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Sample records for phytoplankton community analysis

  1. 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

  2. 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

  3. Analysis of phytoplankton distribution and community structure in the German Bight with respect to the different size classes

    Science.gov (United States)

    Wollschläger, Jochen; Wiltshire, Karen Helen; Petersen, Wilhelm; Metfies, Katja

    2015-05-01

    Investigation of phytoplankton biodiversity, ecology, and biogeography is crucial for understanding marine ecosystems. Research is often carried out on the basis of microscopic observations, but due to the limitations of this approach regarding detection and identification of picophytoplankton (0.2-2 μm) and nanophytoplankton (2-20 μm), these investigations are mainly focused on the microphytoplankton (20-200 μm). In the last decades, various methods based on optical and molecular biological approaches have evolved which enable a more rapid and convenient analysis of phytoplankton samples and a more detailed assessment of small phytoplankton. In this study, a selection of these methods (in situ fluorescence, flow cytometry, genetic fingerprinting, and DNA microarray) was placed in complement to light microscopy and HPLC-based pigment analysis to investigate both biomass distribution and community structure of phytoplankton. As far as possible, the size classes were analyzed separately. Investigations were carried out on six cruises in the German Bight in 2010 and 2011 to analyze both spatial and seasonal variability. Microphytoplankton was identified as the major contributor to biomass in all seasons, followed by the nanophytoplankton. Generally, biomass distribution was patchy, but the overall contribution of small phytoplankton was higher in offshore areas and also in areas exhibiting higher turbidity. Regarding temporal development of the community, differences between the small phytoplankton community and the microphytoplankton were found. The latter exhibited a seasonal pattern regarding number of taxa present, alpha- and beta-diversity, and community structure, while for the nano- and especially the picophytoplankton, a general shift in the community between both years was observable without seasonality. Although the reason for this shift remains unclear, the results imply a different response of large and small phytoplankton to environmental influences.

  4. 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.

  5. Characterization of bacterial community associated with phytoplankton bloom in a eutrophic lake in South Norway using 16S rRNA gene amplicon sequence analysis.

    Science.gov (United States)

    Parulekar, Niranjan Nitin; Kolekar, Pandurang; Jenkins, Andrew; Kleiven, Synne; Utkilen, Hans; Johansen, Anette; Sawant, Sangeeta; Kulkarni-Kale, Urmila; Kale, Mohan; Sæbø, Mona

    2017-01-01

    Interactions between different phytoplankton taxa and heterotrophic bacterial communities within aquatic environments can differentially support growth of various heterotrophic bacterial species. In this study, phytoplankton diversity was studied using traditional microscopic techniques and the bacterial communities associated with phytoplankton bloom were studied using High Throughput Sequencing (HTS) analysis of 16S rRNA gene amplicons from the V1-V3 and V3-V4 hypervariable regions. Samples were collected from Lake Akersvannet, a eutrophic lake in South Norway, during the growth season from June to August 2013. Microscopic examination revealed that the phytoplankton community was mostly represented by Cyanobacteria and the dinoflagellate Ceratium hirundinella. The HTS results revealed that Proteobacteria (Alpha, Beta, and Gamma), Bacteriodetes, Cyanobacteria, Actinobacteria and Verrucomicrobia dominated the bacterial community, with varying relative abundances throughout the sampling season. Species level identification of Cyanobacteria showed a mixed population of Aphanizomenon flos-aquae, Microcystis aeruginosa and Woronichinia naegeliana. A significant proportion of the microbial community was composed of unclassified taxa which might represent locally adapted freshwater bacterial groups. Comparison of cyanobacterial species composition from HTS and microscopy revealed quantitative discrepancies, indicating a need for cross validation of results. To our knowledge, this is the first study that uses HTS methods for studying the bacterial community associated with phytoplankton blooms in a Norwegian lake. The study demonstrates the value of considering results from multiple methods when studying bacterial communities.

  6. 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

  7. Pigment signatures of phytoplankton communities in the Beaufort Sea

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    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.

  8. Imaging flow cytometry for phytoplankton analysis.

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    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.

  9. 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.

  10. 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.

  11. Phytoplankton community structure defined by key environmental variables in Tagus estuary, Portugal.

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    Brogueira, Maria José; Oliveira, Maria do Rosário; Cabeçadas, Graça

    2007-12-01

    In this work, we analyze environmental (physical and chemical) and biological (phytoplankton) data obtained along Tagus estuary during three surveys, carried out in productive period (May/June/July) at ebb tide. The main objective of this study was to identify the key environmental factors affecting phytoplankton structure in the estuary. BIOENV analysis revealed that, in study period, temperature, salinity, silicate and total phosphorus were the variables that best explained the phytoplankton spatial pattern in the estuary (Spearman correlation, rho=0.803). A generalized linear model (GLM) also identified salinity, silicate and phosphate as having a high explanatory power (63%) of phytoplankton abundance. These selected nutrients appear to be consistent with the requirements of the dominant phytoplankton group, Baccilariophyceae. Apparently, phytoplankton community is adapted to fluctuations in light intensity, as suspended particulate matter did not come out as a key factor in shaping phytoplankton structure along Tagus estuary.

  12. 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.

  13. [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.

  14. Impact of salinity and pH on phytoplankton communities in a tropical freshwater system: An investigation with pigment analysis by HPLC

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, P.; Acharyya, T.; Babu, P.V.R.; Bandyopadhyay, D.

    An in vitro study was carried out to understand the effects of salinity shock and variation in pH on phytoplankton communities in a tropical freshwater system of the Godavari River (a major peninsular river in India). The distributions of...

  15. 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.

  16. Identifying Phytoplankton Classes In California Reservoirs Using HPLC Pigment Analysis

    Science.gov (United States)

    Siddiqui, S.; Peacock, M. B.; Kudela, R. M.; Negrey, K.

    2014-12-01

    Few bodies of water are routinely monitored for phytoplankton composition due to monetary and time constraints, especially the less accessible bodies of water in central and southern California. These lakes and estuaries are important for economic reasons such as tourism and fishing. This project investigated the composition of phytoplankton present using pigment analysis to identify dominant phytoplankton groups. A total of 28 different sites with a wide range of salinity (0 - 60) in central and southern California were examined. These included 13 different bodies of water in central California: 6 in the Sierras, 7 in the San Francisco Bay Estuary, and 15 from southern California. The samples were analyzed using high-performance liquid-chromatography (HPLC) to quantify the pigments present (using retention time and the spectral thumbprint). Diagnostic pigments were used to indicate the phytoplankton class composition, focusing on diatoms, dinoflagellates, cryptophytes, and cyanobacteria - all key phytoplankton groups indicative of the health of the sampled reservoir. Our results indicated that cyanobacteria dominated four of the seven bodies of central California water (Mono Lake, Bridgeport Reservoir, Steamboat Slough, and Pinto Lake); cryptophytes and nannoflagellates dominated two of the central California bodies of water (Mare Island Strait and Topaz Lake); and diatoms and dinoflagellates dominated one central California body of water, Oakland Inner Harbor, comprising more than 70% of the phytoplankton present. We expect the bodies of water from Southern California to be as disparate. Though this data is only a snapshot, it has significant implications in comparing different ecosystems across California, and it has the potential to provide valuable insight into the composition of phytoplankton communities.

  17. 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...

  18. 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.

  19. 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

  20. 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.

  1. Photoinhibition and the assembly of light-limited phytoplankton communities

    NARCIS (Netherlands)

    Gerla, D.J.; Mooij, W.M.; Huisman, J.

    2011-01-01

    Photoinhibition is characterised by a decreasing rate of photosynthesis with increasing light. It occurs in many photosynthetic organisms and is especially apparent in phytoplankton species sensitive to high light. Yet, the population and community level consequences of photoinhibition are not well

  2. 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.

  3. 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

    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 ai...... ultimately uncoupling high bacterial production from primary production, leading to severe oxygen consumption following ephemeral blooms...

  4. Phytoplankton community structure and stocks in the Southern Ocean (30-80°E) determined by CHEMTAX analysis of HPLC pigment signatures

    Science.gov (United States)

    Wright, Simon W.; van den Enden, Rick L.; Pearce, Imojen; Davidson, Andrew T.; Scott, Fiona J.; Westwood, Karen J.

    2010-05-01

    The geographic distribution, stocks and vertical profiles of phytoplankton of the seasonal ice zone off east Antarctica were determined during the 2005-2006 austral summer during the Baseline Research on Oceanography, Krill and the Environment-West (BROKE-West) survey. CHEMTAX analysis of HPLC pigment samples, coupled with microscopy, permitted a detailed survey along seven transects covering an extensive area between 30°E and 80°E, from 62°S to the coast. Significant differences were found in the composition and stocks of populations separated by the Southern Boundary of the Antarctic Circumpolar Current (SB), as well as a small influence of the Weddell Gyre in the western sector of the 'zone south of the Antarctic Circumpolar Current' (SACCZ). Within the SACCZ, we identified a primary bloom under the ice, a secondary bloom near the ice edge, and an open-ocean deep population. The similarity of distribution patterns across all transects allowed us to generalise a hypothesized sequence for the season. The primary phytoplankton bloom, with stocks of Chl a up to 239 mg m -2, occurred about 35 days before complete disappearance of the sea ice, and contained both cells from the water column and those released from melting ice. These blooms were composed of haptophytes (in particular, colonies and gametes of Phaeocystis antarctica), diatoms and cryptophytes (or the cryptophyte symbiont-containing ciliate Myrionecta rubrum). Aggregates released by melting ice quickly sank from the upper water column and Chl a stocks declined to 56-92 mg m -2, but the bloom of diatoms and, to a lesser extent, cryptophytes continued until about 20 days after ice melt. The disappearance of sea ice coincided with a sharp increase in P. antarctica and grazing, as indicated by increasing phaeophytin a and phaeophorbide a. Chlorophyllide content suggests that the diatom bloom then senesced, probably due to iron exhaustion. Stocks rapidly declined, apparently due to grazing krill that moved

  5. Effects of nutrients and zooplankton on the phytoplankton community structure in Marudu Bay

    Science.gov (United States)

    Tan, Kar Soon; Ransangan, Julian

    2017-07-01

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

  6. 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.

  7. [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.

  8. 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.

  9. 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.

  10. Spatial pattern of spring phytoplankton community in the coastal waters of northern Zhejiang, East China Sea

    Science.gov (United States)

    Ye, Ran; Cai, Yanhong; Wei, Yongjie; Li, Xiaoming

    2017-04-01

    The spatial pattern of phytoplankton community can indicate potential environmental variation in different water bodies. In this context, spatial pattern of phytoplankton community and its response to environmental and spatial factors were studied in the coastal waters of northern Zhejiang, East China Sea using multivariate statistical techniques. Results showed that 94 species belonging to 40 genera, 5 phyla were recorded (the remaining 9 were identified to genus level) with diatoms being the most dominant followed by dinoflagellates. Hierarchical clustering analysis (HCA), nonmetric multidimentional scaling (NMDS), and analysis of similarity (ANOSIM) all demomstrated that the whole study area could be divided into 3 subareas with significant differences. Indicator species analysis (ISA) further confirmed that the indicator species of each subarea correlated significantly with specific environmental factors. Distance-based linear model (Distlm) and Mantel test revealed that silicate (SiO32-), phosphate (PO43-), pH, and dissolved oxygen (DO) were the most important environmental factors influencing phytoplankton community. Variation portioning (VP) finally concluded that the shared fractions of environmental and spatial factors were higher than either the pure environmental effects or the pure spatial effects, suggesting phytoplankton biogeography were mainly affected by both the environmental variability and dispersal limitation. Additionally, other factors (eg., trace metals, biological grazing, climate change, and time-scale variation) may also be the sources of the unexplained variation which need further study.

  11. 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.

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

    Directory of Open Access Journals (Sweden)

    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

  13. 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

  14. Sustaining diversity in trait-based models of phytoplankton communities

    Directory of Open Access Journals (Sweden)

    Agostino eMerico

    2014-10-01

    Full Text Available It is well-established that when equilibrium is attained for two species competing for the same limiting resource in a stable, uniform environment, one species will eliminate the other due to competitive exclusion. While competitive exclusion is observed in laboratory experiments and ecological models, the phenomenon seems less common in nature, where static equilibrium is prevented by the fluctuating physical environment and by other factors that constantly change species abundances and the nature of competitive interactions. Trait-based models of phytoplankton communities appear to be useful tools for describing the evolution of large assemblages of species with aggregate group properties such as total biomass, mean trait, and trait variance, the latter representing the functional diversity of the community. Such an approach, however, is limited by the tendency of the trait variance to unrealistically decline to zero over time. This tendency to lose diversity, and therefore adaptive capacity, is typically solved by fixing the variance or by considering exogenous processes such as immigration. Exogenous processes, however, cannot explain the maintenance of adaptive capacity often observed in the closed environment of chemostat experiments. Here we present a new method to sustain diversity in adaptive trait-based models of phytoplankton communities based on a mechanism of trait diffusion through subsequent generations. Our modeling approach can therefore account for endogenous processes such as rapid evolution or transgenerational trait plasticity.

  15. [Phytoplankton assemblages and their relation to environmental factors by multivariate statistic analysis in Bohai Bay].

    Science.gov (United States)

    Zhou, Ran; Peng, Shi-Tao; Qin, Xue-Bo; Shi, Hong-Hua; Ding, De-Wen

    2013-03-01

    A detailed field survey of hydrological, chemical and biological resources was conducted in the Bohai Bay in spring and summer 2007. The distributions of phytoplankton and their relations to environmental factors were investigated with multivariate analysis techniques. Totally 17 and 23 taxa were identified in spring and summer, respectively. The abundance of phytoplankton in spring was 115 x 10(4) cells x m(-3), which was significantly higher than that in summer (3.1 x 10(4) cells x m(-3)). Characteristics of phytoplankton assemblages in the two seasons were identified using principal component analysis (PCA), while redundancy analysis (RDA) was used to examine the environmental variables that may explain the patterns of variation of the phytoplankton community. Based on PCA results, in the spring, the phytoplankton was mainly distributed in the center and northern water zone, where the nitrate nitrogen concentration was higher. However, in summer, phytoplankton was found distributed in all zones of Bohai Bay, while the dominant species was mainly distributed in the estuary. RDA indicated that the key environmental factors that influenced phytoplankton assemblages in the spring were nitrate nitrogen (NO3(-) -N), nitrite nitrogen (NO2(-) -N) and soluble reactive phosphorus (SRP), while ammonium nitrogen (NH4(+) -N) and water temperature (WT) played key roles in summer.

  16. 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.

  17. 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.

    , zeaxanthin, and alloxanthin) are diagnostic of specific phytoplankton functional groups (diatoms,dinoflagellates,chlorophytes, cyanobacteria and cryptophytes, respectively) and in a few cases can determine phytoplankton composition at the species level...., 2012). The diagnostic pigment (DP) criteria derived from different combinations of marker pigments (Table 1), roughly corresponds to the biomass proportions of various size groups (pico-, nano- and micro-) of phytoplankton (Vidussi et al., 2001...

  18. 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.

  19. 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

    2017-01-20

    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.

  20. 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

  1. 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.

  2. 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.

    seasonal cycle is poorly known. The results of a study on the community structure of phytoplankton for this region, derived from HPLC pigment analysis and microscopic cell counts is presented. The sampling strategy allowed for large spatial and temporal...

  3. Phytoplankton community of Reis lake in the Brazilian Amazon

    Directory of Open Access Journals (Sweden)

    ISE G. SILVA

    2013-06-01

    Full Text Available Reis Lake is located in the municipality of Caracaraí, state of Roraima (Brazil and is subject to fluctuations in water level. The aim of this study was to analyze the structure of the phytoplankton community on the nictemeral and seasonal scales and determined the influence of limnological variables. Sampling was performed in the rainy season (June/2006 and dry season (November/2006, considering two nictemeral cycles. The phytoplankton community was assessed with regard to composition and density, abiotic variables were analyzed simultaneously. The lake had low concentrations of oxygen, clinograde profile and water stratified during the day and homogenous at night, with low concentrations of nutrients and waters ranging from slightly acidic to alkaline. The phytoplankton was represented by 43 taxa, 35 species in the dry season and 29 species in the rainy season. Low densities of phytoplankton occurred in both nictemeral cycles, with accentuated vertical gradient. The highest densities were recorded in the dry season. Reis Lake exhibits characteristics that classify it as a polymythic and oligotrophic environment. The variability in the data was more important seasonally than on the nictemeral scale, supporting the hypothesis of the influence of the hydrological cycle on the dynamics of phytoplankton communities in floodplain lakes.O lago dos Reis está localizado no município de Caracaraí, no estado de Roraima (Brasil e está sujeito a flutuações no nível da água. O objetivo do estudo foi analisar a estrutura da comunidade fitoplanctônica nas escalas nictemeral e sazonal e determinar a influência de variáveis limnológicas nesta comunidade. As amostragens foram realizadas nos periodos chuvoso e seco, considerando dois ciclos nictemeral. A comunidade fitoplanctônica foi avaliada no que diz respeito à composição e densidade, simultaneamente, variáveis abióticas foram analisadas. O lago apresentou baixas concentrações de oxig

  4. 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

  5. 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.

    phytoplankton community from the Qingdao coast (NW Yellow Sea, China) was studied under different CO2 levels in microcosms. HPLC pigment analysis revealed the presence of diatoms as a dominant microalgal group; however, members of chlorophytes...

  6. The influence of key environmental variables on phytoplankton community structure in the estuary of tidal rivers around Luoyuan Bay, China

    Science.gov (United States)

    Pan, Wenbin; Zheng, Peng; Liang, Yunyan; Cai, Yuanbin

    2017-10-01

    A total of 348 species belonging to 8 phyla and 125 genera were observed in seasonally sampled phytoplankton of tidal rivers from 13 sampling sites around Luoyuan Bay, and all field samplings were carried out in productive period (March/June/August/ December) at ebb tide. Bacillariophyta species were the most abundant species, followed by Chlorophyta, Cyanophytes, Euglenophyta, Cryptophyta, Dinophyta, Xanthophyta and Chrysophytas. Seasonal distribution index (SDI) value ranged from 0.63 to 0.86, which meant that species found at those sites in 4 seasons tended to be largely different. Phytoplankton individuals ranged from 5.939×104 ind L-1 in winter to 75.31×104 ind L-1 in autumn. Phytoplankton biomass ranged from 0.620 mg L-1 in summer to 2.373 mg L-1 in autumn. The grey correlation analysis (GCA) showed that the nutrient variables played an important role in the influence on phytoplankton community in every season. The canonical correspondence analysis (CCA) revealed impact of environmental variables on the different species, most of Bacillariophyta species were negative correlation with nutrients (TP and NH3-N) in the four seasons, Chlorophyta species and Cyanophyta species did not show obvious correlation with environment variables in every season. The combination of GRA analysis and CCA analysis provided a method to quantitatively reveal the correlation between phytoplankton community and environmental variables in water body of tidal rivers at this region.

  7. Distribution of phytoplankton community in relation to environmental parameters in cage culture area of Sepanggar Bay, Sabah, Malaysia

    Science.gov (United States)

    Sidik, Madihah Jaffar; Rashed-Un-Nabi, Md.; Azharul Hoque, Md.

    2008-11-01

    This paper covers spatial and temporal variation in phytoplankton communities and physico-chemical water properties in the cage culture area of Sepanggar Bay, Sabah, Malaysia based on field measurement conducted during July 2005 to January 2006 to study the spatial and temporal variation in phytoplankton communities and physico-chemical water properties of the bay. Phytoplankton samples and water parameters data were collected from five different stations located inside the bay during Southwest, Interseasonal and Northeast monsoons. Forty phytoplankton genera, representatives of 23 families, were found in the study area with a mean abundance of 1.55 ± 1.19 × 10 6 cells L -1. Most of these genera belong to diatoms (82.17%), Dinoflagellates (17.55%) and cyanobacteria (0.29%). Three genera were found to be dominant (>10%) in phytoplankton abundance and these were Coscinodiscus spp. (36.38%), Chaetoceros spp (17.65%) and Bacteriastrum spp. (10.98%). The most dominant genus was Coscinodiscus spp. which showed high abundance during all monsoons and stations (except Station 3). Among the seven environmental parameters tested in this study, water temperature, pH and suspended sediment concentration were found to be significantly different between monsoons. On the other hand, no significant differences were found between stations for the studied physico-chemical parameters. A clear differences in phytoplankton densities were observed between monsoons and stations with higher mean abundances during interseasonal monsoon (2.40 ± 1.37 × 10 6 cells L -1) and at station five (2.05 ± 0.74 × 10 6 cells L -1), respectively. Conversely, the diversity indices, both Shannon-Wiener (H) and Pielou (J), showed no significant difference throughout stations and monsoons (except (H) for monsoons). Analysis of similarity (ANOSIM) results demonstrated temporal differences in phytoplankton community structure with highly diverse phytoplankton assemblage. Through cluster analysis five

  8. 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.

  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. 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".

  11. 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.

  12. Response of polar front phytoplankton and bacterial community to micronutrient amendments

    Digital Repository Service at National Institute of Oceanography (India)

    Jain, A.; Meena, R.M.; Naik, R.K.; Gomes, J.; Bandekar, M.; Bhat, M.; Mesquita, A.; Ramaiah, N.

    , to examine the responses of phytoplankton as well as bacterial community (BC) to these micronutrient amendments. Total chlorophyll a (Chl a) concentration increased significantly (P<0.01) in all micronutrient-enriched microcosms (MEM), with the incubation...

  13. Variations in phytoplankton community in a monsoon-influenced tropical estuary

    Digital Repository Service at National Institute of Oceanography (India)

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

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

  14. 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.

  15. 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.

  16. A global seasonal surface ocean climatology of phytoplankton types based on CHEMTAX analysis of HPLC pigments

    Science.gov (United States)

    Swan, Chantal M.; Vogt, Meike; Gruber, Nicolas; Laufkoetter, Charlotte

    2016-03-01

    Much advancement has been made in recent years in field data assimilation, remote sensing and ecosystem modeling, yet our global view of phytoplankton biogeography beyond chlorophyll biomass is still a cursory taxonomic picture with vast areas of the open ocean requiring field validations. High performance liquid chromatography (HPLC) pigment data combined with inverse methods offer an advantage over many other phytoplankton quantification measures by way of providing an immediate perspective of the whole phytoplankton community in a sample as a function of chlorophyll biomass. Historically, such chemotaxonomic analysis has been conducted mainly at local spatial and temporal scales in the ocean. Here, we apply a widely tested inverse approach, CHEMTAX, to a global climatology of pigment observations from HPLC. This study marks the first systematic and objective global application of CHEMTAX, yielding a seasonal climatology comprised of ~1500 1°×1° global grid points of the major phytoplankton pigment types in the ocean characterizing cyanobacteria, haptophytes, chlorophytes, cryptophytes, dinoflagellates, and diatoms, with results validated against prior regional studies where possible. Key findings from this new global view of specific phytoplankton abundances from pigments are a) the large global proportion of marine haptophytes (comprising 32±5% of total chlorophyll), whose biogeochemical functional roles are relatively unknown, and b) the contrasting spatial scales of complexity in global community structure that can be explained in part by regional oceanographic conditions. The results are publically accessible via

  17. 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.

  18. 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.

  19. 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.

  20. Seasonal dynamics of crustacean zooplankton community structure in Erhai Lake, a plateau lake, with reference to phytoplankton and environmental factors

    Science.gov (United States)

    Yang, Wei; Deng, Daogui; Zhang, Sai; Hu, Cuilin

    2014-09-01

    The seasonal dynamics of a crustacean zooplankton community in Erhai Lake was investigated from May 2010 to April 2011. In total, 11 species were recorded, including six (6 genera) cladoceran and five (5 genera) copepod species. The crustacean zooplankton densities ranged from 24.3 to 155.4 ind./L. In winter and spring, the large-bodied cladoceran Daphnia galeata dominated the crustacean plankton community. In summer and autumn, when the colonial or filamentous algae dominated the phytoplankton communities, the small-bodied species (e.g. B osmina fatalis, Ceriodaphnia quadrangular, and Mesocyclops leuckarti) replaced the large-bodied ones. One-way ANOVA and redundancy analysis revealed that community structure was dependent upon total nitrogen, total phosphorus, water temperature, transparency, and the biomass of small algae. The variation in both phytoplankton structure and environmental variables were important factors in the seasonal succession of crustacean zooplankton structure in Erhai Lake.

  1. Spatio-temporal variations in phytoplankton community structure in ...

    African Journals Online (AJOL)

    OMARI

    2013-09-06

    Sep 6, 2013 ... Phytoplankton is usually at the base of aquatic food web and is the most ... brates and fish possessing size-selective feeding habits on zooplankton ..... been found to produce toxic secondary compounds, other cyanobacteria ...

  2. 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

  3. 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.

  4. 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...

  5. 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

  6. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  8. 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

  9. 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

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

    Science.gov (United States)

    Malkassian, Anthony; Nerini, David; van Dijk, Mark A; Thyssen, Melilotus; Mante, Claude; Gregori, Gerald

    2011-04-01

    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 submersible version of the CytoSense flow cytometer (the CytoSub) has been designed for in situ autonomous sampling and analysis, making it possible to monitor phytoplankton at a short temporal scale and obtain accurate information about its dynamics. For data analysis, a manual clustering is usually performed a posteriori: data are displayed on histograms and scatterplots, and group discrimination is made by drawing and combining regions (gating). The purpose of this study is to provide greater objectivity in the data analysis by applying a nonmanual and consistent method to automatically discriminate clusters of particles. In other words, we seek for partitioning methods based on the optical fingerprints of each particle. As the CytoSense is able to record the full pulse shape for each variable, it quickly generates a large and complex dataset to analyze. The shape, length, and area of each curve were chosen as descriptors for the analysis. To test the developed method, numerical experiments were performed on simulated curves. Then, the method was applied and validated on phytoplankton cultures data. Promising results have been obtained with a mixture of various species whose optical fingerprints overlapped considerably and could not be accurately separated using manual gating.

  11. 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

  12. 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

  13. 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.

