Project 1 - Summary/Abstract Marine biota accumulate both micronutrients and contaminants through complex dietary interactions that transfer energy from primary producers to top predators, and subsequently to the approximately three billion people who consume seafood globally. Climate change is actively reshaping the energy transfer and nutritional composition of seafood by lowering the quality of seafood-derived protein and the amounts of essential micronutrients in seafood. The reliance on seafood as a protein source is not geographically equal and the social perceptions and best-available science surrounding the health benefits and safety risks of consuming seafood are poorly understood. Seafood is the main source of toxic polychlorinated biphenyls (PCBs) and methylmercury (MeHg), and these two contaminants are the basis of most fish consumption health advisories in the US. However, most risk-benefit analyses argue that fish consumption delivers strong health benefits despite exposure to these contaminants. The interacting biogeochemical and ecological processes that govern the accumulation of contaminants and micronutrients in fishes respond differently to environmental change, resulting in seafood species and regions with differing accumulation levels across different temporal scales. Recent work by the Schartup and Choy groups demonstrates how the tight connections between marine food web structure and climate change govern the accumulation of MeHg and plastics in predatory fishes and their prey. Many fundamental questions still remain as to how the interacting roles of diet, bioenergetics, and food web structure dictate the transfer of contaminants and micronutrients through marine ecosystems experiencing unprecedented levels of climate change. The proposed work will comprehensively assess how climate change will shift the balance of human intake of increased contaminant loads and decreased micronutrient quantities in seafood. We present three integrated project aims that comprise a science-based inquiry into the nature of marine ecosystem linkages to climate change, informing public health and contaminant science surrounding the human intake of both the beneficial and the harmful components of seafood. The proposed work will be undertaken jointly by the labs of Schartup (marine chemistry and biogeochemical modeling) and Choy (food web ecology and biochemical tracers), who both have strong track records of collaboration and innovation in these areas. Project 1 will leverage the expertise of diverse collaborators in the acquisition of field specimens (fish stomachs, tissues, prey samples), the facilitation of quality contaminant and micronutrient analyses at SIO, and in model improvements. Project Leaders Schartup and Choy will also interact closely with the other Center investigators by co-utilizing ecologically diverse fish samples from different geographic locations, examining the chemical composition and microbial transformations of per...