Home > Explore News > New Research Sheds Light on Altered Freshwater Flow Effects on Juvenile Fish

New Research Sheds Light on Altered Freshwater Flow Effects on Juvenile Fish

Published on: 07/12/2023
Primary Contact(s): bethany.williams@noaa.gov

Bethany Williams and Arliss Winship pull in a trawl to survey fish in Rookery Bay National Estuarine Research Reserve.

A new publication in Estuaries and Coasts demonstrates how human-altered freshwater flow relates to juvenile fish abundance in the mangrove-lined bays of the Ten Thousand Islands, Florida.

Two species (lane snapper (Lutjanus synagris)  and sand seatrout (Cynoscion arenarius)) are expected to be most affected by the ongoing restoration, but the remaining will be minimally impacted. Changes in freshwater flow to estuaries can cause a suite of ecosystem impacts, including eutrophication and alterations to plant communities, zooplankton populations, and other biota. In southwest Florida, historical manipulation of freshwater flow due to development, canals, and drainage ditches, is pervasive. Because there are estuaries with reduced, increased, and relatively natural freshwater flow, this region presents an ideal system to study how these changes relate to downstream fish abundances. While salinity and temperature had species-specific relationships with fish abundances, seasonality, interannual-variability, and sub-estuary were more closely related to fish than salinity and temperature, in most cases.

This work quantified how changes in freshwater flow, using salinity as a proxy, may relate to downstream fish abundances and therefore the potential implications of planned watershed restoration that is part of the Comprehensive Everglades Restoration Plan. The paper, authored by NCCOS in partnership with Rookery Bay National Estuarine Research Reserve, uses a 20-year trawl dataset to help inform how major restoration projects as part of the Comprehensive Everglades Restoration Plan can be expected to influence fish abundances as natural freshwater flow is restored. 

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