WetlandsRohe kōreporepo

New Zealand has lost 90% of its original wetland area, with large areas of former wetland on flat plains and in valleys drained for use as towns, roads and farmland. The loss has been even more pronounced in Hawke’s Bay, with only 4% of our original wetlands remaining, making them one of the rarest and most threatened ecosystems in the region. Many of our remaining wetlands are heavily modified and under a range of pressures, particularly from pest plant invasion.

Wetlands have important functions and many efforts are being made in Hawke’s Bay to protect and enhance existing wetlands, restore those that have been neglected and create new ones.

The main wetlands in Hawke’s Bay are:

Coastal (lagoons & estuaries) - Whakaki Lagoon, Ahuriri Estuary, Tukituki Estuary, Waitangi Estuary, Whakamahi/Whakamahia Lagoons. 

Freshwater (swamps, lake margins) -  Pekapeka, Lake Whatuma, Lake Runanga, Lake Oingo.

There are many other smaller wetlands on public and private land. Some of these wetlands can be dry at certain times of year, and identification can be tricky as no two wetlands are the same! The process to identify a wetland relies on vegetation, soil and hydrology assessments and may require specialist help.

Why wetlands are important

Wetlands form a critical boundary between land and water.  In Hawke’s Bay we have examples of many types of wetlands. The types of plants and animals found in wetlands vary depending on whether it is coastal or freshwater, how much water flows in and out, how long it stays there, how deep the water is, how warm it gets and what nutrients and sediment are in it. 

Wetlands are important because they:

• are culturally valued, as Maori regard these places as taonga, and of great significance. They once contained many wahi tapu sites, and any work in these areas still needs guidance on their historical protection.  Wetlands can still be food sources and once were transport corridors, provided building supplies and contained many pa sites.
• store floodwaters – just like giant sponges, wetland plants slow the flow of water off the land, soak up excess floodwater, and then slowly release it to maintain summer water flows in streams.
• improve water quality - the plants trap sediment suspended in water, making the water cleaner. Alongside rivers, roots hold bank soils together, reducing erosion and further sediment entering water. Bacteria living in wetland soils absorb and break down nitrogen and other nutrients from farm run-off and leaching, improving water quality.  
• are habitats for a diverse range of plants and animals, many of them rare and threatened species. Wetlands can be important breeding sites and nurseries for young fish and birds.
• are sinks for excess carbon, implicated in potential global warming, especially peaty wetlands like Lake Poukawa.

What we are doing about wetlands in Hawke’s Bay

Volunteers - It’s exciting that in Hawke’s Bay, many hundreds of people care about wetlands and volunteer to help dig, plant and weed wetlands.  We could not restore these ecological areas without their valued help! Many people continue to monitor changes in their wetland projects, and form permanent care groups, such as at Whangawehi at Māhia.

The Regional Council has an important monitoring and research role.  We undertake State of the Environment wetland monitoring to understand the state of wetlands across the region. We are collecting ecological information to better understand the flora and fauna, nutrient status and hydrology of these areas. 

The Regional Council has enhancement and maintenance programmes for wetlands for which we have responsibility at Tūtira, Pekapeka, Taipo, and Waitangi.  We also work with landowners through our Priority Ecosystem programme to enhance biodiversity in prioritised wetlands on private land.

More info?

There is more information on types of wetlands and restoration on the National Wetland Trust of NZ and Science Learning Hub pages.

DairyNZ and NIWA have published Constructed Wetland Practitioner Guidelines. You can find a copy here: wetland_practitioner_guide_web_may_2022.pdf (dairynz.co.nz)

Napier City Council has plans to improve Ahuriri Estuary, its surrounds, public use and the quality of stormwater entering the estuary environment from the city.

Napier City Council stormwater system

International wetlands and World Wetland Day