Effect of mercury upon sporadic variations of sea urchin, Echinometra mathaei in the marine environment

Rapid industrialization in the State of Kuwait caused unprecedented pollution in the marine environment over the recent years. Studies on the effect of mercury (Hg) was least evidenced when compared to other trace metals in Echinometra mathaei, sea urchin collected from the Al-Fintas (Site-A) and Mina Abduallah (Site-B), Southern Kuwait. Reasons were attributed to (a) seasonal restriction of sea urchin abundance, (b) their low mercury concentrations in the Coastal waters (c) analytical imperfection and sensitivity of the instrumentation. In this study, the instrumental lacunae were overcome by using direct mercury analyzer (DMA-80, Milestone, Italy) which yielded consistent and reproducible Hg concentrations in all the samples. In nature, high Hg concentrations were observed in the seawater at 23 °C > 15 °C > 12 °C irrespective of the sites although the total mean Hg concentration was high in Site-A over Site-B. The 96 h and 180 d exposed E. mathaei to LC₅₀ toxicity, and bioaccumulation tests revealed high Hg concentrations in E. mathaei in relation to differential temperature in the sequence of 15 °C > 23 °C > 12 °C with minimal fluctuation of the hydrological parameters. Season-wise analysis showed high Hg concentrations in both the seawater and sea urchin body parts during the winter seasons compared to the summer season and irrespective of the two sites. Thus, this study recommends possible Hg mitigation that affects the socioeconomic condition of the marine resources besides, labeling the sea urchin as a bio-monitoring tool to Hg pollution.