Page 70 - Alderney Regional Environmental Assessment of Renewable Energy: Environmental Report

Alderney Regional Environmental Assessment of Renewable Energy:
Environmental Report
Twelve different biotopes were identified, the majority of which (8) were infralittoral rock
biotopes. This is unsurprising given the preponderance of shallow sites surveyed by
Seasearch. Because of the lack of circalittoral habitats surveyed in 2010 the sponge fauna
was limited to 25 species. Species newly recorded for Alderney were Grantia compressa (Les
Boufresses - Site 2c), Leuconia gossei (Rousset - Site 6c), Stelligera stuposa (Les Boufresses
and Queslingue - Site 4c), Myxilla rosacea (La Tchue - Site 7c) and Endectyon delaubenfelsi
(La Tchue). Two nationally scarce species recorded were Adreus fasicularis (Les Boufresses,
Queslingue and La Tchue) and Axinella damicornis (Les Boufresses, Queslingue, Rousset and
La Tchue).
The seaweeds encountered during the survey were mostly typical of this biogeographic region,
with seaweeds typical of southern Britain together with others which are fairly scarce in Britain
but more common on Atlantic coasts of France and the Iberian Peninsula to the south.
Examples include Haliptilon squamatum, Gracilaria bursa-pastoris, Gigartina teedii and Codium
vermilara. During the 2010 Seasearch survey the Alderney seaweed flora was considered
particularly rich and interesting with a large number of species being recorded from a small
number of sites (Wood, 2010).
Only limited numbers of molluscs were recorded. However, they included four new species for
Alderney. They are all widespread species and in three cases somewhat seasonal in
occurrence. They comprise the moon snail Euspira catena (South of Rubbish Tip - Site 8c),
sea hare Aplysia punctata (Longis Bay - Site 3c), fried egg sea slug Diaphorodoris luteocincta
(Queslingue, La Tchue and South of Rubbish Tip), and sea slug Crimora papillata
(Queslingue).
There were relatively few records of hydroids, anemones and corals, partly due to the shallow
nature of the sites surveyed. Similarly, no unusual flatworms or segmented worms were
observed and crabs, lobsters, shrimps and prawns were notable for their small numbers and
low diversity at all sites. As in previous surveys in Alderney, echinoderms were not numerous
and no new sea squirts were recorded for the area. As on previous surveys the most common
species of sea squirts were the orange sea squirt Stolonica socialis, and two club sea squirts
Aplidium punctum and Morchellium argus.
As observed in the 2007 intertidal survey, the entrance to Longis Bay (Site 1a) is home to an
extensive eelgrass bed. During the 2007 Seasearch survey this eelgrass bed did not appear to
be particularly species rich, though there were burrowing worms and anemones (Wood, 2007).
In 2008, a follow up survey was undertaken to attempt to map the extent of the seagrass bed in
more detail. The survey showed that there was continuous eelgrass across the whole of the
western side of Longis Bay but there is a gap closer to Raz Island (Wood, 2008). This site was
further surveyed in 2010 (Site 3c) where there was found to be continuous eelgrass across the
whole of the mouth of the bay (Wood, 2010).
Sparse areas of eelgrass were also found in the harbour close to the wall (Site 9a) and Saye
Bay (Site 6a) in 2007. Another tide-swept eelgrass bed was also identified in Frying Pan Bay
(Site 5c) in 2010. Seagrass beds, including eelgrass (Zostera marina) are a threatened habitat
in many areas because they occur in shallow, sheltered areas which are also popular with
R/4001/7 46 R.2129