A widely used method to find oil and gas for offshore drilling can kill tiny sea creatures that are key for feeding many marine animals like shellfish, fish, and even whales. And the impacts on these tiny, drifting creatures — called zooplankton — are seen in an area much larger than previously thought.
The study, published in the journal Nature Ecology and Evolution, adds to the body of evidence that the loud noises produced during oil and gas exploration can disrupt marine life — including whales that use sound to communicate and look for food. It also comes just a few months after President Donald Trump has signed an executive order looking to expand offshore gas and oil drilling in the Atlantic and Arctic oceans.
Oil and gas companies looking for offshore natural resources use seismic airguns to blast compressed air through the water and into the seafloor. The noise produced by these airguns is louder than a Saturn V rocket during launch, according to Nature. So researchers wanted to see what the effects are on the sea’s base of the food chain, the zooplankton.
The researchers blasted airguns in the ocean off southern Tasmania, and checked zooplankton populations before and after by using sonar and nets. The abundance of these tiny creatures dropped by 64 percent within one hour of the blast, the study says. Two to three times as many zooplankton were also found dead — and the impacts were recorded as far away as 0.7 miles. Scientists previously estimated that impacts would occur only within 33 feet from the blast.
It’s not 100 percent clear how the airguns are causing the die-offs, but it’s possible the blast throws off the receptors the animals use to navigate, disorienting them and causing them to die, according to Nature. Because zooplankton is key for feeding larger marine animals, the die-offs could have serious cascading effects.
“Plankton underpin whole ocean productivity,” lead author Robert McCauley, an associate professor at Curtin University in Australia, said in a statement. “Their presence impacts right across the health of the ecosystem so it’s important we pay attention to their future.”