Trawling or Visual Censuses? Methodological Bias in the Assessment of Fish Populations in Seagrass Beds   总被引：7，自引：0，他引：7  

Mireille L.  Harmelin-Vivien Patrice  Francour 《Marine Ecology》1992,13(1):41-51

Abstract. Fishes associated with the seagrass Posidonia oceanica were censused both by skid trawl and visual counts around Ischia Island, Italy. Both sampling procedures were performed during the day in summer and in winter at two sites. Significant differences in the number of species, number of individuals, biomass, and trophic structure of the fish assemblage were observed between sampling methods. Fewer fish species were recorded by visual counts than by trawling. More individuals and a greater biomass, however, were recorded from visual counts. The population of macrocarnivores (Scorpaenidae, Serranidae) were better estimated by trawling, as were canopy-dwellers (Syngnathidae; Symphodus rostratus) and benthic species (Gobiidae; Blenniidae; Bothidae). Conversely, good swimmers ( Sparidae; Coris julis, Symphodus spp.), and planktivorous fishes (Centracanthidae, Pomacentridae) mostly escaped the trawl and were better assessed by visual counts. The importance of methodological biases differed from one season to the other and was higher in summer than in winter. Particular attention should be paid to the biases induced by sampling techniques when interpreting data, and different sampling methods should be used to accurately study the fish assemblages of seagrass meadows.  相似文献   

A new classification of the Turkish terranes and sutures and its implication for the paleotectonic history of the region     

Patrice Moix  Laurent Beccaletto  Heinz W. Kozur  Cyril Hochard  Franois Rosselet  Grard M. Stampfli 《Tectonophysics》2008,451(1-4):7-39

The Turkish part of the Tethyan realm is represented by a series of terranes juxtaposed through Alpine convergent movements and separated by complex suture zones. Different terranes can be defined and characterized by their dominant geological background. The Pontides domain represents a segment of the former active margin of Eurasia, where back-arc basins opened in the Triassic and separated the Sakarya terrane from neighbouring regions. Sakarya was re-accreted to Laurasia through the Balkanic mid-Cretaceous orogenic event that also affected the Rhodope and Strandja zones. The whole region from the Balkans to the Caucasus was then affected by a reversal of subduction and creation of a Late Cretaceous arc before collision with the Anatolian domain in the Eocene. If the Anatolian terrane underwent an evolution similar to Sakarya during the Late Paleozoic and Early Triassic times, both terranes had a diverging history during and after the Eo-Cimmerian collision. North of Sakarya, the Küre back-arc was closed during the Jurassic, whereas north of the Anatolian domain, the back-arc type oceans did not close before the Late Cretaceous. During the Cretaceous, both domains were affected by ophiolite obduction, but in very different ways: north directed diachronous Middle to Late Cretaceous mélange obduction on the Jurassic Sakarya passive margin; Senonian synchronous southward obduction on the Triassic passive margin of Anatolia. From this, it appears that the Izmir-Ankara suture, currently separating both terranes, is composite, and that the passive margin of Sakarya is not the conjugate margin of Anatolia. To the south, the Cimmerian Taurus domain together with the Beydağları domain (part of the larger Greater Apulian terrane), were detached from north Gondwana in the Permian during the opening of the Neotethys (East-Mediterranean basin). The drifting Cimmerian blocks entered into a soft collision with the Anatolian and related terranes in the Eo-Cimmerian orogenic phase (Late Triassic), thus suturing the Paleotethys. At that time, the Taurus plate developed foreland-type basins, filled with flysch-molasse deposits that locally overstepped the lower plate Taurus terrane and were deposited in the opening Neotethys to the south. These olistostromal deposits are characterized by pelagic Carboniferous and Permian material from the Paleotethys suture zone found in the Mersin mélange. The latter, as well as the Antalya and Mamonia domains are represented by a series of exotic units now found south of the main Taurus range. Part of the Mersin exotic material was clearly derived from the former north Anatolian passive margin (Huğlu-type series) and re-displaced during the Paleogene. This led us to propose a plate tectonic model where the Anatolian ophiolitic front is linked up with the Samail/Baër-Bassit obduction front found along the Arabian margin. The obduction front was indented by the Anatolian promontory whose eastern end was partially subducted. Continued slab roll-back of the Neotethys allowed Anatolian exotics to continue their course southwestward until their emplacement along the Taurus southern margin (Mersin) and up to the Beydağları promontory (Antaya-Mamonia) in the latest Cretaceous–Paleocene. The supra-subduction ocean opening at the back of the obduction front (Troodos-type Ocean) was finally closed by Eocene north–south shortening between Africa and Eurasia. This brought close to each other Cretaceous ophiolites derived from the north of Anatolia and those obducted on the Arabian promontory. The latter were sealed by a Maastrichtian platform, and locally never affected by Alpine tectonism, whereas those located on the eastern Anatolian plate are strongly deformed and metamorphosed, and affected by Eocene arc magmatism. These observations help to reconstruct the larger frame of the central Tethyan realm geodynamic evolution.  相似文献   

