Assessment of mercury contamination and food composition in commercially important marine fishes in the southern South China Sea

Abstract

This study examined mercury contamination in common commercial marine fish caught from the South China Sea. Specifically, the muscle tissue mercury levels of four species (n = 10), one each from the Scombridae, Serranidae, Carangidae, and Nemipteridae families, was examined using a direct mercury analyzer (MA-3000); their trophic level was assessed using TrophLab tm software. Provisional tolerable weekly intake levels (PTWI) and the relationships between length–mercury concentration and weight–mercury concentration of species using Pearson correlation coefficient were identified. Samples from the Serranidae family had the highest muscle mercury concentrations, followed by Nemipteridae, Carangidae, and Scombridae in descending order. The results show that the highest mercury concentrations were found in Epinephelus heniochus (2.34 ±0.22μg/g) from the Serranidae family, while the lowest mercury concentrations were found in Scomberomorus guttatus (0.05 ± 0.00 μg/g) from the Scombridae family. This study suggests that factors such as size, composition of food in the fish gut, and habitat had the greatest influence on the mercury levels found in these fishes. The PTWI data showed that only 31% of the species in the current study had not exceeded the recommended safety level of 1.6 μg/kg BW/week methylmercury intake. A consideration of PTWI can help to reduce fish consumption risks to consumers by providing a recommended consumption level of each fish.