spirogyra sp., Thiopedia rosea, Cyclotella sp., Minidiscus sp., Achnantes sp., ChIorella sp., Oscillatoria sp., Hemiaulus sp., Surirella sp., Chattonella sp., Thalasiossira mala, Leuvenia sp. Phytoplankton density value of 5.330 ind / I. Phytoplankton diversity index value was 2.6062, included in the medium category. (author)
CNP stoichiometry of a lipid-synthesising zooplankton, Calanus finmarchicus, from winter to spring bloom in a sub-Arctic sound

Science.gov (United States)

Aubert, A. B.; Svensen, C.; Hessen, D. O.; Tamelander, T.

2013-02-01

The aim of this study was to investigate the seasonal stoichiometry of the high-latitude lipid-synthesising copepod Calanus finmarchicus and assess how this would affect dietary demands with season, ontogeny and lipid storage. C:N:P ratios in different stages (adults, copepodite V and IV), in eggs and faecal pellets as well as in bulk food (seston) was analysed in a sub-Arctic Norwegian sound (69° 47'N, 19° 19'E) from late February to mid-May 2009. The period covered the phytoplankton bloom and was divided into four sequences of the bloom based on chl a and seston C:chl a ratio variations. The calculation of the somatic elemental C:N and C:P body ratios (without the lipid storage) indicates that nearly homeostatic control in C. finmarchicus is maintained in somatic tissues within stages, while not if the lipid storage pool is included. Nutrient limitation was assessed calculating threshold elemental ratios based on the somatic body ratios and for different sets of assimilation efficiencies, and indicated a predominant C limitation that may reflect demands for lipid storage. The results suggest that stoichiometric composition and demands in such high-latitude, lipid-storing species strongly depend on stage and season, and the large contribution of storage lipids highlights the need for a two-compartment approach for lipid-synthesising species, with different dietary requirements for somatic growth and for lipid storage.
Spatio-temporal organization of phytoplankton in Peipsi Lake

Directory of Open Access Journals (Sweden)

Sharov Andrey

2016-12-01

Full Text Available In the article, the results of the study of phytoplankton received at 16 stations of the Lake Peipsi in the spring (May, summer (August and autumn (October within the period of 2012–2015 were analyzed. 186 phytoplankton species were found. The list of mass taxa is given. It was noted that phytoplankton biomass had wide amplitude of annual average values in different lakes: Lake Peipsi/Chudskoe 2.1 ± 0.2 (0.3–23.0 mg / L; Lake Pihkva/Pskovskoe 5.4 ± 1.4 (0.4–34.0 mg / L and Lake Lämmijärv/Teploe 6.1 ± 1.2 (3.4–25.1 mg / l. According to species composition, structure and biomass of phytoplankton the lake belongs to the mesotrophic reservoirs with eutrophic features, as it was in previous years of observation. The water quality in the different parts of Lake Peipsi corresponded to conditionally pure water (1st quality class and slightly polluted one(2nd quality class. Correlation between characteristics of phytoplankton and the environmental factors (temperature, water level, transparency, N and P concentration in water was detected.
Climate Change and Algal Blooms =

Science.gov (United States)

Lin, Shengpan

Algal blooms are new emerging hazards that have had important social impacts in recent years. However, it was not very clear whether future climate change causing warming waters and stronger storm events would exacerbate the algal bloom problem. The goal of this dissertation was to evaluate the sensitivity of algal biomass to climate change in the continental United States. Long-term large-scale observations of algal biomass in inland lakes are challenging, but are necessary to relate climate change to algal blooms. To get observations at this scale, this dissertation applied machine-learning algorithms including boosted regression trees (BRT) in remote sensing of chlorophyll-a with Landsat TM/ETM+. The results show that the BRT algorithm improved model accuracy by 15%, compared to traditional linear regression. The remote sensing model explained 46% of the total variance of the ground-measured chlorophyll- a in the first National Lake Assessment conducted by the US Environmental Protection Agency. That accuracy was ecologically meaningful to study climate change impacts on algal blooms. Moreover, the BRT algorithm for chlorophyll- a would not have systematic bias that is introduced by sediments and colored dissolved organic matter, both of which might change concurrently with climate change and algal blooms. This dissertation shows that the existing atmospheric corrections for Landsat TM/ETM+ imagery might not be good enough to improve the remote sensing of chlorophyll-a in inland lakes. After deriving long-term algal biomass estimates from Landsat TM/ETM+, time series analysis was used to study the relations of climate change and algal biomass in four Missouri reservoirs. The results show that neither temperature nor precipitation was the only factor that controlled temporal variation of algal biomass. Different reservoirs, even different zones within the same reservoir, responded differently to temperature and precipitation changes. These findings were further
Ecotoxicology of bromoacetic acid on estuarine phytoplankton.

