Baraloto C.,French National Institute for Agricultural Research |
Couteron P.,Institute pour la Recherche et le Developpement
Biotropica | Year: 2010
We examined fine-scale heterogeneity of environmental conditions in a primary rain forest in French Guiana to describe variation in microhabitats that plants may experience during establishment. We characterized both the range as well as the spatial structuring of 11 environmental factors important for seedling establishment in six hexagonal sampling grids, one each in gap and understory sites at three points representing the predominant geomorphic units in this primary forest. Each grid contained 37 sampling points separated by 31 cm-20 m. Monte-Carlo tests of semivariograms against complete spatial randomness indicated that for many variables in all six sampling grids, spatial dependence did not exceed 1 m. A principal component analysis of all sampling points revealed a lack of spatial microhabitat structure, rather than homogeneous patches associated with canopy structure or geomorphology. Our results suggest that ample fine-scale spatial heterogeneity exists to support the coexistence of plant species with differential abiotic requirements for regeneration. © 2010 The Author(s). Journal compilation © 2010 by The Association for Tropical Biology and Conservation.
Ponge J.-F.,CNRS Mechanical Adaptation and Evolution |
Peres G.,CNRS Ecosystems, Biodiversity, and Evolution Laboratory |
Guernion M.,CNRS Ecosystems, Biodiversity, and Evolution Laboratory |
Ruiz-Camacho N.,Institute pour la Recherche et le Developpement |
And 9 more authors.
Soil Biology and Biochemistry | Year: 2013
A gradient of agricultural intensification (from permanent meadows to permanent crops, with rotation crops and meadows as intermediary steps) was studied in the course of the RMQS-Biodiv program, covering a regular grid of 109 sites spread over the whole area of French Brittany. Soil biota (earthworms, other macrofauna, microarthropods, nematodes, microorganisms) were sampled according to a standardized procedure, together with visual assessment of a Humus Index. We hypothesized that soil animal and microbial communities were increasingly disturbed along this gradient, resulting in decreasing species richness and decreasing abundance of most sensitive species groups. We also hypothesized that the application of organic matter could compensate for the negative effects of agricultural intensity by increasing the abundance of fauna relying directly on soil organic matter for their food requirements, i.e. saprophagous invertebrates. We show that studied animal and microbial groups, with the exception of epigeic springtails, are negatively affected by the intensity of agriculture, meadows and crops in rotation exhibiting features similar to their permanent counterparts. The latter result was interpreted as a rapid adaptation of soil biotic communities to periodic changes in land use provided the agricultural landscape remains stable. The application of pig and chicken slurry, of current practice in the study region, alone or in complement to mineral fertilization, proves to be favorable to saprophagous macrofauna and bacterivorous nematodes. A composite biotic index is proposed to synthesize our results, based on a selection of animals groups which responded the most to agricultural intensification or organic matter application: anecic earthworms, endogeic earthworms, macrofauna other than earthworms (macroarthropods and mollusks), saprophagous macrofauna other than earthworms (macroarthropods and mollusks), epigeic springtails, phytoparasitic nematodes, bacterivorous nematodes and microbial biomass. This composite index allowed scoring land uses and agricultural practices on the base of simple morphological traits of soil animals without identification at species level. © 2013 Elsevier Ltd.
