You may have heard that coral reefs are being threatened by human activity. For instance, the Fight for the Reef campaign aims to raise awareness about how proposed increases in shipping traffic and development of large ports near the Great Barrier Reef would negatively impact the largest coral reef system in the world.
Scleractinian corals can only survive in the sunlit waters of the tropics - less than 1% of the ocean provides acceptable habitat. Corals are also sensitive to local environmental conditions - warmer water temperatures, sedimentation, nutrient runoff, and heavy metal pollution are just some of the factors leading to the destruction of coral reefs worldwide.
But why should we all be worried about coral reefs, particularly when many of us live very far from the tropical oceans?
Coral reefs provide food to millions of humans. Corals, like trees, provide three-dimensional structure and substrate to house and feed fish and other marine animals that humans eat. Some estimates say that over 1 billion people depend on food from coral reefs, and reefs as a whole might be worth around $172 billion for every year they continue to provide essential services to humans, like food.
Coral reefs protect and create land. Coral reefs can dissipate wave energy from storms and tsunamis, reducing damage on adjacent land. Atoll islands continue to exist above the ocean's surface long after the volcanic island upon which they first grew has cooled and sunk below the waves, due exclusively to the growth of corals and other reef-associated organisms like large foraminifera.
Coral reefs might supply natural medicines. Compounds effective against disease-causing agents like bacteria and fungi already exist in nature - and could be developed into effective drugs for humans if they can be isolated. Coral reefs are a likely place to find these natural products, due to their tremendous biodiversity.
Coral reefs are beautiful and intrinsically full of wonder. Nothing much compares to diving below the surface of clear turquoise water and seeing a natural wonderland more intricate and complex than you could possibly dream up. For me, that's enough.
References
Bellwood, D. R. et al. Confronting the Coral Reef Crisis Nature 429, 827-833 (2004).
Henkel, T. P. Coral Reefs Nature Education Knowledge3, 12 (2012).
Knowlton, N. et al. Coral Reef Biodiversity In: Life in the World's Oceans, Edited by A.D. McIntyre (2010).
Moberg, F., Folke, C. Ecological Goods and Services of Coral Reef Ecosystems Ecological Economics 29, 215-233 (1999).
Nyström, M., Folke, C., Moberg, F. Coral Reef Disturbance and Resilience in a Human-Dominated Environment Trends in Ecology and Evolution 15, 413-417 (2000).
Pandolfi, J. et al. Global Trajectories of the Long-Term Decline of Coral Reef Ecosystems Science 301, 955-958 (2003).
Wells, S., Ravilious, C., Corcoran, E. In the Front Line: Shoreline Protection and Other Ecosystem Services from Mangroves and Coral Reefs UNEP-WCMC Biodiversity Series, 24 UNEP/WCMC: Cambridge (2006).
All photographs by Jessica Carilli
Why are corals so important?
Coral reefs are home to 1/4 of all marine species,
and are vital to 500 million people in the world.
Find out more
Home to exceptional biodiversity
In these labyrinths of living limestone, scientists estimate that more than a million animal and plant species are associated with them and that they are home to more than 25% of all marine life.
They are also the basis for the formation of other ecosystems. In fact, the grazing of coral formations by hordes of parrotfish leads to the formation of very large expanses of sand; this, through the action of currents, leads to the formation of shallows, islands and above all, in favourable areas, to the formation of mangroves and other coastal forests.
Coastal protection
Reefs occupy only a tiny part of the seabed: less than 0.2%. Yet they are found along more than 150,000 kilometers of coastline in more than 100 countries and territories.
Due to their massive formation between the surface and the first few dozen meters of depth, coral reefs form a barrier that absorbs the elements coming from the open sea in a very efficient way.
They absorb wave energy and contribute to the reduction of coastal erosion. They reduce damage in the event of storms, hurricanes and other cyclones, as well as, to some extent, the energy of tsunamis. In doing so, they protect both the ecosystems between the reefs and the coasts, such as lagoons with sea grass beds, as well as human settlements along the coast.
Their action is so effective that man imitates it by immersing concrete structures along some of our fragile coasts. Without this protective role, some countries located in atolls would no longer exist.
A food resource
More than 500 million people (including 40 million fishermen), i.e. almost 8% of the world’s population, depend on coral reefs directly in terms of coastal protection, fisheries resources and tourism.
A large proportion of these human populations live in developing countries and island nations and therefore depend to a large extent on food taken directly from reef waters and thus depend on the direct and indirect means of subsistence they can derive from them.
Reef animals are an important source of protein. Coral reefs provide about 10% of the fish caught worldwide. But this figure rises to 20-25% in developing countries, and 70-90% in Southeast Asian countries.
“Well-managed” reefs can yield between 5 and 15 tons of fish, crustaceans, molluscs and other invertebrates per square kilometer.
Of economic importance
As a result of direct revenues from fishing, reefs provide a resource and services that are worth billions of dollars each year.
Millions of people around the world depend on reefs for food, protection and employment. These figures are all the more impressive because reefs cover around 1% of the earth’s surface.
According to an estimate, the total annual net benefit of the world’s coral reefs is $29.8 billion.
Tourism and recreation account for $9.6 billion, coastal protection for $9 billion, fisheries for $5.7 billion and biodiversity for $5.5 billion (Cesar, Burke and Pet-Soede, 2003).
A tourist attraction
Reefs are often the backbone of tropical regions’ economies, where they are generally located.
They attract divers, freedivers, recreational fishermen and lovers of white sandy beaches. More than 100 countries benefit from reef-related tourism and it contributes to more than 30% of export earnings in more than 20 countries.
Local economies benefit from billions of dollars, from visitors that come to admire their reefs to companies exploiting reef ecosystems. In many small islands, more than 90% of new economic development depends on this coastal tourism.
Reef tourism, if managed in a sustainable manner, i.e. respectful of reefs by limiting the destruction and pollution induced by this same tourism, especially when it comes to mass tourism, can provide alternative or complementary income resources for coastal communities in developing countries.
A medical future
Deprived to a very large extent of any possibility of movement, corals have developed an arsenal of very effective chemical weapons to defend themselves and fight in the conquest of reef space.
Coral organisms are of great interest in the search for treatments for certain cancers or the aging of cells. Moreover, due to its nature that is very similar to our bones, the coral’s skeleton, used since 1970 for bone grafts, is a promising lead for bone regeneration.
Since only an infinitesimal portion of reef organisms have been sampled, analyzed and tested, the potential for new pharmaceutical discoveries is enormous.
We use cookies to collect information about how you interact with our website and allow us to remember you. To find out more about the cookies we use, see our
privacy policy.
Reject all Accept all