VORACIOUS PLANKTONIC HYDROIDS - UNEXPECTED PREDATORY IMPACT ON A COASTAL MARINE ECOSYSTEM

Hydroids are typically attached, benthic cnidarians that feed on a var iety of small prey. During sampling on Georges Bank in spring 1994, we found huge numbers of hydroids suspended in the plankton. They fed on young stages of copepods that are an important prey for fish, as well as on young fish themselves. Two independent methods were used to est imate feeding rates of the hydroids; both indicate that the hydroids a re capable of consuming from 50% to over 100% of the daily production of young copepods. These results suggest that hydroids can have a prof ound effect on the population dynamics of zooplankton and young fish o n Georges Bank. Copyright (C) 1996 Elsevier Science Ltd