A Coastal Bay Summer Breeze Study,Part 2: High-resolution Numerical Simulation of Sea-breeze Local Influences     

Isabelle Calmet  Patrice G. Mestayer  Alexander M. J. van Eijk  Olivier Herlédant 《Boundary-Layer Meteorology》2018,167(1):27-51

We complete the analysis of the data obtained during the experimental campaign around the semi circular bay of Quiberon, France, during two weeks in June 2006 (see Part 1). A reanalysis of numerical simulations performed with the Advanced Regional Prediction System model is presented. Three nested computational domains with increasing horizontal resolution down to 100 m, and a vertical resolution of 10 m at the lowest level, are used to reproduce the local-scale variations of the breeze close to the water surface of the bay. The Weather Research and Forecasting mesoscale model is used to assimilate the meteorological data. Comparisons of the simulations with the experimental data obtained at three sites reveal a good agreement of the flow over the bay and around the Quiberon peninsula during the daytime periods of sea-breeze development and weakening. In conditions of offshore synoptic flow, the simulations demonstrate that the semi-circular shape of the bay induces a corresponding circular shape in the offshore zones of stagnant flow preceding the sea-breeze onset, which move further offshore thereafter. The higher-resolution simulations are successful in reproducing the small-scale impacts of the peninsula and local coasts (breeze deviations, wakes, flow divergences), and in demonstrating the complexity of the breeze fields close to the surface over the bay. Our reanalysis also provides guidance for numerical simulation strategies for analyzing the structure and evolution of the near-surface breeze over a semi-circular bay, and for forecasting important flow details for use in upcoming sailing competitions.  相似文献   

Variations in the response of the dune coast of northern France to major storms as a function of available beach sediment volume          下载免费PDF全文

Adrien Crapoulet  Arnaud Héquette  Denis Marin  Franck Levoy  Patrice Bretel 《地球表面变化过程与地形》2017,42(11):1603-1622

A series of airborne topographic LiDAR data were obtained from May 2008 to January 2014 over two coastal sites of northern France (Bay of Wissant and east of Dunkirk). These data were used with wind and tide gauge measurements to assess the impacts of storms on beaches and coastal dunes, and particularly of the series of major storms that hit western Europe during the fall and early winter of 2013. Our results show a high variability in shoreline response from one site to the other, but also within each coastal site. Coastal dune erosion and shoreline retreat occurred at both sites, particularly on the coast of the Bay of Wissant where shoreline retreat up to about 40 m was measured. However, stability or even shoreline advance were also observed despite the occurrence of an extreme water level with a return period >100 years during the storm Xaver in early December 2013. Comparison of shoreline change with variations of coastal dune and upper beach volumes revealed only weak relationships. Our results nevertheless showed that shoreline behavior seems to strongly depend on the initial sediment volume on the upper beach before the occurrence of the storms. According to our measurements, an upper beach volume of about 30 m³ m^?1 between the dune toe and the mean high water level is sufficient at these sites to protect the coastal dunes from storm waves associated with high water levels with return periods >10 years. The identification of such thresholds in terms of upper beach width or sediment volume may represent valuable information for improving the management of shoreline change by providing an estimate of the minimum quantity of sand on the upper beach necessary to ensure shoreline stability in this region. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Regionality and seasonality of submesoscale and mesoscale turbulence in the North Pacific Ocean   总被引：1，自引：0，他引：1  

