Give Corals Back their Colour

They are referred to as rainforests of the sea. But things are not looking bright for these valuable, vulnerable ecosystems. It is estimated by the Global Coral Reef Monitoring Network that 40% of the world's coral reefs will be lost by 2010, and another 20% by 2030 on account of pollution, over fishing, dredging and global warming - the last emerging as the biggest threat of all. When water temperatures turn too high, corals turn white and die. Bleaching events are now occurring yearly.

Reefs of the Gulf

About 8 % of the world's mapped reefs are found in the Middle East, where the Arabian Gulf, which has shallow, fringing reefs, is at the northern limit of coral reef distribution. The best reefs exist along the Saudi coast, while the marine environments of Bahrain, Qatar and Iran have reefs of low diversity. The UAE has extensive offshore reefs and many bank and patch reefs growing in shallow waters around offshore islands along 550 km of the Gulf coast.

The Arabian Gulf reefs may not be very diverse compared to truly tropical areas, but they are of interest for the very reasons that they survive in this environment. They are can withstand temperatures much higher than corals from other reefs in the world. The area, very dry with large seasonal fluctuations in temperature and salinity, supports reef animals and plants that survive under conditions of high stress. These reefs are, therefore, of scientific interest in studies of the impact of increased sea temperatures and global warming.

The Threats

But will the Gulf reefs survive the pollution from towns and industries? From oil exploitation and transport; coastal development; the mining and quarrying; the huge power and desalination plants; the solid waste dumped from ships; reef tourism; oil pollution from operational spills and discharge of dirty ballast water? And still more - will they themselves fall prey to global warming before they can be used for research to detect the impact of climate change on corals?

The risk of oil spills from ships passing the Strait of Hormuz, the world's busiest waterway, is high. Such spills have been witnessed in the past. In 1996, scientists found a new threat to UAE corals - Yellow Band Disease - a previously unknown plague that was consuming the corals in the southern Gulf off Abu Dhabi.

Coral Bleaching

The same year, bleaching of the southern Arabian Gulf corals occurred. Corals of Jebel Ali, Dubai, underwent mass mortality resulting in destruction of 19 sq km of dense coral because of a sea temperature anomaly. The system turned from an actively growing coral-dominated one to one mainly characterised by erosion. In 2002, bleaching happened again, mainly at the near shore site of Jebel Ali port, and the offshore island of Sir Abu Nuair. The bleaching started when sea surface temperatures reached up to 37 degrees near Dubai. All corals bleached white with only few individuals partially bleached or unbleached.

The Arabian Gulf is not the only marine environment so affected. Large scale coral bleaching and subsequent coral death have struck coral reefs across the tropics numerous times during the two past decades, with over 60 local or regional events recorded since 1980. In 1998, bleaching occurred on reefs round the world. In some regions mortality due to bleaching reached 70%. During this world-wide bleaching event, only minor damage was done to Dubai coral communities mainly because all species susceptible to bleaching were already dead since the 1996 mass mortality.

Corals bleach and lose their colour when the algae living within the tissues of the coral animal (called polyp) are expelled. The algae give corals their fantastically vibrant colours. A rise in temperature of just one or two degrees is sufficient for the polyp to expel its co-habiting algae.

Coral Bleaching Monitoring Protocol

To understand the true extent of coral bleaching and its long term impact on coral reefs, scientists from the WWF, the Great Barrier Reef Authority, and the World Fish Centre developed the Coral Bleaching Monitoring Protocol in order to cast further light upon coral bleaching and contribute to its prevention.

Under the new protocol, researchers will ideally collect data prior to a bleaching event, then follow up during and after the event. In this way, both the extent bleaching and, over time, the rate and extent of death or recovery can be assessed. A solid scientific foundation is also a requirement for good resource management. This protocol may, therefore, prove vital in convincing governments to set up marine protected areas (MPAs) and establish functional management schemes of human activities affecting coral reefs.

WWF and coral scientists are urging scientists across the world to put coral reef conservation and curbing climate change on top of the agenda.