Effects of sediment pulses on the deep-sea coral Goniocorella dumosa

Abstract

ABSTRACT Seabed-contact activities operating in the deep sea can generate sediment plumes that pose varying levels of threat to benthic fauna. Corals are important components of deep-sea ecosystems and can be particularly sensitive to elevated suspended sediment concentrations. In this study, we exposed colony fragments of the New Zealand deep-sea scleractinian Goniocorella dumosa to four-day pulses of four target sediment concentrations: 0 mg l−1 (representing control conditions) and 45, 102 and 435 mg l−1 (targeting concentrations expected from mining and trawling disturbance). All coral fragments survived. Oxygen consumption rates were not affected by treatments and time. No visible detrimental effects on coral health were noted after the first pulse of sediment exposure. However, both a loss of coenosarc and instances of polyp mortality were observed on fragments exposed to suspended sediments during the following sediment pulses. This observed decline in coral health over time indicates that G. dumosa could cope with sediment disturbance from human activities that disturb the seafloor for periods of up to four days, but that repeated, or prolonged sediment exposure could cause a deterioration in the health condition of this species. This hypothesis should be further investigated in following studies.