[ad_1]
Ocean sound transmission is being sped up due to global warming induced by climate change – threatening marine species as sounds travel faster and become louder
The ocean soundscape is a symphony of vibrations created by living organisms, natural phenomena, such as waves and cracking Ice, ship traffic, and resource extraction. However, this speed is increasing. Ocean sound transmission could be a danger to marine life in acoustic hotspots.
At 50m depth, ocean sound transmission speed can vary from 1,450 metres per sec in the polar regions to 1,520 meters per second in equatorial water (3,243 to 3,400 mph, respectively).
Already affecting the oceans in a profound way Ocean warming has caused ecosystem damageClimate change, food security, and carbon sinks. Climate change will also have a significant impact on how sound travels under water, potentially affecting both natural soundscapes and accentuating human-generated sound.
Warm water allows sound waves to propagate faster and last longer than in cold water.
Many animals use sound to communicate with one another and navigate their underwater world. However, increasing ocean sound transmission speeds can affect their ability to communicate. Feed, fight, find mates and avoid predators..
Published in Earth’s FutureResearchers investigate the first global-scale estimation of ocean sound speed in relation to future climate model predictions. They also analyse the changes to ocean soundscapes that could affect essential marine life activities.
Future sound speed increases are expected by researchers as ocean sound transmission is likely to increase with warmer sea temperatures – especially in two particular ‘acoustic hotspots’ of future sound speed increases, predicted in the east of Greenland and in the Northwest Atlantic Ocean, East of Newfoundland.
Researchers predict that the average speed at which sound travels in these areas will increase by more than 1.5%.Through 2100, temperatures are expected to continue to rise due to climate change.
By the end of the century, the average speed of sound is predicted to increase by over 1.5% – approximately 25 metres per second (55 miles per hour) – in these waters from the surface to depths of 500 metres (1,640 feet), given continued high greenhouse gas emissions (RCP8.5).
The two aforementioned hotspots – in the Greenland Sea and a patch of the northwestern Atlantic Ocean east of Newfoundland – is predicted for most change at 50 and 500 metre depths.
Author Stefano Salon, a researcher at the National Institute of Oceanography and Applied Geophysics, said: “The major impact is expected in the Arctic, where we know already there is amplification of the effects of climate change now.
“Not all the Arctic, but one specific part where all factors play together to give a signal that, according to the model predictions, overcomes the uncertainty of the model itself.”
Alice Affatati, a bioacoustics researcher, and lead author of the new study, said: “We calculated the effects of temperature, depth and salinity based on public data to model the soundscape of the future,”
Identifying future ocean “acoustic hotspots”
Temperature, pressure with increasing depth, and salinity all have an impact on how fast and far sound travels in water. Researchers analysed hotspots in which the climate signal was distinct from the model uncertainty. These hotspots were larger than seasonal variability.
Other than the outstanding hotpots around Greenland and in the northwestern Atlantic Ocean, the study also discovered a 1% sound speed increase – which is more than 15 metres per second, at 50m in the Barents Sea, northwestern Pacific, and in the Southern Ocean (between 0 and 70E), and at 500 m in the Arctic Ocean, Gulf of Mexico, and southern Caribbean Sea.
Modelling common vocalizations under the projected future conditions of the North Atlantic right whale – which is a critically endangered species inhabiting both north Atlantic acoustic hotspots – the researchers note that the whales’ typical “upcall” at 50 Hertz isAlso, it is likely to spread further in a warmer ocean in the future..
Affatati added: “We chose to talk about one megafauna species, but many trophic levels in the ocean are affected by the soundscape or use sound. All these hotspots are locations of great biodiversity.”
Author Chiara Scaini, an environmental engineer at the National Institute of Oceanography and Applied Geophysics, said: “With complicated problems like climate change, to combine different approaches is the way to go.”
The researchers stated that future work will combine the global soundsscape with other maps of human impacts in the oceans to pinpoint areas prone to stressors.
