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Cayenne, French Guiana

Garcia J.,CNRS Training and Research Center on Mediterranean Environments | Garcia J.,University of Murcia | Rousseau Y.,CNRS Guyane | Legrand H.,DEAL | And 2 more authors.
Marine Ecology Progress Series | Year: 2014

Marine protected area (MPA) effectiveness is highly dependent on the movement patterns of adult fish. In this study, we selected 3 species, Sparisoma viride (Scaridae), Acanthurus chirurgus (Acanthuridae), and Lutjanus apodus (Lutjanidae), to quantify their home ranges, evaluate their site fidelity, and identify movement patterns in Martinique (14° 36' N, 61° 32'W). Two complementary tagging methods (external Floy tags and acoustic telemetry) were utilised to moni tor movement patterns on different spatial scales from November 2009 to November 2011. We tagged 673 A. chirurgus, 131 L. apodus, and 217 S. viride with Floy tags and 30 A. chirurgus, 47 L. apodus, and 37 S. viride with acoustic tags. The results revealed that several individuals maintained a small preferential site for several months to over a year. Other individuals were able to move long distances (<9 km) outside the MPA over a short period (<3 d) and never returned to the MPA. This study highlights the importance of using multiple tagging methods and long-term observations to improve the monitoring of fish movement relative to MPA design and effectiveness. Despite the fragmented habitat in the studied MPA, the results highlight that small MPAs (9.56 km2) could protect the 3 studied species. This study also demonstrated that natural barriers (large areas of silt and sand) were crossed by some individuals. Our findings provide relevant information on these species that should be utilised to better inform MPA design and decisionmaking processes, management, and overall MPA effectiveness. © Inter-Research 2014 Source

Chave J.,CNRS Biological Evolution and Diversity Laboratory | Navarrete D.,Fundacion Puerto Rastrojo | Navarrete D.,National University of Colombia | Almeida S.,Museu Paraense Emilio Goeldi | And 13 more authors.
Biogeosciences | Year: 2010

The production of aboveground soft tissue represents an important share of total net primary production in tropical rain forests. Here we draw from a large number of published and unpublished datasets (n=Combining double low line81 sites) to assess the determinants of litterfall variation across South American tropical forests. We show that across old-growth tropical rainforests, litterfall averages 8.61±1.91 Mg ha -1 yr -1 (mean ± standard deviation, in dry mass units). Secondary forests have a lower annual litterfall than old-growth tropical forests with a mean of 8.01±3.41 Mg ha -1 yr -1. Annual litterfall shows no significant variation with total annual rainfall, either globally or within forest types. It does not vary consistently with soil type, except in the poorest soils (white sand soils), where litterfall is significantly lower than in other soil types (5.42±1.91 Mg ha -1 yr -1). We also study the determinants of litterfall seasonality, and find that it does not depend on annual rainfall or on soil type. However, litterfall seasonality is significantly positively correlated with rainfall seasonality. Finally, we assess how much carbon is stored in reproductive organs relative to photosynthetic organs. Mean leaf fall is 5.74±1.83 Mg ha -1 yr -1 (71% of total litterfall). Mean allocation into reproductive organs is 0.69±0.40 Mg ha -1 yr -1 (9% of total litterfall). The investment into reproductive organs divided by leaf litterfall increases with soil fertility, suggesting that on poor soils, the allocation to photosynthetic organs is prioritized over that to reproduction. Finally, we discuss the ecological and biogeochemical implications of these results. Source

Gensac E.,IRD Montpellier | Gardel A.,CNRS Guyane | Gardel A.,University of the Littoral Opal Coast | Lesourd S.,University of Caen Lower Normandy | Brutier L.,CNRS Guyane
Estuarine, Coastal and Shelf Science | Year: 2015

The coastal environment between the Amazon and the Orinoco Rivers is characterised by the migration of large mud banks formed by accretion of the muddy discharge from the Amazon. The migration of mud in the shallow coastal waters is associated with the creation of mudflats that form a surface for the development of coastal mangroves after consolidation. This study focuses on the fine-scale sedimentary processes involved in the morphodynamic evolution of a consolidated mudflat and its erosion. Mudflats can be divided into two areas: the seafront and the inner part between the seafront and the land. This study highlights a link between tidal mud supply, biofilm migration and increasing elevation in the latter area. The migration of a biofilm through each cycle of tidal supply prevents erosion and permits the continuous accretion of the entire mudflat over several years. This increase in topography is also modulated by fortnightly tidal cycles. Desiccation greatly impacts the mudflat's structure at a yearly scale. This process plays an important role in the erosion of the seafront area under wave action by allowing the formation of mud pebbles, which are progressively abraded into fluid mud supplied to the inner part of the mudflat by over-wash processes. This study provides a better understanding of the behaviour of mudflats on the wave-exposed coast downdrift of the mouth of the Amazon by describing: (1) the processes involved in sediment exchanges between mudflats and mud banks, (2) the mechanisms associated with the persistence of mudflats along the French Guiana coast downdrift of the mouth of the Amazon, and (3) the processes involved in the erosion and recycling of these mudflats. © 2015 Elsevier Ltd. Source

Bletz M.C.,James Madison University | Bletz M.C.,TU Braunschweig | Rosa G.M.,University of Kent | Rosa G.M.,UK Institute of Zoology | And 19 more authors.
Scientific Reports | Year: 2015

Amphibian chytridiomycosis, an emerging infectious disease caused by the fungus Batrachochytrium dendrobatidis (Bd), has been a significant driver of amphibian declines. While globally widespread, Bd had not yet been reported from within Madagascar. We document surveys conducted across the country between 2005 and 2014, showing Bd's first record in 2010. Subsequently, Bd was detected in multiple areas, with prevalence reaching up to 100%. Detection of Bd appears to be associated with mid to high elevation sites and to have a seasonal pattern, with greater detectability during the dry season. Lineage-based PCR was performed on a subset of samples. While some did not amplify with any lineage probe, when a positive signal was observed, samples were most similar to the Global Panzootic Lineage (BdGPL). These results may suggest that Bd arrived recently, but do not exclude the existence of a previously undetected endemic Bd genotype. Representatives of all native anuran families have tested Bd-positive, and exposure trials confirm infection by Bd is possible. Bd's presence could pose significant threats to Madagascar's unique "megadiverse"' amphibians. Source

Mendoza I.,French Natural History Museum | Mendoza I.,Claro | Martin G.,French Natural History Museum | Caubere A.,French Natural History Museum | And 4 more authors.
Journal of Tropical Ecology | Year: 2015

Species showing mast seeding synchronously produce large amounts of fruits during some scattered years. This massive crop has been hypothesized to improve dispersal effectiveness by a satiation of seed predators, but the consequences for seed dispersers have barely been studied in the tropics. We tested the hypothesis that masting resulted in satiation of frugivorous dispersers using the study case of two Manilkara species growing in an Amazonian forest in French Guiana. Seed dispersal was estimated by means of seed traps in two forest types during a 10-y monitoring. Manilkara huberi and M. bidentata showed three fruiting events in a time span of 10 y (in 2001, 2006 and 2010). Estimates of seed dispersal from 2001 and 2010 showed that satiation of frugivores only occurred in the year with the largest crop of Manilkara (2010) and in the habitat where the diversity of primate-dispersed species retrieved in seed traps was the highest (Grand Plateau, with clay soils), while fruit consumers did not seem to be satiated in other instances. Spatio-temporal variability of seed production and the community-crop context are therefore affecting satiation of frugivores during masting events. © 2015 Cambridge University Press. Source

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