Ecological restoration assessment of Adyar creek and estuary using meiofaunal communities as ecological indicators for aquatic pollution

The Adyar estuary has lost its pristine condition and is under great ecological stress due to urbanization, discharge of untreated sewage, solid waste disposal, industrial effluents and encroachments for the past two decades. As a result of degradation, many vital attributes of Adyar estuary such as clean water, faunal and floral diversity and its role as spawning and nursery ground of commercially important finfish and shellfish were lost. In order to restore the ecology of Adyar estuary, Govt.of Tamil Nadu has taken up restoration measures. The present paper deals with the diversity of meiobenthic fauna in the eco-restoration part and non-restoration part to assess the ecological status of Adyar creek and estuary with the help of their ecological indices and physicochemical parameters. In the present study, a total of thirty-nine species belonging to twenty groups of meiofauna were recorded from four stations of Adyar creek and estuary. The Number of meiofaunal species recorded in stations I, II, III and IV were 21, 22, 29 and 34, respectively. Nematodes and rotifers occurred in higher diversity than other meiofaunal groups. The overall density of meiofauna from four stations were ranged between 30±8.33 to 3264.44±378.65 Ind. /10 cm2. In general, higher density of meiofauna was recorded in estuary than the creek. Percentage composition of individual meiofauna groups ranged from 0.01% (gastrotrichs) to 54.9% (rotifers) in all the four stations. Monthly variations in the ecological indices of diversity, dominance and evenness of meiofauna of the four stations of Adyar creek and estuary showed variations in different stations, months and seasons. Results indicate restoration process of the Adyar creek enhanced the physicochemical parameters and meiofaunal diversity. These measures have helped to assess the eco-restoration of the Adyar estuary and are reflected in the favourable diversity of pollution indicator species of meiofauna. The ecological diversity indices and colonization of the restored station provide base-line data for estuarine ecosystem.