Humans have become a dominant force of planetary change. This epoch, referred to as the Anthropocene, implies profound alterations to the Earth’s marine and terrestrial ecosystems upon which so many people depend. In particular, the prospect of a new era of blue growth poses unprecedented sustainability and governance challenges for the ocean, as marine ecosystems face cumulative pressures from local human impacts, global climate change and distal socioeconomic drivers. Exploring what the Anthropocene means for the ocean and its capacity to support human societies in a sustainable and equitable way represents a critical challenge.

This thesis consists of five papers and relies on a mixed-methods approach that includes quantitative and qualitative analyses, transdisciplinary practices, literature reviews and knowledge syntheses. Paper I looks at the relative influence of anthropogenic and biophysical interactions in explaining the occurrence of multiple coral reef regimes across the Hawaiian archipelago. It highlights the nuances of what underpins different regimes and how a reef’s natural setting may either limit or favour successful management interventions. Paper II synthesises the diversity of ocean claims, reviews their impacts, and describes their trajectory as the blue acceleration – a new phase in humanity’s use of the ocean that exhibits a phenomenal rate of change over the last 30 years. Paper III builds on the identification of the world’s largest seafood corporations and reports on a global experiment to test whether these companies have an interest and ability to take on a leadership role for ocean stewardship. The study shows that scientists can play a critical role in this process by linking knowledge to action. Paper IV investigates how finance can promote seafood sustainability. It identifies where different financial mechanisms are most salient along a seafood firm’s development trajectory and discusses three leverage points that could redirect capital towards more sustainable practices: bank loans, stock exchange listing rules, and shareholder activism. Paper V introduces the global production ecosystem (GPE) as a framework that integrates multiple sectors across land and sea to explore the cumulative transformation of the Earth’s biosphere. It shows that the GPE is characterised by hyper-connectivity, global homogenisation and weak feedbacks, which erode resilience and create conditions for new risks to emerge and interact.

Collectively, the five papers suggest that the Anthropocene ocean may be as much about upwelling and parrotfish grazing as it is about bank loans and intensified crop monocultures. The thesis provides novel conceptual and mechanistic ways to link ecosystems to their distal socioeconomic drivers and offers a useful contribution to both academic and policy discussions on how to approach ocean sustainability in the 21^st century.