Scientists warned on Tuesday that controversial seabed mining could pose a major threat to ocean ecosystems, particularly blue whales and other cetaceans already under stress from shipping, pollution and climate change.
A study in the journal Frontiers in Marine Science found that commercial-scale extraction of valuable minerals from the ocean floor, which could begin later this year, would damage habitats and disrupt the way cetaceans communicate.
Earlier research has detailed the likely devastating impact of deep-sea mining on the ocean floor. New analysis by the University of Exeter and Greenpeace Research Laboratories shifts the spotlight to marine megafauna and noise pollution.
“Cetaceans rely on sound for all aspects of their behaviour, such as hunting, breeding and navigation,” Kirsten Thompson, lead author of the study and a lecturer in marine mammal biology at the University of Exeter, told AFP.
“That’s why noise pollution from deep-sea mining is a particular concern.”
The report shows an overlap between the frequencies that cetaceans communicate with and the sound generated by drilling, dredging and the acoustic telemetry needed to remotely operate seabed mining vehicles.
This phenomenon, known as “auditory masking”, has previously been shown to disrupt marine mammal communication and alter their behaviour.
Underwater noise generated by industrial or military operations can bring hunting whales to the surface faster than normal, increasing the risk of gas bubbles forming in the bloodstream, which can lead to suffocation and death .
Other research found that human-made noise increased the risk of separation between humpback whales and their calves, which communicate through silent vocalizations.
– ‘Two-year rule’ –
The new findings come with some caveats.
Because seabed mining has yet to be authorized anywhere in the oceans, Thompson and her team had no real-world data to draw on.
So they used proxies from other industries to estimate the noise expected from industrial seabed mining operations.
Thompson also pointed to knowledge gaps in the distribution of marine mammal species, mainly due to the high cost of biological surveys across vast oceans.
Deep-sea mining is predicted to have a particularly severe impact on cetaceans in the Pacific’s Clarion-Clipperton Zone, home to about two dozen cetacean species, including baleen whales, beaked whales, sperm whales and Risso’s dolphins .
The region is poised to become home to the world’s largest nodule extraction of manganese, a mineral vital in electric car batteries.
The small island nation of Nauru, in particular, sees deep-sea mining as a potentially profitable revenue stream for climate adaptation in the face of rising sea levels and increasingly powerful storms.
In June 2021, the government of Nauru implemented a rule requiring the International Seabed Authority (ISA) – the UN body that regulates deep-sea exploration and exploitation in areas outside national jurisdiction – regulations on offshore mining around the world to be completed within two years.
According to the so-called “two-year rule”, mining could go ahead in July of this year with whatever regulations the ISA has devised by then.
“Given the immediate threat posed by the two-year rule to ocean conservation, we suggest there is no time to waste,” Thompson said.