Role of the Vibrio community, reproductive effort, and environmental parameters in intertidal Pacific oyster summer mortality in British Columbia, Canada

Cowan, M.W.; Pearce, Christopher M.; Finston, Terrie L.; Meyer, G.R.; Marshall, Richard S.; Evans, Wiley; Sutherland, T.F.; Bastide, Paul Y. de la

doi:10.1016/j.aquaculture.2022.739094

Cited by 13 publications

(10 citation statements)

References 65 publications

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“…Similar epidemics with mortality rates ranging from 20 to 100% were reported periodically in many regions of the world where the species is cultivated [10]. Intensive studies have been carried out to investigate the causative factors involved in the syndrome [11][12][13][14]. A strictly pathological explanation has not been defined, though collective evidence suggested that multiplex intrinsic and extrinsic factors and their interactions were responsible for the phenomenon [15][16][17].…”

Section: Introductionmentioning

confidence: 76%

“…have been frequently isolated from moribund Pacific oysters during the summer mortality events, which were suspected to be responsible for the mortality events [28,54,55]. For example, Vibrio splendidus and Vibrio aestuarianus were frequently identified in mortality events in France [51], V. alginolyticus was isolated in a mortality case reported in China [14,56], and V. harveyi was characterized in a mortality case that occurred in Australia [11]. In the present study, bacteria of the genus Vibrio were identified as the primary dominant strains in both hatcheries and open sea areas during 2020 and 2021 in China.…”

Section: Discussionmentioning

confidence: 99%

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Identification and Characterization of Infectious Pathogens Associated with Mass Mortalities of Pacific Oyster (Crassostrea gigas) Cultured in Northern China

Zhang

Huang

Zheng

et al. 2023

Biology

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The Pacific oyster (Crassostrea gigas) aquaculture industry increased rapidly in China with the introduction and promotion of triploid oysters in recent years. Mass mortalities affecting different life stages of Pacific oysters emerged periodically in several important production areas of Northern China. During 2020 and 2021, we conducted a passive two-year investigation of infectious pathogens linked to mass mortality. Ostreid herpesvirus-1 (OsHV-1) was detected to be associated with mass mortalities of hatchery larvae, but not juveniles and adults in the open sea. Protozoan parasites, such as Marteilia spp., Perkinsus spp. and Bonamia spp. were not detected. Bacterial isolation and identification revealed that Vibrio natriegens and Vibrio alginolyticus were the most frequently (9 out of 13) identified two dominant bacteria associated with mass mortalities. Pseudoalteromonas spp. was identified as the dominant bacteria in three mortality events that occurred during the cold season. Further bacteriological analysis was conducted on two representative isolates of V. natriegens and V. alginolyticus, designated as CgA1-1 and CgA1-2. Multisequence analysis (MLSA) showed that CgA1-1 and CgA1-2 were closely related to each other and nested within the Harveyi clade. Bacteriological investigation revealed faster growth, and more remarkable haemolytic activity and siderophore production capacity at 25 °C than at 15 °C for both CgA1-1 and CgA1-2. The accumulative mortalities of experimental immersion infections were also higher at 25 °C (90% and 63.33%) than at 15 °C (43.33% and 33.33%) using both CgA1-1 and CgA1-2, respectively. Similar clinical and pathological features were identified in samples collected during both naturally and experimentally occurring mortalities, such as thin visceral mass, discolouration, and connective tissue and digestive tube lesions. The results presented here highlight the potential risk of OsHV-1 to hatchery production of larvae, and the pathogenic role of V. natriegens and V. alginolyticus during mass mortalities of all life stages of Pacific oysters in Northern China.

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Section: Introductionmentioning

confidence: 76%

Section: Discussionmentioning

confidence: 99%

Identification and Characterization of Infectious Pathogens Associated with Mass Mortalities of Pacific Oyster (Crassostrea gigas) Cultured in Northern China

Zhang

Huang

Zheng

et al. 2023

Biology

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“…While events are primarily driven by high seawater temperatures (i.e. >19−20°C) (Green et al, 2019;Petton et al, 2021), there is a range of additional key contributory factors including reproductive status, genetics, growth and condition, and viral/bacterial pathogenic infection (Li et al, 2009;Barbosa Solomieu et al, 2015;Petton et al, 2021;Cowan et al, 2023). Other environmental factors, including low salinity events (Brown and Hartwick, 1988) and harmful algal blooms (Cassis et al, 2011), have also been associated with increased levels of mortality during the summer.…”

Section: Introductionmentioning

confidence: 99%

“…suspended culture) conditions where animals experience constant immersion and relatively stable growing conditions. The distinctive exposures associated with intertidal and deep-water culture environments drive contrasting magnitudes and frequencies of related stress responses with direct repercussions for growth/condition, reproduction, and survival (Cotter et al, 2010;Pernet et al, 2012Pernet et al, , 2014Petton et al, 2021;Cowan et al, 2023).…”

Section: Introductionmentioning

confidence: 99%

“…Vibrio) (King et al, 2019;Offret et al, 2020). As well, the reduced feeding duration of intertidal animals may result in lowered reproductive condition and reduced spawning, thus decreasing the stress associated with the latter (Cotter et al, 2010;Huvet et al, 2010;Cowan et al, 2023). In contrast, deep-water cultured animals may have to contend with an extended presence of seasonally-unfavorable seawater conditions that may be the result of environmental variations (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Development of a nature-based solution for mitigation of Pacific oyster summer mortality: use of the intertidal zone to improve resilience to environmental stressors

Mackenzie,

Raap,

Leduc

et al. 2024

Front. Mar. Sci.

