FEEDING-BEHAVIOR AND DIET OF COROPHIUM VOLUTATOR IN AN ESTUARY IN SOUTHEASTERN ENGLAND

Experiments with radioactively labelled diatoms confirmed the ability of Corophium volutator (Pallas) to suspension feed and deposit feed. Using either method individual amphipods consumed a mean of approximately 4000 small diatoms in 1 h. However, no diatoms were visible in the guts, probably because they were crushed by the mandibles before ingestion, There was no consistent difference in the amounts of material in the guts of amphipods collected from the mudflats at 4 different states of the tide nor in 4 different seasons. C. volutator were immersed for approximately 3 h in each tidal cycle and as most feeding occurred when they were emersed they must have been deposit feeding on the surface sediment. The chlorophyll a concentrations in the guts of the amphipods collected from the estuary were similar to those from amphipods that had fed on large numbers of diatoms in the laboratory. Despite the absence of intact diatoms in the guts of the amphipods it was concluded that benthic diatoms form a significant part of their diet and that C. volutator populations have the potential to reduce significantly the densities of benthic diatoms by feeding.