Effect of water quality on caddisflies (Trichoptera) in Kallada river, Kerala, India

The caddisflies (Trichoptera) constitute a significant water quality marker group because of their taxonomic richness, ecological diversity, and abundance in virtually all freshwater ecosystems. In this study, caddisflies were collected for an evaluation of the water quality in Kallada river, South, India. Samples collected during the pre-monsoon season were identified at the family level. In total, more than 4500 specimens were identified as belonging to five different taxa. These sensitive species have typically been restricted to non-polluted water bodies. The dominant family at stations S1, S2, S3 and S4 was determined to be Hydropsychidae, whereas the dominant family at S5 was found to be Philopotamidae. The upstream, midstream and downstream sites of Kallada River show drastic differences among caddisfly assemblages. The lack of caddisflies in the midstream and downstream areas is due to anthropogenic interferences and mixing of seawater with freshwater within these low-altitude regions. Other sources of pollution, including bridge construction, urbanization and fishing both midstream and downstream are likely reasons for the fundamental changes in the composition of caddisfly assemblages observed in these areas.