Post-restoration ecological assessment on the zooplankton dynamics of the Adyar creek and estuary

The Adyar estuary is one of the highly productive transitional zones of southeast India, situated in the southern part of Chennai city and acts as a nursery ground for several endemic flora and fauna. Since few decades, due to anthropogenic activities,indiscriminate dumping and discharge of domestic and industrial wastes and pollutants has environmentally damaged the Adyar estuary lowering many of its ecological and socio-economic attributes. In order to mitigate further environmental damage and to restore it to its earlier pristine condition, the Government and several non-Governmental agencies have undertaken ecological restoration measures to enhance its ecology and diversity. In order to evaluate the restoration process, our present study attempts to assess the diversity and abundance of zooplankton population in the restored and non-restored parts of the Adyar creek and estuary. 34 species belonging to 12 zooplankton groups from 4 stations of the Adyar creek and estuary were recorded. Copepods and rotifers were the dominant groups of zooplankton in Adyar estuary. The overall density of zooplankton from 4 stations ranged between 11.5 ± 4.39 and 23,046.67 ± 2872.68 Ind l⁻¹. In general, Adyar estuary recorded higher zooplankton abundance than creek. The relative percentage composition was maximum for rotifers with 85.67% at Station-IV. Copepods dominated Station-I, whereas rotifers dominated the other 3 stations. Overall results indicate that the restoration activities had beneficial effect on the hydrological parameters and in increasing the diversity of zooplankton in the restored part of the Adyar creek and estuary compared to the non-restored part. Ecological indices have been used to assess the present status of the restored and non-restored parts in the Adyar creek and estuary.