114 research outputs found

    Study of Water Speed Sensitivity in a Multifunctional Thick-film Sensor by Analytical Thermal Simulations and Experiments

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    The present paper deals with an application of the analytical thermal simulator DJOSER. It consist of the characterization of a water speed sensor realized in hybrid technology. The capability of the thermal solver to manage the convection heat exchange and the effects of the passivating layers make the simulation work easy and fast.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

    Oceanic long-distance navigation : do experienced migrants use the earth\u27s magnetic field?

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    Albatrosses and sea turtles are known to perform extremely long-distance journeys between disparate feeding areas and breeding sites located on small, isolated, oceanic islands or at specific coastal sites. These oceanic journeys, performed mainly over or through apparently featureless mediums, indicate impressive navigational abilities, and the sensory mechanisms used are still largely unknown. This research used three different approaches to investigate whether bi-coordinate navigation based on magnetic field gradients is likely to explain the navigational performance of wandering albatrosses in the South Atlantic and Indian Oceans and of green turtles breeding on Ascension Island in the South Atlantic Ocean. The possibility that magnetic field parameters can potentially be used in a bi-coordinate magnetic map by wandering albatrosses in their foraging area was investigated by analysing satellite telemetry data published in the literature. The possibilities for using bi-coordinate magnetic navigation varied widely between different areas of the Southern Oceans, indicating that a common mechanism, based on a bi-coordinate geomagnetic map alone, was unlikely for navigation in these areas. In the second approach, satellite telemetry was used to investigate whether Ascension Island green turtles use magnetic information for navigation during migration from their breeding island to foraging areas in Brazilian coastal waters. Disturbing magnets were applied to the heads and carapaces of the turtles, but these appeared to have little effect on their ability to navigate. The only possible effect observed was that some of the turtles with magnets attached were heading for foraging areas slightly south of the control turtles along the Brazilian coast. In the third approach, breeding female green turtles were deliberately displaced in the waters around Ascension Island to investigate which cues these turtles might use to locate and return to the island; the results suggested that cues transported by wind might be involved in the final stages of navigation

    Satellite tracking identifies important foraging areas for loggerhead turtles frequenting the Adriatic Sea, Central Mediterranean

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    The Adriatic Sea is one of the main foraging areas for marine turtles of the Mediterranean Sea, but the specific high-use sites are poorly known, due to the scarceness of satellite tracking data available for juvenile turtles frequenting the area. In the present study, we tracked 8 juvenile and adult loggerhead turtles (Caretta caretta) that were released along the north-western Adriatic coast after a rehabilitation period having been equipped with Argos-linked satellite transmitters. Tracked turtles displayed quite variable movement patterns, but mostly remained in the north-western Adriatic, especially during the summer months. A marked preference for specific coastal sites was revealed in many turtles, that actively moved towards these specific locations when released south of it or having spent the winter away. Pooling these data with those obtained in previous studies on a further 10 turtles, we highlighted the presence of two main high-use areas, north and south of the Po River delta, where future conservation actions may then be focused

    Satellite tracking of leatherback and loggerhead sea turtles on the Southeast African coastline

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    The waters of southeast Africa contain important habitats for several sea turtle species, including the leatherback Dermochelys coriacea, loggerhead Caretta caretta, hawksbill Eretmochelys imbricata, green Chelonia mydas, and olive ridley turtle Lepidochelys olivacea. Many of these species are of conservation concern (Rakotoniria & Cooke, 1994; Thorson et al., 2012; Nel et al., 2013) and vulnerable to regional threats such as fisheries by-catch or boat-strikes (Bourjea et al., 2008; Grantham et al., 2008; Pusineri & Quillard, 2008). To help in the development of effective conservation plans for these species, many conservation or research organisations have used satellite transmitters to help identify critical habitats for sea turtles (Harris et al., 2015; Robinson et al., 2016). Here, we review the movement patterns of sea turtles that have been tracked through satellite telemetry from their nesting beaches on the east coast of South Africa

    Movement patterns of green turtles in Brazilian coastal waters described by satellite tracking and flipper tagging

