Diversity and overlap as measures of environmental quality

It is argued that indices of diversity (information function H) and overlap (percentage similarity PS) can be used together to assess environmental quality. The method is tested using data on demersal fishes from nine Massachusetts estuaries and embayments. Annual diversity ranged from H (log_e) = 0.4–2.4, with low diversities in areas of apparent high pollution and higher diversities in areas of lesser pollution. Where annual diversity is low, little seasonal change is reflected in a high PS from season to season; where annual diversity is high, a relatively lower PS indicates a greater degree of change. For their calculation, both H and PS require the number of individuals in each species in a sample. This data should be considered important in the conduct of faunal surveys that contribute to an environmental impact statement.