We report the results of an aquaria-based experiment testing the effects of simulated sediment plumes generated during mining activities for the extraction of ferromanganese nodules in the Clarion-Clipperton Fracture Zone (CCFZ), northeastern equatorial Pacific Ocean, and seafloor massive sulfides from a hydrothermal vent field in the Azores, northeast Atlantic, on the physiology of the cold-water octocoral Dentomuricea aff. meteor. Coral fragments were exposed to five experimental treatments for a period of four weeks at the DeepSeaLab aquaria facilities (Okeanos-University of the Azores): (1) suspended plumes of abyssal sediments from nodule fields at a concentration of 10 mg/l (2) suspended plumes of abyssal sediments from nodule fields at a concentration of 50 mg/l; (3) hydrothermal polymetallic sulphide particles at a concentration of 10 mg/l; (4) hydrothermal polymetallic sulphide particles at a concentration of 50 mg/l; and (5) a control treatment with no sediment addition. The surface area of the coral tissue lost during the experiment was quantified using photographs of the coral fragments and ImageJ software. Measurements were made every week for a period of 4 weeks.

Species: Dentomuricea aff. meteor1. Experimental treatmentsControl: no particle additionPMS10: Polymetallic sulphides at a concentration of 10 mg/lPMS50: Polymetallic sulphides at a concentration of 50 mg/lNFS10: Nodule field sediments at a concentration of 10 mg/lNFS50: Nodule field sediments at a concentration of 50 mg/lParticles delivered daily in 12 hours cycles