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In recent years, Pacific oyster growers in British Columbia (BC), Canada have experienced devastating losses due to summer mortality syndrome. While anecdotal evidence suggests that intertidally-grown oysters may fare better during mass mortality events than deep-water counterparts, there remains a lack of research examining how different culture conditions may influence severity. To address this, we compared growth, condition, histopathology, reproductive status, and survival between intertidally- and deep-water-cultured oysters over 2 years at three oyster farms in Baynes Sound (BC). A reciprocal transplant was carried out after 1 year to test the use of the intertidal as a mechanism for promotion of physiological resilience prior to deep-water deployment. Field trial results showed significantly higher final survival in oysters transferred from the intertidal to deep water (83.5%) compared to those maintained in deep water (63.6%), but only at one farm, likely as a consequence of varying physical and/or biological characteristics associated with particular farm locations. Histopathology showed little role of disease with regards to varying survival among treatments, though higher occurrence of Viral Gametocytic Hypertrophy was observed in Year 1 oysters under deep-water (62.2%) versus intertidal (37.8%) conditions. Additionally, after 2 years, there was no significant difference in oyster size nor condition index between oysters transplanted from the intertidal to deep water and those solely cultured in deep water. A laboratory-challenge experiment determined significantly different survival curves of Year 1 intertidally- and deep-water-cultured oysters under immersion/emersion and warming conditions, with final survival of 88% and 64%, respectively, under conditions of high temperature (25°C) and immersion. Likewise, Year 2 (i.e. post-transfer) intertidally- and deep-water-cultured oysters showed significantly different survival curves under laboratory-based Vibrio challenge conditions (16°C) with final survival of 63% and 34%, respectively. Results suggest that partial culture in the intertidal at some farms may be an effective method for conferring resilience to summer mortality in Pacific oysters.

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Abundance of Vibrio aestuarianus, water temperature, and stocking density are associated with summer mortality of Pacific oysters in suspended culture

Cowan,

Pearce,

Green

et al. 2024

Aquacult Int

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High mortality rates of cultured Pacific oysters (Crassostrea gigas) during the summer months have regularly occurred on oyster farms in British Columbia, Canada over the last 10 years, but little is known about the microbial and environmental conditions that contribute to such mortality events. The objective of the study was to determine correlative factors associated with the onset of a summer mortality event in oysters (mean ± SD shell height: 14.2 ± 0.5 mm) grown in suspended culture at four stocking densities (150, 300, 450, 600 oysters tray−1) from May 11 to September 17, 2018. Variables examined included both biotic (oyster growth, mortality, reproductive development, and microbiome (approximately every week); Vibrio and harmful algal species abundance) and abiotic (temperature, salinity, turbidity, dissolved oxygen, pCO2, pH, and aragonite saturation) ones. Both the absolute abundance of V. aestuarianus and the relative abundance of Vibrio spp. increased with observed oyster mortality and declining health. Mortality was highest on August 12 and associated with a prior period of elevated temperatures (i.e., increasing temperatures from early July to early August) and increased oyster growth/reproductive development. At that time, systemic mixed microbial infections and necrotic gill tissue in histological cross sections were observed in 19% of oysters that appeared healthy macroscopically. Cumulative percent mortalities per tray ranged from 34 to 75%, the highest-density trays having significantly less mortality and smaller shell width, shell length, and gonad length than lower-density trays. This study demonstrates the significant impact of summer mortality on Pacific oysters and highlights the biotic (host growth, reproductive development, and microbiome composition as well as Vibrio spp. abundance) and abiotic (water temperature) factors associated with the observed mortality in this region.

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Role of the Vibrio community, reproductive effort, and environmental parameters in intertidal Pacific oyster summer mortality in British Columbia, Canada

Cited by 13 publications

References 65 publications

Identification and Characterization of Infectious Pathogens Associated with Mass Mortalities of Pacific Oyster (Crassostrea gigas) Cultured in Northern China

Identification and Characterization of Infectious Pathogens Associated with Mass Mortalities of Pacific Oyster (Crassostrea gigas) Cultured in Northern China

Development of a nature-based solution for mitigation of Pacific oyster summer mortality: use of the intertidal zone to improve resilience to environmental stressors

Abundance of Vibrio aestuarianus, water temperature, and stocking density are associated with summer mortality of Pacific oysters in suspended culture

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