Freshwater Habitats

Whether a freshwater habitat is a water body or a wetland, they are all sensitive to human impact and require management and protection. NIEA have produced Habitat Action Plans (HAPs) that describe the steps that need to be taken to protect these important and fragile environments.

Rivers

Rivers always flow downhill transporting water through our countryside.
Rivers are dynamic systems that are constantly moving and changing, transporting and depositing sediment. The physical structures that result from these active processes and sediment placement are vitally important for wildlife, providing a range of areas for plants and animals to grow, feed or spawn. Waterfalls and gorges, for example, are often very rich in mosses and liverworts because of the damp, humid conditions, while some shingle banks support unique animal communities. Such physical features add considerably to the diversity of rivers and streams.

The best rivers - in terms of water quality and natural form – therefore contain a wide range of plants and animals. The major river of Northern Ireland is the Bann, which rises in the Mourne Mountains and flows northward through Lough Neagh to become a wide and navigable waterway to the sea.

Eutrophic Standing Waters and Mesotrophic lakes

Eutrophic standing waters (.PDF 130.6Kb) tend to occur in lowland areas and include most of the large lakes. They have a high level of nitrates and phosphorous nutrients that often lead to algal blooms, which cloud the water, depriving aquatic plants of light and under extreme circumstances lead to the de-oxygenation of the system. The two largest eutrophic standing waters in Northern Ireland are Lough Neagh and Upper Lough Erne. Lough Neagh provides water for approximately one third of the population of Northern Ireland.
Mesotrophic lakes are characterised by having a narrow range of nutrients, and tend to be highly sensitive to small increases in nutrient levels.

The two largest mesotrophic lake sites in Northern Ireland are Lough Melvin and Upper Lough Macnean, both of which straddle the boarder with the Republic of Ireland.

Marl Lakes

Marl lake (.PDF 123.5Kb) are nutrient and oxygen poor and are characterised by clear water, deposits of calcium phosphate (marl) and charophytes (algae that contain calcium deposits within them). All marl lakes are low altitude, natural lakes. Many lie in inter-drumlin basins receiving water as run off from the drumlin slopes and are also fed by springs and seepage zones, or by inflowing streams. Marl lakes are mainly distributed in the west and north of Britain and Ireland, with a major concentration in south-east Fermanagh, the largest being Lough Inver.