Meeting Abstract
Seagrasses are marine angiosperms that are important primary producers in temperate estuarine and marine ecosystems worldwide, forming ecologically and economically valuable meadows. Of the five species found in the Pacific Northwest of the United States, common eelgrass (Zostera marina) is one of the most widely studied. A marine slime mold, Labyrinthula zosterae is the causative agent for eelgrass wasting disease and is one of the primary causes of declines in seagrass beds. Labrinthula is an opportunistic pathogen that persists in eelgrass beds throughout the world, although it has primarily been studied in shallow, intertidal eelgrass beds. We conducted field and lab analyses to determine the prevalence and severity of wasting disease in intertidal and subtidal Z. marina beds from four sites throughout the San Juan Islands, Washington. By quantifying the diseased tissue on 417 intertidal blades and 480 subtidal blades, we found that subtidal beds had significantly more diseased eelgrass blades than intertidal beds. Furthermore, we determined that depths strongly influenced the severity of wasting disease. Collectively, these data suggest that subtidal beds are more conducive to Labyrinthula growth. This study highlights the need for further marine epidemiological studies to determine what factors may allow Labyrinthula to persist more in subtidal beds than in intertidal eelgrass beds.
