Ecological responses to climate change in a bird-impacted High Arctic pond (Nordaustlandet,Svalbard)

A 28-cm sediment core from an Arctic pond (Nordaustlandet, Svalbard), which is currently subjected to the fertilizing effect of bird guano, was analysed for fossil invertebrates and the physical properties of the sediment. The objective was to examine aquatic community responses to climate warming. Our record reveals that faunal changes have occurred. Initially chironomid assemblages were dominated by a cold-indicating oligotrophic community but this was replaced by a community typical of more nutrient-enriched conditions and warmer water temperature at around AD 1,700–1,800. After AD 1,800, ostracods and Daphnia increase suggesting that a nutrient enrichment threshold was crossed, probably related to increased planktonic algal productivity. In the early twentieth century, organic content markedly increases and magnetic susceptibility values suddenly drop, indicating a further increase in nutrient input and lake productivity. Since the most likely source of nutrients in the lake is goose guano, this suggests that the size of the bird colony may also have increased over this period. These changes coincide with climate warming suggesting a positive feedback in which climate change is the primary driver of the increasing geese abundance and lake productivity. Our results further suggest that the predicted future warming in the Arctic will continue to have cascading effects on freshwater ecosystems in the region.     

Vegetation development and carbon storage on a glacier foreland in the High Arctic, Ny-Ålesund, Svalbard

The distribution of organic carbon and its relationship to vegetation development were examined on a glacier foreland near Ny-Ålesund, Svalbard (79°N). In a 0.72-km² area, we established 43 study plots on three line transects along primary succession from recently deglaciated area to old well-vegetated area. At each plot, we measured the type and percent coverage of vegetation types. The organic carbon content of vegetation, organic soil, and mineral soil samples was determined based on their organic carbon concentration and bulk density. Cluster analysis based on vegetation coverage revealed five types of ground surfaces representing variations in the amounts and allocation patterns of organic carbon. In the later stages of succession, 7%–24% and 31%–40% of organic carbon was contained in the organic and deeper soil layers, respectively. Organic carbon storage in the later stages of succession ranged from 1.1 – 7.9 kg C m⁻². A larger amount of organic carbon, including ancient carbon in a raised beach deposit, was expected to be contained in much deeper soil layers. These results suggest that both vegetation development and geological history affect ecosystem carbon storage and that a non-negligible amount of organic carbon is distributed in this High Arctic glacier foreland.     

Characteristics of ion concentrations in snowpits in Longyearbyen, Svalbard, Arctic

１ＩｎｔｒｏｄｕｃｔｉｏｎＳｔｕｄｉｅｓｏｎｃｈｅｍｉｃａｌｃｈａｒａｃｔｅｒｉｓｔｉｃｓｉｎｓｎｏｗｐｉｔａｒｅｖｅｒｙｉｍｐｏｒｔａｎｔｉｎｒｅｓｅａｒｃｈｏｆｍｏｄｅｒｎｐｒｏｃｅｓｅｓｉｎｓｎｏｗａｎｄｉｃｅ,ｗｈｉｃｈｉｓｂａｓｉｃｃｏｎｔ...     

Protracted Active Surge Phase in the High Arctic (Svalbard): Dynamic Development and Morphological Impact

Glacial surges in Svalbard are protracted and characterized by individual dynamic evolution, in contrast to many other areas, which calls for a subdivision of the classic two‐phased surge cycle. A dominating part of the ice masses seem to have a surge potential and this represents a considerable challenge for palaeoclimatic studies. Glaciological and geological models therefore need to be coupled. The issue is discussed with Fridtjovbreen glacier as an example. This ice mass is one of few glaciers studied throughout a surge cycle. It was active for 12 years (1991–2002) and represents the most protracted surge documented. The maximum advance rate was 4.2 m day^?1, its maximum extent was reached after seven years, its run‐out distance was 4 km, and the relocated ice filled 5 km² of the fjord. Intense subglacial thrusting occurred during various stages, including part of the ice‐front retreat, as shown by sub‐bottom profiling data from 2002. A six‐stage model is presented and processes are discussed with emphasis on the ice‐front retreat with transition to the quiescent phase. Although the surge mechanism itself is unrelated to climate, climatic conditions obviously play a major role in the course of a surge. During the surge, the ice mass made a dramatic impression in the landscape, but 10 years after the maximum extent, there is little onshore evidence of the event.     

