Deep-sea coral Lophelia pertusa laboratory maintenance and exposure to barite using water recirculation systems

Abstract

Drilling activities usually discharge large quantities of fluids and drill cuttings, which are composed of fine particles, such as barite, that can physically affect Lophelia pertusa. An experiment to assess the effects of barite smothering on L. pertusa was conducted with a water recirculation system. The corals were collected in Santos Basin, Brazil. The experiment was conducted in 23 L cone-shaped aquaria, adapted with an individual water recirculation system. Each exposure to suspended barite particles (50 and 100 mg•L-1) plus a control group was maintained in triplicate. Three nubbins were accommodated in the aquaria and acclimated for 7 days. The experimental design simulated two cycles of discharge, followed by a recovery cycle of 7 days each, totaling 35 days. Nine polyps per treatment were monitored twice per day regarding their behavior levels. Time-lapse photographs were also taken during the recovery periods. Total polyp survival in the control was 100%, while those in the 50 and 100 mg•L-1 groups were 94.2 and 93.6%, respectively, with no significant difference between treatments. Polyp activity was different between treatments, with both exposed aquaria displaying higher activity than control. This was probably related to the natural cleaning behavior of L. pertusa. Key words: Barite smothering, sedimentation, impacts of oil and gas industry, Santos Basin, Southeastern Brazil, South Atlantic.