Dr Chris Kavazos takes water measurements at the wetlands. Photo: Claire Concannon / RNZ
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From Lake Waihola, not far south of Ōtepoti Dunedin, fingers of water run down the plains, converging with the Waipori river coming from Lake Waipori.
Dr Chris Kavazos, a freshwater technical advisor for the Department of Conservation, stands in one of these fingers. Waders on, he rummages in the muddy bottom for a logging device that has sat there for the last four months.
Tracking the change
In that time, the device has been taking measurements of pressure and conductivity every ten minutes. From here, the water will complete its journey by joining the Waipori River, which connects with the Taiari (Taieri) river, and then empties into the ocean ten kilometres away.
But it’s not just a one-way trip.
The area is extremely low-lying, just centimetres above sea level. Despite the distance from the coast, these waters experience tidal changes, and influxes of sea water. By measuring tiny pressure changes that equate to water depth, plus a conductivity reading that gives an indication of salinity, these logging devices are tracking the impacts of rising tides on these inland wetland areas.
Dr Chris Kavazos from the Department of Conservation with the water gauge. Photo: Claire Concannon / RNZ
As sea levels rise – a result of human-induced climate change – these wetlands might be the first in New Zealand to experience significant impacts. Chris and others are keen to understand what it might mean for the area, and its inhabitants.
The Waipori–Waihola wetland complex
From a map the approximately 2,500-hectare Waipori–Waihola wetland complex is easy to spot.
Two lakes mark the north and south boundaries. The darker patches of lagoons, pools, swampy areas and meandering channels that connect them are easy to distinguish from the bright green rectangles of cultivated land that form the borders.
And off a gravel road on the inland side of the wetland complex is a small collection of buildings – an office, accommodation, equipment sheds and a native plant nursery – this is the working space of Te Nohoaka o Tukiauau Trust.
Te Nohoaka o Tukiauau, also known as Sinclair Wetlands, is 315 hectares of this larger wetland complex that was was returned to Ngāi Tahu as part of the 1998 Ngāi Tahu Claim Settlement Act – compensation for the loss of the Lake Tatawai Māori fishing reserve, which was drained in the 1920s.
Dr Chris Kavazos and Māori cultural advisor Tumai Cassidy. Photo: Claire Concannon / RNZ
The whole wetland complex is probably less than a third of its original size, says Tumai Cassidy, of Te Rūnanga o Ōtākou, a member of Te Nohoaka o Tukiauau Trust. Drainage and clearing, changing land use, the installing of flood protection banks that constrain the wetland, urban development, wastewater discharge, and introduction of non-native plants and animals have all impacted, and continue to impact, the original ecosystem.
Despite this, it remains an important habitat for native flora and fauna – in particular, for wetland bird species, tuna (longfin and shortfin eels), kanakana (lamprey), and galaxiid fish species (such as giant kōkopu and īnanga).
Traditionally, and today, it’s an important mahinga kai (food gathering) area for Ngāi Tahu. Tumai, the Trust, and others, are working towards restoring it as fully as possible.
The work of restoration
At the hub that is the base for Te Nohoaka o Tukiauau, Paul Pope, programme manager for Te Nukuroa o Matamata Jobs for Nature project, points out the 2,000 kahikatea trees the nursery has grown, ready to plant out.
A Te Rūnanga o Ōtākou project, Te Nukuroa o Matamata has been operating for the last three years – upskilling people in how to remove weeds, plant natives, and control pests. They’ve been operating not just in Te Nohoaka o Tukiauau, but also in the wider wetland area.
Paul Pope at Te Nohoaka o Tukiauau native plant nursery. Photo: Claire Concannon / RNZ
A short drive down a gravel road, Paul points out an area of privately owned wetland that they’ve been operating in. Working with the landowner they’ve fenced off a portion of the wetland, killed willow that were lining an important stream for giant kōkopu, and are now planting out a section.
It will take time, but all this effort gives the native plants and animals a fighting chance, and the wetland ecosystem in general more resilience for what’s to come.
The wider picture
Chris wants to use the data he is gathering to ask specific questions about how these wetlands will look in the future. Will increasing tidal impacts erode them away, releasing more carbon? How far upstream will the important spawning sites for īnanga move? Will it change to a salt marsh ecosystem?
Dr Chris Kavazos by Lake Waihola. Photo: Claire Concannon / RNZ
But zooming out from the wetland complex, the bigger picture is the entire Taiari river catchment.
As part of the Ngā Awa DOC river restoration programme, Chris and others have also been investigating what will happen across the whole of the Taiari catchment as the climate changes.
Listen to the podcast to hear from Chris, Tumai and Paul about the species found in the area, the challenges the wetlands face, their restoration efforts, and their hopes for the future.
Learn more
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In a Waikato peat lake wetland system, a team is struggling with an unusual pest problem – half a million starlings and sparrows.
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Our Changing World has previously covered the work of Te Nohoaka o Tukiauau in relation to conservation translocations.