Distribution and Autecology of Chrysophyte Cysts from High Arctic Svalbard Lakes: Preliminary Evidence of Recent Environmental Change

Chrysophycean stomatocyst assemblages were analysed from the sediments of 17 lakes and ponds from Svalbard as one component of a multi-proxy investigation of recent environmental change in the high Arctic. Sediment cores and water chemistry were collected from each of the study lakes, and chrysophyte stomatocysts were investigated from the top 0.25 cm of sediment (present-day) and bottom (i.e., bottom of short sediment core, pre-industrial) sediment samples. This study represents the first undertaking of chrysophyte cyst morphology and distribution on Svalbard. A total of 153 cyst morphotypes were described with light microscopy and/or scanning electron microscopy, of which 21 are new forms. Canonical correspondence analysis indicates that the present-day distribution of cysts is significantly related to pH (p= 0.02), altitude (p= 0.02), and Na⁺ (p= 0.04). Marked shifts in chrysophyte cyst assemblages were recorded between the top and bottom sediment samples of most lakes. A recent study has demonstrated that Svalbard lakes receive atmospheric contaminants from both local and remote sources. The observed assemblage shifts may be the result of the combined effects of these point sources and long-range pollutants, or the effects of recent climate change, or both.     

Estimation of the annual primary production of the lichen Cetrariella delisei in a glacier foreland in the High Arctic, Ny-Ålesund, Svalbard

The fruticose lichen Cetrariella delisei is among the dominant lichen species in the deglaciated High Arctic areas of Svalbard. As part of a study of carbon cycling in the High Arctic, we aimed to estimate the primary production of lichen in a deglaciated area in Ny-Ålesund, Svalbard (79° N), by examining the effects of abiotic factors on the net photosynthesis ( Pn ) and dark respiration ( R ) rates of C. delisei . Experiments were conducted in the snow-free season of 2000 using an open-flow gas exchange system with an infrared gas analyser. Positive photosynthetic activities were observed on rainy days or soon after rainfall when the thallus water content was high, whereas photosynthetic activities dropped below the detectable limit on clear days because of the low thallus water content. Under a sufficiently high thallus water content and close to light saturation, Pn was nearly constant over a wide temperature range of 4–20 °C, while R increased with increasing temperature. We constructed a model for estimating the net primary production ( NPP ) of lichen based on the relationships between abiotic factors and the CO₂ exchange rate. The mean, minimum and maximum NPP values in the snow-free season, estimated using meteorological data obtained from 1995–2003, were 5.1, 1.0 and 8.4 g dry wt. m⁻² snow-free season⁻¹, respectively. These results suggest that NPP is highly variable and the contribution of lichen to carbon input is small compared with that of vascular plants and mosses in the study site.     

A comparison of climatic change between Svalbard in Arctic and the Qinghai Tibetan Plateau

ＡｃｏｍｐａｒｉｓｏｎｏｆｃｌｉｍａｔｉｃｃｈａｎｇｅｂｅｔｗｅｅｎＳｖａｌｂａｒｄｉｎＡｒｃｔｉｃａｎｄｔｈｅＱｉｎｇｈａｉ┐ＴｉｂｅｔａｎＰｌａｔｅａｕＫａｎｇＳｈｉｃｈａｎｇ（康世昌）,ＹａｏＴａｎｄｏｎｇ（姚檀栋）ａｎｄＱｉｎＤａｈｅ（秦大河...     

