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- Sharks in a changing ocean : a multiscale assessment of anthropogenic pressures on key marine predatorsPublication . Santos, Catarina; Rosa, Rui Afonso Bairrão da; Santos, Catarina Frazão da Fonseca Ribeiro dos; Miranda, Pedro Michael Cavaleiro deWith over a third of their species threatened with extinction, sharks and their relatives have been struggling to cope with the challenges brought upon them by the Anthropocene. While overexploitation has been driving the worldwide decline of this group, the rapidly escalating environmental changes triggered by anthropogenic activities are posed to further test their resilience. By integrating information obtained through distinct approaches, the present dissertation addresses a series of research questions regarding the effects of anthropogenic threats — namely climate change — over sharks, aiming to provide a stepping-stone towards a more holistic understanding of how this group may fare in the oceans of tomorrow. Specifically, through a systematic overview of the scientific landscape, chapter 2 gauges how trends in shark research have evolved over time and are distributed across both spatial and biological dimensions, revealing a clear shift in the motivations driving research over time, along with a marked spatial bias. Additionally, it showcases how, despite the recent increase in the number of studies, climate change remains one of the least studied threats. In this context, chapter 3 banks on decades of literature across the marine tree of life to, through a sequence of meta-analyses, provide critical insights into the effects of warming, acidification, and oxygen loss — highlighting the nefarious impacts of the latter. Meanwhile, chapter 4 uses a similar approach to contrast the effects of warming and acidification over elasmobranchs, considering distinct biological responses and functional attributes. It showcases the clear and pervasive effects of warming and identifies the specific gaps in experimental climate change research featuring sharks, underscoring the paucity of research on oxygen loss. Chapter 5 proposes a framework to evaluate the climate associated risk at the species-level based on species attributes and ecosystem-dependencies, assessing all extant sharks at the global scale. It emphasizes the imminence of the threat imposed by climate change over this group, with many species likely to be impacted over the short-term, and the considerable long-term differences in the scale of impacts caused by distinct scenarios, along with the nature and scale of functional implications. Finally, Chapter 6 uses a correlative approach to project how different emission scenarios may impact the habitat suitability and, consequently, the distribution patterns of sphyrnid sharks, a unique and particularly threatened group of elasmobranchs. In this context, the present dissertation highlights how the timely consideration of climate change is key to the long-term success of management plans, hopefully contributing to future conservation and research endeavors targeting this key group of marine predators.