Accumulation of Total Heterotrophic Bacteria and E. coli in Villorita cyprinoides in the Anchuthengu-Akathumuri Backwaters, Southern Kerala, India

Abstract

The Anchuthengu-Akathumuri backwater system in Kerala, India, is vital for local livelihoods but faces increasing pressures from tourism and urban development, threatening water and sediment quality. This study assesses microbial contamination in water, sediment, and the bivalve Villorita cyprinoides over a year (February 2022 to March 2023) at five sampling stations with varying levels of human influence. The study employed a combination of field and laboratory methodologies, including monthly sampling of water and sediment from five stations, followed by microbiological analysis using standard plate count and most probable number (MPN) techniques. Physicochemical parameters, such as water temperature, pH, conductivity, salinity, dissolved oxygen (DO), and biochemical oxygen demand (BOD), were also analyzed. The results showed that the annual mean log values of TPC in water, sediment, and V. cyprinoides samples were 5.35±0.34, 7.55±0.31, and 7.73±0.30 log10cfu/ml, respectively. E. coli levels in water, sediment, and V. cyprinoides samples ranged from 1.03±0.32 to 1.58±0.56 log10 MPN. Seasonal variations revealed higher TPC levels during pre-monsoon (PRM) with 5.38±0.22 log10cfu/ml in water and 7.41±0.25 log10cfu/g in sediment. Physicochemical parameters showed significant variations, with water temperature ranging from 27.6±2.45°C (post-monsoon) to 30.5±3.8°C (PRM). pH levels ranged from 7.18±0.14 to 7.56±0.06, while conductivity varied from 5.67±2.36 to 13.97±1.4 mS/cm. Correlation analysis revealed significant relationships between physicochemical and microbiological parameters, highlighting the importance of considering both aspects in water quality assessments. Additonally, bioaccumulation study revealed higher microbial concentrations in Villorita cyprinoides compared to surrounding water and sediment, raising food safety concerns. The findings emphasize the need for ongoing monitoring and management of microbial contamination to protect public health and ecosystem integrity. Recommended strategies include reducing anthropogenic impacts, improving waste management, and promoting sustainable development practices. This research offers valuable insights into microbial pollution dynamics, guiding targeted interventions for sustainable coastal management and community health protection.