An increasing number of oil and gas installations are being built on the seafloor, many in isolated and inaccessible spots. But it's a challenge to detect the start of a leak at these kinds of installations before the leak snowballs into a catastrophe like the BP's Deepwater Horizon, with its 11 deaths in the Gulf of Mexico in 2010.
For some situations - although not as deep as the Deepwater Horizon - mussels may be as good an environmental watchdog as more conventional sensors, according to Eirik Sønneland, CEO of a Norwegian company called Biota Guard, which is developing the technology.
“Mussels are up to a thousand times as sensitive to hydrocarbons in the water as the best industrial sensors,” Sønneland is quoted as saying on the Norwegian Broadcasting Corporation’s website NRK.no.
Biota Guard is based in the city of Stavanger, and has specialised in developing the use of mussels as biosensors that can be paired with their man-made equivalents in pollution warning systems.
Individual mussels filter as much as 100 litres of water daily, which makes them particularly good at detecting changes in water quality. Just as our pulse rates rise when we get uncomfortable and stressed, the heartbeats of mussels increase when something is amiss in their environment.
Scientists have found that using sensors to monitor the heart rates of these bivalves allows them to detect and transmit early warnings about environmental changes.
Mussels react to all sorts of environmental factors, including changes in salinity, chemicals, temperature, and noise - all of which provide good indicators of the general health of the ocean at a given spot.
Norway’s Climate and Pollution Agency (Klif) is intrigued by the possible use of mussels in an early warning system.
“Any possible system that can provide an early warning of leaks is good, and Klif is intensifying its focus on this as more and more subsurface oil and gas facilities are deployed on the Norwegian Continental Shelf,” says Chief Engineer Ann Mari Vik Green, from the agency’s Section for the Oil and Gas Industry.
She points out, however, that the sensitivity of mussels can also pose a challenge.
“Mussels are so sensitive to so many changes that it can be hard to figure out what they are reacting to, but they do warn us that something or another is wrong,” says Green.
Eirik Sønneland explains that his company’s system also relies on sensors and water samples in conjunction with the mussels.
“We use a combination of sensors, aimed at signalling whether the abnormal behaviour we detect in the biosensors can be traced to a pollutant discharge or simply to natural variations,” he says.
Biota Guard sees a bright future for the use of mussels and other biological warning indicators. The idea can also be adapted to other areas across the globe by using local bivalves other than mussels, such as oysters.
The company also thinks freshwater mussels could be used to monitor conditions in Norwegian watersheds.