Ocean acidification
Ocean acidification is a global threat to coral reef ecosystems. Based on the biodiversity in the Coral Triangle area, damage will come to many sectors, because the coral reef is a fundamental ecosystem in the coastal area. Started by rising levels of atmospheric carbon dioxide, the calcium carbonate decrease then enhances bioerosion and dissolution rate. The CT should have oligotrophic waters, so the light would penetrate and support photosynthesis by zooxanthellae algae. However coral reef in West Maui, Hawaii, has a sustained condition of nutrient-rich, lower pH submarine groundwater discharge that lowers the pH of seawater. Also, the corals are expose to nitrate concentrations 50 times higher than ambient. Rates of coral calcification are substantially decreased, and rates of bioerosion are orders of magnitude higher than in healthy oligotrophic waters. Measurement using heavier nitrogen isotope (δ15N) values shows that eutrophication of reef seawater by land‐based sources of pollution can magnify the effects of ocean acidification through nutrient-driven-bioerosion. These conditions could contribute to the collapse of coastal coral reef ecosystems sooner than current projections based only on ocean acidification predict.