Human domination of the biosphere has led to substantial gains in human welfare and economic development, but simultaneously threatens the planetary conditions that underpin societal wellbeing and prosperity 1-3 . Emerging challenges, including water scarcity, food security issues and biodiversity loss, are intractable, interconnected and influenced by a range of crossscale drivers and complex feedback mechanisms 4 . These challenges, and attempts to address them, involve multiple groups of people with different needs and interests and are beset by social, political and administrative uncertainty 5 .Researchers and practitioners alike are turning to knowledge co-production as a promising approach to make progress in this complex space. Conceptually, knowledge co-production is part of a loosely linked and evolving cluster of participatory and transdisciplinary research approaches that have emerged in recent decades. These approaches reject the notion that scientists alone identify the

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Determining the form of key predator-prey relationships is critical for understanding marine ecosystem dynamics. Using a comprehensive global database, we quantified the effect of fluctuations in food abundance on seabird breeding success. We identified a threshold in prey (fish and krill, termed "forage fish") abundance below which seabirds experience consistently reduced and more variable productivity. This response was common to all seven ecosystems and 14 bird species examined within the Atlantic, Pacific, and Southern Oceans. The threshold approximated one-third of the maximum prey biomass observed in long-term studies. This provides an indicator of the minimal forage fish biomass needed to sustain seabird productivity over the long term.