Drivers of variation in cleaner-client interactions on coral reefs and their implications for the future

• Applicant: Rachel Gunn, Ph.D.
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions ; Sensory and Behavioural Biology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 534955044

Environmental change is affecting coral reefs via multiple pathways at all ecological levels, from individuals to communities. Understanding the implications of these changes is complex, often involving the study of multiple processes a large scale, which may not feasible. Quantifying behaviour is an invaluable tool for understanding not only how changes in the environment affects individuals, but how changes at the level of the individual can scale up to impact populations, communities, and ecosystems. On coral reefs, understanding the causes and consequences of behavioural expression in functionally important reef fish provides an insight into how coral reef communities will be able to persist under future environmental conditions. Cleaning interactions are a functionally important mutualism on coral reefs. 'Cleaner' species feed on ectoparasites found on 'client' species. Via the consumption of parasites, cleaners positively impact the abundance, diversity, size, recruitment, and immunity of coral reef fish. Cleaner-client interactions are behaviourally complex as the behaviour of cleaners is in part determined by the behaviour of clients, and vice-versa. This project will use coral reef cleaning stations to determine how multiple factors in the ecological, social, and behavioural environment drive individual behavioural variation in cleaner fish. Focussing on the Caribbean sharknose goby, Elacatinus evelynae, the project will quantify the boldness and cleaning behaviour of individuals and ask how these behaviours are determined by the relative roles of and interactions between biotic (Client diversity/abundance, territorial damselfish presence) and abiotic (Temperature, light availability, microhabitat complexity, ectoparasite density) variables.All of these ecological variables are predicted to change as coral reef ecosystems continue to degrade under environmental change and will affect the resources available to cleaner species. Behavioural patterns and ecological processes are closely linked. This project will therefore be able to use E. evelynae behaviour to provide an indication as to how cleaner-client interactions, the functional role of cleaning stations, and the persistence of coral reef communities may be impacted in the future. Finally, the results of this project will hopefully provide the foundation to inform future work that will experimentally manipulate cleaning stations in situ to simulate the effects of environmental change. This will allow the extent to which cleaner goby behavioural expression can promote the maintenance of cleaner-client interactions and cleaner station functionality in the future to be explicitly tested.

• DFG Programme: Research Grants