Science.gov (United States)

Gordon, Ana R; Richardson, Tammi L; Pinckney, James L

2015-11-01

Bromoacetic acid is formed when effluent containing chlorine residuals react with humics in natural waters containing bromide. The objective of this research was to quantify the effects of bromoacetic acid on estuarine phytoplankton as a proxy for ecosystem productivity. Bioassays were used to measure the EC50 for growth in cultured species and natural marine communities. Growth inhibition was estimated by changes in chlorophyll a concentrations measured by fluorometry and HPLC. The EC50s for cultured Thalassiosira pseudonana were 194 mg L(-1), 240 mg L(-1) for Dunaliella tertiolecta and 209 mg L(-1) for Rhodomonas salina. Natural phytoplankton communities were more sensitive to contamination with an EC50 of 80 mg L(-1). Discriminant analysis suggested that bromoacetic acid additions cause an alteration of phytoplankton community structure with implications for higher trophic levels. A two-fold EC50 decrease in mixed natural phytoplankton populations affirms the importance of field confirmation for establishing water quality criteria. Copyright © 2015 Elsevier Ltd. All rights reserved.
Seasonality of coastal zone scanner phytoplankton pigment in the offshore oceans

Science.gov (United States)

Banse, K.; English, D. C.

1994-01-01

The NASA Global Ocean Data Set of plant pigment concentrations in the upper euphotic zone is evaluated for diserning geographical and temporal patterns of seasonality in the open sea. Monthly medians of pigment concentrations for all available years are generated for fields of approximately 77,000 sq km. For the climatological year, highest and lowest medians, month of occurence of the highest median, ratio of highest to lowest medians, and absolute range between the highest and lowest medians are mapped ocean-wide between 62.5 deg N and 62.5 deg S. Seasonal cycles are depicted for 48 sites. In much of the offshore ocean, seasonality of pigment is inferred to be driven almost equally by the interaction of the abiotic environment with phytoplankton physiology and the loss of cells from grazing. Special emphasis among natural domains or provinces is given to the Subantarctic water ring, with no seasonality in its low chlorophyll concentrations in spite of strong environmental forcing, and the narrow Transition Zones, a few degrees of latitude on the equatorial sides of the Subtropical Convergences of the southern hemisphere and their homologs in the northern hemisphere, which have late winter blooms caused by nutrient injection into the upper layers.
Rethinking Bloom's Taxonomy: Implications for Testing and Assessment.

Science.gov (United States)

Anderson, Lorin W.

This paper describes a work in progress on a second edition of "Taxonomy of Educational Objectives, The Classification of Educational Goals, Handbook I: Cognitive Domain," also known as "Bloom's Taxonomy" (B. Bloom and others, Eds., 1956). The new edition will be grounded in the collective wisdom of the original…
Growth of Phytoplankton in Different Fertilizer Media | KADIRI ...

African Journals Online (AJOL)

... medium and there was no significant difference between Scenedesmus and Oscillatoria sp. whereas in the inorganic fertilizer, there was no significant difference between the growth response from all phytoplankton. All experiments lasted 14 days. Key words: Aquaculture, Phytoplankton Production, Biofertilizer, Inorganic
Hydrodynamic control of microphytoplankton bloom in a coastal sea

Indian Academy of Sciences (India)

29

Mucilaginous exudates from the alga due to heat and silicate stress likely ... Bay receives enormous fresh water flux from large and medium rivers of ..... attribute it to: (i) low phytoplankton abundance due to seasonal factors, (ii) phytoplankton.
Harmful algal bloom smart device application: using image analysis and machine learning techniques for early classification of harmful algal blooms (SETAC presentation)

Science.gov (United States)

Reports of toxic cyanobacterial blooms, also known as Harmful Algal Blooms (HABS) have increased drastically in recent years. HABS impact human health from causing mild allergies to liver damage and death. The Ecological Stewardship Institute (ESI) at Northern Kentucky Universi...
Massive salp swarm tilts ocean's chemical balance

Science.gov (United States)

Schultz, Colin

2012-03-01

A surge of nutrients to the warm waters off the southeastern coast of Australia during the highly productive austral spring can spark an explosion in the phytoplankton population. Where phytoplankton bloom, so do the predators that feed on them. Some, like the globally prevalent salp Thalia democratica, excel at capitalizing on the transient nature of phytoplankton blooms. Salps are tiny gelatinous creatures that feed on plankton and other microorganisms by straining them from the ocean water with a fine mesh sieve. A rarity among multicellular animals, salps retain the ability to reproduce by asexual budding, with one salp spawning a clone of itself. This budding, combined with sexual reproduction, enables salp populations to grow by up to 250% per day.
Tropical cyanobacterial blooms: a review of prevalence, problem taxa, toxins and influencing environmental factors

Directory of Open Access Journals (Sweden)

