Effects of Climate-Change Associated Stressors on Fish Social Behaviours

Group living is key to foraging, predator-avoidance, migration, and reproduction in many animal species but has been mostly overlooked in the context of managing the consequences of environmental change. Fishes are frequently used as model taxa to study collective behaviour in animals, and the effects of environmental stressors on ectotherms. They occupy aquatic habitats across the globe, play key roles as both predators and prey, and display a variety of social behaviours. Recent studies by PI Killen have demonstrated that among-individual variation in energy metabolism and locomotor capacity are important to costs and benefits of group-living in fishes, and link behaviour of individual animals to group behaviour. Relationships between metabolism and social behaviour also suggest that temperature change and hypoxia - two consequences of climate change in aquatic environments - may have profound effects on group living. To date, work examining behavioural and physiological responses to climate change has focussed on isolated animals, without inquiry into how effects at the individual level may affect social behaviour. Conversely, how social dynamics feedback to influence phenotypes and responses to environmental change is also unknown. To address these issues, the proposed project will: (1) examine how temperature and hypoxia affect interplay between behaviour of individual animals and their social group; (2) investigate how temperature and hypoxia influence group formation and functioning; and (3) produce a robust movement model of group behaviour that can be applied to a range of environmental conditions and ecological contexts. By adopting innovative empirical and theoretical approaches and combining behaviour and physiology in the lab and field, this project will be the first to examine how thermal shifts and hypoxia brought on by climate change will affect social behaviour.

Policy makers will benefit from the results of the project with specific regard to impacts of environmental change. Links with policymakers and stakeholders in the UK will be achieved by participation in the annual meeting of the annual Marine Alliance for Science & Technology for Scotland (MASTS) general meeting and associational workshops. Scientists and managers from several relevant bodies will be present at these meetings, including Marine Scotland, Scottish Environmental Protection Agency (SEPA), and Scottish Natural Heritage (SNH). Killen already possesses established links within all of these policy bodies and so results can be communicated quickly and directly to the relevant personnel. In Scotland (and indeed globally) there is a pressing need for information to inform the design of networks of Marine Protected Areas.

An immediate non-academic beneficiary of this work will also be the general public. Although many people are aware that animals engage in social behaviour, they are often surprised by the complexities of fish social behaviour and its importance for the health of natural populations. Killen has previously given public talks at the Glasgow Science Festival and British Science Festival on the topic of animal social behaviour. In every instance, the talks have been well-received, had a high degree of audience participation and interaction, and scored highly on audience feedback. In general the topic of social behaviour presents an ideal platform for showcasing the principles of biology, ecology, and evolution. The proposed project would extend this application to discussing the effects of environmental change within a context (i.e. social behaviour) that people can relate to and want to hear about.

Aspects of this study examining flow regimes will increase understanding of how fish biomechanics and spacing in groups affect energetic efficiency while swimming. This is likely to have direct applications in the design of tidal energy harvesters modelled after fish biomechanics (Killen and Ramesh recently collaborated on a one-year project in this area). Ramesh and Killen (along with collaborator in engineering Ignazio Viola at the University of Edinburgh) have recently completed a seed project (Carnegie Collaborative Grant) to investigate the use of fish tail motions during swimming as a means of designing high-efficiency energy tidal energy harvesters. This concept has received attention elsewhere but there are very few (if any) collaborations anywhere in the world with expertise in both engineering and fish biology. Unlike conventional aerodynamic wings and rotary turbines that have been the main focus of tidal energy harvesters - which require smooth flow for maximum efficiency - these fish-inspired harvesters can operate even at low velocities or unsteady flows and vertical gusts due to waves. An intriguing possibility that has not yet been investigated by any research group is that individual energy harvesters could be placed within an array analogous to the positioning of fish within a moving group. If the harvesters are positioned optimally, it should be possible to exploit vortices produced by harvesters further ahead within the array to encourage maximal amounts of flapping and energy extraction by more posterior harvesters.