High-performance Liquid Chromatography Pigment Analysis Research Articles

Concentration and distribution of phytoplankton nitrogen and carbon in the Northwest Atlantic and Indian Ocean: A simple model with applications in satellite remote sensing

Despite the critical role phytoplankton play in marine biogeochemical cycles, direct methods for determining the content of two key elements in natural phytoplankton samples, nitrogen (N) and carbon (C), remain difficult, and such observations are sparse. Here, we extend an existing approach to derive phytoplankton N and C indirectly from a large dataset of in-situ particulate N and C, and Turner fluorometric chlorophyll-a (Chl-a), gathered in the off-shore waters of the Northwest Atlantic and the Arabian Sea. This method uses quantile regression (QR) to partition particulate C and N into autotrophic and non-autotrophic fractions. Both the phytoplankton C and N estimates were combined to compute the C:N ratio. The algal contributions to total N and C increased with increasing Chl-a, whilst the C:N ratio decreased with increasing Chl-a. However, the C:N ratio remained close to the Redfield ratio over the entire Chl-a range. Five different phytoplankton taxa within the samples were identified using data from high-performance liquid chromatography pigment analysis. All algal groups had a C:N ratio higher than Redfield, but for diatoms, the ratio was closer to the Redfield ratio, whereas for Prochlorococcus, other cyanobacteria and green algae, the ratio was significantly higher. The model was applied to remotely-sensed estimates of Chl-a to map the geographical distribution of phytoplankton C, N, and C:N in the two regions from where the data were acquired. Estimates of phytoplankton C and N were found to be consistent with literature values, indirectly validating the approach. The work illustrates how a simple model can be used to derive information on the phytoplankton elemental composition, and be applied to remote sensing data, to map pools of elements like nitrogen, not currently provided by satellite services.

Source and quantity of carbon influence its sequestration in Rostherne Mere (UK) sediment: a novel application of stepped combustion radiocarbon analysis

We explored the roles of phytoplankton production, carbon source, and human activity on carbon accumulation in a eutrophic lake (Rostherne Mere, UK) to understand how changes in nutrient loading, algal community structure and catchment management can influence carbon sequestration in lake sediments. Water samples (dissolved inorganic, organic and particulate carbon) were analysed to investigate contemporary carbon sources. Multiple variables in a 55-cm sediment core, which represents the last ~ 90 years of accumulation, were studied to determine historical production rates of algal communities and carbon sources. Fluctuations in net primary production, inferred from sedimentary diatom abundance and high-performance liquid chromatography (HPLC) pigment methods, were linked to nutrient input from sewage treatment works (STW) in the catchment. Stepped combustion radiocarbon (SCR) measurements established that lake sediment contains between 11% (~ 1929 CE) and 69% (~ 1978 CE) recalcitrant carbon, with changes in carbon character coinciding with peaks in accumulation rate and linked to STW inputs. Catchment disturbance was identified by radiocarbon analysis, and included STW construction in the 1930s, determined using SCR analysis, and recent nearby highway construction, determined by measurements on dissolved organic carbon from the lake and outflow river. The quantity of autochthonous carbon buried was related to diatom biovolume accumulation rate (DBAR) and decreased when diatom accumulation rate and valve size declined, despite an overall increase in net carbon production. HPLC pigment analysis indicated that changes in total C deposition and diatom accumulation were related to proliferation of non-siliceous algae. HPLC results also indicated that dominance of recalcitrant carbon in sediment organic carbon was likely caused by increased deposition rather than preservation factors. The total algal accumulation rate controlled the sediment organic carbon accumulation rate, whereas DBAR was correlated to the proportion of each carbon source buried.

