Injuries, illnesses, loud noises: there are many reasons why whales are stranded. The activity of the sun could also play a role in these fatal events. As a study now shows, gray whales are strikingly frequent during solar storms. However, for a different reason than expected: Responsibility for the disorientation of marine mammals does not seem to be caused by changes in the earth’s magnetic field caused by the solar storms. Instead, there appears to be a connection with high-frequency electromagnetic noise from space. This noise can also be measured on Earth and could severely disturb the animals’ magnetic sense. In a way, they become blind, the researchers report.
Many living beings have a sixth sense: they can perceive the earth’s magnetic field. These animals include, for example, migratory birds, which use their magnetic sense to orientate themselves on their long flights. But fish, wild boar and even dogs also have a built-in magnetic compass. Whales probably also use the earth’s magnetic field to find their way in the vastness of the oceans. However, there are signs that the sense of orientation of marine mammals is failing again and again. Why else are they stranded regularly? To get to the bottom of this question, Jesse Granger from Duke University in Durham and her colleagues have now examined 186 strandings of gray whales. “We chose this species because it travels one of the longest migration routes among mammals and moves close to the coast – even minor navigation errors increase the risk of stranding,” the scientists explain.
Connection with sun spots
For their study, the research team only evaluated data from stranded whales that showed no injuries and had had no contact with humans shortly before their fatal emergence. They looked for connections between the strandings and external factors that have something to do with the magnetic field of the earth. In fact, the analyzes revealed that animals were stranded twice as often on days with many sunspots as on other days. Such dark spots on the surface of the sun are a sign of so-called solar storms. With this phenomenon, so many energetic particles are thrown into space that this can even disrupt the protective earth’s magnetic field – in extreme cases, a strong solar storm also affects the functionality of satellites and communication systems.
Are such marine mammals led on the wrong route by such magnetic field disturbances? Surprisingly, it was found that the strandings could not be directly linked to certain deflections of the earth’s magnetic field. Instead, the researchers found that what seemed to be decisive for the whales’ disorientation was an electromagnetic noise in the radio wave range generated by the solar storms in space, which could also be measured on Earth. Typically, these broadband interference signals are most noticeable at a frequency of 2800 megahertz. The researchers found that the risk of stranding on days with a particularly strong noise in this area increased fourfold. Granger and her colleagues assume that this noise cancels the whale’s sense of magnetism. “Studies with other animals already indicate that high-frequency noise can interfere with the magnetic sense,” the scientists report.
Fatal failure of the magnetic sense
This shows that the whales do not simply receive incorrect information due to the solar storms because the magnetic field changes – researchers had previously suspected this. “Our results show that the animals could rather get stranded because they really go blind,” states Granger. Overall, the scientists’ observations confirm the assumption that whales orient themselves in the sea using an internal magnetic compass and that failure of this navigation system is a reason for stranding events. But not the only one: There are many other aspects that can lead to whale strandings, as the research team emphasizes. In the future, further studies with other whale species will clarify how great the influence of solar activity on the sense of orientation of the marine mammals is and whether the patterns now observed can also be confirmed on a more global level.
Source: Jesse Granger (Duke University, Durham) et al., Current Biology, doi: 10.1016 / j.cub.2020.01.028