Science.gov

Sample records for alter alpine lake

  1. Recent climate extremes alter alpine lake ecosystems

    PubMed Central

    Parker, Brian R.; Vinebrooke, Rolf D.; Schindler, David W.

    2008-01-01

    Here, we show that alpine lake ecosystems are responsive to interannual variation in climate, based on long-term limnological and meteorological data from the Canadian Rockies. In the 2000s, in years with colder winter temperatures, higher winter snowfall, later snowmelt, shorter ice-free seasons, and dryer summers, relative to the 1990s, alpine lakes became clearer, warmer, and mixed to deeper depths. Further, lakes became more dilute and nutrient-poor, the latter leading to significant declines in total phytoplankton biomass. However, increased concentrations of dissolved organic carbon in lake water stimulated the appearance of small mixotrophic algal species, partially offsetting the decline in autotrophic phytoplankton biomass and increasing algal species richness. The climate regime in the 2000s altered the physical, chemical, and biological character and the function of high-elevation aquatic ecosystems. Forecasts of increased climatic variability in the future pose serious ramifications for both the biodiversity and ecosystem function of high-elevation lakes. PMID:18725641

  2. Resistance and resilience of alpine lake fauna to fish introductions

    Treesearch

    R.A. Knapp; K.R. Matthews; O. Sarnelle

    2001-01-01

    Abstract. This paper reports on the response by amphibians, benthic macroinvertebrates, and zooplankton in naturally fishless alpine lakes to fish introductions and subsequent fish disappearance. We assessed resistance (the degree to which a system is altered when the environment changes) by comparing faunal distribution and abundance in lakes that have never been...

  3. The potential for retreating alpine glaciers to alter alpine ecosystems in the Colorado Front Range

    NASA Astrophysics Data System (ADS)

    Hall, E.; Baron, J.

    2013-12-01

    Glaciers are retreating at an unprecedented rate. In mid-latitude alpine ecosystems the presence of glaciers and rock glaciers govern rates and ecology of alpine and sub-alpine ecosystems. Changes in the thermal environment due to the loss of isothermal habitat and inputs from glacier melt chemistry are altering alpine ecosystems in unpredictable ways. In particular, glacier may be a source of nitrogen that is altering alpine ecosystem dynamics. Loch Vale Watershed (LVWS) located within Rocky Mountain National Park. LVWS contains a surface glacier (Andrew's glacier) and a rock glacier (Taylor's glacier) at the headwater of each of the two drainages within the watershed. We collected precipitation from a National Atmospheric Deposition Site and surface water from multiple alpine lakes and streams during a particularly high and low snow year in the Colorado Front Range. We also sampled stream and lake sediments at each site to analyze the associated microbial community. Concentrations of nitrate and ammonium, relative abundance of amoA (the gene responsible for a key step in the microbial nitrification pathway), and the dual isotope signal to nitrate all point to snow melt as a key deliverer of nitrogen to ecosystems along the Colorado Front Range. However, late summer surface water chemistry is isotopically similar to the chemistry of glacial ice. This suggests that retreating glacier may be an additional source of N to alpine ecosystems and have the potential to alter microbial community composition, biogeochemical rate processes, and ecosystem function. These dynamics are most likely not unique to the Colorado Front Range and should be globally distributed as glaciers continue to retreat in high altitude ecosystems around the world.

  4. ALPINE LAKES WILDERNESS STUDY AREA, WASHINGTON.

    USGS Publications Warehouse

    Gualtieri, J.L.; Thurber, H.K.

    1984-01-01

    The Alpine Lakes Wilderness study area, located in the central part of the Cascade Mountains of Washington was examined for its mineral-resource potential. On the basis of that study the area was found to contain deposits of copper, other base metals, and gold and silver. Probable or substantiated mineral-resource potential exists for these commodities in the southwest-central, northwest, and southeast-central parts of the area. The geologic terrane precludes the occurrence of fossil fuel resources.

