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Journal articles on the topic "Wedge Island"
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Mackay, J. Ross. "The frequency of ice-wedge cracking (1967–1987) at Garry Island, western Arctic coast, Canada." Canadian Journal of Earth Sciences 29, no. 2 (February 1, 1992): 236–48. http://dx.doi.org/10.1139/e92-022.
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The frequency of ice-wedge cracking has been studied at Garry Island, Northwest Territories, for the 1967–1987 period. Sites have included low-centre polygons, intermediate-centre polygons, and polygons that do not fit any classification system. Analyses of crack frequency have included trough characteristics, polygon characteristics, and ice-wedge types. The results show that crack frequencies are highly variable within one site and also between two adjacent sites. The correlation between crack frequency and a low air temperature is poor. Crack frequencies for a site with 59 wedges ranged from 8 to 42% between 1967 and 1979 and for a nearby site with 32 wedges from 22 to 75% between 1967 and 1987. In view of the wide range in crack frequencies at a given site, the use of mean ice-wedge growth rates for estimating ages of ice wedges and their casts in environmental reconstruction may be hazardous. The data show that the common twofold classification into active and inactive wedges is difficult to apply because crack frequencies are gradational and dependent on such factors as the number of ice wedges being monitored, the size of the area, the types of ice wedges, and the length of the observation period. A system for classifying crack frequency is proposed.
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Vasil’Chuk, Yu K., and A. C. Vasil’Chuk. "Oxygen isotope composition of the ice wedges of Ayon Island and Late Pleistocene and Holocene palaeotemperature reconstruction of the Northern Chukotka." Moscow University Bulletin. Series 4. Geology, no. 6 (December 28, 2017): 92–104. http://dx.doi.org/10.33623/0579-9406-2017-6-92-104.
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Syngenetic ice wedges have been investigated in the Ayon Island. Their isotopic composition, geochemical characteristics of both ice wedges and enclosing sediment have been obtained; four ice-wedges stages have been distinguished. Paleo temperature reconstructions for Ayon Island and adjacent territories of northern Chukotka have been yielded at the basis of these results. It is observed almost identical trends in the distribution of ice-wedge isotopic characteristics in the island and in the lower reaches of the Kolyma River, as well as differences in the magnitude of isotopic oscillations during the transition from Late Pleistocene to the Holocene as compared to ice-wedges of the Lower Kolyma region.
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Savoskul, Oksana S. "Ion Content of polygonal wedge ice on Bolshoi Lyakhov: a source of palaeoenvironmental information." Annals of Glaciology 21 (1995): 394–98. http://dx.doi.org/10.1017/s0260305500016128.
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Bolshoi Lyakhov is one of the group of the New Siberian Islands in the Laptev Sea. The permafrost of the island is of an extremely low temperature regime, polygonal wedge ice being the most specific feature. The geomorphological level considered is a so-called edoma, presumably of late-Quaternary origin: polygonal ice wedges are more than 10 m wide and up to 25 m deep on this level, and about 1 m × 1.5 m on the peat bogs of Holocene age. Sixty-six samples of underground ice were taken on both surfaces. The macro-ion content was analyzed, i.e. Ca, Mg, Na, K, HCO3, Cl, SO4. A significant difference in ion content was found between the older and the younger ice. The late-Quaternary wedge ice is characterized by the predominance of Ca and HCO3, while the Holocene ice contains considerably higher proportions of Na and Cl. This may be attributed to different environmental conditions during wedge-ice growth: more continental in the late Quaternary and more maritime in the Holocene.
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Savoskul, Oksana S. "Ion Content of polygonal wedge ice on Bolshoi Lyakhov: a source of palaeoenvironmental information." Annals of Glaciology 21 (1995): 394–98. http://dx.doi.org/10.3189/s0260305500016128.
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Bolshoi Lyakhov is one of the group of the New Siberian Islands in the Laptev Sea. The permafrost of the island is of an extremely low temperature regime, polygonal wedge ice being the most specific feature. The geomorphological level considered is a so-called edoma, presumably of late-Quaternary origin: polygonal ice wedges are more than 10 m wide and up to 25 m deep on this level, and about 1 m × 1.5 m on the peat bogs of Holocene age. Sixty-six samples of underground ice were taken on both surfaces. The macro-ion content was analyzed, i.e. Ca, Mg, Na, K, HCO3, Cl, SO4. A significant difference in ion content was found between the older and the younger ice. The late-Quaternary wedge ice is characterized by the predominance of Ca and HCO3, while the Holocene ice contains considerably higher proportions of Na and Cl. This may be attributed to different environmental conditions during wedge-ice growth: more continental in the late Quaternary and more maritime in the Holocene.
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Lewkowicz, Antoni G. "Ice-wedge rejuvenation, fosheim peninsula, ellesmere Island, Canada." Permafrost and Periglacial Processes 5, no. 4 (October 1994): 251–68. http://dx.doi.org/10.1002/ppp.3430050405.
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Bird, Jeremy P., Sialesi Risalto, Elenoa Seniloli, and Tuverea Tuamoto. "A pre-eradication survey of Wedge-tailed Shearwater Puffinus pacificus on Monuriki, Mamanuca Group, Fiji." South Pacific Journal of Natural and Applied Sciences 31, no. 1 (2013): 45. http://dx.doi.org/10.1071/sp13004.
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A brief visit to Monuriki, an island in Fiji’s Mamanuca group was completed in March-April 2011 to gather baseline data on the island’s population of Wedge-tailed Shearwaters Puffinus pacificus prior to the eradication of alien invasive Polynesian Rat Rattus exulans and feral goats Capra hircus from the island in December 2011. We estimated an island-wide population of 2,000-5,500 pairs of Wedge-tailed Shearwaters, the largest population recorded in Fiji. Productivity was estimated to be 40%. It is anticipated these baseline figures will be used to assess the impacts that the removal of invasive mammals has on the population.
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Fortier, Daniel, and Michel Allard. "Late Holocene syngenetic ice-wedge polygons development, Bylot Island, Canadian Arctic Archipelago." Canadian Journal of Earth Sciences 41, no. 8 (August 1, 2004): 997–1012. http://dx.doi.org/10.1139/e04-031.
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The initial configuration of the syngenetic ice-wedge polygons that developed in the outwash plain of glacier C-79 after 6000 BP was modified by the accumulation of wind-blown and organic sediments that began after 3670 ± 110 BP. The late Holocene sedimentation led to an increase in the thermal contraction coefficient of the soil and the formation of third- and fourth-order contraction cracks, partially explaining the current configuration of the polygonal network. The upturning of the sedimentary strata bordering the ice wedges was associated with the summer thermal expansion and resulting internal creep of the soil. The mean annual soil displacement coefficient was in the order of 2.52.7 × 105 /°C at the thousand-year scale. The late Holocene sedimentary strata under the centre of the polygons were undisturbed, which will make it possible to use this sedimentary record in further studies to attempt paleoenvironmental reconstructions from cores.
