USE OF INDICES OF DIVERSITY AND HIERARCHICAL DIVERSITY IN STREAM SURVEYS.

Brillouin's equation (H) for species diversity is preferred to other measures from information theory because it is not biased and does not require unrealistic assumptions about the populations being sampled. Diversities of small replicated samples give a better indication of environmental differences between stations than single large samples. Species diversity may be partitioned hierarchically either according to the categories of the taxonomic hierarchy or any other hierarchy. Taxonomic hierarchical diversity reveals components of diversity at each toxonomic level. For several examples, generic diversity revealed nearly as much about community structure as species diversity, suggesting that discriminating higher taxa rather than identifying species can be often used in aquatic ecology, with savings of time and money.