As the planet warms, many marine plants and animals are moving to keep up with their preferred temperatures. In the Southern Hemisphere, this means that species are settling further south.
This shift is changing what we see when we snorkel and when and where we fish. Importantly, this also changes sensitive marine ecosystems.
But it’s not always easy for scientists to know exactly what’s going on beneath the surface of the ocean. To address this issue, we examined tens of thousands of photographs taken by Australian fishermen and divers and submitted to citizen science programs over the past decade.
They have shown that climate change is already disrupting the structure and function of our marine ecosystems—sometimes in ways previously unknown to marine scientists.
Views in motion
Warming over the Pacific has strengthened the East Australian Current over the past few decades, as shown in the animation at bottom right. This has led to the fact that the waters off the southeast of Australia have warmed up almost four times compared to the global average.
There is already overwhelming evidence that climate change is forcing marine species to move. Understanding this phenomenon is critical to conservation, fisheries management and human health.
For example, if fish susceptible to carrying toxins are starting to appear where you fish, you would like to know about it. And if an endangered species moves somewhere new, we need to know about it in order to protect it.
But the scale of Australia’s coastline means scientists can’t track changes in all areas. That’s where the public can help.
Fishermen, snorkellers and divers often visit the same place regularly over time. Many acquire an in-depth knowledge of the species found in the area.
When a new or unusual species appears on their site, these members of the public may do well to discover it. So our project set out to harness this invaluable community knowledge.
Read more: Climate-dependent migratory species are changing (almost) everything
The value of citizen science
The Redmap citizen science project began in Tasmania in 2009 and went nationwide in 2012. It invites the public to share observations of marine species uncommon in their area.
Redmap means Range Extending Database and Mapping Project. Redmap members use their local knowledge to control Australia’s vast coastline. When something out of the ordinary for a given location is discovered, fishermen and divers can upload a photo with location and size information.
The photographs are then verified by a network of nearly 100 marine scientists across Australia. Individual observations cannot tell us much. But over time, the data could be used to map which species could expand their range further south.
The project is supported by the University of Tasmania’s Institute of Marine and Antarctic Studies, as well as other Australian universities and a number of Commonwealth and government bodies.
Read more: Warming oceans are changing Australia’s fishing industry
We also examined data from two other national marine life surveys: the Reef Life Survey and the iNaturalist Australasian Fishes Project. The resulting dataset included decades of photographic observations of the species by nearly 500 fishermen, divers, snorkelers, spearfishers and scallopers.
Citizen scientists have recorded 77 species farther south than where they lived ten years ago. Many have been observed in the new location for several years and even during the cooler months.
Spearfisher Derrick Cruise, for example, was in for a surprise in 2015 when he saw coral trout swimming through a temperate kelp forest in his local waters near Sydney, much further south than he had seen before. He submitted the photo below to Redmap, which was then verified by a scientist.
Citizen scientists using Redmap were also the first to spot a grim octopus off the coast of Tasmania in 2012. Subsequent genetic studies confirmed the rapid spread of this species in Tasmanian waters.
Similarly, solo oriental rock lobsters have been appearing in Tasmania for some time. But Redmap observations have recorded dozens of individuals living together in a “den” that has not been observed before.
Other species recorded by citizen scientists moving south include the spiked clownfish, Mauritanian idol, and tiger sharks.
Supporting Healthy Oceans
Using citizen science data, we have prepared a report outlining the assessment methods underlying our research. We have also prepared detailed statewide report cards for Western Australia, Tasmania and New South Wales, where coastal waters are warming much faster than the global average.
We also created a map of the identified species changes and a downloadable poster summarizing the results. This allows the public, including those who provided the data, to see at a glance how climate change is affecting our oceans.
Citizen science has benefits beyond helping us understand changes in natural systems. Projects like Redmap open up a public dialogue about the impact of climate change on Australia’s marine environment using the public’s own knowledge and photographs.
Our research suggests that this method engages the community and helps engage people in documenting and understanding the challenges our oceans and coasts face.
A better understanding – both by scientists and the public – will help ensure healthy ecosystems, sustainable fisheries and a thriving future.
Read more: How you can help scientists track how marine life is responding to climate change