Giant kelp project to boost NZ’s coastal ecosystems

Restoring critical coastal habitat by supporting the return of declining iconic kelp forests is the goal of an MBIE-funded University of Otago Marine Science project.

As the recipient of a three-year, $999,999 Smart Ideas Grant, the project will focus on restoring the giant kelp, macrocystis pyrifera, which supports many culturally, commercially and recreationally valuable fisheries and provides numerous ecosystem services along New Zealand’s coastlines.

Giant kelp, which can grow to more than 20m in length, is in global decline due to factors such as increasing ocean temperature, sediment and nutrient runoff, and indirect effects of fishing. 

Along Tasmania’s eastern coastal regions, observations and data indicate an average decline of 92 percent for giant kelp forests since 1940.

Loss of these habitats has direct implications for many associated fisheries such as pāua and crayfish, as well as the ecosystem services they provide, such as buffering coastal ecosystems against processes like ocean acidification.

While reductions on this scale haven’t yet been measured in New Zealand, research fellow for the project Dr Matthew Desmond says similar trends are inevitable as our coastal waters become warmer and additional stressors such as sediment runoff increase.

He says receiving the MBIE grant is recognition these coastal systems are being valued, and provides the chance to rebuild and buffer these valuable ecosystems and fisheries against future climate impacts.

“This is a really great opportunity to capture the current genetic and physiological diversity of New Zealand’s giant kelp strains while it still remains so that we can select the most climate change resilient ones for restoration work,” Desmond says.

Doctorate candidate Doung Lê is assessing the genetic diversity across different strains of giant kelp to help identify those that will perform best under predicted future conditions.

Lê is working with international experts in kelp-culturing from Australia and Chile, and will be applying this knowledge to genetically select for, and promote, climate resilience amongst existing and future kelp populations in New Zealand.

The project will develop the knowledge and infrastructure needed to begin restoring areas where kelp forests are in decline or have been lost, and will build on more than 15 years of kelp research in Otago. 

One coastal stretch of Otago that has experienced a marked decline in kelp habitat is the approximate 15km stretch from Taieri Mouth to Brighton, and is the focus of current master’s student Maddy Glover. 

As part of her research, Glover has interviewed more than 20 fishers and people who have collective knowledge of local kelp forest distribution back to the 1950s.

That knowledge will then be used to build a timeline of kelp distribution and decline, and inform underwater habitat surveys for the purpose of identifying areas suitable for kelp restoration. 

The PI of the Smart Ideas project, associate professor Chris Hepburn, says all these associated strands of work will not only help maintain and restore the values of the local coastal environments, but also importantly build tools that allow for local action to deal with climate change. 

Desmond says the project’s primary focus on habitat restoration, as the first critical step for fisheries restoration, symbolises the bottom-up approach taken with the project. 

“The restoration of critical habitat such as kelp forests is essential for achieving a healthy coastal ecosystem which can then support coastal fisheries and other ecosystem services that kelp forests provide.” 

The project will work closely with partners at Te Rūnanga o Ngāi Tahu, Pāua Industry Council, Otago Rock Lobster Association, and is supported by longstanding relationships and research partnerships such as Te Tiaki Mahinga Kai.   

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