Baillard C.,CNRS Paris Institute of Global Physics |
Crawford W.C.,CNRS Paris Institute of Global Physics |
Ballu V.,University of La Rochelle |
Regnier M.,University of Nice Sophia Antipolis |
Pelletier B.,Institute Pour la Recherche et le Developpement
Journal of Geophysical Research B: Solid Earth | Year: 2015
The Vanuatu arc in the southwest Pacific Ocean is one of the world's most seismically active regions, with almost 39 magnitude 7+ earthquakes in the past 43 years. Convergence rates are around 90-120 mm/yr along most of the arc, but drop to 25-43 mm/yr in the central section, probably due to the subduction of the d'Entrecasteaux ridge. We characterize the slab geometry and tectonic state in this central section by analyzing data from a 10 month deployment of 30 seismometers over this section. We located more than 30,000 events (all less than magnitude 5.5), constructed an improved 1-D velocity model, calculated focal mechanisms and cluster geometries, and determined the 3-D geometry of the interplate seismogenic zone. The seismogenic zone has a shallow bulge in front of the d'Entrecasteaux ridge, which could be explained by the ridge's buoyancy contributing to the uplift of the fore-arc islands. The seismogenic zone extends to ~45 km depth, significantly below the 26-27 km depth of the fore-arc Moho, indicating that the upper mantle wedge is not significantly serpentinized, which is consistent with the relatively high thermal parameter of the subducting plate. The maximum width of the seismogenic zone is 80 km, indicating an upper earthquake magnitude limit of Mw 7.85 ± 0.4, assuming standard rupture zone aspect ratios. The data also reveal a double seismic zone, 20 to 30 km below the seismogenic zone, which is presumably caused by flexure of the downgoing plate. ©2015. American Geophysical Union. All Rights Reserved.
Tremblay Y.,Institute Pour la Recherche et le Developpement |
Tremblay Y.,Instituto del Mar del Peru |
Thiebault A.,Institute Pour la Recherche et le Developpement |
Mullers R.,University of Cape Town |
Pistorius P.,Nelson Mandela Metropolitan University
PLoS ONE | Year: 2014
The study of ecological and behavioral processes has been revolutionized in the last two decades with the rapid development of biologging-science. Recently, using image-capturing devices, some pilot studies demonstrated the potential of understanding marine vertebrate movement patterns in relation to their proximate, as opposed to remote sensed environmental contexts. Here, using miniaturized video cameras and GPS tracking recorders simultaneously, we show for the first time that information on the immediate visual surroundings of a foraging seabird, the Cape gannet, is fundamental in understanding the origins of its movement patterns. We found that movement patterns were related to specific stimuli which were mostly other predators such as gannets, dolphins or fishing boats. Contrary to a widely accepted idea, our data suggest that foraging seabirds are not directly looking for prey. Instead, they search for indicators of the presence of prey, the latter being targeted at the very last moment and at a very small scale. We demonstrate that movement patterns of foraging seabirds can be heavily driven by processes unobservable with conventional methodology. Except perhaps for large scale processes, local-enhancement seems to be the only ruling mechanism; this has profounds implications for ecosystem-based management of marine areas. © 2014 Tremblay et al.
Vannucchi P.,University of Florence |
Sage F.,University Pierre and Marie Curie |
Phipps Morgan J.,Cornell University |
Remitti F.,University of Modena and Reggio Emilia |
Collot J.-Y.,Institute Pour la Recherche et le Developpement
Geochemistry, Geophysics, Geosystems | Year: 2012
Convergent plate boundaries accommodate intraplate displacement within a ∼100-1000 m thick shear zone. Marine geophysicists typically define this zone, the subduction channel (SC), as the sedimentary layer between the downgoing oceanic crust and the base of the upper plate. Geologists and modelers, instead, perceive the SC as a specific type of shear zone. The original theory of SCs was developed when the net accretion of marine sediments to the forearc was thought to typify a convergent margin. While erosive margins were briefly mentioned, their mechanics were not discussed in any detail. We now realize that subduction erosion is taking place at roughly half of the modern subduction margins. Here we review and revise the theory of erosive SCs (1) to unify this concept across disciplines, focusing on the meaning of the channel's boundaries; (2) to redefine the portions of the forearc included in the SC concept; and (3) to better idealize this dynamic system where material supply to the channel, fluid content, and the heterogeneity of deformation all influence the SC's upper and lower boundaries. Migration of the channel boundaries controls the downdip variation of tectonic mechanisms that shape the margin. Within the shallow, <15 km deep part of the SC, a gradual change of physical properties defines three zones; zone 1 of rapid fluid dewatering, zone 2 of overpressure, and zone 3 with metamorphic fluid release. A SC is a dynamic feature with along-strike and downdip variations caused by changes in channel material, in trapped fluid contents, and in interplate boundary geometry. Copyright 2012 by the American Geophysical Union.
