Recruitment of the Pacific oyster Crassostrea gigas in a shellfish-exploited Mediterranean lagoon: discovery, driving factors and a favorable environmental window

Lagarde, Franck; D’Orbcastel, Emmanuelle Roque; Ubertini, Martin; Mortreux, Serge; Bernard, Ismaël; Fiandrino, Annie; Chiantella, Claude; Bakhouche, Béatrice; Roques, Cécile; Bonnet, Delphine; Miron, Gilles; Richard, Marion; Pouvreau, Stéphane; Lett, Christophe

doi:10.3354/meps12265

Cited by 22 publications

(33 citation statements)

References 90 publications

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“…heterotrophic prokaryote abundances increased while ciliate abundances decreased, thus exerting a lower top-down control on heterotrophic prokaryote. In the Thau lagoon, heterotrophic conditions limited the metamorphosis success of C. gigas (Lagarde et al 2017) which supports the idea that a shift toward heterotrophic system caused by filtration and mortality of oysters in excessive density may not favour sustainable development of shellfish culture.…”

Section: Accepted Manuscriptsupporting

confidence: 62%

Changes in planktonic microbial components in interaction with juvenile oysters during a mortality episode in the Thau lagoon (France)

et al. 2019

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Oysters modify the planktonic microbial community structure by their filtration and NH 4 excretion activities. While many studies have been conducted on this subject with adult oysters, none had been carried out in situ with juveniles. Pacific oyster juveniles (Magallana gigas, previously Crassostrea gigas) died massively all over the world since 2008 in relation with OsHV-1 infection. During mortality episodes, sick and dead oysters are not separated from healthy live ones, and left to decay in the surrounding environment, with unknown consequences for the nutrient cycle and planktonic microbial components (PMC). The present study aimed to elucidate for the first time the interactions between oyster juveniles and PMC during a mortality episode. Innovative 425-L pelagic chambers were deployed weekly in situ around oyster lanterns along a stocking-density gradient in the Thau Mediterranean lagoon (France) before, during and after an oyster mortality episode, from April to May 2015. This study reveals (i) significant changes of planktonic microbial community structure during mortality episodes, with a proliferation of picoplankton (<3 μm) and ciliates (Balanion sp., Uronema sp.) within 2 weeks when mortality rates and numbers of moribund juvenile oysters were highest. These changes were probably induced by oyster tissue leaching, decomposition and mineralization, which probably began during the moribund period, as suggested by an increase of PO 4 concentration and N:P ratio decrease, (ii) oyster juveniles mainly retained 3-20 μm plankton. In contrast to adults, picophytoplankton and small heterotrophic flagellates (<3 μm) were significantly depleted in the presence of oyster juveniles. Depletion of picoplankton occurred only at the starting of the mortality episode and during the moribund phase. (iii) Oyster juvenile filtration and mortality shifted the planktonic microbial structure toward a heterotrophic microbial system, where ciliates and heterotrophic flagellates acted as a trophic link between picoplankton and oysters. The next stage of our investigation is to examine the effect of a mortality episode on pathogen fluxes in the water column, exploring their relationships with planktonic Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.components and dead oyster flesh. Highlights► The planktonic microbial components (PMC) change during OsHV-1 oyster juvenile mortality. ► Picophytoplankton and ciliates increase during infection and mortality periods. ► Filtration and mortality of juvenile oysters shift PMC toward a heterotrophic system.

