Page 79 - Alderney Regional Environmental Assessment of Renewable Energy: Environmental Report
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Alderney
Regional Environmental Assessment of Renewable Energy:
Environmental Report
During the 2007 Seasearch survey a number of introduced seaweed species were also
recorded. These included the red seaweed
Asparagopsis armata
which was widely and
commonly recorded around Alderney (Wood, 2007). This species has barbed branches and
attaches to and becomes entangled with, other seaweeds. Another introduced species, the red
algae
Heterosiphonia japonica,
was found in the drift in Braye harbour. It has previously been
recorded on Guernsey. Conversely, thriving populations of the small green seaweed
Codium
tomentosum
were observed. This is the native species which has been replaced by the
invasive green sea finger
C. fragilis
at many sites on the English south coast.
5.1.1.3
Future baseline
Climate change presents various pressures to benthic habitats in terms of the likely increase in
sea level rise (see Section 4.2.1.3). Along Alderney’s coast, these changes could potentially
lead to a reduction in intertidal habitat due to coastal squeeze in areas where hard sea
defences and/or military defences back some of the bays (e.g. Longis Beach), which will have
implications for associated benthic intertidal communities. In addition, climate change could
lead to potential changes in water temperature and an elevated threat from invasive non-native
species. The introduction and establishment of non-native species may also have future
impacts on the ecology with species competing for food and space with indigenous organisms.
5.1.1.4
Limitations and data gaps
A large number of existing relevant baseline studies of intertidal and subtidal species and
habitats exist for the waters around Alderney. The intertidal surveys are concentrated along
the southern coast of Alderney where it is presumed any cable landings would interact with this
habitat. It is assumed that intertidal habitats and species along the north coast of Alderney
would be similar to those observed on the south coast as both sides of the island experience
similar physical forcing characteristics. Due to the importance of some of the benthic species
recorded at Alderney, additional sampling/survey of both intertidal and subtidal areas may be
beneficial to identify and map the distribution of these rare species.
The Agence des Aires Marines Protégées will be publishing the results of a major program to
map the marine habitats in French waters, called CARTographie des HAbitats Marins
(CARTHAM
3
), in the first half of 2014. This study could provide complementary information on
the characterisation and distribution of habitats in the French part of the Race.
The monitoring requirements for benthic marine survey at the EIA project-level will need to be
considered by individual developers, particularly in areas where there is a paucity of data. It is
important to note that the Alderney Wildlife Trust has recommended that a 3-year programme
of ecological baseline information would be required to inform an assessment at the project-
level. Examples of the specialist surveys which may be required to support the EIA include:
Benthic grab samples for faunal and sediment analysis;
Videos/photography surveys;
Trawling surveys;
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