The Experts below are selected from a list of 3549 Experts worldwide ranked by ideXlab platform
Gilles Le Moullac - One of the best experts on this subject based on the ideXlab platform.
-
microplastics induce dose specific transcriptomic disruptions in energy metabolism and immunity of the pearl oyster pinctada Margaritifera
Environmental Pollution, 2020Co-Authors: Tony Gardon, Gilles Le Moullac, Claude Soyez, Arnaud Huvet, Lucie Morvan, Virgile Quillien, J. Le LuyerAbstract:Abstract A combined approach integrating bioenergetics and major biological activities is essential to properly understand the impact of microplastics (MP) on marine organisms. Following experimental exposure of polystyrene microbeads (micro-PS of 6 and 10 μm) at 0.25, 2.5, and 25 μg L−1, which demonstrated a dose-dependent decrease of energy balance in the pearl oyster Pinctada Margaritifera, a transcriptomic study was conducted on mantle tissue. Transcriptomic data helped us to decipher the molecular mechanisms involved in P. Margaritifera responses to micro-PS and search more broadly for effects on energetically expensive maintenance functions. Genes related to the detoxification process were impacted by long-term micro-PS exposure through a decrease in antioxidant response functioning, most likely leading to oxidative stress and damage, especially at higher micro-PS doses. The immune response was also found to be dose-specific, with a stress-related activity stimulated by the lowest dose present after a 2-month exposure period. This stress response was not observed following exposure to higher doses, reflecting an energy-limited capacity of pearl oysters to cope with prolonged stress and a dramatic shift to adjust to pessimum conditions, mostly limited and hampered by a lowered energetic budget. This preliminary experiment lays the foundation for exploring pathways and gene expression in P. Margaritifera, and marine mollusks in general, under MP exposure. We also propose a conceptual framework to properly assess realistic MP effects on organisms and population resilience in future investigations.
-
Microplastics induce dose-specific transcriptomic disruptions in energy metabolism and immunity of the pearl oyster Pinctada Margaritifera
Environmental Pollution, 2020Co-Authors: Tony Gardon, Gilles Le Moullac, Claude Soyez, Arnaud Huvet, Lucie Morvan, Virgile Quillien, Jeremy Le LuyerAbstract:A combined approach integrating bioenergetics and major biological activities is essential to properly understand the impact of microplastics (MP) on marine organisms. Following experimental exposure of polystyrene microbeads (micro-PS of 6 and 10 mu m) at 0.25, 2.5, and 25 mu g L-1, which demonstrated a dose-dependent decrease of energy balance in the pearl oyster Pinctada Margaritifera, a transcriptomic study was conducted on mantle tissue. Transcriptomic data helped us to decipher the molecular mechanisms involved in P. Margaritifera responses to micro-PS and search more broadly for effects on energetically expensive maintenance functions. Genes related to the detoxification process were impacted by long-term micro-PS exposure through a decrease in antioxidant response functioning, most likely leading to oxidative stress and damage, especially at higher micro-PS doses. The immune response was also found to be dose-specific, with a stress-related activity stimulated by the lowest dose present after a 2-month exposure period. This stress response was not observed following exposure to higher doses, reflecting an energy-limited capacity of pearl oysters to cope with prolonged stress and a dramatic shift to adjust to pessimum conditions, mostly limited and hampered by a lowered energetic budget. This preliminary experiment lays the foundation for exploring pathways and gene expression in P. Margaritifera, and marine mollusks in general, under MP exposure. We also propose a conceptual framework to properly assess realistic MP effects on organisms and population resilience in future investigations. (C) 2020 The Authors. Published by Elsevier Ltd.
