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Harbor porpoises are often fatally injured in munitions detonations

2022-01-27T16:52:32.403Z


Harbor porpoises are Germany's only whale species and are highly endangered. Scientists from the University of Hanover have now discovered that many animals die as a result of underwater explosions in the North and Baltic Seas.


Enlarge image

The porpoise is a sea creature with sensitive hearing

Photo: Nature Picture Library / IMAGO

Bleeding in the head tissue, broken auditory bones - when examining 24 dead porpoises, experts from the Veterinary School found characteristic injuries that could only have been caused by strong pressure waves.

These results provided the first evidence that underwater explosions caused by the detonation of munitions actually pose a deadly threat to animals.

Whales have sensitive hearing systems

Experts had been warning for some time about a possible connection between an increased number of dead porpoises washing up on the coasts of northern Germany and detonations of ammunition.

For example, a report by the Federal Agency for Nature Conservation from 2020 showed that the sound pressure from an underwater blast was so great that it could potentially kill the whales in the affected area.

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The researchers from Hanover now examined 24 dead harbor porpoises that were found between September and November 2019 on the Schleswig-Holstein Baltic Sea coast.

According to the university, some of the carcasses were discovered just a few weeks after 42 British aerial bombs from World War II were detonated near the Fehmarn protected area.

The results were published in the journal "Environmental International".

The experts found characteristic injuries to the acoustic organs in ten animals: pathological dislocations and fractures of the middle ear bones, bleeding in the acoustic fat of the lower jaw, the auditory system and the so-called melon.

The melon, which consists of fatty tissue, is important for the echolocation of the animals and thus for orientation, communication and prey capture.

According to the doctors, these injuries can only have been caused by strong pressure waves.

»High direct and indirect damage potential«

A harbor porpoise also had bleeding and hematomas in muscle and fat layers.

This points to a “blunt blast trauma”.

Another animal with blast injuries was found as by-catch.

It can be assumed that the orientation of these two porpoises was significantly reduced by the injuries - which also led to their death.

"This underlines the high direct and indirect damage potential of the blasts," said Ursula Siebert, who heads the Institute for Terrestrial and Aquatic Wildlife Research at the University of Veterinary Medicine.

more on the subject

Munitions dumped in the North and Baltic Seas: time bombs on the seabedBy Jörg Römer

Large amounts of old ammunition lie in the waters of the Baltic and North Seas.

The mines and bombs were placed or dumped there during and after the end of World War II.

If it is not possible to recover the ammunition, it will be detonated because it poses a threat to shipping routes and wind farms under construction.

However, detonations under water produce extreme pressure and sound waves that spread for kilometers and can seriously damage the animals.

Ways to protect the animals are ignored

There are technical protective measures that reduce the risk.

For example, "curtains" of rising air bubbles can significantly limit the propagation of shock waves.

You can also try to drive the animals out of the affected areas before the blast by means of acoustic disturbances.

However, these opportunities are not always used.

No noise protection measures were taken during the blast in 2019.

In that year, at least 180 dead porpoises are said to have been found on the German Baltic Sea coast.

Harbor porpoises are Germany's only whale species.

They are considered critically endangered.

In the central Baltic Sea, the harbor porpoise is threatened with extinction.

vki/dpa/AFP

Source: spiegel

All tech articles on 2022-01-27

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