Dominance of Limnodrilus hoffmeisteri in oligochaete community of Dal lake, Srinagar, Kashmir, India

A total of 5 oligochaete species belonging to three families viz; Tubificidae, Naididae and Aelosomatidae were recorded in the study.. The reported species included Limnodrilus hoffmeisteri, Tubifex tubifex, Branchiura sowerbyii, Aelosoma sp. and Nais sp. Limnodrilus hoffmeisteri is a pollution tolerant species and is widely used as an indicator of organic pollution and was found to be the dominant species of Dal lake with highest average population density of 1269 ind./m2. Mean relative abundance expressed as the percentage of this species was found to be 57% of the total collected oligochaete fauna. This increase in species percentage was closely related to the increase in the oligochaete dynamics of abundance, which in turn lead to changes in the oligochaeta community structure. Pollution measuring index was observed to be 0.9 indicating Dal lake to be an eutrophic water body. Using such biotic indices of density of Tubificidae, percentage of Limnodrilus hoffmeisteri, it was assessed that Dal lake receives large amounts of organic pollutants. These findings also confirmed Limnodrilus hoffmeisteri as a biological indicator of lake conditions.