Studies on triploid oysters in Australia. VI. Gonad development in diploid and triploid Sydney rock oysters Saccostrea commercialis (Iredale and Roughley)

Cox, Elizabeth S; Smith, Matthew J.; Nell, John A.; Maguire, Greg B.

doi:10.1016/0022-0981(95)00147-6

Cited by 43 publications

(24 citation statements)

References 13 publications

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“…This pattern of disease is consistent with prior studies indicating that the disease is most severe in late winter and early spring (Roughley 1926, Nell 2001, 2007, and with anecdotal evidence from oyster growers that stock relocation must occur in late autumn to avoid disease onset , Nell 2001. Prior studies have shown that triploid, as opposed to diploid, Saccostrea glomerata cultivated in all but the most southern of NSW estuaries maintain condition throughout the winter months (Hand & Nell 1999) due to retarded gametogenesis (Cox et al 1996). In our study, we found that oyster condition score decreased in Georges River oysters during the winter months and that there was a significant, although modest, inverse correlation between the presence of histological lesions and oyster condition.…”

Section: Discussionsupporting

confidence: 47%

Longitudinal study of winter mortality disease in Sydney rock oysters Saccostrea glomerata

Spiers¹,

Gabor²,

Fell³

et al. 2014

Dis. Aquat. Org.

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Winter mortality (WM) is a poorly studied disease affecting Sydney rock oysters Saccostrea glomerata in estuaries in New South Wales, Australia, where it can cause significant losses. WM is more severe in oysters cultured deeper in the water column and appears linked to higher salinities. Current dogma is that WM is caused by the microcell parasite Bonamia roughleyi, but evidence linking clinical signs and histopathology to molecular data identifying bonamiasis is lacking. We conducted a longitudinal study between February and November 2010 in 2 estuaries where WM has occurred (Georges and Shoalhaven Rivers). Results from molecular testing of experimental oysters for Bonamia spp. were compared to clinical disease signs and histopathology. Available environmental data from the study sites were also collated and compared. Oyster condition declined over the study period, coinciding with decreasing water temperatures, and was inversely correlated with the presence of histological lesions. While mortalities occurred in both estuaries, only oysters from the Georges River study site showed gross clinical signs and histological changes characteristic of WM (lesions were prevalent and intralesional microcell-like structures were sometimes noted). PCR testing for Bonamia spp. revealed the presence of an organism belonging to the B. exitiosa−B. roughleyi clade in some samples; however, the very low prevalence of this organism relative to histological changes and the lack of reactivity of affected oysters in subsequent in situ hybridisation experiments led us to conclude that this Bonamia sp. is not responsible for WM. Another aetiological agent and a confluence of environmental factors are a more likely explanation for the disease.

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Section: Discussionsupporting

confidence: 47%

Longitudinal study of winter mortality disease in Sydney rock oysters Saccostrea glomerata

Spiers¹,

Gabor²,

Fell³

et al. 2014

Dis. Aquat. Org.

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“…Triploid oysters occasionally produced normal-looking eggs or sperm (however, always immobile) which is in contrast to the information supplied by Cox et al (1996) who never observed mature gametes. Although a detailed histological study was not done, it seemed that the oysters in my study showed more advanced gonadal development than those used in the study of Cox et al (1996).…”

Section: Patterns Of Reproduction and Growthmentioning

confidence: 62%

“…A very small sub-sample of the gonads was taken in order to determine the sex of each oyster (male, female, or unknown sex) and notes about the gonadal development were made. Triploid oyster showing gonadal development similar to that of diploid oysters were considered to be diploids (about 10-15% of all triploid individuals could be expected to be diploids (Cox et al 1996;Guo et al 1996; and omitted from further analysis. Tissues were dried for 48 h at 80C in a ventilated oven, cooled to room temperature in a desiccator and weighed to the nearest 0.01 mg. After weighing, tissues were ashed at 560C for 4 h. The crucibles containing ash were cooled to room temperature in a desiccator and weighed again.…”

