Overwintering of terrestrial Arctic arthropods: the fauna of Svalbard now and in the future     

María Luisa Ávila-Jiménez  Stephen J. Coulson  Torstein Solhøy  & Anna Sjöblom 《Polar research》2010,29(1):127-137

There are over 500 species of arthropods recorded from Svalbard. These animals overwinter either within the soil or on the ground surface, and have to tolerate an environment where the ground is frozen for over 9 months each year. Three cold-tolerance strategies have been described from Svalbard invertebrates: freeze avoidance, freeze tolerance and desiccation. Once in a cold-tolerant state the animals can be extremely cold tolerant in terms of both minimum exposure temperature and period of exposure. How the overwintering capabilities of these animals will be affected by climate changes during the next 100 years, as predicted by climate models, is not yet known. Four principle factors with an impact on overwintering of the terrestrial arthropod fauna are outlined here: (1) warmer winter temperatures, with an increased frequency of extreme events such as freeze–thaw cycles and surface icing; (2) changes in snow fall and snow lie; (3) pollutant load; and (4) dispersal of invertebrates to Svalbard. Finally, areas where further research is required are highlighted: including the development of controlled multi-season field experiments; effect of freeze–thaw cycles; changes in thickness and distribution of snow lie, with the subsequent effects on duration of the summer period; chill susceptibility of soil arthropods; assessing potential colonizing species and the likelihood of these species becoming established; assessing the effect of gene flow from surrounding populations; interactions between pollution and cold tolerance; anoxia stress; and the genetics of cold tolerance.  相似文献   

Surface mass balance and ice flow of the glaciers Austre Lovenbreen and Pedersenbreen,Svalbard,Arctic     

徐明星  闫明  任贾文  艾松涛  康建成  鄂栋臣 《极地研究(英文版)》2010,(2):147-159

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The structural,geometric and volumetric changes of a polythermal Arctic glacier during a surge cycle: Comfortlessbreen,Svalbard          下载免费PDF全文

Owen King  Michael J. Hambrey  Tristram D. L. Irvine‐Fynn  Tom O. Holt 《地球表面变化过程与地形》2016,41(2):162-177

Various parameters of the most recent surge of the polythermal glacier Comfortlessbreen in northwest Svalbard, have been assessed through a combination of remote sensing and ground observations. Analysis of a digital elevation model time‐series shows a marked change in the geometry of the glacier from quiescence (1990 and earlier) into the late surge phase (2009). The transfer of 0.74 km³ of ice caused up to 80 m of surface drawdown in the reservoir area, above the equilibrium line, whilst ice built up in a spatially concentrated manner in the receiving zone, below the equilibrium line. A ramp of ice, c. 100 m above quiescent level, developed in the lower reaches of the glacier late in the surge. Also in the lower reaches of the glacier, structures attributable to the passage of a kinematic wave are identified and the migration of a surge front on the glacier is thus inferred. In a conceptual model, we consider that a bend in the valley, in which the glacier resides, and convergence with tributary glaciers, to be significant factors in the style of surge evolution. Their flow‐restrictive interference results in slow initial mass‐transfer and the growth of a surge front within 3–4 km of the terminus. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Water temperature dynamics in High Arctic river basins   总被引：2，自引：0，他引：2  

Phillip J. Blaen  David M. Hannah  Lee E. Brown  Alexander M. Milner 《水文研究》2013,27(20):2958-2972

