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Статті в журналах з теми "Recrutement corallien"
Roux, Natacha, Pauline Salis, and Vincent Laudet. "Les larves de poissons coralliens : un nouveau modèle d’étude de la métamorphose et des hormones thyroïdiennes." Biologie Aujourd'hui 213, no. 1-2 (2019): 27–33. http://dx.doi.org/10.1051/jbio/2019010.
Повний текст джерелаДисертації з теми "Recrutement corallien"
Pozas-Schacre, Chloé. "Chemical and microbial effects of macroalgae on coral holobionts and reef ecosystems." Electronic Thesis or Diss., Université Paris sciences et lettres, 2024. http://www.theses.fr/2024UPSLP015.
Повний текст джерелаL'accumulation des pertubations environnementales a profondément altéré les communautés benthiques des récifs coralliens, où les macroalgues remplacent souvent les coraux. Ces changements de phase sont favorisés par une compétition intense des algues, limitant la récupération des communautés coralliennes. Si, lors de contacts directs, les molécules allopathiques et les microbes des algues peuvent provoquer la mortalité des coraux, leurs diffusions et leurs impacts au-delà de l'espace physique occupé par les algues demeurent encore largement méconnus. Cette thèse a eu pour objectif de répondre à deux questions majeures : comment les macroalgues modifient les paysages chimiques et microbiens et en quoi ces modifications altèrent la santé de l'holobionte corallien et son recrutement ? En manipulant la présence/absence de macroalgues, cette thèse a permis de mettre en évidence une structuration spatiale à fine échelle des microbes et métabolites selon l'abondance de macroalgues et les couches de diffusion (i.e., couches benthique et momentum). Les eaux autour des algues étaient enrichies en bactéries opportunistes, potentiellement pathogènes, et molécules toxiques (i.e., diterpènes). Ces recherches ont ensuite montré que l'exposition aux macroalgues pouvait altérer le microbiome des larves coralliennes (Pocillopora acuta) et impacter négativement la survie des larves et recrues, au travers d'effets parentaux et environnementaux. L'influence relative des effets par contact vs. médiés par l'eau (i.e., 2 cm) sur l'holobiont corallien a été testée en utilisant l'algue allélopathique Dictyota bartayresiana. Chaque type d'interaction a perturbé distinctement le microbiome et métabolome corallien suggérant un ajustement du métabolisme lipidique pour répondre au coût énergétique de la compétition et à la production de métabolites de défense. En combinant métabarcoding et métabolomique non ciblée, ce travail de thèse a permis de décrire l'identité et la distribution des microbes et métabolites associés à la compétition corail-algues afin de mieux comprendre la conséquence des changements de phase sur la résilience des récifs coralliens
Massé, Lola. "Comparaison de la reproduction sexuée et du recrutement des coraux scléractiniaires entre un récif tropical (La Réunion) et subtropical (Afrique du Sud) du sud-ouest de l’océan Indien." Thesis, La Réunion, 2014. http://www.theses.fr/2014LARE0025/document.
Повний текст джерелаCoral reproduction and recruitment in Scleractinia were compared between the subtropical reefs of South Africa and the tropical reefs of Reunion to assess variations between contrasting environments. In addition, coral larvae and juvenile polyps were exposed to elevated temperature in aquarium to simulate global warming. The two targeted species, Acropora austera and Platygyra daedalea, exhibited the same reproductive mode (hermaphroditic broadcast spawner), gamete development (5-6 months) and breeding seasonality (October to February) in South Africa and Reunion. Coral fecundity was nevertheless higher in South Africa than in Reunion. A. austera and P. certaine limite.AbstractCoral reproduction and recruitment in Scleractinia were compared between the subtropical reefs of South Africa and the tropical reefs of Reunion to assess variations between contrasting environments. In addition, coral larvae and juvenile polyps were exposed to elevated temperature in aquarium to simulate global warming. The two targeted species, Acropora austera and Platygyra daedalea, exhibited the same reproductive mode (hermaphroditic broadcast spawner), gamete development (5-6 months) and breeding seasonality (October to February) in South Africa and Reunion. Coral fecundity was nevertheless higher in South Africa than in Reunion. A. austera and P. daedalea produced respectively 43 and 100% more oocytes per polyp than their Reunion counterparts. The recruitment rate was also higher on the subtropical reefs of South Africa (548 recruits m2 year-1) compared to Reunion (305 recruits m2 year-1). Recruitment was dominated by Pocilloporidae at the two localities, followed by Acroporidae in South Africa and Poritidae in Reunion. In South Africa, an increase in sea temperature of 2°C strongly affected the larval development of the sensitive A. austera, while the more robust P. daedalea sustained temperatures up to 4°C (i.e. 30°C) above ambient. In Reunion, diminished fecundity and recruitment rate seemed to be an indicator of reef perturbation. In contrast in South Africa, the high reproductive effort and larval supply in corals associated with the low levels of disturbance on the reefs may favour coral adaptation, to some extent, under global change
Salles, Océane. "Potentiel évolutif d'une population naturelle de poissons coralliens à fort auto-recrutement dans un environnement variable." Thesis, Paris, EPHE, 2016. http://www.theses.fr/2016EPHE3071.
