A sensitivity analysis of nine diversity and seven similarity indices

Indices summarizing community structure are used to evaluate fundamental community ecology, species interaction, biogeographical factors, and environmental stress. Some of these indices are insensitive to gross community changes induced by contaminants of pollution.

Sixteen indices commonly used to assess the status of aquatic communities in water quality studies were evaluated using computer simulation techniques to determine specific index responses. Three communities of different initial structure (19 species, 38 species, and 83 species) were generated using the lognormal equation. Each community was then perturbed in three ways: common species disproportionally reduced, all species proportionally reduced, and rare species disproportionally reduced. The behavior of the indices was analyzed graphically and differential response due to initial community structure and type of community change was documented. Some recommendations of potential sources of error using community levels indices were developed.