Award: OCE-1752600

High-latitude kelp forests that support complex food webs and coastal economies are increasingly exposed to ocean warming and acidification. To better understand the potential effects of these global changes on high-latitude kelp forests, we conducted laboratory experiments to examine the physiological and ecological response of four primary consumers (red and green sea urchins, pinto abalone and a turban snail), three dominant kelp species (including the habitat forming giant kelp), and other seaweeds to projected future conditions. Despite variability among the four primary consumers in their responses to warming and acidification, some generalities emerged. For example, there was no evidence of compensatory grazing to account for higher energetic costs associated with warming for the two urchin species. Instead, lower pH conditions were associated with reduced grazing rates across both urchin and both gastropod species. Together, our results suggest that reductions in community-level grazing pressure may emerge despite variability in physiological sensitivity and compensatory behaviors.In addition, we found that the three kelps differ in their vulnerability to future environmental conditions, and that the seasonal environmental context of nutrient and light availability shapes these responses. Our results suggest that poleward fringe populations of the habitat-forming giant kelp may be relatively resilient to anticipated ocean warming and acidification. In contrast, ocean warming conditions caused a decrease in the biomass and nutritional quality of both understory kelps. We then used these data to parameterize a dynamic energy budget model of the ecosystem and forecast its stability under projected climate scenarios, using observational data to establish baselines in the biomass and productivity of the primary consumers and primary producers. Despite potential reductions in grazing pressure associated with exposure to conditions projected to occur with continued global change, our findings predict decreased stability and greater uncertainty in kelp forests as the climate evolves, with extinction events playing a large role in determining overall ecosystem robustness. This work provides insight into potential shifts in ecosystem stability due to environmental change and offers guidance for conservation efforts and management. Over the course of the project, we offered two immersive undergraduate courses in Sitka, Alaska (in 2020,2023) serving 40 undergraduate students. This resulted in two podcast series, with eleven episodes in total, about global change at high latitudes that were produced in collaboration with KCAW public radio. The podcasts were aired on public radio and hosted on the website for KCAW. In addition, three of the independent student research projects that were developed in the course resulted in peer-reviewed publications, with far-reaching impacts for these students' careers. The undergraduate students in these classes also presented their research to the local community in Sitka, Alaska at an open house event, with 50-80 local residents attending for each class. Finally, the undergraduate students all participated in outreach events during the course, where they shared their research in more interactive manners. One course created interactive exhibits to share their research during an open house for the local community, whereas the second course created exhibits/activities for the two local high schools serving a high percentage of Indigenous students. Last Modified: 08/09/2024 Submitted by: KristyJKroeker