New research suggests corals can swap out their resident algae for more climate change tolerant friends.

An advanced modelling project has found some corals that swap out the algae inside their tissue for different strains are more tolerant to warming temperatures. 

The experts say this behaviour is likely to help them survive moderate global climate change.

Coral bleaching is a process in which symbiotic algae that live inside coral (called zooxanthellae) are expelled from their overheated home. 

The thermal tolerance of a coral is dictated in part by the type of algae symbiont present. However, the symbionts have both high levels of genetic diversity and adaptive potential, suggesting they could play a role in coral adaptation.

To find out more about this relationship, researchers have developed a global ecological and evolutionary model that simulates coral responses to warming and ocean acidification. 

They applied this model to 1,925 reefs under four climate scenarios. The model included two competing coral species, which could adapt to ocean warming and acidification effects by either shuffling their symbionts (replacing them with more tolerant symbiont types) or through symbiont evolution. 

According to the model, shuffling was more effective than evolution, and ocean warming, rather than acidification, had the strongest impacts on reef degradation. 

However, global patterns were ultimately defined by the interaction of warming and type of adaptation.

The researchers say that although the model involves a simplified representation of coral ecology and evolution, the findings provide insights into coral adaptation that can help inform conservation as well as highlight future research avenues.

The study is accessible here.