Anthropogenic biogeochemical impacts on coral reefs in the Pacific Islands—An overview

Coral reefs dominate the coastal environment in many Pacific Islands, being present as atolls, coral platforms, barrier and fringing reefs. With ever increasing populations and migration of people to the coast, the anthropogenic impacts on these reefs have increased dramatically in the last 30 years. While research on these impacts has been limited, some important progress has been made. This paper reviews some of the completed studies, with outcomes from American Samoa, Fiji, French Polynesia, Guam, Saipan, New Caledonia and Tonga presented. These studies indicate that the most significant impacts have been found in locations close to major urban centres or industrial and mining activities. The extent of impact varies from place to place with minimal impacts in the more isolated and less industrialised communities. Common anthropogenic impacts are contamination caused by inadequate sewage treatment, erosion from adjacent agricultural and urban expansion activities, poor waste management, eutrophication, inefficient and/or inappropriate pesticide use and hydrocarbons use, storage and management. The outcomes include contaminated sediments (trace metals, pesticides, PCBs, hydrocarbons) with some impacts on resident biota. In some instances, the edible quality of local fisheries resources has been significantly compromised.Even in locations with small populations, increasing populations and poor economic conditions have resulted in noticeable effects on the adjacent fringing reefs, including dramatic algal proliferation and declines in fish numbers resulting from increasing nutrient discharges and increased herbivore fish catches. Recovery measures including fishing bans and alternative fishing practices have been implemented to address these issues in some areas.