A major challenge for earth scientists is to understand how oceans respond to decreasing oxygen levels. Areas of low oxygen, oxygen minimum zones (OMZs) and anoxic marine zones (AMZs), are predicted to increase in both expanse and frequency in response to climate warming and human modifications of coastal zones. Global warming is causing oxygen-deficient waters to expand and intensify. Therefore, studies focused on microbial communities inhabiting oxygen-deficient regions are necessary to both monitor and model the impacts of climate change on marine ecosystem functions and services. This study presents a compendium of 5,129 single-cell amplified genomes (SAGs) from marine environments encompassing representative OMZ and AMZ geochemical profiles. The study's researchers include Frank Stewart, associate professor in the Department of Microbiology and Immunology at Montana State University and an adjunct professor in the School of Biological Sciences.