Sample-size dependence of diversity indices and the determination of sufficient sample size in a high-diversity deep-sea environment

Diversity indices, although designed for comparative purposes, often cannot be used as such, due to their sample-size dependence. It is argued here that this dependence is more pronounced in h ~g h divers~ty than in low diversity assemblages and that indices more sensitive to rarer species require larger sample sizes to estimate diversity with reasonable precision than indices which put more weight on commoner species. This was tested for Hill's diversity numbers No to N, (Hill 1973) and some other commonly used diversity indices for a high-diversity nematode assemblage in the Mediterranean deep sea.