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Costa de fiordes da Patagônia Central, Chile, morfologia submarina e fácies acústicas

Vieira, Rosemary; Simões, Jefferson Cardia
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
POR
Relevância na Pesquisa
27.33%
Esse estudo interpreta os perfis acústicos de subfundo e modelos 3D submarinos de alguns fiordes adjacentes ao Campo de Gelo Patagônico Sul, Chile. As bacias aprofundadas mostram a morfologia irregular e distintas formas associadas ao sistema sedimentar de zonas de grounding line, de línguas de gelos flutuantes. Refletores acústicos exibem duas fácies principais: caóticas e estratificadas, segundo sua configuraçãao interna e geometria externa. Os sedimentos provavelmente foram depositados durante a deglaciação durante o Holoceno. A geometria dos depocentros e as características dos refletores acústicos mostram evidências da influência da batimetria e da topografia pré-existentes. Devido às grandes profundidades das bacias, as margens terminais podem ter sido um misto de condiçõoes flutuantes e aterradas no fundo marinho, embora possa predominar o regime glacial temperado.; This study interprets acoustic sub-bottom profiles and submarine 3D models of some of fjords adjacent to Campo de Hielo Patagônico Sur (Southern Patagonian Icefield), Chile. The overdeepened fjord basins show irregular morphology and distinctive landforms associated with a grounding-line, ice tongues and icebergs sedimentary system. Acoustic reflectors display two main facies: chaotic and laminated...

Development of usage statistics for RepositóriUM

Rodrigues, Eloy; Miranda, Ângelo
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /04/2006 ENG
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16.69%
Apresentação efectuada no DSpace User Group Meeting: "Dugnad" among the fjords, Bergen, Norway, 20 - 21 April 2006.; The usage statistics software developed at Minho University, for RepositóriUM, the institutional repository based on DSpace is presented. The system was developed based on the principles and some of the components of the statistics application created and released by ANU. Despite the fact that the development was made to respond to the specific needs of RepositóriUM, the system is completely adjustable to other environments, because their components can be easily configured, changed or extended, to respond to different information needs. The system is composed by 3 main components: Log Processor, Data Model, Web Interface. The first one is responsible for the gathering, real time processing and storing of event logs generated by DSpace. It is composed by different event processors, each one adjusted to a specific event. The second component is the data model stored in a data base management system (DBMS), where the relevant, and properly processed, information is archived. The Web interface is flexible, allowing to configure – according with a base structure –the display of the information in the user interface. The structure of the system is based in the organization of information in two dimensions: type of information (access...

Contribucion al conocimiento de las condiciones hidrograficas de los fiordos de la region magallanica - Chile

Chuecas M,Lisandro; Ahumada B,Ramon
Fonte: Instituto Oceanográfico da Universidade de São Paulo Publicador: Instituto Oceanográfico da Universidade de São Paulo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/1980 ES
Relevância na Pesquisa
17.33%
The spring hydrographic conditions of Magellan flords region were described (i.e., Seno Almirantazgo, Bahía Inútil, Seno Otway and Golfo Xaultegua). The large differences in the water body observed among the fjords were related to the distance between the fjords to the shore and the influence of the coastal waters. Furthemore a seasonal variations analysis with spring and fall data has been carried out. The result shows that the most important parameter in the seasonal fluctuations of the water body was temperature.

Actinomycetes from Sediments in the Trondheim Fjord, Norway:  Diversity and Biological Activity

Bredholt, Harald; Fjærvik, Espen; Johnsen, Geir; Zotchev, Sergey B.
Fonte: Molecular Diversity Preservation International Publicador: Molecular Diversity Preservation International
Tipo: Artigo de Revista Científica
Publicado em 23/01/2008 EN
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17.33%
The marine environment represents a largely untapped source for isolation of new microorganisms with potential to produce biologically active secondary metabolites. Among such microorganisms, Gram-positive actinomycete bacteria are of special interest, since they are known to produce chemically diverse compounds with a wide range of biological activities. We have set out to isolate and characterize actinomycete bacteria from the sediments in one of the largest Norwegian fjords, the Trondheim fjord, with respect to diversity and antibiotic-producing potential. Approximately 3,200 actinomycete bacteria were isolated using four different agar media from the sediment samples collected at different locations and depths (4.5 to 450 m). Grouping of the isolates first according to the morphology followed by characterization of isolates chosen as group representatives by molecular taxonomy revealed that Micromonospora was the dominating actinomycete genus isolated from the sediments. The deep water sediments contained a higher relative amount of Micromonospora compared to the shallow water samples. Nine percent of the isolates clearly required sea water for normal growth, suggesting that these strains represent obligate marine organisms. Extensive screening of the extracts from all collected isolates for antibacterial and antifungal activities revealed strong antibiotic-producing potential among them. The latter implies that actinomycetes from marine sediments in Norwegian fjords can be potential sources for the discovery of novel anti-infective agents.