  14. 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.

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

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    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.

  16. 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.

  17. 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.

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

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    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

  19. 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

  20. 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

  1. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Phytoplankton community dynamics in an intermittently open hypereutrophic coastal lagoon in southern Portugal

    Science.gov (United States)

    Coelho, Susana; Pérez-Ruzafa, Angel; Gamito, Sofia

    2015-12-01

    Phytoplankton community' dynamics were studied in Salgados coastal lagoon in order to evaluate the effects of excessive organic loads and also physical stress caused by the irregular opening of the lagoon. Salgados is a hypereutrophic intermittently open coastal lagoon, which received freshwater inputs from small rivers and from a wastewater treatment plant. Cyanophyceae dominated the phytoplankton communities most of the time; Bacillariophyceae became the main taxonomic group in winter when the lagoon was closed; Chlorophyceae was the major class in early summer; pico-nano flagellate algae accounted for a high percentage of total phytoplankton during spring. Potentially harmful taxa were observed during most of the sampling periods, forming blooms and accounting for a considerable percentage of total phytoplankton abundance. A strong differentiation among dry and wet seasons could be noticed. The dry season was dominated by Microsystis aeruginosa, Rhodomonas sp., pico-nano flagellate algae, Cyclotella spp. and Planktothrix sp., while the wet season, although still with the presence of Microsystis aeruginosa, was dominated by Dolichospermum spiroides. The best environmental variables explaining stations patterns and based on phytoplankton taxa were days of isolation, pH, and salinity. Temperature, cumulative rain and total phosphorus were also related with species and stations patterns. The high nutrient load in Salgados lagoon promoted the development and persistence of harmful algae blooms. Proper management of coastal lagoons involves not only the control of direct discharges of nutrients, but also of other factors, including water level and communication with the sea.

  3. Mesoscale and Sub-mesoscale Variability in Phytoplankton Community Composition in the Sargasso Sea

    Science.gov (United States)

    Bachman, B.; Richardson, T. L.; Lomas, M. W.

    2016-02-01

    The Sargasso Sea is a highly dynamic physical environment in which strong seasonal variability combines with forcing by mesoscale ( 100 km) eddies. Over four cruises (2011 and 2012), we investigated links between water column structure, nutrient regimes, and phytoplankton community composition at a range of time and space scales in the Sargasso Sea. On all cruises, cyanobacteria (Prochlorococcus and Synechococcus) dominated the phytoplankton numerically and haptophytes were the dominant eukaryotes (up to 60% total chl-a). We demonstrated significant effects of mesoscale and inferred sub-mesoscale forcing on phytoplankton community composition. Downwelling (in anticyclones) was coincident with Prochlorococcus abundances 22-66% higher compared to outside stations. We observed a shift in the taxonomic composition of haptophytes between a coccolithophores dominated community in a cyclone in spring 2012 (C2) and a non-coccolithophore community at BATS. At the center of cyclone C1 (summer 2011), we observed significantly higher haptophyte chl-a (non-coccolithophores) and lower cyanobacteria chl-a biomass at the center and edge as compared to BATS. In summer 2012, downwelling associated with anticyclone AC2 occurred at the edge of the eddy and 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 significantly alter phytoplankton community structure. Therefore, while seasonality in the North Atlantic is the primary driver of broad-scale trends in phytoplankton community composition, the effect of transient events must be considered when studying planktonic food webs in the Sargasso Sea.

  4. 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.

  5. 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

  6. 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

  7. Seasonal stages of phytoplankton community structure and sinking loss in the Gulf of Riga

    Science.gov (United States)

    Olli, Kalle; Heiskanen, Anna-Stiina

    1999-12-01

    In this paper, we present the biomass, species composition and sinking losses of phytoplankton and heterotrophic flagellates obtained during three seasonal stages (May 1995; June-July 1994; August 1993) from the Gulf of Riga — a eutrophied, semi-enclosed area in the Baltic Sea. The Gulf was characterised by intensive dinoflagellate (mainly Peridiniella catenata) dominated spring bloom (2700-7600 μg l -1 wet weight) while the diatom Thalassiosira baltica contributed most (80-90%) to the settling phytoplankton biomass (up to 6.5 g m -2 day -1). The mineral nutrients were abundant during the bloom and it is suggested that the differential sedimentation of species was caused by physical factors (thermal stratification of the water column). The phytoplankton biomass in summer (780-2600 μg l -1) was dominated by high abundance of filamentous cyanobacterium Aphanizomenon flos-aquae, autotrophic nanoflagellates and picoplankton. The primary vertical flux of phytoplankton (flos-aquae. Below the pycnocline, resuspended dormant diatom populations caused a significant (up to 1 g m -2 day -1) secondary flux. Large heterotrophic dinoflagellates ( Gyrodinium/Gymnodinium) were abundant (up to 500 μg l -1) in the middle layers and associated to ammonium regeneration. The early autumn stage was a post cyanobacterial bloom situation with relatively low phytoplankton abundance (330-860 μg l -1) dominated by A. flos-aquae and nanoflagellates. Also, the sedimentation of phytoplankton was lowest (up to 340 mg m -2 day -1). Our results indicate high seasonal differences in the phytoplankton community structure and sedimentation. However, the high within-season temporal variability overrules the variability between different areas of the southern part of the Gulf.

  8. Assessing Pigment-Based Phytoplankton Community Distributions in the Red Sea

    KAUST Repository

    Kheireddine, Malika

    2017-05-10

    Pigment-based phytoplankton community composition and primary production were investigated for the first time in the Red Sea in February-April 2015 to demonstrate how the strong south to north environmental gradients determine phytoplankton community structure in Red Sea offshore regions (along the central axis). Taxonomic pigments were used as size group markers of pico, nano-, and microphytoplankton. Phytoplankton primary production rates associated with the three phytoplankton groups (pico-, nano-, and microphytoplankton) were estimated using a bio-optical model. Pico- (Synechococcus and Prochlorococcus sp.) and Nanophytoplankton (Prymnesiophytes and Pelagophytes) were the dominant size groups and contributed to 49 and 38%, respectively, of the phytoplankton biomass. Microphytoplankton (diatoms) contributed to 13% of the phytoplankton biomass within the productive layer (1.5 Zeu). Sub-basin and mesoscale structures (cyclonic eddy and mixing) were exceptions to this general trend. In the southern Red Sea, diatoms and picophytoplankton contributed to 27 and 31% of the phytoplankton biomass, respectively. This result induced higher primary production rates (430 ± 50 mgC m−2 d−1) in this region (opposed to CRS and NRS). The cyclonic eddy contained the highest microphytoplankton proportion (45% of TChla) and the lowest picophytoplankton contribution (17% of TChla) while adjacent areas were dominated by pico- and nano-phytoplankton. We estimated that the cyclonic eddy is an area of enhanced primary production, which is up to twice those of the central part of the basin. During the mixing of the water column in the extreme north of the basin, we observed the highest TChla integrated (40 mg m−2) and total primary production rate (640 mgC m−2 d−1) associated with the highest nanophytoplankton contribution (57% of TChla). Microphytoplankton were a major contributor to total primary production (54%) in the cyclonic eddy. The contribution of picophytoplankton

  9. 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.

  10. 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

  11. Phytoplankton community structure is influenced by seabird guano enrichment in the Southern Ocean

    Science.gov (United States)

    Shatova, O. A.; Wing, S. R.; Hoffmann, L. J.; Wing, L. C.; Gault-Ringold, M.

    2017-05-01

    Phytoplankton biomass, productivity and community structure are strongly influenced by differences in nutrient concentrations among oceanographic water masses. Changes in community composition, particularly in the distribution of cell sizes, can result in dramatic changes in the energetics of pelagic food webs and ecosystem function in terms of biogeochemical cycling and carbon sequestration. Here we examine responses of natural phytoplankton communities from four major water masses in the Southern Ocean to enrichment from seabird guano, a concentrated source of bioactive metals (Mn, Fe, Co, Ni, Cu, Zn) and macronutrients (N, P), in a series of incubation experiments. Phytoplankton communities from sub-tropical water, modified sub-tropical water from the Snares Island wake, sub-Antarctic water and Antarctic water from the Ross Sea, each showed dramatic changes in community structure following additions of seabird guano. We observed particularly high growth of prymnesiophytes in response to the guano-derived nutrients within sub-Antarctic and sub-tropical frontal zones, resulting in communities dominated by larger cell sizes than in control incubations. Community changes within treatments enriched with guano were distinct, and in most cases more extensive, than those observed for treatments with additions of macronutrients (N, P) or iron (Fe) alone. These results provide the first empirical evidence that seabird guano enrichment can drive significant changes in the structure and composition of natural phytoplankton communities. Our findings have important implications for understanding the consequences of accumulation of bioactive metals and macronutrients within food webs and the role of seabirds as nutrient vectors within the Southern Ocean ecosystem.

  12. A microflow cytometer for optical analysis of phytoplankton

    Science.gov (United States)

    Golden, Joel P.; Hashemi, Nastaran; Erickson, Jeffrey S.; Ligler, Frances S.

    2012-01-01

    Analysis of the intrinsic scatter and fluorescence profiles of marine algae can be used for general classification of organisms based on cell size and fluorescence properties. We describe the design and fabrication of a Microflow Cytometer on a chip for characterization of phytoplankton. The Microflow Cytometer measured distinct side-scatter and fluorescence properties of Synechococcus sp., Nitzschia d., and Thalassiosira p. Measurements were confirmed using the benchtop Accuri C6 flow cytometer. The Microflow Cytometer proved sensitive enough to detect and characterize picoplankton with diameter approximately 1 mm and larger phytoplankton of up to 80 mm in length. The wide range in size discrimination coupled with detection of intrinsic fluorescent pigments suggests that this Microflow Cytometer will be able to distinguish different populations of phytoplankton on unmanned underwater vehicles. Reversing the orientation of the grooves in the channel walls returns the sample stream to its original unsheathed position allowing separation of the sample stream from the sheath streams and the recycling of the sheath fluid.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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).

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Analysis of diversity of chromophytic phytoplankton in a mangrove ecosystem using rbcL gene sequencing.

    Science.gov (United States)

    Samanta, Brajogopal; Bhadury, Punyasloke

    2014-04-01

    Phytoplankton forms the basis of primary production in mangrove environments. The phylogeny and diversity based on the amplification and sequencing of rbcL, the large subunit encoding the key enzyme ribulose-1, 5-bisphosphate carboxylase/oxygenase was investigated for improved understanding of the community structure and temporal trends of chromophytic eukaryotic phytoplankton assemblages in Sundarbans, the world's largest continuous mangrove. Diatoms (Bacillariophyceae) were by far the most frequently detected group in clone libraries (485 out of 525 clones), consistent with their importance as a major bloom-forming group. Other major chromophytic algal groups including Cryptophyceae, Haptophyceae, Pelagophyceae, Eustigmatophyceae, and Raphidophyceae which are important component of the assemblages were detected for the first time from Sundarbans based on rbcL approach. Many of the sequences from Sundarbans rbcL clone libraries showed identity with key bloom forming diatom genera namely Thalassiosira, Skeletonema and Nitzschia. Similarly, several rbcL sequences which were diatom-like were also detected highlighting the need to explore diatom communities from the study area. Some of the rbcL sequences detected from Sundarbans were ubiquitous in distribution showing 100% identities with uncultured rbcL sequences targeted previously from the Gulf of Mexico and California upwelling system that are geographically separated from study area. Novel rbcL lineages were also detected highlighting the need to culture and sequence phytoplankton from the ecoregion. Principal component analysis revealed that nitrate is an important variable that is associated with observed variation in phytoplankton assemblages (operational taxonomic units). This study applied molecular tools to highlight the ecological significance of diatoms, in addition to other chromophytic algal groups in Sundarbans.

  3. 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.

  4. 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.

  5. Photophysiological and light absorption properties of phytoplankton communities in the river-dominated margin of the northern Gulf of Mexico

    Science.gov (United States)

    Chakraborty, Sumit; Lohrenz, Steven E.; Gundersen, Kjell

    2017-06-01

    Spatial and temporal variability in photophysiological properties of phytoplankton were examined in relationship to phytoplankton community composition in the river-dominated continental margin of the northern Gulf of Mexico (NGOM). Observations made during five research cruises in the NGOM included phytoplankton photosynthetic and optical properties and associated environmental conditions and phytoplankton community structure. Distinct patterns of spatial and temporal variability in photophysiological parameters were found for waters dominated by different phytoplankton groups. Photophysiological properties for locations associated with dominance by a particular group of phytoplankton showed evidence of photoacclimation as reflected by differences in light absorption and pigment characteristics in relationship to different light environments. The maximum rate of photosynthesis normalized to chlorophyll (PmaxB) was significantly higher for communities dominated (>60% biomass) by cyanobacteria + prochlorophyte (cyano + prochl). The initial slope of the photosynthesis-irradiance (P-E) curve normalized to chlorophyll (αB) was not clearly related to phytoplankton community structure and no significant differences were found in PmaxB and αB between different geographic regions. In contrast, maximum quantum yield of carbon fixation in photosynthesis (Φcmax) differed significantly between regions and was higher for diatom-dominated communities. Multiple linear regression models, specific for the different phytoplankton communities, using a combination of environmental and bio-optical proxies as predictor variables showed considerable promise for estimation of the photophysiological parameters on a regional scale. Such an approach may be utilized to develop size class-specific or phytoplankton group-specific primary productivity models for the NGOM.Plain Language SummaryThis study examined the relationships between phytoplankton community composition and associated

  6. 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

  7. 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.

  8. Phytoplankton distribution and community structure in estuary and fishpond at Subang, Blanakan, West Java

    Science.gov (United States)

    Amadea, E.; Takarina, N. D.; Wardhana, W.

    2017-07-01

    Phytoplankton plays an important role as primary producer and denotes the fertility of territorial waters. Samples were taken from a fishpond and estuary on August 27th, 2016 at Subang, West Java. The purpose of this research was to understand how the distribution and community structure of phytoplankton on fishpond and estuary differ. The result showed that phytoplankton found were composed by 6 classes: Cyanophyceae, Euglenophyceae, Chlorophyceae, Bacillariophyceae, Dinophyceae, and Xanthophyceae. Dinophyceae was found only in estuary, and Xanthophyceae was found only in the fishpond. Index of diversity (H') in the estuary was 2.41 and value of evenness (E) was 0.73. In fishpond, the value of H' was 1.63 and the value of E was 0.59, which shows no significance difference between the two locations. However, there was a difference between the number of Bacillariophyceae and Euglenophyceae found in both locations, and the difference between classes of phytoplankton found shows there might be some relations to the environmental parameters.

  9. 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

  10. 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.

  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. Experimental evaluation of nutrient limitation of phytoplankton communities in the Gulf of Riga

    Science.gov (United States)

    Seppälä, J.; Tamminen, T.; Kaitala, S.

    1999-12-01

    Phytoplankton nutrient limitation was studied in the Gulf of Riga during spring bloom (April 1995), early summer stage (June 1994), cyanobacterial bloom (July 1994) and post cyanobacterial bloom (August 1993). Each year six factorial nutrient enrichment experiments were carried out in various locations in the Gulf; including outer Irbe Strait, northern Gulf and southern Gulf. The responses of natural phytoplankton communities to the nutrient additions (80 μg NH 4-N l -1, 20 μg PO 4-P l -1 and two levels of combined additions) were followed for 3 days using 6 l experimental units. To evaluate the nutrient limitation patterns, time series of chlorophyll a were analysed using polynomial regression models and ranking method, taking advantage of the relatively constant experimental error. Apparent nutrient depletion rates and ratios were estimated, and compared with the changes in particulate nutrient ratios. During the spring diatom bloom in 1995, ambient inorganic nutrient concentrations were still high, and thus phytoplankton biomass did not respond to additions of nutrients. Chlorophyll a specific nutrient depletion rates were low (0.01-0.12 μg N (μg chl a) -1 h -1 and 0.002-0.016 μg P (μg chl a) -1 h -1) and linear over time, thus also revealing that phytoplankton was not limited by these nutrients in that time. In June 1994, there was an areal shift from N limitation in the outer Irbe Strait towards co-limitation in the southern Gulf. Later in July 1994, during the bloom of N-fixing Aphanizomenon flos-aquae, the N limitation was obvious for the whole study area. For this period chlorophyll a specific nutrient depletion rates were high (0.36-0.67 μg N (μg chl a) -1 h -1 and 0.089-0.135 μg P (μg chl a) -1 h -1), and added nutrients were almost totally depleted during the first light period. After the collapse of cyanobacterial bloom in August 1993, the experiment carried out in the southern Gulf indicated P limitation of phytoplankton. The central Gulf was

  13. 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.

  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. 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

  17. 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.

  18. A consistent structure of phytoplankton communities across the warm-cold regions of the water mass on a meridional transect in the East/Japan Sea

    Science.gov (United States)

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

    2017-09-01

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

  19. pCO2 effects on species composition and growth of an estuarine phytoplankton community

    Science.gov (United States)

    Grear, Jason S.; Rynearson, Tatiana A.; Montalbano, Amanda L.; Govenar, Breea; Menden-Deuer, Susanne

    2017-05-01

    The effects of ongoing changes in ocean carbonate chemistry on plankton ecology have important implications for food webs and biogeochemical cycling. However, conflicting results have emerged regarding species-specific responses to pCO2 enrichment and thus community responses have been difficult to predict. To assess community level effects (e.g., production) of altered carbonate chemistry, studies are needed that capitalize on the benefits of controlled experiments but also retain features of intact ecosystems that may exacerbate or ameliorate the effects observed in single-species or single cohort experiments. We performed incubations of natural plankton communities from Narragansett Bay, RI, USA in winter at ambient bay temperatures (5-13 °C), light and nutrient concentrations. Three levels of controlled and constant CO2 concentrations were imposed, simulating past, present and future conditions at mean pCO2 levels of 224, 361, and 724 μatm respectively. Samples for carbonate analysis, chlorophyll a, plankton size-abundance, and plankton species composition were collected daily and phytoplankton growth rates in three different size fractions (20 μm) were measured at the end of the 7-day incubation period. Community composition changed during the incubation period with major increases in relative diatom abundance, which were similar across pCO2 treatments. At the end of the experiment, 24-hr growth responses to pCO2 levels varied as a function of cell size. The smallest size fraction (20 μm size fraction. Cell size distribution shifted toward smaller cells in both the Past and Future treatments but remained unchanged in the Present treatment. Similarity in Past and Future treatments for cell size distribution and growth rate (5-20 μm size fraction) illustrate non-monotonic effects of altered pCO2 on ecological indicators and may be related to opposing physiological effects of high CO2 and low pH both within and among species. Interaction of these effects

  20. 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...

  1. 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

  2. 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.

  3. 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.

  4. Fluorometric Discrimination Technique of Phytoplankton Population Based on Wavelet Analysis

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shanshan; SU Rongguo; DUAN Yali; ZHANG Cui; SONG Zhijie; WANG Xiulin

    2012-01-01

    The discrete excitation-emission-matrix fluorescence spectra(EEMS)at 12 excitation wavelengths (400,430,450,460,470,490,500,510,525,550,570,and 590 nm)and emission wavelengths ranging from 600-750 nm were determined for 43 phytoplankton species.A two-rank fluorescence spectra database was established by wavelet analysis and a fluorometric discrimination technique for determining phytoplankton population was developed.For laboratory simulatively mixed samples,the samples mixed from 43 algal species(the algae of one division accounted for 25%,50%,75%,85%,and 100% of the gross biomass,respectively),the average discrimination rates at the level of division were 65.0%,87.5%,98.6%,99.0%,and 99.1%,with average relative contents of 18.9%,44.5%,68.9%,73.4%,and 82.9%,respectively;the samples mixed from 32 red tide algal species(the dominant species accounted for 60%,70%,80%,90%,and 100% of the gross biomass,respectively),the average correct discrimination rates of the dominant species at the level of genus were 63.3%,74.2%,78.8%,83.4%,and 79.4%,respectively.For the 81 laboratory mixed samples with the dominant species accounting for 75% of the gross biomass(chlorophyll),the discrimination rates of the dominant species were 95.1% and 72.8% at the level of division and genus,respectively.For the 12 samples collected from the mesocosm experiment in Maidao Bay of Qingdao in August 2007,the dominant species of the 11 samples were recognized at the division level and the dominant species of four of the five samples in which the dominant species accounted for more than 80% of the gross biomass were discriminated at the genus level;for the 12 samples obtained from Jiaozhou Bay in August 2007,the dominant species of all the 12 samples were recognized at the division level.The technique can be directly applied to fluorescence spectrophotometers and to the developing of an in situ algae fluorescence auto-analyzer for

  5. 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

  6. 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

  7. Silicate:nitrate ratios of upwelled waters control the phytoplankton community sustained by mesoscale eddies in sub-tropical North Atlantic and Pacific

    Directory of Open Access Journals (Sweden)

    T. S. Bibby

    2010-10-01

    Full Text Available Mesoscale eddies in sub-tropical gyres physically perturb the water column and can introduce macronutrients to the euphotic zone, stimulating a biological response by which phytoplankton communities can become dominated by large phytoplankton. Mesoscale eddies are therefore important in driving export in oligotrophic regions of the modern ocean. The character and magnitude of the biological response sustained by eddies are, however, variable. Here we present data from mesoscale eddies in the Sargasso Sea (Atlantic and the waters off Hawai'i (Pacific, alongside mesoscale events that affected the Bermuda Atlantic Time Series (BATS over the past decade. From this analysis, we suggest that the phytoplankton community structure sustained by mesoscale eddies is predetermined by the relative abundance of silicate over nitrate (Si* in the upwelled waters. We present data that demonstrate that mode-water eddies (MWE in the Sargasso Sea upwell locally formed waters with high Si* to the euphotic zone, and that cyclonic eddies in the Sargasso Sea introduce waters with low Si*, a signature that originated in the iron-limited Southern Ocean. We propose that this phenomenon can explain the observed abundance of large-diatom species in MWE and small prokaryotic phytoplankton in cyclonic features. In contrast to the Atlantic, cyclonic eddies in waters off Hawai'i induce North Pacific Intermediate Water (NPIW that has high Si* and therefore also appears capable of establishing diatom populations. These observations suggest that the structure of phytoplankton communities sustained by eddies may not be directly related to the physical nature of the eddy but rather to the chemical composition of the upwelled waters. This paper links the biological production and export efficiency of mesoscale eddies to events in spatially and temporally disparate locations.

  8. 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. (

  9. Spatial and temporal variability of the phytoplankton community structure in the North Water Polynya, investigated using pigment biomarkers

    DEFF Research Database (Denmark)

    Vidussi, F.; Roy, S.; Lovejoy, C.

    2004-01-01

    . Autotrophic flagellates dominated in April and May along the Canadian coast, where cold Arctic waters with relatively deep mixed layers were found. In contrast, diatoms dominated in May along the Greenland coast in warmer water masses of Atlantic origin and during June in the whole polynya, except......Phytoplankton taxonomic pigments were measured by high-performance liquid chromatography (HPLC) during a 3-month survey (April-June 1998) in the North Water (NOW) Polynya (Canadian Arctic) to investigate changes in phytoplankton biomass and composition and the physical-chemical factors....... The contribution of the different phytoplankton groups to Chl a inferred using a factorization program (CHEMTAX) indicated that the bloom was diatom-dominated (maximum 94% diatoms). The phytoplankton community structure was influenced by the water mass characteristics and the surface circulation pattern...

  10. 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.

  11. 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

  12. Phytoplankton community indicators of changes associated with dredging in the Tagus estuary (Portugal).

    Science.gov (United States)

    Cabrita, Maria Teresa

    2014-08-01

    This work reports changes in suspended particulate matter, turbidity, dissolved Cr, Ni, Cu, Cd, Hg and Pb concentrations, and phytoplankton biomass and composition during a 5-month period dredging operation, in a trace element contaminated area of the Tagus estuary (Portugal). Phytoplankton biomass, diatom:other groups ratio, benthic:pelagic diatom ratio, Margalef's, Simpson's diversity, Shannon-Wiever's, and Warwick and Clarke's taxonomic diversity and distinctness indices, and individual taxa were investigated as indicators of dredging induced changes. Significant rise in sediment resuspension and trace element mobilisation caused by dredging influenced the community structure but not the overall biomass. Benthic diatom displacement into the water column maintained species diversity, and therefore, none of the indices highlighted community changes. Contrastingly, diatom:other groups ratio and benthic:pelagic diatom ratio were reliable indicators for the assessment of dredging induced changes. A shift in composition towards species less susceptible to trace elements was observed, disclosing some individual taxa as potential indicators. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. 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...

  14. 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.

  15. Phytoplankton and bacterial community structures and their interaction during red-tide phenomena

    Science.gov (United States)

    Ismail, Mona Mohamed; Ibrahim, Hassan Abd Allah

    2017-07-01

    Phytoplankton and bacteria diversity were studied before, during and after red tide phenomena during spring season 2015 in the Eastern Harbour (E.H.) of Alexandria, Egypt. Fifty five species of phytoplankton were identified and represented different distinct classes "Bacillariophyceae; Dinophyceae, Chlorophyceae, Cyanophyceae and Eugelenophyceae". Also, Diatom formed the most dominant group. The average number of the phytoplankton density varied from 4.8 × 104 to 1.1 × 106 cell l-1 during the study period and Skeletonema costatum was the agent causing the red tide. The existence percentages of bacteria ranged from 2.6 to 17.9% on all media tested. The bacterial isolates on the nutrient agar medium represented the highest existence with a total percentage of 43.6%, followed by MSA medium (25.7%), while the lowest percentage was for the AA medium at 7.8%. However, twelve isolates were selected as representative for bacterial community during study interval. Based on the morphological, biochemical, physiological and enzymatic characteristics, the bacterial strains were described. Depending on the 16S rDNA gene sequence, three common antagonists were aligned as: Vibrio toranzoniae strain Vb 10.8, Ruegeria pelagia strain NBRC 102038 and Psychrobacter adeliensis strain DSM 15333. The interaction between these bacteria and S. costatum was studied. The growth of S. costatum was significantly lower whenever each bacterium was present as compared to axenic culture. More specifically, 30% (v/v) of the all tested bacteria showed the strongest algicidal activities, as all S. costatum cells were killed after two days. 10% of R. pelagia and P. adeliensis also showed significant algicidal activities within six days.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. Dynamical Analysis of a Nitrogen-Phosphorus-Phytoplankton Model

    Directory of Open Access Journals (Sweden)

    Yunli Deng

    2015-01-01

    Full Text Available This paper presents a nitrogen-phosphorus-phytoplankton model in a water ecosystem. The main aim of this research is to analyze the global system dynamics and to study the existence and stability of equilibria. It is shown that the phytoplankton-eradication equilibrium is globally asymptotically stable if the input nitrogen concentration is less than a certain threshold. However, the coexistence equilibrium is globally asymptotically stable as long as it exists. The system is uniformly persistent within threshold values of certain key parameters. Finally, to verify the results, numerical simulations are provided.

