Potential of metal contamination to affect the food safety of seaweed (Caulerpa spp.) cultured in coastal ponds in Sulawesi, Indonesia

•Caulerpa spp. are traditionally consumed directly as a salad vegetable in coastal areas of South Sulawesi, Indonesia.•We evaluated the metal concentrations of Caulerpa cultured in coastal ponds from a food safety perspective.•Of the metals studied only As (0.7 mg/kg) and Pb (0.35 mg/kg) were recorded at concentrations approaching the national food safety (BSN) limits of Indonesia (1.0 and 0.5 mg/kg respectively).•There was some indication that stronger acid-sulfate soil conditions than seen in our study could lead to elevated levels of heavy metals in cultured Caulerpa.

This study evaluated metal concentrations in Caulerpa spp. cultured in 'traditional' coastal ponds in South Sulawesi and consumed locally as food. Although Caulerpa spp. are a rich source of supplemental dietary nutrients, like many macroalgal species they are also capable of bioaccumulating potentially toxic metals. We measured the metal concentrations of Caulerpa spp. from several locations in South Sulawesi to determine (1) whether cultivated Caulerpa spp. posed a potential risk to consumers, (2) whether Caulerpa spp. from cultivated ponds had different metal content that varied between localities and (3) whether there was any evidence for increased concentrations of heavy metals in Caulerpa spp. cultivated in ponds with known acid sulfate soils (ASS). Of the metals studied only As (0.7 mg kg−1) and Pb (0.35 mg kg−1) were recorded at concentrations approaching the national food safety (BSN) limits of Indonesia (1.0 and 0.5 mg kg−1 respectively). Locality differences were observed between samples that could be explained by the background geography of sites. There was some indication that ASS conditions could lead to elevated levels of heavy metals. Consequently, we propose that the potential acidity of pond soil is considered when cultivating Caulerpa.