Noise emanating from passing ships may disturb animals such as killer whales and dolphins far more than previously thought, with new research showing that the animals’ communication and ability to find prey could be hampered by the underwater din. These noise disturbances occurring at medium and higher frequencie -- including at 20,000Hz where killer whales, also known as orcas, hear bes -- could be hindering the ability of killer whales to communicate and echolocate – the process of using sound to bounce off objects such as prey and identify where they are. Dolphins and porpoises, which also operate at higher frequencies, may be suffering the same problems. Source Research paper (full): https://peerj.com/articles/1657/
Douglas Adams, in his book "Last Chance To See", mentioned what he heard when he lowered a microphone into the stretch of river that was the blind Chinese river dolphin's last remaining home - a shrieking din, an impossible environment for an animal that hunted by sound. https://en.wikipedia.org/wiki/Baiji It went "probably" extinct a few years later. I've been tracking the animals he wrote about in that book, as the last chance to see them: that was the first to drop, afaik. The northern white rhino looks like the second (it's effectively extinct now, with no known breeding population and three known living individuals).
