Napier estuary part of NIWA research project into contaminants

Te Whanganui-a-Orotu (Ahuriri Estuary) will be part of a NIWA study into contaminants that may help to guide future policy setting for central and local government. Photo / NZME

Te Whanganui-a-Orotu (Ahuriri Estuary) will be part of a study into contaminants that may help guide future policy settings for central and local government.

The National Institute of Water and Atmospheric Research is conducting a two-year study, Ki uta ki tai: Estuaries, thresholds and values, on 12 estuaries with a focus on the type and quantity of contaminants each estuary is receiving from rivers and streams.

The joint initiative is funded by two National Science challenges, Sustainable Seas and Our Land & Water, and the Ministry for the Environment.

A NIWA statement said the research is to address local councils' need for guidance in their efforts in developing coastal environmental plans to comply with New Zealand's National Policy Statement for Freshwater Management.

"Estuaries are an integral part of the coastal environment, but the policy for freshwater management does not yet include a clear direction on how to assess the health of estuaries."

Estuaries are coastal water bodies where freshwater mixes with seawater.

Project lead Drew Lohrer, marine ecology specialist, said most local councils were aware of the contaminants running off land and into fresh water and eventually estuaries, but this research would explore the health of each part of an estuary.

"Not all the different parts of the estuary may be equally susceptible or equally exposed to these contaminants.

"That's really what we are trying to explore, just to have a bit more nuance and understanding of the exposure of particular parts of the estuary to contaminants and how that affects the health of the estuary and resources."

He said the process involved taking data collected by Hawke's Bay Regional Council on soft sediment, macrofauna assemblages (type of fauna) and kaimoana abundance across different sites in Ahuriri Estuary.

"Different species have different sensitivities to the contaminants. So when they change, the composition of the assemblage changes, and we can understand the responses to the contaminants."

He said the research will incorporate mātauranga Māori and western science to take a holistic approach in keeping with the ki uta ki tai concept.

He said they weren't setting any policy through their research but they aimed to help councils with decision-making.

"We're basically trying to provide good evidence and information ahead of when councils need to make some changes to their coastal plans."

The NIWA statement said the findings will be used to guide limit-setting for freshwater contaminants in estuaries which the ministry can use to set policy for regional councils to follow.

The final phase of the estuary research is expected to be complete around September 2023.