Healthy Estuaries

Ki Uta Ki Tai

Assessing the interactions between loadings of different contaminants from freshwaters on the health and functioning of estuaries

Spid Pye, Truestock

Project Details Ngā taipitopito

Project Status:
Challenge funding:
$512,000 + co-funding
Research duration:
September 2021 – September 2023

Collaborators Ngā haumi

Auckland Council | Cawthron Institute | Department of Conservation | Integrated Kaipara Harbour Management Group | Kitson Consulting | Land Water People | Manaaki Whenua Landcare Research | Ministry for the Environment | MPI | MUSA Environmental | NIWA | Sustainable Seas Challenge | Te Ao Mārama Inc (Ngai Tahu ki Murihiku) | Te Rūnanga ō Ngāti Whakahemo | University Of Otago | University Of Waikato

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What are we doing?E aha ana mātou?

The health and functioning of estuaries are affected by contaminants from freshwater. These contaminants interact with each other, causing cumulative effects that can be difficult to predict. The National Policy Statement for Freshwater Management does not yet include how to assess the interactions of contaminants.

We are working with Sustainable Seas, in partnership with the Ministry for the Environment (MfE), to address this gap.

In case study estuaries, Māori researchers will work with whānau, hapū, iwi and local community groups to identify aspirations for their estuary, and present uses and stressors.

Our Land and Water researchers will estimate freshwater contaminant loads to New Zealand estuaries historically, now, and under a changed climate. Sustainable Seas will then combine the data with information on estuarine ecology to determine critical stressor thresholds and buffers that take into account the stressors’ cumulative effects, mātauranga Māori, and locally informed objectives. These critical stressor thresholds will be used to establish limits for freshwater contaminants.

Our Land and Water will then assess whether implementing different land management options can meet the proposed limits – now, by 2050, or by 2100.

How can the research be used? Ka pēhea e whai take ai te rangahau?

  • Informed by mātauranga Māori, this mahi will identify contaminant thresholds required to restore the ecological structure and function, and the mauri of estuaries.
  • The research will assess the impact of identified contaminant thresholds on catchment land use, and whether thresholds can be achieved considering realistic land-management options.
  • Health indices and tohu will be identified to inform the management priorities for enhancing estuarine functionality and its mauri.

Participation & engagement Te hunga i whai wāhi mai

  • Research will focus on the Kaipara, Waihi and New River estuaries. These case studies represent different estuary types and sizes with different surrounding land uses and climates.
  • The collaboration with the Ministry for the Environment is a critical part of extending this research nationally. This will include spatial and temporal ecological analyses in 12 estuaries nationwide, and landcover and freshwater input assessments for over 200 estuarine systems all around New Zealand.

Research team Te hunga i whai wāhi mai

Science Lead
Alex Herzig
Manaaki Whenua Landcare Research
Programme Co-ordinator
Anne-Maree Schwarz
Andrew Neverman
Manaaki Whenua Landcare Research
John Dymond
Manaaki Whenua Landcare Research
Sandy Elliot
Ton Snelder
Land Water People
Shaun Awatere
Manaaki Whenua Landcare Research
Kura Paul-Burke
Ngāti Awa, Ngāti Whakahemo
MUSA Environmental
Jane Kitson
Kitson Consulting
Conrad Pilditch
University of Waikato
Richard Bulmer
University of Waikato
Candida Savage
University of Otago
Dana Clark
Cawthron Institute
Patricia Clark

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