How to deal with unwelcome visitors. Katy Gosset learns about a native fungus that might help in the battle against wilding pines. And two national research programmes combine on an expedition to protect our oceans from plastics and invasive species.

Invasive species in Aotearoa are the unwelcome guests who have taken over, made a mess, and just won't leave. Plants that smother ecosystems, seaweeds that take over ocean floor habitats, insects, fungi and bacteria that harm native species. Not only that, but others are constantly knocking on the door. This week, stories on keeping them out, and keeping them in check.

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Pine-fighting fungus

New research has shown a native fungus could help slow the spread of invasive wilding pines.

Conservationists estimate that these weeds now cover 1.8 million hectares of land across New Zealand and the Ministry of Primary Industries forecasts that as much as 20 percent of New Zealand could be covered by unwanted conifers in as little as 20 years. The cost? Around $100 million annually in lost productivity, irrigation, hydro-electric power and fire control. And if the wilding pines continue to spread the cost to our economy could reach into the billions.

Katy Gosset meets a Canterbury Masters student who hopes to halt the pines' progress by innoculating the felled trees with armillaria fungus.

Keeping an eye on the oceans

Unwelcome visitors from the ocean include both invasive species and plastic pollution; keeping both at bay is a massive job.

Two national collaborative research programmes are trying to tackle these issues - the AIM2 (Aotearoa Impacts and Mitigation of Microplastics) project and the Marine Biosecurity Toolbox programme. Both involve large teams of scientists from multiple organisations.

In 2021 these research programmes came together on two expeditions coordinated by the Blue Cradle Foundation to gather biosecurity and microplastics data, first in the Hauraki Gulf and then in Fiordland.

Collaboration and data sharing between the two teams is key, as plastic rafts could act as vehicles for invasive species to arrive in the waters around Aotearoa. Scientists across the two projects are working to identify what different organisms tend to interact with different kinds of plastic so that they can make predictions about what threats the marine environment might face.

Listen to how the researchers sample for plastics, and use environmental DNA methods to survey for biosecurity threats in the Hauraki Gulf…

Go to this episode on rnz.co.nz for more details