STUDY OF FISH FAUNA IN KORAMPALLAM THERMAL ESTUARY, THOOTHUKUDI, SOUTHERN TAMIL NADU

Estuaries constitute an essential habitat for many fish species to complete their life cycle. Korampallam thermal estuary is located just behind the sea-based thermal power plant. This estuary expands into a wide mangrove area and mix with freshwater channel in which surplus water from the Korampallam lake flows into the sea. In this study, fish samples were collected using cast net and sampling was performed during low tide. A total of 43 fish species were identified during the study period, which was coming under 18 families belonging to 6 orders namely clupeiforms, siluriformes, perciforms, tetrodontiforms, beloniforms and mugiliforms. Among the above orders, most dominant fish species belonged to perciformes and mugiliforms.

The species composition and abundance data were analysed during the four seasons namely, summer (April-June), pre-monsoon (July-September), monsoon (October-December) and post-monsoon (January-March). The species composition recorded among seasons, varied in the range of 28-42 numbers. The fish diversity of Korampallam thermal estuary was highest (42 species) in pre-monsoon, and lowest (28 species) in monsoon seasons. The study on species abundance indicated that Korampallam thermal estuary is dominated by Terrapon jarbua, Strongylura  strongylura and Etroplus suratensis.

Seasonal variability in diversity indices was computed by using PRIMER v6 software. The computed value ranges of biodiversity indices (TABLE 1.) were H' value from 3.4 to 3.66, D value from 6.2 to 8.73, J' value from 0.965 to 0.979, ∆ value from 78.06 to 82.11 and the Bray-Curtis similarity was found to be maximum (84.706 %) between summer and pre-monsoon.

A check list of estuarine fish species distributed in the Korampallam thermal estuary, Thoothukudi, southern Tamil Nadu was prepared based on the fish biodiversity during the experimental study period. The anthropogenic threats may call for conservation and monitoring measures in the near future.