Porquerolles Island Research Articles

Short-Range Recordings of Shallow Underwater Explosions with Short-Period and Broadband Seismometers in the Bay of Hyères, France

ABSTRACT This study presents the analysis of the seismic records of eight underwater explosions triggered by the French Navy Mine Warfare Office in December 2018 in the Bay of Hyères, southeast France. The explosions (charges of 80–680 kg TNT-equivalent) were recorded by 17 temporary stations composed of medium-to-broadband velocimeters and accelerometers and of microelectromechanical systems accelerometers with sampling rates of 250 or 500 samples per second, installed at less than 10 km from the sources. The relatively high sampling rates used in this study allow us to observe, at the same time, seismic, hydroacoustic, and acoustic signals at the shore. This experiment offers a unique opportunity to investigate the impact at the shore, and in the water, of relatively large-charge weight detonations as well as of the amplification effects of the sedimentary cover. We notably see that the hydroacoustic signal is, at the rocky sites, the most energetic wavepacket recorded, and that its observation seems to be conditioned by the bathymetry and the seabed sedimentary cover. We also show that the hydroacoustic phase can be advantageously used to precisely estimate the location and origin time of the explosions. Finally, analyses of the spectrum and site response along the shore and at a bell tower on the Porquerolles Island provide interesting insights on the mitigation of the possible nuisance caused at the shore by the disposal of unexploded historical ordnance.

The Grande Passe 1 shipwreck, 2nd century BC, Hyères, France

The Grande Passe 1 shipwreck lies 45 m deep off the coast of Porquerolles Island, Hyères, southern France. Discovered in 1975, new fieldwork campaigns in 2017 and 2018 brought to light a part of the hull (keel, planking, frames), indications of its cargo from the 2nd century BC (Graeco-Italic amphorae), and three well preserved iron anchors. This paper provides a first archaeological analysis of the wreck.

Conflicts and acceptability of visitation management measures for a marine protected area: The case of Porquerolles, Port-Cros National Park

Along the touristic coastlines, Marine Protected Areas are particularly coveted by an increasing number of visitors. This influx has encouraged the implementation of monitoring and management measures by managers of protected areas that promote tourism consistent with biodiversity conservation. However, the choices that need to be made to enforce these measures are particularly complex for they need to take into account the concerns of not only a territory that produces wealth for the local population and those who live in close proximity (due to the attraction to tourists) but also those of a territory that is sensitive and vulnerable environmentally speaking. With regard to the approach initiated by the Port-Cros National Park on the carrying capacity and character of the Park's core areas, we conducted a conflict diagnosis on Porquerolles, an island within the core area. Our aim was to bring to light the territorial realities relating to past and recent conflict situations, the reasons for disputes and the methods of managing them, thus providing focal points that would be useful to help with implementing measures relating to visitation to the island. This study, comprised of interviews, questionnaires, in-situ observations and analyses of legal documents, enabled us to go back over the conflicting history of the territory. It revealed a characterisation and spatialisation of disputes, including breaches of the Environmental Code. This research provided a framework within which the factors influencing the acceptability of visitor management measures could be reflected upon. Three conditions necessary for acceptability were identified for the island of Porquerolles using the conflict analysis: recognising and addressing a differential threshold of acceptance relating to visitation; strengthening trust between the different stakeholders and the proximities on the territory; envisaging a firmer penal policy to reduce the feeling of injustice associated with specific efforts in environmental protection.

First observation of Anguis sp. in the island of Porquerolles (Var, France)

First observation of Anguis sp. in the island of Porquerolles (Var, France)

Benefit of the Potential Future Hyperspectral Satellite Sensor (BIODIVERSITY) for Improving the Determination of Water Column and Seabed Features in Coastal Zones