-
impact of spat shell colour selection in hatchery produced pinctada Margaritifera on cultured pearl colour
Aquaculture Reports, 2018Co-Authors: Manaarii Sham Koua, Gilles Le MoullacAbstract:Beaded cultured pearl farming is a lengthy aquaculture process, particularly when the pearl oysters are produced through a hatchery propagation system, and includes the key steps of artificial breeding, larval and spat rearing before graft operations can take place. Within its genus, Pinctada Margaritifera has the ability to produce the widest range of pearl colours, thanks to the donor colour polymorphism of the inner shell, which is mainly responsible for colour transmission. As hatchery spat production in P. Margaritifera leads to several colour phenotypes (at 3 months old), the aim of this study was to determine whether a relation exists between the colour of the donors as spat and the final pearl colour. In the experiment, which took place over a four-year period, earlier spat colour selection was applied to two hatchery-produced P. Margaritifera families. The spat were traced and then used as donors at the adult stage. A total of 1100 experimental grafts were made, using originally grey, green, red and yellow spat phenotypes as donors. The results showed that all spat colour phenotypes mainly produced pearls in the moderately dark (78.4%) and grey colour (56.7%) classes. Differences in darkness level were produced by red and yellow spat, whose pearls were about twice as pale as those from the grey and green phenotypes. Concerning the pearl colour categories, the results showed that the attractive green/blue pearls were obtained twice as often when using grey and green spat phenotypes and that aubergine/peacock pearls were obtained four times more often by using the red and yellow spat phenotypes. This preliminary study suggests that earlier phenotypic colour selection could be applied in P. Margaritifera spat as a useful indicator in both pearl production cycles and family selection for donor oyster lines of specific colour propagation.
-
Molecular Signatures Discriminating the Male and the Female Sexual Pathways in the Pearl Oyster Pinctada Margaritifera
PLoS ONE, 2015Co-Authors: Vaihiti Teaniniuraitemoana, Peva Levy, Yannick Gueguen, Arnaud Huvet, Nabila Gaertner-mazouni, Gilles Le MoullacAbstract:The genomics of economically important marine bivalves is studied to provide better understanding of the molecular mechanisms underlying their different reproductive strategies. The recently available gonad transcriptome of the black-lip pearl oyster Pinctada Margaritifera is a novel and powerful resource to study these mechanisms in marine mollusks displaying hermaphroditic features. In this study, RNAseq quantification data of the P. Margaritifera gonad transcriptome were analyzed to identify candidate genes in histologically-characterized gonad samples to provide molecular signatures of the female and male sexual pathway in this pearl oyster. Based on the RNAseq data set, stringent expression analysis identified 1,937 contigs that were differentially expressed between the gonad histological categories. From the hierarchical clustering analysis, a new reproduction model is proposed, based on a dual histo-molecular analytical approach. Nine candidate genes were identified as markers of the sexual pathway: 7 for the female pathway and 2 for the male one. Their mRNA levels were assayed by real-time PCR on a new set of gonadic samples. A clustering method revealed four principal expression patterns based on the relative gene expression ratio. A multivariate regression tree realized on these new samples and validated on the previously analyzed RNAseq samples showed that the sexual pathway of P. Margaritifera can be predicted by a 3-gene-pair expression ratio model of 4 different genes: pmarg-43476, pmarg-foxl2, pmarg-54338 and pmarg-fem1-like. This 3-gene-pair expression ratio model strongly suggests only the implication of pmarg-foxl2 and pmarg-fem1-like in the sex inversion of P. Margaritifera. This work provides the first histo-molecular model of P. Margaritifera reproduction and a gene expression signature of its sexual pathway discriminating the male and female pathways. These represent useful tools for understanding and studying sex inversion, sex differentiation and sex determinism in this species and other related species for aquaculture purposes such as genetic selection programs.
-
gonad transcriptome analysis of pearl oyster pinctada Margaritifera identification of potential sex differentiation and sex determining genes
BMC Genomics, 2014Co-Authors: Vaihiti Teaniniuraitemoana, Arnaud Huve, Peva Levy, Emeline Lhuillie, Nabila Gaertnermazouni, Yannick Guegue, Christophe Klopp, Gilles Le MoullacAbstract:Black pearl farming is based on culture of the blacklip pearl oyster Pinctada Margaritifera (Mollusca, lophotrochozoa), a protandrous hermaphrodite species. At first maturation, all individuals are males. The female sex appears progressively from two years old, which represents a limitation for broodstock conditioning for aquaculture production. In marine mollusks displaying hermaphroditic features, data on sexual determinism and differentiation, including the molecular sex determining cascade, are scarce. To increase genomic resources and identify the molecular mechanisms whereby gene expression may act in the sexual dimorphism of P. Margaritifera, we performed gonad transcriptome analysis. The gonad transcriptome of P. Margaritifera was sequenced from several gonadic samples of males and females at different development stages, using a Next-Generation-Sequencing method and RNAseq technology. After Illumina sequencing, assembly and annotation, we obtained 70,147 contigs of which 62.2% shared homologies with existing protein sequences, and 9% showed functional annotation with Gene Ontology terms. Differential expression analysis identified 1,993 differentially expressed contigs between the different categories of gonads. Clustering methods of samples revealed that the sex explained most of the variation in gonad gene expression. K-means clustering of differentially expressed contigs showed 815 and 574 contigs were more expressed in male and female gonads, respectively. The analysis of these contigs revealed the presence of known specific genes coding for proteins involved in sex determinism and/or differentiation, such as dmrt and fem-1 like for males, or foxl2 and vitellogenin for females. The specific gene expression profiles of pmarg-fem1-like, pmarg-dmrt and pmarg-foxl2 in different reproductive stages (undetermined, sexual inversion and regression) suggest that these three genes are potentially involved in the sperm-oocyte switch in P. Margaritifera. The study provides a new transcriptomic tool to study reproduction in hermaphroditic marine mollusks. It identifies sex differentiation and potential sex determining genes in P. Margaritifera, a protandrous hermaphrodite species.
