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Environmental risk factors associated with amoebic gill disease in cultured salmon (Salmo salar L.) smolts in Ireland

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)555–571
JournalJournal of Fish Diseases
Issue number10
Publication statusPublished - 12 Oct 2004


A 2-year study was carried out on amoebic gill disease (AGD) involving monthly samples of 1+ Atlantic salmon, Salmo salar L., smolts, histological assessment of the gills and analysis of environmental data. Gill pathology was seen before amoebae could be detected microscopically. These changes in gill integrity were associated with marine environmental conditions, particularly elevated ammonium, nitrite and chlorophyll levels. The results suggest that the environmental changes predispose salmon to colonization by amoebae and ciliates. High densities of histophagous scuticociliates were observed in the gills during periods of advanced gill pathology. A number of different amoebae were observed in close association with gill pathology. Neoparamoeba was not seen in high densities, nor was it associated with gill pathology, indicating that Neoparamoeba may not be the primary agent of the AGD in Irish salmonid culture.

    Research areas

  • Amoebic gill disease, Atlantic salmon, ciliates, environmental parameters, Neoparamoeba;, risk factors

ID: 16976051