Climatic changes have the potential to alter population and community dynamics, ultimately influencing the biogeographic distributions of species. For many organisms, reproduction is physiologically tied to temperature. We tested the hypothesis that a physiological mechanism for reproductive failure in the acorn barnacle, Semibalanus balanoides, would result in predictable patterns of larval recruitment over broad geographic scales. Recruitment density was predicted to be dependent on the duration of permissive temperatures (< 10oC). for successful reproduction in adult populations of S. balanoides. We found that temperature was a reliable predictive variable for recruitment densities throughout our study region. Post-recruitment processes were also considered, specifically the competition between Semibalanus balanoides and Chthamalus montagui , described in Joseph Connell's 1961 experiment. The competitive hierarchy outlined in this experiment is not consistently observed throughout the range overlap of the two species. Growth and mortality were found to differ dependent on species and latitude, indicating that climate mediates this classic ecological system. Our results provide useful knowledge for refining models of biogeographic shifts. A consistent failure of larval supply and a breakdown of competitive advantage could accelerate the pace of predicted range contraction for S. balanoides. Further investigation of how environmental variables interact with physiology and ecological processes is necessary for accurate predictions of climate change effects.