Morphologic adverse effects in hyperacute exposition to water-based mud in Hydractinia symbiolongicarpus (Hydractiniidae)

Abstract

Wastes derived from the drilling process on offshore oil platforms can leave up to 200 000 tons of cuttings in marine ecosystems. The principal pollutants in cuttings are drilling muds (DM). The DM are used to cool and lubricate the drill bit, counteract pressure forces and possible hydrocarbon leaks. DM contaminate the marine environment and have toxic adverse effects upon marine invertebrate organisms, mainly due to the presence of barite and traces of heavy metals. In this research, hyperacute exposure experiments were performed with complete mixtures of water-based drilling muds (WBM) at maximum concentration levels in Hydractinia symbiolongicarpus colonies. Results showed significant changes (p < 0.001) in polyp morphology immediately after contact with WBM, with a 1.5-fold increase in its diameter and a 75 % of retraction in the length of the tentacles. A biomass loss was observed after exposure (recovery phase). Near 50 % of polyps and stolonal mat were bioabsorbed with statistical significance (p < 0.01) at 72 h. Similar effects have been reported in other species of cnidarians, such as corals, where there is retraction of polyps and exoskeleton exposed areas also observed. Exposure to WBM generates tissue irritation and extreme cases loss of biomass.