Geoscience Reference
In-Depth Information
pearl mussel populations in north-west Russia have
disappeared following large-scale hydro-electric
schemes.
Warmer, drier summers predicted under the
high scenario are likely to result in changes to
the way water is managed, exacerbating climate
change impacts. Increasing demand for potable
water is likely to result in higher demands for water
abstraction from Scottish rivers and lakes. Little
research into the ecological effects of abstractions
in Scotland has been undertaken. However, work
on abstractions in the River Spey Special Area
of Conservation (SAC), which holds the largest
population of freshwater pearl mussels in Great
Britain, has been published recently (EnviroCentre,
2008). It showed that up to 20% of the mean
annual water flow to the River Spey was being
abstracted or transferred out of the catchment and
recommended that measures be put in place to
maximize the management of the existing flows
before any new proposals were considered. Since
publication, further large-scale abstractions have
been granted licences and there are concerns
that resultant lower water flows will have an
adverse impact on the ecology of the River Spey
SAC and the species within it, including Atlantic
salmon, sea/brown trout and freshwater pearl
mussels. Therefore, a review of existing and new
abstraction licences within important freshwater
pearl mussel catchments is recommended to inform
the planning process, as the implications (for
example) in extreme drought conditions are likely
to be highly significant.
particularly likely to be sensitive and therefore
vulnerable to climate change.
In the next 20 years, river managers need
to change their general approach and consider
how to integrate the specific requirements of
endangered aquatic species, such as freshwater
pearl mussels as well as humans living in the
same catchments. This will require changes to
river/catchment management and it is important to
recognize that this may involve difficult decisions
and choices. Little research has looked at how
aquatic conservation and climate change issues
interact or how human responses should be co-
ordinated and developed. In doing so we consider
that the main issues for freshwater pearl mussels
are likely to be:
Implementation of conservation work for host
salmonid populations.
Appropriate management of woodlands and
the strong encouragement of appropriate
broadleaved planting in catchments devoid of
riparian woodland.
Tight control of river engineering activities and
full assessment and consideration of the likely
ecological effects of present and future pressures,
e.g. abstraction licences, hydro-electric power
generation, etc.
A presumption in favour of 'soft' river
engineering flood defence works in important
pearl mussel catchments.
Recognition that some pearl mussel populations
may be lost regardless of effort and therefore
scarce conservation resources should perhaps be
best directed at catchments with upstream lakes
and evidence of recent pearl mussel recruitment as
these populations are the most likely to persist in
the long term.
Success in these endeavours is likely to lie in
developing sustainable catchment management
schemes that demonstrably provide multiple
benefits to humans and freshwater pearl mussels.
Conclusions
The case study of the freshwater pearl mussel
in Scotland is one example of how extreme
climate change scenarios are likely to affect
an endangered river species. As has been
demonstrated, the potential effects of different
elements of predicted climate change are complex
and often contradictory. On a global scale, the
freshwater mussels (Unionacea) are a highly
threatened group (Bauer and Wachtler, 2001) and
their conservation status, complex life histories
and specific habitat requirements suggest they are
References
Anon (1993) Problems with sea trout and salmon in the
Western Highlands. Atlantic Salmon Trust, Pitlochry.
