A wetland is an area of land which is covered in, or wetted by, water for most (but not necessarily all) of the time. Wetlands occur in areas where surface water collects or where groundwater seeps through to the surface. They include swamps, bogs, estuaries, coastal wetlands, lakes and some river edges.
Wetlands were once considered useless wastelands and often used as waste disposal sites or seen as potential pasture. Today however, we recognise that they are important and hugely diverse ecosystems – and that conserving and restoring them benefits not only wetland species, but also many other aspects of our environment and way of life.
Wetlands support processes which provide environmental services like water storage and flood control, nutrient removal, erosion control and water table maintenance.
Wetlands act as a giant sponge, helping to control water flow and water quality. Wetland plants slow the flow of water from the land when it rains. In summer, stored water is slowly released from wetlands, maintaining water flow.
Wetlands are the most productive places on Earth, providing an enormous food source for fish, birds and other animals. They absorb large amounts of water and nutrients from outside sources, and their microorganisms (fungi and bacteria) efficiently decompose and recycle nutrients.
Wetland areas have always been highly valued by Māori, featuring in the history and culture of our local iwi. Wetland plants including harakeke (flax) and raupo, are traditionally used for clothing, mats, medicine and dyes. Tuna (eels) and other wetland animals are a valuable source of food.
Most of New Zealand's wetlands were drained between 1920 and 1980 for pastoral land use. They have been reduced by about 85% and many remaining wetland areas are still under pressure from land development. Of those that are left, many are small and their natural character and habitat quality are degraded by partial drainage, damage by farm animals and weed invasion. Lowland wetlands have been mostly affected and are still at risk in some cases.
Wetlands now cover a very small percentage of New Zealand’s land area, but are home to 22% of our native land bird species. Wetlands support an immense variety of animals, some of which are very rare. Most of New Zealand’s wetland animals are not found anywhere else in the world. They include fernbirds, scaup, paradise shelducks, and giant kokopu.
Many of our wetland plant species are also not found anywhere else in the world. If wetlands are drained, and these unique plant communities are lost, they will be gone forever.
A brochure describing types of wetland in Marlborough and methods of protecting and restoring wetlands is available from the Council.