A Spanish led team of scientists has confirmed that noises from human activity in the oceans are killing marine wildlife and affecting their survival outlook, after assessing over 10,000 scientific reports.
They also captured audio from oceans in different parts of the world showing just how much racket humans are making below sea level. The study shows that these noises, as well as affecting animals’ sense of direction, is also impacting their ability to hear where their homes are and when eggs are being laid.
This in turn impacts their ability to breed and is affecting the population numbers and in some cases the stress caused by noise is outright killing them. And the solutions would be relatively easy and economical to implement.
Most marine animals use their auditory abilities to communicate with each other, to breed, to feed and even to find their home after being dragged off course by ocean currents.
But most of them are struggling to do this due to noise caused by human activity that is now reaching every corner of the planet, due to marine transportation, building in the sea and near coasts, and due to fracking, as well as dynamite fishing, underwater drilling for gas and oil, and even wind farms.
The research, led by Professor Carlos M. Duarte, a renowned marine ecologist at King Abdullah University of Science and Technology (KAUST) in Saudi Arabia, has recently been published in the journal Science. It confirms the impacts of man-made noise on the marine ecosystem.
The researchers dug into 10,000 scientific reports to analyse the impact on the marine system over the last 40 years and have recorded audio in different parts of the world to show the din that can now be heard beneath the waves.
Professor Duarte highlighted the impact of the noise on ocean life, not only among bigger animals but also among invertebrates. The research also conducted a detailed analysis of how human activity has modified the sounds of the ocean, introducing higher noise volumes, silencing the natural sounds of the ocean by decimating the marine animal populations that create them, and eroding their ecosystems.
The expert said: “We have also evaluated the impacts of human noises on the different components of marine life, such as their behaviour, feeding, metabolism, breeding, which are functions that determine the health status of the animals.”
Noise caused by human activity is also causing, as the professor explained, “mortality in extreme cases, linked with the stress suffered by the animals due to this noise.”
The professor explained that a lot of animals are leaving their natural habitats near the coasts, which have more food, but are also noisier. Abandoning plentiful food sources and in many cases leading to a population drop.
He added: “There are marine animals with very poor body-mass indexes, they are starving and they are suffering, their habitat has been reduced because some of the places are too noisy to live there.”
Another consequence of the noise in marine animals is, according to the professor, that they are losing their ability to hear and detect predators. He said: “A lot of fish do not manage to learn the noises that their natural predators make in order to generate a defence reaction.”
But the noise is also affecting stress levels and animals’ metabolisms, which in turn affects breeding patterns. He explained that a “lot of fish spread their sperm into the water and they coordinate the breeding event through noise. If they cannot listen to each other, the breeding cannot be coordinated and it is failing, so there is a huge impact on the breeding system.”
The professor also explained that after breeding, some young fish are dragged over 200 kilometres (120 miles) away by currents.
He said: “Some of them are dying because they cannot find their way back home because the destruction of their habitat has silenced the signal emitted by those habitats or even because there is a lot of human noise, like a sound fog, affecting them and impeding their ability to hear the signal”.
Professor Duarte explained that for example, a barrier reef or an underwater forest, for example, typically emits its own signal that can then be identified by marine animals that would call these locations home.
He said that last year, the typical sound coming from a marine forest had been recorded. He said: “It is like tinkling bells caused by bubbles originating in the forest during the day that goes up to the surface and when they explode because they are very big, they generate this tinkling. It is a clear indication that the underwater forest is correctly carrying out photosynthesis.”
The ocean is therefore like a giant orchestra, with musicians and singers. According to Professor Duarte, one of the most famous singers is the beluga whale, which is one of the species that is the most affected by noise stemming from human activity.
This orchestra of animal sounds and the noise caused by human activity has been compiled in a recording by Jana Winderen, who also participated in the research.
Professor Duarte explained that “noise is fundamental for these animals, they are very shy and the fact that the Arctic is being opened up to maritime transport due to the melting ice caps means they can end up being isolated in open ice areas and they are not going back to their habitats because it is too noisy there.
“When the winter arrives, that open ice area is covered again by the ice and they cannot find a place to breathe on the surface”.
These days, there are no longer any locations on the planet without man-made noise, including the Arctic and Antarctica, although according to Professor Duarte, at some rare moments of the year, Antarctica can have its original soundtrack back because marine transport, fishing and industrial activities are very controlled there.
Duarte and his team blame maritime transport for the most important noises in the ocean, as the noises linked to it occur all over the planet, 24 hours a day, 7 days a week. Other culprits include industrial activity, fracking and building along coastlines.
The research includes some of the measures that can help avoid noise in the ocean, which could be easily put in place and trigger very rapid improvements, according to Professor Duarte. He explained that regarding maritime transport, it is important to identify the noisiest vessels so that they can change their propellers for better designed ones that do not generate so much noise.
He said: “Not only will the noise decrease but we will also see how the use of fuel decreases, generating additional economic benefits for the companies that own the boats.”
Regarding how industrial and building activites along the the coasts could be controlled, he said that there are acoustic barriers, “bubble ones”, that act like curtains that mitigate the noise going into the sea.