scholarly journals A Naïve Population of European Oyster Ostrea edulis with Reduced Susceptibility to the Pathogen Bonamia ostreae: Are S-Strategy Life Traits Providing Protection?

2020 ◽  
Vol 60 (2) ◽  
pp. 249-260
Author(s):  
Sian Egerton ◽  
Sharon A Lynch ◽  
Maria Prado-Alvarez ◽  
Grace Flannery ◽  
Elaine Brennan ◽  
...  
Keyword(s):  
Immune Function ◽  
Multiple Testing ◽  
Marine Organism ◽  
Empirical Support ◽  
Ostrea Edulis ◽  
High Fecundity ◽  
Age Cohorts ◽  
Life Traits ◽  
Bonamia Ostreae ◽  
Triangle Theory

Synopsis European populations of the native flat oyster, Ostrea edulis, have been heavily depleted by two protozoan parasites, Marteila refringens and Bonamia ostreae, with mortalities of up to 90% reported in naïve populations. However, in studies carried out over a 10-year period, researching the parasite–host relationship of B. ostreae and O. edulis in several age cohorts within a naïve O. edulis population from Loch Ryan (LR), Scotland, 1364 specimens were challenged and only 64 (5%), across multiple testing protocols, screened positive for B. ostreae. This article presents a case for the development of S-strategy life traits in the LR population that coincide with enhanced immune function and survival. Oysters are considered typical r-strategists (small in size with fast development and high fecundity) while S-strategists, as outlined in Grime’s (1977) competitor–stress tolerant–ruderal (C–S–R) triangle theory, are characterized by slow growth and investment in the durability of individuals. This study hypothesizes that slower growth and reduced reproductive output in LR oysters has resulted in the investment of an enhanced immune function and reduced susceptibility to B. ostreae that is, r-strategists with S-strategy life traits equates to protection from significant pathogens. The findings presented here within provide a strong case study for local adaptation of energy allocation and provides empirical support for the C–S–R triangle theory in a marine organism.

Conservation biology of marine fishes: perceptions and caveats regarding assignment of extinction risk

2001 ◽  
Vol 58 (1) ◽  
pp. 108-121 ◽  
Author(s):  
Jeffrey A Hutchings
Keyword(s):  
Population Size ◽  
Extinction Risk ◽  
Population Decline ◽  
Empirical Support ◽  
Marine Fishes ◽  
Marine Biodiversity ◽  
Population Declines ◽  
High Fecundity ◽  
Reproductive Rates ◽  
Biological Extinction

Quantitative criteria used to assign species to categories of extinction risk may seriously overestimate these risks for marine fishes. Contemporary perception is that marine fishes may be less vulnerable to extinction than other taxa, because of great natural variability in abundance, high fecundity, rapid population growth, and an intrinsically high capability of recovering from low population size. Contrary to perception, however, there appears to be generally little theoretical or empirical support for the hypotheses that marine fish are more likely to experience large reductions in population size, to produce unusually high levels of recruitment, to have higher reproductive rates, or to recover more rapidly from prolonged population declines than nonmarine fishes. Although existing population-decline criteria may not accurately reflect probabilities of biological extinction, they do appear to reflect the converse-population recovery. Insufficient support for contemporary perceptions of their susceptibility to extinction, coupled with caveats associated with the assignment of extinction risk, suggest that significant increases in the population-decline thresholds used to assign marine fishes to at-risk categories would be inconsistent with a precautionary approach to fisheries management and the conservation of marine biodiversity.

scholarly journals A non-lethal method for detection of Bonamia ostreae in flat oyster (Ostrea edulis) using environmental DNA

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Louise von Gersdorff Jørgensen ◽  
Johan Wedel Nielsen ◽  
Mikkel Kehler Villadsen ◽  
Bent Vismann ◽  
Sussie Dalvin ◽  
...  
Keyword(s):  
Water Samples ◽  
Sea Water ◽  
Diagnostic Technique ◽  
Environmental Dna ◽  
Detection Methods ◽  
Ostrea Edulis ◽  
Breeding Programs ◽  
Bonamia Ostreae ◽  
Flat Oyster ◽  
Selection Of