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Opel, Thomas, Sebastian Wetterich, Hanno Meyer, Alexander Y. Dereviagin, Margret C. Fuchs, and Lutz Schirrmeister. "Ground-ice stable isotopes and cryostratigraphy reflect late Quaternary palaeoclimate in the Northeast Siberian Arctic (Oyogos Yar coast, Dmitry Laptev Strait)." Climate of the Past 13, no. 6 (June 6, 2017): 587–611. http://dx.doi.org/10.5194/cp-13-587-2017.
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Abstract. To reconstruct palaeoclimate and palaeoenvironmental conditions in the northeast Siberian Arctic, we studied late Quaternary permafrost at the Oyogos Yar coast (Dmitry Laptev Strait). New infrared-stimulated luminescence ages for distinctive floodplain deposits of the Kuchchugui Suite (112.5 ± 9.6 kyr) and thermokarst-lake deposits of the Krest Yuryakh Suite (102.4 ± 9.7 kyr), respectively, provide new substantial geochronological data and shed light on the landscape history of the Dmitry Laptev Strait region during Marine Isotope Stage (MIS) 5. Ground-ice stable-isotope data are presented together with cryolithological information for eight cryostratigraphic units and are complemented by data from nearby Bol'shoy Lyakhovsky Island. Our combined record of ice-wedge stable isotopes as a proxy for past winter climate conditions covers about 200 000 years and is supplemented by stable isotopes of pore and segregated ice which reflect annual climate conditions overprinted by freezing processes. Our ice-wedge stable-isotope data indicate substantial variations in northeast Siberian Arctic winter climate conditions during the late Quaternary, in particular between glacial and interglacial times but also over the last millennia to centuries. Stable isotope values of ice complex ice wedges indicate cold to very cold winter temperatures about 200 kyr ago (MIS7), very cold winter conditions about 100 kyr ago (MIS5), very cold to moderate winter conditions between about 60 and 30 kyr ago, and extremely cold winter temperatures during the Last Glacial Maximum (MIS2). Much warmer winter conditions are reflected by extensive thermokarst development during MIS5c and by Holocene ice-wedge stable isotopes. Modern ice-wedge stable isotopes are most enriched and testify to the recent winter warming in the Arctic. Hence, ice-wedge-based reconstructions of changes in winter climate conditions add substantial information to those derived from paleoecological proxies stored in permafrost and allow a distinction between seasonal trends of past climate dynamics. Future progress in ice-wedge dating and an improved temporal resolution of ice-wedge-derived climate information may help to fully explore the palaeoclimatic potential of ice wedges.
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Wetterich, Sebastian, Natalia Rudaya, Vladislav Kuznetsov, Fedor Maksimov, Thomas Opel, Hanno Meyer, Frank Günther, et al. "Ice Complex formation on Bol'shoy Lyakhovsky Island (New Siberian Archipelago, East Siberian Arctic) since about 200 ka." Quaternary Research 92, no. 2 (April 17, 2019): 530–48. http://dx.doi.org/10.1017/qua.2019.6.
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AbstractLate Quaternary landscapes of unglaciated Beringia were largely shaped by ice-wedge polygon tundra. Ice Complex (IC) strata preserve such ancient polygon formations. Here we report on the Yukagir IC from Bol'shoy Lyakhovsky Island in northeastern Siberia and suggest that new radioisotope disequilibria (230Th/U) dates of the Yukagir IC peat confirm its formation during the Marine Oxygen Isotope Stage (MIS) 7a–c interglacial period. The preservation of the ice-rich Yukagir IC proves its resilience to last interglacial and late glacial–Holocene warming. This study compares the Yukagir IC to IC strata of MIS 5, MIS 3, and MIS 2 ages exposed on Bol'shoy Lyakhovsky Island. Besides high intrasedimental ice content and syngenetic ice wedges intersecting silts, sandy silts, the Yukagir IC is characterized by high organic matter (OM) accumulation and low OM decomposition of a distinctive Drepanocladus moss-peat. The Yukagir IC pollen data reveal grass-shrub-moss tundra indicating rather wet summer conditions similar to modern ones. The stable isotope composition of Yukagir IC wedge ice is similar to those of the MIS 5 and MIS 3 ICs pointing to similar atmospheric moisture generation and transport patterns in winter. IC data from glacial and interglacial periods provide insights into permafrost and climate dynamics since about 200 ka.
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Nitzbon, Jan, Moritz Langer, Sebastian Westermann, Léo Martin, Kjetil Schanke Aas, and Julia Boike. "Pathways of ice-wedge degradation in polygonal tundra under different hydrological conditions." Cryosphere 13, no. 4 (April 4, 2019): 1089–123. http://dx.doi.org/10.5194/tc-13-1089-2019.
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Abstract. Ice-wedge polygons are common features of lowland tundra in the continuous permafrost zone and prone to rapid degradation through melting of ground ice. There are many interrelated processes involved in ice-wedge thermokarst and it is a major challenge to quantify their influence on the stability of the permafrost underlying the landscape. In this study we used a numerical modelling approach to investigate the degradation of ice wedges with a focus on the influence of hydrological conditions. Our study area was Samoylov Island in the Lena River delta of northern Siberia, for which we had in situ measurements to evaluate the model. The tailored version of the CryoGrid 3 land surface model was capable of simulating the changing microtopography of polygonal tundra and also regarded lateral fluxes of heat, water, and snow. We demonstrated that the approach is capable of simulating ice-wedge degradation and the associated transition from a low-centred to a high-centred polygonal microtopography. The model simulations showed ice-wedge degradation under recent climatic conditions of the study area, irrespective of hydrological conditions. However, we found that wetter conditions lead to an earlier onset of degradation and cause more rapid ground subsidence. We set our findings in correspondence to observed types of ice-wedge polygons in the study area and hypothesized on remaining discrepancies between modelled and observed ice-wedge thermokarst activity. Our quantitative approach provides a valuable complement to previous, more qualitative and conceptual, descriptions of the possible pathways of ice-wedge polygon evolution. We concluded that our study is a blueprint for investigating thermokarst landforms and marks a step forward in understanding the complex interrelationships between various processes shaping ice-rich permafrost landscapes.
Dissertations / Theses on the topic "Wedge Island"
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Bancroft, Wesley J. "Environmental response to burrowing seabird colonies : a study in ecosystem engineering." University of Western Australia. School of Animal Biology, 2004. http://theses.library.uwa.edu.au/adt-WU2005.0064.
