ABSTRACT: Laboratory experiments investigating predation by plankton on meroplanktonic invertebrate larvae often use unnaturally high densities of prey in filtered seawater. Offering prey under these conditions, however, can alter predator behavior and capture success, potentially creating artifactual predator-prey relationships and predation rates. We conducted laboratory experiments investigating the effect of a range of larval invertebrate densities on predation rates. For the 4 predator-prey combinations examined, there was no predation at natural prey densities in filtered seawater. We then conducted predator-prey experiments in the presence and absence of naturally occurring ambient plankton ('background plankton') at densities where predation had been observed in filtered seawater. In most experiments, background plankton dramatically decreased or eliminated predation which had been observed with unnaturally high prey densities in filtered seawater.

KEY WORDS: Meroplankton · Invertebrate larvae · Predation · Background plankton · Prey density

Published in MEPS Vol. 158 (1997) on November 17
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1997