An investigation of the indirect effects of intertidal shellfish collection

Abstract

Shellfish collection by humans is a form of selective predation, with the larger individuals of a few target species being taken, and can have direct and indirect effects. We investigated the indirect effects of collection by experimental removals of two target species, Cellana tramorerica (Sowerby) and Nerita atramentosa (Reeve) from a rocky shore in south eastern Australia. Removals of single species were compared with the removal of both species and frequent removals were compared against once-off removal events. The removal of Cellann resulted in an increase in micro- algal abundance. This increase was greater where Cellana were frequently removed than where once-off removal of the speci..