Maxine A.D. Mowe

2014-12-01

Full Text Available Toxic cyanobacterial blooms are a major issue in freshwater systems in many countries. The potentially toxic species and their ecological causes are likely to be different in tropical zones from those in temperate water bodies; however, studies on tropical toxic cyanobacterial blooms are sporadic and currently there is no global synthesis. In this review, we examined published information on tropical cyanobacterial bloom occurrence and toxin production to investigate patterns in their growth and distribution. Microcystis was the most frequently occurring bloom genus throughout tropical Asia, Africa and Central America, while Cylindrospermopsis and Anabaena blooms occurred in various locations in tropical Australia, America and Africa. Microcystis blooms were more prevalent during the wet season while Cylindrospermopsis blooms were more prevalent during the dry period. Microcystin was the most encountered toxin throughout the tropics. A meta-analysis of tropical cyanobacterial blooms showed that Microcystis blooms were more associated with higher total nitrogen concentrations, while Cylindrospermopsis blooms were more associated with higher maximum temperatures. Meta-analysis also showed a positive linear relationship between levels of microcystin and N:P (nitrate:phosphate ratio. Tropical African Microcystis blooms were found to have the lowest microcystin levels in relation to biomass and N:P (nitrate:phosphate compared to tropical Asian, Australian and American blooms. There was also no significant correlation between microcystin concentration and cell concentration for tropical African blooms as opposed to tropical Asian and American blooms. Our review illustrates that some cyanobacteria and toxins are more prevalent in tropical areas. While some tropical countries have considerable information regarding toxic blooms, others have few or no reported studies.
Optical detection of Prorocentrum donghaiense blooms based on multispectral reflectance

Institute of Scientific and Technical Information of China (English)

TAO Bangyi; PAN Delu; MAO Zhihua; SHEN Yuzhang; ZHU Qiankun; CHEN Jianyu

2013-01-01

Prorocentrum donghaiense is one of the most common red tide causative dinoflagellates in the Changjiang (Yangtze) River Estuary and the adjacent area of the East China Sea. It causes large-scale blooms in late spring and early summer that lead to widespread ecologic and economic damage. A means for distinguish-ing dinoflagellate blooms from diatom (Skeletonema costatum) blooms is desired. On the basis of measure-ments of remote sensing reflectance [Rrs(λ)] and inherent optical parameters, the potential of using a mul-tispectral approach is assessed for discriminating the algal blooms due to P. donghaiense from those due to S. costatum. The behavior of two reflectance ratios [R1 =Rrs(560)/Rrs(532) and R2 =Rrs(708)/Rrs(665)], suggests that differentiation of P. donghaiense blooms from diatom bloom types is possible from the current band setup of ocean color sensors. It is found that there are two reflectance ratio regimes that indicate a bloom is dominated by P. donghaiense: (1) R1 >1.55 and R2 1.75 and R2 ?1.0. Various sensitivity analyses are conducted to investigate the effects of the variation in varying levels of chlorophyll concentration and colored dissolved organic matter (CDOM) as well as changes in the backscattering ratio (bbp/bp) on the efficacy of this multispectral approach. Results indicate that the intensity and inherent op-tical properties of the algal species explain much of the behavior of the two ratios. Although backscattering influences the amplitude of Rrs(λ), especially in the 530 and 560 nm bands, the discrimination between P. donghaiense and diatoms is not significantly affected by the variation of bbp/bp. Since a CDOM(440) in coastal areas of the ECS is typically lower than 1.0 m−1 in most situations, the presence of CDOM does not interfere with this discrimination, even as SCDOM varies from 0.01 to 0.026 nm−1. Despite all of these effects, the dis-crimination of P. donghaiense blooms from diatom blooms based on multispectral
Water quality status and phytoplankton composition in Soetendalvlei ...

African Journals Online (AJOL)

Three wetlands on the Agulhas Plain, for which no limnological information was available, were investigated in order to provide baseline data on their present water quality and phytoplankton community structure. Physicochemical variables were assessed and phytoplankton biomass and community analyses were ...
Population dynamics of light-limited phytoplankton : Microcosm experiments

NARCIS (Netherlands)

Huisman, Jef

This paper investigates the extent to which the predictions of an elementary model for light-limited growth are matched by laboratory experiments with light-limited phytoplankton. The model and experiments link the population dynamics of phytoplankton species with changes in the light gradient
Does biodiversity of estuarine phytoplankton depend on hydrology?

NARCIS (Netherlands)

Ferreira, JG; Wolff, WJ; Simas, TC; Bricker, SB

2005-01-01

Phytoplankton growth in estuaries is controlled by factors such as flushing, salinity tolerance, light, nutrients and grazing. Here, we show that biodiversity of estuarine phytoplankton is related to flushing, and illustrate this for some European estuaries. The implications for the definition of
Phosphorus physiological ecology and molecular mechanisms in marine phytoplankton.