Abstract Surveillance and diagnosis of parasitic Bonamia ostreae infections in flat oysters (Ostrea edulis) are prerequisites for protection and management of wild populations. In addition, reliable and non-lethal detection methods are required for selection of healthy brood oysters in aquaculture productions. Here we present a non-lethal diagnostic technique based on environmental DNA (eDNA) from water samples and demonstrate applications in laboratory trials. Forty oysters originating from Limfjorden, Denmark were kept in 30 ppt sea water in individual tanks. Water was sampled 6 days later, after which all oysters were euthanized and examined for infection, applying PCR. Four oysters (10%) were found to be infected with B. ostreae in gill and mantle tissue. eDNA purified from the water surrounding these oysters contained parasite DNA. A subsequent sampling from the field encompassed 20 oysters and 15 water samples from 5 different locations. Only one oyster turned out positive and all water samples proved negative for B. ostreae eDNA. With this new method B. ostreae may be detected by only sampling water from the environment of isolated oysters or isolated oyster populations. This non-lethal diagnostic eDNA method could have potential for future surveys and oyster breeding programs aiming at producing disease-free oysters.

Interactions between Ostrea edulis galectin (OE-GAL) and the protozoan parasite Bonamia ostreae

2013 ◽  
Vol 34 (6) ◽  
pp. 1674 ◽  
Author(s):  
M. Prado-Alvarez ◽  
B. Chollet ◽  
N. Faury ◽  
M. Robert ◽  
B. Morga ◽  
...  
Keyword(s):  
Protozoan Parasite ◽  
Ostrea Edulis ◽  
Bonamia Ostreae

Histopathology and a real-time PCR assay for detection of Bonamia ostreae in Ostrea edulis cultured in western Canada

Aquaculture ◽  
2006 ◽  
Vol 261 (1) ◽  
pp. 33-42 ◽  
Author(s):  
Gary D. Marty ◽  
Susan M. Bower ◽  
Kyle R. Clarke ◽  
Gary Meyer ◽  
Geoff Lowe ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Western Canada ◽  
Ostrea Edulis ◽  
Pcr Assay ◽  
Bonamia Ostreae

scholarly journals Influence of parentage upon growth in Ostrea edulis: evidence for inbreeding depression

2000 ◽  
Vol 76 (2) ◽  
pp. 159-168 ◽  
Author(s):  
YAMAMA NACIRI-GRAVEN ◽  
SOPHIE LAUNEY ◽  
NICOLAS LEBAYON ◽  
ANDRE GERARD ◽  
JEAN-PIERRE BAUD
Keyword(s):  
Inbreeding Depression ◽  
Genetic Relatedness ◽  
Protozoan Parasite ◽  
Control Population ◽  
Ostrea Edulis ◽  
The Family ◽  
Bonamia Ostreae ◽  
Sib Families ◽  
The Mean ◽  
Selection For

Genetic variability for growth was analysed in three populations of Ostrea edulis, selected for resistance to the protozoan parasite Bonamia ostreae. This study was undertaken first to determine the potential for selection for growth in populations that have never been selected for this character, and second to estimate heterosis versus inbreeding depression. Growth was monitored in culture for 10 months. The selected populations (namely S85-G3, S89I-G2 and S89W-G2), their crossbred population and a control population were composed of full-sib families whose parents were already genotyped using five microsatellite markers. This genotyping allowed the estimation of genetic relatedness among pairs of parents. The parents' relatedness was then correlated with the growth performance of their offspring within each of the three populations, and inbreeding depression was estimated. The population effect for growth was highly significant, with the crossbred population having the highest growth rate, followed by S89I-G2 and S89W-G2, S85-G3 and the control population. The within-populations family effect was also highly significant, indicating, as well as the high value for heritability at the family level (between 0·57 and 0·92), that a potential for a further selection for growth still exists within the three populations. Estimates of inbreeding depression (relative to the mean, for complete inbreeding) were high (1 for S891-G2, 0·44 for S89W-G2 and between 0·02 and 0·43 for S85-G3), which correlates with the apparent heterosis for growth observed in the crossbred population. These results are discussed in the context of the future management of the selected populations.

