Spatial variability of phytoplankton in a shallow tidal freshwater system reveals complex controls on abundance and community structure.

Autor: Stumpner EB; USGS California Water Science Center, 6000 J Street, Sacramento, CA, USA. Electronic address: estumpner@usgs.gov., Bergamaschi BA; USGS California Water Science Center, 6000 J Street, Sacramento, CA, USA., Kraus TEC; USGS California Water Science Center, 6000 J Street, Sacramento, CA, USA., Parker AE; California State University Maritime Academy, 200 Maritime Academy Drive, Vallejo, CA, USA., Wilkerson FP; Estuary & Ocean Science Center, San Francisco State University, 3152 Paradise Drive, Tiburon, CA, USA., Downing BD; USGS California Water Science Center, 6000 J Street, Sacramento, CA, USA., Dugdale RC; Estuary & Ocean Science Center, San Francisco State University, 3152 Paradise Drive, Tiburon, CA, USA., Murrell MC; US Environmental Protection Agency Gulf Ecology Division, 1 Sabine Island Drive, Gulf Breeze, FL, USA., Carpenter KD; USGS Oregon Water Science Center, 2130 S.W. Fifth Avenue, Portland, OR, USA., Orlando JL; USGS California Water Science Center, 6000 J Street, Sacramento, CA, USA., Kendall C; USGS National Research Program, 345 Middlefield Road, Menlo Park, CA, USA.
Jazyk: angličtina
Zdroj: The Science of the total environment [Sci Total Environ] 2020 Jan 15; Vol. 700, pp. 134392. Date of Electronic Publication: 2019 Sep 13.
DOI: 10.1016/j.scitotenv.2019.134392
Abstrakt: Estuaries worldwide are undergoing changes to patterns of aquatic productivity because of human activities that alter flow, impact sediment delivery and thus the light field, and contribute nutrients and contaminants like pesticides and metals. These changes can influence phytoplankton communities, which in turn can alter estuarine food webs. We used multiple approaches-including high-resolution water quality mapping, synoptic sampling, productivity and nitrogen uptake rates, Lagrangian parcel tracking, enclosure experiments and bottle incubations-over a short time period to take a "spatial snapshot" of conditions in the northern region of the San Francisco Estuary (California, USA) to examine how environmental drivers like light availability, nutrients, water residence time, and contaminants affect phytoplankton abundance and community attributes like size distribution, taxonomic structure, and nutrient uptake rates. Zones characterized by longer residence time (15-60 days) had higher chlorophyll-a concentrations (9 ± 4 µg L -1 ) and were comprised primarily of small phytoplankton cells (<5 µm, 74 ± 8%), lower ammonium concentrations (1 ± 0.8 µM), higher nitrate uptake rates, and higher rates of potential carbon productivity. Conversely, zones characterized by shorter residence time (1-14 days) had higher ammonium concentration (13 ± 5 µM) and lower chlorophyll-a concentration (5 ± 1 µg L -1 ) with diatoms making up a larger percent contribution. Longer residence time, however, did not result in the accumulation of large (>5 µm) cells considered important to pelagic food webs. Rather, longer residence time zones had a phytoplankton community comprised primarily of small cells, particularly picocyanobacteria that made up 38 ± 17% of the chlorophyll-a - nearly double the concentration seen in shorter residence time zones (22 ± 7% picocyanobacterial of chlorophyll-a). Our results suggest that water residence time in estuaries may have an effect as large or larger than that experimentally demonstrated for light, contaminants, or nutrients.
(Published by Elsevier B.V.)
Databáze: MEDLINE
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