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[Truncated abstract] Ecosystem engineers are organisms that physically modify habitat in a manner that modulate resource flows and species within ecosystems. Ecosystem engineering is distinct from classical interactions (competition, predation, parasitism and mutualism) in that it does not involve direct trophic exchange between organisms. The term ‘ecosystem engineer’ is a recently adopted one, and we are just beginning to investigate the occurrence and impact of engineers in ecosystems. My thesis explores the ecosystem engineering actions of Wedge-tailed Shearwaters, Puffinus pacificus, in a Mediterranean island, heathland ecosystem. I have approached this by (1) describing and quantifying the physical impact of these engineers, and (2) describing and quantifying the effects that these actions have on three major ecosystem components: the soil, the vascular plants, and the vertebrate fauna. Wedge-tailed Shearwaters are procellariid seabirds that excavate nesting burrows on offshore islands. The birds are colonial nesters, and on Rottnest Island, 17 km off the mainland coast of south-western Western Australia, their colonies have expanded considerably in recent decades. The expansion fits the trend observed in other tropicalorigin seabirds that breed in south-western Australia. In the last ten years, two new colonies have appeared (in a total of six) and the number of burrows on the island has almost doubled, to 11 745 ± 1320SE. In the same period the area occupied by the birds has increased by almost half ...
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Malone, Shawn Joseph. "Tectonic evolution of northern Ellesmere Island: insights from the Pearya Terrane, Ellesmerian Clastic Wedge And Sverdrup Basin." Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/3496.
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The tectonic evolution of northern Ellesmere Island is dominated by the accretion of the Pearya Terrane and the progressive reworking of materials from the Pearya Terrane and the northern Caledonides. Geochronology from a suite of seven Succession I orthogneiss samples defines a range of earliest Neoproterozoic ages from 962 ± 6 Ma to 974 ± 8 Ma. Geochemistry of both zircon and whole rock samples reveal a complex magmatic history tapping multiple sources. The rocks include both I and S type granitoids, with silica contents ranging from 62% to 73%. Trace element geochemistry reveals LILE enrichment decoupled from low to depleted HFSE values, suggestive of an origin above a subduction zone. Isotope geochemistry supports input from juvenile and evolved materials, with εNd(i) values between -1 and -4.6, and a similar range for εHf from zircon. The northern elements of the Caledonian Orogen preserve a record of magmatism in the c. 985 Ma to 920 Ma range. These ages are also observed in orthogneiss units of the south central Brooks Range and Farewell terrane, Alaska. The Pearya Terrane orthogneiss units and those currently dispersed in Alaska are interpreted to have originated near or on the eastern margin of Greenland and record post-Rodinia assembly subduction outboard of the supercontinent.
Succession II (Trettin, 1987) of the Pearya Terrane represents variably metamorphosed metasedimentary rocks of Proterozoic to early Paleozoic age. These units are structurally juxtaposed with Succession I orthogneiss and Paleozoic sedimentary units of the Pearya Terrane. Detrital zircon age spectra from seven samples of Neoproterozoic meta-sedimentary rocks reveal three groups defined by observed dominant age peaks and youngest observed age populations. Group I includes three quartzite samples and contains numerous c. 1100 Ma to 1800 Ma peaks, with the youngest population at c. 1050 Ma. Two samples of immature meta-sandstone form Group II, defined by a dominant c. 970 Ma age peak. Two samples from the diamictite unit below the Deutchers Glacier thrusts form Group III, with a similar pattern of c. 1000 Ma to 1800 Ma age peaks to Group I; however, this group includes a small population of c. 600 Ma to 700 Ma grains as well. The ubiquitous Mesoproterozoic ages reflect a Grenvillian-Sveconorwegian provenance. These data are consistent with detrital zircon datasets from other North Atlantic-Arctic Caledonide terranes, reinforcing stratigraphic links between the Pearya Terrane and the northern Caledonides. The utility of the Pearya Terrane dataset is multiplied by probable links to Circum-Arctic and Cordilleran terranes, many of which contain similar populations of Mesoproterozic-aged detrital zircon.
U/Pb ages and Hf isotopic data from detrital zircon suites sampled from Ordovician to Carboniferous sedimentary rock of the Pearya Terrane and northern Ellesmere Island record define the background for terranes translating along the northeastern Laurentian margin in the Paleozoic. Ordovician to Silurian clastic sediments deposited on the Pearya Terrane record pre terrane accretion provenance dominated by recycling of the metaigneous and metasedimentary Proterozoic basement as well as an Ordovician arc source. The provenance of Late Devonian sediments deposited during the Ellesmerian Orogen is dominated by similar recycled materials, with new sources derived from Paleoproterozoic domains of the Canadian-Greenland shield and documented late Devonian granitoids emplaced the Canadian Arctic Islands and Arctic Alaska. The basal Sverdrup Basin records increasing proportions of Paleoprtoerozoic and Archean aged grains relative to Mesoproterozoic ages, suggestive of increased contributions from the Laurentian craton and no little detritus exotic to Laurentia. Detrital zircon age spectra from Devonian to Carboniferous sediments in the northern Cordilleran clastic wedge and western Canadian Arctic Islands contain abundant exotic zircon likely derived from the Caledonian and Timanian Orogens. This variance of sediment provenance indicates that the eastern Canadian Arctic Island were isolated from non-Laurentian or Caledonian detritus, and that sources of the exotic Timanian zircon reconstruct farther west along the margin.
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Tollan, Peter Michael Edward. "A tale of two arcs : petrogenesis of ultramafic xenoliths sampling the upper mantle wedge beneath the West Bismarck island arc." Thesis, Durham University, 2014. http://etheses.dur.ac.uk/10758/.
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Peridotite xenoliths transported to the surface in basaltic magma from the upper mantle wedge beneath the West Bismarck island arc, Papua New Guinea, present a rare opportunity to assess the nature of the mantle wedge in an active intra-oceanic island arc. This thesis reports comprehensive new geochemical and isotopic data for harzburgites, pyroxenites and dunites, from the island of Ritter, in order to understand how partial melting and hydrous metasomatism generate chemically, isotopically and physically distinct mantle. The highly depleted major and moderately incompatible trace element composition of residual phases and the radiogenic strontium isotope composition of texturally well-equilibrated harzburgites are best explained by hydrous partial melting and metasomatism associated with a previous period of subduction. Harzburgites that record textural evidence for melt-rock reaction, meanwhile, have elevated equilibration temperatures, oxidised spinel compositions, elevated olivine water contents and strontium isotope compositions identical to regionally erupted basalts. These features reflect interaction between ambient mantle and primary hydrous, oxidised basaltic melts in the upper mantle wedge. Modelling of trace element diffusion profiles in olivine constrains this event to approximately one year before exhumation. The low water contents of both coarse-grained olivine and orthopyroxene are consistent with equilibrium in chemically depleted upper mantle. The absence of hydrated silicon vacancies in olivine despite overall increases in water content during melt-rock reaction indicates that the mantle wedge may not change significantly in mechanical strength during hydrous melting and metasomatism. Chemical and radiogenic signatures of subduction are thus more likely to survive convective homogenisation. The whole-rock budget of highly siderophile elements (HSE) is contained within heterogeneously distributed trace sulphides and inferred alloy phases, and is controlled by both partial melting and metasomatism. An absence of any correlation of Sr isotopes with either HSE or Os isotopes indicates these elements may be immobile in slab-derived fluids. Elevated concentrations of Pt and Pd in pyroxenite are mirrored by depletions in dunite, demonstrating that melt-rock reaction is instead responsible for enrichments in these elements in arc mantle. A correlation between whole-rock 187Os/188Os and phosphorous in olivine offers clues to ancient processes unrelated to active subduction, not recorded by any other chemical or isotopic system.
