Incidence of Eelgrass Wasting Disease at Point Reyes and San Francisco Bay sites
Author: Kaz Davila
Faculty Supervisor: Sarah Cohen
Department: Biology
Eelgrass (Zostera marina) provides important ecosystem services filtering pathogens, serving as a carbon sink, and providing habitat for fisheries species. Labyrinthula zosterae (Laby), seagrass wasting disease, spreads via blade-to-blade contact. Laby produces dark lesions on blades which negatively affect Z. marina photosynthesis and leads to blade degradation. Historically, the spread of Laby has resulted in worldwide large eelgrass die-offs. A National Park Service (NPS) successful passive eelgrass restoration project in Drakes Estero removed abandoned debris that interfered with eelgrass populations. Following debris removal, beds have passively regrown, but less so in areas that required greater excavation (Major Debris). Local research has indicated higher levels of Laby in denser beds at Drakes Estero in comparison to San Francisco Bay sites. Laby lesions from Major Debris and Control transects at Drakes Estero restoration sites were compared. These subtidal blades were assessed for lesion coverage using photographs and ImageJ analysis. Z. marina beds from the Control transects were predicted to have higher wasting disease lesions as there is greater chance of blade-to-blade contact due to higher bed density. In this case, managing density during restorations could be an important strategy for disease control and could benefit future Z. marina repopulation efforts.