Journal of Environmental Biology

Nutrient characteristics and sediment texture of the seagrass beds of the Gulf of Mannar

 T. Thangaradjou*¹ and L. Kannan²

¹Centre of Advanced Study in Marine Biology, Annamalai University, Parangipettai – 608 502, India.

²Thiruvalluvar University, Vellore-632 004, India

(Received: January 15, 2005 ; Revised received: September 20, 2005; Accepted: October 10, 2005)

Abstract: Changes in nutrient concentrations and sediment texture of the seagrass beds were recorded for two years from July 1996 to June 1998 at monthly intervals at two stations (Station 1 - Manoli island; Station 2 - Chinnapalam) of the Gulf of Mannar Marine Biosphere Reserve. Different nutrients in water showed varied concentrations in different seasons. Phosphate concentration varied between 2.32 and 7.32mM, nitrate concentration ranged from 5.2 to 18.78mM and nitrite concentration from 1.92 to 7.32mM. Sand was a major component of the sediments, followed by silt and clay at both the stations. At station 1, sand composition varied between 85.9 and 95.3% while at station 2, it varied between 81.9 and 93.6%. Silt composition varied between 3.1 and 9.4% at station 1and at station 2, it varied between 4.0 and 12.4%. At station 1, clay composition varied from 1.6 to 4.6% and at station 2, it varied between 2.1 and 5.6%. The present study revealed that the nutrients and sediment characteristics of the seagrass beds of the Gulf of Mannar has clear spatial and temporal variations. They are largely interlinked and influenced by the human activities and climatic changes and are individually or jointly governing the distribution, diversity, biomass and productivity of the seagrasses of the Gulf of Mannar.

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