  1. 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...

  2. 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...

  3. 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

  4. 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

  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. Summer aspect of phytoplankton communities in some Montenegrin lakes: Are there changes after more than two decades?

    Directory of Open Access Journals (Sweden)

    Rakočević Jelena

    2012-01-01

    Full Text Available Qualitative and quantitative phytoplankton compositions of 10 Montenegrin lakes were investigated in the summer of 2007. The obtained results were compared with a previous study-period that was undertaken two decades ago. In the first period, diatoms numerically dominated the phytoplankton community in all studied lakes, while in the second period, the same was observed only in three of the ten lakes; in other studied lakes the relative contributions of green algae, dinoflagellates and/or cyanobacteria increased, while the contribution of diatoms decreased. The shift observed in phytoplankton composition and diversity in some of the studied lakes indicates an increase in the trophic level over the two decades. The sustainable management plan of the aquatic ecosystems in Montenegro should include the establishment of an environmental monitoring system in order to record any alterations that may take place in water quality.

  7. Seasonal variation in the biochemical compositions of phytoplankton and zooplankton communities in the southwestern East/Japan Sea

    Science.gov (United States)

    Jo, Naeun; Kang, Jae Joong; Park, Won Gyu; Lee, Bo Ram; Yun, Mi Sun; Lee, Jang Han; Kim, Su Min; Lee, Dasom; Joo, HuiTae; Lee, Jae Hyung; Ahn, So Hyun; Lee, Sang Heon

    2017-09-01

    The macromolecular composition of phytoplankton communities and the proximate composition of zooplankton communities were measured monthly in the southwestern East/Japan Sea from April to November 2014 in order to identify seasonal changes in, and relationships among, the biochemical compositions in both phytoplankton and zooplankton. The carbohydrate content of phytoplankton was highest in June, whereas the protein content was highest in August and lipids were highest in April. Overall, carbohydrates were dominant (53.2 ± 12.5%) in the macromolecular composition of phytoplankton during the study period. This composition is believed to result from the dominance of diatoms and/or nutrient-depleted conditions. In comparison, the protein level of zooplankton was highest in November, whereas lipids were slightly higher in May than other months. Overall, proteins were the dominant organic compounds (47.9±8.6% DW) in zooplankton communities, whereas lipids were minor components (5.5±0.6% DW). The high protein content of zooplankton might be related to the abundance of copepods, whereas the low lipid content might be due to a relatively high primary production that could provide a sufficient food supply for zooplankton so that they do not require high lipid storage. A significant positive correlation (r=0.971, n=7, pJapan Sea ecosystem's response to the many environmental changes associated with global warming.

  8. Unravel the submesoscale dynamics of the phytoplanktonic community in the NW Mediterranean Sea by in situ observations: the 2015 OSCAHR cruise

    Science.gov (United States)

    Marrec, Pierre; Doglioli, Andrea M.; Grégori, Gérald; Della Penna, Alice; Wagener, Thibaut; Rougier, Gille; Bhairy, Nagib; Dugenne, Mathilde; Lahbib, Soumaya; Thyssen, Melilotus

    2017-04-01

    Submesoscale phenomena have been recently recognized as a key factor in physical-biological-biogeochemical interactions, even if it remains unclear how these processes affect the global state of the ocean. Significant large-scale impacts of submesoscale structures on primary production and influence on the phytoplankton community structure and diversity have also been reported. In the past decade submesoscale dynamics have been predominately studied through the analysis of numerical simulations. Observing the coupled physical and biogeochemical variability at this scale remains challenging due to the ephemeral nature of submesoscale structures. The in-situ study of such structures necessitates multidisciplinary approaches involving in situ observations, remote sensing and modeling. Last progresses in biogeochemical sensor development and advanced methodology including Lagrangian real-time adaptative strategies represent outstanding opportunities. The OSCAHR (Observing Submesoscale Coupling At High Resolution) campaign has been conducted thanks to a multidisciplinary approach in order to improve the understanding of submesoscale processes. An ephemeral submesoscale structure was first identified in the Ligurian Sea in fall 2015 using both satellite and numerical modeling data before the campaign. Afterwards, advanced observing systems for the physical, biological and biogeochemical characterization of the sea surface layer at a high spatial and temporal frequency were deployed during a 10-days cruise. A MVP (Moving Vessel Profiler) was used to obtain high resolution CTD profiles associated to a new pumping system with 1-m vertical resolution. Moreover, along the ship track, in addition to the standard measurements of seawater surface samples (Chl-a, nutrients, O2, SST, SSS …), we deployed an automated flow cytometer for near real-time characterization of phytoplankton functional groups (from micro-phytoplankton down to cyanobacteria). The observed submesoscale

  9. 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.

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

    Science.gov (United States)

    Xu, Henglong; Min, Gi-Sik; Choi, Joong-Ki; Al-Rasheid, Khaled A. S.; Lin, Xiaofeng; Zhu, Mingzhuang

    2010-03-01

    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 species were identified, belonging to six taxonomic groups (dinoflagellates, diatoms, cryptophyceans, chlorophyceans, euglenophyceans and chrysophyceans). A single peak of protist abundance occurred in October, mainly due to chlorophyceans, diatoms and chrysophyceans. Two biomass peaks in July and October were primarily due to dinoflagellates and diatoms. Temporal patterns of the phytoplankton communities significantly correlated with the changes in nutrients, temperature and pH, especially phosphate, either alone or in combination with NO3-N and NH3-N. Species diversity, evenness and richness indices were clearly correlated with water temperature and/or salinity, whereas the biomass/abundance ratio showed a significant correlation with NO3-N. The results suggest that phytoplankton are potentially useful bioindicators to water quality in semi-enclosed mariculture systems.

  11. Food Quality and Phytoplankton Community Composition in San Francisco Bay using Imaging Spectroscopy Data from the California HyspIRI Airborne Campaign

    Science.gov (United States)

    Palacios, S. L.; Peacock, M. B.; Golini, A. N.; Cloern, J. E.; Senn, D. B.; Guild, L. S.; Kudela, R. M.

    2016-12-01

    The San Francisco Bay (SFB) is the largest estuary on the west coast of the United States. It is an important transition zone between marine, freshwater, and inland terrestrial watersheds. The SFB is an important region for the cycling of nutrients and pollutants and it supports nurseries of ecologically and commercially important fisheries, including some threatened species. Phytoplankton community structure influences food web dynamics, and the taxonomy of the phytoplankton may be more important in determining primary "food quality" than environmental factors. As such, estimating food quality from phytoplankton community composition can be a robust tool to understand trophic transfer of energy. Recent work explores phytoplankton "food quality" in SFB through the use of microscopy and phytoplankton chemotaxonomy to evaluate how changes in phytoplankton composition may have influenced the recent trophic collapse of pelagic fishes in the northern part of the SFB. The objective of this study is to determine if the approach can also be applied to imaging spectroscopy data in order to quantify phytoplankton "food quality" from space. Imaging spectroscopy data of SFB from the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) was collected during the Hyperspectral Infrared (HyspIRI) Airborne Campaign in California (2013 - 2015) and used in this study. Estimates of ocean chlorophyll and phytoplankton community structure were determined using standard ocean chlorophyll algorithms and the PHYtoplankton Detection with Optics (PHYDOTax) algorithms. These were validated using in situ observations of phytoplankton composition using microscopic cell counts and phytoplankton chemotaxonomy from the US Geological Survey's ship surveys of the SFB. The findings from this study may inform the use of future high spectral resolution satellite sensors with the spatial resolution appropriate for coastal systems (e.g., HyspIRI) to assess "food quality" from space.

  12. Does microphytobenthos resuspension influence phytoplankton in shallow systems? A comparison through a Fourier series analysis

    Science.gov (United States)

    Brito, Ana C.; Fernandes, Teresa F.; Newton, Alice; Facca, Chiara; Tett, Paul

    2012-09-01

    Shallow coastal lagoons, especially the ones with clear waters and lighted substrata, are likely to have large microphytobenthos (MPB) communities. MPB is an important component of these systems, representing up to 99% of the chlorophyll concentration when compared to phytoplankton. It is therefore expected that MPB resuspension play a key role in the dynamics of phytoplankton due to the tide and wind action. Water samples were collected twice per month inside and outside Ria Formosa lagoon (Portugal), for nutrients and chlorophyll a (chl a). Sediment samples were also collected for MPB chl a. Chl a was also analysed in water and sediment samples from Venice lagoon (Italy), at least once per month. A truncated Fourier series was fitted to the data to investigate the seasonal and high-frequency components of the time-series. In the Ria Formosa, the best significant fit for MPB was obtained considering the sum of 26 wave-pairs (sin and cosine), which explained 31% of the variability. The seasonal cycle (1-3 waves) explained approximately 5% of the total variability. Within-day variability which includes spatial heterogeneity explained 61% of the variability. The best fit for phytoplankton inside Ria Formosa was obtained considering the sum of 23 wave-pairs. Outside the lagoon the best fit was obtained using only the sum of 16 wave-pairs. For both cases, the sum of waves explained more than 64% of the variability and the seasonal cycle explained more than 31% of the variability. It is expected that primary producers in the water column have a strong seasonal factor due to the direct effect of the solar cycle, which is the case of other clear waters. In the Venice lagoon, which is microtidal, the best fit for MPB was obtained using 10 wave-pairs. However, the best fit for phytoplankton was obtained with only 3 wave-pairs, indicating the importance of the seasonal cycle. Significant relationships were found between phytoplankton inside and outside the Ria Formosa, as

  13. 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.

  14. 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.

  15. Effect of land use on water quality and phytoplankton community in the tropical Khami River in semi-arid southwest Zimbabwe

    National Research Council Canada - National Science Library

    Dzinomwa, T; Ndagurwa, HGT

    2017-01-01

    The water quality and phytoplankton community assemblage of the Khami River, a tropical river sub catchment in semi-arid southwest Zimbabwe impacted by agriculture and urban land use, were examined in March 2015...

  16. Response of the phytoplankton community to water quality in a local alpine glacial lake of Xinjiang Tianchi, China: potential drivers and management implications.

    Science.gov (United States)

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

    2017-08-31

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

  17. Biophysical modelling of phytoplankton communities from first principles using two-layered spheres: Equivalent Algal Populations (EAP) model

    CSIR Research Space (South Africa)

    Robertson Lain, L

    2014-07-01

    Full Text Available (PFT) analysis. To these ends, an initial validation of a new model of Equivalent Algal Populations (EAP) is presented here. This paper makes a first order comparison of two prominent phytoplankton Inherent Optical Property (IOP) models with the EAP...

  18. 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

  19. The community of phytoplankton of the Dagestan area of Caspian Sea in the new ecological conditions

    Directory of Open Access Journals (Sweden)

    A. Sh. Gasanova

    2008-01-01

    Full Text Available The materials about the phytoplankton composition and distribution in the Daghestan region of the Caspian Sea in connection with changing hydrologicaly-hydrochemical regime in conditions of anthropological and biological environment are presented. It was shown, that the change of water regime brought to alterations in floristic composition of sea weeds and succession of phytoplankton change group. Water biocoenosises of different seacoast zone distinguished specific characterdynamics. Introduction of Mnemiopsis leidyi (A. Agassiz influences on phytoplankton association structure

  20. Multivariate-Analysis of Phytoplankton and Related Environmental-Factors, in a Shallow Hypertrophic Lake

    NARCIS (Netherlands)

    Romo, S.; Van Tongeren, O.F.R.

    1995-01-01

    Data on some relevant environmental variables and phytoplankton species composition, collected from the hypertrophic shallow lake Albufera of Valencia (Spain) during 1980-88, were examined using Redundancy Analysis (RDA). The hydrological cycle of the lake is manipulated for rice cultivation in the

  1. Multivariate-Analysis of Phytoplankton and Related Environmental-Factors, in a Shallow Hypertrophic Lake

    NARCIS (Netherlands)

    Romo, S.; Van Tongeren, O.F.R.

    1995-01-01

    Data on some relevant environmental variables and phytoplankton species composition, collected from the hypertrophic shallow lake Albufera of Valencia (Spain) during 1980-88, were examined using Redundancy Analysis (RDA). The hydrological cycle of the lake is manipulated for rice cultivation in the

  2. 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

  3. 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.

  4. 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.

  5. 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

  6. 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 filaments) have chemical and biological manifestations (Brink et al., 1998; Belkin et al., 2009; Read et al., 2000) and are thought to be hotspots for phytoplankton blooms (Hesse et al., 1989, Franks et al., 1992). The Indian National Centre for Ocean...., Barton, E D., Pilling, I., 1993. Development, persistence, and variability of upwelling filaments off the Atlantic coast of the Iberian Peninsula. J. Geophys. Res. 98, 22681-22692. Hesse, KJ., Liu, Z L., Schaumann, K., 1989. Phytoplankton and fronts...

  7. [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.

  8. Lagrangian Analysis of Kerguelen's Naturally Iron-fertilised Phytoplankton Bloom

    Science.gov (United States)

    Della Penna, A.; Trull, T. W.; Grenier, M.; Wotherspoon, S.; Johnson, C.; De Monte, S.; d'Ovidio, F.

    2015-12-01

    The role of iron as a limiting micro-nutrient for primary production in High Nutrient Low Chlorophyll regions has been highlighted by paleoceanography, artificial fertilisation experiments and observed naturally fertilised systems. Examples of natural fertilisation have suggested that (sub-)mesoscale (1-100 km, days-months) horizontal transport modulates and structures the spatial and temporal extent of iron enrichment, phytoplankton production and biogeography. Here we combine different satellite products (altimetry, ocean color, PHYSAT), in-situ sampling, drifting floats and autonomous profilers to analyse the naturally iron-fertilised phytoplankton bloom of the Kerguelen region (Southern Ocean). Considering the Kerguelen Plateau as the main local source of iron, we compute two Lagrangian diagnostics: the "age" - how long before a water parcel has touched the plateau- and the "origin" - the latitude where a water parcel has left the plateau. First, we verify that these altimetry-defined diagnostics' spatial patterns -computed using geostrophic and Ekman corrected velocity fields- are coherent with the ones structuring the trajectories of more than 100 drifters and that trends in surface Chlorophyll (Chl) present an overall agreement with total column content (yet with ~2-3x differences in dynamic ranges likely due to the varying presence of Chl below the mixed layer). Second, assuming a first-order removal, we fit "age" with iron measurements and we estimate removal rates for bloom and abiotic conditions of respectively 0.058 and 0.041 1/d. Then, we relate "age" and "origin" with locations of high Chl concentrations and diatom-dominance. We find out that locations of high Chl concentration correspond to water parcels that have recently left the plateau. Furthermore, general additive models reveal that recently enriched waters are more likely to present a diatom dominance. However, the expected exponential fit varies within the geographic domain suggesting that

  9. 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

  10. 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.

  11. Analysis method of intracellular iron accumulated in phytoplankton

    Directory of Open Access Journals (Sweden)

    Jorge Falcão Paredes

    1977-01-01

    Full Text Available A colorimetric method for the assessment of iron accumulated in the cells of phytoplankton utilizing potassium ferrocyanide was developed. Two experiences with Phaeodactylum tricornutum and Chlorella sp. were carried out: the first one, on uptake of the iron relatively to the age of the culture: the second one, on the iron uptake by the cells, relatively to different concentrations of the chelator EDTA.Foi desenvolvido um método para análise do ferro acumulado em células de fitoplâncton, usando ferrocianeto de potássio como agente complexante. Com esse objetivo montaram-se duas experiências: uma em que se mostra o acúmulo de ferro em relação à idade das células e uma segunda experiência onde a assimilação é plotada em função da concentração de EDTA no meio de cultura.

  12. 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

  13. The response of a natural phytoplankton community from the Godavari River Estuary to increasing CO2 concentration during the pre-monsoon period

    Digital Repository Service at National Institute of Oceanography (India)

    Biswas, H.; Cros, A.; Yadav, K.; Ramana, V.V.; Prasad, V.R.; Acharyya, T.; Babu, P.V.R.

    also been reported by many authors (Trond et al., 2007; Currie and Kalff, 1984). Even diatoms can be out-done by bacteria during such conditions (Brussard and Riegman, 1998). However, the efficiency of bacteria in competing with phytoplankton..., cyanobacteria can easily compete with diatoms in a mixed population under high CO 2 supply and low silicate concentrations. 19 Conclusion: A natural phytoplankton community in the Godavari River Estuary was found to be quite sensitive to increasing CO...

  14. 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...

  15. 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...

  16. 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

  17. The response of San Francisco Bay Delta phytoplankton communities to experimental ammonium, nitrate, and wastewater effluent additions and changes in irradiance

    Science.gov (United States)

    Strong, A. L.; van Dijken, G.; Mills, M. M.; Huang, I. B.; Francis, C.; Monismith, S. G.; Arrigo, K. R.

    2016-02-01

    The Bay Delta ecosystem exhibits unusually low levels of productivity, given the high levels of inorganic nutrient loading to the system. It has been suggested that anthropogenic ammonium (NH4+) loading inhibits diatom nitrate (NO3-) uptake and ultimately prevents blooms from occurring. From May 5-May 9, 2015, we conducted experimental manipulations and water column profiling research in the Bay Delta, in order to assess the ecological effects of anthropogenic nitrogen loading in the lower Sacramento River on phytoplankton growth, community structure, and dissolved inorganic nitrogen (N) uptake rates. We collected surface water at three locations, two located above and one below the Sacramento Regional wastewater treatment plant's diffuser pipe and incubated water for 48 hours. Experimental treatments included control, +NH4+ to 60 µM, +NO3- to 7.5 µM, and added whole wastewater effluent containing 60 µM NH4+. The water was incubated at ambient water temperature in 10-L cubitainers at two light levels: 50% and 5% of surface irradiance. Over two days, chlorophyll a (Chl a) concentrations increased seven-fold in response to both the +NH4+ and effluent additions at the upstream stations in the 50% light treatment, suggesting strong phytoplankton growth in response to added NH4+. Organic carbon accumulation showed similar patterns, and inorganic nutrients, including dissolved silica were all significantly drawn down. At all stations, Chl a accumulation was strongly affected by light limitation in the 5% light treatment. We also report changes in phytoplankton community structure, based on microscopy enumeration and HPLC pigment analysis. among treatments over the 48 hours. Additionally, we assessed variations in NO3- and NH4+ uptake and CO2 fixation across treatments over the course of the incubation. Taken as a whole, our results suggest that NH4+ from wastewater effluent does not inhibit phytoplankton growth in the Bay Delta, contrary to what has been previously

  18. 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.

  19. 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.

  20. 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,...

  1. 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.

  2. 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

  3. 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

  4. 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

  5. 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.

  6. 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...

  7. 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.

  8. 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.

  9. Simulation of phytoplankton biomass in Quanzhou Bay using a back propagation network model and sensitivity analysis for environmental variables

    Institute of Scientific and Technical Information of China (English)

    ZHENG Wei; SHI Honghua; SONG Xikun; HUANG Dongren; HU Long

    2012-01-01

    Prediction and sensitivity models,to elucidate the response of phytoplankton biomass to environmental factors in Quanzhou Bay,Fujian,China,were developed using a back propagation(BP)network.The environmental indicators of coastal phytoplankton biomass were determined and monitoring data for the bay from 2008 was used to train,test and build a three-layer BP artificial neural network with multi-input and single-output.Ten water quality parameters were used to forecast phytoplankton biomass (measured as chlorophyll-a concentration).Correlation coefficient between biomass values predicted by the model and those observed was 0.964,whilst the average relative error of the network was-3.46% and average absolute error was 10.53%.The model thus has high level of accuracy and is suitable for analysis of the influence of aquatic environmental factors on phytoplankton biomass.A global sensitivity analysis was performed to determine the influence of different environmental indicators on phytoplankton biomass.Indicators were classified according to the sensitivity of response and its risk degree.The results indicate that the parameters most relevant to phytoplankton biomass are estuary-related and include pH,sea surface temperature,sea surface salinity,chemical oxygen demand and ammonium.

  10. Studies on phytoplankton-bacterial interactions

    Digital Repository Service at National Institute of Oceanography (India)

    DeCosta, P.M.

    Given the sheer range of phytoplankton-bacterial interactions, some intriguing aspects have been addressed in this study. Firstly, the role of bacteria in influencing phytoplankton communities at the system level was examined. The seasonal changes...

  11. 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.

    ) cells l sup(-1)). Phytoplankton community was formed by larger diatoms in October 2007, dominated by Hemidiscus hardmannianus and Ditylum brightwellii (300-500 mu m in diameter) whereas in October 2006 smaller diatoms such as Lioloma elongatum (2-4 mu m...

  12. Diel Cycle of Photosynthetic Electron Transport and Fluorescence Characteristics in Natural Phytoplankton Communities.

    Science.gov (United States)

    Kolber, Z.; Klimov, D.

    2007-12-01

    Phytoplankton photosynthetic performance is strongly controlled by the daily irradiance cycle. The most pronounced effects are the photoinhibition of photosynthetic activity in the morning and noon hours, and the development of non-photochemical quenching throughout the day. These two effects are extensively investigated as they significantly diminish the daily production rates. Less obvious, but equally important are the daily changes in the kinetics of rate-limiting electron transport within Photosystem II and Photosystem I of the photosynthetic apparatus. Using a fast repetition rate (FRR) fluorometer operating in the continuous flow-through mode in the Eastern Tropical Pacific, we observed theses rates to decelerate by a factor of five during the night, but recovering to a full speed just before the dawn. We characterized the effects of these changes on the photosynthetic performance of phytoplankton by continuously recording the fast light curves (variable fluorescence versus irradiance relationship). Besides controlling photochemistry, these changes strongly affect the chlorophyll fluorescence yield, especially when measured with a multiple turnover excitation. We will discuss how the knowledge of these rate-limiting steps may improve the fluorescence-based estimates of photosynthesis and chlorophyll biomass.

  13. 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.

  14. 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

  15. 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。

  16. 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.

  17. 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.

  18. Studies on Antarctic phytoplankton

    Digital Repository Service at National Institute of Oceanography (India)

    Pant, A.

    Ice-edge data from a single polynya station at 70 degrees S 11 degrees E over a 2-month period is assessed in relation to previously published work in similar environments. The phytoplankton community seems to be composed of 2 quite different...

  19. 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

  20. Interaction among non-toxic phytoplankton, toxic phytoplankton and zooplankton: inferences from field observations.

    Science.gov (United States)

    Roy, Shovonlal; Bhattacharya, Sabyasachi; Das, Partha; Chattopadhyay, Joydev

    2007-02-01

    We explore the mutual dependencies and interactions among different groups of species of the plankton population, based on an analysis of the long-term field observations carried out by our group in the North-West coast of the Bay of Bengal. The plankton community is structured into three groups of species, namely, non-toxic phytoplankton (NTP), toxic phytoplankton (TPP) and zooplankton. To find the pair-wise dependencies among the three groups of plankton, Pearson and partial correlation coefficients are calculated. To explore the simultaneous interaction among all the three groups, a time series analysis is performed. Following an Expectation Maximization (E-M) algorithm, those data points which are missing due to irregularities in sampling are estimated, and with the completed data set a Vector Auto-Regressive (VAR) model is analyzed. The overall analysis demonstrates that toxin-producing phytoplankton play two distinct roles: the inhibition on consumption of toxic substances reduces the abundance of zooplankton, and the toxic materials released by TPP significantly compensate for the competitive disadvantages among phytoplankton species. Our study suggests that the presence of TPP might be a possible cause for the generation of a complex interaction among the large number of phytoplankton and zooplankton species that might be responsible for the prolonged coexistence of the plankton species in a fluctuating biomass.

  1. 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.

  2. 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.

  3. 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

    于2009年按季度对浙江省临安市内的青山水库进行调查,测定了水体环境因子、浮游植物群落,采用营养状态指数法对水库水质现状进行了分析和评价,并探讨了浮游植物与环境因子之间的关系.结果表明:青山水库处于轻度富营养化和中度富营养化之间,水库入库处营养状态综合指数高于库中和大坝处.调查期间共发现浮游植物7门40属89种.不同季节浮游植物主要优势种类不同,春季以硅藻、隐藻和甲藻为主,夏季以蓝藻和绿藻为主,秋季以蓝藻、硅藻和隐藻为主,冬季以硅藻和隐藻为主.相关分析表明,青山水库浮游植物密度与出入库流量和透明度呈显著负相关,与总磷呈显著正相关.典范对应分析(CCA)表明,出入库流量、水温、溶解氧和营养盐是影响水体浮游植物分布格局的重要环境因子.%Qingshan Reservoir is an important utilization large reservoir which was built in 1964.Its eco-environment and water management have a great significance on sustainable development of this area.With the fast economical development,the water quality has been declined as an amount of pollutants discharged.To explore the characteristics of the phytoplankton community structure and the response of water quality,a survey was carried out quarterly in Qingshan Reservoir in 2009.Based on the analysis of phytoplankton and water samples from inflow,center and dam in Qingshan Reservoir,the characteristics of community structure and abundance distribution were studied,and the water situation was evaluated.Cell number and species identification were performed by light microscope.The dominant population,species diversity and community structure of phytoplankton were determined as well.A total of 89 species in 40 genera and 7 divisions were identified,which the most abundant group was Chlorophyta,with 33 species that account for 37% of total species,followed by Bacillariophyta (27 species

  4. [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

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. 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

  10. Phytobenthos and phytoplankton community changes upon exposure to a sunflower oil spill in a South African protected freshwater wetland

    CSIR Research Space (South Africa)

    Oberholster, Paul J

    2010-08-01

    Full Text Available . At the intracellular level, phytoplankton chlorophyll a and b concentrations as physiological variables were more sensitive indicators of the adverse effects of sunflower oil than the 72 h Selenastrum capricornutum algal bioassay conducted....

