Researcher Creates Hundreds of Scenarios and Determines Importance of Coral Diversity

A UBC Okanagan research team has created a computer modeling program to help scientists predict the effect of climate damage and potential restoration programs on coral reefs around the world.

This is a critical goal, says Dr Bruno Carturan, because climate change is killing many coral species and can lead to the collapse of entire coral reef ecosystems. But, because they are so complex, it is logistically difficult to study the impact of coral reef devastation and regeneration.

Real-world experiments are impractical, as researchers would have to manipulate and disturb large areas of reefs, as well as coral colonies and herbivore populations, and then monitor changes in structure and diversity over many years. .

“It goes without saying that conducting experiments that will disturb natural coral reefs is unethical and should be avoided, while the use of large aquariums is everything. simply unachievable,” says Dr. Carturan, who recently completed his doctoral studies at the Irving K. Barber School of Science. “For these reasons, no such experiment has ever been conducted, which has hampered our ability to predict coral diversity and associated reef resilience.”

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 an area of ​​ square meters. The model represents colonies of corals and different species of algae that grow, compete and reproduce together while being impacted by the climate.

Above all, be aware , all key components of the model, including species characteristics such as competitive abilities and growth rates, are informed by preexisting and actual data from 800 species.

The research team simulated various scenarios – including strong waves, a cyclone or intense heat – and then measured the resilience of each model reef taking into account the damage , recovery time and habitat quality years after disturbance.

By running so many scenarios with computer modeling, the team found that the most diverse communities – those whose species have very dissimilar characteristics – were the added lly resilient. They recovered better from damage and had better habitat quality years after the disturbances.

“ More diverse communities are more likely to have certain species that are very important for resilience,” says Dr. Carturan. “These species have special attributes – they are morphologically complex, competitive and with a good capacity for recovery. When present in a community, these species have maintained or even increased habitat quality after disturbance. In contrast, communities without these species were often dominated by harmful algae in the end.”

Coral diversity determines the strength and long run health of coral reefs, adds he. Coral species are the foundation of motor coral reef ecosystems because their colonies form the physical habitat where thousands of fish and crustaceans live. Among these are herbivores, such as parrotfish and surgeonfish, which maintain the coral habitat by eating the algae. Without herbivores, the algae would kill off many coral colonies, causing the coral habitat to collapse, destroying its many populations.

“What is distinctive about our study, c is that our results apply to most coral communities in the world. By measuring the effect of diversity on resilience in over 245 different coral communities, the extent of diversity likely overlaps with the actual coral diversity found in most reefs ..”

At the same time, the study provides a framework for successfully managing these ecosystems and aiding in the restoration of coral reefs by revealing how the resilience of coral communities can be managed by establishing colonies of species with complementary characteristics.

For the future, there are other questions the model can help answer. For example, coral species vital for resilience are also the most affected by climate change and may not be able to recover if severe climatic heat waves become too frequent.

“It’s a very real and sad conclusion that we could one day lose these important species,” says Dr Carturan. “Our model could be used to experiment and perhaps determine if the loss of these species can be offset by other, more resilient ones that would prevent eventual reef collapse.”

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