Science.gov (United States)

Lin, Senjie; Litaker, Richard Wayne; Sunda, William G

2016-02-01

Phosphorus (P) is an essential nutrient for marine phytoplankton and indeed all life forms. Current data show that P availability is growth-limiting in certain marine systems and can impact algal species composition. Available P occurs in marine waters as dissolved inorganic phosphate (primarily orthophosphate [Pi]) or as a myriad of dissolved organic phosphorus (DOP) compounds. Despite numerous studies on P physiology and ecology and increasing research on genomics in marine phytoplankton, there have been few attempts to synthesize information from these different disciplines. This paper is aimed to integrate the physiological and molecular information on the acquisition, utilization, and storage of P in marine phytoplankton and the strategies used by these organisms to acclimate and adapt to variations in P availability. Where applicable, we attempt to identify gaps in our current knowledge that warrant further research and examine possible metabolic pathways that might occur in phytoplankton from well-studied bacterial models. Physical and chemical limitations governing cellular P uptake are explored along with physiological and molecular mechanisms to adapt and acclimate to temporally and spatially varying P nutrient regimes. Topics covered include cellular Pi uptake and feedback regulation of uptake systems, enzymatic utilization of DOP, P acquisition by phagotrophy, P-limitation of phytoplankton growth in oceanic and coastal waters, and the role of P-limitation in regulating cell size and toxin levels in phytoplankton. Finally, we examine the role of P and other nutrients in the transition of phytoplankton communities from early succession species (diatoms) to late succession ones (e.g., dinoflagellates and haptophytes). © 2015 Phycological Society of America.
Pigment signatures of phytoplankton communities in the Beaufort Sea

Science.gov (United States)

Coupel, P.; Matsuoka, A.; Ruiz-Pino, D.; Gosselin, M.; Marie, D.; Tremblay, J.-É.; Babin, M.

2015-02-01

Phytoplankton are expected to respond to recent environmental changes of the Arctic Ocean. In terms of bottom-up control, modifying the phytoplankton distribution will ultimately affect the entire food web and carbon export. However, detecting and quantifying changes in phytoplankton communities in the Arctic Ocean remains difficult because of the lack of data and the inconsistent identification methods used. Based on pigment and microscopy data sampled in the Beaufort Sea during summer 2009, we optimized the chemotaxonomic tool CHEMTAX (CHEMical TAXonomy) for the assessment of phytoplankton community composition in an Arctic setting. The geographical distribution of the main phytoplankton groups was determined with clustering methods. Four phytoplankton assemblages were determined and related to bathymetry, nutrients and light availability. Surface waters across the whole survey region were dominated by prasinophytes and chlorophytes, whereas the subsurface chlorophyll maximum was dominated by the centric diatoms Chaetoceros socialis on the shelf and by two populations of nanoflagellates in the deep basin. Microscopic counts showed a high contribution of the heterotrophic dinoflagellates Gymnodinium and Gyrodinium spp. to total carbon biomass, suggesting high grazing activity at this time of the year. However, CHEMTAX was unable to detect these dinoflagellates because they lack peridinin. In heterotrophic dinoflagellates, the inclusion of the pigments of their prey potentially leads to incorrect group assignments and some misinterpretation of CHEMTAX. Thanks to the high reproducibility of pigment analysis, our results can serve as a baseline to assess change and spatial or temporal variability in several phytoplankton populations that are not affected by these misinterpretations.
Hydrodynamic control of microphytoplankton bloom in a coastal sea

Indian Academy of Sciences (India)

Hydrodynamic control of microphytoplankton bloom in a coastal sea ... many times more than what could be accounted for by solar insolation and nutrient levels. ... and stable water column and weak winds left undisturbed, the transient bloom.

Latitudinal variation of phytoplankton communities in the western Arctic Ocean

Science.gov (United States)