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    The movements of 8 green turtles Chelonia mydas in Brazilian coastal waters were tracked using transmitters linked to the Argos system for periods of between 1 and 197 d. These were the first tracking data gathered on juveniles of this species in this important foraging ground. Information was integrated with that collected over a decade using traditional flipper-tagging methods at the same site. Both satellite telemetry and flipper tagging suggested that turtles undertook 1 of 3 general patterns of behaviour: pronounced long range movements (>100 km), moderate range movements (<100 km) or extended residence very close to the capture/release site. There seemed to be a general tendency for the turtles recaptured/tracked further afield to have been among the larger turtles captured. Satellite tracking of 5 turtles which moved from the release site showed that they moved through coastal waters; a factor which is likely to predispose migrating turtles to incidental capture as a result of the prevailing fishing methods in the region. The movements of the 3 turtles who travelled less than 100 km from the release site challenge previous ideas relating to home range in green turtles feeding in sea grass pastures. We hypothesise that there may be a fundamental difference in the pattern of habitat utilisation by larger green turtles depending on whether they are feeding on seagrass or macroalgae. Extended tracking of 2 small turtles which stayed near the release point showed that small juvenile turtles, whilst in residence in a particular feeding ground, can also exhibit high levels of site-fidelity with home ranges of the order of several square kilometers

    Pan-Atlantic analysis of the overlap of a highly migratory species, the leatherback turtle, with pelagic longline fisheries

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    This is the final version of the article. Available from the publisher via the DOI in this record.Large oceanic migrants play important roles in ecosystems, yet many species are of conservation concern as a result of anthropogenic threats, of which incidental capture by fisheries is frequently identified. The last large populations of the leatherback turtle, Dermochelys coriacea, occur in the Atlantic Ocean, but interactions with industrial fisheries could jeopardize recent positive population trends, making bycatch mitigation a priority. Here, we perform the first pan-Atlantic analysis of spatio-temporal distribution of the leatherback turtle and ascertain overlap with longline fishing effort. Data suggest that the Atlantic probably consists of two regional management units: northern and southern (the latter including turtles breeding in South Africa). Although turtles and fisheries show highly diverse distributions, we highlight nine areas of high susceptibility to potential bycatch (four in the northern Atlantic and five in the southern/equatorial Atlantic) that are worthy of further targeted investigation and mitigation. These are reinforced by reports of leatherback bycatch at eight of these sites. International collaborative efforts are needed, especially from nations hosting regions where susceptibility to bycatch is likely to be high within their exclusive economic zone (northern Atlantic: Cape Verde, Gambia, Guinea Bissau, Mauritania, Senegal, Spain, USA and Western Sahara; southern Atlantic: Angola, Brazil, Namibia and UK) and from nations fishing in these high-susceptibility areas, including those located in international waters.Work in Gabon was financially supported by the Large Pelagics Research Center through National Oceanographic and Atmospheric Agency award no. NA04NMF4550391, the UK Defra Darwin Initiative, the Shellshock Campaign (European Association for Zoos and Aquaria) and the UK Natural Environment Research Council. Sea turtle monitoring programmes in Gabon were financially supported by the Wildlife Conservation Society and by the Gabon Sea Turtle Partnership with funding from the Marine Turtle Conservation Fund (United States Fish and Wildlife Service, US Department of the Interior). Four of the satellite tags were deployed in Canadian waters by M. James (Dalhousie University) and the Canadian Sea Turtle Network, with the funding support of Canadian Sea Turtle Network leatherback field research provided by R. A. Myers, the Canadian Wildlife Federation, Environment Canada and WWF-Canada. Work in French Guiana was financially supported by CNES, DEAL and the European Union.This study results from the collaborative effort of 10 data providers, which have satellite-tracked leatherback turtles in the Atlantic Ocean since 1995, through their voluntary participation in the Trans-Atlantic Leatherback Conservation Initiative (TALCIN), a WWF-led initiative. We thank C. Drews (WWF-International) and Jean-Yves Georges (IPHC-CNRS) for having initiated this project. Significant contributions were made by A. Fonseca and M. L. Felix and the WWF Guianas office in fostering this project to secure its continuation. We thank those involved in the sea turtle restoration plan in French Guiana (DEAL, ONCFS, Kulalasi NGO, Kwata, the Reserve Naturelle de l'Amana, Chiefs of Awala and Yalimapo), Yvon Le Maho (IPHC-CNRS) for having initiated the leatherback tracking programme in French Guiana, colleagues from the Regional Program for Sea Turtles Research and Conservation of Argentina–PRICTMA, Aquamarina and Fundación Mundo Marino, the onboard scientific observers from PNOFA-DINARA, the crew and owner of the F/V Torres del Paine, the artisanal fishermen from Kiyú, San José, Uruguay, D. del Bene (PROFAUMA), Z. Di Rienzo and colleagues from Karumbé, the University of Pisa for initiating the satellite tagging programmes in South Africa, and the South African Department of Environmental Affairs for continuing the work in cooperation with Dr Nel from the Nelson Mandela Metropolitan University, Port Elizabeth and Ezemvelo KZN Wildlife. We thank M. L. Felix for her efforts in the deployment of satellite tags in Suriname and the Nature Conservation Division Suriname for facilitating these research efforts. P.M. thanks C. Palma for his help in dealing with ICCAT's database, C. Ere, as well as the GIS training and support received from SCGIS and the ESRI Conservation Program, which allowed processing of fishing-effort data. We thank J. Parezo for her careful reading of the manuscript. All authors designed the study and contributed data; S.F, M.S.C., P.M. and M.J.W. compiled the data; S.F., M.A.N. and A.L. coordinated and supervised the project; S.F., M.J.W., P.M. and B.J.G. led the data analysis and interpretation with contributions from all authors; the manuscript was developed by S.F. and M.J.W. as lead authors, with contributions from all authors

