Page 77 - Alderney Regional Environmental Assessment of Renewable Energy: Environmental Report

Alderney Regional Environmental Assessment of Renewable Energy:
Environmental Report
North of Houmet Herbé
An area north of Houmet Herbé located along the north-east coast of Alderney and extending
across all intertidal areas from Fort Houmet Herbé to the bay west of Fort Les was surveyed in
2012 (Figure 12). Both an intertidal habitat biotope survey (AWTE, 2013b) and an intertidal
Phase II fixed photography monitoring survey (AWTE, 2013e) were undertaken for the area.
This coastline consists of a variety of rocky shores, low cliff tops (lighthouse area), small bays
and minor sections of sandy and pebbly shorelines associated with those bays.
In total 29 intertidal biotopes were recorded across the survey area (AWTE, 2013b). The most
predominant biotopes recorded were identified as high to moderate energy littoral and infra-
littoral on stable bedrock and rocky shorelines. The area also includes two small bays, locally
known as St. Esquere Bay and Cats Bay, and a third bay to the west of Fort Les Houmeaux
Florains. High to extremely high wave exposure and strong tidal stream conditions were found
across some part of the survey area. The three bays show more moderate conditions which
allow the appearance of sandy areas within the more sheltered zones.
The quadrat survey stations from the fixed photography monitoring survey (AWTE, 2013e)
showed that the upper shoreline comprised of biotopes that represented moderate energy
types (such as LR.MLR.BF.PelB), lichen types (such as LR.FLR.Lic.YG) and also sediment
biotopes; LS.LCS.Sh.Barsh and LS.LSa.St.Tal. These represent low ecological status and are
commonly associated with this shoreline height region. In addition, the Fucus spiralis biotope
LR.MLR.BF.FspiB was recorded within this shoreline height. This biotope is assigned
moderate ecological status, based on this biotope sustaining high proportions of marine
invertebrate species (AWTE, 2012).
Quadrat survey stations within the mid shoreline height region represented a wider range of
biotopes, including; high to low energy types, rockpools and ephemeral macroalgal dominated
habitats (such as LR.FLR.Eph.EphX). This included the moderate ecological status biotopes;
LR.MLR.BF.Fser.R, LR.MLR.BF.Fser.Bo and LR.LLR.F.Fserr.X. These biotopes are
dominated by the macroalgal Fucus serratus and sustain high proportions of marine
invertebrate species (AWTE, 2012). In addition, the invasive macroalgae species Sargassum
muticum was also recorded as a rock-pool biotope, within this shoreline height (AWTE, 2013e).
The lower shoreline predominately comprised of high energy types and other biotopes types.
This included biotopes such as LR.HLR.FR.Him (characterised by brown seaweed) and
IR.HIR.KSed.Sac (characterised by kelp), which are commonly found within intertidal lower
shoreline height levels. Two moderately ecologically important biotopes were also assigned to
the quadrat survey stations within this shoreline height; LR.MLR.BF.Fser.R (characterised by
Fucus serratus seaweed) and LR.HLR.FR.Coff.Coff (characterised by red algae) (AWTE,
2013e). Both biotopes are known to sustain high biodiversity, with LR.HLR.FR.Coff.Coff also
providing important food sources (such as amphipods) for intertidal creatures, fish and seabirds
(AWTE, 2012).
A total of 33 macroalgal species were identified during the survey. This included 4 Ascomycota
(lichen), 4 Chlorophyta, 10 Phaeophyta and 15 Rhodophyta taxonomic grouped species.
Macroalgae species biodiversity and evenness estimates across the Houmet Herbé survey
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