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Sample records for change phytoplankton community

  1. 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.

  2. Morphofunctional changes of phytoplankton community during pluvial anomaly in a tropical reservoir

    Directory of Open Access Journals (Sweden)

    FRA Câmara

    Full Text Available AbstractThe present study focuses on the structure and function of phytoplankton community during periods of marked changes in hydrological traits, influenced by an atypical climatic event (La Niña and its impact on Armando Ribeiro Gonçalves Reservoir of Rio Grande do Norte, situated in the Caatinga biome of northeastern Brazil. The main questions addressed were: What are the effects of environmental factors on the temporal variation of Morphologically Based Functional Group (MBFG of phytoplankton community? How does the composition of cyanobacterial species shift in relation to high and low trends of phytoplankton diversity? The samples were collected monthly during 2008-2009 and analyzed for pH, temperature, electrical conductivity, dissolved oxygen content and the nutrients, such as, nitrate-nitrogen, ammoniacal nitrogen, total nitrogen and orthophosphate. Phytoplankton samples were collected for both qualitative and quantitative analyses to evaluate species richness index and species diversity index. The data was divided into two distinct hydrodynamic periods of instability and stability. The results demonstrate considerable changes in dissolved oxygen content, water transparency and nitrogen nutrients, which directly influenced the MBFG of phytoplankton community in space and time. The instability of reservoir water was caused by heavy rainfall, which exerts atypical external disturbances. The seasonal variation of MBFG demonstrates a change in cyanobacterial composition and their diversity during instability and stability periods. MBFG VII, composed by colonial cyanobacteria with mucilage, was associated with reduced values of electrical conductance and alterations in pH. The predominance of filamentous species with heterocyst (MBFG III occurs only during the hydrodynamic stability period and did not show significant association with analyzed parameters. The co-dominance of MBGFs III, V and VII along with high species diversity of

  3. Morphofunctional changes of phytoplankton community during pluvial anomaly in a tropical reservoir.

    Science.gov (United States)

    Câmara, F R A; Rocha, O; Pessoa, E K R; Chellappa, S; Chellappa, N T

    2015-08-01

    The present study focuses on the structure and function of phytoplankton community during periods of marked changes in hydrological traits, influenced by an atypical climatic event (La Niña) and its impact on Armando Ribeiro Gonçalves Reservoir of Rio Grande do Norte, situated in the Caatinga biome of northeastern Brazil. The main questions addressed were: What are the effects of environmental factors on the temporal variation of Morphologically Based Functional Group (MBFG) of phytoplankton community? How does the composition of cyanobacterial species shift in relation to high and low trends of phytoplankton diversity? The samples were collected monthly during 2008-2009 and analyzed for pH, temperature, electrical conductivity, dissolved oxygen content and the nutrients, such as, nitrate-nitrogen, ammoniacal nitrogen, total nitrogen and orthophosphate. Phytoplankton samples were collected for both qualitative and quantitative analyses to evaluate species richness index and species diversity index. The data was divided into two distinct hydrodynamic periods of instability and stability. The results demonstrate considerable changes in dissolved oxygen content, water transparency and nitrogen nutrients, which directly influenced the MBFG of phytoplankton community in space and time. The instability of reservoir water was caused by heavy rainfall, which exerts atypical external disturbances. The seasonal variation of MBFG demonstrates a change in cyanobacterial composition and their diversity during instability and stability periods. MBFG VII, composed by colonial cyanobacteria with mucilage, was associated with reduced values of electrical conductance and alterations in pH. The predominance of filamentous species with heterocyst (MBFG III) occurs only during the hydrodynamic stability period and did not show significant association with analyzed parameters. The co-dominance of MBGFs III, V and VII along with high species diversity of phytoplankton community

  4. Using bio-optical parameters as a tool for detecting changes in the phytoplankton community (SW Portugal)

    Science.gov (United States)

    Goela, Priscila C.; Icely, John; Cristina, Sónia; Danchenko, Sergei; Angel DelValls, T.; Newton, Alice

    2015-12-01

    Upwelling events off the Southwest coast of Portugal can trigger phytoplankton blooms that are important for the fisheries and aquaculture sectors in this region. However, climate change scenarios forecast fluctuations in the intensity and frequency of upwelling events, thereby potentially impacting these sectors. Shifts in the phytoplankton community were analysed from the end of 2008 until the beginning of 2012 by examining the bio-optical properties of the water column, namely the absorption coefficients for phytoplankton, non-algal particles and coloured dissolved organic matter (CDOM). The phytoplankton community was assessed by microscopy, with counts from an inverted microscope, and by chemotaxonomic methodologies, using pigment concentrations determined by High-Performance Liquid Chromatography (HPLC). Results both from microscopy and from chemotaxonomic methods showed a shift from diatom dominance related to bloom conditions matching upwelling events, to small flagellate dominance related to no-bloom conditions matching relaxation of upwelling. During bloom conditions, light absorption from phytoplankton increased markedly, while non-algal particles and CDOM absorption remained relatively constant. The dynamics of CDOM in the study area was attributed to coastal influences rather than from phytoplankton origin. Changes in phytoplankton biomass and consequent alterations in phytoplankton absorption coefficients were attributed to upwelling regimes in the area. Bio-optical parameters can contribute to environmental monitoring of coastal and oceanic waters, which in the case of the European Union, involves the implementation of the Water Framework, Marine Strategy Framework and Marine Spatial Planning Directives.

  5. Changes in phytoplankton communities along nutrient gradients in Lake Taihu: evidence for nutrient reduction strategies

    Science.gov (United States)

    Ai, Ying; Bi, Yonghong; Hu, Zhengyu

    2015-03-01

    An annual investigation on phytoplankton communities was conducted to reveal the effects of nutrients on phytoplankton assemblages in Lake Taihu, East China. A total of 78 phytoplankton taxa were identified. Phytoplankton biomass was higher in the northern part of the lake than in the southern part. Cyanobacteria and Bacillariophyta alternated dominance in the northern area, where algal blooms often appear, and co-dominated in the southern area. In the northern part, the proportions of cyanobacteria and Bacillariophyta varied significantly in total biovolume, both along the phosphorus (P) gradient, and between total nitrogen levels (≤3 mg/L and >3 mg/L TN). The proportions of cyanobacteria and Bacillariophyta had no significant variations in total biovolume along P and N (nitrogen) gradients in the southern part. Correlation analysis and CCA results revealed that P was the key factor regulating phytoplankton community structure. Nitrogen was also important for the phytoplankton distribution pattern. It was concluded that nutrient structure was heterogeneous in space and shaped the distribution pattern of phytoplankton in the lake. Both exogenous P and internally sourced P release needs to be considered. N reduction should be considered simultaneously with P control to efficiently reduce eutrophication and algal blooms.

  6. Changes in Phytoplankton Community Structure in Western South China Sea Over the Past 450 Kyrs

    Science.gov (United States)

    Li, L.; Wang, H.; Li, J.; Zhao, M.; Wang, P.; Zhang, C.

    2008-12-01

    Molecular biomarkers (brassicasterol, dinosterol, alkenones, C30 1,15-diol/keto-ol and cholesterol) were measured in an IMAGES core MD05-2901 (14°22.50'N, 110°44.60'E, w.d. 1454 m), to reconstruct the phytoplankton community structure over the past 450 kyrs in the western South China Sea on the eastern slope off Vietnam. Our results showed that diatoms, which are most sensitive to nutrition supply, exhibited relatively high productivity in interglacial period and lower productivity in glacial period, possibly caused by summer monsoon-induced upwelling. Dinoflagellates exhibited simillar phenomena as diatoms. But, coccolithphorids did not show clear glacial/intergalcial patterns and had a gradual increasing trend from 450 kyrs to 200 kyrs followed by a gradual decreasing trend until the present. Eustigmatophytes exhibited higher contents in glacial than interglacial periods and almost the same variations with terrestrial n- alkanes. Relationships among the major biomarker groups indicated complex responses of different phytoplanktons to changes in paleoclimate and paleoenvironment in the past 450 kyrs in western South China Sea.

  7. North-South asymmetry in the modeled phytoplankton community response to climate change over the 21st century

    Science.gov (United States)

    Marinov, Irina; Doney, Scott C.; Lima, Ivan D.; Lindsay, K.; Moore, J. K.; Mahowald, N.

    2013-12-01

    we analyze the impact of projected climate change on plankton ecology in all major ocean biomes over the 21st century, using a multidecade (1880-2090) experiment conducted with the Community Climate System Model (CCSM-3.1) coupled ocean-atmosphere-land-sea ice model. The climate response differs fundamentally in the Northern and Southern Hemispheres for diatom and small phytoplankton biomass and consequently for total biomass, primary, and export production. Increasing vertical stratification in the Northern Hemisphere oceans decreases the nutrient supply to the ocean surface. Resulting decreases in diatom and small phytoplankton biomass together with a relative shift from diatoms to small phytoplankton in the Northern Hemisphere result in decreases in the total primary and export production and export ratio, and a shift to a more oligotrophic, more efficiently recycled, lower biomass euphotic layer. By contrast, temperature and stratification increases are smaller in the Southern compared to the Northern Hemisphere. Additionally, a southward shift and increase in strength of the Southern Ocean westerlies act against increasing temperature and freshwater fluxes to destratify the water-column. The wind-driven, poleward shift in the Southern Ocean subpolar-subtropical boundary results in a poleward shift and increase in the frontal diatom bloom. This boundary shift, localized increases in iron supply, and the direct impact of warming temperatures on phytoplankton growth result in diatom increases in the Southern Hemisphere. An increase in diatoms and decrease in small phytoplankton partly compensate such that while total production and the efficiency of organic matter export to the deep ocean increase, total Southern Hemisphere biomass does not change substantially. The impact of ecological shifts on the global carbon cycle is complex and varies across ecological biomes, with Northern and Southern Hemisphere effects on the biological production and export partially

  8. Biomarker reconstruction of phytoplankton productivity and community structure changes in the middle Okinawa Trough during the last 15 ka

    Institute of Scientific and Technical Information of China (English)

    XING Lei; ZHAO MeiXun; ZHANG HaiLong; LIU YanGuang; SHI XueFa

    2008-01-01

    Biomarkers have been widely used to reconstruct phytoplankton productivity and community structure changes,and this method has been applied for the first time in the middle Okinawa Trough during the transition from the last deglaciation to the Holocene.The total content of all marine phytoplankton biomarkers,used as a total productivity indicator,reveals higher productivity during the deglaciation.The ratios of the biomarkers are used as community structure indicators which show that,compared with the Holocene,the contribution from haptophytes decreased while the contributions from diatoms and dinoflagellates increased during the deglaciation.The increased productivity during the deglacia-tion was likely caused by the stronger winter monsoon.Also increased nutrient supply from terrestrial sources contributes to the higher productivity due to lower sea-level,which is consistent with higher terrestrial biomarker (long-chain n-alkanols) content.These changes in the nutrient supply also con-tributed to the community structure changes in the Okinawa Trough.

  9. Seasonal changes in temperature and nutrient control of photosynthesis, respiration and growth of natural phytoplankton communities

    DEFF Research Database (Denmark)

    Stæhr, P. A.; Sand-Jensen, K.

    2006-01-01

    1. To investigate the influence of elevated temperatures and nutrients on photosynthesis, respiration and growth of natural phytoplankton assemblages, water was collected from a eutrophic lake in spring, summer, autumn, winter and the following spring and exposed to ambient temperature and ambient...... +2, +4 and +6 °C for 2 weeks with and without addition of extra inorganic nutrients. 2. Rates of photosynthesis, respiration and growth generally increased with temperature, but this effect was strongly enhanced by high nutrient availability, and therefore was most evident for nutrient amended....... 4. Although we found distinct responses to relatively small temperature increases, the interaction between nutrient availability, time of the year and, thus, ambient temperature was responsible for most of the observed variability in phytoplankton growth, photosynthesis and respiration. 5. Although...

  10. Climate change impacts on net primary production (NPP) and export production (EP) regulated by increasing stratification and phytoplankton community structure in the CMIP5 models

    Science.gov (United States)

    Fu, Weiwei; Randerson, James T.; Moore, J. Keith

    2016-09-01

    We examine climate change impacts on net primary production (NPP) and export production (sinking particulate flux; EP) with simulations from nine Earth system models (ESMs) performed in the framework of the fifth phase of the Coupled Model Intercomparison Project (CMIP5). Global NPP and EP are reduced by the end of the century for the intense warming scenario of Representative Concentration Pathway (RCP) 8.5. Relative to the 1990s, NPP in the 2090s is reduced by 2-16 % and EP by 7-18 %. The models with the largest increases in stratification (and largest relative declines in NPP and EP) also show the largest positive biases in stratification for the contemporary period, suggesting overestimation of climate change impacts on NPP and EP. All of the CMIP5 models show an increase in stratification in response to surface-ocean warming and freshening, which is accompanied by decreases in surface nutrients, NPP and EP. There is considerable variability across the models in the magnitudes of NPP, EP, surface nutrient concentrations and their perturbations by climate change. The negative response of NPP and EP to increasing stratification reflects primarily a bottom-up control, as upward nutrient flux declines at the global scale. Models with dynamic phytoplankton community structure show larger declines in EP than in NPP. This pattern is driven by phytoplankton community composition shifts, with reductions in productivity by large phytoplankton as smaller phytoplankton (which export less efficiently) are favored under the increasing nutrient stress. Thus, the projections of the NPP response to climate change are critically dependent on the simulated phytoplankton community structure, the efficiency of the biological pump and the resulting levels of regenerated production, which vary widely across the models. Community structure is represented simply in the CMIP5 models, and should be expanded to better capture the spatial patterns and climate-driven changes in export

  11. Observing and modelling phytoplankton community structure in the North Sea

    Science.gov (United States)

    Ford, David A.; van der Molen, Johan; Hyder, Kieran; Bacon, John; Barciela, Rosa; Creach, Veronique; McEwan, Robert; Ruardij, Piet; Forster, Rodney

    2017-03-01

    Phytoplankton form the base of the marine food chain, and knowledge of phytoplankton community structure is fundamental when assessing marine biodiversity. Policy makers and other users require information on marine biodiversity and other aspects of the marine environment for the North Sea, a highly productive European shelf sea. This information must come from a combination of observations and models, but currently the coastal ocean is greatly under-sampled for phytoplankton data, and outputs of phytoplankton community structure from models are therefore not yet frequently validated. This study presents a novel set of in situ observations of phytoplankton community structure for the North Sea using accessory pigment analysis. The observations allow a good understanding of the patterns of surface phytoplankton biomass and community structure in the North Sea for the observed months of August 2010 and 2011. Two physical-biogeochemical ocean models, the biogeochemical components of which are different variants of the widely used European Regional Seas Ecosystem Model (ERSEM), were then validated against these and other observations. Both models were a good match for sea surface temperature observations, and a reasonable match for remotely sensed ocean colour observations. However, the two models displayed very different phytoplankton community structures, with one better matching the in situ observations than the other. Nonetheless, both models shared some similarities with the observations in terms of spatial features and inter-annual variability. An initial comparison of the formulations and parameterizations of the two models suggests that diversity between the parameter settings of model phytoplankton functional types, along with formulations which promote a greater sensitivity to changes in light and nutrients, is key to capturing the observed phytoplankton community structure. These findings will help inform future model development, which should be coupled

  12. 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.

  13. Upwelling and anthropogenic forcing on phytoplankton productivity and community structure changes in the Zhejiang coastal area over the last 100 years

    Institute of Scientific and Technical Information of China (English)

    DUAN Shanshan; XING Lei; ZHANG Hailong; FENG Xuwen; YANG Haili; ZHAO Meixun

    2014-01-01

    Phytoplankton productivity and community structure in marginal seas have been altered significantly dur-ing the past three decades, but it is still a challenge to distinguish the forcing mechanisms between climate change and anthropogenic activities. High time-resolution biomarker records of two 210Pb-dated sediment cores (#34:28.5°N, 122.272°E;CJ12-1269:28.861 9°N, 122.515 3°E) from the Min-Zhe coastal mud area were compared to reveal changes of phytoplankton productivity and community structure over the past 100 years. Phytoplankton productivity started to increase gradually from the 1970s and increased rapidly after the late 1990s at Site #34;and it started to increase gradually from the middle 1960s and increased rapidly after the late 1980s at Site CJ12-1269. Productivity of Core CJ12-1269 was higher than that of Core #34. Phy-toplankton community structure variations displayed opposite patterns in the two cores. The decreasing D/B (dinosterol/brassicasterol) ratio of Core #34 since the 1960s revealed increased diatom contribution to total productivity. In contrast, the increasing D/B ratio of Core CJ12-1269 since the 1950s indicated in-creased dinoflagellate contribution to total productivity. Both the productivity increase and the increased dinoflagellate contribution in Core CJ12-1269 since the 1950-1960s were mainly caused by anthropogenic activities, as the location was closer to the Changjiang River Estuary with higher nutrient concentration and decreasing Si/N ratios. However, increased diatom contribution in Core #34 is proposed to be caused by increased coastal upwelling, with higher nutrient concentration and higher Si/N ratios.

  14. A glimpse into the future composition of marine phytoplankton communities

    Directory of Open Access Journals (Sweden)

    Esteban eAcevedo-Trejos

    2014-07-01

    Full Text Available It is expected that climate change will have significant impacts on ecosystems. Most model projections agree that the ocean will experience stronger stratification and less nutrient supply from deep waters. These changes will likely affect marine phytoplankton communities and will thus impact on the higher trophic levels of the oceanic food web. The potential consequences of future climate change on marine microbial communities can be investigated and predicted only with the help of mathematical models. Here we present the application of a model that describes aggregate properties of marine phytoplankton communities and captures the effects of a changing environment on their composition and adaptive capacity. Specifically, the model describes the phytoplankton community in terms of total biomass, mean cell size, and functional diversity. The model is applied to two contrasting regions of the Atlantic Ocean (tropical and temperate and is tested under two emission scenarios: SRES A2 or ``business as usual'' and SRES B1 or ``local utopia''. We find that all three macroecological properties will decline during the next century in both regions, although this effect will be more pronounced in the temperate region. Being consistent with previous model predictions, our results show that a simple trait-based modelling framework represents a valuable tool for investigating how phytoplankton communities may reorganize under a changing climate.

  15. Community composition has greater impact on the functioning of marine phytoplankton communities than ocean acidification.

    Science.gov (United States)

    Eggers, Sarah L; Lewandowska, Aleksandra M; Barcelos E Ramos, Joana; Blanco-Ameijeiras, Sonia; Gallo, Francesca; Matthiessen, Birte

    2014-03-01

    Ecosystem functioning is simultaneously affected by changes in community composition and environmental change such as increasing atmospheric carbon dioxide (CO2 ) and subsequent ocean acidification. However, it largely remains uncertain how the effects of these factors compare to each other. Addressing this question, we experimentally tested the hypothesis that initial community composition and elevated CO2 are equally important to the regulation of phytoplankton biomass. We full-factorially exposed three compositionally different marine phytoplankton communities to two different CO2 levels and examined the effects and relative importance (ω(2) ) of the two factors and their interaction on phytoplankton biomass at bloom peak. The results showed that initial community composition had a significantly greater impact than elevated CO2 on phytoplankton biomass, which varied largely among communities. We suggest that the different initial ratios between cyanobacteria, diatoms, and dinoflagellates might be the key for the varying competitive and thus functional outcome among communities. Furthermore, the results showed that depending on initial community composition elevated CO2 selected for larger sized diatoms, which led to increased total phytoplankton biomass. This study highlights the relevance of initial community composition, which strongly drives the functional outcome, when assessing impacts of climate change on ecosystem functioning. In particular, the increase in phytoplankton biomass driven by the gain of larger sized diatoms in response to elevated CO2 potentially has strong implications for nutrient cycling and carbon export in future oceans.

  16. 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.

  17. [The phytoplankton community of Punta Morales, Nicoya Gulf, Costa Rica ].

    Science.gov (United States)

    Brugnoli Olivera, E; Morales Ramirez, A

    2001-12-01

    Three daily samplings of the phytoplankton community were made at two consecutive days in March, April, May, September, October, November and December 1997, at Punta Morales, Golfo de Nicoya, Costa Rica. Samples were collected during each tide at depths of 50% and 10% of light penetration using a Niskin bottle. A total of 43 taxa were identified. Centric diatoms, pennates and flagellates represented 90% of total phytoplankton abundance. In the phytoplankton fraction (cells > 30 microm), diatoms were the most abundant group, and Skeletonema costatum (32%) dominated. In nannophytoplankton (cells < 30 microm), Chaetoceros (23.7%) was the most abundant taxon, followed by flagellates (23%) and Cylindrotheca closterium (13.1%). These results agree with previous surveys and suggest that a typical net phytoplankton community persist through time in the Punta Morales zone. The number of nannophytoplankton fraction cells varied seasonally and suggests quantitative changes in species abundance, with possible modifications of cellular size or chain length in filamentous species. The codominance between S. costatum and Chaetoceros spp. during the rainy season suggested the ocurrence of an early ecological sucession, and nutrients could be the factor generating such population changes.

  18. Phytoplankton Diversity Effects on Community Biomass and Stability along Nutrient Gradients in a Eutrophic Lake

    Science.gov (United States)

    Tian, Wang; Zhang, Huayong; Zhao, Lei; Zhang, Feifan; Huang, Hai

    2017-01-01

    The relationship between biodiversity and ecosystem functioning is a central issue in ecology, but how this relationship is affected by nutrient stress is still unknown. In this study, we analyzed the phytoplankton diversity effects on community biomass and stability along nutrient gradients in an artificial eutrophic lake. Four nutrient gradients, varying from slightly eutrophic to highly eutrophic states, were designed by adjusting the amount of polluted water that flowed into the lake. Mean phytoplankton biomass, species richness, and Shannon diversity index all showed significant differences among the four nutrient gradients. Phytoplankton community biomass was correlated with diversity (both species richness and Shannon diversity index), varying from positive to negative along the nutrient gradients. The influence of phytoplankton species richness on resource use efficiency (RUE) also changed from positive to negative along the nutrient gradients. However, the influence of phytoplankton Shannon diversity on RUE was not significant. Both phytoplankton species richness and Shannon diversity had a negative influence on community turnover (measured as community dissimilarity), i.e., a positive diversity–stability relationship. Furthermore, phytoplankton spatial stability decreased along the nutrient gradients in the lake. With increasing nutrient concentrations, the variability (standard deviation) of phytoplankton community biomass increased more rapidly than the average total biomass. Results in this study will be helpful in understanding the phytoplankton diversity effects on ecosystem functioning and how these effects are influenced by nutrient conditions in aquatic ecosystems. PMID:28117684

  19. Scenarios of nutrient alterations and responses of phytoplankton in a changing Daya Bay, South China Sea

    Science.gov (United States)

    Wu, Mei-Lin; Wang, You-Shao; Wang, Yu-Tu; Yin, Jian-Ping; Dong, Jun-De; Jiang, Zhao-Yu; Sun, Fu-Lin

    2017-01-01

    The coastal ecosystem in the Daya Bay is sensitive to the environmental changes induced by highly intensive human activities. We obtained and compiled the recent 30 years' field observational data on nutrients and phytoplankton communities to explore the changing ecosystem. Dissolved inorganic nitrogen concentration (DIN) has significantly increased, while phosphate concentration (DIP) dramatically decreased because of costal anthropogenic influence. The limited factors for phytoplankton have changed from nitrogen in the 1980s to phosphate in the mid-1990s. The net-collected phytoplankton communities has the miniaturized trend, while there is drastic increase of Chlorophyll a (Chl-a) concentration. Even though the diatoms still dominate in phytoplankton community, the dominant species have slightly changed. The alga bloom greatly changed from diatoms dominated to dinoflagellates due to changes of nutrient structure. All these changes on nutrients and phytoplankton communities appear to be closely associated with human activities along the coast of the Daya Bay.

  20. Marine phytoplankton and the changing ocean iron cycle

    Science.gov (United States)

    Hutchins, D. A.; Boyd, P. W.

    2016-12-01

    The availability of the micronutrient iron governs phytoplankton growth across much of the ocean, but the global iron cycle is changing rapidly due to accelerating acidification, stratification, warming and deoxygenation. These mechanisms of global change will cumulatively affect the aqueous chemistry, sources and sinks, recycling, particle dynamics and bioavailability of iron. Biological iron demand will vary as acclimation to environmental change modifies cellular requirements for photosynthesis and nitrogen acquisition and as adaptive evolution or community shifts occur. Warming, acidification and nutrient co-limitation interactions with iron biogeochemistry will all strongly influence phytoplankton dynamics. Predicting the shape of the future iron cycle will require understanding the responses of each component of the unique biogeochemistry of this trace element to many concurrent and interacting environmental changes.

  1. Present status and changes of the phytoplankton community after invasion of Neosalanx taihuensis since 1982 in a deep oligotrophic plateau lake, Lake Fuxian in the subtropical China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xia; XIE Ping; CHEN Fei-zhou; LI Yan-ling; LI Si-xin; GUO Ni-chun; QIN Jian-hui

    2005-01-01

    Phytoplankton assemblages in the subtrophical oligotrophic Lake Fuxian, the second deepest lake in China, were investigated monthly from September 2002 to August 2003. A total of 113 species belonging to seven phyla were identified, among them, a filamentous green alga, Mougeotia sp., dominated almost throughout the study period and comprised most of the total phytoplankton biomass.Mougeotia sp. has made a substantial development during the past decades: it was absent in 1957, only occasionally present in 1983,increased substantially in 1993, and became predominant in 2002-2003. It is likely that natural invasion of the Taihu Lake noodlefish (Neosalanx taihuensis) has led to a change of dominant herbivorous zooplankton from small to large calanoid, which has increased grazing pressure on small edible algae, and thus has indirectly favored the development of the inedible filamentous Mougeotia sp.

  2. Strong responses of Southern Ocean phytoplankton communities to volcanic ash

    OpenAIRE

    Browning, T.J.; Bouman, H. A.; Henderson, G. M.; Mather, T.A.; D. M. Pyle; Schlosser, Christian; Woodward, E.M.S.; Moore, C. M.

    2014-01-01

    Volcanic eruptions have been hypothesized as an iron supply mechanism for phytoplankton blooms; however, little direct evidence of stimulatory responses has been obtained in the field. Here we present the results of twenty-one 1-2day bottle enrichment experiments from cruises in the South Atlantic and Southern Ocean which conclusively demonstrated a photophysiological and biomass stimulation of phytoplankton communities following supply of basaltic or rhyolitic volcanic ash. Furthermore, expe...

  3. First steps of ecological restoration in Mediterranean lagoons: Shifts in phytoplankton communities

    Science.gov (United States)

    Leruste, A.; Malet, N.; Munaron, D.; Derolez, V.; Hatey, E.; Collos, Y.; De Wit, R.; Bec, B.

    2016-10-01

    Along the French Mediterranean coast, a complex of eight lagoons underwent intensive eutrophication over four decades, mainly related to nutrient over-enrichment from continuous sewage discharges. The lagoon complex displayed a wide trophic gradient from mesotrophy to hypertrophy and primary production was dominated by phytoplankton communities. In 2005, the implementation of an 11 km offshore outfall system diverted the treated sewage effluents leading to a drastic reduction of anthropogenic inputs of nitrogen and phosphorus into the lagoons. Time series data have been examined from 2000 to 2013 for physical, chemical and biological (phytoplankton) variables of the water column during the summer period. Since 2006, total nitrogen and phosphorus concentrations as well as chlorophyll biomass strongly decreased revealing an improvement in lagoon water quality. In summertime, the decline in phytoplankton biomass was accompanied by shifts in community structure and composition that could be explained by adopting a functional approach by considering the common functional traits of the main algal groups. These phytoplankton communities were dominated by functional groups of small-sized and fast-growing algae (diatoms, cryptophytes and green algae). The trajectories of summer phytoplankton communities displayed a complex response to changing nutrient loads over time. While diatoms were the major group in 2006 in all the lagoons, the summer phytoplankton composition in hypertrophic lagoons has shifted towards green algae, which are particularly well adapted to summertime conditions. All lagoons showed increasing proportion and occurrence of peridinin-rich dinophytes over time, probably related to their capacity for mixotrophy. The diversity patterns were marked by a strong variability in eutrophic and hypertrophic lagoons whereas phytoplankton community structure reached the highest diversity and stability in mesotrophic lagoons. We observe that during the re

  4. Nutrient limitation in Northern Gulf of Mexico (NGOM: phytoplankton communities and photosynthesis respond to nutrient pulse.

    Directory of Open Access Journals (Sweden)

    Yan Zhao

    Full Text Available Although the Mississippi-Atchafalaya River system exports large amounts of nutrients to the Northern Gulf of Mexico annually, nutrient limitation of primary productivity still occurs offshore, acting as one of the major factors controlling local phytoplankton biomass and community structure. Bioassays were conducted for 48 hrs at two stations adjacent to the river plumes in April and August 2012. High Performance of Liquid Chromatography (HPLC combined with ChemTax and a Fluorescence Induction and Relaxation (FIRe system were combined to observe changes in the phytoplankton community structure and photosynthetic activity. Major fluorescence parameters (Fo, Fv/Fm performed well to reveal the stimulating effect of the treatments with nitrogen (N-nitrate and with nitrogen plus phosphate (+NPi. HPLC/ChemTax results showed that phytoplankton community structure shifted with nitrate addition: we observed an increase in the proportion of diatoms and prasinophytes and a decrease in cyanobacteria and prymnesiophytes. These findings are consistent with predictions from trait-based analysis which predict that phytoplankton groups with high maximum growth rates (μmax and high nutrient uptake rates (Vmax readily take advantage of the addition of limiting nutrients. Changes in phytoplankton community structure, if persistent, could trigger changes of particular organic matter fluxes and alter the micro-food web cycles and bottom oxygen consumption.

  5. 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.

  6. Fluctuations of Phytoplankton Community in the Coastal Waters of Caspian Sea in 2006

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    Siamak Bagheri

    2011-01-01

    Full Text Available Problem statement: The Caspian Sea ecosystem has been suffered with many problems since 1980s. Aanthropogenic pollution from heavy metals, hydrocarbons, pesticides, changes in the quantity of nutrient inputs by rivers, are significant threats to biodiversity and biological resources such as plankton structure in the Caspian Sea. According to the significant of phytoplankton community in marine system. The state of the fluctuations of phytoplankton communities of the southwestern Caspian Sea was investigated and compared with the findings of before 2006. Approach: Phytoplankton abundance and species composition of the Caspian Sea were evaluated by using samples collected at 12 stations along three transects. Samplings were conducted seasonal in 2006 at 5, 10, 20 and 50 m depth were fixed for each transect in the southwestern Caspian Sea. Results: A total of 39 species phytoplankton species were distinguished during 2006, the annual phytoplankton abundance were calculated as 57, 300±15,550 cells.l-1, which ranged from 89, 250±35, 062 cells.l-1 in September to 16, 200±6,664 cells.l-1 in February. The diatoms formed more than half of the total abundance (61% while cyanophytes were the second important group in view of contribution to total phytoplankton (26% in 2006. The study showed that diatoms Thalassionema nitzschioides, Cyclotella meneghiniana and cyanophyte Osillatoria sp. numerically dominated in this area. Conclusion: The study revealed that diatoms were higher than other groups of phytoplankton in 2006. The hydrology variation, increased fresh water inflow via rivers and a rise in nutrients concentrations have played important roles in blooming of phytoplankton species, e.g., the diatoms in this study, which is also known from other marines. Similar studies on determination of the effects of environmental degradation on phytoplankton and hydrological processes should be taken into account in near future.

  7. Simulated terrestrial runoff triggered a phytoplankton succession and changed seston stoichiometry in coastal lagoon mesocosms.

    Science.gov (United States)

    Deininger, A; Faithfull, C L; Lange, K; Bayer, T; Vidussi, F; Liess, A

    2016-08-01

    Climate change scenarios predict intensified terrestrial storm runoff, providing coastal ecosystems with large nutrient pulses and increased turbidity, with unknown consequences for the phytoplankton community. We conducted a 12-day mesocosm experiment in the Mediterranean Thau Lagoon (France), adding soil (simulated runoff) and fish (different food webs) in a 2 × 2 full factorial design and monitored phytoplankton composition, shade adaptation and stoichiometry. Diatoms (Chaetoceros) increased four-fold immediately after soil addition, prymnesiophytes and dinoflagellates peaked after six- and 12 days, respectively. Soil induced no phytoplankton shade adaptation. Fish reduced the positive soil effect on dinoflagellates (Scripsiella, Glenodinium), and diatom abundance in general. Phytoplankton community composition drove seston stoichiometry. In conclusion, pulsed terrestrial runoff can cause rapid, low quality (high carbon: nutrient) diatom blooms. However, bloom duration may be short and reduced in magnitude by fish. Thus, climate change may shift shallow coastal ecosystems towards famine or feast dynamics.

  8. Relationship between N : P : Si ratio and phytoplankton community composition in a tropical estuarine mangrove ecosystem

    Directory of Open Access Journals (Sweden)

    A. K. Choudhury

    2015-02-01

    Full Text Available The present work aims at understanding the importance of Brzezinski–Redfield ratio (modified Redfield ratio as a determinant of natural phytoplankton community composition in a mangrove ecosystem. Even though this ecoregion has been reported to be mostly eutrophic, localised and anthropogenic influences often result in habitat variability especially with regard to nutrient concentrations at different parts of this ecosystem. Phytoplankton, an important sentinel in aquatic ecosystems may respond differently to such alterations in habitat thereby bringing about significant changes in the community composition. Results show that even though habitat variability does exist at our study area and varied on a spatial and temporal scale, the nutrient concentrations were intricately balanced that never became limited and complemented well with the concept of modified Redfield ratio. However, an integrative approach to study phytoplankton community involving microscopy and rbcL clone library and sequencing approach revealed that it was the functional traits of individual phytoplankton taxa that determined the phytoplankton community composition rather than the nutrient concentrations of the study area. Hence we conclude that the recent concept of functional traits and elemental stoichiometry does not remain restricted to controlled environment of experimental studies only but occur in natural mangrove habitat.

  9. Relationship between N : P : Si ratio and phytoplankton community composition in a tropical estuarine mangrove ecosystem

    Science.gov (United States)

    Choudhury, A. K.; Bhadury, P.

    2015-02-01

    The present work aims at understanding the importance of Brzezinski-Redfield ratio (modified Redfield ratio) as a determinant of natural phytoplankton community composition in a mangrove ecosystem. Even though this ecoregion has been reported to be mostly eutrophic, localised and anthropogenic influences often result in habitat variability especially with regard to nutrient concentrations at different parts of this ecosystem. Phytoplankton, an important sentinel in aquatic ecosystems may respond differently to such alterations in habitat thereby bringing about significant changes in the community composition. Results show that even though habitat variability does exist at our study area and varied on a spatial and temporal scale, the nutrient concentrations were intricately balanced that never became limited and complemented well with the concept of modified Redfield ratio. However, an integrative approach to study phytoplankton community involving microscopy and rbcL clone library and sequencing approach revealed that it was the functional traits of individual phytoplankton taxa that determined the phytoplankton community composition rather than the nutrient concentrations of the study area. Hence we conclude that the recent concept of functional traits and elemental stoichiometry does not remain restricted to controlled environment of experimental studies only but occur in natural mangrove habitat.

  10. Structure of the Phytoplankton Community and Its Relationship to Water Quality in Donghu Lake, Wuhan, China

    Institute of Scientific and Technical Information of China (English)

    An-Ping LEI; Zhang-Li HU; Jian WANG; Zhi-Xin SHI; Fung-Yee Nora TAM

    2005-01-01

    The phytoplankton community structure, in terms of species composition, total standing crop,and abundance of the dominant algal species, at four stations in Donghu Lake, Wuhan, China, was investigated monthly from January 1994 to December 1996. A total of 260 taxa was observed, of which Chlorophyta (106 taxa) contributed the highest portion of the total number of taxa, followed by Bacillariophyta (82 taxa)and Cyanophyta (32 taxa). The total standing crop measured by means of chlorophyll a content, cell density,and cell biovolume, as well as the abundance of the dominant species, declined in the order of Station I to Station Ⅳ. Seasonal changes of the standing crop varied greatly among the four stations. Although the cell density at the four stations showed a single peak within a year, the peak density varied from July to November, dependent on the sampling year and the station. For chlorophyll a content and cell biovolume,multiple peaks were observed at Stations Ⅰ and Ⅱ, but a single peak was found at Stations Ⅲ and Ⅳ. The phytoplankton community structure indicated that the trophic status was the highest at Station Ⅰ (most eutrophic), followed by Station Ⅱ; Stations Ⅲ and Ⅳ were the least trophic areas. The long-term changes in phytoplankton community structure further suggested that changes in phytoplankton community structure were correlated with water quality, and eutrophication of Donghu Lake had been aggravated since the 1950s.

  11. Physicochemical conditions in affecting the distribution of spring phytoplankton community

    Science.gov (United States)

    Wei, Yuqiu; Liu, Haijiao; Zhang, Xiaodong; Xue, Bing; Munir, Sonia; Sun, Jun

    2017-03-01

    To better understand the physicochemical conditions in affecting regional distribution of phytoplankton community, one research cruise was carried out in the Bohai Sea and Yellow Sea during 3rd and 23th May, 2010. The phytoplankton community, including Bacillariophyta (105 taxa), Pyrrophyta (54 taxa), Chrysophyta (1 taxon) and Chlorophyta (2 taxa), had been identified and clearly described from six ecological provinces. And, the six ecological provinces were partitioned based on the top twenty dominant species related with notable physicochemical parameters. In general, the regional distributions of phytoplankton ecological provinces were predominantly influenced by the physicochemical properties induced by the variable water masses and circulations. The predominant diatoms in most of water samples showed well adaptability in turbulent and eutrophic conditions. However, several species of dinoflagellates e.g., Protoperidinium conicum, Protoperidinium triestinum, Protoperidinium sp. and Gymnodinium lohmanni preferred warmer, saltier and nutrient-poor environment. Moreover, the dinoflagellates with high frequency in the Yellow Sea might be transported from the Yellow Sea Warm Current. The horizontal distribution of phytoplankton was depicted by diatoms and controlled by phosphate concentration, while the vertical distribution was mainly supported by light and nutrients availability in the subsurface and bottom layers, respectively.

  12. Phytoplankton community structure in the VAHINE mesocosm experiment

    Science.gov (United States)

    Leblanc, Karine; Cornet, Véronique; Caffin, Mathieu; Rodier, Martine; Desnues, Anne; Berthelot, Hugo; Turk-Kubo, Kendra; Heliou, Jules

    2016-09-01

    The VAHINE mesocosm experiment was designed to trigger a diazotroph bloom and to follow the subsequent transfer of diazotroph-derived nitrogen (DDN) in the rest of the food web. Three mesocosms (50 m3) located inside the Nouméa lagoon (New Caledonia, southwestern Pacific) were enriched with dissolved inorganic phosphorus (DIP) in order to promote N2 fixation in these low-nutrient, low-chlorophyll (LNLC) waters. Initially, the diazotrophic community was dominated by diatom diazotroph associations (DDAs), mainly by Rhizosolenia/Richelia intracellularis, and by Trichodesmium, which fueled enough DDN to sustain the growth of other diverse diatom species and Synechococcus populations that were well adapted to limiting DIP levels. After DIP fertilization (1 µM) on day 4, an initial lag time of 10 days was necessary for the mesocosm ecosystems to start building up biomass. However, changes in community structure were already observed during this first period, with a significant drop of both Synechococcus and diatom populations, while Prochlorococcus benefited from DIP addition. At the end of this first period, corresponding to when most added DIP was consumed, the diazotroph community changed drastically and became dominated by Cyanothece-like (UCYN-C) populations, which were accompanied by a monospecific bloom of the diatom Cylindrotheca closterium. During the second period, biomass increased sharply together with primary production and N2-fixation fluxes near tripled. Diatom populations, as well as Synechococcus and nanophytoeukaryotes, showed a re-increase towards the end of the experiment, showing efficient transfer of DDN to non-diazotrophic phytoplankton.

  13. Size-dependent photoacclimation of the phytoplankton community in temperate shelf waters (southern Bay of Biscay)

    KAUST Repository

    Álvarez, E

    2015-12-09

    © Inter-Research 2016. Shelf waters of the Cantabrian Sea (southern Bay of Biscay) are productive ecosystems with a marked seasonality. We present the results from 1 yr of monthly monitoring of the phytoplankton community together with an intensive sampling carried out in 2 contrasting scenarios during the summer and autumn in a mid-shelf area. Stratification was apparent on the shelf in summer, while the water column was comparatively well mixed in autumn. The size structure of the photoautotrophic community, from pico-to micro-phytoplankton, was tightly coupled with the meteo-climatic and hydrographical conditions. Over the short term, variations in the size structure and chlorophyll content of phytoplankton cells were related to changes in the physico-chemical environment, through changes in the availability of nutrients and light. Uncoupling between the dynamics of carbon biomass and chlorophyll resulted in chlorophyll to carbon ratios dependent on body size. The slope of the size dependence of chlorophyll content increased with increasing irradiance, reflecting different photoacclimation plasticity from pico-to micro-phytoplankton. The results have important implications for the productivity and the fate of biogenic carbon in this region, since the size dependence of photosynthetic rates is directly related to the size scaling of chlorophyll content.

  14. Initial size structure of natural phytoplankton communities determines the response to Daphnia diel vertical migration

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    Maarten Boersma

    2012-01-01

    Full Text Available Diel vertical migration (DVM is a common behavior of many pelagic herbivorous zooplankton species in response to predation pressure. It is characterized by a twice daily habitat shift of the zooplankton species: staying in the epilimnion only during night time and migrating down in the crack of dawn in deeper water layers, staying there during the day time. This causes a discontinuous grazing regime and previous studies have shown that the direction and strength of phytoplankton community responses to zooplankton DVM most probably depends on the size of phytoplankton species. To examine the influence of zooplankton DVM on different sized phytoplankton communities, we designed an experiment where we manipulated the size distribution of a natural phytoplankton community a priori in field mesocosms. We investigated the influence of DVM of the cladoceran Daphnia hyalina on two different phytoplankton communities, by the use of deep (10 m field enclosures. Epilimnetic lake water, containing a summer phytoplankton community, was filtered with two different mesh sizes (11 mm and 64 mm. The 11 mm phytoplankton community (“small” contained mainly small algal species, while the 64 mm community (“large” had a wider range of phytoplankton sizes. To simulate zooplankton DVM, D. hyalina were placed in mesh cages that were lowered or raised (“migration” as dictated by the study design; a “no migration” (representing absence of DVM treatment was also tested. Phytoplankton abundance was measured using chlorophyll-a and biovolume; size distribution of the algae and nutrient availability was also determined in each treatment. The results indicated that DVM had contrasting effects on the two evaluated phytoplankton communities. Comparison of “migration” and “no migration” zooplankton treatments showed that nutrient availability and total phytoplankton biovolume was higher in (1 “no migration” treatments with phytoplankton communities

  15. Species- and community-level responses combine to drive phenology of lake phytoplankton

    Science.gov (United States)

    Walters, Annika; Sagrario, María de los Ángeles González; Schindler, Daniel E.

    2013-01-01

    Global change is leading to shifts in the seasonal timing of growth and maturation for primary producers. Remote sensing is increasingly used to measure the timing of primary production in both aquatic and terrestrial ecosystems, but there is often a poor correlation between these results and direct observations of life-history responses of individual species. One explanation may be that in addition to phenological shifts, global change is also causing shifts in community composition among species with different seasonal timing of growth and maturation. We quantified how shifts in species phenology and in community composition translated into phenological change in a diverse phytoplankton community from 1962-2000. During this time the aggregate community spring-summer phytoplankton peak has shifted 63 days earlier. The mean taxon shift was only 3 days earlier and shifts in taxa phenology explained only 40% of the observed community phenological shift. The remaining community shift was attributed to dominant early season taxa increasing in abundance while a dominant late season taxon decreased in abundance. In diverse producer communities experiencing multiple stressors, changes in species composition must be considered to fully understand and predict shifts in the seasonal timing of primary production.

  16. Biodiversity increases the productivity and stability of phytoplankton communities.

    Directory of Open Access Journals (Sweden)

    Alina A Corcoran

    Full Text Available Global biodiversity losses provide an immediate impetus to elucidate the relationships between biodiversity, productivity and stability. In this study, we quantified the effects of species richness and species combination on the productivity and stability of phytoplankton communities subject to predation by a single rotifer species. We also tested one mechanism of the insurance hypothesis: whether large, slow-growing, potentially-defended cells would compensate for the loss of small, fast-growing, poorly-defended cells after predation. There were significant effects of species richness and species combination on the productivity, relative yield, and stability of phytoplankton cultures, but the relative importance of species richness and combination varied with the response variables. Species combination drove patterns of productivity, whereas species richness was more important for stability. Polycultures containing the most productive single species, Dunaliella, were consistently the most productive. Yet, the most species rich cultures were the most stable, having low temporal variability in measures of biomass. Polycultures recovered from short-term negative grazing effects, but this recovery was not due to the compensation of large, slow-growing cells for the loss of small, fast-growing cells. Instead, polyculture recovery was the result of reduced rotifer grazing rates and persisting small species within the polycultures. Therefore, although an insurance effect in polycultures was found, this effect was indirect and unrelated to grazing tolerance. We hypothesize that diverse phytoplankton assemblages interfered with efficient rotifer grazing and that this "interference effect" facilitated the recovery of the most productive species, Dunaliella. In summary, we demonstrate that both species composition and species richness are important in driving patterns of productivity and stability, respectively, and that stability in biodiverse

  17. Effects of ocean acidification on primary production in a coastal North Sea phytoplankton community

    Science.gov (United States)

    Eberlein, Tim; Wohlrab, Sylke; Rost, Björn; John, Uwe; Bach, Lennart T.; Riebesell, Ulf; Van de Waal, Dedmer B.

    2017-01-01

    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. PMID:28273107

  18. Phytoplankton community structure in the Lena Delta (Siberia, Russia) in relation to hydrography

    Science.gov (United States)

    Kraberg, A. C.; Druzhkova, E.; Heim, B.; Loeder, M. J. G.; Wiltshire, K. H.

    2013-02-01

    The Lena Delta in Northern Siberia is one of the largest river deltas in the world. During peak discharge, after the ice melt in spring, it delivers between 60-8000 m3s-1 of water and sediment into the Arctic Ocean. The Lena Delta and the Laptev Sea coast also constitute a~continuous permafrost region. Ongoing climate change, which is particularly pronounced in the Arctic, is leading to increased rates of permafrost thaw. This is likely to profoundly change the discharge rates of the Lena River and the chemistry of the river waters which are discharged into the coastal Laptev Sea, e.g. by increasing concentrations of inorganic nutrients, DOC and importantly methane. These physical and chemical changes will also affect the composition of and interactions between phytoplankton and zooplankton communities, forming the basis of the food web. However, before potential consequences of climate change for coastal arctic plankton communities can be judged, the inherent status of the diversity and linked foodweb interactions within the delta need to be established. As part of the AWI Lena Delta Programme in 2010 the phyto- and microzooplankton community in three river channels as well as four coastal transects were investigated to capture the typical river phytoplankton communities and the transitional zone of brackish/marine conditions. Most CTD profiles from 23 coastal stations showed very strong stratification. The only exception to this was a small a shallow and mixed area running from the outflow of Bykovskaya channel in a northerly direction parallel to the shore (transect 3). Of the five stations in this area three had a salinity of close to zero. Two further stations had salinities of around 2 and 5 throughout the water column. In the remaining transects on the other hand salinities varied between 5-30 with depth. Phytoplankton counts from the outflow from the Lena were dominated by diatoms (Aulacoseira species) cyanobacteria (Aphanizomenon, Pseudanabaena) and

  19. Preliminary study on seasonal succession and development pathway of phytoplankton community in the Bohai Sea

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Phytoplankton species composition and species succession were determined in 1998~1999 based on 2 nestle investigation cruises in the Bohai Sea and two monthly monitoring stations at Penglai and Changdao for 15 months. The seasonal succession and pathway of phytoplankton community in the Bohai Sea were discussed complementarily with history data. The main process of phytoplankton community development in the Bohai Sea was controlled by temperature and nutrient replenishes. There were two cell abundance peaks in an annual variation, the main peak in April and the secondary peak in September. In winter, the cell abundance was low due to the low temperature, the phytoplankton community was mainly made up of small-crled diatoms. In spring, the phytoplankton community was developed very quickly by small-celled diatom in suitable conditions of temperature and nutrients. In summer, the cell abundance decreased and big-celled diatoms became predominated. In autumn, because of the replenish of nutrient, big-celled diatoms and dinoflagellates formed another cell abundance peak.During the annual variation of phytoplankton community in the Bohai Sea, species succession was the main process of community development, the species sequence just occur at special areas and special periods. The evolution of phytoplankton community in the Bohai Sea accords with the hypothesis of Margalef's phytoplankton community of four stages. But the size feature is contrary to the hypothesis,which may be caused by nutrient replenish in autumn in Bohai Sea and the top to down control.

  20. Rapid eco-evolutionary responses in perturbed phytoplankton communities.

    Science.gov (United States)

    Thibodeau, Geneviève; Walsh, David A; Beisner, Beatrix E

    2015-09-07

    Biodiversity currently faces unprecedented threats owing to species extinctions. Ecologically, compensatory dynamics can ensure stable community biomass following perturbation. However, whether there is a contribution of genetic diversity to community responses is an outstanding question. To date, the contribution of evolutionary processes through genotype shifts has not been assessed in naturally co-occurring multi-species communities in the field. We examined the mechanisms contributing to the response of a lake phytoplankton community exposed to either a press or pulse acidification perturbation in lake mesocosms. To assess community shifts in the ecological response of morphospecies, we identified taxa microscopically. We also assessed genotype shifts by sequencing the ITS2 region of ribosomal DNA. We observed ecological and genetic contributions to community responses. The ecological response was attributed to compensatory morphospecies dynamics and occurred primarily in the Pulse perturbation treatment. In the Press treatments, in addition to compensatory dynamics, we observed evidence for genotype selection in two species of chlorophytes, Desmodesmus cuneatus and an unidentified Chlamydomonas. Our study demonstrates that while genotype selection may be rare, it is detectable and occurs especially when new environmental conditions are maintained for long enough to force selection processes on standing variation.

  1. Effects of mixing-induced irradiance fluctuations on nitrogen uptake in size-fractionated coastal phytoplankton communities

    Science.gov (United States)

    Maguer, Jean-François; L'Helguen, Stéphane; Waeles, Matthieu

    2015-03-01

    In coastal waters subjected to strong tidal forcing, phytoplankton populations are exposed to highly variable light regimes. To grow under such fluctuating light environments, phytoplankton adjust their physiological properties. Here, we investigated nitrogen (N) uptake patterns in the western English Channel to determine whether phytoplankton modify their physiological processes involved in N uptake in response to changing irradiance conditions induced by spring-neap tidal cycles. Nitrate (NO3-) and ammonium (NH4+) uptake kinetics as a function of irradiance (VN-E curves) were assessed using 15N tracer techniques on two size fractions (10 μm) of phytoplankton collected at 50% and 1% of surface irradiance during two spring-neap tidal cycles. Overall, the results showed that both small and large phytoplankton, whatever their vertical position in the water column, increased their maximum uptake capacity and their light utilization efficiency for the two N substrates following the decrease in vertical mixing intensity. Moreover, the improvement of irradiance conditions at neap tides was of greater benefit for the larger cells than for the smaller ones and was more favorable for NO3- uptake than for NH4+ uptake. These findings show that the light regime fluctuation resulting from the relaxation of tidal mixing during spring-neap tidal cycle leads to profound physiological adjustments of N uptake processes in phytoplankton communities. They suggest that the changes in NO3- uptake by large phytoplankton associated with the fortnightly spring-neap tidal cycle can account for most of the deviation in background productivity in the western English Channel which is based on NH4+ and is dominated by small cells. The dynamic light regime inherent to macrotidal coastal ecosystems could therefore determine, to a large extent, the importance of new vs. regenerated production as well as the size structure of the phytoplankton community.

  2. Phytoplankton niches, traits and eco-evolutionary responses to global environmental change

    DEFF Research Database (Denmark)

    Litchman, Elena; Edwards, Kyle F.; Klausmeier, Christopher A.;

    2012-01-01

    Phytoplankton are major primary producers in aquatic ecosystems and are sensitive to various aspects of global environmental change. They can respond through phenotypic plasticity, species sorting, genetic adaptation, or a combination of these processes. Here we present conceptual, experimental a...... be investigated simultaneously. Novel models of trait evolution in a community context should provide additional insights into potential adaptation trajectories under diverse global change scenarios...

  3. Phytoplankton community and limnology of Chatla floodplain wetland of Barak valley, Assam, North-East India

    Directory of Open Access Journals (Sweden)

    Sultana Laskar H.

    2013-09-01

    Full Text Available Phytoplankton diversity was investigated over a period of two years (2006 to 2008 in Chatla floodplain wetland in Barak valley, Assam, North-East India. Site 1 and site 2 are two inlets and site 3 is a lentic system associated with vegetation cover of Calamus tenuis and Baringtonia acutangula. The floodplain has a unique hydrology because of the presence of different types of habitats (inlets, fisheries, beels and outlets which maintains a network among the floodplains, rivers and streams. Phytoplankton community composition, density and diversity were studied in relation to environmental variables. All the variables were estimated by following standard methods. Phytoplankton was collected by plankton net and quantitative estimation was made by using Sedgwick Rafter counting cell. Phytoplankton community comprised 53 taxa represented by Chlorophyceae (31, Cyanophyceae (11, Bacillariophyceae (7, Euglenophyceae (1 and Dinophyceae (3. Phytoplankton taxa was dominated by Volvox sp., Nostoc sp., Eunotia sp., Navicula sp., Euglena spp. and density was found highest in site 3 and lowest in site 1. Shannon diversity index (H′ for phytoplankton community varied between 2.4 to 2.65 indicating fairly high species diversity. The varying magnitude of correlationship among environmental variables and phytoplankton species density as shown by Canonical correspondence analysis (CCA indicated that some of the environmental variables (water temperature, transparency, rainfall, nitrate and ammonia are the driving factors for governing the phytoplankton species assemblages in Chatla floodplain wetland. Fluctuation of phytoplankton density and community composition in different habitats indicated various niche apportionment as well as anthropogenic influences.

  4. Responses of phytoplankton community to the input of different aerosols in the East China Sea

    Science.gov (United States)

    Meng, X.; Chen, Y.; Wang, B.; Ma, Q. W.; Wang, F. J.

    2016-07-01

    Atmospheric deposition can affect marine phytoplankton by supplying macronutrients and trace elements. We conducted mesocosm experiments by adding aerosols with different composition (dominated by mineral dust, biomass burning and high Cu, and secondary aerosol, respectively) to the surface seawater of the East China Sea. Chlorophyll a concentrations were found to be the highest and lowest after adding aerosols containing the highest Fe and dissolved inorganic nitrogen (DIN), respectively. The relative abundance of Haptophyceae increased significantly after adding mineral dust, whereas diatom, Dinophyceae and Cryptophyceae reached the maximum accompanied with the highest DIN. Our results suggest that Fe may be more important than DIN in promoting primary productivity in the sampled seawater. The input of mineral dust and anthropogenic aerosols may result in distinct changes of phytoplankton community structure.

  5. Structure of the phytoplankton community in the Cachoeira Dourada reservoir (GO/MG), Brazil.

    Science.gov (United States)

    Teixeira de Oliveira, M; Rocha, O; Peret, A C

    2011-08-01

    The limnological features and the phytoplankton community of the Cachoeira Dourada reservoir were analyzed in December 2006, May 2007 and November 2007. Temporal changes in the taxonomic composition, density, diversity and dominance of species were analyzed in relation to climatic factors and the physical and chemical characteristics of the water. A positive correlation was found between some of the physical and chemical variables and the phytoplankton community. According to the CCA, variables such as the extent of the euphotic zone, temperature, pH, nitrogen and phosphorus concentrations directly affected the phytoplankton dynamics. Organisms belonging to the class Cyanophyceae were the most representative in all the sampling periods, comprising the functional groups K, S1, M and H. Hydrodynamics and seasonal fluctuations of environmental factors were the driving forces determining the composition and abundance of the algal assemblages. Despite the prevalence of Cyanobacteria, the reservoir is still oligotrophic. The absence of blooms and the relatively low population abundances indicated that the quality of the reservoir's water still lies within the limits required for its multiples uses.

  6. Phytoplankton community structure and dynamics in the North Atlantic subtropical gyre

    Science.gov (United States)

    Cáceres, Carlos; Rivera, Antonella; González, Sonia; Anadón, Ricardo

    2017-02-01

    Phytoplankton fuel epipelagic ecosystems and affect global biogeochemical cycles. Nevertheless, there is still a lack of quantitative information about the factors that determine both phytoplankton community structure and dynamics, particularly in subtropical gyres. Here, we estimated size fractionated phytoplankton growth (μ) and microzooplankton grazing rates (m) along a transect in the subtropical North Atlantic, from the island of Hispaniola to the Iberian Peninsula, by conducting dilution experiments and fitting mixed models. We also examined the relationship between nutrient availability and the differences in both phytoplankton community structure and size fractionated phytoplankton growth rates at two spatial scales (i.e. subtropical gyre and within-province spatial scale). Our results revealed high values for both phytoplankton growth and microzooplankton grazing rates. Phytoplankton growth (0.00-1.19 d-1) displayed higher variability among stations, biogeochemical provinces and size fractions than the microzooplankton grazing rate (0.32-0.74 d-1). Differences in phytoplankton community structure were associated with dissolved inorganic nitrogen (0.72-5.85 μM; R2 = 0.19) and squared Brunt-Väisälä frequency (R2 = 0.21) at the whole gyre scale. Conversely, the differences in phytoplankton growth rate showed a weak relationship with those properties (R2 ⩽ 0.05) at that scale, but a stronger relationship at the within province scale (R2 ⩾ 0.07). These results support the idea that phytoplankton grow at high rates in oligotrophic subtropical gyres, this is likely due to the selection of phytoplankton groups with functional traits suited to exploit low nutrient availability. Thus, shedding new, multi-scale knowledge on the commonly misunderstood "ocean deserts".

  7. Development of a cost-effective metabarcoding strategy for analysis of the marine phytoplankton community.

    Science.gov (United States)

    Yoon, Tae-Ho; Kang, Hye-Eun; Kang, Chang-Keun; Lee, Sang Heon; Ahn, Do-Hwan; Park, Hyun; Kim, Hyun-Woo

    2016-01-01

    We developed a cost-effective metabarcoding strategy to analyze phytoplankton community structure using the Illumina MiSeq system. The amplicons (404-411 bp) obtained by end-pairing of two reads were sufficiently long to distinguish algal species and provided barcode data equivalent to those generated with the Roche 454 system, but at less than 1/20th of the cost. The original universal primer sequences targeting the 23S rDNA region and the PCR strategy were both modified, and this resulted in higher numbers of eukaryotic algal sequences by excluding non-photosynthetic proteobacterial sequences supporting effectiveness of this strategy. The novel strategy was used to analyze the phytoplankton community structure of six water samples from the East/Japan Sea: surface and 50 m depths at coastal and open-sea sites, with collections in May and July 2014. In total, 345 operational taxonomic units (OTUs) were identified, which covered most of the prokaryotic and eukaryotic algal phyla, including Dinophyta, Rhodophyta, Ochrophyta, Chlorophyta, Streptophyta, Cryptophyta, Haptophyta, and Cyanophyta. This highlights the importance of plastid 23S primers, which perform better than the currently used 16S primers for phytoplankton community surveys. The findings also revealed that more efforts should be made to update 23S rDNA sequences as well as those of 16S in the databases. Analysis of algal proportions in the six samples showed that community structure differed depending on location, depth and season. Across the six samples evaluated, the numbers of OTUs in each phylum were similar but their relative proportions varied. This novel strategy would allow laboratories to analyze large numbers of samples at reasonable expense, whereas this has not been possible to date due to cost and time. In addition, we expect that this strategy will generate a large amount of novel data that could potentially change established methods and tools that are currently used in the realms of

  8. Development of a cost-effective metabarcoding strategy for analysis of the marine phytoplankton community

    Directory of Open Access Journals (Sweden)

    Tae-Ho Yoon

    2016-06-01

    Full Text Available We developed a cost-effective metabarcoding strategy to analyze phytoplankton community structure using the Illumina MiSeq system. The amplicons (404–411 bp obtained by end-pairing of two reads were sufficiently long to distinguish algal species and provided barcode data equivalent to those generated with the Roche 454 system, but at less than 1/20th of the cost. The original universal primer sequences targeting the 23S rDNA region and the PCR strategy were both modified, and this resulted in higher numbers of eukaryotic algal sequences by excluding non-photosynthetic proteobacterial sequences supporting effectiveness of this strategy. The novel strategy was used to analyze the phytoplankton community structure of six water samples from the East/Japan Sea: surface and 50 m depths at coastal and open-sea sites, with collections in May and July 2014. In total, 345 operational taxonomic units (OTUs were identified, which covered most of the prokaryotic and eukaryotic algal phyla, including Dinophyta, Rhodophyta, Ochrophyta, Chlorophyta, Streptophyta, Cryptophyta, Haptophyta, and Cyanophyta. This highlights the importance of plastid 23S primers, which perform better than the currently used 16S primers for phytoplankton community surveys. The findings also revealed that more efforts should be made to update 23S rDNA sequences as well as those of 16S in the databases. Analysis of algal proportions in the six samples showed that community structure differed depending on location, depth and season. Across the six samples evaluated, the numbers of OTUs in each phylum were similar but their relative proportions varied. This novel strategy would allow laboratories to analyze large numbers of samples at reasonable expense, whereas this has not been possible to date due to cost and time. In addition, we expect that this strategy will generate a large amount of novel data that could potentially change established methods and tools that are currently used in

  9. Spatio-temporal distribution of net-collected phytoplankton community and its response to marine exploitation in Xiangshan Bay

    Institute of Scientific and Technical Information of China (English)

    JIANG Zhibing; ZHU Xuyu; GAO Yu; CHEN Quanzhen; ZENG Jiangning; ZHU Genhai

    2013-01-01

    To explore the spatial-temporal distribution of the phytoplankton community and evaluate the combined effects of marine resource exploitation,net-collected phytoplankton and physical-chemical parameters were investigated in the Xiangshan Bay during the four seasons of 2010.A total of eight phyla,97 genera,and 310 species were found,including 232 diatom species,45 dinoflagellate species and 33 other taxa.The phytoplankton abundances presented a significant (P<0.001) seasonal difference with the average of 60.66×104 cells/m3.Diatoms (mainly consisting of Coscinodiscus jonesianus,Cerataulina pelagica,Skeletonema costatum,and genus Chaetoceros) dominated the phytoplankton assemblage in all seasons.We found great spatio-temporal variation in community composition based on the multidimensional scaling and similarity analysis.Canonical correspondence analysis show that temperature,nutrition,illumination,and salinity were the main variables associated with microalgal assemblage.Compared with the previous studies,an increase in phytoplankton abundance and change in the dominant species coincided with increased exploitation activities in this bay (e.g.operation of coastal power plants,intensive mariculture,tidal flat reclamation,and industrial and agricultural development).The present findings suggest that the government should exercise caution when deciding upon developmental patterns in the sea-related economy.

  10. Variation of summer phytoplankton community composition and its relationship to nitrate and regenerated nitrogen assimilation across the North Atlantic Ocean

    Science.gov (United States)

    Van Oostende, N.; Fawcett, S. E.; Marconi, D.; Lueders-Dumont, J.; Sabadel, A. J. M.; Woodward, E. M. S.; Jönsson, B. F.; Sigman, D. M.; Ward, B. B.

    2017-03-01

    The North Atlantic Ocean is considered a nitrogen (N) limited system once vernal stabilisation of the water column alleviates light limitation and allows phytoplankton growth to deplete surface nutrients to virtually undetectable levels. Ammonium and other regenerated N forms are then the main surface N source for phytoplankton production. The effort to determine which phytoplankton groups contribute to long-term biological export production would be greatly aided by information on which phytoplankton groups are responsible for the assimilation of nitrate, as opposed to those assimilating predominantly regenerated N. In this study, we used the natural abundance N isotopes to examine basin-scale patterns of nitrate and regenerated N assimilation and evaluated the relationships between these trends and phytoplankton community composition. Samples were collected during a summertime cruise transect (August-September 2013) from the subtropical (36°N 73°W) to the subarctic (54°N 20°W) North Atlantic and analysed for the N isotopic composition (δ15N vs. N2 in air) of particulate nitrogen (PN) and nitrate, size-fractionated chlorophyll a, and phytoplankton group biomass using flow cytometry. The depth of the 300 nmol l-1 nitrate isopleth shoaled from the subtropics (79 m), where phytoplankton stripped surface waters of nitrate, to the subarctic, where it intersected with the surface and the upward nutrient supply drove a summer phytoplankton bloom. The δ15N of PN above the nitracline increased from the subtropics (-0.3‰) to the subarctic (4.2‰), reflecting both a change in the δ15N of the subsurface nitrate source (from 2.4‰ to 5.1‰) and increased reliance by phytoplankton on nitrate relative to regenerated N. Throughout the transect, the phytoplankton community was mainly composed of pico- and nano-sized cells (>88% of chlorophyll a in the <20 μm size fraction). In the part of the transect southwest of the Grand Banks, Prochlorococcus and Synechococcus

  11. Community structure and spatial-temporal variation of netz-phytoplankton in the Bering Sea in summer

    Institute of Scientific and Technical Information of China (English)

    WANG Yu; XIANG Peng; YE Youyin; LIN Gengming; YANG Qingliang; LIN Heshan; LIN Mao

    2016-01-01

    Marine biodiversity is changing in response to altered physical environment, subsequent ecological changes as well as anthropogenic disturbances. In this study, phytoplankton samplesin situ collected in the Bering Sea in July of 1999 and 2010 were analyzed to obtain phytoplankton community structure and spatial-temporal variation between the beginning and end of this decade, and the correlation of phytoplankton community dynamics and environmental factors was investigated. A total of 5 divisions, 58 genera and 153 species of phytoplankton belonging to 3 ecological groups were identified. The vast majority of phytoplankton consisted of diatoms accounting for 66.7% of the total species and 95.2% of the total abundance. Considering differentiation in spatial extent and phytoplankton sample types, there were subtle changes in species composition, large altering in abundance and significant variation in spatial distribution between two surveys. The abundance peak area was located at the Bering Strait while sub peak was found at the Bering Sea Basin. The boreal-temperate diatom was the dominant flora, which was subsequently replaced by eurythermal and frigid-water diatom. Phytoplankton community in the Bering Sea was not a simplex uniform community but composed of deep-ocean assemblage and neritic assemblage. The deep-ocean assemblage was located in the northwestern Pacific Ocean and Bering Sea Basin, dominated by boreal-temperate species (Neodenticula seminae,Thalassiothrix longissima,Amphiprora hyperborean,Chaetoceros atlanticus,Thalassiosira trifulta, etc.) and eurychoric species (Thalassionema nitzschioides,Ch. compressus,Rhizosolenia styliformis, etc.), and characterized by low abundance, even inter-species abundance allocations, diverse dominant species and high species diversity. The neritic assemblage was distributed on the continental shelf and slope of Bering Sea and was mainly composed of frigid-water species (Th. nordenskiöldii,Ch. furcellatus,Ch. socialis

  12. [Community structure characteristics of phytoplankton and related affecting factors in Hengshan Reservoir, Zhejiang, China].

    Science.gov (United States)

    Yang, Liang-Jie; Yu, Peng-Fei; Zhu, Jun-Quan; Xu, Zhen; Lü, Guang-Han; Jin, Chun-Hua

    2014-02-01

    In order to reveal the community structure characteristics of phytoplankton and the relationships with environmental factors in Hengshan Reservoir, the phytoplankton species composition, abundance, biomass and 12 environmental factors at 4 sampling sites were analyzed from March 2011 to February 2012. A total of 246 phytoplankton species were identified, which belong to 78 genera and 7 phyla. The dominant species were Melosira varians, M. granulate, Cyclotella meneghiniana, Asterianella formosa, Synedra acus, Achnanthes exigua, Ankistrodesmus falcatus, Oscillatoria lacustris, Cryptomonas erosa, Chroomonas acuta, Phormidium tenue and Microcystis aeruginosa, etc. Seasonal variations of species were obvious. The annual abundance and biomass of the phytoplankton were 0.51 x 10(5)-14.22 x 10(5) ind x L(-1) and 0.07-1.27 mg x L(-1), respectively. The values of the Margelef index, Pielou index and Shannon index of the phytoplankton community were 1.10-3.33, 0.26-0.81 and 0.51-2.38, respectively. The phytoplankton community structure was of Bacillariophyta-Cryptophyta type in spring and winter, of Chlorophyta-Cyanophyta type in summer, and of Bacillariophyta type in autumn. Canonical correlation analysis (CCA) showed that temperature, transparency, chemical oxygen demand and pH had the closest relationships with the phytoplankton community structure in the reservoir. Water quality evaluation showed that Hengshan Reservoir was in a secondary pollution with a meso-trophic level.

