Assessing marine ecosystems to improve management

Giant kelp and hordes of kina in Tory Channel. Credit: Nick Shears, University of Auckland

Sustainable Seas National Science Challenge researchers are hoping that marine health data gathered on a recent field trip to Queen Charlotte Sounds will support more integrated management of the ecosystem.

The team of researchers from the University of Auckland, University of Canterbury, University of Waikato and NIWA spent eight days in the Sounds sampling at more than 200 sites. They were investigating the ecological effects effects of fishing and sediment runoff from land, and looking for areas that might be suitable for restoration in the future. 

“We are working with the local community, to help them focus on shared goals and engage with management of the Sounds,” says Project Leader, Professor Simon Thrush from the University of Auckland. The researchers were joined during the survey by students from Te Ātiawa and Marlborough Girls' College.

“The techniques we are using are quick and cheap, but highly informative – we can interpret any changes based on our understanding of the whole ecosystem” explains Professor Thrush. “Of course we can do more intensive and expensive studies, but the key point here is we want to see how this data fits with the current management systems and help to advance new types of management to avoid problems caused by cumulative effects.”

The team noted that some areas of seafloor undisturbed by fishing were showing signs of recovery, with young horse mussels reestablishing and growing.

“We were saddened to discover that some previously identified areas of high biodiversity seemed to have disappeared. We feel this highlights the disconnect between scientific discovery, policy and implementing management actions,” continues Prof Thrush.

The team also recorded changes in rocky reef habitats. The number of sea urchins (kina) was much higher than anticipated and they were overgrazing and destroying seaweed beds. The excess of urchins is commonly a consequence of the removal of predators such as fish and crayfish. The team also speculate that giant kelp populations may have been further stressed by last year’s marine heat wave.

The team is now analysing the wealth of data gathered during the trip. Their findings will be shared with the local community in March 2019, and they are planning further trips to the Sounds to continue working with local managers, iwi and community groups to improve the ecological status of the Sounds.

“If we can build on local initiatives, like native forest regeneration and changes to local fishing regulations, we should be able to enhance the long-term value of the Sounds and build stronger resilience to the impacts of climate change,” continues Professor Thrush.

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