Freshwater oligochaetes (Annelida) from Western Ghats andthe west coast of Karnataka (India)

Abstract

The fauna of aquatic oligochaetes (microdriles) of Karnataka, India is poorly known. The aim of the present survey was to prepare the preliminary checklist of microdrile worms present in the freshwater bodies of Western Ghats and the west coast of Karnataka. The wetland ecosystems are mostly perennial and host a large number of species. However, they are exposed to various environmental factors including rainfall, changes in chemicals, pH, growth of macroalgae and macrophytes, decay of plant and animal materials, and human activities such as fishing. The aquatic oligochaetes are the most important microinvertebrates, adapted to every kind of water such as saltwater, brackish water, and freshwater, including small streams, large rivers, marshes, ponds, lakes, springs, and groundwater. They are found in algae, aquatic vegetation, floating rotting material, and bottom mud (Wetzel et al., 2000). They are an important food source for some invertebrate and fishes. They can be of importance in water management because of their potentially high densities (Brinkhurst and Jamieson, 1971), their wide distribution, and their indicator value (Milbrink, 1973;Chapman et al., 1982;Särkkä, 1994). They display a great diversity in aquatic bodies, including over 1700 species. Of these, about 1100 species are freshwater species and others are primarily terrestrial, belonging to the family Enchytraeidae (Martin et al., 2007). The ecological value of oligochaetes includes their importance in aquatic food chains, their impact on sediment structure and water-Abstract: A survey on freshwater oligochaetes was conducted between October 2011 and June 2013 in selected wetlands of the Dakshina Kannada, Udupi, and Shimoga districts of Karnataka, India. In this study, 260 wetlands were sampled and examined for the presence of microdriles. Sixteen species of aquatic oligochaetes were recorded. Of these, 10 species belonged to the family Naididae (monophyletic) and 6 species to the family Pristinidae. The species' distribution patterns in different water bodies and habitat specificity (if any) in the study area are presented.