  13. Phytoplankton abundance and community structure in the Antarctic polar frontal region during austral summer of 2009

    Institute of Scientific and Technical Information of China (English)

    SHRAMIK Patil; RAHUL Mohan; SUHAS Shetye; SAHINA Gazi

    2013-01-01

    The Antarctic polar front region in the Southern Ocean is known to be most productive.We studied the phytoplankton community structure in the Indian sector at this frontal location during late austral summer (February,2009) onboard R/V Akademic Boris Petrov.We used the phytoplankton and microheterotrophs abundance,as also the associated physico-chemical parameters to explain the low phytoplankton abundance in the study region.This study emphasizes the shift of phytoplankton,from large (>10 μm) to small (<10 μm) size.The phytoplankton abundance appears to be controlled by physical parameters and by nutrient concentrations and also by the microheterotrophs (ciliates and dinoflagellates) which exert a strong grazing pressure.This probably reduces small (<10 μm) and large (>10 μm)phytoplankton abundance during the late austral summer.This study highlights the highly productive polar front nevertheless becomes a region of low phytoplankton abundance,due to community shifts towards pico-phytoplankton (<10 μm) during late austral summer.

  14. Phytoplanktonic desmids community in Donghu Lake, Wuhan,China

    Institute of Scientific and Technical Information of China (English)

    WEI Yinxin; YU Minjuan

    2005-01-01

    For compilation and comparison of desmids flora, the authors restudied the species composition,cell density and biomass of phytoplankton desmids collected at six stations in Donghu Lake at intervals of three months monitored from March of 1956 to February of 1957. A total of 122 taxa belonging to 16 genera were identified from qualitative and quantitative samples. Species of Cosmarium were the most popular ones occupying about 41% of the total species. Based on the observations, the annual mean values of the cell density and biomass were 132.11 × 102 cells/L and 0.09 mg/L. Cosmarium, Staurastrum, Staurodesmus and Closterium dominated and contributed more than 70 % of the total cell density and biomass at six stations in four seasons.The maximum species number, cell density and biomass in autumn revealed that the highest variety (64 taxa,1296× 102 cells/L and 0.889 mg/L respectively) occurred at Station 3 located in the southern part of Donghu Lake. From then on to the mid 1990s the desmids community decreased sharply in Donghu Lake, resulted clearly from eutrophication in the lake.

  15. Phytoplanktonic desmids community in Donghu Lake, Wuhan, China

    Science.gov (United States)

    Wei, Yinxin; Yu, Minjuan

    2005-03-01

    For compilation and comparison of desmids flora, the authors restudied the species composition, cell density and biomass of phytoplankton desmids collected at six stations in Donghu Lake at intervals of three months monitored from March of 1956 to February of 1957. A total of 122 taxa belonging to 16 genera were identified from qualitative and quantitative samples. Species of Cosmarium were the most popular ones occupying about 41% of the total species. Based on the observations, the annual mean values of the cell density and biomass were 132.11×102 cells/L and 0.09 mg/L. Cosmarium, Staurastrum, Staurodesmus and Closterium dominated and contributed more than 70% of the total cell density and biomass at six stations in four seasons. The maximum species number, cell density and biomass in autumn revealed that the highest variety (64 taxa, 1296×102 cells/L and 0.889 mg/L respectively) occurred at Station 3 located in the southern part of Donghu Lake. From then on to the mid 1990s the desmids community decreased sharply in Donghu Lake, resulted clearly from eutrophication in the lake.

  16. Photophysiological state of natural phytoplankton communities in the South China Sea and Sulu Sea

    Directory of Open Access Journals (Sweden)

    W. Cheah

    2013-07-01

    Full Text Available In recent years, an increasing number of studies on phytoplankton in the tropical South China Sea (SCS and Sulu Sea (SS have been conducted. However, still little is known about the photophysiological state of natural phytoplankton communities under varying environmental conditions. This study investigates the photophysiological state of natural phytoplankton communities in the southern SCS and SS based on high horizontal and vertical resolution field observations collected during the SHIVA (Stratosphere ozone: Halogens in a Varying Atmosphere cruise (SO 218 in November 2011 on board RV Sonne. At the surface, pigment results revealed that total chlorophyll a (TChl a concentrations at all offshore stations were low at the surface and were generally dominated by cyanobacteria. Enhanced concentrations of TChl a were only observed below the upper mixed layer and above the euphotic depth with haptophytes, prochlorophytes and prasinophytes contributing most of the biomass. At stations close to the coast and river outflows, surface phytoplankton blooms (between 1 to 2.2 mg m−3 dominated by diatoms were observed. Overall, the study region exhibited strong nitrate + nitrite (NOx, −1, and phosphate (PO4, −1 depletion from surface down to about 50–60 m. Silicate (Si exhibited similar trends with the exception of some near shore stations in which high Si concentrations (> 2 μmol L−1 were observed in conjunction with increased TChl a and diatoms concentrations. Surface NOx concentrations were observed to correlate positively with temperature (τ = 0.22, p n = 108, whereas negative correlations were reported between surface NOx (τ = −0.27, p n = 108, Si (τ = −0.68, p n = 108 and salinity indicating that the enhancement in nutrients at the surface was probably supplied through fresher and warmer river waters near the coast. In contrast, the opposite was observed between temperature, salinity and all nutrients in the water column suggesting

  17. The effect of seasonality in phytoplankton community composition on CO2 uptake on the Scotian Shelf

    Science.gov (United States)

    Craig, Susanne E.; Thomas, Helmuth; Jones, Chris T.; Li, William K. W.; Greenan, Blair J. W.; Shadwick, Elizabeth H.; Burt, William J.

    2015-07-01

    We characterise seasonal patterns in phytoplankton community composition on the Scotian Shelf, northwest Atlantic Ocean, through a study of the numerical abundance of different cell sizes - pico-, nano- and microphytoplankton. Cell abundances of each size class were converted to cellular carbon and their seasonal patterns compared with the partial pressure of carbon dioxide (pCO2) also measured at the study site. We observed a persistent drawdown of CO2 throughout the summer months, despite nutrient depleted conditions and apparent low biomass suggested by the chlorophyll record. This drawdown was associated with a summertime phytoplankton assemblage numerically dominated by small phytoplankton that reach their peak abundance during this period. It was found that phytoplankton carbon during this period accounted for approximately 10% of spring bloom phytoplankton carbon and pointed to the importance role that small cells play in annual CO2 uptake.

  18. Phytoplankton community structure in the Lena Delta (Siberia, Russia in relation to hydrography

    Directory of Open Access Journals (Sweden)

    A. C. Kraberg

    2013-02-01

    Full Text Available The Lena Delta in Northern Siberia is one of the largest river deltas in the world. During peak discharge, after the ice melt in spring, it delivers between 60–8000 m3s−1 of water and sediment into the Arctic Ocean. The Lena Delta and the Laptev Sea coast also constitute a~continuous permafrost region. Ongoing climate change, which is particularly pronounced in the Arctic, is leading to increased rates of permafrost thaw. This is likely to profoundly change the discharge rates of the Lena River and the chemistry of the river waters which are discharged into the coastal Laptev Sea, e.g. by increasing concentrations of inorganic nutrients, DOC and importantly methane. These physical and chemical changes will also affect the composition of and interactions between phytoplankton and zooplankton communities, forming the basis of the food web. However, before potential consequences of climate change for coastal arctic plankton communities can be judged, the inherent status of the diversity and linked foodweb interactions within the delta need to be established. As part of the AWI Lena Delta Programme in 2010 the phyto- and microzooplankton community in three river channels as well as four coastal transects were investigated to capture the typical river phytoplankton communities and the transitional zone of brackish/marine conditions. Most CTD profiles from 23 coastal stations showed very strong stratification. The only exception to this was a small a shallow and mixed area running from the outflow of Bykovskaya channel in a northerly direction parallel to the shore (transect 3. Of the five stations in this area three had a salinity of close to zero. Two further stations had salinities of around 2 and 5 throughout the water column. In the remaining transects on the other hand salinities varied between 5–30 with depth. Phytoplankton counts from the outflow from the Lena were dominated by diatoms (Aulacoseira species

  19. Development of phytoplankton communities: Implications of nutrient injections on phytoplankton composition, pH and ecosystem production

    DEFF Research Database (Denmark)

    Jakobsen, Hans; Blanda, Elisa; Stæhr, Peter Anton;

    2015-01-01

    developed and became dominant whereas diatoms became rare as compared to the parallel controls. At pH > 9, a shift from the presence of the potential nuisance Alexandrium pseudogonyaulax towards high pH tolerant Prorocentrum species was observed. Diatoms disappeared when A. pseudogonyaulax became dominant......The development of a marine phytoplankton community was studied in a series of mesocosm tanks exposed to different levels of nutrient inputs. Key ecosystem variables such as phytoplankton species development, ecosystem net production (NEP), pH and bacteria production were measured. The overall aim...... was to mimic the consequences of extreme weather events by applying nutrients in either repeated (pulse treatment) versus a single inputs (full treatment). Regardless of treatment type, pH increased steadily, until nutrients became exhausted. During the experiment, potentially nuisance dinoflagellates...

  20. Mechanisms shaping size structure and functional diversity of phytoplankton communities in the ocean

    Science.gov (United States)

    Acevedo-Trejos, Esteban; Brandt, Gunnar; Bruggeman, Jorn; Merico, Agostino

    2015-03-01

    The factors regulating phytoplankton community composition play a crucial role in structuring aquatic food webs. However, consensus is still lacking about the mechanisms underlying the observed biogeographical differences in cell size composition of phytoplankton communities. Here we use a trait-based model to disentangle these mechanisms in two contrasting regions of the Atlantic Ocean. In our model, the phytoplankton community can self-assemble based on a trade-off emerging from relationships between cell size and (1) nutrient uptake, (2) zooplankton grazing, and (3) phytoplankton sinking. Grazing `pushes' the community towards larger cell sizes, whereas nutrient uptake and sinking `pull' the community towards smaller cell sizes. We find that the stable environmental conditions of the tropics strongly balance these forces leading to persistently small cell sizes and reduced size diversity. In contrast, the seasonality of the temperate region causes the community to regularly reorganize via shifts in species composition and to exhibit, on average, bigger cell sizes and higher size diversity than in the tropics. Our results raise the importance of environmental variability as a key structuring mechanism of plankton communities in the ocean and call for a reassessment of the current understanding of phytoplankton diversity patterns across latitudinal gradients.

  1. Algae/bacteria consortium in high rate ponds : influence of solar radiation on the phytoplankton community.

    OpenAIRE

    Assemany, Paula Peixoto; Calijuri, Maria Lúcia; Couto, Eduardo de Aguiar do; Souza, Mauro Henrique Batalha de; Silva, Nirlane Cristiane; Santiago, Aníbal da Fonseca; Castro, Jackeline de Siqueira

    2015-01-01

    Using multivariate statistical tools, the composition of the phytoplankton community was related to the characteristics of the domestic sewage used as culture medium in three high rate ponds (HRPs) submitted to different solar radiation levels. A total of 32 genera of phytoplankton were identified in the ponds; the class Chlorophyceae was the most abundant during the entire sampling period, with a larger number of individuals of the genus Desmodesmus in the summer and fall, and of the genu...

  2. Phytoplankton community and limnochemistry of Piburger See (Tyrol, Austria 28 years after lake restoration

    Directory of Open Access Journals (Sweden)

    Hansjörg THIES

    2002-02-01

    Full Text Available Phytoplankton community and limnochemistry of Piburger See, a small soft-water, meromictic lake situated at 913 m a.s.l. in a crystalline area of the Central Eastern Alps of Tyrol (Austria, were investigated 28 years after the beginning of lake restoration. Although long-term data of the lake show a declining trend in total phosphorus concentrations and phytoplankton biovolume, the response of Piburger See to the restoration measures carried out in 1970 was delayed by about 20 years. At present the lake is approaching its former oligotrophic level. The most evident difference between the past and present phytoplankton species composition of Piburger See is the actual absence of the Cyanophycean Oscillatoria limosa C. A. Agardh, which markedly increased during the first two decades after the lake restoration (1970-1987. The phytoplankton biovolume recorded in 1998 was lower than in the 1970s and 1980s, while seasonal patterns were similar to those recorded before and later on in the lake restoration. The lowest annual phytoplankton biovolume in 1998 occurred in early winter, while the absolute maximum was observed in metalimnetic water layers in late spring. In 1998 the intra-annual patterns of phytoplankton biovolume and chlorophyll-a compare well. Phytoplankton succession started in early 1998 under ice with coccal green algae followed by flagellated Chrysophyceae during spring. The mid-summer phytoplankton community was dominated by centric Bacillariophyceae, which were later replaced by coccal Cyanophyceae. During autumn, Dinophyceae and Chrysophyceae prevailed. Epilimnetic dominance of centric diatoms during mid summer appears to be a new feature, which in 1998 was related to a strong depletion of dissolved silica and nitrate. Long-term water chemistry and phytoplankton data were checked against local weather data in order to explain the delay in the re-oligotrophication process of Piburger See. However, no clear relationship could be

  3. Phytoplankton community structure and environmental parameters in aquaculture areas of Daya Bay, South China Sea.

    Science.gov (United States)

    Wang, Zhaohui; Zhao, Jiangang; Zhang, Yujuan; Cao, Yu

    2009-01-01

    Environmental characteristics and phytoplankton community structure were investigated in two aquaculture areas in Dapeng Cove of Daya Bay, South China Sea, between April 2005 and June 2006. Phytoplankton abundance ranged between 5.0 and 8877.5 cells/mL, with an average of 751.8 cells/mL. The seasonal cycle of phytoplankton were demonstrated by frequent oscillations, with recurrent high abundances from late spring to autumn and a peak stage in late winter. Diatoms were the predominant phytoplankton group, accounting for 93.21% of the total abundance. The next most abundant group was the dinoflagellates, which made up only 1.24% of total abundance. High concentrations of Alexandrium tamarense (Lebour) Balech with a maximum of 603.0 cells/mL were firstly recorded in this area known for high rates of paralytic shellfish poisoning (PSP) contamination. Temperatures and salinities were within the suitable values for the growth of phytoplankton, and were important in phytoplankton seasonal fluctuations. The operation of the Daya Bay Nuclear Power Station (DNPS) exerts influences on the phytoplankton community and resulted in the high abundances of toxic dinoflagellate species during the winter months. Dissolved inorganic nitrogen (DIN) and dissolved silicate (DSi) were sufficient, and rarely limited for the growth of phytoplankton. Dissolved inorganic phosphorus (DIP) was the most necessary element for phytoplankton growth. The enriched environments accelerated the growth of small diatoms, and made for the shift in predominant species from large diatom Rhizosolenia spp. to chain-forming diatoms such as Skeletonema costatum, Pseudo-nitzschia spp. and Thalassiosira subtilis.

  4. Structure and dynamics of the phytoplankton community within a maturation pond in a semiarid region

    Directory of Open Access Journals (Sweden)

    E. A. Pastich

    Full Text Available Abstract In northeastern Brazil, stabilization ponds are very suitable for wastewater treatment because of the relative great land availability and environmental conditions (e.g., high temperature favorable for microorganism optimal development. However, blooms of potentially toxic cyanobacteria may affect the use of these treatment ponds due to resulting effluent poor quality. The objective of this study was to evaluate the dynamics of phytoplankton communities and the occurrence of cyanobacteria in a maturation pond located immediately after a series of two ponds. Temperature, dissolved oxygen, pH, BOD, N, and P were measured during a period of four months when samples were collected from the surface and the bottom of 7 sampling points distributed inside the pond. The phytoplankton of collected samples was also identified and classified using a conventional optical microscopy. Analysis of variance and Tukey test were used to evaluate the results. The three phytoplankton divisions found (Cyanophyta, Chlorophyta, and Euglenophyta did not change considerably through surface and bottom. However, they changed greatly over the sampled months; great dominance of Cyanophyta was found at April and October, while Chlorophyta dominated the lagoon in September. Low superficial organic loads (between 78 and 109 kg BOD.ha–1.d–1 and N:P ≤ 10 were the determinant factors that favored the predominance of Cyanophyta. The presence of two potentially toxic species of Cyanophyta, Oscillatoria sp. and Microcystis aeruginosa, indicates that caution is required when considering the final destination of treated effluent and suggests a need to assess the risks and benefits associated with the use of the treatment technology.

  5. Reversal in the relationship between species richness and turnover in a phytoplankton community.

    Science.gov (United States)

    Matthews, Blake; Pomati, Francesco

    2012-11-01

    Negative relationships between species richness and the rate of compositional turnover are common, suggesting that diverse communities have greater stability than depauperate ones; however, the mechanistic basis for this pattern is still widely debated. Species richness and turnover can covary either because they are mechanistically linked or because they share common environmental drivers. Few empirical studies have combined long-term changes in community composition with multiple drivers of environmental change, and so little is known about how the underlying mechanisms of species coexistence interact with changes in the mean and variability of environmental conditions. Here, we use a 33 year long time series (1976-2008) of phytoplankton community composition from Lake Zurich, to examine how environmental variation influences the relationship between richness and annual turnover. We find that the relationship between richness and annual turnover reverses midway through the time series (1992-1993), leading to a hump-shaped relationship between species richness and annual turnover. Using structural equation modeling we show that annual turnover and diversity are independently associated with different drivers of environmental change. Furthermore, we find that the observed annual sequences of community assembly give rise to rates of species accumulation that are more heterogeneous through time than expected by chance, likely owing to a high proportion of species showing significant autocorrelation and to strong positive covariation in the occurrences of species.

  6. Ecological relationships between phytoplankton communities at different spatial scales in European reservoirs: implications at catchment level monitoring programmes.

    NARCIS (Netherlands)

    Cabecinha, E.; Brink, van den P.J.; Cabral, J.A.; Cortes, R.

    2009-01-01

    Phytoplankton communities are structured by factors acting over temporal and spatial scales. Identifying which factors are driving spatial patterns in aquatic communities is the central aim of ecology. In this study, data sets of phytoplankton communities and environmental data of two Portuguese res

  7. Effects of iron stress on chromatic adaptation by natural phytoplankton communities in the Southern Ocean

    NARCIS (Netherlands)

    van Leeuwe, M.A.; Timmermans, K.R.; Witte, H.J.; Kraay, G.W.; Veldhuis, M.J.W.; de Baar, H.J.W.

    1998-01-01

    Effects of iron stress on chromatic adaptation were studied in natural phytoplankton communities collected in the Pacific region of the Southern Ocean. Iron enrichment experiments (48 to 72 h) were performed, incubating plankton communities under white, green and blue light respectively, with and wi

  8. Phytoplankton Community Dynamics in West Lake After Drawing Water from the Qiantang River

    Institute of Scientific and Technical Information of China (English)

    魏印心; 李瑾; 虞左明

    2004-01-01

    Seventeen phytoplankton dominant species of 218 taxa were found to have contributed to more than 80% of the biomass after analysis of the January, 1955 to December, 1996 phytoplankton population at five stations in West Lake after Qiantang River water had been drawn into the lake for a decade. The seasonal fluctuations were obvious; the maximum cell density of 90.91×107-93.58×107 cells/L and biomass of 57.41-58.61 mg/L occurred mainly in summer of 1996,largely as a result of the development of Lyngbya contorta, Merismopedia tenuissima, Oscillatoria limnetica, Spirulina laxissima and Scenedesmus quadricauda, etc. at Stations 2 and 4. At Station 1 located near the inlet for drawing water from the Qiantang River, the species number, cell density, biomass, chlorophyll a concentration and physico-chemical parameters (except for total nitrogen) were obviously greater than those at the other four stations, also greater than the corresponding parameters before the drawing of water from the Qiantang River into the lake.Compared with the results of study on the phytoplankton community in 1980 before the drawing of Qiantang River into the lake, the species number and the total individual density were increased, the dominant species changed somewhat, the biomass was decreased. The water quality was improved (especially at Station 1) after the drawing of river water into the lake.Based on criteria for evaluating trophic status, the biological and chemical indicators such as species composition and dominant species, and other parameters such as annual mean value cell densities (36.06×107-51.27×107 cells/L), biomass (29.03-39.74 mg/L), chl a concentrations (41.29-67.67μg/L), total nitrigen (1.72-2.89 mg/L), total phosphorus (0.12-0.16 mg/L) obtained at Stations 2, 3, 4 and 5, showed that West Lake is still at eutrophic lake.

  9. Phytoplankton Community of Elechi Creek, Niger Delta, Nigeria-A Nutrient-Polluted Tropical Creek

    Directory of Open Access Journals (Sweden)

    O. A. Davies

    2009-01-01

    Full Text Available Problem statement: Elechi Creek of the Upper Bonny Estuary in the Niger Delta contributes to the Rivers State Fish resources. It is a sink receiving organic anthropogenic wastes from Diobu, Eagle Island and waterfront dwellers of Diobu areas. Fishing, car washing, bathing, swimming and other human activities are constantly going on within and around this creek. Based on these activities, there is urgent need to study the phytoplankton community that supports its fisheries. Approach: The study investigated the phytoplankton composition, diversity, abundance and distribution as well as surface water physico-chemical parameters. Phytoplankton and surface water samples were collected bi-monthly from October 2007-March 2008 at high tide from five stations according to APHA methods. These were analyzed for temperature, transparency, dissolved oxygen, salinity, alkalinity, chloride and nutrients. Phytoplankton was identified microscopically. Species diversity was calculated using standard indices. Results: A total of 169 species of phytoplankton, based on cell counts, was dominated by diatoms, 33255 counts mL-1 (36% and blue-green algae, 32909 counts mL-1 (35.7% were identified. The abundance of phytoplankton decreased downstream of this creek (1>2>3>4 except in station 5 with the highest phytoplankton abundance (23938 counts mL-1. There was slight fluctuation in the measured physico-chemical parameters. The results of this study indicated the characteristic species and distribution of phytoplankton in Elechi Creek during the dry months. Conclusion/Recommendation: The high level of phosphate above the permissive limit showed that this creek is hypereutrophic and organic polluted. The high nutrients status favors the high abundance of phytoplankton. The municipal effluents (especially raw human and animal faces discharges must be discontinued. Detergents with low concentration of phosphate are recommended for manufacturing and use. Municipal wastes must

  10. 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

  11. Composition, abundance and ecology of phytoplankton communities of Loktak Lake, Manipur, India

    Directory of Open Access Journals (Sweden)

    B.K. Sharma

    2009-08-01

    Full Text Available Phytoplankton communities of Loktak Lake (a Ramsar site, studied during November 2002-October 2004, reveal the occurrence of 75 and 71 species, indicate monthly richness ranging between 47� plus or minus 6 and 49� plus or minus 3 species and record 50.0-83.2 and 64.5-84.0 % community similarities during two annual cycles respectively. Chlorophyta (33� plus or minus 5 and 35� plus or minus 5 species show qualitative dominance and importance of Closterium > Cosmarium > Staurastrum > Micrasterias > Gonatozygon species. Phytoplankton (206� plus or minus 58 and 220� plus or minus 53 n/l comprise between 45.1� plus or minus 6.5 and 42.9� plus or minus 5.8 % of net plankton abundance, indicate trimodal annual patterns and record peak abundance during winter. Chlorophyta (111� plus or minus 20 and 119� plus or minus 15 n/l, the dominant quantitative component, indicate winter peaks; Closterium > Staurastrum > Gonatozygon > Micrasterias species contribute significantly to their abundance. Ceratium hirudinella (43� plus or minus 52 and 39� plus or minus 37 n/l is the sole important individual species of phytoplankton. Dinophyta > Bacillariophyta are sub-dominant groups and Euglenophyta > Cyanophyta > Chrysophyta show very low densities. Phytoplankton communities are characterized by higher species diversity, higher evenness and lower dominance. Abiotic factors register limited influence on richness and abundance of phytoplankton and on abundance of constituent groups. Multiple regression indicates relatively lower influence of fifteen abiotic factors on richness of phytoplankton and higher cumulative influence on abundance of phytoplankton, Chlorophyta, Dinophyta and Bacillariophyta.

  12. [Seasonal variations of community structures phytoplankton in groundwater discharge areas along the Northern Yucatán Peninsula coast].

    Science.gov (United States)

    Alvarez-Góngora, Cynthia Catalina; Liceaga-Correa, Maria de los Angeles; Herrera-Silveira, Jorge Alfredo

    2012-03-01

    The highly touristic Yucatán Peninsula is principally constituted with coastal marine environments. Like other coastal areas, this has been affected by the increase of waste water discharge, hydrological modifications and land use changes in the area. The phytoplankton community structure is one of the main components of coastal ecosystems and the most affected in hydrological processes. In order to follow the seasonal variations, the phytoplankton was characterized to follow the hydrological variability in two sites (Dzilam and Progreso) of the Northern Yucatán Peninsula. For this, cruises were carried out monthly during one year, from April 2004 to March 2005, with two samplings per season (dry, rainy and "nortes"). Hydrological variability was associated with seasonality and directly linked to groundwater discharges in the Dzilam area, and waste water discharges in the Progreso area. The highest nutrient concentrations occurred mainly during the rainy season. The phytoplankton community changes observed throughout the year suggested that the hydrological and chemical variability associated with seasonality and anthropogenic impacts have a strong influence. The substitution of diatoms by dinoflagellates as the dominant group in Progreso was the result of seasonal variability itself, but also could have been caused by eutrophic processes; while in Dzilam, the major presence of diatoms could have been favored by groundwater discharges. The results of this study can be used to understand the linkages between stressors from the anthropogenic activities and coastal water quality and changes.

  13. 淀山湖水华高发期浮游植物群落变化特征研究%Characteristics of Phytoplankton Community Changes in Dianshan Lake During Peak Period of Algal Blooms

    Institute of Scientific and Technical Information of China (English)

    徐春燕; 杨洁; 马明睿; 胡雪芹; 由文辉

    2012-01-01

    Based on the investigation data of phytoplankton in Dianshan Lake from May to October in 2009,the characteristics of phytoplankton community and the dominant species succession are studied.The results show that Cyanophyta and Chlorophta are the main taxa.Cyanophyta is dominant in cell abundance and Chlorophta is dominant in species variety.From the flat distribution,the species variety and density of Cyanophyta are higher in west and southwest.The peak of cell density reaches 23.40×107 cells·L-1 in September due to the occurrence of cyanobacterial bloom,Cyanophyta account for 90.3 percents,with significant differences in each point(ANOVA,P0.05).An obvious succession of phytoplankton species is found,Microcystis of Cyanophyta become the dominant taxa and then conglutinated together to form water bloom.Temperature and pH are the main factors that affect the cyanobacterial bloom,and wind direction is an important reason for the horizontal distribution of the bloom-forming Microcystis.The phytoplankton diversity index is poor in central and western sites,diversity index decreases during cyanobacterial bloom and the community structures are simple.%根据2009年5~10月淀山湖浮游植物数量和种类的观测结果,对水华高发季节浮游植物群落组成特点及优势种交替过程进行分析,初步探讨这一时期浮游植物群落特征与环境因子的关系.结果表明,这一时期浮游植物主要由蓝藻和绿藻组成,蓝藻在密度上、绿藻在种类上占优势.水平分布上,西部和西南部的蓝藻密度值和种类数较高.总密度最高峰出现在9月,其值为23.40×107cells.L-1,其中蓝藻数量占90.3%,各样点间总密度差异显著(ANOVA,P〈0.05).优势种在调查期间存在明显的交替现象,蓝藻门微囊藻属(Microcystis)藻类逐步成为优势种并形成水华.水温与pH是影响水华发生的重要环境因子,微囊藻受风向影响容易向下风向水域聚集形成水华.淀山湖

  14. Short-term variations of phytoplankton communities in response to anthropogenic stressors in a highly altered temperate estuary

    Science.gov (United States)

    Sin, Yongsik; Jeong, Byungkwan

    2015-04-01

    Data for phytoplankton size classes, taxonomy, and water properties were collected through an episodic freshwater discharge event (4 days) in the temperate Youngsan River estuary, which is highly disturbed by manually regulated inputs of freshwater from a sea dike, to investigate the effects of an acute change in anthropogenic stressors on the short-term dynamics of phytoplankton and their surrounding environments. The salinity of the well-mixed saline water (33.2-33.5) decreased to as low as 4.0 and water temperature increased to 24.0 °C during the freshwater discharge, resulting in a stratified water column in the upper region of the estuary. During the discharge, chlorophyll a (chl a) concentrations increased to as much as 15.66 μg L-1 with micro-sized phytoplankton being dominant due to the presence of micro-sized freshwater phytoplankton, mostly Aulacoseira ambigua (98% in cell abundance), transported from the reservoir. Primary production decreased to as little as 87.9 mg C m-2 d-1, although nutrients such as NO2- + NO3- were supplied by the freshwater inputs of the discharge. Following the discharge, dinoflagellate blooms, dominated by Heterocapsa sp. (>88%), a nano-sized red tide species, developed in the upper regions of the estuary with peaks in chl a concentrations reaching as high as 30.33 μg L-1. Another red tide species, Prorocentrum micans, was also dominant in the estuary, suggesting that harmful algal blooms (HABs) are associated with anthropogenic stressors related to the freshwater inputs. The Shannon diversity index decreased to 0.18 while the Simpson dominance index increased to 0.94 during the discharge, but the diversity increased again following the discharge. The phytoplankton communities and diversity changed along the salinity gradient, corresponding to an "ecocline" pattern. The results of multivariate statistical analysis suggested that phytoplankton species and size structure were controlled mainly by salinity, water temperature

  15. Size-selective toxicity effects of the antimicrobial tylosin on estuarine phytoplankton communities.

    Science.gov (United States)

    Kline, Allison; Pinckney, James L

    2016-09-01

    The purpose of this study was to determine the lethal and sublethal effects of the antimicrobial tylosin on natural estuarine phytoplankton communities. Bioassays were used in experimental treatments with final concentrations of 5 to 1000 μg tylosin l(-1). Maximum percent inhibition ranged from 57 to 85% at concentrations of 200-400 μg tylosin l(-1). Half maximum inhibition concentrations of tylosin were ca. 5x lower for small phytoplankton (20 μm) and suggests that small phytoplankton are more sensitive to tylosin exposure. Sublethal effects occurred at concentrations as low as 5 μg tylosin l(-1). Environmental concentrations of tylosin (e.g., 0.2-3 μg l(-1)) may have a significant sublethal effect that alters the size structure and composition of phytoplankton communities. The results of this study highlight the potential importance of cell size on toxicity responses of estuarine phytoplankton.

  16. A 150-year record of phytoplankton community succession controlled by hydroclimatic variability in a tropical lake

    Science.gov (United States)

    Afrifa Yamoah, Kweku; Callac, Nolwenn; Fru, Ernest Chi; Wohlfarth, Barbara; Wiech, Alan; Chabangborn, Akkaneewut; Smittenberg, Rienk H.

    2016-07-01

    Climate and human-induced environmental change promote biological regime shifts between alternate stable states, with implications for ecosystem resilience, function, and services. While these effects have been shown for present-day ecosystems, the long-term response of microbial communities has not been investigated in detail. This study assessed the decadal variations in phytoplankton communities in a ca. 150 year long sedimentary archive of Lake Nong Thale Prong (NTP), southern Thailand using a combination of bulk geochemical analysis, quantitative polymerase chain reaction (qPCR) and lipid biomarkers techniques including compound-specific hydrogen isotope analysis as a proxy for precipitation. Relatively drier and by inference warmer conditions from ca. 1857 to 1916 Common Era (CE) coincided with a dominance of the green algae Botryococcus braunii, indicating lower nutrient levels in the oxic lake surface waters, possibly related to lake water stratification. A change to higher silica (Si) input around 1916 CE was linked to increased rainfall and concurs with an abrupt takeover by diatom blooms lasting for 50 years. These were increasingly outcompeted by cyanobacteria from the 1970s onwards, most likely because of increased levels of anthropogenic phosphate and a reduction in rainfall. Our results showcase that the multi-proxy approach applied here provides an efficient way to track centennial-scale limnological, geochemical and microbial change, as influenced by hydroclimatic and anthropogenic forcing.

  17. Mesoscale and sub-mesoscale variability in phytoplankton community composition in the Sargasso Sea

    Science.gov (United States)

    Cotti-Rausch, Bridget E.; Lomas, Michael W.; Lachenmyer, Eric M.; Goldman, Emily A.; Bell, Douglas W.; Goldberg, Stacey R.; Richardson, Tammi L.

    2016-04-01

    The Sargasso Sea is a dynamic physical environment in which strong seasonal variability combines with forcing by mesoscale (~100 km) eddies. These drivers determine nutrient, light, and temperature regimes and, ultimately, the composition and productivity of the phytoplankton community. On four cruises (2011 and 2012; one eddy per cruise), we investigated links between water column structure and phytoplankton community composition in the Sargasso at a range of time and space scales. On all cruises, cyanobacteria (Prochlorococcus and Synechococcus) dominated the phytoplankton numerically, while haptophytes were the dominant eukaryotes (up to 60% of total chl-a). There were substantial effects of mesoscale and sub-mesoscale forcing on phytoplankton community composition in both spring and summer. Downwelling (in anticyclones) resulted in Prochlorococcus abundances that were 22-66% higher than at 'outside' stations. Upwelling (in cyclones) was associated with significantly higher abundances and POC biomass of nanoeukaryotes. In general, however, each eddy had its own unique characteristics. The center of anticyclone AC1 (spring 2011) had the lowest phytoplankton biomass (chl-a) of any eddy we studied and had lower nitrate+nitrite (N+N deep mixed layer, yet had relatively low nutrient concentrations. We observed a shift in the taxonomic composition of haptophytes between a coccolithophore-dominated community in C2 (98% of total haptophyte chl-a) and a non-coccolithophore community at BATS. In summer 2012, downwelling associated with anticyclone AC2 occurred at the edge of the eddy (not at the center), where AC2 interacted with a nearby cyclone. At the edge, we found significantly lower Synechococcus abundances and higher eukaryote chl-a compared to the center of AC2 and BATS. These along-transect nuances demonstrate the significance of small-scale perturbations that substantially alter phytoplankton community structure. Therefore, while seasonality in the North

  18. Phytoplankton community and environmental correlates in a coastal upwelling zone along western Taiwan Strait

    Science.gov (United States)

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

    2016-02-01

    Upwelling system in western Taiwan Strait is important for facilitating the fishery production. This study investigated hydro-chemical properties, phytoplankton biomass, phytoplankton species composition, three-dimensional (horizontal, vertical and transect) distribution of phytoplankton abundance, as well as phytoplankton annual variation and the correlation of phytoplankton community with the upwelling of underlying current and nutrients according to samples of Fujian-Guangdong coastal upwelling zone in western Taiwan Strait from August 27 to September 8, 2009. The results manifest that the nutrient-rich cold and high salinity current on the continental shelf of South China Sea upwells to the Fujian-Guangdong coastal waters through Taiwan Bank and the surging strength to surface is weak while strong at 30-m layer. The thermohaline center of coastal upwelling shifts to the east of Dongshan Island and expanded to offshore waters in comparison with previous records. A total of 137 phytoplankton species belonging to 59 genera in 4 phyla are identified excluding the unidentified species. Diatom is the first major group and followed by dinoflagellate. Cyanobacteria mainly composed by three Trichodesmium species account for a certain proportions, while Chrysophyta are only found in offshore waters. The dominant species include Thalassionema nitzschioides, Pseudo-nitzschia pungens, Thalassionema frauenfeldii, Pseudo-nitzschia delicatissima, Rhizosolenia styliformis, Chaetoceros curvisetus, Diplopsalis lenticula and Trichodesmium thiebautii. Phytoplankton community mainly consists of eurythermal and eurytopic species, followed by warm-water species, tropic high-salinity species and oceanic eurythermic species in order. Phytoplankton abundance ranges from 1.00 × 102 ind./L ~ 437.22 × 102 ind./L with an average of 47.36 × 102 ind./L. For vertical distribution, maximum abundance is found at 30 m-depth and the surface comes second. Besides, the abundance below 30 m

  19. Maixi River estuary to the Baihua Reservoir in the Maotiao River catchment: phytoplankton community and environmental factors

    Institute of Scientific and Technical Information of China (English)

    LI Qiuhua; CHEN Lili; CHEN Fengfeng; GAO Tingjin; LI Xiaofeng; LIU Songping; LI Cunxiong

    2013-01-01

    Phytoplankton and environmental variables were measured monthly from July 2009 to August 2011 in the Maixi River from the estuary to Baihua Reservoir in the Maotiao River catchment,southwestern China,to understand phytoplankton community structure and environmental factors.The relationship between phytoplankton community structure and environmental factors including hydrological,meteorological,physical,and chemical variables were explored using multivariate analysis.A total of 81taxa of phytoplankton were identified,which were mainly composed of chlorophyta,bacillariophyta,and cyanobacteria.The phytoplankton community was dominated by Pseudanabaena limnetica during summer and fall and by Cyclotella meneghiniana during winter and spring.The abundance of phytoplankton ranged from 0.24×104 cells/L to 33.45×i06 cells/L,with the minimum occurring during February 2010 and the maximum during July 2009.The phytoplankton community was dominated mainly by cyanobacteria from April to September,and by bacillariophyta and pyrrophyta from October to March.Canonical correspondence analysis showed that temperature,pH values,and orthophosphate were the most important driving factors regulating the composition and dynamics of the phytoplankton community in the estuary.Cyanobacteria and euglenophyta abundance and biomass were affected mainly by temperature and pH values,while most chlorophyta and bacillariophyta were influenced by the concentrations of nutrients.

  20. Abundance, biomass and composition of spring ice algal and phytoplankton communities of the Laptev Sea (Arctic)

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Abundance, biomass and composition of the ice algal and phytoplankton communities were investigated in the southeastern Laptev Sea in spring 1999.Diatoms dominated the algal communities and pennate diatoms dominated the diatom population. 12 dominant algal species occurred within sea ice and underlying water column, including Fragilariopsis oceanica, F. cylindrus, Nitzschia frigida , N. promare, Achnanthes taeniata , Nitzschia neofrigida , Navicula pelagica , N. vanhoef fenii, N. septentrionalis, Melosira arctica , Clindrotheca closterium and Pyramimonas sp. The algal abundance of bottom 10 cm sea ice varied between 14.6 and 1562.2 × 104 cells l-1 with an average of 639.0 × 104cells l-1 , and the algal biomass ranged from 7.89 to 2093.5 μg C l-1 with an average of 886.9 μg C l-1 , which were generally one order of magnitude higher than those of sub-bottom ice and two orders of magnitude higher than those of underlying surface water. The integrated algal abundance and biomass of lowermost 20 cm ice column were averagely 7.7 and 12.2 times as those of upper 20 m water column, respectively, suggesting that the ice algae might play an important role in maintaining the coastal marine ecosystem before the thawing of sea ice. Ice algae influenced the phytoplankton community of the underlying water column.However, the "seeding" of ice algae for phytoplankton bloom was negligible because of the low phytoplankton biomass within the underlying water column.

  1. Ice cover extent drives phytoplankton and bacterial community structure in a large north-temperate lake: implications for a warming climate.

    Science.gov (United States)

    Beall, B F N; Twiss, M R; Smith, D E; Oyserman, B O; Rozmarynowycz, M J; Binding, C E; Bourbonniere, R A; Bullerjahn, G S; Palmer, M E; Reavie, E D; Waters, Lcdr M K; Woityra, Lcdr W C; McKay, R M L

    2016-06-01

    Mid-winter limnological surveys of Lake Erie captured extremes in ice extent ranging from expansive ice cover in 2010 and 2011 to nearly ice-free waters in 2012. Consistent with a warming climate, ice cover on the Great Lakes is in decline, thus the ice-free condition encountered may foreshadow the lakes future winter state. Here, we show that pronounced changes in annual ice cover are accompanied by equally important shifts in phytoplankton and bacterial community structure. Expansive ice cover supported phytoplankton blooms of filamentous diatoms. By comparison, ice free conditions promoted the growth of smaller sized cells that attained lower total biomass. We propose that isothermal mixing and elevated turbidity in the absence of ice cover resulted in light limitation of the phytoplankton during winter. Additional insights into microbial community dynamics were gleaned from short 16S rRNA tag (Itag) Illumina sequencing. UniFrac analysis of Itag sequences showed clear separation of microbial communities related to presence or absence of ice cover. Whereas the ecological implications of the changing bacterial community are unclear at this time, it is likely that the observed shift from a phytoplankton community dominated by filamentous diatoms to smaller cells will have far reaching ecosystem effects including food web disruptions.

  2. Phytoplankton community of Lake Baskandi anua, Cachar District, Assam, North East India – An ecological study

    Directory of Open Access Journals (Sweden)

    Devi M.B.

    2016-01-01

    Full Text Available Diversity, relative abundance and dominance of phytoplankton community of the Lake Baskandi anua, an oxbow lake of Assam, North east India were studied during December 2009 to November 2010. Chlorophyll content and biomass of phytoplankton along with physico-chemical properties of water of the lake were also estimated. The lake is covered with Hydrilla and other macrophytes like Eichhornia, Trapa, Altrnenthera, Polygonum, Ludwizia sp., etc. Seasonal fluctuations of 41 genera of phytoplankton, belonging to 5 groups (Chlorophyceae, Cyanobacteria, Bacillariophyceae, Euglenophyceae and Dinophyceae were encountered in the lake. Chlorophyceae was found to be highest in winter, Cyanobacteria and Euglena in monsoon and Bacillariophyceae in pre monsoon. According to Engelmann’s scale, Spirogyra indica was found eudominant followed by 10 dominant, 24 subdominant and 20 recedent species. Chlorophyll- a content of phytoplankton varied from 14.18 to 33.89 μg·L-1, during the study period. One way analysis of variance (ANOVA revealed significant seasonal variation in physico-chemical properties of water like Water temperature, pH, Conductivity, Dissolved oxygen, Free CO2, Total alkalinity, Calcium, Chloride, Nitrate and Ammonia. Relationship between phytoplankton group assemblage and environmental variables were explored by the ordination method CCA (Canonical Correspondence Analysis.

  3. Marine phytoplankton temperature versus growth responses from polar to tropical waters--outcome of a scientific community-wide study.

    Directory of Open Access Journals (Sweden)

    Philip W Boyd

    Full Text Available "It takes a village to finish (marine science these days" Paraphrased from Curtis Huttenhower (the Human Microbiome project The rapidity and complexity of climate change and its potential effects on ocean biota are challenging how ocean scientists conduct research. One way in which we can begin to better tackle these challenges is to conduct community-wide scientific studies. This study provides physiological datasets fundamental to understanding functional responses of phytoplankton growth rates to temperature. While physiological experiments are not new, our experiments were conducted in many laboratories using agreed upon protocols and 25 strains of eukaryotic and prokaryotic phytoplankton isolated across a wide range of marine environments from polar to tropical, and from nearshore waters to the open ocean. This community-wide approach provides both comprehensive and internally consistent datasets produced over considerably shorter time scales than conventional individual and often uncoordinated lab efforts. Such datasets can be used to parameterise global ocean model projections of environmental change and to provide initial insights into the magnitude of regional biogeographic change in ocean biota in the coming decades. Here, we compare our datasets with a compilation of literature data on phytoplankton growth responses to temperature. A comparison with prior published data suggests that the optimal temperatures of individual species and, to a lesser degree, thermal niches were similar across studies. However, a comparison of the maximum growth rate across studies revealed significant departures between this and previously collected datasets, which may be due to differences in the cultured isolates, temporal changes in the clonal isolates in cultures, and/or differences in culture conditions. Such methodological differences mean that using particular trait measurements from the prior literature might introduce unknown errors and bias into

  4. Spectral fluorometric characterization of phytoplankton community composition using the Algae Online Analyser.

    Science.gov (United States)

    Richardson, Tammi L; Lawrenz, Evelyn; Pinckney, James L; Guajardo, Rodney C; Walker, Elyse A; Paerl, Hans W; MacIntyre, Hugh L

    2010-04-01

    The utility of a multiple-fixed-wavelength spectral fluorometer, the Algae Online Analyser (AOA), as a means of quantifying phytoplankton biomass and community composition was tested using natural communities from two southeastern United States estuaries, North Inlet, South Carolina, and the Neuse River Estuary, North Carolina. Estimates of biomass (as chlorophyll a) were correlated with HPLC values and variations (usually over-estimates) were consistent with effects of light intensity and nutrient availability on fluorescence quenching. AOA estimates of taxonomic structure were consistent with those from HPLC-derived marker pigments by ChemTax, with both methods indicating domination by chromophytes and green algae in North Inlet and chromophytes and cyanobacteria in the Neuse. We recommend frequent calibration by discrete sample collection, and calibration with species representative of the region of interest. Overall, the AOA appears to be a useful tool for monitoring of phytoplankton community composition, especially as an early warning system for the detection of harmful algal blooms.

  5. Temperature affects the size-structure of phytoplankton communities in the ocean

    KAUST Repository

    López-Urrutia, Ángel

    2015-03-05

    The strong inverse correlation between resource availability and temperature in the ocean poses a challenge to determine the relative effect of these two variables on the size-structure of natural phytoplankton communities. Maranon et al (2012) compiled a dataset of concurrent temperature and resource level proxies that they claim disentangled the effect of temperature from that of resource supply. They concluded that the hypothesis that temperature per se plays a direct role in controlling phytoplankton size structure should be rejected. But our reanalysis of their data reaches a very different conclusion and suggests that they failed to separate the effects of temperature from the effects of resources. Although we obviously concur with Maranon et al (2012) in the long-known predominance of small phytoplankton cells under oligotrophic conditions, from our point of view this should not deter us from considering temperature as an important explanatory variable at a global scale since we show that, for the vast oligotrophic areas of the world\\'s oceans where chlorophyll concentrations are below <1 g L-1 temperature explains a high proportion of the variability in the size distribution of phytoplankton communities, a variability that can not be explained on the basis of the resource level proxies advocated by Maranon et al. (2012).

  6. Phytoplankton community structure in reservoirs of different trophic status, Northeast China

    Institute of Scientific and Technical Information of China (English)

    MA Chengxue; YU Hongxian

    2013-01-01

    The aim of this study was to determine the phytoplankton community structures of reservoirs of different trophic status,located in a cold region.Physical and chemical variables and the phytoplankton communities were investigated in two reservoirs (Xiquanyan Reservoir and Taoshan Reservoir) in Northeast China in 2009.The two reservoirs showed strong seasonal fluctuations in their physical and chemical composition.Results of the trophic status index indicated that Xiaquanyan Reservoir was mesotrophic,whilst Taoshan Reservoir was eutrophic.Diatoms were the dominant phytoplankton group in Xiquanyan Reservoir throughout all seasons of the study,while in Taoshan Reservoir,diatoms dominated in spring,and cyanobacteria dominated in summer and autumn.This difference was resulted from differences in local environmental factors,including nutrients and hydrology.This study suggests that in mesotrophic reservoirs,nutrients played a key role in controlling seasonal phytoplankton successions,whereas in eutrophic reservoirs water temperature was the key factor in a cold region.Notably,the dominant species in summer in the Taoshan Reservoir was Microcystis,which may produce toxins depending on the ambient conditions,and presenting a risk of local toxin contamination.

  7. Climate Change Effects on Iron Availability to Arctic Phytoplankton

    Science.gov (United States)

    Maldonado, Maria Teresa; Li, Jingxuan; Semeniuk, David; Schuback, Nina; Hoppe, Clara; AWI/UBC Collaboration

    2016-09-01

    Phytoplankton, unicellular algae, are responsible for 50% of earth's photosynthesis, and for a significant consumption of atmospheric CO2. Iron (Fe) is essential for phytoplankton, but is extremely depleted in seawater, limiting photosynthesis in 30% of the global ocean. Oceanic Fe bioavailability is determined by physical and chemical processes. The Arctic Ocean is experiencing the greatest decrease in seawater pH (termed ocean acidification). Simultaneously, ice retreat is promoting higher light intensity in Arctic Ocean. We investigated the effects of ocean acidification and high light on Fe availability to Arctic phytoplankton. Iron uptake rates by plankton, using the radionuclide 55Fe, were used as a proxy for Fe bioavailability. In an Arctic summer research cruise, we measured Fe uptake by two phytoplankton populations subjected to two light levels, as well as present CO2 levels (400ppm) or those expected by 2100 (1100 ppm). Our results demonstrated that high CO2 decreases Fe availability, while high light increases it, suggesting that future Fe bioavailability might be similar to present day. However, the detrimental effects of high CO2 were more pronounced in the plankton population exposed to higher seawater temperature. Future studies should investigate the interaction among light, CO2 and temperature on the Fe physiology of Arctic phytoplankton.

  8. Seasonal change of phytoplankton (spring vs. summer) in the southern Patagonian shelf

    Science.gov (United States)

    Gonçalves-Araujo, Rafael; de Souza, Márcio Silva; Mendes, Carlos Rafael Borges; Tavano, Virginia Maria; Garcia, Carlos A. E.

    2016-08-01

    As part of the Patagonian Experiment (PATEX) project two sequential seasons (spring/summer 2007-2008) were sampled in the southern Patagonian shelf, when physical-chemical-biological (phytoplankton) data were collected. Phytoplankton biomass and community composition were assessed through both microscopic and high-performance liquid chromatography/chemical taxonomy (HPLC/CHEMTAX) techniques and related to both in situ and satellite data at spatial and seasonal scales. Phytoplankton seasonal variation was clearly modulated by water column thermohaline structure and nutrient dynamics [mainly dissolved inorganic nitrogen (DIN) and silicate]. The spring phytoplankton community showed elevated biomass and was dominated by diatoms [mainly Corethron pennatum and small (bloom. In contrast, the phytoplankton community in summer presented lower biomass and was mainly dominated by haptophytes (primarily Emiliania huxleyi and Phaeocystis antarctica) and dinoflagellates, associated with shallower and well-stratified upper mixed layers with higher nutrient concentrations, likely due to lateral advection of nutrient-rich waters from the Malvinas Current. The gradual establishment of a strongly stratified and shallow UMLD as season progressed, was an important factor leading to the replacement of the spring diatom community by a dominance of calcifying organisms, as shown in remote sensing imagery and confirmed by microscopic examination. Furthermore, in spring, phaeopigments a (degradation products of chlorophyll a) relative to chlorophyll a, were twice that of summer, indicating the diatom bloom was under higher grazing pressure.

  9. Identification of ecological thresholds from variations in phytoplankton communities among lakes: contribution to the definition of environmental standards.

    Science.gov (United States)

    Roubeix, Vincent; Danis, Pierre-Alain; Feret, Thibaut; Baudoin, Jean-Marc

    2016-04-01

    In aquatic ecosystems, the identification of ecological thresholds may be useful for managers as it can help to diagnose ecosystem health and to identify key levers to enable the success of preservation and restoration measures. A recent statistical method, gradient forest, based on random forests, was used to detect thresholds of phytoplankton community change in lakes along different environmental gradients. It performs exploratory analyses of multivariate biological and environmental data to estimate the location and importance of community thresholds along gradients. The method was applied to a data set of 224 French lakes which were characterized by 29 environmental variables and the mean abundances of 196 phytoplankton species. Results showed the high importance of geographic variables for the prediction of species abundances at the scale of the study. A second analysis was performed on a subset of lakes defined by geographic thresholds and presenting a higher biological homogeneity. Community thresholds were identified for the most important physico-chemical variables including water transparency, total phosphorus, ammonia, nitrates, and dissolved organic carbon. Gradient forest appeared as a powerful method at a first exploratory step, to detect ecological thresholds at large spatial scale. The thresholds that were identified here must be reinforced by the separate analysis of other aquatic communities and may be used then to set protective environmental standards after consideration of natural variability among lakes.

  10. Impacts of climate change, land-use change and phosphorus reduction on phytoplankton in the River Thames (UK).

    Science.gov (United States)

    Bussi, Gianbattista; Whitehead, Paul G; Bowes, Michael J; Read, Daniel S; Prudhomme, Christel; Dadson, Simon J

    2016-12-01

    Potential increases of phytoplankton concentrations in river systems due to global warming and changing climate could pose a serious threat to the anthropogenic use of surface waters. Nevertheless, the extent of the effect of climatic alterations on phytoplankton concentrations in river systems has not yet been analysed in detail. In this study, we assess the impact of a change in precipitation and temperature on river phytoplankton concentration by means of a physically-based model. A scenario-neutral methodology has been employed to evaluate the effects of climate alterations on flow, phosphorus concentration and phytoplankton concentration of the River Thames (southern England). In particular, five groups of phytoplankton are considered, representing a range of size classes and pigment phenotypes, under three different land-use/land-management scenarios to assess their impact on phytoplankton population levels. The model results are evaluated within the framework of future climate projections, using the UK Climate Projections 09 (UKCP09) for the 2030s. The results of the model demonstrate that an increase in average phytoplankton concentration due to climate change is highly likely to occur, with the magnitude varying depending on the location along the River Thames. Cyanobacteria show significant increases under future climate change and land use change. An expansion of intensive agriculture accentuates the growth in phytoplankton, especially in the upper reaches of the River Thames. However, an optimal phosphorus removal mitigation strategy, which combines reduction of fertiliser application and phosphorus removal from wastewater, can help to reduce this increase in phytoplankton concentration, and in some cases, compensate for the effect of rising temperature.

  11. Eutrophication influence on phytoplankton community composition in three bays on the eastern Adriatic coast

    Directory of Open Access Journals (Sweden)

    Mia Bužančić

    2016-10-01

    Full Text Available This study shows the influence of eutrophication pressure on the phytoplankton community structure, abundance and biodiversity in the investigated bays with different hydromorphological features. Šibenik Bay is a highly stratified estuary of the karstic river Krka; Kaštela Bay is a semi-enclosed coastal bay, which is influenced by the relatively small river Jadro; and Mali Ston Bay is located at the Neretva River estuary, the largest river on the eastern part of the Adriatic Sea. All of the areas are affected by urban pressure, which is reflected in the trophic status of the waters. The greatest anthropogenic influence was found in Kaštela Bay while the lowest influence was found in Mali Ston Bay. In this study, the highest biomass concentration and maximum abundance of phytoplankton were recorded at the stations under the strongest anthropogenic influence. Those stations show a dominance of abundance compared to the biomass and a dominance of opportunistic species, which is reflected in the lower biodiversity of phytoplankton community. Diatoms were the most represented group of the phytoplankton community in all three bays, followed by the dinoflagellates. Diatoms that were highlighted as significant for the difference between the bays were Skeletonema marinoi in Šibenik Bay, Leptocylindrus minimus in Kaštela Bay and the genus Chaetoceros spp. in Mali Ston Bay. Dinoflagellates were more abundant at the stations under the strongest anthropogenic influence, and most significant were Prorocentrum triestinum in Kaštela Bay and Gymnodinium spp. in Šibenik Bay and Mali Ston Bay.

  12. Phytoplanktonic Community of Organically Polluted Tropical Reservoirs in Eastern India

    Institute of Scientific and Technical Information of China (English)

    SANJIB; Kumar; Das; DIBYENDU; Biswas; SUDIPTO; Roy

    2007-01-01

    Plankton communities of three reservoirs of India reflect the direct relationship with organic pollution. The assessment of water quality as highly or lowly organically polluted for the three water bodies has been achieved with help of algal community, which can be used as an indicator of organic pollution. Algal pollution indices according to Palmer[1] and Watanabe[2]and based on genus and species were used in rating water samples for high or low organic pollution. Among 26 genera of algae found in India, 20 most frequent and common genera were taken into account for indexing pollution status. Water quality index (WQI) on the basis of weighting and rating of the chemical parameter was also used to correlate the Palmer index with physicochemical parameters of the three reservoirs. Fig 5, Tab 3, Ref 29

  13. 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

    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......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 this area...... was studied at both the community and species level in experimental pH treatments within (pH 8.0, 7.7 and 7.4) and outside (pH 7.1) in situ pH. The growth rate of the phytoplankton community decreased during the experimental acidification from 0.50 ± 0.01 d-1 (SD) at pH 8.0 to 0.22 ± 0.01 d-1 at pH 7...

  14. Phytoplankton pigment patterns and community composition in the northern South China Sea during winter

    Science.gov (United States)

    Zhai, Hongchang; Ning, Xiuren; Tang, Xuexi; Hao, Qiang; Le, Fengfeng; Qiao, Jing

    2011-03-01

    Phytoplankton pigment patterns and community composition were investigated in the northern South China Sea using high-performance liquid chromatography and the CHEMTAX software from February 11 to 23, 2009. We recognized four different vertical distribution patterns of pigments: chlorophyll a (Chi a)-like type, divinyl chlorophyll a (DV Chi a) type, even distribution type, and surface type. The average value of ratios of accessory photo-protective pigments (APP) to accessory photo-synthetic pigments was 0.89±0.63 in the upper 50 m and 0.16±0.06 below 50 m depth. With increasing depth, APP decreased and photo-synthetically active radiation was attenuated. There was an obvious succession in the phytoplankton community from inshore to the open sea. Diatoms were dominant in the inshore region, while pelagophytes, Prochlorococcus, cyanobacteria and prymnesiophytes were dominant in the open sea. The vertical distribution of phytoplankton also differed greatly from inshore to the open sea. In the coastal and shelf region, diatoms were important components in the whole water column. Cyanobacteria also had a high abundance at the Subsurface Chlorophyll a Maxima (SCM) in the shelf region. In the slope and open sea, Prochlorococcus and cyanobacteria were important groups above the SCM, while pelagophytes dominated below the SCM.

  15. Phytoplankton pigment patterns and community composition in the northern South China Sea during winter

    Institute of Scientific and Technical Information of China (English)

    ZHAI Hongchang; NING Xiuren; TANG Xuexi; HAO Qiang; LE Fengfeng; QIAO Jing

    2011-01-01

    Phytoplankton pigment patterns and community composition were investigated in the northern South China Sea using high-performance liquid chromatography and the CHEMTAX software from February 11 to 23, 2009. We recognized four different vertical distribution patterns of pigments: chlorophyll a (Chl a)-like type, divinyl chlorophyll a (DV Chl a) type, even distribution type, and surface type. The average value of ratios of accessory photo-protective pigments (APP) to accessory photo-synthetic pigments was 0.89±0.63 in the upper 50 m and 0.16±0.06 below 50 m depth. With increasing depth, APP decreased and photo-synthetically active radiation was attenuated. There was an obvious succession in the phytoplankton community from inshore to the open sea. Diatoms were dominant in the inshore region, while pelagophytes, Prochlorococcus,cyanobacteria and prymnesiophytes were dominant in the open sea. The vertical distribution of phytoplankton also differed greatly from inshore to the open sea. In the coastal and shelf region,diatoms were important components in the whole water column. Cyanobacteria also had a high abundance at the Subsurface Chlorophyll a Maxima (SCM) in the shelf region. In the slope and open sea, Prochlorococcus and cyanobacteria were important groups above the SCM, while pelagophytes dominated below the SCM.

  16. Modelling climate change, land-use change and phosphorus reduction impacts on phytoplankton in the River Thames (UK)

    Science.gov (United States)

    Bussi, Gianbattista; Whitehead, Paul; Dadson, Simon

    2016-04-01

    In this study, we assess the impact of changes in precipitation and temperature on the phytoplankton concentration of the River Thames (UK) by means of a physically-based model. A scenario-neutral approach was employed to evaluate the effects of climate variability on flow, phosphorus concentration and phytoplankton concentration. In particular, the impact of uniform changes in precipitation and temperature on five groups of phytoplankton (diatoms and large chlorophytes, other chlorophytes, picoalgae, Microcystis-like cyanobacteria and other cyanobacteria) was assessed under three different land-use/land-management scenarios (1 - current land use and phosphorus reduction practices; 2 - expansion of agricultural land and current phosphorus reduction practices; 3 - expansion of agricultural land and optimal phosphorus reduction practices). The model results were assessed within the framework of future climate projections, using the UK Climate Projections 09 (UKCP09) for the 2030s. The results of the model demonstrate that an increase in average phytoplankton concentration due to climate change is highly likely to occur, and its magnitude varies depending on the river reach. Cyanobacteria show significant increases under future climate change and land-use change. An expansion of intensive agriculture accentuates the growth in phytoplankton, especially in the upper reaches of the River Thames. However, an optimal phosphorus removal mitigation strategy, which combines reduction of fertiliser application and phosphorus removal from wastewater, can help to reduce this increase in phytoplankton concentration, and in some cases, compensate for the effect of rising temperature.

  17. A universal driver of macroevolutionary change in the size of marine phytoplankton over the Cenozoic.

    Science.gov (United States)

    Finkel, Z V; Sebbo, J; Feist-Burkhardt, S; Irwin, A J; Katz, M E; Schofield, O M E; Young, J R; Falkowski, P G

    2007-12-18

    The size structure of phytoplankton assemblages strongly influences energy transfer through the food web and carbon cycling in the ocean. We determined the macroevolutionary trajectory in the median size of dinoflagellate cysts to compare with the macroevolutionary size change in other plankton groups. We found the median size of the dinoflagellate cysts generally decreases through the Cenozoic. Diatoms exhibit an extremely similar pattern in their median size over time, even though species diversity of the two groups has opposing trends, indicating that the macroevolutionary size change is an active response to selection pressure rather than a passive response to changes in diversity. The changes in the median size of dinoflagellate cysts are highly correlated with both deep ocean temperatures and the thermal gradient between the surface and deep waters, indicating the magnitude and frequency of nutrient availability may have acted as a selective factor in the macroevolution of cell size in the plankton. Our results suggest that climate, because it affects stratification in the ocean, is a universal abiotic driver that has been responsible for macroevolutionary changes in the size structure of marine planktonic communities over the past 65 million years of Earth's history.

  18. Temporal dynamics of phytoplankton communities in a semi-enclosed mariculture pond and their responses to environmental factors

    Institute of Scientific and Technical Information of China (English)

    许恒龙; MIN; Gi-Sik; CHOI; Joong-Ki; AL-RASHEID; Khaled; A.; S.; 林晓凤; 朱明壮

    2010-01-01

    Variations in physical-chemical factors, species composition, abundance and biomass of nano-and micro-phytoplankton assemblages, as well as their responses to environmental factors, were investigated over a complete cycle (6 months) in a semi-enclosed shrimp-farming pond near Qingdao, northern China. The aim was to establish the temporal patterns of phytoplankton communities and to evaluate protists as suitable bioindicators to water quality in mariculture systems. A total of 34 taxa with nine dominant spec...

  19. The effects of spring-neap tide on the phytoplankton community development in the Jiaozhou Bay,China

    Institute of Scientific and Technical Information of China (English)

    LIU Dongyan; SUN Jun; LIU Zhe; CHEN Hongtao; WEI Hao; ZHANG Jing

    2004-01-01

    The development of the phytoplankton community was studied in the Jiaozhou Bay during the spring to neap tide in August 2001, through three cruises and a 15 d continuous observation. This investigation indicates that diatom cell abundance increased sharply following the end of a spring tide, from 9 cells/cm3 to a peak of 94 cells/cm3. The dominant species composition and abundance show a quick species sequence from spring to neap tide, and the dominant species at the start phase is Skeletomena costatum, then changes to Chaetoceros curvisetus, finally it changes to Eucampia zodiacus. Silicate concentration increases during spring tide, as a result of nutrient replenishment from the water-sediment interface, its initial average concentration in neap tide is 1.39 μmol/dm3 and reached the peak average concentration of 8.40 μmol/dm3 in spring tide. But the nitrogen concentration dropped due to dilution by the low nitrogen seawater from the Huanghai Sea, its initial average concentration in neap tide is 67 μmol/dm3 and decreased to the average concentration of 54 μmol/dm3 in spring tide. The degree of silicon limitation was decreased and phytoplankton, especially diatoms, responds immediately after nutrient replenishment in the water column. Skeletonmea costatum, as one of the dominant species in the Jiaozhou Bay, shows a quicker response to nutrient availability than Eucampia zodiacus and Chaetoceros curvisetus. It is proposed that dominant species composition and water column stability synchronously determine the development of phytoplankton summer blooms in the Jiaozhou bay.

  20. The community composition and production of phytoplankton in fish pens of Cape Bolinao, Pangasinan: a field study.

    Science.gov (United States)

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

    2004-11-01

    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.

  1. The community composition and production of phytoplankton in fish pens of Cape Bolinao, Pangasinan: a field study

    Energy Technology Data Exchange (ETDEWEB)

    Yap, Leni G. [University of the Philippines in the Visayas, Tacloban College, Tacloban City, Leyte 6500 (Philippines)]. E-mail: leni@upmsi.ph; Azanza, Rhodora V. [Marine Science Institute, University of the Philippines, Diliman, Quezon City 1101 (Philippines)]. E-mail: rhod@upmsi.ph; Talaue-McManus, Liana [Division of Marine Affairs, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149 (United States)]. E-mail: lmcmanus@rsmas.miami.edu

    2004-11-01

    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{sup 4} cells/l and even as high as 10{sup 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{sup 5} cells/l), during the dry season of the same year and a Prorocentrum minimum bloom (4.7 x 10{sup 5} cells/l), which accompanied a massive fish kill during January 2002.

  2. Micro-phytoplankton community structure in the coastal upwelling zone off Concepción (central Chile): Annual and inter-annual fluctuations in a highly dynamic environment

    Science.gov (United States)

    Anabalón, V.; Morales, C. E.; González, H. E.; Menschel, E.; Schneider, W.; Hormazabal, S.; Valencia, L.; Escribano, R.

    2016-12-01

    An intensification of upwelling-favorable winds in recent decades has been detected in some of the main eastern boundary current systems, especially at higher latitudes, but the response of coastal phytoplankton communities in the Humboldt Current System (HCS) remains unknown. At higher latitudes in the HCS (35-40°S), strong seasonality in wind-driven upwelling during spring-summer coincides with an annual increase in coastal chlorophyll-a and primary production, and a dominance of micro-phytoplankton. In order to understand the effects of potential upwelling intensification on the micro-phytoplankton community in this region, annual and inter-annual variability in its structure (total and taxa-specific abundance and biomass) and its association with oceanographic fluctuations were analyzed using in situ time series data (2002-2009) from a shelf station off Concepcion (36.5°S). At the annual scale, total mean abundance and biomass, attributed to a few dominant diatom taxa, were at least one order of magnitude greater during spring-summer than autumn-winter, in association with changes in upwelling and surface salinity and temperature, whereas macro-nutrient concentrations remained relatively high all the year. At the inter-annual scale, total abundance and biomass decreased during the upwelling season of the 2006-2009 period compared with the 2002-2006 period, notably due to lower abundances of Skeletonema and Leptocylindrus, but the relative dominance of a few taxa was maintained. The 2006-2009 period was characterized by higher upwelling intensity, colder and higher salinity waters, and changes in nutrient concentrations and ratios compared with the first period. The inter-annual changes in the micro-phytoplankton community were mostly associated with changes in surface salinity and temperature (changes in upwelling intensity) but also with changes in Si/N and N/P, which relate to other land-derived processes.

  3. Long Term Effect of Cyprinid Fishes on Phytoplankton and Zooplankton Communities in a Shallow Water Protection Reservoir

    Science.gov (United States)

    Mátyás, Kálmán; Korponai, János; Tátrai, István; Paulovits, Gábor

    2004-01-01

    The effects of fish kill and different fish stocks on the phytoplankton and zooplankton dynamics were studied in a shallow hypertrophic reservoir system. When fish stock was below 100 kg ha-1, nutrient availability was not the main limiting factor for growth of phytoplankton. Consequently top-down forces controlled phytoplankton. In the years with high fish stock (>100 kg ha-1) the bottom-up forces dominated as nutrient availability was the main limiting factor for growth of phytoplankton. We can conclude that significant water quality improvement can be achieved in the reservoir system by decreasing fish stock below 100 kg ha-1. Although clear-water phase could be stabilised temporary by macrophytes, stabilisation of good water quality requires continuous regulation of fish community. (

  4. Response of phytoplankton community structure and size-fractionated Chlorophyll a in an upwelling simulation experiment in the western South China Sea

    Science.gov (United States)

    Cui, Dongyang; Wang, Jiangtao; Tan, Liju

    2016-10-01

    The South China Sea (SCS), which is the largest marginal sea in the western tropical Pacific, plays an important role in regional climate change. However, the research on the phytoplankton community structure (PCS) response to the upwelling remains inadequate. In January 2014, the upwelling simulation experiment was performed in the western SCS. Results indicate that the nutrient-rich bottom water not only increased the total Chlorophyll a (Chl a) concentrations, but would potentially altered the PCS. Due to new nutrients added, microphytoplankton had more sensitivity response to nutrient uptake than other phytoplankton groups. The variation of nutrients induced by formation, weakening and disappearance of upwelling resulted in phytoplankton species succession from cyanophyta to bacillariophyta. It may be the leading factor of the changes in PCS and size-fractionated Chl a. The initial concentration of DIP less than 0.1 μmolL-1 could not sustain the phytoplankton growth. This indicates that phosphorus may be the limiting factor in the western SCS.

  5. Spatiotemporal variations in phytoplankton biomass and community structure in a meridional transect of the East/Japan Sea

    Science.gov (United States)

    Kwak, J. H.; Kang, C. K.; Kang, H.

