East Anglia ONE
EMF Assessment
pinnipeds are known to enter the North Sea sporadically, often during the summer months (SMRU 2001; Hammond et al 2005). Owing to their predominantly pelagic existence, with migrations strongly linked to surface waters for breathing, these species are only likely to encounter the B fields generated by EAONE OWF should they dive to feed near the seabed or should they venture into very shallow water. Owing to the rapid attenuation of the B fields with distance from the cables, combined with lack of evidence of effects upon cetaceans, it is expected these mammals will be largely unaffected by the current project. The same is postulated for chelonians (turtles), some species of which are also sporadic summer visitors to the North Sea (e.g. leatherback turtle, Dermochelys coriacea; Reeds 2004), for similar reasons.
6.2. iE fields
Again, research into possible interactions between marine fauna and electric fields generated by sub-sea cables is still at an early stage, and information relatively limited. Given the sensitivity of certain marine organisms to electric fields there is potential for effects to occur. There are three main concerns:
Repulsion Confusion with bioelectric fields Physiological effects
6.2.1. Invertebrates
No marine invertebrates have been definitively demonstrated as being electrically sensitive (it has been suggested that certain freshwater crayfish may possess an electric sense (Patullo & Macmillan 2007), but evidence remains lacking (Steullet et al 2007)). The iE fields expected to be induced are of relatively minimal strength and therefore unlikely to cause detrimental physiological effects to these taxa, supported by anecdotal evidence of benthic invertebrates living directly upon DC electrodes (Nielsen 1986) with no apparent effects (Walker 2001; Swedpower 2003). Therefore, no effects of induced electric fields surrounding EAONE cables are expected among these taxa.
6.2.2. Fish
In general, teleost fish are not believed to be electrically sensitive (except weakly electric fish, such as electric catfishes or knifefishes, but these are almost entirely tropical freshwater species). The marine Perciformes (electric stargazers) do possess electric organs, but appear not to utilise electroreception (Bradford 1986; Bullock et al 1983). Species such as salmon, tunas, plaice and cod have been postulated as being electrically sensitive in the past (Regnart 1931; Rommel & McCleave 1973; Kalmijn 1974), but more recent reviews have cast doubt on these abilities (Bullock 1986). Teleosts would probably only respond to strong electric fields of 6 to 15v/m or more, at which levels the fish would be repulsed (Uhlmann 1975; Poleo et al 2001). Sturgeons (Acipenseriform fish), for example, have been shown to veer away, or slow when approaching high voltage overhead lines (110kV) passing over the water (Poddubny 1967). However, even the maximum electric field induced around separated and unburied cables likely at EAONE are a number of orders
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