Abstract
Abstract This study examined the diversity of mercury (Hg) content in the substrate and thallus of Sargassaceae and its bioaccumulation potential. The samples used consisted of the genera Sargassum and Sirophysalis. Samples were collected from four coastal locations on Lombok Island: Pelangan, Elak-elak, Batu Layar, and Lendang Luar. The sampling locations were determined based on traditional gold processing activities and the presence of Sargassaceae samples. Sargassaceae and sediment samples were collected using purposive sampling. Mercury content in the sediment and algal thallus was quantified using an Atomic Absorption Spectrophotometer (AAS). The results showed that sediment Hg concentrations varied between 0.160 and 2.369 ppm, while algal Hg content ranged from 0.141 to 4.114 ppm. The highest bioaccumulation factor (BCF = 15.34) was observed in Sargassum siliquosum from Elak-elak, indicating strong Hg uptake capacity, while the lowest BCF (0.06) was found in Sargassum siliquosum from Batu Layar. Spatial differences in Hg accumulation in the Sargassaceae family are related to variations in Hg concentration in the substrate, which affects metal availability. Overall, Sargassum species exhibited higher Hg bioaccumulation potential than Sirophysalis, indicating their suitability as bioindicators of mercury contamination.