    2015-12-01

    To better understand the variations in phytoplankton biomass and community composition associated with water-column structure and environmental conditions in the East/Japan Sea (EJS), three cruses were carried out along a meridional transect in May 2007 (spring), July 2009 (summer), and October 2012 (fall). The subpolar front (SPF) was formed between warm and cold water mass (37-40 °N). Chlorophyll a concentration and phytoplankton community composition were studied using HPLC pigment and CHEMTAX analysis and the results showed no significant differences between warm and cold water masses. These results reject our initial hypothesis that different water masses between southern and northern parts of the EJS may lead to different phytoplankton community structure. During the study periods, isotherm layers (≤ 12 °C) fluctuated over 50 m depth between warm and cold water masses on the basis of the SPF. In contrast, the nitracline (i.e. 2.5 μM nitrate isopleths) depth was recorded within the limited depths ranged 20-40 m, 30-50 m, and 40-60 m in spring, summer, and fall, respectively. The chlorophyll a concentrations at the subsurface chlorophyll maxima (SCM) in spring and summer (356 ± 233 and 270 ± 182 ng L-1, respectively) were significantly higher than those in fall (117 ± 89 ng L-1). The relative contributions of phytoplankton groups to total chlorophyll a concentration reflected phytoplankton community composition in the SCM layer with showing a dominance of diatoms (58 ± 19, 48 ± 11, and 30 ± 20 % in spring, summer, and fall, respectively). High contribution of diatoms to total biomass may enhance the efficiency of biological pump in the EJS. In addition, canonical correspondence analysis revealed a clear distribution of phytoplankton groups associated with temperature and nutrient concentration which mean prevalence of vertical variation. Finally, our findings suggested that phytoplankton biomass and groups are regulated by surface mixed layer depth

  6. 连云港田湾核电站邻近海域网采浮游植物群落的变化%Changes of Net-collected Phytoplankton Community in Sea Area Adjacent to Tianwan Nuclear Power Plant of Lianyungang

    Institute of Scientific and Technical Information of China (English)

    万晔; 杨华; 刘吉堂; 马润美; 程祥圣; 王超; 葛修军; 朱旭宇

    2014-01-01

    The net-collected phytoplankton in the sea area adjacent to Tianwan Nuclear Power Plant of Lianyungang was in -vestigated in May 2011, August 2012 and August 2013, and their species composition , annual changes and relations with environ-mental factors were studied .A total of 160 phytoplankton species in 8 phyla were identified , including 113 diatom species , 31 dino-flagellate species and other 18 taxonomic ( Chlorophyta , Chrysophyta , Euglenophyta , Cyanophyt , Xanthophyta and Cryptophyta ) species.Dominant species consisted of 7 diatom species and 1 dinoflagellate species.The correlation analysis showed that the cell density of phytoplankton was significantly positively correlated with phosphate concentration , nitrite concentration and temperature , and was negatively correlated with salinity .Since the year 1983, the structure of nutritive salt in the studied sea area has changed obviously:the concentration of phosphate sharply increased from 0.70μmol/L in 1983 to 29.38μmol/L in 2013;the ratio of N to P also increased from 4.9∶1 in 1983 to 53.7∶1 in 2013.Meanwhile, the structure of phytoplankton community has also experienced an obvious variation since 1983, and the dominant species Chaetoceros spp.was gradually replaced by Skeletonema spp.%根据2011年5月、2012年8月和2013年8月在连云港田湾核电站邻近海域进行的调查,研究了网采浮游植物的种类组成、年际变化及其与环境因子的关系。该海域共鉴定出浮游植物8门160种,其中硅藻种类数最多(113种),甲藻其次(31种),蓝藻、金藻、黄藻、绿藻、裸藻和隐藻偶有检出。优势种共8种,包括7种硅藻和1种甲藻。相关性分析表明,浮游植物细胞丰度与磷酸盐、亚硝酸盐和温度呈显著正相关,与盐度呈负相关。结合历史数据分析表明,近30年来核电站邻近海域营养盐结构已发生较大变化,表现为硝酸盐浓度急剧升高,由1983年的0.70

  7. Seasonal variations in the phytoplankton community and the relationship between environmental factors of the sea around Xiaoheishan Island in China

    Science.gov (United States)

    Zhang, Zhipeng; Tang, Xuexi; Tang, Haitian; Song, Jingjing; Zhou, Jian; Liu, Hongjun; Wang, Qixiang

    2017-01-01

    Seasonal variations in the phytoplankton community and the relationship between environmental factors of the sea area around Xiaoheishan Island are investigated in the present study. Xiaoheishan Island is located at 37°58'14″N and 120°38'46″E in Shandong Province, China. A total of 65 species of phytoplankton belonging to three phyla and 27 genera were identified, with Bacillariophyta having the largest number of species. The annual average chlorophyll a concentration for this area was 3.11 μg/L, and there occurs a Skeletonema costatum bloom in winter. The Shannon-Weaver indexes (log2) of the phytoplankton from all stations were higher than 1, and the Pielou indexes were all higher than 0.3. The results of the canonical correspondence analysis (CCA) indicated that water temperature, PO 4 3- and Cu were the environmental factors that had the greatest influence on the distribution of the phytoplankton community throughout the entire year. Although the concentration of heavy metal is well up to the state standards of the first grade of China (GB 3097-1997), these metals still have an impact on the phytoplankton community from this area.

  8. Interactive Effect of UVR and Phosphorus on the Coastal Phytoplankton Community of the Western Mediterranean Sea: Unravelling Eco-Physiological Mechanisms.

    Directory of Open Access Journals (Sweden)

    Presentación Carrillo

    Full Text Available Some of the most important effects of global change on coastal marine systems include increasing nutrient inputs and higher levels of ultraviolet radiation (UVR, 280-400 nm, which could affect primary producers, a key trophic link to the functioning of marine food webs. However, interactive effects of both factors on the phytoplankton community have not been assessed for the Mediterranean Sea. An in situ factorial experiment, with two levels of ultraviolet solar radiation (UVR+PAR vs. PAR and nutrients (control vs. P-enriched, was performed to evaluate single and UVR×P effects on metabolic, enzymatic, stoichiometric and structural phytoplanktonic variables. While most phytoplankton variables were not affected by UVR, dissolved phosphatase (APAEX and algal P content increased in the presence of UVR, which was interpreted as an acclimation mechanism of algae to oligotrophic marine waters. Synergistic UVR×P interactive effects were positive on photosynthetic variables (i.e., maximal electron transport rate, ETRmax, but negative on primary production and phytoplankton biomass because the pulse of P unmasked the inhibitory effect of UVR. This unmasking effect might be related to greater photodamage caused by an excess of electron flux after a P pulse (higher ETRmax without an efficient release of carbon as the mechanism to dissipate the reducing power of photosynthetic electron transport.

  9. The role of deep convection on the dynamics of the North Atlantic phytoplankton community

    DEFF Research Database (Denmark)

    Lindemann, Christian

    In recent years observations of a significant winter phytoplankton stock and blooms in the absence of stratification have challenged the classical picture of phytoplankton dynamics in the North Atlantic. To explain phytoplankton winter survival, it has been suggested that deep convection can...... convective motion as such. Due to the coupling of deep convection and phytoplankton winter survival in the north Atlantic this can lead to an underestimation of winter phytoplankton biomass. As a first step to improve the winter phytoplankton representation, a simple parameterization assuming average mixed...

  10. Effect of Chemical and Physical Properties of River Water in Shatt Al-Hilla on Phytoplankton Communities

    Directory of Open Access Journals (Sweden)

    Fikrat M. Hassan

    2008-01-01

    Full Text Available This paper aims to study the chemical and physical properties in the ecological system of Shatt Al-Hilla in Babylon Governorate in Iraq and its effect on phytoplankton population. In this context, several limnological parameters were evaluated during the period from December 2003 through November 2004 from four sampling stations sited along Shatt Al-Hilla. The physical parameters included: temperature, turbidity and electrical conductivity. The chemical parameters included: pH, alkalinity dissolved oxygen, total hardness and the concentrations of nitrite, nitrate, phosphate and sulphate. A total of 154 species were recorded. Ninety-seven species of the total belong to Bacillariophyceae, 37 species belong to Chlorophyceae, 13 species to Cyanophyceae, 5 species to Chrysophyceae, and 2 species to Euglenophyceae. Bimodal variation of phytoplankton was observed. Five genus of phytoplankton were the highest number of species ( Nitzschia, Navicula, Gomphonema, Cymbella and Scendesmus. Some species was occurred continuously during study period such as, Cyclotella ocellata, Cyclotella meneghiniana, Aulacoseria distans, and Gomphonema abbreviatum. The phytoplankton communities at all sampling sites showed a clear seasonal variation in phytoplankton cell number. However, no significant correlation between total cell number of phytoplankton and nutrient concentration was observed. The study was revealed the city sewage discharge, agriculture and urban run-off were affecting the water quality of Shatt Al-Hilla.

  11. Phytoplankton community characteristics in the coastal waters of the southeastern Arabian Sea Phytoplankton community characteristics in the coastal waters of the southeastern Arabian Sea

    Institute of Scientific and Technical Information of China (English)

    MINU P; SHAJU S S; MUHAMED ASHRAF P; MEENAKUMARI B

    2014-01-01

    Remote sensing applications are important in the fisheries sector and efforts were on to improve the predic-tions of potential fishing zones using ocean color. The present study was aimed to investigate the phyto-plankton dynamics and their absorption properties in the coastal waters of the southeastern Arabian Sea in different seasons during the year 2010 to 2011. The region exhibited 73 genera of phytoplankton from 19 orders and 41 families. The numerical abundance of phytoplankton varied from 14.235×103 to 55.075×106 cells/L. Centric diatoms dominated in the region and the largest family identified was Thalassiosiraceae with main genera asSkeletonemaspp.,Planktionellaspp.andThalassiosiraspp. Annual variations in abun-dance of phytoplankton showed a typical one-peak cycle, with the highest recorded during premonsoon season and the lowest during monsoon season. The species diversity index of phytoplankton exhibited low diversity during monsoon season. Phytoplankton with pigments Chlorophylla, Chlorophyllb, Chlorophyll c, peridinin, diadinoxanthin, fucoxanthin,β-carotene and phycoerythrobilin dominated in these waters. The knowledge on phytoplankton dynamics in coastal waters of the southeastern Arabian Sea forms a key parameter in bio-optical models of pigments and productivity and for the interpretation of remotely sensed ocean color data.

  12. Iron released from ilmenite mineral sustains a phytoplankton community in microcosms

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, C.E.G.; Velip, D.; Mourya, B.S.; Shaikh, S.; Das, A.; LokaBharathi, P.A.

    ilmenite had significantly higher phytoplankton growth compared with controls containing no ilmenite or those containing only ferrous sulfate. Phytoplankton cell numbers in the ilmenite-supplemented treatment were 20X higher than in controls. The later...

  13. Physical-biological coupling in the Amundsen Sea, Antarctica: Influence of physical factors on phytoplankton community structure and biomass

    Science.gov (United States)

    Lee, Youngju; Yang, Eun Jin; Park, Jisoo; Jung, Jinyoung; Kim, Tae Wan; Lee, SangHoon

    2016-11-01

    To understand the spatial distribution of phytoplankton communities in various habitats in the Amundsen Sea, western Antarctica, a field survey was conducted at 15 stations during the austral summer, from December 2013 to January 2014. Water samples were analyzed by microscopy. We found high phytoplankton abundance and biomass in the Amundsen Sea polynya (ASP). Their strong positive correlation with water temperature suggests that phytoplankton biomass accumulated in the surface layer of the stratified polynya. In the ASP, the predominant phytoplankton species was Phaeocystis antarctica, while diatoms formed a major group in the sea ice zone, especially Fragilariopsis spp., Chaetoceros spp., and Proboscia spp. Although this large diatom abundance sharply decreased just off the marginal sea ice zone, weakly silicified diatoms, due to their high buoyancy, were distributed at almost all stations on the continental shelf. Dictyocha speculum appeared to favor the area between the marginal sea ice zone and the ASP in contrast to cryptophytes and picophytoplankton, whose abundance was higher in the area between the continental shelf and the open ocean of Amundsen Sea. Several environmental factors were found to affect the spatial variation of phytoplankton species, but the community structure appeared to be controlled mainly by the seawater density related to sea-ice melting and water circulation in the Amundsen Sea.

  14. Spatial variability in phytoplankton community structure along the eastern Arabian Sea during the onset of south-west monsoon

    Science.gov (United States)

    Ahmed, Ayaz; Kurian, Siby; Gauns, Mangesh; Chndrasekhararao, A. V.; Mulla, Amara; Naik, Bhagyashri; Naik, Hema; Naqvi, S. W. A.

    2016-05-01

    The Arabian Sea experiences moderate to weak upwelling along the south-west coast of India, which subsequently propagates towards the north. This causes variation in plankton community composition, which is addressed in the present study. Here we report the spatial variations in distribution of phytoplankton groups along the north-south transect in the eastern Arabian Sea based on marker pigments supported with flow-cytometric and microscopic analyses. 15 phytoplankton pigments were identified using High-performance liquid chromatography (HPLC) and the chemotaxonomic software (CHEMTAX) analysis associated these to seven major group of phytoplankton. The phytoplankton biomass, chlorophyll a (Chl a) was higher in southern stations with dominance of fucoxanthin whereas, divinyl chlorophyll a (divinyl Chl a), marker pigment of Prochlorococcus was present only in the northern region. Microscopic observation revealed the dominance of larger forms; diatoms (Chaetoceros coarctatum and Nitzschia sp.) and dinoflagellates (Scrippsiella sp., Oxytoxum nanum and Oxytoxum sp.) in the southern region. Furthermore, a study of plankton size distribution showed dominance of picoplankton (fpico) followed by nanoplankton (fnano) along the northern stations with comparatively higher microplankton (fmicro) in the south. This study clearly showed the influence of different environmental conditions on the phytoplankton community as reflected in dominance of diatoms in the southern (south of 12 °N) and that of picoplankton in the northern (north of 12 °N) region.

  15. Linking phytoplankton community size composition with temperature, plankton food web structure and sea–air CO2 flux

    DEFF Research Database (Denmark)

    Hilligsøe, Karen Marie; Richardson, Katherine; Bendtsen, Jørgen

    2011-01-01

    Data collected at open water stations (depth>400m) in all major ocean basins in 2006–2008 are used to examine the relationship between the size structure of the phytoplankton community (determined by size fractionated chlorophyll filtration), temperature and inorganic nutrient availability. A sig...

  16. Investigation on the occurrence and significance of cyclic adenosine 3':5'-monophosphate in phytoplankton and natural aquatic communities

    Energy Technology Data Exchange (ETDEWEB)

    Francko, D.A.

    1980-01-01

    This study is an investigation into the occurrence and potential functions of cyclic adenosine 3':5'-monophosphate (cAMP), a potent and ubiquitous metabolic regulatory molecule in heterotrophic organisms, in phytoplankton and in natural aquatic communities. Laboratory-cultured phytoplankton were grown under both optimal and suboptimal nutrient regimes under constant temperature and illumination regimes. Cellular and extracellular cAMP production, characterized by a number of biochemical techniques, was correlated with growth rate dynamics, chlorophyll a synthesis, /sup 14/C-bicarbonate uptake, alkaline phosphatase activity, and heterocyst formation. The blue-green alga Anabaena flos-aquae was used as a model system in the examination of these metabolic variables. Additionally, this alga was used to test the effects of perturbation of cAMP levels on the aforementioned metabolic variables. Investigations on the occurrence and seasonal dynamics of cAMP in aquatic systems were conducted on Lawrence Lake, a hardwater oligotrophic lake, and on Wintergreen Lake, a hardwater hypereutrophic lake, both in southwestern Michigan. Putative cAMP from both systems was characterized by several biochemical techniques. Weekly sampling of particulate and dissolved cAMP in the epilimnia of both lakes was correlated with data on the rates of primary productivity, alkaline phosphatase activity, chlorophyll a synthesis and changes in phytoplankton community structure.

  17. Physical-Biological Coupling in the Western South China Sea: The Response of Phytoplankton Community to a Mesoscale Cyclonic Eddy.

    Directory of Open Access Journals (Sweden)

    Lei Wang

    Full Text Available It is widely recognized that the mesoscale eddies play an important part in the biogeochemical cycle in ocean ecosystem, especially in the oligotrophic tropical zones. So here a heterogeneous cyclonic eddy in its flourishing stage was detected using remote sensing and in situ biogeochemical observation in the western South China Sea (SCS in early September, 2007. The high-performance liquid chromatography method was used to identify the photosynthetic pigments. And the CHEMical TAXonomy (CHEMTAX was applied to calculate the contribution of nine phytoplankton groups to the total chlorophyll a (TChl a biomass. The deep chlorophyll a maximum layer (DCML was raised to form a dome structure in the eddy center while there was no distinct enhancement for TChl a biomass. The integrated TChl a concentration in the upper 100 m water column was also constant from the eddy center to the surrounding water outside the eddy. However the TChl a biomass in the surface layer (at 5 m in the eddy center was promoted 2.6-fold compared to the biomass outside the eddy (p < 0.001. Thus, the slight enhancement of TChl a biomass of euphotic zone integration within the eddy was mainly from the phytoplankton in the upper mixed zone rather than the DCML. The phytoplankton community was primarily contributed by diatoms, prasinophytes, and Synechococcus at the DCML within the eddy, while less was contributed by haptophytes_8 and Prochlorococcus. The TChl a biomass for most of the phytoplankton groups increased at the surface layer in the eddy center under the effect of nutrient pumping. The doming isopycnal within the eddy supplied nutrients gently into the upper mixing layer, and there was remarkable enhancement in phytoplankton biomass at the surface layer with 10.5% TChl a biomass of water column in eddy center and 3.7% at reference stations. So the slight increasing in the water column integrated phytoplankton biomass might be attributed to the stimulated phytoplankton

  18. Characteristics of Phytoplankton Community Structure During and After a Bloom of the Dinoflagellate Scrippsiella trochoidea by HPLC Pigment Analysis

    Institute of Scientific and Technical Information of China (English)

    WONG Chun-kwan; WONG Chong-kim

    2009-01-01

    A bloom of the dinoflagellate Scrippsiella trochoidea was detected for the first time in inner Tolo Harbor, Hong Kong in 2000. Water samples were collected at eight stations along a transect passing through a red tide patch for microscopic analysis of phytoplankton composition and high-performance liquid chromatography (HPLC) analysis of phytoplankton pigments. During the bloom, the density of dinoflagellates was 1.1×106 cells L-1 within the patch and 8.6×105 cells L-1 outside the patch where the phyto-plankton community was dominated by diatoms. After the bloom the S. trochoidea began to decrease in density and was replaced by diatoms as the dominating bloom-causing organisms at all stations, and the density of dinoflagellates at most stations was less than 1.0×106 cells L-1. The status of S. trochoidea as the causative species of the bloom was indicated by the presence of peridinin, the marker pigment for dinoflagellates. The shift from dinoflagellates to diatoms was marked by the decline of peridinin and the preva-lence of fucoxanthin. Phytoplankton pigment markers also revealed the presence of other minor phytoplankton assemblages such as cryptomonads and blue-green algal.

  19. Repercussions of salinity changes and osmotic stress in marine phytoplankton species

    Science.gov (United States)

    D'ors, A.; Bartolomé, M. C.; Sánchez-Fortún, S.

    2016-06-01

    The short-term effect of low salinity was studied using laboratory protocols on some coastal phytoplankton species such as chlorophycea Tetraselmis suecica, among diatom the strain Nitzschia N1c1 and dinoflagellates Alexandrium minutum and Prorocentrum lima. All of cultures were exposed to low salinities, and cell growth rate, photosynthetic quantum yield (ΦPSII), and gross photosynthesis (Pg) were analyzed. Growth rate inhibition was similar in all species, and all of them also tolerate short-term exposures to salinities in the range 5-35. There were no significant differences between ΦPSII and Pg endpoints from Tetraselmis suecica and Nitzschia sp., while Alexandrium minutum and Prorocentrum lima displayed a higher affectation rate on Pg than on ΦPSII activity. The influence of low salinity was higher on respiration in T. suecica, while both dinoflagellates had higher net photosynthesis. Nitzschia sp. exhibited similar involvement of the two photosynthetic parameters. Therefore, although the four phytoplankton monocultures studied are able to survive in internal areas of estuaries under low salinity conditions, the photosynthetic activity is more affected than the growth rate in all phytoplankton communities studied except in chlorophycea T. suecica, which has increased tolerance for this salinity decrease.

  20. A new approach to assess the effects of oil spills on phytoplankton community during the "Serious Game" experiment (MEDESS-4MS Project)

    Science.gov (United States)

    Fiori, Emanuela; Servadei, Irene; Piermattei, Viviana; Bonamano, Simone; Madonia, Alice; Guerrini, Franca; Marcelli, Marco; Pistocchi, Rossella

    2016-11-01

    The "Serious Game" experiment was focused on the development of an integrated monitoring approach to oil spill events in the Mediterranean Sea; it was carried out in the Northern Tyrrhenian Sea, an area that is reported to have intense marine traffic often connected to operational oil discharges. Our experiment was designed in order to develop a rapid assessment of oil spill effects on phytoplankton community through the integration of satellite imagery, in situ sampling and new low-cost technologies. In particular, satellite images were frequently acquired to monitor the study area. When the oil slick was detected, a real time sampling survey was carried out with the support of the Italian Coast Guards, employed as Voluntary Observing Ships for the identification of the polluted area, as well as for sampling and measuring activities. During the experiment, numerous analyses were carried out on the controls (C1, C5, E1, E5) and oiled (M1, M2, M4) stations to assess the most useful methods to quantify the impact of oil slick on the phytoplankton community. Among the numerous methods used, phytoplankton qualitative and quantitative evaluation was indispensable to appreciate subtle changes among the different phytoplankton groups; it is therefore a crucial analysis to observe the short negative effects of oil exposure on microalgae. In addition, the C:N ratio was shown to be a reliable parameter to evaluate the presence of oil compounds in the particulate fraction. Also the new low-cost technology used (the vertical profiler T-FLaPpro) was proved to be an efficient support to the rapid assessment of the oil impact along the water column.

  1. The chronic effects of oil pollution on marine phytoplankton in a subtropical bay, China.

    Science.gov (United States)

    Huang, Yi-Jun; Jiang, Zhi-Bing; Zeng, Jiang-Ning; Chen, Quan-Zhen; Zhao, Yong-qiang; Liao, Yi-bo; Shou, Lu; Xu, Xiao-qun

    2011-05-01

    To evaluate the effects of crude oil water accommodated fraction (WAF) on marine phytoplankton community, natural phytoplankton collected seasonally from the Yueqing bay were exposed to eight groups of crude oil WAF for 15 days under laboratory conditions. Chlorophyll a and cell density were measured, and species of phytoplankton were identified every 24 h to reflect the change of phytoplankton community. The results showed that (1) High concentrations (≥ 2.28 mg l(-1)) of oil pollution would greatly restrain phytoplankton growth (poil WAF in all seasons (ppollutant concentrations in different seasons. Different species had different tolerances to the oil pollution, thus leading to abnormal succession.

  2. 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.

  3. 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.

  4. Experimental evolution meets marine phytoplankton.

    Science.gov (United States)

    Reusch, Thorsten B H; Boyd, Philip W

    2013-07-01

    Our perspective highlights potentially important links between disparate fields-biological oceanography, climate change research, and experimental evolutionary biology. We focus on one important functional group-photoautotrophic microbes (phytoplankton), which are responsible for ∼50% of global primary productivity. Global climate change currently results in the simultaneous change of several conditions such as warming, acidification, and nutrient supply. It thus has the potential to dramatically change phytoplankton physiology, community composition, and may result in adaptive evolution. Although their large population sizes, standing genetic variation, and rapid turnover time should promote swift evolutionary change, oceanographers have focussed on describing patterns of present day physiological differentiation rather than measure potential adaptation in evolution experiments, the only direct way to address whether and at which rate phytoplankton species will adapt to environmental change. Important open questions are (1) is adaptation limited by existing genetic variation or fundamental constraints? (2) Will complex ecological settings such as gradual versus abrupt environmental change influence adaptation processes? (3) How will increasing environmental variability affect the evolution of phenotypic plasticity patterns? Because marine phytoplankton species display rapid acclimation capacity (phenotypic buffering), a systematic study of reaction norms renders them particularly interesting to the evolutionary biology research community.

  5. 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...

  6. Communities under climate change

    DEFF Research Database (Denmark)

    Nogues, David Bravo; Rahbek, Carsten

    2011-01-01

    The distribution of species on Earth and the interactions among them are tightly linked to historical and contemporary climate, so that global climate change will transform the world in which we live. Biological models can now credibly link recent decadal trends in field data to climate change......, but predicting future impacts on biological communities is a major challenge. Attempts to move beyond general macroecological predictions of climate change impact on one hand, and observations from specific, local-scale cases, small-scale experiments, or studies of a few species on the other, raise a plethora...... of unanswered questions. On page 1124 of this issue, Harley (1) reports results that cast new light on how biodiversity, across different trophic levels, responds to climate change....

  7. 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

  8. Iron limitation of a springtime bacterial and phytoplankton community in the Ross Sea: implications for vitamin B12 nutrition

    Directory of Open Access Journals (Sweden)

    Erin M. Bertrand

    2011-08-01

    Full Text Available The Ross Sea is home to some of the largest phytoplankton blooms in the Southern Ocean. Primary production in this system has previously been shown to be iron limited in the summer and periodically iron and vitamin B12 colimited. In this study, we examined trace metal limitation of biological activity in the Ross Sea in the austral spring and considered possible implications for vitamin B12 nutrition. Bottle incubation experiments demonstrated that iron limited phytoplankton growth in the austral spring while B12, cobalt, and zinc did not. This is the first demonstration of iron limitation in a Phaeocystis antarctica-dominated, early season Ross Sea phytoplankton community. The lack of B12 limitation in this location is consistent with previous Ross Sea studies in the austral summer, wherein vitamin additions did not stimulate P. antarctica growth and B12 was limiting only when bacterial abundance was low. Bottle incubation experiments and a bacterial regrowth experiment also revealed that iron addition directly enhanced bacterial growth. B12 uptake measurements in natural water samples and in an iron fertilized bottle incubation demonstrated that bacteria serve not only as a source for vitamin B12, but also as a significant sink, and that iron additions enhanced B12 uptake rates in phytoplankton but not bacteria. Additionally, vitamin uptake rates did not become saturated upon the addition of up to 95 pM B12. A rapid B12 uptake rate was observed after 13 min, which then decreased to a slower constant uptake rate over the next 52 hours. Results from this study highlight the importance of iron availability in limiting early season Ross Sea phytoplankton growth and suggest that rates of vitamin B12 production and consumption may be impacted by iron availability.

  9. 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.

    In a monsoon-affected tropical estuary, oscillations in freshwater discharge during monsoon shifted the phytoplankton blooms from those adapted to low salinity to high salinity and vice versa. Salinity stratification during monsoon (onset...

  10. Fluorescence signatures of an iron-enriched phytoplankton community in the eastern equatorial Pacific Ocean

    Science.gov (United States)

    Hoge, Frank E.; Wayne Wright, C.; Swift, Robert N.; Yungel, James K.; Berry, Richard E.; Mitchell, Richard

    Laser-induced fluorescence profiles of chlorophyll and phycoerythrin pigments and chromophoric dissolved organic matter (CDOM) fluorescence acquired over an iron-enriched phytoplankton patch are compared to profiles made over adjacent, naturally occurring phytoplankton patches. A total of four airborne missions were flown during an 8 day period following the release of the iron-rich fertilizer. Analyses of the airborne laser-induced fluorescence profiles from the upper-ocean layer reveal: (1) Ship-dispersed iron enhances localized phytoplankton production in high-nutrient/low-chlorophyll regions such as found in the eastern equatorial Pacific Ocean. (2) The chlorophyll concentration within the iron-enriched phytoplankton patch exceeded levels of chlorophyll found in naturally occurring phytoplankton patches located outside the enriched region. (3) An increase in phycoerythrin fluorescence was observed within the enriched region in correspondence with the elevated chlorophyll fluorescence. However, the phycoerythrin/chlorophyll fluorescence ratio was lower within the enriched patch than in naturally occurring phytoplankton patches outside of the enriched region. (4) No above-background chromorophoric dissolved organic matter (CDOM) fluorescence was observed in the enriched patch. Elevated CDOM fluorescence was associated with some of the naturally occurring phytoplankton patches outside the enriched region, while other such phytoplankton patches showed no measurable increase in CDOM over background levels. (5) The surface layer manifestation of the patch was observed to be transported to the north and west in close agreement with the drogue positions. No elevated surface layer chlorophyll fluorescence was seen in the vicinity of the ship as it sampled the submerged fraction at the time of the 30 October and 1 November overflights. The phycoerythrin pigment fluorescence emission was insensitive to ambient cloud-induced downwelling irradiance variability, while at the

  11. Changes in nutrient uptake of phytoplankton under the interaction between sunlight and phosphate in the Changjiang(Yangtze)River Estuary

    Institute of Scientific and Technical Information of China (English)

    FANG Tao; LI Daoji; YU Lihua; LI Yun

    2008-01-01

    We conducted ship-board incubation experiments to investigate changes in nutrient uptake of phytoplankton under different phosphate concentrations and irradiances in the Changjiang River Estuary and its adjacent waters in China.Under 100% natural irradiance the uptake rates of phosphate,silicate,and nitrate were accelerated at high phosphate levels(1.84 μM),while under low irradiance(about 50%natural irradiance)their uptake rates were restrained at the high but stimulated greatly at the intermediate phosphate concentrations(1.26μM),as the growth of phytoplankton,changes in nitrite and ammonium uptake didn't follow an obvious pattern.Our results alSO showed that there were linear relationships between nitrate,silicate and phosphate uptake at different phosphate concentrations under low and high irradiances,and the growth period of phytuplankton was prolonged both at the high phosphate concentrations under high irradiance and at the intermediate concentrations under low irradiance,suggesting that the limitation of phytoplankton growth mainly reflected changes in its growth period,and because no such environment(low-irradiance and low phosphate concentrations)actually existed in a high turbidity zone,phytoplankton blooms hardly occurred there.In the absence of irradiance,denitrification occurred readily and phytoplankton was kept decreasing,which resulted in phOSphate regeneratton.

  12. 北京翠湖湿地浮游植物群落特征%Characterization of the Phytoplankton Community in Cuihu Wetland in Beijing

    Institute of Scientific and Technical Information of China (English)

    王晓星

    2013-01-01

      2012年4月至11月,对翠湖湿地浮游植物的群落结构和物种多样性进行了初步研究,并结合水体理化指标进行分析讨论。结果显示,在翠湖湿地共鉴定出浮游植物8门73属154种,以绿藻门、硅藻门和蓝藻门种类数量最多,且8月份种类达到高峰。翠湖湿地浮游植物的平均密度为14243.62×104 cells/L,以绿藻门、蓝藻门和硅藻门的藻类密度最大,黄藻门和甲藻门藻类密度最小;浮游植物Shannon-wiener指数平均值为1.50,且浮游植物群落中的优势种群随季节变化而不同。翠湖湿地浮游植物的变化与水温、总氮浓度和叶绿素a 浓度密切相关,多项指标表明翠湖湿地水体呈富营养化状态,污染程度为中污染,水体中有机质含量较高。%From April to November, 2012, structure and species diversity of phytoplankton community in the Cuihu Wetland were studied in combination with physiochemical indicators of the water. Results showed that the total amount of the phytoplankton were of 8 phyla, 73 genera and 154 species, the largest number of species were of Chlorophyta, Bacillariophyta and Cyanophyta, when reached a peak in August. The average density of phytoplankton in Cuihu Wetland was 14243.62 ×104 cells/L, the density of algae, for instance, Chlorophyta, Cyanophyta and Bacillariophyta reached the maximum density, while such as Xanthophyta and Dinoflagellate reached the minimum density; the average value of Shannon-wiener index was 1.50, and the dominant species in phytoplankton varies among seasons. The changes of phytoplankton in the Cuihu wetland closely related to water temperature, total nitrogen concentration and chlorophyll-a concentration. A number of indicators showed that Cuihu Wetland was in a state of eutrophication, moderate level of pollution, and high content of organic matter in water.

  13. Characteristics of Phytoplankton Community Structure in Hongfeng Lake%红枫湖浮游植物群落的结构特征分析

    Institute of Scientific and Technical Information of China (English)

    梁正其; 姚俊杰; 方贵镇; 王秀龙; 陆敬波; 吴艳

    2011-01-01

    为了解红枫湖水体状况及其浮游植物的多样性和群落结构,在红枫湖选择18个典型的采样点,于2010年10月和12月两次采样,对所采集植物进行定性、定量分析.结果表明,目前红枫湖有浮游植物8门13目1亚目23科37属55种,其中,绿藻门种类最多,共21种,占总数的38.2%;蓝藻门次之,共15种,占总数的27.3%;硅藻9种,占16.3%;甲藻和黄藻各3种,分别占5.5%;金藻门2种,占3.6%;裸藻和隐藻各1种,各占1.8%.红枫湖浮游植物平均数量和平均生物量分别为7.5×105个/L和1.79 mg/L.优势种为小环藻、色球藻和小球藻,优势度分别为0.407、0.048和0.077.与1996年相比,主要优势种发生了变化,但浮游植物群落结构仍以绿藻为主,蓝藻次之.红枫湖浮游植物多样性和均匀度分别在2.01~2.68和0.35~0.50,表明,红枫湖水体状况优于1996年.%The qualitative and quantitative analysis of phytoplankton in waters from 18 typical sampling points of Hongfeng Lake was conducted to know the water body status of Hongfeng Lake and the diversity and community structure of phytoplankton. The results showed that there were 55 species, belonging to 37 genera, 23 families, 1 suborder, 13 orders and 8 phyla in phytoplankton. 21 Chlorophta species, 15 Cyanophyta species, 9 Bacillariophyta species, 3 Pyrrophyceae species, 3 Xanthophyta species, 2 Chrysophyta species, 1 Euglenophyta species and Cryptophyceae species accounted for 38. 2%, 27. 3%, 16. 3% , 5. 5% , 5. 5% , 3. 6% , 1. 8% and 1. 8% respectively. The average quantity per litre and biomass of phytoplankton in Hongfeng Lake were 7. 5 X 105 and 1. 79mg/L. The dominance of Cyclotella sp. Chlorella vulgaris and Chroococcus sp. Was 0. 407, 0. 048 and 0. 077 separately. The main dominant species in phytoplankton were changed, but the community structure of phytoplankton still was dominated by green alga, followed by blue-green algae in Hongfeng Lake. The diversity and uniformity variation of

  14. Phytoplankton pigments and functional community structure in relation to environmental factors in the Pearl River Estuary

    Directory of Open Access Journals (Sweden)

    Chao Chai

    2016-07-01

    Full Text Available Two cruises were undertaken in the Pearl River Estuary in November 2011 and March 2012 to analyze the distribution of phytoplankton pigments and to define the relationships of pigment indices and functional community structure with environmental factors. Among 22 pigments, 17 were detected by high-performance liquid chromatography. Chlorophyll a was found in all samples, with a maximum of 7.712 μg L−1 in spring. Fucoxanthin was the most abundant accessory pigment, with mean concentrations of 2.914 μg L−1 and 0.207 μg L−1 in spring and autumn, respectively. Chlorophyll a, chlorophyll c2, fucoxanthin, diadinoxanthin, and diatoxanthin were high in the northern or northwest estuary in spring and in the middle-eastern and northeast estuary in autumn. Chlorophyll b, chlorophyll c3, prasinoxanthin, and peridinin were similarly distributed during the two cruises. Chlorophyll a and fucoxanthin positively correlated with nutrients in spring, whereas 19′-hex-fucoxanthin and 19′-but-fucoxanthin negatively correlated. The biomass proportion of microphytoplankton (BPm was higher in spring, whereas that of picophytoplankton (BPp was higher in autumn. BPm in spring was high in areas with salinity 30. BPm increased but BPn reduced with the increase in nutrient contents. By comparison, BPp reduced with the increase in nutrient contents in spring, but no relationship was found between BPp and nutrient contents in autumn. The ratios of photosynthetic carotenoids to photoprotective carotenoids in the southern estuary approached unity linear relationship in spring and were under the unity line in autumn.

  15. Phytoplankton community from Lake Taihu,China,has dissimilar responses to inorganic and organic nutrients

    Institute of Scientific and Technical Information of China (English)

    Xiaodong Wang; Boqiang Qin; Guang Gao; Yongping Wang; Xiangming Tang; Timothy Otten

    2010-01-01

    To evaluate the response of phytoplankton from Lake Taihu to different types of nutrients,the phytoplankton responses were measured after adding inorganic nitrogen (N) and phosphorus (P) or decomposed algal scum (Microcystis spp.) into the lake water.Both types of nutrients promoted an increase in phytoplankton biomass as determined by chlorophyll a and algal wet weight.The addition of decomposed algal scum resulted in a significantly greater phytoplankton response than the addition of inorganic N and P alone.The dissolved inorganic N and P in the inorganic nutrient treatment were found not limit phytoplankton growth.The higher algal biomass obtained in the treatment with decomposed algal scum indicated the importance of other organic nutrients besides N and P such as trace elements,as well as the importance of the form of N since the levels of ammonia nitrogen (NH4+-N) from the decomposed algal treatment were actually higher than that of the inorganic N and P addition.Microcystis spp.(Cyanobacteria),Scenedesmus spp.(Chlorophyta) and Synechocystis spp.(Cyanobacteria) were the dominant taxa in the control,inorganic N and P treatment,and the decomposed algal scum treatment,respectively.Microcystis never bloomed in response to both types of nutrient additions indicating that the bloom propagation is not solely related to nutrient additions,but may be related to the absence of selective grazing from zooplankton.

  16. Phytoplankton community structure in Lake Taiping of Anhui Province%安徽太平湖浮游植物群落结构

    Institute of Scientific and Technical Information of China (English)

    熊莲; 刘冬燕; 王俊莉; 吴明姝; 李东京

    2016-01-01

    /L. The average of Shannon-Wiener and Pielou evenness index are 2.17 and 0.61, respectively. The dominant species add up to 17, belonging to 4 phyla, and 12 species of them areβ-moderate pollution indication algae which focus on Cyanophyta and Bacillariophyta. Annual change indicates that phytoplankton community structure is relatively stable in Lake Taiping. Cluster analysis indicates that phytoplankton community structure is similar between summer and autumn, and phytoplank-ton community structure is similar in H1, H2, H3 to the H4 and H5 sampling sites. Correlation analysis indicates that abundance and biomass are significant positively related with temperature, but abundance and biomass are significant negatively related with the transparency. Changes in water quality will directly affect phytoplankton changes, and cause complex changes in ecosystem and ecological process in Lake Taiping.

  17. 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...

  18. Seasonal changes of phytoplankton production in response to high nitrogen load in the Bay of Seine

    Science.gov (United States)

    L Helguen, S.; Maguer, J.-F.; Madec, C.

    2003-04-01

    Seasonal changes of uptake of nitrogenous nutrients and regeneration were investigated in nitrogen rich waters of the Bay of Seine. Uptake of nitrogen nutrients (NO_3-, NH_4^+ and urea), and NH_4^+ regeneration, were measured using the 15N isotope technique in three different water masses along a salinity gradient (salinity: 27-29, 31-32 and 34-35). The Seine river add very high quantities of inorganic nitrogen to the coastal waters mainly in the form of nitrate (up to 120 μmol l-1). In the plume, the nitrate concentration remained high (> 10 μmol l-1) during all the seasons. In these nitrate enrich waters, phytoplankton attained high biomass (20-25 μg chla l-1). Species succession was marked by blooms formation from the beginning of spring until the end of summer. The high biomass was represented by microplankton generally dominated by diatom species during all the seasons. However, nano- and picoplankton biomass increased significantly during the summer and represented up to 50% of the total biomass of phytoplankton. Nitrogen uptake rates were higher in the Seine Bay plume (0.5 μmol l-1 h-1) than the other coastal waters. Although, the N uptake was high, it was limited by light, which was due to the high turbidity and strong vertical mixing in these plume waters. The seasonal variations in nitrogen uptake demonstrated that during spring, up to 80% of nitrogen was utilized by microplancton whereas in summer, all the fractions utilized nitrogen significantly. In spring, nitrate was the major nitrogen nutrient taken up (˜ 80% of total nitrogen uptake). During other seasons, ammonium and urea were the highly utilized nitrogen compounds (up to 95% of total nitrogen uptake). Ammonium regeneration by microhétérotrophs increased significantly in the plume waters during the spring bloom and remained high (> 0.1 μmol l-1 h-1) until the end of summer. The high and prolonged use of NH_4^+ was due to high autochthonous production, fulfil 40 to 100% of NH_4^+ demand of

  19. Phytoplankton communities from San Francisco Bay Delta respond differently to oxidized and reduced nitrogen substrates - even under conditions that would otherwise suggest nitrogen sufficiency

    Directory of Open Access Journals (Sweden)

    Patricia M Glibert

    2014-07-01

    Full Text Available The effect of equivalent additions of nitrogen (N, 30-40 μM-N in different forms (ammonium, NH4+, and nitrate, NO3- under conditions of different light exposure on phytoplankton community composition was studied in a series of four, 5-day enclosure experiments on water collected from the nutrient-rich San Francisco Bay Delta over two years. Overall, proportionately more chlorophyll a and fucoxanthin (generally indicative of diatoms was produced per unit N taken up in enclosures enriched with NO3- and incubated at reduced (~15% of ambient light intensity than in treatments with NO3- with high (~60% of ambient light exposure or with NH4+ under either light condition. In contrast, proportionately more chlorophyll b (generally indicative of chlorophytes and zeaxanthin (generally indicative of cyanobacteria was produced in enclosures enriched with NH4+ and incubated under high light intensity than in treatments with low light or with added NO3- at either light level. Rates of maximal velocities (Vmax of uptake of N substrates, measured using 15N tracer techniques, in all enclosures enriched with NO3- were higher than those enriched with NH4+. Directionality of trends in enclosures were similar to phytoplankton community shifts observed in transects of the Sacramento River to Suisun Bay, a region in which large changes in total N quantity and form occur. These data substantiate the growing body of experimental evidence that dichotomous microbial communities develop when enriched with the same absolute concentration of oxidized vs. reduced N forms, even when sufficient N nutrient was available to the community prior to the N inoculations.

  20. Solar irradiance changes and phytoplankton productivity in Earth's ocean following astrophysical ionizing radiation events

    CERN Document Server

    Neale, Patrick J

    2016-01-01

    Two atmospheric responses to simulated astrophysical ionizing radiation events significant to life on Earth are production of odd-nitrogen species, especially NO2, and subsequent depletion of stratospheric ozone. Ozone depletion increases incident short-wavelength ultraviolet radiation (UVB, 280-315 nm) and longer ( > 600 nm) wavelengths of photosynthetically available radiation (PAR, 400 -700 nm). On the other hand, the NO2 haze decreases atmospheric transmission in the long-wavelength UVA (315-400 nm) and short wavelength PAR. Here we use the results of previous simulations of incident spectral irradiance following an ionizing radiation event to predict changes in Terran productivity focusing on photosynthesis of marine phytoplankton. The prediction is based on a spectral model of photosynthetic response developed for the dominant genera in central regions of the ocean (Synechococcus and Prochlorococcus), and remote-sensing based observations of spectral water transparency, temperature, wind speed and mixed...

  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,...

  2. Effects of chemical ecological adjustment and control experiment on phytoplankton community in the Aoshan Bay

    Institute of Scientific and Technical Information of China (English)

    陈碧鹃; 赵俊; 辛福言; 崔毅; 过锋

    2002-01-01

    There is a low nutrient level in the Aoshan Bay. In June 1999, the chemical adjustment and control experiment was made in the Aoshan Bay. Following tracts investigation was carried out before the experiment and on the 1st, 2nd, 4th, 5th, 6th and 45th day/after the experiment. While the variance of amount of phytoplankton, the replacement of superior species and the species composition of phytoplankton were researched. The results show that the amount of phytoplankton in the Aoshan Bay rises gradually after the experiment. Ceratium macroceros Cleve of pyrophyta was the dominant species before the experiment, its dominant index was 37.7%. Six days after the experiment, its dominant index dropped to 17.6%. Meanwhile the dominant index of Asterionella japonics Cleve rose from 7.1% to 39.2%, it became the first dominant species. Forty-five days after the experiment, the amount of phytoplankton in the Aoshan Bay was 5.15 to 137.32 times more than that in 1997.

  3. 太湖浮游植物群落结构及其与水质指标间的关系%Structure of Phytoplankton Community and Relationship between Phytoplankton Community and Water Quality in Taihu Lake

    Institute of Scientific and Technical Information of China (English)

    李娣; 李旭文; 牛志春; 王霞; 师伟; 于红霞

    2014-01-01

    To research the structure of phytoplankton community and relationship between phytoplankton community and water quality in Taihu Lake, phytoplankton community structure and water quality indicators (temperature, transparency, pH value, dissolved oxygen, conductivity, total nitrogen, total phosphorus, ammonia, high manganese on permanganate index, chemical oxygen demand, fluoride, biological oxygen demand, nitrate, nitrite, phosphate solubility and chlorophyll a) were monthly investigated at seven sites in Taihu Lake between January and December of 2013 in our study. Meanwhile, Pearson’s correlations between phytoplankton communities and environmental variables were used to find the factors that influenced the distribution of phytoplankton community. The results found that there were 124 species of phytoplankton, including 30 taxa Cyanophyta, 47 kinds of Bacillariophyta, 34 species Chlorophyta, 3 Cryptophyta, 6 Euglenophyta, 4 Dinoflagellate; as an absolute dominant species, dominance of Microcystis spp. was 80.8 %. From space, phytoplankton density in Gonghu was highest among the seven sites. Diversity of phytoplankton community was lower than other sites. Meanwhile, density percentage of Microcystis spp. in Gonghu was 90.1%, far higher than other sites. From the time point of view, December was when the density of phytoplankton community in Taihu Lake was highest, followed by June. The principal pollutant was total nitrogen, secondly total phosphorus, thirdly chemical oxygen demand. Concentration of pollutants in West Taihu was highest in our study. Through correlation analysis of phytoplankton community and water quality, it showed that water temperature, transparency, total nitrogen, chemical oxygen demand and chlorophyll a were main factors that influenced phytoplankton community structure in Taihu Lake. Controlling water pollutant emissions and restoring ecological function should be an effective method to manage cyanobacteria bloom in Taihu Lake. Meanwhile

  4. Fluorescence, pigment and microscopic characterization of Bering Sea phytoplankton community structure and photosynthetic competency in the presence of a Cold Pool during summer

    Science.gov (United States)

    Goes, Joaquim I.; Gomes, Helga do Rosario; Haugen, Elin M.; McKee, Kali T.; D'Sa, Eurico J.; Chekalyuk, Alexander M.; Stoecker, Diane K.; Stabeno, Phyllis J.; Saitoh, Sei-Ichi; Sambrotto, Raymond N.

    2014-11-01

    Spectral fluorescence measurements of phytoplankton chlorophyll a (Chl a), phytoplankton phycobilipigments and variable fluorescence (Fv/Fm), are utilized with High Performance Liquid Chromatography (HPLC) estimates of phytoplankton pigments and microscopic cells counts to construct a comprehensive picture of summer-time phytoplankton communities and their photosynthetic competency in the eastern Bering Sea shelf. Although the Bering Sea was ice-free during our study, the exceptionally cold winter that preceded the summer of 2008 when our cruise took place, facilitated the formation of a "Cold Pool" (<2 °C) and its entrapment at depth in the northern middle shelf. The presence of a strong pycnocline over the entire middle and outer shelves restricted inorganic nutrient fluxes into the surface waters resulting in phytoplankton populations that were photo-physiologically stressed due to nutrient limitation. Elevated Chl a concentrations recorded in the Green Belt along the shelf edge of the Bering Sea, were due to Phaeocystis pouchetii and nano-sized cryptophytes. Although inorganic nutrients were not limiting in the Green Belt, Fv/Fm values were low in all probability due to iron limitation. Phytoplankton communities in the low biomass surface waters of the middle shelf were comprised of prasinophytes, haptophytes, cryptophytes and diatoms. In the northern part of the middle shelf, a sinking bloom made up of the centric diatoms Chaeotoceros socialis, Thalassiosira nordenskioeldii and Porosira glacialis was located above the Cold Pool. The high biomass associated with this senescent bloom and its accretion above the pycnocline, suggests that the Cold Pool acts as a barrier, preventing sinking phytoplankton from reaching the bottom where they can become available to benthic organisms. We further posit that if summer-time storms are not energetic enough and the Cold Pool is not eroded, its presence facilitates the transfer of the large spring phytoplankton bloom to

  5. UV-induced changes in phytoplankton cells and its effects on grazers

    NARCIS (Netherlands)

    Hessen, D.O.; DeLange, H.J.; Van Donk, E.

    1997-01-01

    This review addresses the effects of UV-radiation on the morphology and biochemistry of phytoplankton and the potential effects on grazers. UVA and UVB radiation inhibit the uptake of inorganic nutrients in phytoplankton. Reduced rates of ammonium and nitrate uptake in marine diatoms, and reduced up

  6. Trends of phytoplankton characteristics and their communities in pre- and post-liming time in Lake Orta (1984-1998

    Directory of Open Access Journals (Sweden)

    Pierisa PANZANI

    2001-02-01

    Full Text Available This paper is an assessment of the changing properties of Lake Orta phytoplankton in the period 1984-1998, which includes the large-scale liming carried out in the lake in 1989 and 1990. The phytoplankton is analysed first in its general properties (abundance, biovolume, chlorophyll-a concentration, average cell size, diversity by means of time courses of the mentioned variables based on monthly data through the entire period, and by correlations between the same variables. Moreover, through clustering techniques, the evolution of the species composition has been studied, showing the gradual decrease of chlorophytes after the liming and the noticeable increase of the diatom population, both as biovolume and diversity. Although the assemblage of the dominant species still mirrors the presence of some residual toxic compounds into the lake water, in the most recent period the evolution of the algal populations showed a clear trend towards a species assemblage more similar to those observed in the other deep italian subalpine lakes. After the improving of the chemical environment, the main abiotic factor that in the next years could play a major role in modifying the species assemblage is probably the phosphorus supply, whose in-lake concentration is low, despite the high annual load from the basin. A better understanding of the mechanisms underlying the phosphorus dynamics represent the basis to make reliable hypotheses about the future evolution of the phytoplankton assemblage.

  7. Structure and composition of the phytoplanktonic community in TRanca Grande Lagoo (Junín, Perú

    Directory of Open Access Journals (Sweden)

    Mauro Mariano-Astocóndor

    2014-06-01

    Full Text Available The Tranca Grande lagoon is one of the systems where the truchiculture is realized, a productive activity which supports the lake since 1995. It is located in the Paramo floor or Tropical Montano in the Department of Junin, Province of Jauja to 4320 m of altitude (11º43’57?S and (75º13’18? W. The structure and composition of the superficial phytoplanktonic community was studied from monthly samples collected from January to December on 1996 in relation to 21 physical-chemical variables of water. The community showed 51 species belonging to Bacillariophyta, Chlorophyta, Cyanophyta, Euglenophyta, Chrysophyta and Pyrrophyta. The highest average values of density were from Gloeocystis gigas and Ulothrix sp. On the rainy months, the rain fall had a considerable influence on the dilution and sedimentation of the macronutrients responsible for the conductivity, alkalinity, hardness, calcium and magnesium which decrease their values, and likewise the values of the diversity and density decrease. In the period of low-water mark, the characteristics mentioned about rainy period appear on the inverse way. The quantity of species and their density on the phytoplankton were found with the Multiple Regression Analysis. a Species = 7,32+10,59 (The clearness of water - 0,1614 (hardness of calcium + 4,90 (nitrates. b Density = -1,00 + 4397,18 (pH - 223,6 (total alkalinity - 1,4 (phosphates

  8. Effects of climatic variability on phytoplankton community structure and bloom development in the eutrophic, microtidal, New River Estuary, North Carolina, USA

    Science.gov (United States)

    Hall, Nathan S.; Paerl, Hans W.; Peierls, Benjamin L.; Whipple, Anthony C.; Rossignol, Karen L.

    2013-01-01

    The roles of climatically driven freshwater flow, nutrient loading, and temperature on phytoplankton community biomass and composition were examined along a downstream transect within the New River Estuary, North Carolina from 2007 to 2010. This microtidal system has a history of eutrophication symptoms, including harmful algal blooms. Riverine discharge strongly controlled nutrient loading to the estuary. Except during very high flow conditions, loads were generally assimilated near the head of the estuary and low concentrations of dissolved inorganic nitrogen and phosphate, cyanobacteria to exploit low residual nutrient concentrations, and subsidies to the diatom population via sediment resuspension events. In addition to effects of flow, pico-cyanobacteria and harmful raphidophyte taxa demonstrated positive relationships with temperature. Overall, results demonstrate a strong linkage between the phytoplankton community and two important climatic drivers, flow and temperature. The observed sensitivity of phytoplankton biomass to nutrient loads suggests that load reductions (or increases) are likely to decrease (or increase) total phytoplankton biomass in this system. However, phytoplankton community composition appears to be largely determined by environmental factors other than nutrient loading, particularly temperature, stratification and sediment resuspension.

  9. Comunidade fitoplanctônica de um pesqueiro na cidade de São Paulo Phytoplankton community in a recreational fishing lake, Brazil

    Directory of Open Access Journals (Sweden)

    Mayla Matsuzaki

    2004-10-01

    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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

  10. In situ study on photosynthetic characteristics of phytoplankton in the Yellow Sea and East China Sea in summer 2013

    Science.gov (United States)

    Li, Junlei; Sun, Xiaoxia; Zheng, Shan

    2016-08-01

    In situ studies on photosynthetic characteristics of phytoplankton were important for the analysis of changes in community structure and for the prediction and control of algal blooms, but such studies of phytoplankton in offshore China were few. In this study, the detailed distribution of photosynthetic characteristics of phytoplankton in the summer of 2013 in the Yellow Sea and East China Sea was measured using Phyto-PAM (Pulse Amplitude Modulation). The phytoplankton community structure and the environmental parameters were also investigated to estimate the relationship between the distribution of the photochemical competence of phytoplankton and ecological factors. The total average Fv/Fm (the potential maximum quantum yield) value of phytoplankton in the Yellow Sea and East China Sea in summer 2013 was less than 0.5, reflecting that the photosynthetic activity of phytoplankton was relatively low. Fv/Fm of phytoplankton in summer was significantly positively associated with nitrate content (NO2-), which reflects relationship between metabolism and photosynthesis of phytoplankton: accompanied by NO2- metabolism, photosynthesis and photosynthetic capacity may be enhanced simultaneously, so the Fv/Fm value would increase with the NO2- released by phytoplankton. Through the in situ study on photosynthetic characteristics of phytoplankton in the Yellow Sea and East China Sea, we come to the conclusion that photosynthetic characteristics and activity of phytoplankton are influenced by its biological characteristics and surrounding ecological factors, such as irradiance, nutrients and phytoplankton community. Meanwhile, the thermally stratified structure and the movement of water masses, such as the Yangtze River diluted water, the Yellow Sea cold water mass and other different water system, also have an important impact on phytoplankton photosynthetic activity and characteristics. Greater understanding of the detailed photosynthetic characteristics of phytoplankton

  11. 于桥水库秋季浮游植物群落结构与水质因子的关系%Relationship between structure of phytoplankton community and water quality factors in Yuqiao Reservoir in autumn

    Institute of Scientific and Technical Information of China (English)

    田志强; 田秉晖; 辛丽花; 贾大伟; 张磊

    2011-01-01

    Aimed at the problems of water security resulted of eutrophication caused by algae outbreaks in Yuqiao Reservoir in autumn, the relationship between structure of phytoplankton community and water quality factors was studied, at the same time, eutrophication main-control factors and principal water quality factors which influenced on structure of phytoplankton community were recognized. The results showed a total of 110 phytoplankton species was detected, which belonged to 52 genera, 7 phylum; phytoplankton average abundance was 3.46 × 105 cells/L, and dominant species consisted of Synedra acus Kutz, Synedra arnphicephala , Anabaena cylindricus , and Raphidiopsis curvata; The status of water quality was general mesotrophic; Changes of water quality had a greater impact on species number and abundance of the phytoplankton. DO, pH and transparency were primary water quality factors which influenced on structure of phytoplankton community, and phosphorus is the main controlling factor of eutrophication.Base on the current eutrophication in Yuqiao Reservoir, water security can be ensured by regulating water quality factors and community structure so as to avoid large scale of algae outbreak.%针对于桥水库秋季藻类大量爆发引发的富营养化所导致的供水安全问题,研究了浮游植物群落结构与水质因子的关系,找出影响浮游植物群落结构的主要水质因子和富营养化的主控因子.结果显示,2009年秋季于桥水库共有浮游植物110种,隶属于7门52属,平均丰度为3.46×105个/L,优势种为弯形尖头藻、圆柱鱼腥藻、双头针杆藻、尖针杆藻;于桥水库水质总体处于中营养状态;浮游植物物种丰富度、丰度受水质变化影响较大,DO、pH、透明度是影响浮游植物群落结构的主要水质因子,磷是富营养化的主控因子.在现有的富营养化状况下,通过调控主要水质因子,控制群落结构,可以防止水华大规模爆发,确保水质安全.

  12. CHEMTAX-derived phytoplankton community structure associated with temperature fronts in the northeastern Arabian Sea..

    Digital Repository Service at National Institute of Oceanography (India)

    Roy, R.; Chitari, R.; Kulkarni, V.; Krishna, M.S.; Sarma, V.V.S.S.; Anil, A.C.

    and Southwest Monsoon of 1995 as described by HPLC-analyzed pigments. Deep-Sea Res. II. 45, 2133-2170. Landry, MR., 2002. Integrating classical and microbial food web concepts: evolving views from the open-ocean tropical Pacific. Hydrobiologia. 480, 29... the phytoplankton pigment composition and nutrient signatures of these SST filaments and / or fronts in the NEAS to understand their role in food web dynamics. To our knowledge this is the first report from this region. Materials and methods 2.1. Study area...

  13. An automated platform for phytoplankton ecology and aquatic ecosystem monitoring.

    Science.gov (United States)

    Pomati, Francesco; Jokela, Jukka; Simona, Marco; Veronesi, Mauro; Ibelings, Bas W

    2011-11-15

    High quality monitoring data are vital for tracking and understanding the causes of ecosystem change. We present a potentially powerful approach for phytoplankton and aquatic ecosystem monitoring, based on integration of scanning flow-cytometry for the characterization and counting of algal cells with multiparametric vertical water profiling. This approach affords high-frequency data on phytoplankton abundance, functional traits and diversity, coupled with the characterization of environmental conditions for growth over the vertical structure of a deep water body. Data from a pilot study revealed effects of an environmental disturbance event on the phytoplankton community in Lake Lugano (Switzerland), characterized by a reduction in cytometry-based functional diversity and by a period of cyanobacterial dominance. These changes were missed by traditional limnological methods, employed in parallel to high-frequency monitoring. Modeling of phytoplankton functional diversity revealed the importance of integrated spatiotemporal data, including circadian time-lags and variability over the water column, to understand the drivers of diversity and dynamic processes. The approach described represents progress toward an automated and trait-based analysis of phytoplankton natural communities. Streamlining of high-frequency measurements may represent a resource for understanding, modeling and managing aquatic ecosystems under impact of environmental change, yielding insight into processes governing phytoplankton community resistance and resilience.

  14. 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.

  15. Phytoplankton response to whole lake inorganic N fertilization along a gradient in dissolved organic carbon.

    Science.gov (United States)

    Deininger, A; Faithfull, C-L; Bergström, A-K

    2017-01-31

    Global change has increased inorganic nitrogen (N) and dissolved organic carbon (DOC; i.e. 'browning') inputs to northern hemisphere boreal lakes. However, we do not know how phytoplankton in nutrient poor lake ecosystems of different DOC concentration respond to increased N availability. Here, we monitored changes in phytoplankton production, biomass and community composition in response to whole lake inorganic N fertilization in six boreal unproductive Swedish lakes divided into three lake pairs (control, N enriched) at three DOC levels (low, medium, high), with one reference year (2011) and two impact years (2012, 2013). We found that phytoplankton biomass and production decreased with DOC concentration before N fertilization. Further, phytoplankton community composition also differed with respect to DOC, with a dominance of non-flagellated autotrophs at low DOC towards an increasing dominance of flagellated autotrophs with increased lake DOC concentration. The N fertilization increased phytoplankton biomass and production in all lakes, but did not affect phytoplankton community composition. However, the net response in biomass and production to N fertilization declined with increasing DOC, implying that the lake DOC concentration is critical in order to infer phytoplankton responses to N fertilization, and that the system switches from being primarily nutrient limited to becoming increasingly light limited with increased DOC concentration. In conclusion, our results show that browning will reduce phytoplankton production and biomass and influence phytoplankton community composition, whereas increased inorganic N loadings from deposition, forestry or other land use will primarily enhance phytoplankton biomass and production. Together, any change in the landscape that enhances inorganic N availability will increase phytoplankton production and biomass, but the positive effects of N will be much weaker or even neutralized in browner lakes as caused by light

  16. Changes in phytoplankton composition in response to tides, wind-induced mixing conditions, and freshwater outflows in an urbanised estuarine complex

    Directory of Open Access Journals (Sweden)

    GAO Moser

    Full Text Available 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.

  17. Research on Phytoplankton Community of Dianchi Lake%滇池浮游藻类群落构成调查

    Institute of Scientific and Technical Information of China (English)

    施择; 李爱军; 张榆霞; 铁程; 赵琦林; 李颖; 金玉

    2014-01-01

    The species composition and temporal distribution of Dianchi phytoplankton was studied in May 2012 and December. A total of 159 algae species belonging to 66 genera, 8 phyla were identified. The dominant taxa were Chlorophyta and Cyanophyta, with the species number in the order of Chlorophyta > Cyanophyta. The average density of phytoplankton community reached 1�398 × 108 cell/L and 2�180 × 108 cell /L in May and December separately. Microcystis Kutz, Cyanophyta, was the highest cell proportion. The average density of phytoplankton community was higher in northern lake than that in southern lake in May, but this density was lower in northern lake than that in southern and middle lake in December. Algal biomass was significantly higher in outer lake than inner lake, but there was higher cell proportion of Chlorophyta in inner lake than outer lake. Algal biomass was significantly higher in December than in May. Compared with the phytoplankton investigation in Dianchi Lake from April 2006 to May 2007, few difference was found about the number of algae species, common species, dominant species and biomass levels in Dianchi Lake ( mostly outer lake of Dianchi) .%对滇池浮游藻类群落组成和空间分布开展了2次调查,鉴定出藻类8门66属159种及变种,绿藻种类最多,蓝藻次之。5、12月滇池全湖平均藻类密度分别为1�398×108、2�180×108个/升,蓝藻门微囊藻属为优势藻类。5月的调查中滇池外海藻类生物量呈北高南低的格局,而12月则呈现南部和中部高,北部低。外海的藻类生物量明显高于草海,草海藻类群落构成与外海明显不同,主要表现为绿藻门藻类所占比例较高。12月滇池外海及全湖藻类生物量都显著高于5月。与上一次(2006-2007年)滇池浮游藻类的系统调查相比,滇池(主要是外海)浮游藻类在物种数量、常见藻类、优势藻类及生物量水平方面与之接近。

  18. Phytoplankton response to winter warming modified by large-bodied zooplankton: an experimental microcosm study

    Directory of Open Access Journals (Sweden)

    Hu He

    2015-03-01

    Full Text Available While several field investigations have demonstrated significant effects of cool season (winter or spring warming on phytoplankton development, the role played by large-bodied zooplankton grazers for the responses of phytoplankton to winter warming is ambiguous. We conducted an outdoor experiment to compare the effect of winter warming (heating by 3°C in combination with presence and absence of Daphnia grazing (D. similis on phytoplankton standing crops and community structure under eutrophic conditions. When Daphnia were absent, warming was associated with significant increases in phytoplankton biomass and cyanobacterial dominance. In contrast, when Daphnia were present, warming effects on phytoplankton dynamics were offset by warming-enhanced grazing, resulting in no significant change in biomass or taxonomic dominance. These results emphasize that large-bodied zooplankton like Daphnia spp. may play an important role in modulating the interactions between climate warming and phytoplankton dynamics in nutrient rich lake ecosystems.

  19. Solar Irradiance Changes and Phytoplankton Productivity in Earth's Ocean Following Astrophysical Ionizing Radiation Events.

    Science.gov (United States)

    Neale, Patrick J; Thomas, Brian C

    2016-04-01

    Two atmospheric responses to simulated astrophysical ionizing radiation events significant to life on Earth are production of odd-nitrogen species, especially NO2, and subsequent depletion of stratospheric ozone. Ozone depletion increases incident short-wavelength ultraviolet radiation (UVB, 280-315 nm) and longer (>600 nm) wavelengths of photosynthetically available radiation (PAR, 400-700 nm). On the other hand, the NO2 haze decreases atmospheric transmission in the long-wavelength UVA (315-400 nm) and short-wavelength PAR. Here, we use the results of previous simulations of incident spectral irradiance following an ionizing radiation event to predict changes in terran productivity focusing on photosynthesis of marine phytoplankton. The prediction is based on a spectral model of photosynthetic response, which was developed for the dominant genera in central regions of the ocean (Synechococcus and Prochlorococcus), and on remote-sensing-based observations of spectral water transparency, temperature, wind speed, and mixed layer depth. Predicted productivity declined after a simulated ionizing event, but the effect integrated over the water column was small. For integrations taking into account the full depth range of PAR transmission (down to 0.1% of utilizable PAR), the decrease was at most 2-3% (depending on strain), with larger effects (5-7%) for integrations just to the depth of the surface mixed layer. The deeper integrations were most affected by the decreased utilizable PAR at depth due to the NO2 haze, whereas shallower integrations were most affected by the increased surface UV. Several factors tended to dampen the magnitude of productivity responses relative to increases in surface-damaging radiation, for example, most inhibition in the modeled strains is caused by UVA and PAR, and the greatest relative increase in damaging exposure is predicted to occur in the winter when UV and productivity are low.

  20. Partitioning the Relative Importance of Phylogeny and Environmental Conditions on Phytoplankton Fatty Acids.

    Directory of Open Access Journals (Sweden)

    Aaron W E Galloway

    Full Text Available Essential fatty acids (EFA, which are primarily generated by phytoplankton, limit growth and reproduction in diverse heterotrophs. The biochemical composition of phytoplankton is well-known to be governed both by phylogeny and environmental conditions. Nutrients, light, salinity, and temperature all affect both phytoplankton growth and fatty acid composition. However, the relative importance of taxonomy and environment on algal fatty acid content has yet to be comparatively quantified, thus inhibiting predictions of changes to phytoplankton food quality in response to global environmental change. We compiled 1145 published marine and freshwater phytoplankton fatty acid profiles, consisting of 208 species from six major taxonomic groups, cultured in a wide range of environmental conditions, and used a multivariate distance-based linear model to quantify the total variation explained by each variable. Our results show that taxonomic group accounts for 3-4 times more variation in phytoplankton fatty acids than the most important growth condition variables. The results underscore that environmental conditions clearly affect phytoplankton fatty acid profiles, but also show that conditions account for relatively low variation compared to phylogeny. This suggests that the underlying mechanism determining basal food quality in aquatic habitats is primarily phytoplankton community composition, and allows for prediction of environmental-scale EFA dynamics based on phytoplankton community data. We used the compiled dataset to calculate seasonal dynamics of long-chain EFA (LCEFA; ≥C20 ɷ-3 and ɷ-6 polyunsaturated fatty acid concentrations and ɷ-3:ɷ-6 EFA ratios in Lake Washington using a multi-decadal phytoplankton community time series. These analyses quantify temporal dynamics of algal-derived LCEFA and food quality in a freshwater ecosystem that has undergone large community changes as a result of shifting resource management practices, highlighting

  1. Structure and dynamics of phytoplankton community in the Botafogo reservoir-Pernambuco-Brazil

    Directory of Open Access Journals (Sweden)

    Giulliari Alan da Silva Tavares de Lira

    2009-04-01

    Full Text Available The aim of the present study was to investigate the structure and dynamics of the phytoplankton in the Botafogo reservoir-PE-Brazil. Phytoplankton assemblages were identified from current literature and density was estimated using an inverted microscope. Concurrently to the sampling of biotic variables, measurements of abiotic parameters, such as water temperature, dissolved oxygen and pH, were determined using field probes and transparency was determined with a Secchi disk. Total phosphorus and total nitrogen concentrations were determined in laboratory. A total of 24 taxa were identified. Chlorophyta presented the greatest number of species. Species diversity in the reservoir was low throughout the study period. Principal component analysis revealed that Trachelomonas volvocina, Chlorella vulgaris, Euglena sp. and Peridinium gatunense were directly correlated with oxygen, turbidity and total nitrogen; Planktosphaeria gelatinosa, P. gatunense and Euglena sp. were directed correlated with total nitrogen; rainfall explained the occurrence of Monoraphidium arcuatum and Chlorella vulgaris.O objetivo do presente estudo foi investigar a estrutura e dinâmica do fitoplâncton no reservatório de Botafogo-PE-Brasil. A comunidade fitoplanctônica foi identificada com literatura atualizada e a densidade estimada usando microscópio invertido. Concomitantemente as coletas das variáveis bióticas, foram medidos alguns parâmetros abióticos como temperatura da água, oxigênio dissolvido, condutividade e pH usando sondas de campo e transparência com disco de Secchi. Concentrações de fósforo total e nitrogênio total foram determinados em laboratório. Vinte e quatro táxons foram identificados tendo Chlorophyta apresentado maior número de espécie. A diversidade de espécie no reservatório foi baixa durante todo o período de estudo. A análise de componentes principais mostrou que Trachelomonas volvocina, Chlorella vulgaris, Euglena sp. e

  2. Changing closed agricultural policy communities

    NARCIS (Netherlands)

    Termeer, C.J.A.M.; Werkman, R.A.

