195. Substrates across both the offshore cable corridor and the East Anglia THREE site are homogenous being characterised predominantly by sand and muddy sand (Chapter 10 Benthic Ecology). Therefore introduction of hard substrate would increase habitat heterogeneity.
196. This new habitat may in turn, be colonised by new faunal communities and species, potentially increasing the diversity, productivity and overall biomass of the local marine community (Chapter 10 Benthic Ecology). With respect to fish species these expected changes would potentially result in an increase in biomass through the introduction of new habitat, nursery areas and increases in prey productivity (Hoffman et al. 2000).
197. Scour protection represents an introduction of hard substrate to a marine environment in an area that it does not naturally occur in significant quantities. The worst case scenario for scour protection on the benthic environment is presented in Table 11.2. The worst case scenario is the installation of a 60m diameter GBS foundation with scour protection installed out to a diameter of 180m.
198. Further introduction of hard substrate would also occur as a result of a potential of up to 10% of inter-array and offshore export cables (including cable crossings) being protected by the potential methods outlined in Table 11.2.
199. The introduction of hard substrate into a predominantly soft substrate habitat would be expected to increase biodiversity and overall biomass due to an increase in habitat heterogeneity.
200. Lindeboom et al. (2011) found that new hard substrate introduced by the construction of the Dutch OWEZ windfarm acted as a new habitat type with a higher biodiversity of marine organisms.
201. The expected increase in diversity and productivity of sea bed communities may have an impact on fish, resulting in either attraction or increased productivity (Hoffman et al. 2000). The potential for marine structures, whether man-made or natural, to attract and concentrate fish is well documented (Sayer et al. 2005; Bohnsack 1989; Bohnsack & Sutherland 1985; Jørgensen et al. 2002). Further studies that have been carried out at Swedish windfarms showed that bases of the foundations acted as a fish aggregation device (FAD) for demersal and pelagic species alike (Inger et al. 2009).
202. The study concluded that the effect of a FAD was that the biomass of fish species was higher around foundations compared to areas where there was no FAD present (Wilhelmsson et al. 2006). Fish aggregate from the surrounding areas, attracted by
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 11 Fish and Shellfish Page 70
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