    Pan-Atlantic analysis of the overlap of a highly migratory species, the leatherback turtle, with pelagic longline fisheries

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    Large oceanic migrants play important roles in ecosystems, yet many species are of conservation concern as a result of anthropogenic threats, of which incidental capture by fisheries is frequently identified. The last large populations of the leatherback turtle, Dermochelys coriacea, occur in the Atlantic Ocean, but interactions with industrial fisheries could jeopardize recent positive population trends, making bycatch mitigation a priority. Here, we perform the first pan-Atlantic analysis of spatio-temporal distribution of the leatherback turtle and ascertain overlap with longline fishing effort. Data suggest that the Atlantic probably consists of two regional management units: northern and southern (the latter including turtles breeding in South Africa). Although turtles and fisheries show highly diverse distributions, we highlight nine areas of high susceptibility to potential bycatch (four in the northern Atlantic and five in the southern/equatorial Atlantic) that are worthy of further targeted investigation and mitigation. These are reinforced by reports of leatherback bycatch at eight of these sites. International collaborative efforts are needed, especially from nations hosting regions where susceptibility to bycatch is likely to be high within their exclusive economic zone (northern Atlantic: Cape Verde, Gambia, Guinea Bissau, Mauritania, Senegal, Spain, USA and Western Sahara; southern Atlantic: Angola, Brazil, Namibia and UK) and from nations fishing in these high-susceptibility areas, including those located in international waters

    Pan-atlantic analysis of the overlap of a highly migratory species, the leatherback turtle, with pelagic longline fisheries

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    Large oceanic migrants play important roles in ecosystems, yet many species are of conservation concern as a result of anthropogenic threats, of which incidental capture by fisheries is frequently identified. The last large populations of the leatherback turtle, Dermochelys coriacea, occur in the Atlantic Ocean, but interactions with industrial fisheries could jeopardize recent positive population trends, making bycatch mitigation a priority. Here, we perform the first pan-Atlantic analysis of spatio-temporal distribution of the leatherback turtle and ascertain overlap with longline fishing effort. Data suggest that the Atlantic probably consists of two regional management units: northern and southern (the latter including turtles breeding in South Africa). Although turtles and fisheries show highly diverse distributions, we highlight nine areas of high susceptibility to potential bycatch (four in the northern Atlantic and five in the southern/equatorial Atlantic) that are worthy of further targeted investigation and mitigation. These are reinforced by reports of leatherback bycatch at eight of these sites. International collaborative efforts are needed, especially from nations hosting regions where susceptibility to bycatch is likely to be high within their exclusive economic zone (northern Atlantic: Cape Verde, Gambia, Guinea Bissau, Mauritania, Senegal, Spain, USA and Western Sahara; southern Atlantic: Angola, Brazil, Namibia and UK) and from nations fishing in these high-susceptibility areas, including those located in international waters

