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Electromagnetic Fields and Marine Organisms

The electricity produced by offshore wind turbines is transmitted by cables over long distances. The electric current generated produces magnetic fields. Studies of possible effects of artificial static magnetic fields have been carried out on various species under various experimental conditions. Artificial electromagnetic fields could interact with marine organisms to produce detectable changes. Usually, however, only very slight differences in control groups have been recorded.

The magnetic field may affect molluscs, crustaceans, fish and marine mammals that use the earth's magnetic field for orientation during navigation. But it is still unknown whether the magnetic fields associated with wind turbines influence marine organisms (Gill, 2005).

Elasmobranches, one of the more electro-sensitive species, are attracted by electrical fields in the range of 0.005-1 µV cm1 and avoid fields over 10 µV cm1.

Electro-sensitive species could be attracted or repelled by the electrical fields generated by submarine cables. Special attention must be paid in areas of breeding, feeding or nursing because of the congregation or dispersion of sensitive individuals in the benthic community (Gill, 2005).

Experimental analysis on several benthic organisms exposed to static magnetic fields of 3.7 mT for several weeks have shown no differences in survival between experimental and control populations. Similarly, mussels living under these static magnetic field conditions for three months during the reproductive period do not present significant differences with the control group. The conclusions are that static magnetic fields of power cable transmissions don't seem to influence the orientation, movement or physiology of the tested benthic organisms (Koeller et al, 2006).

The results from the study carried out on Nysted about the influence of electromagnetic fields on fish are not conclusive. Some impact on fish behaviour has been recorded, but it was not possible to establish any correlation. There is not enough knowledge about this topic and additional research is needed (DEA, 2006).

The magnetic fields of both types of cable (bipolar and concentric) used in marine wind farms, are small or zero. The Greenpeace study mentioned earlier concludes that the electromagnetic fields of submarine cables have no significant impacts on the marine environment (Greenpeace, 2005). Studies with a long-term perspective are necessary to confirm the negligible impact of electromagnetic fields of wind energy on marine ecosystems (Koeller et al, 2006).

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