Comparison of HPLC Pigment Analysis and Microscopy in Phytoplankton Assessment in the Seomjin River Estuary, Korea

The distribution of microalgal species in estuaries shows marked gradients because of the mixing of marine and fresh water during tidal exchanges. To assess the spatio-temporal distribution of phytoplankton in the Seomjin River estuary (SRE), Korea, we investigated the seasonal phytoplankton communities along a salinity gradient in the estuary using both high performance liquid chromatography (HPLC) pigment analysis and light microscopy. Both types of analysis indicated that marine planktonic diatoms generally dominated at downstream sites having salinities >10, whereas freshwater species dominated at upstream sites having salinities <5. High levels of the pigments fucoxanthin and alloxanthin were found at upstream sites in the SRE in late spring. During summer, relatively high levels of the pigment peridinin were present in downstream areas of the SRE, and relatively high levels of diatoms occurred in upstream areas. In autumn, small Cryptomonas species were found in high abundance based on microscopic analysis, while CHEMTAX analysis of photosynthetic pigments showed relatively high concentrations of the diatom pigment fucoxanthin, implying the co-occurrence of a small unidentified phytoplankton. During winter, when the estuarine waters were well mixed, both the microscopic and CHEMTAX analyses showed that diatoms dominated at most stations. Seasonal and horizontal gradients in environmental conditions were clearly influenced by the salinity and nutrient loadings, especially the nitrate+nitrite and silicate concentrations. In particular, the ratio of photoprotective carotenoid pigments (PPCs) to photosynthetic carotenoid pigments (PSCs) was relatively low during all four seasons. This was predominately because of the high productivity of diatoms, which have a very low ratio of PPCs to PPSs. The SRE is a favorable habitat for diatoms because it is a high turbulence area having rapid water movement as a result of tidal changes. Overall, there was consistency in the data derived from the microscopy and chemotaxonomy analyses, suggesting that both methods are useful for analysis of the phytoplankton community structure in this complex estuarine and coastal water ecosystem.

Temporal and spatial variation of phytoplankton in Admiralty Bay, South Shetlands: the dynamics of summer blooms shown by pigment and light microscopy analysis

We conducted an integrated study of phytoplankton taxonomic composition, biomass and physicochemical properties of the water in Admiralty Bay, South Shetlands. The aim of the study was to provide detailed information on phytoplankton composition and diversity related to relevant environmental conditions. High-performance liquid chromatography pigment analysis and microscopy were performed in the summers of 2007 and 2009–2010. Results for 2007 showed a typical high-nutrient, low-chlorophyll system. Total carbon biomass and cell numbers were dominated by nanoflagellates, while diatoms made up 1.2–4.5 % of the total algal numbers and contributed a maximum of 23.4 % to the total cell carbon. A small algal bloom occurred in the center of the bay, with chlorophyll a values of ~1.0 µg l−1. The prevalent pigment was 19′-hexanoyloxyfucoxanthin, characteristic of the Prymnesiophyceae. In January 2010, the values of chlorophyll a (8–24 µg l−1) and cell carbon (150 µg l−1) were the highest ever recorded for Admiralty Bay. In general the algal populations were dominated numerically by nanoflagellates, but a bloom of diatoms (maximum 30 % of total cells and 50 % of total cell carbon) was observed. Diatoms were dominated by those of micro-size: Thalassiosira ritscheri and T. antarctica. The dominant pigment was fucoxanthin, mainly found in diatoms. The diatom bloom could be related to the southeast wind direction, stable water column conditions and an inflow of diatom-rich waters from the Bransfield Strait, while the input of high-turbidity, low-salinity water from melting glaciers and strong katabatic northwest winds could favor nanoflagellates.

Protist community composition in the Pacific sector of the Southern Ocean during austral summer 2010

Knowledge about the protist diversity of the Pacific sector of the Southern Ocean is scarce. We tested the hypothesis that distinct protist community assemblages characterize large-scale water masses. Therefore, we determined the composition and biogeography of late summer protist assemblages along a transect from the coast of New Zealand to the eastern Ross Sea. We used state of the art molecular approaches, such as automated ribosomal intergenic spacer analysis and 454-pyrosequencing, combined with high-performance liquid chromatography pigment analysis to study the protist assemblage. We found distinct biogeographic patterns defined by the environmental conditions in the particular region. Different water masses harbored different microbial communities. In contrast to the Arctic Ocean, picoeukaryotes had minor importance throughout the investigated transect and showed very low contribution south of the Polar Front. Dinoflagellates, Syndiniales, and small stramenopiles were dominating the sequence assemblage in the Subantarctic Zone, whereas the relative abundance of diatoms increased southwards, in the Polar Frontal Zone and Antarctic Zone. South of the Polar Front, most sequences belonged to haptophytes. This study delivers a comprehensive and taxon detailed overview of the protist composition in the investigated area during the austral summer 2010.