    2011-01-01

    Agricultural policy networks have served as classic examples of closed policy communities facing pressure to open up. However, attempts to change them are slowly moving forward. The dialogues on Common Agricultural Policy reforms in which the Dutch Ministry of Agriculture is engaged with a range of

  3. 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.

  4. Changes in N:P stoichiometry influence taxonomic composition and nutritional quality of phytoplankton in the Peruvian upwelling

    Science.gov (United States)

    Hauss, Helena; Franz, Jasmin M. S.; Sommer, Ulrich

    2012-10-01

    Inorganic dissolved macronutrient (nitrogen, N, and phosphorus, P) supply to surface waters in the eastern tropical South Pacific is influenced by expanding oxygen minimum zones, since N loss occurs due to microbial processes under anoxic conditions while P is increasingly released from the shelf sediments. To investigate the impact of decreasing N:P supply ratios in the Peruvian Upwelling, we conducted nutrient manipulation experiments using a shipboard mesocosm setup with a natural phytoplankton community. In a first experiment, either N or P or no nutrients were added with mesozooplankton present or absent. In a second experiment, initial nutrient concentrations were adjusted to four N:P ratios ranging from 2.5 to 16 using two "high N" and two "high P" levels in combination (i.e., + N, + P, + N and P, no addition). Over six and seven days, respectively, microalgal biomass development as well as nutrient uptake was monitored. Phytoplankton biomass strongly responded to N addition, in both mesozooplankton-grazed and not grazed treatments. The developing diatom bloom in the "high N" exceeded that in the "low N" treatments by a factor of two. No modulation of the total biomass by P-addition was observed, however, species-specific responses were more variable. Notably, some organisms were able to benefit from low N:P fertilization ratios, especially Heterosigma sp. and Phaeocystis globosa which are notorious for forming blooms that are toxic or inadequate for mesozooplankton nutrition. After the decline of the diatom bloom, the relative contribution of unsaturated fatty acid to the lipid content of seston was positively correlated to diatom biomass in the peak bloom, indicating that positive effects of diatom blooms on food quality of the protist community to higher trophic levels remain even after the phytoplankton biomass was incorporated by grazers. Our results indicate an overall N-limitation of the system, especially in the case of dominating diatoms, which were

  5. Phytoplankton community structure and nitrogen nutrition in Leeuwin Current and coastal waters off the Gascoyne region of Western Australia

    Science.gov (United States)

    Hanson, Christine E.; Waite, Anya M.; Thompson, Peter A.; Pattiaratchi, Charitha B.

    2007-04-01

    Within the coastal waters of the eastern Indian Ocean adjacent to Western Australia, we tested the hypothesis that regenerated production (and, by inference, the microbial food web) would predominate in oligotrophic Leeuwin Current (LC) and offshore (OS) surface waters. Conversely, we expected that new production would be more important within the ˜5 times more productive shelf countercurrents (Ningaloo and Capes Currents; NC&CC) and the LC&OS deep chlorophyll maximum (DCM). Phytoplankton species composition and abundance were assessed using both light microscopy and chemotaxonomic methods, and isotopic nitrogen uptake experiments ( 15NO 3-, 15NH 4+) were performed at trace (0.05 μM) and saturating (5.0 μM) levels. Phytoplankton community structure was statistically distinct between LC&OS and countercurrent regions. Picoplankton (unicellular cyanobacteria and prochlorophytes) accounted for a mean of 55-65% of pigment biomass in LC&OS waters, with haptophytes as the other primary contributor (21-32%). Conversely, within countercurrent and shelf regions, diatoms (up to 22%) and haptophytes (up to 57%) were more abundant, although cyanobacteria still played an important role (up to 40% of pigment biomass). Absolute NO 3- uptake rates for all samples ranged between 0.5 and 7.1 nmol L -1 h -1, and in countercurrent waters were not significantly different at the surface (3.0±2.1 nmol L -1 h -1; mean±SD) compared to the DCM (2.7±2.3 nmol L -1 h -1). However, in LC&OS waters, rates were significantly lower at the surface (1.2±0.7 nmol L -1 h -1) than the DCM (3.9±2.5 nmol L -1 h -1; p=0.05). These values represent conservative estimates for the region due to methodological difficulties encountered with nitrogen uptake experiments in these oligotrophic waters. In contrast with the distinct community composition between different water types, mean estimates of the f-ratio were similar across sampling depths and water types: 0.17±0.07 at the surface and 0.16±0.06 at

  6. PHYTOPLANKTON COMMUNITY VARIATION AND RELATIONSHIP WITH ENVIROMENTAL FACTORS IN QINGSHANHU RESERVOIR, ZHEJIANG PROVINCE%浙江青山水库浮游植物群落结构变化及与环境因子的关系

    Institute of Scientific and Technical Information of China (English)

    盛海燕; 姚佳玫; 何剑波; 刘明亮; 韩轶才; 虞左明

    2015-01-01

    ),Cyanophyta (17 species),Euglenophyta (6 species),other alges (6 species).The abundance of phytoplankton cells varied from 6.20 × 105 to 1.18× 107 cells/L (averaging 4.88 × 107 cells/L).The main physical and chemical indicators results showed that the water quality of Qingshan Reservoir was in the lightmiddle eutrophic state.The trophic state index was higher in inflow than in center and dam sites.The concentrations of total nitrogen and total phosphorus were higher than the surface water quality standards Ⅳ value.The indices of Shannon-Wiener,Margalef and Pielou Evenness were 1.37-2.23 (averaging 1.79),0.56-1.52 (averaging 1.05) and 0.45-0.77 (averaging 0.64),respectively.The dominant species of each month were identified and their contribution to the total abundance was analyzed.The seasonal variation of phytoplankton community structure was significant.In spring Bacillariophyta,Cryptophyta and Pyrrophyta dominated,in summer Cyanophyta and Chlorophyta dominated,in autumn Cyanophyta,Bacillariophyta and Cryptophyta,and in winter Bacillariophyta and Cryptophyta.The relationship between phytoplankton and environmental factors were discussed.Correlation analysis showed that there was significant negative correlation between phytoplankton density and transparency,inflow,outflow,and significant positive correlation between phytoplankton density and TP.Canonical correspondence analysis (CCA) showed that the inflow,outflow,water temperature,dissolved oxygen and nutrients were important environmental factors affecting the distribution pattern of phytoplankton.Qingshan Reservoir is located in a typical subtropical monsoon climate area,seasonal changes in the density of phytoplankton communities significantly affected by seasonal changes in watershed hydrology,and in particular,rainfall,temperature and hydraulic retention time are the main factors affecting phytoplankton community.

  7. Revaluating ocean warming impacts on global phytoplankton

    Science.gov (United States)

    Behrenfeld, Michael J.; O'Malley, Robert T.; Boss, Emmanuel S.; Westberry, Toby K.; Graff, Jason R.; Halsey, Kimberly H.; Milligan, Allen J.; Siegel, David A.; Brown, Matthew B.

    2016-03-01

    Global satellite observations document expansions of the low-chlorophyll central ocean gyres and an overall inverse relationship between anomalies in sea surface temperature and phytoplankton chlorophyll concentrations. These findings can provide an invaluable glimpse into potential future ocean changes, but only if the story they tell is accurately interpreted. Chlorophyll is not simply a measure of phytoplankton biomass, but also registers changes in intracellular pigmentation arising from light-driven (photoacclimation) and nutrient-driven physiological responses. Here, we show that the photoacclimation response is an important component of temporal chlorophyll variability across the global ocean. This attribution implies that contemporary relationships between chlorophyll changes and ocean warming are not indicative of proportional changes in productivity, as light-driven decreases in chlorophyll can be associated with constant or even increased photosynthesis. Extension of these results to future change, however, requires further evaluation of how the multifaceted stressors of a warmer, higher-CO2 world will impact plankton communities.

  8. Hydrology and phytoplankton community structure at Itamaracá-Pernambuco (Northeast Brazil

    Directory of Open Access Journals (Sweden)

    Maria Luise Koening

    1999-01-01

    Full Text Available Quali-quantitative studies and hydrologic parameters were carried out in the profiles 6 (Orange and 7 (Catuama during the Victor Hensen cruise, in accordance with the bilateral scientific cooperation agreement Brazil/Germany. Hydrologically a zone of thermic and saline stability characterizes the superficial layer. The nutrient concentrations were generally low on the surface and higher at levels surpassing 100m in depth. 102 taxa were identified including diatoms (49, dinoflagellates (49, bluegreen algae (3, and euglenophyceae (1. The diversity and evenness were high, surpassing the environmental equilibrium. The clustering of samples showed evidence of 2 main groups, one encompassing the stations 32 and 38, characterized predominantly by Oscillatoria erythraeum, and another encompassing the remaining stations, characterized by dinoflagellates and diatoms. The clustering of species involved 4 groups, the biggest being oceanic marine species (49 species and coastal and eurihaline marine species (31 species. The phytoplankton density varied from 50,000 cell.l-1 to 590,000 cell.l-1, characterizing an oligotrophic environment.Estudos hidrológicos e fitoplanctônicos foram realizados em dois perfis perpendiculares à costa, em frente à Ilha de Itamaracá-PE (perfis Orange e Catuama, durante a Expedição do Navio de Pesquisas Victor Hensen, dentro do acordo de cooperação bilateral celebrado entre o Departamento de Oceanografia da UFPE e o Centro de Ecologia Marinha Tropical (ZMT-Bremen-Alemanha. A camada superficial está caracterizada por uma zona de estabilidade térmica e salina. As concentrações de nutrientes foram geralmente mais baixas na superfície e mais elevadas em profundidades acima de 100m. Foram identificados 102 táxons, incluindo 49 diatomáceas, 49 dinoflagelados, 3 cianofíceas e 1 euglenofícea. A diversidade específica e equitabilidade foram elevadas, indicando um equilíbrio ambiental. A associação das amostras

  9. Protist community composition during early phytoplankton blooms in the naturally iron-fertilized Kerguelen area (Southern Ocean)

    Science.gov (United States)

    Georges, C.; Monchy, S.; Genitsaris, S.; Christaki, U.

    2014-10-01

    Microbial eukaryotic community composition was examined by 18S rRNA gene tag pyrosequencing, during the early phase of spring phytoplankton blooms induced by natural iron fertilization, off Kerguelen Island in the Southern Ocean (KEOPS2 cruise). A total of 999 operational taxonomical units (OTUs), affiliated to 30 known high-level taxonomic groups, were retrieved from 16 samples collected in the upper 300 m water column. The alveolata group was the most abundant in terms of sequence number and diversity (696 OTUs). The majority of alveolata sequences were affiliated to Dinophyceae and to two major groups of marine alveolates (MALV-I and MALV-II). In the upper 180 m, only 13% of the OTUs were shared between of the fertilized stations and the reference site characterized by high-nutrient low-chlorophyll (HNLC) waters. Fungi and Cercozoa were present in iron-fertilized waters, but almost absent in the HNLC samples, while Haptophyta and Chlorophyta characterized the HNLC sample. Finally, the 300 m depth samples of all stations were differentiated by the presence of MALV-II and Radiolaria. Multivariate analysis, examining the level of similarity between different samples, showed that protistan assemblages differed significantly between the HNLC and iron-fertilized stations, but also between the diverse iron-fertilized blooms.

  10. 新疆塘巴湖水库浮游植物群落组成特征%Ecological features of phytoplankton community of Tangbahu Reservoir in Xinjiang

    Institute of Scientific and Technical Information of China (English)

    薛俊增; 边佳胤; 王琼; 蔡桢; 朱新英; 李周永; 李海峰; 吴惠仙

    2012-01-01

    line has flinched 500 meters.It will make an impact in aquatic ecosystem.The phytoplankton which have an important impact on the plankton community,are major component groups of aquatic plankton.Phytoplankton community structure of Tangbahu Reservoir was investigated and analyzed in July 2008(the flow period),October 2008(the dry period) and May 2009(the flood period).Results showed that a total of 97 phytoplankton species,belonging to 8 phyla were identified,of which 43 species were Bacillariophyta,28 species were Chlorophyta,12 species were Cyanophyta,5 species were Euglenophyta,3 species were Cryptophyta,3 species were Xanthophyta,2 species were Pyrrophyta and 1 species were Chrysophyta.The number of species for Bacillariophyta,Chlorophyta,Cyanophyta,Euglenophyta,Cryptophyta,Xanthophyta,Pyrrophyta Chrysophyta accounted for 45%,29%,12%,5%,3%,3%,2% and 1% of the total species respectively.The trends of species changing showed: the flood period(56 species) the flow period(39 species) the dry period(19 species),the flood period and the flow period was made up by 8 phyla,but the dry period was made up by 6 phylathe.The dominance analysis showed that the phytoplankton community structure was typical type of Chlorella-diatoms in this reservoir.A.oscillarioides,M.aeruginisa,C.minor,C.bodanica,S.bijuga,W.botryoides,C.vulgaris and T.oblonga were the dominant species in the normalwater season.In the dry season,dominant species were M.flos-marginata,C.minor,M.granulata,C.debaryana,S.bijuga,C.vulgaris and C.erosaerosa.But in the wet season M.incerta Lemm,M.granulate,A.formosa,S.armatus,C.vulgaris,C.minima,C.erosaovata and G.aeruginosum were the dominant species.The phytoplankton in Tangbahu Reservoir showed larger alternation of hydro-period with the highest density(9.42±2.20×106 ind/L) in dry period,followed by the flow period(7.80±1.41×106 ind/L),the flood period was the lowest for 1.11±2.32×106 ind/L,it also had a very significant

  11. 万峰湖浮游植物群落的时空分布%Temporal and spatial characteristics of phytoplankton community in Wanfeng Reservoir.

    Institute of Scientific and Technical Information of China (English)

    李秋华; 商立海; 李广辉; 冯新斌; 闫海鱼

    2011-01-01

    于2009年9月(夏季)和2010年1月(冬季)对万峰湖(水库)的浮游植物群落结构时空分布特征进行研究.在万峰湖共监测到浮游植物49种,其中夏季水库表层(0-10 m)浮游植物优势种为蓝藻门中的拟柱孢藻(Cylindrospermopsis rackiborskii),底层为硅藻门中肘状针杆藻(Synedra ulna)和梅尼小环藻(Cyclotella meneghiniana);在冬季以硅藻门中的小环藻(Cyclotella sp.)和梅尼小环藻为主.夏季,浮游植物表层丰度为13.0×104~54.6×104 cells·L-1,野鸭滩(S2)最高,而以坝艾(S4)浮游植物丰度最低;浮游植物主要集中在表层(0~10 m),以蓝藻组成为主,蓝藻丰度百分数在大坝(S1)最高,达到90.3%,香浓多样性指数夏季高于冬季,夏季表层均匀度指数最低.冬季,浮游植物丰度为17.43×104~25.28×104 cells·L-1,浮游植物主要集中在表层(0~10 m)和中层(10~50 m),水体的各层硅藻所占比例均在90%以上.从浮游植物群落结构和丰度看,万峰湖处于中营养状态,冬季水质好于夏季.夏冬两季浮游植物丰度与水体的温度及水深都表现出了较强的相关关系.%To understand the temporal and spatial characteristics of phytoplankton community structure in Wanfeng, a deep altiplano reservoir, phytoplankton was measured in September, 2009 and January, 2010. Forty-nine species of algae were identified. In summer the community was dominated by Cylindrospermopsis rackiborskii at the surface (0-10 m) and at the bottom ( >60 m) Synedra ulna and Cyclotella meneghiniana became dominant, but in winter the community was dominated by Synedra ulna and Cyclotella meneghiniana. The phytoplankton abundance ranged from 13. 0×104 to 54. 6×104 cells · L-1 in summer and 17. 43 ×104 to 25. 28×104 cells · L-1 in winter. The maximum phytoplankton abundance was at Yeyatang ( S2) , but the minimum phytoplankton abundance was at Baai ( S4). In summer, phytoplankton collected at the surface ( 0-10 m) was primarily composed

  12. Changing restoration rules: exotic bivalves interact with residence time and depth to control phytoplankton productivity

    Science.gov (United States)

    Lucas, Lisa V.; Thompson, Janet K.

    2012-01-01

    Non-native species are a prevalent ecosystem stressor that can interact with other stressors to confound resource management and restoration. We examine how interactions between physical habitat attributes and a particular category of non-native species (invasive bivalves) influence primary production in aquatic ecosystems. Using mathematical models, we show how intuitive relationships between phytoplankton productivity and controllable physical factors (water depth, hydraulic transport time) that hold in the absence of bivalves can be complicated—and even reversed—by rapid bivalve grazing. In light-limited environments without bivalves, shallow, hydrodynamically “slow” habitats should generally have greater phytoplankton biomass and productivity than deeper, “faster” habitats. But shallower, slower environments can be less productive than deeper, faster ones if benthic grazing is strong. Moreover, shallower and slower waters exhibit a particularly broad range of possible productivity outcomes that can depend on whether bivalves are present. Since it is difficult to predict the response of non-native bivalves to habitat restoration, outcomes for new shallow, slow environments can be highly uncertain. Habitat depth and transport time should therefore not be used as indicators of phytoplankton biomass and production where bivalve colonization is possible. This study provides for ecosystem management a particular example of a broad lesson: abiotic ecosystem stressors should be managed with explicit consideration of interactions with other major (including biotic) stressors. We discuss the applicability and management implications of our models and results for a range of aquatic system types, with a case study focused on the Sacramento-San Joaquin Delta (California, USA). Simple mathematical models like those used here can illuminate interactions between ecosystem stressors and provide process-based guidance for resource managers as they develop strategies

  13. Microscopic examination on cytological changes in Allium cepa and shift in phytoplankton population at different doses of Atrazine

    Science.gov (United States)

    Ghosh, Nabarun; Finger, Kristen; Usnick, Samantha; Rogers, William J.; Das, A. B.; Smith, Don W.

    2010-06-01

    Atrazine is a wide-range herbicide. For over 50 years, atrazine has been used as a selective broadleaf herbicide in many capacities, from pre-plant to pre-emergence to post-emergence, depending on the crop and application. Currently, 96% of all atrazine used is for commercial applications in fields for the control of broadleaf and grassy weeds in crops such as sorghum, corn, sugarcane, pineapple and for the control of undesirable weeds in rangeland. Many panhandle wells have also detected atrazine in samples taken. The concern for the public is the long-term effect of atrazine with its increasing popularity, and the impact on public health. We investigated the effect of different concentrations of atrazine on Allium cepa (onion), a standard plant test system. We established a control with the Allium bulbs grown on hydroponics culture. Varying concentrations of atrazine was used on the standard plant test system, Allium cepa grown hydroponically. The mitotic indices varied and with higher doses, we observed various chromosomal abnormalities including sticky bridges, early and late separations, and lag chromosomes with higher doses of treatments. In the second part of the experiment, 0.1ppb, 1ppb, 10ppb, and 100ppb concentrations of atrazine were applied to established phytoplankton cultures from the Lake Tanglewood, Texas. Study with a Sedgwick-Rafter counter, a BX-40 Olympus microscope with DP-70 camera revealed a gradual shift in the phytoplankton community from obligatory to facultative autotroph and finally to a parasitic planktonic community. This explains the periodic fish kill in the lakes after applications of atrazine in crop fields.

  14. Graptolite community responses to global climate change and the Late Ordovician mass extinction

    Science.gov (United States)

    Sheets, H. David; Mitchell, Charles E.; Melchin, Michael J.; Loxton, Jason; Štorch, Petr; Carlucci, Kristi L.; Hawkins, Andrew D.

    2016-07-01

    Mass extinctions disrupt ecological communities. Although climate changes produce stress in ecological communities, few paleobiological studies have systematically addressed the impact of global climate changes on the fine details of community structure with a view to understanding how changes in community structure presage, or even cause, biodiversity decline during mass extinctions. Based on a novel Bayesian approach to biotope assessment, we present a study of changes in species abundance distribution patterns of macroplanktonic graptolite faunas (˜447-444 Ma) leading into the Late Ordovician mass extinction. Communities at two contrasting sites exhibit significant decreases in complexity and evenness as a consequence of the preferential decline in abundance of dysaerobic zone specialist species. The observed changes in community complexity and evenness commenced well before the dramatic population depletions that mark the tipping point of the extinction event. Initially, community changes tracked changes in the oceanic water masses, but these relations broke down during the onset of mass extinction. Environmental isotope and biomarker data suggest that sea surface temperature and nutrient cycling in the paleotropical oceans changed sharply during the latest Katian time, with consequent changes in the extent of the oxygen minimum zone and phytoplankton community composition. Although many impacted species persisted in ephemeral populations, increased extinction risk selectively depleted the diversity of paleotropical graptolite species during the latest Katian and early Hirnantian. The effects of long-term climate change on habitats can thus degrade populations in ways that cascade through communities, with effects that culminate in mass extinction.

  15. Graptolite community responses to global climate change and the Late Ordovician mass extinction.

    Science.gov (United States)

    Sheets, H David; Mitchell, Charles E; Melchin, Michael J; Loxton, Jason; Štorch, Petr; Carlucci, Kristi L; Hawkins, Andrew D

    2016-07-26

    Mass extinctions disrupt ecological communities. Although climate changes produce stress in ecological communities, few paleobiological studies have systematically addressed the impact of global climate changes on the fine details of community structure with a view to understanding how changes in community structure presage, or even cause, biodiversity decline during mass extinctions. Based on a novel Bayesian approach to biotope assessment, we present a study of changes in species abundance distribution patterns of macroplanktonic graptolite faunas (∼447-444 Ma) leading into the Late Ordovician mass extinction. Communities at two contrasting sites exhibit significant decreases in complexity and evenness as a consequence of the preferential decline in abundance of dysaerobic zone specialist species. The observed changes in community complexity and evenness commenced well before the dramatic population depletions that mark the tipping point of the extinction event. Initially, community changes tracked changes in the oceanic water masses, but these relations broke down during the onset of mass extinction. Environmental isotope and biomarker data suggest that sea surface temperature and nutrient cycling in the paleotropical oceans changed sharply during the latest Katian time, with consequent changes in the extent of the oxygen minimum zone and phytoplankton community composition. Although many impacted species persisted in ephemeral populations, increased extinction risk selectively depleted the diversity of paleotropical graptolite species during the latest Katian and early Hirnantian. The effects of long-term climate change on habitats can thus degrade populations in ways that cascade through communities, with effects that culminate in mass extinction.

  16. Seasonal characteristics of size-fractionated phytoplankton community and fate of photosynthesized carbon in a sub-Antarctic area (Straits of Magellan)

    Science.gov (United States)

    Decembrini, Franco; Bergamasco, Alessandro; Mangoni, Olga

    2014-08-01

    Phytoplankton community size drives the rates of biogenic carbon and the overall structure and dynamics of the marine pelagic food web. The Straits of Magellan, an inland passage between the Pacific and Atlantic Oceans, can be separated into three main sub-basins: the western-Pacific, the V-shaped central zone, and the eastern-Atlantic. To provide insights into the food structure of the phytoplankton community, size-fractionated chlorophyll a concentration and primary production rates were measured across the three sectors of the Magellan Straits in four periods between 1989 and 1995 in the Straits. Phytoplanktonic biomass and production ratios provided ecological insights into the food web structure, including the relevance of grazing in its largest fraction. The micro-phytoplanktonic fraction (> 10 μm) in the Pacific sub-basin is significantly less abundant than in the Central and Atlantic ones. Conversely, the lowest abundance of the pico-fraction (partially spilling out into the Atlantic sector. The most active grazing activities occur in the Central sub-basin during the spring bloom and appear even stronger in summer. Our results pinpoint also that the basic levels of the planktonic food web rely on the nanophytoplankton (10-2 μm) fraction, which is the main contributor to the continuum multivorous food web. When external energy (e.g. nutrient pulses from land freshwater and water mixing) enters the system, the structure of the plankton in the Straits shifts towards the herbivorous food web and is characterized by the presence of large-size diatoms. This dynamics keeps the system in a persistent mesotrophic state, featuring a lower trophic status than the Antarctic ones but much higher than that of oligotrophic temperate areas.

  17. Bacterial survival governed by organic carbon release from senescent oceanic phytoplankton

    Directory of Open Access Journals (Sweden)

    S. Lasternas

    2013-10-01

    Full Text Available Bacteria recycle vast amounts of organic carbon, playing key biogeochemical and ecological roles in the ocean. Bacterioplankton dynamics are expected to be dependent on phytoplankton primary production, but there is a high diversity of processes (e.g. sloppy feeding, cell exudation, viral lysis involved in the transference of primary production to dissolved organic carbon available to bacteria. Here we show cell survival of heterotrophic bacterioplankton in the subtropical Atlantic Ocean to be determined by phytoplankton extracellular carbon release (PER. PER represents the fraction of primary production released as dissolved organic carbon, and changes in the PER variability was explained by phytoplankton cell death, with the communities experiencing the highest phytoplankton cell mortality showing a larger proportion of extracellular carbon release. Both PER and the percent of dead phytoplankton cells increased from eutrophic to oligotrophic waters, while heterotrophic bacteria communities, including 60 to 95% of living cells (%LC, increased from the productive to the most oligotrophic waters. The percentage of living heterotrophic bacterial cells increased with increasing phytoplankton extracellular carbon release, across oligotrophic to productive waters in the NE Atlantic, where lower PER have resulted in a decrease in the flux of phytoplankton DOC per bacterial cell. The results highlight phytoplankton cell death as a process influencing the flow of dissolved photosynthetic carbon in the NE Atlantic Ocean, and demonstrated a close coupling between the fraction of primary production released and heterotrophic bacteria survival.

  18. Spring bloom community change modifies carbon pathways and C : N : P : Chl a stoichiometry of coastal material fluxes

    Directory of Open Access Journals (Sweden)

    K. Spilling

    2014-08-01

    Full Text Available Diatoms and dinoflagellates are major bloom-forming phytoplankton groups competing for resources in the oceans and coastal seas. Recent evidence suggests that their competition is significantly affected by climatic factors under ongoing change, modifying especially the conditions for cold-water, spring bloom communities in temperate and arctic regions. We investigated the effects of phytoplankton community composition on spring bloom carbon flows and nutrient stoichiometry in multi-year mesocosm experiments. Comparison of differing communities showed that community structure significantly affected C accumulation parameters, with highest particulate organic carbon (POC build-up and dissolved organic carbon (DOC release in diatom-dominated communities. In terms of inorganic nutrient drawdown and bloom accumulation phase, the dominating groups behaved as functional surrogates. Dominance patterns, however, significantly affected C : N : P : Chl a ratios over the whole bloom event: when diatoms were dominant, these ratios increased compared to dinoflagellate dominance or mixed communities. Diatom-dominated communities sequestered carbon up to 3.6-fold higher than the expectation based on the Redfield ratio, and 2-fold higher compared to dinoflagellate dominance. To our knowledge, this is the first experimental report of consequences of climatically driven shifts in phytoplankton dominance patterns for carbon sequestration and related biogeochemical cycles in coastal seas. Our results also highlight the need for remote sensing technologies with taxonomical resolution, as the C : Chl a ratio was strongly dependent on community composition and bloom stage. Climate-driven changes in phytoplankton dominance patterns will have far-reaching consequences for major biogeochemical cycles and need to be considered in climate change scenarios for marine systems.

  19. Relationship between bacteria and phytoplankton during the giant jellyfish Nemopilema nomurai bloom in an oligotrophic temperate marine ecosystem

    Institute of Scientific and Technical Information of China (English)

    ZENG Yang; HUANG Xuguang; HUANG Bangqin; MI Tiezhu

    2016-01-01

    Bacterial abundance, phytoplankton community structure and environmental parameters were investigated to study the relationships between bacteria and phytoplankton during giant jellyfish Nemopilema nomurai blooms in the central Yellow Sea during 2013. N. nomurai appeared in June, increased in August, reached a peak and began to degrade in September 2013. Results showed that phosphate was possible a key nutrient for both phytoplankton and bacteria in June, but it changed to nitrate in August and September. Phytoplankton composition significantly changed that pico-phytoplankton relative biomass significantly increased, whereas other size phytoplankton significantly decreased during jellyfish bloom. In June, a significantly positive correlation was observed between chlorophyll a concentration and bacterial abundance (r=0.67, P0.05, n=25), but the relationship (r=0.71, P<0.001, n=31) was rebuilt with jellyfish degradation in September. In August, small size phytoplankton occupied the mixed layer in offshore stations, while bacteria almost distributed evenly in vertical. Chlorophyll a concentration significantly increased from (0.42±0.056) μg/L in June to (0.74±0.174) μg/L in August , while bacterial abundance just slightly increased. Additionally, the negative net community production indicated that community respiration was not entirely determined by the local primary productivity in August. These results indicated that jellyfish blooms potentially affect coupling of phytoplankton and bacteria in marine ecosystems.

  20. Community structure of phytoplankton in Baishi Reservoir%白石水库浮游植物的群落结构研究

    Institute of Scientific and Technical Information of China (English)

    李沂軒; 鞠哲; 赵文; 班艳丽; 郭凯; 蔡志龙; 张荣坤; 戴玉新

    2016-01-01

    Phytoplankton community structure including species composition, dominant species, density, biomass, biodiversity , and spatial-temporal pattern of phytoplankton was monthly surveyed from August 2013 to July 2014 in order to provide scientific basis for sustainable water conservation and fisheries in Baishi Reservoir. Results showed that 239 phytoplankton species were found, including 138 species in Chlorophyta, 39 species in Bacillariophyta, 26 species in Euglenophyta, 19 species in Cyanophyta, 8 species in Pyrrophyta, 3 species in Chrysophyta, 3 species in Cryptophyta and 3 species in Xanthophyta, with dominant species Phormidium tenue, Cryptomonas erosa, and Synedra acus. There were phytoplankton density of 13. 44í106 cells/L, and the biomass of 11. 33 mg/L, with the dominant species in Bacillariophyta, Cryptophyta and Cyanobacteria. The phytoplankton had significant variation in spatial and temporal distribution in community structure, the order of density variation of phytoplankton as summer>autumn>spring>winter and as Linghe >Mangniu >upstream >downstream >midstream in spatial profile. Accord-ing to the criteria of the classification of phytoplankton biomass, Baishi Reservoir is within eutrophic, with evenness index of 0 . 24-0 . 48 , an average of 0 . 36 , diversity index of 1 . 73-3 . 44 , an average of 2 . 61 , indicating that the reservoir is moderately polluted due to nitrogen and phosphorus which have a significant impact on the growth of phytoplankton.%为给白石水库生态环境保护和渔业可持续发展提供科学依据和基础资料,于2013年8月—2014年7月对白石水库的浮游植物群落结构,包括浮游植物的种类组成、优势种、密度、生物量、生物多样性和时空格局进行了周年研究。结果表明:白石水库共发现浮游植物239种,其中绿藻138种,硅藻39种,裸藻26种,蓝藻19种,甲藻8种,金藻、隐藻、黄藻各3种;主要优势种为小席藻Phormidium tenue

  1. Community Organizing and Educational Change: A Reconnaissance

    Science.gov (United States)

    Shirley, Dennis

    2009-01-01

    Ten years ago community organizing as a form of educational change had only begun to challenge traditional models of school reform. Yet a decade later, community organizing has led to important changes in school and community relationships that have been documented by scholars in the areas of education, sociology, social work, and political…

  2. Resolving Changing Chemical and Physical Properties of SSA Particle Types during Laboratory Phytoplankton Blooms using Online Single Particle Analysis

    Science.gov (United States)

    Sultana, C. M.; Prather, K. A.; Richardson, R.; Wang, X.

    2015-12-01

    Changes in the chemical composition of sea spray aerosols (SSA) can modify their climate-relevant properties. Recent studies have shown a diverse set of distinct SSA particle types, however there are conflicting reports on how and whether biological activity controls the organic fraction and mixing state of SSA. This study leverages an aerosol time-of-flight mass spectrometer to give an accounting of the temporally resolved mixing state of primary SSA (0.4 - 3 µm vacuum aerodynamic diameter), encompassing 97% of particles detected over the course of laboratory phytoplankton blooms. The influence of biological activity on the climate relevant properties of defined particle types is also investigated. Spatial chemical particle heterogeneity and particularly the surface chemical composition of particles are described along with particle type specific water-particle interactions. These online measurements in tandem with chemical composition could give new insight on the link between seawater chemistry, marine aerosols, and climate properties.

  3. Phytoplankton diversity, biomass, and production

    Digital Repository Service at National Institute of Oceanography (India)

    Madondkar, S.G.P.; Gomes, H.; Parab, S.G.; Pednekar, S.; Goes, J.I.

    of the standing stock and organic productivity of an estuary. These variables have often been utilized to evaluate the overall health of an estuarine ecosystem and in management strategies to ensure sustainable use of the estuaries. Earlier investigations...) 2002. in the Zuari (1.02?3.07 ? 105 cellsl-1), suggesting that the phytoplankton species in the Zuari were more amenable to freshwater as compared to those in the Mandovi. The presence of a prominent community of freshwater phytoplankton was evident...

  4. 安徽菜子湖浮游植物群落结构的周年变化(2010年)%Annual dynamics of phytoplankton abundance and community structure (2010) in Lake Caizi, Anhui Province

    Institute of Scientific and Technical Information of China (English)

    刘雪花; 赵秀侠; 高攀; 韩飞园; 周非; 周忠泽; 徐慧琴

    2012-01-01

    The annual dynamics of phytoplankton community structure in Lake Caizi has been investigated in 2010. The results indicated that; ( 1) A total of 285 phytoplankton species from 110 genera of 8 phylum were identified. Phytoplankton species composition in different months showed significant difference. The maximal number of phytoplankton species (173) occurred in March while the minimum (105) in January. The dominant class of phytoplankton changed seasonally. Cyanophyta peaked all the year round; diatoms had an apparent dominance in January, May, September and November; Xanthophyta also played an important role in January, March and May; Chlorophyta dominated in November, Cryptophyta dominated in May while Chrysophyta dominated in January. The cell density and biomass of phytoplankton were higher in summer and autumn than that in winter and spring. The cell density of phytoplankton between different months had significant difference. The maximal density, with the value (66. 13 ?8. 58 ) x 105 cells/L occurred in July while the minimal value of (12.78 ?. 61 ) x 105 cells/L appeared in January. Whereas, the maximal biomass of phytoplankton(2. 80 ?. 17 mg/L) occurred in September and the minimal(0. 72 ?. 03 mg/L) appeared in May, and the biomass in different months was also significant different. (2) Temporal variations of three indices (including Margalef index, Shannon-Wiener index and Pielou evenness index) were obvious. All the indices were higher in winter and spring than those in summer and autumn. The maximal value occurred in March while the minimal one appeared in July. ( 3 ) The phytoplankton community structure was influenced by different factors in different months. As a result, the groups of sampling station changedseasonally according to cluster analysis. (4) The obvious variation of phytoplankton community structure was present in 2010 compared with that in 2007. The number of species decreased from 340 in 2007 to 285 in 2010, however, the cell density

  5. Atlantic advection driven changes in glacial meltwater: Effects on phytoplankton chlorophyll-a and taxonomic composition in Kongsfjorden, Spitsbergen.

    NARCIS (Netherlands)

    van de Poll, Willem; Maat, Douwe S.; Fischer, Philipp; Rozema, Patrick; Daly, Oonagh; Koppelle, Sebastiaan; Visser, Ronald; Buma, Anita

    2016-01-01

    Phytoplankton biomass and composition was investigated in a high Arctic fjord (Kongsfjorden, 79°N, 11°40′E) using year round weekly pigment samples collected from October 2013 to December 2014. In addition, phytoplankton dynamics supplemented with physical and chemical characteristics of the 2014 sp

  6. Community Capitals as Community Resilience to Climate Change: Conceptual Connections.

    Science.gov (United States)

    Kais, Shaikh Mohammad; Islam, Md Saidul

    2016-12-06

    In the last few decades, disaster risk reduction programs and climate initiatives across the globe have focused largely on the intimate connections between vulnerability, recovery, adaptation, and coping mechanisms. Recent focus, however, is increasingly paid to community resilience. Community, placed at the intersection between the household and national levels of social organization, is crucial in addressing economic, social, or environmental disturbances disrupting human security. Resilience measures a community's capability of bouncing back-restoring the original pre-disaster state, as well as bouncing forward-the capacity to cope with emerging post-disaster situations and changes. Both the 'bouncing back' and 'moving forward' properties of a community are shaped and reshaped by internal and external shocks such as climate threats, the community's resilience dimensions, and the intensity of economic, social, and other community capitals. This article reviews (1) the concept of resilience in relation to climate change and vulnerability; and (2) emerging perspectives on community-level impacts of climate change, resilience dimensions, and community capitals. It argues that overall resilience of a place-based community is located at the intersection of the community's resilience dimensions, community capitals, and the level of climate disruptions.

  7. Structure of late summer phytoplankton community in the Firth of Lorn (Scotland) using microscopy and HPLC-CHEMTAX

    Science.gov (United States)

    Brito, Ana C.; Sá, Carolina; Mendes, Carlos R.; Brand, Tim; Dias, Ana M.; Brotas, Vanda; Davidson, Keith

    2015-12-01

    The Firth of Lorn is at the mouth of one of Scotland's largest fjordic sea lochs, Loch Linnhe. This sea loch, which is fed by a number of other inner lochs, supplies a significant flow of freshwater, which frequently causes the stratification of the water column. To investigate how environmental conditions influence the spatial distribution of phytoplankton in this region water samples were collected for phytoplankton (pigments and microscopy), and other environmental variables including nutrients. Chemotaxonomy was used to estimate the contribution of different taxonomic groups to total chlorophyll a (phytoplankton biomass index). Good agreement was obtained between chemotaxonomy and microscopy data. The highest levels of chlorophyll a (˜2.6 mg m-3) were found in the vicinity of Oban Bay, where cryptophytes, the most abundant group, dinoflagellates and other flagellates thrived in the stratified water column. Centric diatoms, mainly Chaetoceros sp. and Skeletonema costatum, were associated with NH4 and SiO2 concentrations and stratification, while pennate diatoms, mainly Cylindrotheca sp. and Nitzchia sp., were found to be associated with NO3 + NO2 and high surface mixed layer depths. Four diatom groups were identified in accordance to their surface to volume ratios, as well as their affinity to environmental parameters (nutrients) and turbulence. This study used a combination of physico-chemical data, classical microscopy methods (appropriate for large cells > 20 μm) and HPLC-CHEMTAX approaches (for large and small cells) to evaluate the distribution of phytoplankton functional groups in a fjordic coastal area.

  8. A numerical index for evaluating phytoplankton response to changes in nutrient levels in deep mediterranean reservoirs

    Directory of Open Access Journals (Sweden)

    Nicola SECHI

    2009-02-01

    Full Text Available This paper proposes a new ecological index based on phytoplankton (MedPTI as suggested by the European Directive 2000/60/CE, Water Framework Directive (WFD. The index is a useful tool to verify the impacts of eutrophication in Mediterranean reservoirs belonging to different categories of the WFD. Multiple data sets were employed to develop the MedPTI index. The calibration data set included data collected from 30 Sardinian reservoirs in 1994. A list of 44 selected taxa was obtained and used for index calculation. A second dataset including 48 averaged annual values from 10 reservoirs was used. Results showed good correlation between MedPTI and concentration of total phosphorus, which was the limiting nutrient in these reservoirs. The trophic classifications determined using the index agreed with the results from the OECD probabilistic model on the same series of data. Finally, the index was included in an international exercise to compare the definition of reference conditions and quality class boundaries against indices used in other Mediterranean countries.

  9. Global Patterns of Phytoplankton Dynamics in Coastal Ecosystems

    Science.gov (United States)

    Paerl, Hans; Yin, Kedong; Cloern, James

    2011-03-01

    Scientific Committee on Ocean Research Working Group 137 Meeting; Hangzhou, China, 17-21 October 2010; Phytoplankton biomass and community structure have undergone dramatic changes in coastal ecosystems over the past several decades in response to climate variability and human disturbance. These changes have short- and long-term impacts on global carbon and nutrient cycling, food web structure and productivity, and coastal ecosystem services. There is a need to identify the underlying processes and measure the rates at which they alter coastal ecosystems on a global scale. Hence, the Scientific Committee on Ocean Research (SCOR) formed Working Group 137 (WG 137), “Global Patterns of Phytoplankton Dynamics in Coastal Ecosystems: A Comparative Analysis of Time Series Observations” (http://wg137.net/). This group evolved from a 2007 AGU-sponsored Chapman Conference entitled “Long Time-Series Observations in Coastal Ecosystems: Comparative Analyses of Phytoplankton Dynamics on Regional to Global Scales.”

  10. Nitrogen and phosphorus intake by phytoplankton in the Xiamen Bay

    Institute of Scientific and Technical Information of China (English)

    林彩; 林辉; 贺青; 许焜灿; 吴省三; 张元标; 陈金民; 陈宝红; 林力斌; 卢美鸾; 陈维芬; 汤荣坤; 暨卫东

    2010-01-01

    This paper describes a time series experiment examining the nitrogen and phosphorus intake of natural phytoplankton communities by a microcosms approach.Seawater samples containing natural phytoplankton communities were collected from waters around Baozhu Islet in inner Xiamen Bay and around Qingyu Islet in the outer bay.The goal was to elucidate the relationship between phytoplankton population enhancement,the biological removal of nitrogen and phosphorus from the seawater,and the phytoplankton nitrogen an...

  11. 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.

  12. Early Growth of Phytoplankton Community in Dianshan Lake%淀山湖浮游藻类群落的早期增长

    Institute of Scientific and Technical Information of China (English)

    程曦; 李小平

    2011-01-01

    Seasonal variation of phytoplankton community biomass(Chla) in Dianshan Lake was simulated based on data of 2004-2009.The result showed that early growths of the phytoplankton community in spring and summer seasons could be well described by the Logistic growth model.General speaking,phytoplankton community dominated by diatom and green algae may enter its exponential phase in the late February,doubling its density within 18 days,and reaching its maximum growth rate of 29.4 μg·(L·month)-1 in the middle of March,blooming in June.Phytoplankton community dominated by blue green algae may enter its exponential phase in the middle June,doubling its density within 26 days,and reaching its maximum growth rate of 22.8 μg·(L·month)-1 in the middle of July,blooming during August-September.The general pattern of early growth of phytoplankton community may offer sound information for early warning and prevention of algal bloom.%对2004~2009年淀山湖浮游藻类群落生物量[以叶绿素a(Chla)表示]随时间的变化进行了数学模拟.模拟结果表明,Logistic增长模型能够很好地描述淀山湖浮游藻类群落春季和夏季的早期增长.一般说来,淀山湖春季以硅藻和绿藻为主的浮游藻类群落于2月下旬进入指数级增长,到3月上旬浮游藻类密度已经达到始盛点的2倍,浮游藻类密度的翻倍时间仅为18 d,到3月中旬浮游藻类群落的增长速度达到最大值29.4μg.(L.月)-1;6月可能形成浮游藻类水华.淀山湖夏季以蓝藻为主的浮游藻类群落于6月中下旬进入指数级增长,到7月中旬浮游藻类密度已经达到始盛点的2倍,浮游藻类密度的翻倍时间为26 d;到7月下旬浮游藻类群落的增长速度达到最大值22.8μg.(L.月)-1,8~9月可能形成蓝藻水华.淀山湖浮游藻类群落早期增长的一般规律,可以为浮游藻类水华的早期预警和预防提供科学依据.

  13. Seasonal dynamics of phytoplankton and planktonic protozoan communities in a northern temperate humic lake: diversity in a dinoflagellate dominated system.

    Science.gov (United States)

    Graham, J M; Kent, A D; Lauster, G H; Yannarell, A C; Graham, L E; Triplett, E W

    2004-11-01

    Species diversity and richness, and seasonal population dynamics of phytoplankton, planktonic protozoa, and bacterioplankton sampled from the epilimnion of Crystal Bog in 2000, were examined in order to test the hypothesis that these groups' diversity and abundance patterns might be linked. Crystal Bog, a humic lake in Vilas County, Wisconsin, is part of the North Temperate Lakes Long-Term Ecological Research Site. Phytoplankton and planktonic protozoa were identified and enumerated in a settling chamber with an inverted microscope. Bacterial cells were enumerated with the use of fluorescence 4', 6'-diamidino-2-phenylindole (DAPI)-staining procedures, and automated ribosomal intergenic spacer analysis (ARISA) was used to assess bacterioplankton diversity. Bacterial cell counts showed little seasonal variation and averaged 2.6 x 10(6) cells/mL over the ice-free season. Phytoplankton and planktonic protozoan numbers varied by up to two orders of magnitude and were most numerous in late spring and summer. Dinoflagellates largely dominated Crystal Bog throughout the ice-free period, specifically Peridiniopsis quadridens in the spring, Peridinium limbatum in summer, and Gymnodinium fuscum and P. quadridens in fall. Brief blooms of Cryptomonas, Dinobryon, and Synura occurred between periods of dinoflagellate domination. The dominant dinoflagellate, Peridinium limbatum, was calculated to have a growth rate of 0.065 day(-1) and a doubling time of 10.7 days. Heterotrophic nanoflagellates (HNFs) were a consistent component of the planktonic protozoa; seasonal patterns were determined for three genera of HNFs (Monosiga, Bicosoeca, and Desmarella moniliformis). Three genera of ciliates (Coleps, Strobilidium, and Strombidium) comprised the greater part of the planktonic protozoa in Crystal Bog. The number of species of planktonic protozoa was too low to calculate a diversity index. Shannon-Weaver diversity indices for phytoplankton and bacterioplankton in the epilimnion

  14. Alternating Current-Dielectrophoresis Collection and Chaining of Phytoplankton on Chip: Comparison of Individual Species and Artificial Communities

    Directory of Open Access Journals (Sweden)

    Coralie Siebman

    2017-01-01

    Full Text Available The capability of alternating current (AC dielectrophoresis (DEP for on-chip capture and chaining of the three species representative of freshwater phytoplankton was evaluated. The effects of the AC field intensity, frequency and duration on the chaining efficiency and chain lengths of green alga Chlamydomonas reinhardtii, cyanobacterium Synechocystis sp. and diatom Cyclotella meneghiniana were characterized systematically. C. reinhardtii showed an increase of the chaining efficiency from 100 Hz to 500 kHz at all field intensities; C. meneghiniana presented a decrease of chaining efficiency from 100 Hz to 1 kHz followed by a significant increase from 1 kHz to 500 kHz, while Synechocystis sp. exhibited low chaining tendency at all frequencies and all field intensities. The experimentally-determined DEP response and cell alignment of each microorganism were in agreement with their effective polarizability. Mixtures of cells in equal proportion or 10-times excess of Synechocystis sp. showed important differences in terms of chaining efficiency and length of the chains compared with the results obtained when the cells were alone in suspension. While a constant degree of chaining was observed with the mixture of C. reinhardtii and C. meneghiniana, the presence of Synechocystis sp. in each mixture suppressed the formation of chains for the two other phytoplankton species. All of these results prove the potential of DEP to discriminate different phytoplankton species depending on their effective polarizability and to enable their manipulation, such as specific collection or separation in freshwater.

  15. Monsoon-induced changes in the size-fractionated phytoplankton biomass and production rate in the estuarine and coastal waters of southwest coast of India.

    Science.gov (United States)

    Madhu, N V; Jyothibabu, R; Balachandran, K K

    2010-07-01

    Changes in the autotrophic pico- (0.2-2 microm), nano- (2-20 microm), and microplankton (>20 microm) biomass (chlorophyll a) and primary production were measured in the estuarine and coastal waters off Cochin, southwest coast of India during the onset and establishment of a monsoon. During this period, the estuary was dominated by nutrient-rich freshwater, whereas the coastal waters were characterized with higher salinity values (>30 psu) and less nutrients. The average surface chlorophyll a concentrations and primary production rates were higher in the estuary (average 13.7 mg m(-3) and 432 mgC m(-3) day(-1)) as compared to the coastal waters (5.3 mg m(-3) and 224 mgC m(-3) day(-1)). The nanoplankton community formed the major fraction of chlorophyll a and primary production, both in the estuary (average 85 +/- SD 8.3% and 81.2 +/- SD 3.2%) and the coastal waters (average 73.2 +/- SD 17.2% and 81.9 +/- 15.7%). Nanoplankton had the maximum photosynthetic efficiency in the coastal waters (average 4.8 +/- SD 3.9 mgC mgChl a m(-3) h(-1)), whereas in the estuary, the microplankton had higher photosynthetic efficiency (average 7.4 +/- 7 mgC mgChl a m(-3) h(-1)). The heavy cloud cover and increased water column turbidity not only limit the growth of large-sized phytoplankton in the Cochin estuary and coastal waters but also support the proliferation of nanoplankton community during the monsoon season, even though large variation in nanoplankton chlorophyll a and production exists between these two areas.

  16. Community Capitals as Community Resilience to Climate Change: Conceptual Connections

    Directory of Open Access Journals (Sweden)

    Shaikh Mohammad Kais

    2016-12-01

    Full Text Available In the last few decades, disaster risk reduction programs and climate initiatives across the globe have focused largely on the intimate connections between vulnerability, recovery, adaptation, and coping mechanisms. Recent focus, however, is increasingly paid to community resilience. Community, placed at the intersection between the household and national levels of social organization, is crucial in addressing economic, social, or environmental disturbances disrupting human security. Resilience measures a community’s capability of bouncing back—restoring the original pre-disaster state, as well as bouncing forward—the capacity to cope with emerging post-disaster situations and changes. Both the ‘bouncing back’ and ‘moving forward’ properties of a community are shaped and reshaped by internal and external shocks such as climate threats, the community’s resilience dimensions, and the intensity of economic, social, and other community capitals. This article reviews (1 the concept of resilience in relation to climate change and vulnerability; and (2 emerging perspectives on community-level impacts of climate change, resilience dimensions, and community capitals. It argues that overall resilience of a place-based community is located at the intersection of the community’s resilience dimensions, community capitals, and the level of climate disruptions.

  17. Monsoon driven changes in phytoplankton populations in the eastern Arabian Sea as revealed by microscopy and HPLC pigment analysis

    Digital Repository Service at National Institute of Oceanography (India)

    Parab, S.G.; Matondkar, S.G.P.; Gomes, H.; Goes, J.I.

    ). Accessory pigments can provide class-specific differentiation, allowing for the recognition of the eastern Arabian Sea. By comparing pigment signatures with information on phytoplankton species composition derived from microscopy, we have also attempted... that are strongly linked to monsoonal wind-driven forcing during the NE and SW monsoons (Goes et al., 1992; Banse and English, 1993, 2000; Madhu- pratap et al., 1996; Prasanna Kumar et al., 2001). The increase in phytoplankton biomass to bloom proportions during...

  18. Long-term changes in phytoplankton in a humic lake in response to the water level rising: the effects of beaver engineering on a freshwater ecosystem

    Directory of Open Access Journals (Sweden)

    Pęczuła W.

    2013-08-01

    Full Text Available Although water level changes are supposed to be a key factor affecting the functioning of lake ecosystems, knowledge on this topic is scarce, particularly for humic lakes. This paper presents the results of 18 years’ research on a small humic lake exposed to hydrological change (rising of the water level, which was induced by spontaneous colonization of the lake by the European beaver (Castor fiber L.. We put forward a hypothesis that this change will be reflected in the quantity and structure of summer phytoplankton due to expected changes in the water chemistry. We noted a statistically significant decrease in total phosphorus and calcium concentrations, electrolytic conductivity, and Secchi disc transparency, and an increase in water color. The phytoplankton structure changed, with cyanoprocaryota and greens decreasing and flagellates increasing. The alteration was observed in a lake which had previously been drained by ditches, so beaver damming appeared to cause the return of the lake to its original endorheic conditions as well as to a water chemistry and phytoplankton structure more typical of undisturbed humic lakes.

  19. 新疆乌伦古湖浮游植物群落结构%Phytoplankton community structure in Lake Ulungur in Xinjiang Uygur Autonomous Region

    Institute of Scientific and Technical Information of China (English)

    刘宇; 郝志才; 沈建忠; 李鸿; 赵永晶; 马徐发; 刘其根; 江敏; 董攸; 刘军

    2009-01-01

    characteristiscs for the dominant species. Raphidiopsis sinensia, Teraedron minimum, Selenastrum minutum, Chlorella vulgaris and Synedra acus were dominant species in the whole yesr, while Synedra ulna could only be found in spring, summer and autumn. Kirchneriella contorta and Chlorella ellipsoidea dominated in summer, and Chlorococcum infusionum and Treubaria crassispina dominated in winter. The standing crop of phytoplankton peaked only in summer with a hiomass of 6.77mg/L and the minimum biomass of 1.45mg/L occurred in winter. Compared with historical data, the phytoplankton composition had remarkable changes. The growth of green alga and diatom were most notable, while the number of the phytoplankton increased many fold in the past 30 years.

  20. Limited impact of ocean acidification on phytoplankton community structure and carbon export in an oligotrophic environment: Results from two short-term mesocosm studies in the Mediterranean Sea

    Science.gov (United States)

    Gazeau, F.; Sallon, A.; Pitta, P.; Tsiola, A.; Maugendre, L.; Giani, M.; Celussi, M.; Pedrotti, M. L.; Marro, S.; Guieu, C.

    2017-02-01

    Modifications in the strength of the biological pump as a consequence of ocean acidification, whether positive or negative, have the potential to impact atmospheric CO2 and therefore climate. So far, most plankton community perturbation studies have been performed in nutrient-rich areas although there are some indications that CO2-dependent growth could differ in nutrient-replete vs. -limited regions and with different community compositions. Two in situ mesocosm experiments were performed in the NW Mediterranean Sea during two seasons with contrasted environmental conditions: summer oligotrophic stratified waters in the Bay of Calvi vs. winter mesotrophic well-mixed waters in the Bay of Villefranche. Nine mesocosms were deployed for 20 and 12 d, respectively, and subjected to seven CO2 levels (3 controls, 6 elevated levels). Both phytoplankton assemblages were dominated by pico- and nano-phytoplankton cells. Although haptophyceae and dinoflagellates benefited from short-term CO2 enrichment in summer, their response remained small with no consequences on organic matter export due to strong environmental constraints (nutrient availability). In winter, most of the plankton growth and associated nutrient consumption occurred during the 4-day acidification period (before the experimental phase). During the remaining experimental period, characterized by low nutrient availability, plankton growth was minimal and no clear CO2-dependency was found for any of the tested parameters. While there is a strong confidence on the absence of significant effect of short-term CO2 addition under oligotrophic conditions, more investigations are needed to assess the response of plankton communities in winter when vertical mixing and weather conditions are major factors controlling plankton dynamics.

  1. Global change and terrestrial plant community dynamics.

    Science.gov (United States)

    Franklin, Janet; Serra-Diaz, Josep M; Syphard, Alexandra D; Regan, Helen M

    2016-04-05

    Anthropogenic drivers of global change include rising atmospheric concentrations of carbon dioxide and other greenhouse gasses and resulting changes in the climate, as well as nitrogen deposition, biotic invasions, altered disturbance regimes, and land-use change. Predicting the effects of global change on terrestrial plant communities is crucial because of the ecosystem services vegetation provides, from climate regulation to forest products. In this paper, we present a framework for detecting vegetation changes and attributing them to global change drivers that incorporates multiple lines of evidence from spatially extensive monitoring networks, distributed experiments, remotely sensed data, and historical records. Based on a literature review, we summarize observed changes and then describe modeling tools that can forecast the impacts of multiple drivers on plant communities in an era of rapid change. Observed responses to changes in temperature, water, nutrients, land use, and disturbance show strong sensitivity of ecosystem productivity and plant population dynamics to water balance and long-lasting effects of disturbance on plant community dynamics. Persistent effects of land-use change and human-altered fire regimes on vegetation can overshadow or interact with climate change impacts. Models forecasting plant community responses to global change incorporate shifting ecological niches, population dynamics, species interactions, spatially explicit disturbance, ecosystem processes, and plant functional responses. Monitoring, experiments, and models evaluating multiple change drivers are needed to detect and predict vegetation changes in response to 21st century global change.

  2. Community structure and its seasonal variation of phytoplankton in adjacent waters of Yangjiang Nuclear Power Plant%阳江核电站邻近水域浮游植物群落结构及其季节变化

    Institute of Scientific and Technical Information of China (English)

    王雨; 林茂; 陈兴群; 林更铭

    2012-01-01

    Based on three cruise surveys in 2009 and 2010, an investigation was carried out on the community structure and its seasonal variation of phytoplankton in the adjacent waters of the nuclear plant being constructed at the second stage in Yangjiang City of Guangdong Province. The water range affected by the thermal effluent and the effects of the nuclear plant on the phytoplankton were predicted. In 78 samples, a total of 125 species (including 2 varieties) were identified , belonging 50 genera of 6 classes, among which, diatoms were predominant in the species composition. Dinoflagellates contributed the second major group. Chromophyta abundance increased sharply in November but not reached the algae bloom threshold of cell abundance. The dominant species were Leptocylindrus danicus, Guinaridia striata, Skeletonema costatum, Pseud-onitzchia pungens, Melosira moniliformis, Phaeocystis globosa, Ceratium furca, and Chaetoceros densus. The species composition and phytoplankton cell abundance showed significant seasonal changes, with different high abundance regions. The seasonal average cell abundance of phytoplankton was (111.8±120.6)×103 cells ? L-1. The overall horizontal distribution of phytoplankton cell abundance had a trend of decreased from nearshore in east to offshore in southwest. The Shannon diversity index was coincident with Pielou evenness index. The low values of the two indices in November suggested that in the survey areas, phytoplankton community was unstable,and water quality was unhealthy. The potential water range affected by the thermal effluent was within 10 km. The seasonal variation of phytoplankton species composition indicated its flexibility to temperature. The occurrence of high abundance of Phaeocystis globosa should be paid attention. The high velocity of flow and the widen water area around Yangjiang Nuclear Power Plant benefited water exchange, and thus, the second-stage project of the Yangjiang Nuclear Power Plant would not make a

  3. Soil fungal community responses to global changes

    DEFF Research Database (Denmark)

    Haugwitz, Merian Skouw

    Global change will affect the functioning and structure of terrestrial ecosystems and since soil fungi are key players in organic matter decomposition and nutrient turnover, shifts in fungal community composition might have a strong impact on soil functioning. The main focus of this thesis...... composition of fungi, but the effects were generally limited to the litter layer and the uppermost humus layer (0-5 cm), which was unexpected considering the ecosystem had been manipulated for 18 years. Taken together the global change experiments altered the soil fungal communities and thereby highlight...... was therefore to investigate the impact of global environmental changes on soil fungal communities in a temperate and subartic heath ecosystem. The objective was further to determine global change effects on major functional groups of fungi and analyze the influence of fungal community changes on soil carbon...

  4. Effect of decreasing phosphorus in eutrophic water on the community structure of phytoplankton%富营养化水体降磷对浮游植物群落结构特征的影响

    Institute of Scientific and Technical Information of China (English)

    孟顺龙; 瞿建宏; 裘丽萍; 胡庚东; 范立民; 宋超; 吴伟; 陈家长; 徐跑

    2013-01-01

    示出试验组浮游植物多样性和均匀度优于对照组。研究表明富营养化水体降磷对浮游植物群落结构产生了明显影响,使群落结构处于更加复杂、完整和稳定的状态。%Phytoplankton is the base of material recycle and energy flow in aquatic ecosystem. As the primary producer, the community structure of phytoplankton influences the structure and function of aquatic ecosystem directly. In aquaculture research field, how to cultivate fish needing phytoplankton, which can maintain the ecosystem balance of aquaculture water area and provide food for farming fish, has been always an important problem and research hotspot. The effect of phosphorus change on the growth of phytoplankton had been researched by the method of adding phosphorus to test water. However, the effect of decreasing phosphorus in eutrophic water on the community structure of phytoplankton has not been reported yet. The effect of decreasing phosphorus in eutrophic water on the community structure of phytoplankton was researched by adding phosphorus removing agent to test water sampling from eutrophication lake and by the method of Pielou uniformity index, Mcnaughton predominance index and Shannon diversity index. Results showed that there were 6 classes including 29 species of phytoplankton had been recorded in the test water sampling from Lake Wuli. Among them, Chlorophyta was the predominant species, which had 14 species, accounted for 48.28%of the total species. Cyanophyta, Bacillariophyta, Cryptophyta, Euglenophyta, Pyrrophyta were recorded 7, 4, 2, 1, 1 species and accounted for 24.13%, 13.79%, 6.90%, 3.45%, 3.45%respectively. There no difference in the number of phytoplankton species, but the community structure of phytoplankton changed significantly after the phosphorus in eutrophic water was decreased. And the quantity of phytoplankton decreased significantly from 13 238.8×104 cells· L-1 to 3 997.5×104 cells· L-1, and the decrease ratio was 69

  5. Phytoplankton Community Structure in the Yangtze River Estuary and Its Relation to Environmental Factors%长江口浮游植物群落特征及其与环境的响应关系

    Institute of Scientific and Technical Information of China (English)

    李俊龙; 郑丙辉; 刘录三; 唐静亮

    2013-01-01

    seasons. CCA ordination analysis indicated that environmental factors play important roles in controlling the phytoplankton community structure, while the controlling factors vary with seasons. The primary factors affecting the structure of diatom community were identified to be CODMn and NO3 - -N content in April, to be SiO44--Si, NO3--N and PO43--P content in August, and to be PO43- -P and SiO4 4--Si in November. Contents of NH4 +-N , C0DMn, and NO3--N and the transparency were the main factors affecting the structure of dinoflagellates in April, August and November, respectively. These results indicated that environmental factors play important roles in the seasonal and spatial variations of phytoplankton community structure in Yangtze River estuary, and the major driving factors changed with seasonal changes.

  6. Changes in turbulent mixing shift competition for light between phytoplankton species

    NARCIS (Netherlands)

    J. Huisman; J. Sharples; J. Stroom; P.M. Visser; W.E.A. Kardinaal; J.M.H. Verspagen; B. Sommeijer

    2004-01-01

    The intriguing impact of physical mixing processes on species interactions has always fascinated ecologists. Here, we exploit recent advances in plankton models to develop competition theory that predicts how changes in turbulent mixing affect competition for light between buoyant and sinking phytop

  7. Soil bacterial community responses to global changes

    DEFF Research Database (Denmark)

    Bergmark, Lasse

    /change the microbial community towards a higher fungal dominance. That could lead to a change in the carbon and nutrient flow in soil. In Manuscript 2 the impact of climate change manipulations and the seasonal dynamics of soil fungi and bacterial communities are investigated. Our results show that the soil fungal......Soil bacteria and archaea are essential for ecosystem functioning and plant growth through their degradation of organic matter and turnover of nutrients. But since the majority of soil bacteria and archaea are unclassified and “nonculturable” the functionality of the microbial community and its...... overall importance for ecosystem function in soil is poorly understood. Global change factors may affect the diversity and functioning of soil prokaryotes and thereby ecosystem functioning. To gain a better understanding of the effects of global changes it is of fundamental importance to classify...

  8. [Phytoplankton community structure and assessment of water quality in the middle and lower reaches of Fenhe River].

    Science.gov (United States)

    Wang, Ai-Ai; Feng, Jia; Xie, Shu-Lian

    2014-03-01

    To understand the distribution of phytoplankton and the water quality in the middle and lower reaches of Fenhe River, 18 sampling sites were selected for specimen collection, species identification and data analysis. The results showed that: (1) There were 298 species of phytoplankton under the membership of 8 divisions and 96 genera, among which, Bacillariophyta was the dominant division, with a total of 127 species of 27 genera, followed by Chlorophyta, with 104 species of 41 genera, and Cyanophyta, with 45 species of 20 genera. Only 22 species of 8 genera belonged to Euglenophyta, Cryptophyta, Pyrrophyta, Chrysophyta and Xanthophyta. The number of species in wet season was higher than that in dry season at all sites. Dominant species included Cyclotella meneghiniana, Synedra acus, Navicula cryptocephala, Nitzschia palea of Bacillariophyta, Chlorella vulgaris of Chlorophyta, Oscillatoria tenuis, O. amphibia of Cyanophyta, most of which were indicator species of alpha- and beta-mesosaprobic type. Cell density was higher in wet season and lower in dry season. (2) Shannon-Wieaver species diversity index ranged from 1 to 3 basically. Margalef species richness index ranged from 0.5 to 2. Pielou evenness index ranged 0.3-0.8. (3) During the wet season, most dominant species of Chlorophyta and Euglenophyta had higher correlation with chemical oxygen demand (COD), conductivity and ammonia nitrogen. The dominant species of Cyanophyta were greatly influenced by the contents of water temperature and chromium (Cr). The distribution of dominant species of Bacillariophyta was complicatedly related with environmental factors. During the dry season, there was a higher correlation between the members of Cyanophyta and ammonia nitrogen, total phosphorus, COD. The species of Chlorophyta and Euglenophyta were mainly influenced by the dissolved oxygen and total phosphorus. The bacillariophytes were mainly related with total phosphorus, dissolved oxygen, pH and cadmium (Cd). In

  9. Yearly changes of phytoplankton in the ecological monitoring zone of Daya Bay%大亚湾生态监控区的浮游植物年际变化

    Institute of Scientific and Technical Information of China (English)

    王雨; 林茂; 林更铭; 王春光; 项鹏

    2012-01-01

    Based on a great deal of monitoring data and information obtained from National Oceanic Administration, the Third Institute of Oceanography and other authorities, the yearly changes and spatial variation of phytoplankton community in the Ecological Monitoring Zone of Daya Bay were studied. To assess the current status and further trend, the phytoplankton composition, abundance, dominant species, diversity and harmful algae bloom events from 2004 to 2007 were analyzed. Results showed that the main principal phytoplankton ecotypes were changed from warm-water species to eurythermy species. The species and abundance were yearly degressive. The distribution of phytoplankton abundance kept a trend of higher in the west coast and lower in the east and southeast coast, and higher alongshore and lower offshore. It is presented that the rich nutrients and warm water discharge affected the phytoplankton abundance. In the Ecological Monitoring Zone of Daya Bay the dominant species were mostly dia- tom with seasonal and yearly diversity and variability. Rhizosolenia alata f. gracillima was the predominant species in spring and Pseudo-nitzschia delicatissma was the predominant species in summer. Pyrrophyta started to be the ascendancy at the end of spring. The diversity of phytoplankton community was yearly decreased and the evenness of phytoplankton community was yearly increased. The unconventionality of phytoplankton multiplication led to lower diversity, species imbalance, monotony of community. Harmful algae bloom occurred frequently in spring and summer, and its frequency and classes were increased year by year. All of these indicated that the ecosystem of the Ecological Monitoring Zone of Daya Bay was vulnerable and undergoing a rapid deterioration.%依据国家海洋局、国家海洋局第三海洋研究所等权威机构2004~2007年所获的数据和资料,对大亚湾生态监控区近4a长时间尺度的浮游植物群落年际变化进行分析,

  10. 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.; Yoder, J. A.

    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

  11. Atlantic advection driven changes in glacial meltwater: Effects on phytoplankton chlorophyll-a and taxonomic composition in Kongsfjorden, Spitsbergen.

    Directory of Open Access Journals (Sweden)

    Willem Hendrik Van De Poll

    2016-10-01

    Full Text Available Phytoplankton biomass and composition was investigated in a high Arctic fjord (Kongsfjorden, 79˚N, 11˚40’E using year round weekly pigment samples collected from October 2013 to December 2014. In addition, phytoplankton dynamics supplemented with physical and chemical characteristics of the 2014 spring bloom (April –June 2014 were assessed in two locations in Kongsfjorden. The goal was to elucidate effects of Atlantic advection on spatial phytoplankton chlorophyll-a (chl-a and taxonomic composition. Chl-a declined during the polar night to a minimum of 0.01 mg m-3, followed by a 1000-fold increase until May 28. Atlantic advection prevented sea ice formation and increased springtime melting of marine terminating glaciers. This coincided with spatial and temporal differences in abundances of flagellates (prasinophytes, haptophytes, cryptophytes, and chrysophytes and diatoms in early spring. More flagellated phytoplankton were observed in the non-stratified central Kongsfjorden, whereas diatoms were more abundant in the stratified inner fjord. Contrasting conditions between locations were reduced when glacial melt water stratification expanded towards the mouth of the fjord, mediating a diatom dominated surface bloom at both locations. We suggest that glacial melt water governs spring bloom spatial timing and composition in the absence of sea ice driven stratification. The spring bloom exhausted surface nutrient concentrations by the end of May. The nutrient limited post bloom period (June-October was characterized by reduced biomass and pigments of flagellated phytoplankton, consisting of prasinophytes, haptophytes, chrysophytes and to a lesser extent cryptophytes and peridinin-containing dinoflagellates.

