Dominance of Parasitic Neoparamoeba perurans in the Salmon Gill Environment

Amoebic gill disease (AGD) has hindered Atlantic salmon aquaculture in Tasmania for more the 30 years. The marine amoeba Neoparamoeba perurans causes AGD, however, many other amoebae colonise the gills and it is unknown whether they influence disease onset and severity.

Our study designed and applied new quantitative PCR assays to profile N. perurans and the accompanying amoeba species over a one-year period from two different Tasmanian farm sites. The survey aimed to identify relationships between specific amoeba taxa with spatial, temporal and pathological variables to infer the potential role these species play alongside N. perurans.

The project was part of an ongoing collaboration between CSIRO and the Marine Institute in Ireland. The team found that while a diversity of amoebae colonise the gills of AGD-affected farmed Atlantic salmon, N. perurans was the dominant species, and increasing N. perurans load on gills correlated with reduced gill health. The non-N. perurans species were minor players in the gill environment. However, there were times when N. perurans could not be detected and Nolandella spp. were highly prevalent on gills with low level of gill pathology.

The significance of Nolandella spp. in relation to AGD is not yet understood. These findings have been published in the journal Aquaculture Environment Interactions (2019, vol. 11) and forms the first molecular-based study to investigate the ecology of multiple amoeba species in association with AGD.

 

Article reference

English, C.J., Swords, F., Downes, J.K., Ruane, N.M., Botwright, N.A., Taylor, R.S., Barnes, A.C., Wynne, J.W., Lima, P.C., Cook, M.T., 2019. Prevalence of six amoeba species colonising the gills of farmed Atlantic salmon with amoebic gill disease (AGD) using qPCR. Aquac. Environ. Interact. 11, 405–415. https://doi.org/10.3354/aei00325

CSIRO Aquaculture contact

Chloe English, PhD Candidate, The University of Queensland/CSIRO