DIETARY PATTERNS IN STREAM- AND LAKE-DWELLING POPULATIONS OF AUSTROPOTAMOBIUS PALLIPES

Abstract

White-clawed crayfish (Austropotamobius pallipes) are widespread in Ireland in both running and standing water, although stream-dwelling in much of their range elsewhere. A detailed comparative study of a lake and a stream population demonstrated that diets changed with crayfish size from feeding on entomostracans to a predominance of aquatic macrophytes and terrestrial vegetation. However, carnivory remained important at all sizes: Gammarids were a significant component in larger lake crayfish and in all sizes of stream crayfish. Fish increased in importance with crayfish size. A. pallipes thus appears more carnivorous than some other European and American crayfish. The extent to which this is related to habitat is discussed.