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Calabrese, Licia. "Foraging ecology and breeding biology of Wedge-tailed shearwater (Puffinus pacificus) and Tropical shearwater (Puffinus bailloni) on Aride Island Nature Reserve, Seychelles : tools for conservation." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066508/document.
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Cette étude analyse la quasi-totalité du cycle de vie de deux espèces de puffins sympatriques, le puffin tropical (Puffinus bailloni, PT) et le puffin du Pacific (P. pacificus, PP) nichant sur Aride Island (Seychelles). L’objectif est de comprendre les interactions existantes entre ces espèces, ainsi que l’influence de l’environnement, au sein de la colonie et dans le milieu marin. Le nombre de couples ont était estime à 15,000 pour le PP et 30,000 pour le PT (où la population est probablement en déclin). Ils sélectionnent davantage des zones escarpées avec des végétations basses. Les PP montrent également une préférence pour les zones rocheuses avec un sol profond. Les PT nichent pendant toute l’année mais de manière plus intensive en fin de saison de reproduction des PP et le taux d'échec de la reproduction est maximal durant la période où les deux espèces nichent en même temps. Dans le milieu marin, il-y-a une ségrégation spatiale entre les deux espèces, exploitant des zones d’alimentation bien distinctes hors saison de reproduction et se distinguant également dans leur comportement alimentaire (profondeur de plonge). Dans la colonie les deux espèces sont en concurrence sur le site de reproduction mais les PP semblent être de meilleurs compétiteurs. Nous proposons la mise en place de mesures de conservation pour les deux espèces, mais favorisant spécialement les PTThe procellariiformes are one of the most endangered orders in the world. In addition, information on population estimates, trends, movements at sea and population dynamic is lacking for many species. We analysed almost the full life cycle of two sympatric species: the tropical (Puffinus bailloni, TS) and the wedge-tailed shearwater (P. pacificus, WS) breeding at Aride Island (Seychelles), in order to understand the interactions between them and the environment both at sea and in the colony. We assessed habitat selection, abundance, distribution and breeding success of the two species at the colony and the habitat selection and distribution at sea. The population was 15,000 and 30,000 pairs for WS and TS respectively; the TS is possibly in decline. Both species selected steep and lowly vegetated areas; the WS also selected boulder-like zones. The TS nests year-round but it has a peak of breeding at the end of the WS breeding season and its failure rate is higher when the two species co-exist. We found spatial, rather than ecological, segregation between the two species at sea in both foraging behaviour (diving depth) and inter-breeding areas. On land they are likely to compete for breeding sites with the WS often over competing the TS. We then suggest future conservation plans focused on both species but especially on the TS
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Bellamy, Stephen, and steve bellamy@flinders edu au. "RESOURCE PARTITIONING BETWEEN TWO SYMPATRIC AUSTRALIAN SKINKS, EGERNIA MULTISCUTATA AND EGERNIA WHITII STEPHEN BELLAMY Thesis submitted in total fulfilment of the requirements of the degree of Doctor of Philosophy AUGUST 2006 SCHOOL OF BIOLOGICAL SCIENCES FLINDERS UNIVERSITY, ADELAIDE, SOUTH AUSTRALIA ________________________________________." Flinders University. Biological Sciences, 2007. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20070124.145924.
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When species compete for resources, in a stable homogeneous environment, there are two possible outcomes. The first is that one species will out-compete the other and exclude it from the environment. This is known as the competitive exclusion principle. The second is that both species will manage to coexist. Coexistence can only occur if the species niches are differentiated such that interspecific competition is minimised, or eliminated. This outcome is known as resource partitioning.
Two closely related Australian skink species of the Egernia genus, Egernia multiscutata and Egernia whitii, are abundant and sympatric on Wedge Island in South Australias Spencer Gulf. The species are morphologically very similar and appear to have very similar life histories and habitat requirements. Ostensibly, they would compete for limiting resources in this environment.
This thesis is the first investigation into resource partitioning in this previously unstudied model organism. I report the results of multi-faceted investigations into the coexistence of the skinks, E. multiscutata and E. whitii on Wedge Island and the evidence for, and mechanisms of, any facultative resource partitioning between them.
Study methods involved a transect survey of most of Wedge Island to determine the species distributions and any evidence for resource partitioning; a morphological comparison to investigate any potential competitive advantages of either species; a habitat choice experiment to establish retreat-site preferences in the absence of interspecific interference; and, a series of staged dyadic encounter experiments to investigate interspecific competitive interactions.
Resource partitioning was evidenced by differential distributions of the species among substrates containing the elements required for permanent refuge shelters. This partitioning was not mediated by avoidance of particular substrates but by the presence of the opponent species, combined with attraction to suitable substrates. Asymmetries in some morphological characters were found to confer a potential competitive advantage to E. multiscutata in agonistic encounters with E. whitii. Both species were found to have the same refuge site preferences when interference competition was experimentally removed. This result was not concordant with observed resource partitioning in the field and suggests that the habitat choices of both species are modified by the presence of the opponent species. Analyses of staged dyadic encounter experiments showed that E. multiscutata was more likely to gain greater access to a contested habitat resource and more likely to exclude E. whitii from the resource than vice-versa. Nevertheless, the outcome of competitive interactions was not completely deterministic and there was some tolerance of co-habitation. E. multiscutatas competitive advantage was attributable largely to its greater mass and head dimensions relative to snout to vent length. However, differential behavioural responses to the threat of larger opponent size also played an important part in resource partitioning between the species.
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Martin, Michael Robert. "Ecotourism potential in the Spencer Gulf : case studies of Wedge and Reevesby Islands /." Title page, contents and abstract only, 1996. http://web4.library.adelaide.edu.au/theses/09ENV/09envm3818.pdf.
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Nicholson, Lisa. "Breeding Strategies and Community Structure in an Assemblage of Tropical Seabirds on the Lowendal Islands, Western Australia." Murdoch University, 2002. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20040929.134652.
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Information about tropical seabird communities is less abundant in the literature than for those that occur at higher latitudes. In research papers examining seabird breeding communities in tropical environments, it has been found that food availability was temporally and spatially variable in comparison to higher latitudes. This environmental variability would be expected to influence the life-history traits of tropical seabird species, and in turn, the structure of the communities in which they occur. To examine the impact of environmental variability upon the life-history traits and community structure of tropical seabirds, a comparative study of the breeding strategies of three tropical tern species and an outlier, shearwater species was carried out, at the Lowendal Islands, Western Australia (20o3952S; 115o3444E) between 1996 and 2000.