  5. Melting Alpine glaciers enrich high-elevation lakes with reactive nitrogen.

    PubMed

    Saros, Jasmine E; Rose, Kevin C; Clow, David W; Stephens, Verlin C; Nurse, Andrea B; Arnett, Heather A; Stone, Jeffery R; Williamson, Craig E; Wolfe, Alexander P

    2010-07-01

    Alpine glaciers have receded substantially over the last century in many regions of the world. Resulting changes in glacial runoff not only affect the hydrological cycle, but can also alter the physical (i.e., turbidity from glacial flour) and biogeochemical properties of downstream ecosystems. Here we compare nutrient concentrations, transparency gradients, algal biomass, and fossil diatom species richness in two sets of high-elevation lakes: those fed by snowpack melt alone (SF lakes) and those fed by both glacial and snowpack meltwaters (GSF lakes). We found that nitrate (NO(3)(-)) concentrations in the GSF lakes were 1-2 orders of magnitude higher than in SF lakes. Although nitrogen (N) limitation is common in alpine lakes, algal biomass was lower in highly N-enriched GSF lakes than in the N-poor SF lakes. Contrary to expectations, GSF lakes were more transparent than SF lakes to ultraviolet and equally transparent to photosynthetically active radiation. Sediment diatom assemblages had lower taxonomic richness in the GSF lakes, a feature that has persisted over the last century. Our results demonstrate that the presence of glaciers on alpine watersheds more strongly influences NO(3)(-)concentrations in high-elevation lake ecosystems than any other geomorphic or biogeographic characteristic.

  6. Agriculture causes nitrate fertilization of remote alpine lakes

    NASA Astrophysics Data System (ADS)

    Hundey, E. J.; Russell, S. D.; Longstaffe, F. J.; Moser, K. A.

    2016-02-01

    Humans have altered Earth's nitrogen cycle so dramatically that reactive nitrogen (Nr) has doubled. This has increased Nr in aquatic ecosystems, which can lead to reduced water quality and ecosystem health. Apportioning sources of Nr to specific ecosystems, however, continues to be challenging, despite this knowledge being critical for mitigation and protection of water resources. Here we use Δ17O, δ18O and δ15N from Uinta Mountain (Utah, USA) snow, inflow and lake nitrate in combination with a Bayesian-based stable isotope mixing model, to show that at least 70% of nitrates in aquatic systems are anthropogenic and arrive via the atmosphere. Moreover, agricultural activities, specifically nitrate- and ammonium-based fertilizer use, are contributing most (~60%) Nr, and data from other North American alpine lakes suggest this is a widespread phenomenon. Our findings offer a pathway towards more effective mitigation, but point to challenges in balancing food production with protection of important water resources.

  7. Agriculture causes nitrate fertilization of remote alpine lakes

    PubMed Central

    Hundey, E. J.; Russell, S. D.; Longstaffe, F. J.; Moser, K. A.

    2016-01-01

    Humans have altered Earth's nitrogen cycle so dramatically that reactive nitrogen (Nr) has doubled. This has increased Nr in aquatic ecosystems, which can lead to reduced water quality and ecosystem health. Apportioning sources of Nr to specific ecosystems, however, continues to be challenging, despite this knowledge being critical for mitigation and protection of water resources. Here we use Δ17O, δ18O and δ15N from Uinta Mountain (Utah, USA) snow, inflow and lake nitrate in combination with a Bayesian-based stable isotope mixing model, to show that at least 70% of nitrates in aquatic systems are anthropogenic and arrive via the atmosphere. Moreover, agricultural activities, specifically nitrate- and ammonium-based fertilizer use, are contributing most (∼60%) Nr, and data from other North American alpine lakes suggest this is a widespread phenomenon. Our findings offer a pathway towards more effective mitigation, but point to challenges in balancing food production with protection of important water resources. PMID:26853267

  8. Alpine Lake Phytoplankton Responses to the 2002 Drought in Colorado

    NASA Astrophysics Data System (ADS)

    Flanagan, C. M.

