Journal of the Marine Biological Association of India

Accumulation of micro-organisms in Marcia recens (yellow clam), an edible bivalve of Ashtamudi estuary

Volume 65 Issue 1

Letty Titus and B. T. Sulekha

doi:10.6024/jmbai.2023.65.1.2378-08

Abstract

The Ashtamudi Estuary is one of the unique wetland ecosystems which is composed of fresh and saltwater habitats and has international importance as defined by the Ramsar convention. Though the wetland is noted for its valuable biotic resources, adorable beauty and strong endemicity, the backwater system is under stress due to contamination from waste disposal, industrialization and urbanization. The occurrence of total heterotrophic bacteria and E. coli in water, sediment and edible bivalve species, Marcia recens (Yellow clam) from three sites viz., Neendakara, Dalavapuram and Kureepuzha of the lake is seasonally analysed. Physicochemical parameters such as water temperature, pH, salinity, DO and BOD in surface water samples are measured following standard procedures. TPC and E. coli in water, sediment and the clam were analysed using Pour plate and MPN methods, respectively. The results show that counts of TPC and E. coli in lake components are comparatively higher in the monsoon season. Even though without spatial variation, analysis indicates slight temporal variation in TPC in water and sediment. Pearson’s correlation coefficients revealed a significant positive correlation between TPC and pH. In general MPN E. coli values were higher in clams than in sediments and water. There was an increase in accumulation in the clams irrespective of stations during the monsoon season, which exceeded the standards set by European Union for Class A waters. The positive correlation of rainfall with E.coli in bivalves shows the negative influence of rainwater on bacterial contamination in the lake. Higher E. coli densities in the lake and their bioaccumulation during monsoon season at certain pockets are a matter of concern. To improve consumer health protection, pollution reduction measures and sanitation programmes should be implemented.

Keywords

Ashtamudi Lake , bioaccumulation, TPC, marcia recens, yellow clam, E. coli

Date : 28-04-2023