(1) National Oceanic and Atmospheric Administration, Great Lakes Environmental Research Laboratory, 2300 Washtenaw Avenue, 48104 Ann Arbor, MI, U.S.A.;(2) Division of Biological Sciences, The University of Michigan, Ann Arbor, Michigan
Abstract:
Rates of nitrogen and phosphorus release from individualDaphnia magna were determined by measuring ammonia and soluble reactive phosphorus in successive 10-min incubations in small (0.05 ml) vessels after the animals were removed from their food. Release rates of both nutrients were generally highest initially and decreased with time after removal. The ratio of nitrogen to phosphorus released increased with time after animals were removed from an artificial detritus/bacterial food; ratios were lower and changed with time less for animals fed algae. These data suggest errors may be introduced by assumptions of constant stoichiometry for nutrient release in varying environments.GLERL Contribution No. 268