Studies on Niche Breadth of Aquatic Oligochaetes of Some Tropical Freshwater Bodies

The present paper dealt with the measurement of niche breadth of some dominant aquatic Oligochaetes and to ascertain whether they are habitat generalists or specialists. Of the total 11 Oligochaet species, 6 belong to Tubificidae, 1 belongs to Aeolosomatidae and the rests to Naididae. The overall highest value of niche breadth among all the spp. round the year was 4.975 in the month of December for Branchiura sowerbyi while the lowest value was 1.000 for many spp. except a few. Out of 11 Oligochaetes, 6 (Branchiura sowerbyi,Tubifex tubifex, Limnodrilus udekemianus, Limnodrilus angustepenis, Aelosoma sp. and Dero sp.) were grouped under habitat generalists whose average niche breadth values were 4.124, 3.212, 3.219, 3.654, 3.600 and 3.936 respectively. Only 1 Oligochaet i.e. Aulodrilus americanus (0.666) was categorized as habitat specialists. Remaining four viz. Limnodrilus hoffmeisteri, Dero pectinata, Chaetogaster sp. and Pristina sp. were categorized as habitat intermediates with mean values of 2.082, 1.959, 1.952 and 1.645 respectively.