Use of diversity estimations in the study of sedimentary benthic communities

Abstract

The soft-bottom benthos covers most of the sea floor. Measurement and analysis of the species richness of these habitats are increasingly needed for studies of community regulation and for providing scientific criteria for the conservation of the ocean bottom at all depths. Diversity measures provide an evolving suite of tools that allow benthic ecologists to meet both basic and applied needs. While species diversity is now considered a fundamental aspect of communities and ecosystems, the measurement of benthic diversity did not become commonplace until the late 1960s. Prior to that communities were characterised by representative species with the implicit assumption that minor species components did not warrant detailed analysis. Use of diversity measures in benthic ecology has largely parallelled studies in other ecosystems with an emphasis upon measures that are informative when applied to large amounts of data with high species numbers. Non-parametric indices such as Simpson's and Shannon's are widely used along with simple species richness. Logseries and log-normal distributions have been advocated as general neutral models but receive less use. Current research is especially focused upon extrapolation of unsampled species richness and diversity relationships across spatial scales. Major contributions from benthic ecology include the rarefaction of samples to a uniform size, the development of indices that include phylogenetic relationships in diversity estimation and the extrapolation of full species richness from observed values. In meeting scientific and societal needs, benthic ecologists must apply methods that are insightful yet can be simply explained within the resource-policy arena.