Min Joo, Hyoung; Lee, Sang H.; Won Jung, Seung; Dahms, Hans-Uwe; Hwan Lee, Jin

2012-12-01

Recent studies have shown that photosynthetic eukaryotes are an active and often dominant component of Arctic phytoplankton assemblages. In order to explore this notion at a large scale, samples were collected to investigate the community structure and biovolume of phytoplankton along a transect in the western Arctic Ocean. The transect included 37 stations at the surface and subsurface chlorophyll a maximum (SCM) depths in the Bering Sea, Chukchi Sea, and Canadian Basin from July 19 to September 5, 2008. Phytoplankton (>2 μm) were identified and counted. A cluster analysis of abundance and biovolume data revealed different assemblages over the shelf, slope, and basin regions. Phytoplankton communities were composed of 71 taxa representing Dinophyceae, Cryptophyceae, Bacillariophyceae, Chrysophyceae, Dictyochophyceae, Prasinophyceae, and Prymnesiophyceae. The most abundant species were of pico- to nano-size at the surface and SCM depths at most stations. Nano- and pico-sized phytoplankton appeared to be dominant in the Bering Sea, whereas diatoms and nano-sized plankton provided the majority of taxon diversity in the Bering Strait and in the Chukchi Sea. From the western Bering Sea to the Bering Strait, the abundance, biovolume, and species diversity of phytoplankton provided a marked latitudinal gradient towards the central Arctic. Although pico- and nano-sized phytoplankton contributed most to cell abundance, their chlorophyll a contents and biovolumes were less than those of the larger micro-sized taxa. Micro-sized phytoplankton contributed most to the biovolume in the largely ice-free waters of the western Arctic Ocean during summer 2008.
An Artificial Neural Network Based Short-term Dynamic Prediction of Algae Bloom

Directory of Open Access Journals (Sweden)

Yao Junyang

2014-06-01

Full Text Available This paper proposes a method of short-term prediction of algae bloom based on artificial neural network. Firstly, principal component analysis is applied to water environmental factors in algae bloom raceway ponds to get main factors that influence the formation of algae blooms. Then, a model of short-term dynamic prediction based on neural network is built with the current chlorophyll_a values as input and the chlorophyll_a values in the next moment as output to realize short-term dynamic prediction of algae bloom. Simulation results show that the model can realize short-term prediction of algae bloom effectively.
Morphological switch to a resistant subpopulation in response to viral infection in the bloom-forming coccolithophore Emiliania huxleyi.

Science.gov (United States)

Frada, Miguel José; Rosenwasser, Shilo; Ben-Dor, Shifra; Shemi, Adva; Sabanay, Helena; Vardi, Assaf

2017-12-01

Recognizing the life cycle of an organism is key to understanding its biology and ecological impact. Emiliania huxleyi is a cosmopolitan marine microalga, which displays a poorly understood biphasic sexual life cycle comprised of a calcified diploid phase and a morphologically distinct biflagellate haploid phase. Diploid cells (2N) form large-scale blooms in the oceans, which are routinely terminated by specific lytic viruses (EhV). In contrast, haploid cells (1N) are resistant to EhV. Further evidence indicates that 1N cells may be produced during viral infection. A shift in morphology, driven by meiosis, could therefore constitute a mechanism for E. huxleyi cells to escape from EhV during blooms. This process has been metaphorically coined the 'Cheshire Cat' (CC) strategy. We tested this model in two E. huxleyi strains using a detailed assessment of morphological and ploidy-level variations as well as expression of gene markers for meiosis and the flagellate phenotype. We showed that following the CC model, production of resistant cells was triggered during infection. This led to the rise of a new subpopulation of cells in the two strains that morphologically resembled haploid cells and were resistant to EhV. However, ploidy-level analyses indicated that the new resistant cells were diploid or aneuploid. Thus, the CC strategy in E. huxleyi appears to be a life-phase switch mechanism involving morphological remodeling that is decoupled from meiosis. Our results highlight the adaptive significance of morphological plasticity mediating complex host-virus interactions in marine phytoplankton.
[Ecological characteristics of phytoplankton in Suining tributary under bio-remediation].

Science.gov (United States)

Liu, Dongyan; Zhao, Jianfu; Zhang, Yalei; Ma, Limin

2005-04-01

Based on the analyses of phytoplankton community in the treated and untreated reaches of Suining tributary of Suzhou River, this paper studied the effects of bio-remediation on phytoplankton. As the result of the remediation, the density and Chl-a content of phytoplankton in treated reach were greatly declined, while the species number and Shannon-Wiener diversity index ascended obviously. The percentage of Chlorophyta and Baeillariophyta ascended, and some species indicating medium-and oligo-pollution were found. All of these illustrated that bio-remediation engineering might significantly benefit to the improvement of phytoplankton community structure and water quality.
Seasonal Variability of Phytoplankton Population in the Brahmani ...

African Journals Online (AJOL)

Seasonal Variability of Phytoplankton Population in the Brahmani Estuary of Orissa, India. S Palleyi, RN Kar, CR Panda. Abstract. The dynamic relationship of water physico-chemical characteristics with phytoplankton has long been of great interest in both experimental ecology and environmental management. This study ...
Consortial brown tide - picocyanobacteria blooms in Guantánamo Bay, Cuba.