Arctic Ocean manganese contents and sediment colour cycles

Cyclical variations in colour and manganese content in sediments from the central Arctic Ocean have been interpreted to represent climatically controlled changes in the input of Mn from the Siberian hinterland, and/or variations in the intermediate and deep water ventilation of the Arctic basins, although a diagenetic origin has not been excluded. A reinvestigation of core 96/12-1pc using an Itrax X-ray fluoresence (XRF) core scanner confirms that these colour cycles are indeed controlled by variations in Mn content, although changes in the source region of the sediment may override the Mn colour signal in certain intervals. The prominent Mn cycles show no correspondence to any of the other measured elements. This decoupling of Mn and the bulk chemistry of the sediment is taken to indicate that the cycles observed are caused by variations in water column ventilation and riverine input, rather than variations in sediment source or diagenesis. We therefore conclude that the Mn maxima do represent warm phases with increased ventilation and/or riverine input, and that they therefore could be used for chronostratigraphic correlation between cores from the central Arctic Ocean, where traditional isotope stratigraphy is difficult or impossible to establish because of the lack of calcareous microfossils.     

Impact of the Arctic Fox Alopex lagopus on nesting success of geese in southeast Svalbard, 1989

Goose populations, with special emphasis on Light-bellied Brent Geese Branta bernicla hrota , were censured in Tusenøyane and Tjuvfjorden, southeast Svalbard, July-August 1989. A total of 425 non-breeding Brent Geese, 210 Barnacle Geese Branta leucopsis and 421 Pink-footed Geese Anser bra-chyrhynchus and 11, 2 and 3 families of the three species, respectively, were counted. Brent Geese attempted to nest on 6 of the 20 islands surveyed, and were successful on four. Barnacle Geese attempted to nest on three islands and were successful on two. Many islands known to be traditional nesting sites were entirely void of geese. Pink-footed Geese were only seen in Tjuvfjorden. The breeding failure on the islands was linked to the presence of the Arctic Fox Alopex lagopus which probably caused the geese to completely give up the attempt to nest. On one island the fox had apparently arrived after nest initiation and ravaged 45 Brent Goose and Barnacle Goose nests. It is likely that the foxes stranded on the islands during ice break-up. As a consequence of the presence of foxes on most of Tusenøyane, more than half of the potential breeding segment of the Svalbard Brent Goose population failed to nest in the summer of 1989.     

Changes in The Dynamics And Thermal Regime of The Permafrost and Active Layer of The High Arctic Coastal Area in North‐West Spitsbergen,Svalbard

In this paper changes in the active layer of the high arctic coastal area in north‐west Spitsbergen, Svalbard are described. Analysis includes both the ground thawing depth and its near‐surface thermal structure. The study was conducted on the Kaffiøyra Plain (Svalbard) at several fixed sites, which represent places typical of the region: a sandy beach, a tundra plain and a moraine ridge. The results show that in recent years, at two measurement points a significantly deeper thawing was observed. In 1996–2012 on the beach and on the moraine the trend of active layer thickness change was +1.3 cm yr^?1 and +2.5 cm yr^?1, respectively. Generally, in the years 2008–2012 the mean thickness of the active layer in the Kaffiøyra region increased by 3% to 6%. Even at the spatially close sites, within similar environments, there are significant differences in the thickness of the active layer. Measurements show that significant changes also occurred in the thawed ground temperature. Mean values of the observed near‐surface temperature in recent years (2007–2011) were higher by more than 1.0°C, in comparison to the mean in the late 1970s.     

Reconceptualising coarse sediment delivery problems in rivers as catchment-scale and diffuse

