As climate change wreaks havoc on the Great Barrier Reef, marine researchers must be both resilient and resourceful.
In February last year, people around Australia and the world looked on in horror as climate change made its mark on the world’s largest coral reef. Huge swathes of coral were bleached white by warming ocean temperatures, including up to two-thirds of the northern Great Barrier Reef. Across Australia, marine ecologists scrambled to document the extent of the damage. It was a daunting and often depressing task, and nobody envied the scientists involved. Nobody really talked about them, either.
There is a certain breed of scientist who lives and breathes for coral reefs and all their intricate workings. ‘Coral reef scientist’ may at first sound like a glamorous job title, conjuring images of crystal waters, endless sunshine and an underwater kaleidoscope of colour. But as the devastating extent of the bleaching became clear, reef scientists crossed their fingers and hoped that this would be the wake-up call required to save the reef.
Coral bleaching occurs when ocean temperatures stay above average for an extended period of time. The corals are forced to expel the symbiotic algae living in their tissue, which ordinarily provide them with food and colouration. Once the algae are gone, the coral’s ghostly calcium carbonate skeleton becomes visible beneath the now transparent tissue. These coral are now ‘bleached,' but not dead; if the temperature drops quickly enough, the algae can return. However, if the temperature remains high, the coral will die and there is no coming back from the dead.
At the end of 2016, the National Coral Bleaching Taskforce, headed by Terry Hughes at the ARC Centre of Excellence for Coral Reef Studies in Townsville, confirmed that up to 67% of coral in the inner-northern Great Barrier Reef had died. In recent years, the Great Barrier Reef has withstood the worst of multiple tropical cyclones, all while still recovering from severe bleaching events in 1998 and 2002. Add to that last year’s bleaching event, and the Great Barrier Reef looks to be in worse shape than ever before. Scientists predict that it could be up to 15 years before newly settled corals in the northern region can grow to similar sizes.
Different researchers responded to the mass bleaching event in their own way, often depending on their career stage or research area. For those starting out in research, sudden and intense environmental disasters can temporarily wreak havoc. For Katie Motson, a new PhD student at James Cook University, the bleaching caused major headaches and the relocation of her fieldwork from Lizard Island to the southern Great Barrier Reef, a less ideal study site. Motson’s PhD will investigate how degraded coral reefs affect the health of herbivorous fish populations.
Motson was disappointed when she realised that Lizard Island was no longer a viable option for her PhD research — the reefs there just didn’t have the coral cover needed for her study. As devastating as it was to witness, the bleaching event encouraged Motson to stay in research. “The whole reason I wanted to go into a PhD, the whole reason I am in marine biology is for coral reef conservation,” she says. “Managing resilience is more important now than ever, as well as educating ourselves in the dynamics of coral reef ecology. This is what I signed up for”.
Such disturbance to logistics is fortunately limited to a small proportion of the research community. Students coming to the end of their PhD and other early-career researchers often have enough data collected previously that they can continue publishing and move other research to new sites.
For many scientists, the science continues just as before. Andrew Hoey, a marine ecologist at the ARC Centre of Excellence for Coral Reef Studies, has studied the interactions between coral reef fish and algae for the last 15 years. Because cyclones had previously torn through many of his long-term study sites, the bleaching event did not evoke in him the same shock that others felt.
“I am even more motivated to keep studying the reef now,” says Hoey. “You have to be positive about continuing in the field. The reef won’t disappear, it will just change, so there will always be questions that need answering.” Hoey expects that scientists will alter the type of questions they seek to answer to reflect the urgency of the situation and the public’s increasing awareness of coral bleaching.
Jodie Rummer, a fish physiologist at James Cook University, runs aquarium experiments to study how small reef fish perform under environmental conditions predicted by climate change models, such as increased water temperatures and ocean acidification. At the onset of last year’s bleaching event, Rummer found that her lab's research had stopped being simulations of a future climate, and was in fact reflecting the present climate.
The bleaching on the Great Barrier Reef was induced by higher-than-normal ocean temperatures, a result of climate change exacerbated by an El Niño. In February and March 2016, the water temperature along the northeast coast of Australia rose beyond that used as treatments in laboratory simulations of future ocean conditions. “The most mind-blowing aspect was that what was happening on Lizard Island was what we normally simulate in labs as end-of-century conditions,” says Rummer. Average temperatures predicted by climate models for the year 2100 had been reached in 2016 — briefly, yes, but to devastating effect. Rummer and her students had to recalibrate not only their experiments, but also their approach to studying the potential impacts of climate change on fish physiology.
Four sampling trips later, Rummer and her colleagues have huge amounts of data from before, during and after the bleaching event, which will enable them to paint a detailed picture of how coral reef fish communities respond to severe coral bleaching. The silver lining of an otherwise depressing situation is that scientists were able to prepare and conduct rigorous sampling throughout the Great Barrier Reef. Nothing could stop the event from unfolding, but the organisation of a National Coral Bleaching Taskforce meant that scientists were poised to collect as much information as possible.
The impacts of the bleaching event on the scientific community are not necessarily negative, but do require the adjustment of traditional research practices. Rummer hopes that the events of 2016 will encourage people to be even better scientists than before.
As a call to arms, the coral bleaching and the dire state of the world’s coral reefs will no doubt inspire more communication and collaboration across disciplines, both within and beyond coral reef science. The urgent need for a scientifically literate society has also been brought into sharp focus. While coral reef scientists remain hopeful, hope remains for the future of coral reefs.
Edited by Andrew Katsis and Ellie Michaelides