  12. 兴凯湖当壁镇湖区夏季浮游植物群落结构变化%Variations of Phytoplankton Community Structure in Dangbi Town of Xingkai Lake in Summer

    Institute of Scientific and Technical Information of China (English)

    李喆; 刘伟; 唐富江; 王继隆; 徐慧东

    2012-01-01

    Variations of phytoplankton community structure in Dangbi Town of Xingkai Lake was investigated in July 2009.The results showed that the phytoplankton assemblage was composed of 41 species in total,belonging to seven taxonomic groups.Chlorophyta were represented by the highest percentage of taxa(39.0%) followed by Bacillariophyta(24.4%).The average cell density of phytoplankton was 192.97×104ind·L-1 and the average biomass was 2.4605mg·L-1.Bacillariophyta were represented by the highest cell density(147.47×104ind·L-1) and biomass(2.2818mg·L-1).Dominant species concluded Bacillariophyta,Chlorophyta,Cyanophyta,Xanthophyta.Dominant species were Cyclotella comta,Melosira granulate,Chlorella vulgaris,Ocystis lacustris,Chroococcus minor and Tribonemn sp...The diversity of phytoplankton in that lake was abundant(the value of H’ was 2.09;the value of J was 0.56).Over time,there was little change in dominant species and large change in species composition,cell density and biomass.The later time was the lower X index was.Compared with data between 2001 and 2009,species composition and cell density of phytoplankton in Xingkai Lake declined slightly.Dominant species of Bacillariophyta and Cryptophyta declined and dominant species of Chlorophyta increased.The percentage of filamentous algae in dominant species was increasing.In addition,the biomass of phytoplankton rose in Xingkai Lake.At the same time,fish production potential tended to increase in Dangbi Town of Xingkai Lake.There were two purposes of this study.One purpose was to accumulate basic data of phytoplankton resources in Dangbi Town of Xingkai Lake.The other purpose was to provide reference data for fish feeding habits that was studied by co-workers in Xingkai Lake.%2009年夏季对兴凯湖当壁镇湖区浮游植物群落结构进行研究。结果表明,兴凯湖当壁镇湖区浮游植物共计7门41种属,绿藻、硅藻的种类为主,分别占39.0%、24.4%;数量、生物量均值分别为192.97

  13. Macroecological patterns in the distribution of marine phytoplankton

    DEFF Research Database (Denmark)

    Mousing, Erik Askov

    Marine phytoplankton are responsible for approximately half of the global total primary production. The photosynthesis they carry out sustains higher trophic levels in the marine ecosystem. Changes in phytoplankton community composition can have cascading effects on food web dynamics, total...... stratification limiting the flux of nutrients from the deep ocean). This affect has important implications for the global carbon cycle and should be included in future climate models. In manuscript II, changes in the mean cyst size of dinoflagellates are investigated in relation to temperature changes during...... in the 1970s. However, increasing silicate in the deep ocean over the same period has indicated that there is an overlooked source of silicate and has brought the paradigm of silica limitation into question. Here, it is shown that silicate-using protists became more diluted in the sediment after 1970...

  14. The relationship between phytoplankton distribution and water column characteristics in North West European shelf sea waters.

    Science.gov (United States)

    Fehling, Johanna; Davidson, Keith; Bolch, Christopher J S; Brand, Tim D; Narayanaswamy, Bhavani E

    2012-01-01

    Phytoplankton underpin the marine food web in shelf seas, with some species having properties that are harmful to human health and coastal aquaculture. Pressures such as climate change and anthropogenic nutrient input are hypothesized to influence phytoplankton community composition and distribution. Yet the primary environmental drivers in shelf seas are poorly understood. To begin to address this in North Western European waters, the phytoplankton community composition was assessed in light of measured physical and chemical drivers during the "Ellett Line" cruise of autumn 2001 across the Scottish Continental shelf and into adjacent open Atlantic waters. Spatial variability existed in both phytoplankton and environmental conditions, with clear differences not only between on and off shelf stations but also between different on shelf locations. Temperature/salinity plots demonstrated different water masses existed in the region. In turn, principal component analysis (PCA), of the measured environmental conditions (temperature, salinity, water density and inorganic nutrient concentrations) clearly discriminated between shelf and oceanic stations on the basis of DIN:DSi ratio that was correlated with both salinity and temperature. Discrimination between shelf stations was also related to this ratio, but also the concentration of DIN and DSi. The phytoplankton community was diatom dominated, with multidimensional scaling (MDS) demonstrating spatial variability in its composition. Redundancy analysis (RDA) was used to investigate the link between environment and the phytoplankton community. This demonstrated a significant relationship between community composition and water mass as indexed by salinity (whole community), and both salinity and DIN:DSi (diatoms alone). Diatoms of the Pseudo-nitzschia seriata group occurred at densities potentially harmful to shellfish aquaculture, with the potential for toxicity being elevated by the likelihood of DSi limitation of

  15. Dynamics of phytoplankton pigments in water and surface sediments of a large shallow lake

    Directory of Open Access Journals (Sweden)

    Ilmar Tõnno

    2011-06-01

    Full Text Available Our aim was to find out to which extent fossil phytoplankton pigments in the large shallow and turbid Lake Võrtsjärv carry information on the history of phytoplankton communities. For this purpose we examined how the changes in the pigment composition of surface sediments follow their changes in the water column. Depth-integrated lake water and surface sediment samples were collected weekly in May–October 2007. Considering cyanobacterial and diatom dominance in phytoplankton, we analysed fucoxanthin, diadinoxanthin and diatoxanthin as marker pigments for diatoms, zeaxanthin as a marker pigment for total cyanobacteria and canthaxanthin as a marker pigment for colonial cyanobacteria. Chlorophyll a and its derivative pheophytin a were applied as indicators for total phytoplankton. The dynamics of phytoplankton pigments in surface sediments generally did not follow their dynamics in the water column, possibly due to intensive resuspension and a high sedimentation rate in a large and shallow lake. It was noticed that the surface sediment carries information on pigment degradation intensity and on weight and size characteristics of phytoplankton cells, which affect their sinking and floating velocities. Higher pigment contents of sediment in spring were presumably caused by lower resuspension due to high water level and slower degradation in cold water. Pheophytin a and the marker pigments of cyanobacteria were found to be persistent against degradation in upper sediment layers, which makes them useful indicators for tracking the historical changes in phytoplankton communities also in a shallow lake. Sharp decrease in chemically unstable pigment contents between the sediment surface and deeper layers indicates that only the uppermost sediment surface is resuspended in Lake Võrtsjärv. The transformation of the diatom marker carotenoid diadinoxanthin to diatoxanthin was found to occur mainly in sediments and not in the water column, and the

  16. Phytoplankton community and water quality in guilin city section of Lijiang River in summer, China%漓江桂林市区段夏季浮游植物群落特征与水质评价

    Institute of Scientific and Technical Information of China (English)

    周振明; 陈朝述; 刘可慧; 李俊; 陈孟林; 蒋瑜; 于方明

    2014-01-01

    Phytoplankton plays a crucial role for primary productivity in aquatic ecosystems. The changes in community structure are related to the environmental conditions of water and directly affect the function of aquatic ecosystems; it is one of the important indicating factors of the quality of the water environment. In order to reveal the relationship between the structure of the phytoplankton community and the water quality of Lijiang River, the physical and chemical indicators and Phytoplankton community characteristics in the Guilin city section of Lijiang River (from Zhaojiaqiao village to Wangjia village) were investigated in August, 2012. The results showed that the contents of permanganate index (CODMn), total nitrogen (TN), total phosphorus (TP), ammonia (NH4+-N) were from 1.80 to 6.20, 1.12 to 2.68, 0.022 to 0.282 and 0.34 to 1.73 mg·L-1, respectively, which smoothly changed in the upstream and significantly increased in tributaries. A total of 128 species which belong to 60 genera of 7 phyla were identified in Lijiang River, including 50 species of Bacillariophyta (39.06%), 52 species of Chlorophyta (40.63%), 16 species of Cyanophyta (12.5%), 7 species of Euglenophyta (5.47%), 1 species of Pyrrophyta (0.78%), 1 species of Chrysophyta (0.78%) and 1 species of Xanthophyta (0.78%). The dominant species were S. tephanodiscus,C. pyrenoidosa, N.rhynchocephal, N.exigua,C.Bodanica,S.quadricandaandS. ulna. The cell abundance of phytoplankton ranged from 10.3×104 to 1047.0×104 ind.·L-1 and the average cell abundance was 474.7×104 ind.·L-1, which was the smallest in Zhaojiaqiao village and the largest in Nanxihe entrance; green algae was major on species and diatom was major on cell abundance and distribution of dominant species. Thus, Lijiang River could be classified as the diatom-green algae river. Shannon-Wiener and Simpson indexes of phytoplankton were from 1.60 to 4.27 and 2.24 to 12.74, indicating that the water quality of Lijiang River was cleaning

  17. Seasonal change of ice algal and phytoplankton assemblages in the Nella Fjord near Zhongshan Station, East Antarctica

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The ice algal and phytoplankton assemblages were studied from Nella Fjord near Zhongshan Station, East Antarctica from April 12 to December 30, 1992. Algal blooms occurred about 3 cm thick on the bottom of sea ice in late April and mid November to early December respectively, and a phytoplankton bloom appeared in the underlying surface water in mid December following the spring ice algal bloom. The biomass in ice bottom was 1 to 3 orders of magnitude higher than that of surface water. Amphiprora kjellmanii, Berkeleya sp., Navicula glaciei, Nitzschia barkelyi, N. cylindrus /N. curta, N. lecointei and Nitzschia sp. were common in the sea ice temporarily or throughout the study period. The biomass in a certain ice segment was decreased gradually and the dominant species were usually succeeded as the season went on. Nitzschia sublineata and Dactyliosolen antarctica were two seasonal dominant species only observed in underlying water column. The assemblages between bottom of ice and underlying surface water were different except when spring ice algae bloomed. The evidence shows that the ice algal blooms occurred mainly by in situ growth of ice algae, and the phytoplankton bloom was mostly caused by the release of ice algae.

  18. 2009年秋季长江安徽-江苏段浮游植物群落的种类组成与空间特征%Species Composition and Spatial Characteristics of the Phytoplankton Community in the Anhui-Jiangsu Reach of Yangtze River in Autumn, 2009

    Institute of Scientific and Technical Information of China (English)

    孟顺龙; 陈家长; 胡庚东; 吴伟; 瞿建宏; 范立民; 裘丽萍

    2011-01-01

    and Mcnaughton dominance index, and the spatial distribution characteristic of phytoplankton was analyzed according to the clustering analytical method simultaneously. The results showed that there were 5 classes, including 27 species of phytoplankton had been recorded in the Anhui-Jiangsu reach of Yangtze river in autumn. Among them,Bacillariophyta was the predominant species, which had 16 species, accounted for 59.3% of the total species.Chlorophyta was recorded 6 species, accounted for 22.2%. Cyanophyta, Cryptophyta and Euglenophyta were recorded 2, 2, 1 species each and accounted for 7.4%, 7.4%, 3.7% respectively. The predominant species of phytoplankton in the Anhui-Jiangsu reach of Yangtze river in autumn were Fragilaria crotonensis, Melosira italica, Navicula cryptocephala, Cyclotella and Chroomonas acuta. The phytoplankton abundance in the Anhui-Jiangsu reach of Yangtze river in autumn ranged from 5.68× 104 cells/L to 7.08× 104 cells/L, with the average of 6.01 × l04 cells/L, and the phytoplankton biomass ranged from 30.43 μg/L to 34.73 μg/L, with the average of 32.46 μg/L. The number of phytoplankton species decreased and the phytoplankton abundance and biomass increased compared with the results of previous studies, which meant that the water quality in the jiangsu reach of Yangtze river had deteriorated. However, Bacillariophyta was still the main predominant species and the phytoplankton community structure had not changed significantly compared with the results of previous studies, which meant that the water quality in the Jiangsu reach of Yangtze river had not deteriorated seriously. The results of similarity clustering of phytoplankton community indicated that the phytoplankton community at Nanjing, Wuhu and Jiangyin were similar and the phytoplankton community at tongling was similar to that at anqing.

  19. Networked Community Change: Understanding Community Systems Change through the Lens of Social Network Analysis.

    Science.gov (United States)

    Lawlor, Jennifer A; Neal, Zachary P

    2016-06-01

    Addressing complex problems in communities has become a key area of focus in recent years (Kania & Kramer, 2013, Stanford Social Innovation Review). Building on existing approaches to understanding and addressing problems, such as action research, several new approaches have emerged that shift the way communities solve problems (e.g., Burns, 2007, Systemic Action Research; Foth, 2006, Action Research, 4, 205; Kania & Kramer, 2011, Stanford Social Innovation Review, 1, 36). Seeking to bring clarity to the emerging literature on community change strategies, this article identifies the common features of the most widespread community change strategies and explores the conditions under which such strategies have the potential to be effective. We identify and describe five common features among the approaches to change. Then, using an agent-based model, we simulate network-building behavior among stakeholders participating in community change efforts using these approaches. We find that the emergent stakeholder networks are efficient when the processes are implemented under ideal conditions.

  20. 三峡水库洪水调度对香溪河藻类群落结构的影响%Effects of flood regulation on phytoplankton community structure in the Xiangxi River, a tributary of the Three Gorges Reservoir

    Institute of Scientific and Technical Information of China (English)

    彭成荣; 陈磊; 毕永红; 夏春香; 类咏梅; 杨毅; 简铁柱; 胡征宇

    2014-01-01

    Flood control is an important function for Three Gorges Reservoir (TGR). In July 2013 there was 3 flood peaks in TGR and flood regulation was used to block the deluge and reduce the impact on the middle and lower reaches of the Yangtze River. Anin situ investigation was conducted to screen the effects of flood regulation on phytoplankton community structure in the Xiangxi River. During the course of flood regulation, the water level in Xiangxi River ranged from 145.63m to 148.36m, the change of the average velocity in the estuary was higher than that in the midstream. There was a significant difference in average velocity between the estuary and midstream (P<0.05). Before the flood regulation, the dominant algal taxa were cyanophyta and bacillariophyta, cyanophyta had a higher proportion in both sampling sites. During the flood regulation period, hydrodynamic characteristics and algal community structure were significantly changed, Shannon-Weaver index decreased. After the flood regulation, diatoms were dominant in the midstream, while the proportion of cyanophyta increased gradually in the estuary. The flood regulation changed the environmental conditions. Hydrological and hydrodynamic characteristics in backwater caused by flooding regulation has been changed markedly, which influenced water quality of tributaries; consequently, followed by rapid changes in phytoplankton community. Results indicated the fluctuation of water level caused by flood regulation destroyed the habitat of algae strongly, and then leads to the changes of community structure. It could be deduced that such flood regulation would be helpful to inhibit and delay the formation of algal bloom in the tributaries of Three Gorges Reservoir.%以三峡大坝汛期洪水调度为契机,于2013年7月在香溪河开展原位监测,研究了洪水调度对藻类群落结构的影响.结果显示:在洪水调度期间香溪河水位变动范围是145.63~148.36m,河流中上游平均流速变化幅度

  1. Assessing spatial and temporal variability of phytoplankton communities' composition in the Iroise Sea ecosystem (Brittany, France): A 3D modeling approach. Part 1: Biophysical control over plankton functional types succession and distribution

    Science.gov (United States)

    Cadier, Mathilde; Gorgues, Thomas; Sourisseau, Marc; Edwards, Christopher A.; Aumont, Olivier; Marié, Louis; Memery, Laurent

    2017-01-01

    Understanding the dynamic interplay between physical, biogeochemical and biological processes represents a key challenge in oceanography, particularly in shelf seas where complex hydrodynamics are likely to drive nutrient distribution and niche partitioning of phytoplankton communities. The Iroise Sea includes a tidal front called the 'Ushant Front' that undergoes a pronounced seasonal cycle, with a marked signal during the summer. These characteristics as well as relatively good observational sampling make it a region of choice to study processes impacting phytoplankton dynamics. This innovative modeling study employs a phytoplankton-diversity model, coupled to a regional circulation model to explore mechanisms that alter biogeography of phytoplankton in this highly dynamic environment. Phytoplankton assemblages are mainly influenced by the depth of the mixed layer on a seasonal time scale. Indeed, solar incident irradiance is a limiting resource for phototrophic growth and small phytoplankton cells are advantaged over larger cells. This phenomenon is particularly relevant when vertical mixing is intense, such as during winter and early spring. Relaxation of wind-induced mixing in April causes an improvement of irradiance experienced by cells across the whole study area. This leads, in late spring, to a competitive advantage of larger functional groups such as diatoms as long as the nutrient supply is sufficient. This dominance of large, fast-growing autotrophic cells is also maintained during summer in the productive tidally-mixed shelf waters. In the oligotrophic surface layer of the western part of the Iroise Sea, small cells coexist in a greater proportion with large, nutrient limited cells. The productive Ushant tidal front's region (1800 mgC·m- 2·d- 1 between August and September) is also characterized by a high degree of coexistence between three functional groups (diatoms, micro/nano-flagellates and small eukaryotes/cyanobacteria). Consistent with

  2. Suitability of phytosterols alongside fatty acids as chemotaxonomic biomarkers for phytoplankton

    Directory of Open Access Journals (Sweden)

    Sami Johan Taipale

    2016-03-01

    Full Text Available e composition and abundance of phytoplankton is important factor defining ecological status of marine and freshwater ecosystems. Chemotaxonomic markers (e.g., pigments and fatty acids are needed for monitoring changes in phytoplankton community and to know nutritional quality of seston for herbivorous zooplankton. Here we investigated the suitability of sterols along with fatty acids as chemotaxonomic markers by analyzing sterol and fatty acid composition of 10 different phytoplankton classes including altogether 37 strains isolated from freshwater lakes and by using multivariate statistics. We were able to detect totally 47 fatty acids and 29 sterols in our phytoplankton samples, which both differed statistically significantly between phytoplankton classes. Due to the high variation of fatty acid composition among cyanobacteria, taxonomical differentiation increased, when cyanobacteria were excluded from statistical analysis. Sterol composition was more heterogeneous within class than fatty acids and did not improve separation of phytoplankton classes when used alongside with fatty acids. However, we conclude that sterols can provide additional information on the abundance of specific genera within a class which can be generated by using fatty acids. For example, whereas high 16 ω-3 PUFAs (polyunsaturated fatty acid indicates the presence of Chlorophyceae, simultaneous high amount of ergosterol could specify the presence of Chlamydomonas spp. (Chlorophyceae. Additionally, we found specific 4α-methyl sterols for distinct Dinophyceae genus, suggesting that 4α-methyl sterols can potentially separate freshwater dinoflagellates from each other.

  3. Competing phytoplankton undermines allelopathy of a bloom-forming dinoflagellate.

    Science.gov (United States)

    Prince, Emily K; Myers, Tracey L; Naar, Jerome; Kubanek, Julia

    2008-12-07

    Biotic interactions in the plankton can be both complex and dynamic. Competition among phytoplankton is often chemically mediated, but no studies have considered whether allelopathic compounds are modified by biotic interactions. Here, we show that compounds exuded during Karenia brevis blooms were allelopathic to the cosmopolitan diatom Skeletonema costatum, but that bloom allelopathy varied dramatically among collections and years. We investigated several possible causes of this variability and found that neither bloom density nor concentrations of water-borne brevetoxins correlated with allelopathic potency. However, when we directly tested whether the presence of competing phytoplankton influenced bloom allelopathy, we found that S. costatum reduced the growth-inhibiting effects of bloom exudates, suggesting that S. costatum has a mechanism for undermining K. brevis allelopathy. Additional laboratory experiments indicated that inducible changes to K. brevis allelopathy were restricted to two diatoms among five sensitive phytoplankton species, whereas five other species were constitutively resistant to K. brevis allelopathy. Our results suggest that competitors differ in their responses to phytoplankton allelopathy, with S. costatum exhibiting a previously undescribed method of resistance that may influence community structure and alter bloom dynamics.

  4. 洋山港浮游植物群落特征研究%ECOLOGICAL FEATURES OF PHYTOPLANKTON COMMUNITY OF YANGSHAN PORT

    Institute of Scientific and Technical Information of China (English)

    孙玲霜; 薛俊增; 庄骅; 王宝强; 吴惠仙

    2012-01-01

    洋山港是上海航运的枢纽港,2009年1月~12月对洋山港浮游植物群落进行了生态学研究,共鉴定浮游植物5门58属112种,合赤潮藻类5门21属34种,群落结构组成以硅藻为主.其中优势种由具槽帕拉藻(Paralia sulcata)、具翼漂流藻(Planktoniella blanda)、辐射圆筛藻(Coscinodiscus radiatus)、格氏圆筛藻(Coscinodiscus granii)、条纹小环藻(Cyclotella striata)、扭曲小环藻(Cyclotella comta)、菱形海线藻(Thalassionema nitzschioides)、尖刺伪菱形藻(Pseudo-nitzschia pungens)以及短柄曲壳藻(Achnanthes brevi pes)等构成.浮游植物细胞丰度变化范围是(6.15×104~1.39×104) ind/L,全年平均值为3.32×104 ind/L,11月细胞丰度达到最高值,其次为3月,呈现双峰型的周年变化规律.硅藻在全年的浮游植物细胞丰度组成中始终占据绝对优势地位.相关性分析发现,浮游植物细胞丰度、温度和溶解氧两两间呈现出极显著相关性(P<0.01),其中仅细胞丰度与溶解氧之间呈现正相关(r>0),其余两两间为负相关关系(r<0).%Yangshan port is a China's major port and is building into an international shipping center, and it affected by several water bodies. Phytoplankton community structure of Yangshan port was investigated and analyzed on January to December in 2009. A total of 112 phytoplankton species, belonging to 5 phylum 58 genus were identified, 34 species belonging to red tide phytoplankton, and diatom phylum played an important role in the community structure. Paralia sulcata, Planktoniella blanda, Coscinodiscus radiatus, Coscinodiscus granii, Cyclotella striata, Cyclotella comta, Thalassionema nitzschioides, Pseudo-nitzschia pungens as well as Achnanthes brevipes were the dominant species. The ranges of cell density were 6. 15 104ind/L to 1. 38 104ind/L, and the annual average was 3. 32 104ind/L. The cell density was greatest in November, and then was in March, two high peaks were found in the period of

  5. Phytoplankton Composition and Abundance in Restored Maltanski Reservoir under the Influence of Physico-Chemical Variables and Zooplankton Grazing Pressure.

    Directory of Open Access Journals (Sweden)

    Anna Kozak

    Full Text Available In this paper we present the effects of environmental factors and zooplankton food pressure on phytoplankton in the restored man-made Maltański Reservoir (MR. Two methods of restoration: biomanipulation and phosphorus inactivation have been applied in the reservoir. Nine taxonomical groups of phytoplankton represented in total by 183 taxa were stated there. The richest groups in respect of taxa number were green algae, cyanobacteria and diatoms. The diatoms, cryptophytes, chrysophytes, cyanobacteria, green algae and euglenophytes dominated in terms of abundance and/or biomass. There were significant changes among environmental parameters resulting from restoration measures which influenced the phytoplankton populations in the reservoir. These measures led to a decrease of phosphorus concentration due to its chemical inactivation and enhanced zooplankton grazing as a result of planktivorous fish stocking. The aim of the study is to analyse the reaction of phytoplankton to the restoration measures and, most importantly, to determine the extent to which the qualitative and quantitative composition of phytoplankton depends on variables changing under the influence of restoration in comparison with other environmental variables. We stated that application of restoration methods did cause significant changes in phytoplankton community structure. The abundance of most phytoplankton taxa was negatively correlated with large zooplankton filter feeders, and positively with zooplankton predators and concentrations of ammonium nitrogen and partly of phosphates. However, restoration was insufficient in the case of decreasing phytoplankton abundance. The effects of restoration treatments were of less importance for the abundance of phytoplankton than parameters that were independent of the restoration. This was due to the continuous inflow of large loads of nutrients from the area of the river catchment.

  6. Title: Freshwater phytoplankton responses to global warming.

    Science.gov (United States)

    Wagner, Heiko; Fanesi, Andrea; Wilhelm, Christian

    2016-09-20

    Global warming alters species composition and function of freshwater ecosystems. However, the impact of temperature on primary productivity is not sufficiently understood and water quality models need to be improved in order to assess the quantitative and qualitative changes of aquatic communities. On the basis of experimental data, we demonstrate that the commonly used photosynthetic and water chemistry parameters alone are not sufficient for modeling phytoplankton growth under changing temperature regimes. We present some new aspects of the acclimation process with respect to temperature and how contrasting responses may be explained by a more complete physiological knowledge of the energy flow from photons to new biomass. We further suggest including additional bio-markers/traits for algal growth such as carbon allocation patterns to increase the explanatory power of such models. Although carbon allocation patterns are promising and functional cellular traits for growth prediction under different nutrient and light conditions, their predictive power still waits to be tested with respect to temperature. A great challenge for the near future will be the prediction of primary production efficiencies under the global change scenario using a uniform model for phytoplankton assemblages.

  7. Supporting Community-Oriented Educational Change

    Directory of Open Access Journals (Sweden)

    Linda Mabry

    1999-04-01

    Full Text Available A study of a federally funded program to develop and implement community-oriented social studies curricula and curriculum-based assessments grounds cautions for educational change initiatives. In this case, despite the project director's stated intent to support teachers' desire for instruction regarding local culture and history, top-down support for classroom-level change evidenced insensitivity. Production and implementation of the planned curricula and assessments was obstructed by teacher's lack of cultural identification with the targeted community groups, workload, competing instructional priorities, inadequate communication, and organizational politics. Professional development was sometimes beneficial but more often ineffective—either perfunctory, unnecessary, or disregarded. The findings offer insight regarding educational change and a systemic analysis.

  8. The impact of climate on the geographical distribution of phytoplankton species in boreal lakes.

    Science.gov (United States)

    Hallstan, Simon; Trigal, Cristina; Johansson, Karin S L; Johnson, Richard K

    2013-12-01

    Here, we use a novel space-by-time approach to study large-scale changes in phytoplankton species distribution in Swedish boreal lakes in response to climate variability. Using phytoplankton samples from 27 lakes, evenly distributed across Sweden, all relatively unimpacted by anthropogenic disturbance and sampled annually between 1996 and 2010, we found significant shifts in the geographical distribution of 18 species. We also found significant changes in the prevalence of 45 species (33 became more common and 12 less common) over the study period. Using species distribution models and phytoplankton samples from 60 lakes sampled at least twice between 1992 and 2010, we evaluated the importance of climate variability and other environmental variables on species distribution. We found that temperature (e.g., extreme events and the duration of the growing season) was the most important predictor for species detections. Many cyanobacteria, chlorophytes, and, to a lesser extent, diatoms and zygnematophytes, showed congruent and positive responses to temperature. In contrast, precipitation explained little variation and was important only for a few taxa (e.g., Staurodesmus spp., Trachelomonas volvocina). At the community level, our results suggest a change in community composition at temperatures over 20 °C and growing seasons longer than 40 days. We conclude that climate is an important driver of the distributional patterns of individual phytoplankton species and may drive changes in community composition in minimally disturbed boreal lakes.

  9. Annual boom-bust cycles of polar phytoplankton biomass revealed by space-based lidar

    Science.gov (United States)

    Behrenfeld, Michael J.; Hu, Yongxiang; O'Malley, Robert T.; Boss, Emmanuel S.; Hostetler, Chris A.; Siegel, David A.; Sarmiento, Jorge L.; Schulien, Jennifer; Hair, Johnathan W.; Lu, Xiaomei; Rodier, Sharon; Scarino, Amy Jo

    2016-12-01

    Polar plankton communities are among the most productive, seasonally dynamic and rapidly changing ecosystems in the global ocean. However, persistent cloud cover, periods of constant night and prevailing low solar elevations in polar regions severely limit traditional passive satellite ocean colour measurements and leave vast areas unobserved for many consecutive months each year. Consequently, our understanding of the annual cycles of polar plankton and their interannual variations is incomplete. Here we use space-borne lidar observations to overcome the limitations of historical passive sensors and report a decade of uninterrupted polar phytoplankton biomass cycles. We find that polar phytoplankton dynamics are categorized by `boom-bust' cycles resulting from slight imbalances in plankton predator-prey equilibria. The observed seasonal-to-interannual variations in biomass are predicted by mathematically modelled rates of change in phytoplankton division. Furthermore, we find that changes in ice cover dominated variability in Antarctic phytoplankton stocks over the past decade, whereas ecological processes were the predominant drivers of change in the Arctic. We conclude that subtle and environmentally driven imbalances in polar food webs underlie annual phytoplankton boom-bust cycles, which vary interannually at each pole.

  10. Retrieving the vertical distribution of chlorophyll a concentration and phytoplankton community composition from in situ fluorescence profiles: A method based on a neural network with potential for global-scale applications

    Science.gov (United States)

    Sauzède, R.; Claustre, H.; Jamet, C.; Uitz, J.; Ras, J.; Mignot, A.; D'Ortenzio, F.

    2015-01-01

    neural network-based method is developed to assess the vertical distribution of (1) chlorophyll a concentration ([Chl]) and (2) phytoplankton community size indices (i.e., microphytoplankton, nanophytoplankton, and picophytoplankton) from in situ vertical profiles of chlorophyll fluorescence. This method (FLAVOR for Fluorescence to Algal communities Vertical distribution in the Oceanic Realm) uses as input only the shape of the fluorescence profile associated with its acquisition date and geo-location. The neural network is trained and validated using a large database including 896 concomitant in situ vertical profiles of High-Performance Liquid Chromatography (HPLC) pigments and fluorescence. These profiles were collected during 22 oceanographic cruises representative of the global ocean in terms of trophic and oceanographic conditions, making our method applicable to most oceanic waters. FLAVOR is validated with respect to the retrieval of both [Chl] and phytoplankton size indices using an independent in situ data set and appears to be relatively robust spatially and temporally. To illustrate the potential of the method, we applied it to in situ measurements of the BATS (Bermuda Atlantic Time Series Study) site and produce monthly climatologies of [Chl] and associated phytoplankton size indices. The resulting climatologies appear very promising compared to climatologies based on available in situ HPLC data. With the increasing availability of spatially and temporally well-resolved data sets of chlorophyll fluorescence, one possible global-scale application of FLAVOR could be to develop 3-D and even 4-D climatologies of [Chl] and associated composition of phytoplankton communities. The Matlab and R codes of the proposed algorithm are provided as supporting information.

  11. Effect of environmental forcing on the biomass, production and growth rate of size-fractionated phytoplankton in the central Atlantic Ocean

    Science.gov (United States)

    Huete-Ortega, María; Calvo-Díaz, Alejandra; Graña, Rocío; Mouriño-Carballido, Beatriz; Marañón, Emilio

    2011-11-01

    To ascertain the response of phytoplankton size classes to changes in environmental forcing, we determined size-fractionated biomass, carbon fixation and growth (production/biomass) rates in surface waters along the central Atlantic Ocean (26°N-5°S). As a result of the enhanced input of nutrients into the euphotic layer and the higher water column stability found at the equatorial upwelling, we observed increases not only in phytoplankton biomass and primary production, but also in turnover rates, suggesting nutrient limitation of phytoplankton physiology in the oligotrophic central Atlantic. The phytoplankton groups analysed (pico-, small nano-, large nano- and micro-phytoplankton) showed different responses to the equatorial environmental forcing, in terms of carbon biomass, primary production and growth rate. Large nano- and micro-phytoplankton consistently showed higher growth rates and carbon fixation to chl a ratios than smaller phytoplankton. We observed a higher stimulating effect of increased nitrate supply on the small phytoplankton growth rates. This observation can be explained by the dynamics of the equatorial upwelling, where the continuous but small nutrient input into the euphotic layer provide a competitive advantage for smaller cells adapted to oligotrophic conditions. The size-fractionated approach shown here reveals important group-specific differences in the response to environmental forcing, which cannot be appreciated in bulk measurements of the whole community.

  12. Role of zooplankton dynamics for Southern Ocean phytoplankton biomass and global biogeochemical cycles

    DEFF Research Database (Denmark)

    Le Quéré, Corinne; Buitenhuis, Erik T.; Moriarty, Róisín

    2016-01-01

    Global ocean biogeochemistry models currently employed in climate change projections use highly simplified representations of pelagic food webs. These food webs do not necessarily include critical pathways by which ecosystems interact with ocean biogeochemistry and climate. Here we present a global...... zooplankton community, despite iron limitation of phytoplankton community growth rates. This result has implications for the representation of global biogeochemical cycles in models as zooplankton faecal pellets sink rapidly and partly control the carbon export to the intermediate and deep ocean....

  13. 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

  14. Warming and Ocean Acidification Effects on Phytoplankton--From Species Shifts to Size Shifts within Species in a Mesocosm Experiment.

    Science.gov (United States)

    Sommer, Ulrich; Paul, Carolin; Moustaka-Gouni, Maria

    2015-01-01

    While the isolated responses of marine phytoplankton to climate warming and to ocean acidification have been studied intensively, studies on the combined effect of both aspects of Global Change are still scarce. Therefore, we performed a mesocosm experiment with a factorial combination of temperature (9 and 15 °C) and pCO2 (means: 439 ppm and 1040 ppm) with a natural autumn plankton community from the western Baltic Sea. Temporal trajectories of total biomass and of the biomass of the most important higher taxa followed similar patterns in all treatments. When averaging over the entire time course, phytoplankton biomass decreased with warming and increased with CO2 under warm conditions. The contribution of the two dominant higher phytoplankton taxa (diatoms and cryptophytes) and of the 4 most important species (3 diatoms, 1 cryptophyte) did not respond to the experimental treatments. Taxonomic composition of phytoplankton showed only responses at the level of subdominant and rare species. Phytoplankton cell sizes increased with CO2 addition and decreased with warming. Both effects were stronger for larger species. Warming effects were stronger than CO2 effects and tended to counteract each other. Phytoplankton communities without calcifying species and exposed to short-term variation of CO2 seem to be rather resistant to ocean acidification.

  15. Warming and Ocean Acidification Effects on Phytoplankton--From Species Shifts to Size Shifts within Species in a Mesocosm Experiment.

    Directory of Open Access Journals (Sweden)

    Ulrich Sommer

    Full Text Available While the isolated responses of marine phytoplankton to climate warming and to ocean acidification have been studied intensively, studies on the combined effect of both aspects of Global Change are still scarce. Therefore, we performed a mesocosm experiment with a factorial combination of temperature (9 and 15 °C and pCO2 (means: 439 ppm and 1040 ppm with a natural autumn plankton community from the western Baltic Sea. Temporal trajectories of total biomass and of the biomass of the most important higher taxa followed similar patterns in all treatments. When averaging over the entire time course, phytoplankton biomass decreased with warming and increased with CO2 under warm conditions. The contribution of the two dominant higher phytoplankton taxa (diatoms and cryptophytes and of the 4 most important species (3 diatoms, 1 cryptophyte did not respond to the experimental treatments. Taxonomic composition of phytoplankton showed only responses at the level of subdominant and rare species. Phytoplankton cell sizes increased with CO2 addition and decreased with warming. Both effects were stronger for larger species. Warming effects were stronger than CO2 effects and tended to counteract each other. Phytoplankton communities without calcifying species and exposed to short-term variation of CO2 seem to be rather resistant to ocean acidification.

  16. 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.

  17. Use of ultrafiltration to isolate viruses from seawater which are pathogens of marine phytoplankton.

    Science.gov (United States)

    Suttle, C A; Chan, A M; Cottrell, M T

    1991-03-01

    Viruses may be major structuring elements of phytoplankton communities and hence important regulators of nutrient and energy fluxes in aquatic environments. In order to ascertain whether viruses are potentially important in dictating phytoplankton community structure, it is essential to determine the extent to which representative phytoplankton taxa are susceptible to viral infection. We used a spiral ultrafiltration cartridge (30,000-molecular-weight cutoff) to concentrate viruses from seawater at efficiencies approaching 100%. Natural virus communities were concentrated from stations in the Gulf of Mexico, a barrier island pass, and a hypersaline lagoon (Laguna Madre) and added to cultures of potential phytoplankton hosts. By following changes in in vivo fluorescence over time, it was possible to isolate several viruses that were pathogens to a variety of marine phytoplankton, including a prasinophyte (Micromonas pusilla), a pennate diatom (likely a Navicula sp.), a centric diatom (of unknown taxa), and a chroococcoid cyanobacterium (a Synechococcus sp.). As well, we observed changes in fluorescence in cultures of a cryptophyte (a Rhodomonas sp.) and a chlorophyte (Nannochloropsis oculata) which were consistent with the presence of viral pathogens. Although pathogens were isolated from all stations, all the pathogens were not isolated from every station. Filterability studies on the viruses infecting M. pusilla and the Navicula sp. showed that the viruses were consistently infective after filtration through polycarbonate and glass-fiber filters but were affected by most other filter types. Establishment of phytoplankton-pathogen systems will be important in elucidating the effect that viruses have on primary producers in aquatic systems.

  18. 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.

  19. Synoptic relationships between surface Chlorophyll-a and diagnostic pigments specific to phytoplankton functional types

    Directory of Open Access Journals (Sweden)

    M. Noguchi-Aita

    2011-02-01

    Full Text Available Error-quantified, synoptic-scale relationships between chlorophyll-a (Chl-a and phytoplankton pigment groups at the sea surface are presented. A total of ten pigment groups were considered to represent three Phytoplankton Size Classes (PSCs, micro-, nano- and picoplankton and seven Phytoplankton Functional Types (PFTs, i.e. diatoms, dinoflagellates, green algae, prymnesiophytes (haptophytes, pico-eukaryotes, prokaryotes and Prochlorococcus sp.. The observed relationships between Chl-a and PSCs/PFTs were well-defined at the global scale to show that a community shift of phytoplankton at the basin and global scales is reflected by a change in Chl-a of the total community. Thus, Chl-a of the total community can be used as an index of not only phytoplankton biomass but also of their community structure. Within these relationships, we also found non-monotonic variations with Chl-a for certain pico-sized phytoplankton (pico-eukaryotes, Prokaryotes and Prochlorococcus sp. and nano-sized phytoplankton (Green algae, prymnesiophytes. The relationships were quantified with a least-square fitting approach in order to enable an estimation of the PFTs from Chl-a where PFTs are expressed as a percentage of the total Chl-a. The estimated uncertainty of the relationships depends on both PFT and Chl-a concentration. Maximum uncertainty of 31.8% was found for diatoms at Chl-a = 0.49 mg m−3. However, the mean uncertainty of the relationships over all PFTs was 5.9% over the entire Chl-a range observed in situ (0.02 < Chl-a < 4.26 mg m−3. The relationships were applied to SeaWiFS satellite Chl-a data from 1998 to 2009 to show the global climatological fields of the surface distribution of PFTs. Results show that microplankton are present in the mid and high latitudes, constituting only ~10.9% of the entire phytoplankton community in the mean field for 1998–2009, in which diatoms explain ~7.5%. Nanoplankton are ubiquitous throughout the global surface oceans

  20. Astaxanthin production in marine pelagic copepods grazing on two different phytoplankton diets

    Science.gov (United States)

    Van Nieuwerburgh, Lies; Wänstrand, Ingrid; Liu, Jianguo; Snoeijs, Pauli

    2005-02-01

    The red carotenoid astaxanthin is a powerful natural antioxidant of great importance in aquatic food webs where it is abundant in eggs and body tissues of fish and crustaceans. Little is known about the impact of the phytoplankton diet on astaxanthin production in copepods, its major pelagic producers. We followed the transfer of carotenoids from phytoplankton to copepods in a mesocosm experiment on the northern Atlantic coast (Norway) and recorded the astaxanthin production in copepods. Wild copepods grazed on nutrient-manipulated phytoplankton blooms, which differed in community composition and nutrient status (nitrogen or silicate limitation). The copepod pigments consisted mainly of free astaxanthin and mono- and diesters of astaxanthin. We found no significant difference in astaxanthin production per copepod individual or per unit C depending on the phytoplankton community. However, in the mesocosms astaxanthin per unit C decreased compared with natural levels, probably through a lower demand for photoprotection by the copepods in the dense phytoplankton blooms. The total astaxanthin production per litre was higher in the silicate-limited mesocosms through increased copepod density. Pigment ratio comparisons suggested that the copepod diet here consisted more of diatoms than in the nitrogen-limited mesocosms. Silicate-saturated diatoms were less grazed, possibly because they could invest more in defence mechanisms against their predators. Our study suggests that the production of astaxanthin in aquatic systems can be affected by changes in nutrient dynamics mediated by phytoplankton community composition and copepod population growth. This bottom-up force may have implications for antioxidant protection at higher trophic levels in the food web.

  1. Co-occurrence patterns in aquatic bacterial communities across changing permafrost landscapes

    Directory of Open Access Journals (Sweden)

    J. Comte

    2015-07-01

    Full Text Available Permafrost thaw ponds and lakes are widespread across the northern landscape and may play a central role in global biogeochemical cycles, yet knowledge about their microbial ecology is limited. We sampled a set of thaw ponds and lakes as well as shallow rock-basin lakes that are located in distinct valleys along a North–South permafrost degradation gradient. We applied high-throughput sequencing of the 16S rRNA gene to determine co-occurrence patterns among bacterial taxa, and then analyzed these results relative to environmental variables to identify factors controlling bacterial community structure. Network analysis was applied to identify possible ecological linkages among the bacterial taxa and with abiotic and biotic variables. The results showed an overall high level of shared taxa among bacterial communities within each valley, however the bacterial co-occurrence patterns were non-random, with evidence of habitat preferences. There were taxonomic differences in bacterial assemblages among the different valleys that were statistically related to dissolved organic carbon concentration, conductivity and phytoplankton biomass. Co-occurrence networks revealed complex interdependencies within the bacterioplankton communities and showed contrasting linkages to environmental conditions among the main bacterial phyla. The thaw pond networks were composed of a limited number of highly connected taxa. This "small world network" property would render the communities more robust to environmental change but vulnerable to the loss of microbial keystone species.

  2. A database of marine phytoplankton abundance, biomass and species composition in Australian waters.

    Science.gov (United States)

    Davies, Claire H; Coughlan, Alex; Hallegraeff, Gustaaf; Ajani, Penelope; Armbrecht, Linda; Atkins, Natalia; Bonham, Prudence; Brett, Steve; Brinkman, Richard; Burford, Michele; Clementson, Lesley; Coad, Peter; Coman, Frank; Davies, Diana; Dela-Cruz, Jocelyn; Devlin, Michelle; Edgar, Steven; Eriksen, Ruth; Furnas, Miles; Hassler, Christel; Hill, David; Holmes, Michael; Ingleton, Tim; Jameson, Ian; Leterme, Sophie C; Lønborg, Christian; McLaughlin, James; McEnnulty, Felicity; McKinnon, A David; Miller, Margaret; Murray, Shauna; Nayar, Sasi; Patten, Renee; Pritchard, Tim; Proctor, Roger; Purcell-Meyerink, Diane; Raes, Eric; Rissik, David; Ruszczyk, Jason; Slotwinski, Anita; Swadling, Kerrie M; Tattersall, Katherine; Thompson, Peter; Thomson, Paul; Tonks, Mark; Trull, Thomas W; Uribe-Palomino, Julian; Waite, Anya M; Yauwenas, Rouna; Zammit, Anthony; Richardson, Anthony J

    2016-06-21

    There have been many individual phytoplankton datasets collected across Australia since the mid 1900s, but most are unavailable to the research community. We have searched archives, contacted researchers, and scanned the primary and grey literature to collate 3,621,847 records of marine phytoplankton species from Australian waters from 1844 to the present. Many of these are small datasets collected for local questions, but combined they provide over 170 years of data on phytoplankton communities in Australian waters. Units and taxonomy have been standardised, obviously erroneous data removed, and all metadata included. We have lodged this dataset with the Australian Ocean Data Network (http://portal.aodn.org.au/) allowing public access. The Australian Phytoplankton Database will be invaluable for global change studies, as it allows analysis of ecological indicators of climate change and eutrophication (e.g., changes in distribution; diatom:dinoflagellate ratios). In addition, the standardised conversion of abundance records to biomass provides modellers with quantifiable data to initialise and validate ecosystem models of lower marine trophic levels.

  3. A database of marine phytoplankton abundance, biomass and species composition in Australian waters

    Science.gov (United States)

    Davies, Claire H.; Coughlan, Alex; Hallegraeff, Gustaaf; Ajani, Penelope; Armbrecht, Linda; Atkins, Natalia; Bonham, Prudence; Brett, Steve; Brinkman, Richard; Burford, Michele; Clementson, Lesley; Coad, Peter; Coman, Frank; Davies, Diana; Dela-Cruz, Jocelyn; Devlin, Michelle; Edgar, Steven; Eriksen, Ruth; Furnas, Miles; Hassler, Christel; Hill, David; Holmes, Michael; Ingleton, Tim; Jameson, Ian; Leterme, Sophie C.; Lønborg, Christian; McLaughlin, James; McEnnulty, Felicity; McKinnon, A. David; Miller, Margaret; Murray, Shauna; Nayar, Sasi; Patten, Renee; Pritchard, Tim; Proctor, Roger; Purcell-Meyerink, Diane; Raes, Eric; Rissik, David; Ruszczyk, Jason; Slotwinski, Anita; Swadling, Kerrie M.; Tattersall, Katherine; Thompson, Peter; Thomson, Paul; Tonks, Mark; Trull, Thomas W.; Uribe-Palomino, Julian; Waite, Anya M.; Yauwenas, Rouna; Zammit, Anthony; Richardson, Anthony J.

    2016-06-01

    There have been many individual phytoplankton datasets collected across Australia since the mid 1900s, but most are unavailable to the research community. We have searched archives, contacted researchers, and scanned the primary and grey literature to collate 3,621,847 records of marine phytoplankton species from Australian waters from 1844 to the present. Many of these are small datasets collected for local questions, but combined they provide over 170 years of data on phytoplankton communities in Australian waters. Units and taxonomy have been standardised, obviously erroneous data removed, and all metadata included. We have lodged this dataset with the Australian Ocean Data Network (http://portal.aodn.org.au/) allowing public access. The Australian Phytoplankton Database will be invaluable for global change studies, as it allows analysis of ecological indicators of climate change and eutrophication (e.g., changes in distribution; diatom:dinoflagellate ratios). In addition, the standardised conversion of abundance records to biomass provides modellers with quantifiable data to initialise and validate ecosystem models of lower marine trophic levels.

  4. A database of marine phytoplankton abundance, biomass and species composition in Australian waters

    Science.gov (United States)

    Davies, Claire H.; Coughlan, Alex; Hallegraeff, Gustaaf; Ajani, Penelope; Armbrecht, Linda; Atkins, Natalia; Bonham, Prudence; Brett, Steve; Brinkman, Richard; Burford, Michele; Clementson, Lesley; Coad, Peter; Coman, Frank; Davies, Diana; Dela-Cruz, Jocelyn; Devlin, Michelle; Edgar, Steven; Eriksen, Ruth; Furnas, Miles; Hassler, Christel; Hill, David; Holmes, Michael; Ingleton, Tim; Jameson, Ian; Leterme, Sophie C.; Lønborg, Christian; McLaughlin, James; McEnnulty, Felicity; McKinnon, A. David; Miller, Margaret; Murray, Shauna; Nayar, Sasi; Patten, Renee; Pritchard, Tim; Proctor, Roger; Purcell-Meyerink, Diane; Raes, Eric; Rissik, David; Ruszczyk, Jason; Slotwinski, Anita; Swadling, Kerrie M.; Tattersall, Katherine; Thompson, Peter; Thomson, Paul; Tonks, Mark; Trull, Thomas W.; Uribe-Palomino, Julian; Waite, Anya M.; Yauwenas, Rouna; Zammit, Anthony; Richardson, Anthony J.

    2016-01-01

    There have been many individual phytoplankton datasets collected across Australia since the mid 1900s, but most are unavailable to the research community. We have searched archives, contacted researchers, and scanned the primary and grey literature to collate 3,621,847 records of marine phytoplankton species from Australian waters from 1844 to the present. Many of these are small datasets collected for local questions, but combined they provide over 170 years of data on phytoplankton communities in Australian waters. Units and taxonomy have been standardised, obviously erroneous data removed, and all metadata included. We have lodged this dataset with the Australian Ocean Data Network (http://portal.aodn.org.au/) allowing public access. The Australian Phytoplankton Database will be invaluable for global change studies, as it allows analysis of ecological indicators of climate change and eutrophication (e.g., changes in distribution; diatom:dinoflagellate ratios). In addition, the standardised conversion of abundance records to biomass provides modellers with quantifiable data to initialise and validate ecosystem models of lower marine trophic levels. PMID:27328409

  5. Plant community responses to climate change

    Energy Technology Data Exchange (ETDEWEB)

    Kongstad, J.

    2012-07-01

    ecosystem more resilient to the climatic treatments than expected. We also found that the amount of flowering culms of D. flexuosa increased in response to increased CO{sub 2}, whereas the seed germination success decreased. The bryophyte biomass and the nitrogen content decreased in response to nitrogen addition. Even such apparently minor changes might, given time, affect the plant composition and thereby possibly also the major ecosystem processes. Further, we observed changes in the aboveground plant composition in response to the climate manipulations at the Mols site, where C. vulgaris was regenerating after a disturbance. Here a decrease in biomass of the pioneer stage was seen, when subjected to the drought treatment compared to warmed and control treatments. I therefore conclude, that the stage of the C. vulgaris population as well as the magnitude and frequency of disturbances determine the effects of future climate change on the plant community in heathland ecosystems. (Author)

  6. 仿刺参养殖池塘中浮游和底栖藻类群落的变化%Variation in Phytoplankton and Benthic Alga Communities in Sea Cucumber Apostichopus japonicus Culture Ponds

    Institute of Scientific and Technical Information of China (English)

    刘冉; 迟爽; 程敬伟; 曾勇; 赵振军; 马家好; 崔龙波

    2013-01-01

    Composition ,density ,biomass ,Shannon-Weiner index ,Pielou’s evenness index ,Margalef’s richness index and McNaugton dominance index of the phytoplankton and benthic alga communities were determined in six 5000 ~ 6000 m2 ponds with depth of 1 .8 ~ 2 .0 m for sea cucumber A postichopus j aponicus culture in coastal Laizihou ,Shandong Province from October ,2011 to September ,2012 .A total of 40 species in 7 phyla of phytoplankon were found ,with the predominant Bacillariophyta ,and 18 benthic alga species in Bacillariophyta .The density was ranged from 7 .810 × 105 to 249 .662 × 105 cell/L ,with biomass of 1 .65~12 .07 mg/L in the phytoplankon and from 4 .124 × 105 to 14 .289 × 105 cell/cm2 ,with biomass of 2 .60~11 .27 mg/cm2 ,in the benthic algae in the ponds .There were Shannon-Weiner index of 2 .09~2 .93 in the phytoplankon and 1 .67~2 .73 in the benthic algae ,and Pielou’s evenness index of 0 .56~0 .78 in the phytoplankon and 0 .48~0 .73 in the benthic algae .The phytoplankon showed Margalef’s richness index from 1 .74 to 2 .42 and the benthic algae from 1 .41 to 1 .83 .The predominant phytoplankton species were found to be changed with time ,but almost no changes were observed in the predominant benthic algae in the year . There were very significant positive correlation between the density of phytoplankton and that of benthic algae in the ponds ,indicating that the species diversity in phytoplankton and benthic algae community is rich and the ecological environment is good in the culture ponds .%2011年10月至2012年9月对山东省莱州市仿刺参养殖区的6口面积为5000~6000 m2,水深1.8~2.0 m的养殖池塘中的浮游和底栖藻类进行了调查,分析其群落的组成、密度、生物量、Shannon-Weiner多样性指数、Pielou均匀度指数、Margalef丰富度指数和McNaugton优势度指数。研究结果表明,仿刺参池塘中共鉴定出浮游藻类7门40种,主要由硅藻组成;底栖藻类18种,均

  7. Canonical correspondence analysis of phytoplankton community and environmental factors in Qinhuai River in autumn and winter%秦淮河秋冬季浮游植物群落与环境因子典范对应分析

    Institute of Scientific and Technical Information of China (English)

    严莹

    2013-01-01

    2012年10月和2013年1月对南京市内外秦淮河浮游植物群落进行调查和分析。共鉴定出浮游植物4门30属37种,秋季主要以蓝藻-硅藻为主,平均丰度和生物量分别为221.5万cells/L和4.41 mg/L,冬季以硅藻为主,平均丰度和生物量分别为153.4万cells/L和6.58 mg/L。典范对应分析显示,绿藻对氮磷营养盐浓度、高锰酸盐指数等含量较高的水体耐受能力较强,硅藻则对多变的环境适应能力较强;氮磷比对蓝藻、裸藻和部分绿藻的分布有较明显的影响;秋冬季节影响秦淮河浮游植物群落分布的主要环境因子为水温和溶解氧,其次为氮磷营养盐浓度和电导率。%The phytoplankton community in the internal and external Qinhuai River in Nanjing City was investigated and analyzed in October 2012 and January 2013 . A total of 37 species of phytoplankton belonging to four families and 30 genera were identified. Blue-green algae-diatoms were dominant phytoplankton in the autumn, with an average abundance and biomass of 221.5í104 cells/L and 4.41 mg/L, respectively. Diatoms were dominant phytoplankton in the winter, with an average abundance and biomass of 153.4í104 cells/L and 6.58 mg/L, respectively. Canonical correspondence analysis ( CCA) showed that green algae had a high tolerance to water that had high nitrogen and phosphorus nutrient concentrations and permanganate indices, and diatoms had a strong ability to adapt to a changeable environment; the ratio of nitrogen to phosphorus had a significant impact on the distributions of cyanobacteria, euglena, and part of the green algae; and water temperature and dissolved oxygen were the main environmental factors influencing the distribution of the phytoplankton community in the Qinhuai River in the autumn and winter, followed by nitrogen and phosphorus nutrient concentrations and electrical conductivity.

  8. Phytoplankton biovolume is independent from the slope of the size spectrum in the oligotrophic atlantic ocean

    KAUST Repository

    Moreno-Ostos, Enrique

    2015-08-06

    Modelling the size-abundance spectrum of phytoplankton has proven to be a very useful tool for the analysis of physical-biological coupling and the vertical flux of carbon in oceanic ecosystems at different scales. A frequent observation relates high phytoplankton biovolume in productive regions with flatter spectrum slope and the opposite in oligotrophic ecosystems. Rather than this, the relationship between high biovolume phytoplankton assemblages and flatter size-abundance spectra does not correspond with measurements of the phytoplankton community in the Atlantic Ocean open waters. As part of the Malaspina Circunnavegation Expedition, sixty seven sampling stations within the Atlantic Ocean covering six oceanographic provinces, at different seasons, produced a complete set of phytoplankton size-spectra whose slope and biovolume did not show any obvious interrelation. In these oligotrophic sites, small (procaryotes) and medium-size (nanoplankton) cells are responsible for the most part of biovolume, and their response to environmental conditions does not apply to changes in the size-abundance spectrum slope as expected in richer, large-cell dominated ecosystems.

  9. Spatio-temporal variability of phytoplankton dimensional classes in the Mediterranean Sea from satellite data

    Science.gov (United States)

    Sammartino, Michela; Di Cicco, Annalisa; Marullo, Salvatore; Santoleri, Rosalia

    2016-04-01

    Phytoplankton contributes to fix half of the carbon dioxide released on Earth, becoming a key component not only in the carbon cycle, but also in several biogeochemical cycles. It is involved in the control of greenhouse gases and, consequently, in the effect of climate change on marine system. Therefore, phytoplankton is often considered one of the most common bio-indicator for any environmental changes, which, in turn, can affect the algal community composition and structure. The alteration of the biological, physical and chemical conditions in the ocean can be reflected in the algal assemblage structure, in terms of variation of dominant size class and taxonomic composition. In this work, the seasonal and year-to-year variability of the phytoplankton size class (PSC) spatial distribution has been examined in the Mediterranean Sea using ten year of satellite observations. The estimation of PSCs from space is based on relationship between chlorophyll a (Chl a) and diagnostic pigments that should be verified at regional scales. Our analysis shows that the Mediterranean pigments ratios differs from the global ones; therefore, we regionalized the mathematical relation existing between the Chl a and the diagnostic pigments, used in the in situ PSC identification. This regionally tuned relation allowed to improve the estimation of PSCs from space by reducing the observed bias between modelled and measured PSCs. The analysis of PSC satellite time series allowed, for the first time, to have a quantitative description of the seasonal and inter-annual variability of the spatial distribution of the algal community in the Mediterranean Sea. The results demonstrated that the pico-phytoplankton contributes with high values to the total Chl a, especially in summer and in ultra-oligotrophic environments, such as the Levantine basin. Micro-phytoplankton contribution results high during spring bloom period in offshore areas, characterized by a strong water mixing; while, in

  10. Genetic diversity of marine Synechococcus and co-occurring cyanophage communities: evidence for viral control of phytoplankton.

    Science.gov (United States)

    Mühling, Martin; Fuller, Nicholas J; Millard, Andrew; Somerfield, Paul J; Marie, Dominique; Wilson, William H; Scanlan, David J; Post, Anton F; Joint, Ian; Mann, Nicholas H

    2005-04-01

    Unicellular cyanobacteria of the genus Synechococcus are a major component of the picophytoplankton and make a substantial contribution to primary productivity in the oceans. Here we provide evidence that supports the hypothesis that virus infection can play an important role in determining the success of different Synechococcus genotypes and hence of seasonal succession. In a study of the oligotrophic Gulf of Aqaba, Red Sea, we show a succession of Synechococcus genotypes over an annual cycle. There were large changes in the genetic diversity of Synechococcus, as determined by restriction fragment length polymorphism analysis of a 403- bp rpoC1 gene fragment, which was reduced to one dominant genotype in July. The abundance of co-occurring cyanophage capable of infecting marine Synechococcus was determined by plaque assays and their genetic diversity was determined by denaturing gradient gel electrophoresis analysis of a 118-bp g20 gene fragment. The results indicate that both abundance and genetic diversity of cyanophage covaried with that of Synechococcus. Multivariate statistical analyses show a significant relationship between cyanophage assemblage structure and that of Synechococcus. These observations are consistent with cyanophage infection being a major controlling factor in picophytoplankton succession.

  11. EFFECTS OF COPPER SULFATE TREATMENT ON EUTROPHIC URBAN LAKE PHYTOPLANKTON COMMUNITIES%硫酸铜控藻对浮游植物群落的影响

    Institute of Scientific and Technical Information of China (English)

    赵小丽; 宋立荣; 张小明

    2009-01-01

    硫酸铜广泛用于水华藻类的去除和控制.本文测定了不同藻类对Cu2+的敏感性,几种常见水华藻类对Cu2+的敏感性顺序为:铜绿微囊藻>水华鱼腥藻>小环藻>莱哈衣藻>斜生栅藻.在某城市的富营养化湖泊中用Cu-SO4·5H2O(102μg/L Cu2+)作为杀藻剂控制蓝藻水华的试验结果表明:在用硫酸铜控制蓝藻水华的过程中,水体透明度有明显改善;总氮总磷无显著变化;浮游植物总数在试验初期下降,但在试验后期则有所回升,在试验初期蓝藻门数量有所下降,绿藻门和硅藻门数量增加,这与不同藻类对Cu2+敏感性差异相关;试验后期,蓝藻门种类快速生长,并成为优势种;水柱中微囊藻毒素的浓度随藻类数量的减少在4d内大幅降低.%Copper sulphate treatment is widely used as a global and empirical method to remove or control phytoplankton blooms. We tested the acute toxicity of 5 species of familiar microalgae and gave an urban lake copper sulfate treat in order to illuminate how the water body response to copper treat, especially the change of phytoplankton species and density of microcystins. According to OECD Alga growth inhibition test, effect of copper on 5 species of familiar microalgae was tested, and species of Cyanophyta showed much higher sensitivity to copper than species of Chlorophyta and Bacillariophyta. In a eutrophic urban lake,CuSO4·5H2O was used as algicide to control the water bloom caused by cyanobacterial.The copper concentration applied was 102μg/L (as copper). We investigated the lake response to copper sulfate, which showed that the transparence was substantially improved; TN and TP did not change a lot; total algal decreased just after the copper sulfate treatment, and later increased again; at the beginning of the experiment, species of Cyanophyta died and the amount sharply decreased, Bacillariophyta and Chlorophyta turned to be the preponderant species, which could be related to species

  12. Response of rotifer functional groups to changing trophic state and crustacean community

    Directory of Open Access Journals (Sweden)

    Marina MANCA

    2011-08-01

    Full Text Available Information based on taxon-based indices is species-specific while information gained from function-based research can give a comprehensive view of ecosystem processes. We applied the guild-ratio, an index based on the proportion of functional groups of rotifers (i.e. microphagous and raptorial species, on a long-term data set of Lago Maggiore. By applying seasonal trend decomposition based on smoothing techniques and non-metrical multidimensional scaling, we assessed the response of rotifer functional groups to changes in trophic state and climate. While the taxon-based indices showed smooth changes, the function-based index showed a dramatic shift from a raptorial to a microphagous dominance, with a back-shift to raptorial dominance starting in 2000. The seasonal peak of microphagous and raptorial dry weight was clearly separated in the pre-eutrophication period. When mesotrophic conditions prevailed both peaks overlapped, only to be separated again with re-oligotrophication. We attributed these alterations of rotifer functional groups to changes in competition with crustacean zooplankton and to decreased phytoplankton algal abundance and size while altered seasonality in functional groups could be related to inter-group competition for food. We hypothesise that the effects of trophic state (i.e. altered phytoplankton and climate (i.e. altered cladoceran community were transferred across trophic levels to rotifer functional groups. Our study highlights that functional groups are valid instruments for illustrating unifying principles in ecology through a better understanding of ecosystem processes and the interrelationship between trophic levels.

  13. 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...

  14. Impact of Three Gorges Reservoir Impoundment and Discharge on the Phytoplankton Community Structure of Xiaojiang River%三峡水库泄、蓄水过程对小江浮游植物群落结构的影响

    Institute of Scientific and Technical Information of China (English)

    潘晓洁; 刘诚; 朱梦灵; 郑志伟; 邹曦; 胡莲; 万成炎

    2016-01-01

    discharge period.Cluster analysis shows that the phytoplankton community during the two periods was clustered into different groups,which changed differently over time.Correlation analysis shows that temperature and nutrient levels played critical roles in phytoplankton growth,but the hydrologic index had very little impact during either period.To summarize,the discharge-impoundment cycle of Three Gorges Reservoir strongly af-fects phytoplankton community structure in Xiaojiang River and temperature and nutrient levels are the primary in-fluences.Phytoplankton density increases significantly late in discharge period,when the decrease in water level leads to a high risk of algal bloom.

  15. Response of a natural Phytoplankton community from the Qingdao coast (Yellow Sea, China) to variable CO2 levels over a short-term incubation experiment

    Digital Repository Service at National Institute of Oceanography (India)

    Biswas, H.; Jie, J.; Li, Y.; Zhang, G.; Zhu, Z.-Y.; Wu, Y.; Zhang, G.-L.; Li, Y.-W.; Liu, S.M.; Zhang, J.

    ) under low CO2 levels, and diffusive CO2 uptake increased upon the increase of external CO2 levels. Although, considerable increase in phytoplankton biomass was noticed in all CO2 treatments, CO2

  16. Characteristics of community structures of phytoplankton in the salt lakes in Naqu region, Tibet%西藏那曲地区盐湖浮游植物群落结构的特征

    Institute of Scientific and Technical Information of China (English)

    陈立婧; 杨菲; 吴淑贤; 刘喜方; 贾沁贤

    2013-01-01

    2009年4-5月对西藏那曲地区12个盐湖进行浮游植物采样调查,共检出浮游植物58种,隶属于6门39属,其中硅藻门种数最多(34种),占浮游植物总种数的58.62%,其次为绿藻门(11种)和蓝藻门(8种).主要优势种为舟形藻属未定种1种、菱形藻属未定种1种、湖泊鞘丝藻和小形卵囊藻.平均生物密度和生物量分别为9.70 × 104 cells/L和0.162 8 mg/L.分析了西藏盐湖浮游植物区系组成特点,及其与环境因子尤其是含盐量的关系,结果表明:浮游植物物种数、生物密度与生物量均与含盐量存在不显著的负相关关系(P>0.05),在盐湖生态系统中,盐度是决定浮游植物多样性及个体数量的关键因素之一,浮游植物群落结构受众多生态因子共同影响.研究亮点:西藏盐湖不同于内陆淡水湖泊,其盐度较高,地理、自然环境恶劣,尤其那曲地区处于西藏羌北无人区,进藏调查研究只有少数具备条件的单位能够完成,因此其盐湖浮游植物一直都缺乏全面详细的调查.本文对西藏那曲地区12个盐湖的浮游植物群落结构进行调查,以丰富西藏盐湖浮游生物资源、生态学资料,并为盐湖资源综合性开发利用提供一定参考.%The phytoplankton of 12 salt lakes in Naqu region,Tibet had been investigated during April to May in 2009.A total of 58 species of phytoplankton were identified,belonging to 39 genera of 6 phyla.Bacillariophyta (34 species) was dominant in species richness by 58.62 percentage,followed by Cyanophyta (11 species) and Chlorophyta (8 species).Navicula sp.,Nitzschia sp.,Lyngbya limnetica,Oocystis parva were the main dominant species.The average density and biomass of phytoplankton were 9.70 × 104 cells/L and 0.162 8 mg/L,respectively.This paper also discusses the phytoplankton community characteristics of Tibet salt lakes,and the relationship between floristic composition characteristics of phytoplankton and environmental factors

  17. Phytoplankton community composition and its relationships with the environment in Shanton Harbor of South China%汕头港浮游植物组成特征及其与环境的关系

    Institute of Scientific and Technical Information of China (English)

    杜虹; 王亮根; 曹会彬; 陈伟洲

    2011-01-01

    于2009年3月-2010年3月对汕头港生态环境进行连续监测,研究了浮游植物组成及其对环境条件的敏感程度.结果表明:研究区共鉴定出322种浮游植物,包含了234种硅藻,141种淡水和半咸水种以及64种赤潮生物;浮游植物丰度、Shannon指数和均匀度指数分别是3127.6×104cells·m-3、2.53和0.57;中肋骨条藻(Skeletonema costatum)和颤藻( Oscillatoria sp.)是全年优势种,优势度分别是0.066和0.038;浮游生物数量组成结构与温度明显相关(r=0.699,P<0.01).浮游植物与环境因子之间的相关性分析显示,透明度是汕头港浮游植物生长主要限制因子.比较浮游植物数量组成与环境因子间的相关程度发现,上游输入是汕头港污染物的重要来源之一.多维尺度与Pearson相关性分析显示,汕头港浮游植物群落结构变化主要受温度、盐度与pH影响.%Based on the monitoring data of the eco-environment in Shantou Harbor from March 2009 to March 2010, this paper studied the composition of phytoplankton community and its sensitivity to the environment in the Harbor. A total of 322 phytoplankton species were identified, including 234 diatom species, 141 fresh-water and brackish water species, and 64 red tide species. The average abundance, Shannon index, and evenness index of the community were 3127. 6×104 cells · m-3 , 2. 53 , and 0. 57 , respectively , and Skeletonema costatum and Oscillatoria sp. were the dominant species throughout the year, with the dominance index being 0. 066 and 0. 038, respectively. There was a significant positive correlation between phytoplankton community composition and water temperature ( r= -0. 699 , P<0. 01 ) , and the phytoplankton growth was mainly limited by water transparence. The relevance degree of phytoplankton composition and environmental factors showed that upstream input was an important source of Shantou Port pollutants, and the multi-scale and Pearson correlation analyses indicated

  18. [Historical changes in community concepts and the effect of such on community health nursing praxis].

    Science.gov (United States)

    Yeh, Lily; Chen, Yi-Hsing

    2011-02-01

    In the 21st century, many healthcare programs are delivered in community settings. As such, successfully recruiting target members of the community to participate in programs represents a key challenge for the nursing profession. Although the "community" is not a new concept, its meaning has changed over the past century or more of public healthcare, which has had a profound effect on community health nursing praxis. This article describes changes in community concepts through history in order to define the significance of community participation in today's community health nursing practice.

  19. Seasonal variations of group-specific phytoplankton cell death in Xiamen Bay, China

    Science.gov (United States)

    Huang, Xiaozhou; Liu, Xin; Chen, Jixin; Xiao, Wupeng; Cao, Zhen; Huang, Bangqin

    2017-03-01

    The importance of phytoplankton cell death is being increasingly recognized, however, there are still no published reports on this in Xiamen Bay. In this study, the proportion of dead phytoplankton cells associated with environmental factors was assessed at a station in Xiamen Bay from December 2012 to December 2013, using a cell digestion assay, which is an effective method to analyze dead/ living cells in complex natural phytoplankton communities. The percentages of dead cells (% DC) in the total phytoplankton in summer (16%±6%) were lower than those in winter (27%±16%). Six groups of phytoplankton (G1-G6) were categorized by flow cytometry. These phytoplankton communities with diverse seasonal variations in % DC had different responses to environmental constraints. The main factors affecting mortality were temperature and salinity, while nutrient concentration showed little influence on phytoplankton death. Additionally, our results provide evidence that chlorophyll a concentrations had an inverse relationship with total phytoplankton % DC and viable cell abundance was more meaningful than total cells to explain variations in environmental parameters (such as Chl a). Moreover, the lowest mean % DC in total phytoplankton was 16%±6% at our sample site, which is in a subtropical area with high water temperatures, full solar radiation, and rich nutrients. This indicates that phytoplankton cell death is a process that cannot be ignored. In summary, phytoplankton cell death is important in understanding the dynamics of phytoplankton communities and the functioning of subtropical ecosystems.

