Select Committee on Environment, Transport and Regional Affairs Appendices to the Minutes of Evidence


Annex 1

THE SPECIAL WILDLIFE INTEREST OF CANALS

  Summary of designated areas:

  Sites of Special Scientific Interest (SSSIs): 83 SSSIs in England are associated with canals, approximately half of these are designated mainly for their aquatic plant interest. The others include canal reservoirs, bat roosts and land through which canals happen to run, including important geological exposures. British Waterways has responsibility for 67 SSSIs in England.

  Special Areas of Conservation (SAC's): Two candidate SAC's have been submitted to the European Commission under the 1992 Habitats Directive, these are Cannock Extension Canal and the Welsh section of the Montgomery Canal in Wales. A small section of the Rochdale Canal was proposed as a candidate SAC by Government in August 2000 and is currently the subject of a consultation exercise.

  Special Protection Areas (SPAs): Such areas are identified under the Birds Directive (79/409/EEC). Only one canal, the Pocklington Canal has SPA status.

WHY CANALS CAN PROVIDE A SUITABLE ENVIRONMENT FOR WILDLIFE

  Whilst the semi-natural habitats found in or by some of our richest rivers and lakes provide a haven for range of plant and animal species, canals despite their artificiality are nevertheless also very important. They are, in effect, very slow moving rivers and form important corridors for wildlife. Canals support a wide range of wildlife habitats from open water, through bankside to marginal wetlands.

  Open water is the most important habitat associated with canals and they can support a higher number of aquatic plant species than some of our best rivers and lakes of similar trophic status. The reasons for this are three-fold:

    —  Benign conditions: The canal environment is benign, there are no spate flows or wave-washed shorelines. The whole canal is a shallow-water habitat with potential for rooted aquatic plants to thrive. Such habitats are equivalent to a particular part of a lake or river.

    —  Water quality: In some canals water is sourced from springs or, for example, header reservoirs in the Pennines. Such water is often of a mesotrophic nutrient status of pH 6.0-7.0. In particular, total phosphorus levels may not exceed 35 µgl-1. Such mesotrophic conditions are the preferred environment for many plants and animals. This is not to say that canals are free from pollution. Much of the network is subject to eutrophication from sewage, industry or agriculture, and these sections are not generally suitable for a range of aquatic plants. What is important is that the headwaters of canal systems, side channels or remainder canals often contain plant species in abundance. These are now difficult to find in other lowland semi-natural open water habitats.

    —  Geographical Position: The third reason is that canals are low-lying and, with their low flow rates and high water temperatures in spring, provide for rapid growth of plants. Whilst some British lakes are mesotrophic, they are generally found in the uplands and are subject to climatic extremes which limit the number of species able to survive. Moreover, lakes in the lowlands are very often polluted by an excess of phosphorus, which through eutrophication leads to a loss in aquatic plant species.

IMPORTANT AQUATIC PLANTS

  The importance of aquatic plantlife in canals is recognised by British Waterways in A Framework for Waterway Wildlife Strategies (2000). It states "most of our canal SSSIs are designated because of water plants—having either an unusual variety of species or special rare ones. Some are designated for both reasons and their biodiversity importance can often complicate restoration projects".

Floating Water Plantain Luronium natans

  A species of international importance is floating water plantain, Luronium natans. It is listed for protection on Annex 2 of the Habitats Directive. Its distribution within the European Union is centred on Britain. Whilst lakes such as Derwent Water contain between 1,000 and 2,000 individual plants and in some exposed lakes in Wales their numbers may be reduced to a few hundred, the Rochdale canal and Montgomery canal in Wales each contain in the best stretches several hundred thousand plants per kilometre. These must be the densest populations in Europe, and their conservation and the maintenance of such population is a special challenge to British Waterways in the restoration of navigation to these canals.

Pondweeds

  The pondweeds (Potamogeton spp) are a particularly important group of aquatic plants. Canals support abundant growths of the species in the table below, many of which are of limited distribution in England or are nationally scarce or rare.

