The structure of diversity in an epiphytic chironomid community

The structure of diversity in a chironomid community inhabiting submerged macrophytes was analysed, including the relationship between predation/competition and chironomid diversity. Diversity as expressed by the Shannon function H′ was found to be strongly associated with equitability J but not with species richness S in this community. Chironomid species richness was correlated with the abundance of diatoms. Diversity H′ and equitability J were significantly correlated with chironomid density through the year. Invertebrate predators were generally rare and occurred sporadically throughout the year in this habitat, with only three species (Chaetogaster diaphanus, Rhyacophila dorsalis and Zavrelimyia sp.) attaining >25% habitat occupancy. Neither these predators nor non-chironomid competitors encountered in the same habitat (Stylaria lacustris, Ophidonais serpentina, Hydroptila sp., Simulium spp. and Hydropsyche siltalai) appeared to affect diversity measures of the chironomid community under study, apart from a weak tendency of high Simulium density negatively affecting the total chironomid abundance. In conjunction with other analyses, this chironomid community seemed to be stochastically dynamic and was little influenced by biotic factors such as predation and competition.