Comparison of hydrographic and sediment characteristics of seagrass meadows of Gulf of Mannar and Palk Bay, South West Coast of India

Abstract

Near shore of Gulf of Mannar and Palk Bay are characterized by seagrass meadows which has potential in coastal protection and as nursery feeding grounds for marine organisms besides use by fishers as medicine. The dynamic ecological disturbances affect the meadows constantly and as it is important to understand the effects, a study on the hydro-chemical and sediment characteristics of major seagrass meadows in these areas was carried out to access the pollution status and factors regulating the seagrass population. The nutrients and heavy metals concentrations were high in Gulf of Mannar than Palk Bay. Dissolved oxygen, nitrate and total nitrogen levels in the surface waters were varied from 5.39 to 8.16 mg per l, 2.73 to 5.18 µmol per l and 15.23 to 126.90 µmol per l respectively. The sediment characteristics showed sandy in nature ( 72.02 - 97.06% ) and the total organic carbon in the sediment varied from 0.24 - 0.58%. Even though, the heavy metals were low in sediments and water compared to reported data, toxic metals such as mercury, arsenic, cadmium and lead were detected in the sediments and their presence may affect the utilization of seagrasses.