  20. Regime shift from phytoplankton to macrophyte dominance in a large river: Top-down versus bottom-up effects

    Energy Technology Data Exchange (ETDEWEB)

    Ibanez, Carles, E-mail: carles.ibanez@irta.cat [IRTA Aquatic Ecosystems, Carretera Poble Nou, Km 5.5, 43540 St. Carles de la Rapita, Catalonia (Spain); Alcaraz, Carles; Caiola, Nuno; Rovira, Albert; Trobajo, Rosa [IRTA Aquatic Ecosystems, Carretera Poble Nou, Km 5.5, 43540 St. Carles de la Rapita, Catalonia (Spain); Alonso, Miguel [United Research Services S.L., Urgell 143, 08036 Barcelona, Catalonia (Spain); Duran, Concha [Confederacion Hidrografica del Ebro, Sagasta 24-26, 50071 Zaragoza, Aragon (Spain); Jimenez, Pere J. [Grup Natura Freixe, Major 56, 43750 Flix, Catalonia (Spain); Munne, Antoni [Agencia Catalana de l' Aigua, Provenca 204-208, 08036 Barcelona, Catalonia (Spain); Prat, Narcis [Departament d' Ecologia, Universitat de Barcelona, Diagonal 645, 08028 Barcelona Catalonia (Spain)

    2012-02-01

    The lower Ebro River (Catalonia, Spain) has recently undergone a regime shift from a phytoplankton-dominated to a macrophyte-dominated system. This shift is well known in shallow lakes but apparently it has never been documented in rivers. Two initial hypotheses to explain the collapse of the phytoplankton were considered: a) the diminution of nutrients (bottom-up); b) the filtering effect due to the colonization of the zebra mussel (top-down). Data on water quality, hydrology and biological communities (phytoplankton, macrophytes and zebra mussel) was obtained both from existing data sets and new surveys. Results clearly indicate that the decrease in phosphorus is the main cause of a dramatic decrease in chlorophyll and large increase in water transparency, triggering the subsequent colonization of macrophytes in the river bed. A Generalized Linear Model analysis showed that the decrease in dissolved phosphorus had a relative importance 14 times higher than the increase in zebra mussel density to explain the variation of total chlorophyll. We suggest that the described changes in the lower Ebro River can be considered a novel ecosystem shift. This shift is triggering remarkable changes in the biological communities beyond the decrease of phytoplankton and the proliferation of macrophytes, such as massive colonization of Simulidae (black fly) and other changes in the benthic invertebrate communities that are currently investigated. - Highlights: Black-Right-Pointing-Pointer We show a regime shift in a large river from phytoplankton to macrophyte dominance. Black-Right-Pointing-Pointer Two main hypotheses are considered: nutrient decrease and zebra mussel grazing. Black-Right-Pointing-Pointer Phosphorus depletion is found to be the main cause of the phytoplankton decline. Black-Right-Pointing-Pointer We conclude that oligotrophication triggered the colonization of macrophytes. Black-Right-Pointing-Pointer This new regime shift in a river is similar to that described

  1. Distribuição vertical da comunidade fitoplanctônica do lago dos Tigres (Goiás, Brasil = Vertical distribution of phytoplankton communities in Tigres Lake (Goiás, Brazil

    Directory of Open Access Journals (Sweden)

    João Carlos Nabout

    2008-01-01

    Full Text Available O lago dos Tigres é um lago do tipo vale bloqueado, sendo que não foiregistrado estudo evidenciando a distribuição vertical fitoplanctônica para esse tipo de lago; dessa forma, esta pesquisa assume um caráter pioneiro. Objetivou-se, nesse trabalho, oreconhecimento temporal e espacial dos padrões verticais de atributos da comunidade fitoplanctônica, detectar os grupos funcionais fitoplanctônicos dominantes e descritivos do sistema e relacioná-los com características limnológicas. O lago estudado foi caracterizadocomo polimítico quente, sendo que ocorreram eventuais estratificações térmicas nas estações de maior profundidade. Os períodos de seca e início de chuva apresentaram-se tanto limnologicamente (evidenciado pela ACP quanto biologicamente (observado pela ACC distintos. Os meses de seca apresentaram maiores concentrações de nutrientes emaiores transparências. Nesses meses, também foi registrado predomínio dos grupos funcionais Lo, Y , N e W1. Os meses de chuvas apresentaram maiores temperaturas e menores transparências, sendo que os grupos funcionais predominantes foram S1, T e N. Avaliando conjuntamente as características limnológicas, o biovolume e os gruposfuncionais, pode-se concluir que o perfil vertical do lago dos Tigres é oligo-mesotrófico.Tigres Lake is a blocked valley lake, with no registered studies ofphytoplankton vertical distribution for that lake type; as such, our work assumes a pioneering nature. The aim of this study was to recognize temporally and spatially the vertical patterns of phytoplankton community attributes, to detect the dominant anddescriptive phytoplankton functional groups, and relate them to limnological characteristics. Tigres Lake was characterized as a warm polymictic lake, featuring occasional thermal stratification in deeper stations. The dry and early rainy seasons presented limnological (evidenced by PCA and biological (observed by CCA differences. The dry months presented

  2. Phytoplankton functional traits and seston stable isotopes signature: a functional-based approach in a deep, subalpine lake, Lake Maggiore (N. Italy

    Directory of Open Access Journals (Sweden)

    Anna Visconti

    2012-01-01

    Full Text Available The seasonal variation of seston stable isotopes signature of carbon (δ13C in Lake Maggiore during 2008 was related to seasonal variation of the lake phytoplankton community, investigated in terms of phytoplankton taxonomic groups, morpho-functional groups (MBFG, cell size classes and cell shape classes. Three open water stations were selected to reflect truly pelagic, influenced by littoral and riverine carbon sources; phytoplankton samples were collected from two water depths, 0-20 m and 25-50 m. Among stations differences in δ13C signatures of seston were statistically non significant, confirming that allochthonous input may become important only after exceptional rainfall events. Nonparametric multiplicative regression (NPMR was utilized to identify among the phytoplankton parameters (taxonomic groups, MBFG, cell shapes, cell sizes which were the best predictors of the δ13C variation. Bacillariophyceae and two morpho-functional groups, Group 6 (non-flagellated organisms with siliceous exoskeletons and Group 3 (large filamentous algae with aerotopes were statistically significant. Non-metric multidimensional scaling (NMS ordination was used to investigate differences in phytoplankton samples and their relationship with δ13C variation. When morphological and functional phytoplankton traits were superimposed, the NMS ordination showed that cylinder cells (for cell shape classes, class 500-2000 mm3 (for cell size classes and Group 6 (for MBFG were the most related to δ13C variation. Our study confirms that the variation in the pelagic δ13C seston most probably reflects changes in phytoplankton carbon isotopic signature, consequent to changes in availability of carbon sources depending on the season and due to different isotopic fractionation of phytoplankton taxonomic groups. Statistical investigations have allowed us to investigate the potential role of phytoplankton morphological and functional traits in the seasonal variation of δ13C

  3. Phytoplankton Community Structure and Its Relationship to Water Quality Parameters in a Compound Aquaculture System%复合养殖系统中浮游植物群落结构及其与水环境因子的关系

    Institute of Scientific and Technical Information of China (English)

    王璐; 李冰; 孙盛明; 王林; 张明明; 朱健

    2015-01-01

    .Then the sample was concentrated to 50 mL by settling for 24 h.The phyto-plankton qualitative and quantitative analysis were both conducted under an optical microscope.A total of 91 phyto-plankton species from 8 phyla were identified in the pond,including Bacillariophyta,Chlorophyta,Cyanophyta, Cryptophyta,Euglenophyta,Chrysophyta,Xanthophyta and Pyrrophyta.Among them,Chlorophyta (53 species) accounted for 58.24% of the total phytoplankton species,with absolute dominance,while the phytoplankton densi-ty was dominated by Cyanophyta,accounting for 79.82% of the total phytoplankton density.During the entire stud-y,phytoplankton species composition,density and biomass of the phytoplankton community did not change signifi-cantly in the pond.The phytoplankton density varied from 1.09 ×109 cells/L to 1.83 ×109 cells/L with an average of 1.52 ×109 cells/L and the phytoplankton biomass ranged from 8.76 mg/L to 11.03 mg/L with an average of 9.80 mg/L.The phytoplankton community was dominated by ten species including Scenedesmus bijuga,Crucigenia tetrapedia,Westella botryoides from Chlorophyta,and Merismopedia tenuissima,Gloeocapsa punctata,Oscillatoria li-mosa,Merismopedia elegans,Chroococcus minutus,Spirulina princeps,Microcystis incerta from Cyanophyta.The Shannon-Wiener diversity index,Margalef richness index and Pielou evenness index of the phytoplankton communi-ty were in the range of 2.77 -3.27,2.75 -3.18,and 0.45 -0.55,respectively,indicating that the phytoplank-ton community structure in the pond was very stable.Redundancy analysis shows that phytoplankton density in the pond was closely related with several environmental variables.Chlorella vulgaris,Crucigenia tetrapedia from Chlo-rophyta were mainly affected by temperature,dissolved oxygen,and pH,while Merismopedia tenuissima,Gloeocap-sa punctata in Cyanophyta were mainly affected by pH and ammonia nitrogen.%以主养团头鲂(Megalobrama amblycephala)搭配少量鲢(Hypophthalmichthys molitrix

  4. 石臼湖江苏段浮游植物群落结构特征及与环境因子的关系%Phytoplankton Community Structure and Its Relationship to Environmental Factors in Shijiu Lake (Jiangsu section)

    Institute of Scientific and Technical Information of China (English)

    国超旋; 王冬梅; 胡晓东; 吴沛沛

    2016-01-01

    Shijiu Lake is the only riparian shallow lake connecting with the lower Yangtze River.In recent years, human activities have severely disturbed the natural environment of Shijiu Lake and concern over water quality and the aquatic ecosystem is increasing.In this study,we completed the first investigation of the phytoplankton commu-nity and primary water quality parameters in the Jiangsu Section of Shijiu Lake.After gathering data,characteristics of the phytoplankton community were analyzed and phytoplankton dynamics,in response to environmental factors, were explored.The study provides data on the aquatic environment and biological resources of Shijiu Lake and will support environmental protection.In October of 201 2 and February,May and August of 201 3,the phytoplankton investigation was carried out at 1 2 sampling sites in Shijiu Lake.The environmental parameters measured in situ in-cluded pH,dissolved oxygen (DO),transparency (SD),depth,turbidity(Tur),total dissolved solids,water temperature (WT)and conductivity (Cond).Samples were also collected for laboratory analysis that included the 5-day biological oxygen demand (BOD5 ),total nitrogen (TN),total phosphorus (TP),permanganate chemical oxygen demand (CODMn )and ammonium nitrogen (NH4-N).A total of 79 phytoplankton species belonging to 8 phyla and 53 genera were identified.Chlorophyta (39 species),Cyanophyta (1 3 species)and Bacillariophyta (1 1 species)dominated the phytoplankton community,accounting for 50.65%,1 6.88% and 1 4.29% of the total species,respectively.During the investigation,1 0 dominant species were observed.Diatoms,adaptable to low wa-ter temperature and light intensity were the dominant phylum in winter.The dominant species were rich in spring, but the dominance values were low (0.03 -0.09).Filamentous blue-green algae dominated in summer and au-tumn.The cell density of phytoplankton ranged from 8.44 ×1 06 to 64.77 ×1 06 cells/L,with an average value of 28.93 ×1 06 cells

  5. 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.

  6. 太湖流域主要河道浮游植物类群对比研究%Comparison of the Phytoplankton Community in Major Rivers of the Taihu Basin

    Institute of Scientific and Technical Information of China (English)

    邓建明; 徐彩平; 陈宇炜; 邵晓阳; 高俊峰

    2011-01-01

    Phytoplankton assemblages were sampled in spring (13th-22nd April) and summer (10th - 19th July), 2010, and were compared in order to obtain basic information of the community of phytoplankton and their relationships with environmental factors among different rivers in the Taihu basin. Samples for phytoplankton were both identified and counted under a microscope at 400×. The results of counting shown that Synedra sp., Cryptomonas sp., Aulacoseira sp., Fragilaria sp. and Navicula sp. were the dominant genus in the inflowing rivers and Aulacoseira sp.,Scenedesmu sp., Cryptomonas sp., Asterionella sp. and Closterium sp. in outflowing rivers in spring. And in summer, the major genus in inflowing rivers were Synedra sp., Crucigenia sp.,Cryptomonas sp., Euglena and Microcystis sp. and were Aulacoseira sp., Scenedesmus sp.,Cryptomonas sp., Synedra sp. in outflowing rivers. That is to say the phytoplankton community is different between both in temporal and spatial distribution in Taihu basin. Then several diversity indices were calculated and the indices shown that diversity of phytoplankton in spring were slightly higher than in summer, and it was also varied among rivers. Liner regressions between diversity indices and environmental factors indicated that Shannon-Wiener diversity index had strong relationships with conductivity, total phosphorus (TP), total nitrogen (TN), total solid suspended (SS), chemical oxygen demand (CODMn) and nitrate (NO3--N) in spring and nitrate (NO3--N), chemical oxygen demand (CODMn) conductivity in summer. Further more, the most important environmental factors that regulated the phytoplankton community (basically analyzed according to predominated genus) were SS, TN, and conductivity in spring, and were CODMn,NO3--N and TN in summer as illuminated by the ordination of Canonical correspondence analysis (CCA).%2010年春季(4月13日-4月22日)和夏季(7月10日-7月19日)对太湖流域主要入湖河道进行了两次调查.对不同河

  7. Synergistic effects of UVR and simulated stratification on commensalistic phytoplankton-bacteria relationship in two optically contrasting oligotrophic Mediterranean lakes

    Science.gov (United States)

    Carrillo, P.; Medina-Sánchez, J. M.; Durán, C.; Herrera, G.; Villafañe, V. E.; Helbling, E. W.

    2015-02-01

    An indirect effect of global warming is a reduction in the depth of the upper mixed layer (UML) causing organisms to be exposed to higher levels of ultraviolet (UVR, 280-400 nm) and photosynthetically active radiation (PAR, 400-700 nm). This can affect primary and bacterial production as well as the commensalistic phytoplankton-bacteria relationship. The combined effects of UVR and reduction in the depth of the UML were assessed on variables related to the metabolism of phytoplankton and bacteria, during in situ experiments performed with natural pico- and nanoplankton communities from two oligotrophic lakes with contrasting UVR transparency (high-UVR versus low-UVR waters) of southern Spain. The negative UVR effects on epilimnetic primary production (PP) and on heterotrophic bacterial production (HBP), intensified under increased stratification, were higher in the low-UVR than in the high-UVR lake, and stronger on the phytoplanktonic than on the heterotrophic bacterial communities. Under UVR and increased stratification, the commensalistic phytoplankton-bacteria relationship was strengthened in the high-UVR lake where excretion of organic carbon (EOC) rates exceeded the bacterial carbon demand (BCD; i.e., BCD : EOC(%) ratio 100). The greater UVR damage to phytoplankton and bacteria and the weakening of their commensalistic interaction found in the low-UVR lake indicates that these ecosystems would be especially vulnerable to UVR and increased stratification as stressors related to global climate change. Thus, our findings may have important implications for the carbon cycle in oligotrophic lakes of the Mediterranean region.

  8. Genetic diversity and temporal dynamics of phytoplankton viruses in East Lake, China

    Institute of Scientific and Technical Information of China (English)

    Mei-Niang; Wang; Xing-Yi; Ge; Yong-Quan; Wu; Xing-Lou; Yang; Bing; Tan; Yu-Ji; Zhang; Zheng-Li; Shi

    2015-01-01

    Phytoplankton viruses are important components of aquatic ecosystems. However, their prevalence and genetic diversity in marine and freshwater systems are largely under estimated owing to the immense size of water bodies and limitations in virus discovery techniques. In this study, we conducted a 1-year survey of phytoplankton virus communities by collecting surface water monthly from an inland lake(East Lake) in China between May 2012 and April 2013. We examined four phytoplankton viruses, i.e., myoviruses, podoviruses, siphoviruses, and phycodnaviruses, and seven sets of primers were used to target conserved genes within these four species. In this year-long investigation, a total of 358 different virus-related sequences from four virus families were obtained. All virus families were detected in all months, except for cyanopodoviruses, which were only identified during eight of the 12 months surveyed. Moreover, virus abundance and diversity changed dynamically over time. Phylogenetic analysis revealed that the majority of viral sequences from East Lake, China displayed distinct clustering patterns compared with published sequences. These results supported the existence of a highly diverse and unique phytoplankton virus community in East Lake, China.

  9. Interactions of anthropogenic stress factors on phytoplankton

    Directory of Open Access Journals (Sweden)

    Donat P. Häder

    2015-03-01

    Full Text Available Phytoplankton are the main primary producers in aquatic ecosystems. Their biomass production and CO2 sequestration equals that of all terrestrial plants taken together. Phytoplankton productivity is controlled by a number of environmental factors, many of which currently undergo substantial changes due to anthropogenic global climate change. Light availability is an absolute requirement for photosynthesis, but excessive visible and UV radiation impair productivity. Increasing temperatures enhance stratification, decrease the depth of the upper mixing layer exposing the cells to higher solar radiation, and reduce nutrient upward transport from deeper layers. At the same time, stratospheric ozone depletion exposes phytoplankton to higher solar UV-B radiation especially in polar and mid latitudes. Terrestrial runoff carrying sediments and dissolved organic matter into coastal waters leads to eutrophication while reducing UV penetration. All these environmental forcings are known to affect physiological and ecological processes of primary producers. Ocean acidification due to increased atmospheric CO2 concentrations changes the seawater chemistry; it reduces calcification in phytoplankton, macroalgae and many zoological taxa and enhances UV-induced damage. Ocean warming results in changing species composition and favors blooms of toxic prokaryotic and eukaryotic phytoplankton; it moderates UV-induced damage of the photosynthetic apparatus because of higher repair rates. Increasing pollution from crude oil spills, persistent organic pollutants, heavy metal as well as industrial and household wastewaters affect phytoplankton, which is augmented by solar UV radiation. In view of the fact that extensive analyses of the impacts of multiple stressors are scarce, here we review reported findings on the impacts of anthropogenic stressors on phytoplankton with an emphasis on their interactive effects and a prospect for future studies.

  10. Annual variation of phytoplankton community in the north branch of the Yangtze River estuary%长江口北支浮游植物群落结构周年变化特征

    Institute of Scientific and Technical Information of China (English)

    刘笑; 薛俊增; 吴惠仙

    2014-01-01

    An annual survey was conducted on the community structure of phytoplankton from October 2010 to September 2011 at 5 sta-tions in the north branch of the Yangtze River estuary .A total of 183 phytoplankton species were identified , which belonged to 60 gene-ra of 7 phyla.Diatom was the major phytoplankton group which was 137 species of 35 genera and its species number accounted for 75%of all species .Melosira sulcata, Skeletonema costatum, Cyclotella striata, Oscillatoria amphibia, Pseudo-Nitzschia sicula v.Bicu-neata, Cyclotella sp.and Melosira granulata were the dominant species .Phytoplankton abundance difference was not significant among seasons ( p>0.05 ) , but monthly difference was significant ( p<0.05 ) .Phytoplankton density ranged from 2.83 ×10 3 to 6.18 ×10 4 cells/L with the nighest density in June and the lowest density in January .The annual average abundance was 1.73 10 4 cells/L.Corre-lation analysis found that the density of phytoplankton was significantly positively correlated to nitrate and ammonia .The impact of ni-trogenous nutrients for phytoplankton was significantly .%2010年10月至2011年9月对长江口北支水域的浮游植物进行周年调查,共采集到183种(包括变种和变型),隶属于7门60属,其中硅藻门种类最多,有35属137种,占浮游植物总种类数的75%。周年优势种为具槽直链藻、中肋骨条藻、条纹小环藻、两栖颤藻、小伪菱形藻双楔变种、颗粒直链藻和小环藻未定种。本次调查中,季节间浮游植物的丰度差异不显著(P>0.05),但各月间浮游植物丰度差异显著(P<0.05),全年丰度在2.83×103~6.18×104cells/L之间,其中6月的丰度最高,1月的丰度最低,全年的平均丰度为1.73×104cells/L。 Pearson相关性分析显示,浮游植物丰度与硝酸盐浓度显著正相关(P<0.05),与氨氮浓度极显著正相关(P<0.01),含氮营养盐对浮游植物的影响明显。

  11. Satellite-detected fluorescence reveals global physiology of ocean phytoplankton

    Directory of Open Access Journals (Sweden)

    M. J. Behrenfeld

    2008-11-01

    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 use satellite-based fluorescence measurements to evaluate light-absorption and energy-dissipation processes influencing phytoplankton light use efficiency and demonstrate its utility as a global physiological indicator of iron-limited growth conditions. This new tool provides a path for monitoring climate-phytoplankton physiology interactions, improving descriptions of light use efficiency in ocean productivity models, evaluating nutrient-stress predictions in ocean ecosystem models, and appraising phytoplankton responses to natural iron enrichments or purposeful iron fertilizations activities.

  12. Combined DNA and lipid analyses of sediments reveal changes in Holocene phytoplankton populations in an Antarctic lake

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Coolen, M.J.L.; Muyzer, G.; Rijpstra, W.I.C.; Schouten, S.; Volkman, J.K.

    2004-01-01

    Preserved ribosomal DNA of planktonic phototrophic algae was recovered from Holocene anoxic sediments of Ace Lake (Antarctica), and the ancient community members were identified based on comparative sequence analysis. The similar concentration profiles of DNA of haptophytes and their traditional lip

  13. Phytoplankton Monitoring Network (PMN)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Phytoplankton Monitoring Network (PMN) is a part of the National Centers for Coastal Ocean Science (NCCOS). The PMN was created as an outreach program to connect...

  14. Characterization of phytoplankton pigments and functional community structure in the Gulf of Mannar and the Palk Bay using HPLC–CHEMTAX analysis.

    Digital Repository Service at National Institute of Oceanography (India)

    Madhu, N.V.; Ullas, N.; Ashwini, R.; Meenu, P.; Rehitha, T.V.; Lallu, K.R.

    HPLC technique does not afford anything on species identification rather than the class level information (Suzuki et al., 1997; Barlow et al., 2008); however, this measurement is faster and reproducible for analysing a large set of samples compared... mathematical programme used to calculate the ratio of marker pigments to chlorophyll a, and an estimate of individual phytoplankton class biomass in terms of chlorophyll a. It is based on matrix factorization explained by Mackey et al (1996). The initial...

  15. Phytoplankton community dynamics during late spring coccolithophore blooms at the continental margin of the Celtic Sea (North East Atlantic, 2006–2008)

    OpenAIRE

    Van Oostende, Nicolas; Harlay, Jérôme; Vanelslander, Bart; Chou, Lei; Vyverman, Wim; Sabbe, Koen

    2012-01-01

    We determined the spatial and temporal dynamics of major phytoplankton groups in relation to biogeochemical and physical variables during the late spring coccolithophore blooms (May-June) along and across the continental margin of the northern Bay of Biscay (2006-2008). Photosynthetic biomass (Chla) of the dominant plankton groups was determined by CHEMTAX analysis of HPLC pigment signatures. We used uni- and multivariate statistical techniques to identify the main physical and biogeochemical...

  16. Imaging flow cytometry for phytoplankton analysis.

    Science.gov (United States)

    Dashkova, Veronika; Malashenkov, Dmitry; Poulton, Nicole; Vorobjev, Ivan; Barteneva, Natasha S

    2017-01-01

    This review highlights the concepts and instrumentation of imaging flow cytometry technology and in particular its use for phytoplankton analysis. Imaging flow cytometry, a hybrid technology combining speed and statistical capabilities of flow cytometry with imaging features of microscopy, is rapidly advancing as a cell imaging platform that overcomes many of the limitations of current techniques and contributed significantly to the advancement of phytoplankton analysis in recent years. This review presents the various instrumentation relevant to the field and currently used for assessment of complex phytoplankton communities' composition and abundance, size structure determination, biovolume estimation, detection of harmful algal bloom species, evaluation of viability and metabolic activity and other applications. Also we present our data on viability and metabolic assessment of Aphanizomenon sp. cyanobacteria using Imagestream X Mark II imaging cytometer. Herein, we highlight the immense potential of imaging flow cytometry for microalgal research, but also discuss limitations and future developments.

  17. The effect of nutrient supply ratios on organic matter dynamics, phytoplankton community composition and diazotrophy in the eastern tropical South Pacific

    Science.gov (United States)

    Meyer, J.; Lavik, G.; Riebesell, U.

    2015-12-01

    Upwelling of nutrient loaded water masses with low inorganic nitrogen (N) to phosphorus (P) ratios is thought to favor non-Redfield primary production by phytoplankton species adapted to exponential growth. Additionally, an excess of P (P*) in OMZ-influenced waters is also supposed to provide a niche for nitrogen fixing organisms. In order to assess the influence of low inorganic nutrient ratios on the stoichiometry and composition of primary producers, biogeochemical measurements were carried out in the eastern tropical South Pacific during R/V Meteor cruise M93. A succession of different functional types of phytoplankton was observed along onshore - offshore transects with diatoms dominating the productive upwelling region, while haptophytes, cryptophytes and crysophytes prevailed in the more oligotrophic open ocean. Simultaneously, particulate organic nitrogen to phosphorus ratios increased with increasing distance from shore. The stoichiometry of organic matter, however, always exceeded ratios of 16:1, although nutrient supply ratios were below Redfield proportions in the whole sampling area. A considerable amount of P* was detected in the surface ocean layer above the shelf, which decreased as water masses were advected beyond the shelf slope. Phytoplankton pigment analyses with HPLC revealed the existence of diazotrophic marker pigments in the study area, hinting towards a local replenishment of the N-deficit via nitrogen fixation.

  18. Coupling of heterotrophic bacteria to phytoplankton bloom development at different pCO2 levels: a mesocosm study

    Directory of Open Access Journals (Sweden)

    R. Thyrhaug

    2008-01-01

    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 linked to phytoplankton development and, hence, may also potentially depend on changes in pCO2.

  19. Quantification of environment-driven changes in epiphytic macroinvertebrate communities associated to Phragmites australis

    Directory of Open Access Journals (Sweden)

    Miguel CAÑEDO-ARGÜELLES

    2009-08-01

    Full Text Available The epiphytic macroinvertebrate communities associated with the Common Reed, Phragmites australis (Cav. Trin. ex Steudel, were examined seasonally from summer 2004 to spring 2005 in eleven coastal lagoons of the Llobregat Delta (NE Spain following the method proposed by Kornijów & Kairesalo (1994. The aims of the study were to: 1 characterise and quantify changes in epiphytic macroinvertebrate communities along environmental gradients; 2 assess the contribution of elements of the epiphytic compartment to structuring the community; 3 define the optima and tolerances of selected epiphytic macroinvertebrate taxa for the most relevant ecological factors responsible for assemblage composition; and 4 identify possible epiphytic species assemblages that would allow a lagoon’s typology to be established, as well as their representative indicator species. Communities showed statistically significant seasonal variation, with two faunal peaks: one in summer, with high chironomid densities, and the other in winter, with high naidid densities. These peaks showed a clear response to the influence of environmental factors. Salinity explained the highest percentage of total variance (36%, while trophic variables (nutrients, phytoplanktonic chlorophyll-a, and total organic carbon and epiphyton biomass (19.2 and 4% of total variance explained, respectively were secondary. Three different epiphytic macroinvertebrate species assemblages could be defined. These assemblages were directly linked to conductivity conditions, which determined the rate of survival of certain taxa, and to the existence of a direct connection with the sea, which permitted the establishment of "brackish-water" species. In spite of the existence of these species assemblages, the species composition and biomass of epiphytic macroinvertebrates and epiphyton differed substantially between lagoons; both elements were subject to changes in the environment, which finally determined the site

  20. Analysis of Phytoplankton Community Composition in Culturing Pond of Litopenaeus vannamei%凡纳滨对虾养殖水体中浮游植物群落的组成分析

    Institute of Scientific and Technical Information of China (English)

    李由明; 黄翔鹄; 李晓梅

    2012-01-01

    为了解凡纳滨对虾(Litopenaeus vannamei)池塘水体中浮游植物群落的组成及变化,本文对凡纳滨对虾养殖水体中浮游植物进行了分析.结果表明,养殖水体中的藻类共由21个种类组成,属于5大门类.浮游植物优势种群分别为绿藻门的小球藻(Chlorella sp)和波吉卵囊藻(Oocystis borgei),硅藻门的小环藻(Cyclostella sp.)、新月拟菱形藻(N.closterium sp.)、角毛藻(C.mueeleri sp.),蓝藻门的平裂藻(Merismopediasp.)和席藻(Phormidium sp.).在养殖早期和后期,浮游植物数量的变动范围分别为:0.5~2×107个/升和0.3~5×107个/升.%Phytoplankton community were analysed for the composition and variation of phytoplankton commu- nity of culturing pond of Litopenaeus vannamei in this paper. The results indicated that there were 21 species, be- longing to 5 Phylums in culturing pond. Dominant species of phytoplankton were Chlorella sp ,Oocystis, belonging to Chlorophyta and Cyclostella sp. ,N. closterium sp. ,C. mueeleri sp. , belonging to Bacillariophyta and Phormidium sp. ,Merismopedia sp. , belonging to Cyanophyta. In initial and final stage of culturing, the amount of phyto- plankton was 0.5 -2 × 107individuals/litre and 0.3 -5 × 107indiveduals/litre respectively.

  1. 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.

  2. 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.

  3. 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.

  4. The role of light for fish-zooplankton-phytoplankton interactions during winter in shallow lakes - a climate change perspective

    DEFF Research Database (Denmark)

    Bramm, Mette Elisabeth; Lassen, Majbritt Kjeldahl; Liboriussen, Lone;

    2009-01-01

    1. Variations in the light regime can affect the availability and quality of food for zooplankton grazers as well as their exposure to fish predation. In northern lakes light is particularly low in winter and, with increasing warming, the northern limit of some present-day plankton communities may...... in the life history of copepods. The strength of the fish effect on zooplankton biomass diminished with declining light and the effect of light was strongest in the presence of fish. 4. When fish were present, reduced light led to a shift from rotifers to calanoid copepods in the clear lake and from rotifers...

  5. Changes in production and respiration during a spring phytoplankton bloom in San Francisco Bay, California, USA: Implications for net ecosystem metabolism

    Science.gov (United States)

    Caffrey, J.M.; Cloern, J.E.; Grenz, C.

    1998-01-01

    We present results of an intensive sampling program designed to measure weekly changes in ecosystem respiration (oxygen consumption in the water column and sediments) around the 1996 spring bloom in South San Francisco Bay, California, USA. Measurements were made at a shallow site (2 m, where mean photic depth was 60% of the water column height) and a deep site (15 m, mean photic depth was only 20% of the water column). We also estimated phytoplankton primary production weekly at both sites to develop estimates of net oxygen flux as the sum of pelagic production (PP), pelagic respiration (PR) and benthic respiration (BR). Over the 14 wk period from February 5 to May 14, PP ranged from 2 to 210, PR from 9 to 289, and BR from 0.1 to 48 mmol O2 m-2 d-1, illustrating large variability of estuarine oxygen fluxes at the weekly time scale. Pelagic production exceeded total respiration at the shallow site, but not at the deep site, demonstrating that the shallow domains are net autotrophic but the deep domains are net heterotrophic, even during the period of the spring bloom. If we take into account the potential primary production by benthic microalgae, the estuary as a whole is net autotrophic during spring, net heterotrophic during the nonbloom seasons, and has a balanced net metabolism over a full annual period. The seasonal shift from net autotrophy to heterotrophy during the transition from spring to summer was accompanied by a large shift from dominance by pelagic respiration to dominance by benthic respiration. This suggests that changes in net ecosystem metabolism can reflect changes in the pathways of energy flow in shallow coastal ecosystems.

  6. Population dynamics of light-limited phytoplankton : Microcosm experiments

    NARCIS (Netherlands)

    Huisman, Jef

    1999-01-01

    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 cause

  7. 桂林市4个城中湖泊夏季浮游植物群落结构与水质评价%Characterization of Summer Phytoplankton Community and Water Quality Assessment of Four Guilin Lakes

    Institute of Scientific and Technical Information of China (English)

    陈朝述; 李俊; 陈孟林; 于方明; 邓华; 周振明

    2015-01-01

    body and diversity of the algae community is an important index for evaluating its ecosystem function .In this study , spatial variation of the summer phytoplankton community including species composition , species number and density were investigated from July 11 to August 10 , 2013 in Sihu Lake of Guilin .The water quality was also evalu-ated using the Carlson trophic status index ( TSIm) and phytoplankton biodiversity to provide basic data for water pollution control and ecological management of Sihu Lake .Eight sampling sites were selected based on direction of water flow in the four lakes , distributed in the central area of each lake and the intersection of each two lakes .Phy-toplankton samples for qualitative analysis were collected using No .25 plankton net , preserved in white glass bottles and fixed with 5%formalin.1 L water samples for phytoplankton quantitative analysis were collected at 0.5 m be-low the surface using a glass water sampler and placed in polyethylene bottles and fixed with 15 mL of Lugol′s solu-tion.Then the samples were concentrated to 30 mL by settling in the laboratory .Counting and identification of all phytoplankton samples were accomplished with an algae intelligent identification counter (Algacount S300).Meas-urements of pH and DO were made in situ before sampling and water samples were collected for determination of water quality parameters including TN , TP, NH3-N, NO3-N, CODMn and Chl-a.Concentrations of TN and TP in the four lakes ranged from 0.78 mg/L to 0.93 mg/L and 0.074 mg/L to 0.105 mg/L, with mean values of 0.86 mg/L and 0.087 mg/L, respectively.In all sampling sites, TP concentrations were relatively high and all ex-ceeded grade Ⅲof the ground water quality standard in China .A total of 117 species from 58 genera of 7 phyla were identified in Sihu Lake , including 54 species of Chlorophyta , 37 species of Bacillariophyta , 12 species of Cya-nophyta , 9 species of Euglenophyta , 3 species of Pyrrophyta , 1 species of

  8. Co-occurrence patterns in aquatic bacterial communities across changing permafrost landscapes

    Science.gov (United States)

    Comte, J.; Lovejoy, C.; Crevecoeur, S.; Vincent, W. F.

    2016-01-01

    Permafrost thaw ponds and lakes are widespread across the northern landscape and may play a central role in global biogeochemical cycles, yet knowledge about their microbial ecology is limited. We sampled a set of thaw ponds and lakes as well as shallow rock-basin lakes that are located in distinct valleys along a north-south permafrost degradation gradient. We applied high-throughput sequencing of the 16S rRNA gene to determine co-occurrence patterns among bacterial taxa (operational taxonomic units, OTUs), and then analyzed these results relative to environmental variables to identify variables controlling bacterial community structure. Network analysis was applied to identify possible ecological linkages among the bacterial taxa and with abiotic and biotic variables. The results showed an overall high level of shared taxa among bacterial communities within each valley; however, the bacterial co-occurrence patterns were non-random, with evidence of habitat preferences. There were taxonomic differences in bacterial assemblages among the different valleys that were statistically related to dissolved organic carbon concentration, conductivity and phytoplankton biomass. Co-occurrence networks revealed complex interdependencies within the bacterioplankton communities and showed contrasting linkages to environmental conditions among the main bacterial phyla. The thaw pond networks were composed of a limited number of highly connected taxa. This "small world network" property would render the communities more robust to environmental change but vulnerable to the loss of microbial "keystone species". These highly connected nodes (OTUs) in the network were not merely the numerically dominant taxa, and their loss would alter the organization of microbial consortia and ultimately the food web structure and functioning of these aquatic ecosystems.

  9. Studies on the phytoplankton of the deep subalpine Lake Iseo

    Directory of Open Access Journals (Sweden)

    Rosario MOSELLO

    2003-08-01

    Full Text Available This paper reports the results of investigations carried out on the chemical characteristics and phytoplankton community of Lake Iseo. Samplings were performed on a monthly basis from 1998 to 2000. At least three main algal groups dominated the community throughout the study period. The large Bacillariophyceae were dominant mainly during late winter and early spring (Aulacoseira spp., Melosira varians, Asterionella formosa, with few species able to maintain occasional positive growth also during mid summer and/or autumn (Fragilaria crotonensis and Diatoma elongatum. The thermal stability of the water column and silica depletion were the main factors responsible for the decline of the large spring diatoms. The subsequent growth of Mougeotia sp. (Conjugatophyceae was favoured by its lower sinking rate and resistance to increasing grazing pressure by the dominant copepods (Copidodiaptomus steueri and cladocerans (Daphnia hyalina × galeata. Among the cyanobacteria, the greater development of Planktothrix rubescens in the autumn months, with conditions of vertical homogenisation and decreasing Zeu/Zmix ratios, was favoured by its ability to survive at low light irradiances. The temporal replacement of these three groups constitutes the main sequence of the annual phytoplankton succession in Lake Iseo. A large development of other algal groups was recorded only in one or two of the three study years (e.g. Dinophyceae and Chlorococcales. The changes observed in the annual phytoplankton development are discussed in the light of differences in the spring fertilisation of the waters, caused by differences in the depth of the layer involved in the late winter and spring vertical mixing.

  10. Tackling climate change through community: the politics and practice of the low carbon communities challenge

    OpenAIRE

    Hauxwell-Baldwin, Richard

    2013-01-01

    Despite claims by academics and policymakers that community may offer a potentially useful context through which to tackle climate change, there is limited empirical evidence to support such an assertion. This thesis sets out to address that gap. Drawing on theories of the governance of environmental change, community, social interaction, and governmentality, it presents a qualitative case-study of the Low Carbon Communities Challenge (LCCC). The LCCC was a United Kingdom governme...

  11. Effects of co-cultured fish species combination and formulated feed supplement on phytoplankton community in the enclosures with inte-grated culture of freshwater pearl mussel and fishes%不同鱼类混养组合与饲喂方式对鱼蚌综合养殖水体浮游植物群落结构的影响

    Institute of Scientific and Technical Information of China (English)

    唐金玉; 王岩; 戴杨鑫; 李由明

    2014-01-01

    the enclosures with integrated culture of freshwater pearl mussel Hyriopsis cumingii and fishes. Four treatments, including stocking of grass carp, gibel carp, silver carp and bighead carp with formulated feed supplement (GISB-F ), stocking of grass carp, gibel carp, silver carp and bighead carp without formulated feed supplement (GISB-NF), stocking of silver carp and bighead carp with formulated feed supplement (SB-F), stocking of silver carp and bighead carp without formulated feed supplement (SB-NF), were examined. In each enclosure, 20 mussel, 15 grass carp, 5 gibel carp, 5 silver carp and 5 big-head carp were stocked, respectively. Results showed that the phytoplankton biomass ranged from 3.7 × 108 to 6.0 × 108 cell·L-1 during the experiment. No significant differences were found in the species composition, biomass and biodiver-sity index of phytoplankton, dominance index of the dominant species, and the ratio of cyanobacteria biomass to phy-toplankton biomass between enclosures GISB-F, GISB-NF, SB-F and SB-NF. However, the concentration of chloro-phyll a was higher in the enclosures fed formulated feed than in the enclosures without formulated feed supplement. Seasonal dynamics in phytoplankton community was observed. The dominant species of phytoplankton was green algae (Crucigenia and Scenedesmus) at the beginning of the experiment, and changed to blue-green algae (Merismopedia and Microcyslis) at the end of the experiment, suggesting the trend of occurrence of blue-green algae bloom. The factors that significantly influenced the alteration of community structure of phytoplankton included water temperature (T), ammonia (NH3-N), total nitrogen (TN) and chemical oxygen demand (CODMn). This result indicated that the changes of co-cultured species combination and formulated feed supplement could not change the trend that blue-green algal bloom finally occurred in the enclosures since NH3-N, TN and CODMn increased with the progress of the experiment.

  12. In Vivo Single-Cell Fluorescence and Size Scaling of Phytoplankton Chlorophyll Content.

    Science.gov (United States)

    Álvarez, Eva; Nogueira, Enrique; López-Urrutia, Ángel

    2017-04-01

    In unicellular phytoplankton, the size scaling exponent of chlorophyll content per cell decreases with increasing light limitation. Empirical studies have explored this allometry by combining data from several species, using average values of pigment content and cell size for each species. The resulting allometry thus includes phylogenetic and size scaling effects. The possibility of measuring single-cell fluorescence with imaging-in-flow cytometry devices allows the study of the size scaling of chlorophyll content at both the inter- and intraspecific levels. In this work, the changing allometry of chlorophyll content was estimated for the first time for single phytoplankton populations by using data from a series of incubations with monocultures exposed to different light levels. Interspecifically, our experiments confirm previous modeling and experimental results of increasing size scaling exponents with increasing irradiance. A similar pattern was observed intraspecifically but with a larger variability in size scaling exponents. Our results show that size-based processes and geometrical approaches explain variations in chlorophyll content. We also show that the single-cell fluorescence measurements provided by imaging-in-flow devices can be applied to field samples to understand the changes in the size dependence of chlorophyll content in response to environmental variables affecting primary production.IMPORTANCE The chlorophyll concentrations in phytoplankton register physiological adjustments in cellular pigmentation arising mainly from changes in light conditions. The extent of these adjustments is constrained by the size of the phytoplankton cells, even within single populations. Hence, variations in community chlorophyll derived from photoacclimation are also dependent on the phytoplankton size distribution.

  13. Research on Cold Core Eddy Change and Phytoplankton Bloom Induced by Typhoons: Case Studies in the South China Sea

    Directory of Open Access Journals (Sweden)

    Xiao-dong Shang

    2015-01-01

    Full Text Available The effects of 8 typhoons which passed by coldcore eddy (CCE areas in the South China Sea (SCS from 1997 to 2009 were observed and evaluated. The changes in the preexisting CCE acted upon by typhoons were described by eddy kinetic energy (EKE and eddy available gravitational potential energy (EAGPE. The mechanical energy of CCE was estimated from a two-layer reduced gravity model. Comparing with the scenario that typhoon passes by the region without CCEs, the preexisting CCE area plays an important role in the increase of chlorophyll-a (chl-a concentration in the CCEs impacted by the typhoons. The preexisting chl-a in CCE is about 25%~45% (8%~25% of postexisting chl-a in CCE for higher (slower transit speed typhoons. If the EAGPE of CCE increases greatly after typhoon passing by with slow transit speed, so does the chl-a in the CCE area. The EKE (EAGPE changes of the preexisting CCE are in the order of O(1014~1015 J. EKE and EAGPE of CCE are dominantly enhanced by typhoon with slow transit speed (<3 m/s and the posttyphoon EAGPE is always larger than posttyphoon EKE for 8 cases. The maximum EAGPE change of the preexisting CCE reaches 5.11×1015 J, which was induced by typhoon Hagibis.

  14. Winter Phytoplankton Assemblages of Coastal Yellow Sea Connected to Jiaozhou Bay, China

    Institute of Scientific and Technical Information of China (English)

    WEN Lixia; SUN Jun; HE Qing; WANG Dan; WANG Min

    2007-01-01

    The daily species variation of phytoplankton assemblage of coastal Yellow Sea connected to Jiaozhou Bay in the seawater around the Xiaoqingdao Island was studied for the three months of winter, 2003. A total of 79 taxa from four phyla, Bacillariophyta (52 species), Pyrrophyta (25 species), Chrysophyta (1 species), and Cyanophyta (1 species) were determined. In general,the most important groups were Bacillariophyta and Pyrrophyta on cell abundance and species richness. In January, the dominant species was mainly composed of cosmopolitan species such as Skeletonema costatum, then it changed to cosmopolitan species Thalassiosira nordenskiodii in February, and finally, it recovered to Skeletonema costatum again in March. Cell abundance ranged from 1.02 to 130.71 ×103 cells L-1 with a single peak on 6th Feb., and the average abundance was 28.11 ± 26.01 × 103 cells L-1 (n= 90) during the winter time. The trends of Shannon-Weiner diversity index and Pielou's evenness index were contrary to cell abundance, whereas the species diversity and evenness were the lowest in February. Temperature and salinity were closely correlated to phytoplankton species composition and cell abundance. According to the variations of temperature and salinity, species sequence was obvious at the studied site. This implies that the phytoplankton community of inner Jiaozhou Bay would be influenced heavily by the coastal Yellow Sea phytoplankton assemblages.

  15. Phytoplankton Bloom in North Sea off Scotland

    Science.gov (United States)

    2008-01-01

    The northern and western highlands of Scotland were still winter-brown and even dusted with snow in places, but the waters of the North Sea were blooming with phytoplankton on May 8, 2008, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite passed over the region and captured this image. The tiny, plant-like organisms swirled in the waters off the country's east coast, coloring the shallow coastal waters shades of bright blue and green. Phytoplankton are tiny organisms--many are just a single cell--that use chlorophyll and other pigments to capture light for photosynthesis. Because these pigments absorb sunlight, they change the color of the light reflected from the sea surface back to the satellite. Scientists have used observations of 'ocean color' from satellites for more than 20 years to track worldwide patterns in phytoplankton blooms. Phytoplankton are important to the Earth system for a host of reasons, including their status as the base of the ocean food web. In the North Sea, they are the base of the food web that supports Scotland's commercial fisheries, including monkfish and herring. As photosynthesizers, they also play a crucial role in the carbon cycle, removing carbon dioxide from the atmosphere. Some oceanographers are concerned that rising ocean temperatures will slow phytoplankton growth rates, harming marine ecosystems and causing carbon dioxide to accumulate more rapidly in the atmosphere.

  16. Optical community index to assess spatial patchiness during the 2008 North Atlantic Bloom

    Science.gov (United States)

    Cetinić, I.; Perry, M. J.; D'Asaro, E.; Briggs, N.; Poulton, N.; Sieracki, M. E.; Lee, C. M.

    2014-09-01

    The ratio of two in situ optical measurements, chlorophyll fluorescence (Chl F) and optical particulate backscattering (bbp), varied with changes in phytoplankton community composition during the North Atlantic Bloom experiment in the Iceland Basin in 2008. Using ship-based measurements of Chl F, bp, chlorophyll a (Chl), HPLC pigments, phytoplankton composition and carbon biomass, we found that oscillations in the ratio varied with changes in plankton community composition; hence we refer to Chl F/bp as an "optical community index". The index varied by more than a factor of two, with low values associated with pico- and nanophytoplankton and high values associated with diatom dominated phytoplankton communities. A Lagrangian mixed-layer float and four Seagliders, operating continuously for two months, made similar measurements of the optical community index and followed the evolution and later demise of the diatom spring bloom. Temporal changes in optical community index and, by implication the transition in community composition from diatom to post-diatom bloom communities, were not simultaneous over the spatial domain surveyed by the ship, float and gliders. Not only phytoplankton biomass, but also community composition was patchy at the submesoscale. The ratio of simple optical properties measured from autonomous platforms, when carefully validated, provides a tool for studying phytoplankton patchiness on extended temporal scales and ecological relevant spatial scales, and should offer new insights into the processes regulating patchiness.

  17. Optical community index to assess spatial patchiness during the 2008 North Atlantic Bloom

    Directory of Open Access Journals (Sweden)

    I. Cetinić

    2014-09-01

    Full Text Available The ratio of two in situ optical measurements, chlorophyll fluorescence (Chl F and optical particulate backscattering (bbp, varied with changes in phytoplankton community composition during the North Atlantic Bloom experiment in the Iceland Basin in 2008. Using ship-based measurements of Chl F, bp, chlorophyll a (Chl, HPLC pigments, phytoplankton composition and carbon biomass, we found that oscillations in the ratio varied with changes in plankton community composition; hence we refer to Chl F/bp as an "optical community index". The index varied by more than a factor of two, with low values associated with pico- and nanophytoplankton and high values associated with diatom dominated phytoplankton communities. A Lagrangian mixed-layer float and four Seagliders, operating continuously for two months, made similar measurements of the optical community index and followed the evolution and later demise of the diatom spring bloom. Temporal changes in optical community index and, by implication the transition in community composition from diatom to post-diatom bloom communities, were not simultaneous over the spatial domain surveyed by the ship, float and gliders. Not only phytoplankton biomass, but also community composition was patchy at the submesoscale. The ratio of simple optical properties measured from autonomous platforms, when carefully validated, provides a tool for studying phytoplankton patchiness on extended temporal scales and ecological relevant spatial scales, and should offer new insights into the processes regulating patchiness.

  18. Community Preparedness: Creating a Model for Change

    Science.gov (United States)

    2010-03-01

    such as tractor safety (Witte et al., 1993), Radon awareness (Witte et al., 1998b), teenage pregnancy (Witte, 1997), and HIV/AIDS in Africa (Witte...greater threats were “getting fat” or “losing friends.” Thus, the teens suggested that an 25 effective pregnancy prevention fear appeal should threaten...Witte, K. (1997). Preventing teen pregnancy through persuasive communications: Realities, myths, and the hard-fact truths. Journal of Community

  19. Community Changes Address Common Health Threat

    Centers for Disease Control (CDC) Podcasts

    2013-09-30

    This podcast helps residents living in multiunit housing, like apartments and condos, understand the threat of secondhand smoke. It also helps residents understand what steps they can take to breathe a little easier if involuntarily exposed to secondhand smoke.  Created: 9/30/2013 by Division of Community Health, National Center for Chronic Disease Prevention and Health Promotion.   Date Released: 9/30/2013.

  20. Community structure changes of macrobenthos in the South Yellow Sea

    Institute of Scientific and Technical Information of China (English)

    ZHANG Junlong; XU Fengshan; LIU Ruiyu

    2012-01-01

    The ecological environment in the Yellow Sea has changed greatly from the 1950s to 1990s and this has had significant impact on marine organisms.In this study,data on soft-sediment macrobenthos occurring in depths from 25 m to 81 m in the South Yellow Sea were used to compare changes in community structure.The agglomerative classification (CLUSTER) and multidimensional scaling (MDS) methods were applied.Five communities were recognized by cluster analysis:1.The Yellow Sea Cold Water Mass community dominated by cold water species,which changed slightly in species composition since the 1950s; 2.The mixed community with the coexistence of cold water species and warm water species,as had been reported previously; 3.The polychaete-dominated eurythermal community in which the composition changed considerably as some dominant species disappeared or decreased; 4.The Changjiang (Yangtze) River Estuarine community,with some typical estuarine species; 5.The community affected by the Yellow Sea Warm Current.The greatest change occurred in the coastal area,which indicated that the change may be caused by human activities.Macrobenthos in the central region remained almost unchanged,particularly the cold water species shielded by the Yellow Sea Cold Water Mass.The depth,temperature and median grain size of sediments were important factors affecting the distributions of macrobenthos in the South Yellow Sea.

  1. Landscape fragmentation affects responses of avian communities to climate change.

    Science.gov (United States)

    Jarzyna, Marta A; Porter, William F; Maurer, Brian A; Zuckerberg, Benjamin; Finley, Andrew O

    2015-08-01

    Forecasting the consequences of climate change is contingent upon our understanding of the relationship between biodiversity patterns and climatic variability. While the impacts of climate change on individual species have been well-documented, there is a paucity of studies on climate-mediated changes in community dynamics. Our objectives were to investigate the relationship between temporal turnover in avian biodiversity and changes in climatic conditions and to assess the role of landscape fragmentation in affecting this relationship. We hypothesized that community turnover would be highest in regions experiencing the most pronounced changes in climate and that these patterns would be reduced in human-dominated landscapes. To test this hypothesis, we quantified temporal turnover in avian communities over a 20-year period using data from the New York State Breeding Atlases collected during 1980-1985 and 2000-2005. We applied Bayesian spatially varying intercept models to evaluate the relationship between temporal turnover and temporal trends in climatic conditions and landscape fragmentation. We found that models including interaction terms between climate change and landscape fragmentation were superior to models without the interaction terms, suggesting that the relationship between avian community turnover and changes in climatic conditions was affected by the level of landscape fragmentation. Specifically, we found weaker associations between temporal turnover and climatic change in regions with prevalent habitat fragmentation. We suggest that avian communities in fragmented landscapes are more robust to climate change than communities found in contiguous habitats because they are comprised of species with wider thermal niches and thus are less susceptible to shifts in climatic variability. We conclude that highly fragmented regions are likely to undergo less pronounced changes in composition and structure of faunal communities as a result of climate change

  2. Influence of timing of sea ice retreat on phytoplankton size during marginal ice zone bloom period on the Chukchi and Bering shelves

    Science.gov (United States)

    Fujiwara, A.; Hirawake, T.; Suzuki, K.; Eisner, L.; Imai, I.; Nishino, S.; Kikuchi, T.; Saitoh, S.-I.

    2016-01-01

    The size structure and biomass of a phytoplankton community during the spring bloom period can affect the energy use of higher-trophic-level organisms through the predator-prey body size relationships. The timing of the sea ice retreat (TSR) also plays a crucial role in the seasonally ice-covered marine ecosystem, because it is tightly coupled with the timing of the spring bloom. Thus, it is important to monitor the temporal and spatial distributions of a phytoplankton community size structure. Prior to this study, an ocean colour algorithm was developed to derive phytoplankton size index FL, which is defined as the ratio of chlorophyll a (chl a) derived from cells larger than 5 µm to the total chl a, using satellite remote sensing for the Chukchi and Bering shelves. Using this method, we analysed the pixel-by-pixel relationships between FL during the marginal ice zone (MIZ) bloom period and TSR over the period of 1998-2013. The influences of the TSR on the sea surface temperature (SST) and changes in ocean heat content (ΔOHC) during the MIZ bloom period were also investigated. A significant negative relationship between FL and the TSR was widely found in the shelf region during the MIZ bloom season. However, we found a significant positive (negative) relationship between the SST (ΔOHC) and TSR. Specifically, an earlier sea ice retreat was associated with the dominance of larger phytoplankton during a colder and weakly stratified MIZ bloom season, suggesting that the duration of the nitrate supply, which is important for the growth of large-sized phytoplankton in this region (i.e. diatoms), can change according to the TSR. In addition, under-ice phytoplankton blooms are likely to occur in years with late ice retreat, because sufficient light for phytoplankton growth can pass through the ice and penetrate into the water columns as a result of an increase in solar radiation toward the summer solstice. Moreover, we found that both the length of the ice-free season

  3. Seymour Sarason in Memorial: Prospects for Community and Social Change

    Science.gov (United States)

    Maton, Kenneth I.

    2012-01-01

    Seymour Sarason passed away on January 10, 2010 at the age of 91. He was the author of more than 40 books, including The Culture of the School and the Problem of Change (1971), The Creation of Settings and the Future Societies (1972), and The Psychological Sense of Community: Prospects for a Community Psychology (1974). His groundbreaking ideas…

  4. How to Make a Healthy Change in Your Community Today

    Centers for Disease Control (CDC) Podcasts

    2012-04-15

    In this podcast, the speakers will discuss how to create healthy changes that benefit residents and businesses in local communities, as well as provide inspiration for other communities to make healthy living a priority.  Created: 4/15/2012 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 8/28/2012.

  5. The Role of the Change Agent in Community Development

    Science.gov (United States)

    Kristensen, Richard E.

    1974-01-01

    The article focuses on the change agent's possible interventions in efforts to ameliorate conditions in poverty-stricken communities, discussing his power role in three different models of social intervention: the service model, the community organization model, and the training model. The agent is urged to examine his own motives constantly. (AJ)

  6. Using Education to Bring Climate Change Adaptation to Pacific Communities

    Science.gov (United States)

    Vize, Sue

    2012-01-01

    Traditional communities remain a dominant feature in the Pacific and are key players in land and sea management. Fostering improved climate literacy is therefore essential to equip communities to respond to the current and future challenges posed by climate change in the region. Increased understanding and development of skills to respond to the…

  7. Short-term changes of the mesozooplankton community and copepod gut pigment in the Chukchi Sea in autumn

    Science.gov (United States)

    Matsuno, K.; Yamaguchi, A.; Nishino, S.; Inoue, J.; Kikuchi, T.

    2015-03-01

    In the Chukchi Sea, due to the recent drastic reduction of sea-ice during the summer, an increasing formation of atmospheric turbulence has been reported. However, the importance and effects of atmospheric turbulence on the marine ecosystem are not fully understood in this region. To evaluate the effect of atmospheric turbulence on the marine ecosystem, high-frequent sampling (two to four times per day) on the mesozooplankton community and the gut pigment of dominant copepods were made at a fixed station in the Chukchi Sea from 10 to 25 September 2013. During the study period, a strong wind event (SWE) was observed on 18 September. After the SWE, the standing stock of chlorophyll a (chl a) was increased, especially for micro-size (> 10 μm) fractions. Zooplankton abundance ranged 23 610-56 809 ind. m-2 and exhibited no clear changes with SWE. In terms of abundance, calanoid copepods constituted the most dominated taxa (mean: 57%), followed by barnacle larvae (31%). Within the calanoid copepods, small-sized Pseudocalanus spp. (65%) and large-sized Calanus glacialis (30%) dominated. In the population structure of C. glacialis, copepodid stage 5 (C5) dominated, and the mean copepodid stage did not vary with SWE. The dominance of accumulated lipids in C5 and C6 females with immature gonads indicated that they were preparing for seasonal diapause. The gut pigment of C. glacialis C5 was higher at night and was correlated with ambient chl a, and a significant increase was observed after SWE (2.6 vs. 4.5 ng pigment ind.-1). Assuming C : Chl a ratio, the grazing impact by C. glacialis C5 was estimated to be 4.14 mg C m-2 day-1, which corresponded to 0.5-4.6% of the standing stock of micro-size phytoplankton. Compared with the metabolic food requirement, their feeding on phytoplankton accounted for 12.6% of their total food requirement. These facts suggest that C. glacialis could not maintain their population on solely phytoplankton food, and other food sources (i

  8. 于桥水库浮游植物群落结构及与水质关系研究%Relationship of Phytoplankton Community Structure and Water Quality in Yuqiao Reservoir

    Institute of Scientific and Technical Information of China (English)

    武丹; 韩龙; 卞少伟; 梅鹏蔚

    2015-01-01

    Yuqiao Reservoir,a large diversion and storage reservoir for the Luanhe-Tianjin Water Diversion Pro-ject,supports industrial,agricultural and urban domestic water usage in Tianjin.In recent years,the eutrophica-tion of Yuqiao Reservoir has become increasingly serious.In May,July,August,September and November of 2012,we investigated the composition and distribution of the phytoplankton community and the associated environ-mental factors at five sites in Yuqiao Reservoir,aiming to understand the relationship between phytoplankton and water quality.The collection,qualitative and quantitative analysis of phytoplankton were carried out according to methods found in the literature.Sixteen water quality parameters were determined including water temperature (T),suspended solids (SS),fluoride (F -),pH,DO,SD,CODMn ,CODCr,BOD5 ,NO2-N,NO3-N,NH3-N, TN,TP,SO2 -4 and Chl-a.A water quality index,biological indexes and comprehensive nutritional status index (TLI(∑ ))were used to evaluate the trophic status in Yuqiao reservoir and the relationship between phytoplankton and water quality was analyzed by redundancy analysis (RDA).A total 123 phytoplankton species from 7 phyla were identified,with primary dominance by Chlorophyta (64 species)with 52.0% of the total species.Among them,Microcystis aeruginosa,Microcystis flos-aquae in Cyanophyta and Chlamydomonas sp.,Pediastrum simplex in Chlorophyta were the dominant species.The abundance of phytoplankton in Yuqiao Reservoir ranged from 369.75 ×104 cells/L to 4 636.64 ×104 cells/L,with the average value of 1 353.00 ×104 cells/L,and the biomass ranged from 1.12 mg/L to 13.58 mg/L,with an average value of 4.61mg/L.The phytoplankton community structure ex-hibited significant seasonal variation,and the variations in species number,abundance and biomass all followed the same trend:summer - autumn - spring.The assessment based on the water quality index,biological indexes and comprehensive nutritional status index (TLI

  9. Behavioural change in an urban smart-grid community

    NARCIS (Netherlands)

    Milovanovic, Marko; Steg, Emmalina; Spears, Russell

    2014-01-01

    Achieving long term behavioral change is a challenging task, especially when it comes to changing energy use habits. In our research we explore the social route to behavioral change, and examine how people influence each other in urban communities. We explore the conditions under which individuals a

  10. Climate change adaptation strategy for the Folk Communities

    DEFF Research Database (Denmark)

    Abdul-Al-Pavel, Muha.; Khan, Mohammed Abu Sayed Arfin; Rahman, Syed Ajijur

    2013-01-01

    In Bangladesh, impacts on agriculture from extreme climate are increasingly vulnerable. On the other hand, folk communities are intensely depending on agriculture for their livelihoods. Climate change has already negatively affected the vegetable production by annual recurrent flood in Bangladesh...

  11. Influence of hydrography on the spatiotemporal variability of phytoplankton assemblages and primary productivity in Funka Bay and the Tsugaru Strait

    Science.gov (United States)

    Isada, Tomonori; Hirawake, Toru; Nakada, Satoshi; Kobayashi, Tsukuru; Sasaki, Ken'ichi; Tanaka, Yoshiyuki; Watanabe, Shuichi; Suzuki, Koji; Saitoh, Sei-Ichi

    2017-03-01

    Phytoplankton community structures and primary productivity were assessed in relation to the oceanographic conditions in the coastal waters of Funka bay and the eastern end of the Tsugaru Strait, adjacent to southwestern Hokkaido, Japan, from April 2010 to January 2012. Phytoplankton community compositions, as estimated from chemotaxonomic analysis based on high-performance liquid chromatography of pigments, showed diatom blooms during spring in both 2010 and 2011. However, spatial heterogeneity of chlorophyll a (Chl a) concentration and primary productivity were found between regions investigated within and outside of Funka Bay during the spring diatom blooms in April 2010. The low Chl a concentrations within Funka Bay in April 2010 were related to the depletion of dissolved inorganic macronutrients, which implies that this difference was related to both the small inflow of the cold Coastal Oyashio Current (COW) into the bay and the development of clockwise circulation caused by discharge of fresh water into the bay. After the spring diatom blooms, the major phytoplankton groups in the study area were Chl b-containing phytoplanktons (chlorophytes and prasinophytes) because of changes in salinity associated with river discharge during the melting season. The results indicate that these phytoplanktons play an important role in the carbon cycle after the spring bloom in Funka Bay and the eastern end of the Tsugaru Strait. The thermohaline fronts created by the COW and the Tsugaru Warm Water in late February produced north-south differences in phytoplankton community structures in the eastern end of the Tsugaru Strait. Diatoms with high Chl a concentrations dominated in the northern section of the front. In the southern section, the proportions of chlorophytes and cryptophytes were high. Increases in cyanobacterial abundance and temperature were detected in both regions. Additionally, the contribution of pico- plus nano-sized phytoplankton productivity to the total

  12. Investigation on the occurrence and significance of cyclic adenosine 3':5'-monophosphate in phytoplankton and natural aquatic communities

    Energy Technology Data Exchange (ETDEWEB)

    Francko, D.A.

    1980-01-01

    This study demonstrates, on the basis of several analyanalytical criteria, that the production and extracellular release of cyclic adenosine 3':5'-monophosphate (cAMP) is widespread among phytoplankton species. The production and release of CAMP varied markedly among different species grown under similar environmental conditions, and intraspecifically during the life cycle of a given algal species. This investigation marks the first time cAMP has been investigated in natural aquatic systems. An examination of epilimnetic lakewater samples from Lawrence Lake, a hardwater oligotrophic lake, and Wintergreen Lake, a hardwater hypereutrophic lake, both in southwestern Michigan, demonstrated that cAMP existed in both particulate-associated and dissolved forms in these systems.

  13. Changes in phytoplankton productivity and impacts on environment in the Zhejiang coastal mud area during the last 100 years%浙江近岸泥质区百年来浮游植物生产力的变化及对环境的响应

    Institute of Scientific and Technical Information of China (English)

    冯旭文; 段杉杉; 石学法; 刘升发; 赵美训; 杨海丽; 朱德弟; 王奎

    2013-01-01

      在210 Pb定年的基础上,对取自浙江沿岸泥质缺氧区的柱样沉积物开展了菜子甾醇、甲藻甾醇、长链烯酮等生物标志化合物分析,根据生物标志化合物含量及比例的分布特征,重建了泥质区110年来浮游植物生产力及群落结构变化。结果表明浙江近岸浮游植物生产力百年来呈上升趋势,自20世纪60年代开始上升,80年代以来有显著增加,浮游植物群落结构则均有甲藻比例上升、硅藻比例下降的趋势。研究认为,浙江沿岸泥质区百年来浮游植物生产力的提高与我国化肥施用量和长江氮的入海通量呈正相关,营养盐N∶P和N∶Si比值的增加导致浮游植物优势种由硅藻向甲藻的转变,说明自20世纪60年代,尤其是自20世纪80年代以来工农业快速发展、大型水利工程建设等人类活动是导致浙江沿岸泥质区海域浮游植物生产力提高及群落结构变化的主要因素。%A high resolution sediment core was selected in the Zhejiang coastal mud area ,which was also located within the hypoxia area. The biomarkers ,such as brassicasterol ,dinosterol and C37-Alkenone were determined on the 210 Pb-dated sediment core. According to the vertical distribution of the biomarkers and ratios in the core sedi-ments ,we reconstructed the changes in phytoplankton productivity and community structure over the last 110 years in the Zhejiang coastal region. The results indicated increased phytoplankton productivity during the last 100 years in the mud area. Phytoplankton productivity increased gradually starting in the 1960s and accelerated after the 1980s. The change of phytoplankton community structure showed an increasing relative contribution of dino-flagellates and a decreasing relative contribution of diatoms over the last 100 years. The increase in phytoplankton productivity in the Zhejiang coastal mud area corresponded to the increased use of fertilizer and nitrogen

  14. 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.

  15. Southern Ocean phytoplankton turnover in response to stepwise Antarctic cooling over the past 15 million years

    Science.gov (United States)

    Crampton, James S.; Cody, Rosie D.; Levy, Richard; Harwood, David; McKay, Robert; Naish, Tim R.

    2016-06-01

    It is not clear how Southern Ocean phytoplankton communities, which form the base of the marine food web and are a crucial element of the carbon cycle, respond to major environmental disturbance. Here, we use a new model ensemble reconstruction of diatom speciation and extinction rates to examine phytoplankton response to climate change in the southern high latitudes over the past 15 My. We identify five major episodes of species turnover (origination rate plus extinction rate) that were coincident with times of cooling in southern high-latitude climate, Antarctic ice sheet growth across the continental shelves, and associated seasonal sea-ice expansion across the Southern Ocean. We infer that past plankton turnover occurred when a warmer-than-present climate was terminated by a major period of glaciation that resulted in loss of open-ocean habitat south of the polar front, driving non-ice adapted diatoms to regional or global extinction. These findings suggest, therefore, that Southern Ocean phytoplankton communities tolerate “baseline” variability on glacial-interglacial timescales but are sensitive to large-scale changes in mean climate state driven by a combination of long-period variations in orbital forcing and atmospheric carbon dioxide perturbations.

  16. 人工试验湖泊浮游藻类群落的生态学研究%ECOLOGICAL INFLUENCES OF PHYTOPLANKTON COMMUNITY IN AN EXPERIMENTAL MAN-MADE LAKE

    Institute of Scientific and Technical Information of China (English)

    夏爽; 张琪; 刘国祥; 胡征宇

    2013-01-01

    To evaluate the possible ecological risks of transgenic (CAgcGH) common carp, an experimental man-made lake was set up in 2002. We investigated the phytoplankton community structure, seasonal dynamics, annual variations of phytoplankton, as well as its relationships with environmental factors. Samples of phytoplankton were collected sea-sonally from 2006 to 2010. Sixty-six species belonging to seven phyla and forty-seven genera were identified, among which Chlorophyta was the most. The results of two-way indicators species analysis (TWINSPAN) and detrended cor-respondence analysis (DCA) showed that the samples were congregated into four groups, which indicated obvious sea-sonal character. In winter, the community structure was simple.The biodiversity was the lowest. The community was mainly composed of Cyclotella sp. and Dinobryon divergens;in spring, several diatoms, such as Cyclotella sp., Synedra sp. and Melosira granulata became dominant species;in summer, community structure was the most complex, with the highest biodiversity, and Merismopedia glauca and Lyngbya contarta were dominant. In our five-year-experiment, the cell density rose by 33.1%, and mean annual cell density was (1.43±0.75) ×106 cells/L;the percentage of diatoms in the phytoplankton community dropped from 48.2% to 16.2%, while the percentage of Cyanobacteria in the phytoplankton community rose from 9.3% to 42.2%. The results of canonical correlation analysis (CCA) demonstrated that the com-munity structure was mainly influenced by temperature and dissolved oxygen. The influence of the density of total phosphorus and nitrogen was non-negligitible, and the influence of pH was small. Diatoms mainly appeared in samples from middle and low temperature sites, blue-green algae mainly appeared in samples from high temperature sites, Des-midiales mainly appeared in samples from sites with high transparency and total phosphorus, and Chrysomonadales mainly appeared in samples from sites with high

  17. Bacterioplankton communities of Crater Lake, OR: Dynamic changes with euphotic zone food web structure and stable deep water populations

    Science.gov (United States)

    Urbach, E.; Vergin, K.L.; Larson, G.L.; Giovannoni, S.J.

