Spatial variability of heavy metals in estuarine, mangrove and coastal ecosystems along Parangipettai, Southeast coast of India.

An elaborate survey on the contamination of heavy metals was carried out in surface sediments of different ecosystems such as Vellar-Coleroon estuarine, Pichavaram mangrove and coastal region of Parangipettai, Southeast coast of India. The study was intended since, the coal based thermal power plant and oil refinery plant are proposed to set up along this coast and aquaculture industries and dredging activities are developing. The parameters such as soil texture, pH, total organic carbon (TOC) and heavy metal (Fe, Mn, Cu, Cd, Zn and Ni) concentrations were analyzed for the surface sediments during pre and postmonsoon seasons. Among the metals analyzed, Fe and Mn were found to have dominant as the levels were recorded as 11,804 µg g-1 and 845.2 µg g-1 respectively. A significant correlation was observed between total organic carbon (TOC) and heavy metals. In the mangrove ecosystem, the levels of heavy metals found to be maximum indicating that the rich organic matter acts as an efficient binding agent for metals. The overall finding of the present study indicated that the sediments from the entire Vellar-Coleroon estuarine and Pichavaram mangrove ecosystems were found moderately polluted with cadmium metal. The result of cluster analysis indicated disparity in accumulation of heavy metals in sediments of different ecosystems due to the variations in organic matter. The heavy metals were transported from land to coastal through flood during monsoon season reflecting the variations in their levels in different ecosystems at postmonsoon season.

Isolation and molecular characterization of multidrug-resistant halophilic bacteria from shrimp farm effluents of Parangipettai coastal waters.

Multidrug resistance of heterotrophic bacteria isolated from an aquaculture farm effluent in Parangipettai, at the southeastern coast of India, was investigated. In the initial screening, 27 antibiotic-resistant strains were isolated. All the strains were tested for antibiotic susceptibility against chloramphenicol with varying concentrations. From these, two highly resistant strains, i.e. S1 and S5, were isolated. The selected strains were identified by 16S ribosomal RNA (rRNA) sequencing techniques and confirmed as Bacillus pumilus and Bacillus flexus. Both the antibiotic-resistant strains were further utilized for multidrug susceptibility test by using various antibiotics. These two strains showed antibiotic resistance to 14 of 17 antibiotics tested. Both microdilution assay and well assay methods were used to determine the minimal inhibitory concentration (MIC) for the sensitive strains. Both the tests were shown to be almost similar. Our study highlights the occurrence of multidrug-resistant bacteria in the shrimp farm effluents.

Metals in fish along the southeast coast of India.

Metal concentrations (cadmium, chromium, iron, lead, copper, manganese, zinc and mercury) in the muscle of five fish species (Epinephelus chlorostigma, Lutjanus russelli, Terapon jarbua, Cynoglossus arel and Lagocephalus lunaris) from the six fish landing centres along southeast coast of India were measured. In Cuddalore and Mudasalodai, the level of toxic metals cadmium, chromium and manganese were well above the permissible limits. Concentrations of cadmium, chromium, manganese and mercury in C. arel were above the permissible limit and it is consistent with their habitat and diet. The results showed a relationship between metal concentrations and pollution status of the areas.