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Section: Accepted Manuscriptsupporting

confidence: 62%

Changes in planktonic microbial components in interaction with juvenile oysters during a mortality episode in the Thau lagoon (France)

et al. 2019

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“…In our case, monitoring in 2012, 2013 and 2014 revealed spatial and temporal patterns that had an environmental influence on different stages, i.e. spawning, settlement and metamorphosis (Lagarde et al 2017. This shows that the intrinsic ecological functioning of the lagoon combined with heterotrophic/mixotrophic vs. autotrophic regimes (Leruste et al 2016) can influence gametogenesis, spawning behavior, settlement of larvae, and hence recruitment success.…”

Section: Discussionmentioning

confidence: 53%

“…As reported by Lagarde et al (2017), young oyster abundances were estimated every two weeks at three different settler stages: pre-settled larvae (pediveliger), young postlarvae and newly settled juveniles (Arakawa 1990) from June to September in 2012, 2013 and 2014. An original method with a temporal overlap of collector deployment was used (Hughes et al 2000, Arnold & Steneck 2011.…”

Section: Abundance Of Young Settlers and Survival Rate At Metamorphosismentioning

confidence: 99%

“…The collectors were vertically submerged 2 m below the surface, suspended inside shellfish farming structures, or outside farming structures (see Figure 2(a) in Lagarde et al (2017) for more details). The systems were designed to support two sets of collectors immersed for two or four weeks.…”

Section: Abundance Of Young Settlers and Survival Rate At Metamorphosismentioning

confidence: 99%

“…The 3 purpose of our study was thus to test the hypothesis that the size of C. gigas at metamorphosis is linked to specific environmental/trophic conditions that may affect the success of subsequent recruitment. The Thau lagoon was selected to test this hypothesis because of its high temporal and spatial ecological heterogeneity that affect oyster recruitment (Lagarde et al 2017).…”

Section: Introductionmentioning

confidence: 99%

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Trophic environments influence size at metamorphosis and recruitment performance of Pacific oysters

Lagarde¹,

Richard²,

Bakhouche³

et al. 2018

Mar. Ecol. Prog. Ser.

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Reproduction and recruitment of benthic invertebrates are influenced by the climate and by the ecological structure of marine ecosystems, along with local anthropogenic pressures such as eutrophication or oligotrophication. Using the Pacific oyster Crassostrea gigas as a biological model, we tested the hypothesis that the variability in prodissoconch II (PII) size (i.e. size at metamorphosis) depends on ecological functioning. Settlement and recruitment were assessed at 5 sampling sites on the French Mediterranean shellfish farmed Thau lagoon during the main summer recruitment events in 3 consecutive years (2012-2014). Hydrobiological and planktonic analyses were conducted at 3 sampling sites. Our results showed that recruitment was extremely heterogeneous, ranging from 0 to 260 ± 27 SE ind. dm-2 throughout the ecosystem and was linked with variability in PII size, which ranged from 180 to 296 µm. The annual temporal pattern of PII sizes appeared to be controlled by temperature during the settlement period, whereas the spatial pattern depended on phytoplankton biomass and on the trophic functioning of the ecosystem. Smaller PII sizes were significantly correlated with the highest phytoplankton biomass, while larger PII sizes were positively correlated with mixotrophic cryptophyte abundance. We found an inverse relationship between PII size and survival after metamorphosis, showing that recruitment success was associated with smaller PII sizes. Regional climate conditions and local trophic functioning appear to be key factors in metamorphosis and consequently contribute to recruitment heterogeneity. Further studies should be performed in other ecosystems following an oligotrophication trajectory to generalize this result.

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Pull the trigger: interplay between benthic and pelagic cues driving the early recruitment of a natural bivalve assemblage

et al. 2022

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Recruitment of the Pacific oyster Crassostrea gigas in a shellfish-exploited Mediterranean lagoon: discovery, driving factors and a favorable environmental window

Cited by 22 publications

References 90 publications

Changes in planktonic microbial components in interaction with juvenile oysters during a mortality episode in the Thau lagoon (France)

Changes in planktonic microbial components in interaction with juvenile oysters during a mortality episode in the Thau lagoon (France)

Trophic environments influence size at metamorphosis and recruitment performance of Pacific oysters

Pull the trigger: interplay between benthic and pelagic cues driving the early recruitment of a natural bivalve assemblage

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