Impact of predation and sediment disturbance by Carcinus maenas (L.) on free-living nematode community structure

A microcosm experiment was conducted to investigate the effects of continuo us and episodic biological disturbance by Carcinus maenas on estuarine nema tode assemblages from sand and mud for a period of 57 days. Univariate meth ods of data evaluation failed to reveal major changes in community structur e. Distributional techniques (dominance curves) were more sensitive in dete cting changes in diversity patterns in the sand assemblage. Results of mult ivariate analyses indicated that nematode assemblages had changed character istically due to biological disturbance. The observed changes in nematode c ommunity stucture were the result of confounded effects of predation and mo dification of the sediment due to crab activity. Nematode assemblages from the organic-poor sand were mainly affected by crab predation, those from th e organic-rich mud were mainly affected by changes to the sediment due to c rab feeding activity. Effects of biological disturbance on both nematode as semblages were dependent on the frequency of disturbance events. (C) 1999 E lsevier Science B.V. All rights reserved.