Occurrence of wasting disease in <i>Zostera noltii</i>

Zostera noltii Hornem. did not decline in the 1930s when wasting disease destroyed many beds of Zostera marina L. It appears, however, that wasting disease occurs also in Z. noltii. A census of herbarium specimens kept in the Rijksherbarium, Leiden, showed that a small number of diseased specimens have been collected from the middle of the 19th century onwards. In all west European populations investigated in 1989 and 1990, at least a few specimens were found with wasting disease-like damage patterns. A laboratory experiment showed that the sensitivity of Z. noltii to contact infection is similar to that of Z. marina. The causing agent, Labyrinthula P, has been isolated from Z. noltii.