Abstract
The propriety of using hierarchical entropy of information theory (H) as a trophic state of lake was examined for the community of phytoplankton from Lake Kasumigaura and Lake Biwa. Species entropy for the community of phytoplankton (Hs) may be partitioned hierarchically either according to the categories of the taxonomic hierarchy. Taxonomic hierarchical entropy reveals components of entropy at each taxonomic level. For the community of phytoplankton, generic entropy (Hg) revealed nearly as much about community structures as Hs suggesting that discriminating higher taxa rather than identifying species can be used in the community of phytoplankton, with saving of time and money.