    2005-05-01

    Because the hydrologic regime of alpine catchments is dominated by snow melt, their terrestrial and aquatic ecosystems are extremely sensitive to physical and climatic fluctuations in the amount of snow and timing of snowmelt. The drought of 2002 in Colorado was the most extreme drought of the past 100 years of record for the state. Measured at the outflow of Green Lake 4, an alpine lake in Green Lake Valley, located within the Niwot Ridge Long Term Ecological Research (LTER) site in the Front Range of Colorado, the 2002 drought resulted in snowmelt discharge that was just 60% of recent historical averages for stream discharge. We examined how the drought affected the phytoplankton population in this alpine lake. Algal biomass was quantified and samples for community composition analysis were collected during the summers of 2000, 2001 and 2002. The results of the statistical comparison indicate a significant increase in total density of algal cells, possibly caused by drought-induced factors such as earlier ice-out and hence higher irradiance, higher hydraulic residence time and lower wash-outs, plus higher surface water temperatures. Species in three divisions, Bacillariophyta, Chlorophyta and Cyanophyta, showed significant responses. A principal components analysis confirmed a shift in the community composition during the drought. Although based on only three seasons of monitoring data, these results may foreshadow climate change and implicate subsequent biological effects in high altitude watersheds.

  9. Differences in UV transparency and thermal structure between alpine and subalpine lakes: implications for organisms†

    PubMed Central

    Rose, Kevin C.; Williamson, Craig E.; Saros, Jasmine E.; Sommaruga, Ruben; Fischer, Janet M.

    2010-01-01

    Ultraviolet (UV) radiation is a globally important abiotic factor influencing ecosystem structure and function in multiple ways. While UV radiation can be damaging to most organisms, several factors act to reduce UV exposure of organisms in aquatic ecosystems, the most important of which is dissolved organic carbon (DOC). In alpine lakes, very low concentrations of DOC and a thinner atmosphere lead to unusually high UV exposure levels. These high UV levels combine with low temperatures to provide a fundamentally different vertical structure to alpine lake ecosystems in comparison to most lowland lakes. Here, we discuss the importance of water temperature and UV transparency in structuring alpine lake ecosystems and the consequences for aquatic organisms that inhabit them. We present transparency data on a global data set of alpine lakes and nearby analogous subalpine lakes for comparison. We also present seasonal transparency data on a suite of alpine and subalpine lakes that demonstrate important differences in UV and photosynthetically active radiation (PAR, 400–700 nm) transparency patterns even within a single region. These data are used to explore factors regulating transparency in alpine lakes, to discuss implications of future environmental change on the structure and function of alpine lakes, and ways in which the UV transparency of these lakes can be used as a sentinel of environmental change. PMID:19707613

  10. Water quality of two glacial alpine Italian lakes.

    PubMed

    Zelano, Vincenzo; Zambrotta, Maria; Defilippi, Albino; Torazzo, Annamaria

    2005-01-01

    The purpose of this study was to characterize, in a period of one year, two glacial lakes, Alice and Meugliano, located in an alpine reservoir on the basis of physical and chemical features. The two lakes show two periods of mixing: one in the spring and one in the autumn, so can be classified as dimictic lakes. They are characterized by pH, alkalinity, low conductivity and and quite dilute ionic concentrations. With regard to nutrients, most nitrogen occurred in the nitric form in the superficial layers. During the period of thermal stratification, in the anoxic layer NO3- decreases and NH4+ increases, confirming the activity of the anaerobic denitrificant bacteria. Total and soluble phosphorus levels show homogeneity during the cold period at different depths, while with stratification concentrations increase in the hypolimnium and metalimnium. In both lakes there is an inverse correlation between transparency and chlorophyll a. To evaluate the trophic state the conventional criteria of Nurnberg 2 and four lake trophic indices (TSIs) are used. Both evaluations suggest that the two lakes are eutrophic, with worse conditions in Alice. Deviations of the trophic states, based on the relation between TSIs, indicate that factors other than phosphorous limit the algal biomass, and that non-algal particles influence light attenuation

  11. Preliminary evaluation of lake susceptibility to water-quality degradation by recreational use, Alpine Lakes Wilderness Area, Washington

    USGS Publications Warehouse

    Gilliom, Robert J.; Dethier, D.P.; Safioles, S.A.; Heller, P.L.