Повний текст джерелаThe evolutionary potential of wild populations to respond to environmental change will determine their capacity to adapt and survive. However, in order to achieve evolutionary change, variation in the contribution of an individual to the next generation — its fitness — must have a genetic basis and be heritable. The study of the evolutionary potential of populations requires longitudinal and relatedness data with different environments to partition the contribution of genes, maternal effects and environment on fitness. Estimates of genetic heritability of fitness traits are extremely rare, especially for marine species, where inter-generational relationships are rarely known. Here, we present the first multi-generational pedigree for a marine fish population by repeatedly genotyping all individuals in a population of the orange clownfish (Amphiprion percula) at Kimbe Island (Papua New Guinea) over a 10-year period. Based on 2927 individuals, our pedigree analysis revealed that longitudinal philopatry was recurrent over five generations. We show that local reproductive success has a very low (<1%) but significant heritability. We also show that additive genetic variation and maternal effects on local fitness are both extremely low (<1%). Habitat is the major driver that explain differences in the contribution of individuals to the next generation in the local population (until 96.5%). Together these results suggest that while the environment imposes strong selection pressures on the local fitness, the low heritability indicates the orange clownfish population has little evolutionary potential to adapt to local environmental changes
Jorissen, Hendrikje. "Comprendre l’association algue coralline – corail : des espèces clés aux médiateurs chimiques et microbiens." Thesis, Université Paris sciences et lettres, 2020. http://www.theses.fr/2020UPSLP025.
Повний текст джерелаCrustose coralline algae (CCA) are commonly associated with healthy reefs and play an important role in benthic systems by guiding settlement of many habitat forming or ecologically important organisms, including corals. However, the ability of CCA to induce coral settlement is not ubiquitous among CCA species. Corals exhibit settlement preferences for certain CCA species. These preferences demonstrate the capacity of coral larvae to discriminate among CCA species and raise the question of the mechanisms involved. Despite the enormous variety of CCA species on coral reefs, little is known about the diversity of their associated chemicals and microbes and the ecological role of these compartments, notably for coral recruitment. Chapter 2 of this thesis investigated the microbial and chemical composition of six CCA species, which occupy different ecological niches on the coral reefs of Moorea (French Polynesia), and how these two compartments (i.e., microbial and chemical) relate to successful settlement success of Acropora cytherea larvae. Results showed settlement was highest on the cryptic CCA species Titanoderma prototypum and that practically no larvae settled on exposed CCA species. While all CCA species had distinct metabolic fingerprints and contained high metabolic diversity, the metabolomic diversity and richness of T. prototypum were significantly higher than those of the other CCA species. T. prototypum also hosted a significantly higher bacterial diversity than the other CCA species, and contained a higher abundance of bacteria that potentially produce antibacterial compounds. The presence of these bacteria could inhibit coral pathogens, which in turn could enhance the survival of coral settlers. Thus, coral settlement is a complex process of biochemical communications between CCA, their associated microbial surface communities and coral larvae. Despite widespread acceptance that CCA positively influence coral recruitment success, there are no experimental data on the effects of CCA species on late post-settlement survival and growth of corals. Chapter 3 tested the impact of four CCA species from two habitats (exposed and subcryptic) on the survival and growth of Pocillopora recruits. CCA had a contrasting effect on the survival of coral recruits depending on habitat and recruit size. In subcryptic habitats, CCA can reduce the survival and/or growth of coral recruits via direct competitive overgrowth, while, in exposed habitats, they can enhance coral recruitment by alleviating competition with turf algae. Importantly, this study demonstrated that not all CCA species are beneficial to the survival and growth of coral recruits and that there is considerable variability in both the outcome and process of competition between CCA and corals. Chapter 4 and 5 focused on investigating whether two