Bacterial accumulation in edible bivalve, Villorita cyprinoides of Ashtamudi estuarine wetland, a Ramsar site in Kerala State, India

Abstract

The Ashtamudi Lake in Kerala, recognized under the Ramsar Convention, showcases rich biodiversity but faces pollution threats from human activities. Of particular concern is the potential bacterial contamination of inland fishery resources due to these anthropogenic influences. The present study, seasonally analysed the total heterotrophic bacteria (THB) and E. coli in water, sediment and Villorita cyprinoides respectively using pour plate and MPN methods. Water temperature, pH, salinity, DO and BOD of water samples were also estimated. The results showed the presence of THB in water was more in monsoon season and in sediments and the organism in premonsoon season. However, E. coli counts were more in all the media in monsoon season. The E. coli count slightly exceeded the standards set by European Union for Class A waters. In general, THB and MPN E. coli values were the highest in the oyster. Pearson’s correlation showed highly significant positive correlation between THB and E. coli in all the phases. pH and salinity showed highly significant positive correlation with BAF and highly significant negative correlation with DO and rainfall. Conversely, rainfall and BOD showed significant negative correlation with BAF. The present study indicates that the density of E. coli in shellfish at some locations exceeds the standard limit set by Indian Standards.