Section: Methodsmentioning

confidence: 99%

“…Although there is some gonadal development and production of gametes (Allan and Downing 1986;Allan and Downing 1990;Cox et al 1996;Kiyomoto et al 1996;Ruiz-Verdugo et al 2000) or the production of viable offspring (Akashige 1990;Guo and Allan 1994a;RuizVerdugo et al 2000), the allocation of energy to reproduction is thought to be only minor compared to that of diploid oysters (Guo and Allan 1994a). Therefore, it was assumed that the oxygen consumed by triploid oysters only reflected the costs of growth and maintenance of somatic tissues.…”

Section: Introductionmentioning

confidence: 98%

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Physiological costs of reproduction in the Sydney rock oyster Saccostrea glomerata

Honkoop

2003

Oecologia

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In this study, triploid Sydney rock oysters Saccostrea glomerata, which do not reproduce and have only limited gonadal development, were used to calculate the cost of producing and maintaining somatic tissues. The consumption of oxygen was measured and converted to units of energy expended. The consumption of oxygen of diploid oysters, in different stages of the reproductive cycle, was also measured. Knowing the costs of producing and maintaining somatic tissues (obtained from the triploid oysters), it was possible to calculate the energy demand of somatic and reproductive tissues of diploid oysters. The focus of this study was to test whether this method would work, to investigate if this method would give results in accordance with modern life-history theory and to test hypotheses about costs of reproduction in oysters. It was found that in diploid oysters, 27% of the consumed oxygen was needed for reproductive processes. It was also found that the costs of production and maintenance of reproductive tissues were on average 84% of those of somatic tissues. Costs for the production and maintenance of somatic tissues decreased over time. Costs for reproduction also decreased, but were dependent on the stage of gonadal development. If the relative mass of gametes in the gonads was large, the costs were relatively small; if the mass was relatively small, the costs were large. Differences between traits of males and females were never significant, suggesting that reproductive effort and costs were similar in males and females. It was estimated that if diploid oysters did not reproduce, they could gain 64% more somatic ash-free dry mass. Thus, in terms of growth, reproduction is an expensive activity.

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“…Similarly, in studies of other species from Pakistan (C. rivularis, C. madrasensis, Saccostrea glomerata and S. cucculata), only 0.06% true hermaphroditism has been recorded (Asif 1979). In C. glomerata, 0.7% hermaphroditism has been recorded (Dinamani 1974), in S. commercialis 0.32% (Cox et al 1996), and in C. rhizophorae 0.5% (Nascimento et al 1980). Likewise, studies of the Pacific oyster C. gigas have also shown a relatively low incidence of hermaphroditism for yearling oysters, ranging between 0 and 1.1% recorded at a variety of different sites in Japan, the USA and Canada (Amemiya 1929, Berg 1969.…”

Section: Results Development Monitored Over Time -Growthmentioning

confidence: 99%

Long-term and transgenerational effects of nonylphenol exposure at a key stage in the development of Crassostrea gigas. Possible endocrine disruption?

Nice¹,

Morritt²,

Crane³

et al. 2003

Mar. Ecol. Prog. Ser.

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The widespread aquatic pollutant nonylphenol has been found to induce long-term and transgenerational effects in the Pacific oyster Crassostrea gigas that have not previously been reported. Evidence is provided demonstrating that when larvae are exposed to environmentally relevant concentrations of nonylphenol for a single 48 h exposure at a key stage in their development, long-term sexual developmental effects are induced. Data provided by this study suggest that exposure to 1 and 100 µg l -1 nonylphenol at Days 7 to 8 post-fertilization results in a change in the sex ratio towards females and an increase in the incidence of hermaphroditism (10 mo later, up to 30% of the resulting adults were fully functional hermaphrodites). Gamete viability is also affected, resulting in poor embryonic and larval development (up to 100% mortality) of the subsequent generation.

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Studies on triploid oysters in Australia. VI. Gonad development in diploid and triploid Sydney rock oysters Saccostrea commercialis (Iredale and Roughley)

Cited by 43 publications

References 13 publications

Longitudinal study of winter mortality disease in Sydney rock oysters Saccostrea glomerata

Longitudinal study of winter mortality disease in Sydney rock oysters Saccostrea glomerata

Physiological costs of reproduction in the Sydney rock oyster Saccostrea glomerata

Long-term and transgenerational effects of nonylphenol exposure at a key stage in the development of Crassostrea gigas. Possible endocrine disruption?

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