Photo: Jean-Philippe Maréchal

A UBC Okanagan researcher is using computer modelling to help manage the world's coral reefs while predicting future reef health.

Biology doctoral student Bruno Carturan is working with scientists at Australia's Flinders' University and Nova Blue Environment to study the ecosystems of the planet's endangered reefs.

“Coral reefs are among the most diverse ecosystems on Earth and they support the livelihoods of more than 500 million people,” says Carturan. “But coral reefs are also in peril. About 75 per cent of the world’s coral reefs are threatened by habitat loss, climate change and other human-caused disturbances.”

Carturan studies under UBC Okanagan professors Lael Parrott and Jason Pither, who all explore resilience, biodiversity and complex systems. Carturan says that if no effective measures are taken by 2050, nearly all of the planet's reefs will be affected. 

However, there is still hope. Carturan has found ways to examine the reefs and why some ecosystems are stronger than others. Finding out why this is, could help stem the losses.

“In other ecosystems, including forests and wetlands, experiments have shown that diversity is key to resilience,” he says. “With more species, comes a greater variety of form and function—what ecologists call traits. And with this, there is a greater likelihood that some particular traits, or combination of traits, help the ecosystem better withstand and bounce back from disturbances.”

Ecologists have extensively investigated the importance of diversity in ecosystems with the consensus that more diverse ecosystems are more resilient. This however has rarely been tested with corals. 

Creating an experiment where the conditions of real coral reefs is challenging for many reasons. One significant challenge is that the required size, timeframe and various samples needed are unmanageable, but thats where computer simulation modelling comes in. 

“Technically called an ‘agent-based model,’ it can be thought of as a virtual experimental arena that enables us to manipulate species and different types of disturbances, and then examine their different influences on resilience in ways that are just not feasible in real reefs,” says Carturan.

In the simulation, individual coral reef colonies and algae grow, compete, reproduce and die in realistic ways over the span of decades. This includes the number and identity to see how the virtual reefs respond to threats.

“This is crucial because these traits are the building blocks that give rise to ecosystem structure and function. For instance, corals come in a variety of forms—from simple spheres to complex branching—and this influences the variety of fish species these reefs host, and their susceptibility to disturbances such as cyclones and coral bleaching," says Carturan. 

By running the simulations over and over again, combinations which provide the greatest resilience are identified. This can aid ecologists in their efforts to design reef management and restoration. 

“Sophisticated models like ours will be useful for coral-reef management around the world,” says collaborating Flinders researcher Professor Corey Bradshaw. “For example, Australia’s iconic Great Barrier Reef is in deep trouble from invasive species, climate change-driven mass bleaching and overfishing.

“This high-resolution coral ‘video game’ allows us to peek into the future to make the best possible decisions and avoid catastrophes.”

Photo: Jean-Philippe Maréchal