Most of the studies dealing with seabed mapping from hyperspectral images have been carried out using airborne data although hyperspectral satellite sensors have already been or are planned to be launched for the near future (hyperspectral imager for the coastal ocean (HICO) environmental mapping and analysis program (ENMAP) or BIODIVERSITY). The objective of this study is to evaluate the benefit of a BIODIVERSITY-like sensor to determine the bio-optical properties of the water column, namely the Chlorophyll-a concentration, the suspended particulate matter (SPM) concentration, the absorption coefficient of the colored dissolved organic matter (CDOM), the bathymetry and the composition of the seabed, according to its spatial resolution and spectral resolution and its signal to noise ratio. For this purpose, radiative transfer simulations are analyzed together with remote sensing hyperspectral airborne data acquired above the Porquerolles Island (France). The retrieval performance of all in-water and seabed parameters derived from the inversion of BIODIVERSITY-like data is compared with the performance obtained using ENMAP and HICO spatial and radiometric specifications. It is shown that a BIODIVERSITY-like sensor significantly improves the estimation performance of the water column parameters. Furthermore, BIODIVERSITY-like sensor is highly appropriate for seabed mapping when bottom pixels are composed of pure material (e.g., Sand or Posidonia ) in shallow waters when seabed depth is less than 10 m. Conversely, the performance of the inversion deteriorates when seabed pixels are composed of mixed materials (e.g., Sand mixed with Posidonia ). It is also shown that the concentration of chlorophyll, SPM and CDOM absorption are less sensitive to noise level than depth and seabed abundance.

Report on the 1st Thematic School on Dielectrics 2018

The first Thematic School on Dielectrics was organized under the sponsorship of CNRS—French National Research Center, and supported by DEIS, on Porquerolles Island in France, June 24 to 29, 2018. The topic of this first edition was the ageing and reliability of dielectric materials and related structures.

Quantification of cliff retreat in coastal Quaternary sediments using anatomical changes in exposed tree roots

AbstractSea cliffs represent 80% of the world's coasts and can be found virtually in all types of morphogenetic environments. Most studies on rocky environments focused on the impacts of modern sea level rise on cliff stability derived from sequential surveys, direct measurements or erosional features in anthropogenic structures. In this study, we explore the potential of dendrogeomorphic techniques to quantify multidecadal changes in coastal environments on Porquerolles Island (France). We sampled a total of 56 cross‐sections from 16 Pinus halepensis Mill. roots growing on former alluvial deposits and on sandy‐gravelly cliffs to quantify mean annual cliff retreat rates as well as changes in cliff geometry. Anatomical changes in roots have been used successfully in the past to quantify continuous denudation rates on slopes, channel incision and gullying processes but the approach has not been used so far in a coastal cliff context. At Porquerolles Island, reconstructed rates of cliff retreat cover 30–40 years and show average erosion rates between 0.6 and 3.9 cm yr−1 (average: 2.1 cm yr−1). Highest rates are observed at Pointe de la Tufière (2.6–3.9 cm yr−1), a small rock promontory that is more exposed to wave and storm surges than the remainder of the study area. By contrast, lower erosion rates are recorded at cliffs protected by the La Courtade pocket beach (0.6–1.9 cm yr−1). This contribution demonstrates that dendrogeomorphic analyses of roots clearly have a significant potential and that they are a powerful tool for the quantification of multidecadal rates of cliff retreat in areas where measurements of past erosion are lacking. More specifically, the approach also has clear advantages over the shorter time series obtained with repeat monitoring (e.g. terrestrial laser scanning, sensors, erosion pins) or over longer, but more coarsely resolved records obtained from aerial photographs or radio‐nuclides. © 2018 John Wiley & Sons, Ltd.

Distribution of natural and anthropogenic radionuclides in northwest Mediterranean coastal sediments

