Perspectives on the wasting disease of eelgrass Zostera marina

Abstract

Early in the 1930's a major epidemic decimated populations of eelgrass Zostera manna L. along the Atlantic coast of North America and Europe. Over 90 % of the eelgrass populations disap- peared, resulting in dramatic changes within the coastal ecosystem. There was much speculation about the possible causes of the wasting disease ranging from pathogen~c microorganisms to abiotic factors including changes in temperature, precipitation, salinity, and pollution In a critical review of the Literature, substantial research supported the view that a specles of the genus Labyrinthula, a marine slime mold, was the primary causative agent of the epidemic dlsease This hypothesis was consistently supported by data collected throughout the range of diseased eelgrass populations. In the present recurrence of eelgrass wasting disease, a pathogenic species, Labyrinthula zosterae has been identified as the causative agent of the disease. Similarities of past and present wasting disease episodes further support the hypothesis that Labyrinthula is the primary etiological agent.