    1980-01-01

    The relative susceptibility of lakes in the Alpine Lakes Wilderness Area to water-quality degradation was evaluated from two perspectives: (1) water-quality sensitivity, which is the tendency of a lake 's water quality to degrade in response to pollutant loading, and (2) pollutant-loading likelihood, which is determined by the presence of drainage-basin features that enhance the transport of pollutants to a lake. Water-quality sensitivity was evaluated for 60 lakes, using a mass-balance phosphorus model to predict the response of each lake to a hypothetical ' worst-case ' increase in phosphorus loading. This evaluation suggested that lakes in the Alpine Lakes Wilderness Area generally are not sensitive to foreseeable increases in phosphorus loading because of their high rate of dilution and flushing. Pollutant-loading likelihood was evaluated according to the amount of seasonal ' wet area ' near a lake and in the drainage basin. Of 298 lakes evaluated for pollutant-loading likelihood, 74 lakes were rated moderate to high. On the basis of these findings, lakes in the Alpine Lakes Wilderness Area are generally not considered susceptible to long-term degradation as a result of recreational use, but some lakes are probably susceptible to temporary local pollution. The nature of this potential problem, and knowledge of natural features of the Alpine Lakes Wilderness Area, suggest an approach for managing recreation so that the risk of water-quality degradation is minimized. (USGS)

  12. Small lakes in big landscape: Multi-scale drivers of littoral ecosystem in alpine lakes.

    PubMed

    Zaharescu, Dragos G; Burghelea, Carmen I; Hooda, Peter S; Lester, Richard N; Palanca-Soler, Antonio

    2016-05-01

    In low nutrient alpine lakes, the littoral zone is the most productive part of the ecosystem, and it is a biodiversity hotspot. It is not entirely clear how the scale and physical heterogeneity of surrounding catchment, its ecological composition, and larger landscape gradients work together to sustain littoral communities. A total of 113 alpine lakes from the central Pyrenees were surveyed to evaluate the functional connectivity between littoral zoobenthos and landscape physical and ecological elements at geographical, catchment and local scales, and to ascertain how they affect the formation of littoral communities. At each lake, the zoobenthic composition was assessed together with geolocation, catchment hydrodynamics, geomorphology and topography, riparian vegetation composition, the presence of trout and frogs, water pH and conductivity. Multidimensional fuzzy set models integrating benthic biota and environmental variables revealed that at geographical scale, longitude unexpectedly surpassed altitude and latitude in its effect on littoral ecosystem. This reflects a sharp transition between Atlantic and Mediterranean climates and suggests a potentially high horizontal vulnerability to climate change. Topography (controlling catchment type, snow coverage and lakes connectivity) was the most influential catchment-scale driver, followed by hydrodynamics (waterbody size, type and volume of inflow/outflow). Locally, riparian plant composition significantly related to littoral community structure, richness and diversity. These variables, directly and indirectly, create habitats for aquatic and terrestrial stages of invertebrates, and control nutrient and water cycles. Three benthic associations characterised distinct lakes. Vertebrate predation, water conductivity and pH had no major influence on littoral taxa. This work provides exhaustive information from relatively pristine sites, and unveils a strong connection between littoral ecosystem and catchment

  13. Evaluation of storage and filtration protocols for alpine/subalpine lake water quality samples

    Treesearch

    John L. Korfmacher; Robert C. Musselman

    2007-01-01

    Many government agencies and other organizations sample natural alpine and subalpine surface waters using varying protocols for sample storage and filtration. Simplification of protocols would be beneficial if it could be shown that sample quality is unaffected. In this study, samples collected from low ionic strength waters in alpine and subalpine lake inlets...