The distribution of radionuclides in NW Mediterranean coastal sediments, and the processes controlling their abundance were investigated in three cores taken near the island of Porquerolles and one offshore Monaco. The sediments collected near Porquerolles were strongly anoxic due to diagenetic processes involved in the decomposition of organic matter, whereas they transitioned from oxic to anoxic at a depth of 4 cm beneath the seawater interface at Monaco. Organic carbon (OC) was more abundant in sediments at Porquerolles (by about a factor of 3–5) than at Monaco and elsewhere in the coastal NW Mediterranean. Sediment cores collected NE of Porquerolles also possessed elevated uranium concentrations that correlated with high OC content and strong reducing conditions. The 239,240Pu and 241Am activities in surficial sediments ranged from 1 to 5.7 Bq kg−1 and 0.3 to 1 Bq kg−1, respectively, while the 137Cs activity ranged from 0.3 to 6.2 Bq kg−1. The mean activity ratios of 241Am/239,240Pu and 238Pu/239,240Pu in Porquerolles and Monaco sediments were similar to the global fallout ratios. Sediment inventories of global fallout 239,240Pu (430–800 Bq m−2) and 241Am (150–285 Bq m−2) were by about a factor of 5–10 higher at Porquerolles, whereas the inventory of 137Cs (430–1000 Bq m−2) was substantially lower at the investigated stations than have been reported elsewhere at similar latitudes. Specific local conditions characterised by high OC sediment loads due to the growth and mortality of Posidonia oceanica have been responsible for deposition of large amounts of seagrass tissues at the NE corner of Porquerolles, which have had a profound effect on the distribution of radionuclides in the sediments.

On the Nature of Near-Inertial Oscillations in the Uppermost Part of the Ocean and a Possible Route toward HF Radar Probing of Stratification

AbstractInertial band response of the upper ocean to changing wind is studied both theoretically and by analysis of observations in the northwestern Mediterranean. On the nontraditional f plane, because of the horizontal component of the earth’s rotation for waves of inertial band with frequencies slightly below the local inertial frequency f, there is a waveguide in the mixed layer confined from below by the pycnocline. It is argued that when the stratification is shallow these waves are most easily and strongly excited by varying winds as near-inertial oscillations (NIOs). These motions have been overlooked in previous studies because they are absent under the traditional approximation. The observations that employed buoys with thermistors, ADCPs, and two 16.3-MHz Wellen Radar (WERA) HF radars were carried out in the Gulf of Lion in April–June 2006. The observations support the theoretical picture: a pronounced inertial band response occurs only in the presence of shallow stratification and is confined to the mixed layer, and the NIO penetration below the stratified layer is weak. NIO surface magnitude and vertical localization are strongly affected by the presence of even weak density stratification in the upper 10 m. The NIO surface signatures are easily captured by HF radars. Continuous 1.8-yr HF observations near the Porquerolles Island confirm that shallow stratification is indeed the precondition for a strong NIO response. The response sensitivity to stratification provides a foundation for developing HF radar probing of stratification and, indirectly, vertical mixing, including spotting dramatic mixing events and spikes of vertical heat, mass, and momentum exchange.

A peaceful zone bordering two Argentine ant (Linepithema humile) supercolonies

In invasion areas, the Argentine ant (Linepithema humile) forms huge supercolonies with free exchange of individuals among nests. Two continental supercolonies on the French mediterranean coast, the Main European supercolony and the Corsican supercolony, are known to contain workers showing moderate to high levels of inter-supercolony aggression. We performed chemical and behavioral assays using workers from eight coastal sites in southeastern France covering a geographical zone that includes nests of the two supercolonies, to determine the nature of worker interactions in a supercolony boundary zone. We examined how the chemical and behavioral clines vary across the borders of the Main and Corsican supercolonies. Our results on Giens peninsula and Porquerolles island populations bordering the Main supercolony reveal the existence of a peaceful border zone with no aggression between workers of the Main supercolony and the Corsican supercolony. The chemical results, however, exhibited qualitative similarity to those observed in the Corsican supercolony and revealed both quantitative and qualitative chemical differences from those observed in the Main supercolony. These peaceful populations may result from fusion and/or genetic crosses between the two supercolonies, and we hypothesize that such peaceful border zones are instrumental in the evolution of supercolonies.

Ecole thématique CNRS « Etudier les réseaux sociaux », Porquerolles,10-14 septembre 2012

CNRS Thematic School “Studying Social Networks”, Porquerolles, 10-14 September 2012: Following the success of the first CNRS Summer School on social networks in Cargèse, Corsica, 15-20 September 2008 (see the preceding article by Alain Degenne), the organizers and the CNRS decided that a second thematic school should be organized on the Mediterranean island of Porquerolles, this time with more of a concentration on social sciences other than sociology, and specifically on history. This is a report on this rather successful second thematic school on social networks.

