DEEP-sea oil rigs are havens for wildlife, according to a survey of porpoises visiting a rig in the North Sea. If confirmed, the findings may prompt a rethink of current regulations governing the fate of platforms in the north-east Atlantic and Europe.
Previously, researchers had shown that coral, plankton and fish thrive on and around ocean platforms like oil rigs, largely because they provide shelter from the open sea and are no-go zones for fishing boats. Now it looks as though they may also support cetaceans.
of Ocean Science Consulting, a UK-based consultancy in Dunbar, East Lothian, and her colleagues placed microphones designed to record the patterns of porpoise clicks around an oil rig near the Dogger Bank in the North Sea to listen for harbour porpoises, a threatened species. Over 525 days, they recorded 2479 harbour porpoise visits, almost all of which happened at night. The pattern of clicking matched that of porpoises hunting for fish, suggesting that they were travelling to the rig to feed (ICES Journal of Marine Science, ). 鈥淣o one has done research like this before,鈥� Todd says.
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鈥淭he nightly pattern of clicking recorded at the oil rig matched that of porpoises hunting for fish鈥�
Because the work was funded by the German chemical company BASF, which harvests oil and gas from the rig, Todd acknowledges that she could be accused of industry bias and a conflict of interest. But she is adamant that the results are bona fide, and receives support from other researchers.
鈥淚 do not believe that the potential conflict of interest has affected the results or their interpretation,鈥� says Andrew Guerin of the National Oceanography Centre in Southampton, UK, who studies the interaction of marine life with rigs.
However, Guerin does stress that there are still plenty of unanswered questions. The information collected does not reveal how many porpoises visited, where they disappeared to during the day, or their abundance in neighbouring areas of the ocean. Todd says that to advance the study she plans to drop microphones in nearby open sea as a control, and deploy cameras around the rig to combine click data with footage of feeding activity.
Her findings add to mounting evidence that rigs are wildlife havens. 鈥淚t鈥檚 fascinating, and consistent with trends we鈥檙e observing here,鈥� says Paul Sammarco of the Louisiana Universities Marine Consortium in Chauvin, who has seen coral and fish colonising rigs in the Gulf of Mexico. In the US, federal laws are being amended to allow decommissioned rigs to remain where they are, Sammarco says.
In Europe, rig disposal became a big issue in 1995 when Greenpeace campaigned against plans by the oil giant, Shell, to sink a rig called Brent Spar, famously comparing the feat to 鈥渢hrowing a beer can in the sea鈥�. Strict new laws followed in 1998 as part of the OSPAR convention, forbidding owners from either leaving decommissioned rigs where they are or sinking them.
The says that rules cannot be changed unless all 15 signatory nations agree. But in the next few months the commission is planning to publish a new assessment of the environmental impact of offshore activities, including the value of artificial reefs.