  14. Nonnative trout impact an alpine-nesting bird by altering aquatic-insect subsidies.

    PubMed

    Epanchin, Peter N; Knapp, Roland A; Lawler, Sharon P

    2010-08-01

    Adjacent food webs may be linked by cross-boundary subsidies: more-productive donor systems can subsidize consumers in less-productive neighboring recipient systems. Introduced species are known to have direct effects on organisms within invaded communities. However, few studies have addressed the indirect effects of nonnative species in donor systems on organisms in recipient systems. We studied the direct role of introduced trout in altering a lake-derived resource subsidy and their indirect effects in altering a passerine bird's response to that subsidy. We compared the abundance of aquatic insects and foraging Gray-crowned Rosy-Finches (Leucosticte tephrocotis dawsoni, "Rosy-Finch") at fish-containing vs. fishless lakes in the Sierra Nevada Mountains of California (USA). Introduced trout outcompeted Rosy-Finches for emerging aquatic insects (i.e., mayflies). Fish-containing lakes had 98% fewer mayflies than did fishless lakes. In lakes without fish, Rosy-Finches showed an aggregative response to emerging aquatic insects with 5.9 times more Rosy-Finches at fishless lakes than at fish-containing lakes. Therefore, the introduction of nonnative fish into the donor system reduced both the magnitude of the resource subsidy and the strength of cross-boundary trophic interactions. Importantly, the timing of the subsidy occurs when Rosy-Finches feed their young. If Rosy-Finches rely on aquatic-insect subsidies to fledge their young, reductions in the subsidy by introduced trout may have decreased Rosy-Finch abundances from historic levels. We recommend that terrestrial recipients of aquatic subsidies be included in conservation and restoration plans for ecosystems with alpine lakes.

  15. Hypsometry and the distribution of high-alpine lakes in the European Alps

    NASA Astrophysics Data System (ADS)

    Prasicek, Günther; Otto, Jan-Christoph; Buckel, Johannes; Keuschnig, Markus

    2017-04-01

    Climate change strongly affects alpine landscapes. Cold-climate processes shape the terrain in a typical way and ice-free overdeepenings in cirques and glacial valleys as well as different types of moraines favor the formation of lakes. These water bodies act as sediment sinks and high-alpine water storage but may also favor outburst and flooding events. Glacier retreat worldwide is associated with an increasing number and size of high-alpine lakes which implies a concurrent expansion of sediment retention and natural hazard potential. Rising temperatures are regarded to be the major cause for this development, but other factors such as the distribution of area over elevation and glacier erosional and depositional dynamics may play an important role as well. While models of ice flow and glacial erosion are employed to understand the impact of glaciers on mountain landscapes, comprehensive datasets and analyses on the distribution of existing high-alpine lakes are lacking. In this study we present an exhaustive database of natural lakes in the European Alps and analyze lake distribution with respect to hypsometry. We find that the distribution of lake number and lake area over elevation only weakly coincides with hypsometry. Unsurprisingly, largest lakes are often tectonically influenced and located at the fringe of the mountain range and in prominent inter-montane basins. With increasing elevation, however, the number of lakes, lake area and total area decrease until a local minimum is reached around the equilibrium line latitude (ELA) of the last glacial maximum (LGM). Above the LGM ELA, total area further decreases, but lake number and area increase again. A local maximum in lake area coincides with an absolute maximum in lake number between the ELAs of the LGM and the little ice age around 2500 m. We conclude that glacial erosional and depositional dynamics control the distribution and size of high-alpine lakes and thus demand for exceptional attention when

  16. Shifts in alpine lakes' ecosystems in Japan driven by increasing Asian dusts

    NASA Astrophysics Data System (ADS)

    Tsugeki, N. K.; Tani, Y.; Ueda, S.; Agusa, T.; Toyoda, K.; Kuwae, M.; Oda, H.; Tanabe, S.; Urabe, J.

    2011-12-01

    Recently in East Asia the amount of fossil fuel combustion have increased with economic growth. It has caused a problem of trans-boundary air pollution in the whole of eastern Asia. Furthermore, Asian dust storms contribute episodically to the global aerosol load. However, the effects of increased Asian dusts on aquatic ecosystems are not well understood. If biologically important nutrients such as nitrogen (N) and phosphorus (P) are transported via air dust, the atmospheric deposition of the dust may have serious impacts on recipient aquatic ecosystems because the biological production is limited by these nutrient elements. A previous report using sedimentary records has evaluated that atmospheric P inputs to the alpine lakes in the United States increased fivefold following the increased western settlement to this country during the nineteenth century. Since P is the most deficient nutrient for production in many lakes increase in P loading through atmospheric deposition of anthropogenically-derived dust might greatly affect the lake ecosystems. We examined fossil pigments and zooplankton remains from Pb-dated sediments taken from a high mountain lake of Hourai-Numa, located in the Towada-Hachimantai National Park of Japan, to uncover historical changes in the phyto- and zooplankton community over the past 100 years. Simultaneously, we measured the biogeochemical variables of TOC, TN, TP, δ13C, δ15N, and 206Pb/207Pb, 208Pb/207Pb in the sediments to identify environmental factors causing such changes. As a result, despite little anthropogenic activities in the watersheds, alpine lakes in Japan Islands increased algal and herbivore plankton biomasses by 3-6 folds for recent years depending on terrestrial the surrounded vegetations and landscape conditions. Biological and biogeochemical proxies recorded in the lake sediments indicate that this eutrophication occurred after the 1990s when P deposition increased due to atmospheric loading transported from Asian