Preliminary quantification of the erosion of sandy-gravelly cliffs on the island of Porquerolles (Provence, France) through dendrogeomorphology, using exposed roots of Aleppo pine (Pinus halepensis Mill.)

This study is a first attempt to specify the geodynamic processes leading to the erosion of detrital quaternary cliffs on the island of Porquerolles, and to quantify the rate of erosion by means of dendrogeomorphology. The island is located in the Mediterranean Sea, off the coast of Provence (France). This method identifies the roots of Aleppo pine (Pinus halepensis Mill.) that have been unearthed by cliff retreat. The year of denudation is revealed by the net change in tracheid anatomy in tree rings, so that the retreating rates of cliffs can be established and the ratio between the distance of loosening and the number of years since denudation can be assessed. 13 root samples were used to determine that the cliff retreat is due to small rockfalls, at an average rate of 2.5 cm/a. This value is compared to other rates of erosion quantified on rocky or sandy shores. A review of the method and a comparison with methods based on photogrammetry and micrometrics are proposed.

Pioneer marine biofilms on artificial surfaces including antifouling coatings immersed in two contrasting French Mediterranean coast sites

Marine biofilm communities that developed on artificial substrata were investigated using molecular and microscopic approaches. Polystyrene, Teflon® and four antifouling (AF) paints were immersed for 2 weeks at two contrasting sites near Toulon on the French Mediterranean coast (Toulon military harbour and the natural protected area of Porquerolles Island). Biofilms comprising bacteria and diatoms were detected on all the coatings. The population structure as well as the densities of the microorganisms differed in terms of both sites and coatings. Lower fouling densities were observed at Porquerolles Island compared to Toulon harbour. All bacterial communities (analysed by PCR-DGGE) showed related structure, controlled both by the sites and the type of substrata. Pioneer microalgal communities were dominated by the same two diatom species, viz. Licmophora gracilis and Cylindrotheca closterium, at both sites, irrespective of the substrata involved. However, the density of diatoms followed the same trend at both sites with a significant effect of all the AF coatings compared to Teflon and polystyrene.

Preface

This special issue of DCDS-S is dedicated to the proceedings of the second edition of the Conference Numerical Models for Controlled Fusion (NMCF09) that was held on the Island of Porquerolles (France) April 20-24, 2009. “<br><br> For more information please click the “Full Text” above.

STRATEGY FOR THE CONSERVATION OF FRENCH OLIVE GENETIC RESOURCES

ISHS XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): Olive Trends Symposium - From the Olive Tree to Olive Oil: New Trends and Future Challenges STRATEGY FOR THE CONSERVATION OF FRENCH OLIVE GENETIC RESOURCES

Frontiers in Catalysis and Materials Chemistry: The 3rdIDECAT Conference on Catalysis

Frontiers in Catalysis and Materials Chemistry: The 3^rdIDECAT Conference on Catalysis

