987 resultados para Sea land contrast
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[EN] Marine turtles undergo dramatic ontogenic changes in body size and behavior, with the loggerhead sea turtle, Caretta caretta, typically switching from an initial oceanic juvenile stage to one in the neritic, where maturation is reached and breeding migrations are subsequently undertaken every 2-3 years [1-3]. Using satellite tracking, we investigated the migratory movements of adult females from one of the world's largest nesting aggregations at Cape Verde, West Africa. In direct contrast with the accepted life-history model for this species [4], results reveal two distinct adult foraging strategies that appear to be linked to body size. The larger turtles (n = 3) foraged in coastal waters, whereas smaller individuals (n = 7) foraged oceanically.
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The proliferation of private land conservation areas (PLCAs) is placing increasing pressure on conservation authorities to effectively regulate their ecological management. Many PLCAs depend on tourism for income, and charismatic large mammal species are considered important for attracting international visitors. Broad-scale socioeconomic factors therefore have the potential to drive fine-scale ecological management, creating a systemic scale mismatch that can reduce long-term sustainability in cases where economic and conservation objectives are not perfectly aligned. We assessed the socioeconomic drivers and outcomes of large predator management on 71 PLCAs in South Africa. Owners of PLCAs that are stocking free-roaming large predators identified revenue generation as influencing most or all of their management decisions, and rated profit generation as a more important objective than did the owners of PLCAs that did not stock large predators. Ecotourism revenue increased with increasing lion (Panthera leo) density, which created a potential economic incentive for stocking lion at high densities. Despite this potential mismatch between economic and ecological objectives, lion densities were sustainable relative to available prey. Regional-scale policy guidelines for free-roaming lion management were ecologically sound. By contrast, policy guidelines underestimated the area required to sustain cheetah (Acinonyx jubatus), which occurred at unsustainable densities relative to available prey. Evidence of predator overstocking included predator diet supplementation and frequent reintroduction of game. We conclude that effective facilitation of conservation on private land requires consideration of the strong and not necessarily beneficial multiscale socioeconomic factors that influence private land management.
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Thesis (Master's)--University of Washington, 2016-06
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Panoramic Sea Happening (After Kantor) is a 7 minute durational film that reimagines part of Tadeusz Kantor's original sea happenings from 1967 in a landscape in which the sea has retreated. The conductor of Kantor’s original performance is replaced with a sound object cast adrift on a beach in Dungeness (UK). The object plays back the sound of the sea into the landscape, which was performed live and then filmed from three distinct angles. The first angle mimics the position of the conductor in Kantor’s original happening, facing outwards into the horizon of the beach and recalls the image in Kantor’s work of a human figure undertaking the absurd task of orchestrating the sound of a gigantic expanse of water. The second angle exposes the machine itself and the large cone that amplifies the sound, reinforcing the isolation of the object. The third angle reveals a decommissioned nuclear power station and sound objects used as a warning system for the power plant. Dungeness is a location where the sea has been retreating from the land, leaving traces of human activity through the disused boat winches, abandoned cabins and the decommissioned nuclear buildings. It is a place in which the footprint of the anthropocene is keenly felt. The sound object is intended to act as an anthropomorphic figure, ghosting the original conductor and offering the sound of the sea back into the landscape through a wide mouthpiece, echoing Kantor’s own load hailer in the original sequence of sea happenings. It speculates on Kantor's theory of the bio-object, which proposed a symbiotic relationship between the human and the nonhuman object in performance, as a possible instrument to access a form of geologic imagination. In this configuration, the human itself is absent, but is evoked through the objects left behind. The sound object, helpless in a red dingy, might be thought of as a co-conspirator with the viewer, enabling a looking back to the past in a landscape of an inevitable future. The work was originally commissioned by the University of Kent in collaboration with the Polish Cultural Institute for the Symposium Kantorbury Kantorbury in Canterbury (UK) to mark the 100 years since Tadeusz Kantor’s birth (15 - 19 September 2015). It should be projected and requires stereo speakers.