  Of the 21 true species of Potamogeton 15 species are found in canals. Two of these are nationally rare. Grass-wrack pondweed would be rare in Britain were it not for the canal system holding dense populations of this nationally scarce species, notably in the Rochdale, Ashton and Montgomery Canal. Similarly, canals hold notable populations of the uncommon or local species of various-leaved pondweed, red pondweed, long-stalked pondweed, flat-stalked pondweed and hair-like pondweed. Of the 15 species of pondweed found in the canal system, five are commonplace species. The distribution of the 10 remaining species—almost half of the group— would be very limited in Britain were it not for canals.

POTAMOGETON SPECIES FOUND IN CANALS

Common name
Latin name
Status
Broad-leaved pondweedPotamogeton natans Commonplace throughout Britain.
Shining pondweedPotamogeton lucens Common in England and Wales.
Various-leaved pondweedPotamogeton gramineus Frequent in Scotland. Local in England and Wales.
Red pondweedPotamogeton alpinus Frequent in Scotland. Local in England and Wales.
Long-stalked pondweedPotamogeton praelingus Very scarce in England and Wales. Scarce in Scotland.
Perfoliate pondweedPotamogeton perfoliatus Commonplace throughout Britain.
American pondweedPotamogeton epihydrus Nationally rare, one record in South Uist, Outer Hebrides. Introduced from seeds in cotton bales imported from USA to Lancashire in 19th Century. Abundant in two canals.
Flat-stalked pondweedPotamogeton friesii Frequent to near scarce throughout Britain.
Blunt-leaved pondweedPotamogeton obtusifolius Freqent in Scotland, N England. Local in lowlands of England and Wales.
Small pondweedPotamogeton berchtoldii Frequent throughout Britain.
Hairlike pondweedPotamogeton trichoides Close to being nationally scarce.
Grass-wrack pondweedPotamogeton compressus Close to being nationally rare, nationally scarce.
Sharp-leaved pondweedPotamogeton acutifolius Nationally rare. Extinct (?) from two canal sites.
Curled pondweedPotamogeton crispus Commonplace throughout British lowlands.
Fennel pondweedPotamogeton pectinatus Commonplace throughout British lowlands.


  A nationally rare species is found in 15 or less 10x10 km squares in Britain.

  A nationally scarce species is found in 16-100 10x10 km squares.

  There are 2,400 10x10 km squares in Britain.

Other plants of local distribution

  These include frog-bit Hydrocharis morsus-ranae, flowering rush Butomus umbellatus and fringed water lily Nymphoides peltata.

DRAGONFLIES

  38 species of dragonfly are known to breed in Britain. 20 species have been recorded from canals, but not all of these breed in canals. The club-tailed dragonfly Gomphus vulgatissimus, the white-legged damselfly Platycnemis pennipes and the red-eyed damselfly Erythromma najas are three important species known to breed in canals.

WHITE-CLAWED CRAYFISH

  Once common, our native crayfish is now a protected species under the Wildlife and Countryside Act (1981). Canals have become an important haven, and their importance has only recently become apparent. Individuals numbering several thousand have been found in the stoned canal sides during restoration work on the Huddersfield Narrow Canal. Special provisions have been made to safeguard them, and new habitats have been provided.

AMPHIBIANS

  Great crested newt is a protected species under the Wildlife and Countryside Act 1981 and the EU Habitats Directive. It is quite rare in the canal network, and there are no candidate SACs identified. Smooth and palmate newts also breed in or by canals, and frogs and toads breed in quiet back waters on the canal network.

MAMMALS

  Water voles are a protected species and are recognised as a priority species under the Biodiversity UK programme. Canals with soft banks and fringing habitats support good populations. Otters use canal corridors, and canals have an important role in providing a dispersal corridor. Bats are nocturnal users of canal corridors for feeding on flying insects. They use canal-side trees and canal tunnels to roost or hibernate in. One site, the Greywell Tunnel on the Basingstoke Canal SSSI in Hampshire (a local-authority owned canal) has one of the largest bat hibernating sites in northern Europe.


 
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