Latitudinal gradients in species interactions are widely cited as potential causes or consequences of global patterns of biodiversity. However, mechanistic studies documenting changes in interactions across broad geographic ranges are limited. We surveyed predation intensity on common prey (live amphipods and gastropods) in communities of eelgrass (Zostera marina) at 48 sites across its Northern Hemisphere range, encompassing over 37° of latitude and four continental coastlines. Predation on amphipods declined with latitude on all coasts but declined more strongly along western ocean margins where temperature gradients are steeper. Whereas in situ water temperature at the time of the experiments was uncorrelated with predation, mean annual temperature strongly positively predicted predation, suggesting a more complex mechanism than simply increased metabolic activity at the time of predation. This large‐scale biogeographic pattern was modified by local habitat characteristics; predation declined with higher shoot density both among and within sites. Predation rates on gastropods, by contrast, were uniformly low and varied little among sites. The high replication and geographic extent of our study not only provides additional evidence to support biogeographic variation in predation intensity, but also insight into the mechanisms that relate temperature and biogeographic gradients in species interactions.

Significance: Although the United States needs to expand its STEM (science, technology, engineering, mathematics) workforce, United States postsecondary institutions struggle to retain and effectively teach students in STEM disciplines. Using teaching techniques beyond lecture, such as pair discussions and reflective writing, has been shown to boost student learning, but it is unknown what proportion of STEM faculty use these active-learning pedagogies. Here we describe DART: Decibel Analysis for Research in Teaching, a machine-learning–derived algorithm that analyzes classroom sound to predict with high accuracy the learning activities used in classrooms, and its application to thousands of class session recordings. DART can be used for large-scale examinations of STEM teaching practices, evaluating the extent to which educators maximize opportunities for effective STEM learning.