Paul C Southgate - One of the best experts on this subject based on the ideXlab platform.
-
Genome-wide comparisons reveal evidence for a species complex in the black-lip pearl oyster Pinctada Margaritifera (Bivalvia: Pteriidae)
Scientific Reports, 2018Co-Authors: Paul C Southgate, Dean R Jerry, Kyall R. ZengerAbstract:Evolutionary relationships in the black-lip pearl oyster Pinctada Margaritifera which is highly valued for pearl production remain poorly understood. This species possesses an 18,000 km Indo-Pacific natural distribution, and its current description includes six subspecies defined exclusively on morphological characters. To evaluate its taxonomic identity using molecular data, 14 populations in both the Indian and Pacific Oceans (n = 69), and the congeneric taxa P . maxima and P . mazatlanica (n = 29 and n = 10, respectively) were sampled. Phylogenomic reconstruction was carried out using both 8,308 genome-wide SNPs and 10,000 dominant loci (DArTseq PAVs). Reconstructions using neighbour-joining (Nei’s 1972 distances), maximum likelihood and Bayesian approaches all indicate that the taxonomy of P . Margaritifera is quite complex, with distinct evolutionary significant units (ESUs) identified within Tanzanian and Iranian populations. Contrastingly, phylogenies generated for Pacific Ocean oysters resolved a large monophyletic clade, suggesting little support for two current morphological subspecies classifications. Furthermore, P . mazatlanica formed a basal clade closest to French Polynesian P . Margaritifera , suggesting it may be conspecific. Collectively, these findings provide evidence that P . Margaritifera comprises a species complex, perhaps as a result of population fragmentation and increased divergence at range limits.
-
use of tropical microalgae as food for larvae of the black lip pearl oyster pinctada Margaritifera
Aquaculture, 2007Co-Authors: Erika Martinezfernandez, Paul C SouthgateAbstract:Abstract This study determined the nutritional value of tropical microalgae for black-lip pearl oyster ( Pinctada Margaritifera , L.) larvae. One-day old larvae were fed the flagellates Pavlova salina , Pavlova sp., TISO and Micromonas pusilla in binary and ternary combinations in Experiment 1. In a second experiment, umbo-stage larvae were fed the best binary combinations from Experiment 1 with the addition of one diatom species ( C. muelleri , Chaetoceros sp. or Skeletonema sp.) per combination. The best two ternary combinations (flagellates only) from Experiment 1, Pav. salina / Pavlova sp./TISO and TISO/ M. pusilla / Pavlova sp., were also assessed in Experiment 2. In Experiment 1, greater growth rate was shown by larvae fed the ternary combination of Pavlova sp./ Pav. salina /TISO followed for the binary combination of Pavlova sp./ M. pusilla ; however, larvae fed Pavlova sp. as a mono-specific diet performed as well as those fed the ternary combination of Pavlova sp./ Pav. salina / M. pusilla ( P = 0.001). The addition of a diatom to microalgae diets composed of flagellates resulted in increased growth rates and survival of umbo-stage P. Margaritifera larvae when compared to combinations without a diatom (Experiment 2). The results showed that Pavlova sp. supported a high growth rate of D-stage P. Margaritifera larvae which was equivalent to that of larvae fed plurispecific diets. For umbo-stage P. Margaritifera larvae, the best growth rate was achieved when the binary combination of Pavlova sp. and C. muelleri was used. Based on these results, Pavlova sp. and Pavlova sp./ C. muelleri are recommended as diets for D-stage and umbo-stage P. Margaritifera larvae, respectively.
