A fish kill in a Ponte Vedra Beach lake resulted in hundreds of dead fish floating for days. Among the carcasses of shad and other freshwater species were distressed fish gulping for air at the surface.
It is unclear what caused the die-off without water sampling data. The private lake east of A1A is in the community of Sawgrass Country Club and outside the jurisdiction of the Florida Fish and Wildlife Commission.
The vast majority of fish kills in Florida are caused by natural environmental impacts. The occasional depletion of dissolved oxygen in a lake or waterbody is by far the most common cause of fish kills in the state.
Fish need oxygen just like humans and gills take in oxygen dissolved in the water.
This incident is probably related to low oxygen in the water based on clues from the surviving fish gulping for air.
Sometimes toxic algae blooms may be cause and drop in oxygen.
UNF Biology Professor Kelly J. Smith suspects there probably was a major algae bloom. “Heterotrophic bacteria drove the oxygen levels down extremely low. Very low oxygen levels can also lead to hydrogen sulfide release which is toxic to fish. What lead to local effects is a question”.
These events are easy to recognize because they usually affect many different sizes and species of fish, whereas cold temperature fish kills tend to affect only one or two species.
If it is a DO-related fish kill, large fish tend to be affected first and more severely than other fish and small fish can be seen gulping or gasping for air at the surface just before a fish kill occurs.