Eutrophic Standing Water - Hatchmere PEC
What are they?
Dense, green algae often turns our lakes, reservoirs and gravel pits green in mid-summer; if you can see to the bottom, the beds are covered by dark mud, rich in organic matter. Fish bubble at the surface, birds nest on rafts of twigs and damselflies alight on water-lilies.
These water bodies are known as ‘eutrophic standing waters’ because they are rich in minerals and organic content; as a result, wildlife is plentiful. However, many lowland water bodies in the UK are now heavily polluted, with nutrient concentrations far in excess of ordinary levels; in these cases, algal blooms reduce the amount of oxygen in the water to the detriment of other species.
Where are they found?
Eutrophic waters are most typical of hard water areas of the lowlands of southern and eastern UK, but they also occur in the north and west, especially near the coast. The total area of eutrophic standing water in the UK is estimated at 178,500 hectares.
Why are they important?
In their natural state, eutrophic waters are rich in wildlife – numerous species of invertebrate and fish are present, alongside important populations of wildfowl, amphibians and dragonflies.
Fennel-leaved pondweed and spiked water-milfoil are typical submerged plants of our lakes and reservoirs, while floating plants like yellow water-lily dot the surface with colour. This vegetation provides cover and shelter for a wide range of invertebrates from water snails to beetles. White-clawed crayfish also hide among the plants.
Our lakes and reservoirs are well-known for their fish populations. Coarse fish such as roach, tench and perch are typical of eutrophic waters, and salmon also occur in some areas. Amphibians such as the protected great crested newt, common toad and common frog are often present and may be hunted by herons standing by the water’s edge or voracious pike lurking beneath the surface.
The abundance of food can support internationally important bird populations. For example, Loch Leven in Scotland and Lough Neagh in Northern Ireland each support over 20,000 wildfowl including large numbers of wintering whooper swan. Loch Leven is nationally important for breeding ducks, such as wigeon, gadwall and shoveler, and Lough Neagh is important for breeding great crested grebe.
Are they threatened?
Eutrophic standing waters are under threat from pollution. Fertilisers used for agricultural production find their way into these waters and enrich them with nutrients to the extreme that plant and animal communities are damaged. Silts and sediments from agriculture and development can smother fish spawning sites and damage plantlife. These problems are made worse by the removal of waterside vegetation which acts as a barrier to pollutants.
Water abstraction, recreational activities like fishing and boating, and the introduction of invasive species have also had, and continue to have, detrimental effects on the wildlife of our lakes, reservoirs and gravel pits.
How are The Wildlife Trusts helping?
Restoration projects carried out by local Wildlife Trusts up and down the country are aiding our eutrophic standing waters by reinstating natural water levels, improving bankside vegetation and providing homes for rare species like water voles.
Working with landowners, anglers, politicians, statutory bodies and water companies to promote wildlife-friendly practices, The Wildlife Trusts are working towards a Living Landscape: a network of habitats and wildlife corridors across town and country, which are good for both wildlife and people.
What can I do to help?
- Take part in conservation measures on your land – ask your local Wildlife Trust for advice on managing eutrophic standing waters sympathetically.
- Provide a little space for nature in your garden by creating a wildlife pond – visit our Wild About Gardens website to find out how.
- Support the work of The Wildlife Trusts protecting and restoring wetland habitats across the UK – become a member of your local Wildlife Trust.
- Volunteer with your local Wildlife Trust and help your local wetland wildlife; you could be involved in everything from surveying for water vole signs to raising awareness about these vital habitats.