The hidden world beneath the waves is becoming increasingly crowded with human technology. Submarine power cables, which carry electricity from offshore wind farms and other marine installations, are vital for renewable energy. Yet, new research has uncovered an unusual side effect: female crabs actively move toward the electromagnetic fields these cables generate.
A Magnetic Attraction
In controlled laboratory experiments, scientists observed female shore crabs (Carcinus maenas) spending much more time near areas where electromagnetic fields were present. Using Helmholtz coils, researchers created fields that mimic the strength of electricity-carrying submarine cables. The females slowed their movement by nearly 40 percent in these zones, showing that the invisible fields altered their natural behavior. Males, on the other hand, showed little response and continued to wander freely regardless of the electromagnetic environment.
Why This Matters
Shore crabs play a crucial role in marine ecosystems as both predators and prey, and their movements directly affect reproduction. Female crabs usually migrate to deeper waters to release eggs, ensuring that larvae drift into the open ocean. If these females linger around cables instead, they risk delaying or disrupting migration. Such changes could force them to release eggs in the wrong place or at the wrong time, reducing larval survival and destabilizing crab populations.
Future Considerations
As countries expand offshore renewable energy, engineers continue to lay more submarine cables across the seafloor. This discovery highlights how subtle technologies can reshape marine behavior, urging planners to account for ecological impacts when designing underwater infrastructure. Scientists still do not know why females react so strongly, but the findings open important questions about how electromagnetic fields influence life in the sea.