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

    Digital Repository Service at National Institute of Oceanography (India)

    Ahmed, A.; Kurian, S.; Gauns, M.; ChndrasekharaRao, A.V.; Mulla, A.; Naik, B.; Naik, H.; Naqvi, S.W.A.

    .H., 2003. Phytoplankton photopigments as indicators of estuarine and coastal eutrophication. BioScience. 53(10), 953-964. Partensky, F., Hess, W.R., Vaulot, D., 1999. Prochlorococcus, a marine photosynthetic prokaryote of global significance. Microbiol...

  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 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.

  13. 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

  14. Biological production, export efficiency, and phytoplankton communities across 8000 km of the South Atlantic

    Science.gov (United States)

    Howard, E. M.; Durkin, C. A.; Hennon, G. M. M.; Ribalet, F.; Stanley, R. H. R.

    2017-07-01

    In situ oxygen tracers (triple oxygen isotope and oxygen/argon ratios) were used to evaluate meridional trends in surface biological production and export efficiency across 8000 km of the tropical and subtropical South Atlantic in March-May 2013. We used observations of picophytoplankton, nanophytoplankton, and microphytoplankton to evaluate community structure and diversity and assessed the relationships of these characteristics with production, export efficiency, and particulate organic carbon (POC) fluxes. Rates of productivity were relatively uniform along most of the transect with net community production (NCP) between 0 and 10 mmol O2 m-2 d-1, gross primary production (GPP) between 40 and 100 mmol O2 m-2 d-1, and NCP/GPP, a measure of export efficiency, ranging from 0.1 to 0.2 (0.05-0.1 in carbon units). However, notable exceptions to this basin-scale homogeneity included two locations with highly enhanced NCP and export efficiency compared to surrounding regions. Export of POC and particulate nitrogen, derived from sediment traps, correlated with GPP across the transect, over which the surface community was dominated numerically by picophytoplankton. NCP, however, did not correlate with POC flux; the mean difference between NCP and POC flux was similar to published estimates of dissolved organic carbon export from the surface ocean. The interrelated rates of production presented in this work contribute to the understanding, building on the framework of better-studied ocean basins, of how carbon is biologically transported between the atmosphere and the deep ocean.

  15. Biodiversity increases functional and compositional resistance, but decreases resilience in phytoplankton communities.

    Science.gov (United States)

    Baert, Jan M; De Laender, Frederik; Sabbe, Koen; Janssen, Colin R

    2016-12-01

    There is now ample evidence that biodiversity stabilizes aggregated ecosystem functions, such as primary production, in changing environments. In primary producer systems, this stabilizing effect is found to be driven by higher functional resistance (i.e., reduced changes in functions by environmental changes) rather than through higher functional resilience (i.e., rapid recovery following environmental changes) in more diverse systems. The stability of aggregated ecosystem functions directly depends on changes in species composition and by consequence their functional contributions to ecosystem functions. Still, it remains only theoretically explored how biodiversity can stabilize ecosystem functions by affecting compositional stability. Here, we demonstrate how biodiversity effects on compositional stability drive biodiversity effects on functional stability in diatom communities. In a microcosm experiment, we exposed 39 communities of five different levels of species richness (1, 2, 4, 6, and 8 species) to three concentrations of a chemical stressor (0, 25, and 250 μg/L atrazine) for four weeks, after which all communities were transferred to atrazine-free medium for three more weeks. Biodiversity simultaneously increased, increasing functional and compositional resistance, but decreased functional and compositional resilience. These results confirm the theoretically proposed link between biodiversity effects on functional and compositional stability in primary producer systems, and provide a mechanistic underpinning for observed biodiversity-stability relationships. Finally, we discuss how higher compositional stability can be expected to become increasingly important in stabilizing ecosystem functions under field conditions when multiple environmental stressors fluctuate simultaneously. © 2016 by the Ecological Society of America.

  16. Detection of Toxic Phytoplankton Species by Immunochemical Particle Analysis Based on Flow Cytometry

    NARCIS (Netherlands)

    Vrieling, Engel G.; Gieskes, Winfried W.C.; Zeijl, Wilhelmus J.M. van; Veenhuis, Marten

    1994-01-01

    Particulate suspended matter in oceanic, coastal, and estuarine regions can be specifically marked immunochemically with a fluorescent probe using antisera recognizing antigens present on their surface. Of the particulate matter, phytoplankton is a major component. Toxic species that may form

  17. Exploration of relationships between phytoplankton biomass and related environmental variables using multivariate statistic analysis in a eutrophic shallow lake: a 5-year study

    Institute of Scientific and Technical Information of China (English)

    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 spatial and temporal heterogeneity. To elucidate relationships between them in a eutrophic shallow lake, Taihu Lake, relative long-term data set of biotic and abiotic parameters of water quality in the lake were conducted using multivariate statistical analysis within seasonal periodicity. The results indicate that water temperature and total phosphorus (TP) played governing roles in phytoplankton dynamics in most seasons (i.e. temperature in winter, spring and summer; TP in spring, summer and autumn); COD (chemical oxygen demand) and BOD (biological oxygen demand) presented significant positive relationships with phytoplankton biomass in spring, summer and autumn. However, a complex interplay was found between phytoplankton biomass and nitrogen considering significant positive relationships occurring between them in spring and autumn, and conversely negative ones in summer. As the predatory factor, zooplankton presented significant grazing-pressure on phytoplankton biomass during summer in view of negative relationship between them in the season. Significant feedback effects of phytoplankton development were identified in summer and autumn in view that significant relationships were observed between phytoplankton biomass and pH, Trans (transparency of water) and DO. The results indicate that interactions between phytoplankton biomass and related environmental variables are highly sensitive to seasonal periodicity, which improves understanding of different roles of biotic and abiotic variables upon phytoplankton variability, and hence, advances management methods for eutrophic lakes.

  18. 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.

  19. Micro Flow Cytometry Miniaturisation - Towards in-situ Optical Phytoplankton Analysis

    Science.gov (United States)

    Zmijan, R.; Abi Kaed Bey, S.; Mowlem, M. C.; Morgan, H.

    2012-04-01

    The use of flow cytometry for studies of temporal and spatial variability of phytoplankton populations is a valuable tool contributing to research relating carbon biogeochemistry and climate change. Early designs and marine deployments of such devices started over two decades ago [1-3]. Miniaturisation and cost reduction without sacrificing performance remains a major challenge but would enable mass production and deployment. Large numbers of measurement nodes (e.g. as part of a global ocean observation system) would be possible which would increase data available over both spatial and temporal scales. This research presents two different design approaches for miniaturisation and integration of optics into a microfluidic cytometer chip. The proposed solutions are suitable for micro cytometers with external components coupled with optical fibres and were simulated and optimised using ray tracing software (Zemax). The two designs address light delivery for excitation of particles within the measurement region of the cytometer. One uses an integrated micro lens (fabricated in the chip) and the other a ball shaped micro lens manufactured separately and then inserted into the chip. Both approaches collimate the excitation light beam (from an off chip diode laser coupled with an optical fibre) into the fluidic channel. The predicted (by ray tracing) excitation beam widths are 70 and 80 µm for the integrated and the ball lens respectively, and are in agreement with experimental data presented. The proposed cytometer chip design is compatible with low cost materials (acrylic glass, cyclo-olefines) and manufacturing methods (micro milling, hot embossing, injection moulding). 1. Dubelaar, G.B.J. and P.L. Gerritzen, CytoBuoy: a step forward towards using flow cytometry in operational oceanography. Scientia Marina, 2000. 64(2): p. 255-265. 2. Peeters, J.C.H., et al., Optical Plankton Analyzer - a Flow Cytometer for Plankton Analysis .1. Design Considerations. Cytometry, 1989

  20. 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

  1. 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

  2. Spatio-temporal interdependence of bacteria and phytoplankton during a Baltic Sea spring bloom

    Directory of Open Access Journals (Sweden)

    Carina eBunse

    2016-04-01

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

  3. 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

  4. 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...

  5. 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。

  6. Noctiluca and copepods grazing on the phytoplankton community in a nutrient-enriched coastal environment along the southwest coast of India.

    Science.gov (United States)

    Arunpandi, N; Jyothibabu, R; Jagadeesan, L; Gireeshkumar, T R; Karnan, C; Naqvi, S W A

    2017-07-01

    The relative grazing impact of Noctiluca scintillans (hereafter referred only Noctiluca) and copepods (Acrocalanus gracilis, Paracalanus parvus, Acartia danae and Oithona similis) on the phytoplankton community in an upwelling-mudbank environment along the southwest coast India is presented here. This study was carried out during the Pre-Southwest Monsoon (April-May) to the Late Southwest Monsoon (August) period in 2014. During the sampling period, large hydrographical transformation was evident in the study area (off Alappuzha, Southwest coast of India); warmer Pre-Southwest Monsoon water column condition got transformed into cooler and nitrate-rich hypoxic waters during the Southwest Monsoon (June-August) due to intense coastal upwelling. Copepods were present in the study area throughout the sampling period with a noticeable increase in their abundance during the Southwest Monsoon. On the other hand, the first appearance of Noctiluca in the sampling location was during the Early Southwest Monsoon (mid-June) and thereafter their abundance increased towards the Peak Southwest Monsoon. The grazing experiments carried out as per the food removal method showed noticeable differences in the feeding preferences of Noctiluca and copepods, especially on the different size fractions of phytoplankton. Noctiluca showed the highest positive electivity for the phytoplankton micro-fraction (av. 0.49 ± 0.04), followed by nano-fraction (av. 0.17 ± 0.04) and a negative electivity for the pico-fraction (av. -0.66 ± 0.06). In total ingestion of Noctiluca, micro-fraction contribution (83.7%) was significantly higher compared to the nano- (15.7%) and pico-fractions (0.58%). On the other hand, copepods showed the highest positive electivity for the phytoplankton nano-fraction (av. 0.38 ± 0.04) followed by micro- (av. -0.17 ± 0.05) and pico-fractions (av. -0.35 ± 0.05). Similarly, in total ingestion of copepods, nano-fraction (69.7%) was the highest followed by micro

  7. 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

  8. 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.

  9. 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.

  10. High Performance Liquid Chromatographic Analysis of Phytoplankton Pigments Using a C16-Amide Column

    Science.gov (United States)

    A reverse-phase high performance liquid chromatographic (RP-HPLC) method was developed to analyze in a single run, most polar and non-polar chlorophylls and carotenoids from marine phytoplankton. The method is based on a RP-C16-Amide column and a ternary gradient system consistin...

  11. Detection of Toxic Phytoplankton Species by Immunochemical Particle Analysis Based on Flow Cytometry

    NARCIS (Netherlands)

    Vrieling, Engel G.; Gieskes, Winfried W.C.; Zeijl, Wilhelmus J.M. van; Veenhuis, Marten

    1994-01-01

    Particulate suspended matter in oceanic, coastal, and estuarine regions can be specifically marked immunochemically with a fluorescent probe using antisera recognizing antigens present on their surface. Of the particulate matter, phytoplankton is a major component. Toxic species that may form harmfu

  12. Stress and toxicity of biologically important transition metals (Co, Ni, Cu and Zn) on phytoplankton in a tropical freshwater system: An investigation with pigment analysis by HPLC

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, P.; Babu, P.V.R.; Acharyya, T.; Bandyopadhyay, D.

    followed by Zn, Co and Ni. Phytoplankton communities in Godavari River have different tolerance levels for different metals. Cu and Zn were found to be lethal at high concentration for both green algae and cyanobacteria. Cyanobacteria were found to be very...

  13. PHYTOPLANKTON OF CASPIAN

    Directory of Open Access Journals (Sweden)

    Aysha Sharapatinovna Gasanova

    2015-01-01

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

  14. 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.

  15. 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.

  16. 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.”

  17. 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.

  18. 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

  19. Dynamical analysis in a bioeconomic phytoplankton zooplankton system with double time delays and environmental stochasticity

    Science.gov (United States)

    Liu, Chao; Wang, Luping; Zhang, Qingling; Yan, Yun

    2017-09-01

    This paper presents a double delayed bioeconomic phytoplankton zooplankton system with commercial harvesting on zooplankton and environmental stochasticity. Maturation delay for toxin producing phytoplankton and gestation delay for zooplankton are considered. Environmental stochasticity is incorporated into the proposed system in form of Gaussian white noises. Some sufficient conditions are derived to show that the proposed system has a unique global positive solution. In absence of double time delays, stochastic stability and existence of stochastic Hopf bifurcation are studied based on invariant measure theory and singular boundary theory of diffusion process for the proposed system. In presence of double time delays, asymptotic behaviors of the interior equilibrium are discussed by constructing some appropriate Lyapunov functions.

  20. [Analysis of Phytoplankton in Tsimlyansk Reservoir (RUSSIA) for the Presence of Cyanobacterial Hepato- and Neurotoxins].

    Science.gov (United States)

    Sidelev, S I; Golokolenova, T B; Chernova, E N; Russkikh, I V

    2015-01-01

    Although the water bodies of southern Russia experience the most extreme effects of cyanobacterial blooms, molecular genetic data on the composition of toxigenic cyanobacteria in this region have been absent. Screening for the genes responsible for the synthesis of hepatotoxins (microcystins and cylindrospermopsin) and neurotoxins (anatoxin-a and saxitoxins) in cyanobacteria from the Tsimlyansk reservoir on the Don River was carried out. The presence of microcystin-producing Microcystis and Planktothrix populations, as well as of cyanobacteria capable of synthesis of a neurotoxin anatoxin-a was revealed by polymerase chain reaction (PCR). A hypothesis of the presence of anatoxin-a-producing Planktothrix rubescens population in the phytoplankton of the Tsimlyansk reservoir is proposed. The obtained PCR data were confirmed by the results of enzyme-linked immunosorbent assay (ELISA) and liquid chromatography/mass-spectrometry (LC/MS). Anatoxin-a and five microcystin variants were identified in the phytoplankton biomass.

  1. Phytoplankton pigments and epifluorescence microscopy as tools for ecological status assessment in coastal and estuarine waters, within the Water Framework Directive.

    Science.gov (United States)

    Seoane, Sergio; Garmendia, Maialen; Revilla, Marta; Borja, Angel; Franco, Javier; Orive, Emma; Valencia, Victoriano

    2011-07-01

    Inverted microscopy is widespread employed for the analysis of phytoplankton composition within water quality monitoring networks. However, the analysis at the lowest taxonomical level is not always required for ecological status assessment. In addition, inverted microscopy can underestimate the small phytoplankton, and not always distinguish photoautotrophic from heterotrophic cells. In this study, as alternative tools, epifluorescence microscopy and High Performance Liquid Chromatography (HPLC) were employed to characterize phytoplankton communities within waters of different trophic condition. Epifluorescence microscopy confirmed its effectiveness to count the small phytoplankton. Furthermore, significant correlations between nutrients of anthropogenic origin and nanoplankton abundances were found. However, this technique resulted very time-consuming. HPLC together with the CHEMTAX program was more appropriate than inverted microscopy, in terms of cost-effectiveness. Also, the main variability patterns observed in the phytoplankton community structure by HPLC coincided with previous findings in the study area. Nevertheless, a rapid screening at the inverted microscope is recommended.

  2. Variation of climatic and physical co-determinants of phytoplankton community in four nictemeral sampling days in a shallow tropical reservoir, Southeastern Brazil

    Directory of Open Access Journals (Sweden)

    J. J. RAMÍREZ

    Full Text Available Spatial and temporal variation of climatic and physical characteristics in a shallow tropical reservoir in the city of São Paulo, Southeastern Brazil, and their possible influence on the dynamics of the phytoplankton population. Samples were taken at 5 depths of the water column (subsurface: 1% Io, 10% Io, 2 m, and bottom and at 4 hour intervals (6:00, 10:00, 14:00, 18:00, 22:00, 2:00, and 6:00 h during summer (March 3-4, fall (June 13-14, winter (August 29-30, and spring (November 29-30 of 1994 at a single sampling station. Garças Reservoir (23º39'S, 46º37'W is a kinetic turbulent system, highly influenced by winds, with stratification that may last for days or weeks, and which undergoes mixing periods more than once in a year. A thermal pattern of this type is comparable to the warm discontinuous polymictic. Considering its optical properties, the water body was classified as an ecosystem with moderate turbidity, which decreases basically due to increased phaeopigment concentration during the spring. Also, the reservoir is an ecosystem whose phytoplanktonic community is subjected to stress, the degree of which depends on level of light penetration.

  3. 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.

  4. Environmental gradients regulate the spatio-temporal variability of phytoplankton assemblages in the Can Gio Mangrove Biosphere Reserve, Vietnam

    Science.gov (United States)

    Pham, Thanh-Luu

    2017-07-01

    This paper covers spatial and temporal variation in phytoplankton communities and physico-chemical variables in the Can Gio Mangrove Biosphere Reserve (CGMBR), Vietnam, based on field measurement conducted monthly at nine stations during February 2009 to January 2010. Species diversity, richness and phytoplankton abundance were calculated. Canonical Correspondence Analysis (CCA) was used to investigate the relationship between environmental factors and phytoplankton community. A total of 126 species were recorded with a clear dominance of Bacillariophyceae, which formed about 76.4% of the total phytoplankton counts with an annual average of 44.900 cells/L. Other algal classes like Dinophyceae, Cyanophyceae and Chrysophyceae sustained low counts, forming collectively about 14% of the total abundance of phytoplankton. Although Chaetoceros and Coscinodiscus were the most dominant genera, Schroederella and Skeletonema showed high abundance during the studied period. Among the nine environmental parameters tested in this study, salinity, nitrate and ammonium were found to be significantly different between two seasons. On the other hand, no significant difference was found between stations for the studied variables. Results of CCA indicated that phytoplankton assemblage in the CGMBR was influenced by salinity, nitrate and phosphate concentration. This is the first study simultaneously investigating the phytoplankton communities and their environment in this area and it is essential in order to set up the baseline of future studies.

  5. Physicochemical Flux and Phytoplankton diversity in Shagari ...

    African Journals Online (AJOL)

    USER

    2007-03-20

    Mar 20, 2007 ... environments for the development of phytoplankton communities, which may ... Gawon gulbe which originates partly from River Rima in the northern part of .... may not affect fish as reported by Ayodele and. Ajani (1999).

  6. Differences in Rate and Direction of Shifts between Phytoplankton Size Structure and Sea Surface Temperature

    Directory of Open Access Journals (Sweden)

    Hisatomo Waga

    2017-03-01

    Full Text Available Species distributions are changing with various rates and directions in response to recent global warming. The velocity of sea surface temperature (SST has been used to predict species migration and persistence as an expectation of how species track their thermal niches; however, several studies have found that evidence for species shifts has deviated from the velocity of SST. This study investigated whether estimation of the velocity of shifts in phytoplankton size structure using remote sensing data could contribute to better prediction of species shifts. A chlorophyll-a (Chla size distribution (CSD model was developed by quantifying the relationships between the size structure of the phytoplankton community and the spectral features of the phytoplankton absorption coefficient (aph(λ, based on the principal component analysis approach. Model validation demonstrated that the exponent of CSD (hereafter, CSD slope, which can describe the synoptic size structure of a phytoplankton community, was derived successfully with a relative root mean square error of 18.5%. The median velocity of CSD slope across the ocean was 485.2 km·decade−1, broadly similar to Chla (531.5 km·decade−1. These values were twice the velocity of SST, and the directions of shifts in CSD slope and Chla were quite different from that of SST. Because Chla is generally covariant with the size structure of a phytoplankton community, we believe that spatiotemporal changes in Chla can explain the variations of phytoplankton size structure. Obvious differences in both rate and direction of shifts were found between the phytoplankton size structure and SST, implying that shifts of phytoplankton size structure could be a powerful tool for assessing the distributional shifts of marine species. Our results will contribute to generate global and regional maps of expected species shifts in response to environmental forcing.

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

    DEFF Research Database (Denmark)

    Wang, Chao; Li, Xinhui; Wang, Xiangxiu;

    2016-01-01

    similarities. These groups were distinct with respect to species richness, biomass and indicators, especially for groups representing spatial dimension. The Linear Discriminant Analysis (LDA) model indicated that the spatial patterns of phytoplankton assemblages were mostly explained by water quality variables...... dominate? Are physical or chemical factors determining the above patterns in this area? We conclude that the spatial-temporal patterns of phytoplankton in the PRD are closely associated with eutrophication levels caused by anthropogenic activities. The spatial patterns are apparently dominant in this area......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...

  8. Improved monitoring of phytoplankton bloom dynamics in a Norwegian fjord by integrating satellite data, pigment analysis, and Ferrybox data with a coastal observation network

    Science.gov (United States)

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

    2011-01-01

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

  9. 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

  10. Numerical analysis of cumulative impact of phytoplankton photoresponses to light variation on carbon assimilation.

    Science.gov (United States)

    Esposito, S; Botte, V; Iudicone, D; d'Alcala', M Ribera

    2009-12-07

    Light variation in temporal and spatial domains is a key constraint on the photosynthetic performance of phytoplankton. The most obvious responses are the modification of cell pigment content either to improve photocapture or to mitigate photo-damage. Very few studies have analyzed whether light variation significantly alters carbon assimilation, especially in a fluctuating light environment as in the mixed layer of the ocean. We addressed the question using a modeling approach, which allows the reproduction of most of the possible scenarios, obtained with great difficulty from laboratory or field experiments. The complete model is based on the dynamic coupling of a photoacclimation and photodamage-repair responses. In this combined model the virtual phytoplankton is exposed to different light regimes (steady, square wave, sinusoidal light-dark cycles and fluctuating regimes). The results reconcile controversial results on different photoacclimation states achieved during fluctuating light regimes. The model produces a depression of carbon assimilation in any light fluctuating scenario, as compared to steady light regimes, due to the temporal delay between light fluctuations and photoresponses. These results suggest the possibility of selective pressure during evolution, more effective on photoprotective mechanisms than on optimization of light harvesting.

  11. 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

  12. The Relationship between Phytoplankton Distribution and Water Column Characteristics in North West European Shelf Sea Waters

    Science.gov (United States)

    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

  13. 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

  14. 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。

  15. MODIS observed phytoplankton dynamics in the Taiwan Strait: an absorption-based analysis

    Directory of Open Access Journals (Sweden)

    S. Shang

    2010-10-01

    Full Text Available This study uses MODIS observed phytoplankton absorption coefficient (aph as a preferable index of pigmentation to characterize phytoplankton variability in optically complex waters. We chose a quasi-analytical bio-optical inversion algorithm (QAA to derive aph from remote sensing reflectance (Rrs, both in situ and MODIS measured and then evaluated the Rrs derived aph by comparing them with match-up in situ measured aph collected in both oceanic and very nearshore waters in the Taiwan Strait (TWS. For the data with matching spatial and temporal window, it is found that the average percentage error (ε between MODIS Rrs derived aph at 443 nm (aph(443, abbreviated as Aph and field measured Aph is 33.8% (N = 30, Aph ranges from 0.012–0.537 m−1, with a root mean square error in log scale (RMSE of 0.226. By comparison, ε is 28.0% (N = 88, RMSE = 0.150 between ship-borne Rrs derived Aph and field measured Aph. Values of ε as large as 135.6% (N = 30, RMSE = 0.383 are found between MODIS Rrs derived chlorophyll-a (chl-a, OC3M algorithm and field measured chl-a. Based on these evaluation results, we applied QAA to MODIS Rrs data between 2003–2009 to derive climatological monthly mean Aph for the TWS. Three distinct features of phytoplankton dynamics are identified. First, Aph is low and the least variable in the Penghu Channel, where the South China Sea water enters the TWS. This region maintains slightly higher values in winter (~17% higher than that in the other seasons due to surface nutrient entrainment under winter wind-driven vertical mixing. Second, Aph is high and the most variable in the mainland nearshore water, with

  16. 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.

  17. Wakefield: Community and Library Analysis.

    Science.gov (United States)

    Trumpeter, Margo C.; Donahue, Mary Ellen

    This community analysis was conducted in order to characterize and identify the information needs of the Wakefield community, and library services and use were evaluated to determine how well the library meets these needs. The study included an examination of the history of the town and its physical characteristics, economic development, and…

  18. 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.

  19. 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

  20. 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.

  1. Identification of non-indigenous phytoplankton species dominated bloom off Goa using inverted microscopy and pigment (HPLC) analysis

    Digital Repository Service at National Institute of Oceanography (India)

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

    An unusual phytoplankton bloom dominated by unidentified green coloured spherical algal cells (approx 5 mu m diameter) and dinoflagellates (Heterocapsa, Scripsiella and Gymnodinium) was encountered along the coast of Goa, India during 27 and 29...

  2. Phytoplankton composition and biomass across the southern Indian Ocean

    DEFF Research Database (Denmark)

    Schlüter, Louise; Henriksen, Peter; Nielsen, Torkel Gissel

    2011-01-01

    Phytoplankton composition and biomass was investigated across the southern Indian Ocean. Phytoplankton composition was determined from pigment analysis with subsequent calculations of group contributions to total chlorophyll a (Chl a) using CHEMTAX and, in addition, by examination in the microscope....... The different plankton communities detected reflected the different water masses along a transect from Cape Town, South Africa, to Broome, Australia. The first station was influenced by the Agulhas Current with a very deep mixed surface layer. Based on pigment analysis this station was dominated by haptophytes......, pelagophytes, cyanobacteria, and prasinophytes. Sub-Antarctic waters of the Southern Ocean were encountered at the next station, where new nutrients were intruded to the surface layer and the total Chl a concentration reached high concentrations of 1.7 μg Chl a L−1 with increased proportions of diatoms...

