Collaborative Research: Thermal refuge or cascading extinctions: evaluating the capacity of coastal foundation species to mitigate impacts of intensifying heat waves

Heat waves are increasing across the U.S., altering the health of coastal ecosystems and, by extension, the health and welfare of the American public who depend on coastal resources. The success of coastal systems may depend on species that create habitat, protecting the overall ecological community from heat-wave impacts. Seaweed canopies and shellfish beds can provide shade and retain moisture, maintaining a cooler, damper environment that buffers the effects of heat waves. This project evaluates the ability of two of the most abundant habitat-forming species on the U.S. coastline – rockweeds and mussels – to maximize the survival of coastal species experiencing increasing heat waves along the west coast of North America from California to Alaska. The project combines observations during natural heat-wave events, heating experiments, and physiological studies of habitat-formers and the plants and animals they support to identify the vulnerabilities and refuges within the coastal ecosystem during these extreme events. The project will also provide training opportunities for students, expand course-based research experiences, and support outreach and knowledge exchange with environmental management agencies and the public. Together, these activities strengthen scientific capacity and improve understanding of coastal ecosystem resilience in a changing environment. To evaluate the ability of coastal foundation species to mitigate impacts of extreme heat events, the investigators test the hypothesis that foundation species are more tolerant of heat waves than the associated species that they support. Rockweeds and mussels are abundant foundation species likely to withstand stressors that other, facilitated species are unable to tolerate. But intensification of heat-wave events could push foundation species beyond their limits. There is a critical need to understand the potential for foundation species to mitigate impacts of heat waves or for cascading local extinctions to occur associated with their losses. The investigators combine observations during natural heat-wave events and in situ heating experiments with measurements of environmental conditions and physiological performance of foundation species and associated species. The objectives are to (i) quantify foundation species’ facilitation of associated communities by mitigating environmental stress; (ii) determine susceptibility of foundation species to heat-wave conditions and how their loss reshapes intertidal communities; (iii) identify physiological mechanisms underlying susceptibility of foundation and associated species to temperature stress; and (iv) predict outcomes of intensifying heat waves for foundation species and associated communities. The results of this research lay a strong foundation for anticipating the impacts of extreme heat events on the health of coastal ecosystems. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2547413 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Matthew Bracken | Institution: University of California-Irvine, IRVINE, CA | Award Amount: $391,523 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2547413 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2547413.html