Zydelis R.,Duke University |
Zydelis R.,DHI Water - Environment - Health |
Lewison R.L.,San Diego State University |
Shaffer S.A.,University of California at Santa Cruz |
And 15 more authors.
Proceedings of the Royal Society B: Biological Sciences | Year: 2011
Fisheries by catch is a recognized threat to marine mega fauna. Addressing by catch of pelagic species however is challenging owing to the dynamic nature of marine environments and vagility of these organisms. In order to assess the potential for species to overlap with fisheries, we propose applying dynamic habitat models to determine relative probabilities of species occurrence for specific oceanographic conditions. We demonstrate this approach by modelling habitats for Laysan (Phoebastria immutabilis) and black-footed albatrosses (Phoebastria nigripes) using telemetry data and relating their occurrence probabilities to observations of Hawaii-based long line fisheries in 1997-2000. We found that modelled habitat preference probabilities of black-footed albatrosses were high within some areas of the fishing range of the Hawaiian fleet and such preferences were important in explaining by catch occurrence. Conversely, modelled habitats of Laysan albatrosses overlapped little with Hawaii-based long line fisheries and did little to explain the by catch of this species. Estimated patterns of albatross habitat overlap with the Hawaiian fleet corresponded to by catch observations: black-footed albatrosses were more frequently caught in this fishery despite being 10 times less abundant than Laysan albatrosses. This case study demonstrates that dynamic habitat models based on telemetry data may help to project interactions with pelagic animals relative to environmental features and that such an approach can serve as a tool to guide conservation and management decisions. © 2011 The Royal Society.
Costalago D.,Institute pour la Recherche et le Developpement |
Costalago D.,Nelson Mandela Metropolitan University
Vie et Milieu | Year: 2015
In the Atlantic Ocean, small pelagic fish occasionally execute long distance migrations before they become adults. However, in the Mediterranean Sea, the populations of the most common small pelagic fish, anchovy and sardine, seem to be generally more confined to relatively small areas. Particularly in the NW Mediterranean, local environmental conditions, such as mesoscale events, wind forcing or river run-offs, can contribute to shaping the dispersal patterns of fishes, especially in their early life stages. Intrinsic factors such as dietary preferences, swimming abilities or feeding behavior can also play an essential role in the distribution of the populations in the region. Some studies have been done in the NW Mediterranean in order to elucidate which factors are playing the main roles in the dispersal and in the ecology of anchovy and sardine larvae and juveniles. Nevertheless, a holistic evaluation of all the potential attributes conditioning the distribution of early life history anchovy and sardine is lacking. It is therefore necessary to clearly highlight the most determinant biological and environmental features for the dispersion of the early life stages of anchovy and sardine in the NW Mediterranean. This review of the state-of-the-art in the distribution and the trophic ecology of the larvae and juveniles of these populations, pointing out the main methods utilized, will also help to identify some of the major gaps of knowledge and discrepancies that might conduce to future research.
PubMed | Institute pour la Recherche et le Developpement, Nelson Mandela Metropolitan University and University of Cape Town
Type: Journal Article | Journal: PloS one | Year: 2014
The study of ecological and behavioral processes has been revolutionized in the last two decades with the rapid development of biologging-science. Recently, using image-capturing devices, some pilot studies demonstrated the potential of understanding marine vertebrate movement patterns in relation to their proximate, as opposed to remote sensed environmental contexts. Here, using miniaturized video cameras and GPS tracking recorders simultaneously, we show for the first time that information on the immediate visual surroundings of a foraging seabird, the Cape gannet, is fundamental in understanding the origins of its movement patterns. We found that movement patterns were related to specific stimuli which were mostly other predators such as gannets, dolphins or fishing boats. Contrary to a widely accepted idea, our data suggest that foraging seabirds are not directly looking for prey. Instead, they search for indicators of the presence of prey, the latter being targeted at the very last moment and at a very small scale. We demonstrate that movement patterns of foraging seabirds can be heavily driven by processes unobservable with conventional methodology. Except perhaps for large scale processes, local-enhancement seems to be the only ruling mechanism; this has profounds implications for ecosystem-based management of marine areas.