    2007-01-01

    The distribution of bacterial and archaeal species in Crater Lake plankton varies dramatically over depth and with time, as assessed by hybridization of group-specific oligonucleotides to RNA extracted from lakewater. Nonmetric, multidimensional scaling (MDS) analysis of relative bacterial phylotype densities revealed complex relationships among assemblages sampled from depth profiles in July, August and September of 1997 through 1999. CL500-11 green nonsulfur bacteria (Phylum Chloroflexi) and marine Group I crenarchaeota are consistently dominant groups in the oxygenated deep waters at 300 and 500 m. Other phylotypes found in the deep waters are similar to surface and mid-depth populations and vary with time. Euphotic zone assemblages are dominated either by ??-proteobacteria or CL120-10 verrucomicrobia, and ACK4 actinomycetes. MDS analyses of euphotic zone populations in relation to environmental variables and phytoplankton and zooplankton population structures reveal apparent links between Daphnia pulicaria zooplankton population densities and microbial community structure. These patterns may reflect food web interactions that link kokanee salmon population densities to community structure of the bacterioplankton, via fish predation on Daphnia with cascading consequences to Daphnia bacterivory and predation on bacterivorous protists. These results demonstrate a stable bottom-water microbial community. They also extend previous observations of food web-driven changes in euphotic zone bacterioplankton community structure to an oligotrophic setting. ?? 2007 Springer Science+Business Media B.V.

  18. Phytoplankton size impact on export flux in the global ocean

    Science.gov (United States)

    Mouw, Colleen B.; Barnett, Audrey; McKinley, Galen A.; Gloege, Lucas; Pilcher, Darren

    2016-10-01

    Efficiency of the biological pump of carbon to the deep ocean depends largely on biologically mediated export of carbon from the surface ocean and its remineralization with depth. Global satellite studies have primarily focused on chlorophyll concentration and net primary production (NPP) to understand the role of phytoplankton in these processes. Recent satellite retrievals of phytoplankton composition now allow for the size of phytoplankton cells to be considered. Here we improve understanding of phytoplankton size structure impacts on particle export, remineralization, and transfer. A global compilation of particulate organic carbon (POC) flux estimated from sediment traps and 234Th are utilized. Annual climatologies of NPP, percent microplankton, and POC flux at four time series locations and within biogeochemical provinces are constructed. Parameters that characterize POC flux versus depth (export flux ratio, labile fraction, and remineralization length scale) are fit for time series locations, biogeochemical provinces, and times of the year dominated by small and large phytoplankton cells where phytoplankton cell size show enough dynamic range over the annual cycle. Considering all data together, our findings support the idea of high export flux but low transfer efficiency in productive regions and vice versa for oligotrophic regions. However, when parsing by dominant size class, we find periods dominated by small cells to have both greater export flux efficiency and lower transfer efficiency than periods when large cells comprise a greater proportion of the phytoplankton community.

  19. 元荡水域浮游植物的群落结构及水质评价%Phytoplankton Community Structure and Water Quality Assessment in Yuandang Lake Area

    Institute of Scientific and Technical Information of China (English)

    王忆; 钟俊生; 郁蔚文; 胡景; 陈立婧

    2016-01-01

    A preliminary survey was carried on phytoplankton community and species diversity of Yuandang Lake in 2013.It found a total of 111 species of phytoplankton belonging to 7 phyla and 72 genera, among which there are 35 genera and 48 species.43.24% of the total spe-cies were Chlorophyta.Phytoplankton biomass and density were 2.13 mg/L and 842.80 ×104 cells/L.Merismopedia.tenuissima, Oscillato-ria.amphbia, Oscillatoria splendida, Coelastrum microporum, Tribonema minus, etc.are the main dominant species.The dominant species of Cyanophyta appeared in spring, summer and autumn.The dominant species of Chlorophyta appeared in winter, and the Xanthophyta appeared in autumn and winter.Based on the analysis of statistics, the annual average values of Shannon-Wiener index, Margalef index, and Algae in-dex were 1.70, 1.13, 6.00 respectively, so this survey indicated that Yuandang Lake suffered from eutrophication.%2013年对元荡湖的浮游植物群落和物种多样性进行了初步调查研究,共发现浮游植物111种,隶属7门,72属,其中绿藻门为主要类群,35属48种,占浮游植物总物种的43.24%。浮游植物生物量和密度分别为2.13 mg/L和842.80×104 cells/L,主要优势种有微小平列藻(Merismopedia tenuissima)、两栖颤藻(Oscillatoria amphbia)、灿烂颤藻(Oscillatoria splendida)、小空心藻(Coelastrum microporum)、小型黄丝藻(Tribonema minus)等。蓝藻门的优势种出现在春、夏、秋季,绿藻门的优势种出现在冬季,黄藻门的优势种出现在秋冬季。Shannon-Wiener多样性指数全年均值为1.70,Margalef 丰富度指数全年均值为1.13,藻类综合指数全年均值为6.00,元荡湖水体呈富营养型。

  20. The annual cycles of phytoplankton biomass

    Science.gov (United States)

    Winder, M.; Cloern, J.E.

    2010-01-01

    Terrestrial plants are powerful climate sentinels because their annual cycles of growth, reproduction and senescence are finely tuned to the annual climate cycle having a period of one year. Consistency in the seasonal phasing of terrestrial plant activity provides a relatively low-noise background from which phenological shifts can be detected and attributed to climate change. Here, we ask whether phytoplankton biomass also fluctuates over a consistent annual cycle in lake, estuarine-coastal and ocean ecosystems and whether there is a characteristic phenology of phytoplankton as a consistent phase and amplitude of variability. We compiled 125 time series of phytoplankton biomass (chloro-phyll a concentration) from temperate and subtropical zones and used wavelet analysis to extract their dominant periods of variability and the recurrence strength at those periods. Fewer than half (48%) of the series had a dominant 12-month period of variability, commonly expressed as the canonical spring-bloom pattern. About 20 per cent had a dominant six-month period of variability, commonly expressed as the spring and autumn or winter and summer blooms of temperate lakes and oceans. These annual patterns varied in recurrence strength across sites, and did not persist over the full series duration at some sites. About a third of the series had no component of variability at either the six-or 12-month period, reflecting a series of irregular pulses of biomass. These findings show that there is high variability of annual phytoplankton cycles across ecosystems, and that climate-driven annual cycles can be obscured by other drivers of population variability, including human disturbance, aperiodic weather events and strong trophic coupling between phytoplankton and their consumers. Regulation of phytoplankton biomass by multiple processes operating at multiple time scales adds complexity to the challenge of detecting climate-driven trends in aquatic ecosystems where the noise to

  1. Influence of timing of sea ice retreat on phytoplankton size during marginal ice zone bloom period in the Chukchi and Bering shelves

    Directory of Open Access Journals (Sweden)

    A. Fujiwara

    2015-08-01

    Full Text Available Timing of sea ice retreat (TSR as well as cell size of primary producers (i.e., phytoplankton plays crucial roles in seasonally ice-covered marine ecosystem. Thus, it is important to monitor the temporal and spatial distribution of phytoplankton community size structure. Prior to this study, an ocean color algorithm has been developed to derive phytoplankton size index FL, which is defined as the ratio of chlorophyll a derived from the cells larger than 5 μm to the total chl a using satellite remote sensing for the Chukchi and Bering shelves. Using this method, we analyzed pixel-by-pixel relationships between FL during marginal ice zone (MIZ bloom period and TSR over a period of 1998–2013. The influence of TSR on sea surface temperature (SST and changes in ocean heat content (ΔOHC during the MIZ bloom period were also investigated. A significant negative relationship between FL and TSR was widely found in the shelf region during MIZ bloom season. On the other hand, we found a significant positive (negative relationship between SST (ΔOHC and TSR. That is, earlier sea-ice retreat was associated with a dominance of larger phytoplankton during a colder and weakly stratified MIZ bloom season, suggesting that duration of nitrate supply, which is important for large-sized phytoplankton growth in this region (i.e., diatoms, can change according to TSR. In addition, under-ice phytoplankton blooms are likely to occur in years with late ice retreat, because sufficient light for phytoplankton growth can pass through the ice and penetrate into the water columns due to an increase in solar radiation toward the summer solstice. Moreover, we found not only the length of ice-free season but also annual median of FL positively correlated with annual net primary production (APP. Thus, both phytoplankton community composition and growing season are important for APP in the study area. Our findings showed quantitative relationship between the inter

  2. Technological Change, Globalization, and the Community College

    Science.gov (United States)

    Romano, Richard M.; Dellow, Donald A.

    2009-01-01

    In early nineteenth-century England, workers now known as Luddites roamed the countryside destroying machinery that they saw as creating unemployment and upsetting their traditional way of life. They believed that the growing mechanization of production, what people would now call technological change, and the expanding volume of trade ushered in…

  3. Microbial community functional change during vertebrate carrion decomposition.

    Science.gov (United States)

    Pechal, Jennifer L; Crippen, Tawni L; Tarone, Aaron M; Lewis, Andrew J; Tomberlin, Jeffery K; Benbow, M Eric

    2013-01-01

    Microorganisms play a critical role in the decomposition of organic matter, which contributes to energy and nutrient transformation in every ecosystem. Yet, little is known about the functional activity of epinecrotic microbial communities associated with carrion. The objective of this study was to provide a description of the carrion associated microbial community functional activity using differential carbon source use throughout decomposition over seasons, between years and when microbial communities were isolated from eukaryotic colonizers (e.g., necrophagous insects). Additionally, microbial communities were identified at the phyletic level using high throughput sequencing during a single study. We hypothesized that carrion microbial community functional profiles would change over the duration of decomposition, and that this change would depend on season, year and presence of necrophagous insect colonization. Biolog EcoPlates™ were used to measure the variation in epinecrotic microbial community function by the differential use of 29 carbon sources throughout vertebrate carrion decomposition. Pyrosequencing was used to describe the bacterial community composition in one experiment to identify key phyla associated with community functional changes. Overall, microbial functional activity increased throughout decomposition in spring, summer and winter while it decreased in autumn. Additionally, microbial functional activity was higher in 2011 when necrophagous arthropod colonizer effects were tested. There were inconsistent trends in the microbial function of communities isolated from remains colonized by necrophagous insects between 2010 and 2011, suggesting a greater need for a mechanistic understanding of the process. These data indicate that functional analyses can be implemented in carrion studies and will be important in understanding the influence of microbial communities on an essential ecosystem process, carrion decomposition.

  4. Microbial community functional change during vertebrate carrion decomposition.

    Directory of Open Access Journals (Sweden)

    Jennifer L Pechal

    Full Text Available Microorganisms play a critical role in the decomposition of organic matter, which contributes to energy and nutrient transformation in every ecosystem. Yet, little is known about the functional activity of epinecrotic microbial communities associated with carrion. The objective of this study was to provide a description of the carrion associated microbial community functional activity using differential carbon source use throughout decomposition over seasons, between years and when microbial communities were isolated from eukaryotic colonizers (e.g., necrophagous insects. Additionally, microbial communities were identified at the phyletic level using high throughput sequencing during a single study. We hypothesized that carrion microbial community functional profiles would change over the duration of decomposition, and that this change would depend on season, year and presence of necrophagous insect colonization. Biolog EcoPlates™ were used to measure the variation in epinecrotic microbial community function by the differential use of 29 carbon sources throughout vertebrate carrion decomposition. Pyrosequencing was used to describe the bacterial community composition in one experiment to identify key phyla associated with community functional changes. Overall, microbial functional activity increased throughout decomposition in spring, summer and winter while it decreased in autumn. Additionally, microbial functional activity was higher in 2011 when necrophagous arthropod colonizer effects were tested. There were inconsistent trends in the microbial function of communities isolated from remains colonized by necrophagous insects between 2010 and 2011, suggesting a greater need for a mechanistic understanding of the process. These data indicate that functional analyses can be implemented in carrion studies and will be important in understanding the influence of microbial communities on an essential ecosystem process, carrion decomposition.

  5. 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.

  6. Determinants of beta diversity: the relative importance of environmental and spatial processes in structuring phytoplankton communities in an Amazonian floodplain Determinantes da diversidade beta: a importância relativa de processos ambientais e espaciais na estrutura de comunidades fitoplanctônicas de uma planície de inundação amazônica

    Directory of Open Access Journals (Sweden)

    Ina de Souza Nogueira

    2010-09-01

    Full Text Available AIM: Beta diversity is defined as the change in species composition along environmental gradients, and in the present study, we investigated the influence of local (i.e., environmental and regional (i.e., dispersal factors in community structure. The aims of this study were to evaluate the beta diversity of phytoplankton communities in the Curuaí floodplain and to determine the relative importance of environmental and spatial processes in shaping phytoplankton community structure; METHOD: The phytoplankton communities were sampled in 16 lakes of the Curuaí floodplain (Amazon Basin during high-water periods in 2002 and 2003. We used partial redundancy analysis (pRDA to evaluate the pure effect of environmental (six variables and spatial (spatial filter variability on phytoplankton community composition; RESULTS: There were 156 taxa recorded in the two study years, including 122 algae species in 2002 and 66 algae species in 2003. The beta diversity that we measured (βSIM index was 0.889 in 2002 and 0.789 in 2003. The partitioning variation demonstrated that the majority of variation in phytoplankton community structure was not significantly explained by pure environmental and pure spatial components. However, environmental variables presented a larger coefficient of determination than the spatial variable; CONCLUSION: Other factors than those we measured in this study, such as local variables (i.e., biotic interactions, hydrology, etc. and stochastic events, affected the absence of significant results in our data. Therefore, we suggest that additional variables, such as biological interactions and other local factors, should be considered in this type of analysis to increase its explanatory power for understanding the variation of diversity in these communities.OBJETIVO: A diversidade beta é definida como as mudanças na composição de espécies ao longo de um gradiente ambiental, e atualmente, ecólogos têm investigado a influência de

  7. 2009年秋季长江安徽-江苏段浮游植物群落的种类组成与空间特征%Phytoplankton Community Structure and Its Spatial Distribution along Anhui-Jiangsu Reaches of the Yangtze River in Autumn 2009

    Institute of Scientific and Technical Information of China (English)

    孟顺龙; 陈家长; 胡庚东; 吴伟; 瞿建宏; 范立民; 裘丽萍

    2012-01-01

    quanti- ties, biomass and the Mcnaughton's dominance indices were all measured and their spatial distribution characteristics were determined using cluster analysis. [Result] There were 27 species, belonging to 5 phyla, namely Chlorophyta, Bacillariophyta, Cyanophyta, Euglenophyta and Cryptophyta, of phytoplankton collected and identified from the surveys. Results showed that Bacillariophyta was the predominant phyto- plankton with 16 species collected which accounted for 59.3% of the total species identified. The number of species collected belonging to Chlorophyta, Cyanophyta, Cryptophyta and Euglenophyta were 6, 2, 2, and 1, accounting for 22.2%, 7.4%, 7.4% and 3.7% of the total number identified, respectively. At the species level, the predominant species were Fragilaria crotonensis, Melosira italica, Navicula crypto- cephala, Cyclotella striata and Chroomonas acuta. Phytoplankton abundance was ranging from 5.68×10^4 to 7.08×10^4 cells/L with its average of 6.01×10^4 cells/L. Phyto- plankton biomass was ranging from 30.43 to 34.73 μg/L with its average of 32.46 μg/L. Compared with the previous reports, the number of phytoplankton species was decreased but its abundance and biomass was increased along the Jiangsu reach of the Yangtze River. However, Bacillariophyta species were still the predominant species and the phytoplankton community structure had not significantly changed from the previous studies. [Conclusion] These results might be explained as that the water quality in the Yangtze River was deteriorated but had not come to the worst. The results of similarity analysis gave two clusters of phytoplankton community as Nanjing, Wuhu and Jiangyin sampling sites were clustered into one group and Tongling and Anqing were clustered into another group.

  8. Signs of the Land: Reaching Arctic Communities Facing Climate Change

    Science.gov (United States)

    Sparrow, E. B.; Chase, M. J.; Demientieff, S.; Pfirman, S. L.; Brunacini, J.

    2014-12-01

    In July 2014, a diverse and intergenerational group of Alaskan Natives came together on Howard Luke's Galee'ya Camp by the Tanana River in Fairbanks, Alaska to talk about climate change and it's impacts on local communities. Over a period of four days, the Signs of the Land Climate Change Camp wove together traditional knowledge, local observations, Native language, and climate science through a mix of storytelling, presentations, dialogue, and hands-on, community-building activities. This camp adapted the model developed several years ago under the Association for Interior Native Educators (AINE)'s Elder Academy. Part of the Polar Learning and Responding Climate Change Education Partnership, the Signs of the Land Climate Change Camp was developed and conducted collaboratively with multiple partners to test a model for engaging indigenous communities in the co-production of climate change knowledge, communication tools, and solutions-building. Native Alaskans have strong subsistence and cultural connections to the land and its resources, and, in addition to being keen observers of their environment, have a long history of adapting to changing conditions. Participants in the camp included Elders, classroom teachers, local resource managers and planners, community members, and climate scientists. Based on their experiences during the camp, participants designed individualized outreach plans for bringing culturally-responsive climate learning to their communities and classrooms throughout the upcoming year. Plans included small group discussions, student projects, teacher training, and conference presentations.

  9. Distribution patterns of phytoplankton in the Changjiang River estuary and adjacent waters in spring 2009

    Science.gov (United States)

    Kong, Fanzhou; Xu, Zijun; Yu, Rencheng; Yuan, Yongquan; Zhou, Mingjiang

    2016-09-01

    The Changjiang River estuary and adjacent waters are one of the most notable regions for red tides/harmful algal blooms in China's coastal waters. In this study, phytoplankton samples were collected and analyzed during the outbreak stage of red tides in May 2009. It was found that dinoflagellates, Prorocentrum donghaiense and Karenia mikimotoi, and diatoms, Skeletonema spp. and Paralia sulcata, were the major taxa dominating the phytoplankton community. Cluster analysis, non-metric multidimensional scaling (NMDS) and analysis of similarities (ANOSIM) was conducted on a data matrix including taxa composition and cell abundance of the phytoplankton samples. The analyses categorized the samples into three groups at a similarity level of 30%. Group I was characterized by estuarine diatoms and distributed mainly in the highly turbid estuarine region. Group II, which was dominated by the diatom Skeletonema spp. and represented the red tide of Skeletonema spp., was situated around Group I in the sea area west of 122°50'E. Group III was characterized by a high proportion of dinoflagellates and was found further offshore compared with Groups I and II. Group III was further divided into two subgroups (III-S1 and III-S2) at a similarity level of 40%. Group III-S1 was characterized by the presence of the benthic diatom P. sulcata, representing phytoplankton samples collected either from the bottom or from the sea area affected by upwelling. Group III-S2 was dominated by dinoflagellates and represented red tides formed by P. donghaiense and K. mikimotoi. A gradual change of red-tide causative species was observed from the estuary to the offshore sea area, from diatoms to armored dinoflagellates and then unarmored dinoflagellates. Environmental factors associated with each group, and thus affecting the distribution of phytoplankton and red tides, are discussed.

  10. Future Search in School District Change: Connection, Community, and Results

    Science.gov (United States)

    Schweitz, Rita; Martens, Kim; Aronson, Nancy; Weisbord, Marvin; Janoff, Sandra

    2005-01-01

    This book contains sixteen compelling case studies that illustrate the power of future search to create lasting, whole system change. Future Search in School District Change: Connection, Community, and Results chronicles ways in which educational institutions have used broad-based stakeholder involvement to improve education. These experiences, by…

  11. Do high concentrations of microcystin prevent Daphnia control of phytoplankton?

    Science.gov (United States)

    Chislock, Michael F; Sarnelle, Orlando; Jernigan, Lauren M; Wilson, Alan E

    2013-04-15

    Toxin-producing cyanobacteria have frequently been hypothesized to limit the ability of herbivorous zooplankton (such as Daphnia) to control phytoplankton biomass by inhibiting feeding, and in extreme cases, causing zooplankton mortality. Using limnocorral experiments in hyper-eutrophic ponds located in Alabama and Michigan (U.S.A.), we tested the hypothesis that high levels of cyanobacteria and microcystin, a class of hepatotoxins produced by several cyanobacterial genera, prevent Daphnia from strongly reducing phytoplankton abundance. At the start of the first experiment (Michigan), phytoplankton communities were dominated by toxic Microcystis and Anabaena (∼96% of total phytoplankton biomass), and concentrations of microcystin were ∼3 μg L⁻¹. Two weeks after adding Daphnia pulicaria from a nearby eutrophic lake, microcystin levels increased to ∼6.5 μg L⁻¹, yet Daphnia populations increased exponentially (r = 0.24 day⁻¹). By the third week, Daphnia had suppressed phytoplankton biomass by ∼74% relative to the no Daphnia controls and maintained reduced phytoplankton biomass until the conclusion of the five-week experiment. In the second experiment (Alabama), microcystin concentrations were greater than 100 μg L⁻¹, yet a mixture of three D. pulicaria clones from eutrophic lakes in southern MI increased and again reduced phytoplankton biomass, in this case by over 80%. The ability of Daphnia to increase in abundance and suppress phytoplankton biomass, despite high initial levels of cyanobacteria and microcystin, indicates that the latter does not prevent strong control of phytoplankton biomass by Daphnia genotypes that are adapted to environments with abundant cyanobacteria and associated cyanotoxins.

  12. Effects of Hyriopsis cumingii and Aristichthys nobilis on the enclosures phytoplankton community of Hypophthalmichthys molitrix pond%鲢、鳙对三角帆蚌池塘藻类影响的围隔实验

    Institute of Scientific and Technical Information of China (English)

    周小玉; 张根芳; 刘其根; 鄢灵兰; 李家乐

    2011-01-01

    以浙江金华汤溪威旺养殖基地的三角帆蚌养殖水体为研究对象,通过围隔实验比较研究了单养鲢、鳙和三角帆蚌的池塘浮游植物密度、生物量和优势种(属)组成等的差异,以及养蚌池混养鲢鳙对水体浮游植物密度、生物量以及优势种变化的影响.结果表明,养蚌(10#)围隔的浮游植物平均密度和生物量均显著高于高密度鲢(12#)围隔(P<0.05),其蓝藻数量及生物量显著高于高密度鲢(12#)和低密度鳙(13#)围隔(P<0.05),绿藻数量则显著低于低密度鲢单养(11#)围隔(P<0.05).在鱼蚌混养的情况下,单养蚌(10#)围隔浮游植物平均数量显著高于鲢-蚌混养(15#,16#)和鳙-蚌混养(17#,18#)围隔(P<0.05),其蓝藻数量及生物量极显著高于鲢-蚌混养(15#,16#)或鳙-蚌(17#,18#)围隔(P<0.01),其绿藻数量显著低于混养高密度鲢(16#)或低密度鳙(17#)的混养围隔(P<0.05).研究结果充分说明,鲢、鳙和三角帆蚌三者对水体藻类组成的影响有别,三角帆蚌养殖池中适当混养鲢或鳙可以有效控制蓝藻(铜绿微囊藻)的生长,促进绿藻(四尾栅藻)的生长,并最终有利于三角帆蚌的养殖,混养鲢密度的增加有利于控制藻类生长,而鳙密度的增加促进了裸藻等中大型藻类的生长.%Through the investigation on the enclosure phytoplankton community in pearl mussel ponds, we comparatively studied the different effects of silver carp (Hypophthalmichthys molitrix ), bighead carp (Aristichthys nobilis)and the pearl mussel Hyriopsis cumingii on quantity,biomass and dominant species of phytoplankton,and the effects of the two carps on the phytoplankton in mussel ponds. The results showed that the density and biomass of phytoplankton in mussel monocultured pond(10g) are significantly higher than those in high density of silver carp monocultured pond(12#) (P <0.05) ,the density and biomass of cyanobacteria in mussel pond is significantly higher than those

  13. Phytoplankton responses to atmospheric metal deposition in the coastal and open-ocean Sargasso Sea

    Directory of Open Access Journals (Sweden)

    Katherine Rose Marie Mackey

    2012-10-01

    Full Text Available This study investigated the impact of atmospheric metal deposition on natural phytoplankton communities at open-ocean and coastal sites in the Sargasso Sea during the spring bloom. Locally collected aerosols with different metal contents were added to natural phytoplankton assemblages from each site, and changes in nitrate, dissolved metal concentration, and phytoplankton abundance and carbon content were monitored. Addition of aerosol doubled the concentrations of cadmium, cobalt, copper, iron, manganese and nickel in the incubation water. Over the three-day experiments, greater drawdown of dissolved metals occurred in the open ocean water, whereas little metal drawdown occurred in the coastal water. Two populations of picoeukaryotic algae and Synechococcus grew in response to aerosol additions in both experiments. Particulate organic carbon (POC increased and was most sensitive to changes in picoeukaryote abundance. Phytoplankton community composition differed depending on the chemistry of the aerosol added. Enrichment with aerosol that had higher metal content led to a 10-fold increase in Synechococcus abundance in the oceanic experiment but not in the coastal experiment. Enrichment of aerosol-derived cobalt (Co, manganese, and nickel were particularly enhanced in the oceanic experiment, suggesting the Synechococcus population may have been fertilized by these aerosol metals. Copper (Cu-binding ligand concentrations were in excess of dissolved Cu in both experiments, and increased with aerosol additions. Bioavailable free hydrated Cu2+ concentrations were below toxicity thresholds throughout both experiments. These experiments show (1 atmospheric deposition contributes biologically important metals to seawater, (2 these metals are consumed over time scales commensurate with cell growth, and (3 growth responses can differ between distinct Synechococcus or eukaryotic algal populations despite relatively close geographic proximity and taxonomic

  14. Phytoplankton responses to atmospheric metal deposition in the coastal and open-ocean Sargasso Sea.

    Science.gov (United States)

    Mackey, Katherine R M; Buck, Kristen N; Casey, John R; Cid, Abigail; Lomas, Michael W; Sohrin, Yoshiki; Paytan, Adina

    2012-01-01

    This study investigated the impact of atmospheric metal deposition on natural phytoplankton communities at open-ocean and coastal sites in the Sargasso Sea during the spring bloom. Locally collected aerosols with different metal contents were added to natural phytoplankton assemblages from each site, and changes in nitrate, dissolved metal concentration, and phytoplankton abundance and carbon content were monitored. Addition of aerosol doubled the concentrations of cadmium (Cd), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), and nickel (Ni) in the incubation water. Over the 3-day experiments, greater drawdown of dissolved metals occurred in the open ocean water, whereas little metal drawdown occurred in the coastal water. Two populations of picoeukaryotic algae and Synechococcus grew in response to aerosol additions in both experiments. Particulate organic carbon increased and was most sensitive to changes in picoeukaryote abundance. Phytoplankton community composition differed depending on the chemistry of the aerosol added. Enrichment with aerosol that had higher metal content led to a 10-fold increase in Synechococcus abundance in the oceanic experiment but not in the coastal experiment. Enrichment of aerosol-derived Co, Mn, and Ni were particularly enhanced in the oceanic experiment, suggesting the Synechococcus population may have been fertilized by these aerosol metals. Cu-binding ligand concentrations were in excess of dissolved Cu in both experiments, and increased with aerosol additions. Bioavailable free hydrated Cu(2+) concentrations were below toxicity thresholds throughout both experiments. These experiments show (1) atmospheric deposition contributes biologically important metals to seawater, (2) these metals are consumed over time scales commensurate with cell growth, and (3) growth responses can differ between distinct Synechococcus or eukaryotic algal populations despite their relatively close geographic proximity and taxonomic similarity.

  15. Warming accelerates termination of a phytoplankton spring bloom by fungal parasites.

    Science.gov (United States)

    Frenken, Thijs; Velthuis, Mandy; de Senerpont Domis, Lisette N; Stephan, Susanne; Aben, Ralf; Kosten, Sarian; van Donk, Ellen; Van de Waal, Dedmer 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, which may change the type of food available for higher trophic levels. Some phytoplankton species are inedible to zooplankton, and the termination of their population by parasites may liberate otherwise unavailable carbon and nutrients. Phytoplankton spring blooms often consist of large diatoms inedible for zooplankton, but the zoospores of their fungal parasites may serve as a food source for this higher trophic level. Here, we investigated the impact of warming on the fungal infection of a natural phytoplankton spring bloom and followed the response of a zooplankton community. Experiments were performed in ca. 1000 L indoor mesocosms exposed to a controlled seasonal temperature cycle and a warm (+4 °C) treatment in the period from March to June 2014. The spring bloom was dominated by the diatom Synedra. At the peak of infection over 40% of the Synedra population was infected by a fungal parasite (i.e. a chytrid) in both treatments. Warming did not affect the onset of the Synedra bloom, but accelerated its termination. Peak population density of Synedra tended to be lower in the warm treatments. Furthermore, Synedra carbon: phosphorus stoichiometry increased during the bloom, particularly in the control treatments. This indicates enhanced phosphorus limitation in the control treatments, which may have constrained chytrid development. Timing of the rotifer Keratella advanced in the warm treatments and closely followed chytrid infections. The chytrids' zoospores may thus have served as an alternative food source to Keratella. Our study thus emphasizes the importance of incorporating not only nutrient limitation and grazing, but also parasitism in understanding the

  16. Global change and marine communities: Alien species and climate change

    Energy Technology Data Exchange (ETDEWEB)

    Occhipinti-Ambrogi, Anna [DET - Dip. di Ecologia del Territorio, Sezione di Ecologia, Universita degli Studi di Pavia, Via S. Epifanio 14, I-27100 Pavia (Italy)]. E-mail: occhipin@unipv.it

    2007-07-01

    Anthropogenic influences on the biosphere since the advent of the industrial age are increasingly causing global changes. Climatic change and the rising concentration of greenhouse gases in the atmosphere are ranking high in scientific and public agendas, and other components of global change are also frequently addressed, among which are the introductions of non indigenous species (NIS) in biogeographic regions well separated from the donor region, often followed by spectacular invasions. In the marine environment, both climatic change and spread of alien species have been studied extensively; this review is aimed at examining the main responses of ecosystems to climatic change, taking into account the increasing importance of biological invasions. Some general principles on NIS introductions in the marine environment are recalled, such as the importance of propagule pressure and of development stages during the time course of an invasion. Climatic change is known to affect many ecological properties; it interacts also with NIS in many possible ways. Direct (proximate) effects on individuals and populations of altered physical-chemical conditions are distinguished from indirect effects on emergent properties (species distribution, diversity, and production). Climatically driven changes may affect both local dispersal mechanisms, due to the alteration of current patterns, and competitive interactions between NIS and native species, due to the onset of new thermal optima and/or different carbonate chemistry. As well as latitudinal range expansions of species correlated with changing temperature conditions, and effects on species richness and the correlated extinction of native species, some invasions may provoke multiple effects which involve overall ecosystem functioning (material flow between trophic groups, primary production, relative extent of organic material decomposition, extent of benthic-pelagic coupling). Some examples are given, including a special

  17. Change in fish community structure in the Barents Sea.

    Directory of Open Access Journals (Sweden)

    Michaela Aschan

    Full Text Available Change in oceanographic conditions causes structural alterations in marine fish communities, but this effect may go undetected as most monitoring programs until recently mainly have focused on oceanography and commercial species rather than on whole ecosystems. In this paper, the objective is to describe the spatial and temporal changes in the Barents Sea fish community in the period 1992-2004 while taking into consideration the observed abundance and biodiversity patterns for all 82 observed fish species. We found that the spatial structure of the Barents Sea fish community was determined by abiotic factors such as temperature and depth. The observed species clustered into a deep assemblage, a warm water southern assemblage, both associated with Atlantic water, and a cold water north-eastern assemblage associated with mixed water. The latitude of the cold water NE and warm water S assemblages varied from year to year, but no obvious northward migration was observed over time. In the period 1996-1999 we observed a significant reduction in total fish biomass, abundance, mean fish weight, and a change in community structure including an increase in the pelagic/demersal ratio. This change in community structure is probably due to extremely cold conditions in 1996 impacting on a fish community exposed to historically high fishing rates. After 1999 the fish community variables such as biomass, abundance, mean weight, P/D ratio as well as community composition did not return to levels of the early 90s, although fishing pressure and climatic conditions returned to earlier levels.

  18. Controls on soil microbial community stability under climate change

    Directory of Open Access Journals (Sweden)

    Franciska T De Vries

    2013-09-01

    Full Text Available Soil microbial communities are intricately linked to ecosystem functioning because they play important roles in carbon and nitrogen cycling. Still, we know little about how soil microbial communities will be affected by disturbances expected with climate change. This is a significant gap in understanding, as the stability of microbial communities, defined as a community's ability to resist and recover from disturbances, likely has consequences for ecosystem function. Here, we propose a framework for predicting a community’s response to climate change, based on specific functional traits present in the community, the relative dominance of r- and K-strategists, and the soil environment. We hypothesize that the relative abundance of r- and K-strategists will inform about a community’s resistance and resilience to climate change associated disturbances. We also propose that other factors specific to soils, such as moisture content and the presence of plants, may enhance a community’s resilience. For example, recent evidence suggests microbial grazers, resource availability, and plant roots each impact on microbial community stability. We explore these hypotheses by offering three vignettes of published data that that we re-analyzed. Our results show that community measures of the relative abundance of r- and K-strategists, as well as environmental properties like resource availability and the abundance and diversity of higher trophic levels, can contribute to explaining the response of microbial community composition to climate change-related disturbances. However, further investigation and experimental validation is necessary to directly test these hypotheses across a wide range of soil ecosystems.

  19. Dynamic Changes of Microbial Community for Degradation of Lignocellulose

    Institute of Scientific and Technical Information of China (English)

    LI Wenzhe; LIU Shuang; WANG Chunying; ZHENG Guoxiang

    2010-01-01

    Dynamic changes of a microbial community for lignocellulose degradation were explored in details.Community composition and development were investigated by the means of denaturing gradient gel electrophoresis(DGGE),and results showed that the microbial community was constituted of 14 kinds of bacteria and presented the fluctuation in some degrees with fermentation.Furthmore,the result of cluster analysis of DGGE pattern was accordant with growth curve,and the degradation process was divided into three stages: initial stage(0-12 h),intermediate stage(24-144 h)and end stage(144-216 h).

  20. 长湖圆心湖夏季浮游植物群落结构特征分析%Community Structure of Phytoplankton and Water Quality Assessment of Yuanxinhu Area of Lake Changhu in Summer

    Institute of Scientific and Technical Information of China (English)

    聂细荣; 周淼; 黄俊; 郭坤; 柴毅; 罗静波; 杨德国; 何勇凤; 邓义

    2016-01-01

    To study phytoplankton community structures and assess water quality in Yuanxinhu area, lake Changhu,a survey was carried out in this area in July of 2015. Biodiversity of phytoplankton in this area were measured by using Shannon index,Pielou index and Margalef index,water quality was assessed based on these indices. The results showed that,a total of 49 phytoplankton species were iden-tified,which belong to 6 phyla. Species number in Chlorophyta was 27,accounted for 55. 10% of the total,following by Cyanophyta and Bacillariophyta,whose numbers were 12(accounted for 24. 49%) and 6(accounted for 12. 24%)respectively. Ratios between density of species in Cyanophyta and the total in each site were larger than 66 . 45%,highest data of 85 . 53% was obtained in sites YXH4 . Density of phytoplankton ranged from 20. 88 í 106 cell/L to 51. 15 í 106 cell/L ,with an average of 29. 19 í106 cell/L . Seven dominant species were recognized,density of which accounted for 83. 42%to 92 . 53% in each site;Oscillatoria amphibia possessed the highest dominant index( 0 . 50 ),and its density accounted for 44. 71% of the total. Based on algal index and biodiversity indices ,it was indi-cated that Yuanxinhu area was in moderate eutrophic state.%为了解长湖圆心湖浮游植物群落结构特征及水质现状,于2015年7月对该区域进行采样调查,获得了浮游植物种类的分布及丰度数据,使用Shannon指数、均匀度指数、Margalef指数对浮游植物的多样性进行了测度,并对该区域的水质进行评价.此次调查共鉴定浮游植物6门49种(含变型变种),以绿藻门的种类为主,多达27种,其次为蓝藻门和硅藻门(分别为12和6种);各样点蓝藻门种类的丰度占比超过66.45%,在YXH4高达85.53%.各样点浮游植物丰度变化范围为20.88×106~51.15×106 cell/L,平均丰度为29.19×106 cell/L.应用优势度指数共筛选出优势种7种,其在各站点的丰度占比为83.42%~92.53%;

  1. 逊别拉河自然保护区浮游植物群落结构特征的初步研究%Study on Phytoplankton Community Structure in Xunbiela River Nature Reserve

    Institute of Scientific and Technical Information of China (English)

    李反修; 姜作发; 李喆; 霍堂斌

    2013-01-01

    An investigation was conducted on the community structure of phytoplankton in the Xunbiela River Nature Reserve from September to October in 2010, and the water quality of the Xunbiela River Nature Reserve was assessed with biotic indices. The results showed that the phytoplankton assemblage was composed of 50 species in total .belonging to eight taxonomic groups. Bacillar-iophyta were represented by the highest number of taxa (28) followed by Chlorophyta (15), Cyanophyta(2). The percentage of Crypto-phyta, Euglenophyta, Pyrrophyta, Chrysophyta and Xanthophyta was 14.0 %. Dominant species were Synedra acus, Fragilaria sp., Cy-clotella comta, Gomphonema constriction, Acicular sp., Newicula simples, Pinnularia sp., Cymbella sp., Cymbella cistula. The average cell density of phytoplankton was 183.47X 104ind.·L-1 and the average biomass was 4.3740 mg·L-1. Cell density and biomass of Bacil-lariophyta were the highest, 134.12x 104ind.·L-1 and 3.9354mg·L-1 respectively. The percentage of Bacillariophyta cell density and biomass were 61.82% and 89.9 % respectively. The diversity of phytoplankton in that river was abundant. In addition, combining of H' (3.01 )、J(0.88)diversity indices, the water quality was between os-clean type in Xunbiela River Nature Reserve. It provided a suitable habitat for fishes.%2010年9~10月,对逊别拉河自然保护区浮游植物群落结构进行了初步研究,并利用生物指数对逊别拉河自然保护区水质进行评价.结果表明,浮游植物共计8门50种,以硅藻为主,28种,占56.0%;绿藻次之,15种,占30.0%;蓝藻2种,占8.5%;隐藻、裸藻、甲藻、金藻、黄藻各1种,共占14.0%;优势种类及常见种全部为硅藻门种类:尖针杆藻Synedra acus、脆杆藻Fragilaria sp.、扭曲小环藻Cyclotella comta、缢缩异极藻Gomphonemaconstrictum、舟形藻Acicular sp.、简单舟形藻Navicula simples、羽文藻Pinnulariasp.、桥弯藻Cymbella sp.、箱形桥弯藻Cymbella cistula.

  2. 马颊河与徒骇浮游植物群落特征及水质初步评价%Phytoplankton community characterization and preliminary evaluation on water quality of Majia and Tuhai River in Haihe River basin

    Institute of Scientific and Technical Information of China (English)

    宋芬; 王卫民; 单保庆; 阎里清; 黎洁; 周洁

    2011-01-01

    The investigation of phytoplankton community characterization including species composition,population size, dominant species and saprobic indicators was conducted in order to evaluate the water quality of Majia and Tuhai River in Haihe River basin. The results revealed that 126 species of phytoplankton belonging to 7 phyla and 67 genera existed in Majia River, while 114 species of phytoplankton belonging to 7 phyla and 63 genera were found in Tuhai River. Chlorophyta was the richest algae in both rivers, followed by Bacillariophyta and Cyanophyta. Cyanophyta, Chlorophyta and Bacillariophyta were found in all the sampling sites (the frequency was 100%). Cyanophyta was absolute the majority in Majia River in population, which accounted for 53.59% ,while the Chlorophyta was predominant in Tuhai River,which accounted for 35. 73%. The average density of phytoplankton in Majia and Tuhai River were 22. 424 × 106 ind./L and 13. 950× 106 ind./L, respectively. The Shannon-Weaver index, Margalef index and Pielou index varied among 2. 48-4. 64,3. 62-9. 91 and 0. 47-0. 84 in Majia River, while 3.04-4.57,2. 94-10. 15 and 0. 63-0.82 in Tuhai River,respectively. The water quality of both rivers was preliminary evaluated based on above results. In conclusion water quality was good, can be labeled as mesotrophic, but had the potential to turn to eutrophication. So we should pay attention to protect the water quality and enhance the management of the both rivers.%对海河流域马颊河与徒骇河的浮游植物种类组成、种群数量、优势种、污染指示种等进行调查研究,结果表明马颊河浮游植物为126种,隶属7门67属;徒骇河浮游植物为114种,隶属7门63属.2条河流浮游植物种类组成均以绿藻为最多,其次是硅藻和蓝藻;各采样点蓝藻、绿藻和硅藻出现的频度均为100%.在种群数量上,马颊河蓝藻占绝对优势(占藻类数量的53.59%),而徒骇河绿藻占优势(占藻类数量的35.73%),马颊河

  3. Changes in viral and bacterial communities during the ice-melting season in the coastal Arctic (Kongsfjorden, Ny-Ålesund).

    Science.gov (United States)

    De Corte, Daniele; Sintes, Eva; Yokokawa, Taichi; Herndl, Gerhard J

    2011-07-01

    Microbial communities in Arctic coastal waters experience dramatic changes in environmental conditions during the spring to summer transition period, potentially leading to major variations in the relationship between viral and prokaryotic communities. To document these variations, a number of physico-chemical and biological parameters were determined during the ice-melting season in the coastal Arctic (Kongsfjorden, Ny-Ålesund, Spitsbergen). The bacterial and viral abundance increased during the spring to summer transition period, probably associated to the increase in temperature and the development of a phytoplankton bloom. The increase in viral abundance was less pronounced than the increase in prokaryotic abundance; consequently, the viral to prokaryotic abundance ratio decreased. The bacterial and viral communities were stratified as determined by Automated Ribosomal Intergenic Spacer Analysis and Randomly Amplified Polymorphic DNA-PCR respectively. Both the bacterial and viral communities were characterized by a relatively low number of operational taxonomic units (OTUs). Despite the apparent low complexity of the bacterial and viral communities, the link between these two communities was weak over the melting season, as suggested by the different trends of prokaryotic and viral abundance during the sampling period. This weak relationship between the two communities might be explained by UV radiation and suspended particles differently affecting the viruses and prokaryotes in the coastal Arctic during this period. Based on our results, we conclude that the viral and bacterial communities in the Arctic were strongly affected by the variability of the environmental conditions during the transition period between spring and summer.

  4. Effects of climate change on plant population growth rate and community composition change.

    Science.gov (United States)

    Chang, Xiao-Yu; Chen, Bao-Ming; Liu, Gang; Zhou, Ting; Jia, Xiao-Rong; Peng, Shao-Lin

    2015-01-01

    The impacts of climate change on forest community composition are still not well known. Although directional trends in climate change and community composition change were reported in recent years, further quantitative analyses are urgently needed. Previous studies focused on measuring population growth rates in a single time period, neglecting the development of the populations. Here we aimed to compose a method for calculating the community composition change, and to testify the impacts of climate change on community composition change within a relatively short period (several decades) based on long-term monitoring data from two plots-Dinghushan Biosphere Reserve, China (DBR) and Barro Colorado Island, Panama (BCI)-that are located in tropical and subtropical regions. We proposed a relatively more concise index, Slnλ, which refers to an overall population growth rate based on the dominant species in a community. The results indicated that the population growth rate of a majority of populations has decreased over the past few decades. This decrease was mainly caused by population development. The increasing temperature had a positive effect on population growth rates and community change rates. Our results promote understanding and explaining variations in population growth rates and community composition rates, and are helpful to predict population dynamics and population responses to climate change.

  5. Effects of climate change on plant population growth rate and community composition change.

    Directory of Open Access Journals (Sweden)

    Xiao-Yu Chang

    Full Text Available The impacts of climate change on forest community composition are still not well known. Although directional trends in climate change and community composition change were reported in recent years, further quantitative analyses are urgently needed. Previous studies focused on measuring population growth rates in a single time period, neglecting the development of the populations. Here we aimed to compose a method for calculating the community composition change, and to testify the impacts of climate change on community composition change within a relatively short period (several decades based on long-term monitoring data from two plots-Dinghushan Biosphere Reserve, China (DBR and Barro Colorado Island, Panama (BCI-that are located in tropical and subtropical regions. We proposed a relatively more concise index, Slnλ, which refers to an overall population growth rate based on the dominant species in a community. The results indicated that the population growth rate of a majority of populations has decreased over the past few decades. This decrease was mainly caused by population development. The increasing temperature had a positive effect on population growth rates and community change rates. Our results promote understanding and explaining variations in population growth rates and community composition rates, and are helpful to predict population dynamics and population responses to climate change.

  6. Coupling Spatiotemporal Community Assembly Processes to Changes in Microbial Metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Graham, Emily B.; Crump, Alex R.; Resch, Charles T.; Fansler, Sarah; Arntzen, Evan; Kennedy, David W.; Fredrickson, Jim K.; Stegen, James C.

    2016-12-16

    Community assembly processes govern shifts in species abundances in response to environmental change, yet our understanding of assembly remains largely decoupled from ecosystem function. Here, we test hypotheses regarding assembly and function across space and time using hyporheic microbial communities as a model system. We pair sampling of two habitat types through hydrologic fluctuation with null modeling and multivariate statistics. We demonstrate that dual selective pressures assimilate to generate compositional changes at distinct timescales among habitat types, resulting in contrasting associations of Betaproteobacteria and Thaumarchaeota with selection and with seasonal changes in aerobic metabolism. Our results culminate in a conceptual model in which selection from contrasting environments regulates taxon abundance and ecosystem function through time, with increases in function when oscillating selection opposes stable selective pressures. Our model is applicable within both macrobial and microbial ecology and presents an avenue for assimilating community assembly processes into predictions of ecosystem function.

  7. Effects of Sulfate on the Community Structure of Phytoplankton in Freshwater%硫酸盐对淡水浮游藻类群落结构的影响研究

    Institute of Scientific and Technical Information of China (English)

    钟远; 樊娟; 刘春光; 庄源益

    2009-01-01

    In order to promote the understanding of sulfate enrichnment on the growth and .sucession of phytoplanktion cotomunities in eutrophic freshwater body laboratory experiment of phytoplankton in a landscapc water body was conducted.Three treatment groups were set up in experiment:cantroal (G0),step by step enrichmenl (G1) and eurichmet at a time (G2). The resolt indicated that the addition of sulfate promoted the increase of Chloropbyta species and biomass, while inhibited the growth of native Cyanobacteria and diatom species. Species and biomass. of G0, G1 group were similar and much higher than those of G2 group. Avcrage biomass of G0, Gland G2 group was 98.46, 96.09 and 81.19 mg·L~(-1) , respectively. C0 group was almost always dominated by Cyanobacteria species such as P. corium and O. amphibia, dominant species in G1 and G2 groups changed from Cyannbacteria species to Chlorophyta species including S. quadricauda, G. radiate and S. obliqus. Compared with that of control group GO (1.49±0.32),the average community diversity indices of G1 (1.70 ±0.1g)and G2 groups ( 1.68±0.40) were elevated.%为了解硫酸盐含量增加对富营养化淡水水体藻类生长及群落演替的影响,对天津市某景观水体藻类进行了室内模拟试验研究.按硫酸盐投加方式分设对照组(G0)、逐步投加组(G1)和一次性投加组(G2).结果表明,向水中投加一定浓度硫酸盐可以抑制原有蓝藻和硅藻生长,而绿藻种类和生物量增加.G0和G1组的种类数和生物量相近但是大于G2组.G0、G1和G2组的平均总生物量分别为98.46、96.09和81.19 mg·L~(-1).对照组几乎始终是皮状席藻(P.corium)和两栖颤藻(0.amphibia)等蓝藻为第一优势种,而投加硫酸盐的G1和G2组优势种从皮状席藻和小颤藻(0.tenuis)等蓝藻向四尾栅藻(S.quadricauda)、放射多芒藻(G.radiate)和斜生栅藻(S.obliqus)等绿藻演替.群落平均多样性指数与对照组G0(1.49±0.32)相比,投加硫酸盐的G1(1.70±0

  8. Environment Changes of Lampao Dam Communities in Northeast Thailand

    Directory of Open Access Journals (Sweden)

    Winyoo Sata

    2008-01-01

    Full Text Available Problem statement: The objective of this research was to study the environment change of Lampao Dam communities in Northeast Thailand, being a case study of the Sa-Adnathom community, Lamklong sub-district, Muang, Kalasin province, adjacent to the Lampao Dam. Approach: A qualitative research, it started with a review of literature and related researches. Field data were collected by way of interviews and both participant and non-participant observations, involving 15 informants including senior-villagers, who had lived in the village some 10-20 years. The research data were descriptively analyzed and presented. Results: As a result its was found that the Lampao Dam communities date back 200 years to the era of Chiangsom Kingdom. Deserted due to deadly epidemics, the area was later on repopulated by migrants from Yang Talad district, Kalasin province. A new community, called Sa-Adnathom, was born. Prior to the inception of the National Plan for Social and Economic Development in 1961, the environment of this community was complete with fertile land and natural resource abundance. People lived in harmony with nature and relied on resources from it for their livelihood, especially from Nong Waeng reservoir, Phan and Yang streams and Khoke Ngoo forest. But with the implementation of the first Plan for Social and Economic Development in 1961-1966 the Thai government started the construction of the Lampao Dam in 1963. Completed in 1968, the Dam took land from the villagers, part of which were simply flooded. This forced the village farmers to change their means of livelihood from relying on forest and rivers to production methods which by necessity involved purchase of machines and usage of chemical fertilizers. In short, a change from farming to fishing in Lampao Dam. Their values also changed from local exchanges of goods to money economy, which only led to household debts, increasing with rising degree of consumerism. Eventually people in the

  9. Effect of ocean acidification and elevated fCO2 on trace gas production by a Baltic Sea summer phytoplankton community

    Science.gov (United States)

    Webb, Alison L.; Leedham-Elvidge, Emma; Hughes, Claire; Hopkins, Frances E.; Malin, Gill; Bach, Lennart T.; Schulz, Kai; Crawfurd, Kate; Brussaard, Corina P. D.; Stuhr, Annegret; Riebesell, Ulf; Liss, Peter S.

    2016-08-01

    The Baltic Sea is a unique environment as the largest body of brackish water in the world. Acidification of the surface oceans due to absorption of anthropogenic CO2 emissions is an additional stressor facing the pelagic community of the already challenging Baltic Sea. To investigate its impact on trace gas biogeochemistry, a large-scale mesocosm experiment was performed off Tvärminne Research Station, Finland, in summer 2012. During the second half of the experiment, dimethylsulfide (DMS) concentrations in the highest-fCO2 mesocosms (1075-1333 µatm) were 34 % lower than at ambient CO2 (350 µatm). However, the net production (as measured by concentration change) of seven halocarbons analysed was not significantly affected by even the highest CO2 levels after 5 weeks' exposure. Methyl iodide (CH3I) and diiodomethane (CH2I2) showed 15 and 57 % increases in mean mesocosm concentration (3.8 ± 0.6 increasing to 4.3 ± 0.4 pmol L-1 and 87.4 ± 14.9 increasing to 134.4 ± 24.1 pmol L-1 respectively) during Phase II of the experiment, which were unrelated to CO2 and corresponded to 30 % lower Chl a concentrations compared to Phase I. No other iodocarbons increased or showed a peak, with mean chloroiodomethane (CH2ClI) concentrations measured at 5.3 (±0.9) pmol L-1 and iodoethane (C2H5I) at 0.5 (±0.1) pmol L-1. Of the concentrations of bromoform (CHBr3; mean 88.1 ± 13.2 pmol L-1), dibromomethane (CH2Br2; mean 5.3 ± 0.8 pmol L-1), and dibromochloromethane (CHBr2Cl, mean 3.0 ± 0.5 pmol L-1), only CH2Br2 showed a decrease of 17 % between Phases I and II, with CHBr3 and CHBr2Cl showing similar mean concentrations in both phases. Outside the mesocosms, an upwelling event was responsible for bringing colder, high-CO2, low-pH water to the surface starting on day t16 of the experiment; this variable CO2 system with frequent upwelling events implies that the community of the Baltic Sea is acclimated to regular significant declines in pH caused by up to 800 µatm fCO2. After

  10. Preparing the U.S. health community for climate change.

    Science.gov (United States)

    Jackson, Richard; Shields, Kyra Naumoff

    2008-01-01

    In society's effort to address and prepare for climate change, the health community itself must ensure that it is prepared. Health personnel will require flexible and iterative action plans to address climate change at the individual, hospital, local health department, state, and national levels. This requires that health workers analyze the impact of climate change with a view to human health, and then formulate robust policy and demonstrate authentic leadership. In this review, we summarize the status of the health community's preparation for climate change and provide specific recommendations for action at each level. Although preparation status and recommendations vary, our observation is that it is not enough for public health and medical care agencies and departments to develop policies and advocate change. They have a direct responsibility to demonstrate substantive leadership.

  11. Functional analysis and classification of phytoplankton based on data from an automated flow cytometer

    NARCIS (Netherlands)

    Malkassian, A.; Nerini, D.; Van Dijk, M.A.; Thyssen, M.; Mante, C.; Gregori, G.

    2011-01-01

    Analytical flow cytometry (FCM) is well suited for the analysis of phytoplankton communities in fresh and sea waters. The measurement of light scatter and autofluorescence properties of particles by FCM provides optical fingerprints, which enables different phytoplankton groups to be separated. A su

  12. Spatio-temporal patterns and predictions of phytoplankton assemblages in a subtropical river delta system

    DEFF Research Database (Denmark)

    2016-01-01

    Spatial and seasonal sampling within a subtropical river delta system, the Pearl River Delta (China), provided data to determine seasonal phytoplankton patterns and develop prediction models. The high nutrient levels and frequent water exchanges resulted in a phytoplankton community with greatest...

  13. Dinâmica da comunidade fitoplanctônica e variáveis físicas e químicas em tanques experimentais submetidos a diferentes adubações orgânicas Dynamics of the phytoplankton community and physical and chemical variables in experimental tanks with different organic manure

    Directory of Open Access Journals (Sweden)

    Claudemir Martins Soares

    2001-05-01

    Full Text Available Objetivando-se determinar a influência de diferentes adubos orgânicos na comunidade fitoplanctônica, realizou-se este experimento, com duração de 40 dias, em tanques de cimento amianto com capacidade para 1000l. Os tanques foram adubados com estercos de aves (EA, suínos (ES, bovinos (EB e coelhos (EC, em um delineamento inteiramente casualizado, com quatro tratamentos e cinco repetições. A primeira adubação foi de 50 g de esterco, sendo realizadas novas adubações com 25 g, em intervalos de sete dias. O plâncton foi coletado a cada três dias, filtrando-se 250 ml de água em rede de 20µm e fixados em 10mL de formalina 2%. A análise qualitativa e quantitativa foi realizada em microscópio óptico. Ao mesmo tempo, foram monitoradas algumas variáveis físicas e químicas. A densidade média mais elevada do fitoplâncton foi observada com o uso de EA no 40º dia (26.842 org./l, seguido de ES (17.164 org./L, no 22º dia, EC (8.880 org./L, no 28º dia e EB (5.564 org./l, no 22º dia. Houve predominância dos gêneros Scenedesmus, Cyclotella e Acanthosphaera. Os valores de pH e condutividade elétrica oscilaram conforme ocorriam alterações nas densidades do fitoplâncton. O uso de EA levou a maiores valores destes parâmetros na maioria das coletas. Conclui-se que os diferentes tratamentos exerceram influência na densidade dos grupos fitoplanctônicos; entretanto estercos de aves levaram à maior densidade de algas, seguidos por esterco de suínos, coelhos e bovinosThe influence of different types of organic manure in the phytoplankton community is provided. Experiment was undertaken during 40 days in 1000L asbestos tanks. Tanks were fertilized with poultry (PO, pig (PI, cattle (CA and rabbit (RA manure, in a randomized design, with four treatments and five replications. First fertilization consisted of 50 g of manure, with 25 g fertilizations at seven-day intervals. Plankton was collected every three days by filtering 250 mL of water

  14. Impact of zinc and iron on phytoplankton community structure during recruitment:A case study in Lake Xu-anwu, Nanjing%锌和铁对浅水湖泊中浮游植物复苏影响研究--以玄武湖为例

    Institute of Scientific and Technical Information of China (English)

    滕益莉; 王沛芳; 任凌霄; 王超; 钱进; 刘佳佳

    2016-01-01

    选取冬季12月的玄武湖水样,调整培养液的起始金属离子浓度(锌:0、3.25×10-4、3.25×10-3、3.25×10-2 mg·L-1;铁:0、2.80×10-4、2.80×10-3、2.80×10-2 mg·L-1),探讨金属离子锌、铁对浮游植物复苏过程中群落结构的影响。结果表明:当锌为3.25×10-2 mg·L-1时,蓝藻的复苏受到明显的抑制,绿藻及硅藻的生长受到胁迫作用,Fv/Fm值分别降至0.40、0.30、0;当铁浓度高于2.80×10-2 mg·L-1时,蓝藻的复苏同样受到抑制,Fv/Fm值降为0.45,而绿藻和硅藻的Fv/Fm分别为0.33和0.07。高铁浓度下复苏后的浮游植物以蓝藻门的微囊藻为主,绿藻门的栅藻次之;高浓度锌胁迫下复苏后的浮游植物主要为绿藻门的栅藻,其次是绿藻门的小球藻,再后是蓝藻门的微囊藻。%Many studies have focused on the effects of temperature, light and dissolved oxygen on the growth of phytoplankton. However, the understanding of metal effects on phytoplankton during recruitment remains unclear. In the present study, water samples taken from Xuanwu Lake in December have been used to clarify the relationship between metal concentration and community structure change during phyto-plankton recovery process. The initial zinc(0, 3.25í10-4, 3.25í10-3, 3.25í10-2 mg·L-1)and iron concentrations(0, 2.80í10-4, 2.80í10-3, 2.80í10-2 mg·L-1)were employed in cultivation experiment. Results showed that when zinc concentration was higher than 3.25í10-3 mg·L-1, the recruitment of blue algae was obviously inhibited and the growth of green algae and diatoms was reduced. The Fv/Fm values of these three algae were 0.4, 0.3 and 0,respectively. Similar results were also observed when iron concentration was over 2.80í10-4 mg·L-1. The re-cruitment of blue algae was inhibited. Fv/Fm values of blue algae, green algae and diatoms were reduced to 0.45, 0.33 and 0.07, respective-ly. It can be concluded that recruited phytoplankton was

  15. Changing nutrient stoichiometry affects phytoplankton production, DOP build up and dinitrogen fixation – a mesocosm experiment in the eastern tropical North Atlantic

    Directory of Open Access Journals (Sweden)

    J. Meyer

    2015-07-01

    Full Text Available Ocean deoxygenation due to climate change may alter redox-sensitive nutrient cycles in the marine environment. The productive eastern tropical North Atlantic (ETNA upwelling region may be particularly affected when the relatively moderate oxygen minimum zone (OMZ deoxygenates further and microbially-driven nitrogen (N loss processes are promoted. Consequently, water masses with a low N : P ratio could reach the euphotic layer, possibly influencing primary production in those waters. Previous mesocosm studies in the oligotrophic Atlantic Ocean identified N availability as controlling of primary production, while a possible co-limitation of nitrate and phosphate (P could not be ruled out. To better understand the impact of changing N : P ratios on primary production and on N2 fixation in the ETNA surface ocean, we conducted land-based mesocosm experiments with natural plankton communities and applied a broad range of N : P ratios (2.67–48. Silicate was supplied at 15 μmol L−1 in all mesocosms. We monitored nutrient drawdown, bloom formation, biomass build up and diazotrophic feedback in response to variable nutrient stoichiometry. Our results confirmed N to be limiting to primary production. We found that excess P was channeled through particulate organic matter (POP into the dissolved organic matter (DOP pool. In mesocosms with low P availability, DOP was utilized while N2 fixation increased, suggesting a link between those two processes. Interestingly this observation was most pronounced in mesocosms where inorganic N was still available, indicating that bioavailable N does not necessarily has to have a negative impact on N2 fixation. We observed a shift from a mixed cyanobacterial/proteobacterial dominated active diazotrophic community towards diazotrophic diatom symbionts of the Richelia-Rhizosolenia symbiosis. We hypothesize that a potential change in nutrient stoichiometry in the ETNA might lead to a general shift within the

  16. Analysis of phytoplankton composition from southern Malabar Coast during the 2005 monsoon as a follow-up of September 2004 stench event

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaiah, N.; Catul, V.; Kurian, S.; Rodrigues, V.; Paul, J.T.; Fernandes, V.; Imtiaz, C.A.

    . A continuous monitoring programme for documenting phytoplankton assemblages along the coast at some pre-decided locations is called for. Many issues related to global change, climate considerations and coastal phytoplankton biodiversity changes...

  17. Phytoplankton distribution in unusually low sea ice cover over the Pacific Arctic

    Directory of Open Access Journals (Sweden)

    P. Coupel

    2012-11-01

    Full Text Available A large part of the Pacific Arctic basin experiences ice-free conditions in summer as a result of sea ice cover steadily decreasing over the last decades. To evaluate the impact of sea ice retreat on the marine ecosystem, phytoplankton in situ observations were acquired over the Chukchi shelf and the Canadian basin in 2008, a year of high melting. Pigment analyses and taxonomy enumerations were used to characterise the distribution of main phytoplanktonic groups. Marked spatial variability of the phytoplankton distribution was observed in summer 2008. Comparison of eight phytoplankton functional groups and 3 size-classes (pico-, nano- and micro-phytoplankton also showed significant differences in abundance, biomass and distribution between summer of low ice cover (2008 and heavy ice summer (1994. Environmental parameters such as freshening, stratification, light and nutrient availability are discussed as possible causes to explain the observed differences in phytoplankton community structure between 1994 and 2008.

  18. Role of zooplankton dynamics for Southern Ocean phytoplankton biomass and global biogeochemical cycles

    Science.gov (United States)

    Le Quéré, Corinne; Buitenhuis, Erik T.; Moriarty, Róisín; Alvain, Séverine; Aumont, Olivier; Bopp, Laurent; Chollet, Sophie; Enright, Clare; Franklin, Daniel J.; Geider, Richard J.; Harrison, Sandy P.; Hirst, Andrew G.; Larsen, Stuart; Legendre, Louis; Platt, Trevor; Prentice, I. Colin; Rivkin, Richard B.; Sailley, Sévrine; Sathyendranath, Shubha; Stephens, Nick; Vogt, Meike; Vallina, Sergio M.

    2016-07-01

    Global ocean biogeochemistry models currently employed in climate change projections use highly simplified representations of pelagic food webs. These food webs do not necessarily include critical pathways by which ecosystems interact with ocean biogeochemistry and climate. Here we present a global biogeochemical model which incorporates ecosystem dynamics based on the representation of ten plankton functional types (PFTs): six types of phytoplankton, three types of zooplankton, and heterotrophic procaryotes. We improved the representation of zooplankton dynamics in our model through (a) the explicit inclusion of large, slow-growing macrozooplankton (e.g. krill), and (b) the introduction of trophic cascades among the three zooplankton types. We use the model to quantitatively assess the relative roles of iron vs. grazing in determining phytoplankton biomass in the Southern Ocean high-nutrient low-chlorophyll (HNLC) region during summer. When model simulations do not include macrozooplankton grazing explicitly, they systematically overestimate Southern Ocean chlorophyll biomass during the summer, even when there is no iron deposition from dust. When model simulations include a slow-growing macrozooplankton and trophic cascades among three zooplankton types, the high-chlorophyll summer bias in the Southern Ocean HNLC region largely disappears. Our model results suggest that the observed low phytoplankton biomass in the Southern Ocean during summer is primarily explained by the dynamics of the Southern Ocean zooplankton community, despite iron limitation of phytoplankton community growth rates. This result has implications for the representation of global biogeochemical cycles in models as zooplankton faecal pellets sink rapidly and partly control the carbon export to the intermediate and deep ocean.

  19. Phytoplankton distribution in the Western Arctic Ocean during a summer of exceptional ice retreat

    Science.gov (United States)

    Coupel, P.; Jin, H. Y.; Ruiz-Pino, D.; Chen, J. F.; Lee, S. H.; Li, H. L.; Rafizadeh, M.; Garçon, V.; Gascard, J. C.

    2011-07-01

    A drastic ice decline in the Arctic Ocean, triggered by global warming, could generate rapid changes in the upper ocean layers. The ice retreat is particularly intense over the Canadian Basin where large ice free areas were observed since 2007. The CHINARE 2008 expedition was conducted in the Western Arctic (WA) ocean during a year of exceptional ice retreat (August-September 2008). This study investigates whether a significant reorganization of the primary producers in terms of species, biomass and productivity has to be observed in the WA as a result of the intense ice melting. Both pigments (HPLC) and taxonomy (microscopy) acquired in 2008 allowed to determine the phytoplanktonic distribution from Bering Strait (65° N) to extreme high latitudes over the Alpha Ridge (86° N) encompassing the Chukchi shelf, the Chukchi Borderland and the Canadian Basin. Two different types of phytoplankton communities were observed. Over the ice-free Chukchi shelf, relatively high chl-a concentrations (1-5 mg m-3) dominated by 80 % of diatoms. In the Canadian Basin, surface waters are oligotrophic (poverty (Canadian Basin) and the richness (Chukchi shelf) of the WA, we explore the role of the nutrient-rich Pacific Waters, the bathymetry and two characteristics linked to the intense ice retreat: the stratification and the Surface Freshwater Layer (SFL). The freshwater accumulation induced a strong stratification limiting the nutrient input from the subsurface Pacific waters. This results in a biomass impoverishment of the well-lit layer and compels the phytoplankton to grow in subsurface. The phytoplankton distribution in the Chukchi Borderland and north Canadian Basin, during the summer of exceptional ice retreat (2008), suggested when compared to in-situ data from a more ice covered year (1994), recent changes with a decrease of the phytoplankton abundance while averaged biomass was similar. The 2008 obtained phytoplankton data in the WA provided a state of the ecosystem which

  20. Latitudinal phytoplankton distribution and the neutral theory of biodiversity

    KAUST Repository

    Chust, Guillem

    2012-11-16

    Recent studies have suggested that global diatom distributions are not limited by dispersal, in the case of both extant species and fossil species, but rather that environmental filtering explains their spatial patterns. Hubbell\\'s neutral theory of biodiversity provides a framework in which to test these alternatives. Our aim is to test whether the structure of marine phytoplankton (diatoms, dinoflagellates and coccolithophores) assemblages across the Atlantic agrees with neutral theory predictions. We asked: (1) whether intersite variance in phytoplankton diversity is explained predominantly by dispersal limitation or by environmental conditions; and (2) whether species abundance distributions are consistent with those expected by the neutral model. Location: Meridional transect of the Atlantic (50° N-50° S). Methods: We estimated the relative contributions of environmental factors and geographic distance to phytoplankton composition using similarity matrices, Mantel tests and variation partitioning of the species composition based upon canonical ordination methods. We compared the species abundance distribution of phytoplankton with the neutral model using Etienne\\'s maximum-likelihood inference method. Results: Phytoplankton communities are slightly more determined by niche segregation (24%), than by dispersal limitation and ecological drift (17%). In 60% of communities, the assumption of neutrality in species\\' abundance distributions could not be rejected. In tropical zones, where oceanic gyres enclose large stable water masses, most communities showed low species immigration rates; in contrast, we infer that communities in temperate areas, out of oligotrophic gyres, have higher rates of species immigration. Conclusions: Phytoplankton community structure is consistent with partial niche assembly and partial dispersal and drift assembly (neutral processes). The role of dispersal limitation is almost as important as habitat filtering, a fact that has been

  1. Changes in soil bacterial community structure with increasing disturbance frequency.

    Science.gov (United States)

    Kim, Mincheol; Heo, Eunjung; Kang, Hojeong; Adams, Jonathan

    2013-07-01

    Little is known of the responsiveness of soil bacterial community structure to disturbance. In this study, we subjected a soil microcosm to physical disturbance, sterilizing 90 % of the soil volume each time, at a range of frequencies. We analysed the bacterial community structure using 454 pyrosequencing of the 16S rRNA gene. Bacterial diversity was found to decline with the increasing disturbance frequencies. Total bacterial abundance was, however, higher at intermediate and high disturbance frequencies, compared to low and no-disturbance treatments. Changing disturbance frequency also led to changes in community composition, with changes in overall species composition and some groups becoming abundant at the expense of others. Some phylogenetic groups were found to be relatively more disturbance-sensitive or tolerant than others. With increasing disturbance frequency, phylogenetic species variability (an index of community composition) itself became more variable from one sample to another, suggesting a greater role of chance in community composition. Compared to the tightly clustered community of the original undisturbed soil, in all the aged disturbed soils the lists of most abundant operational taxonomic units (OTUs) in each replicate were very different, suggesting a possible role of stochasticity in resource colonization and exploitation in the aged and disturbed soils. For example, colonization may be affected by whichever localized concentrations of bacterial populations happen to survive the last disturbance and be reincorporated in abundance into each pot. Overall, it appears that the soil bacterial community is very sensitive to physical disturbance, losing diversity, and that certain groups have identifiable 'high disturbance' vs. 'low disturbance' niches.

