Diversity and distribution of aquatic insects and their relation to water quality parameters at the selected stations of the Chalakudy River, Kerala, India

Abstract

The present study assessed the diversity, distribution, and composition of aquatic insects and their relation to water quality parameters in the selected stations of the Chalakudy River. A total of 595 individuals belong to 7 orders, and 22 families were identified from the study area. Athirappilly exhibited the highest Shannon diversity (2.657) and species richness (3.374). In contrast, the lowest Shannon diversity (2.161) and species richness (2.009) were recorded at Ezhattumugham. The elevated diversity and richness at Athirappilly, coupled with sensitive taxa belonging to Ephemeroptera, Plecoptera, and Trichoptera, indicate favourable ecological conditions and minimal anthropogenic impact. Conversely, diminished diversity and richness with a lack of sensitive taxa at Ezhattumugham were attributed to deteriorated water quality. A two-way analysis of variance was performed to assess variations in physicochemical parameters between stations and seasons, revealing significant spatial and seasonal variations. Water temperature, electrical conductivity, dissolved oxygen, and biological oxygen demand exhibited statistically significant differences between stations and across seasons. Canonical correspondence analysis elucidated a significant relationship between the distribution and composition of aquatic insects and the water quality variables measured. The pre-monsoon season was characterized by a higher prevalence of tolerant taxa, while the post-monsoon season was distinguished by sensitive taxa, reflecting improved water quality. These patterns highlight the temporal fluctuations in water quality and their impact on aquatic insects. The finding emphasizes the interplay between water quality parameters and biodiversity, offering valuable insight for conservation efforts and sustainable river basin management.