Page 76 - Alderney Regional Environmental Assessment of Renewable Energy: Environmental Report

Alderney Regional Environmental Assessment of Renewable Energy:
Environmental Report
A total of 13 intertidal biotopes were recorded across both the inshore and offshore rock
outcrops (AWTE, 2013c). The most predominant biotopes recorded were identified as high
energy littoral and infralittoral on stable bedrock and rocky shorelines.
On the inshore reef, the bladder wrack biotope LR.MLR.BF.FvesB dominates higher ground
levels. The common brown seaweed Himanthalia elongata biotope was identified extending
across the most part of the lower infra-littoral and sub-littoral environments. A high density of
the seaweed Bifurcaria bifurcata was noted on the biotope LR.HLR.FR.Coff.Coff, but not to the
extent seen on the offshore reef (AWTE, 2013c). The quadrat survey stations from the fixed
photography monitoring survey (AWTE, 2013d) also revealed the presence of the biotope
LR.MLR.BF.Fser.R, which is composed of a mixture of the Phaeophyta macroalgae species,
Fucus serratus, and other Rhodophyta macroalgae species. Both these biotopes are also
regarded as moderately ecologically important as they sustain high biodiversity, and provide
important food sources (such as amphipods) for intertidal creatures, fish and seabirds (AWTE,
2012).
The offshore reef was characterised by the presence of large quantities of highly unstable
coarse sediment where scour-tolerant species dominate (AWTE, 2013c). The quadrat survey
stations within the offshore section predominately comprised of high to moderate energy
biotopes and a number of other biotope types (AWTE, 2013d). This included the infralittoral
fringe kelp Saccorhiza polyschides biotope, IR.HIR.KSed.Sac, which is described as a sand-
scoured, kelp dominated environment (AWTE, 2012). This biotope extended across the whole
infra-littoral fringe and corresponded to 58% of the overall survey area. This biotope is
regarded as uncommon in the UK, mainly due to the physical characteristics associated with it.
Although it has not been assigned with an importance status in the British Isles, this biotope is
considered of locally moderate importance (AWTE, 2013c).
A total of 21 macroalgal species were identified during the survey of the Brinchetais Ledge
survey area, overall (AWTE, 2013d). This included 3 Chlorophyta, 7 Phaeophyta and 11
Rhodophyta taxonomic grouped species. The inshore section consisted of slightly larger
estimates of species biodiversity; however macroalgae composition and functional form were
generally similar between the inshore and offshore sections of the Brinchetais Ledge survey
area due to large proportions of the coralline algae Lithothamnia species recorded within both
sections. A high density of the seaweed Bifurcaria bifurcata was noted on the infra-littoral
fringe and infra-littoral zone of the offshore reef characterised by the biotopes Coralline
officinalis and Mastocarpus stellatus on exposed to moderately exposed lower eulittoral rock
(LR.HLR.FR.Coff.Coff) on its uppermost level and IR.HIR.KSed.Sac on the lower levels
(AWTE, 2013c).
Eight species were recorded within the Brinchetais Ledge survey area, comprising 1 Cnidarian,
1 Crustacean, 1 Poriferan and 5 Molluscan species. The total number of faunal individuals
recorded within the inshore and offshore sections was largely comparable. Intertidal faunal
species composition differed slightly between the inshore and offshore regions of the
Brinchetais Ledge survey area, due to larger proportions of the anemone, Actinia equina
recorded within the offshore section. The analysis also outlined the overall dominating
presence of barnacle species throughout the survey area (AWTE, 2013d).
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