Science.gov (United States)

Hall, Nathan S; Litaker, R Wayne; Kenworthy, W Judson; Vandersea, Mark W; Sunda, William G; Reid, James P; Slone, Daniel H; Butler, Susan

2018-03-01

A brown tide bloom of Aureoumbra lagunensis developed in Guantánamo Bay, Cuba during a period of drought in 2013 that followed heavy winds and rainfall from Hurricane Sandy in late October 2012. Based on satellite images and water turbidity measurements, the bloom appeared to initiate in January 2013. The causative species (A. lagunensis) was confirmed by microscopic observation, and pigment and genetic analyses of bloom samples collected on May 28 of that year. During that time, A. lagunensis reached concentrations of 900,000 cells ml -1 (28 ppm by biovolume) in the middle portion of the Bay. Samples could not be collected from the northern (Cuban) half of the Bay because of political considerations. Subsequent sampling of the southern half of the Bay in November 2013, April 2014, and October 2014 showed persistent lower concentrations of A. lagunensis, with dominance shifting to the cyanobacterium Synechococcus (up to 33 ppm in April), an algal group that comprised a minor bloom component on May 28. Thus, unlike the brown tide bloom in Laguna Madre, which lasted 8 years, the bloom in Guantánamo Bay was short-lived, much like recent blooms in the Indian River, Florida. Although hypersaline conditions have been linked to brown tide development in the lagoons of Texas and Florida, observed euhaline conditions in Guantánamo Bay (salinity 35-36) indicate that strong hypersalinity is not a requirement for A. lagunensis bloom formation. Microzooplankton biomass dominated by ciliates was high during the observed peak of the brown tide, and ciliate abundance was high compared to other systems not impacted by brown tide. Preferential grazing by zooplankton on non-brown tide species, as shown in A. lagunensis blooms in Texas and Florida, may have been a factor in the development of the Cuban brown tide bloom. However, subsequent selection of microzooplankton capable of utilizing A. lagunensis as a primary food source may have contributed to the short-lived duration
[Phytoplankton community in a recreational fishing lake, Brazil].

Science.gov (United States)

Matsuzaki, Mayla; Mucci, José Luiz Negrão; Rocha, Aristides Almeida

2004-10-01

The assessment of water quality and phytoplankton community in recreational environments allows to setting management programs aiming at preventing potential harm to human health. The purpose of the present study was to describe phytoplankton seasonal changes in a freshwater system and their relation to water quality. The recreational fishing lake is located in the southern area of the city of São Paulo, Brazil. Water samples were collected in three previously selected sites in the lake throughout a year and analyzed regarding floristic composition and physical and chemical parameters. The phytoplankton qualitative analysis revealed 91 taxa distributed among eight classes: Chlorophyceae, Cyanophyceae, Euglenophyceae, Zygnemaphyceae, Bacillariophyceae, Xantophyceae, Dinophyceae, and Chrysophyceae. Some physical and chemical parameters seemed to influence phytoplankton community behavior. Chlorophyceae development was favored by local conditions. Among the species of cyanobacteria identified, Microcystis paniformis, Cylindrospermopsis raciborskii, and Anabaena species were the most important due to their ability to produce toxins, posing a high risk to public health. Some physical and chemical parameters had an impact on the structure of phytoplankton community. The presence of Microcystis paniformis, Cylindrospermopsis raciborskii and Anabaena species indicates toxic potential and likelihood of public health problems unless there is constant monitoring. Further studies are recommended to prevent hazardous effects to the environment and public health.
Seasonal Dynamics of Haptophytes and dsDNA Algal Viruses Suggest Complex Virus-Host Relationship.

Science.gov (United States)

Johannessen, Torill Vik; Larsen, Aud; Bratbak, Gunnar; Pagarete, António; Edvardsen, Bente; Egge, Elianne D; Sandaa, Ruth-Anne

2017-04-20

Viruses influence the ecology and diversity of phytoplankton in the ocean. Most studies of phytoplankton host-virus interactions have focused on bloom-forming species like Emiliania huxleyi or Phaeocystis spp. The role of viruses infecting phytoplankton that do not form conspicuous blooms have received less attention. Here we explore the dynamics of phytoplankton and algal viruses over several sequential seasons, with a focus on the ubiquitous and diverse phytoplankton division Haptophyta, and their double-stranded DNA viruses, potentially with the capacity to infect the haptophytes. Viral and phytoplankton abundance and diversity showed recurrent seasonal changes, mainly explained by hydrographic conditions. By 454 tag-sequencing we revealed 93 unique haptophyte operational taxonomic units (OTUs), with seasonal changes in abundance. Sixty-one unique viral OTUs, representing Megaviridae and Phycodnaviridae , showed only distant relationship with currently isolated algal viruses. Haptophyte and virus community composition and diversity varied substantially throughout the year, but in an uncoordinated manner. A minority of the viral OTUs were highly abundant at specific time-points, indicating a boom-bust relationship with their host. Most of the viral OTUs were very persistent, which may represent viruses that coexist with their hosts, or able to exploit several host species.
Application of a laser fluorometer for discriminating phytoplankton species

Science.gov (United States)

