According to a new study, published in the journal Frontiers in Ecology and the Environment,, the deaths of thousands of Humboldt squid, which died off the coast of Oregon in 2004 and 2008 weren't cause by a shift in deep-sea currents as previously thought--underwater noise pollution literally blew holes in their heads.
Michel André of the Technical University of Catalonia in Barcelona, lead a team of biologists who found that subjecting squid to even short intervals of relatively low intensity, low frequency sound caused large holes to form in the squid's statocysts; the fluid-filled structures that enable the invertebrates to maintain their balance and position in water.
In a press release announcing the findings, André remarked, “If the relatively low intensity, short exposure used in our study can cause such severe acoustic trauma, then the impact of continuous, high intensity noise pollution in the oceans could be considerable.”
One likely source of such high intensity noise is the use of seismic air guns in mapping and prospecting the seabed. When similar deaths occured in 2001 and 2000 off Asturias, Spain, biologists there ruled out most other causes, eventually narrowing in on use of the air gun.
Many underwater species have sensitive hearing to take advantage of the way sound travels farther and faster in water than in air. Not only does noise pollution interfere with the ability of ocean species to hunt and escape predators; damage to the statocyst would injure a squid's balance and spatial orientation. "In other words," André concluded, "this would not be compatible with life.”
The discovery that noise pollution can kill squidraises further questions about the impact it has on other marine life.
"Is noise pollution capable of impacting the entire web of ocean life?" André wonders. " What other effects is noise having on marine life, beyond damage to auditory reception systems? And just how widespread and invasive is sound pollution in the marine environment?”
Dr. Marsha Green, founder of the non-profit Ocean Mammal Institute, which opposes seismic air guns, responded to the report by saying, "Scientists now agree that high intensity sound can deafen and kill marine mammals. We also know that noise from air guns used for oil and gas exploration reduce fish catch rates by 40-80 pecent. André's work is highly regarded and certainly indicates that even low level noise can affect squid. The big question is, 'Were seismic exploration with air guns, military sonar or other noise activities occuring in the area in 2004 and 2008 when the squid stranded?'"
Comments