The concentration of heavy metals in marine fish is important for assessing the health risks associated with fish consumption. In this study, the concentration of metals such as copper, lead and manganese were analyzed in the muscle tissue of five coral reef-associated fish species collected from the central Red Sea, Saudi Arabia. The maximum copper content of 0.183 µg g-1 (ww) was detected in fish samples. Fish samples also showed maximum lead and manganese values of 0.030 and 0.064 µg g-1 (ww), respectively. The metal concentration in fish tissue samples did not vary significantly between the fish species. In conclusion, the results obtained indicate that the content of heavy metals in the coral reef-associated fishes is below the values determined by various agencies for seafood safety.

Heavy metals are major stressors for benthic macroalgal communities in marine ecosystems. In this study, the effects of copper and cadmium on some physiological parameters along with antifouling defense of the marine macroalga Ulva reticulata were assessed under laboratory conditions. Macroalgal samples were treated with three concentrations (1 mg l−1, 3 mg l−1 and 5 mg l−1) of copper and cadmium for 2 and 7 days. After treatment, algal samples were analyzed for chlorophyll-a, carotenoid, total polyphenol and total antioxidant capacity. Also, algal extracts were tested against biofilm-forming bacteria strains to understand differences in antifouling activity. The results indicated that exposure of U. reticulata to copper and cadmium, on the one hand, induced protective mechanisms such as total phenol production and antioxidant capacity against metal stress and, on the other hand, reduced photosynthesis. While the extract obtained from control algal samples showed a strong inhibitory effect on the growth of biofilm-forming bacteria, treatment with heavy metals resulted in reduced antibiofilm activity. In general, the results revealed that exposure of macroalgae to heavy metals can affect antifouling defense traits in addition to changes in photosynthetic pigment content.

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