Assessment of heavy metal contamination and trophic status of coral reef sediments of the Lakshadweep Archipelago, Arabian Sea

Abstract

This study investigated the distribution, contamination status, and ecological implications of heavy metals in the Lakshadweep Archipelago corals and coral reef sediments and the role of labile organic matter on metal accumulation in sediments. Heavy metal concentrations were relatively higher in the inter-tidal sediments than in the lagoon and the corals. The geochemical indices generally indicated the low anthropogenic contribution of heavy metals in sediments, and according to the sediment quality guidelines, there are no adverse effects on the biota. Sedimentary biochemical constituents are dominated by carbohydrates (CHO) followed by Lipids (LPD) and Proteins (PRT), and the low values of PRT: CHO and LPD: CHO ratios indicated aged, refractory organic matter with low nutritional quality. A portion of CHO may be derived from terrestrial sources, and statistical analyses revealed that CHO and LPD are the potential carriers of toxic metals such as Cd, Co and As into the coral reef environment. The biota-sediment accumulation factor (BSAF) showed Cd as a macro concentrator and Zn, Ni, V and As as micro-macro concentrators in Lakshadweep corals.