Kuhn C.E.,National Oceanic and Atmospheric Administration |
Tremblay Y.,Institute pour la Recherche et le Developpement |
Ream R.R.,National Oceanic and Atmospheric Administration |
Gelatt T.S.,National Oceanic and Atmospheric Administration
Endangered Species Research | Year: 2010
The foraging strategies of diving marine species are often categorized into 3 fundamental groups (epipelagic, mesopelagic, and benthic foraging) based on diving, habitat use, and diet studies. Because these foraging strategies are influenced by the distribution and behavior of the prey being targeted, we would expect search behavior and space use to differ depending on the strategy employed. Since northern fur seals Callorhinus ursinus display both epipelagic and benthic foraging strategies, they were an ideal model to test the hypothesis that fine-scale movement and space-use patterns will vary when animals use markedly different foraging strategies. Dive bouts were characterized into foraging strategies based on numerous dive parameters (depth, duration, etc.). For each strategy, we compared movement patterns (e.g. transit rate and path straightness) and space use (area-restricted search [ARS] zones) around St. Paul Island, Alaska, USA. Nearly all dive parameters were significantly different between foraging strategies (epipelagic vs. benthic). In addition, epipelagic bouts were more sinuous and covered a greater total distance than benthic bouts. However, the greater distances traveled in epipelagic bouts were due to longer bout durations, as transit rates were not different between the 2 strategies. On average, <2 ARS zones were identified per trip, and the characteristics of epipelagic and benthic ARS zones were not different. By combining dive behavior with precise at-sea locations, this study has provided a greater understanding of the fine-scale foraging behavior of northern fur seals. Monitoring changes in foraging behavior over time and comparing behavior among populations with differing population trajectories may provide more clues as to why northern fur seal numbers on St. Paul Island continue to decline. © Inter-Research 2010.
PubMed | Shirdi Sai Baba Hospital, University of Maryland Baltimore County, Navrongo Health Research Center, Voltaire and 5 more.
Type: | Journal: Clinical infectious diseases : an official publication of the Infectious Diseases Society of America | Year: 2015
The group A meningococcal vaccine (PsA-TT) clinical development plan included clinical trials in India and in the West African region between 2005 and 2013. During this period, the Meningitis Vaccine Project (MVP) accumulated substantial experience in the ethical conduct of research to the highest standards.Because of the public-private nature of the sponsorship of these trials and the extensive international collaboration with partners from a diverse setting of countries, the ethical review process was complex and required strategic, timely, and attentive communication to ensure the smooth review and approval for the clinical studies. Investigators and their site teams fostered strong community relationships prior to, during, and after the studies to ensure the involvement and the ownership of the research by the participating populations. As the clinical work proceeded, investigators and sponsors responded to specific questions of informed consent, pregnancy testing, healthcare, disease prevention, and posttrial access.Key factors that led to success included (1) constant dialogue between partners to explore and answer all ethical questions; (2) alertness and preparedness for emerging ethical questions during the research and in the context of evolving international ethics standards; and (3) care to assure that approaches were acceptable in the diverse community contexts.Many of the ethical issues encountered during the PsA-TT clinical development are familiar to groups conducting field trials in different cultural settings. The successful approaches used by the MVP clinical team offer useful examples of how these problems were resolved.ISRCTN17662153 (PsA-TT-001); ISRTCN78147026 (PsA-TT-002); ISRCTN87739946 (PsA-TT-003); ISRCTN46335400 (PsA-TT-003a); ISRCTN82484612 (PsA-TT-004); CTRI/2009/091/000368 (PsA-TT-005); PACTR ATMR2010030001913177 (PsA-TT-006); PACTR201110000328305 (PsA-TT-007).