Environmental impacts of dredging and other sediment disturbances on corals: A review

• Published in: Marine pollution bulletin 2012-09, Vol.64 (9), p.1737-1765
• Main Authors: Erftemeijer, Paul L.A., Riegl, Bernhard, Hoeksema, Bert W., Todd, Peter A.
• Format: Article
• Language: English
• Subjects: Animals; Anthozoa - physiology; Bacteria; calyx; coral polyps; Coral Reefs; Corals; Critical thresholds; Disturbances; Dredging; Dredging impacts; Environment; environmental impact; Environmental Monitoring; explosions; Geologic Sediments - analysis; inflation; larvae; light intensity; light requirement; Marine; Mitigation; mortality; mucus; mushrooms; necrosis; particle size; Reefs; risk; Sedimentation; Sediments; shade; Ships; suspended sediment; symbionts; Turbidity; Water Pollutants - analysis; water pollution; water quality
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2012.05.008

► Intensity, duration and frequency of sediment disturbance determine dredging impacts on corals. ► Sediment stress effects have been investigated in ∼10% of known reef-building coral species. ► Tolerance limits of coral reefs to suspended sediment vary widely from 100mgL−1. ► Tolerance limits of corals to sedimentation vary widely from 400mgcm−2day−1. ► Sensitivity to sediment stress is significantly related to coral growth form, but not calyx size. A review of published literature on the sensitivity of corals to turbidity and sedimentation is presented, with an emphasis on the effects of dredging. The risks and severity of impact from dredging (and other sediment disturbances) on corals are primarily related to the intensity, duration and frequency of exposure to increased turbidity and sedimentation. The sensitivity of a coral reef to dredging impacts and its ability to recover depend on the antecedent ecological conditions of the reef, its resilience and the ambient conditions normally experienced. Effects of sediment stress have so far been investigated in 89 coral species (∼10% of all known reef-building corals). Results of these investigations have provided a generic understanding of tolerance levels, response mechanisms, adaptations and threshold levels of corals to the effects of natural and anthropogenic sediment disturbances. Coral polyps undergo stress from high suspended-sediment concentrations and the subsequent effects on light attenuation which affect their algal symbionts. Minimum light requirements of corals range from