Phylogeny and characterisation of Nannochloropsis oceanica var. sinensis var. nov. (Eustigmatophyceae), a new oleaginous alga from China

Cao S., Zhang X., Fan X., Qiao H., Liang C., Xu D., Mou S., Wang W. and Ye N. 2013. Phylogeny and characterisation of Nannochloropsis oceanica var. sinensis var. nov. (Eustigmatophyceae), a new oleaginous alga from China. Phycologia 52: 573–577. DOI: 10.2216/13-164.1Strain QD001, previously identified as Chlorella, was examined using molecular phylogenetic analysis (nuclear-encoded 18S rRNA, ITS, rbcL), ITS2 secondary structure, light and electron microscopy, high-performance liquid chromatography pigment analysis, and fatty acid analysis. The strain was shown to be phylogenetically distinct from all described taxa, and the strain was named Nannochloropsis oceanica var. sinensis var. nov. DNA sequences from the new variety were very similar to GenBank sequences for N. maritima nomen nudum.

Phytoplankton community during a coccolithophorid bloom in the Patagonian Shelf: microscopic and high-performance liquid chromatography pigment analyses

We describe the phytoplankton community and biomass during a summer coccolithophorid bloom sampled over the Patagonian shelf (48.5°S–50.5°S). Those phytoplankton species can contribute to the flux of calcium carbonate out of surface waters. Results from both microscope and high-performance liquid chromatography (HPLC) analysis are shown to complement information on the phytoplankton community. From CHEMTAX analysis of HPLC data, the most important organisms and groups identified were the coccolithophoridEmiliania huxleyi, the haptophytePhaeocystis antarctica, dinoflagellates, diatoms, cryptophytes, prasinophytes and cyanobacteria. Phytoplankton microscope counts were converted into phytoplankton group-specific biovolume estimates. Although some microscope-identified taxa could not be determined by CHEMTAX, e.g. the autotrophic ciliateMyrionecta rubra, cluster analyses from both techniques showed similar results for the main groups. BothEmiliania huxleyicell concentration and biomass, and the pigment 19′-hexanoyloxyfucoxanthin were the most important biological features during the sampling period. At surface, nitrate was moderately high (0.2–4.2 µM) in coccolithophorid-dominated samples, whereas phosphate (<0.33 µM) and silicate (<1.35 µM) concentrations were low. Among the environmental factors low Si:N ratios were mainly associated with the dominance ofE. huxleyi. Competition and probably differential grazing could also promote a coccolithophorid outgrowth over other photoautotrophs during the summer season in the Patagonian shelf.

Examples of high performance liquid chromatography (HPLC) application in marine ecology studies in the northern Adriatic

Photosynthetic pigments have proved to be useful biomarkers of the abundance, composition and physiological status of the phytoplankton biomass in the marine environment. Using HPLC pigment analysis, we determined phytoplankton community structure in three different marine environments: in the area of a fish farm, in the area of sewage outlets, and in the mucilaginous aggregates. At the reference site we observed seasonal changes with prevalence of fucoxanthin-containing phytoplankton (i.e. diatoms) during winter/spring and autumn. In the fish farm area the concentration of chlorophyll a degradation products was higher, whereas in the locally enriched environment of sewage outlets we observed only small changes in taxonomic composition and phytoplankton biomass. The impact of season is more expressed than the impact of sewage discharge. With the use of HPLC pigment analysis we determined the development of phytoplankton community in different stages of mucilage aggregates. Phytoplankton biomass was composed primarily of diatoms, and as the aggregates aged, diatoms increased in the relative biomass. Our examples have proven the usefulness and suitability of HPLC pigment analysis in marine ecology studies.

Characteristics of phytoplankton community structure during and after a bloom of the dinoflagellate Scrippsiella trochoidea by HPLC pigment analysis

A bloom of the dinoflagellate Scrippsiella trochoidea was detected for the first time in inner Tolo Harbor, Hong Kong in 2 000. 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 phytoplankton 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 prevalence of fucoxanthin. Phytoplankton pigment markers also revealed the presence of other minor phytoplankton assemblages such as cryptomonads and blue-green algal.

