CS39A Zooplankton - Feeding, Reproduction, Growth and Molecular Diversity
Date: Tuesday, June 11, 2002
Time: 11:15:00 AM
Location: View Royal
 
Manuel Villar-Argaiz, University of Minnesota, Saint Paul, , mvillar@ugr.es
 
ASSIMILATION OF CARBON BY CRUSTACEAN ZOOPLANKTON: EFFECTS OF ONTOGENY AND FOOD QUALITY
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Assimilation of carbon was measured at distinct developmental stages of several cladoceran and copepod freshwater species (Daphnia magna, D. pulicaria, D. pulex, D. dentifera, Bosmina longilostris, Simocephalus vetulus, Diaptomus sicilis and Diaptomus clavipes) fed 14C-labeled algae of varying food quality. Zooplankton acclimated for 36 hrs were fed high concentrations of labeled P-sufficient and P-deficient Scenedesmus obliquus or Cryptomonas erosa. Our results show that C assimilation efficiency (AEC) in zooplankters often varied with the P content of their food, although P-deficient diets did not invariably result in reduced AEC. No consistent ontogenetic trend in AEC was observed among cladocerans, and while it increased with dry weight in D. magna, AEC showed the reversed trend in D. pulicaria or no trend in D. pulex and S. vetulus. In general, algal P content had no major influence on AEC for copepod males and females, but this efficiency increased by 1.8 to 2.2x in ovigerous reproductive females fed P-deficient algae. AEC for the different zooplankton species will be discussed in the light of the chemical C:N:P content of zooplankton and consequences for homeostasis and life strategies will be derived.