  17. Dust inputs and bacteria influence dissolved organic matter in clear alpine lakes

    PubMed Central

    Mladenov, N.; Sommaruga, R.; Morales-Baquero, R.; Laurion, I.; Camarero, L.; Diéguez, M.C.; Camacho, A.; Delgado, A.; Torres, O.; Chen, Z.; Felip, M.; Reche, I.

    2011-01-01

    Remote lakes are usually unaffected by direct human influence, yet they receive inputs of atmospheric pollutants, dust, and other aerosols, both inorganic and organic. In remote, alpine lakes, these atmospheric inputs may influence the pool of dissolved organic matter, a critical constituent for the biogeochemical functioning of aquatic ecosystems. Here, to assess this influence, we evaluate factors related to aerosol deposition, climate, catchment properties, and microbial constituents in a global dataset of 86 alpine and polar lakes. We show significant latitudinal trends in dissolved organic matter quantity and quality, and uncover new evidence that this geographic pattern is influenced by dust deposition, flux of incident ultraviolet radiation, and bacterial processing. Our results suggest that changes in land use and climate that result in increasing dust flux, ultraviolet radiation, and air temperature may act to shift the optical quality of dissolved organic matter in clear, alpine lakes. PMID:21792184

  18. Reconstructing geomorphic patterns and forcing factors from Alpine Lake Sediment

    NASA Astrophysics Data System (ADS)

    Arnaud, Fabien; Poulenard, Jérôme; Giguet-Covex, Charline; Wilhelm, Bruno; Révillon, Sidonie; Jenny, Jean-Philippe; Revel, Marie; Enters, Dirk; Bajard, Manon; Fouinat, Laurent; Doyen, Elise; Simonneau, Anaëlle; Pignol, Cécile; Chapron, Emmanuel; Vannière, Boris; Sabatier, Pierre

    2017-04-01

    In this paper we review the scientific efforts that were led over the last decades to reconstruct geomorphic patterns from continuous alpine lake sediment records. Whereas our results point a growing importance of humans as erosion forcing factors, we will focus here on climate-related processes. Our main dataset is made of a regional approach which was led without any a priori regarding erosion forcing factors. We hence integrated a set of sediment sequences from various environment along an altitudinal gradient from 200 up to 2400m asl in Northern French Alps. Altogether our data point climate change as one of the main factor of erosion variability. In particular, the last two cold spells that occurred during the early middle age (Dark Age) and between the 14th and the 20th century AD (Little Ice Age) appear to be outstanding compared to any other periods of enhanced erosion along the Holocene. The climatic forcing of those erosion phases is supported by an increase in the contribution of glacier-eroded material at a regional scale. At local scales, our data also point the growing importance, since at least the mid Bronze Age (ca. 3500 cal. BP) of human activities as a major erosion factor. This influence peaked during the late Iron Age and Antiquity periods (200 BC - 400 AD) when we record a regional generalised period of enhanced erosion in response to the development of pasturing activities. Thanks to provenance and weathering markers, we evidenced a strong relationship between the changes in ecosystems, soil development and erosion patterns. We hence showed the vegetal colonisation of bared soil led to a period of intense weathering while new soils were under formation between 11,000 and 8,000 cal. BP. Soils then knew an optimum until the onset of the Neoglacial at ca. 4,500 cal. BP prior to decline under both climate and human pressures. Altogether our data point the complexity of processes that affected the Earth critical zone along the Holocene. However

  19. THE CHALLENGE OF ACQUIRING ALPINE LARGE VOLUME LAKE WATER SAMPLES FOR ULTRA TRACE LEVEL ANALYSIS

    EPA Science Inventory

    The National Exposure Research Laboratory-Las Vegas, Nevada is interested in the emerging field technology of in-situ extraction of contaminants from surface water. A current research project involves ultra-trace level determination of agricultural pesticides from alpine lakes. T...