Short-time scale variation of phytoplankton succession in Lisbon bay (Portugal) as revealed by microscopy cell counts and HPLC pigment analysis

The phytoplankton distribution and composition in Lisbon bay was studied, at a short time scale based on a weekly sampling, during one year (April 2004 – May 2005), using microscopic examination and pigment analysis with high-performance liquid chromatography (HPLC). This work is a contribution to the knowledge on species succession and ecology of coastal communities. The frequency of the sampling permitted monitoring peak blooming and decaying, a process which frequently occurred within 1 –2 weeks. Cell counts determined that the classes Dinophyceae, Bacillariophyceae and Prymnesiophyceae dominated the assemblages. Maxima abundances and diversity of phytoplankton were observed from spring to autumn. HPLC analysis reflected the major seasonal variations observed by the cell counts and in addition detected the presence of four small sized phytoplankton classes that were not identified by microscopy. Phytoplankton counts were essential to identify the main contributing species to total chlorophyll a. Fucoxantin, peridinin and 19′-hexanoyloxyfucoxanthin appeared as good indicators for diatoms, dinoflagellates and coccolithophores, respectively, with synchronized seasonal variations and significant positive correlations.

Microphytobenthos of the Dogger Bank: a comparison between shallow and deep areas using phytopigment composition of the sediment

The surface sediment characteristics related to benthic microalgae primary production were studied at the Dogger Bank, North Sea, in order to evaluate the potential role of microphytobenthos as a food source for the macrobenthic fauna. Twenty-one stations were sampled in July 2001 and May 2002, with water depth ranging from 16.3 to 68.5 m. High-performance liquid chromatography pigment analyses revealed that concentrations of chlorophyll a, chlorophyll c and fucoxanthin are mainly associated with benthic diatom flora at most parts of the Dogger Bank. High percentage of phytopigments (>50%) was firmly attached to sand grains at the stations shallower than 40 m water depth. The deeper stations were characterized by a phytopigment composition originating from pelagic phytoplankton settled on the sea floor. Qualitative microscopy showed that the benthic microflora on top of the Bank mainly consists of small diatoms (5–10 μm), such as e.g., Diploneis spp., living attached to the sand grains. The results are discussed concerning possible implications for ecology and biogeochemistry of the Dogger Bank area.

Estimation of phytoplankton biomass using HPLC pigment analysis in the southwestern Black Sea

Abstract The phytoplankton population of the southwestern Black Sea in May 2001 was studied by taxonomic analysis using microscopic examination and by pigment analyses using high-performance liquid chromatography (HPLC). Pigment data, which identified phytoplankton assemblages dominated by dinoflagellates, diatoms and coccolithophores in May 2001, were compared to phytoplankton cell counts and biomass. There were significant (p

Late summer community composition and abundance of photosynthetic picoeukaryotes in Norwegian and Barents Seas

We investigated marine picoeukaryotic diversity (cells <3 µm) in samples collected in late summer 2002 at the boundary between the Norwegian, Greenland, and Barents Seas. The two main Arctic and Atlantic water masses in this region are separated by the polar front. We combined total counts of picoeukaryotes assemblages by flow cytometry and epifluorescence microscopy with taxa detection by tyramide signal amplification-fluorescent in situ hybridization (TSAFISH) and high performance liquid chromatography (HPLC) pigment analyses. The picoeukaryotic community was primarily composed of photoautotrophs (75% of the cells on average). Members of the division Chlorophyta, in particular the species Micromonas pusilla (Butcher) Manton and Parke, were the major components in truly Arctic waters (32% of the picoeukaryotes, maximum 3,200 cells ml21). M. pusilla was also well represented in coastal waters and at the polar front (25% of the picoeukaryotes, maximum 9,100 cells ml21). Haptophyta were prominent in more typical Atlantic waters (up to 35% of the picoeukaryotes, maximum 4,500 cells ml21). Quantification of haptophyte biomass by HPLC pigment analyses and CHEMTAX, and haptophyte abundances by TSA-FISH were in good agreement. This confirms previous studies, which suggested that M. pusilla is a dominant contributor of picoeukaryotic communities in both coastal and nutrient rich environments, whereas haptophytes seem to be more important in open seawaters.