  2. Monsoon-induced changes in the size-fractionated phytoplankton biomass and production rate in the estuarine and coastal waters of southwest coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Madhu, N; Jyothibabu, R; Balachandran, K.K.

    phytoplankton populations, in various water masses in the Gulf of Maine. Biol. Oceanogr. 3: 223-248. Jyothibabu, R., Madhu, N. V., Jayalakshmi, K.V., Balachandran, K.K., Shiyas, C.A., Martin, G.D & Nair, K.K.C. (2006). Impact of fresh water influx.... In: Berger, W.H., Smetacek, V.S., Wefer, G._Eds.., Productivity of the Ocean: Present and Past, Dahlem Konferenzen Wiley, Chichester. Madhu. N.V., Jyothibabu, R., Balachandran, K.K., Honey, U.K., Martin, G.D., Vijay, J. G., Shiyas, C. A., Gupta, G...

  3. Seasonal variability of the phytoplankton community of a lateral channel (Cortado of the Upper Paraná River Dinâmica sazonal da comunidade fitoplanctônica de um canal lateral (Canal Cortado do Alto Rio Paraná (PR, Brasil

    Directory of Open Access Journals (Sweden)

    Márcia Divina de Oliveira

    2000-05-01

    Full Text Available The seasonal variability of the phytoplanktonic community was studied in one lateral channel of the Upper Paraná River. The extensive samplings (monthly were taken in three stations in the Cortado Channel (22º47‘30”S, 53º24‘37”W from March of 1993 to February of 1994. Temporal changes in taxonomic composition, density, biomass, diversity and dominance were analyzed in relation to regional climate and hydrology, and to the physical and chemical factors of the water column. The phytoplanktonic community was composed of 95 taxa. The classes Cyanophyceae (Anabaena circinalis and Bacillariophyceae (Aulacoseira granulata were the most abundant, being responsible for the biomass peaks that occurred. The temporal variation in density and biomass did not show a clear seasonality, however, the highest biomass occurred in the late low waters (limnophase, with dominance of microplankton. Nanoplanktonic species, C-strategists common in Paraná River, mainly Cryptomonas brasiliensis, were abundant throughout the study periodFoi estudada a variabilidade sazonal da comunidade fitoplanctônica de um canal lateral do Alto Rio Paraná. As amostragens extensivas (mensais foram efetuadas em três estações no canal Cortado (22º47‘30”S, 53º24‘37”W no período de março de 1993 a fevereiro de 1994. As flutuações temporais na composição taxonômica, densidade, biomassa, diversidade e dominância foram analisadas em relação aos fatores climáticos e hidrológicos regionais e aos fatores físicos e químicos da água. A comunidade fitoplanctônica esteve representada por 95 táxons. As classes Cyanophyceae (Anabaena circinalis e Bacillariophyceae (Aulacoseira granulata foram as mais abundantes, sendo responsáveis pelos picos de biomassa registrados. As variações temporais na densidade, diversidade e biomassa não apresentaram conspícua sazonalidade. A máxima biomassa, entretanto, ocorreu ao término do período de águas baixas (limnofase

  4. Performing Environmental Change: MED Theatre and the Changing Face of Community-Based Performance Research

    Science.gov (United States)

    Schaefer, Kerrie

    2012-01-01

    This article examines a programme of work produced by community-based theatre company, Manaton and East Dartmoor (MED) Theatre, addressing issues of climate change as they impact on life in rural Devon, UK. After some discussion of MED Theatre's constitution as a community-based company and the group's long-term engagement with the place, history,…

  5. Collaboration and Community Change in the Children's Futures Initiative

    Science.gov (United States)

    Walker, Karen E.; Feldman, Amy

    2009-01-01

    In 2002, The Robert Wood Johnson Foundation launched Children's Futures (CF), a 10-year community change initiative designed to improve the health and well-being of children from birth to age three throughout Trenton, New Jersey. CF's strategies included efforts to increase residents' access to prenatal and other health services, provide parenting…

  6. Empowerment and Health: The Theory and Practice of Community Change.

    Science.gov (United States)

    Wallerstein, Nina

    1993-01-01

    Empowerment as social action addresses lack of control by enhancing participation in community action. An alcohol and substance abuse prevention program for New Mexico adolescents used Freire's problem posing and critical thinking philosophy and methods to empower young people to change their health behavior. (SK)

  7. A Decade of Complete Change in a Muslim Community

    Institute of Scientific and Technical Information of China (English)

    CAI YI

    2007-01-01

    @@ Talking about changes in the Muslim-inhabited Niu Jie Street of Beijing, every member of the community would be all smiles. "Everything has changed; the mosque, the streetscape and the people, too" they would say. Niu Jie or Ox Street is situated in the Xuanwu District in the southern part of Beijing. The 1.44 square kilometer area is inhabited by 54,000 people, mostly of Muslims.

  8. Short- and Long-Term Response of Phytoplankton to ENSO in Prydz Bay, Antarctica:Evidences from Field Measurements, Remote Sensing Data and Stratigraphic Biomarker Records

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jun; Hans-Ulrich Peter; ZHANG Haisheng; HAN Zhengbing; HU Chuanyu; YU Peisong; LU Bing; Thomas S.Bianchi

    2014-01-01

    The study provides one of the first lines of evidence showing linkages between Antarctic phytoplankton abundance and composition in response to ENSO, based on historical reconstruction of sediment biomarkers. In addition to sediment biomarkers, field measured and remote sensing data of phytoplankton abundance were also recorded from Prydz Bay, Eastern Antarctica. Com-munity structure of field measured phytoplankton showed significant El Niño/La Niña-related succession during 1990 to 2002. In general, the number of algae species decreased during El Niño and La Niña years compared to normal years. Austral summer monthly variation of remotely sensed chlorophyll-a (Chl-a), particulate organic carbon (POC), and sea surface temperature (SST) indicated that ENSO impacted the timing of phytoplankton blooms during 2007 to 2011. Phytoplankton blooms (indicated by Chl-a and POC) preceded the increases in SST during El Niño years, and lagged behind the SST increases during La Niña years. Stratigraphic record of marine sedimentary lipid (brassicasterol, dinosterol and alkenones) biomarkers inferred that the proportions of different algae (diatoms, dinoflagellates and haptophytes) changed significantly between El Niño and La Niña events. The relative proportion of diatoms increased, with that of dinoflagellates being decreased during El Niño years, while it was reversed during La Niña years.

  9. Forcing of dissolved organic carbon release by phytoplankton by anticyclonic mesoscale eddies in the subtropical NE Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    S. Lasternas

    2013-03-01

    Full Text Available The organic carbon fluxes mediated by planktonic communities in two cyclonic eddies (CEs and two anticyclonic eddies (AEs at the Canary Eddy Corridor were studied and compared with the dynamics in two far-field (FF stations located outside the eddies. We observed favorable conditions and signs for upwelling at the center of CEs and for downwelling and mixing at the centers of AEs. CEs were characterized by a higher concentration of nutrients and the highest concentration of chlorophyll a (chl a, associated with the highest abundance of microphytoplankton and diatoms. AEs displayed concentrations of chl a values and nutrients similar to those at the FF stations, except for the highest ammonium concentration occurring at AE and a very low concentration of phosphorus at FF stations. AEs were transient systems characterized by an increasing abundance of picophytoplankton and heterotrophic bacteria. While primary production was similar between the systems, the production of dissolved organic carbon (PDOC was significantly higher in the AEs. Phytoplankton cell mortality was lowest in the CEs, and we found higher cell mortality rates at AE than at FF stations, despite similar chl a concentration. Environmental changes in the AEs have been significantly prejudicial to phytoplankton as indicated by higher phytoplankton cell mortality (60% of diatoms cells were dead and higher cell lysis rates. The adverse conditions for phytoplankton associated with the early-stage anticyclonic systems, mainly triggered by active downwelling, resulted in higher cell mortality, forcing photosynthesized carbon to fuel the dissolved pool.

  10. 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

  11. Contrasting patterns of free-living bacterioplankton diversity in macrophyte-dominated versus phytoplankton blooming regimes in Dianchi Lake, a shallow lake in China

    Science.gov (United States)

    Wang, Yujing; Li, Huabing; Xing, Peng; Wu, Qinglong

    2016-04-01

    Freshwater shallow lakes typically exhibit two alternative stable states under certain nutrient loadings: macrophyte-dominated and phytoplankton-dominated water regimes. An ecosystem regime shift from macrophytes to phytoplankton blooming typically reduces the number of species of invertebrates and fishes and results in the homogenization of communities in freshwater lakes. We investigated how microbial biodiversity has responded to a shift of the ecosystem regime in Dianchi Lake, which was previously fully covered with submerged macrophytes but currently harbors both ecological states. We observed marked divergence in the diversity and community composition of bacterioplankton between the two regimes. Although species richness, estimated as the number of operational taxonomic units and phylogenetic diversity (PD), was higher in the phytoplankton dominated ecosystem after this shift, the dissimilarity of bacterioplankton community across space decreased. This decrease in beta diversity was accompanied by loss of planktonic bacteria unique to the macrophyte-dominated ecosystem. Mantel tests between bacterioplankton community distances and Euclidian distance of environmental parameters indicated that this reduced bacterial community diff erentiation primarily reflected the loss of environmental niches, particularly in the macrophyte regime. The loss of this small-scale heterogeneity in bacterial communities should be considered when assessing long-term biodiversity changes in response to ecosystem regime conversions in freshwater lakes.

  12. 山西宁武亚高山湖群浮游植物群落结构特征%Characteristics of phytoplankton community structures in Ningwu subalpine lakes, Shanxi Province

    Institute of Scientific and Technical Information of China (English)

    张俊芳; 冯佳; 谢树莲; 王石会

    2012-01-01

    通过对山西宁武亚高山湖群浮游植物群落结构的调查研究,共鉴定出浮游植物291个种、变种及变型,隶属于8门,45科,108属.各采样站点间种数相差较大,以马营海种类最多,干海最少.硅藻门、绿藻门和蓝藻门明显占优势,优势科、优势属和优势种也都较为明显.优势种有蓝藻门的细小隐球藻(Aphanocapsa elachista)、铜绿微囊藻(Microcystis aeruginisa)和小席藻(Phormidium tenue),硅藻门的库津小环藻(Cyclotella kuetzingii)、肘状脆杆藻(Fragilaria ulna)、尖针杆藻(Synedra acus),绿藻门的狭形纤维藻(Ankistrodesmus angustus)和小球藻(Chlorella vulgaris).浮游植物平均密度为3.49 × 106cells/L.水面下0.5m处比水表层的细胞密度高.综合4种生物多样性指数,宁武亚高山湖群水质总体为轻污染.%The phytoplankton community structures in Ningwu subalpine lakes have been studied and 291 taxa, belonging to 8 divisions, 45 families and 108 genera, have been identified. The species numbers of each sampling station are quite different. The most abundant species are occurred in Lake Mayinghai, and the least in Lake Ganhai. Bacillariophyta, Chlorophyta and Cyanophy-ta dominate the area, in addition, dominant families, dominant genera and dominant species are also relatively clear. There are 8 dominant species and they are Aphanocapsa elachista, Micrvcystis aeruginosa, Phormidium tenue, Cyclotella kuelxingii, Fragilaria ulna, Synedra acus, Ankistrodesmus angustus and Chlorella vulgaris. The average phytoplankton cell density is 3.49 x 106cells/L in the lakes. The cell density in 0.5 m depth was higher than that on the surface. The initially assessment by four biodiversity indexes is that the water quality in Ningwu subalpine lakes is light-polluted.

  13. Structure and Dynamics of Phytoplankton Community in the Rivers of Jiangyin City%江阴地区主要河道浮游藻类群落特征

    Institute of Scientific and Technical Information of China (English)

    宋晓兰; 吕伟民; 卞金良; 张洁; 黄振荣; 郑科; 奚海明

    2013-01-01

    Phytoplankton assemblages were sampled in September, 2010, November, April and July, 2011 in main rivers of Jiangyin city of Taihu basin. 141 species / genera belonging to 7 phyla were identified. The results indicated higher species richness and standing crop of phytoplankton during summer and autumn than during winter and spring. The dominant algal group during winter and spring were centric diatom (Cyclotella meneghini-ana, Aulacoseira granulata) , Cryptophyta (Cryptomonas erosa) , Euglenophyta (Euglena spp. ) and Chlorophy-ta ( Chlamydomonas spp. and Oocystis spp. ). The community during summer and autumn was dominated by Cya-nobacteria (Oscillatoria princes, Planktothrix agardhii) and diatom (C. meneghiniana). The seasonal variation among north-south rivers (Xicheng river, Baiqugang river and Zhangjiagang river) was much severer than that a-mong east-west rivers (Yingtian river, Xiheng river and Dongheng river). It indicated that main rivers were in a, (3 - type moderate pollution by saprobic indicator.%2010年9月和2011年1月、4月、7月共4次对江阴6条主要河道的浮游藻类群落特征开展调查分析.共发现浮游藻类7门141属种,种类丰富度和现存量夏秋季高于秋冬季.优势种属呈季节性演替,即冬季梅尼小环藻(Cyclotella meneghiniana)、颗粒直链硅藻(Aulacoseira granulata)-春季梅尼小环藻、啮蚀隐藻(Cryptomonas erosa)、裸藻属(Euglena spp.)、衣藻属(Chlamydomonas spp.)、卵囊藻属(Oocystis spp.)-夏季巨颤藻(Oscillatoria princeps)、阿氏浮丝藻(Planktothrix agardhii)-秋季巨颤藻、阿氏浮丝藻、梅尼小环藻.南北向河道(锡澄运河、白屈港河和张家港河)的浮游藻类季节波动性大于东西向河道(应天河、东横河和西横河).通过指示生物法,调查河道处于α,β-中污染状态.

  14. Risk associated with toxic blooms of marine phytoplankton functional groups on Artemia franciscana

    Institute of Scientific and Technical Information of China (English)

    Ana Dors; Mara Carmen Bartolom; Sebastin Snchez-Fortn

    2014-01-01

    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.

  15. Large-scale shifts in phytoplankton groups in the Equatorial Pacific during ENSO cycles

    Directory of Open Access Journals (Sweden)

    I. Masotti

    2010-04-01

    Full Text Available The El Niño Southern Oscillation (ENSO drives important changes in the marine productivity of the Equatorial Pacific, in particular during major El Niño/La Niña transitions. Changes in environmental conditions associated with these climatic events also likely impact phytoplankton composition. In this work, the distribution of four major phytoplankton groups (nanoeucaryotes, Prochlorococcus, Synechococcus, and diatoms was examined between 1996 and 2007 by applying the PHYSAT algorithm to the ocean color data archive from the Ocean Color and Temperature Sensor (OCTS and Sea-viewing Wide Field-of-view Sensor (SeaWiFS. Coincident with the decrease in chlorophyll concentrations, a large-scale shift in the phytoplankton composition of the Equatorial Pacific, that was characterized by a decrease in Synechococcus and an increase in nanoeucaryotes dominance, was observed during the early stages of both the strong El Niño of 1997 and the moderate El Niño of 2006. A significant increase in diatoms dominance was observed in the Equatorial Pacific during the 1998 La Niña and was associated with elevated marine productivity. An analysis of the environmental variables using a coupled physical-biogeochemical model (NEMO-PISCES suggests that the Synechococcus dominance decrease during the two El Niño events was associated with an abrupt decline in nutrient availability (−0.9 to −2.5 μM NO3 month−1. Alternatively, increased nutrient availability (3 μM NO3 month−1 during the 1998 La Niña resulted in Equatorial Pacific dominance diatom increase. Despite these phytoplankton community shifts, the mean composition is restored after a few months, which suggests resilience in community structure. Such rapid changes to the composition of phytoplankton groups should be considered in future modeling approaches to represent variability of the marine productivity in the Equatorial Pacific and to quantify its

  16. 新疆阿克达拉水库浮游植物群落生态特征%Ecological characteristics of phytoplankton community of Akedala Reservoir in Xinjiang

    Institute of Scientific and Technical Information of China (English)

    吴惠仙; 王琼; 蔡桢; 朱新英; 李周永; 薛俊增

    2011-01-01

    Akedala Reservoir locates in Altay Prefecture, Xinjiang. The water of the reservoir is supplemented from Ulungur River and Ulungur Lake. The reservoir is an important water resource for fishers. Phytoplankton community structure was investigated and analyzed to explain the ecological characters of Akedala Reservoir in July 2008, October 2008 and May 2009. A total of 101 phytoplankton species, belonging to 8 phylums was identified. There are 40 species of diatom, 38 species of green algae, 7 species of blue green algae, 6 species of euglenids, 4 species of yellow green algae, 3 species of chrysophyceae, 2 species of cryptomonads, 1 species of fire algae. Green algae and diatoms are dominance in the species composition. Phytoplankton species composition in different periods shows significant differences(P<0.01): the wet season's(57 species) > the normal-water season's(42 species) > the dry season's(31 species). Anabaena oscillarioides, Scenedesmus quadricauda, Ankistrodemus angustus, Ankistrodesmus acicularis, Chlorella vulgaris as well as Tribonema. Sp are the dominant species. Cell density for different categories of phytoplankton is significantly difference (P < 0. 01): Xanthophyta has the largest cell density, followed by Cyanophyta and Chlorophyta. The cell density in different periods is also significant difference (F =49. 58, P<0.001): the normal-water season's[ (7. 89 ±1.48) ×106ind/L] > the wet season's( (5.17 ±0. 59) × 106 ind/L] > the dry season's[ (0.49 ±0.09)× 106 ind/L]. Moreover.the phytoplankton composition, cell density and diversity are closely related to the water temperature and the water level of Akedala Reservoir.%为了解其水生生物生态现状,于2008年7月(平水期)、10月(枯水期)和次年5月(丰水期)对阿克达拉水库内浮游植物群落生态特征进行了研究.共采集到浮游植物8门101种,其中硅藻40种、绿藻38种、蓝藻7种、裸藻6种、黄藻4种、金藻3种、隐藻2种和甲藻1

  17. Phytoplankton assemblage of a solar saltern in Port Fouad, Egypt

    Directory of Open Access Journals (Sweden)

    Fedekar Fadel Madkour

    2012-11-01

    Full Text Available The present study is the first investigation of the phytoplankton community inone of Egypt's saltworks. The phytoplankton composition and distribution infive ponds of increasing salinity were investigated in the solar saltern of Port Fouad.The phytoplankton community consisted of 42 species belonging to cyanobacteria(16, diatoms (12, dinoflagellates (11, Euglenophyceae (2 and Chlorophyceae (1.The number of species decreased significantly and rapidly with increasing salinity,varying between 33 species in the first pond (P1 and one species in the crystallizerpond (P5. Conversely, the total phytoplankton density, except that recordedin P1, increased significantly with rising salinity, fluctuating between 8.7 and56 × 105 individuals l-1 in P2 and P5 respectively. In spiteof the local variations in climate and nutrient availability, the phytoplankton composition, density and spatialvariations along the salinity gradient were, in many respects, very similar towhat has been observed in other solar saltworks. The pond with the lowest salinity(P1 - -1 was characterized by a significant diversity andblooming of diatoms and dinoflagellates. Intermediate salinity ponds (P2 andP3 with salinity ∼ 112-180 g l-1 exhibited a decline in bothspecies richness and density, but the stenohaline blue green algae (Synechocystis salina did flourish. The highly saline concentrating ponds andcrystallizers (P4 and P5 with salinity ∼ 223-340 g l-1 werecharacterized by few species, the disappearance of blue green algae and thethriving of the halotolerant green alga Dunaliella salina.

  18. Phytoplankton distribution in the Western Arctic Ocean during a summer of exceptional ice retreat

    Directory of Open Access Journals (Sweden)

    P. Coupel

    2011-07-01

    Full Text Available A drastic ice decline in the Arctic Ocean, triggered by global warming, could generate rapid changes in the upper ocean layers. The ice retreat is particularly intense over the Canadian Basin where large ice free areas were observed since 2007. The CHINARE 2008 expedition was conducted in the Western Arctic (WA ocean during a year of exceptional ice retreat (August–September 2008. This study investigates whether a significant reorganization of the primary producers in terms of species, biomass and productivity has to be observed in the WA as a result of the intense ice melting. Both pigments (HPLC and taxonomy (microscopy acquired in 2008 allowed to determine the phytoplanktonic distribution from Bering Strait (65° N to extreme high latitudes over the Alpha Ridge (86° N encompassing the Chukchi shelf, the Chukchi Borderland and the Canadian Basin.

    Two different types of phytoplankton communities were observed. Over the ice-free Chukchi shelf, relatively high chl-a concentrations (1–5 mg m−3 dominated by 80 % of diatoms. In the Canadian Basin, surface waters are oligotrophic (<0.1 mg m−3 and algal assemblages were dominated by haptophytes and diatoms while higher biomasses (~0.4 mg m−3 related to a deep Subsurface Chlorophyll Maximum (SCM are associated to small-sized (nano and pico phytoplankton. The ice melting onset allows to point out three different zones over the open basin: (i the ice free condition characterized by deep and unproductive phytoplankton communities dominated by nanoplankton, (ii an extended (78°–83° N Active Melting Zone (AMZ where light penetration associated to the stratification start off and enough nutrient availability drives to the highest biomass and primary production due to both diatoms and large flagellates, (iii heavy ice conditions found north to 83° N allowing light limitation and consequently low biomass and primary production associated to pico

  19. Phytoplankton diversity and productivity in a highly turbid, tropical coastal system (Bach Dang Estuary, Vietnam)

    Science.gov (United States)

    Rochelle-Newall, E. J.; Chu, V. T.; Pringault, O.; Amouroux, D.; Arfi, R.; Bettarel, Y.; Bouvier, T.; Bouvier, C.; Got, P.; Nguyen, T. M. H.; Mari, X.; Navarro, P.; Duong, T. N.; Cao, T. T. T.; Pham, T. T.; Ouillon, S.; Torréton, J.-P.

    2011-01-01

    The factors controlling estuarine phytoplankton diversity and production are relatively well known in temperate systems. Less however is known about the factors affecting phytoplankton community distribution in tropical estuaries. This is surprising given the economic and ecological importance of these large, deltaic ecosystems, such as are found in South East Asia. Here we present the results from an investigation into the factors controlling phytoplankton distribution and phytoplankton-bacterial coupling in the Bach Dang Estuary, a sub-estuary of the Red River system, in Northern Vietnam. Phytoplankton diversity and primary and bacterial production, nutrients and metallic contaminants (mercury and organotin) were measured during two seasons: wet (July 2008) and dry (March 2009). Phytoplankton community composition differed between the two seasons with only a 2% similarity between July and March. The large spatial extent and complexity of defining the freshwater sources meant that simple mixing diagrams could not be used in this system. We therefore employed multivariate analyses to determine the factors influencing phytoplankton community structure. Salinity and suspended particulate matter were important factors in determining phytoplankton distribution, particularly during the wet season. We also show that phytoplankton community structure is probably influenced by the concentrations of mercury species (inorganic mercury and methyl mercury in both the particulate and dissolved phases) and of tri-, di, and mono-butyl tin species found in this system. Freshwater phytoplankton community composition was associated with dissolved methyl mercury and particulate inorganic mercury concentrations during the wet season, whereas, during the dry season, dissolved methyl mercury and particulate butyl tin species were important factors for the discrimination of the phytoplankton community structure. Phytoplankton-bacterioplankton coupling was also investigated during both

  20. Phytoplankton diversity and productivity in a highly turbid, tropical coastal system (Bach Dang Estuary, Vietnam

    Directory of Open Access Journals (Sweden)

    E. J. Rochelle-Newall

    2011-01-01

    Full Text Available The factors controlling estuarine phytoplankton diversity and production are relatively well known in temperate systems. Less however is known about the factors affecting phytoplankton community distribution in tropical estuaries. This is surprising given the economic and ecological importance of these large, deltaic ecosystems, such as are found in South East Asia. Here we present the results from an investigation into the factors controlling phytoplankton distribution and phytoplankton-bacterial coupling in the Bach Dang Estuary, a sub-estuary of the Red River system, in Northern Vietnam. Phytoplankton diversity and primary and bacterial production, nutrients and metallic contaminants (mercury and organotin were measured during two seasons: wet (July 2008 and dry (March 2009. Phytoplankton community composition differed between the two seasons with only a 2% similarity between July and March. The large spatial extent and complexity of defining the freshwater sources meant that simple mixing diagrams could not be used in this system. We therefore employed multivariate analyses to determine the factors influencing phytoplankton community structure. Salinity and suspended particulate matter were important factors in determining phytoplankton distribution, particularly during the wet season. We also show that phytoplankton community structure is probably influenced by the concentrations of mercury species (inorganic mercury and methyl mercury in both the particulate and dissolved phases and of tri-, di, and mono-butyl tin species found in this system. Freshwater phytoplankton community composition was associated with dissolved methyl mercury and particulate inorganic mercury concentrations during the wet season, whereas, during the dry season, dissolved methyl mercury and particulate butyl tin species were important factors for the discrimination of the phytoplankton community structure. Phytoplankton-bacterioplankton coupling was also

  1. Phytoplankton, bacterioplankton and virioplankton structure and function across the southern Great Barrier Reef shelf

    Science.gov (United States)

    Alongi, Daniel M.; Patten, Nicole L.; McKinnon, David; Köstner, Nicole; Bourne, David G.; Brinkman, Richard

    2015-02-01

    Bacterioplankton and phytoplankton dynamics, pelagic respiration, virioplankton abundance, and the diversity of pelagic diazotrophs and other bacteria were examined in relation to water-column nutrients and vertical mixing across the southern Great Barrier Reef (GBR) shelf where sharp inshore to offshore gradients in water chemistry and hydrology prevail. A principal component analysis (PCA) revealed station groups clustered geographically, suggesting across-shelf differences in plankton function and structure driven by changes in mixing intensity, sediment resuspension, and the relative contributions of terrestrial, reef and oceanic nutrients. At most stations and sampling periods, microbial abundance and activities peaked both inshore and at channels between outer shelf reefs of the Pompey Reef complex. PCA also revealed that virioplankton numbers and biomass correlated with bacterioplankton numbers and production, and that bacterial growth and respiration correlated with net primary production, suggesting close virus-bacteria-phytoplankton interactions; all plankton groups correlated with particulate C, N, and P. Strong vertical mixing facilitates tight coupling of pelagic and benthic shelf processes as, on average, 37% and 56% of N and P demands of phytoplankton are derived from benthic nutrient regeneration and resuspension. These across-shelf planktonic trends mirror those of the benthic microbial community.

  2. Seasonal variation in functional phytoplankton groups in Xiangxi Bay, Three Gorges Reservoir

    Institute of Scientific and Technical Information of China (English)

    YANG Min; BI Yonghong; HU Jianlin; ZHU Kongxian; ZHOU Guangjie; HU Zhengyu

    2011-01-01

    We describe the phytoplankton dynamics and structure in Xiangxi Bay,Three Gorges Reservoir.Samples were collected monthly in the surface waters between August 2007 and July 2008.We identified 10 principle functional groups.C-strategists and S/R-strategists with a wide range of tolerance dominated the phytoplankton assemblage.Seasonal variation was related to water column stability because of changes in hydraulic operation in October,January,and May.Functional group C (Asterionellaformosa)and P (Aulacoseria granulata) dominated in August and September,whereas group Lo (Peridiniopsis niei)was the most abundant between February and April,forming a dinoflagellate bloom.Group B (Stephanodiscus hantzschii),X2 (Komma acudata),and Y ( Cryptomonas erosa) were present throughout most of the year but were most abundant in late spring.A cyanobacterial bloom occurred from June to July,during which group M ( Microcystis aeruginosa,M.wesenbergii) and H1 (Anabaena flos-aquae) were dominant.Green algae,characterized by group G (Eudorina sp.,Pandorina sp.,Pyramidomonas sp.) and J (Pediastrum spp.,Coelastrum spp.,Scenedesums spp.),were abundant after the bloom degraded.This sequence was corroborated by canonical correspondence analysis (CCA).The summary sequence of functional groups resulting from CCA was:C/P→ Lo→H1/M/J/G.The dynamics of the phytoplankton community may be explained by the stability of water column,irradiance,water temperature,and nutrient structure.

  3. Size change, shape change, and the growth space of a community

    OpenAIRE

    Spencer, Matthew

    2014-01-01

    Measures of biodiversity change such as the Living Planet Index describe proportional change in the abundance of a typical species, which can be thought of as change in the size of a community. Here, I discuss the orthogonal concept of change in relative abundances, which I refer to as shape change. To be logically consistent, a measure of the rate of shape change should be scaling invariant (have the same value for all data with the same vector of proportional change over a given time interv...

  4. Population dynamics and diversity of viruses, bacteria and phytoplankton in a shallow eutrophic lake.

    Science.gov (United States)

    Tijdens, Marjolijn; Hoogveld, Hans L; Kamst-van Agterveld, Miranda P; Simis, Stefan G H; Baudoux, Anne-Claire; Laanbroek, Hendrikus J; Gons, Herman J

    2008-07-01

    of the viruses in Lake Loosdrecht may be phytoplankton and more specific cyanobacterial viruses. Temporal changes in bacterial abundances were significantly related to viral community assemblage, and vice versa, suggesting an interaction between viral and bacterial communities in Lake Loosdrecht.

  5. Creating a Learning Community for Solutions to Climate Change

    Science.gov (United States)

    Bloom, A. J.; Benedict, B. A.; Blockstein, D. E.; Hassenzahl, D. M.; Hunter, A.; Jorgensen, A. D.; Pfirman, S. L.

    2011-12-01

    The rapidly evolving and interdisciplinary nature of climate change presents a challenge to colleges and universities as they seek to educate undergraduate students. To address this challenge, the National Council for Science and the Environment (NCSE) with NSF funding is creating a nationwide cyber-enabled learning community called CAMEL (Climate, Adaptation, and Mitigation e-Learning). CAMEL engages experts in science, policy and decision-making, education, and assessment in the production of a virtual toolbox of curricular resources designed for teaching climate change causes, consequences, and solutions. CAMEL is: ? Developing cyberinfrastructure that supports and promotes the creation of materials and community; ? Generating materials for the Encyclopedia of Earth, a site averaging 50,000 views per day; ? Ensuring that materials developed and shared are founded on the best available scientific information and follow the most appropriate educational practices; ? Assisting faculty at institutions of higher education across the United States as they create, improve, test, and share resources for teaching students not only how to diagnose climate change problems, but also to identify and effect solutions; ? Evaluating the determinants of successful community building using cybermedia. The community and resultant content range from general education to upper division courses for students in a variety of majors. At the center of the community are the 160 colleges and universities represented in NCSE's Council of Environmental Deans and Directors. Members of this group represent recognized expertise in virtually all areas of this project. A team with substantial experience with evaluating innovative initiatives in STEM education is administering the evaluation component.

  6. Life in an extreme environment: phytoplankton blooms in the upper Scheldt estuary

    OpenAIRE

    Muylaert, K.; Kromkamp, J.

    2002-01-01

    Being extremely turbid environments characterised by short residence times and rapid changes in salinity, the upper reaches of estuaries comprise an extreme environment for phytoplankton to live and grow in. Nevertheless, in many estuaries including the Schelde estuary, these reaches often support dense phytoplankton populations. In the past, these phytoplankton blooms in the upper reaches of estuaries have often been found difficult to explain. In this presentation, we will describe the exte...

  7. 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...

  8. 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 i

  9. Iron from melting glaciers fuels phytoplankton blooms in the Amundsen Sea (Southern Ocean) : Phytoplankton characteristics and productivity

    NARCIS (Netherlands)

    Alderkamp, Anne-Carlijn; Mills, Matthew M.; van Dijken, Gert L.; Laan, Patrick; Thuroczy, Charles-Edouard; Gerringa, Loes J. A.; de Baar, Hein J. W.; Payne, Christopher D.; Visser, Ronald J. W.; Buma, Anita G. J.; Arrigo, Kevin 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 i

  10. Distribution of phytoplankton in a lowland river, Germany, in relation to environmental factors

    OpenAIRE

    Wu, Naicheng; Schmalz, Britta; Fohrer, Nicola

    2010-01-01

    Abstract In comparison to lentic systems, the species composition and community structure of phytoplankton in lotic habitats are still poorly understood. We investigated the spatial and temporal dynamics of phytoplankton community in a German lowland river- the Kielstau catchment, and the relationships with environmental variables. Among the 125 taxa observed, Desmodesmus communis, Pediastrum duplex and Discostella steligera were dominant species at lentic sites while Tabellaria fl...

  11. Biodiversity decreases disease through predictable changes in host community competence.

    Science.gov (United States)

    Johnson, Pieter T J; Preston, Daniel L; Hoverman, Jason T; Richgels, Katherine L D

    2013-02-14

    Accelerating rates of species extinctions and disease emergence underscore the importance of understanding how changes in biodiversity affect disease outcomes. Over the past decade, a growing number of studies have reported negative correlations between host biodiversity and disease risk, prompting suggestions that biodiversity conservation could promote human and wildlife health. Yet the generality of the diversity-disease linkage remains conjectural, in part because empirical evidence of a relationship between host competence (the ability to maintain and transmit infections) and the order in which communities assemble has proven elusive. Here we integrate high-resolution field data with multi-scale experiments to show that host diversity inhibits transmission of the virulent pathogen Ribeiroia ondatrae and reduces amphibian disease as a result of consistent linkages among species richness, host composition and community competence. Surveys of 345 wetlands indicated that community composition changed nonrandomly with species richness, such that highly competent hosts dominated in species-poor assemblages whereas more resistant species became progressively more common in diverse assemblages. As a result, amphibian species richness strongly moderated pathogen transmission and disease pathology among 24,215 examined hosts, with a 78.4% decline in realized transmission in richer assemblages. Laboratory and mesocosm manipulations revealed an approximately 50% decrease in pathogen transmission and host pathology across a realistic diversity gradient while controlling for host density, helping to establish mechanisms underlying the diversity-disease relationship and their consequences for host fitness. By revealing a consistent link between species richness and community competence, these findings highlight the influence of biodiversity on infection risk and emphasize the benefit of a community-based approach to understanding infectious diseases.

  12. Exploration of relationships between phytoplankton biomass and related environmental variables using multivariate statistic analysis in a eutrophic shallow lake: A 5-year study

    NARCIS (Netherlands)

    Wang, X.L.; Lu, Y.L.; He, G.Z.; Han, Jingyi; Wang, T.Y.

    2007-01-01

    Understanding the process of the changing phytoplankton patterns can be particularly useful in water quality improvement and management decisions. However, it is generally not easy to illustrate the interactions between phytoplankton biomass and related environmental variables given their high spati

  13. Size change, shape change, and the growth space of a community.

    Science.gov (United States)

    Spencer, Matthew

    2015-03-21

    Measures of biodiversity change such as the Living Planet Index describe proportional change in the abundance of a typical species, which can be thought of as change in the size of a community. Here, I discuss the orthogonal concept of change in relative abundances, which I refer to as shape change. To be logically consistent, a measure of the rate of shape change should be scaling invariant (have the same value for all data with the same vector of proportional change over a given time interval), but existing measures do not have this property. I derive a new, scaling invariant measure. I show that this new measure and existing measures of biodiversity change such as the Living Planet Index describe different aspects of dynamics. I show that neither body size nor environmental variability need affect the rate of shape change. I extend the measure to deal with colonizations and extinctions, using the surreal number system. I give examples using data on hoverflies in a garden in Leicester, UK, and the higher plant community of Surtsey. I hypothesize that phylogenetically restricted assemblages will show a higher proportion of size change than diverse communities.

  14. Changing times, changing stories: generational differences in climate change perspectives from four remote indigenous communities in Subarctic Alaska

    Directory of Open Access Journals (Sweden)

    Nicole M. Herman-Mercer

    2016-09-01

    Full Text Available Indigenous Arctic and Subarctic communities currently are facing a myriad of social and environmental changes. In response to these changes, studies concerning indigenous knowledge (IK and climate change vulnerability, resiliency, and adaptation have increased dramatically in recent years. Risks to lives and livelihoods are often the focus of adaptation research; however, the cultural dimensions of climate change are equally important because cultural dimensions inform perceptions of risk. Furthermore, many Arctic and Subarctic IK climate change studies document observations of change and knowledge of the elders and older generations in a community, but few include the perspectives of the younger population. These observations by elders and older generations form a historical baseline record of weather and climate observations in these regions. However, many indigenous Arctic and Subarctic communities are composed of primarily younger residents. We focused on the differences in the cultural dimensions of climate change found between young adults and elders. We outlined the findings from interviews conducted in four indigenous communities in Subarctic Alaska. The findings revealed that (1 intergenerational observations of change were common among interview participants in all four communities, (2 older generations observed more overall change than younger generations interviewed by us, and (3 how change was perceived varied between generations. We defined "observations" as the specific examples of environmental and weather change that were described, whereas "perceptions" referred to the manner in which these observations of change were understood and contextualized by the interview participants. Understanding the differences in generational observations and perceptions of change are key issues in the development of climate change adaptation strategies.

  15. Changing times, changing stories: Generational differences in climate change perspectives from four remote indigenous communities in Subarctic Alaska

    Science.gov (United States)

    Herman-Mercer, Nicole M.; Matkin, Elli; Laituri, Melinda J.; Toohey, Ryan C; Massey, Maggie; Kelly Elder,; Schuster, Paul F.; Mutter, Edda A.

    2016-01-01

    Indigenous Arctic and Subarctic communities currently are facing a myriad of social and environmental changes. In response to these changes, studies concerning indigenous knowledge (IK) and climate change vulnerability, resiliency, and adaptation have increased dramatically in recent years. Risks to lives and livelihoods are often the focus of adaptation research; however, the cultural dimensions of climate change are equally important because cultural dimensions inform perceptions of risk. Furthermore, many Arctic and Subarctic IK climate change studies document observations of change and knowledge of the elders and older generations in a community, but few include the perspectives of the younger population. These observations by elders and older generations form a historical baseline record of weather and climate observations in these regions. However, many indigenous Arctic and Subarctic communities are composed of primarily younger residents. We focused on the differences in the cultural dimensions of climate change found between young adults and elders. We outlined the findings from interviews conducted in four indigenous communities in Subarctic Alaska. The findings revealed that (1) intergenerational observations of change were common among interview participants in all four communities, (2) older generations observed more overall change than younger generations interviewed by us, and (3) how change was perceived varied between generations. We defined “observations” as the specific examples of environmental and weather change that were described, whereas “perceptions” referred to the manner in which these observations of change were understood and contextualized by the interview participants. Understanding the differences in generational observations and perceptions of change are key issues in the development of climate change adaptation strategies.

  16. 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).

  17. Phytoplankton depth profiles and their transitions near the critical sinking velocity.

    Science.gov (United States)

    Kolokolnikov, Theodore; Ou, Chunhua; Yuan, Yuan

    2009-07-01

    We consider a simple phytoplankton model introduced by Shigesada and Okubo which incorporates the sinking and self-shading effect of the phytoplankton. The amount of light the phytoplankton receives is assumed to be controlled by the density of the phytoplankton population above the given depth. We show the existence of non-homogeneous solutions for any water depth and study their profiles and stability. Depending on the sinking rate of the phytoplankton, light intensity and water depth, the plankton can concentrate either near the surface, at the bottom of the water column, or both, resulting in a "double-peak" profile. As the buoyancy passes a certain critical threshold, a sudden change in the phytoplankton profile occurs. We quantify this transition using asymptotic techniques. In all cases we show that the profile is locally stable. This generalizes the results of Shigesada and Okubo where infinite depth was considered.

  18. Microbial community changes in heathland soil communities along a geographical gradient: Interaction with climate change manipulations

    DEFF Research Database (Denmark)

    Sowerby, A.; Emmett, B.; Beier, C.;

    2005-01-01

    Climate change constitutes a serious threat for European heathlands as unlike other sources of damage, such as over-grazing, local remediation is not a possibility. Within the large pan-European projects, CLIMOOR and VULCAN, the effect of periodic drought and increased temperature were investigated...

  19. Impact of wastewater on phytoplankton

    Digital Repository Service at National Institute of Oceanography (India)

    Jaiswar, M.J.R.

    A number of studies on phytoplankton were conducted by National Institute of Oceanography, Goa, India at Thane Creek, Maharashtra, India, Ulhas River estuary, Versova Creek and Mahim Creek under Coastal Ocean Monitoring and Prediction System (COMAPS...

  20. Phytoplankton growth and microzooplankton grazing dynamics across vertical environmental gradients determined by transplant in situ dilution experiments.

    Science.gov (United States)

    Gutiérrez-Rodríguez, Andrés; Selph, Karen E; Landry, Michael R

    2016-03-01

    The Costa Rica Dome (CRD) represents a classic case of the bloom-forming capacity of small phytoplankton. Unlike other upwelling systems, autotrophic biomass in the CRD is dominated by picocyanobacteria and small eukaryotes that outcompete larger diatoms and reach extremely high biomass levels. We investigated responses of the subsurface phytoplankton community of the CRD to changes associated with vertical displacement of water masses, coupling in situ transplanted dilution experiments with flow cytometry and epifluorescence microscopy to assess group-specific dynamics. Growth rates of Synechococcus (SYN) and photosynthetic picoeukaryotes (PEUK) were positively correlated with light (Rpearson_SYN = 0.602 and Rpearson_PEUK = 0.588, P chemistry, light also plays a significant role in controlling microphytoplankton populations in the CRD.

  1. Sensitivity of winter phytoplankton communities from Andean lakes to artificial ultraviolet-B radiation Sensibilidad de comunidades fitoplanctónicas invernales de lagos andinos a la radiación ultravioleta-B artificial

    Directory of Open Access Journals (Sweden)

    E. WALTER HELBLING

    2001-06-01

    Full Text Available During July of 1999 sampling was carried out in five Andean lakes to determine the sensitivity of winter phytoplankton communities to ultraviolet-B radiation (UV-B, 280-320 nm. The studied lakes, Moreno, El Trébol, Nahuel Huapi, Gutiérrez, and Morenito, located in the Patagonia region (41° S, 71° W, 800 m of altitude, had attenuation coefficients for UV-B that ranged from 0.36 m-1 (Lake Moreno to 2.8 m-1 (Lake Morenito. The samples were inoculated with labeled carbon (NaH14CO3 and incubated in an illuminated chamber (UV-B = 0.35 W m-2, UV-A [320-400 nm] = 1.1 W m-2, and PAR [400-700 nm] = 10.8 W m-2 at 10 °C. The phytoplankton cells were exposed to UV radiation (280-400 nm + PAR (quartz tubes, and to UV-A + PAR (quartz tubes covered with Mylar-D. The total duration of the experiments was 4 h and two samples were taken from each treatment every hour. In lakes Moreno, El Trébol, Nahuel Huapi and Gutiérrez, the photosynthetic inhibition increased linearly with UV-B doses, while in Lake Morenito just a slight relationship was observed. After receiving a dose of 1.25 kJ m-2 (UV-B, phytoplankton from Lake Morenito had the highest cumulative photosynthetic inhibition (44 %, whereas in Lakes Moreno, El Trébol, Nahuel Huapi and Gutiérrez the inhibition was of 22, 11, 5, and 1 %, respectively. However, at the end of incubation period and after receiving doses of 5 kJ m-2, the most inhibited phytoplankton cells were from Lake Moreno (70 % and the most resistant (27 % was that from Lake Gutiérrez. The kinetics of inhibition was different in each lake, and transparent lakes, with higher proportion of large cells, had higher inhibition rates. The results suggest that an increase in UV-B radiation (e.g., produced by a decrease in stratospheric ozone would have a greater impact on microplankton from clear lakes, while pico- and nanoplankton from less transparent lakes will be less affectedDurante julio de 1999 se realizaron muestreos en cinco lagos

  2. Community-based adaptation to climate change: an update

    Energy Technology Data Exchange (ETDEWEB)

    Ayers, Jessica; Huq, Saleemul

    2009-06-15

    Over a billion people - the world's poorest and most bulnerable communities – will bear the brunt of climate change. For them, building local capacity to cope is a vital step towards resilience. Community-based adaptation (CBA) is emerging as a key response to this challenge. Tailored to local cultures and conditions, CBA supports and builds on autonomous adaptations to climate variability, such as the traditional baira or floating gardens of Bangladesh, which help small farmers' crops survive climate-driven floods. Above all, CBA is participatory – a process involving both local stakeholders, and development and disaster risk reduction practitioners. As such, it builds on existing cultural norms while addressing local development issues that contribute to climate vulnerability. CBA is now gaining ground in many regions, and is ripe for the reassessment offered here.

  3. Toxicity of atmospheric aerosols on marine phytoplankton

    Science.gov (United States)

    Paytan, A.; Mackey, K.R.M.; Chen, Y.; Lima, I.D.; Doney, S.C.; Mahowald, N.; Labiosa, R.; Post, A.F.

    2009-01-01

    Atmospheric aerosol deposition is an important source of nutrients and trace metals to the open ocean that can enhance ocean productivity and carbon sequestration and thus influence atmospheric carbon dioxide concentrations and climate. Using aerosol samples from different back trajectories in incubation experiments with natural communities, we demonstrate that the response of phytoplankton growth to aerosol additions depends on specific components in aerosols and differs across phytoplankton species. Aerosol additions enhanced growth by releasing nitrogen and phosphorus, but not all aerosols stimulated growth. Toxic effects were observed with some aerosols, where the toxicity affected picoeukaryotes and Synechococcus but not Prochlorococcus.We suggest that the toxicity could be due to high copper concentrations in these aerosols and support this by laboratory copper toxicity tests preformed with Synechococcus cultures. However, it is possible that other elements present in the aerosols or unknown synergistic effects between these elements could have also contributed to the toxic effect. Anthropogenic emissions are increasing atmospheric copper deposition sharply, and based on coupled atmosphere-ocean calculations, we show that this deposition can potentially alter patterns of marine primary production and community structure in high aerosol, low chlorophyll areas, particularly in the Bay of Bengal and downwind of South and East Asia.

  4. Distribuição vertical da comunidade fitoplanctônica do lago dos Tigres (Goiás, Brasil - DOI: 10.4025/actascibiolsci.v30i1.1446 Vertical distribution of phytoplankton communities in Tigres Lake (Goiás, Brazil during the rainy and dry seasons - DOI: 10.4025/actascibiolsci.v30i1.1446

    Directory of Open Access Journals (Sweden)

    Ina de Souza Nogueira

    2008-03-01

    Full Text Available O lago dos Tigres é um lago do tipo vale bloqueado, sendo que não foi registrado estudo evidenciando a distribuição vertical fitoplanctônica para esse tipo de lago; dessa forma, esta pesquisa assume um caráter pioneiro. Objetivou-se, nesse trabalho, o reconhecimento temporal e espacial dos padrões verticais de atributos da comunidade fitoplanctônica, detectar os grupos funcionais fitoplanctônicos dominantes e descritivos do sistema e relacioná-los com características limnológicas. O lago estudado foi caracterizado como polimítico quente, sendo que ocorreram eventuais estratificações térmicas nas estações de maior profundidade. Os períodos de seca e início de chuva apresentaram-se tanto limnologicamente (evidenciado pela ACP quanto biologicamente (observado pela ACC distintos. Os meses de seca apresentaram maiores concentrações de nutrientes e maiores transparências. Nesses meses, também foi registrado predomínio dos grupos funcionais Lo, Y , N e W1. Os meses de chuvas apresentaram maiores temperaturas e menores transparências, sendo que os grupos funcionais predominantes foram S1, T e N. Avaliando conjuntamente as características limnológicas, o biovolume e os grupos funcionais, pode-se concluir que o perfil vertical do lago dos Tigres é oligo-mesotróficoTigres Lake is a blocked valley lake, with no registered studies of phytoplankton vertical distribution for that lake type; as such, our work assumes a pioneering nature. The aim of this study was to recognize temporally and spatially the vertical patterns of phytoplankton community attributes, to detect the dominant and descriptive phytoplankton functional groups, and relate them to limnological characteristics. Tigres Lake was characterized as a warm polymictic lake, featuring occasional thermal stratification in deeper stations. The dry and early rainy seasons presented limnological (evidenced by PCA and biological (observed by CCA differences. The dry months

  5. 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...... by a lack of in situ observations of the phytoplankton community composition and its evolution during this critical period. We investigated the dynamics of the phytoplankton community structure at two contrasting sites in the Iceland and Norwegian Basins during the early stage (25 March–25 April...... a biomass. The ICB phytoplankton composition appeared primarily driven by the physicochemical environment, with periodic events of increased mixing restricting further increases in biomass. In contrast, the NWB phytoplankton community was potentially limited by physicochemical and/or biological factors...

  6. The limit of the genetic adaptation to copper in freshwater phytoplankton.

    Science.gov (United States)

    Rouco, Mónica; López-Rodas, Victoria; González, Raquel; Huertas, I Emma; García-Sánchez, María J; Flores-Moya, Antonio; Costas, Eduardo

    2014-08-01

    Copper is one of the most frequently used algaecides to control blooms of toxic cyanobacteria in water supply reservoirs. Among the negative impacts derived from the use of this substance is the increasing resistance of cyanobacteria to copper toxicity, as well as changes in the community structure of native phytoplankton. Here, we used the ratchet protocol to investigate the differential evolution and maximum adaptation capacity of selected freshwater phytoplankton species to the exposure of increasing doses of copper. Initially, a dose of 2.5 μM CuSO4·5H2O was able to completely inhibit growth in three strains of the toxic cyanobacterium Microcystis aeruginosa, whereas growth of the chlorophyceans Dictyosphaerium chlorelloides and Desmodesmus intermedius (represented by two different strains) was completely abolished at 12 μM. A significant increase in resistance was achieved in all derived populations during the ratchet experiment. All the chlorophyceans were able to adapt to up to 270 μM of copper sulfate, but 10 μM was the highest concentration that M. aeruginosa strains were able to cope with, although one of the replicates adapted to 30 μM. The recurrent use and increasing doses of copper in water reservoirs could lead to the selection of copper-resistant mutants of both chlorophyceans and cyanobacteria. However, under high concentrations of copper, the composition of phytoplankton community could undergo a drastic change with cyanobacteria being replaced by copper-resistant chlorophyceans. This result stems from a distinct evolutionary potential of these species to adapt to this substance.

  7. Modeling the influence from ocean transport, mixing and grazing on phytoplankton diversity

    DEFF Research Database (Denmark)

    Adjou, Mohamed; Bendtsen, Jørgen; Richardson, Katherine

    2012-01-01

    Phytoplankton diversity, whether defined on the basis of functional groups or on the basis of numbers of individual species, is known to be heterogeneous throughout the global ocean. The factors regulating this diversity are generally poorly understood, although access to limiting nutrients...... and light is known to influence distributions for certain groups of phytoplankton. Here, we develop a simple box model of biomasses and a limiting nutrient to describe the composition of phytoplankton communities in the euphotic zone. In addition to analyzing the relative importance of nutrient availability...... in generating and maintaining diversity, we apply the model to quantify the potential role of zooplankton grazing and ocean transport for the coexistence of competing species and phytoplankton diversity. We analyze the sensitivity of phytoplankton biomass distributions to different types of grazing functional...

  8. Improving Climate Change Communication Skills through Community Outreach

    Science.gov (United States)

    Hanrahan, J.

    2015-12-01

    While many undergraduate Atmospheric Science departments are expanding their curriculums to focus on the science of climate change, often overlooked is the need to educate students about how this topic can be effectively communicated to others. It has become increasingly difficult for young scientists to comfortably discuss this polarizing topic with people outside of the classroom. To address this, Atmospheric Science faculty at Lyndon State College are providing undergraduate students the opportunity to practice this important skill by reaching out to the local community. Over the past year, students have been meeting regularly to discuss climate change and its impacts, and to present this information to the general public at local schools and organizations. The group was organized with the primary goal of teaching undergraduate students about effective ways to communicate basic climate science to nonscientists, but to also improve public understanding of anthropogenic climate change while starting a conversation among young people in the community. We will identify lessons learned after one year, discuss effective strategies, and summarize student feedback.

  9. Short-term changes in the mesozooplankton community and copepod gut pigment in the Chukchi Sea in autumn: reflections of a strong wind event

    Science.gov (United States)

    Matsuno, K.; Yamaguchi, A.; Nishino, S.; Inoue, J.; Kikuchi, T.

    2015-07-01

    To evaluate the effect of atmospheric turbulence on a marine ecosystem, high-frequency samplings (two to four times per day) of a mesozooplankton community and the gut pigment of dominant copepods were performed at a fixed station in the Chukchi Sea from 10 to 25 September 2013. During the study period, a strong wind event (SWE) was observed on 18 September. After the SWE, the biomass of chlorophyll a (Chl a) increased, especially for micro-size (> 10 μm) fractions. The zooplankton abundance ranged from 23 610 to 56 809 ind. m-2 and exhibited no clear changes as a result of the SWE. In terms of abundance, calanoid copepods constituted the dominant taxa (mean: 57 %), followed by barnacle larvae (31 %). Within the calanoid copepods, small-sized Pseudocalanus spp. (65 %) and large-sized C. glacialis (30 %) dominated. In the population structure of C. glacialis, copepodid stage 5 (C5) dominated, and the mean copepodid stage did not vary with the SWE. The dominance of accumulated lipids in C5 and C6 females with immature gonads indicated that they were preparing for seasonal diapause. The gut pigment of C. glacialis C5 was higher at night and was correlated with ambient Chl a (Chl a, and a significant increase was observed after the SWE (2.6 vs. 4.5 ng pigment ind.-1). The grazing impact by C. glacialis C5 was estimated to be 4.14 mg C m-2 day-1, which corresponded to 0.5-4.6 % of the biomass of the micro-size phytoplankton. Compared with the metabolic food requirement, C. glacialis feeding on phytoplankton accounted for 12.6 % of their total food requirement. These facts suggest that C. glacialis could not maintain their population by feeding solely on phytoplankton and that other food sources (i.e., microzooplankton) must be important in autumn. As observed by the increase in gut pigment, the temporal phytoplankton bloom, which is enhanced by the atmospheric turbulence (SWE) in autumn, may have a positive effect on copepod nutrition.

  10. Everglades Plant Community Response to 20th Century Hydrologic Changes

    Science.gov (United States)

    Willard, D. A.; Bernhardt, C. E.; Holmes, C. W.; Weimer, L. M.

    2002-05-01

    Pollen records in sediment cores from sites in the historic Everglades allowed us to document the natural variability of the ecosystem over the past 2,000 years and contrast it to 20th century changes in wetland plant communities. The natural system included extensive water-lily sloughs, sawgrass ridges, and scattered tree islands extending from Lake Okeechobee southward through Shark River Slough. Between ~1000 AD and 1200 AD, weedy species such as Amaranthus (water hemp) became more abundant, indicating decreased annual rainfall, shorter hydroperiods, and shallower water depths during this time. After ~1200 AD, vegetation returned to its pre-1000 AD composition. During the 20th century, two phases of hydrologic alteration occurred. Completed by 1930, the first phase included construction of the Hoover Dike, canals linking Lake Okeechobee to the Atlantic Ocean, and the Tamiami Trail. Reconstructions of plant communities indicate that these changes shortened hydroperiods and lowered water depths throughout the Everglades. The extent of water-lily slough communities decreased, and tree islands became larger in Shark River Slough. The second phase resulted from construction of canals and levees in the 1950s, creating three Water Conservation Areas. The response of plant communities to these changes varied widely depending on location in the Everglades. In Loxahatchee NWR, weedy and short-hydroperiod plant species became more abundant in marshes, and species composition of tree islands changed. In Water Conservation Area 2A, cattail replaced sawgrass in marshes with high nutrient influx; the ridge and slough structure of the marshes was replaced by more homogeneous sawgrass marshes; sustained high water levels for more than a decade resulted in loss of tree islands that had existed for more than 1,000 years. In Everglades National Park, the extent of slough vegetation decreased further. Near Florida Bay, the rate of mangrove intrusion into fresh-water marshes

  11. Stronger communities? Changing prospects for community-led strategic planning in New Zealand

    Directory of Open Access Journals (Sweden)

    Bruno Brosnan

    2010-12-01

    Full Text Available New Zealand’s Local Government Act 2002 ushered in a new phase in local government, a phase that is best characterised by the term ‘empowerment’. Not only were councils empowered to promote social, economic, environmental and cultural well-being, in contrast with previous more prescriptive legislation, but citizens were empowered to engage in community-led strategic planning. In many respects the new statute reflected contemporary international public management trends in which governance is increasingly being conducted via networks of public and private actors. However, with the change of government from a centre-left Labour-led coalition to a centre-right National-led government following the November 2008 general election, it is less certain that local government and communities will continue to experience a strengthening of the pluralisation of governance that has been a feature of the past decade. This article argues that the potential disempowerment of local government, and possible attenuation of community-led strategic planning in New Zealand, comes at a time when the momentum for devolution to local government and other communities is increasing elsewhere.

  12. Disassembling iron availability to phytoplankton

    Directory of Open Access Journals (Sweden)

    Yeala eShaked

    2012-04-01

    Full Text Available The bioavailability of iron to microorganisms and its underlying mechanisms have far reaching repercussions to many natural systems and diverse fields of research, including ocean biogeochemistry, carbon cycling and climate, harmful algal blooms, soil and plant research, bioremediation, pathogenesis and medicine. Within the framework of ocean sciences, short supply and restricted bioavailability of Fe to phytoplankton is thought to limit primary production and curtail atmospheric CO2 drawdown in vast ocean regions. Yet a clear-cut definition of bioavailability remains elusive, with elements of iron speciation and kinetics, phytoplankton physiology, light, temperature and microbial interactions, to name a few, all intricately intertwined into this concept. Here, in a synthesis of published and new data, we attempt to disassemble the complex concept of iron bioavailability to phytoplankton by individually exploring some of its facets. We distinguish between the fundamentals of bioavailability - the acquisition of Fe-substrate by phytoplankton - and added levels of complexity involving interactions among organisms, iron and ecosystem processes. We first examine how phytoplankton acquire free and organically-bound iron, drawing attention to the pervasiveness of the reductive uptake pathway in both prokaryotes and eukaryotes. Turning to acquisition rates, we propose to view the availability of various Fe-substrates to phytoplankton as spectrum rather than an absolute all or nothing. We then demonstrate the use of uptake rate constants to make comparisons across different studies, organisms, Fe compounds and environments, and for gauging the contribution of various Fe substrates to phytoplankton growth in situ. Last, we describe the influence of aquatic microorganisms on iron chemistry and fate by way of organic complexation and bio-mediated redox transformations and examine the bioavailability of these bio-modified Fe species.

  13. Disassembling iron availability to phytoplankton.

    Science.gov (United States)

    Shaked, Yeala; Lis, Hagar

    2012-01-01

    The bioavailability of iron to microorganisms and its underlying mechanisms have far reaching repercussions to many natural systems and diverse fields of research, including ocean biogeochemistry, carbon cycling and climate, harmful algal blooms, soil and plant research, bioremediation, pathogenesis, and medicine. Within the framework of ocean sciences, short supply and restricted bioavailability of Fe to phytoplankton is thought to limit primary production and curtail atmospheric CO(2) drawdown in vast ocean regions. Yet a clear-cut definition of bioavailability remains elusive, with elements of iron speciation and kinetics, phytoplankton physiology, light, temperature, and microbial interactions, to name a few, all intricately intertwined into this concept. Here, in a synthesis of published and new data, we attempt to disassemble the complex concept of iron bioavailability to phytoplankton by individually exploring some of its facets. We distinguish between the fundamentals of bioavailability - the acquisition of Fe-substrate by phytoplankton - and added levels of complexity involving interactions among organisms, iron, and ecosystem processes. We first examine how phytoplankton acquire free and organically bound iron, drawing attention to the pervasiveness of the reductive uptake pathway in both prokaryotic and eukaryotic autotrophs. Turning to acquisition rates, we propose to view the availability of various Fe-substrates to phytoplankton as a spectrum rather than an absolute "all or nothing." We then demonstrate the use of uptake rate constants to make comparisons across different studies, organisms, Fe-compounds, and environments, and for gaging the contribution of various Fe-substrates to phytoplankton growth in situ. Last, we describe the influence of aquatic microorganisms on iron chemistry and fate by way of organic complexation and bio-mediated redox transformations and examine the bioavailability of these bio-modified Fe species.

  14. 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.

  15. Patchiness in a minimal nutrient – phytoplankton model

    Indian Academy of Sciences (India)

    Hiroshi Serizawa; Takashi Amemiya; Kiminori Itoh

    2008-09-01

    We present a minimal two-component model that can exhibit various types of spatial patterns including patchiness. The model, comprising nutrients and phytoplankton, includes the effect of nutrient uptake by phytoplankton as a Holling type II functional response, and also includes the effect of zooplankton grazing on phytoplankton as a Holling type II non-dynamical term. The mean-field model without the diffusion and advection terms shows both bistability and limit-cycle oscillations as a few parameters such as the input rate of nutrients and the maximum feeding rate of zooplankton are changed. If the parameter values are chosen from the limit-cycle oscillation region, the corresponding reaction–advection–diffusion equations show spatial pattern formations by the combined effects of advection and diffusion by turbulent stirring and mixing, and biological interactions. As the nutrient input is increased, the system behaviour changes from the extinction of the entire phytoplankton to the formation of filamentous patterns, patchiness patterns and homogeneous distributions. These observations suggest that the spatial pattern of phytoplankton can function as an indicator to evaluate the eutrophication level in aquatic ecosystems.

  16. Soil denitrifier community size changes with land use change to perennial bioenergy cropping systems

    Science.gov (United States)

    Thompson, Karen A.; Deen, Bill; Dunfield, Kari E.

    2016-10-01

    Dedicated biomass crops are required for future bioenergy production. However, the effects of large-scale land use change (LUC) from traditional annual crops, such as corn-soybean rotations to the perennial grasses (PGs) switchgrass and miscanthus, on soil microbial community functioning is largely unknown. Specifically, ecologically significant denitrifying communities, which regulate N2O production and consumption in soils, may respond differently to LUC due to differences in carbon (C) and nitrogen (N) inputs between crop types and management systems. Our objective was to quantify bacterial denitrifying gene abundances as influenced by corn-soybean crop production compared to PG biomass production. A field trial was established in 2008 at the Elora Research Station in Ontario, Canada (n  =  30), with miscanthus and switchgrass grown alongside corn-soybean rotations at different N rates (0 and 160 kg N ha-1) and biomass harvest dates within PG plots. Soil was collected on four dates from 2011 to 2012 and quantitative PCR was used to enumerate the total bacterial community (16S rRNA) and communities of bacterial denitrifiers by targeting nitrite reductase (nirS) and N2O reductase (nosZ) genes. Miscanthus produced significantly larger yields and supported larger nosZ denitrifying communities than corn-soybean rotations regardless of management, indicating large-scale LUC from corn-soybean to miscanthus may be suitable in variable Ontario climatic conditions and under varied management, while potentially mitigating soil N2O emissions. Harvesting switchgrass in the spring decreased yields in N-fertilized plots, but did not affect gene abundances. Standing miscanthus overwinter resulted in higher 16S rRNA and nirS gene copies than in fall-harvested crops. However, the size of the total (16S rRNA) and denitrifying bacterial communities changed differently over time and in response to LUC, indicating varying controls on these communities.

  17. Organic nutrient enrichment in the oligotrophic ocean: Impacts on remineralization, carbon sequestration, and community structure

    Science.gov (United States)

    Mackey, K. R.; Paytan, A.; Post, A. F.

    2007-12-01

    In oligotrophic seas where inorganic nitrogen (N) and phosphorus (P) are below the limits of detection, organic forms of these nutrients may constitute greater than 90% of the total N and P in the euphotic zone. The combined enzymatic activity of phytoplankton and heterotrophic bacteria determines the rate of nutrient remineralization, thereby influencing phytoplankton growth rates and carbon sequestration in these regions. In this study we investigated the effects of fertilization with ammonium (NH4), nitrate (NO3), nitrite (NO2), and phosphate (PO4) as well as various forms of organic N (urea, glycine) and P (deoxyribonucleic acid, 2- aminoethyl phosphonic acid, phytic acid) on the growth and taxonomic composition of the phytoplankton community in the Gulf of Aqaba, Red Sea. The impacts of these changes on nutrient cycling and biological assimilation were also assessed. Organic N additions led to phytoplankton growth when given together with PO4, yielding 2-3 fold increases in chlorophyll a (Chl a) and cell density relative to initial levels. Moreover, our results show that addition of NH4 or NO3 led to accumulation of extra-cellular NO2, suggesting that incomplete assimilatory reduction of NO3 by phytoplankton as well as chemoautotrophic oxidation of NH4 by ammonium oxidizing microbes contributed to NO2 formation. These findings conflict with earlier studies in the Gulf that attributed NO2 formation solely to the phytoplankton community. Organic P additions also led to 2-3 fold increases in Chl a and cell density relative to initial levels when given together with NH4 and NO3. Compared to other P additions, DNA led to the rapid accumulation of extra-cellular PO4, indicating substantial nucleotidase activity in excess of the amount needed to meet phytoplankton growth requirements. These results show the importance and interconnectivity of phytoplankton and heterotrophic bacteria communities in contributing to nutrient cycling and carbon sequestration in

  18. 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.

  19. Benefits and limitations of an intercalibration of phytoplankton assessment methods based on the Mediterranean GIG reservoir experience.

    Science.gov (United States)

    Pahissa, José; Catalan, Jordi; Morabito, Giuseppe; Dörflinger, Gerald; Ferreira, João; Laplace-Treyture, Christophe; Gîrbea, Ruxandra; Marchetto, Aldo; Polykarpou, Polina; de Hoyos, Caridad

    2015-12-15

    The status of European legislation regarding inland water quality after the enactment of the Water Framework Directive (WFD) originated scientific effort to develop reliable methods, primarily based on biological parameters. An important aspect of the process was to ensure that quality assessment was comparable between the different Member States. The Intercalibration process (IC), required in the WFD ensures the unbiased application of the norm. The presented results were developed in the context of the 2nd IC phase. An overview of the reservoir type definition of the Lake Mediterranean Geographical Intercalibration Group, where four types were considered divided by both alkalinity and climate, together with the results for selection of Maximum Ecological Potential sites (MEP) are presented. MEP reservoirs were selected based on pressure and biological variables. Three phytoplankton-based assessment methods were intercalibrated using data from Mediterranean countries. The Mediterranean Assessment System for Reservoirs Phytoplankton (Spain), the New Mediterranean Assessment System for Reservoirs Phytoplankton (Portugal and Cyprus) and the New Italian Method (Italy) were applied. These three methods were compared through option 3 of the Intercalibration Guide. The similarity of the assessments was quantified, and the Good/Moderate (GM) boundaries assessed. All three methods stood as comparable at the GM boundary except for the MASRP in siliceous wet reservoirs, which was slightly stricter. Finally, the main taxonomic groups represented in the phytoplankton community at MEP conditions were identified, as well as their main changes with an increasing trophic status. MEP sites are dominated by chrysophytes in siliceous wet reservoirs and by the diatoms Cyclotella and Achnanthes in calcareous ones. Cyanobacteria take over the community in both calcareous and siliceous wet reservoirs as eutrophication increases. In summary, the relevance and reliability of the quality

  20. Effects of Environmental Factors on the Temporal Stability of Phytoplankton Biomass in a Eutrophic Man-Made Lake

    Directory of Open Access Journals (Sweden)

    Wang Tian

    2016-12-01

    Full Text Available The stability of phytoplankton biomass is important in maintaining the health of an aquatic ecosystem. In this study, the main environmental factors and phytoplankton biomass were investigated monthly from May 2011 to April 2013 in a eutrophic lake. The influence of both the mean values and variability (standard deviation of environmental factors on the temporal stability index (TSI, measured as coefficient of variation of phytoplankton was analyzed. Complex relationships were observed between the mean environmental factors and phytoplankton TSI: a positive relationship for dissolved oxygen (DO and pH, a negative relationship for total nitrogen (TN and ammonia nitrogen (NH4+-N, a unimodal relationship for total phosphorus (TP, and no relationship for water temperature (WT. Mean values of DO and pH mainly influenced the stability of phytoplankton through increasing the average total biomass. However, mean TN and NH4+-N concentrations destabilized phytoplankton TSI primarily through increasing the variability of community biomass. There were also complex relationships between the variability of environmental factors and phytoplankton TSI: a negative relationship for TN, a unimodal relationship for NH4+-N and TP, and no relationship for WT, DO, and pH. The variability of nutrient concentrations mainly affected phytoplankton TSI through influencing the variability of community biomass, while their influence on the average total biomass was weak. Results in this research will be helpful in understanding the influence of environmental factors on the temporal stability of phytoplankton.

  1. Assessing the role of dust deposition on phytoplankton ecophysiology and succession in a low-nutrient low-chlorophyll ecosystem: a mesocosm experiment in the Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    V. Giovagnetti

    2012-12-01

    Full Text Available In this study, we investigate the phytoplankton community response, with emphasis on ecophysiology and succession, after two experimental additions of Saharan dust in the surface layer of a low-nutrient low-chlorophyll ecosystem in the Mediterranean Sea. Three mesocosms were amended with evapocondensed dust to simulate realistic Saharan dust events while three additional mesocosms were kept unamended and served as controls. Expe