Abstract: Current-day populations of coral reef fish suffer when exposed acutely to elevated temperatures, but future warming will occur over greater timescales. Recent studies show that developmental or parental exposure to higher temperature can buffer the effects of warming on reef fishes. Yet we do not know the exposure duration, timing, or sex-specific requirements to induce these plastic changes within and across generations. In my PhD, I used the coral reef damselfish, Acanthochromis polyacanthus, to determine the length of exposure to warming early in life necessary to influence fitness-related characteristics later in life. I then experimentally tested sex- and time- specific effects of warming on reproductive performance and offspring quality. I found elevated temperature experienced in the first weeks post hatching was critical to stimulate beneficial adjustments later in life, but ongoing exposure to warming created trade-offs, including a cessation of reproduction when females experienced warming their entire lives. As expected, both parents’ thermal experiences played a role in offspring performance, but interestingly fathers’ thermal experiences had the greatest impact. In nature, this could mean coral reef fish born during a marine heatwave may have enhanced performance and so too could the next generation depending on whether the mother, father, or both parents experienced the heatwave. Conversely, the lack of reproduction from an average increase in temperature would likely lead to population decline. My findings highlight the complexity of predicting the effects of ocean warming, since the duration, timing, and sex-linked experiences to warming interact, even across generations.

Biography: Rachel is a marine ecologist that draws on an evolutionary perspective to study how coral reef fishes persist in a changing climate. She has a keen interest in statistics, particularly Bayesian methods. Rachel is a PhD candidate supervised by Prof. Philip Munday and Dr Jennifer Donelson at the ARC Centre of Excellence for Coral Reef Studies. Her interest in the underwater world began in her youth, privately breeding rare fishes and working in the ornamental aquarium industry. She went on to complete a Bachelor of Marine Sc. at Macquarie University, whilst working as an environmental educator in Sydney, Australia. Rachel undertook a M.Sc. in evolutionary biology at the University of Basel in Switzerland, where she studied the adaptive radiation of cichlid fishes in the African Great Lakes. She then worked as a marine ecologist for an NGO in South Africa before embarking on her PhD.