-
mantle regeneration in the pearl oysters pinctada fucata and pinctada Margaritifera
Aquaculture, 2005Co-Authors: Hector Acostasalmon, Paul C SouthgateAbstract:Abstract Mantle tissue in pearl oysters (Pteriidae) is responsible for secreting the mother-of-pearl or nacre lining the shell. When grafted into another oyster, excised mantle tissue, commonly called ‘saibo’, is responsible for cultured pearl production. This study was undertaken to assess the process of mantle regeneration in the Akoya pearl oyster Pinctada fucata and the blacklip pearl oyster Pinctada Margaritifera following mantle excision. Prior to saibo excision, oysters were anaesthetized with 2 mL L −1 propylene phenoxetol. Saibo tissue was excised from 50 P . fucata and 10 P. Margaritifera . After excision, all oysters were returned to culture conditions. All oysters were maintained in panel (pocket) nets on a long-line at Magnetic Island, north Queensland, Australia. Oysters were anaesthetized and sacrificed 3, 6, 9, 12, 15, 20, 30, 45, 60 and 90 days after saibo excision to assess mantle regeneration using histological and histochemical techniques. Survival over the 90-day study was 100% and 70% for P. fucata and P. Margaritifera , respectively. After excision, the mantle tissue healed within the first three days and began growing as connective tissue. Muscular development was seen between days 60 and 90 after excision. Shell formation abilities were recovered by day 15 when secretory cells and conchiolin secretions were first observed. Both P. fucata and P. Margaritifera regenerated mantle to its original extent within the 90-day study. This is the first description of in vivo mantle regeneration in pearl oysters and the results have major implications for the lucrative cultured pearl industry. Our results indicate that mantle tissue donors need not be killed for pearl production. Those producing saibo that results in good quality pearls could be used as future parent-stock in breeding programs or for subsequent saibo donation and pearl production.
-
Mantle regeneration in the pearl oysters Pinctada fucata and Pinctada Margaritifera
Aquaculture, 2005Co-Authors: Héctor Acosta-salmón, Paul C SouthgateAbstract:Mantle tissue in pearl oysters (Pteriidae) is responsible for secreting the mother-of-pearl or nacre lining the shell. When grafted into another oyster, excised mantle tissue, commonly called 'saibo', is responsible for cultured pearl production. This study was undertaken to assess the process of mantle regeneration in the Akoya pearl oyster Pinctada fucata and the blacklip pearl oyster Pinctada Margaritifera following mantle excision. Prior to saibo excision, oysters were anaesthetized with 2 mL L-1 propylene phenoxetol. Saibo tissue was excised from 50 P. fucata and 10 P. Margaritifera. After excision, all oysters were returned to culture conditions. All oysters were maintained in panel (pocket) nets on a long-line at Magnetic Island, north Queensland, Australia. Oysters were anaesthetized and sacrificed 3, 6, 9, 12, 15, 20, 30, 45, 60 and 90 days after saibo excision to assess mantle regeneration using histological and histochemical techniques. Survival over the 90-day study was 100% and 70% for P. fucata and P. Margaritifera, respectively. After excision, the mantle tissue healed within the first three days and began growing as connective tissue. Muscular development was seen between days 60 and 90 after excision. Shell formation abilities were recovered by day 15 when secretory cells and conchiolin secretions were first observed. Both P. fucata and P. Margaritifera regenerated mantle to its original extent within the 90-day study. This is the first description of in vivo mantle regeneration in pearl oysters and the results have major implications for the lucrative cultured pearl industry. Our results indicate that mantle tissue donors need not be killed for pearl production. Those producing saibo that results in good quality pearls could be used as future parent-stock in breeding programs or for subsequent saibo donation and pearl production. © 2005 Elsevier B.V. All rights reserved
-
fouling and predation how do they affect growth and survival of the blacklip pearl oyster pinctada Margaritifera during nursery culture