High Natality Rates of Endangered Steller Sea Lions in Kenai Fjords, Alaska and Perceptions of Population Status in the Gulf of Alaska

Maniscalco, John M.; Springer, Alan M.; Parker, Pamela
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 08/04/2010 EN
Relevância na Pesquisa
27.33%
Steller sea lions experienced a dramatic population collapse of more than 80% in the late 1970s through the 1990s across their western range in Alaska. One of several competing hypotheses about the cause holds that reduced female reproductive rates (natality) substantively contributed to the decline and continue to limit recovery in the Gulf of Alaska despite the fact that there have been very few attempts to directly measure natality in this species. We conducted a longitudinal study of natality among individual Steller sea lions (n = 151) at a rookery and nearby haulouts in Kenai Fjords, Gulf of Alaska during 2003–2009. Multi-state models were built and tested in Program MARK to estimate survival, resighting, and state transition probabilities dependent on whether or not a female gave birth in the previous year. The models that most closely fit the data suggested that females which gave birth had a higher probability of surviving and giving birth in the following year compared to females that did not give birth, indicating some females are more fit than others. Natality, estimated at 69%, was similar to natality for Steller sea lions in the Gulf of Alaska prior to their decline (67%) and much greater than the published estimate for the 2000s (43%) which was hypothesized from an inferential population dynamic model. Reasons for the disparity are discussed...

Megafaunal Communities in Rapidly Warming Fjords along the West Antarctic Peninsula: Hotspots of Abundance and Beta Diversity

Grange, Laura J.; Smith, Craig R.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 03/12/2013 EN
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28.36%
Glacio-marine fjords occur widely at high latitudes and have been extensively studied in the Arctic, where heavy meltwater inputs and sedimentation yield low benthic faunal abundance and biodiversity in inner-middle fjords. Fjord benthic ecosystems remain poorly studied in the subpolar Antarctic, including those in extensive fjords along the West Antarctic Peninsula (WAP). Here we test ecosystem predictions from Arctic fjords on three subpolar, glacio-marine fjords along the WAP. With seafloor photographic surveys we evaluate benthic megafaunal abundance, community structure, and species diversity, as well as the abundance of demersal nekton and macroalgal detritus, in soft-sediment basins of Andvord, Flandres and Barilari Bays at depths of 436–725 m. We then contrast these fjord sites with three open shelf stations of similar depths. Contrary to Arctic predictions, WAP fjord basins exhibited 3 to 38-fold greater benthic megafaunal abundance than the open shelf, and local species diversity and trophic complexity remained high from outer to inner fjord basins. Furthermore, WAP fjords contained distinct species composition, substantially contributing to beta and gamma diversity at 400–700 m depths along the WAP. The abundance of demersal nekton and macroalgal detritus was also substantially higher in WAP fjords compared to the open shelf. We conclude that WAP fjords are important hotspots of benthic abundance and biodiversity as a consequence of weak meltwater influences...

Picky, hungry eaters in the cold: persistent substrate selectivity among polar pelagic microbial communities

Steen, Andrew D.; Arnosti, Carol
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 08/10/2014 EN
Relevância na Pesquisa
17.33%
Polar pelagic microbial communities access a narrower range of polysaccharide substrates than communities at lower latitudes. For example, the glucose-containing polysaccharide pullulan is typically not hydrolyzed in fjord waters of Svalbard, even though pullulan is rapidly hydrolyzed in sediments from Svalbard fjords, other polysaccharides are hydrolyzed rapidly in Svalbard waters, and pullulan is hydrolyzed rapidly in temperate waters. The purpose of this study was to investigate potential factors preventing hydrolysis of pullulan in Svalbard fjord waters. To this end, in two separate years, water from Isfjorden, Svalbard, was amended with different carbon sources and/or additional nutrients in order to determine whether increasing the concentration of these potentially-limiting factors would lead to measurable enzymatic activity. Addition of nitrate, phosphate, glucose, or amino acids did not yield detectable pullulan hydrolysis. The only treatment that led to detectable pullulan hydrolysis was extended incubation after the addition of maltotriose (a subunit of pullulan, and potential inducer of pullulanase). In these fjords, the ability to enzymatically access pullulan is likely confined to numerically minor members of the pelagic microbial community. These results are consistent with the hypothesis that pelagic microbial communities at high latitudes exhibit streamlined functionality...

