| Seals are known to be attracted by the sea around windfarms; researchers found that tagged individuals in the North Sea traced out ‘a striking grid pattern’ in their daily movements, swimming directly from one wind turbine to the next – hunting for fish. As with other physical structures in the sea, from mangrove roots to coral reefs, wind farms appear to afford fish at least some shelter from predators – and from modern industrial fishing boats. More complex structures such as sunken ships attract both fish and large crustaceans such as lobsters and crabs. In Scotland fishing communities have successfully dropped scrap vehicles onto featureless sandy areas of sea floor to attract these creatures and effectively increase local marine biodiversity as well as their catch. The underwater section of wind- turbine towers can suffer scouring from currents, and they also attract colonisation by the larvae of corals and other sedentary marine organisms. Some green energy companies are starting to think laterally; could their turbines be protected by underwater structures that at the same time enhance marine biodiversity from corals to fish.In tropical waters the future of coral reefs is matter of urgent concern as bleaching events become more common, and dead reefs become prone to wave damage and collapse. In other places shores without the protection of offshore coral reefs are eroding as sea level rises. Could artificial reefs help? Dr Will Bateman of CCell Technologies in north London certainly thinks so. He has devised a method of producing new reefs very much more quickly than occurs in nature. By passing a small electric charge (produced from wave action or a solar panel) through a grid of steel arches he has found that electrolysis causes artificial limestone to build up on the structure, which acts as a reef, breaking the energy of waves thus protecting the shore. There are several incidental benefits to biodiversity.The artificial shallow lagoon can potentially become a seagrass zone, and the structure itself attracts new coral colonies to form – a process which can be accelerated by seeding with young coral. The first ‘digital reef’ off the coast of Yucatan, Mexico, is controlled via the internet from the CCell offices in London, with the performance of each few metres monitored continually so the technique can be perfected. In two years, it has already accreted around two centimetres of limestone, demonstrating a far cheaper and more environmentally sensitive method of creating a new reef structure than the present alternative – dropping large concrete blocks offshore. A further development of the technique could be to mimic lost mangroves by constructing digital versions of the complex mangrove-root habitats that are vital fish breeding grounds.CCell’s technique could potentially add value to windfarms by creating durable underwater structures around their turbine towers. Danish windfarm giant Orsted has even started to plan for ‘rewilding’ the North Sea; they see the possibility of artificial reefs protecting their towers also encouraging new fish spawning grounds safe from illegal fishing. It chimes with the current move towards rewilding; only this week the Marine Conservation Society has announced the designation of four big new Marine Protected Areas in British Waters. With far better protection than previous such zones (such as banning of bottom-trawling), it is hoped that these will contribute to major improvements in the entire marine ecosystem – and restoring commercial fish stocks. |
PLANETARY HEALTH WEEKLY 