Ammonium release by zooplankton in suspensions of heat-killed algae and an evaluation of the flow-cell method
- 1 January 1986
- journal article
- research article
- Published by Oxford University Press (OUP) in Journal of Plankton Research
- Vol. 8 (2) , 341-352
- https://doi.org/10.1093/plankt/8.2.341
Abstract
The maximum excretion rate of NH4 (39 nmol mg dry wt−1 h−1) was directly measured for Daphnia pulex by measuring NH4 accumulation in bottles containing D. pulex and dense, satiating suspensions of heat-killed algae. Ammonium release rates in the algal suspensions were compared to those of individual animals removed from the suspension and placed in flow cells. Ammonium release rate, R (nmol mg dry wt−1 h−1). in the flow cell decreased very rapidly with time, t (min), after removal according to the relation R = 26 + 25e−0.16t. Ammonium excretion obtained by the flow cell method after extrapolation to time zero was not significantly different from that obtained in the bottles. The considerable experiment-to-experiment variation in NH4 excretion was in large part correlated (r2 = 0.73) with the feeding rate on the algae.Keywords
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