  3. Growth response of natural phytoplankton to enrichment of urea and ...

    African Journals Online (AJOL)

    user

    community in the Neuse River estuary showed preference for ... 2) Over what time frame do phytoplankton taxa respond to nutrient .... different dissolved N forms did not show any significant ..... Can plankton communities be considered as.

  4. Ecological provinces of spring phytoplankton in the Yellow Sea:species composition

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shan; LENG Xiaoyun; FENG Yuanyuan; DING Changlin; YANG Yang; WANG Jing; WANG Houjie; SUN Jun

    2016-01-01

    Phytoplanktonic ecological provinces of the Yellow Sea (31.20°–39.23°N, 121.00°–125.16°E) is derived in terms of species composition and hydrological factors (temperature and salinity). 173 samples were collected from 40 stations from April 28 to May 18, 2014, and a total of 185 phytoplanktonic algal species belonging to 81 genera of 7 phyla were identified by Utermöhl method. Phytoplankton abundance in surface waters is concentrated in the west coast of Korean Peninsula and Korea Bay, and communities in those areas are mainly composed of diatoms and cyanobacteria with dominant species ofCylindrotheca closterium,Synechocystis pevalekii,Chroomonas acuta, Paralia sulcata,Thalassiosira pacifica andKarenia mikimotoi, etc. The first ten dominant species of the investigation area are analyzed by multidimensional scaling (MDS) and cluster analysis, then the Yellow Sea is divided into five provinces from Province I (P-I) to Province V (P-V). P-I includes the coastal areas near southern Liaodong Peninsula, with phytoplankton abundance of 35 420×103–36 163×103 cells/L and an average of 35 791×103 cells/L, and 99.84% of biomass is contributed by cyanobacteria. P-II is from Shandong Peninsula to Subei coastal area. Phytoplankton abundance is in a range of 2×103–48×103 cells/L with an average of 24×103 cells/L, and 63.69% of biomass is contributed by diatoms. P-III represents the Changjiang (Yangtze River) Diluted Water. Phytoplankton abundance is 10×103–37×103 cells/L with an average of 24×103 cells/L, and 73.14% of biomass is contributed by diatoms. P-IV represents the area affected by the Yellow Sea Warm Current. Phytoplankton abundance ranges from 6×103 to 82×103 cells/L with an average of 28×103 cells/L, and 64.17% of biomass is contributed by diatoms. P-V represents the cold water mass of northern Yellow Sea. Phytoplankton abundance is in a range of 41×103–8 912×103 cells/L with an average of 1 763×103 cells/L, and 89.96% of biomass is

  5. Bacterial production, primary production, phytoplankton, zooplankton, biological analysis of fish, and massive fish length data from the EVRIKA and other platforms in the Antarctic from 23 February 1980 to 09 December 1988 (NODC Accession 9600039)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Bacterial production, primary production, phytoplankton, zooplankton, biological analysis of fish, and massive fish length data were collected from the EVRIKA and...

  6. Assessing spatial and temporal variability of phytoplankton communities' composition in the Iroise Sea ecosystem (Brittany, France): A 3D modeling approach. Part 2: Linking summer mesoscale distribution of phenotypic diversity to hydrodynamism

    Science.gov (United States)

    Cadier, Mathilde; Sourisseau, Marc; Gorgues, Thomas; Edwards, Christopher A.; Memery, Laurent

    2017-05-01

    Tidal front ecosystems are especially dynamic environments usually characterized by high phytoplankton biomass and high primary production. However, the description of functional microbial diversity occurring in these regions remains only partially documented. In this article, we use a numerical model, simulating a large number of phytoplankton phenotypes to explore the three-dimensional spatial patterns of phytoplankton abundance and diversity in the Iroise Sea (western Brittany). Our results suggest that, in boreal summer, a seasonally marked tidal front shapes the phytoplankton species richness. A diversity maximum is found in the surface mixed layer located slightly west of the tidal front (i.e., not strictly co-localized with high biomass concentrations) which separates tidally mixed from stratified waters. Differences in phenotypic composition between sub-regions with distinct hydrodynamic regimes (defined by vertical mixing, nutrients gradients and light penetration) are discussed. Local growth and/or physical transport of phytoplankton phenotypes are shown to explain our simulated diversity distribution. We find that a large fraction (64%) of phenotypes present during the considered period of September are ubiquitous, found in the frontal area and on both sides of the front (i.e., over the full simulated domain). The frontal area does not exhibit significant differences between its community composition and that of either the well-mixed region or an offshore Deep Chlorophyll Maximum (DCM). Only three phenotypes (out of 77) specifically grow locally and are found at substantial concentration only in the surface diversity maximum. Thus, this diversity maximum is composed of a combination of ubiquitous phenotypes with specific picoplankton deriving from offshore, stratified waters (including specific phenotypes from both the surface and the DCM) and imported through physical transport, completed by a few local phenotypes. These results are discussed in light

  7. 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.

  8. Identification of non-indigenous phytoplankton species dominated bloom off Goa using inverted microscopy and pigment (HPLC) analysis

    Indian Academy of Sciences (India)

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

    2011-12-01

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

  9. Multivariate statistical analysis of water quality and phytoplankton characteristics in Daya Bay, China, from 1999 to 2002

    Directory of Open Access Journals (Sweden)

    You-Shao Wang

    2006-06-01

    Full Text Available This study analyzed seasonal physicochemical and phytoplanktondata collected at 12 marine monitoring stations in Daya Bay from1999 to 2002. Cluster analysis based on water quality and phytoplanktonparameters measured at the 12 stations could be grouped intothree clusters: cluster I - stations S1, S2, S7 and S11 in thesouthern part and the north-eastern part of Daya Bay; clusterII - stations S5, S6, S9, S10 and S12 in the central and north-easternparts of Daya Bay; cluster III - stations S3, S4 and S8 in the cageculture areas in the south-western part of Daya Bay and in thenorth-western part of the Bay near Aotou harbor. Bivariate correlationsbetween phytoplankton density and the major physical and nutrientfactors were calculated for all stations. Factor analysis showsthat there were high positive loadings of pH, TIN and the ratioof TIN to PO4-P in the three clusters, which indicates thatall the stations in the three clusters were primarily groupedaccording to their respective nutrient conditions.

  10. Availability of iron for phytoplankton growth in the north-east Atlantic

    Science.gov (United States)

    Blain, S.; Guieu, C.; Claustre, H.; Leblanc, K.; Moutin, T.; Quéguiner, B.; Sarthou, G.

    2003-04-01

    We present results from a cruise (February March 2001, Programme Océanographique Multi disciplinaire Meso-echelle POMME) in the north east Atlantic between Azore and Portugal (39N--44N, 17--21W). The studied area was characterised by high mesoscale activities. The availability of iron for phytoplankton was studied using deck incubation experiments. On a qualitative point of view, experiments demonstrated that dissolved iron concentration was limiting the primary production in spring. For diatoms a simultaneous limitation by silicic acid has been also observed. The availability of iron has been manipulated using desferral ligand (DFOB). Addition of DFOB clearly reduced the growth of the phytoplankton community showing that a large part of the ambient iron was bioavailable. However our results confirm also previous works showing that a small growth of the phytoplankton community is possible even if DFOB is added. Based on pigment analysis we determined the half saturation constant for different phytoplankton groups. Estimated values were 0.2 nM for micro- and nano-phytoplankton and and much lower for picoplankton.

  11. 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

  12. Optimization of crude enzyme preparation methods for analysis of glutamine synthetase activity in phytoplankton and field samples

    Institute of Scientific and Technical Information of China (English)

    WANG Yujue; WANG Dazhi; HONG Huasheng

    2009-01-01

    Glutamine synthetase (GS) is an important enzyme involved in nitrogen assimilation and metabolism in marine phytoplankton. However, little work has been done in situ due to the limitation of crude enzyme preparation methods. In this study, three enzyme preparation methods, high-speed centrifugation (HC, <10 000 g), ultracentrifugation (UC, 70 000 g), and ultrafiltration (UF) with 100 kμ, molecular weight cutoff, were compared using two diatom species (Asterionellopsis glacialis and Thalassiosira weissflogii), and two dinoflagellate species (Alexandrium catenella and Prorocentrum donghaiense) as experimental materials together with field samples collected from Xiamen Harbor, China. The results showed that HC is the best method to prepare crude enzymes for glutamine synthetase activity (GSA) in diatom species and diatom-dominant samples, while UF is the best method to extract GS from dinoflagellate species and dinoflagellate-dominant samples. For the HC method, the optimal centrifugal speed and time were 10 000 g and 35 min, respectively, and under these conditions, the highest GSA was obtained in all samples. This study indicates that both methods (HC and UF) overcome the limitation of centrifugal speed and could be applied to in situ GSA analysis, especially at sea.

  13. Constraining the variability of optical properties in the Santa Barbara Channel, CA: A phytoplankton story

    Science.gov (United States)

    Barron, Rebecca Katherine

    The research presented in this dissertation evaluates the direct relationships of phytoplankton community composition and inherent optical properties (IOP); that is, the absorption and scattering of light in the ocean. Phytoplankton community composition affect IOPs in both direct and indirect ways, thus creating challenges for optical measurements of biological and biogeochemical properties in aquatic systems. Studies were performed in the Santa Barbara Channel (SBC), CA where an array of optical and biogeochemical measurements were made. Phytoplankton community structure was characterized by an empirical orthogonal functional analysis (EOF) using phytoplankton accessory pigments. The results showed that phytoplankton community significantly correlated to all IOPs, e.g. phytoplankton specific absorption, detrital absorption, CDOM absorption and particle backscattering coefficients. Furthermore, the EOF analysis was unique in splitting the microphytoplankton size class into separate diatom and dinoflagellate regimes allowing for assessment optical property differences within the same size class, a technique previously not systematically achievable. The phytoplankton functional group dinoflagellates were particularly influential to IOPs in surprising ways. Dinoflagellates showed higher backscattering efficiencies than would be predicted based on Mie theory, and significantly influenced CDOM absorption via direct association with dissolved mycosproine-like amino acid absorption (MAA) peaks in CDOM spectra. A new index was developed in this work to quantify MAA absorption peaks in CDOM spectra, and was named the MAA Index. Prior to this research dissolved MAA absorption in natural waters was never quantified, and CDOM data containing these peaks were often disregarded and discarded from analysis. CDOM dynamics in the SBC were assessed for a 15-year study period, and this work shows that significantly large MAA Index values, e.g. MAA Index > 1, were present in

  14. Phytoplankton taxonomy based on CHEMTAX and microscopy in the northwestern Black Sea

    Science.gov (United States)

    Eker-Develi, Elif; Berthon, Jean-François; Canuti, Elisabetta; Slabakova, Natalya; Moncheva, Snejana; Shtereva, Galina; Dzhurova, Boryana

    2012-06-01

    Abundance and carbon biomass of different phytoplankton groups obtained by microscopy were compared with taxonomy derived from pigment measurements and CHEMTAX analysis of samples collected in June 2006 in the NW Black Sea. The diatom Chaetoceros curvisetus was dominant in terms of carbon biomass based on cell volume at inshore stations, while the coccolithophore Emiliania huxleyi was prevalent at offshore. Emiliania huxleyi reached bloom abundance of 3.3 × 106 cells L- 1. The chlorophyll a (chl a) concentration within phytoplankton groups as allocated by CHEMTAX was in agreement with microscopy derived carbon biomasses of the taxonomic groups diatoms, dinoflagellates and cryptophytes only. Carbon biomass of less abundant phytoplankton taxa (cyanophytes, euglenophytes and chlorophytes) did not correlate with group-specific chl a. It was not possible to detect E. huxleyi bloom by CHEMTAX analysis probably due to much higher biomass of other species containing 19'-hexanoyloxyfucoxanthin. Nutrient concentrations were generally high in the waters where diatom and dinoflagellates dominated the community but low in the area of E. huxleyi bloom. A good correlation between total carbon biomass of phytoplankton and chl a was found and the estimated C:chl a ratio of phytoplankton varied between 36 and 256 (in average 124 ± 50).

  15. 杭州地区17座水库浮游植物群落组成及其与环境因子的关系%Phytoplankton Communities and Their Relationship with Environmental Factors in 1 7 Medium and Large Reservoirs in Hangzhou

    Institute of Scientific and Technical Information of China (English)

    盛海燕; 姚佳玫; 刘明亮; 何剑波; 韩轶才; 虞左明; 张银龙

    2015-01-01

    The reservoir has gradually taken on the role of drinking water supply instead of flood control,irrigation and power generation for the serious water pollution of rivers and lakes.The deterioration of water quality in the Qiantang River and the Tiaoxi River in Hongzhou area threatens the drinking water supply in the region.Decision-making departments consider reservoir water as a feasible and safe water resource of water supply for this area.Sev-enteen reservoirs along the Qiantang River and the Tiaoxi River were selected according to the distribution of water resources in Hangzhou.Our study investigated the phytoplankton community of the 17 medium and large reservoirs, analyzed the relationship between phytoplankton and nutrient status of the water body and provided basic informa-tion and data for water resources protection and drinking water safety.The phytoplankton samples were selected during flood season (August)and dry season (December)in 2008 and 2009 .Qualitative phytoplankton samples were taken with 25 μm plankton nets from different directions and at different depth.1 L samples for quantitative a-nalysis were collected 0.5 m below the surface,then concentrated and identified after settling.Physical and chemi-cal factors were measured including the water temperature (WT),water transparence (SD),pH,dissolved oxygen (DO),chemical oxygen demand (CODMn),total nitrogen (TN),ammonia nitrogen (NH3-N),total phosphorus (TP),soluble phosphorus (DP)and soluble silica (DSi).Chlorophyll a was determined by spectrophotometry.A total of 85 species of phytoplankton in 7 phyla were collected and the species were dominated by Chlorophyta (29 ), followed by Bacillariophyta (26),Cyanophyta (15),Euglenophyta (6),Cryptophyta(3),Pyrrophyta (3)and Chrysophyta (3).Phytoplankton density averaged 1.27 ×106 -6.55 ×106 cells/L and was the highest in summer (12.2 ×106 cells/L)and the lowest in winter (0.168 ×106 cells/L).Annual average chlorophyll a concentration varied between 2

  16. 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

  17. Structure and temporal variation of the phytoplankton of a macrotidal beach from the Amazon coastal zone

    Directory of Open Access Journals (Sweden)

    JISLENE B. MATOS

    Full Text Available ABSTRACT The present study aimed to analyze the structure and the temporal variation of the phytoplankton of Ajuruteua beach (Bragança, Pará and to investigate the influence of environmental variables on the dynamics of this community to provide a basis about the trophic state of this environment. Biological, hydrological and hydrodynamic samplings were performed during a nyctemeral cycle in the months of November/08, March/09, June/09 and September/09. We identified 110 taxa, which were distributed among the diatoms (87.3%, dinoflagellates (11.8% and cyanobacteria (0.9%, with the predominance of neritic species, followed by the tychoplankton species. Chlorophyll-a concentrations were the highest during the rainy period (24.5 mg m-3, whereas total phytoplankton density was higher in the dry period (1,255 x 103 cell L-1. However, phytoflagellates density was significantly higher during the rainy period. Cluster Analysis revealed the formation of four groups, which were influenced by the monthly differences in the environmental variables. The Principal Component Analysis indicated salinity and chlorophyll-a as the main variables that explained the components. Spearman correlation analysis supported the influence of these variables on the local phytoplankton community. Overall, the results obtained suggest that rainfall and strong local hydrodynamics play an important role in the dynamic of the phytoplankton of Ajuruteua beach, by influencing both environmental and biological variables.

  18. 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.

  19. Environmental drivers of phytoplankton distribution and composition in Tagus Estuary, Portugal

    Science.gov (United States)

    Gameiro, C.; Cartaxana, P.; Brotas, V.

    2007-10-01

    A 7-year (March 1999-November 2005) monitoring program was developed in the Tagus estuary to study phytoplankton dynamics and several key controlling factors, namely nutrient content, light availability, atmospheric and hydrodynamic conditions (temperature, wind, rainfall, river flow, and salinity). Water was collected at four sampling sites on a monthly basis. Phytoplankton biomass, analyzed as Chl a, was moderate to low, when compared to other mesotidal estuaries: interannual average Chl a values ranged from 1.4 in winter to 8.0 μg L -1 in summer. A consistent seasonal pattern was observed, with a unimodal peak extending from late spring to summer. The phytoplankton community, as determined by biomarker pigment concentration using HPLC and CHEMTAX, was dominated by diatoms (57%), and included cryptophytes (23%), dinoflagellates (6.8%), chlorophytes (5.4%), euglenophytes (4.9%), and prasinophytes (2.6%). The method was capable of detecting phytoplankton taxa generally underestimated or overlooked when using standard microscopic techniques. Diatoms were the main bloom-formers in the summer Chl a maximum. A stepwise regression analysis showed that air temperature, river flow and irradiance explained 47% of the observed Chl a variance, illustrating the importance of climatic factors as driving forces for seasonal and interannual variability of phytoplankton.

  20. Spatial distribution of phytoplankton in the Gulf of Riga during spring and summer stages

    Science.gov (United States)

    Seppälä, J.; Balode, M.

    1999-12-01

    Distribution patterns of chlorophyll a, phytoplankton species and biomass were studied in the Gulf of Riga, one of the most eutrophicated areas of the Baltic Sea. Quasi-synoptic measurements were carried out during four seasonal stages (spring bloom 1995, early-summer stage 1994, cyanobacterial bloom 1994, and late summer stage 1993). For each stage, common factor analysis was used to simplify the highly correlated patterns of nutrients, salinity, temperature and the depth of mixed layer. Obtained latent variables were used to explain spatial distribution of phytoplankton. Generally, the distribution of phytoplankton variables followed closely the patterns of nutrient rich fresh water. During the spring bloom in 1995, the spatial structures of phytoplankton biomass (4-27 mg l -1) and chlorophyll a (13-50 μg l -1) were well explained ( r=0.68 and 0.69, respectively, pAphanizomenon flos-aquae (L.) Ralfs) took place in 1994 after warming up of the surface layer. The abundance of A. flos-aquae was related to the common structure of N, P and fresh water and the bloom was most dense (up to 6.6 mg l -1) in the southern Gulf. At the same time, the contribution of picoplankton from total chlorophyll a was high (up to 60%) in the northern Gulf affected less by the nutrient load. The late summer phase in 1993 was characterized by high heterotrophic activities and the phytoplankton community was dominated by cryptomonads (on the average 50% of total biomass). At that stage the distribution of phytoplankton was obviously governed by biological interactions and the multivariate methods were not especially successful to explain the spatial distribution of the main components of phytoplankton community. Excluding the late summer phase, the statistical methods used in this study revealed well the relationships between phytoplankton variables and nutrient rich fresh water. It is evident that nutrient load from the River Daugava is a reason for higher phytoplankton biomass in the

  1. 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

    early autumn. As a result,this area has been targeted for monitoring by the Water Environment Management Department and Three Gorges Reservoir Management Department.To study the effect of rapid water level fluctuations in Three Gor-ges Reservoir,the phytoplankton community of Xiaojiang River was investigated in June and October of 2013. Three sampling sites were established in the Gaoyang section,where algae blooms frequently occur,and located in the middle and on each side of the tributary bay.Samples from the upper,middle and lower layers were collected for quantitative and qualitative phytoplankton analysis on June 1,8,15,22 and 29 during the discharge period of Three Gorges Reservoir,and on Oct.4,11,18 and 25 during the impoundment period.Water quality parameters were measured when phytoplankton samples were collected.A total of 136 phytoplankton species (including varie-ties)belonging to 70 genera and 6 phyla (during the discharge period)and 7 phyla (during the impoundment peri-od)were identified in Xiaojiang River.Phytoplankton species were dominated by Chlorophyta,Bacillariophyta and Cyanophyta,together accounting for 87.49% (discharge)and 80.87% (impoundment)of the total phytoplankton species,and displayed little difference in species composition between the two periods.The phytoplankton density range was 8.1 ×104 cells/L -127.2 ×104 cells/L during the discharge period and 24.4 ×104 cells/L -99.9 × 104 cells/L during the impoundment period,slightly lower and with less variation than during the discharge period. Cell density increased significantly with time during the discharge period,while it gradually decreased with time during the impoundment period.Phytoplankton density was dominated by diatoms during discharge period and by cyanobacteria during the impoundment period (>50% in each case).Both the Shannon index range (1.80 -3.68)and Margalef index range (0.09 -0.61)during the impoundment period were significantly higher,and lar-ger,than the range during

  2. 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.

  3. 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.

  4. 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

    With the development of intensive aquaculture and high-density breeding,the excessive input of forage leads to the deterioration of pond water quality and disease outbreaks occur frequently in the cultured animals. Meanwhile,aquacultural wastewater was being discharged directly into the aquatic environment without treatment. A new,more ecological,culturing method,the integrated pond aquaculture-constructed wetland system,improves the quality of the products while conserving water resources and effectively treating the aquacultural wastewater.In this research,a modern integrated system was studied,consisting of a constructed wetland (0.045 hm2 )and a cul-ture pond (0.33 hm2 ).In the system,Megalobrama amblycephala fingerlings (33 000 ind /hm2 )with a small number of Hypophthalmichthys molitrix(3 750 ind/hm2 ),Aristichthy nobilis (900 ind /hm2 ),Carassius auratus gibelio (3 750 ind /hm2 )and Ctenopharyngodon idellus (150 ind /hm2 )were mix-cultured in the pond.The wastewater was filtered and purified through the constructed wetland and recirculated back to the pond.The finger-lings were fed on an artificial diet four times daily.The constructed wetland began operation in July,2014 and the wetland plants were harvested in December.From August to November 2014,we investigated the community struc-ture of phytoplankton in the pond when the constructed wetland was fully functioning.The relationship between phytoplankton community structure and water quality parameters was analyzed by redundancy analysis (RDA). Three sample sites were selected in the culture pond and the water samples were collected near the end of each month for determination of water physicochemical parameters including T,pH,DO,TN,TP,NH3-N and NO -2 -N. Phytoplankton samples for qualitative analysis were collected with a No.25 plankton net.1 L water samples for quantitative phytoplankton analysis were collected at 0.5 m below the surface using a glass water sampler and 15 mL Lugol′s solution was added

  5. 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.

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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...

  11. Phytoplankton Ecology and Hydrological Dynamics of the Yahuarcaca Lake System, Amazonas, Colombia: Integrated Analysis of 16 Years of Study

    Directory of Open Access Journals (Sweden)

    Maria Juliana Salcedo-Hernández

    2012-09-01

    Full Text Available This article provides a synthesis of the current knowledge on the evolving relation between the Amazon River and the Yahuarcaca lagoon system, through the limnological features and the ecology of phytoplankton in a period of sixteen years. The synthesis of the information was conducted by reviewing existing data about the system, for the time indicated, and analyzing it by means of descriptive statistics and linear correlation between the variables found. Also, it contains a summary of the most important aspects of the first attempt in Colombia to evaluate the influence of the flood pulse on the phytoplankton in a daily time scale. The thermal pattern of this laggon system corresponds to a warm and constant polymicthic lake type according to the de Lewis (1983 classification. The physical, chemical and biological variables examined in this várzea system change according to the hydrologic period. The conductivity, transparency and richness of the phytoplankton increase in the low water season, while the nutrient concentration, and the density, productivity and the biomass of phytoplankton increase during the high water season. Nitrate during the low water season and phosphate during the high water season are the most restricting nutrients. The changes that have taken place through these years in the connectivity between the river and the Yahuarcaca lagoon system are reflected in the dynamics of the structure and composition of the phytoplankton. Normal 0 21 false false false ES-CO X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabla normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-bidi-font-family:"Times New Roman"; mso-ansi-language:ES-CO; mso-fareast-language:ES-CO;}

  12. 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.

  13. Phytoplankton diversity in the Parangipettai coastal waters, southeast coast of India.

    Science.gov (United States)

    Rajkumar, M; Rajasekar, K Thillai; Sun, Jun; Jenkinson, I R; Prabu, V Ashok; Perumal, P

    2012-11-01

    An investigation was carried out during June 2005 to May 2007 on hydrography, composition and community structure of phytoplankton including chlorophyll a in Parangipettai coastal waters (southeast coast of India). Air and surface water temperatures varied from 25.5 to 31.2 degrees C and from 25 to 29.3 degrees C, respectively. Salinity values varied from 5 to 33.1 per thousand and the pH ranged between 7.2 and 8.3. Dissolved oxygen content varied from 3.1 to 7.9 mg l(-1) while the light extinction coefficient values (LEC) ranged between 1.8 and 11.0 cm. The range of inorganic nutrients viz., nitrate, nitrite, phosphate and silicate were: 6.5 - 27.0 microM; 1.0 - 8.9 microM; 0.1 - 3.0 microM and 15.0 - 140 microM, respectively. The range of chlorophyll a was: 2.0 - 7.5 microg l(-1). Presently, 117 phytoplankton species representing different classes viz: Bacillariophyceae (66); Dinophyceae (22); Cyanophyceae (19); Chlorophyceae (7) and Chrysophyceae (3) were recorded. The phytoplankton cell abundance varied from 0.14 to 132 cells ml(-1), with peak diversity (3.52 bits ind.(-1)) during summer season. The maximum abundance was found during summer season coinciding with the stable hydrographical conditions. Canonical Correspondence Analysis was applied in this study for discriminating environmental factors effecting on phytoplankton community at species level.

  14. 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.

  15. 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.

