Scientists measure their reaction when exposed to oil and natural gas in the water

French researchers hoping to get an early warning on pollution in the ocean have found an unlikely ally in a mollusc more often destined for the dinner table. Their findings reveal that much like canaries in a coal mine, oysters stationed near offshore oil platforms can detect minute amounts of hydrocarbons as each one constantly filters dozens of gallons of water every day.

That could alert scientists to tiny infrastructure cracks before they become catastrophic oil spills that threaten wildlife and coastal communities. Attached to rocks or other supports, oysters are ideal for nearly real-time analysis because "they have nothing to do except notice the surrounding noises and temperature and light variations," said Jean-Charles Massabuau, a researcher at France's CNRS scientific institute. The bivalve "is perfectly made for sampling the quality of the water it filters all day long" as it reacts almost instantly to the slightest amount of oil, Massabuau said.

To study the reactions, he and his team have come up with an electrically isolated aquarium using concrete and plastic foam blocks, old bicycle tube tires and tennis balls at the world's second-oldest marine research station, on the Bay of Arcachon in southwest France.

Electrodes are attached to about a dozen oysters in the tank, allowing researchers to measure how quickly each oyster's valves are opening and closing to filter the water for food. Spikes in valve cycles are the first alert that the mollusc has become stressed, with larger increases corresponding to higher hydrocarbon concentrations.

The observations have been tested in areas including the Barents Sea off Norway and Russia, as well as canals built for a research facility operated by the French energy giant Total outside Pau in southwest France.


Source: September 18, 2018, The Hindu