Iwi, scientists to study Hokianga Harbour silt threat

A GNS Science crew takes a sediment sample during an earlier research project. Photo / GNS Science

A Far North iwi hopes a $100,000 science grant will help improve understanding of how the Hokianga Harbour has changed since people arrived in the country — and what can be done to restore its health.

The study comes amid mounting concerns over the state of the harbour, where human activity, particularly deforestation, has led to species loss, poor water quality and high levels of siltation.

The funding was awarded to Crown-owned research institute GNS Science and Te Rarawa Anga Mua, a subsidiary of Te Rūnanga o Te Rarawa.

Geologist Dr Kyle Bland, of GNS Science, said the project would involve taking about half a dozen core samples from the harbour bottom, each 2-5m in length, by dropping a gravity sampler over the side of a boat. The scientists would be guided by iwi on the sampling locations.

The Hokianga Harbour's beauty belies its problems with sedimentation, caused by the wholesale logging of the area's kauri forests. Photo / supplied

The sediment samples would then be taken to Wellington for analysis, which would include dating the layers and profiling their chemical and physical properties.

Representatives of Te Rarawa Anga Mua would travel to the GNS Science lab in Wellington to take part in the analysis and gain experience in scientific methods.

Bland said that would help develop skills and increase the level of interest in science within the iwi.

''The cores are like a tape recorder of Earth's history. They will reveal the type of vegetation in the Hokianga area and how it has changed over the centuries. Scientists will be looking for the makeup of species, the rate of sediment input, and any abrupt changes,'' Bland said.

''The cores will also reveal the diversity of marine life and how it has changed. A detailed understanding of the harbour's history will help in the development of a sound plan to regenerate it.''

The project was expected to start in early summer with a hui in Hokianga.

Wendy Henwood, of Te Rarawa Anga Mua, said people's health could not be separated from the health of the whenua and its waterways.

"We're excited about this collaboration. It will promote interest in science and research of the Hokianga Harbour via the history gleaned from the sediment cores and mātauranga Māori," she said.

The Hokianga Harbour as seen from the air. Photo / Merv Ellis

Bland said he hoped to use the project's findings to secure funding for a larger research project to build a more comprehensive picture of sedimentation in the harbour.

Te Rarawa Anga Mua is a charitable trust which aims to advance the iwi's social, environmental, cultural and economic well-being.

Te Pūnaha Hihiko: Vision Mātauranga Capability Fund is administered by the Ministry of Business, Innovation and Employment and invests in programmes that aid Māori development.