This three-year, $586,609 National Science Foundation project grant in the Geosciences program (CFDA 47.050) supports research at the Scripps Institution of Oceanography, University of California San Diego, to apply novel methods for understanding microbial growth efficiency, function, and energy transfer in the ocean. The research aims to identify ecological conditions and microbial taxa accounting for variance in microbial growth efficiency along light and nutrient gradients. It uses data collected in the California Current ecosystem to measure environmental factors, estimate microbial energy conversion, and compare to other metabolic processes. Innovative radioisotope tracer techniques, flow cytometry, and community structure analysis are combined with machine learning to provide predictive analytics linking microbial abundance, efficiency, and environmental conditions. The project also provides at-sea research training for graduate students, postdoctoral scholars, and undergraduates from historically underrepresented groups in marine sciences.