Aquaculture International, 2003Co-Authors: Paul C SouthgateAbstract:This paper reports on 5 experiments conducted to assess the effect of cleaning regime and predation on growth and survival of blacklip pearl oyster (Pinctada Margaritifera) juveniles in north Queensland, Australia. P. Margaritifera juveniles with a mean (±SE) dorso-ventral shell height (DVH) of 4.5 ± 0.1 mm were placed into plastic mesh trays and cleaned either every 4 or 8 weeks or left uncleaned for 16 weeks. Cleaning regime had a significant effect on growth and survival (P < 0.005). Lowest DVH (16.2 ± 1.0) was shown by oysters in uncleaned trays during 16 weeks compared to oysters in cleaned trays; however, there was no significant difference in DVH between oysters held in trays cleaned every 4 (19.4 ± 1.2) or 8 weeks (21.2 ± 0.8). In contrast lowest survival was shown by oysters held in trays that were cleaned every 4 weeks (30 ± 5%), but no differences were noted between oysters cleaned every 8 weeks (63 ± 4%) and oysters that were left uncleaned for 16 weeks (75 ± 8%). Predators of P. Margaritifera in northern Australia included crabs, stomatopods, flatworms, gastropods and fish. The stomatopod, Gonodactylus falcatus, was the most destructive predator with individuals consuming in excess of 20 juvenile pearl oysters per week. The leather jacket, Paramonocanthus japonicus, did not kill pearl oysters, but trimmed the margin of oysters shells significantly reducing DVH when compared to control groups cultured without fish. Removing predators monthly had a significant effect on growth of pearl oysters compared to oysters in non-inspected trays; however monthly inspection of culture trays did not significantly improve oyster survival.
Juergen Geist - One of the best experts on this subject based on the ideXlab platform.
-
The relationship between the freshwater pearl mussel (Margaritifera Margaritifera) and its hosts
Biology Bulletin, 2017Co-Authors: Jenseike Taeubert, Juergen GeistAbstract:Endangered freshwater pearl mussels Margaritifera Margaritifera reveal a complex life cycle with an obligate host-dependent phase. Only two species, Atlantic salmon Salmo salar and brown trout S. trutta, are important hosts in Europe, indicating a high degree of specialization. Whilst freshwater pearl mussels with their filtering activity can provide important ecosystem services and indirectly improve the habitat quality for their salmonid hosts, their direct effects on physiological stress, reduced swimming performance, and increased mortality at high rates of infestation all support a parasitic character of the mussel during its hostdependent phase. From an evolutionary perspective, both the much greater generation time of the parasite compared to the host, as well as the great distribution ranges of M. Margaritifera and its hosts should favour local adaptation patterns. The variable suitability of different salmonid strains and species as hosts for M. Margaritifera and the resulting differences in the performance of larvae during the host-dependent phase indicate that host-management strategies should focus on maintaining high quality hosts at a regional scale to avoid selection or genetic drift effects which could erode the genetic and evolutionary potential for adaptation to changing environmental conditions.
-
environmental dna as a monitoring tool for the endangered freshwater pearl mussel Margaritifera Margaritifera l a substitute for classical monitoring approaches
Aquatic Conservation-marine and Freshwater Ecosystems, 2016Co-Authors: Bernhard C. Stoeckle, Ralph Kuehn, Juergen GeistAbstract:Knowledge of species distribution is of utmost importance for conservation and management of endangered freshwater mussels. Conventional monitoring approaches are often time consuming and costly. The use of environmental DNA (eDNA) is a relatively new approach and considered as an effective tool to detect the presence of target species in aquatic environments. The aim of this study was to establish a nested PCR system to detect eDNA of Margaritifera Margaritifera and to discuss the advantages and disadvantages of eDNA in mussel surveys compared with classical monitoring. DNA of M. Margaritifera was detected in 2 L water samples collected directly downstream (25 m) from pearl mussel populations (population size from 800–20 000), with an internal-nested PCR approach greatly increasing the detection sensitivity (down to 10 fg target DNA). eDNA detection at greater distances downstream (500 and 1 000 m) of these populations failed, possibly due to DNA degradation or dilution processes. eDNA was also detected downstream of an extinct population, most likely resulting from overlooked mussels or the release of DNA from dead shells. The eDNA approach proposed herein may be helpful in initial screening of streams that are otherwise difficult to monitor, or in the detection of buried juvenile mussels without disturbing their habitat. However, it cannot replace monitoring of population demography, and of other important information for conservation, and should thus only be seen as a supplementary tool. Copyright © 2015 John Wiley & Sons, Ltd.