Despite the high sensitivity of polar regions to climate change and the strong influence of temperature upon ecosystem processes, contemporary understanding of water temperature dynamics in Arctic river systems is limited. This research gap was addressed by exploring high‐resolution water column thermal regimes for glacier‐fed and non‐glacial rivers at eight sites across Svalbard during the 2010 melt season. Mean water column temperatures in glacier‐fed rivers (0.3–3.2 °C) were lowest and least variable near the glacier terminus but increased downstream (0.7–2.3 °C km^–1). Non‐glacial rivers, where discharge was sourced primarily from snowmelt runoff, were warmer (mean: 2.9–5.7 °C) and more variable, indicating increased water residence times in shallow alluvial zones and increased potential for atmospheric influence. Mean summer water temperature and the magnitude of daily thermal variation were similar to those of some Alaskan Arctic rivers but low at all sites when compared with alpine glacierized environments at lower latitudes. Thermal regimes were correlated strongly (p < 0.01) with incoming short‐wave radiation, air temperature, and river discharge. Principal drivers of thermal variability were inferred to be (i) water source (i.e. glacier melt, snowmelt, groundwater); (ii) exposure time to the atmosphere; (iii) prevailing meteorological conditions; (iv) river discharge; (v) runoff interaction with permafrost and buried ice; and (vi) basin‐specific geomorphological features (e.g. channel morphology). These results provide insight into the potential changes in high‐latitude river systems in the context of projected warming in polar regions. We hypothesize that warmer and more variable temperature regimes may prevail in the future as the proportion of bulk discharge sourced from glacial meltwater declines and rivers undergo a progressive shift towards snow water and groundwater sources. Importantly, such changes could have implications for aquatic species diversity and abundance and influence rates of ecosystem functioning in high‐latitude river systems. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Depositional processes of the Zhushadong and Mantou formations (Early to Middle Cambrian), Shandong Province,China: roles of archipelago and mixed carbonate–siliciclastic sedimentation on cycle genesis during initial flooding of the North China Platform     

SUNG KWUN CHOUGH 《Sedimentology》2011,58(6):1530-1572

To understand the depositional processes and environmental changes during the initial flooding of the North China Platform, this study focuses on the Lower to Middle Cambrian Zhushadong and Mantou formations in Shandong Province, China. The succession in the Jinan and Laiwu areas comprises mixed carbonate and siliciclastic deposits composed of limestone, dolostone, stromatolite, thrombolite, purple and grey mudstone, and sandstone. A detailed sedimentary facies analysis of seven well‐exposed sections suggests that five facies associations are the result of an intercalation of carbonate and siliciclastic depositional environments, including local alluvial fans, shallowing‐upward carbonate–siliciclastic peritidal cycles, oolite dominant shoals, shoreface and lagoonal environments. These facies associations successively show a transition from an initially inundated tide‐dominated carbonate platform to a wave‐dominated shallow marine environment. In particular, the peritidal sediments were deposited during a large number of depositional cycles. These sediments consist of lime mudstone, dolomite, stromatolite and purple and grey mudstones. These shallowing‐upward cycles generally resulted from carbonate production in response to an increase of accommodation during rising sea‐level. The carbonate production was, however, interrupted by frequent siliciclastic input from the adjacent emergent archipelago. The depositional cycles thus formed under the influence of both autogenetic changes, including sediment supply from the archipelago, and allogenic control of relative sea‐level rise in the carbonate factory. A low‐relief archipelago with an active tidal regime allowed the development of tide‐dominated siliciclastic and carbonate environments on the vast platform. Siliciclastic input to these tidal environments terminated when most of the archipelago became submerged due to a rapid rise in sea‐level. This study provides insights on how a vast Cambrian carbonate platform maintained synchronous sedimentation under a tidal regime, forming distinct cycles of mixed carbonates and siliciclastics as the system kept up with rising relative sea‐level during the early stage of basin development in the North China Platform.  相似文献   

The interannual variability of megafaunal assemblages in the Arctic deep sea: Preliminary results from the HAUSGARTEN observatory (79°N)     

