Redrawing the lines of battle in coral reef fish communities

Coexistence of competing species in ecological communities is made possible by co-evolved "rules of engagement". During competition, these rules enable contest resolution through avoidance or signals, without the need to escalate to direct attacks, which prevents unnecessary energy loss for both individuals. However, rapid environmental change can disrupt established competitor hierarchies as the effect of resource loss differs between species, and can even create completely new combinations of species through the formation of novel ecosystems.

In these scenarios, the lines of battle need to be redrawn or, in the worst case, established from scratch.

Coral reef fish communities are hyperdiverse and highly threatened, making them an excellent model system for exploring how species coexist, both fundamentally, and under rapid environmental change. Reef fish communities are restructuring globally as species alter behaviour, shift geographic distributions or die. Resolving how, when and why decisions of whether to fight can tip the energetic balance of individuals and populations towards lethal outcomes, and how it could scale up to restructure communities and ecosystems, is necessary to provide realistic predictions on future impacts of global environmental change.

This project aims to reveal how coral reef fish contests mediate coexistence, and the consequences of disruption to this process in a rapidly changing environment. Taking advantage of multiple field locations through CASE Partner Operation Wallacea (Opwall), you will conduct strong field-based tests of underlying theories to explain contest behaviour between species.

You will use a combination of existing video-footage and manipulative field experiments to reveal how and why contest behaviour varies between different species and, using a macroecological approach, through space and time. Using this information, you will parameterise simulation models that can be manipulated to explore scenarios for when suboptimal contest resolution between novel species combinations can initiate or accelerate the collapse of existing communities.