-
Strong genetic differentiation and low genetic diversity of the freshwater pearl mussel (Margaritifera Margaritifera L.) in the southwestern European distribution range
Conservation Genetics, 2016Co-Authors: Bernhard C. Stoeckle, Juergen Geist, Ralph Kuehn, Rafael Araujo, Carlos Toledo, Annie MachordomAbstract:Genetic diversity of European freshwater pearl mussel, Margaritifera Margaritifera (L.), appears exceptional with highest genetic variability found in the northernmost European populations of Scandinavia and lower genetic variability in central and southern Europe. The objective of this study was to investigate genetic diversity and differentiation of 14 southernmost populations on the Iberian Peninsula which greatly differ in terms of life span and habitat conditions from the rest of central and northern European populations. The analyses of ten microsatellite loci revealed a pronounced level of genetic divergence and very low genetic diversity. These results match the expectations of geographically peripheral populations with respect to their genetic composition. The life history strategy, the narrow ecological niche of the species, and anthropogenic habitat modifications have most likely shaped the genetic pattern of Iberian pearl mussel populations. The peripheral position with less optimal habitat conditions may increase the extinction risk of these populations and thus effective conservation strategies for the Iberian M. Margaritifera are needed. The successful conservation of the species at its southwestern margin requires inclusion of genetically different conservation units which may reveal local adaptation.
-
trophic relationships between the larvae of two freshwater mussels and their fish hosts
Invertebrate Biology, 2015Co-Authors: Marco Denic, Jenseike Taeubert, Juergen GeistAbstract:Freshwater mussels of the order Unionoida have life cycles that include larval attachment to and later metamorphosis on suitable host fishes. Information on the trophic relationship between unionoid larvae and their host fishes is scarce. We investigated the trophic interaction between fish hosts and encysted larvae of two species of freshwater mussels, Margaritifera Margaritifera and Unio crassus, using stable isotope analyses of larvae and juvenile mussels as well as of host fish gill and muscle tissues before and after infestation. Due to different life histories and durations of host-encystment, mass and size increase in M. Margaritifera during the host-dependent phase were greater than those of U. crassus. δ13C and δ15N signatures of juvenile mussels approached isotopic signatures of fish tissues, indicating a parasitic relationship between mussels and their hosts. Shifts were more pronounced for M. Margaritifera, which had a five-fold longer host-dependent phase than U. crassus. The results of this study suggest that stable isotope analyses are a valuable tool for characterizing trophic relationships and life history strategies in host–parasite systems. In the case of unionoid mussels, stable isotopic shifts of the larvae are indicative of the nutritional versus phoretic importance of the host.
-
Critical swimming speed of brown trout (Salmo trutta) infested with freshwater pearl mussel (Margaritifera Margaritifera) glochidia and implications for artificial breeding of an endangered mussel species
Parasitology Research, 2013Co-Authors: Jenseike Taeubert, Juergen GeistAbstract:Unionid freshwater mussels need to attach to a host fish for completion of their life cycle. It remains unclear whether the relationship between these mussels and their host fishes can be considered parasitic, mutualistic, or commensal. Herein, we studied the effects of Margaritifera Margaritifera infestation on Salmo trutta , the most important host of this endangered mussel species in Central Europe. Glochidial load of host fish increased with increasing glochidial concentration, but the highest ratios of encysted glochidia to exposed glochidia were found at low concentration (15,000 glochidia L^−1) during infestation. Host fish mortality occurred at infestation rates of ~350 glochidia per g fish weight and was highest (60 %) at the highest infestation rates (~900 glochidia per g fish weight). On a sublethal level, swimming performance of hosts was inversely related to infestation rates, with infestation of ~900 glochidia per g fish weight reducing critical swimming speed of S . trutta significantly by ~20 % compared to infestation with 6 glochidia per g fish weight. The high mortality and the impaired swimming capability of highly infested hosts indicate a parasitic interaction between M . Margaritifera and its host. For conservation and reintroduction of M . Margaritifera via glochidia-infested S . trutta , we recommend glochidial loads of 5–100 glochidia per g fish weight, while for artificial breeding of juvenile M . Margaritifera under laboratory conditions, higher infestation rates of up to 300 glochidia per g fish weight are ideal to balance high yields of mussels and welfare of host fishes.
Stephane Pouvreau - One of the best experts on this subject based on the ideXlab platform.
-
Pearl oysters Pinctada Margaritifera grazing on natural plankton in Ahe atoll lagoon (Tuamotu Archipelago, French Polynesia).
