Influence of river inflows on plankton distribution around the southern perimeter of the Salton Sea,California |
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Authors: | Kristen M Reifel Brandon K Swan Errel Olivo James M Watts Charles C Trees Stuart H Hurlbert |
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Institution: | (1) Department of Biology and Center for Inland Waters, San Diego State University, San Diego, California 92182-4614, USA;(2) Center for Hydro-optics and Remote Sensing, San Diego State University, 6505 Alvarado Road Suite 206, San Diego, California 92120, USA;(3) Present address: Graduate Program in Marine Environmental Biology, Department of Biology, University of Southern California, Los Angeles, California 90089-0371, USA;(4) Present address: Marine Science Program, University of California, Santa Barbara, California 93106-6150, USA;(5) Present address: Department of Biology, Arizona State University, Tempe, Arizona 85287-1501, USA |
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Abstract: | The influence of river inflows (2.5–5 g l−1) on phytoplankton and zooplankton was assessed with samples collected at 17 sites around the 50 km perimeter of the southern
basin of the Salton Sea (41–45 g l−1) along the 5 m isobath on 2 September and 11 December 2000. Phytoplankton generally increased in abundance downcurrent of
the points of inflow, but patterns in downcurrent abundance varied widely among species. Several diatom species showed large
increases; Chaetoceros muelleri var subsalsum, Cylindrotheca closterium and Thalassionema sp. increased up to 800-fold in abundance by ca. 20 km downcurrent from inflow points in September. In contrast, the dinoflagellates
Gyrodinium uncatenum and Prorocentrum minimum increased 6- and 4-fold, respectively, in December, and Gonyaulax grindleyi actually decreased downcurrent of the rivers in September. In September, patterns in downcurrent abundance were correlated
with the ratio of cell surface area to cell biovolume, with species with high ratios showing the largest increases. Zooplankton
abundances did not show regular trends downcurrent of river inflows except for the larvae of Balanus amphitrite, which increased in density ca. 100-fold. This increase most likely reflected the abundance of adult-colonized rocky substrates
near river inflow points. The strong upcurrent trends documented for some species seemed to have been due to the injection
of nutrient-rich water from central to nearshore areas and near-site mortality due to the presence of hydrogen sulfide. This
study gives a first glimpse of the complexity of the responses of nearshore plankton to river inflow and provides evidence
for how changes in factors such as current speed, nutrient supply and salinity stratification may influence plankton dynamics.
Guest Editor: John M. Melack
Saline Waters and their Biota |
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Keywords: | diatoms dinoflagellates phytoplankton salt lakes sulfide turbulence zooplankton |
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