Damage continued

  
Eutrophication

The enrichment of water by nutrients, is considered to be the biggest threat to water quality in Northern Ireland mainly due to the release of nutrients (animal waste, fertilizers, sewage) from the land. Excessive nutrients in a lake or other body of water can cause a dense growth of plant life; the decomposition of the plants depletes the supply of oxygen, leading to animal death. Phosphorus enrichment may stimulate growth of phytoplankton in freshwater systems and hence make the water more cloudy, the underwater climate becoming unfavourable for many submerged plants which gradually become excluded.
Eutrophication can result in the widespread replacement of important fen plant and reedbed communities and associated invertebrate species, with less demanding species of lower conservation value.

Fish farms

Fish farms on rivers usually abstract water from the river and then release waste back to the same watercourse. The temperature, pH and chemical composition of fish farm waste may differ from that of natural stream water. This can lead to increased oxygen demand (and hence a low oxygen concentration in the water), increased suspended solids, nutrient enrichment of the receiving waters and, consequently, major decreases in biodiversity.

Invasive species

Invasive species deliberately or accidentally introduced. Fish introductions can impact on the overall ecological status of a lake by significantly altering the food web. In addition, fish introductions can have specific impacts on the genetic integrity of established fish populations by cross-breeding with them, such as native populations of brown trout. The threats from introduced species are very complex.

Litter

Large quantities of flotsam, including plastics, cans, bottles, fuel and fallen animals are deposited each year all around the shores of Northern Ireland’s water bodies and along the watercourses that discharge into them. This is the result of a combination of deliberate and negligent actions. Flotsam can be aesthetically unpleasant, pose a hazard to watercraft and a source of infection and disease which is a direct hazard to wildlife and livestock.

Peat-cutting

Peat cutting for fuel has effected the character of many important fen sites. Although this has largely ceased, without appropriate management, the biodiversity associated with many sites will continue to deteriorate resulting in the loss of open water and more open fen habitats.

Recreation

Northern Ireland’s lakes have an important visual and aesthetic value and can also have considerable amenity value including bathing, fishing, shooting, boating and other water sports. Water-borne traffic can damage aquatic plants at the point of launch, or through bank-side wave erosion, passage through strands of vegetation, or the cutting action of propellers.

Water abstraction

All fish movements and migrations depend on adequate waterflow. The removal of water can also cause important wetland habitats, such as marshes and wet woodlands, to dry out.