Phytoplankton population dynamics at the Bermuda Atlantic Time-series station in the Sargasso Sea

Abstract Phytoplankton populations were analyzed using flow cytometry in monthly samples at the Bermuda Atlantic Time-series Study (BATS) station in the Sargasso Sea from 1989–1994 for picoplankton ( Synechococcus and Prochlorococcus ) and from 1992–1994 for eukaryotic phytoplankton in order to better understand the mechanisms that dictate seasonal and inter-annual patterns in the phytoplankton community. The eukaryotic phytoplankton were dominated by populations of small nanoplankton (mostly 2–4 μm diameter), though populations of coccolithophores and sometimes pennate diatoms also could be distinguished. Flow cytometric measurements of population abundances, individual cell light scattering (which can be related to cell size), and chlorophyll fluorescence were made. Synechococcus and the eukaryotic phytoplankton reached their greatest concentrations during the spring bloom each year when the water column was deeply mixed and nutrients were detectable in surface waters. The maximum cell concentration for Prochlorococcus was in the summer and fall of each year, with a deeper sub-surface maximum than Synechococcus . Picoplankton chlorophyll fluorescence and estimated cell size were greater at depth than near the surface, and were lowest in midsummer for both Synechococcus and Prochlorococcus . In the summer and fall, Prochlorococcus cells were often smallest at mid-depth, even when fluorescence per cell and cell concentration were lower at the surface. For the eukaryotes (including coccolithophores), cell concentrations were high during the spring in both 1992 and 1993, and in fall 1992. At these times, mean cell size and fluorescence were low. Improved size and carbon estimates were made and it was found that the estimated contribution of phytoplankton carbon to total particulate organic carbon, integrated over the upper 200 m, averaged 33% (range 21–43%) with no pronounced seasonal pattern.

[1]  R. Olson,et al.  Diel patterns in optical properties of the chlorophyte Nannochloris sp.: Relating individual‐cell to bulk measurements , 1998 .

[2]  J. Moffett.  Temporal and spatial variability of copper complexation by strong chelators in the Sargasso Sea , 1995 .

[3]  David M. Nelson,et al.  Diatom growth and productivity in an oligo‐trophic midocean gyre: A 3‐yr record from the Sargasso Sea near Bermuda , 1997 .

[4]  Robert R. Bidigare,et al.  On the chlorophyll a retention properties of glass‐fiber GF/F filters , 1995 .

[5]  M. D. Keller,et al.  A comparison of HPLC pigment signatures and electron microscopic observations for oligotrophic waters of the North Atlantic and Pacific Oceans , 1996 .

[6]  R. R. Strathmann,et al.  ESTIMATING THE ORGANIC CARBON CONTENT OF PHYTOPLANKTON FROM CELL VOLUME OR PLASMA VOLUME1 , 1967 .

[7]  B. Austin.  Methods in aquatic bacteriology , 1988 .

[8]  Daniel Vaulot,et al.  The importance of Prochlorococcus to community structure in the central North Pacific Ocean , 1994 .

[9]  J. A. Dusenberry,et al.  Increasing the sensitivity of a FACScan flow cytometer to study oceanic picoplankton , 1994 .

[10]  A. Wood,et al.  Biomass of bacteria, cyanobacteria, prochlorophytes and photosynthetic eukaryotes in the Sargasso Sea , 1992 .

[11]  B. C. Booth.  Size classes and major taxonomic groups of phytoplankton at two locations in the subarctic pacific ocean in May and August, 1984 , 1988 .

[12]  P. Burkill,et al.  Synechococcus and its importance to the microbial foodweb of the northwestern Indian Ocean , 1993 .

[13]  D. Vaulot,et al.  A simple method to preserve oceanic phytoplankton for flow cytometric analyses. , 1989, Cytometry.

[14]  Lisa R. Moore,et al.  Physiology and molecular phylogeny of coexisting Prochlorococcus ecotypes , 1998, Nature.

[15]  Paul G. Falkowski,et al.  Primary Productivity and Biogeochemical Cycles in the Sea , 1992 .

[16]  Michael E. Sieracki,et al.  Relationships between cell volume and the carbon and nitrogen content of marine photosynthetic nanoplankton , 1992 .

[17]  Kent K. Cavender-Bares.  Size distributions, population dynamics, and single-cell properties of marine plankton in diverse nutrient environments , 1999 .

