Assessment of heavy metal concentrations in seabed sediments of the coral ecosystem in Bangladesh: An in-depth analysis of ecotoxicity and ecological health

Saint Martin Island (SMI), the first coral reef ecosystem at the Bay of Bengal is ecologically significant for its unique biological richness. The purpose of this study is to monitor environmental health by measuring hazardous metals in coral reef and evaluating the ecological status. The study assesses environmental health state and identifies the probable source using various indices such as contamination factor and degree, pollution load index, geo accumulation index, enrichment factor, ecological risk index, potential ecological risk index, mean effects range median quotient, modified hazard quotient, toxicity risk indicator, and positive matrix factorization, hieracia cluster analysis. The measured constituents are found in range, for As (0.07–2.30), Pb (18.18–28.53), Hg (0.03–0.08), Fe (30160–65445.21), Cd (0.02–5.73), Mn (511–806), Cu (6.2–22.85), Zn (27.7–87), Cr (14.13–58.73), and Ni (32.25–132.13) mg/kg. All the stations were found with higher concentration of Ni in seabed sediments than the threshold limits. The source of toxins from upstream is an issue to consider when analyzing coral health from an ecotoxicological standpoint. The study area also coincided with the newly established SMI marine protected area (MPA) by Ministry of Forest, Environment and Climate Change, Bangladesh, and the sample sites are distinct within the framework of the methodological study. Thus, this research is expected to help for monitoring and establishing baseline for evaluating the ecological status for management plans.