  16. 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

  17. Phytoplankton Community Structure and Diversity Assessment in the Upper Reach of the Yellow River during Spring and Autumn%黄河上游龙羊峡至积石峡段春秋季浮游植物群落结构及多样性评价

    Institute of Scientific and Technical Information of China (English)

    陈燕琴; 申志新; 刘玉婷

    2014-01-01

    conducted at ten sample sites in March (spring)and August (autumn)of 2013.Results shed light on the phytoplankton community struc-ture in the upper Yellow River and provide data to evaluate the aquatic environment and support efforts to use Yellow River water resources sustainably in Qinghai Province.Phytoplankton and water samples for qualitative and quantitative analysis were collected from the water surface (<50 cm).The geographical coordinates,height above sea level,water temperature and pH of each sample site were measured at the same time.Dissolved oxygen (DO) was determined by the iodine method (GB 7489-87)within 24 h.A total of 7 phyla,including 64 species of phyto-plankton,were observed.Bacillariophyta was the dominant phylum,including 25 species (genera)and accounting for 39.1% of the total phytoplankton species,followed by Chlorophyta [19 species (genera),29.7%],Cyano-phyta [12 species (genera),18.8%],Chrysophyta and Pyrrophyta[3 species (genera),4.6%],Euglenophyta and Cryptophyta [1 species (genera),1 .6%].The most commonly encountered species were Cyclotella sp.,Di-atoma vulgare,Asterionella sp.,Fragilaria sp.,Synedra sp.,Synedra acus,Achnanthes sp.,Phormidium sp., Merismopedia sp.,Dinobryon sp.,Chlamydomona sp.,Chlorella sp.,and Pandorina sp.The seven most common species of Bacillariophyta accounted for 53.8% of the 13 dominant species.Seasonal variation of phytoplankton composition was obvious,with higher species richness in autumn,but Bacillariophyta was dominant in both sea-sons.The phytoplankton density ranged from 1.27 ×104 cell/L to 180.48 ×104 cell/L,with an average of 25.33 ×104 cell/L,and the phytoplankton biomass ranged from 0.0049 mg/L to 0.4293 mg/L,with an average of 0.0732 mg/L.The density and biomass of Bacillariophyta accounted for 70.7% and 77.9% of the total phyto-plankton community.The phytoplankton biomass was larger in autumn than in spring.The mean Shannon-Wiener diversity index,Pielou evenness index and Margalef richness index were 2

  18. Multivariate Analysis of Phytoplankton Communities in 37 Danish Lakes Studied During 12 Years

    DEFF Research Database (Denmark)

    Jensen, J. P.; Jeppesen, E.; Bjerring, Rikke

    Organised by Balaton Limnological Research Institute of the Hungarian Academy of Science, Tihany, and Institute of Biology, university of Veszprém......Organised by Balaton Limnological Research Institute of the Hungarian Academy of Science, Tihany, and Institute of Biology, university of Veszprém...

  19. 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.

  20. 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.

  1. 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

    于2006年11月至2007年7月按季度对乌伦古湖浮游植物进行了取样调查,共发现浮游藻类164种(包括若干未定名种),隶属于8门90属,其中Anabaena bergii为新疆新记录种,两种硅藻Chaetocerns sp.和Thalassionema sp.属于海产种类.各季种类组成均以绿藻门和硅藻门为主,蓝藻门和裸藻门次之,甲藻门、金藻门、黄藻门、隐藻门种类均比较少.秋季种类最多,有141种;其次是夏季和春季,分别为128种和121种;冬季种类最少,仅有95种.中华小尖头藻、微小四角藻、小形月牙藻、小球藻及尖针杆藻为全年可见优势种;肘状针杆藻在春季、夏季和秋季构成优势种群;扭曲蹄形藻和椭圆小球藻仅在夏季构成优势种群,而水溪绿球藻和粗刺四棘藻仅在冬季构成优势种群.藻类生物量周年变动模式为单峰型,生物量的峰值出现在夏季(6.77mg/L).最低值出现在冬季(1.45mg/L).结合历史资料分析发现,30年来,乌伦古湖浮游藻类不仅在种类组成上发生了明显的变化,在数量上也显著着一定的增长,并以绿藻和硅藻类群的增长最为显著.%The phytoplankton of Lake Uhmgur was investigated seasonally from November, 2006 to July, 2007. A total of 164 phytoplankton species (including a number of unconfirmed species) was detected, which belonged to 90 genera, 8 phylum. Among them, Anabaena bergii was a new record species of cyanophyta in Xinjiang Uygur Autonomous Region, and two species of bacillariophyta, Chaetoceros sp. and Thalassionema sp., belonged to marine algal. In each season, the phytoplankton composition was dominated by Chlorophyta aad Bacillariophyta, secondly dominated by Cyanophyta, Euglenophyta, Xanthophyta, Chrysophyta, Cryptophyta and Pyrrophyta. The number of phytoplankton species was the highest in autumn (141 species), followed by the summer (128 species) aad spring (121 species), the lowest in winter (95 species). There was an obvious seasonal

  2. 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

  3. The Effect of Atrazine on Louisiana Gulf Coast Estuarine Phytoplankton.

    Science.gov (United States)

    Starr, Alexis V; Bargu, Sibel; Maiti, Kanchan; DeLaune, Ronald D

    2017-02-01

    Pesticides may enter water bodies in areas with a high proportion of agricultural land use through surface runoff, groundwater discharge, and erosion and thus negatively impact nontarget aquatic organisms. The herbicide atrazine is used extensively throughout the Midwest and enters the Mississippi River through surface runoff and groundwater discharge. The purpose of this study was to determine the extent of atrazine contamination in Louisiana's estuaries from Mississippi River water under different flow and nutrient regimes (spring and summer) and its effect on the biomass and oxygen production of the local phytoplankton community. The results showed that atrazine was consistently present in these systems at low levels. Microcosm experiments exposed to an atrazine-dilution series under low and high nutrient conditions to determine the phytoplankton stress response showed that high atrazine levels greatly decreased phytoplankton biomass and oxygen production. Phytoplankton exposed to low and moderate atrazine levels under high nutrient conditions were able to recover after an extended acclimation period. Communities grown under high nutrient conditions grew more rapidly and produced greater levels of oxygen than the low nutrient treatment groups, thus indicating that atrazine exposure may induce a greater stress response in phytoplankton communities under low-nutrient conditions. The native community also experienced a shift from more sensitive species, such as chlorophytes, to potentially more resilient species such as diatoms. The phytoplankton response to atrazine exposure at various concentrations can be especially important to greater trophic levels because their growth and abundance can determine the potential productivity of the entire ecosystem.

  4. Zooplankton excretion metabolites stimulate Southern Ocean phytoplankton growth

    KAUST Repository

    Coello-Camba, A.

    2017-04-24

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

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. Phytoplankton and littoral epilithic diatoms in high mountain lakes of the Adamello-Brenta Regional Park (Trentino, Italy and their relation to trophic status and acidification risk

    Directory of Open Access Journals (Sweden)

    Monica TOLOTTI

    2001-08-01

    Full Text Available A survey of phytoplankton and littoral epilithic diatom communities was carried out on 16 high mountain lakes in the Adamello- Brenta Regional Park (NE Italy as part of a wider research project aimed to the limnological characterisation of the seldom-studied lakes in this Alpine Region. The regional study was supplemented by the analysis of seasonal variations in two representative lakes. The principal goals of this paper are 1 to identify the most important environmental variables regulating patterns in the species composition of both phytoplankton and littoral diatoms, 2 to evaluate whether these algal communities can be used to improve trophic classification and 3 whether they can facilitate monitoring of diffuse human impacts (e.g. airborne pollution on high altitude lakes. The relevance to monitoring is based on the acid sensitivity of all lakes studied, as indicated by the very low average alkalinity values (4-97 μeq l-1 recorded during the investigation period. Chlorophyll-a concentrations and phytoplankton biovolume recorded in the lakes were very low, with maxima in the deep-water layers and in late summer. Phytoplankton communities were dominated by flagellated algae (Chrysophyceae and Dinophyceae. Several coccal green algae were present, while planktonic diatoms were almost completely absent. Littoral diatom communities were dominated by alpine and acidophilous taxa (mainly belonging to the genera Achnanthes and Eunotia. Trophic classification based on phytoplankton and littoral diatoms, respectively, ascribed all lakes to the oligotrophic range. In both algal communities species indicative of acidified conditions were found. Multivariate analyses indicated that both the regional distribution and seasonal variation of phytoplankton are mainly driven by nutrient concentration. Diatoms are predominantly affected by geochemical characteristics including pH and mineralization level.

  10. 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.

  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. 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.

  13. 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

  14. 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.

  15. Polar Lipids Analysis of Cultured Phytoplankton Reveals Significant Inter-taxa Changes, Low Influence of Growth Stage, and Usefulness in Chemotaxonomy.

    Science.gov (United States)

    Cañavate, José Pedro; Armada, Isabel; Hachero-Cruzado, Ismael

    2017-05-01

    The high lipid diversity of microalgae has been used to taxonomically differentiate phytoplankton taxa at the class level. However, important lipids such as phospholipids (PL) and betaine lipids (BL) with potential chemotaxonomy application in phytoplankton ecology have been scarcely studied. The chemotaxonomy value of PL and BL depends on their intraspecific extent of variation as microalgae respond to external changing factors. To determine such effects, lipid class changes occurring at different growth stages in 15 microalgae from ten different classes were analyzed. BL occurred in 14 species and were the less affected lipids by growth stage with diacylglyceryl-hydroxymethyl-N,N,N-trimethyl-b-alanine (DGTA) showing the highest stability. PL were more influenced by growth stage with phosphatidylcholine (PC), phosphatidylglycerol (PG), and phosphatidyletanolamine (PE) declining towards older culture stages in some species. Glycolipids were the more common lipids, and no evident age-related variability pattern could be associated to taxonomic diversity. Selecting BL and PL as descriptor variables optimally distinguished microalgae taxonomic variability at all growth stages. Principal coordinate analysis arranged species through a main tendency from diacylglyceryl-hydroxymethyl-N,N,N-trimethyl-b-alanine (DGCC) containing species (mainly dinoflagellates and haptophytes) to DGTA or PC containing species (mainly cryptophytes). Two diatom classes with similar fatty acid profiles could be distinguished from their respective content in DGTA (Bacillariophyceae) or DGCC (Mediophyceae). In green lineage classes (Trebouxiophyceae, Porphyridophyceae, and Chlorodendrophyceae), PC was a better descriptor than BL. BL and PL explained a higher proportion of microalgae taxonomic variation than did fatty acids and played a complementary role as lipid markers.

  16. 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.

  17. 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.

  18. Warming will affect phytoplankton differently: evidence through a mechanistic approach.

    Science.gov (United States)

    Huertas, I Emma; Rouco, Mónica; López-Rodas, Victoria; Costas, Eduardo

    2011-12-07

    Although the consequences of global warming in aquatic ecosystems are only beginning to be revealed, a key to forecasting the impact on aquatic communities is an understanding of individual species' vulnerability to increased temperature. Despite their microscopic size, phytoplankton support about half of the global primary production, drive essential biogeochemical cycles and represent the basis of the aquatic food web. At present, it is known that phytoplankton are important targets and, consequently, harbingers of climate change in aquatic systems. Therefore, investigating the capacity of phytoplankton to adapt to the predicted warming has become a relevant issue. However, considering the polyphyletic complexity of the phytoplankton community, different responses to increased temperature are expected. We experimentally tested the effects of warming on 12 species of phytoplankton isolated from a variety of environments by using a mechanistic approach able to assess evolutionary adaptation (the so-called ratchet technique). We found different degrees of tolerance to temperature rises and an interspecific capacity for genetic adaptation. The thermal resistance level reached by each species is discussed in relation to their respective original habitats. Our study additionally provides evidence on the most resistant phytoplankton groups in a future warming scenario.

  19. Phytoplankton Identification Manual

    Digital Repository Service at National Institute of Oceanography (India)

    Verlecar, X.N.; Desai, S.R.

    of Environment & Forests, New Delhi 3 FOREWORD Since its inception in 1966 the National Institute of Oceanography is involved in taxonomic classification of marine phytoplankton, zooplankton, benthos and other flora and fauna under the Project ? Measurement... details of taxonomic classification and description of the concerned organisms / species. All the figures are well illustrated and detailed identification key is provided. This should surely guide even a beginner to understand the identification...

  20. 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.

  1. An Inverse Modeling Approach to Estimating Phytoplankton Pigment Concentrations from Phytoplankton Absorption Spectra

    Science.gov (United States)

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

    2011-01-01

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

  2. A numerical modeling analysis of the phytoplankton and nutrients dynamics for Todos Santos Bay and northwestern Baja California

    Science.gov (United States)

    Cruz Rico, J. E., Sr.; Rivas, D.

    2015-12-01

    A tridimensional physical-biological numerical model is implemented for the Todos Santos Bay and the northwest of Baja California to investigate the mechanics and ecological processes associated with the regional plankton dynamics. An NPZD (Nitrate, Phytoplankton, Zooplankton, and Detritus) ecosystem simple model is used to describe the distribution and evolution of the lower trophic levels in the area of study. The model adequately reproduces the spatial distribution of the concentration of chlorophyll for the different seasons of the year. In general, the distribution of the subsurface chlorophyll maximum (SCM) depends primarily on the seasonal circulation patterns, the total solar irradiance, and the vertical flux of nutrients. Interannual variability shows two extreme years in the analyzed period: 2006 and 2007. Year 2006 was an anomalous warm year, with a weak upwelling activity and low chlorophyll concentrations compared to year 2011. These anomalies are related to the activity of the Pacific Decadal Oscillation, the El Niño+3, and the regional Outgoing Longwave Radiation. Thus, in spite of the simplicity of the NPZD model, both temporal and spatial patterns of distribution of chlorophyll and nutrients are generally reproduced.

  3. 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

  4. Tight Coupling of Glaciecola spp. and Diatoms during Cold-Water Phytoplankton Spring Blooms

    Science.gov (United States)

    von Scheibner, Markus; Sommer, Ulrich; Jürgens, Klaus

    2017-01-01

    Early spring phytoplankton blooms can occur at very low water temperatures but they are often decoupled from bacterial growth, which is assumed to be often temperature controlled. In a previous mesocosm study with Baltic Sea plankton communities, an early diatom bloom was associated with a high relative abundance of Glaciecola sequences (Gammaproteobacteria), at both low (2°C) and elevated (8°C) temperatures, suggesting an important role for this genus in phytoplankton-bacteria coupling. In this study, the temperature-dependent dynamics of free-living Glaciecola spp. during the bloom were analyzed by catalyzed reporter deposition fluorescence in situ hybridization using a newly developed probe. The analysis revealed the appearance of Glaciecola spp. in this and in previous spring mesocosm experiments as the dominating bacterial clade during diatom blooms, with a close coupling between the population dynamics of Glaciecola and phytoplankton development. Although elevated temperature resulted in a higher abundance and a higher net growth rate of Glaciecola spp. (Q10 ∼ 2.2), their growth was, in contrast to that of the bulk bacterial assemblages, not suppressed at 2°C and showed a similar pattern at 8°C. Independent of temperature, the highest abundance of Glaciecola spp. (24.0 ± 10.0% of total cell number) occurred during the peak of the phytoplankton bloom. Together with the slightly larger cell size of Glaciecola, this resulted in a ∼30% contribution of Glaciecola to total bacterial biomass. Overall, the results of this and previous studies suggest that Glaciecola has an ecological niche during early diatom blooms at low temperatures, when it becomes a dominant consumer of phytoplankton-derived dissolved organic matter.

  5. Empirical relationships between phytoplankton and zooplankton biomass in Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Jayalakshmy, K.V.

    Empirical models based on regression analysis are derived using published values of phytoplankton and crustacean zooplankton biomass from Indian Ocean. Three regression models are derived. There is significant correlation between zooplankton...

  6. Seniors' Online Communities: A Quantitative Content Analysis

    Science.gov (United States)

    Nimrod, Galit

    2010-01-01

    Purpose: To examine the contents and characteristics of seniors' online communities and to explore their potential benefits to older adults. Design and Methods: Quantitative content analysis of a full year's data from 14 leading online communities using a novel computerized system. The overall database included 686,283 messages. Results: There was…

  7. 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

  8. 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

  9. 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.

  10. 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

  11. Primary production in a tropical large lake: The role of phytoplankton composition

    Energy Technology Data Exchange (ETDEWEB)

    Darchambeau, F., E-mail: francois.darchambeau@ulg.ac.be [Chemical Oceanography Unit, University of Liège, Liège (Belgium); Sarmento, H., E-mail: hugo.sarmento@gmail.com [Department of Hydrobiology, Federal University of São Carlos, 13565-905 São Carlos, São Paulo (Brazil); Descy, J.-P., E-mail: jean-pierre.descy@unamur.be [Research Unit in Environmental and Evolutionary Biology, University of Namur, Namur (Belgium)

    2014-03-01

    Phytoplankton biomass and primary production in tropical large lakes vary at different time scales, from seasons to centuries. We provide a dataset made of 7 consecutive years of phytoplankton biomass and production in Lake Kivu (Eastern Africa). From 2002 to 2008, bi-weekly samplings were performed in a pelagic site in order to quantify phytoplankton composition and biomass, using marker pigments determined by HPLC. Primary production rates were estimated by 96 in situ {sup 14}C incubations. A principal component analysis showed that the main environmental gradient was linked to a seasonal variation of the phytoplankton assemblage, with a clear separation between diatoms during the dry season and cyanobacteria during the rainy season. A rather wide range of the maximum specific photosynthetic rate (P{sub Bm}) was found, ranging between 1.15 and 7.21 g carbon g{sup −1} chlorophyll a h{sup −1}, and was best predicted by a regression model using phytoplankton composition as an explanatory variable. The irradiance at the onset of light saturation (I{sub k}) ranged between 91 and 752 μE m{sup −2} s{sup −1} and was linearly correlated with the mean irradiance in the mixed layer. The inter-annual variability of phytoplankton biomass and production was high, ranging from 53 to 100 mg chlorophyll a m{sup −2} (annual mean) and from 143 to 278 g carbon m{sup −2} y{sup −1}, respectively. The degree of seasonal mixing determined annual production, demonstrating the sensitivity of tropical lakes to climate variability. A review of primary production of other African great lakes allows situating Lake Kivu productivity in the same range as that of lakes Tanganyika and Malawi, even if mean phytoplankton biomass was higher in Lake Kivu. - Highlights: • We provide a 7-year dataset of primary production in a tropical great lake. • Specific photosynthetic rate was determined by community composition. • Annual primary production varied between 143 and 278 mg C m

  12. 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

  13. 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.

  14. 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%;

  15. Resolving variability of phytoplankton species composition and blooms in coastal ecosystems

    Science.gov (United States)

    Klais, Riina; Cloern, James E.; Harrison, Paul J.

    2015-09-01

    The contributions to this special volume focus on phytoplankton dynamics in coastal ecosystems, where perturbations from terrestrial, atmospheric, oceanic sources and human activities converge to cause changes in phytoplankton communities. Analyses of phytoplankton time series across the range of coastal sites, either as meta-analyses or single site based studies, complete our general understanding of the ecology of coastal phytoplankton dynamics. The role of short-term variability of the phytoplankton community appears to be more important for the annual primary production than previously thought, especially during the high biomass spring bloom period (Gallegos and Neale, 2015). Diel vertical migration of motile species is commonplace even in shallow and presumably well-mixed estuaries (Hall et al., 2015). Comparing phytoplankton patterns in various sites reveals contrasting long-term trends in the last two decades, reflecting the recent history of economic growth in related coastal areas. In Chesapeake Bay Estuary (US east coast) and Thau Lagoon (southern France), oligotrophication has been achieved by different nutrient reduction measures (Gowen et al., 2015; Harding et al., 2015), while in the Patos Lagoon Estuary (Brazil) and SE coast of Arabian Sea, the last two decades showed signs of eutrophication, following the more recent period of economic growth in the area (Haraguchi et al., 2015; Godhe et al., 2015). The global meta-analyses in this volume exposed the great challenges involved when working with this type of data, due to the diversity of idiosyncrasies characteristic to most phytoplankton time series, for example, the taxonomic practices, cell volume calculations (Harrison et al., 2015), volume to carbon conversions (Carstensen et al., 2015; Olli et al., 2015). But also the diversity of the patterns themselves makes analyses challenging (Carstensen et al., 2015; Thompson et al., 2015). To begin to move towards more similar practices in plankton

  16. 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...

  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. 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. 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

  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. Chapter 11. Community analysis-based methods

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Y.; Wu, C.H.; Andersen, G.L.; Holden, P.A.

    2010-05-01

    Microbial communities are each a composite of populations whose presence and relative abundance in water or other environmental samples are a direct manifestation of environmental conditions, including the introduction of microbe-rich fecal material and factors promoting persistence of the microbes therein. As shown by culture-independent methods, different animal-host fecal microbial communities appear distinctive, suggesting that their community profiles can be used to differentiate fecal samples and to potentially reveal the presence of host fecal material in environmental waters. Cross-comparisons of microbial communities from different hosts also reveal relative abundances of genetic groups that can be used to distinguish sources. In increasing order of their information richness, several community analysis methods hold promise for MST applications: phospholipid fatty acid (PLFA) analysis, denaturing gradient gel electrophoresis (DGGE), terminal restriction fragment length polymorphism (TRFLP), cloning/sequencing, and PhyloChip. Specific case studies involving TRFLP and PhyloChip approaches demonstrate the ability of community-based analyses of contaminated waters to confirm a diagnosis of water quality based on host-specific marker(s). The success of community-based MST for comprehensively confirming fecal sources relies extensively upon using appropriate multivariate statistical approaches. While community-based MST is still under evaluation and development as a primary diagnostic tool, results presented herein demonstrate its promise. Coupled with its inherently comprehensive ability to capture an unprecedented amount of microbiological data that is relevant to water quality, the tools for microbial community analysis are increasingly accessible, and community-based approaches have unparalleled potential for translation into rapid, perhaps real-time, monitoring platforms.

  2. Phytoplankton across Tropical and Subtropical Regions of the Atlantic, Indian and Pacific Oceans

    Science.gov (United States)

    Estrada, Marta; Delgado, Maximino; Blasco, Dolors; Latasa, Mikel; Cabello, Ana María; Benítez-Barrios, Verónica; Fraile-Nuez, Eugenio; Mozetič, Patricija; Vidal, Montserrat

    2016-01-01

    We examine the large-scale distribution patterns of the nano- and microphytoplankton collected from 145 oceanic stations, at 3 m depth, the 20% light level and the depth of the subsurface chlorophyll maximum, during the Malaspina-2010 Expedition (December 2010-July 2011), which covered 15 biogeographical provinces across the Atlantic, Indian and Pacific oceans, between 35°N and 40°S. In general, the water column was stratified, the surface layers were nutrient-poor and the nano- and microplankton (hereafter phytoplankton, for simplicity, although it included also heterotrophic protists) community was dominated by dinoflagellates, other flagellates and coccolithophores, while the contribution of diatoms was only important in zones with shallow nutriclines such as the equatorial upwelling regions. We applied a principal component analysis to the correlation matrix among the abundances (after logarithmic transform) of the 76 most frequent taxa to synthesize the information contained in the phytoplankton data set. The main trends of variability identified consisted of: 1) A contrast between the community composition of the upper and the lower parts of the euphotic zone, expressed respectively by positive or negative scores of the first principal component, which was positively correlated with taxa such as the dinoflagellates Oxytoxum minutum and Scrippsiella spp., and the coccolithophores Discosphaera tubifera and Syracosphaera pulchra (HOL and HET), and negatively correlated with taxa like Ophiaster hydroideus (coccolithophore) and several diatoms, 2) a general abundance gradient between phytoplankton-rich regions with high abundances of dinoflagellate, coccolithophore and ciliate taxa, and phytoplankton-poor regions (second principal component), 3) differences in dominant phytoplankton and ciliate taxa among the Atlantic, the Indian and the Pacific oceans (third principal component) and 4) the occurrence of a diatom-dominated assemblage (the fourth principal

  3. Phytoplankton across Tropical and Subtropical Regions of the Atlantic, Indian and Pacific Oceans.

    Directory of Open Access Journals (Sweden)

    Marta Estrada

    Full Text Available We examine the large-scale distribution patterns of the nano- and microphytoplankton collected from 145 oceanic stations, at 3 m depth, the 20% light level and the depth of the subsurface chlorophyll maximum, during the Malaspina-2010 Expedition (December 2010-July 2011, which covered 15 biogeographical provinces across the Atlantic, Indian and Pacific oceans, between 35°N and 40°S. In general, the water column was stratified, the surface layers were nutrient-poor and the nano- and microplankton (hereafter phytoplankton, for simplicity, although it included also heterotrophic protists community was dominated by dinoflagellates, other flagellates and coccolithophores, while the contribution of diatoms was only important in zones with shallow nutriclines such as the equatorial upwelling regions. We applied a principal component analysis to the correlation matrix among the abundances (after logarithmic transform of the 76 most frequent taxa to synthesize the information contained in the phytoplankton data set. The main trends of variability identified consisted of: 1 A contrast between the community composition of the upper and the lower parts of the euphotic zone, expressed respectively by positive or negative scores of the first principal component, which was positively correlated with taxa such as the dinoflagellates Oxytoxum minutum and Scrippsiella spp., and the coccolithophores Discosphaera tubifera and Syracosphaera pulchra (HOL and HET, and negatively correlated with taxa like Ophiaster hydroideus (coccolithophore and several diatoms, 2 a general abundance gradient between phytoplankton-rich regions with high abundances of dinoflagellate, coccolithophore and ciliate taxa, and phytoplankton-poor regions (second principal component, 3 differences in dominant phytoplankton and ciliate taxa among the Atlantic, the Indian and the Pacific oceans (third principal component and 4 the occurrence of a diatom-dominated assemblage (the fourth

  4. 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

  5. Large-scale shifts in phytoplankton groups in the Equatorial Pacific during ENSO cycles

    Directory of Open Access Journals (Sweden)

    I. Masotti

    2011-03-01

    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 nanoeucaryote 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.

