Researchers find reason for strange holes in the North Sea

A team of researchers examined the seabed off Heligoland for noticeable depressions. An interesting connection came across.

Helgoland – What happens on the ocean floor is unfathomable to most people. But even researchers who have been studying these topics for many years continue to experience surprises. This is shown by a current study by the Christian Albrechts University in Kiel (CAU). The scientists examined supposed pockmarks in the North Sea.

Deepenings in the North Sea are puzzling researchers

These are crater-like depressions in the sediment that are created by the escape of methane or groundwater, explains the University of Kiel on their website website. There are millions of them. But the ones before Helgoland The studied depressions in the North Sea are something special. The research team led by the geoscientist Dr. Jens Schneider from Deimling convinced.

“We had to develop an alternative hypothesis for its origin,” says the researcher. With his colleagues from the fields of biology and oceanography, he had an interdisciplinary team with which he was able to take different perspectives on the research subject.

Sensitive technology helps to investigate depressions in the North Sea

To record the surface of the seabed in the North Sea, Schneider von Deimling used a modern echo sounder. Using the device, he found that the holes were on average just eleven centimeters deep and therefore particularly shallow. “Our high-resolution data provide a new interpretation for the formation of tens of thousands of pits Seabed in the North Sea and we predict that the underlying mechanisms apply globally but have been overlooked so far,” he says.

The suspected connection was: The depressions in the North Sea were caused by harbor porpoises searching for food. The species of whale, which at first glance looks like dolphins, prefers to feed on sand eels, according to studies of the stomach contents of stranded porpoises have shown. This type of eel burrows underground when threatened.

Harbor porpoises searching for food are the reason for depressions in the North Sea

Their hypothesis helped the researchers in their further investigations. “This enabled us to predict where potential harbor porpoise feeding sites were, and this is exactly where we were able to find the pits – always close to sand eel habitats,” says Schneider von Deimling about the depressions in the North Sea. The researchers discovered almost 42,500 depressions. “Our extensive and cross-disciplinary data analysis now provides a coherent explanation for our porpoise pit hypothesis.”

He even dares to take a broader look at his results. “The formation mechanism of these pits, as we call them, probably also explains the existence of numerous crater-like depressions on the seafloor worldwide, which have been misinterpreted as the result of methane gas leaks.”