PREINGESTIVE SELECTION OF DIFFERENT MICROALGAL MIXTURES IN CRASSOSTREA GIGAS AND MYTILUS EDULIS, ANALYSED BY FLOW CYTOMETRY

S. Bougrier, A.J.S. Hawkins, M. Heral-1997

Aquaculture, 150: 123-134

Abstract:

The potential impact of selective grazing by filter-feeding bivalves

was studied on the relative composition of both planktonic and

benthic algae that are commonly suspended in coastal areas. Different

feeding behaviour was observed in the oyster Crassostrea gigas and

the mussel Mytilus edulis. C. gigas preferentially filtered and rejected

(as pseudofaeces prior to ingestion) diatom species relative to

flagellates. These differences appear to depend upon differences in

algal shape and flexibility. Findings also suggest that ratios of

rejection to filtration for flagellate species were influenced by the

planktonic or benthic origin of the other available algal species.

Future studies of trophic flux and resource utilisation should therefore

consider the extent to which different filter-feeding species may

preferentially filter and/or ingest separate algal species that are

simultaneously available in the surrounding seston.

(CNRS-IFREMER, Crema, BP 5, 17137 L'Houmeau, France)

home

------------------------------------------------------------------------------