Does the marine copepod Calanus pacificus consume transparent exopolymer particles (TEP)?

Gel-like transparent exopolymer particles (TEP) formed from polysaccharides exuded copiously by natural phytoplankton and bacteria occur ubiquitously in sea water, but the utilization of these particles as a food source by zooplankton is poorly known. The common marine calanoid copepod Calanus pacificus consumed TEP and produced abundant fecal pellets when TEP were offered both alone and in the presence of diatom cells. TEP consumption increased with TEP concentration and the presence of TEP did not inhibit ingestion of cells. However, because of their low carbon content, TEP contributed only 15% to total carbon consumption in the presence of phytoplankton food. While copepods consumed pure TEP in this study, sticky TEP in nature contain abundant inclusions of bacteria and microorganisms too small for copepods to capture individually. Thus, consumption of TEP may be most significant as a mechanism by which carbon may be shunted from the microbial loop to higher trophic levels.