Spatially Estimating Disturbance of Harbor Seals (Phoca vitulina)

Jansen, John K.; Brady, Gavin M.; Ver Hoef, Jay M.; Boveng, Peter L.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 01/07/2015 EN
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17.33%
Tidewater glacial fjords in Alaska provide habitat for some of the largest aggregations of harbor seals (Phoca vitulina), with calved ice serving as platforms for birthing and nursing pups, molting, and resting. These fjords have also been popular destinations for tour ships for more than a century, with dramatic increases in vessel traffic since the 1980s. Seals on ice are known to flush into the water when approached by tour ships, but estimating the exposure to disturbance across populations is difficult. Using aerial transect sampling while simultaneously tracking vessel movements, we estimated the spatial overlap between seals on ice and cruise ships in Disenchantment Bay, Alaska, USA. By integrating previously estimated rates of disturbance as a function of distance with an ‘intensity surface’ modeled spatially from seal locations in the surveys, we calculated probabilities of seals flushing during three separate ship visits. By combining our estimate of seals flushed with a modeled estimate of the total fjord population, we predict that up to 14% of the seals (up to 11% of pups) hauled out would have flushed into the water, depending on the route taken by ships relative to seal aggregations. Such high potential for broad-scale disturbance by single vessels (when up to 4 ships visit per day) was unexpected and underscores the need to 1) better understand long-term effects of disturbance; 2) regularly monitor populations exposed to high vessel traffic; and 3) develop conservation measures to reduce seal-ship overlap.

TERRIGENOUS, BIOGENIC, AND VOLCANOCLASTIC SEDIMENTATION PATTERNS OF THE BRANSFIELD STRAIT AND BAYS OF THE NORTHERN ANTARCTIC PENINSULA: IMPLICATIONS FOR QUATERNARY GLACIAL HISTORY

SINGER, JILL KAREN
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
17.33%
A marine sedimentologic investigation was conducted on the northern Antarctic Peninsula continental margin. The data base included piston cores, surficial sediments, and high resolution seismic reflection profiles. The objectives of this study were three-fold: examine sedimentation patterns in the Bransfield Basin, a high-latitude, actively spreading back-arc basin; relate sedimentation processes to lithofacies patterns in bays and fjords of the South Shetland Islands, Palmer Archipelago, and Danco Coast; and interpret the recent glacial-climatic history of this region. As a back-arc basin in a polar latitude, the Bransfield Basin represents a unique sedimentary environment. Fluvial discharge systems are lacking and the Bransfield Basin receives only minor amounts of continentally-derived sediment. The South Shetland arc is inactive, and the locus of recent volcanic activity is the axis of back-arc spreading. The sediments accumulating in the Bransfield Basin represent the input of terrigenous, biogenic, and volcaniclastic phases. Sediment distribution reflects the interplay of marine currents, primary production, and volcanic activity. At water depths $<$250 m, marine currents actively redistribute sediment, and residual deposits blanket the shelf between the northern tip of the Antarctic Peninsula and Tower Island. A transition from residual deposits to deposits with increased mud content west of Tower Island indicates a decrease in the intensity of marine currents as they flow east to west along the shelf. Lower energy conditions characterize the Bransfield Basin...

Seismic facies investigation and late Quaternary glacial history of the Chilean shelf and fjords and Antarctic Peninsula fjords

DaSilva, Jana Lee
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
17.33%
High-resolution seismic data collected in inland waters Chile and the Antarctic Peninsula (41$spcirc$S-65$spcirc$S) were interpreted using seismic facies analysis. Piston cores provide some lithologic control on the interpretation of the seismic data. These data span a latitudinal transect that encompasses temperate, subpolar and polar climatic regimes, and these regimes are characterized by differences in seismic facies. In the present climatic regime, northern and central Chile fall into a temperate climate regime and the Antarctic Peninsula falls into a subpolar/polar climate regime. A sub-temperate facies transition encompasses the South Shetland Islands and southern Chilean fjord region. The data were used to compile maps that show seismic facies distribution patterns and these maps are the basis for glacial reconstructions that span the present interglacial to the Last Glacial Maximum (LGM). The maps show the extent of northward shift in climatic settings during the Last Glacial Maximum.

