Abstract. Nur I, Aris EA, Yusnaini Y, Beavis S. 2021. The potential use of Octolasmis spp. parasites in mud crabs Scylla spp. as a bioindicator for mercury pollution. Biodiversitas 22: 3764-3772. Artisanal small-scale gold mining and the use of mercury is widespread across Indonesia, often characterized by relatively short-lived gold rushes. In the late and post-mining phases, mercury stored in mine tailings and river beds was transported down catchment, posing risks to ecosystems and human health over much longer time scales. These risks can be under-rated when mercury concentrations in water, sediments, and aquatic species are low enough to meet relevant guideline thresholds. In this study in Southeast Sulawesi, Indonesia, we have investigated the Costraca barnacle, Octolasmis, as a bioindicator of mercury contamination. The presence of Octolasmis parasites in mud crabs, Scylla spp., and the accumulation of mercury (Hg) in the hosts, parasites, and the ambient environment, were analyzed across both dry and wet seasons. Severe infestation of Octolasmis was assessed using prevalence, abundance, and intensity. Hg concentrations were significantly higher in the Octolasmis parasites than in the host tissues, water and sediments. The mean bioconcentration factor (BCF) of Hg equaled 7938.21 from water to parasites, and 28.91 from the host’s gill tissue to the parasites. The results suggest that Octolasmis spp. can be used effectively as a bioindicator in coastal catchments impacted by mercury contamination, even when concentrations of mercury are low in water and river sediments. The study provides the first report of Octolasmis spp. parasitized to mud crabs as a reliable bioindicator of Hg contamination and pollution.

Penelitian ini bertujuan untuk mengetahui jenis parasit dan tingkat serangannya serta kandungan logam berat merkuri (Hg) pada kepiting bakau (Scylla sp) Hasil Tangkapan di  Desa Rarongkeu Kec. Lantari Jaya, Kab. Bombana Sulawesi Tenggara. Pemeriksaan parasit dilakukan pada organ insang sedangkan pemeriksaan logam berat merkuri dilakukan pada beberapa organ yaitu, insang, daging, darah dan pada parasit yang menginfeksi insang (Octolasmis sp). Seluruh parasit yang ditemukan pada penelitian ini merupakan ektoparasit yang terdiri dari Octolasmis sp.,dan Ascarophis sp yang menginfeksi organ insang. Nilai prevalensi parasit berkisar antara 50 – 100 % dan intensitas 69 - 150 Ind/ekor. Hasil pemeriksaan konsentrasi logam berat pada daging adalah (0,15 mg/kg), Insang (0,087 mg/kg), dan darah (<0,002 ml/l). Kualitas air yang diperoleh menunjukkan bahwa kualitas air masih berada dalam kisaran toleransi untuk menunjang kehidupan organisme. Kata kunci : Scylla sp, Parasit, Prevalensi,