MULTIVARIATE MEASURE OF NICHE OVERLAP USING CANONICAL CORRESPONDENCE-ANALYSIS

A measure of multidimensional niche overlap based on species scores fr om canonical correspondence analysis is presented. This measure, N, is the amount of overlap using species scores as approximate weighted av erages with respect to multidimensional niche breadth for the communit y given by N = 0 - [(u(i) - u(j))'V-1 (u(i) - u(j)) g \V\]. Multidimen sional niche overlap was calculated for a representative periphytic co mmunity from northern Lake Huron. Classification of species interactio n or species similarities was accomplished using cluster analysis of t he multidimensional niche overlap values. Two major groups of taxa sho wing similarities were evident based on niche influence. This influenc e produced a gradation of species found in clean waters to those found in varying degrees of pollution.