Effect of Corophium volutator on the abundance of benthic diatoms, bacteria and sediment stability in two estuaries in southeastern England

Abstract

In in situ experiments the abundance of Corophium volutator (Pallas) in areas of intertidal mudflats of the Rivers Crouch and Blackwater, southeastern England, was reduced by spraying with an insecticide. In these sprayed areas the densities of bacteria and diatoms increased significantly, as did the concentrations of chlorophyll a. These changes were attributed to the reduction in the grazing pressure by C. volutator, which is a deposit feeder that consumes diatoms and bacteria. The shear strength of the sediment in the sprayed areas increased, probably for 2 reasons: firstly because of increased amounts of mucopolysaccharide secreted by the microflora, and secondly because of the decreased water content of the sediment. The activities of C volutator may, therefore, exacerbate the erosion that is prevalent in estuaries j.n southeastern England