Rocky reefs in Kalbarri, Western Australia before (left) and after (right) the 2011 marine heatwave, which wiped out extensive underwater kelp forests. All images supplied by Thomas Wernberg.
You’ve likely heard about how the Great Barrier Reef is dying. Yet on the other side of the country another reef is suffering pretty badly too. And as in Queensland, the problem for the Great Southern Reef is warming waters.
See the kelp forests of the Great Southern Reef need cool temperatures to survive, but as climate change makes global El Niño events more prevalent, the underwater plants are struggling to cope. A massive heatwave in 2011 saw ocean temperatures off the coast of Western Australia increase by three to four degrees above their normal maximum. The reef is yet to recover.
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Marine Scientist Thomas Wernberg, from the University of Western Australia, has dedicated years of research to the plight of the Great Southern Reef. He co-authored a study, published last week, which highlights how dire the situation has become.
“We compiled data on the reef over a 15 year period,” Wernberg told VICE. “After the 2011 marine heatwave, we basically saw all of the kelp forest disappear from Kalbarri to Port Gregory, then from Gregory down to Perth there was substantial damage too.” That’s over 100 kilometres worth of kelp.
But rising sea temperatures isn’t the Great Southern Reef’s only concern. As one of Australia’s least-known biodiversity hotspots, it also faces some serious PR problem. Nobody seems to have heard of it.
The Great Southern Reef covers 70,000 square kilometres. It contributes billions to Australia’s tourism and fishing industries each year, and is dying at a rate comparable to the decomposing corals of the Great Barrier.
“If you look at reef related media exposure, coral reefs get 80 to 90 percent more coverage than temperate reefs and kelp forests,” Wernberg explained. “We very much believe the Great Southern Reef is under appreciated. There’s an imbalance in media exposure, and a lot of that is founded in a lack of understanding.”
Unfortunately, making Australia love kelp is also a tough sell. Coral, as featured in Finding Nemo, is colourful, highly textured, and fun to look at from a glass bottom boat. Kelp, on the other hand, is essentially just seaweed. Even if it’s very important seaweed that helps feed populations of rare fish found nowhere else in the world.
This is what healthy kelp looks like.
“The whole Great Southern Reef that we’ve defined extends north of Perth, all the way to Sydney via Tasmania,” Wernberg said. “So it’s a massively long reef system, and it’s defined by kelp forest which acts in the same way as coral—sustaining populations of dependent species.”
Ordinarily, these kelp forests can bounce back from extreme weather incidents like the 2011 heatwave. However, El Niño events are becoming all too common. The warmer waters have brought with them populations of very hungry tropical fish, which wouldn’t normally inhabit these temperate regions.
“When you suddenly have too many hungry fish arriving, they eat everything and kelp is unable to recover,” Wernberg told VICE.
Kelp forests provide homes and food for a host of rare native marine species, so when they start dying the flow on effects are immediate. The Great Southern Reef is home to some of the most unique biodiversity in the world. “Between 30 and 80 percent of all species are found only on the Great Southern Reef, and nowhere else,” said Wernberg.
Native harlequin fish are among the species worst affected by kelp death.
The Great Southern Reef also props up Australia’s rock lobster and abalone fishery industries—worth around $375 million and $135 million each year, respectively. That’s four times more fishing revenue than the Great Barrier Reef produces.
It’s really hard to say whether the effects of warming waters can be reversed in time to save the Great Southern Reef. “There’s only one thing to do and that’s control our carbon emissions, because that’s the root cause—climate change,” Wernberg said.
“Possibly, we can restore some of these kelp forests by looking at alternative hardier seaweeds that can live in warmer waters and replace the old kelp with those… But while that could work, the scale of the problem is potentially too big.”
Of course, stepping away from a singular focus on the Great Barrier Reef and taking in the bigger picture when it comes to Australia’s marine health would help too. “It’s not them or us, but Australia has more to offer in terms of magnificent unique environments that are under threat.”
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