environmental stressors, ocean acidification (OA) and hypoxia, respectively, impact the coral-CCA association by disrupting larval settlement behavior and recruitment of two coral species (A. cytherea and A. pulchra) on an otherwise preferred and beneficial CCA species (T. prototypum). Larvae of both coral species avoided bottom exploration and settlement in low pH environments. They avoided bottom exploration in reduced oxygen environments and settled on T. prototypum fragments only in oxygen rich environments, with settlement rates increasing exponentially with oxygen concentrations. These results indicate that low oxygen and low pH areas can negatively influence coral settlement success and that oxygen and pH act as chemical cues for coral larval orientation and settlement. This thesis aids to better understand the role of CCA, micro-organisms and chemicals in the fine-scale dynamics of coral recruitment now and under future ocean conditions. It highlights that CCA-coral interactions are complex processes that are likely mediated by chemicals and microbes and these interactions can be affected by changing environments
Durville, Patrick. "Colonisation ichtyologique des platiers de La Réunion et biologie des post-larves de poissons coralliens." Phd thesis, Université de la Réunion, 2002. http://tel.archives-ouvertes.fr/tel-00545391.
Повний текст джерелаFauvelot, Cécile. "Influence des caractéristiques biologiques et historiques des espèces sur la structuration d'une métapopulation en milieu fragmenté insulaire : exemple des poissons coralliens en Polynésie française." Paris 6, 2002. http://www.theses.fr/2002PA066137.
Повний текст джерелаJouval, Florian. "Successions écologiques et potentiel de récupération des communautés coralliennes : structure, démographie et recrutement dans le sud-ouest de l'océan Indien." Thesis, La Réunion, 2019. http://www.theses.fr/2019LARE0019.
Повний текст джерелаCoral reefs support millions of people’s livelihood around the world. However, the effects of climate change and the increase in frequency and intensity of disturbances are leading to their accelerated degradation and to the decline of scleractinian coral communities. Current concerns relate to the resilience of these vulnerable ecosystems. In this context, it is essential to improve our understanding of the mechanisms underlying maintenance of coral communities, which may also improve conservation and management efforts that are urgently needed for these ecosystems. This PhD work aims to analyze demographic processes, including recruitment, and the structure of coral assemblages at several scales in different island environments of the southwestern Indian Ocean region. These descriptors were addressed through ecological succession on reefs and underwater lava flows of Reunion Island, and through the assessment of the reef recovery potential of five island systems in the area. Results show that coral recruitment in the Mascarene Islands (Reunion and Rodrigues) is low and highly variable at all spatial scales, from a few centimeters to several hundreds of kilometers. This spatial variability is also observed between sites in terms of benthic cover, density, size structure, mortality and recovery potential of coral communities. However, this spatial variability is not clearly linked to the protection levels of the sites, nor to the theoretical patterns of ecological succession (studied in Reunion Island). A succession pattern is yet highlighted through the increase in coral size and species richness over time until interspecific interactions (e.g. competition for space) lead to their decline. In addition, a strong dominance of the Pocillopora genus is recorded at all lava flow sites, confirming its pioneering and competitive nature. The recovery index (RI) that we developed suggests that the recovery potential of the reefs of the Mozambique Channel is higher (especially for Europa) than that of the reefs of the Mascarene Islands, which are more subject to direct anthropogenic pressures. These results are consistent with past observations of recovery trajectories of the studied reefs following various disturbances. The addition of recruitment rates to the calculation of RI for Reunion and Rodrigues islands clearly modifies the recovery potential of these islands sites: the sites with the highest recruitment rates are also those with the highest RI. This project thus provides essential information on Indian Ocean reef communities that may improve management strategies for coral reef conservation
Tiavouane, Josina. "Les bénitiers de Nouvelle-Calédonie : nouvelles espèces et échelles spatiales de connectivité chez Tridacna maxima et Hippopus hippopus." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066661.
