A blue-ringed octopus pulses vibrant azure spots from within a tangle of yellow kelp just off Devonport. A yellow-bellied sea snake, tiger-striped, with a tail like a festively painted rudder, glides up the beach from the shallows. A small turtle in green-blue water off Bicheno looks like a little shell nestled in kelp – until you look more closely at the photograph.
Redmap is a citizen science platform where people can post photographs of sea creatures found outside their normal range. These sightings are then verified by scientists. The website was created by marine biologist Professor Gretta Pecl, who grew up in the northern suburbs of nipaluna/Hobart. Redmap is used to track outliers, possible signals of what is to come.
Around the globe, species are on the move as the climate changes. Whole forests creep poleward or to higher altitudes. Migratory birds leave earlier in the spring. Hidden under the water, a similar displacement of life is occurring, creating new ecosystems. Such species shifts are known as the fingerprint of climate change, but as Pecl points out, the fingerprint is fuzzy.
At least a quarter of earth’s species are on the move, but possibly as many as eight in 10. In the seas surrounding lutruwita/Tasmania, changes are occurring rapidly as our waters warm at a rate up to four times faster than the global average. As the warmer waters of the Eastern Australian Current push further south, they bring a flood of new arrivals which mingle with native fish.
Many coastal Tasmanian species cannot move further south as they have nowhere to go to, leading to new combinations of species, the unsettling of traditional relationships by new arrivals, with a question mark over how this will all eventually play out. “Some species have the capacity to shift quickly and others don’t,” says Pecl. “It’s a really complicated puzzle. When we’re trying to view that pattern, we get all this patchy and biased information, so when things are cryptic or small we don’t have enough data on them.”
Cryptic creatures include the blue-ringed octopus which, surprisingly, has always been an occasional visitor to Tasmania. Like the turtle, Pecl does not think its presence here is connected to climate change, but due to its mysterious nature, it is hard to be sure. The yellow-bellied sea snake may be a different story. Globally, it looks as though this species is shifting polewards. It is not yet able to survive the chilly winters of Tasmania, but in future, it seems likely that it will make its home here.
Tasmania has already quietly acquired at least 100 new species, including the gloomy octopus, whose presence here was first brought to attention on Redmap. With eyes that protrude cartoonishly atop its head, the octopus half scuttles and half glides about the ocean floor, trailing its legs like a dark cape. It is known for creating communal underwater “cities”. Genetic study has confirmed that it is a new arrival. Conversations with octopus fishers working in the vicinity of the Redmap sighting reveal that it already makes up 10 per cent of their catch at the time.
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The idea for Redmap emerged from Pecl’s conversations with fishers in the 2000s. During her work on the Tasmanian east coast, Pecl recalls seeing “the odd species that didn’t belong”, such as the long-spined sea urchin. She also spent time talking to local fishers, who were starting to see snapper arrive. “It was just, ‘ooh, that’s unusual’. It didn’t really start to feel like it was a huge climate change thing until working with rock lobster fishers. We did a survey of the rock lobster fishers where 80 per cent of them said they didn’t accept or acknowledge climate change. But then we did a workshop where we said, ‘Let’s just put that aside a minute – what sort of changes are you seeing in the marine environment?’ And they had a list as long as your arm.”
At the time, Pecl was also applying for a grant to look further at the new snapper populations reported by fishermen off the Tasmanian north coast. The grant was rebuffed on the grounds that there was no evidence of snapper in the state. “I thought, if there’s nothing that accepts the observations of recreational and commercial fishers, I’ll make something and we’ll turn it into data, and that’s really when all the climate change work took off.”
What can we expect to happen to our marine environment in future?
“It’s hard to imagine,” Pecl says. “We know that the east coast is one of the fastest-warming regions in the world and will continue to be so for the next 20 or so years at least. So we’re in for very large changes. We imagine kelp will continue to decline, urchins will continue to take over, we will end up with more tropical and sub-tropical species here. There will unfortunately probably be more heat-related diseases.”
Tasmanians may remember that in the wake of the 2015-2016 marine heatwave, Pacific Oyster Mortality Syndrome wiped out 90 per cent of local oysters.
This all sounds bleak, but the more understanding we have of climate change, the better prepared we can be. Citizen science is one way that ordinary people can contribute, Pecl believes, as well as looking after our natural places. This is a principle Pecl lives by – her plans for the weekend after our conversation included taking her children to an invasive starfish clean-up.
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While researching this story, I felt deeply saddened. I want to finish with optimism, but how to do so without sounding falsely positive? Our seas are changing, and much has already declined. The future is uncertain, though we know that our waters will continue to warm. We still have an opportunity to protect our local ecosystems and species, whether through actions like catching and eating sea urchin, or lobbying for climate change action. As communities, we can care for our local areas. Looking at my son, who is nine months old, I feel that it is necessary to try.
Read more about Redmap at www.redmap.org.au.
