New Zealand Journal of Marine and Freshwater Research abstracts

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Deposit feeding ecology of Amphibola crenata I. Long-term effects of deposit feeding on sediment micro-organisms

S. KIM JUNIPER

Department of Zoology
University of Canterbury
Christchurch, New Zealand

and

Cawthron Institute

P.O. Box 175
Nelson, New Zealand

Abstract Short-term effects of deposit feeding on benthic micro-organisms are known from several marine environments, but longer-term influences of deposit feeders have not been extensively investigated. The long-term microbial response to deposit feeding by the gastropod Amphibola crenata was monitored in a 10-month field study where deposit feeding intensity was controlled in artificial enclosures. The presence of the snail resulted in a minor decrease in bacterial numbers and a slight increase in heterotrophic activity relative to bacterial cell numbers. This effect may have been the long-term signature of a previously reported pulse in bacterial production during the recolonisation of Amphibola faeces. Normal snail density had a strong inhibitory effect on primary productivity by the benthic microalgae, reducing CO₂ fixation to 29-47% of levels that could be attained when snails were excluded. Variations in the effect of deposit feeding on micro-organisms over the experimental period suggest that it may be modified by seasonal factors acting on benthic communities. In a similar interaction of influences, seasonal changes in microbial biomass and activity appeared to vary with snail density.

Keywords deposit feeding; Amphibola crenata; benthic ecology; sediment micro-organisms

New Zealand Journal of Marine and Freshwater Research, 1987, Vol. 21: 235-246 0028-8330/87/2102-0235$2.50/0 © Crown copyright 1987 Received 12 January 1986; accepted 17 September 1986

PDF file of entire paper: medium quality (945K); (scanned from paper original: notes about this process)

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