Simulation of optically conditioned retention and mass occurrences of Periphylla periphylla

Dupont, Nicolas; Aksnes, Dag L.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
17.33%
Jellyfish blooms are of increasing concern in many parts of the world, and in Norwegian fjords an apparent increase in mass occurrences of the deep water jellyfish Periphylla periphylla has attracted attention. Here we investigate the hypothesis that changes in the water column light attenuation might cause local retention and thereby facilitate mass occurrences. We use a previously tested individual-based model of light-mediated vertical migration in P. periphylla to simulate how retention is affected by changes in light attenuation. Our results suggest that light attenuation, in combination with advection, has a two-sided effect on retention and that three fjord categories can be defined. In category 1, increased light attenuation turns fjords into dark “deep-sea” environments which increase the habitat and retention of P. periphylla. In category 2, an optimal light attenuation facilitates the maximum retention and likelihood for mass occurrences. In category 3, further increase in light attenuation, however, shoals the habitat so that individuals are increasingly exposed to advection and this results in loss of individuals and decreased retention. This classification requires accurate determinations of the organism's light preference...

Modeling suspended solids in a Northern Chilean Patagonia glacier-fed fjord: GLOF scenarios under climate change conditions

Paredes, María Alejandra; Tironi, Antonio; Contreras, Manuel; Marín Briano, Víctor Hernán
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo de revista
EN
Relevância na Pesquisa
27.66%
Artículo de publicación ISI; Suspended solids play an ecologically important role in glacier-fed fjords, given its dominant effect on their primary production arising from the generation of turbid water plumes by retreating glaciers, which increase light attenuation. Glacial-lake outburst floods, GLOFs, are sudden releases of lake-water impounded by a glacier which may affect either locally or regionally depending on the amount of water and suspended solids released. Chilean Patagonia has been characterized by some of the fastest glacial retreats worldwide and by an increase in GLOFs events. In this article we describe the development of a hydrodynamic model to study the distribution of suspended solids in the Baker channel, a glacier-fed fjord located in Northern Chilean Patagonia. We further describe the simulation of three climate change induced GLOF scenarios and discuss their potential effects on fjord’s primary production. The model was implemented as a two-level, one-way, nested hierarchy using the MOHID water modeling system. The large extent, oceanic, level corresponded to a one-layer barotropic model, while the smaller extent, fjord, level corresponded to a 3D baroclinic model with 31 Cartesian layers. Velocities...

Size diversity as an expression of phytoplankton community structure and the identification of its patterns on the scale of fjords and channels

Montecino, Vivian; Paredes, María Alejandra
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo de revista
EN
Relevância na Pesquisa
27.33%
Artículo de publicación ISI; Large microalgae, such as diatoms can generate high levels of biomass, unlike small phytoplankton components in the austral Fjords and estuarine systems of Chile. We propose a cell-size-based diversity index (H'(size)) measured as chlorophyll-a concentrations (Chl-a) to determine if the relationship between H'(size) versus Chl-a results in a hump-shaped distribution considering: (i) the intermediate disturbance hypothesis, (ii) phytoplankton size colonization strategies, and (iii) predictions of low H'(size) with high or low Chl-a levels and peaks in H'(size) with intermediate Chl-a levels. The functional responses of phytoplankton are tightly coupled to environmental conditions. Could, then, the relationship between H'(size) and Chl-a occur on a particular temporal/spatial scale? Herein, we analyze data from three CIMAR-Fiordos cruises performed between 2001 and 2002 within areas of different continental influence from 41 degrees to 47 degrees S. Phytoplankton samples were taken at different locations and depths, filtered to obtain Chl-a with and without size-fractionation (> 20 mu m, < 11 mu m), and then used to calculate H'(size). Total Chl-a (TChl-a) changed by two orders of magnitude between different cruises and areas. The small phytoplankton fraction (< 11 mu m) dominated with low TChl-a values (<= 1 mg m(-3))...