This paper assesses river channel management activities in the context of the interaction between coarse sediment delivery, climate change, river channel response and flood risk. It uses two main sources of evidence: (1) an intensive instrumentation of an upland river catchment using both traditional hydrometric and novel sediment sensing methods; and (2) a sediment delivery model that combines a treatment of sediment generation from mass failure with a treatment of the connectivity of this failed material to the drainage network. The field instrumentation suggests that the precipitation events that deliver sediment from hillslopes to the drainage network are different to those that transfer sediment within the network itself. Extreme events, that could occur at any time in the year (i.e. they are not dependent on wet antecedent conditions), were crucial for sediment delivery. However, sustained high river flows were responsible for the majority of transfer within the river itself. Application of three downscaling methods to climate model predictions for the 2050s and 2080s suggested a significant increase in the number and potential volume of delivery events by the 2050s, regardless of the climate downscaling scenario used. First approximations suggested that this would translate into annual bed level aggradation rates of between 0.10 and 0.20 m per year in the downstream main channel reaches. Second, the importance of this delivery for flood risk studies was confirmed by simulating the effects of 16 months of measured in-channel simulation with river flows scaled for climate change to the 2050s and 2080s. Short-term sedimentation could result in similar magnitude increases in inundated area for 1 in 0.5 and 1 in 2 year floods to those predicted for the 2050s in relation to increases in flow magnitude. Finally, we were able to develop an alternative approach to river management in relation to coarse sediment delivery, based upon reducing the rates of coarse sediment delivery through highly localised woodland planting, under the assumption that reducing delivery rates should reduce the rate of channel migration and hence the magnitude of the bank erosion problem. Thus, the paper demonstrates the need to conceptualise local river management problems in upland river environments as point scale manifestations of a diffuse sediment delivery process, with a much more explicit focus on the catchment scale, if our river systems are to become more insulated from the impacts of future climate changes.     

River sediment supply, sedimentation and transport of the highly turbid sediment plume in Malindi Bay, Kenya

The paper presents results of a study on the sediment supply and movement of highly turbid sediment plume within Malindi Bay in the Northern region of the Kenya coast. The current velocities, tidal elevation, salinity and suspended sediment concentrations (TSSC) were measured in stations located within the bay using Aanderaa Recording Current Meter (RCM-9), Turbidity Sensor mounted on RCM-9, Divers Gauges and Aanderaa Temperature-Salinity Meter. The study established that Malindi Bay receives a high terrigenous sediment load amounting to 5.7 × 10⁶ ton·yr^?1. The river freshwater supply into the bay is highly variable ranging from 7 to 680 m³·s^?1. The high flows that are > 150 m³·s^?1 occurred in May during the South East Monsoon (SEM). Relatively low peak flows occurred in November during the North East Monsoon (NEM) but these were usually <70 m³·s^?1. The discharge of highly turbidity river water into the bay in April and May occurs in a period of high intensity SEM winds that generate strong north flowing current that transports the river sediment plume northward. However, during the NEM, the river supply of turbid water is relatively low occurring in a period of relatively low intensity NEM winds that result in relatively weaker south flowing current that transports the sediment plume southward. The mechanism of advection of the sediment plume north or south of the estuary is mainly thought to be due to the Ekman transport generated by the onshore monsoon winds. Limited movement of the river sediment plume southward towards Ras Vasco Da Gama during NEM has ensured that the coral reef ecosystem in the northern parts of Malindi Marine National Park has not been completely destroyed by the influx of terrigenous sediments. However, to the north there is no coral reef ecosystem. The high sediment discharge into Malindi Bay can be attributed to land use change in the Athi-Sabaki River Basin in addition to rapid population increase which has led to clearance of forests to open land for agriculture, livestock grazing and settlement. The problems of heavy siltation in the bay can be addressed by implementing effective soil conservation programmes in the Athi-Sabaki Basin. However, the soil conservation programmes in the basin are yet to succeed due to widespread poverty among the inhabitants and the complications brought about by climate change.     

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

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.     

Petrochemistry of Jurassic and Cretaceous tholeiites from Kong Karls Land, Svalbard, and their relation to Mesozoic magmatism in the Arctic

A study of the whole-rock geochemistry and mineral chemistry of high-TiO₂ Upper Jurassic and medium-TiO₂ Lower Cretaceous basalts from Kong Karls Land, Svalbard, is presented. Geochemical criteria indicate that the basalts are initial rifting tholeiites with weak signs of crustal contamination. The Upper Jurassic basalts appear to be associated with the Olga Rift, part of a trans-Barents rift system which failed to link the proto-Atlantic and proto-Arctic basins. The Lower Cretaceous basalts may be more closely related to initial rifting tholeiites on Franz Josef Land and Spitsbergen generated during the rifting stage of opening of the Canada Basin. During break-up of the Barents Shelf, the sequence of magma types corresponds to the pre-, syn- and post-rifting stages established in other areas of continental break-up. Evidence for a possible hot-spot or plume trail, extending from Siberia to the Yermak Plateau over 250 Ma, is assembled.     

