Dr Murray Roberts: Chilling threat being posed to our deep-sea wonders

Cold-water corals provide a rich habitat for other forms of marine life, and archive thousands of years' worth of information on climate change, but they're under threat from fishing, mining and, ironically, climate change itself.

Think of corals and what springs to mind? Island paradises in clear blue waters? Palm trees, sandy beaches and luxurious holidays in the Caribbean? All true, but corals aren't only found in the tropics. In fact, there are more coral species in deep, cold-water waters than on shallow, tropical reefs. And it's these cold-water corals in the North Atlantic that my research team at Heriot-Watt University studies. It's fascinating and frustrating work. With almost every survey comes evidence that human activities have damaged deep-sea habitats and the spectres of global warming and ocean acidification may completely alter the present balance of ocean ecosystems, with huge implications for marine life and the people it supports.

So where do corals fit into the scheme of things? Corals are important because over millennia they accumulate, forming reefs. In turn reefs are home to thousands of other species. There are more vertebrates - in the form of fish - on tropical coral reefs than anywhere else on Earth. On deep-sea coral reefs it's the animals without backbones that dominate, with more than 1300 species logged in the North Atlantic so far. Cataloguing and understanding this biodiversity is one of our greatest challenges, but also one of the most rewarding parts of the work. Biodiversity is valuable in its own right, but marine life has also evolved a complex chemical ecology including compounds with potent anti-cancer properties. Scientists have barely begun to explore this storehouse of potential new drugs.

Corals also continue to surprise us. Two years ago a team at Texas A&M University discovered that a live individual cold-water coral growing on a Hawaiian seamount was over 4000 years old, making it the oldest known living animal on Earth. In 2003 my team discovered a whole complex of deep-water coral reefs near the Hebridean Island of Mingulay and Melanie Douarin at the University of Edinburgh has carefully dated coral skeletons from the base of these reefs to show that they are at least 5000 years old. In deeper offshore waters giant coral carbonate mounds were first discovered in the early 1990s. When they were explored layers of cold-water coral reefs were discovered going back more than two million years.

The fossil coral skeletons in these reefs lock away an archive of the environment they grew in, and deep-sea corals are one of most exciting archives of past ocean climate. But just as we're beginning to understand these species-rich archives we're also learning how vulnerable and threatened cold-water corals really are.

Deep-water trawling rapidly reduces thousands of years of growth to rubble. Discoveries of trawl damage on the High Seas beyond national jurisdiction has prompted the UN to call upon states to conserve all vulnerable marine ecosystems, including cold-water corals. As the global demand for metals increases mining companies are looking to mineral-rich deposits in the deep sea. For years the stuff of science fiction, advances in underwater technology make deep-sea mining a technical reality and it remains to be seen whether the presence of vulnerable marine ecosystems tempers industrialisation of deep-sea deposits.

Perhaps the most insidious threat to cold-water corals, however, comes from our addiction to fossil fuels. Approximately a third of the carbon dioxide released by burning fossil fuels since the industrial revolution has dissolved in the oceans. Without this, global warming would be more severe. But the payback is ocean acidification. Carbon dioxide dissolved in water produces carbonic acid, and it's this process that is gradually acidifying the oceans. Any marine life that produces limestone skeletons - including corals, molluscs and plankton - faces an uncertain future in an increasingly acidic ocean.

At Heriot-Watt we are tackling these issues through the university's environment and climate change theme and with a recently awarded research grant from the UK Ocean Acidification Research Programme. Work began last year as we developed new laboratory systems to mimic predicted future levels of acidification. This summer we head off to the Mingulay reefs to begin our studies in earnest, with another expedition planned to Rockall Bank in 2012. But corals grow slowly - it will take us the best part of three years to complete our experiments.

Dr Murray Roberts is director of the Centre for Marine Biodiversity & Biotechnology at Heriot-Watt University

Website raises awareness

HERIOT-Watt's Cold-water Coral Research Group recently launched www.lophelia.org, a website devoted to all aspects of cold-water corals.

The website features a five-minute film where Sir David Attenborough, right, introduces cold-water corals, explains the threats they face and what we can do. The website is full of information and other features, from downloadable screensavers to a Kid's Zone.