With the conditions under which coral reefs have flourished in the past half-million years dramatically changing, their ability to survive in a globally warming world may crucially depend on the levels of pollution to which they are exposed, the United Nations environmental agency warned today.
At the same time, the UN Environment Programme (UNEP) reported that the number of ‘dead zones’ or low oxygenated areas in the world’s seas and oceans due to pollution may now be as high as 200 and are fast becoming major threats to fish stocks and oysters, and thus to people who depend upon fisheries for food and livelihoods.
The latest findings from two separate reports were released at an inter-governmental review congress in Beijing where 700 delegates from some 115 countries are seeking to chart a new course for the Global Programme of Action (GPA) for the Protection of the Marine Environment from Land-Based Sources, a voluntary UNEP initiative.
“There are numerous compelling reasons for combating pollution to the marine environment,” UNEP Executive Director Achim Steiner said. “These range from public health concerns to the economic damage such pollution can cause to tourism and fisheries.
“Climate change, and the need to build resilience into habitats and ecosystems so that they can cope with the anticipated increase in temperatures likely to come, now represents a further urgent reason to act,” he added of the report on coral reefs – Our Precious Coasts: Marine Pollution, Climate Change and Resilience of Coastal Ecosystems.
The study is based on surveys carried out between 2004 and 2006 following damage caused to reefs world-wide in 1997-1998 when surface sea temperatures reached up to 34 degrees Celsius.
Corals in an estimated 16 per cent of the world’s coral reefs suffered up to 90 per cent mortality as a result of mass bleaching, with reefs across the Indian Ocean, including around the Comoros, La Reunion, Madagascar, Mauritius and Seychelles, among those severely damaged.
But soft coral cover and stony coral increased rapidly in areas least affected by coastal development. “If we fail to protect the coastlines from unchecked piecemeal development, or protect the water sheds from deforestation, huge amounts of sewage and sediment loads will reduce the ability of reefs to recover dramatically,” UNEP Rapid Response Team researcher Christian Nellemann said.
“Once they are overgrown, it is difficult for them to recover, and over time they change or even die entirely.”
The findings on the ‘dead zones’ – where algal blooms triggered by nutrients from sources such as fertilizer run-off, sewage, animal wastes and atmospheric deposition from the burning of fossil fuels can remove oxygen from the water – show that the number and size of deoxygenated areas are on the rise, with the total climbing every decade since the 1970s.
Some of the earliest recorded dead zones were in places like Chesapeake Bay in the United States, the Baltic, Black and northern Adriatic seas and the Scandinavian fjords, but others have been appearing off South America, China, Japan, south east Australia and New Zealand. The best known area is in the Gulf of Mexico, directly linked to nutrients or fertilizers carried down by the Mississippi River.