Utility of caddisflies (Insecta: Trichoptera) as indicators of water quality in Kallada River, Kerala, India

Abstract

ABSTRACT The perennial Kallada River originates at Karimalai-Kodakkal in the Southern part of Sahyadri (Western Ghats), running through Kollam, Pathanamthitta, and Trivandrum districts of Kerala, India. One of the crucial World Bank aided and the most significant Irrigation projects in Kerala is centred on the Kallada River, and now this project is benefited for in 92 villages. However, it is essential to monitor the water quality of the Kallada River. The focus of the present study is to assess the water quality of the Kallada River using caddisflies (Trichoptera) as well as physicochemical parameters of water. Samples of caddisflies and water were collected from 6 sites in the river to monitor water quality during the pre-monsoon season. Altogether, more than 3000 specimens belonging to 5 different taxa were recorded. A multivariate statistical approach was applied to study the influences of the water quality on caddisflies fauna. The results indicate that the upstream supported community abundance than the downstream. Less abundance of caddisflies was observed in the midstream and downstream sites Punalur and West Kallada, respectively. Caddisflies were absent in the sixth site Koivila, resulting from saltwater intrusion from the Ashtamudy estuary and various anthropogenic activities such as boating, civic effluents, and fishing. Upstream sites showed good water quality conditions and caddisfly abundance. The Kallada River is under threat of anthropogenic disturbances, especially in the mid and downstream sections. The caddisfly assemblage proved to be suitable in identifying variations in water quality conditions in the Kallada River because of their significant responses to environmental fluctuations.