Duration vs severity: Understanding invertebrate herbivory under varying warming events

As oceans warm, organisms are experiencing increased thermal stress. Marine thermal anomalies occur in both short-term heatwaves and long-term increases to mean temperatures, but direct comparative studies looking at the impacts of multiple types of thermal anomalies are rare. In ectothermic organisms, studies examining metabolic change after heatwaves show conflicting results to long-term climate change studies, leaving questions as to how species will be impacted across timescales. We tested the hypothesis that moderate experimental warming would increase herbivory rates over time, with a more pronounced increase occurring during long-term warming in comparison to short-term heatwaves. After simulating warming events on red sea urchins (Mesocentrotus franciscanus) and purple sea urchins (Strongylocentrotus purpuratus), the dominant eastern Pacific kelp forest herbivores, we found that feeding rates and thermal maxima varied by species and length of warming. While short-term heatwave events showed no increase in herbivory, longer-term warming led to increased herbivory in both species. Consumption and dissection data is included for both long-term and short-term warming experiments for both urchin species.