Hideharu Sasaki  Patrice Klein  Yoshikazu Sasai  Bo Qiu 《Ocean Dynamics》2017,67(9):1195-1216

The kinetic energy (KE) seasonality has been revealed by satellite altimeters in many oceanic regions. Question about the mechanisms that trigger this seasonality is still challenging. We address this question through the comparison of two numerical simulations. The first one, with a 1/10° horizontal grid spacing, 54 vertical levels, represents dynamics of physical scales larger than 50 km. The second one, with a 1/30° grid spacing, 100 vertical levels, takes into account the dynamics of physical scales down to 16 km. Comparison clearly emphasizes in the whole North Pacific Ocean, not only a significant KE increase by a factor up to three, but also the emergence of seasonal variability when the scale range 16–50 km (called submesoscales in this study) is taken into account. But the mechanisms explaining these KE changes display strong regional contrasts. In high KE regions, such the Kuroshio Extension and the western and eastern subtropics, frontal mixed-layer instabilities appear to be the main mechanism for the emergence of submesoscales in winter. Subsequent inverse kinetic energy cascade leads to the KE seasonality of larger scales. In other regions, in particular in subarctic regions, results suggest that the KE seasonality is principally produced by larger-scale instabilities with typical scales of 100 km and not so much by smaller-scale mixed-layer instabilities. Using arguments from geostrophic turbulence, the submesoscale impact in these regions is assumed to strengthen mesoscale eddies that become more coherent and not quickly dissipated, leading to a KE increase.  相似文献   

An urban neighborhood temperature and energy study from the CAPITOUL experiment with the Solene model     

Aurélien Hénon  Patrice G. Mestayer  Jean-Pierre Lagouarde  James A. Voogt 《Theoretical and Applied Climatology》2012,110(1-2):177-196

A methodology is proposed to analyze the radiative and thermal exchanges between a small urban neighborhood and the atmosphere based on the use of the thermoradiative model SOLENE and radiometric measurements to optimize the effective values of its constant parameters. Applied to the center of Toulouse, France, the optimization data are building surface temperatures measured with handheld radiometers and a downward-facing pyranometer during one of the intense observation periods of the CAnopy and Particles Interactions in TOulouse Urban Layer (CAPITOUL) experimental campaign. The quality of the simulations is assessed by comparing, without any other model adjustment, the model outputs for two diurnal cycles (1?day in summer and 1?day in winter) against two independent experimental datasets from fixed permanent radiometers and from sensors measuring the solar, infrared and sensible heat fluxes to the atmosphere at the top of a mast 30?m above the roofs. These simulations allow us to further analyze the separate contributions of the different surface classes, roofs, facades and pavement to these fluxes and to compare them with their counterparts observed over a neighborhood of Marseilles city center during a previous experiment. The partition is remarkably similar in Toulouse and Marseilles: 6–7% for the solar radiation, 73–76% for the infrared radiation and 17–20% for the sensible heat flux. The contribution of roofs to the infrared flux appears proportional to their plan area proportion (built density) but not the contributions to the other two fluxes. The contributions of facades to all three fluxes are roughly proportional to their fraction of the total surface area.  相似文献   

Hot orogens     

Dominique Chardon  Guest editor  Patrice Rey  Guest editor  Christian Teyssier  Guest editor  Donna L. Whitney  Guest editor 《Tectonophysics》2009,477(3-4):103

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K–Ar dating and δO–δD tracing of illitization within and outside the Shea Creek uranium prospect,Athabasca Basin,Canada     

Emmanuel Laverret  Norbert Clauer  Anthony Fallick  Julien Mercadier  Patricia Patrier  Daniel Beaufort  Patrice Bruneton 《Applied Geochemistry》2010

