Black coral in Fiordland. Photo: Supplied / Matteo Collina
Scientists are testing Fiordland's black corals against heat waves in the lab to see if they can survive the effects of climate change.
Marine heatwaves are becoming more intense, and this is New Zealand's first experiment on how the species could cope.
Victoria University marine biologist Professor James Bell recently took part in an expedition to collect and examine black corals in Fiordland - some of which are hundreds of years old.
"The fact that they live so long makes them a good kind of environmental indicator of disturbance generally," he told Morning Report on Monday.
"So if we know that there are areas where there should be these black corals and the black corals aren't there, it probably means that they've experienced some disturbance over time, so they're a kind of good indicator species."
Black corals are actually white, he said, the name coming from the colour of their skeleton.
With permission from the Department of Conservation - which took some wrangling - and the use of an underwater drone, Bell and his team collected about 120 corals (out of millions) to look at closely in the lab.
The advantage they had in Fiordland is that corals there grow as close as five metres to the surface.
"One of the cool things about Fiordland is that normally all black corals occur in really deep waters - in Fiordland they occur up to 5m, but down to kind of 100m, so we can collect them via scuba divers and also with a drone."
A worker with some of the samples in the lab at Victoria University. Photo: Supplied / Matteo Collina
Last year, a study of marine sponges found global temperature rises may have already exceeded 1.5C.
And a heatwave in 2022 caused "wide-scale" bleaching of sponges in the Fiordland region, Bell told RNZ at the time.
Black coral in Fiordland. Photo: Supplied / Matteo Collina
The latest trip, aboard the Department of Conservation vessel the Southern Winds, was undertaken in "really warm" weather - great for them, but not so much for the corals.
"We brought back some of these black corals to our lab and we're running a simulated marine heatwave experiment… and we're slowly heating them up, and we should know in a couple of months how they respond to these marine heatwaves and warmer marine heatwaves in the future."
Some of the samples in the lab. Photo: Supplied / Matteo Collina
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