Bridled Terns Sterna anaethetus and Wedge-tailed Shearwaters Puffinus pacificus shared the life-history traits of migration or dispersal from the breeding colony and east-Indian Ocean metapopulation when not breeding, a summer breeding schedule, nest-site fidelity, concealed nest-sites, clutch size of one, offshore and pelagic foraging regime, and protracted post-natal growth. Crested Terns Sterna bergii and Lesser Crested Terns Stern bengalenis bred within the same colony and shared the life-history traits of presence at the breeding colony when not breeding, an autumn breeding schedule, change in colony site each season, open dense nest-sites, brood size of one. inshore foraging regime (as well as offshore for Crested Terns) and rapid post-natal growth.
It was found that each species experienced variation in nest-site occupancy and/or colony size, as well as variation in timing of breeding and breeding success between years. The effects upon each species seemed to operate independently, as concurrently breeding species did not appear affected by the same events, with the exception of cyclones. Late and/or poor breeding success in a species often coincided with oceanographic changes in the north-west region, such as fluctuations in the strength of flow and temperature of the Leewin Current. The Leewin Current is a warm water, low salinity current flowing southwards along most of the Western Australian coastline and has a stronger, warmer flow during El Nino Southern Oscillation (ENSO) events. Cyclone activity is also influenced by ENSO induced changes in the regions water temperature. Changes in the Leewin Current affected the timing of breeding for Wedge-tailed Shearwaters, and feeding conditions for all study species, presumably as a result of changes in prey availability, while cyclone events delayed breeding for Crested Terns and Lesser Shearwaters in the years studied. Cyclone events were the most obvious cause of re-laying in the case of Crested Terns and Lesser Crested Terns, and breeding failure in the case of Bridled Terns and Wedge-tailed Shearwaters. Breeding failure was common among later breeders in the Crested Tern colonies. Breeding success was relatively high for lesser Crested Terns in all years studied, as they hatched and fledged their chicks within the Crested Tern colony among the first wave of breeders.
There was some overlap in the diets and foraging grounds of the four study species. Crested terns and Lesser Crested Terns had the most similar diet, however, Crested Terns appeared to be the most opportunistic foragers, with the highest diversity of dietary prey, while Lesser Crested Terns diet consisted of a high proportion of atherinids. Bridled Terns has the next highest prey diversity, while half the diet of Wedge-tailed Shearwaters in this region, similar to conspecifics elsewhere, consisted of squid. Wedge-tailed Shearwaters were observed to be offshore and pelagic foragers. Their distribution in the waters surrounding the Lowendal Islands ranged to the full extent of observation transects(63 Km), and most likely beyond, excluding inshore waters (i.e. within 5 km of islands). They were not present in the vicinity of the Lowendal Islands when they were not breeding. Bridled Terns were observed to be offshore foragers, also ranging to the full extent of transects, and most likely beyond, occasionally including inshore waters. They were rarely observed when not breeding, with the exception of a small number of fledglings at the end of the breeding season. Crested Terns were observed to combine inshore and offshore foraging grounds, only ranging to the full extent of transects during their breeding season. Lesser Crested Terns were observed foraging inshore only.
Chick provisioning, in terms of meal size and frequency, varied between years and within seasons for all species. It was demonstrated that there were differences in mean corrected meal sizes between years for Wedge-tailed Shearwaters, and the same was inferred from chick growth curves for Bridled Terns. Wedge-tailed Shearwaters provisioned their chicks with larger meal sizes and a higher occurrence of double feeds in 1996/97 than in other years studied. The amount of time spent feeding chicks in the burrow by Wedge-tailed Shearwaters adults became shorter as the breeding season progressed. It was demonstrated that all three tern species increased the meal size delivered to chicks as they grew. Wedge-tailed Shearwaters did not increase meal size as the season progressed, however they did increase feeding frequency. The feeding frequency of Crested Terns was highest in 1999, nearly doubling that observed in 1997 and 1998. In 1998 Lesser Crested Terns fed their chicks up to six times more frequently than Crested Terns.
Chick growth varied for Wedge-tailed Shearwaters and Bridled Terns between seasons. Bridled Tern chicks grew more rapidly in 1997/98, were heavier and reached higher asymptotes for all linear parameters, the exception of wing length, than in 2000. On the other hand, Wedge-tailed Shearwater chicks grew more rapidly in 1999/2000 than in 1997/98, however, they attained similar asymototes for all parameters in both years. In the absence of repeat measures of same individuals, Crested Tern and Lesser Crested tern growth was examined using age categorization based on wing and tail feather development. Both species appeared to attain similar sizes at similar rates in each year.
Wedge-tailed Shearwaters accumulated weight up to 30% in excess of mean adult weight in all seasons. This is a common trait exhibited in procellarigorms, and some weight loss occurs prior to fledging. It is suggested, based upon evidence from other studies in which weight loss prior to fledging was found to be water loss, that lipid accumulation acts as an insurance for the period after fledging when young are leaning to forage for themselves.
The information gathered for this project found no direct evidence of competition among the species comprising the seabird community if Lowendal Islands. Niche overlap occurred amongst all species, particularly in the case of lesser Crested Terns and Crested Terns, which shared breeding phenology, breeding colonies, foraging grounds and dietary overlap. Niche overlap also occurred between Wedge-tailed Shearwaters and Bridled Terns, which shared breeding phenology and foraging grounds.
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Bellamy, Robyn Lyle, and robyn bellamy@flinders edu au. "LIFE HISTORY AND CHEMOSENSORY COMMUNICATION IN THE SOCIAL AUSTRALIAN LIZARD, EGERNIA WHITII." Flinders University. Biological Sciences, 2007. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20070514.163902.
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ABSTRACT
Social relationships, habitat utilisation and life history characteristics provide a framework which enables the survival of populations in fluctuating ecological conditions. An understanding of behavioural ecology is critical to the implementation of Natural Resource Management strategies if they are to succeed in their conservation efforts during the emergence of climate change. Egernia whitii from Wedge Island in the Spencer Gulf of South Australia were used as a model system to investigate the interaction of life history traits, scat piling behaviour and chemosensory communication in social lizards.
Juveniles typically took ¡Ý 3 years to reach sexual maturity and the results of skeletochronological studies suggested longevity of ¡Ý 13 years. Combined with a mean litter size of 2.2, a pregnancy rate estimated at 75% of eligible females during short-term studies, and highly stable groups, this information suggests several life history features.
Prolonged juvenile development and adult longevity may be prerequisite to the development of parental care. Parental care may, in turn, be the determining factor that facilitates the formation of small family groups. In E. whitii parental care takes the form of foetal and neonatal provisioning and tolerance of juveniles by small family or social groups within established resource areas. Presumably, resident juveniles also benefit from adult territorialism. Research on birds suggests that low adult mortality predisposes cooperative breeding or social grouping in birds, and life history traits and ecological factors appear to act together to facilitate cooperative systems.
