Coral reefs are among the most productive and biodiverse ecosystems on earth. They are important habitat, spawning and breeding grounds for many important marine species, both fish and invertebrate species. Humans rely on coral reefs for many resources, such as seafood and new medicines, as well as a number of beneficial ecosystem services, such as coastal protection and nutrient cycling. Despite the importance of coral reefs to humans and other organisms, they are highly threatened due to their proximity to the coastline. A large portion of the world’s population lives within the coastal zone, and therefore reefs are heavily impacted by anthropogenic activities, such as development, pollution and agricultural resources. Many coastal systems are also heavily exploited for resources, and destructive fishing practices are a major threat to reefs worldwide.
Caribbean and Atlantic Ocean
The Caribbean and Atlantic Ocean are home to around 9% of the world’s mapped coral reefs. Of these reefs, two-thirds have been classified as at risk. Major contributors to coral reef degradation in these areas include threats such as sedimentation from upland deforestation, poor agricultural practices, pollution, overfishing and coastal development. The majority of highly threatened reefs are found along the Antilles archipelago, in countries such as Jamaica, Haiti, the Dominican Republic and Puerto Rico. Almost all the reefs found in the Florida Keys are moderately threatened, largely from farming and coastal development, and targeted fishing of lobster and conch. Reefs in the Bahamas and Yucatan Peninsula are classified as low risk, as are many of the remote reefs found off Belize, Nicaragua and Honduras.
The Indian Ocean contains around 15% of the world’s mapped reefs, half of which have been classified as at risk. Many of the highly threatened reefs are found off the coast of India and Sri Lanka, where destructive fishing practices, overexploitation of marine resources, pollution, coral mining for lime and sedimentation build up due to land clearing threaten the survival of many coral reefs. In East Africa, many of the most damaged reefs occur close to major towns or cities where they have been impacted by sewage discharge and overexploitation. Destructive fishing practices, such as blast fishing, and poor agricultural practice, have also been highlighted as threats to coral reefs along this coastline. In more remote locations, such as the Maldives and Chagos Archipelago, reefs have been assessed as being in better condition and are at a lower risk of degradation.
Middle East: The Red Sea and Arabian Gulf
Around 8% of the world’s coral reefs have been mapped to the Red Sea and Arabian Gulf, of which 60% have been classified as at risk. Major threats in this region include overfishing, coastal development, industrial pollution and oil spills. Around 30% of the world’s oil tankers pass through the Arabian Gulf, which is why coral reefs here are more likely to be damaged by oil spills than anywhere else. Reefs here are thought to be more susceptible to degradation because the region has limited water circulation and is prone to environmental temperature extremes. Tourism and related development have also been documented to have led to the degradation of corals in the Gulf of Aqaba.
South East Asia
One quarter of the world’s coral reefs can be found in South East Asia, one of the most threatened regions in the world. An estimated 80% of reefs are classified as at risk, and over half of them are classified as high risk. Reefs off the coasts of countries such as the Philippines, Java, Sabah, Eastern Sumatra and Sulawesi are heavily impacted by humans, as around 70% of people live within the coastal zone and rely heavily on the ocean for resources such as food. Some of the major threats in this region are overfishing, destructive fishing practices, pollution resulting from coastal development and the build-up of sediment. A large majority of coral reef cover can be found in the Philippines and Indonesia, together with extraordinarily high levels of biodiversity. Unfortunately, almost all reefs in the Philippines and around 83% of reefs in Indonesia are at risk, and very few remain in good condition.
The Pacific Ocean hosts around 40% of the world’s mapped reefs, 60% of which have been classified as low risk, making it one of the regions of least concern. Australia in particular, which is home to the Great Barrier Reef, has a high level (around 70%) of low risk classified reefs, largely due to good management practices. However, reefs in other densely populated areas face heavy anthropogenic pressures, such as logging, agricultural erosion, overfishing and coastal development. Some heavily impacted areas include Papua New Guinea, Vanuatu, Fiji, Hawaii and the Solomon Islands. Around 50% of reefs off the coasts of Hawaii and the Solomon Islands are classified as potentially threatened, and as many as 66% of the Fiji reefs are at risk.
The Good News
With the increase in global attention, knowledge gathering and awareness of the threats facing coral reefs, there is movement at local, national and international levels towards increased protection and therefore conservation of coral reefs. While we still have a long way to go towards improving our interactions with the environment and taking care of our planet, understanding the threats that face coral reefs is the first step to begin implementing changes to effectively protect these highly vulnerable systems. A common approach to protecting coral reefs is the establishment of MPAs (marine protected areas), which often restrict or completely ban the removal of organisms and certain fishing methods. These no take zones are effective at preventing damage to reefs from destructive fishing practices, as well as overharvesting of marine resources.
In conclusion, coral reefs are among the most highly threatened ecosystems on earth, with around 58% being classified as potentially threatened by anthropogenic disturbances. Some of the most species-rich reefs occur within the ocean surrounding South East Asia, which is one of the most highly threatened regions. Overexploitation of marine resources and coastal development have been identified as two of the most significant threats to coral reefs worldwide, although some regions are also exposed to other unique pressures. On the positive side, the Pacific region which contains the large area coverage of coral reefs is also among the least threatened regions, and there is much that other countries can learn from places like Australia, which ensure the protection of their reefs through effective management plans and the establishment of MPAs.