MEPS 226:265-271 (2002)  -  doi:10.3354/meps226265

Impact of the wasting disease pathogen, Labyrinthula zosterae, on the photobiology of eelgrass Zostera marina

Peter J. Ralph1,*, Frederick T. Short2

1Institute for Water and Environmental Resource Management, University of Technology, Sydney, PO Box 123, Broadway New South Wales 2007 Australia
2Jackson Estuarine Laboratory, University of New Hampshire, 85 Adams Point Road, Durham, New Hampshire 03824, USA

ABSTRACT: Labyrinthula zosterae is clearly shown to be a primary pathogen of eelgrass Zostera marina L., not merely a secondary infection of senescent leaves or an indication of decomposition. The results of this investigation using a Diving-PAM fluorometer indicate that the regions of tissue photosynthetically compromised by Labyrinthula are substantially larger than previously thought. Labyrinthula moves through Zostera marina tissue at a rate of up to 0.8 mm h-1 during daylight periods. The photosynthetic efficiency of apparently healthy green leaf tissue can be reduced by almost 50% in areas up to 3 mm from a necrotic region infected with Labyrinthula. Once a necrotic spot expands to bisect the eelgrass leaf, the condition of all acropetal tissue is diminished; leaf tissue up to 5 cm away has severely reduced photosynthetic activity.


KEY WORDS: Eelgrass · Zostera marina · Slime mold · Labyrinthula · Seagrass · Protist · Wasting disease


Full text in pdf format