Low mercury content in Seychelles seaweed: implications for aquaculture expansion

Abstract

Stable tropical conditions and a near-pristine marine environment in the Seychelles suggest a high potential for seaweed aquaculture to supply growing global markets for sustainable marine products. The aims of this study were to assess the mercury content in five seaweed species that are candidates for aquaculture in Seychelles: Gracilaria cortica, Gracilaria salicornia, Caulerpa racemosa, Sargassum spp., and Asparagopsis taxiformis. Mercury contamination is a significant con- cern in seaweed aquaculture because it may bioaccumulate, potentially affecting human health when derived products are used. Samples were collected from different sites in Seychelles, categorized as polluted or unpolluted, to evaluate the influence of environmental factors on mercury accumulation. The results showed that mercury contents were low across all tested seaweed species and sites, with the highest observed content of 0.0038 mg/kg (wet weight), well below international safety limits. Significant differences were found between species; however, site pollution level did not significantly influence mercury content. Low mercury content, in addition to a favourable physical environment, confirm that the region is suitable for seaweed aquaculture. It is recommended that other heavy metal concentrations are also assessed, to pro- vide a comprehensive safety evaluation of seaweed aquaculture in Seychelles.