Looking to the future for a low-lying wetland

Climate-change-induced sea level rise is happening. What will this mean for our low-lying wetlands? Will they get eroded away - releasing more carbon? Or will they grow at the same rate, and hold their ground? And what will this mean for the critters that live there? A team are investigating at an Otago wetland that might be the first in New Zealand to make this change.

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.

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…

Go to this episode on rnz.co.nz for more details