[18]  H. Thierstein,et al.  Coccolithophore dynamics off Bermuda (N. Atlantic) , 2001 .

[19]  H. Stommel,et al.  How representative is the series of Panulirus stations of monthly mean conditions o , 1969 .

[20]  R. Olson,et al.  Spatial and temporal distributions of prochlorophyte picoplankton in the North Atlantic Ocean , 1990 .

[21]  J. Ryther,et al.  Annual variations in primary production of the Sargasso sea off Bermuda , 1961 .

[22]  J. Ryther,et al.  The annual cycle of primary production in the Sargasso Sea off Bermuda , 1959 .

[23]  Michele D. DuRand.  Phytoplankton Growth and Diel Variations in Beam Attenuation through Individual Cell Analysis. , 1995 .

[24]  Anthony H. Knap,et al.  Overview of the U.S. JGOFS Bermuda Atlantic Time-series Study and the Hydrostation S program , 1996 .

[25]  P. R. Sloan,et al.  RELATIONSHIP BETWEEN CARBON CONTENT, CELL VOLUME, AND AREA IN PHYTOPLANKTON , 1966 .

[26]  P. Glibert,et al.  Effect of irradiances up to 2000 μE m−2 s−1 on marine Synechococcus WH7803—I. Growth, pigmentation, and cell composition , 1987 .

[27]  R. Olson,et al.  Seasonal and depth variation in microbial size spectra at the Bermuda Atlantic time series station , 1999 .

[28]  Sallie W. Chisholm,et al.  Comparative physiology of Synechococcus and Prochlorococcus: influence of light and temperature on growth, pigments, fluorescence and absorptive properties , 1995 .

[29]  R. Goericke.  Response of phytoplankton community structure and taxon‐specific growth rates to seasonally varying physical forcing in the Sargasso Sea off Bermuda , 1998 .

[30]  David A. Siegel,et al.  Seasonal variability of light availability and utilization in the Sargasso Sea , 1995 .

[31]  R. Guillard,et al.  The Phytoplankton of the Sargasso Sea off Bermuda , 1960 .

[32]  K. Bruland,et al.  Spatial and temporal variability in copper complexation in the North Pacific , 1990 .

[33]  J. Waterbury,et al.  Biological and ecological characterization of the marine unicellular Cyanobacterium Synechococcus , 1987 .

[34]  Lisa R. Moore,et al.  Photophysiology of the marine cyanobacterium Prochlorococcus: Ecotypic differences among cultured isolates , 1999 .

[35]  R. Goericke,et al.  Response of Sargasso Sea phytoplankton biomass, growth rates and primary production to seasonally varying physical forcing , 1998 .

[36]  J. Dusenberry.  Picophytoplankton photoacclimation and mixing in the surface oceans , 1995 .

[37]  D. Vaulot,et al.  Annual variability of phytoplankton and bacteria in the subtropical North Pacific Ocean at Station ALOHA during the 1991–1994 ENSO event , 1997 .

[38]  Robert R. Bidigare,et al.  Seasonal patterns of ocean biogeochemistry at the U.S. JGOFS Bermuda Atlantic time-series study site , 1994 .

[39]  R. Parsons,et al.  BATS Methods Manual, Version 4 , 1997 .

[40]  H. Ducklow,et al.  Stocks and dynamics of bacterioplankton in the northwestern Sargasso Sea , 1996 .

[41]  R. Olson,et al.  Discrimination of eukaryotic phytoplankton cell types from light scatter and autofluorescence properties measured by flow cytometry. , 1989, Cytometry.

[42]  E. Haugen,et al.  Overestimation of heterotrophic bacteria in the Sargasso Sea: direct evidence by flow and imaging cytometry , 1995 .

[43]  R. Andersen,et al.  ULTRASTRUCTURE AND 18S RRNA GENE SEQUENCE FOR PELAGOMONAS CALCEOLATA GEN. ET SP. NOV. AND THE DESCRIPTION OF A NEW ALGAL CLASS, THE PELAGOPHYCEAE CLASSIS NOV. 1 , 1993 .

[44]  D. Caron,et al.  The contribution of microorganisms to particulate carbon and nitrogen in surface waters of the Sargasso Sea near Bermuda , 1995 .

[45]  R. Olson,et al.  Pigments, size, and distributions of Synechococcus in the North Atlantic and Pacific Oceans , 1990 .