Chen, Peng; Pan, Delu; Mao, Zhihua

2015-04-01

A portable laser-induced fluorescence system for discriminating phytoplankton species has been developed. It consists of a high pulsed repetition frequency (10-kHz) microchip laser at 405 nm, a reflective fluorescent probe and a broadband micro spectrometer. The measured fluorescent spectra were overlapped by various fluorescent components, and were then decomposed by a bi-Gaussian mixture model. A spectral shape description index was designed to characterize fluorescent spectral shapes for descriminating the phytoplankton species cultured in our laboratory. Using clustering analysis, the samples of eight phytoplankton species belonging to two divisions of Bacillariophyta and Dinophyta were divided into six categories: 1) Chaetoceros debilis, Thalassiosira rotula; 2) Prorocentrum donghaiense, Prorocentrum dentatum; 3) Gymnodinium simplex; 4) Alexandrium tamarense; 5) Karenia mikimotoi; and 6) Akashiwo sanguinea. The phytoplankton species belonging to Bacillariophyta were well separated from those belonging to Dinophyta. In addition, the phytoplankton species belonging to Dinophyta were successfully distinguished from each other at genus level. The portable system is expected to be used both in vivo and in the field.
Phytoplankton species composition of four ecological provinces in Yellow Sea, China

Science.gov (United States)

Li, Xiaoqian; Feng, Yuanyuan; Leng, Xiaoyun; Liu, Haijiao; Sun, Jun

2017-12-01

The ecological province based on phytoplankton species composition is important to understanding the interplay between environmental parameters and phytoplankton species composition. The aim of this study was to establish phytoplankton species composition ecological pattern thus elucidate the relationship between environmental factors and the phytoplankton species composition in the ecological provinces. Phytoplankton samples were collected from 31 stations in Yellow Sea (121.00°-125.00°E, 32.00°-39.22°N) in November 2014. The samples were enumerated and identified with the Utermöhl method under an optical inverted microscope-AE2000 with magnifications of 200 × or 400 ×. In the present study, a total of 141 taxa belonging to 60 genera of 4 phyla of phytoplankton were identified, among them 101 species of 45 genera were Bacillariophyta, 36 species of 11 genera were Dinophyta, 3 species of 3 genera were Chrysophyta and 1 species of 1 genera was Chlorophyta. The study area was divided into 4 ecological provinces according to an unsupervised cluster algorithm applied to the phytoplankton biomass. A T-S (Temperature-Salinity) scatter diagram depicted with data of water temperature and salinity defined by environmental provinces matched well with the ecological provinces. The results of Canonical Correspondence Analysis (CCA) indicated that the phytoplankton species composition was mainly correlated with temperature, salinity and silicate concentration in the studied area. A method of establishing ecological provinces is useful to further understanding the environmental effects on the marine phytoplankton species composition and the consequent marine biogeochemistry.
phytoplankton diversity indices of Osse River, Edo State, Nigeria

African Journals Online (AJOL)

USER

The phytoplankton diversity indices of Osse River, Edo State, Nigeria, were investigated monthly from January ... In terms of abundance, Bacillariophyceae had the highest distribution of phytoplankton (79.00%), ...... erosion beach in Lagos.
Spatial and temporal patterns of phytoplankton abundance and ...

African Journals Online (AJOL)

Bacillariophyta was the most abundant group (48.17% of total phytoplankton) and was uniformly distributed in all waters, followed by Cyanobacteria (33.33%), which decreased with distance offshore. Chlorophyta, the third highest in abundance (15.5%), increased with distance offshore. A total of 92 phytoplankton species ...
Response of phytoplankton assemblages isolated for short periods ...

African Journals Online (AJOL)

The response of phytoplankton assemblages isolated in enclosures for short periods of time was examined in hyper-eutrophic Lake Chivero (Harare, Zimbabwe), to determine the factors that influenced the structure of the phytoplankton community, after noticing a marked decline in the dominance of Microcystis aeruginosa ...
Effects of a future warmer ocean on the coexisting copepods Calanus finmarchicus and C. glacialis in Disko Bay, Western Greenland

DEFF Research Database (Denmark)

Kjellerup, Sanne; Dünweber, Michael; Swalethorp, Rasmus

2012-01-01

The effects of temperature and food was examined for Calanus finmarchicus and C. glacialis during 3 phases of the phytoplankton spring bloom in Disko Bay, western Greenland. The 2 species were collected during pre-bloom, bloom, and post-bloom and exposed to temperatures from 0 to 10°C, combined...... production. Our results suggest that a future warmer ocean will reduce the advantage of early spawning by C. glacialis and that C. finmarchicus will become increasingly prevalent...
Development of a Continuous Phytoplankton Culture System for Ocean Acidification Experiments

Directory of Open Access Journals (Sweden)