E. whitii practice scat piling both individually and in small groups. Social benefits arising from signalling could confer both cooperative and competitive benefits. Permanent territorial markers have the potential to benefit conspecifics, congenerics and other species. The high incidence of a skink species (E. whitii) refuging with a gecko species (N. milii) on Wedge Island provides an example of interspecific cooperation. The diurnal refuge of the nocturnal gecko is a useful transient shelter for the diurnal skink. Scat piling may release a species ¡®signature¡¯ for each group that allows mutual recognition.
Scat piling also facilitates intraspecific scent marking by individual members, which has the potential to indicate relatedness, or social or sexual status within the group. The discovery of cloacal scent marking activity is new to the Egernia genus. E. Whitii differentiate between
their own scats, and conspecific and congeneric scats. They scent mark at the site of conspecific scats, and males and females differ in their response to scent cues over time. Scat piling has the potential to make information concerning the social environment available to dispersing transient and potential immigrant conspecifics, enabling settlement choices to be made.
This thesis explores some of the behavioural strategies employed by E. whitii to reduce risks to individuals within groups and between groups. Scents eliciting a range of behavioural responses relevant to the formation of adaptive social groupings, reproductive activity, and juvenile protection until maturity and dispersal are likely to be present in this species. Tests confirming chemosensory cues that differentiate sex, kin and age would be an interesting addition to current knowledge. The interaction of delayed maturity, parental care, sociality, chemosensory communication and scat piling highlights the sophistication of this species¡¯ behaviour.
An alternative method for permanently marking lizards was developed. Persistence, reliability and individual discrimination were demonstrated using photographic identification and the method was shown to be reliable for broad-scale application by researchers. Naturally occurring toe loss in the field provided a context against which to examine this alternative identification method and revealed the need to further investigate the consequences of routine toe clipping, as this practice appears to diminish survivorship.
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Weege, Stefanie [Verfasser], and Hugues [Akademischer Betreuer] Lantuit. "Climatic drivers of retrogressive thaw slump activity and resulting sediment and carbon release to the nearshore zone of Herschel Island, Yukon Territory, Canada / Stefanie Weege ; Betreuer: Hugues Lantuit." Potsdam : Universität Potsdam, 2017. http://d-nb.info/1218402490/34.
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Goulart, da Costa Ana Cristina. "Mass-wasting episodes in the geological evolution of the Azores islands : timing, recurrence, mechanisms and consequences." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112001/document.
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Les grands effondrements de flanc sont des phénomènes récurrents dans l'évolution géologique des îles océaniques. Parfois catastrophiques. les épisodes de déstabilisation sont capables de générer d'importants tsunamis, et représentent donc des événements dangereux. Le îles des Açores à l’est de la Dorsale Médio-Atlantique sont situées sur la frontière de plaques diffuse entre l’Eurasie (Eu) et la Nubie (Nu), et donc sous l'influence d’un contrôle structural et d’une activité sismique importante (événements historiques de magnitude jusqu'à environ 7). Avant le projet MEGAHazards (PTDC/CTE-GIX /108149/2008, financé par FCT, Portugal), les effondrements de flanc à grande échelle étaient considérés inexistants aux Açores, principalement à cause de la petite dimension des édifices volcaniques. Ici, nous concluons sans équivoque que de tels événements se sont bien produits dans les Açores. La thèse de doctorat porte sur l'évolution de la ride volcanique escarpée de Pico-Faial, qui se trouve sur une faille normale majeur associée à la limite diffuse Nu/Eu, et particulièrement sur les grands effondrements de flanc qui ont affecté l'île de Pico. A partir de modèles numériques de terrain à haute-résolution, de nouvelles données structurales, stratigraphiques, et de datations K-Ar, nous avons: (1) calibré la stratigraphie volcanique de Pico; (2) reconstruit les phases majeures de croissance et de destruction des îles de Pico durant les derniers 200 kyr; (3) reconstruit l'évolution du slump actif du SE d'île de Pico, au cours des derniers 125 kyr; (4) fourni de nouvelles interprétations concernant l'escarpement qui coupe le flanc S du stratovolcan de Pico; (5) montré l’existence d’effondrements catastrophiques des flancs N et S de l'île de Pico entre ca. 125 et 70 ka, qui ont généré d'importants débris sous-marins; et (6) proposé que l’accommodation de l' extension associé à la limite des plaques Nu/Eu le long de la ride Pico-Faial, a été consolidée dans les derniers ca. 125 ka. De nombreux facteurs favorisant le développement des instabilités de flanc sur les îles volcaniques ont été proposés dans la littérature, mais leur rôle exact et leur contribution mutuelle restent mal compris. Nous présentons ici une solution analytique pour la théorie du Prisme Critique de Coulomb cohésif, appliquée à des instabilités gravitaires, et des simulations analogiques complémentaires pour tester certaines implications structurales du modèle. Nous étudions l'impact de variables comme: la géométrie et les dimensions du prisme, la cohésion, le coefficient de friction interne et le rapport de surpression de fluide (surpression de fluide divisé par la pression lithostatique).Nous concluons que: (1) l’augmentation de la pente des flancs du volcan et du décollement basal conduit à une diminution du rapport de surpression de fluide nécessaire pour produire la rupture; (2) la diminution de l'effet stabilisateur de la cohésion avec la profondeur du décollement basal favorise l'occurrence de déstabilisation gravitaire profonde à grande échelle pour des décollements plus profonds que 2000-2500 m. Pour des décollements basales plus superficiels, les rapports de surpression de fluide nécessaires pour induire la rupture sont relativement supérieurs. Pour les décollements moins profonds, des flancs très inclinés et des matériaux très résistants, la rupture superficielle parallèle à la surface du flanc est favorisée, par rapport à la rupture profonde; (3) Pour des profondeurs supérieures à 2500 m (cas des grands édifices volcaniques), tandis que l'impact de la cohésion diminue, l'effet de la friction interne le long du décollement basal devient relativement plus importante. L’étude des grands effondrements de flanc dans les îles des Açores, et la modélisation des variables qui contrôlent la stabilité des édifices volcaniques demeurent cependant incomplets, et seront approfondis dans un futur procheLarge-scale flank collapses are recurrent in the geological evolution of volcanic ocean islands. Such