The causes of death of 900 dolphins off the coast of Peru

News. New York, May 30. According to The New York Times, experts from the environmental organization Orca Peru, investigated tissue samples of dead dolphins came to the conclusion that the cause of the mass death of dolphins, most likely the sonar (sonar), which are used for different kinds of survey work using acoustic emission .

According to scientists, the dolphins have died from decompression sickness, which was caused by the action of the acoustic equipment used by the U.S. company BPZ for exploration in search of oil. In addition to dolphins in the same area killed about 1,500 pelicans.

One of the first versions of the death of the animals was the effect of the toxins that can get into the water in an area where the U.S. company BPZ conducts exploration. Later version was considered the possibility of viral infection or bacterial infection, which is also not confirmed, because the test results were negative.

The hypothesis of a lack of food in the area also seemed unlikely to scientists, since species of dolphins that died, the common dolphin (Delphinus capensis) and Argentine porpoises (Phocoena spinipinnis), can easily be transported over long distances.

"Animals have died from an attack of the bends caused by acoustic trauma. Harm, was not compatible with life, dolphins caused, apparently, seismic equipment used for the exploration of hydrocarbon deposits, "- said the Marine vet, President Orca Peru Carlos Yaypen-Yyanos.

All 30 animals tested had traces of bleeding in the middle ear, the gas bubbles in the tissues of all the organs, and emphysema, which indicates acute decompression (decompression) of disease. It occurs when a rapid change in pressure in the external environment, where due to the strong contrast with the internal pressure of gases dissolved in the blood and tissues of the body are highlighted in the form of bubbles and destroy the cell walls throughout the body.
According to scientists, the gas bubbles in the tissues of dolphins could be the result of "direct physical impact of strong sound wave, which could destabilize the gas pressure in animals."

President Orca Peru Yaypen-Yyanosa believes that the harmful effect is intermittent, since dolphins killed at the same time, they were thrown to the shore for a few tens of individuals within 2-4 months.

First it was assumed that marine mammals have some sort of immunity to decompression sickness. But scientists have known many cases where whales and dolphins died due to human activities, such as during military exercises using sonar or seismic surveys.


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