CS39A Zooplankton - Feeding, Reproduction, Growth and Molecular Diversity
Date: Tuesday, June 11, 2002
Time: 4:00:00 PM
Location: View Royal
 
FitzgeraldGM, Dalhousie University, Halifax, Canada, fitzgerg@is2.dal.ca
Head, E, J, Department of Fisheries and Oceans, Dartmouth, Canada, HeadE@mar.dfo-mpo.gc.ca
 
CAN WE MEASURE FEEDING RATES OF COPEPODS USING THE GUT PIGMENT METHOD?
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The feeding rates of copepods are measured in order to determine their role in aquatic food webs, to quantify their importance in global carbon cycling, and to support theories about the energetics of filter-feeding. The gut pigment method is commonly used to measure copepod feeding rates. Central to the use of this method is the assumption that chlorophyll a and its degradation products, phaeopigments, are conserved during passage through the gut. With the objective of observing the fate of photosynthetic pigments during feeding, the pelagic copepod community of the Bedford Basin, Nova Scotia, was sampled on a weekly basis for one year. Copepods were offered one of three species of cultured algae. Ingestion rates and changes in pigment complement were quantified using high performance liquid chromatography. Chlorophyll a was destroyed at rates that varied with community structure, ingestion rate, and algal food type. The significant and highly variable degree of pigment destruction observed confirmed reservations about the use of the gut pigment method and, by extension, calls into question our understanding of the trophic role of copepods in aquatic ecosystems.