Assessment of Sediment and Water Regimes in Island Ecosystems of the Gulf of Mannar: Implications for Ecological Monitoring

Abstract

Island ecosystems are highly dynamic, and this study examined sediment and water regimes across four coral islands in the Gulf of Mannar to evaluate their ecological significance. Sediment and water samples were collected from four islands, with sediment analyses covering grain size, calcium carbonate (CaCO₃), organic carbon, organic matter, and key water parameters: pH, salinity, temperature, conductivity, dissolved oxygen (DO), turbidity, and total dissolved solids (TDS). Standardized protocols ensured consistency, and data analysis (ANOVA, correlation, regression, Principal Component Analysis (PCA)) was used to assess spatial variability and interrelationships. Sediment composition varied significantly (p< 0.05) in terms of sand, silt, clay, calcium carbonate, organic carbon, and organic matter, with regression analysis revealing a positive trend for silt and negative trends for the other components. PCA (KMO = 0.402; Bartlett’s p< 0.0001) revealed two principal components explaining 87.05% of total variance, with Component 1 linked to sand, organic carbon, and organic matter, and Component 2 to silt, clay, calcium carbonate, and organic matter. Water parameters also varied significantly (p< 0.05); conductivity (r = 0.369) and temperature (r = 0.302) correlated with island location, while temperature was strongly associated with conductivity (r = 0.478) and TDS (r = 0.405). PCA (Kaiser-Meyer-Olkin (KMO) = 0.563; Bartlett’s p< 0.0001) identified ionic strength and thermal regime as key environmental drivers. These findings establish critical baseline data, offering a robust framework that demonstrates how sedimentary composition and physicochemical parameters jointly regulate benthic-pelagic interactions and ecosystem resilience. Overall, island-specific sediment and water patterns exert strong control on ecological processes, providing early detection of environmental shifts and strengthening evidence-based adaptive management. The study offers valuable insights for ecological monitoring and conservation within the Gulf of Mannar region.