Freshwater Flow Affects Subsidies of a Copepod (Pseudodiaptomus forbesi) to Low-Salinity Food Webs in the Upper San Francisco Estuary

Productivity of the food web supporting small pelagic fishes in the upper San Francisco Estuary is chronically low, and some of the native fish species are in a long-term decline. The low-salinity (oligohaline) zone (LSZ) is particularly depauperate in phytoplankton and zooplankton. Based on prior e...

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Bibliographic Details
Published in:Estuaries and coasts 2023-03, Vol.46 (2), p.450-462
Main Authors: Hassrick, Jason L., Korman, Josh, Kimmerer, Wim J., Gross, Edward S., Grimaldo, Lenny F., Lee, Calvin, Schultz, Andrew A.
Format: Article
Language:English
Subjects:
Aquatic crustaceans
Bayesian analysis
Bayesian theory
Climate change
Coastal Sciences
Drought
Earth and Environmental Science
Ecology
Empirical analysis
Environment
Environmental Management
Estuaries
Estuarine dynamics
Fish
Flow rates
Flow velocity
Food chains
Food webs
Fresh water
Freshwater
Freshwater & Marine Ecology
Indigenous species
Inland water environment
Pelagic fish
Phytoplankton
Plankton
Population decline
Prey
Probability theory
Pseudodiaptomus forbesi
Salinity
Salinity effects
Subsidies
Tracking
Water and Health
Zooplankton
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Summary:Productivity of the food web supporting small pelagic fishes in the upper San Francisco Estuary is chronically low, and some of the native fish species are in a long-term decline. The low-salinity (oligohaline) zone (LSZ) is particularly depauperate in phytoplankton and zooplankton. Based on prior empirical studies, it is hypothesized that freshwater flow increases the subsidy of a key copepod prey species ( Pseudodiaptomus forbesi ) from its freshwater population center into the LSZ. We combined hydrodynamic and particle-tracking modeling with Bayesian analysis in a box-model approach to estimate the magnitude of this subsidy and its dependence on freshwater flow rates. Net gains of P. forbesi into the LSZ came mostly from freshwater, landward regions of higher copepod abundance. The subsidy increased with freshwater flow, a finding that supports previous empirical analyses. However, in the context of persistent drought and ongoing climate change, the levels required to achieve a detectable net gain may be difficult and costly to achieve.
ISSN:1559-2723
1559-2731
DOI:10.1007/s12237-022-01142-1