Fish Sampling Provides Critical Data for Florida Bay

Long-term monitoring efforts at ESC track the changing trends in fish community dynamics over time.

On any given winter morning, you can find Audubon researchers at the dock in Tavernier in the Florida Keys, loading up boats with gear in the predawn light. In the busy season, November through April, the fish crew at Audubon's Everglades Science Center (ESC) begin their day in the dark and are on the water by sunrise.

ESC staff have been examining prey availability for nesting birds in Florida Bay for 30 years by monitoring hydrologic conditions and sampling prey-base fishes in the bay's coastal mangrove zone. Each month during the busy winter season, researchers conduct fish sampling at 11 study sites throughout Southern Biscayne Bay, Florida Bay, and Cape Sable. A fish sample occurs over three consecutive days, using a drop net technique to capture fish. These primary and secondary producers serve a vital purpose in Florida Bay, making up the food base for many higher trophic level predators such as game fish, crocodilians, wading birds, and fish-eating birds of prey.

Water management practices have disrupted the Everglades' natural sheet flow pattern. ESC research links changes in freshwater flow to decreased plant production and subsequent loss of small fishes. The data also illustrate how sea-level rise has been detrimental to the natural fish community's overall functioning and productivity in these mangrove wetlands. In the winter nesting season, wading birds depend on seasonal dry-downs to concentrate their prey, which in turn makes feeding easier. However, because sea-level rise prevents water levels from falling low enough in the dry season to concentrate fish, successfully raising chicks has become much more difficult.

Long-term monitoring efforts at ESC track the changing trends in fish community dynamics over time. This information helps to evaluate the efficacy of restoration efforts that aim to increase freshwater flow to the Everglades and sheds light on the harmful effects of rising sea levels.

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