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

Abstract

Direct measurements were made of carbon transfer efficiency from bacteria and algae to zooplankton in subtropical Lake Okeechobee, Florida; USA. A radio-tracer method was used to determine carbon transfer efficiency to the >200 μm size class, comparing results from treatments where the label was added as 14C glucose or 14C-bicarbonate. The studies were done at a near-shore 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 particulate activity occurred in the >200 μm size class. Low efficiencies suggest a considerable loss of carbon from the copepod- and cyanobacteria-dominated food web; this seems to be typical of highly eutrophic lakes.