We report the results of an aquaria-based experiment testing the effects of suspended particles generated during potential mining activities, on a common habitat-building coral species in the Azores, Dentomuricea aff. meteor. Coral fragments were maintained in 10-L aquaria and exposed to three experimental treatments for a period of four weeks at the DeepSeaLab aquaria facilities (Okeanos-University of the Azores): (1) control conditions (no added sediments); (2) suspended polymetallic sulphide (PMS) particles; (3) suspended quartz particles. The concentration of suspended PMS and quartz particles in each treatment was measured during an exposure period of 4 hours. Suspended particle concentrations were measured one minute after particle addition, and then at intervals of 5, 15, 30 minutes, 1 hour, 2 hours and 4 hours after particle addition in the PMS and quartz particle treatments and in control aquaria with no particle addition.

Suspended sediments: Concentration of suspended particles during the 4-hour closed system periodControl: no sediment additionPMS: suspended polymetallic sulfide particles Quartz: suspended quartz particlesExperiment duration: 27 daysParticle concentration: 25 mg/l delivered in 4 hours closed water flow systemExperimental time: time 0 (start of experiment), other times: days after beginning of experiment