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The coastal districts, as an intersection of two perfectly different ecosystems of dry land and sea, is one of the most complicated and the richest natural system on earth. Considering these areas are constantly exposed to aggregation of water pollutants and also consequence resulting from construction and development activities, they are very vulnerable. Therefore, "sensitive Coastal areas" has become a common word in the related subjects to marine environment recently. The said title relates to the areas of the coastal lines which are vulnerable to the natural condition or human actions because of ecological, social, economic, educational and research importance, also they need particular supports. The southern coasts of Caspian Sea, In Iran prominent samples are of these sensitive areas which their environment are exposed to demolition and destruction intensely, due to increasing and uncontrolled development. The first stage of protecting and managing the coastal areas is identifying sensitive Coastal areas and broadening the Coasts. In this survey, we attempted to examine a definite area in the southern coasts of Caspian Sea. In Iran, by profiting from the world experiences and concluded researches in Iran especially the concluded studies by marine environment office and the Environment protection organization on the subject of determination criteria of the sensitive ecological districts. For this purpose (In Gilan Province) Boujagh national park district which is located in the mouth of sefidroud river and also is possessed of the special ecological and environmental features and distinctions. In this survey, first they said district is divided proportionally on the basis of using a grid system in order to identify the sensitive ecological districts and broaden the coast, and then the desired indices have been determined and scored by numeral valuation method in each unit and then analysis has been done by using of the geography information system (GIS) and final has estimated economic valuation of sensitive ecological areas that is presented in this essay.
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The period of the 18th and 19th centuries was one of great change in the Highlands and Islands of Scotland. Improvement, the Jacobite Rebellions, and the Clearances transformed its communities and landscapes. These events have rightly been a focus of research. However, archaeological approaches have often sought simply to illustrate these processes, rather than create new narratives about life in the past. The resulting picture of the period can over-emphasise economic change whilst failing to reflect the richness and variety of everyday life. This thesis aims to suggest a new approach to the place and period, one which addresses matters often ignored in previous work. Whilst it has an archaeological sensibility, it draws on ideas from outside archaeology, such as landscape theory and on Gaelic oral tradition, an underused resource, to create a novel and broad-based approach to the period. An important part of the method is a synchronic approach that seeks to reconstruct the experience of the landscape at very particular times, engaging fully with the everyday experience of landscape rather than grand historical narratives. Two Hebridean case studies are utilised: Hiort (St Kilda) and Loch Aoineart, South Uist. Thematic discussions drawn from these landscapes are intended as critical assessments of the efficacy of the approach, as well as new narratives about life in the past in themselves. The thesis concludes by comparing the two case studies, reflecting on the merits of the approach, discussing recurrent themes in the work, and considering its wider context and implications. It is concluded that taking a novel approach to the case study landscapes can create narratives that often contrast or expand upon those produced by previous scholars, allow for a more detailed consideration of everyday life in the period, and open up new areas for archaeological enquiry. The extensive and critical use of evidence from Gaelic oral tradition is highlighted as crucial in understanding life and society in the period. The thesis questions the utility of grand historical narratives as a framework for archaeological study of post-medieval Gaeldom and suggests that our understanding of the past is best served by approaching the evidence in ways which allows for many different voices and stories from the past to emerge.
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The sea surface temperature (SST) and chlorophyll-a concentration (CHL-a) were analysed in the Gulf of Tadjourah from two set of 8-day composite satellite data, respectively from 2008 to 2012 and from 2005 to 2011. A singular spectrum analysis (SSA) shows that the annual cycle of SST is strong (74.3% of variance) and consists of warming (April-October) and cooling (November-March) of about 2.5C than the long-term average. The semi-annual cycle captures only 14.6% of temperature variance and emphasises the drop of SST during July-August. Similarly, the annual cycle of CHL-a (29.7% of variance) depicts high CHL-a from June to October and low concentration from November to May. In addition, the first spatial empirical orthogonal function (EOF) of SST (93% of variance) shows that the seasonal warming/cooling is in phase across the whole study area but the southeastern part always remaining warmer or cooler. In contrast to the SST, the first EOF of CHL-a (54.1% of variance) indicates the continental shelf in phase opposition with the offshore area in winter during which the CHL-a remains sequestrated in the coastal area particularly in the south-east and in the Ghoubet Al-Kharab Bay. Inversely during summer, higher CHL-a quantities appear in the offshore waters. In order to investigate processes generating these patterns, a multichannel spectrum analysis was applied to a set of oceanic (SST, CHL-a) and atmospheric parameters (wind speed, air temperature and air specific humidity). This analysis shows that the SST is well correlated to the atmospheric parameters at an annual scale. The windowed cross correlation indicates that this correlation is significant only from October to May. During this period, the warming was related to the solar heating of the surface water when the wind is low (April-May and October) while the cooling (November-March) was linked to the strong and cold North-East winds and to convective mixing. The summer drop in SST followed by a peak of CHL-a, seems strongly correlated to the upwelling. The second EOF modes of SST and CHL-a explain respectively 1.3% and 5% of the variance and show an east-west gradient during winter that is reversed during summer. This work showed that the seasonal signals have a wide spatial influence and dominate the variability of the SST and CHL-a while the east-west gradient are specific for the Gulf of Tadjourah and seem induced by the local wind modulated by the topography.
