Identical Response of Caged Rock Crabs (Genera Metacarcinus and Cancer) to Energized and Unenergized Undersea Power Cables in Southern California, USA

Abstract

Energy generation facilities (i.e., wave and wind) are being sited in offshore marine waters. The electricity generated from these facilities is transmitted to shore through cables carrying alternating or direct current. This current produces an electromagnetic field (EMF) that is emitted from the cable. Concerns have been voiced regarding how marine organisms, in this instance crabs, respond to the EMF emitted by submarine power cables. Two submarine cables, one energized and the other unenergized, and separated by about 7 m, were used in the experiment. Crabs (Metacarcinus anthonyi (Rathbun, 1897) and Cancer productus (Randall, 1839)) were placed in plastic perforated boxes secured to the sea floor with one end in contact with one of the two cables. After one hour and 24 hours, scuba divers ascertained the position of the crabs within the boxes, these positions designated as either “near-half” or “far-half.” EMF readings were taken on the floor of each box at the edge closest to the cable and on the floor of that box furthest from the cable at one and 24 hours. Within the boxes, EMF levels were between 46.2–80.0 microteslas next to the cable and