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Uneven progress in tackling malnutrition has kept food and nutrition security high on the 53 development agenda globally 1,3. Micronutrients, such as iron and zinc, are a particular focus; it is estimated that nearly two billion people lack key micronutrients 7 , underlying nearly half of all deaths in children under the age of five years , and reducing GDP in Africa by estimates of up to 11% 2,3,7. Consequently, efforts to tackle malnutrition have shifted from a focus on 57 increasing energy and macronutrients (e.g. protein) towards ensuring sufficient consumption 58 of micronutrients 3. People gain nutrients from a mix of locally produced and imported food products. Fish, harvested widely and traded both domestically and internationally, are a rich source of bioavailable micronutrients, which are often deficient in diets that rely heavily on plant-based sources 6,8. Fish could therefore help address nutritional deficiencies if there are 62 sufficient quantities of fishery-derived nutrients accessible in places where deficiencies exist. 63 However, addressing this major food policy frontier has been elusive, in part because the 64 nutrient composition of fish varies significantly among species, and data remain sparse for most species 5. Here we determine the contribution marine fisheries can make to addressing micronutrient 68 deficiencies. First, using strict inclusion protocols (methods), we developed a database of 2,267 69 measures of nutritional composition, from 367 fish species, spanning 43 countries, for seven nutrients essential to human health: calcium, iron, selenium, zinc, vitamin A, omega-3 (n-3 71 fatty acids), and protein. We then gathered species-level environmental and ecological traits 72 that capture elements of diet, thermal regime, and energetic demand in fish 9,10 to develop a series of Bayesian hierarchical models that determine drivers of nutrient content (Methods).

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With the ongoing loss of coral cover and the associated flattening of reef architecture, understanding the links between coral habitat and reef fishes is of critical importance. Here, we investigate whether considering coral traits and functional diversity provides new insights into the relationship between structural complexity and reef fish communities, and whether coral traits and community composition can predict structural complexity. Across 157 sites in Seychelles, Maldives, the Chagos archipelago and Australia's Great Barrier Reef, we find that structural complexity and reef zone are the strongest and most consistent predictors of reef fish abundance, biomass, species richness, and trophic structure. However, coral traits, diversity and life histories provided additional predictive power for models of reef fish assemblages, and were key drivers of structural complexity. Our findings highlight that reef complexity relies on living corals-with different traits and life histories-continuing to build carbonate skeletons, and that these nuanced relationships between coral assemblages and habitat complexity can affect the structure of reef fish assemblages. Seascape-level estimates of structural complexity are rapid and cost-effective with important implications for the structure and function of fish assemblages, and should be incorporated into monitoring programs.

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Sudden losses to food production-shocks-and their consequences across land and sea pose cumulative threats to global sustainability. We conduct an integrated assessment of global production data from crop, livestock, aquaculture, and fisheries sectors over 53 years to understand how shocks occurring in one food sector can create diverse and linked challenges among others. We show that some regions are shock hotspots, exposed frequently to shocks across multiple sectors. Critically, shock frequency has increased through time on land and sea at a global scale. Geopolitical and extreme-weather events were the main shock drivers identified, although with considerable differences across sectors. We illustrate how socialecological drivers, influenced by dynamics of the food system, can spillover multiple food sectors and create synchronous challenges or trade-offs among terrestrial and aquatic systems. In a more shock-prone and interconnected world, bold food policy and social protection mechanisms that help people anticipate, cope and recover from losses will be central to sustainability. Main Food production shocks pose significant challenges for the UN Sustainable Development Goals (SDGs) 1 because of their potential to disrupt food supply and security, livelihoods, and human well-being 2-7. A wide range of social-ecological pressures on food systems can drive shocks through direct or indirect mechanisms. For example, droughts or floods can rapidly increase mortality of crops, livestock, or farmed fish; whereas sudden outbreaks of violent conflict may prevent farmers or fishers accessing their production systems 7,8. Prolonged overfishing can also produce unexpected, sudden losses in catch as exploited fish populations are pushed toward ecological tipping points, after which stock collapse occurs 9. People's vulnerability to shock events rests on their capacity to adapt, the scale and frequency of RSC, JLB, KLN, and BSH designed the study, and RSC conducted the analysis and wrote the paper. TAR assisted with figures and AJ assisted with qualitative analysis of shock drivers.

Fisheries and aquaculture make a crucial contribution to global food security, nutrition and livelihoods. However, the UN Sustainable Development Goals separate marine and terrestrial food production sectors and ecosystems. To sustainably meet increasing global demands for fish, the interlinkages among goals within and across fisheries, aquaculture and agriculture sectors must be recognized and addressed along with their changing nature. Here, we assess and highlight development challenges for fisheries-dependent countries based on analyses of interactions and trade-offs between goals focusing on food, biodiversity and climate change. We demonstrate that some countries are likely to face double jeopardies in both fisheries and agriculture sectors under climate change. The strategies to mitigate these risks will be context-dependent, and will need to directly address the trade-offs among Sustainable Development Goals, such as halting biodiversity loss and reducing poverty. Countries with low adaptive capacity but increasing demand for food require greater support and capacity building to transition towards reconciling trade-offs. Necessary actions are context-dependent and include effective governance, improved management and conservation, maximizing societal and environmental benefits from trade, increased equitability of distribution and innovation in food production, including continued development of low input and low impact aquaculture.

Abstract. Ecological structures and processes occur at specific spatiotemporal scales, and interactions that occur across multiple scales mediate scale-specific (e.g., individual, community, local, or regional) responses to disturbance. Despite the importance of scale, explicitly incorporating a multi-scale perspective into research and management actions remains a challenge. The discontinuity hypothesis provides a fertile avenue for addressing this problem by linking measureable proxies to inherent scales of structure within ecosystems. Here we outline the conceptual framework underlying discontinuities and review the evidence supporting the discontinuity hypothesis in ecological systems. Next we explore the utility of this approach for understanding cross-scale patterns and the organization of ecosystems by describing recent advances for examining nonlinear responses to disturbance and phenomena such as extinctions, invasions, and resilience. To stimulate new research, we present methods for performing discontinuity analysis, detail outstanding knowledge gaps, and discuss potential approaches for addressing these gaps.