Parellel Conservation Management Acitivies
UK biodiversity action plan for maerl
UK biodiversity action plan for maerl
A biodiversity action plan for maerl as a habitat is being prepared by S. Scott, and is
currently in draft stage. The action plan notes that three of the statutory Marine Nature
Reserves in Britain, Skomer in Wales, Lundy in England and Strangford Lough in Northern
Ireland, contain maerl (although none have particularly well-developed beds). It also
notes the potential value of SSSI legislation in protecting maerl. Although most maerl
beds cannot normally be included within SSSI designations in England and Wales where the
lower limit of SSSI designation is usually mean low water, in Scotland, the planning
boundary is normally the mean low water of spring tides, which could include maerl where
it occurs in the subtidal fringe. This happens at a few sites, for instance at Taynish on
the shores of Loch Sween, Argyll, where the SSSI boundary (but not the NNR boundary)
extends to mean low water of spring tidcs and includes the high marine interest in the
rapids. However at best SSSI designation can only afford limited protection to a very
small proportion of total maerl populations. Proposed actions include:
- Listing maerl beds under Annex 1 of the Habitats Directive, both in their own right and
as a specific component of sealoch systems.
- Pressing for the addition of Lithothamnion glaciale to Annex V of the Habitats
- Ensuring that planning applications for structures such as roads and aquaculture
installations are compatible with the conservation requirements of maerl beds.
- Completing surveys of the extent, quality and composition of UK maerl bed communities.
- Listing further sites for eventual classification as SACs to ensure the full range of
maerl bed and associated community types and ecological conditions is represented in the
network of protected sites.
- Including provision for the maintenance of the extent and health of maerl bed
communities in management plans for SACs where these include maerl beds.
- Taking account of the conservation requirements for maerl bed communities in the
development and implementation of coastal zone management plans and ensuring that they are
not managed in isolation from other habitats and communities in these areas.
The EU MAST-funding BIOMAERL programme, co-ordinated by Prof. P.G. Moore, Millport, is
a 3-year collaborative programme between laboratories in UK, Spain, France and Malta, and
began in February 1996. Pairs of maerl grounds have been identified for study by
participants in the Clyde Sea area (Scotland), Galicia (Spairl), Brittany (France),
Alicante (Spain) and Malta. Each pair represents a ground that has been impacted
anthropogenically and a relatively pristine control ground. In Scotland, Alicante and
Malta, impacts to maerl habitats derive mainly from the use of towed demersal fishing
gears. In the Ria de Vigo (Galicia), the major impacts derive from organic matter falling
from moored rafts used in the culture of the edible mussel. In the Bay of Brest
(Brittany), maerl beds are also affected by high nutrient and sediment loadings due to
eutrophication. Another pair of sites in Brittany (in the Glenan archipelago) are being
compared to assess the impact of maerl extraction practices.
The BIOMAERL programme, when complete, will provide the first biogeographical inventory
of macrofaunal and floral species in European seas, including identification of key
species, their population structure and an analysis of their functional significance in
this ecosystem. Assessment of the different anthropogenic threats to this biodiversity
experienced over the range of sites considered will generate recommendations as to the
most effective management strategies for this sensitive habitat.
The BIOMAERL team propose that one way to advance maerl conservation is the
establishment of an Environmental Quality Standard for European maerl grounds which is
capable of containing, and integrating, all the pertinent structural and functional
aspects of the habitat revealed by their studies. They suggest that this might be
achievable by allocating a point score to each of the following indicators: edaphic
complexity (sediment stratification), basic energy resources (% organic matter, %
epifauna/infauna, % macrodetritivores), complex trophic interactions (% predators, %
microdetritivores). A summated score would then represent the overall biodiversity status
of a particular maerl bed. Such an index would be capable of being monitored over time to
provide a check on environmental change, especially any deterioration. It would also
supply a mappable, objectively-derived descriptor that, by virtue of being independent of
species composition, would be capable of direct comparison at a pan-European scale.