M. Bergmann  T. SoltwedelM. Klages 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(6):711-723

Although megafaunal organisms play an important role in deep benthic ecosystems and contribute significantly to benthic biomass in the Arctic little is known about their temporal dynamics. Here, we assessed the interannual dynamics of megafaunal organisms from the HAUSGARTEN observatory in the Fram Strait, an area where the effects of climatic forcing are particularly evident. We analysed three congruent camera transects taken in 2002, 2004 and 2007. Environmental parameters were measured in order to be able to put our faunal results into an environmental context.Our results indicate that although the densities of megafaunal species show different patterns over time, most exhibit an overall decrease between 2002 and 2007 and total megafaunal densities decreased regularly from 2002 to 2004 to 2007 (12.16±0.96 to 7.41±0.43 ind m⁻²). This concurs with a steady increase in bottom-water temperatures and a decrease in the total organic content and microbial biomass of surficial sediments at the same time period. Although suspension feeder densities also decreased, predator/scavenger and deposit feeder densities have declined to such an extent that suspension feeders accounted for almost 100% of the megafauna in 2007. It could thus be argued that the trophic diversity at the central HAUSGARTEN station (2500 m) has decreased. Temperature-related changes in the production of the surface layers may lead to changes in the quality and/or quantity of particles exported to the deep seafloor. The densities of deposit feeders (i.e. holothurians) peaked (1.14±0.13 ind m⁻²) in 2004, the year following the longest ice cover. These results indicate the importance of ice-related export of particles to the deep seafloor and highlight the need for time-series transects, especially in an era when productive marginal ice zones tend to disappear with the receding sea ice. Although there is a general consensus that the Arctic is in a transition towards a warmer state, only continued observation will allow us to assess if the interannual changes observed are a result of decadal cycles related to the Arctic and North Atlantic Oscillation or if they are indicators of long-term change.  相似文献   

基于生物资源的万山海洋牧场生境适宜性评估     

初建松  郑卫东  孙利元  彭道民  索安宁  朱玉贵 《海洋科学》2024,48(1):75-84

万山群岛海域生态环境日益恶化、渔业资源持续衰退,因此建设万山群岛海洋牧场,修复海域生态环境、实现渔业资源可持续利用迫在眉睫。针对现阶段基于海洋生物资源的海洋牧场适宜性评估的研究较少,本研究利用渔业资源调查和全球物种数据库记录数据及13个环境因素数据,采用物种分布模型MaxEnt对选择的白姑鱼、日本金线鱼、红星梭子蟹和浅缝骨螺潜在分布区进行预测,探讨海洋生物地理分布与海洋环境因素之间的关系进而进行万山海洋牧场生境适宜性评估,结果表明:(1)各模型AUC值均大于0.9,说明构建的模型对这些物种潜在分布的模拟效果较好,后续可采用MaxEnt模型对4种生物的栖息地分布区进行预测;(2)海底浮游植物密度、海底温度以及海底硅酸盐浓度是影响这4种海洋生物栖息地分布的关键环境因子;(3)基于该4种海洋物种MaxEnt模型的HSI分布区所存在重叠区域来看,海洋牧场拟建设区域应为纬度21.85°N~22.15°N,经度113.6°E~114.2°E。研究结果可为万山海洋牧场规划和建设提供科学依据。  相似文献   

HYDROCHEMISTRY AS AN INDICATOR OF SUBGLACIAL DRAINAGE SYSTEM STRUCTURE: A COMPARISON OF ALPINE AND SUB-POLAR ENVIRONMENTS     

