A research team has developed a computer modeling program to assist scientists in predicting the impact of climate change and eventual restoration plans on coral reefs worldwide. According to researchers, this is a critical goal because climate change is killing many coral species and could lead to the collapse of entire coral reef ecosystems.
A UBC Okanagan research team has developed a computer modeling program to assist scientists in predicting the impact of climate change and eventual restoration plans on coral reefs worldwide. According to Dr. Bruno Carturan, this is a critical goal because climate change is killing many coral species and could lead to the collapse of entire coral reef ecosystems. But, because they are so complex, it’s logistically challenging to study the impact of devastation and regeneration of coral reefs.
Real-world experiments are impractical because researchers would need to manipulate and disrupt large areas of reefs, as well as coral colonies and herbivore populations, and then monitor changes in structure and diversity over long periods of time.
“It goes without saying that conducting experiments that disturb natural coral reefs is unethical and should be avoided, and using large aquariums is simply impractical,” says Dr. Carturan, who recently completed his doctoral studies at the Irving K. Barber Faculty of Science. “As a result, no such experiments have ever been carried out, limiting our ability to predict coral diversity and the associated resilience of the reefs.”
Our study is unique in that our findings apply to the majority of coral communities around the world. The span of diversity likely overlaps the actual coral diversity found in most reefs after measuring the effect of diversity on resilience in more than 245 different coral communities.
Dr. Bruno Carturan
For his latest research, published recently in Frontiers in Ecology and Evolution, Dr. Carturan used models to create 245 coral communities, each with a unique set of nine species and each occupying a surface of 25 square metres. The model represents coral colonies and different species of algae that grow, compete and reproduce together while also being impacted by climate.
Crucially, he notes, all the key components of the model, including species’ traits such as competitive abilities and growth rates, are informed by pre-existing, real-world data from 800 species.
The research team simulated various scenarios – including strong waves, a cyclone or intense heat – and then measured each model reef’s resilience taking note of damage, recovery time, and the quality of the habitat 10 years after the disturbance.
By running so many scenarios with computer modelling, the team found that more diverse communities — those with species having highly dissimilar traits – were most resilient. They were better at recovering from damage and had greater habitat quality 10 years after the disturbances.
“More diverse communities are more likely to have certain species that are very important for resilience,” Dr. Carturan explains. “These species have particular traits — they are morphologically complex, competitive, and with a good capacity to recover. When present in a community, these species maintained or even increased the quality of the habitat after the disturbance. Contrastingly, communities without these species were often dominated by harmful algae at the end.”
Coral diversity determines the strength and future health of coral reefs, he adds. Coral species are the foundation of coral reef ecosystems because their colonies form the physical habitat where thousands of fish and crustaceans live. Among those are herbivores, such as parrotfish and surgeonfish, which maintain the coral habitat by eating the algae. Without herbivores, the algae would kill many coral colonies, causing the coral habitat to collapse, destroying its many populations.
“Our study is unique in that our findings apply to the majority of coral communities around the world. The span of diversity likely overlaps the actual coral diversity found in most reefs after measuring the effect of diversity on resilience in more than 245 different coral communities.”
Simultaneously, the study provides a framework for successfully managing these ecosystems and aiding in coral reef restoration by revealing how coral community resilience can be managed by establishing colonies of species with complementary traits.
In the future, the model can help answer additional questions. For example, coral species that are critical for resilience are also the most affected by climate change and may be unable to recover if extreme climatic heatwaves become too common.
“It’s a very real and sad conclusion that we might lose these important species one day,” Dr. Carturan says. “Our model could be used to experiment and possibly determine if the loss of these species can be compensated for by other, more resistant species, preventing the eventual collapse of the reefs.”
