Page 128 - Alderney Regional Environmental Assessment of Renewable Energy: Environmental Report

Alderney Regional Environmental Assessment of Renewable Energy:
Environmental Report
more distant prey resources (if such a change were to occur), than for instance gannets that
are generally less sensitive to natural changes in the availability of food, and can forage over a
much wider area. Diving species with high wing loading have high energetic cost during flight,
thought to be linked with adaptation of wings for underwater locomotion (Gaston and Jones
1998; Thaxter et al., 2010). Thus, while they have the potential to forage far from colonies,
their typical ranges may be smaller than those of other species, i.e. 20-40km (Thaxter et al.,
2009; 2010), and may be less flexible in making changes in the event of reduced prey
availability (Enstipp et al ., 2006). In summary, diving species are considered to have a
moderate sensitivity to this effect, and surface-feeding species have a low sensitivity.
All birds are at some risk of disturbance from the indirect loss of foraging habitat although it is
clearly the case that this is dependent upon foraging locations used by different species (i.e.
whether they feed on intertidal or offshore locations) and the area of development activity. In
general, the effects will be temporary during initial survey phases, causing minimal disruption.
However, more significant effects may occur in the construction, operation and
decommissioning phases. For instance, Garthe and Hüppop (2004) evaluated the sensitivity of
species to offshore wind farms, and their score for flexibility in habitat use provides a useful
measure to the sensitivity of species to this effect. As suggested by evidence from offshore
wind farms, red-throated divers and common scoters (both diving species) may be particularly
sensitive to disturbance and thus the effects of indirect habitat loss. Displacement studies
around turbines and boat related activity reported in NE and JNCC (2010) showed that up to 80
to 100% of red-throated divers were displaced from the development footprint and surrounding
area. The effect of disturbance and habitat exclusion will depend on the extent of construction
and operational activities, as well as the time of year; a potential mitigation is to avoid
construction at vital times (i.e. before and during breeding) when prey is needed by adult birds
and for provisioning to offspring.
In the absence of further information on specific location of elements of the Draft Plan (and
therefore the degree of overlap with potentially sensitive areas), exposure to change is
considered to be medium if percussive piling is required for construction of tidal stream
turbines, offshore substations, onshore substations and onshore wind turbine resulting in an
insignificant to minor adverse impact for terrestrial and surface-feeding foraging birds, and
minor to moderate adverse for diving birds. For all other elements and phases of the Draft
Plan, exposure to change is considered low and the potential impacts insignificant to minor
adverse.
5.4.2.6 Non-toxic contamination
As outlined in Section 4.3.2.2, in areas being excavated or disturbed for the installation/removal
of tidal stream turbines, cables or offshore substations there will be a temporary increase in
SSC and turbidity, potentially leading to effects on (diving) seabird foraging success and
predator-prey interactions. Species diving underwater are at greatest risk of having foraging
activity disrupted by sediment mobilisation and suspension, and this is most likely to occur
during the construction and decommissioning phases. Diving species such as Auks, Shags
and Cormorants use much of the water column and thus are considered to have a moderate
sensitivity to this effect, whereas surface-feeding seabirds are considered to have a low
sensitivity. However, all species are at risk of disruption due to likely prey avoidance of areas
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