Research: Porpoises, not methane, may be responsible for mysterious pits in North Sea

In the depths of the North Sea, researchers have long been puzzled by small depressions that appear to have been formed by leaking methane. However, recent discoveries have proposed a surprising explanation: these pits may actually be the result of foraging porpoises, challenging established beliefs about the geological features of the sea.

The idea that methane was responsible for the formation of these pits initially faced skepticism from Geoscientist Jens Schneider von Deimling of Kiel University. Given the North Sea’s sandy floor and strong currents, which prevent methane accumulation, he doubted the feasibility of this theory. “I didn’t really see any mechanisms that accumulate methane,” he stated.

Further research expeditions supported Schneider von Deimling’s doubts. Mapping studies utilizing a sub-bottom echo sounder, a type of sonar that emits sound waves to image the shallow subsurface, led researchers to conclude that methane was not responsible for creating the pits. “We mined thousands of miles of data for shallow gas, and simply didn’t find that,” explained Schneider von Deimling.

To delve deeper into the matter, researchers employed a high-resolution multi-beam echo sounder, enabling them to closely examine the shape of the pits. They discovered that the pits did not exhibit the conical shape typically associated with methane leaks; instead, they maintained a consistent depth of 4.3 inches (10.92 centimeters) but varied in width.

The collaboration between Schneider von Deimling and biologists studying harbour porpoises yielded a significant breakthrough. These porpoises, renowned for scouring the seafloor in search of buried sand eels, were found to overlap with the locations of the pits. Subsequent analysis of oceanographic data and echo sounder surveys confirmed this correlation, indicating that the pits were likely created by porpoises and later shaped by ocean currents.

This discovery challenges previous assumptions about the origins of these pits and underscores the interconnectedness of marine ecosystems. It highlights the importance of interdisciplinary collaboration in unraveling the mysteries of the natural world.