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Microbiological aspects of an oyster (Crassostrea gigas ) hatchery, with special reference to larval mortalities

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Lewis, Thomas E (1991) Microbiological aspects of an oyster (Crassostrea gigas ) hatchery, with special reference to larval mortalities. Research Master thesis, University of Tasmania.

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Abstract

Investigations of the cause/s of larval mortalities at a commercial
Pacific oyster '(Crassostrea gigas ) hatchery in Tasmania, Australia, were
carried out during successive production seasons. Epidemiological
evidence suggested that cultures of microalgae, harvested semicontinuously
as food for larval oysters (Crassostrea gigas ) were the major
vectors for transmission of bacterial disease. There was no evidence that
bacteria associated with intake seawater, fertilised eggs or hatchery fomites
(biofilmed surfaces) caused larval losses, or that non-bacteriological
factors (eg. nutrition, gene pool, heavy metal contamination) were
responsible for larval mortalities. All microalgal clones (Isochrysis sp.
clone T. Iso., Chroomonas salina Butcher 3C, Thalassiosira pseudonana
Hasle et Heimdal 3H, Chaetoceros calcitrans Paulsen, Dunaliella salina
Butcher, Pavlova (Monochrysis ) lutheri Droop, Tetraselmis suecica
Butcher)used as food for larvae, were implicated in the transmission of disease.
It was apparent that mixed, rather than single, bacterial biotypes were
responsible for disease. Bacteria cultured from moribund larvae rarely
included presumptive Vibrio or Flavobacterium /Cytophaga spp., and
never red-pigmented Pseudomonas spp .

Item Type: Thesis (Research Master)
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Date Deposited: 02 Feb 2010 05:56
Last Modified: 11 Mar 2016 05:55
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