  6. Fluid dynamical niches of phytoplankton types.

    Science.gov (United States)

    d'Ovidio, Francesco; De Monte, Silvia; Alvain, Séverine; Dandonneau, Yves; Lévy, Marina

    2010-10-26

    The biogeochemical role of phytoplanktonic organisms strongly varies from one plankton type to another, and their relative abundance and distribution have fundamental consequences at the global and climatological scales. In situ observations find dominant types often associated to specific physical and chemical water properties. However, the mechanisms and spatiotemporal scales by which marine ecosystems are organized are largely not known. Here we investigate the spatiotemporal organization of phytoplankton communities by combining multisatellite data, notably high-resolution ocean-color maps of dominant types and altimetry-derived Lagrangian diagnostics of the surface transport. We find that the phytoplanktonic landscape is organized in (sub-)mesoscale patches (10-100 km) of dominant types separated by physical fronts induced by horizontal stirring. These physical fronts delimit niches supported by water masses of similar history and whose lifetimes are comparable with the timescale of the bloom onset (few weeks). The resonance between biological activity and physical processes suggest that the spatiotemporal (sub-)mesoscales associated to stirring are determinant in the observation and modeling of marine ecosystems.

  7. 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

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

    Science.gov (United States)

    Galloway, Aaron W E; Winder, Monika

    2015-01-01

    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 diatoms

  9. 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

  10. Metagenomic analysis of microbial communities and beyond

    DEFF Research Database (Denmark)

    Schreiber, Lars

    2014-01-01

    From small clone libraries to large next-generation sequencing datasets – the field of community genomics or metagenomics has developed tremendously within the last years. This chapter will summarize some of these developments and will also highlight pitfalls of current metagenomic analyses. It w...... heterologous expression of metagenomic DNA fragments to discover novel metabolic functions. Lastly, the chapter will shortly discuss the meta-analysis of gene expression of microbial communities, more precisely metatranscriptomics and metaproteomics....

  11. Estrutura e dinâmica da comunidade fitoplanctônica a jusante e montante do reservatório de Corumbá, Caldas Novas, Estado de Goiás, Brasil Structure and dynamics of the phytoplankton community downstream and upstream Corumbá reservoir, Caldas Novas, state of Goiás, Brazil

    Directory of Open Access Journals (Sweden)

    Sueli Train

    2001-05-01

    aims at characterizing the phytoplankton community in stations upstream and downstream Corumbá reservoir in the state of Goiás, and at identifying the main environmental variables that influence its structure. Samples of sub-surface water were collected monthly in 3 stations (2 upstream Corumbá reservoir and 1 downstream, from November 1996 to November 1997, and bimonthly from January 1998 to May 1999. The distribution pattern of phytoplankton was analyzed through the limnological factors of water temperature, flow, turbidity, electric conductivity, reactive soluble phosphorus, ammonium, nitrate, and total Kjeldahl nitrogen, using canonical correspondence analysis. Among the 162 taxa identified, Cyanophyceae and Bacillariophyceae were the most abundant and were responsible for density peaks. During the study period, the largest phytoplankton density (28.313 ind.ml-1 registered in the Corumbá river occurred in the station lying downstream the reservoir, with the dominance of the diatom Achnanthes minutissima. The heterocytous cyanoprokaryote Cylindrospermopsis raciborskii presented high abundance in the stations upstream the reservoir during the dry season. Variations showed a sharp seasonality related to the hydrological cycle, or rather, the lowest phytoplankton density occurred in the period of largest flow and maximum abundance was registered during reduced flow. Therefore, the dynamics of the phytoplankton community was strongly determined by the flow, temperature and nutrient concentrations of the Corumbá river

  12. Phytoplankton diversity in the East China Sea and Yellow Sea measured by PCR-DGGE and its relationships with environmental factors

    Science.gov (United States)

    Sun, Jing; Yu, Zhigang; Gao, Yahui; Zhou, Qianqian; Zhen, Yu; Chen, Hongtao; Zhao, Liyuan; Yao, Qingzhen; Mi, Tiezhu

    2010-03-01

    Relationships between phytoplankton community composition and environmental variables in the East China Sea (ECS) and Yellow Sea (YS) were investigated using geochemical and molecular microbiology methods. The diversity of phytoplankton was characterized using cultivation-independent PCR-based denaturing gradient gel electrophoresis (DGGE). Groups resulting from unweighted pair-group method with arithmetic averages clustering of the DGGE profiles showed good consistency with the eco-environmental characteristics of the sea area they belonged to. Additionally, the clustering results based on DGGE fingerprinting and those based on morphological compositions were practically identical. The relationship of phytoplankton diversity to environmental factors was statistically analyzed. Temperature, dissolved inorganic nitrogen (DIN), and silicate-Si were found significantly related to the phytoplankton community composition. Canonical correspondence analysis (CCA) was performed to reveal the relationship between community composition and these three environmental factors. Generally, values of the ECS are clearly separated from those of the YS in the CCA biplot, due to mainly the effect of temperature and DIN.

  13. Ultrafast quantitative time-stretch imaging flow cytometry of phytoplankton

    Science.gov (United States)

    Lai, Queenie T. K.; Lau, Andy K. S.; Tang, Anson H. L.; Wong, Kenneth K. Y.; Tsia, Kevin K.

    2016-03-01

    Comprehensive quantification of phytoplankton abundance, sizes and other parameters, e.g. biomasses, has been an important, yet daunting task in aquatic sciences and biofuel research. It is primarily because of the lack of effective tool to image and thus accurately profile individual microalgae in a large population. The phytoplankton species are highly diversified and heterogeneous in terms of their sizes and the richness in morphological complexity. This fact makes time-stretch imaging, a new ultrafast real-time optical imaging technology, particularly suitable for ultralarge-scale taxonomic classification of phytoplankton together with quantitative image recognition and analysis. We here demonstrate quantitative imaging flow cytometry of single phytoplankton based on quantitative asymmetric-detection time-stretch optical microscopy (Q-ATOM) - a new time-stretch imaging modality for label-free quantitative phase imaging without interferometric implementations. Sharing the similar concept of Schlieren imaging, Q-ATOM accesses multiple phase-gradient contrasts of each single phytoplankton, from which the quantitative phase profile is computed. We employ such system to capture, at an imaging line-scan rate of 11.6 MHz, high-resolution images of two phytoplankton populations (scenedesmus and chlamydomonas) in ultrafast microfluidic flow (3 m/s). We further perform quantitative taxonomic screening analysis enabled by this technique. More importantly, the system can also generate quantitative phase images of single phytoplankton. This is especially useful for label-free quantification of biomasses (e.g. lipid droplets) of the particular species of interest - an important task adopted in biofuel applications. Combining machine learning for automated classification, Q-ATOM could be an attractive platform for continuous and real-time ultralarge-scale single-phytoplankton analysis.

  14. 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.

  15. Spectra of light absorption by phytoplankton pigments in the Baltic; conclusions to be drawn from a Gaussian analysis of empirical data

    Directory of Open Access Journals (Sweden)

    Dariusz Ficek

    2004-12-01

    Full Text Available Analysed by differential spectroscopy, 1208 empirical spectra of light absorption apl(λ by Baltic phytoplankton were spectrally decomposed into 26 elementary Gaussian component bands. At the same time the composition and concentrations of each of the 5 main groups of pigments (chlorophylls a, chlorophylls b, chlorophylls c, photosynthetic carotenoids and photoprotecting carotenoids were analysed in 782 samples by HPLC. Inspection of the correlations between the intensities of the 26 elementary absorption bands and the concentrations of the pigment groups resulted in given elementary bands being attributed to particular pigment groups and the spectra of the mass-specific absorption coefficients established for these pigment groups. Moreover, balancing the absorption effects due to these 5 pigment groups against the overall absorption spectra of phytoplankton suggested the presence of a sixth group of pigments, as yet unidentified (UP, undetected by HPLC. A preliminary mathematical description of the spectral absorption properties of these UP was established. Like some forms of phycobilins, these pigments are strong absorbers in the 450-650 nm spectral region. The packaging effect of pigments in Baltic phytoplankton was analysed statistically, then correlated with the concentration of chlorophyll a in Baltic water. As a result, a Baltic version of the algorithm of light absorption by phytoplankton could be developed. This algorithm can be applied to estimate overall phytoplankton absorption spectra and their components due to the various groups of pigments from a knowledge of their concentrations in Baltic water.

  16. Microbial community analysis using MEGAN.

    Science.gov (United States)

    Huson, Daniel H; Weber, Nico

    2013-01-01

    Metagenomics, the study of microbes in the environment using DNA sequencing, depends upon dedicated software tools for processing and analyzing very large sequencing datasets. One such tool is MEGAN (MEtaGenome ANalyzer), which can be used to interactively analyze and compare metagenomic and metatranscriptomic data, both taxonomically and functionally. To perform a taxonomic analysis, the program places the reads onto the NCBI taxonomy, while functional analysis is performed by mapping reads to the SEED, COG, and KEGG classifications. Samples can be compared taxonomically and functionally, using a wide range of different charting and visualization techniques. PCoA analysis and clustering methods allow high-level comparison of large numbers of samples. Different attributes of the samples can be captured and used within analysis. The program supports various input formats for loading data and can export analysis results in different text-based and graphical formats. The program is designed to work with very large samples containing many millions of reads. It is written in Java and installers for the three major computer operating systems are available from http://www-ab.informatik.uni-tuebingen.de.

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. Studies on phytoplankton with reference to dinoflagellates

    Digital Repository Service at National Institute of Oceanography (India)

    Naik, R.K.

    in different regions 52 3.4. Discussion 54 Chapter 4 Micro-phytoplankton community structure at Mormugao and Visakhapatnam ports 4A.1. Introduction 58 4A.2. Materials and methods 60 4A.2.1. Study areas 60 4A.2...P��� QDQRSODQNWRQ� ��-��� ȝP�� DQG� SLFRSODQNWRQ� ����-�� ȝP�� �7DEOH� ����� Diatoms (Class Bacillariophyta) occur in all 3 size classes whereas dinoflagellates (Class Dinophyta) are represented in the micro- and nanoplankton groups (Jeffrey and Hallegraeff 1990...

  2. 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

  3. Community structures of phytoplankton and their relationships with environmental factors in the Jinshahe Reservoir, Hubei Province%湖北金沙河水库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)

    张云; 马徐发; 郭飞飞; 李建柱; 熊邦喜

    2015-01-01

    In order to evaluate the water quality of drinking water resource in the middle reaches of the Changjiang River, phyto-plankton community structures and their diversities were investigated seasonally from August, 2013 to April, 2014 in the Jinshahe Reservoir, Hubei Province. Meanwhile, multivariate statistics was used to analyze the relationships between phytoplankton assem-blages and environmental variables. The results showed that there were total of 216 species of phytoplankton belonging to 8 phyla and 94 genera. Chlorophyta which made up of 51. 39% of the total numbers of the species was the dominant group, followed by Bacillariophyta and Cyanophyta. Dominant species varied in different seasons. In summer, the ecological dominance of Synedra acus was the highest (0. 195), and in autumn, Phormidium tenus (0. 180) and Raphidiopsis sinensia (0. 171) had the highest ecological dominance. In winter, Cyclotella stelligera (0. 220) and Dinobryon cylindricum (0. 234) had the highest ecological dominance, and Achanthidum catenatum was the absolute dominant species with its ecological dominance of 0. 910. In general, Cyanophyta, Bacillariophyta and Chlorophyta were dominant groups in summer, and Cyanophyta, Bacillariophyta, Chlorophyta and Cryptophyta were dominant groups in autumn. Bacillariophyta and Chrysophyta were dominant groups in winter, and Bacillariophy-ta was the absolute dominant group in spring. Biodiversity indices showed that phytoplankton had higher values of the Shannon-Wiener diversity and the Pielou diversity in autumn, but the lowest values in spring because the absolute dominant species appeared in spring other than in autumn. In addition, the highest value of Margalef diversity occurred in autumn because of its larger number of species. Redundancy analysis was used to analyze the relationships between the dominant species in each season and the envi-ronmental factors filtered by Pearson correlation analysis. The results showed that phosphate, total

  4. 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

  5. Diversity and distribution of winter phytoplankton in the Arabian Gulf and the Sea of Oman

    Science.gov (United States)

    Polikarpov, Igor; Saburova, Maria; Al-Yamani, Faiza

    2016-05-01

    The spatial distribution of the phytoplankton (diversity, composition, and cell abundance) was described in relation to local environmental conditions across the Arabian Gulf, the Strait of Hormuz, and the Sea of Oman based on data of ROPME cruise of winter 2006. The 376 phytoplankton taxa identified in these waters represented a diverse composition of species with a prevalence of dinoflagellates and diatoms. Three peaks in the phytoplankton abundance were recorded throughout the studied area associated with diatom-dominated phytoplankton blooms in the central and northwestern part of the Arabian Gulf and in the Sea of Oman and the adjacent waters. The studied area was divided into three main regions by cluster analysis based on differences in the phytoplankton composition and concentration. The Sea of Oman and the Strait of Hormuz were occupied by highly abundant, strongly diatom-dominated phytoplankton assemblage. The Arabian Gulf was divided into two main regions along a diagonal northwest-southeast axis, with rather diatom-dominated phytoplankton assemblage off the south and along the Iranian coast but with flagellate-dominated phytoplankton of the north and along the Arabian coast. The distance-based linear modeling revealed a significant relationship between the phytoplankton composition and water masses as indexed by salinity. Our results demonstrated that abundance and composition of winter phytoplankton were related to water circulation pattern in the Arabian Gulf and the Sea of Oman.

  6. 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...

  7. Temporal and spatial fluctuations of phytoplankton in a tropical coastal lagoon, southeast Brazil

    National Research Council Canada - National Science Library

    Melo, S; Bozelli, RL; Esteves, FA

    2007-01-01

    Spatial and temporal variability of the phytoplankton community in the tropical coastal Imboassica lagoon, an environment naturally isolated from the ocean by a narrow sandbar, was analysed every two...

  8. 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.

  9. Lidar fluorosensor system for remote monitoring phytoplankton blooms in the Swedish marine campaign

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-09-01

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

  10. Phytoplankton community structure at the juncture of the Agulhas return front and subtropical front in the Indian Ocean sector of Southern Ocean: Bottom-up and top-down control

    Digital Repository Service at National Institute of Oceanography (India)

    Naik, R.K.; George, J.V.; Soares, M.A.; Devi, A.; Anilkumar, N.; Roy, R.; Bhaskar, P.V.; Murukesh, N.; Achuthankutty, C.T.

    The juncture of the Agulhas Return Front (ARF) and Subtropical Front (STF) in the Indian Ocean sector of Southern Ocean (SO) is characterized by high mesoscale turbulence, which results in sporadic, short lived phytoplankton proliferation The biota...

  11. Zooplankton communities in the Krenceng Reservoair, Cilegon, Banten

    Directory of Open Access Journals (Sweden)

    Mufti P. Patria

    2005-11-01

    Full Text Available This research was carried out to know the structure of zooplankton communities and relations between the phytoplankton and zooplankton in the Krenceng Reservoair, Cilegon. The zooplankton abundance with used Sedwigck Rafter Counting Method, diversity and evenness were counted. Relations between zooplankton and the environmental factors as well as its relations to phytoplankton calculated with regression. The results showed that are 13 species of the zooplankton found which including in three classes with the highest abundance on Novembers 2002 and March 2003 of the Rotifera. The analysis of regression pointed out that the environmental factors such: pH, BOD5, nitrate, CO2 and abundance of phytoplankton influence the abundance zooplankton in November. While in March, the abundance of zooplankton is influenced by brigthtness, nitrate, orthophosphates and C organic. The abundance of phytoplankton influenced positively by the abundance of zooplankton.

  12. 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.

  13. 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...

  14. 北冰洋中心区表层海水营养盐及浮游植物群落对快速融冰的响应%RESPONSE OF NUTRIENTS AND THE SURFACE PHYTOPLANKTON COMMUNITY TO ICE MELTING IN THE CENTRAL ARCTIC OCEAN

    Institute of Scientific and Technical Information of China (English)

    庄燕培; 金海燕; 陈建芳; 王斌; 李宏亮; 陈法锦; 卢勇; 徐杰

    2012-01-01

    During the fourth Chinese National Arctic Research Expedition cruise in summer 2010, a time-series observation was carried out to examine the response of nutrients and phytoplankton community in the ice-water interface to the ice melting in the central Arctic Ocean. Phosphate and silicate in the ice-water interface were rich relative to dissolved inorganic nitrogen ( DIN) , based on the Redfield ratio (16N: IP: 16Si) , suggesting that DIN was the potential limiting nutrient. DIN concentrations in the sea ice were about 3-4 times that in the surface seawater, indicating that melting ice delivered DIN to the surface water. Pigment analysis showed that fucoxanthin and chlorophyll a contribute to carotenoids and chlorophylls in particles. The mean concentrations of chlorophyll c, diatoxanthin, diadinoxanthin and fucoxanthin from 15 August to 18 August were 6 μg o m-3 , 22 μg · m-3 , 73 μg o m-3 and 922 μg o m-3, respectively, suggesting that diatoms dominated in the phytoplankton community composition. Furthermore , a notable enhancement in fucoxanthin and chlorophyll a during a large-scale ice melting was likely attributed to senescent diatoms released from the bottom sea-ice as well as phytoplankton diatoms growth in the water column due to the input of nutrients (i. e. DIN) and reducing light limitation from melting ice. Temporal distribution patterns of prasinoxanthin and lutein differed from fucoxanthin, indicating that the response of green algae and diatoms to ice melting were different.%依托2010年夏季中国第四次北极科学考察,通过对高纬度极地冰下水和冰芯的营养盐的连续观测及表层水颗粒物的藻类色素分析,获取了夏季快速融冰下冰水界面营养盐和光合色素的分布信息.结果表明调查期问表层水磷酸盐和硅酸盐相对于无机氮更丰富(依据Redfield比值),表现为显著的氮限制.而冰芯无机氮浓度相对更高,融冰释放对水体无机氮有一定的补充.色

  15. 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).

  16. 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...

  17. 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

  18. Vertical distribution and composition of phytoplankton under the influence of an upper mixed layer.

    Science.gov (United States)

    Ryabov, Alexei B; Rudolf, Lars; Blasius, Bernd

    2010-03-01

    The vertical distribution of phytoplankton is of fundamental importance for the dynamics and structure of aquatic communities. Here, using an advection-reaction-diffusion model, we investigate the distribution and competition of phytoplankton species in a water column, in which inverse resource gradients of light and a nutrient can limit growth of the biomass. This problem poses a challenge for ecologists, as the location of a production layer is not fixed, but rather depends on many internal parameters and environmental factors. In particular, we study the influence of an upper mixed layer (UML) in this system and show that it leads to a variety of dynamic effects: (i) Our model predicts alternative density profiles with a maximum of biomass either within or below the UML, thereby the system may be bistable or the relaxation from an unstable state may require a long-lasting transition. (ii) Reduced mixing in the deep layer can induce oscillations of the biomass; we show that a UML can sustain these oscillations even if the diffusivity is less than the critical mixing for a sinking phytoplankton population. (iii) A UML can strongly modify the outcome of competition between different phytoplankton species, yielding bistability both in the spatial distribution and in the species composition. (iv) A light limited species can obtain a competitive advantage if the diffusivity in the deep layers is reduced below a critical value. This yields a subtle competitive exclusion effect, where the oscillatory states in the deep layers are displaced by steady solutions in the UML. Finally, we present a novel graphical approach for deducing the competition outcome and for the analysis of the role of a UML in aquatic systems.

  19. 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.

  20. Phytoplankton growth and microzooplankton grazing in the subtropical Northeast Atlantic.

    Directory of Open Access Journals (Sweden)

    Carlos Cáceres

    Full Text Available Dilution experiments were performed to estimate phytoplankton growth and microzooplankton grazing rates during two Lagrangian surveys in inner and eastern locations of the Eastern North Atlantic Subtropical Gyre province (NAST-E. Our design included two phytoplankton size fractions (0.2-5 µm and >5 µm and five depths, allowing us to characterize differences in growth and grazing rates between size fractions and depths, as well as to estimate vertically integrated measurements. Phytoplankton growth rates were high (0.11-1.60 d(-1, especially in the case of the large fraction. Grazing rates were also high (0.15-1.29 d(-1, suggesting high turnover rates within the phytoplankton community. The integrated balances between phytoplankton growth and grazing losses were close to zero, although deviations were detected at several depths. Also, O2 supersaturation was observed up to 110 m depth during both Lagrangian surveys. These results add up to increased evidence indicating an autotrophic metabolic balance in oceanic subtropical gyres.

  1. Spontaneous Assembly of Exopolymers from Phytoplankton

    Directory of Open Access Journals (Sweden)

    Yong-Xue Ding

    2009-01-01

    Full Text Available Phytoplankton exopolymeric substances (EPS contribute significantly to the dissolved organic car bon (DOC pool in the ocean, playing crucial roles in the surface ocean car bon cycle. Recent studies have demonstrated that ~10% of marine DOC can self-assemble as microgels through electro static Ca bonds providing hotspots of enriched microbial substrate. How ever, the question whether EPS can self-assemble and the formation mechanisms for EPS microgels have not been examined. Here were port that EPS from three representative phytoplankton species, Synechococcus, Emiliania huxleyi, and Skeletonema costatum can spontaneously self assemble in artificial sea water (ASW, forming microscopic gels of ~ 3 - 4 _ in diameter. Different from the marine DOC polymers assembly, these EPS samples can self-assemble in Ca2+-free ASW. Further experiments from fluorescence enhancement and chemical composition analysis confirmed the existence of fair amounts of hydrophobic domains in these EPS samples. These results suggest that hydrophobic interactions play a key role in the assembly of EPS from these three species of marine phytoplankton.

  2. 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.

  3. A coupled physical-biological model of the Northern Gulf of Mexico shelf: model description, validation and analysis of phytoplankton variability

    Directory of Open Access Journals (Sweden)

    K. Fennel

    2011-07-01

    Full Text Available The Texas-Louisiana shelf in the Northern Gulf of Mexico receives large inputs of nutrients and freshwater from the Mississippi/Atchafalaya River system. The nutrients stimulate high rates of primary production in the river plume, which contributes to the development of a large and recurring hypoxic area in summer, but the mechanistic links between hypoxia and river discharge of freshwater and nutrients are complex as the accumulation and vertical export of organic matter, the establishment and maintenance of vertical stratification, and the microbial degradation of organic matter are controlled by a non-linear interplay of factors. Unraveling these interactions will have to rely on a combination of observations and models. Here we present results from a realistic, 3-dimensional, physical-biological model with focus on a quantification of nutrient-stimulated phytoplankton growth, its variability and the fate of this organic matter. We demonstrate that the model realistically reproduces many features of observed nitrate and phytoplankton dynamics including observed property distributions and rates. We then contrast the environmental factors and phytoplankton source and sink terms characteristic of three model subregions that represent an ecological gradient from eutrophic to oligotrophic conditions. We analyze specifically the reasons behind the counterintuitive observation that primary production in the light-limited plume region near the Mississippi River delta is positively correlated with river nutrient input, and find that, while primary production and phytoplankton biomass are positively correlated with nutrient load, phytoplankton growth rate is not. This suggests that accumulation of biomass in this region is not primarily controlled bottom up by nutrient-stimulation, but top down by systematic differences in the loss processes.

  4. 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.

  5. Diversity of phytoplankton community in different urban aquatic ecosystems in metropolitan João Pessoa, state of Paraíba, Brazil Diversidade da comunidade fitoplactônica em diferentes ecossistemas aquáticos urbanos da região metropolitana de João Pessoa, PB, estado da Paraíba, Brasil

    Directory of Open Access Journals (Sweden)

    Davi Freire da Costa

    2011-12-01

    Full Text Available AIM: The aim of the present study was to identify which environmental factors affect the seasonal phytoplankton structure in different types of tropical aquatic ecosystems. Phytoplankton sampling was performed bi-monthly from August 2009 to June 2110 at three sites in the Solon de Lucena Lake, Jaguaribe River and Águas Minerais reservoir. METHODS: The environmental variables were water temperature, transparency, depth, degree of infestation of aquatic macrophytes, air temperature, wind speed, solar radiation and precipitation. The phytoplankton community was studied in terms of richness, density, diversity and evenness. The data were treated with analysis of variance and canonical correspondence analysis. RESULTS: Spatial variations in the data only occurred between ecosystems (p OBJETIVO: Este trabalho visou identificar que fatores ambientais interferem na estrutura sazonal fitoplanctônica em diferentes tipos de ecossistemas aquáticos tropicais. Coletas do fitoplâncton foram realizadas bimestralmente de agosto/2009 até junho/2010 em três pontos na lagoa Solon de Lucena, no rio Jaguaribe e no reservatório das Águas Minerais. MÉTODOS: As variáveis ambientais utilizadas neste estudo foram temperatura e transparência da água, profundidade, níveis de infestação de macrófitas aquáticas, temperatura do ar, velocidade do vento, radiação solar e precipitação pluviométrica. A comunidade fitoplanctônica foi estudada em nível de riqueza, densidade, diversidade e equitatividade. Os dados foram tratados através de análise de variância e ACC. RESULTADOS: A variação espacial dos dados foi observada apenas entre os ecossistemas (p < 0,05. O reservatório e o rio apresentaram fitoplâncton típico de ambientes lóticos com maior riqueza de Bacillariophyta (52,8% e 47,8%, respectivamente. Entretanto, a lagoa apresentou riqueza típica de ambientes lacustres com maior contribuição de Chlorophyta (52,8%. Este ecossistema diferente dos

  6. 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

  7. Diversity of Phytoplankton of a sub-tropical reservoir of Mizoram, northeast India

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    Bhushan Kumar Sharma

    2016-12-01

    Full Text Available Phytoplankton of Khawiva reservoir of Mizoram, northeast India (NEI revealed a total of 55 species; nearly concurrent mean monthly richness and high community similarities (vide Sørensen index during two years affirmed homogeneity in its species composition. Phytoplankton comprised dominant component (61.1±14.3% of net plankton and recorded wider density variations. Chlorophyta influenced phytoplankton abundance with quantitative importance of Staurastrum spp. >Xanthidium spp. >Cosmarium spp. in particular. Bacillariophyta formed subdominant group; Cryptophyta and Cyanophyta showed limited importance; and Euglenophyta and Dinophyta recorded poor densities. Phytoplankton is characterized by moderate species diversity, high evenness and low dominance but with wide variations. Richness, abundance and species diversity followed no definite patterns of monthly variations during two years. Insignificant influence of individual abiotic factors on phytoplankton assemblages coupled with low cumulative influence of fifteen abiotic parameters (vide CCA yielded little insight on overall role of abiotic parameters.