  20. Alpine glacier-fed turbid lakes are discontinuous cold polymictic rather than dimictic

    PubMed Central

    Peter, Hannes; Sommaruga, Ruben

    2017-01-01

    Abstract Glacier retreat as a consequence of climate change influences freshwater ecosystems in manifold ways, yet the physical and chemical bases of these effects are poorly studied. Here, we characterize how water temperature differs between alpine lakes with and without direct glacier influence on seasonal and diurnal timescales. Using high temporal resolution monitoring of temperature in 4 lakes located in a catchment influenced by glacier retreat, we reported unexpectedly high surface temperatures, even in proglacial lakes located 2600 m a.s.l. Cold glacier meltwater and low nighttime air temperatures caused a distinct diurnal pattern of water temperature in the water column of glacier-influenced lakes. Precipitation onto glacier surfaces apparently leads to rapid cooling of the glacier-fed lakes and disrupts the thermal stratification with several mixing events during the summer. Taken together, these mechanisms contribute to the unique seasonal and diurnal dynamics of glacier-influenced lakes that contrast with the typical dimictic pattern of clear alpine lakes and represent an example of discontinuous cold polymictic lake type. This work contributes to the basic description of how climate and meteorology affect the physical properties of an increasingly common lake type. PMID:28690780

  1. Alpine Channel and Floodplain Dynamics in the Lake Tahoe Region, California

    NASA Astrophysics Data System (ADS)

    Liquori, M.; Chris, B.; Parris, A.; Heins, A.; Stofleth, J.; Wickland, M.

    2006-12-01

    Alpine floodplains provide diverse habitat components for terrestrial and aquatic species, and strongly influence bank stability and channel migration processes. They also present complex restoration challenges. Several systems in the Lake Tahoe region have been diagnosed with incised channel conditions that generate excessive mobile sediment from eroding banks, degrade riparian vegetation communities, and diminish floodplain wetland abundance and quality. Conventional efforts to restore these systems focus on reconnecting floodplains, primarily through channel or floodplain modifications designed to reestablish floodplain inundation frequency near a Q1.5 level. Recent observations along lower Squaw Creek and the Upper Truckee River suggest that human impacts and climate-induced shifts over the 20th Century appear to significantly change the processes and dynamics between channels and floodplains. Our observations highlight differences in alpine settings as compared with lowland environments. Increased rain-on-snow frequency appears to increase the importance of avulsion and channel widening processes over channel meander processes. Loss of channel sinuosity, increases in depth and changes in channel shape appear to follow rain-on-snow events. These changes affect the overall sediment transport regime, even as snowmelt duration continues to exert the primary influence over dominant discharge relationships. During floods, discontinuous, proximal deposition of coarse sediment replaces uniform, distal deposition of finer sediments, altering the structure of the channel bed and floodplain. Early snowmelt from developed hillslopes saturates floodplains even in the absence of regular flooding, potentially negating or eliminating the restorative benefit of increased flood frequency. These results suggest that effective long-term restoration strategies cannot rely on historic sinuosity patterns or simple flood frequency metrics, but must begin to understand how changes in