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Malaga is in southern Spain, in a region called Andalusia. Costa del Sol belongs to the province of Malaga, near the Strait of Gibraltar and near the coast of Africa (about 300 km) and about 2,300 km of Sluptz. The Costa del Sol is next to the Mediterranean Sea and near the Atlantic Ocean. Strong and rapid growth of tourism in the countries of southern Europe and in Poland. Spain currently (2015) is the third largest inbound of international tourism (68 mil.) and the second inbound in tourism revenue. Europe is a major world tourist region. The first recipient of tourism in the world is France. Most tourism takes place between developed countries.
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Observing, modelling and understanding the climate-scale variability of the deep water formation (DWF) in the North-Western Mediterranean Sea remains today very challenging. In this study, we first characterize the interannual variability of this phenomenon by a thorough reanalysis of observations in order to establish reference time series. These quantitative indicators include 31 observed years for the yearly maximum mixed layer depth over the period 1980–2013 and a detailed multi-indicator description of the period 2007–2013. Then a 1980–2013 hindcast simulation is performed with a fully-coupled regional climate system model including the high-resolution representation of the regional atmosphere, ocean, land-surface and rivers. The simulation reproduces quantitatively well the mean behaviour and the large interannual variability of the DWF phenomenon. The model shows convection deeper than 1000 m in 2/3 of the modelled winters, a mean DWF rate equal to 0.35 Sv with maximum values of 1.7 (resp. 1.6) Sv in 2013 (resp. 2005). Using the model results, the winter-integrated buoyancy loss over the Gulf of Lions is identified as the primary driving factor of the DWF interannual variability and explains, alone, around 50 % of its variance. It is itself explained by the occurrence of few stormy days during winter. At daily scale, the Atlantic ridge weather regime is identified as favourable to strong buoyancy losses and therefore DWF, whereas the positive phase of the North Atlantic oscillation is unfavourable. The driving role of the vertical stratification in autumn, a measure of the water column inhibition to mixing, has also been analyzed. Combining both driving factors allows to explain more than 70 % of the interannual variance of the phenomenon and in particular the occurrence of the five strongest convective years of the model (1981, 1999, 2005, 2009, 2013). The model simulates qualitatively well the trends in the deep waters (warming, saltening, increase in the dense water volume, increase in the bottom water density) despite an underestimation of the salinity and density trends. These deep trends come from a heat and salt accumulation during the 1980s and the 1990s in the surface and intermediate layers of the Gulf of Lions before being transferred stepwise towards the deep layers when very convective years occur in 1999 and later. The salinity increase in the near Atlantic Ocean surface layers seems to be the external forcing that finally leads to these deep trends. In the future, our results may allow to better understand the behaviour of the DWF phenomenon in Mediterranean Sea simulations in hindcast, forecast, reanalysis or future climate change scenario modes. The robustness of the obtained results must be however confirmed in multi-model studies.
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In May, June and July 1996, samples wcre collected along one transect greatly influenced by river discharge (eastern side of the gulf), along one transect slightly influence by river discharge (western side), at one station Iocated in the mouth of the main river (River Daugava), at one station located in the center of the Gulf and at several nearshore locations of the western side. Ratios of rnolecular concentrations of in situ dissolved ioorganic nitrogen, phosphorus and silicon, as weIl as enrichment bioassays were llsed to dctcrrnine which nutrient (s) lirnited the potential biomass of phytoplankton. Both comparison of (NO.d-N02+NJ.L): P04 (DIN: DIP) values with Redfic1d's ratio and bioassay inspection led to the sarne conclusions. Phosphorus was clearly the nutrient most limiting for the potcntial biornass of test species in nitrogen- rich waters, which occurred in mid spring, in the upper layer of the southern-eastern part of the Gulf which is greatly influenced by river discharge. In late spring, with the decrease of the total DIN reserve, nitrogen and phosphorus showed an equallimiting role. In deeper layers of this area and out of the river plume (western side and central part of the gulf), nitrogen was the limiting nutrient. In summer, whcn river discharge was the lowest, a11 DIN concentrations but one ranged between 1.6 and 2.6 µM, and the whole area was nitrogen-limited for both the cyanobacterial and the algal test strains. In 74% of the samples for which nitrogen was the limiting nutrient, phosphorus was recorded to be the second potentially limiting nutrient. In contrast, silicon never appeared as limiting the growth potential of either Microcystis aeruginosa or Phaeodactylum tricornutum; phosphorus was the limiting nutrient when DIN: Si03 values were >1 (in May), but DIN: Si03 was <1 when nitrogen was limiting (June and July). The authors conclude that the recently reported decrease of silicon loading in coastal waters and its subsequent enhanced importance in pushing the outcome of species competition towards harmful species may not yet be the most important factor for the Gulf of Riga. Iron appeared for 12% of the tests in the list of nutrients limiting the potential biomass. Tentative results also indicated that a significant fraction of the nitrogen (~,4 µg-atom N 1(-1) taken up by Microcystis aeruginosa may have been in the form of dissolved organic nitrogen (DON). It is thus also suggested tentatively that more attention be paid to these nitrients during further research in the Gulf of Riga.
