Posted at 12:00 p.m
Whales strand after hearing sonar
The first indications that noise harms marine life came from passing military submarines. “A few decades ago, we started stranding whales shortly after military maneuvers and tests. Military sonars are very powerful,” explains Pierre Cauchy, specialist in marine acoustics at the Rimouski Institute of Marine Sciences (ISMER). “It was confirmed twenty years ago. We have adjusted the procedures to protect the whales. »
PHOTO FROM NOAA WEBSITE
Cuvier’s whale stranded underwater in Guam after military maneuvers
Since then, studies have shown that fish and squid can also be affected. “We are talking about very strong noise sources that create shock waves like explosions. The sound is so loud and close that animals are killed almost instantly. Mammals have eardrums similar to ours. Not all fish organs have the same density. For example, the swim bladder may burst. But we are talking about extreme cases here. »
A plan to reduce the impact of ocean noise released in 2016 by the US National Oceanic and Aeronautical Administration (NOAA) states that the degree of swelling of fish’s swim bladders affects their survival rate after these very high levels of noise, which can exceed 200 decibels.
communication difficulties
In recent years, research has focused on other effects of underwater noise. “Do boat engines drive marine life away from certain locations or disrupt communication between animals? asks Mr. Cauchy. For example, we know that cetacean species that communicate hundreds of miles away have reduced capacity [à des dizaines de kilomètres] when there is a lot of boat noise. »
“The next summer, a community in Nunavut, Baker’s Lake, asked us to check whether vessels increasing their traffic due to a mining project scared off certain species of fish, as reported by fishermen, says the marine acoustics specialist. These studies are more difficult to conduct than those on extreme noise because we are talking about ocean productivity and reproduction rates, variables that are affected by a multitude of factors. »
solutions
According to Cauchy, research into extreme noise has already led to improvements in marine practice. “For example, with underwater seismic surveys or pylon installation, we can start emitting quieter sounds in the hope that the mammals and maybe the fish will move away. Of course, we can reduce the speed of ships, but that can have economic consequences. The St. Lawrence Seaway, for example, is vital to North America. Specifically, the Beluga Whale Conservation Action Plan released by Fisheries and Oceans Canada in 2019 proposes changing ship schedules to protect certain times of the day and season.
More aggressive lobsters
At the University of Quebec at Rimouski (UQAR), biologist Réjean Tremblay has developed the “larvosonic”, a tank specifically designed to test the effects of noise on larvae. “Clam larvae hover early in life and feed on plankton,” says Mr. Tremblay. Eventually they attach themselves to the rocks. It appears that they rely on ambient noise to see if they are close enough to shore to settle down. Ship noise can affect them. »
PHOTO SUPPLIED BY RÉJEAN TREMBLAY
Mussel larvae on the ropes that form the substrate of the ISMER larvoscope
PHOTO SUPPLIED BY RÉJEAN TREMBLAY
The ISMER larvoscope
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Other studies have shown that noise makes lobsters more aggressive. “The dominant lobsters make noise and the others have to reproduce the noise to show their submission,” says Mr. Tremblay. When ships prevent dominant lobsters from hearing others, they may think they have competition and become aggressive when defending their spot. The lobster’s auditory system is the fleece of hair on its legs, which has yet to be confirmed.
Thanks to the hydrophones installed in Saint-Pierre-et-Miquelon and Sept-Îles, Mr Tremblay completes an ambitious project to study the effects of noise on invertebrates with French colleagues. The animals studied are then characterized at the University of Quebec in Montreal (UQAM) in Isabelle Marcotte’s biology laboratory.
PHOTO FROM UQAR WEBSITE
A hydrophone installed in Saint-Pierre-et-Miquelon
“We want to assess the stress caused by noise at the biochemical level,” says Ms. Marcotte. We have focused on species with economic value: mussels, oysters, lobsters, crabs. The mussel industry on Prince Edward Island, which accounts for three quarters of production in Canada, is very interested in our work. It could help direct the mussels to the aquaculture sites where they are supposed to settle. »
Congresses on marine noise have included sessions on invertebrates for a number of years. In 2016, researchers in Dublin showed that certain species of mollusks hide in the sand in the presence of noise, affecting their ability to feed and reproduce. Hermit crabs might think a boat noise means their shell is damaged, causing them to climb out to examine it, an action that leaves them vulnerable to predators, a spokesman said.
Loud construction of wind turbines
PHOTO PHIL NOBLE, Portal ARCHIVE
The construction of wind turbines at sea causes a lot of noise.
Another project by UQAR’s Mr Tremblay involves the construction of offshore wind turbines. It takes powerful sledgehammers to tear down the structures that support them – which makes a lot of noise. Scallop larvae grow faster in the presence of this noise, but the implications of this early maturation are unclear — and it’s unclear if they’re positive or negative. “We are currently conducting experiments in the field to confirm the observations obtained in the laboratory and to demonstrate the consequences for the afterlarvae and young animals afterwards,” says Mr. Tremblay.
Atlas and Mars
Mr. Cauchy leads Mars (Marine Acoustic Research Station), a project to characterize the noise of individual ships. “We want to understand the properties associated with noise,” says Mr. Cauchy. Are electric motors the solution, or is it a change in ship design or propellers? Atlas, another ISMER project, intends to create a 3D map of noise – environmental noise and human origin – throughout the Saint Lawrence River. “Mars and Altas together will allow us to really improve the situation for wildlife while considering economic realities,” says Cauchy. Mars, which includes four underwater hydrophones in addition to shipboard equipment, also includes UQAR’s Applied Research Center Innovation Maritime (IMAR).
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22-fold increase in noise emitted by lobsters in the presence of ship noise
SOURCE: NAVY Pollution Bulletin