The letter refers to a specimen of Z. angustifolia, which D. Seaward sent to den Hartog for analysis of disease. den Hartog mentions that Z. angustifolia is thought to be an ecological variant of Zostera marina. The specimen from the Fleet was diseased, with Labyrinthula lesions. This disease had been recorded from specimens from the Fleet on other occasions and in 1934 and the 1970=s. Wasting disease (caused by Labyrinthula) has been found in eelgrass not subject to an epidemic of the disease, and it is thought that an epidemic could be caused by stress to the plants, such as too little light or too high temperatures.

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