High-voltage electricity surging through undersea power cables doesn’t bother local sea life, three new studies suggest. The work eases concerns that planned offshore power production from wind turbines and tidal generators would disrupt marine communities.
Tracking the movements of fish and crabs around underwater power cables, the new studies reveal that marine critters don’t shy away from the magnetic fields put off by the cables. One study even found that the thick cables can serve as artificial habitats and host undersea communities.
“There’s much less of a concern now,” said Ann Bull, a marine biologist at the Bureau of Ocean Energy Management in Camarillo, Calif., who presented two of the studies February 26 at the American Geophysical Union’s Ocean Sciences Meeting.
In the 1980s, the first underwater telecommunications cables clashed with marine life: Sharks intrigued by electric fields put off by the wires would gnaw on the cables, often leaving teeth behind. Wrapping the cables in insulating material blocked the electric fields and stemmed shark attacks, but magnetic fields generated by the cables remained. Laboratory experiments show that many marine creatures can sense even relatively weak magnetism, sparking fears that the cables serve as “electric fences” that disrupt sea life.
Commercial fishers particularly worried that crabs wouldn’t cross undersea cables to find bait in crab traps. To test this, Bull and her colleagues built cages with two baited traps, one of which required crabs to pass over an active power line. Both Dungeness crabs (Metacarcinus magister) and rock crabs (Romaleon antennarium) had no problem crossing the line: In hundreds of trials, the crabs chose each trap around half the time.
