Use and reuse of long-term ecological data is needed for understanding how biological communities are responding to a changing world. In marine environments, key data includes large-scale patterns such as El Niño, ocean conditions such as sea surface temperature and winds, and biological data such as the distribution and abundance of food resources and marine wildlife. These core data are often collected in non-standardized ways, which makes it a challenge to compare patterns of biological response across different regions or marine ecosystems. The Long-Term Ecological Research (LTER) network provides an opportunity to make comparisons between sites as they share similarities in conceptual design and data collection procedures. In this ULTRA-Data project, a team of scientists is harmonizing ecological data from three different LTER sites representing temperate (California Current), subpolar (Northern Gulf of Alaska) and polar (Antarctic Peninsula) marine ecosystems. These three sites are influenced by global-scale processes and each provides comparable local data on ocean conditions, lower trophic level planktonic food resources (euphausiid crustaceans, also known as “krill”), and upper trophic level consumers (seabirds). The investigators are testing the idea that seabird populations and community structure are affected by local ocean conditions (habitat quality) and food resource availability, affected by larger-scale processes as observed during El Niño. Results from this