Environmental contamination using accumulation of metals in marine sponge,Sigmadocia fibulata inhabiting the coastal waters of Gulf of Mannar,India

Coastal marine ecosystems in many parts of the world are under unrelenting stress caused by urban development, pollutants and other ecological impacts such as building of infrastructure, land reclamation for port and industrial development, habitat modification, tourism and recreational activities. The present work is a first extensive field study using the marine sponge, Sigmadocia fibulata as a bioindicator to detect metal pollution between inshore and offshore environment of the ‘Gulf of Mannar’, India. Samples of S. fibulata were collected from different places of inshore (0.1–0.5?km) and offshore (3–5?kms) locations. Metal concentrations in water and bioaccumulation in sponges were determined by ICP-MS (Inductively coupled plasma-mass spectrometry). Enrichment of metal contamination was more in the inshore, when compared to offshore environment. Higher concentrations of metals Fe, Al, Ni, Mn, Cu, Cr, Co, Ba, Zn, V, Pb and Cd in inshore waters (3–6.4 times than offshore) may be due to the discharge of monsoonal rains, carrying a discharge of industrial and agricultural wastes and sewage directly into the coast. This is substantiated by a highly significant positive correlation between concentrations of metals in the water and accumulation in sponges. The bioaccumulation of metals in sponge tissue were in order of Fe?>?Al?>?Ni?>?Mn?>?Cu?> Cr?>?Co?>?Ba?>?Zn?>?V?>?Cd?>?Pb in both the inshore and offshore regions. Apparently, the macromolecule composition (sugars, proteins and lipids) was significantly reduced by the accumulation of metals in inshore sponges. The current findings indicated that the frequent monitoring is necessary to assess the eco-health of the marine environment by choosing bio-indicator species like S. fibulata, which provide accurate, reliable measurements of environmental quality.