Alteration of freshwater flows into estuaries negatively impacts Florida's fisheries.
It does this in three ways:
Changes in freshwater flows - the amount, the timing, and the location - kills seagrasses, oysters and other shellfish, and kills or displaces small organisms like fish and shrimp that are gamefish prey. This happens even if the water is pristine - this is because these impacts are due to changes in salinity (the salt content in the water) caused by these altered flows. When gamefish have less to eat and fewer habitats to hide, their health, survival and abundance decline.
Stormwater runoff into estuaries contains the remnants of herbicides and pesticides that are used on lawns, in agriculture, on golf courses. These contaminants remain in the ecosystem for long periods of time, and cause health issues for gamefish and their prey.
Too many nutrients entering coastal waters cause plankton and algae blooms the shade light from seagrasses, which kills the seagrasses. The algae that grows on the bottom also smothers oysters and other bottom organisms. When the plankton and algae die, their decomposition consumes all of the oxygen in the water, which causes fish kills. And when the algae decomposes, it releases all of those nutrients back into the water, which causes more algae blooms. The legacy of nutrient pollution can last for years.