Background/Aims
Studies investigating fish cognition in the wild remain scarce due to methodological and financial constraints, as well as limited control over exogenous factors and unpredictable weather. Yet, advancing research in this area offers valuable insights into the ecological relevance of decades of laboratory findings on fish cognition and has the potential to improve management and restoration efforts, especially in the face of rapid environmental change.
Methods
In this study, we investigated how the loss of structural habitat complexity affects the cognitive abilities of humbug damselfish (Dascyllus aruanus). Fieldwork was conducted on One Tree Island, a protected, tourism-free coral cay in the southern Great Barrier Reef, from September to October 2025. Coral cover around the island dropped to just 30% during the observation period, primarily due to coral bleaching and Cyclone Alfred. Cognitive flexibility was assessed in the field using a reversal learning task in groups of humbug damselfish inhabiting reef patches of varying habitat complexity. However, a variety of other reef fish species also consistently participated in our experiments. Cognitive flexibility enables individuals to adapt their behaviour in response to changing environments.
Hypothesis (Data are currently being analysed)
We hypothesised that reef fishes from more complex sites would exhibit greater cognitive flexibility than individuals from less complex sites, as increased habitat complexity is associated with enhanced cognitive functions across aquatic and terrestrial taxa (Shumway 2008; Boesch 2021; Klinke and Brown 2026).
Conclusion
Understanding how habitat complexity influences reef fish cognition in the wild is crucial, as cognitive abilities may play a key role in determining individual survival and species persistence under rapidly changing environmental conditions.