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Creating a sea change

Informing policy on the conservation of coral reefs

Published: 12 July 2016

We urgently need to change our behaviour to protect coral reefs for future generations, says Professor Jörg Wiedenmann, Head of the Coral Reef Laboratory at the University of Southampton.

According to the World Wide Fund for Nature (WWF), coral reefs provide close to US$30bn each year in goods and services, as well as being very productive ecosystems, supporting enormous biodiversity.

Five things you might not know about coral:

  • Coral reefs cover less than 1% of the ocean floor but support 25% of all marine life on the planet.

  • Coral reefs provide nearly $30 billion each year in goods and services including fisheries, tourism, coastal protection and medicine.

  • A square kilometre of healthy, well-managed coral reef can yield a catch of over 15 tonnes of fish a year.

  • Some of the coral reefs on the planet today began growing over 50 million years ago.

  • Many species of coral are hermaphrodites, meaning they produce both sperm and eggs at the same time.

Coral reefs benefit society

Coral reefs have an impact on many industries. For example, they form the nurseries for about a quarter of the oceans’ fish; an estimated one billion people have some dependence on coral reefs for food and income from fishing. If properly managed, reefs can yield around 15 tonnes of fish and other seafood per square kilometre each year.

Coral species also contribute to future medical advances. Already coral reef organisms are being used in treatments for diseases like cancer and HIV. Just as with tropical forests, we may continue to find the answers to medical problems in the coral reefs as long as we can keep them healthy.

Reefs break down the power of waves during storms, hurricanes, typhoons and even tsunamis. By helping to prevent coastal erosion, flooding, and loss of property on the shore, the reefs save billions of dollars each year in terms of reduced insurance and reconstruction costs and reduced need to build costly coastal defences – not to mention the reduced human cost of destruction and displacement.

Tourism revenues generated by coral reefs are also significant. Australia’s Great Barrier Reef generates well over AU$1.3bn (US$1bn) per year from tourism; sustainably managed coral reef-based tourism can provide additional sources of income to poorer coastal communities in developing countries.

Coral bleaching

Corals usually have a brownish appearance due to algae living in their tissue. The corals cannot exist without the symbiotic relationship with these algae since they provide the coral with sugars and lipids and also allow the corals to access dissolved nitrogen and phosphorus in the water, a key to survival in nutrient-poor waters.

Factors that put a stress on the symbiotic relationship between corals and algae, such as increases in temperature and light, have the potential to result in coral bleaching – the loss of algae from the coral’s tissue, resulting in the coral turning white. In addition, research by Jörg and his team has shown that unfavourable levels of nutrients in the water column can also increase the susceptibility to bleaching. 

If corals don’t recover their symbionts relatively quickly then they often die, so coral mortality is usually quite high after a mass bleaching event, which in turn has a negative impact on the ecosystems they support.

“My team and I have been looking at the factors that affect coral bleaching for many years. At Southampton we have an advanced aquarium facility where we can monitor coral under simulated environmental conditions for long periods of time,” says Jörg. “We can therefore increase the temperature and light levels or introduce pollutants to understand how the coral responds.”

Our research delivers the scientific knowledge base that is required to motivate changing attitudes in the way humans interact with coral reef ecosystems.

Professor Jörg Wiedenmann - Head of the Coral Reef Laboratory at the University of Southampton

Jörg’s team also complements these experiments with studies in the Persian/Arabian Gulf (PAG). “Reef corals in the PAG withstand exceptionally high salinity and regular summer temperatures of around 35°C that kill similar coral species elsewhere,” he explains. “These thermo-tolerant communities established themselves over a relatively short time (approximately 6,000 years) under the pressure of rapid climate change and can therefore inform how other coral reefs may respond to global warming.”

Research carried out by the Southampton team shows that the existing biodiversity of coral reefs can be crucial for the adaptation of the underwater ecosystem to increases in sea water temperature. “Species that have already adapted to increased temperatures can occur in very low numbers, and in most cases it would be difficult to identify them in the crowd of less tolerant organisms,” explains Jörg. “So, crucially, if human societies continue to destroy coral reefs by overfishing, coastal construction and pollution, we are running the risk of losing this biodiversity and along with it those individuals that might allow the reefs to adapt to heat stress and climate change,” he adds.

“It is therefore of the utmost importance that we protect all existing ecosystems to prevent the biodiversity from being destroyed. We are working with environment agencies, for example in the Middle East, to find solutions that can remove harmful pollutants from waste water before they enter reefs. We are also informing them about the importance of biodiversity in these ecosystems in order to influence policy on reef conservation and management."

“Our research delivers the scientific knowledge base that is required to motivate changing attitudes in the way humans interact with coral reef ecosystems.”

More information about Jörg’s research

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