北极斯瓦尔巴群岛冰川流域可培养细菌的系统发育多样性及固氮菌初步研究

从北极斯瓦尔巴群岛冰川流域的上、中、下游采集了5种代表性土壤和冰川融水样品(MT、AT、TN、BT、MS),采用常规LB和严格无氮培养基低温培养方法,对其中的可培养细菌和潜在固氮细菌进行了总菌计数以及菌株的富集、分离与纯化。经菌落菌体形态观察、16S r RNA基因初步测序排重、固氮基因nif H的PCR检测,分别选取48株可培养分离细菌和31株潜在固氮菌进行了基于16S r RNA基因全序列测定的系统发育分析。目的是初步了解该特殊生境中可培养细菌(包括潜在固氮菌)的多样性及其分布状况,为进一步研究它们在此生境中的生态功能奠定基础。实验结果表明,可培养细菌在5个采集样品中的总菌数为BTTNATMT=MS,严格无氮培养基分离菌总菌数为BTATMTTNMS。48株可培养代表菌分属于Proteobacteria、Actinobacteria、Bacteroidetes、Firmicutes 4个门的7纲、14属之中,它们在5个样品中的多样性程度为BT(6纲、6属)MT(4纲、6属)AT、MS(均为3纲、3属)TN(2纲、3属),优势菌群主要分布在γ-proteobacteria纲的Pseudomonas属(20.8%,集中在AT、BT、MS样品中)和β-proteobacteria纲的Janthinobacterium属(35.4%,集中在MS样品中),表现出一定程度的系统发育多样性。潜在固氮菌实验结果表明,能在严格无氮培养基上生长且可检测到nif H的31株代表菌具有极为单一的系统发育多样性。其中90.32%菌株集中在γ-proteobacteria纲的Pseudomonas属,仅在MT和MS样品中有3株菌分布在α-proteobacteria纲的Rhizobium属、β-proteobacteria纲的Janthinobacterium属和Actinobacteria纲的Arthrobacter属,它们与分离自其他极端环境的相关标准菌株具有高度16S r RNA基因同源性。另外,本实验还发现有8株菌的16S r RNA基因序列与相关标准菌株的相似度低于98.50%,推测它们具有成为该特殊生境下新种的潜质。     

Sediment discharge variability in Arctic rivers: implications for a warmer future

A new model for predicting the sediment flux in ungauged river basins is applied to 46 Arctic to sub-Arctic rivers. The model predicts the preanthropogenic flux of sediment to within a factor of 2, across four orders of magnitude in basin area and run-off. The model explains for the first time why Arctic rivers carry so little sediment when compared at the global scale. Sensitive to drainage basin temperature, the model is used to examine the impact of a climate warming scenario on the loads of high latitude rivers. As the Arctic warms, rivers will carry increased sediment loads, similar to more temperate rivers. For every 2°C warming, the model predicts a 22% increase in the flux of sediment carried by rivers. For every 20% increase in water discharge there will be a 10% increase in sediment load. The model also aids the interpretation of palaeoclimate records obtained from Arctic continental margins.     

稳态风沙流中瞬态输沙特征

风沙流中沙粒运动在来流风速不变时也会表现出非稳态特征。在风洞内利用粒子图像测速系统（PIV）测量了风沙运动的时间序列,并基于PIV测量技术提出风沙流中沙粒平均直径、数密度、平均水平速度和输沙通量等参数在某一时刻的计算方法,其中输沙通量的计算考虑沙粒大小垂向分布的影响。结果表明：来流风速不变时,沙粒平均直径、数密度、平均水平速度和输沙通量随时间具有明显的波动性;沙粒平均直径和平均水平速度的标准偏差一般随高度增加而增加,沙粒数密度和输沙通量标准偏差随高度增大而减小;这些参数的相对标准偏差均随高度增加而增大。