Cathryn Wynn-Edwards

2014-06-01

Full Text Available Around one third of all anthropogenic CO2 emissions have been absorbed by the oceans, causing changes in seawater pH and carbonate chemistry. These changes have the potential to affect phytoplankton, which are critically important for marine food webs and the global carbon cycle. However, our current knowledge of how phytoplankton will respond to these changes is limited to a few laboratory and mesocosm experiments. Long-term experiments are needed to determine the vulnerability of phytoplankton to enhanced pCO2. Maintaining phytoplankton cultures in exponential growth for extended periods of time is logistically difficult and labour intensive. Here we describe a continuous culture system that greatly reduces the time required to maintain phytoplankton cultures, and minimises variation in experimental pCO2 treatments over time. This system is simple, relatively cheap, flexible, and allows long-term experiments to be performed to further our understanding of chronic responses and adaptation by phytoplankton species to future ocean acidification.
A review of carbon blooms on JET and TFTR

International Nuclear Information System (INIS)

Ulrickson, M.

1990-01-01

Operation of JET and TFTR at high auxiliary heating power has resulted in the occurrence of phenomena called carbon blooms. The carbon bloom is characterized by a rapid increases in the emission of carbon spectral lines, the Z eff , the radiated power, and the plasma density. There is also a concurrent decrease in the neutron emission rate, stored energy, and plasma pressure. On both machines the source of the carbon is observed to be at localized (both toroidally and polidally) hot spots on either the divertor plates or limiters. The localized hot spots are due to one or more of the following: disruption damage spots, misalignment of tiles, and/or exposed edges of tiles. The occurrence of carbon blooms limits the performance of the highest input power plasmas on both machines. This paper reviews the carbon bloom phenomenon as it occurs on both JET and TFTR. (orig.)
Health risk assessment standards of cyanobacteria bloom occurrence in bathing sites

Directory of Open Access Journals (Sweden)

Agnieszka Stankiewicz

2011-03-01

Full Text Available Threat for human health appears during a massive cyanobacteria bloom in potable water used for human consumption or in basins used for recreational purposes. General health risk assessment standards and preventive measures to be taken by sanitation service were presented in scope of: – evaluation of cyanobacteria bloom occurrence in bathing sites / water bodies, – procedures in case of cyanobacteria bloom, including health risk assessment and decision making process to protect users’ health at bathing sites, – preventive measures, to be taken in case of cyanobacteria bloom occurrence in bathing sites and basins, where bathing sites are located.
Biomass relations between phytoplankton and zooplankton in Goa waters

Digital Repository Service at National Institute of Oceanography (India)

Pant, A.; Matondkar, S.G.P.; Goswami, S.C.

Biomass of phytoplankton and zooplankton, measured as particulate oxidizable carbon, shows that at shallowest stations (5 m) there is large excess of phytoplankton organic carbon over zooplankton carbon in all the samples There is no significant...
Peculiarities of the Woody Plants Re-Bloom

OpenAIRE

Opalko Olga Anatolievna; Opalko Anatoly Ivanovich

2015-01-01

The data of literary sources concerning the bloom of angiosperm plants and deviation in the development of a flower and inflorescence, in particular untimely flowering, was generalized; our observation results of some peculiarities of re-bloom of woody plants in the National Dendrological Park “Sofiyivka” of NAS of Ukraine (NDP “Sofiyivka”) were discussed. The flowering process was formed during a long-term evolution of a propagation system of angiosperm plants as a basis of fertilization and...
Concentrations of heavy metals in sediment and organisms during a harmful algal bloom (HAB) at Kun Kaak Bay, Sonora, Mexico

International Nuclear Information System (INIS)

Garcia-Hernandez, Jaqueline; Garcia-Rico, Leticia; Jara-Marini, Martin E.; Barraza-Guardado, Ramon; Hudson Weaver, Amy

2005-01-01

In early April 2003, fishermen from Kino Bay Sonora alerted us about a massive die-off of fish and mollusks occurring at Kun Kaak Bay. Phytoplankton samples taken on 17 May 2003 reported the presence of a harmful algal bloom composed of Chatonella marina, Chatonella cf. ovata, Gymnodinium catenatum and Gymnodinium sanguineum. On 22 of May, we collected samples of water, sediment and organisms at the affected area. Physicochemical parameters and nutrients were measured in water samples from different depths. Sediment and benthic organisms were analyzed for Cd, Cu, Zn, Pb and Hg. We found concentrations of heavy metals higher than background levels for this area. Cadmium and Lead concentrations in sediment from the HAB area were up to 6x greater than background levels and Cd in mollusks was 8x greater than regulations allow. A relationship between elevated Cd and Pb concentrations in sediment and the survival of toxic dinoflagellates is suspected

Some links on this page may take you to non-federal websites. Their policies may differ from this site.