Scotland's Wildlife – an assessment of biodiversity in 20

7 Freshwater and wetland ecosystems 5
7.1 Habitat extent
On 1:50,000 scale maps, the river length is 100,000km and standing water bodies
(lochs) number 27,000. Scotland’s fresh waters are strong visual components in the
landscape. Covering about two per cent of Scotland’s land area, they represent some
70% of the total surface area of fresh water (90% of the volume) in the UK. The
interplay of weather, altitude, geology, soil type, landform and land use has resulted in a
diversity of fresh waters and associated assemblages of habitats and species. Of
international importance are: large concentration of deep, unpolluted lochs formed as a
result of glacial activity, often with wildlife communities characteristic of nutrient-poor
waters; extensive systems of blanket bog pools, which are globally rare, reflecting
distinctive climatic, topographic and hydrological conditions; unusual assemblages of
freshwater plants at the interface of North American and European species distributions;
several internationally rare invertebrate species, including glacial relicts with boreoalpine
distributions; existence, within the northern temperate zone, of relatively
unmodified and unpolluted river systems exhibiting natural physical, chemical and
biological changes along their length due to altitudinal and geological transitions.
Favourable conditions for hydro-power generation in Scotland – a wet climate and
mountainous terrain – have been exploited over the past century. A high voltage grid,
constructed in the early 1930s, made possible large-scale transmission of hydro-power.
Between 1945 and 1965, some 28 conventional hydro-schemes were constructed,
incorporating 66 dams. A characteristic of Scottish schemes is their extensive networks
of reservoirs, with aqueducts and tunnels for diverting water from neighbouring
catchments into the main storage reservoirs, augmenting power production and
accommodating seasonal variations in rainfall. By the mid-1960s, the economic
potential of catchments had been largely developed, although some pumped-storage
schemes were constructed thereafter to store and release energy surpluses from large
thermal and nuclear power stations. The changed economics of renewable energy has
given rise to the further development of hydro-power in Scotland. In December 2009,
hydro power contributed 42% of Scotland’s renewable energy, second only to wind
power. It has been estimated that this could be increased by 50 per cent, based on an
un-tapped potential for more than 1,000 new schemes across the country. Scotland's
biggest hydro electric scheme to be built in more than 50 years, at Glendoe above Loch
Ness, was opened in 2009.
According to the Countryside Survey, the number of ponds increased by 6% between
1998 and 2007. However, they represent only a small part of the overall extent of
standing open waters, which remained unchanged. The extent (width) of rivers and
streams is weather dependent, so little ecological significance can be attributed to the
3% increase between 1998 and 2007.
5 With thanks to the Scottish Environment Protection Agency (SEPA) for contributions to this section.
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