There are tens of thousands of mysterious holes at the bottom of the North Sea. It was assumed that they form when gases leave the seafloor, for example. But new research now reveals that in some cases things are very different…
In many cases, gases not seeping from the seafloor, but porpoises, seem to be the cause; Scientists have reached this conclusion after long and extensive research using many different scientific disciplines. For example, when hunting sand eels, porpoises leave small scratches about 11 cm deep. These scratches can eventually develop into craters up to 50 meters deep. The results are therefore very important, because these deep wells could ultimately have a significant impact on the various ecosystems found in the sea.
Liquids
Previously, it was believed that wells were located at the bottom of the sea, and it is also called Warts They are always formed from liquids and gases that have left the seafloor. New research shows that this is not always the case. For example, there are many sand eels on the sea floor and porpoises leave these holes behind when they hunt. These scratches resemble the so-called Warts, but it is much less deep, and therefore not the same. Scientist Jens Schneider von Demling helped in the research. He says: “Our results show for the first time that these scratches on the sea floor are directly caused by the way porpoises and sand eels behave. So the scratches are not just caused by rising fluids.” The research has been published in the journal Earth and Environment Communications.
Porpoises on the hunt
Scientists used a range of different techniques for research. For example, they used very modern depth sounders, looked at the behavior of porpoises and even used satellites. Ultimately, they discovered 42,458 wells in the North Sea area they examined with an average depth of 11 cm. Scientists found it striking that these pits are mainly found in sand snake breeding areas. This confirmed their hypothesis that not all wells on the seafloor are caused solely by rising gas and water at the bottom. “We had to come up with an alternative hypothesis that could explain where these wells are coming from,” explains Schneider von Demling. “This finally allowed us to predict where potential hunting grounds for porpoises should be located, and that's exactly where we found the wells: always near areas where porpoises live.”
green energy
Scientists suspect that the small wells could eventually develop into much larger wells up to 50 meters deep. This is important to know because it can have major impacts on how marine ecosystems evolve. “In the long term, the results will be of great interest, especially from a geological and biological perspective,” says Schneider von Daimling. “The results can therefore be used to better assess the environmental risks of green energy at sea. In this way, marine life can be better protected.”
In addition, it is now clear that the many small scratches on the ocean floor ultimately have a large impact on the amount of sediment transported in the area. The first calculations show that the study area is 1581 km22 Nearly 773,369 tons of sediment alone settled. This amount of sediment is equivalent to the weight of 500,000 cars. Although the porpoises themselves are only interested in hunting sand eels, they also initiate the processes that ultimately shape the ocean floor.
