Heavy metal enrichment characteristics and risk assessment of typical fishes in tropical seagrass beds

The ingestion of seagrass by herbivorous fish will affect the transfer process of metal elements in seagrass beds, and the accumulation of heavy metals will cause human ingestion risks. Taking two typical fish species (Siganus guttatus and S. fuscessens) eating seagrasses in two tropical seagrass beds as main research objects, we determined the enrichment of heavy metals and their contamination, and assessed the dietary exposure risk in seagrass bed environment and fishes. Then we further explored the transfer characteristics of heavy metals in seagrass bed ecosystems. The results show that the contents of Cu, Cd, Zn and Pb in fish muscles were at a low level. There are significant positive correlations between Cu and Pb, and between Zn and CD. The enrichment effects of Zn and Cu were greater than those of Cd and Pb, but only Zn showed an potential enrichment effect in these two fish muscles. The Zn contents in these two fishes showed a serious pollution risk, while Pb contents showed slight pollution, but the contents of Cu and Cd were at a normal risk level. Eating these two fishes has little health risk. Due to the different growth rates and food sources, the content, pollution and enrichment of heavy metals in S. fuscessens are slightly higher than those in S. guttatus. The contents and enrichment of heavy metals in seagrass beds are generally higher than those in fishes. The accumulation of heavy metals mainly occurs in seagrass, and the heavy metal content in fish decreases with higher trophic levels.