Microbiological quality of shellfish harvesting areas in the Ashtamudi and Vembanad estuaries (India): Environmental influences and compliance with international standards

• Published in: Marine pollution bulletin 2020-07, Vol.156, p.111255, Article 111255
• Main Authors: Chinnadurai, Shunmugavel, Campos, Carlos J.A., Geethalakshmi, V., Sharma, Jenni, Kripa, V., Mohamed, K.S.
• Format: Article
• Language: English
• Subjects: Accumulation factor; Best practice; Bivalves; Clams; Classification; Coliforms; Contamination; Estuaries; Faecal indicator organisms; Fecal coliforms; Harvesting; International standards; Legislation; Livestock; Marine molluscs; Microbial contamination; Monsoon season; Pollution control; Pollution sources; Risk assessment; Sanitation; Septic tanks; Sewage pollution; Shellfish; Shellfish fisheries; Surveying; Water analysis; Water pollution; Water sampling
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2020.111255

The sources of microbiological contamination in shellfish harvesting areas in the Ashtamudi and Vembanad estuaries were identified through a sanitary survey. Samples of shellfish and waters were tested for faecal indicator bacteria. Both estuaries receive high levels of contamination from septic tank discharges and areas with high numbers of birds and livestock. An assessment to illustrate the classification status of the harvesting areas indicated that 64% of oyster and 58% of clam samples from Ashtamudi and 54% of mussel samples from Vembanad would comply with the lower class B standard of the EU classification system. Most water results would comply with the faecal coliform standard for ‘Prohibited’ areas under the US classification system. None of the water samples from Ashtamudi were below the standard for ‘Approved’ areas. Pollution reduction measures and implementation of a sanitation programme according to international best practice would improve consumer health protection. •High levels of faecal contamination of human and animal origins in the estuaries•Concentrations of faecal coliforms elevate during monsoon periods.•Bacterial concentrations in shellfish correlate strongly with those in the waters.•On average, clams accumulate higher levels of coliforms than oysters.•Shellfish requires post-harvest treatment prior to marketing for human consumption.