Page 73 - Alderney Regional Environmental Assessment of Renewable Energy: Environmental Report

Alderney Regional Environmental Assessment of Renewable Energy:
Environmental Report
The lower shoreline predominately comprised of high and moderate energy biotopes types.
This included biotopes such as the red algae biotope LR.HLR.FR.Pal, which is commonly
found within intertidal lower shoreline height levels. Two moderately ecologically important
biotopes were also identified within this lower shoreline height; LR.MLR.BF.Fser.R and
LR.HLR.FR.Coff.Coff. 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; 2013f).
A total of 24 macroalgal species were identified during the Phase II survey throughout the Bay.
This included 3 Ascomycota (lichen), 3 Chlorophyta, 8 Phaeophyta and 10 Rhodophyta
taxonomic grouped species. Macroalgae species biodiversity and evenness estimates were
lowest within the upper and mid shoreline height regions of the Hanaine Bay survey area. This
was due to the large proportion of the lichen species Caloplaca marina, within the upper
shoreline height region. The largest marcroalgal species biodiversity estimates were observed
within the lower shoreline height region (AWTE, 2013f).
A total number of 422 faunal individuals were recorded within the Hanaine Bay survey area,
including seven molluscan species. Again, the upper shoreline height region consisted of the
lowest abundance counts and biodiversity estimates, across the three shoreline height regions
of the Hanaine Bay survey area. Faunal species biodiversity estimates were greatest within
the mid shoreline height region. Species composition and functional forms showed some
differences between the three shoreline height levels. This was due to the dominance of the
top shell Phorcus lineatus within the upper shoreline height region and the common limpet,
Patella vulgata within the mid and lower shoreline height regions (AWTE, 2013f).
The South Coast of Alderney
AWTE completed an intertidal biotope survey between August and September 2011 in an area
located along the south coast of Alderney, adjacent to the Alderney Race tidal stream
(Figure 12). The coastline consists of a variety of rocky shore areas, pebbly and sandy
shorelines and also cliff tops.
A total of 28 intertidal biotopes were recorded across the survey area. As observed in Hanaine
Bay, the moderately important biotopes characterised by Fucus serratus, LR.HLR.FT.FSerTx,
LR.MLR.BF.FSerR, LR.MLR.BFFSer.Bo were also observed here. The importance of such
biotopes was based on the important role they play on marine invertebrates and in the life of
other marine animals.
The common brown seaweed Himanthalia elongata biotope (LR.HLR.FR.Him) was identified
extending across the lower infra-littoral and sub-littoral environments of the entire survey area.
These areas also comprise an element of the locally important Eelgrass biotope (biotope code:
SS.SMp.SSgr.Zmar), primarily concentrated between the Frying Pan and Impot areas (AWTE,
2012a). A variety of rockpools, caves and overhangs were also located throughout the survey
area, both within the upper and lower shore regions of the intertidal area. These were
characterised predominately by opportunistic and invasive seaweed species. This included
fresh-water influenced green seaweeds, encrusting algae and the invasive species Sargassum
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