  8. 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...

  9. Social network analysis community detection and evolution

    CERN Document Server

    Missaoui, Rokia

    2015-01-01

    This book is devoted to recent progress in social network analysis with a high focus on community detection and evolution. The eleven chapters cover the identification of cohesive groups, core components and key players either in static or dynamic networks of different kinds and levels of heterogeneity. Other important topics in social network analysis such as influential detection and maximization, information propagation, user behavior analysis, as well as network modeling and visualization are also presented. Many studies are validated through real social networks such as Twitter. This edit

  10. 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...

  11. 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

  12. Phytoplankton dynamics within a discrete water mass off Cape Hatteras, North Carolina: the Lagrangian experiment

    Science.gov (United States)

    Redalje, D. G.; Lohrenz, S. E.; Verity, P. G.; Flagg, C. N.

    As part of the Department of Energy Ocean Margins Program, we examined the spatial and temporal variability in primary production and phytoplankton pigments during two cruises to the shelf waters between the Chesapeake Bay and Cape Hatteras. The first cruise was conducted in March 1996, reflecting well-mixed conditions just prior to the spring transition, while the second cruise was conducted during July 1996 when the water column was more stratified. During each cruise, primary production and high performance liquid chromatography (HPLC) pigments for the whole community and drogue. In March, production ranged from 0.50 to 0.65 g C m -2 d -1, with 52-62% of the production attributed to the smaller size fraction. About 50% of the total chlorophyll a (chl a) was found in the >8-μm size fraction. Pigment composition was dominated by chlorophylls a, c1 and c2, and fucoxanthin, indicating the importance of diatoms. In July, production was more variable, ranging from 0.38 to 2.09 g C m -2 d -1, with 41-83% of production attributed to the <8-μm size fraction. Rates increased over the 4-day study. Most of the chl a was found in the <8-μm size fraction. The phytoplankton pigments were dominated by chl a and fucoxanthin with chlorophylls c1 and c2, again indicating the importance of diatoms during this cruise.CHEMTAX (Mackey et al. CHEMTAX User's Manual: a program for estimating class abundances from chemical markers—application to HPLC measurements of phytoplankton pigments. CSIRO Marine Laboratories, Report 229, Hobart, 42 pp.), a factor analysis computer program, was used to examine phytoplankton community structure using marker pigments from our HPLC analyses to determine the relative importance of various taxa. In March, diatoms dominated whole water samples, with consistent contributions from dinoflagellates and cryptophytes. The <8-μm fraction was dominated by small diatoms, chrysophytes, cryptophytes and dinoflagellates. In July, diatoms were still present and

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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

  18. 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.

  19. A coupled physical-biological model of the Northern Gulf of Mexico shelf: model description, validation and analysis of phytoplankton variability

    Directory of Open Access Journals (Sweden)

    K. Fennel

    2011-01-01

    Full Text Available The Texas-Louisiana shelf in the Northern Gulf of Mexico receives large inputs of nutrients and freshwater from the Mississippi/Atchafalaya River system. The nutrients stimulate high rates of primary production in the river plume, which contributes to the development of a large and recurring hypoxic area in summer. The mechanistic links between hypoxia and river discharge of freshwater and nutrients are complex as the accumulation and vertical export of organic matter, the establishment and maintenance of vertical stratification, and the microbial degradation of organic matter are controlled by a non-linear interplay of factors. We present results from a realistic, 3-dimensional, physical-biological model that includes the processes thought to be of first order importance to hypoxia formation and demonstrate that the model realistically reproduces many features of observed nitrate and phytoplankton dynamics including observed property distributions and rates. We then contrast the environmental factors and phytoplankton source and sink terms characteristic of three model subregions that represent an ecological gradient from eutrophic to oligotrophic conditions. We analyze specifically the reasons behind the counterintuitive observation that primary production in the light-limited plume region near the Mississippi River delta is positively correlated with river nutrient input. We find that, while primary production and phytoplankton biomass are positively correlated with nutrient load, phytoplankton growth rate is not. This suggests that accumulation of biomass in this region is not primarily controlled bottom up by nutrient-stimulation, but top down by systematic differences in the loss processes. We hypothesize that increased retention of river water in high discharge years explains this phenomenon.

  20. Experimental manipulations of microbial food web interactions in a humic lake: shifting biological drivers of bacterial community structure.

    Science.gov (United States)

    Kent, Angela D; Jones, Stuart E; Lauster, George H; Graham, James M; Newton, Ryan J; McMahon, Katherine D

    2006-08-01

    A previous multiyear study observed correlations between bacterioplankton community composition (BCC) and abundance and the dynamics of phytoplankton populations and bacterivorous grazers in a humic lake. These observations generated hypotheses about the importance of trophic interactions (both top-down and bottom-up) for structuring bacterial communities in this lake, which were tested using two multifactorial food web manipulation experiments that separately manipulated the intensity of grazing and the composition of the phytoplankton community. Our results, combined with field observations, suggest that a hierarchy of drivers structures bacterial communities in this lake. While other studies have noted links between aggregate measures of phytoplankton and bacterioplankton communities, we demonstrate here correlations between succession of phytoplankton assemblages and BCC as assessed by automated ribosomal intergenic spacer analysis (ARISA). We used a novel approach linking community ARISA data to phylogenetic assignments from sequence analysis of 16S rRNA gene clone libraries to examine the responses of specific bacterial phylotypes to the experimental manipulations. The synchronous dynamics of these populations suggests that primary producers may mediate BCC and diversity through labile organic matter production, which evolves in quality and quantity during phytoplankton succession. Superimposed on this resource-mediated control of BCC are brief periods of intense bacterivory that impact bacterial abundance and composition.

  1. Metagenomic analysis of microbial communities and beyond

    DEFF Research Database (Denmark)

    Schreiber, Lars

    2014-01-01

    From small clone libraries to large next-generation sequencing datasets – the field of community genomics or metagenomics has developed tremendously within the last years. This chapter will summarize some of these developments and will also highlight pitfalls of current metagenomic analyses....... It will illustrate the general workflow of a metagenomic study and introduce the three different metagenomic approaches: (1) the random shotgun approach that focuses on the metagenome as a whole, (2) the targeted approach that focuses on metagenomic amplicon sequences, and (3) the function-driven approach that uses...... heterologous expression of metagenomic DNA fragments to discover novel metabolic functions. Lastly, the chapter will shortly discuss the meta-analysis of gene expression of microbial communities, more precisely metatranscriptomics and metaproteomics....

  2. 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. Copyright © 2016 Elsevier GmbH. All rights reserved.

  3. Inhomogeneous dominance patterns of competing phytoplankton groups in the wake of an island

    Directory of Open Access Journals (Sweden)

    D. Bastine

    2010-12-01

    Full Text Available We investigate the competition between two different functional groups of phytoplankton in the wake of an island close to a coastal upwelling region. We couple a simple biological model with three trophic levels and a hydrodynamic model of a von Kármán vortex street. The spatio-temporal abundance shows that the different phytoplankton groups dominate in different regions of the flow. The composition of the phytoplankton community varies e.g. for the different vortices. We study the mechanism leading to these inhomogeneous dominance patterns by investigating the nutrient transport in the flow and the interplay of hydrodynamic and biological time scales.

  4. Phytoplankton variation and its relation to nutrients and allochthonous organic matter in a coastal lagoon on the Gulf of Mexico

    Science.gov (United States)

    Aké-Castillo, José A.; Vázquez, Gabriela

    2008-07-01

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

  5. 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.

  6. 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.

  7. 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. Experiments consisted in two consecutive dust additions and samples were daily collected at different depths (−0.1, −5 and −10 m during one week, starting before each addition occurred. Data concerning HPLC pigment analysis on two size classes (< 3 and > 3 µm, electron transport rate (ETR versus irradiance curves, non-photochemical fluorescence quenching (NPQ and phytoplankton cell abundance (measured by flow cytometry, are presented and discussed in this paper. Results show that picophytoplankton mainly respond to the first dust addition, while the second addition leads to an increase of both pico- and nano-/microphytoplankton. Ecophysiological changes in the phytoplankton community are revealed, and an increase in NPQ development, as well as in pigment concentration per cell, follows the dust additions. ETR does not show large variations between dust-amended and control conditions, while biomass increases in response to the dust additions. Furthermore, the biomass increase observed during this mesocosm experiment allows us to attempt a quantitative assessment and parameterization of the onset of a phytoplankton bloom in a nutrient-limited ecosystem.

    These results are discussed focusing on the adaptation of picophytoplankton to such a nutrient-limited mixed layer system, as well as on size-dependent competition ability in phytoplankton.

  8. 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

    Science.gov (United States)

    Giovagnetti, V.; Brunet, C.; Conversano, F.; Tramontano, F.; Obernosterer, I.; Ridame, C.; Guieu, C.

    2012-12-01

    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. Experiments consisted in two consecutive dust additions and samples were daily collected at different depths (-0.1, -5 and -10 m) during one week, starting before each addition occurred. Data concerning HPLC pigment analysis on two size classes ( 3 µm), electron transport rate (ETR) versus irradiance curves, non-photochemical fluorescence quenching (NPQ) and phytoplankton cell abundance (measured by flow cytometry), are presented and discussed in this paper. Results show that picophytoplankton mainly respond to the first dust addition, while the second addition leads to an increase of both pico- and nano-/microphytoplankton. Ecophysiological changes in the phytoplankton community are revealed, and an increase in NPQ development, as well as in pigment concentration per cell, follows the dust additions. ETR does not show large variations between dust-amended and control conditions, while biomass increases in response to the dust additions. Furthermore, the biomass increase observed during this mesocosm experiment allows us to attempt a quantitative assessment and parameterization of the onset of a phytoplankton bloom in a nutrient-limited ecosystem. These results are discussed focusing on the adaptation of picophytoplankton to such a nutrient-limited mixed layer system, as well as on size-dependent competition ability in phytoplankton.

  9. Spatiotemporal heterogeneity of phytoplankton diversity and its relation to water environmental factors in the southern waters of Miaodao Archipelago, China

    Institute of Scientific and Technical Information of China (English)

    ZHENG Wei; LI Fen; SHI Honghua; HUO Yuanzi; LI Yan; CHI Yuan; GUO Zhen

    2016-01-01

    To study the water quality influenced by the anthropogenic activities and its impact on the phytoplankton diversity in the surface waters of Miaodao Archipelago, the spatiotemporal variations in phytoplankton communities and the environmental properties of the surface waters surrounding the Five Southern Islands of Miaodao Archipelago were investigated, based on seasonal field survey conducted from November 2012 to August 2013. During the survey, a total of 109 phytoplankton species from 3 groups were identified in the southern waters of Miaodao Archipelago, of which 77 were diatoms, 29 were dinoflagellates, and 3 were chrysophytes. Species number was higher in winter (73), moderate in autumn (70), but lower in summer (31) and spring (27). The species richness index in autumn (5.92) and winter (4.28) was higher than that in summer (2.83) and spring (1.41). The Shannon-Wiener diversity index was high in autumn (2.82), followed by winter (1.99) and summer (1.92), and low in spring (0.07). The species evenness index in autumn (0.46) and summer (0.39) was higher than that in winter (0.32) and spring (0.02). On the basis of principal component analysis (PCA) and redundancy analysis (RDA), we found that dissolved inorganic nitrogen (DIN) and chemical oxygen demand (COD) in spring, COD in summer, pH in autumn, and salinity and oil pollutant in winter, respectively, showed the strongest association with the distribution of phytoplankton diversity. The spatial heterogeneity of the southern waters of Miaodao Archipelago was quite obvious, and three zones, i.e., northeastern, southwestern and inter-island water area, were identified by cluster analysis (CA) based on key environmental variables.

  10. Ocean acidification impacts bacteria-phytoplankton coupling at low-nutrient conditions

    Science.gov (United States)

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

    2017-01-01

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

  11. 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.

    (September) phytoplankton counts range in Mandovi was 0.68 –1.36 X 10 sup(5) L sup(-1) and that of Zuari were 1.02 – 3.07 X 10 sup(5) L sup(-1). Similar pattern was also observed in pigment distribution. In Mandovi Chl a during non monsoon period was as high...

  12. Effects of “submerged aeration systems” on water quality and phytoplankton community structure in Portunus trituberculatus culture ponds%“底充式增氧”技术对梭子蟹养殖池塘水质环境及浮游植物群落结构的影响

    Institute of Scientific and Technical Information of China (English)

    傅彩萍; 郑忠明; 金忠文; 郝锵; 陆开宏

    2012-01-01

    5 mg/L, while that of the control pond at (4. 28~6. 45) mg/ L; and at the later period of cultivation, the mass concentration of ammonia nitrogen of the experimental pond was 0.140 mg/L, much lower than that of the control pond (1. 360 mg/L). (2) the cell abundance of the algae in the experimental pond is much higher than that of the control pond, and that of green algae is 8. 79 X 108 ind/L; MDS sequencing, ANOSIM test and SIMPER analysis show significant differences of phytoplankton community structure between the two ponds; at the mid and later period of cultivation, the phytoplankton community structure is stable in the experimental pond and unstable in the control ponds; the dissimilarity of the two ponds is as high as 84. 44%, and the dominant species of the former are Oocystis sp. And Phormidium sp. , while that of the latter are diatom and cyanobacteria 5 Bio-Env analysis show that the correlation between the zooplankton abundance and environmental viable combination with dissolved oxygen is the strongest. (3) Compared to the traditional waterwheel aeration system, the effects of "submerged aeration system" to improve the DO mass concentration of the aquaculture pond are obvious, and it can also improve the water quality and stabilize the community structure of the algae in the farming pond during the cultivation.

  13. Studies on relationships between phytoplankton community and environment factors of rivers and reservoirs in Tianjin%天津市河流和水库浮游植物群落与水环境因子关系的研究

    Institute of Scientific and Technical Information of China (English)

    杨华; 傅志茹; 李春艳; 张韦

    2012-01-01

    Sampling survey on 5 rivers and 4 reservoirs in Tianjin were carried out in May, July and September 2009 to study the relationship between phytoplankton community and environment factors of rivers and reservoirs in Tianjin. The result showed that there' were 100 species, 7 phylum phytoplankton in rivers, while 81 species, 8 phylum phytoplankton in reservoirs. Dominant species were Chlorophyta and Cyanophyta in rivers, Bacillariophyta and Cyanophyta in reservoirs. Secchi -depth (SD) , pH, total phosphorus (TP) , bicarbonate alkalinity ( Bi -alk) were significant different between rivers and reserviors (P <0. 01 ). Environmental factors which affected phytoplankton density in rivers were: Zoo-plankton abundance (Zoo) , potassium permanganate index ( COD ) , ammonianitrogen ( NH3-N ) , carbonate alkalinity ( Ca-alk) , phosphate concentrations ( PO43-) , TP inturn. Those affected phytoplankton in reserviors were: Bi - alk, Ca2+ , NH3 -N, SD, dissolved oxygen (DO) , water depth (H) , chlorophyll (a, b) , total alkalinity (alk) , total hardness (DH) , pH in turn.%为探明天津市河流、水库浮游植物群落结构及其与环境因子的关系,于2009年5月、7月、9月对天津市的5条河流和4个水库进行采样分析.结果表明,天津市河流浮游植物为7门100种,优势种为绿藻、蓝藻;水库为8门81种,优势种为硅藻、蓝藻.环境因子在河流和水库间差异极显著的为透明度、pH、总磷和重碳酸盐碱度(P<0.01).影响浮游植物群落结构的环境因子,河流依次为:浮游动物丰度、高锰酸盐指数、氨氮、碳酸盐碱度、磷酸盐浓度、总磷;水库依次为:重碳酸盐碱度、钙离子浓度、氨氮、透明度、溶解氧、水深、叶绿素(a、b)、总碱度、总硬度、pH.

  14. Seasonal variation of the phytoplankton community structure in the São João River, Iguaçu National Park, Brazil Variação sazonal da estrutura da comunidade fitoplanctônica no Rio São João, Parque Nacional do Iguaçu, Brasil

    Directory of Open Access Journals (Sweden)

    JC. Bortolini

    2013-02-01

    Full Text Available The limnological characteristics and the phytoplankton community of the pelagic region of the São João River, tributary of the Iguaçu River, Iguaçu National Park were analyzed from August 2008 to July 2009. 221 taxa were identified and the Bacillariophyceae class was the most representative. Bacillariophyceae and Chrysophyceae were the dominant classes in density and Bacillariophyceae in biovolume. According to the DCA carried out for phytoplankton density and biovolume, significant differences were identified between the periods, and between the sites and study periods, respectively. The highest richness of species reached 40 taxa in September 2008 at station 1. The Shannon-Wiener diversity indexes and evenness, calculated from the density of phytoplankton, were temporally heterogeneous and spatially similar. In general, the significant temporal variations in the composition of the phytoplankton community were due to variations in limnological conditions, mainly temperature, transparency and nutrients. Spatially the structure was more similar due to the proximity among the stations. Moreover, the similarity of the distribution of communities in lotic environments were due to the unidirectional flow.As características limnológicas e a comunidade fitoplanctônica na região pelágica do Rio São João, tributário do Rio Iguaçu, Parque Nacional do Iguaçu, foram analisadas de agosto de 2008 a julho de 2009. Foram identificados 221 táxons, sendo Bacillariophyceae a classe mais representativa. Bacillariophyceae e Chrysophyceae foram as classes dominantes em densidade e Bacillariophyceae, em biovolume. De acordo com a DCA realizada para densidade e biovolume, foram identificadas diferenças significativas entre os períodos e entre os locais e períodos estudados, respectivamente. A maior riqueza de espécies foi alcançada em setembro de 2008 com 40 táxons na estação 1. O índice de diversidade de Shannon-Wiener e a equitabilidade

  15. River Flow Control on the Phytoplankton Dynamics of Chesapeake Bay

    Institute of Scientific and Technical Information of China (English)

    YU Qingyun; WANG You; TANG Xuexi; LI Ming

    2013-01-01

    Recent observations support an emerging paradigm that climate variability dominates nutrient enrichment in costal ecosystems,which can explain seasonal and inter-annual variability of phytoplankton community composition,biomass (Chl-a),and primary production (PP).In this paper,we combined observation and modeling to investigate the regulation of phytoplankton dynamics in Chesapeake Bay.The year we chose is 1996 that has high river runoff and is usually called a ‘wet year’.A 3-D physical-biogeochemical model based on ROMS was developed to simulate the seasonal cycle and the regional distributions of phytoplankton biomass and primary production in Chesapeake Bay.Based on the model results,NO3 presents a strong contrast to the river nitrate load during spring and the highest concentration in the bay reaches around 80mmol N m3.Compared with the normal year,phytoplankton bloom in spring of 1996 appears in lower latitudes with a higher concentration.Quantitative comparison between the modeled and observed seasonal averaged dissolved inorganic nitrogen concentrations shows that the model produces reliable results.The correlation coefficient r2 for all quantities exceeds 0.95,and the skill parameter for the four seasons is all above 0.95.

  16. 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.

  17. Spatial and temporal assessment of the initial pattern of phytoplankton population in a newly built coastal reservoir

    Science.gov (United States)

    Ren, Xiangyu; Yang, Kai; Che, Yue; Wang, Mingwei; Zhou, Lili; Chen, Liqiao

    2016-09-01

    For decades, the main threat to the water security of a metropolis, such as the city of Shanghai, has been the rapidly growing demand for water and at the same time, the decrease in water quality, including eutrophication. Therefore Shanghai shifted the preferred freshwater source to the Yangtze Estuary and constructed the Qingcaosha Reservoir, which is subject to less eutrophic water from the Yangtze River. To assess the population of phytoplankton for the first time in the newly built reservoir, this study improved an integrated method to assess the phytoplankton pattern in large-water-area reservoirs and lakes, using partial triadic analysis and Geographic Information Systems. Monthly sampling and monitoring from 10 stations in the reservoir from July 2010 to December 2011 were conducted. The study examined the common pattern of the phytoplankton population structure and determined the differences in the specific composition of the phytoplankton community during the transition period of the reservoir. The results suggest that in all but three sampling stations in the upper parts of Qingcaosha Reservoir, there was a strong common compromise in 2011. The two most important periods occurred from late summer to autumn and from winter to early spring. The former was characterized by the dominance of cyanobacteria, whereas the latter was characterized by the dominance of both chlorophyta and diatoms. Cyanobacteria ( Microcystis spp. as the main genus) were the monopolistic dominant species in the summer after reservoir operation. The statistical analysis also indicated the necessity for regular monitoring to focus on the stations in the lower parts of the reservoir and on several limited species.

  18. Short-term variability in halocarbons in relation to phytoplankton pigments in coastal waters of the central eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Roy, R.

    Halocarbons released from oceans are known to be important in the atmospheric processes. Their abundance in seawater is influenced by water column conditions and phytoplankton community. In the present study halocarbon abundances together...

  19. Spring phytoplankton variability along a south coast of Sfax at the water-sediment interface (Tunisia, Eastern Mediterranean Sea

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    Amira Rekik

    2016-02-01

    Full Text Available Objective: To compare the composition of the phytoplankton classes during the two spring studies, to study whether the spatial distribution of the phytoplankton is stable or not between spring 2010 and spring 2011 and to estimate the abiotic factor that mostly affects the structure and the richness of phytoplankton. Methods: Phytoplankton sub-samples were counted under an inverted microscope using the Utermöhl method. Phytoplankton identification was made from morphological criteria after consulting various keys. Results: Results showed a significant difference from spring 2010 to spring 2011 regarding nitrate/phosphate ratio, with high value in spring 2010 (30.19 ± 25.70. Relatively low nitrate/phosphate ratio (1.13 ± 0.53 during spring 2011 might result from phosphogypsum. Phytoplankton was characterised by the proliferation of Bacillariophyceae (46%–78% of the total microphytoplankton and by the large number of Euglenophyceae. Thirty two Bacillariophyceae species were identified at every station, represented essentially by Amphora sp., Navicula sp., Coscinodiscus sp. and Grammatophora sp. The results advise that Bacillariophyceae are usually adapted to particular ecological environment. Conclusions: This study shows that hydrological conditions in the south coast of Sfax present a high spatial and seasonal variability. The phytoplankton community distribution showed clear variations along the coastal stations during a spring cruises conducted in May 2010 and May 2011. The phytoplankton community found along the coast was dominated by opportunistic Bacillariophyceae species.

  20. Temporal and spatial distribution of phytoplankton functional groups and role of environment factors in a deep subtropical reservoir

    Science.gov (United States)

    Li, Lei; Li, Qiuhua; Chen, Jing'an; Wang, Jingfu; Jiao, Shulin; Chen, Fengfeng

    2017-09-01

    Phytoplankton and environment factors were investigated in 2015 and phytoplankton functional groups were used to understand their temporal and spatial distribution and their driving factors in Wanfeng Reservoir. Seventeen functional groups (B, D, E, F, G, J, Lo, MP, P, S1, T, W1, W2, X1, X2, Xph, Y) were identified based on 34 species. The dominant groups were: J/B/P/D in dry season, X1/J/Xph/G/T in normal season and J in flood season. Phytoplankton abundance ranged from 5.33×104 cells/L to 3.65×107 cells/L, with the highest value occurring in flood season and lowest in dry season. The vertical profile of dominant groups showed little differentiation except for P, which dominated surface layers over 20 m as a result of mixing water masses and higher transparency during dry season. However, the surface waters presented higher values of phytoplankton abundance than other layers, possibly because of greater irradiance. The significant explaining variables and their ability to describe the spatial distribution of the phytoplankton community in RDA differed seasonally as follows: dry season, NH4-N, NO3-N, NO2-N, TN:TP ratio and transparency (SD); normal season, temperature (WT), water depth, TN, NH4-N and NO3-N; flood season, WT, water depth, NO3-N and NO2-N. Furthermore, nitrogen, water temperature, SD and water depth were significant variables explaining the variance of phytoplankton communities when datasets included all samples. The results indicated that water physical conditions and hydrology were important in phytoplankton community dynamics, and nitrogen was more important than phosphorus in modifying phytoplankton communities. Seasonal differences in the relationship between the environment and phytoplankton community should be considered in water quality management.

  1. Phytoplankton biomass, production and potential export in the North Water

    Science.gov (United States)

    Klein, Bert; LeBlanc, Bernard; Mei, Zhi-Ping; Beret, Rachel; Michaud, Josée; Mundy, C.-J.; von Quillfeldt, Cecilie H.; Garneau, Marie-Ève; Roy, Suzanne; Gratton, Yves; Cochran, J. Kirk; Bélanger, Simon; Larouche, Pierre; Pakulski, J. Dean; Rivkin, Richard B.; Legendre, Louis

    The seasonal patterns of phytoplankton biomass and production were determined in the North Water, located between Greenland and Ellesmere Island (Canadian Arctic), in August 1997, April-July 1998, and August-September 1999. The patterns differed among the four defined regions of this large polynya, i.e. North (>77.5°N), East (>75°W), West (5 μm) fraction dominated the biomass and production during the bloom. During July, August, and September, biomass and production decreased over the whole region, with the highest biomass, dominated by large cells, occurring in the North. The annual particulate and dissolved phytoplankton production were the highest ever reported for the high Arctic, reaching maximum values of 254 and 123 g C m -2 yr -1, respectively, in the East. Rates in the North and West were considerably lower than in the East (ca. two- and three-fold, respectively). The f-ratios (i.e. ratio of new to total production), derived from the size structure of phytoplankton, were high north of 76°N (0.4-0.7). Regionally, this indicated a high potential export of particulate organic carbon ( EPOC) from the phytoplankton community to other trophic compartments and/or downwards in the East (155 g C m -2 yr -1), with lower values in the North and West (i.e. 77 and 42 g C m -2 yr -1, respectively). The seasonal and spatial patterns of EPOC were consistent with independent estimates of potential carbon export. Phytoplankton biomass and production were generally dominated by the large size fraction, whereas EPOC seemed to be dominated by the large size fraction early in the season and by the small size fraction (<5 μm) from June until the end of the growing season.