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The health status of two species of Tasmanian farmed shellfish, Crassostrea gigas (thunberg, 1793) and Ostrea angasi (Sowerby, 1871).

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Wilson, JR (1993) The health status of two species of Tasmanian farmed shellfish, Crassostrea gigas (thunberg, 1793) and Ostrea angasi (Sowerby, 1871). Research Master thesis, University of Tasmania..

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Abstract

A project to assess the health of Tasmania's farmed shellfish was conducted
during the period October 1990 - June 1992. A total of 5290 Pacific oysters
(Crassostrea gigas) and 630 flat oysters (Ostrea angasi) were collected during the
program which involved near-monthly collections of shellfish from each of four
growing areas in Tasmania. Pacific oysters were free of any prescribed or
potential pathogen. Flat oysters were found to be infected with a serious
pathogen, Bonamia sp, and a viral inclusion of unknown significance. Histological
examination of these samples revealed the presence of low numbers of commensal
organisms in the tissues.of both species of oyster. Pacific oysters were infected
with a viral infection of the gametes, rickettsia1 inclusions, two species of ciliates,
two protozoans of unknown taxonomy, a turbellarian and two types of copepods.
Flat oysters were infected with rickettsia1 inclusions, a ciliate and two types of
copepod. Three species of spionid polychaetes were dissected from shellblisters
affecting Pacific oysters. Changes in histological appearance of Pacific oysters
including changes in the leydig tissue, the types and degree of infiltration of
haemocytes and atrophy of digestive tubules show some seasonal trends and ire
correlated to the gonadal stage of the oyster. Also, digestive tubule atrophy and
abundance of brown cells are correlated with lower salinity.

Item Type: Thesis (Research Master)
Date Deposited: 23 Feb 2009 04:37
Last Modified: 11 Mar 2016 05:55
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