Abstract

GIS mapping of submerged aquatic vegetations, associated fish assemblage and sediment distribution in Northern Palk Bay, Thanjavur District, Tamil Nadu
Palk Bay is located between India and Srilanka. This project is aimed to study the seagrass spread area, associated fishes and sediment types in northern Palk Bay. This two year project has completed acoustic seagrass survey and presently doing sediment sampling. For seagrass survey, transects perpendicular to shore were laid in GIS software which are distanced at 1 km in between them. Our research boat was oriented along the transect at a speed of 2-3 nautical miles/hours while operating habitat mapping echo sounder. The recorded data were exported to GIS software for generating percentage cover, canopy height, and depth and sediment maps. The acoustic survey was carried out all along the Thanjavur district that covered 220 square kilometers, which has identified 12,200 hectares of seagrass beds. This kind of study is first time conducted in India by this project and additionally we explored underwater canyon. Presently we are collecting sediment samples in every 500m along the same transects in order to analyze pH, total organic carbon, total nitrogen and total organic phosphorous. The study will be helpful to obtain accurate baseline data about the seagrass beds in the Palk Bay and sediment that are important for fishery.