Examining the predictors of fraud in state-owned enterprises: an application of the fraud triangle theory

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Godfred Matthew Yaw Owusu ◽  
Theodora Aba Abekah Koomson ◽  
Stanley Agbenya Alipoe ◽  
Yusuf Ahmed Kani
Keyword(s):  
Structural Equation ◽  
Empirical Support ◽  
Partial Least Square ◽  
Least Square ◽  
Fraud Triangle ◽  
Data Collection Tool ◽  
Content Type ◽  
The Public ◽  
Triangle Theory ◽  
The Empirical Analysis

Purpose This paper aims to investigate the views of employees on the motives behind frequently reported fraudulent activities at the workplace. Using the fraud triangle theory (FTT) as the theoretical lens, the study examines the effect of pressure, opportunity and rationalization on fraudulent acts by employees at the workplace. Design/methodology/approach The study follows a correlational quantitative approach using questionnaires as the main data collection tool. A total of 243 valid responses from employees working in different state-owned enterprises in Ghana were used in the empirical analysis. The hypothesized relationships of the study were tested using the partial least square-structural equation modelling technique. Findings The results from the structural analysis showed that pressure, rationalization and opportunity are important in explaining why employees engage in fraudulent activities at the workplace. Originality/value The findings do not only provide empirical support for the applicability of the FTT in the Ghanaian context but most importantly offer some useful insights into the fraud discourse from the public sector workers’ perspective.

Interlaboratory variability in screening for Bonamia ostreae, a protistan parasite of the European flat oyster Ostrea edulis

2014 ◽  
Vol 110 (1) ◽  
pp. 93-99 ◽  
Author(s):  
G Flannery ◽  
SA Lynch ◽  
M Longshaw ◽  
D Stone ◽  
P Martin ◽  
...  
Keyword(s):  
Ostrea Edulis ◽  
Interlaboratory Variability ◽  
Bonamia Ostreae ◽  
Flat Oyster

scholarly journals Characterization of actin genes in Bonamia ostreae and their application to phylogeny of the Haplosporidia

Parasitology ◽  
2007 ◽  
Vol 134 (14) ◽  
pp. 1941-1948 ◽  
Author(s):  
I. LÓPEZ-FLORES ◽  
V. N. SUÁREZ-SANTIAGO ◽  
D. LONGET ◽  
D. SAULNIER ◽  
B. CHOLLET ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Protozoan Parasite ◽  
Ostrea Edulis ◽  
Coding Region ◽  
Actin Genes ◽  
Bonamia Ostreae ◽  
Flat Oyster ◽  
Primer Sets ◽  
Systemic Infections

SUMMARYBonamia ostreae is a protozoan parasite that infects the European flat oyster Ostrea edulis, causing systemic infections and resulting in massive mortalities in populations of this valuable bivalve species. In this work, we have characterized B. ostreae actin genes and used their sequences for a phylogenetic analysis. Design of different primer sets was necessary to amplify the central coding region of actin genes of B. ostreae. Characterization of the sequences and their amplification in different samples demonstrated the presence of 2 intragenomic actin genes in B. ostreae, without any intron. The phylogenetic analysis placed B. ostreae in a clade with Minchinia tapetis, Minchinia teredinis and Haplosporidium costale as its closest relatives, and demonstrated that the paralogous actin genes found in Bonamia resulted from a duplication of the original actin gene after the Bonamia origin.

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