The Kidneys of Zealandia Te Māra a Tāne

Written by Freya Bacon-Bootham

World Wetlands Day 2023. 

Kūkūwai/wetlands are either permanently or intermittently wet areas and an important taonga/treasure of Aotearoa. In the last 150 years, over 90% of Aotearoa’s kūkūwai have been lost. Much of this loss happened from the drainage of kūkūwai so that the areas could be used for agriculture.

The kūkūwai at Zealandia Te Māra a Tāne is manmade, as the valley’s history of dams and reservoirs created the opportunity for it to be formed. The water of this kūkūwai is fed through rainfall and the stream that flows into it, the Te Māhanga stream. Being a swamp kūkūwai, it hosts a rich supply of nutrients and sediments from a mixture of minerals and peat.

This kūkūwai is part of the Kaiwharawhara catchment, which starts at Zealandia Te Māra a Tāne. As part of the headwaters, this kūkūwai is a crucial part of the water quality of the entire catchment. Changes in the water quality here may impact the catchment further downstream as well.

Biodiversity

Kūkūwai host a great portion of Aotearoa’s biodiversity. The variable water levels allow kūkūwai to have a large diversity of plants. In Aotearoa, 30% of native manu/birds are kūkūwai species.

The kūkūwai in Zealandia Te Māra a Tāne is home to many plants. These plants perform a variety of roles, benefiting both species currently calling the sanctuary home and species that could return one day. Some of the plants and their benefits are listed here:

• • Toetoe are useful for wind shelter and erosion control. The bases of toetoe are ideal spawning habitats for the fish inanga/common galaxias. Traditionally the leaves have been used to make baskets and mats, to line the walls of a home, and to help with bleeding and diarrhoea.
• • Pūrei is an excellent source of food and shelter for ground manu, and pāteke have been spotted taking shelter underneath the leaves.
• • Tī kōuka/Cabbage tree is another ideal plant for erosion control. They are also home to berries that manu love, and their fallen leaves improve the soil. Māori used these trees for food, medicine, and marking pathways and important places due to their long life.
• • Marie Tawake/swamp maire berries are enjoyed by manu and tuna kuwharwharu/longfin eels. Māori used these berries as a natural dye and food source.
• • Harakeke/flax is not only loved by manu like tūī but is also a habitat for geckos, insects, and pekapeka. Traditionally used to make kete, whāriki/floor mats, kākahu/cloaks, and ropes.

Alongside the variety of plants, many others call the kūkūwai at Zealandia Te Māra a Tāne home. Four species of dragonflies and damselflies can be seen flying around the water and plants: the blue damselfly, common redcoat damselfly, ranger dragonfly, and yellow-spotted dragonfly. As the water quality improves in the valley, more of these species will be around to be spotted.

Cleanser

Kūkūwai are a vital part of maintaining a healthy ecosystem and often are referred to as the ‘kidneys of the earth’.

Water moves slowly through kūkūwai, allowing sediment and debris time to separate from the water and remain in the kūkūwai, rather than being washed downstream. When too much sediment and debris enter stream systems, they can create blockages causing streams to flood and breach their banks.

Kūkūwai plants are an important part of a kūkūwai cleansing abilities. These plants take up many nutrients in the water, cleansing it before it flows out of the kūkūwai. Kūkūwai plants are excellent trappers of nitrogen and phosphorus, nutrients which are associated with agricultural run-off. Without plants removing the excess nutrients in the water, the nutrients will encourage unwanted plant growth, such as algal bloom.

Climate Crisis

Kūkūwai are critical ecosystems when considering the climate crisis. They act as carbon sinks, storing large amounts of carbon dioxide. Yet, when kūkūwai are drained, this large amount of carbon is released. Before drainage, the kūkūwai is a low-oxygen area, which slows plant decay. When the land becomes well-oxygenated due to water being drained away, the plant decay is rapidly sped up, leading to large amounts of carbon being released into the atmosphere.

Drainage of kūkūwai also creates problems with the water table. The water table is the boundary between surface water and groundwater. When a kūkūwai is drained, the water table lowers, which decreases the quantity of groundwater available, reducing available drinking water.

In the face of increasingly extreme and variable weather patterns, kūkūwai are important flood defences. They decrease flooding through:

• • Trapping water and giving it time to drain
• • Restricting the amount of silt and debris entering streams and rivers

Caring for the kūkūwai throughout Aotearoa has long-reaching impacts beyond their borders. Their role as cleansers and hosts of biodiversity means that the kūkūwai in Zealandia Te Māra a Tāne impacts the entire Kaiwharawhara catchment. Getting involved in community restoration projects and celebrating World Wetlands Day on 2 February is a great way for you to help the kūkūwai of Aotearoa.

Image Credit: 1. Freya Bacon-Bootham | 2. Janice McKenna | 3. Steve-Attwood