catastrophic episodes of destabilization can be voluminous and generate large tsunamis, which may cause considerable damage and thus represent extremely hazardous events. The Azores islands east of the Mid-Atlantic Ridge are located on the Eurasia(Eu)/Nubia(Nu) plate boundary, and therefore subject to structural control and seismic activity (historical events of magnitude up to ca. 7). However, prior to MEGAHazards Project (PTDC/CTE-GIX/108149/2008, funded by FCT, Portugal), large-scale flank collapses in the Azores were considered to be lacking, mainly due to the small dimension of the volcanic edifices. Here, we conclude unequivocally on the occurrence of such events in the Azores. The present PhD thesis addresses the evolution of the Pico-Faial steep volcanic ridge, which sits on a major normal fault associated with the Eu/Nu diffuse boundary, focusing especially on the large-scale flank failures in Pico Island. Based on high-resolution sub-aerial and submarine Digital Elevation Models, new structural and stratigraphic data, and high-resolution K-Ar dating on separated volcanic groundmass, we: (1) constrain the volcano stratigraphy of Pico; (2) reconstruct the major phases of growth and destruction in Pico and Faial islands in the last 200 kyr; (3) reconstruct the ca. 125 kyr evolution of the currently active large-scale slump in the SE of Pico Island; (4) provide new structural data/interpretations regarding the scarp that sharply cuts the S flank of Pico Stratovolcano; (5) report on the occurrence of large-scale failures in the N and S flanks of the Pico Island between ca. 125 and 70 ka, which generated large submarine debris deposits; and (6) propose that the role of the Pico-Faial ridge as a structure accommodating part of the extension on the diffuse Nu/Eu boundary has been consolidated in the last ca. 125 kyr. Many factors favouring the development of such large-scale flank instabilities have been proposed in the literature, but their exact role and mutual contribution remain poorly understood. We here present an analytical solution for the cohesive Coulomb Critical Wedge theory applied to gravitational instabilities, and associated analogue simulations to test some structural implications of the model. We investigate the impact of several variables on the stability of volcanic flanks, including: wedge slope and dimensions, cohesion, internal friction along the basal detachment, and fluid overpressure. We conclude that: (1) the steepening of the volcanic flanks and basal detachment lead to a decrease in the fluid overpressure ratio (fluid overpressure divided by lithostatic pressure) necessary to produce failure. (2) The decrease of the stabilizing effect of cohesion with increasing depth of the basal detachment favours the occurrence of deep-seated large-scale gravitational destabilization in basal detachments deeper than ca. 2000-2500 m (in volcanic edifices necessarily higher than 2500 m). For shallower basal detachments, the overpressure ratios required to induce failure are comparatively larger. For shallower basal detachments, steeper flanks and stronger edifice materials, shallow failure parallel to the edifice flank surface is favoured, instead of deep-seated deformation. (3) With increasingly deeper basal detachments (possible in larger volcanic edifices), while the impact of cohesion diminishes, the relative importance of basal internal friction for the stability of the edifice increases. The investigation of the occurrence of large-scale mass-wasting in the Azores islands, and the modelling of the variables controlling the stability of the volcanic edifices are only at their first steps and will be further developed in the future
Books on the topic "Wedge Island"
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Inamullah, Mohammad. Drive a wedge: The strategy behind Iraq War. [Philadelphia, PA]: Xlibris Corp., 2008.
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Baumann, Maria. Katharina heisst jetzt Ayse: Wege deutscher Frauen zum Islam. Regensburg: Scriptorium, 2004.
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Schmid, Hansjörg. Islam im europäischen Haus: Wege zu einer interreligiösen Sozialethik. Freiburg im Breisgau: Herder, 2012.
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Islam, Frauen und Europa: Islamischer Feminismus und Gender Jihad, neue Wege für Musliminnen in Europa? Stuttgart: Verlag W. Kohlhammer, 2013.
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Viele Wege und ein Ziel: Leben und Wirken von Sayyid Abū l-Ḥasan ʻAlī al-Ḥasanī Nadwī (1914-1999). Würzburg: Ergon, 2004.
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Schmid, Michael. Christen und Muslime in der Schule: Möglichkeiten und Wege interreligiöser Begegnungen. Berlin: EB-Verlag, 2010.
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Schmid, Michael. Christen und Muslime in der Schule: Möglichkeiten und Wege interreligiöser Begegnungen. Berlin: EB-Verlag, 2010.
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1960-, Neuser Bernd, ed. Dialog im Wandel: Der christlich-islamische Dialog : Anfange - Krisen - neue Wege. Neukirchen-Vluyn: Neukirchener Verlagshaus, 2005.
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1943-, Schäfer Peter, ed. Wege mystischer Gotteserfahrung: Judentum, Christentum und Islam = Mystical approaches to God : Judaism, Christianity, and Islam. Munchen: Oldenbourg, 2006.
Find full textBook chapters on the topic "Wedge Island"
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Ida, Yoshiaki. "STRUCTURE of the mantle wedge and volcanic activities in the island arcs." In High‐Pressure Research in Mineral Physics: A Volume in Honor of Syun‐iti Akimoto, 473–80. Washington, D. C.: American Geophysical Union, 1987. http://dx.doi.org/10.1029/gm039p0473.
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Kamel, Susan. "Eine ästhetische Präsentation des Islam." In Wege zur Vermittlung von Religionen in Berliner Museen, 117–42. Wiesbaden: VS Verlag für Sozialwissenschaften, 2004. http://dx.doi.org/10.1007/978-3-322-81022-9_7.
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Dziri, Amir. "»So stiftet Frieden!« (49:9) – Islamisch-theologische Wege zu einem ursachengerechten Umgang mit religiös motivierter Gewalt." In Gewalt und Gewaltfreiheit in Judentum, Christentum und Islam, 83–102. Göttingen: Vandenhoeck & Ruprecht, 2018. http://dx.doi.org/10.13109/9783666370823.83.
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Collot, J. Y., H. G. Greene, M. A. Fisher, and E. Geist. "Tectonic Accretion and Deformation of the Accretionary Wedge in the North D'Entrecasteaux Ridge-New Hebrides Island Arc Collision Zone: Evidence from Multichannel Seismic Reflection Profiles and Leg 134 Results." In Proceedings of the Ocean Drilling Program, 134 Scientific Results. Ocean Drilling Program, 1994. http://dx.doi.org/10.2973/odp.proc.sr.134.001.1994.
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Cooney, Gabriel. "Icons of Antiquity: Remaking Megalithic Monuments in Ireland." In The Lives of Prehistoric Monuments in Iron Age, Roman, and Medieval Europe. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780198724605.003.0011.
