doi:10.1038/nindia.2014.77 Published online 2 June 2014
Toxic pollutants in the waters of Goa are leaving a permanent imprint in the DNA of small marine snails1. Scientists say the molluscs could act as a sentinel species for bio-monitoring of pollution along the coastal ecosystem of one of the hottest tourism destinations of India.
Untreated sewage water, discharge from industries and oil spills from cargo ships and motor boats, release DNA-damaging toxins such as polycyclic aromatic hydrocarbon (PAH) and heavy metals. The researchers set out to study how these ‘genotoxins’ might be affecting marine organisms.
They collected several individuals of Morula granulata, a predatory snail, from nine beaches across Goa – Arambol, Anjuna, Sinquerim, Dona Paula, Bogmalo, Hollant, Velsao, Betul and Palolem. In the lab, they isolated DNA from these snails and assessed the extent of genetic damage. They also measured numerous parameters of water quality including temperature, pH, salinity, PAH, as well as nitrate and phosphate concentrations.
The researchers found that the snails showed higher DNA damage in beaches that had greater concentration of carcinogenic poly-aromatic hydrocarbon (PAH) in the sediments. The two beaches where these snails showed the highest loss of DNA integrity, Sinquerim (47%) and Hollant (56%) had regular oil spills from cargo ships, fishing trawlers, tourist boats, as well as extensive industrial discharges, all major source of PAHs. Genetic damage also seemed linked to salinity as well as nitrate and phosphate concentrations.
It is important to study how a continually changing environment affects the genome and immunological response in marine organisms, says Anupam Sarkar, one of the authors of the study. "The extent of DNA damage in marine gastropods is an important indicator of the ecotoxicological impact of contaminating agents," he added.
1. Sarkar, A. et al. Evaluation of impairment of DNA in marine gastropod, Morula granulata as a biomarker of marine pollution. Ecotox. Environ. Safe. (2014) doi: 10.1016/ecoenv.2014.04.023