Bioaccumulation of Heavy Metals and Hydrocarbon by Clibanarius africanus (Hermit Crab) Exposed to Produced Water

This study examined the level of heavy metals (zinc, barium, arsenic, mercury, nickel, lead, cobalt, copper, chromium, cadmium and iron) and Hydrocarbon related parameters (Total petroleum hydrocarbon, Total hydrocarbon content and Polycyclic aromatic hydrocarbon) in Clibanarius africanus (hermit crab) exposed to produced water. The Clibanarius africanus was sourced from African Regional Aquaculture Centre (ARAC), Buguma, in Rivers State, while the treated produced water was obtained from an Oil and Gas facility within Mbo LGA, Akwa Ibom State, along Calabar estuary in the Niger Delta Region of Nigeria. The Clibanarius africanus was exposed to the produced water for 28 days and heavy metals and hydrocarbon related parameters were analysed at varying time intervals: day 0, 7, 14, 21 and 28 using standard procedure. The results of the heavy metals and Hydrocarbon related parameter analyses showed a significant increase (p<0.05) as the exposure duration to produced water increased, suggesting bioaccumulation by the test organisms. In addition, metals such as zinc, copper, chromium and iron had their limits within the threshold recommended by Food and Agricultural Organization/Word Health Organization, Median International Standard and European Union for food fish consumed by human within the study period. Other parameters such as cadmium and lead had their values within and above the limits specified by some agencies. Since crustaceans which are part of the food chain have the capacity to accumulate these toxicants, it could end up in humans that consume these as food where they cause diseases, based on the type and concentration of the toxicants. Therefore, there is need for the agency responsible for the regulation of effluents/waste water from oil and gas facilities to review their discharge guideline towards zero harmful discharge into the water bodies like other regions so as to forestall the adverse effect of the produced water discharges on the aquatic organisms.

Keywords: Bioaccumulation, Clibanarius africanus, Heavy metals, Hydrocarbon, Produced water.