MARTYN TRANTER  GILES H. BROWN  ANDREW J. HODSON  ANGELA M. GURNELL 《水文研究》1996,10(4):541-556

The anion compositions (SO²₄, HCO⁻₃ and Cl⁻) of runoff from the Haut Glacier d'Arolla, Switzerland and Austre Brøggerbreen, Svalbard are compared to assess whether or not variations in water chemistry with discharge are consistent with current understanding of the subglacial drainage structure of warm- and polythermal-based glaciers. These glacial catchments have very different bedrocks and the subglacial drainage structures are also believed to be different, yet the range of anion concentrations show considerable overlap for SO²⁻₄ and HCO⁻₃. Concentrations of Cl⁻ are higher at Austre Brøggerbreen because of the maritime location of the glacier. Correcting SO²⁻₄ for the snowpack component reveals that the variation in non-snowpack SO²⁻₄ with discharge and with HCO⁻₃ is similar to that observed at the Haut Glacier d'Arolla. Hence, if we assume that the provenance of the non-snowpack SO²⁻₄ is the same in both glacial drainage systems, a distributed drainage system also contributes to runoff at Austre Brøggerbreen. We have no independent means of testing the assumption at present. The lower concentrations of non-snowpack SO²⁻₄ at Austre Brøggerbreen may suggest that a smaller proportion of runoff originates from a distributed drainage system than at the Haut Glacier d'Arolla.  相似文献   

Mechanisms of collapse of the cretaceous helvetiafjellet formation at Kvalvågen,eastern Spitsbergen     

Nate Onderdonk  Ivar Midtkandal 《Marine and Petroleum Geology》2010

Coastal cliffs at Kvalvågen, eastern Spitsbergen, expose palaeolandslide blocks and related slope failure features that record local collapse of an otherwise undisturbed succession of paralic sediments. The collapse occurred along a shallow sloping shelf at the edge of an epicontinental sea in the Early Cretaceous. The event was coincident with a rise in relative sea level along a coast that had just previously experienced a major paralic regression across a muddy marine environment. The low relief environment in which the slope failure structures formed, as well as the timing of the collapse raise questions regarding the cause of the topographic instability and the possible influence of sea level changes or tectonic activity. These outcrops have been previously interpreted as the collapse of a deltaic system triggered by local seismic activity or collapse of a shelf break in the headwall regions of submarine canyons. This paper presents new structural and stratigraphic data that refine and adjust the previous interpretations through the evaluation of a variety of possible mechanisms for collapse based on the new data. Our data suggest that active delta deposition was not occurring at Kvalvågen at the time of collapse and that the collapse was likely due to allogenic forcing. Despite the possible influence of pore fluids and rheological controls on the collapse, we find that the geometry and kinematics of landslide slip planes, synsedimentary folds, and other slope failure related features require over-steepened topography and that these are most consistent with westward-directed collapse off of a north striking escarpment with elevated topography on the east side. Fault exposures, a large contrast in palaeo-elevation, and liquifaction features support previous interpretations of a tectonic cause for the collapse and suggest that this topographic feature may have been a fault or fold scarp. This study demonstrates the importance of combining stratigraphic and sedimentological data with structural data and kinematic analysis in the interpretation of sedimentary processes.  相似文献   

长山群岛海洋渔业资源的平均营养级变化特征     

孙才志  曹威威  肖春柳 《海洋通报》2019,38(1):87-95

根据长山群岛 1965-2016 年渔业统计资料,分析长山群岛海域主要捕捞渔获物产量、平均营养级 （Mean trophic level, MTL）、渔业均衡指数 （Fishing in balance index,FiB） 年际变化,探讨其海洋渔业资源利用状况,并利用小波分析方法研究52年来渔获物 MTL 周期变化特征。研究表明： （1） 长山群岛捕捞产量、MTL 和 FiB 指数呈阶段性变化; （2） 长山群岛渔业资源开发经历初期开发、扩张捕捞、过度捕捞、资源破坏等四个阶段,渔业资源环境正在逐渐恶化;（3） 受人类捕捞活动影响,MTL 在 15~19 年和 24~34 年两种时间尺度下呈周期波动,30 年为第一主周期,17 年为第二主周期。长山群岛渔业资源破坏日益严重,未来几年平均营养级将呈下降趋势。为防止渔业资源进一步衰退,应加强捕捞活动管理力度,落实海洋渔业资源保护制度;完善预警机制,构建海洋渔业资源监测系统;同时应积极调整长山群岛渔业产业结构,提高资源产出效率.  相似文献