Coral reefs act as world climate change warning
07.11.2009
When coral reefs are in trouble it’s a warning for the whole world, writes Cheryl-Samantha Owen, Ocean Correspondent of the United Arab Emirates-based newspaper 7DAYS.
Formed from myriad living organisms over millennia, coral reefs are the most biologically diverse ecosystems in the ocean.
They provide essential habitats for numerous species of fish and invertebrates, and more than one quarter of all marine life depends on them for food and shelter. Worth an estimated $375 billion each year, they are also an important component of economic security for many nations.
To date, science has described 845 different species of reef-building corals, and yet these rainforests of the sea cover less than 1% of the earth’s surface. And their tenuous existence on our blue planet is getting weaker by the hour.
Assessments have shown that 70% of the world’s coral reefs are threatened or destroyed; 20% of those are damaged beyond repair, and in some areas many coral reefs have lost more than 80% of coral species.
The dreaded climate change is now acknowledged as one of the greatest perils to the continued existence of coral reefs worldwide.
Though coral reefs are bombarded by a host of challenges, including ocean acidification as a result of increasing levels of atmospheric carbon dioxide, increased predation by the crown of thorns starfish, invasive species and markets for marine products, one of the gravest and most immediate threats to their survival is from a phenomenon known as coral bleaching.
The term refers to the whitening of corals, which results from the degeneration and or loss of algae (called zooxanthellae) that live in the coral tissues.
Under normal conditions the zooxanthellae live in a state of harmony with the coral, both mutually benefiting the other, but an increase in seawater temperatures pushes corals over their thermal limit, causing them to expel their colourful symbiotic algae and bare their white skeletons.
During the 1998 El Nino and its associated warming seawater temperatures, not a single coral reef region escaped mass bleaching, resulting in death to 16% of the world’s reefs.
The unlucky reefs lost up to 90% of their coral cover. In that year alone the average coral cover based on 36 locations in the western Indian Ocean declined by about 40%.
Reefs in the northern Arabian Gulf and the Gulf of Oman were among some of the most heavily affected, while the southern Arabian Gulf and Arabian Sea suffered less.
For those of you who enjoy the captivating world beneath the waves – or to the more than 500 million people worldwide who currently depend on coral reefs for food, storm protection, jobs and recreation – the harsh truth does not simply finish here.
Further degradation is predicted, and by 2050 severe coral bleaching may be an annual event.
Other human-induced threats compound the devastation of climate change. In the face of coastal development, over-fishing, coral extraction, sedimentation and pollution, coral reefs barely stand a chance, and a world without reefs is rapidly becoming a very realistic scenario.
The loss of coral ecosystems will have enormous cascading and negative effects on the health of the entire ocean.
In essence, coral reefs are like the canaries that were taken down coal mines in the old days to act as indicators of dangerous gases present – a warning to humanity about the impacts of climate change and increasing human population pressure on the health of the planet.
Studies have shown that the more complex, mature, or intact an ecosystem, the more resilient it is to human disturbance.
A high number of levels on the food chain, which includes a healthy population of top predators such as sharks, give coral reefs a better chance of survival.
Marine science, such as that conducted or supported by the Save Our Seas Foundation (SOSF) on coral reefs in the Red Sea and on Aldabra in Seychelles is essential in gathering data for use in managing and protecting coral reefs. The foundation is also supporting coral propagation work off the Saudi Arabian coast.
These innovative projects have become a valuable tool in the race to nurture coral reefs back to health and redevelop a healthy marine system.
Small coral fragments, taken from mature artificial frames or from coral pieces broken off by divers or snorkellers, are attached to frames placed underwater, and within about three to four weeks coral growth is visible.
As well as pushing for policy changes and the lowering of carbon dioxide emission levels to a point below what they are today, each individual needs to take responsibility now for his or her part in the greater picture while the warning songs of the yellow canaries are still loud enough to be heard.
For more information on coral reefs, sharks and our blue planet, visit www.saveourseas.com