The impact that the coronavirus lockdown has had on the natural world has been considerable. The air quality around major cities has improved, animals have been seen strolling in cities, and the grinding push of industry has brrn quieted for the first time in the generation. But it has also affected the oceans of the world.
For the first time in a long time, the ocean has fallen silent.
Researchers examining real-time underwater sound signals from seabed observatories run by Ocean Networks Canada near the ports around Vancouver found a significant drop in low-frequency sound associated with ships. The deep ocean site, around 60km from the shipping lanes and in 3,000 metres of water, also showed a drop in average weekly noise of 1.5 decibels, or around a 15% decrease in power.
“We are facing a moment of truth,” said Michelle Fournet, a marine acoustician at Cornell University, who studies humpback whales in south-east Alaska. “We have an opportunity to listen – and that opportunity to listen will not appear again in our lifetime.”
“We have a generation of humpbacks that have never known a quiet ocean,” said Fournet, whose work has shown that the whales have altered their calling behaviour in response to a noisy ocean.
The seas around Vancouver is usually very busy around late April as cruise ships arrive and depart. This year, the cruise ships are silent due to the viral outbreak.
Nathan Merchant, a bioacoustics expert at the UK government’s Centre for Environment, Fisheries and Aquaculture Science (Cefas) in Lowestoft, said: “We are on tenterhooks waiting to see what our records are saying.”
“What we know about whales in south-east Alaska is that when it gets noisy they call less, and when boats go by they call less,” said Fournet. “I expect what we might see is an opportunity for whales to have more conversation and to have more complex conversation.”
“We have this natural experiment going on. Of course it is a terrible crisis, but we may as well get on and look at the data, to find out what effect it is having.”