Повний текст джерелаDespite their functional role in coral reef ecosystems, giant clams (Tridacninae) are in decline worldwide due to their overexploitation. In New Caledonia, 1 to 9 tons are harvested per year. In this context, the main objectives of this thesis are to provide information about the demographic and evolutionary population’s connectivity for two species of giant clams in New Caledonia, Tridacna maxima and Hippopus hippopus, in order to estimate the spatial scales of larval dispersal, understand their population dynamics and propose appropriate conservation measures. The connectivity of populations was estimated by analyzing microsatellite genetic markers specifically developed for these two species. Sampling allowed the identification of two new species in New Caledonia. At reef scale and up to a few kilometers, parentage analysis showed that giant clam populations have varying self-recruitment rates, up to 8% for T. maxima in southwest lagoon and 29% for H. hippopus in northeastern lagoon. The spatial scales of larval dispersal varied for the two species, up to at least 35km for H. hippopus. At the scale of the territory, giant clam populations showed a weak genetic structure, highlighting evolutionary connectivity among sampled sites. However, significant differences were observed between the Mainland and Chesterfield, Loyalty Islands and Entrecasteaux for H. hippopus and between the west coast and the Loyalty Islands for T. maxima. These results provide important answers related to the spatial scales of larval dispersal in giant clams in New Caledonia
Cuif, Marion. "Combinaison de la modélisation biophysique et de marquages isotopiques pour estimer la connectivité démographique des populations marines : application à Dascyllus aruanus dans le lagon sud-ouest de Nouvelle-Calédonie." Electronic Thesis or Diss., Paris 6, 2014. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2014PA066526.pdf.
Повний текст джерелаUnderstanding marine populations dynamics is critical to their effective management,and requires information on patterns of dispersal and connectivity that are still poorlyknown. Many marine organisms have a bipartite life history with a pelagic larvalstage that often represents the only opportunity for dispersal. In the last decade,new empirical and simulation approaches to measuring larval dispersal have beendeveloped, but results from these two different approaches have rarely been comparedin the context of a single marine system, impeding the use of larval dispersal modelsin metapopulation models supporting decision making. In this doctoral research, weused both approaches to investigate larval connectivity for a coral reef fish, Dascyllusaruanus, in the South-West Lagoon of New Caledonia. Our biophysical dispersalmodel shows that larval retention exhibits considerable temporal variability at bothlagoon and patch reef scales and periodically reaches large values despite low averagewater residence time. Artificial transgenerational marking of embryonic otoliths inthe wild also showed relatively low self-recruitment rates indicating high populationopenness at the reproductive season scale, with considerable monthly variability ofself-recruitment. Large quantitative discrepancies between simulations and empiricalresults emphasize the need to better understand processes that facilitate local retention,such as homing behavior and very small scale circulation patterns
Cuif, Marion. "Combinaison de la modélisation biophysique et de marquages isotopiques pour estimer la connectivité démographique des populations marines : application à Dascyllus aruanus dans le lagon sud-ouest de Nouvelle-Calédonie." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066526/document.
Повний текст джерелаUnderstanding marine populations dynamics is critical to their effective management,and requires information on patterns of dispersal and connectivity that are still poorlyknown. Many marine organisms have a bipartite life history with a pelagic larvalstage that often represents the only opportunity for dispersal. In the last decade,new empirical and simulation approaches to measuring larval dispersal have beendeveloped, but results from these two different approaches have rarely been comparedin the context of a single marine system, impeding the use of larval dispersal modelsin metapopulation models supporting decision making. In this doctoral research, weused both approaches to investigate larval connectivity for a coral reef fish, Dascyllusaruanus, in the South-West Lagoon of New Caledonia. Our biophysical dispersalmodel shows that larval retention exhibits considerable temporal variability at bothlagoon and patch reef scales and periodically reaches large values despite low averagewater residence time. Artificial transgenerational marking of embryonic otoliths inthe wild also showed relatively low self-recruitment rates indicating high populationopenness at the reproductive season scale, with considerable monthly variability ofself-recruitment. Large quantitative discrepancies between simulations and empiricalresults emphasize the need to better understand processes that facilitate local retention,such as homing behavior and very small scale circulation patterns