Morphoedaphic and Biogeographic Analysis of Crayfish Distribution in Northern Wisconsin

Abstract

Crayfish distribution and abundance were surveyed among 67 lakes in the Vilas County area of northern Wisconsin, and then multiple regression was used to analyze the relationship between the results and various physical, chemical and biological variables. The region is dominated by Orconectes rusticus, O. propinquus and O. virilis, but Cambarus diogenes, Procambarus acutus and O. immunis are also present; only O. virilis was previously documented from the area. No single variable or combination of variables fully explained variations in crayfish distributions. Substrate, Ca level, geographic isolation as related to colonization opportunity, and lake size appear to be of general importance. Continuing introductions and competitive exclusion are also probably significant, resulting in a dynamic situation involving an interaction of multiple controlling factors.