First devices installed in Te Moana a Toi to monitor estuaries

  • 27/10/2022

NIWA scientists have installed special devices in Te Moana a Toi (Bay of Plenty) coastal wetlands to monitor changes in elevation.

The regional council wants to see how its estuaries and saltmarshes might fare with rising seas and changing sediment flows.

So Toi Moana contracted NIWA scientists to install 12-rod surface elevation table (RSET) devices at Athenree and Ōhiwa.

They're some of the last unspoiled coastal marshlands in Aotearoa.

NIWA principal scientist Dr Andrew Swales spearheaded the project.

"The concept is really about saying can we offset the effects of climate warming and the costs of adaptation in the future through coastal wetland enhancement and restoration?" Dr Swales said.

He said estuaries and salt marshes buffer against erosion and flooding in prone areas, so we need to understand them better.

The RSET devices were previously used in 2007, in Tīkapa Moana Firth of Thames.

Toi Moana coastal catchments manager Pim de Monchy said they're trying to rejuvenate the region's lost marshlands.

"As well as protecting what's left, we're actively involved in trying to restore new wetland habitat back into some catchments," de Monchy said.

Drive 14 minutes east of Whakatāne PAK'nSAVE and you'll end up at Ōhiwa harbour.

It's been an important source of kai for local iwi Tūhoe, Ngāti Awa, and Te Whakatōhea for centuries.

"It's always been a food basket for our tribes, since mai rā anō." Te Whakatōhea iwi development manager Danny Paruru said.

Paruru said he supports the research because local iwi are experiencing things like more frequent floods, and reduced mussel and pipi beds.

"We are a low-lying area anyway. The Kutarere community, which sits at the southern end of Ōhiwa, is already seeing some impacts of climate change."

Helping communities adapt to the changing climate is a key part of NIWA's Future Coasts Aotearoa programme.

For wetlands to survive, they need to accumulate sediment at a faster rate than rising seas.

De Monchy says coastal wetlands are "right up there with tropical rainforests in terms of productivity". 

"They're one of the most valuable ecosystems that we have."

And as the sea rises, wetlands normally move inland uninhibited, but human infrastructure stops that - think railroads, stopbanks, and roads.

It's estimated some 90 percent of freshwater wetlands across the motu have been lost, partially because they've been converted to pastoral farmland.

"It's really universal. New Zealand has really nuked its wetlands, particularly freshwater wetlands" Dr Swales said.

It's hoped more monitoring devices will be installed over the next year in other regions.

A tool for coastal communities feeling the impacts of climate change today, to prepare them for tomorrow.