Responses of phytoplankton and heterotrophic bacteria in the northwest subarctic Pacific to in situ iron fertilization as estimated by HPLC pigment analysis and flow cytometry

To verify the hypothesis that the growth of phytoplankton in the Western Subarctic Gyre (WSG), which is located in the northwest subarctic Pacific, is suppressed by low iron (Fe) availability, an in situ Fe fertilization experiment was carried out in the summer of 2001. Changes over time in the abundance and community structure of phytoplankton were examined inside and outside an Fe patch using phytoplankton pigment markers analyzed by high-performance liquid chromatography (HPLC) and flow cytometry (FCM). In addition, the abundance of heterotrophic bacteria was also investigated by FCM. The chlorophyll a concentration was initially ca. 0.9 μg l −1 in the surface mixed layer where diatoms and chlorophyll b-containing green algae (prasinophytes and chlorophytes) were predominant in the chlorophyll biomass. After the iron enrichment, the chlorophyll a concentration increased up to 9.1 μg l −1 in the upper 10 m inside the Fe patch on Day 13. At the same time, the concentration of fucoxanthin (a diatom marker) increased 45-fold in the Fe patch, and diatoms accounted for a maximum 69% of the chlorophyll biomass. This result was consistent with a microscopic observation showing that the diatom Chaetoceros debilis had bloomed inside the Fe patch. However, chlorophyllide a concentrations also increased in the Fe patch with time, and reached a maximum of 2.2 μg l −1 at 5 m depth on Day 13, suggesting that a marked abundance of senescent algal cells existed at the end of the experiment. The concentration of peridinin (a dinoflagellate marker) also reached a maximum 24-fold, and dinoflagellates had contributed significantly (>15%) to the chlorophyll biomass inside the Fe patch by the end of the experiment. Concentrations of 19′-hexanoyloxyfucoxanthin (a prymnesiophyte marker), 19′-butanoyloxyfucoxanthin (a pelagophyte marker), and alloxanthin (a cryptophyte marker) were only incremented a few-fold increment inside the Fe patch. On the contrary, chlorophyll b concentration reduced to almost half of the initial level in the upper 10 m water column inside the Fe patch at the end of the experiment. A decrease with time in the abundance of eukaryotic ultraphytoplankton (<ca. 5 μm in size), in which chlorophyll b-containing green algae were possibly included was also observed by FCM. Overall, our results indicate that Fe supply can dramatically alter the abundance and community structure of phytoplankton in the WSG. On the other hand, cell density of heterotrophic bacteria inside the Fe patch was maximum at only ca. 1.5-fold higher than that outside the Fe patch. This indicates that heterotrophic bacteria abundance was little respondent to the Fe enrichment.

The effects of a PSII inhibitor on phytoplankton community structure as assessed by HPLC pigment analyses, microscopy and flow cytometry

Measurements of the stress imposed by a PSII inhibiting herbicide (Irgarol 1051 ®) on the composition of a phytoplankton community was investigated by comparing chemotaxonomy, as determined by high performance liquid chromatography (HPLC), optical microscopy and analytical flow cytometry (AFC). Changes in community structure were induced in microcosms containing a natural marine phytoplankton community exposed to different concentrations of Irgarol 1051 ® (0.5 and 1.0 μg l −1). Microcosms were maintained under controlled laboratory conditions in semi-continuous culture over 120 h. Class-specific phytoplankton biomass (chlorophyll a) was estimated using CHEMTAX analyses of pigment concentrations. Microscopic identification and carbon content estimates were cross-correlated with CHEMTAX and also with AFC enumeration/size classifications of major phytoplankton groups. CHEMTAX–HPLC analyses and microscopy results demonstrated that prasinophytes and prymnesiophytes were the most affected groups following exposure to Irgarol 1051 ®. The selective reductions in both classes as estimated by both techniques revealed similar trends. Results for chlorophytes and dinoflagellates showed these groups to be most tolerant to Irgarol 1051 ®. Indeed, class-specific biomass for chlorophytes as determined by CHEMTAX and microscopy were correlated ( R 2 = 0.53) which demonstrated an increase in both abundance and carbon content following exposures to Irgarol 1051 ®. Abundances of nanoeukaryotes as determined by microscopy afforded good agreement with results from AFC ( R 2 = 0.8), although for picoeukaryotes, abundances were underestimated by microscopy ( R 2 = 0.43). The relative performance of the selected techniques is discussed.