Marine pollution bulletin, 2012Co-Authors: Jonathan Fournier, Stephane Pouvreau, Gilles Le Moullac, Marc Bouvy, Marine Couraudon-réale, Loïc Charpy, Marcel Le Pennec, Christine Dupuy, Jean-claude CochardAbstract:In atoll lagoons of French Polynesia, growth and reproduction of pearl oysters are mainly driven by plankton concentration. However, the actual diet of black-lip pearl oysters Pinctada Margaritifera in these lagoons is poorly known. To fill this gap, we used the flow through chamber method to measure clearance rates of P. Margaritifera in Ahe atoll lagoon (Tuamotu Archipelago, French Polynesia). We found: (i) that pearl oysters cleared plankton at a rate that was positively related to plankton biovolume, (ii) that nanoflagellates were the main source of carbon for the pearl oysters, and (iii) that the quantity and origin of carbon filtrated by pearl oysters was highly dependent on the concentration and composition of plankton. These results provide essential elements for the comprehension of growth and reproduction variability of pearl oysters in atoll lagoons of French Polynesia.
-
Influence of plankton concentration on gametogenesis and spawning of the black lip pearl oyster Pinctada Margaritifera in Ahe atoll lagoon (Tuamotu Archipelago, French polynesia).
Marine Pollution Bulletin, 2012Co-Authors: Jonathan Fournier, Stephane Pouvreau, Marcel Le Pennec, Emmanuelle Levesque, Gilles Le MoullacAbstract:Pearl culture industry represents one of the dominant business sector of French Polynesia. However, it still entirely relies on unpredictable spat collection success. Our aim was to assess the influence of natural plankton concentration fluctuations on maturation and spawning of the black lip pearl oyster Pinctada Margaritifera, during a 4 months survey conducted in Ahe atoll lagoon. Plankton concentration was assessed by chlorophyll a extraction and by microscope counts while gonadic index, gonado-visceral dry weights and histology were used to measure pearl oysters reproduction activity. We found that (i) plankton concentration fluctuations were mainly related to wind regime, (ii) gametogenesis rate was mainly related to plankton concentration, (iii) spawning occurred when maximal gonad storage was reached, (iv) plankton concentration was the main spawning synchronizing factor. These results contribute explaining P. Margaritifera spat collection variability in French Polynesian atoll lagoon.
-
Application of a bioenergetic growth model to larvae of the pearl oyster Pinctada Margaritifera L.
Journal of Sea Research, 2011Co-Authors: Yoann Thomas, Pierre Garen, Stephane PouvreauAbstract:We applied, for the first time, a dynamic energy budget (DEB) growth model to the larval phase in the pearl oyster Pinctada Margaritifera var. cumingii (Linne 1758) to evaluate the impact of spatio-temporal variation in the atoll lagoon environment on its capacity for development. The specific parameters of the model, which represent ingestion, temperature effect and the relationship between length and biovolume of the larvae, were determined from experiments or taken from the literature. The interpretation of the values of these parameters allowed us to identify the underlying adaptive character trait: P. Margaritifera larvae have a good capacity to exploit low food concentrations and a narrow range of thermal tolerance restricted to hydrobiological conditions found in the tropical oligotrophic waters of its distribution zone. Growth simulations show a good fit with the observations made on reared larvae under different conditions, fed on either cultured algae or natural plankton, and with growth data from a natural cohort. Finally, a first application of the model to a pearl- culture lagoon reveals the predominant effect of the vertical structure of trophic resources in determining spatial variation in larval growth. Research highlights ► We developed a DEB model for Pinctada Margaritifera larvae. ► To our knowledge, it is the third application of a DEB model for bivalve larvae, but the first one for tropical bivalves. ► This model is used to give insight into the ecology of this species. ► Application for aquaculture purposes is also discussed.
