Philosophical Transactions of the Royal Society B: Biological Sciences
Eelgrass creates critical coastal habitats worldwide and fulfills essential ecosystem functions as a foundation seagrass. Climate warming and disease threaten eelgrass, causing mass mortalities and cascading ecological impacts. Subtidal meadows are deeper than intertidal and may also provide refuge from the temperature-sensitive seagrass wasting disease. From cross-boundary surveys of 5761 eelgrass leaves from Alaska to Washington and assisted with a machine-language algorithm, we measured outbreak conditions. Across summers 2017 and 2018, disease prevalence was 16% lower for subtidal than intertidal leaves; in both tidal zones, disease risk was lower for plants in cooler conditions. Even in subtidal meadows, which are more environmentally stable and sheltered from temperature and other stressors common for intertidal eelgrass, we observed high disease levels, with half of the sites exceeding 50% prevalence. Models predicted reduced disease prevalence and severity under cooler conditions, confirming a strong interaction between disease and temperature. At both tidal zones, prevalence was lower in more dense eelgrass meadows, suggesting disease is suppressed in healthy, higher density meadows. These results underscore the value of subtidal eelgrass and meadows in cooler locations as refugia, indicate that cooling can suppress disease, and have implications for eelgrass conservation and management under future climate change scenarios.
National Science Foundation
climate change, climate refugia, eelgrass, Labyrinthula zosterae, marine disease, seagrass wasting disease
Urban and Regional Planning
Olivia J. Graham, Tiffany Stephens, Brendan Rappazzo, Corinne Klohmann, Sukanya Dayal, Emily M. Adamczyk, Angeleen Olson, Margot Hessing-Lewis, Morgan Eisenlord, Bo Yang, Colleen Burge, Carla P. Gomes, and Drew Harvell. "Deeper habitats and cooler temperatures moderate a climate-driven seagrass disease" Philosophical Transactions of the Royal Society B: Biological Sciences (2023). https://doi.org/10.1098/rstb.2022.0016