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Recent marine long-offset transient electromagnetic (LOTEM) measurements yielded the offshore delineation of a fresh groundwater body beneath the seafloor in the region of Bat Yam, Israel. The LOTEM application was effective in detecting this freshwater body underneath the Mediterranean Sea and allowed an estimation of its seaward extent. However, the measured data set was insufficient to understand the hydrogeological configuration and mechanism controlling the occurrence of this fresh groundwater discovery. Especially the lateral geometry of the freshwater boundary, important for the hydrogeological modelling, could not be resolved. Without such an understanding, a rational management of this unexploited groundwater reservoir is not possible. Two new high-resolution marine time-domain electromagnetic methods are theoretically developed to derive the hydrogeological structure of the western aquifer boundary. The first is called Circular Electric Dipole (CED). It is the land-based analogous of the Vertical Electric Dipole (VED), which is commonly applied to detect resistive structures in the subsurface. Although the CED shows exceptional detectability characteristics in the step-off signal towards the sub-seafloor freshwater body, an actual application was not carried out in the extent of this study. It was found that the method suffers from an insufficient signal strength to adequately delineate the resistive aquifer under realistic noise conditions. Moreover, modelling studies demonstrated that severe signal distortions are caused by the slightest geometrical inaccuracies. As a result, a successful application of CED in Israel proved to be rather doubtful. A second method called Differential Electric Dipole (DED) is developed as an alternative to the intended CED method. Compared to the conventional marine time-domain electromagnetic system that commonly applies a horizontal electric dipole transmitter, the DED is composed of two horizontal electric dipoles in an in-line configuration that share a common central electrode. Theoretically, DED has similar detectability/resolution characteristics compared to the conventional LOTEM system. However, the superior lateral resolution towards multi-dimensional resistivity structures make an application desirable. Furthermore, the method is less susceptible towards geometrical errors making an application in Israel feasible. In the extent of this thesis, the novel marine DED method is substantiated using several one-dimensional (1D) and multi-dimensional (2D/3D) modelling studies. The main emphasis lies on the application in Israel. Preliminary resistivity models are derived from the previous marine LOTEM measurement and tested for a DED application. The DED method is effective in locating the two-dimensional resistivity structure at the western aquifer boundary. Moreover, a prediction regarding the hydrogeological boundary conditions are feasible, provided a brackish water zone exists at the head of the interface. A seafloor-based DED transmitter/receiver system is designed and built at the Institute of Geophysics and Meteorology at the University of Cologne. The first DED measurements were carried out in Israel in April 2016. The acquired data set is the first of its kind. The measured data is processed and subsequently interpreted using 1D inversion. The intended aim of interpreting both step-on and step-off signals failed, due to the insufficient data quality of the latter. Yet, the 1D inversion models of the DED step-on signals clearly detect the freshwater body for receivers located close to the Israeli coast. Additionally, a lateral resistivity contrast is observable in the 1D inversion models that allow to constrain the seaward extent of this freshwater body. A large-scale 2D modelling study followed the 1D interpretation. In total, 425 600 forward calculations are conducted to find a sub-seafloor resistivity distribution that adequately explains the measured data. The results indicate that the western aquifer boundary is located at 3600 m - 3700 m before the coast. Moreover, a brackish water zone of 3 Omega*m to 5 Omega*m with a lateral extent of less than 300 m is likely located at the head of the freshwater aquifer. Based on these results, it is predicted that the sub-seafloor freshwater body is indeed open to the sea and may be vulnerable to seawater intrusion.