Isotope analyses (K–Ar, δ¹⁸O and δD) were performed on illite from both the sandstone cover and the underlying basement, close to and distant from Shea Creek, an unconformity-type U deposit (Athabasca Basin, Canada); the illite had previously been characterized crystallographically. In the barren areas away from deposit, illite is mainly of the cis-vacant 1M polytype occurring as relatively coarse-grained lath-shaped particles, while it occurs as fine-grained particles of the trans-vacant 1M type next to and in the U mineralized strata. The tectonic-induced hydrothermal system that favored illite crystallization was multi-episodic 1453 ± 2, 1330 ± 20 and probably about 1235 Ma ago. These illite-forming episodes appear to have occurred contemporaneously to those favoring the concentration of the associated U oxides, which were dated independently by the U–Pb method in the Shea Creek deposits and elsewhere in the Athabasca Basin.  相似文献   

Assessing climate change impacts,sea level rise and storm surge risk in port cities: a case study on Copenhagen   总被引：8，自引：1，他引：7  

Stéphane Hallegatte  Nicola Ranger  Olivier Mestre  Patrice Dumas  Jan Corfee-Morlot  Celine Herweijer  Robert Muir Wood 《Climatic change》2011,104(1):113-137

This study illustrates a methodology to assess the economic impacts of climate change at a city scale and benefits of adaptation, taking the case of sea level rise and storm surge risk in the city of Copenhagen, capital of Denmark. The approach is a simplified catastrophe risk assessment, to calculate the direct costs of storm surges under scenarios of sea level rise, coupled to an economic input–output (IO) model. The output is a risk assessment of the direct and indirect economic impacts of storm surge under climate change, including, for example, production and job losses and reconstruction duration, and the benefits of investment in upgraded sea defences. The simplified catastrophe risk assessment entails a statistical analysis of storm surge characteristics, geographical-information analysis of population and asset exposure combined with aggregated vulnerability information. For the city of Copenhagen, it is found that in absence of adaptation, sea level rise would significantly increase flood risks. Results call for the introduction of adaptation in long-term urban planning, as one part of a comprehensive strategy to manage the implications of climate change in the city. Mitigation policies can also aid adaptation by limiting the pace of future sea level rise.  相似文献   

Late Glacial and Holocene avulsions of the Rio Pastaza Megafan (Ecuador–Peru): frequency and controlling factors     

Carolina Bernal  Frédéric Christophoul  José Darrozes  Jean-Claude Soula  Patrice Baby  José Burgos 《International Journal of Earth Sciences》2011,100(7):1759-1782

The geomorphological study by means of remote sensing imagery of the Rio Pastaza Megafan (Ecuador and northern Peru) reveals the traces of numerous avulsions. One hundred and eight avulsion sites have been defined. The location of these sites, the available radiocarbon ages as well as historical maps of the seventeenth century, enable us to propose an evolution history of the migration and avulsions of the Rio Pastaza since the Last Glacial Maximum. The first avulsions of the Río Pastaza occurred after the LGM in a zone close to and roughly parallel to the sudandean front, where the developed avulsion gave a distributive pattern to the ancient stream of the Río Pastaza in an area located between the modern Río Morona and Pastaza, where they caused the Rio Pastaza to develop a fan-like distributary pattern. This is interpreted as a response to thrust-related forelimb tilt, progressively shifting eastward the Rio Pastaza and the apex of the megafan. This sequence of events ended with the Great Diversion of the Rio Pastaza towards the modern Rios Corrientes and Tigre. Avulsions occurred in the Tigre-Corrientes Area between 9200 and 8,500 years Cal BP. Afterwards, the Río Pastaza was diverted to its present-day north–south course. This last significant avulsion occurred before AD 1691. In the area located between the modern Río Morona and Pastaza, avulsion frequency—probably overestimated—ranges between 100 and 200 years. In the Ríos Tigre and Corrientes area, avulsion frequency—probably underestimated—ranges from 300 to 400 years. Regional tectonics is likely to have triggered most of the avulsions in the Morona Pastaza area but its influence is restricted to this area. The factors controlling the avulsions in the Tigre-Corrientes area are less clear because the frequently described “hydrologic”-driven avulsion as observed in areas characterized by contrasted hydrologic cycles are inconsistent with the characteristics of the hydrologic cycles of the Rio Pastaza.  相似文献