Chironomid faunal composition represented by taxonomic distinctness index reveals environmental change in a lotic system over three decades.

Abstract

The widely distributed family of the Chironomidae represents the most diverse and abundant group of macroinvertebrate fauna and potentially provides information on stream water quality and the effect of anthropogenic disturbances. Change in the chironomid faunal composition in the Southern Morava River basin (Serbia) was examined by comparing data from 1981 and 2010. We tested the performance of the parameter “taxonomic distinctness” (delta+) as an indicator of water quality and examined the possible relationship between delta+ and water quality using PCA. The 2010 survey yielded 96 taxa in 28 localities over three seasons. In total, 10,179 specimens represented the five subfamilies. Chironomid diversity was captured with the index delta+ that is based upon taxonomic distinctiveness and purported to be independent of sampling effort. Delta+ was correlated to total species richness and is significantly higher now than it was in 1981. In keeping with PCA results, delta+ was increasing in accordance with water quality increase. We conclude that delta+ is a useful measure for estimating anthropogenic disturbance over time. The linear relationship between delta+ and the water quality gradient gives rise to a novel metric, independent of sampling effort, in the multimetric approaches of analyzing macroinvertebrate assemblage data for bioassessments.