Sir

Bell and Smith in their Brief Communication1 said that the azooxanthellate scleractinian Lophelia pertusa (L.) had been found on oil platforms in the North Sea. They also state that corals such as those on Brent Spar and those near the Beryl Alpha platform2 “have been exposed to agreed quality standards of operational discharges, such as oily water, drilling muds and chemicals, and contaminants that may leak from cuttings piles…”, suggesting that L. pertusa is thus not obviously affected by discharges from oil platforms.

But there is no definitive evidence that these corals have been exposed to any discharges, let alone a specific level of any “quality standard”. It is perfectly feasible that their position in the water column precludes such exposure. Current understanding of the environmental sensitivity of deep-water species such as L. pertusa is limited by the lack of information on their biology and ecology. Our understanding of coral distribution is incomplete3; we know nothing of the reproduction or dispersal of these organisms, or their sensitivity to suspended sediments, or the effect on them of exposure to drilling discharges.

Bell and Smith's conclusion — that by leaving the ‘footings’ of large platforms with jacket weights of more than 10,000 tonnes in place, existing colonies will be preserved and L. pertusa might spread in the North Sea — is naive.

In the long term, we do not understand the ecological implications of leaving such structures in place, let alone whether they will survive to form some form of artificial reef. It is known that L. pertusa can settle on to man-made structures. For example, early linear extension rate measurements (sensu growth rate as described by Bell and Smith) were estimated from the overall length of corals that had settled on undersea cables4.

But we are a long way from understanding how any such decommissioning strategy would affect the ecology of the North Sea. An open debate and more effort to understand the underlying science are needed before statements can be made on the environmental sensitivity of any species.