Dr Shaun Wilson and Professor Nick Graham have been working with researchers from around the globe on projects that investigate how climate change and fishing affect the world’s reefs and the services these reefs provide.
Shaun and Nick first met at Newcastle University in 2005, where they worked together on a project assessing the impacts of marine heatwaves on corals and the wildlife they support.
Now Nick has invited Shaun, who is head of marine science at the Western Australian Department of Biodiversity, Conservation and Attractions to spend 10 weeks in the Lancaster Environment Centre as part of Lancaster’s Distinguished Visitor programme. It’s an opportunity for them to further their collaboration.
Back in 2005, they visited the Seychelles, wherein 1998 a mass bleaching event had caused widespread death of coral on the islands' reefs. An extensive data set, collected there in 1994, provided a basis for measuring changes in the coral and fish.
This first trip proved so interesting that they have returned together to the same reefs every three years, to see how the reefs responded to this major disturbance over long timescales. As a consequence, they’ve built one of the world’s longest-term data sets on the impact of, and recovery from, coral bleaching.
“It’s a very valuable dataset. There is not a lot of information at this spatial and temporal scale,” said Shaun. “It has helped us to understand how coral bleaching effects reef fish and associated fisheries, and which factors promote recovery of reefs after the bleaching.”
Indeed their work published in Nature in 2015 identified five things which are important to recovery: maintaining structural complexity; water depth; high water quality with low levels of nutrients; high numbers of juvenile corals and lots of herbivorous fish to feed on the fleshy seaweed so it doesn’t take over the system.
“Some of these things can be managed locally to reduce the chances that reefs will be over-taken by fleshy seaweed,” says Shaun. “Management of waterways and fisheries can maintain high levels of water quality and herbivorous fish, whilst large scale knowledge on reef depth and complexity can determine which reefs are most resilient to climate change, informing conservation planning.”
Some of the reefs have suffered regime shifts, when corals move to an alternate state, dominated by fleshy brown seaweed rather than coral. Once the reefs have got to that state they are unlikely to recover. One of the big research challenges is to discover whether it is possible to reverse this regime shift and how it might be done. A question that is currently being tackled by Lancaster PhD students, supervised by Nick.
Their latest trip, early in 2017, was a depressing experience for the scientists, coming a few months after another mass bleaching event, that affected 75% of the world’s coral reefs.
“Since our initial surveys in 2005 we had seen a lot of the reefs recover and now we were seeing them crash back down to similar conditions as seen following the 1998 mass death of corals,” Shaun explains.
It is primarily the branching corals, which provide refuge for small fish, that have bleached and died, while a lot of the much slower growing massive corals, seem to have survived and are still providing some structural complexity and habitat.
“The maintenance of structural complexity is really important for recovery so there is some hope for Seychelles reefs. But these and other reefs need time to fully recover after large scale disturbances, which may not happen if the time between coral bleaching events becomes shorter.”
The Lancaster visit offers Shaun time to discuss where next with the Seychelles project. “It provides the opportunity to work face to face with Nick and his research students: despite modern communications, nothing matches sitting down in a room and talking things through with people.”
“I also gain a lot by coming into a totally new environment and meeting new people, including social scientists: this is not my area of expertise but social science is an important part of any environmental work.”
Nick adds, “Having Shaun visit has been a wonderful opportunity for us to solidify our thinking and collaboration, and plan future work together. Shaun’s perspectives from working at the interface between research and management of coral reefs in Australia have been of huge value to our growing group of coral reef researchers here in Lancaster.”
For Shaun, the Seychelles research offers useful insight into how to manage the reefs back home in Western Australia.
“There are a number of reefs that have recently bleached in Western Australia, and the research we carry out in the Seychelles and other parts of the world helps us understand which reefs are most likely to recover.”