    Network analysis of sea turtle movements and connectivity: A tool for conservation prioritization

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    This is the final version. Available on open access from Wiley via the DOI in this recordData availability statement: The data that support the findings of this study are available in the Supplementary Material of this article and Zenodo (https://doi.org/10.5281/zenodo.5898578). Details for all animals included in this study are provided in Appendices S1 and S2. Data used to create the spatial networks are listed in the Appendices S3 and S4. The geospatial files for all networks are available on the Migratory Connectivity in the Ocean Project website (https://mico.eco) and Dryad (https://doi.org/10.5061/dryad.j3tx95xg9). Additional data that support the findings of this study are available from the corresponding author upon reasonable request.Aim Understanding the spatial ecology of animal movements is a critical element in conserving long-lived, highly mobile marine species. Analyzing networks developed from movements of six sea turtle species reveals marine connectivity and can help prioritize conservation efforts. Location Global. Methods We collated telemetry data from 1235 individuals and reviewed the literature to determine our dataset's representativeness. We used the telemetry data to develop spatial networks at different scales to examine areas, connections, and their geographic arrangement. We used graph theory metrics to compare networks across regions and species and to identify the role of important areas and connections. Results Relevant literature and citations for data used in this study had very little overlap. Network analysis showed that sampling effort influenced network structure, and the arrangement of areas and connections for most networks was complex. However, important areas and connections identified by graph theory metrics can be different than areas of high data density. For the global network, marine regions in the Mediterranean had high closeness, while links with high betweenness among marine regions in the South Atlantic were critical for maintaining connectivity. Comparisons among species-specific networks showed that functional connectivity was related to movement ecology, resulting in networks composed of different areas and links. Main conclusions Network analysis identified the structure and functional connectivity of the sea turtles in our sample at multiple scales. These network characteristics could help guide the coordination of management strategies for wide-ranging animals throughout their geographic extent. Most networks had complex structures that can contribute to greater robustness but may be more difficult to manage changes when compared to simpler forms. Area-based conservation measures would benefit sea turtle populations when directed toward areas with high closeness dominating network function. Promoting seascape connectivity of links with high betweenness would decrease network vulnerability.International Climate Initiative (IKI)German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU

    Green and hawksbill turtles in the Lesser Antilles demonstrate behavioural plasticity in inter-nesting behaviour and post-nesting migration

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    Satellite transmitters were deployed on three green turtles, Chelonia mydas, and two hawksbill turtles, Eretmochelys imbricata, nesting in the Lesser Antilles islands, Caribbean, between 2005-2007 to obtain preliminary information about the inter-nesting, migratory and foraging habitats in the region. Despite the extremely small dataset, both year-round residents and migrants were identified; specifically (1) two green turtles used local shallow coastal sites within 50 km of the nesting beach during all of their inter-nesting periods and then settled at these sites on completion of their breeding seasons, (2) one hawksbill turtle travelled 200 km westward before reversing direction and settling within 50 km of the original nesting beach and (3) one green and one hawksbill turtle initially nested at the proximate site, before permanently relocating to an alternative nesting site over 190 km distant. A lack of nesting beach fidelity was supported by flipper tag datasets for the region. Tagging datasets from 2002-2012 supported that some green and hawksbill individuals exhibit low fidelity to nesting beaches, whereas other females exhibited a high degree of fidelity (26 turtles tagged, 40.0km maximum distance recorded from original nesting beach). Individual turtles nesting on St Eustatius and St Maarten appear to exhibit behavioural plasticity in their inter-nesting behaviour and post-nesting migration routes in the Eastern Caribbean. The tracking and tagging data combined indicate that some of the green and hawksbill females that nest in the Lesser Antilles Islands are year-round residents, while others may nest and forage at alternative sites. Thus, continued year-round protection of these islands and implementation of protection programmes in nearby islands could contribute towards safeguarding the green and hawksbill populations of the region
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