Karenia umbella sp. nov. (Gymnodiniales, Dinophyceae), a new potentially ichthyotoxic dinoflagellate species from Tasmania, Australia

A new, potentially ichthyotoxic gymnodinioid dinoflagellate, Karenia umbella de Salas, Bolch & Hallegraeff, is described from Tasmanian coastal waters, Australia. It is characterized by light and electron microscopy of field samples and laboratory cultures, as well as large-subunit ribosomal DNA sequences and high-performance liquid chromatography pigment analyses of two cultured strains. The new Karenia species has a straight apical groove and contains fucoxanthin derivative carotenoid pigments, typical of the genus. Karenia umbella differs from its closest relative K. longicanalis in its larger size, longer epicone with a finger-like sulcal intrusion, asymmetrically shaped hypocone, irregularly shaped chloroplasts, and presence of six or eight radial furrows on the epicone surface. It differs from K. digitata in its significantly larger size and the shape of the epicone and hypocone. Genetically, this species is distinct from the dorsoventrally flattened Karenia species K. mikimotoi, K. brevis, and K. brevisulcata.

HPLC pigment analysis of marine phytoplankton during a red tide occurrence in Tolo Harbour, Hong Kong

A red tide was detected in the inner parts of Tolo Harbour, Hong Kong, in November 2000. Water samples were collected from a fixed station at the centre of the red tide patch for microscopic analysis of phytoplankton community composition and high performance liquid chromatography (HPLC) analysis of phytoplankton pigments. At the peak of the red tide on 24 November 2000, phytoplankton was dominated by the dinoflagellate Scrippsiella trochoidea. The red tide began to decline at the end of November and, by 1 December 2000, the phytoplankton was dominated by diatoms. Chlorophylls and carotenoids in water samples were analysed using HPLC pigment separation technique. Dinoflagellates were indicated by the signature pigment peridinin. Significant correlation ( r=0.999) was found between the peridinin concentration and dinoflagellate density. A decrease in peridinin and an increase in fucoxanthin, a major carotenoid in diatoms, marked the shift in phytoplankton composition at the end of the red tide. HPLC analysis also revealed the occurrence of minor phytoplankton groups that are difficult to identify by light microscopy. Red tide monitoring and study of red tide dynamics in Hong Kong have been based on cell counting and spectrophotometric or fluorometric measurement of chlorophyll a. HPLC pigment analysis provides an effective alternative for investigating phytoplankton dynamics during red tide and other algal blooms.

Growth and mortality rates of phytoplankton in the northwestern North Pacific estimated by the dilution method and HPLC pigment analysis

Pigment-based growth rates of phytoplankton and mortality rates due to microzooplankton grazing were estimated using a dilution method combined with high-performance liquid chromatography (HPLC) pigment analysis in the northwestern North Pacific in autumn 1998. The dilution experiments were conducted at different hydrographic stations in both colder and warmer water masses. No significant difference was found between the growth rate of the phytoplankton community (0.38–0.70 day −1; estimated by chlorophyll a) at the colder and warmer water stations, while the mortality rate (0.15–0.88 day −1; estimated by chlorophyll a) tended to be higher at warmer water stations. The combination of estimates of daily chlorophyll a production and particulate organic carbon (POC) production enabled us to assess the carbon to chlorophyll a ratio (C/chl a) of “new” organic matter produced by living phytoplankton. The method provided an implicit value of the C/chl a of in situ living phytoplankton. The rate estimates from taxon-specific pigments suggested a possibility that chlorophyll b-containing green algae were grazed preferentially by microzooplankton during their active growth, and the standing stock of green algae was more strictly controlled by micrograzer than other algal groups such as diatoms. This result is one possible explanation for the fact that blooms of green algae have not been reported in the open ocean, in contrast with diatoms.

Flow cytometric discrimination of various phycobilin-containing phytoplankton groups in a hypertrophic reservoir.

