Total organic carbon profile in water and sediment in coral reef ecosystem of Agatti Island, Lakshadweep Sea

Abstract

Total organic carbon profile in sea water (depth-wise) and sediment has been investigated on seasonal basis in the coral reef ecosystem of Agatti island, Lakshadweep sea. The TOC values of sea water and sediment were converted into percentage to understand its level of distribution. The level of TOC in the surface sea water ranged from 0.40 to 1.02 ppm and the level of TOC at the ~5 m depth ranged from 0.18 to 1.86 ppm. The pH did not show any variation depth-wise (7.65 to 8.49). Sedimentary organic carbon (SOC) was found in the range of 0.21 to 2.35 mg C/g. Significant seasonal variation was not found for water TOC and SOC levels. The pH for sediment was recorded from 7.79 to 8.62. Water pH showed significant positive correlation with sediment pH (R²=0.959). The sand fraction was found more in the texture followed by silt and clay. Clay was found to have positive correlation with SOC (P >0.01). The TOC profile in the Lakshadweep sea was found in the order: Surface water TOC < water TOC at ~5 m depth < SOC. The percentage composition of SOC showed more than 1000 times as compared to water TOC. However, the levels recorded in this study are found within the limit prescribed by EPA and its influence on coral reef ecosystem is discussed.