Scientists know that some chopped whales blend and die after exposure to naval sound and now they know why: giant marine mammals suffer from decompression diseases such as divers.
At first, the explanation presented today by 21 experts in the Royal Society magazine exploded Procedures B it seems implacable
Millions of evolution years have turned whales into perfectly calibrated diving machines that penetrate kilometers below the surface for hours to a section, feeding on food in the depths of ink.
Heart rate decreases, blood flow is limited, oxygen is maintained. So how could the deepest diver in the ocean finish off with nitrogen bubbles that poison your veins, like a diving beginner that rises too quickly to the surface?
Brief answer: Chopped whales, especially a species known as Cuvier, are really frightened.
"In the presence of sonar they are stressing and swim vigorously outside the sound source, changing their diving pattern," said lead author Yara Bernaldo de Quiros, a researcher at the Institute of Animal Health of the University of Las Palmas de Gran Canaria, Spain.
"The response to stress, in other words, invalidates the diving response, which causes animals to accumulate nitrogen," he added. "It's like an adrenaline shot."
A type of sonar in particular casts these whales away from the balance.
MASS-ATTACHED RATINGS & # 39; ATTENTION & # 39;
Developed in the 1950s to detect submarines, the active medium frequency sound (MFAS) is used today in patrols and naval exercises, especially for the United States and its NATO allies.
As of 1960, the ships began to emit submarine signals in a range of about 5 kilohertz (kHz).
It was when the massification of whales whipped began, especially in the Mediterranean.
Between 1960 and 2004, 121 of these called "atypical" masses were produced, with at least 40 closely linked in time and the site with naval activities.
These were not individual captives of old or sick animals, or in massive reservoirs like last November in New Zealand, when more than 200 pilot whales approached.
On the contrary, a handful or more chopped whales would be grounded in a day or two, and not more than a few miles away.
The deadliest episode, in 2002, was detained for a period of 36 hours in the Canary Islands during a naval exercise in NATO.
"After a few hours of the development of sonar, the animals began to appear on the beach," said Bernaldo de Quiros.
On the outside, whales did not show signs of illness or damage: they had normal body weight and had no skin lesions or infections.
Internally, it was another story. The nitrogen gas bubbles filled the veins and their brains were destroyed by hemorrhaging.
Autopsies also revealed damages to other organs, as well as to the spinal cord and the central nervous system.
CANARY ISLAND MORATORIUM
As with altitude sickness, reactions, in humans, and probably in whales, to nitrogen bubbles in the blood vary in type and intensity.
A 2003 study a Nature about the possible link between sonar and the death of whales led Spain to ban these naval exercises around the Canaries in 2004.
"Until then, the Canaries were a key point for this type of" atypical "breaks, said Bernaldo de Quiros." Since the moratorium, none has produced. "
The authors called for similar prohibitions to be prohibited in other regions where whales at risk are known.
Cuvier's chopped whale grows up to seven meters and is mainly eaten by squid and deep-sea fish. His mouth turned to the outside gives the impression of a permanent smile.
The whale is listed as "vulnerable" on the red list of threatened species of IUCN, and is believed to have a global population of 5,000 to 7,000.
Other threats include boat strikes, ocean pollution and changing habitats caused by climate change.