The Combined Effects of Multiple Environmental Stressors on Predator-Prey Interactions in Freshwater Habitats

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)


Research in the field of behavioural ecology has addressed many aspects of species dynamics in the context of environmental variability. However, natural systems face increasing challenges due to anthropogenically driven disturbances and global warming. Within natural habitats, environmental parameters which exceed normal strength and variation can have independent or interactive effects on the species that inhabit them. Interacting effects often create unpredictability in the system’s response to change, posing challenges for conservation. In this thesis I explore the impacts of co-occurring environmental stressors on fish predator-prey interactions, with a focus on increased water temperature and turbidity. These parameters are known to impact the same behavioural processes in fish (i.e. activity and risk perception) through different modalities (i.e. metabolic and sensory), potentially leading to the emergence of “ecological surprises”. I present a review on the impact of increased turbidity on predator-prey interactions of freshwater fish; then, through both laboratory and field experiments, I assess how changes in turbidity and other focal stressors affect different stages of the predator-prey interactions. The findings highlight the complexity of predator-prey interactions in the context of environmental change. While encounters between visual predators and their prey may become less frequent due to deteriorating water quality, they may also become more perilous for the prey due to their increased conspicuousness in warmer water, reduced anti-predator behaviour due to impaired visual information, and heightened predation risk induced by higher predation drive. Collectively, the results presented in this thesis highlight the importance of including relevant ecological complexity in the assessment of behavioural processes either in the field or through multi-factorial laboratory studies. This is crucial because the emergence of “ecological surprises” is context-dependent and relative to the behaviours quantified.
Date of Award19 Mar 2024
Original languageEnglish
Awarding Institution
  • University of Bristol
SponsorsUK Research and Innovation
SupervisorChristos C Ioannou (Supervisor) & Martin J Genner (Supervisor)

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