Knowledge of phytoplankton structure is important information in water quality control. Lake restoration and sanitation measures in particular must be evaluated on the organismic level to valuate biological effects and assess the risk of potentially toxic Cyanobacteria blooms. We used and comparatively tested three independent methods for phytoplankton analysis in a hypertrophic reservoir under restoration. Nine unialgal cultures and outdoor samples were examined by high-performance liquid chromatography pigment analysis, microscopical cell counting, and flow cytometric (FCM) light scatter and fluorescence analysis to measure the percentage contribution of the major algal groups to chlorophyll a and biovolume. The FCM instrument settings and identification criteria were developed using a single excitation wavelength at 514 nm to differentiate nine algal species representing the major groups of algae. Fluorescence was detected at 585, 620, 650, and 680 nm. The results show that FCM is the only method for determining changes in the phytoplankton composition on both a chlorophyll a and biovolume basis. Each of the three methods has specific advantages and disadvantages, and should be chosen depending on the experimental problem. FCM sorting allows the combination of all three and offers further new perspectives.

Form IA rbcL transcripts associated with a low salinity/high chlorophyll plume ('Green River') in the eastern Gulf of Mexico

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 198:1-8 (2000) - doi:10.3354/meps198001 Form IA rbcL transcripts associated with a low salinity/high chlorophyll plume ('Green River') in the eastern Gulf of Mexico John H. Paul1,*, Albin Alfreider2, Jordan B. Kang1, Roger A. Stokes1, Dale Griffin1, Lisa Campbell3, Erla Ornolfsdottir3 1Department of Marine Science, University of South Florida, 140 Seventh Avenue South St. Petersburg, Florida 33701, USA 2Institute of Zoology and Limnology, University of Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria 3Department of Oceanography, Texas A&M University, College Station, Texas 77843-3146, USA *E-mail: jpaul@seas.marine.usf.edu ABSTRACT: Coastal plumes of low salinity water that extend hundreds of kilometers offshore into oligotrophic waters are often found in the Gulf of Mexico. To characterize one such feature, a series of photoautotrophic activity and biomass parameters were measured at 2 stations in the eastern Gulf of Mexico, including pigments by high performance liquid chromatography (HPLC), autotrophic picoplankton abundance by flow cytometry, photoautotrophic 14C-HCO3- fixation, and Ribulose-1,5-diphosphate carboxylase large subunit gene (rbcL) transcriptional activity. One sampling site (Stn 4) was in a 15 m deep, low salinity (29.8 ppt) plume 242 km west of Tampa Bay. This feature contained relatively high chlorophyll a (chl a) concentrations, carbon fixation rates, and Synechococcus cell abundance (8.6 x 104 cells ml-1) at 3 m depth and a relatively shallow (45 m depth) subsurface chlorophyll a maximum (SCM). We also found a high level (1.1 ng l-1) of Form IA rbcL mRNA in the surface water as determined by probing with a 1.1 kb Synechococcus WH7803 rbcL probe. Form IA rbcLs have been found to occur mainly in chemosynthetic autotrophic bacteria but have recently been described in Synechococcus WH7803 as well as in Prochlorococcus GP2. In contrast, a nearby station outside of the plume (Stn 7) had a SCM at 83 m, lower chl a, Synechococcus cell counts, and carbon fixation rates in the surface waters. The amount of Form IA rbcL was only about 3% of the concentration found in the surface waters of Stn 4. Both stations had an abundance of Prochlorococcus cells (>105 ml-1) at intermediate depths (20 to 70 m). The picoeucaryote community occurred principally below the Prochlorococcus community, coinciding with the SCM, and was composed of diatoms, prymnesiophytes, and pelagophytes as determined by HPLC pigment analysis. This report represents the first description of Form IA rbcL transcriptional activity in the marine environment, and indicates that Form IA rbcL-containing picoplankton (like Prochlorococcus GP2 and Synechococcus WH7803) may be important in the primary production of low salinity, surface water plumes of the Gulf of Mexico. KEY WORDS: RuBisCO · Gene expression · Phytoplankton · Gulf of Mexico Full text in pdf format NextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 198. Publication date: June 05, 2000 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 2000 Inter-Research.