Corals were highly threatened from both global and local-scale impacts all over the world. They are suffering massive declines in their diversity in response to human activities. In this study, we investigated the worldwide distribution patterns of corals and coral environments that contain high levels of species richness, and examined the anthropogenic effects on corals at a global scale. We mapped hotpots of coral species richness by extracting more than 540,000 coral records (Class Anthozoa) from the OBIS database and binned them to 2,592 cells in a 5 × 5 latitude-longitude grid. We then analyzed the relationships between global patterns of coral-species richness and environmental factors, such as sea-surface temperature, sea-surface salinity, partial pressure of CO2, and sea-surface current. We further compared the global pattern of coral species diversity with that of local threat of human activities to corals.
Results/Conclusions
We identified the hotspots of coral biodiversity to be restricted environments within tropical regions characterized by relatively high water temperatures (25–27°C), with salinities in the range of 34–35 PSU and partial pressure of CO2 between 360–380 µatm. Coral hotspots were primarily located in regions where warm oceanic currents flow at slower speeds (< 0.2 m s–1), such as the Caribbean Sea, Indian Ocean, and western Pacific Ocean. We identified the coral species for which habitats are under severe human-induced threat by coastal development and marine- and watershed-based pollution, exacerbated by industrialization, especially in areas of high coral-species richness. We found that the habitats for most Acropora species in particular are being subjected to high levels of human threat. Our results indicate that many areas of high coral species richness are threatened by human activities. Effective conservation of coral ecosystems will be extremely difficult witho ut the immediate implementation of large-scale protective measures.