Marine animals | toxic noises

More and more studies show the deleterious effects of noise from human activities on fish and marine mammals. Quebec researchers are now looking into the impact of noise on marine invertebrates, including lobsters and mussels.

Whales stranded after hearing sonar

The first indications that noise harms marine animals came from passing military submarines. “We started to see, a few decades ago, strandings of whales shortly after military maneuvers and tests. Military sonars are very powerful,” explains Pierre Cauchy, marine acoustics specialist at the Rimouski Institute of Marine Sciences (ISMER). “It was confirmed twenty years ago. We have adapted the ways of doing things to protect the whales. »

Since then, studies have shown that fish and squid can also be affected. “We are talking about very strong noise sources, which make shock waves like explosions. The sound is so loud and close that animals are killed almost instantly. Mammals have eardrums much like ours. Not all fish organs have the same density. The swim bladder, for example, can burst. But we are talking about extreme cases. »

A marine noise impact reduction plan released in 2016 by the U.S. National Oceanic and Aeronautical Administration (NOAA) states that the degree of swelling of fish’s swim bladders influences their survival rate after these very high noises, which can exceed 200 decibels.

Difficulty communicating

In recent years, research has focused on other effects of underwater noise. “Are boat engines driving marine life away from certain places, or interfering with communication between animals? asks Mr. Cauchy. We know, for example, that species of whales that communicate with each other hundreds of kilometers away have a reduced capacity [à des dizaines de kilomètres] when there is a lot of boat noise. »

“Next summer, a community in Nunavut, Baker’s Lake, asked us to check whether the vessels that are more frequent because of a mining project have scared away certain types of fish, as reported by fishermen, indicates the specialist. marine acoustics. These studies are more difficult to do than those on extreme noise, because we are talking about marine productivity and reproduction rate, variables that are influenced by a host of factors. »

Solutions

Research into extreme noise has already led to improvements in marine practices, according to Cauchy. “For example, for underwater seismic explorations or the installation of pylons, we can start by emitting quieter noises in the hope that the mammals move away, and perhaps also the fish. For ships, we can obviously reduce the speed, but that can have economic impacts. The St. Lawrence Seaway, for example, is vital to North America. The beluga whale protection action plan, published in 2019 by Fisheries and Oceans Canada, proposes in particular to alter vessel schedules to protect certain times of the day and of the year.

More aggressive lobsters

At the University of Quebec at Rimouski (UQAR), biologist Réjean Tremblay has developed the “larvosonic”, a tank specially designed to test the impact of noise on larvae. “Mussel larvae float at the start of their life and feed on plankton,” says Mr. Tremblay. At some point, they attach themselves to the rocks. It seems that they rely on ambient noise to see if they are close enough to the coast and decide to settle. Ship noise can affect them. »

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. If vessels prevent dominant lobsters from hearing others, they may think they have competition and become aggressive in defending their place. The lobster’s hearing system is the fleece of hair on its legs, which remains to be confirmed.

Thanks to hydrophones installed in Saint-Pierre-et-Miquelon and Sept-Îles, Mr. Tremblay is completing an ambitious project to study the impact of noise on invertebrates with French colleagues. The animals studied will then be characterized at the University of Quebec in Montreal (UQAM), in the biology laboratory of Isabelle Marcotte.

“We want to assess the stress created by noise on a biochemical level,” says Ms.^me Marcotte. We focused on species that have economic value: mussels, oysters, lobsters, crabs. The mussel industry in Prince Edward Island, which is responsible for three-quarters of production in Canada, is very interested in our work. It could help direct the mussels to the aquaculture sites where we want them to settle. »

Congresses on marine noise have for some years included sessions on invertebrates. In Dublin in 2016, researchers showed that in the presence of noise, certain species of molluscs hide in the sand, which compromises their ability to feed and reproduce. Hermit crabs may 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 speaker said.

Loud construction of wind turbines

Another project by Mr. Tremblay, from UQAR, concerns the construction of wind turbines at sea. To break down the structures that support them, powerful sledgehammers are needed – which makes a lot of noise. Scallop larvae grow faster in the presence of this noise, but the effects of this early maturation are unclear – and it is unclear whether they are positive or negative. “We are currently carrying out experiments in the field to confirm the observations obtained in the laboratory and to demonstrate the consequences on the post-larvae and juveniles thereafter,” 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 characteristics associated with noise,” says Mr. Cauchy. Are electric motors the solution, or are changes to ship design or propellers? Atlas, another ISMER project, intends to create a 3D map of noise – ambient and of human origin – throughout the St. Lawrence River. “Mars and Altas together will allow us to really improve the situation for wildlife, taking into account economic realities,” says Cauchy. Mars, which includes four underwater hydrophones in addition to equipment on board ships, also involves UQAR’s Innovation maritime (IMAR) applied research center.