Ester Dias is a Biologist and holds a M.Sc. in Applied Ecology (2007) and a Ph.D. in Environmental and Marine Sciences (2014), completed at the University of Porto. She is currently a post-doc researcher at CIIMAR were she is studying the life history plasticity of diadromous species. Her research interests also include estuarine ecology and biological invasions, and the use of ecological tracers (e.g. stable isotopes) to characterize food webs and fish movements.
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Technical advances in bio-logging achieved over the years have allowed the study of the effects of climate warming on large oceanic fish movements. It has been observed that deepening isotherms and shoaling of oxygen minimum zones result in a reduction in the vertical distribution of ectothermic pelagic predators with high oxygen demands such as sharks. However, fundamental questions remain unanswered, such as Q1) how increasing temperature and hypoxia affect the foraging behavior of large predatory fish and their body condition, and Q2) what are the consequences for population fitness (i.e., reproductive success)? Answering these questions is necessary for the management and conservation of large predators because warming and deoxygenation are likely to have direct impacts not only on their spatial distribution (by avoiding low dissolved oxygen concentrations and/or high temperatures) but also on their body condition, and consequently on their fitness. Therefore, the main objective of this proposal is to investigate how ocean warming and deoxygenation will influence the foraging behavior and reproductive potential of marine predators. To achieve this goal, A) the diet, B) body condition, and C) reproductive potential of the widely distributed ectothermic predator, the blue shark (Prionace glauca), will be investigated in two contrasting areas considering temperature and oxygen conditions- Cabo Verde (high temperature and hypoxia) and Azores (low temperature and normoxia). For that, stable isotopes will be used to identify the most likely prey assimilated by sharks in each area, followed by an estimation of the energy density profiles of the blue sharks and their most likely prey (Q1). This information will be combined with tagging data (i.e., provides information on habitat use and oxygen consumption) to develop a bioenergetics model (Dynamic Energy Budget) to estimate the reproductive potential (a proxy for fitness) of sharks considering temperature, oxygen, and food availability/quality, or a combination of these factors (Q2). Blue sharks are an important component in pelagic fisheries, especially for drifting longliners targeting swordfish and tunas. Understanding the potential effects of climate-driven changes on their reproductive potential is paramount to inform sustainable fisheries management practices, while developing targeted interventions, if necessary, to mitigate these effects and preserve their populations.