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Species composition and gear competition for the small-scale fisheries in the Cyclades waters (off Naxos Island, Aegean Sea. Hellas) was studied based on samples collected during 1997-1998 with gill nets of different mesh sizes and longlines with hooks of different sizes. Comparisons used univariate and multivariate techniques based on species compositions by number and weight and the commercial/total catch ratio in terms of weight and number. The results of the various techniques were in agreement and suggested that the different gear/size/season combinations fall into two groups (all gill nets and all longlines), which differed from each other in terms of species composition. species diversity and dominance. In contrast, the commercial/total catch ratio did not differ either within and between gears. The implications of the results for the management of the Mediterranean fisheries resources are also discussed. (C) 2002 Elsevier Science B.V. All rights reserved.
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The sea lamprey Petromyzon marinus (Linnaeus) is both an invasive non-native species in the Laurentian Great Lakes of North America and an imperiled species in much of its native range in North America and Europe. To compare and contrast how understanding of population ecology is useful for control programs in the Great Lakes and restoration programs in Europe, we review current understanding of the population ecology of the sea lamprey in its native and introduced range. Some attributes of sea lamprey population ecology are particularly useful for both control programs in the Great Lakes and restoration programs in the native range. First, traps within fish ladders are beneficial for removing sea lampreys in Great Lakes streams and passing sea lampreys in the native range. Second, attractants and repellants are suitable for luring sea lampreys into traps for control in the Great Lakes and guiding sea lamprey passage for conservation in the native range. Third, assessment methods used for targeting sea lamprey control in the Great Lakes are useful for targeting habitat protection in the native range. Last, assessment methods used to quantify numbers of all life stages of sea lampreys would be appropriate for measuring success of control in the Great Lakes and success of conservation in the native range.
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This doctoral thesis focuses on the study of historical shallow landslide activity over time in response to anthropogenic forcing on land use, through the compilation of multi-temporal landslide inventories. The study areas, located in contrasting settings and characterized by different history of land-cover changes, include the Sillaro River basin (Italy) and the Tsitika and Eve River basins (coastal British Columbia). The Sillaro River basin belongs to clay-dominated settings, characterized by extensive badland development, and dominated by earth slides and earthflows. Here, forest removal began in the Roman period and has been followed by agricultural land abandonment and natural revegetation in recent time. By contrast, the Tsitika-Eve River basins are characterized by granitic and basaltic lithologies, and dominated by debris slides, debris flows and debris avalanches. In this setting, anthropogenic impacts started in 1960’s and have involved logging operation. The thesis begins with an introductory chapter, followed by a methodological section, where a multi-temporal mapping approach is proposed and tested at four landslide sites of the Sillaro River basin. Results, in terms of inventory completeness in time and space, are compared against the existing region-wide Emilia-Romagna inventory. This approach is then applied at the Sillaro River basin scale, where the multi-temporal inventory obtained is used to investigate the landslide activity in relation to historical land cover changes across geologic domains and in relation to hydro-meteorological forcing. Then, the impact of timber harvesting and road construction on landslide activity and sediment transfer in the Tsitika-Eve River basins is investigated, with a focus on the controls that interactions between landscape morphometry and cutblock location may have on landslide size-frequency relations. The thesis ends with a summary of the main findings and discusses advantages and limitations associated with the compilation of multi-temporal inventories in the two settings during different periods of human-driven, land-cover dynamics.
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Sea–level change is one of the ocean characteristics closely connected to climate change. Understanding its variation is essential since a large portion of the world’s population is located in low–lying locations. Two main techniques are employed to measure sea level: satellite altimetry and tide gauges. Satellite altimetry monitors sea–level relative to a geocentric reference, is unaffected by crustal processes and covers nearly the entire surface of the oceans since 1993. Conversely, tide gauges measure sea level at specific coastal locations and relative to a local ground benchmark, therefore are impacted by vertical land movements. In this study, the linear and non–linear geocentric and relative sea–level trends along the Emilia–Romagna coast (Northern Italy) have been analyzed over different periods. In order to assess the local sea–level variability, data from satellite altimetry and tide gauges have been compared over a common time interval (1993–2019), hence disentangling the contribute of vertical land movements. Non–linearity has been also evaluated at the broader scale of the Mediterranean Sea, in order to depict the main variability in geocentric sea–level trends from regional to sub–basin scale. Furthermore, the anthropogenic and natural influence at the river basin scale has been addressed, in order to shed light on the factors inducing the drastic reduction of riverine sediment supply to the Emilia–Romagna coast over the period 1920–2020. The findings of this analysis indicate that the sediment delivery reduction to the coast by rivers has been driven by several anthropogenic processes, acting on various spatiotemporal scales. Moreover, the local absolute sea–level trend is far from linear and appear "contaminated" by the presence of natural oscillations that act at the multi–decadal, quasi–decadal and inter–annual scale, mainly driven by both large–scale climatic modes and variations in local oceanography.