EMBRACE-OCE-Growth: The dynamics and drivers of fish-mediated ecosystem functions in Large Marine Ecosystems

Marine fishes play important roles within ecosystems, such as transporting food and nutrients, which ultimately supports healthy oceans and productive fisheries. As marine ecosystems have been increasingly impacted by environmental changes, the abundance and composition of fish species has been rapidly changing worldwide. Because different species play different roles, changing fish populations could have major impacts on the health and stability of ecosystems. However, very little research has measured these impacts, and we lack fundamental knowledge about how marine ecosystems could change in the future. This project will use long-term monitoring data to measure food and nutrient transport by fishes in large marine ecosystems and uncover how this is being modified by stressors like ocean warming and fishing. This project will advance fundamental scientific knowledge in marine biology and will support national welfare by improving our ability to predict changes in ecosystems and manage sustainable fisheries. This project will also broaden participant diversity in marine science by training a diverse group of undergraduate and graduate students and by supporting marine biology summer camps for historically-underserved youth groups. This project will quantify temporal patterns (up to 40 years) of biomass production, nutrient cycling, and piscivory by fish assemblages across 800 spatial locations spanning six European Large Marine Ecosystems. Moreover, this project will quantify the influences of environmental and human factors on these fish-mediated ecosystem functions across space and time. To accomplish this, our team will integrate standardized bottom trawl data with bioenergetics modeling and statistical inference. Specifically, we will collect fish specimens during research cruises in the North Sea and will analyze them for whole-body carbon, nitrogen, and phosphorus content, as well as growth rate and diet. These data will be input into stoichiometry-based models to predict individual-level nitrogen and phosphorus storage and excretion rates, as well as biomass accumulation and piscivory. These outputs will then be scaled up to entire fish communities for all locations in all time periods to map the spatiotemporal dynamics of fish-mediated ecosystem functions. We will then analyze the environmental and human drivers of these patterns using causal inference theory and Bayesian regression models. By integrating ecological stoichiometry with extensive spatial and temporal monitoring data, this project will provide novel insights on how marine ecosystem functioning is responding to environmental changes, which will be critical for guiding ecosystem-based management into the future. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.