-
gametogenic cycle and reproductive effort of the tropical blacklip pearl oyster pinctada Margaritifera bivalvia pteriidae cultivated in takapoto atoll french polynesia
Aquatic Living Resources, 2000Co-Authors: Stephane Pouvreau, Aline Gangnery, Jerome Tiapari, Franck Lagarde, Matthieu Garnier, Alain BodoyAbstract:The gametogenic cycle and the reproductive effort of the blacklip pearl oyster, Pinctada Margaritifera, cultivated in Takapoto lagoon were studied for a 1-year period (March 1997-April 1998) by bimonthly observations of gonadal sections, dry tissue weights and gonadal index in a population of pearl oyster composed of three age-groups. Pearl oysters attained sexual maturity in the end of their first year (height ≈ 40 mm), implying that P. Margaritiferais a late-maturing species in comparison with other Pteriidae. This species was also confirmed to be a marked protandrous successive hermaphrodite in culture, with 100 % of males at first maturity and 75 % in older pearl oyster (height > 120 mm). The general pattern of gametogenic activity, fairly synchronous in both sexes, was comparable with that of other tropical bivalves: reproduction occurs continuously throughout the year with a maximal activity during the warm season (November-May). No resting period was observed. Quantitative growth data showed that P. Margaritifera exhibits an annual synchronised polymodal spawning pattern, with two spawning peaks in age-group I (height ≈ 70 mm) and five in age-groups II (height ≈ 100 mm) and III (height ≈ 120 mm). Spawning was sometimes incomplete, nevertheless a clear relationship between gamete production (PR, g) and size (height H, mm) was obtained: PR = 5.26 × 10 -7 H 2.91 (R_ = 0.99, P < 0.05). Estimation of PR was used to calculate the annual reproductive effort in P. Margaritifera. Reproductive effort (%) was similar to those calculated for temperate species and showed a progressive increase with the age of pearl oyster, from 7 % in age-group I to 38 % in age-group III. This study showed that, in a fairly stable tropical environment such as the Takapoto lagoon, P. Margaritifera is a multiple spawner, which uses an opportunistic reproductive strategy, allowing investment, all year around, of any surplus energy into gamete production. Surplus energy is ensured by the high pumping rates developed by this non-symbiotic bivalve to succeed in low seston conditions. © 2000 Ifremer/Cnrs/Inra/Ird/Cemagref/Editions scientifiques et medicales Elsevier SAS
Jonathan Fournier - One of the best experts on this subject based on the ideXlab platform.
-
Pearl oysters Pinctada Margaritifera grazing on natural plankton in Ahe atoll lagoon (Tuamotu Archipelago, French Polynesia).
Marine pollution bulletin, 2012Co-Authors: Jonathan Fournier, Stephane Pouvreau, Gilles Le Moullac, Marc Bouvy, Marine Couraudon-réale, Loïc Charpy, Marcel Le Pennec, Christine Dupuy, Jean-claude CochardAbstract:In atoll lagoons of French Polynesia, growth and reproduction of pearl oysters are mainly driven by plankton concentration. However, the actual diet of black-lip pearl oysters Pinctada Margaritifera in these lagoons is poorly known. To fill this gap, we used the flow through chamber method to measure clearance rates of P. Margaritifera in Ahe atoll lagoon (Tuamotu Archipelago, French Polynesia). We found: (i) that pearl oysters cleared plankton at a rate that was positively related to plankton biovolume, (ii) that nanoflagellates were the main source of carbon for the pearl oysters, and (iii) that the quantity and origin of carbon filtrated by pearl oysters was highly dependent on the concentration and composition of plankton. These results provide essential elements for the comprehension of growth and reproduction variability of pearl oysters in atoll lagoons of French Polynesia.
-
Influence of plankton concentration on gametogenesis and spawning of the black lip pearl oyster Pinctada Margaritifera in Ahe atoll lagoon (Tuamotu Archipelago, French polynesia).
Marine Pollution Bulletin, 2012Co-Authors: Jonathan Fournier, Stephane Pouvreau, Marcel Le Pennec, Emmanuelle Levesque, Gilles Le MoullacAbstract:Pearl culture industry represents one of the dominant business sector of French Polynesia. However, it still entirely relies on unpredictable spat collection success. Our aim was to assess the influence of natural plankton concentration fluctuations on maturation and spawning of the black lip pearl oyster Pinctada Margaritifera, during a 4 months survey conducted in Ahe atoll lagoon. Plankton concentration was assessed by chlorophyll a extraction and by microscope counts while gonadic index, gonado-visceral dry weights and histology were used to measure pearl oysters reproduction activity. We found that (i) plankton concentration fluctuations were mainly related to wind regime, (ii) gametogenesis rate was mainly related to plankton concentration, (iii) spawning occurred when maximal gonad storage was reached, (iv) plankton concentration was the main spawning synchronizing factor. These results contribute explaining P. Margaritifera spat collection variability in French Polynesian atoll lagoon.