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Megalithic tombs dating to the Neolithic and Early Bronze Age (4000–2000 cal. BC) are a very distinctive aspect of the Irish landscape (Jones 2007; Scarre 2007). They are an important monumental aspect of this period and since the 1990s our understanding of this period has been complemented by an extensive record of settlement and related activity that has been revealed through development-led archaeology (e.g. Smyth 2011). A focus of antiquarian and archaeological interest since at least the nineteenth century, the basis of modern approaches to megalithic tombs includes the systematic Megalithic Survey of Ireland that was initiated by Ruaidhrí de Valera in the 1950s, under the auspices of the Ordnance Survey of Ireland (Ó Nualláin 1989; Cody 2002 are the latest volumes published) and the excavation of key sites, for example the passage tombs of Newgrange (O’Kelly 1982; O’Kelly et al. 1983) and Knowth (Eogan 1984; 1986; Eogan and Roche 1997; Eogan and Cleary forthcoming) in the Boyne Valley and Carrowmore in Co. Sligo (Burenhult 1980; 1984; 2001). Current work includes the excavation of individual sites, work on the sources used in tomb construction, reviews of particular megalithic tomb types, landscape and regional studies, archaeoastronomy and overviews for a wide readership. The known number of megalithic tombs on the island now approaches 1,600 and the majority of these can be categorized as falling into one of four tomb types whose names encapsulate key architectural features of each tradition, hence the terms portal tombs, court tombs, passage tombs and wedge tombs (Evans 1966, 7–15; Valera and Ó Nualláin 1972, xiii). Unsurprisingly, much of the focus of archaeological research has been on the role of these monuments for the people and societies who constructed them. Issues such as the date of construction of different tomb types (Cooney et al. 2011) and the relationship between them have been central to key debates about the Neolithic, informing such major topics as the date and character of the Mesolithic to Neolithic transition, the changing character of society over the course of the Neolithic, mortuary rites and traditions, and the links between Ireland, Britain, and north-west Europe at this time (Cooney 2000; Bradley 2007; Waddell 2010).
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Westbrook, G. K. "Growth of Accretionary Wedges off Vancouver Island and Oregon." In Proceedings of the Ocean Drilling Program, 146 Part 1 Initial Reports. Ocean Drilling Program, 1994. http://dx.doi.org/10.2973/odp.proc.ir.146-1.011.1994.
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"Anadromous Sturgeons: Habitats, Threats, and Management." In Anadromous Sturgeons: Habitats, Threats, and Management, edited by Daniel Hatin, Jean Munro, François Caron, and Rachel D. Simons. American Fisheries Society, 2007. http://dx.doi.org/10.47886/9781888569919.ch7.
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<em>Abstract</em>.—Space use and habitat selection of early juvenile Atlantic sturgeon <em>Acipenser oxyrinchus</em> have been little studied and remain largely unknown throughout the species’ range. In 2000–2002, survey trawling, ultrasonic telemetry, benthos sampling, and hydrodynamic modeling were used to determine the summer movement patterns, home range size, and habitat use and selection of early juvenile Atlantic sturgeon in the St. Lawrence estuary. Sonic-tagged Atlantic sturgeon, assumed to be age 2 based on their size, used a global area estimated at 76 km2 that included two main core areas. Individual summer home range sizes varied from 1 to 8 km2, but core areas were generally smaller than 1 km2. The mean daily distance traveled ranged from 0.4 to 13.5 km/d and was significantly related to sturgeon size. Fish were located mostly in freshwater relatively close to the salt wedge boundary and far from the shore, intertidal zones, and islands. They mostly used the 6–10-m depth range relatively close to a channel, in areas with low bottom current velocities, and over silt–clay substrates. Salinity and distance from the salt wedge were the two most important variables explaining their habitat selection. Age-0 Atlantic sturgeon used similar depth ranges, bottom salinities, and current velocities, but occupied mainly sandy substrate. Management implications of these results are discussed in relation to the impact of dredging and sediment disposal operations in the St. Lawrence estuary.
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Lucas, Stephen E., and J. Casey Moore. "Cataclastic deformation in accretionary wedges: Deep Sea Drilling Project Leg 66, southern Mexico, and on-land examples from Barbados and Kodiak Islands." In Geological Society of America Memoirs, 89–104. Geological Society of America, 1986. http://dx.doi.org/10.1130/mem166-p89.
Full textConference papers on the topic "Wedge Island"
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da Silva*, Ivo Vieira, Isabel Montoya-Montes, Michel Michaelovitch de Mahiques, Javier Alcántara-Carrió, Rodolfo Jasão Soares Dias, Paola Castellano, Francisco J. Lobo, et al. "Characterization of the sedimentary wedge off São Sebastião Island, São Paulo." In 14th International Congress of the Brazilian Geophysical Society & EXPOGEF, Rio de Janeiro, Brazil, 3-6 August 2015. Brazilian Geophysical Society, 2015. http://dx.doi.org/10.1190/sbgf2015-084.
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Ziemer, Gesa. "Towards a Novel Type of Ice for Model Tests With Vertically Sided Structures." In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-77850.
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Model tests in ice are well-established to assess ice loads acting on ship-shaped structures. Model basins worldwide have elaborated different types of model ice over the past decades and gained confidence in e.g. predicting ship’s resistance which is validated by full scale data. Driven by industrial needs, the model ice was invented and modified with emphasis on the failure observed on ship hulls: Mostly flexural failure with only limited influence of crushing, i.e. against a vertical stem contour. Nowadays, the same model ice is occasionally used for structures exposed to ice action which are far from being ship-shaped, such as vertical sided monopiles or artificial islands. This approach is often questioned as the currently used model ice is usually insufficiently brittle, overstates out-of-plane deformation and flexural failure of the ice sheet, and transfers most of the ice load by a hard top layer rather than creating a wedge-shaped ice edge with a line-like contact approximately at middle height of the ice thickness as observed in full scale indentation tests. Therefore, results from tests with vertical structures in model ice have to be treated cautiously and not all observations are directly scalable. In an attempt to overcome the most severe issues with HSVA’s model ice in tests with vertically sided structures, a new way of initiating the formation of a model ice sheet was tested as a part of the IVOS project. Instead of spraying a top layer, the water in the basin was kept in motion by a wave maker while crystals formed. When the waves were stopped, an ice sheet with larger crystals in the top layer grew. A compliant vertical structure was pushed through this ice sheet and global and local loads were measured. The measurements were compared to tests with the same structure in conventional columnar model ice. Various ice properties were measured throughout the tests. This paper introduces an alternative way to create a model ice sheet for tests with vertically sided structures utilizing a wavemaker, and discusses the findings from first model tests.
Reports on the topic "Wedge Island"
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Kabanov, P. Geological and geochemical data from the Canadian Arctic Islands. Part XV: basal strata of Devonian clastic wedge on Banks Island and correlation with mainland Northwest Territories. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2018. http://dx.doi.org/10.4095/306368.
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Embry, A. F. Chapter 10: Middle-Upper Devonian Clastic Wedge of the Arctic Islands. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1991. http://dx.doi.org/10.4095/100309.
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Bozhko, S. I., A. S. Ksyonz, A. M. Ionov, D. A. Fokin, V. Dubost, F. Debontridder, T. Cren, and D. Roditchev. Growth of layered wedge-shaped islands of Pb on the vicinal Si: new mechanism of twin boundary formation. Edited by Lotfia Elnai and Ramy Mawad. Journal of Modern trends in physics research, December 2014. http://dx.doi.org/10.19138/mtpr/(14)73-80.
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