Foreword

This special issue of RCM contains a selection of 25 papers presented at the 2nd Joint European Stable Isotope User Meeting (JESIUM) held at Presqu'île de Giens, France, from 31st August to 5th September 2008. JESIUM, the Joint European Stable Isotope User Meeting, is initiated by the national associations/networks of stable isotope users from across Europe (BASIS Benelux, ESIR Eastern and central Europe, GASIR Germany, SFIS France, SIMSUG UK, and SINA Austria). The objectives of JESIUM are to bring together scientists with a broad range of interests in stable isotopes, to encourage communication across disciplines and country boundaries, to provide the opportunity to discuss theoretical and methodological difficulties, and to exchange ideas about how techniques might be transferred to other areas of research. Following the success of the first JESIUM meeting organised by Rebecca Hood-Nowotny in Vienna (2004) with the contribution of the Stable Isotope Network of Austria (SINA), the French Society of Stable Isotopes (SFIS) was proud to organise the second JESIUM (2008) in the south of France under the coordination of Jaleh Ghashghaie. The JESIUM objectives were successfully achieved in a meeting that gathered approximately 290 participants from diverse backgrounds, mostly from Europe but also from all around the world (about 30 countries were represented), and stimulated the active participation of commercial sponsors (25 companies). JESIUM 2008 was highly successful and it was a great pleasure to host this event in France. On behalf of the organizing committee, we would like to thank all the participants for the high quality of their presentations, the conveners for selecting the talks and organizing the sessions and discussions, and the sponsors for supporting this meeting. Methodological advances in stable isotope studies Physiology & Biochemistry across the spectrum of life forms Plant Ecophysiology: from leaf to ecosystem Soil, Marine & Freshwater Ecology Hydrology, Earth Science & Cosmochemistry Climatology, Palaeoclimatology & Archaeology Isotopic signatures as diagnostic & decision tools for society New concepts and developments A total of 84 oral communications and over 200 posters were presented, including one senior and one or two junior keynote lectures and about 10 regular talks per session. The diversity and quality of communications (talks as well as posters) and the discussions (both formal and informal) guaranteed an interesting program. Young scientists were especially promoted during JESIUM 2008. In the preparation phase, every European Association selected a young scientist to present a ‘Junior Keynote’ lecture. Likewise, and under the benevolent control of Tom Bullen, prizes for the ‘best overall presentation by a young scientist’ and the ‘best poster by a young scientist’ were awarded to Britta Hartard and Mehmet Senbayram, respectively. JESIUM 2008 was characterized by a culture of openness, collaboration and fun, and was full of memorable moments: a musical opening, a cruise to Porquerolles Island, and an already famous dancing gala night. To keep pace with the innovations and to reap maximum benefit for all, it is necessary for us to continue to collaborate and to educate scientists across Europe in this exciting and enlightening branch of science. It is with this in mind that we are pleased to announce the next JESIUM in 2012 in Germany; for the latest information, see the JESIUM website (http://www.jesium.eu). Please enjoy the quality of the papers and be inspired by the JESIUM 2008 spirit.

A century of warfare shoots holes in anti-Caulerpa campaign

Effort to have all varieties of the marine alga Caulerpa taxifolia listed as noxious weeds hinges on the argument that the alga's proliferation in the Mediterranean Sea is a cause and not a consequence of environmental degradation. Until now, the occurrence of two populations in a pristine part of the northern Mediterranean near the island of Porquerolles has upheld this claim. Here we show that the alga's development at Porquerolles is indeed a consequence of environmental degradation caused by military weapons' impacts on seagrass beds during the last century. The available data show that substratum enrichment plays a key role in fostering development of Caulerpa, irrespective of whether this results directly from pollution or from the impacts of pollution and other anthropogenic factors on benthic vegetation cover.

A century of warfare shoots holes in anti-Caulerpa campaign

AbstractEffort to have all varieties of the marine alga Caulerpa taxifolia listed as noxious weeds hinges on the argument that the alga's proliferation in the Mediterranean Sea is a cause and not a consequence of environmental degradation. Until now, the occurrence of two populations in a pristine part of the northern Mediterranean near the island of Porquerolles has upheld this claim. Here we show that the alga's development at Porquerolles is indeed a consequence of environmental degradation caused by military weapons' impacts on seagrass beds during the last century. The available data show that substratum enrichment plays a key role in fostering development of Caulerpa, irrespective of whether this results directly from pollution or from the impacts of pollution and other anthropogenic factors on benthic vegetation cover.

Joint construction and appropriation of indicators by users, managers and scientists: the case study of Port-Cros and Porquerolles tourist frequentation observatory

Port-Cros, a national marine park, and its neighbouring island of Porquerolles are two French Mediterranean islands both managed by the Port-Cros National Park. Numerous visitors are attracted by their preserved environmental heritage. Thus, it is paramount for the Park Board to consider the consequences of the massive influx of sailors and tourists. A precise study of frequentation was started in 2001 with Geomer, an academic geography laboratory. This first stage was the beginning of a fruitful collaboration between scientists and the park managers; it drove the latter to want to continue the study in order to develop a tourist frequentation observatory. This project progressively gathered additional actors, i.e. sector chiefs and field agents of the park and local populations. Bountiles, a helping tool for decision-making, was jointly constructed and permitted appropriation of a part of it by any of the actors to their own profile and expectations. Now, this local context-adapted observatory is operational, and its implementation has been accompanied by the scientists, according to the park request.