Glaciation as a destructive and constructive control on mountain building

Tomkin, Jonathan H.; Vásquez, Cristián; Reiners, Peter W.; Wilson, Nathaniel J.; Brandon, Mark T.; Thomson, Stuart N.
Fonte: NATURE PUBLISHING GROUP Publicador: NATURE PUBLISHING GROUP
Tipo: Artículo de revista
EN
Relevância na Pesquisa
17.33%
Theoretical analysis predicts that enhanced erosion related to late Cenozoic global cooling can act as a first-order influence on the internal dynamics of mountain building, leading to a reduction in orogen width and height(1-3). The strongest response is predicted in orogens dominated by highly efficient alpine glacial erosion, producing a characteristic pattern of enhanced erosion on the windward flank of the orogen and maximum elevation controlled by glacier equilibriumline altitude(3,4), where long-term glacier mass gain equals mass loss. However, acquiring definitive field evidence of an active tectonic response to global climate cooling has been elusive(5). Here we present an extensive new low-temperature thermochronologic data set from the Patagonian Andes, a high-latitude active orogen with a well-documented late Cenozoic tectonic, climatic and glacial history. Data from 38 degrees S to 49 degrees S record a marked acceleration in erosion 7 to 5 Myr ago coeval with the onset of major Patagonian glaciation(6) and retreat of deformation from the easternmost thrust front(7). The highest rates and magnitudes of erosion are restricted to the glacial equilibrium line altitude on the windward western flank of the orogen, as predicted in models of glaciated critical taper orogens where erosion rate is a function of ice sliding velocity(3...

Multi-Cuts Solutions of Laplacian Growth

Abanov, Ar.; Mineev-Weinstein, M.; Zabrodin, A.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
17.33%
A new class of solutions to Laplacian growth with zero surface tension is presented and shown to contain all other known solutions as special or limiting cases. These solutions, which are time-dependent conformal maps with branch cuts inside the unit circle, are governed by a nonlinear integral equation and describe oil fjords with non-parallel walls in viscous fingering experiments in Hele-Shaw cells. Integrals of motion for the multi-cut Laplacian growth solutions in terms of singularities of the Schwarz function are found, and the dynamics of densities (jumps) on the cuts are derived. The subclass of these solutions with linear Cauchy densities on the cuts of the Schwarz function is of particular interest, because in this case the integral equation for the conformal map becomes linear. These solutions can also be of physical importance by representing oil/air interfaces, which form oil fjords with a constant opening angle, in accordance with recent experiments in a Hele-shaw cell.; Comment: 19 pages, 3 figures, improved order of exposition

Remote sensing of seawater and drifting ice in Svalbard fjords by compact Raman LIDAR

Bunkin, Alexey F.; Klinkov, Vladimir K.; Lednev, Vasily N.; Lushnikov, Dmitry L.; Marchenko, Aleksey V.; Morozov, Eugene G.; Pershin, Sergey M.; Yulmetov, Renat N.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 08/08/2013
Relevância na Pesquisa
27.33%
A compact Raman LIDAR system for remote sensing of sea and drifting ice was developed at the Wave Research Center at the Prokhorov General Physics Institute of the RAS. The developed system is based on a diode pumped solid state YVO4:Nd laser combined with compact spectrograph equipped with gated detector. The system exhibits high sensitivity and can be used for mapping or depth profiling of different parameters within many oceanographic problems. Light weight (~20 kg) and low power consumption (300 W) make possible to install the device on any vehicle including unmanned aircraft or submarine system. The Raman LIDAR presented was used for Svalbard fjords study and analysis of different influence of the open sea and glaciers on the water properties. Temperature, phytoplankton, and dissolved organic matter distributions in the seawater were studied in the Ice Fjord, Van Mijen Fjord and Rinders Fjord. Drifting ice and seawater in the Rinders Fjord were characterized by the Raman spectroscopy and fluorescence. It was found that the Paula Glacier strongly influences the water temperature and chlorophyll distributions in the Van Mijen Fjord and Rinders Fjord. Possible applications of compact LIDAR systems for express monitoring of seawater in the places with high concentration of floating ice or near cold streams in the Arctic Ocean are discussed; Comment: 28 pages...

