Exploring cold water corals

The deep sea is one of the last remaining frontiers in human exploration. Hidden within the darkness are reefs known as cold water corals, home to crustaceans, molluscs, other invertebrates and fish that form the base of a food chain. As part of a European-funded research programme, British and Dutch coral experts are working together with their American colleagues to shed some light on the deep water corals throughout the Atlantic.

Data and samples are being collected from reefs throughout the Gulf of Mexico. The team also use a submersible to get close up to the sea animals and study their behaviour. For the European scientists it is a chance to study reefs on the other side of the Atlantic and to investigate the connection between cold water corals on both sides of the Atlantic. The source of this connection is the Gulf stream, which transports larvae of various species out of the Gulf, around Florida, off the coast of the Carolinas and then across to Europe. A particular species, called lophelia, is predominant on both sides of the Atlantic, although there are some differences.
The Dutch team have had a deep-water probe, called a lander, sitting on the sea-floor beside corals in the Gulf of Mexico. For the past year it has been collecting data regarding water temperature, salinity and current speed. The use of identical equipment in Europe means that comparisons can be easily made. The scientists are looking for daily, seasonal or even annual changes. It may also be possible to find evidence for climate events, such as Hurricane Katrina that hit the coastline not far from the lander site.

The coral colonies take thousands of years to build up and the growth of a coral is marked each year with a ring. The rings can then be chemically analysed to investigate ocean ecology, history and climate, stretching back thousands of years.

However, the location of these corals in the dark, watery underworld does not spare them from human influences. Deep sea trawling is a damaging factor and, like most ecosystems, they suffer from pollution. Enormous quantities of carbon dioxide released by humans are absorbed by the oceans. Because of the dynamics of the water, the carbon dioxide does not just stay on the ocean surface, it will eventually reach deeper waters. As the carbon dioxide dissolves, the water becomes acidic and the corals themselves begin to dissolve

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Science & Technology

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• mexico
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