Relative efficiencies of carbon transfer from bacteria and algae to zooplankton in a subtropical lake

Direct measurements were made of carbon transfer efficiency from bacteria a nd algae to zooplankton in subtropical Lake Okeechobee, Florida, USA. A rad io-tracer method was used to determine carbon transfer efficiency to the >2 00 mu m size class, comparing results from treatments where the label was a dded as C-14 glucose or C-14-bicarbonate. The studies were done at a near-s hore and an offshore site, and repeated on five occasions between July 1998 and 1999. The results displayed little variation with location, month, or type of tracer used. After 4 h incubations, between 0.1 and 1.0% of the par ticulate activity occurred in the >200 mu m size class. Low efficiencies su ggest a considerable loss of carbon from the copepod- and cyanobacteria-dom inated food web; this seems to be typical of highly eutrophic lakes.