RELATIONS BETWEEN TROPHIC STATE INDICATORS AND FISH IN FLORIDA (USA) LAKES

Total fish biomass per unit area was positively correlated with total phosphorus, total nitrogen, chlorophyll a, and inversely correlated wi th Secchi disk transparency in 65 Florida (U.S.A.) lakes selected to r ange from oligotrophic to hypereutrophic. Species numbers were positiv ely related to lake surface area but not trophic state. There were som e shifts in species composition with changes in trophic state, though only a few species showed significant changes in their standing crops. In particular the recreationally important centrarchids did not show important changes with trophic state, and there were no critical point s on the trophic spectrum where there were dramatic changes in fish ab undance or standing crops. The facts that Florida lakes do not have de ep, cold hypolimnia, do not have salmonid species, and have no ice in the winter are among the possible reasons that the more eutrophic Flor ida lakes do nor show the same changes in fish populations often descr ibed for northern lakes.