Blinding solar storms could be the cause of whale strandings
Grey whales may be "blinded" by solar storms, according to a new study published in the journal Current Biology. The solar activity interferes with the whales’ internal magnetic navigation system, causing them to become stranded on the shore, often resulting in death.
Many species of whales have been observed undertaking mammoth seasonal migrations that take them from ocean regions rich with food to their traditional breeding grounds. Depending on the species, a whale can travel upwards of 10,000 miles (16,100 km) on a single migratory round trip, which often takes the vast marine mammals close to shorelines.
Sadly, each year seemingly healthy whales are found stranded on shorelines across the globe, where, without intervention, they inevitably die.
Scientists have explored a relationship between sunspots – dark regions that occur on our star’s surface and are known to accompany solar storms – and stranding events.
During a solar storm high-energy particles are ejected from our Sun’s atmosphere, and rush outward into the solar system. These particles interact with Earth’s geomagnetic field, sometimes disrupting it to such an extent that it can affect the behavior of organisms that rely on it to navigate.
A newly published study builds on earlier work to explore how sunspots may be linked to gray whale strandings, and investigates the process by which the Sun is able to disrupt the marine mammals’ navigational sensors.
The researchers used data spanning 31 years, and focused on 186 strandings that involved healthy, uninjured whales.
Upon analyzing the data, it was revealed that the chance of a stranding was around twice as high on days during which spots occurred on the Sun’s surface, than on randomly selected days when they did not. This suggests that the whales rely on a form of magnetic navigation to maintain a true course during their long migrations.
The research details two ways that the solar activity could have confused the whales’ magnetic instinct.
"Is it that the solar storms are pushing the magnetic field around and giving the whales incorrect information – for example, the whale thinks it is on 4th Street, but it is actually on 8th?" comments Jesse Granger of Duke University, co-author of the new study. "Or is it that the solar storms are messing up the receptor itself – the whale thinks it is on 4th Street, but has just gone blind?”
It is possible that the whales were becoming stranded as a result of a deviation in Earth’s magnetic field brought on by an interaction with charged particles from the Sun, tricking the whales into thinking that they are in the wrong place.
Secondly, the solar particles could lead to an increase in solar radio flux, which according to the study is the "globally averaged measure of radio frequency (RF)." This radio noise has been known to interfere with several species’ magnetic navigation capabilities, and so could be "blinding" the whales’ biological sensors.
The results of the study revealed that the latter scenario is more likely to be the case. Whales were four times as likely to become stranded on days that coincided with a high RF noise due to solar activity compared to other randomly selected days.
Conversely, the team found no significant increase in the number of beachings on days wherein Earth’s magnetic field had deviated from normal.
The researchers stress that solar activity is not the sole cause for whale strandings, there are also anthropogenic reasons, including interference from naval sonar.
The paper has been published in the journal Current Biology.
Source: Duke University