Fjords in viscous fingering: Selection of width and opening angle

Ristroph, Leif; Thrasher, Matthew; Mineev-Weinstein, Mark B.; Swinney, Harry L.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
28%
Our experiments on viscous fingering of air into oil contained between closely spaced plates reveal two selection rules for the fjords of oil that separate fingers of air. (Fjords are the building blocks of solutions of the zero-surface-tension Laplacian growth equation.) Experiments in rectangular and circular geometries yield fjords with base widths 1/2 lambda_c, where lambda_c is the most unstable wavelength from a linear stability analysis. Further, fjords open at an angle of 8.0 degrees plus or minus 1.0 degree. These selection rules hold for a wide range of pumping rates and fjord lengths, widths, and directions.; Comment: 4 pages, 4 figures. The APS version of this article is available at http://link.aps.org/abstract/PRE/v74/e015201

Contribucion al conocimiento de las condiciones hidrograficas de los fiordos de la region magallanica - Chile

Chuecas M, Lisandro; Ahumada B, Ramon
Fonte: Universidade de São Paulo. Instituto Oceanográfico Publicador: Universidade de São Paulo. Instituto Oceanográfico
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; Formato: application/pdf
Publicado em 01/01/1980 SPA
Relevância na Pesquisa
17.33%
The spring hydrographic conditions of Magellan flords region were described (i.e., Seno Almirantazgo, Bahía Inútil, Seno Otway and Golfo Xaultegua). The large differences in the water body observed among the fjords were related to the distance between the fjords to the shore and the influence of the coastal waters. Furthemore a seasonal variations analysis with spring and fall data has been carried out. The result shows that the most important parameter in the seasonal fluctuations of the water body was temperature.

SELECTION OF HAUL-OUT SUBSTRATE BY HARBOR SEALS (PHOCA VITULINA) ASSOCIATED WITH TIDEWATER GLACIERS IN KENAI FJORDS NATIONAL PARK, ALASKA.

Bishop, Amanda
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Masters' project
Publicado em 28/04/2011 EN_US
Relevância na Pesquisa
27.86%
In Alaska, 10-15% of harbor seals use glacial ice as a haulout substrate on which to rest, molt, and care for young. Some glaciers in Kenai Fjords National Park are receding at a staggering rate which could reduce the habitat available to seals in the near future. Understanding the current usage of haulout substrate at both a local and region scale will be vital to effective and proactive management of the species in light of climate change predictions. The primary goal of the present study was to evaluate the seasonal characteristics of ice availability and the associated patterns of usage by harbor seals in Northwestern Fjord—which terminates in a rapidly receding glacier. Patterns of seal attendance and ice conditions were evaluated across six sub-regions and across two summers. Data from Northwestern Fjord was also contrasted with observations conducted in a location, Aialik Bay, where the primary glacier is relatively stable. Results of this analysis indicate seasonal patterns of ice availability and linkages between seasonal ice conditions and the numbers of seals present. Overall ice coverages did not have predictable seasonal trends but small and medium sized ice platforms had significant trends in their availability throughout the summer. In Northwestern Fjord attendance peaked in midsummer and was positively correlated with ice availability and the availability of large sized bergs. Seal attendance also exhibited seasonal trends in Aialik Bay but opposite those observed in Northwestern Fjord. This study provided a baseline understanding of habitat availability and usage for the study area. Further research examining the patterns of habitat use by sex...

Impact of ocean stratification on submarine melting of a major Greenland outlet glacier

Fiammetta Straneo; Ruth Curry; David Sutherland; Gordon Hamilton; Claudia Cenedese; Kjetil Vaage; Leigh Stearns
Fonte: Nature Preceedings Publicador: Nature Preceedings
Tipo: Manuscript
Relevância na Pesquisa
17.86%
Submarine melting is an important balance term for tidewater glaciers1,2 and recent observations point to a change in the submarine melt rate as a potential trigger for the widespread acceleration of outlet glaciers in Greenland3-5. Our understanding of the dynamics involved, and hence our ability to interpret past and predict future variability of the Greenland Ice Sheet, however, is severely impeded by the lack of measurements at the ice/ocean interface. To fill this gap, attempts to quantify the submarine melt rate and its variability have relied on a paradigm developed for tidewater glaciers terminating in fjords with shallow sills. In this case, the fjords’ waters are mostly homogeneous and the heat transport to the terminus, and hence the melt rate, is controlled by a single overturning cell in which glacially modified water upwells at the ice edge, driving an inflow at depth and a fresh outflow at the surface1. Greenland’s fjords, however, have deep sills which allow both cold, fresh Arctic and warm, salty Atlantic waters, circulating around Greenland, to reach the ice sheet margin3,6,7. Thus, Greenland’s glaciers flow into strongly stratified fjords and the generic tidewater glacier paradigm is not applicable. Here...