CS08 Biogeochemical Cycles
Date: Monday, June 10, 2002
Time: 2:00:00 PM
Location: Saanich
 
Acharya Kumud, Dept. of Biology, Arizona State University, Tempe, , k.acharya@asu.edu
Kyle, M, , Dept. of Biology, Arizona State University, Tempe, , mkyle@asu.edu
Elser, J, , Dept. of Biology, Arizona State University, Tempe, , j.elser@asu.edu
 
EFFECT OF STOICHIOMETRIC DIETARY MIXING ON DAPHNIA GROWTH AND REPRODUCTION
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Effects of stoichiometric dietary mixing on Daphnia performance were studied to test whether diets of equivalent bulk stoichiometric food quality (C:P ratio) would produce equivalent performance when C:P was uniform among cells or when the diet involved a mixture of high C:P and low C:P cells. Daphnia were fed saturating concentrations of a uniform food of moderate C:P (UNI; C:P = ~500) or mixtures (MIX) of high C:P (1000-1600; LOP) and low C:P (~100; MON) algae prepared to match C:P in UNI. Daphnia were also fed MON and LOP algae separately. Juvenile growth rate and adult fecundity, as well as C, N, P, and RNA contents, were measured. Daphnia galeata performance in UNI and MIX did not differ, indicating that partitioning of C and P among particles did not affect dietary quality. However, D. pulicaria performed better in MIX than in UNI, indicating some benefit of a more heterogeneous diet; the mechanisms for this improvement are unclear. In general, reduced P and RNA contents accompanied lower growth rates.