  2. Catchment-mediated atmospheric nitrogen deposition drives ecological change in two alpine lakes in SE Tibet.

    PubMed

    Hu, Zhujun; Anderson, Nicholas John; Yang, Xiangdong; McGowan, Suzanne

    2014-05-01

    The south-east margin of Tibet is highly sensitive to global environmental change pressures, in particular, high contemporary reactive nitrogen (Nr) deposition rates (ca. 40 kg ha(-1)  yr(-1) ), but the extent and timescale of recent ecological change is not well prescribed. Multiproxy analyses (diatoms, pigments and geochemistry) of (210) Pb-dated sediment cores from two alpine lakes in Sichuan were used to assess whether they have undergone ecological change comparable to those in Europe and North America over the last two centuries. The study lakes have contrasting catchment-to-lake ratios and vegetation cover: Shade Co has a relatively larger catchment and denser alpine shrub than Moon Lake. Both lakes exhibited unambiguous increasing production since the late 19th to early 20th. Principle component analysis was used to summarize the trends of diatom and pigment data after the little ice age (LIA). There was strong linear change in biological proxies at both lakes, which were not consistent with regional temperature, suggesting that climate is not the primary driver of ecological change. The multiproxy analysis indicated an indirect ecological response to Nr deposition at Shade Co mediated through catchment processes since ca. 1930, while ecological change at Moon Lake started earlier (ca. 1880) and was more directly related to Nr deposition (depleted δ(15) N). The only pronounced climate effect was evidenced by changes during the LIA when photoautotrophic groups shifted dramatically at Shade Co (a 4-fold increase in lutein concentration) and planktonic diatom abundance declined at both sites because of longer ice cover. The substantial increases in aquatic production over the last ca. 100 years required a substantial nutrient subsidy and the geochemical data point to a major role for Nr deposition although dust cannot be excluded. The study also highlights the importance of lake and catchment morphology for determining the response of alpine lakes to

  3. The Impact of UV Radiation on Paramecium Populations from Alpine Lakes.

    PubMed

    Kammerlander, Barbara; Tartarotti, Barbara; Sonntag, Bettina

    2017-08-21

    Paramecium populations from a clear and a glacier-fed turbid alpine lake were exposed to solar simulated ultraviolet (UVR) and photosynthetically active radiation (PAR) at 8 and 15 °C. The ciliates were tested for DNA damage (comet assay), behavioral changes, and mortality after UVR + PAR exposure. High DNA damage levels (~58% tail DNA) and abnormal swimming behavior were observed, although no significant changes in cell numbers were found irrespective of the lake origin (clear, turbid), and temperatures. We conclude that environmental stressors such as UVR and their effects may influence the adaptation of ciliates living in alpine lakes. © 2017 The Author(s) Journal of Eukaryotic Microbiology published by Wiley Periodicals, Inc. on behalf of International Society of Protistologists.

  4. Satellite monitoring of dramatic changes at Hawai'i's only alpine lake: Lake Waiau on Mauna Kea volcano

    USGS Publications Warehouse

    Patrick, Matthew R.; Kauahikaua, James P.

    2015-01-01

    Lake Waiau is a small, typically 100-meter-long lake, located near the summit of Mauna Kea volcano, on the Island of Hawaiʻi. It is Hawaiʻi’s only alpine lake and is considered sacred in Hawaiian cultural tradition. Over the past few years, the lake has diminished in size, and, by October 2013, surface water had almost completely disappeared from the lake. In this study, we use high-resolution satellite images and aerial photographs to document recent changes at the lake. Based on our reconstructions covering the past 200 years, the historical lake surface area has typically ranged from 5,000 to 7,000 square meters, but in 2010 a dramatic plunge in lake area ensued. The lake area rebounded significantly in early 2014, following heavy winter storms. This near disappearance of the lake, judging from analysis of visitor photographs and field reports, appears to be highly unusual, if not unprecedented, in the historical record. The unusually low water levels in the lake are consistent with a recent severe drought in Hawaiʻi.

  5. Scalable Climate Forcing Optical Indices: How Effective Are They in Alpine Lakes?

    NASA Astrophysics Data System (ADS)

    Williamson, C. E.; Overholt, E.; Fischer, J.; Olson, M.; Brentrup, J.; Saros, J. E.; Melack, J. M.

    2014-12-01

    As the world gets warmer and wetter, it is important to identify sentinel systems to resolve the response of ecosystems to climate change across drivers and complex landscapes. Recently developed climate forcing optical indices (CFOI) related to the quality and quantity of dissolved organic carbon (DOC) have been shown to be scalable from short-term storm events to interdecadal periods in diverse lakes in lowland landscapes. Are these CFOI metrics effective in alpine ecosystems, which are often viewed as more responsive sentinels of climate change than lowland ecosystems? DOC-related optical data from a series of alpine lakes in North America are used here to address this question. The response of these CFOI metrics followed the same tight relationship in alpine lakes as in lowland lakes, with a seasonal increase in spectral slope between 275 and 295 nm (S275-295) and a decrease in DOC-specific absorbance at 320 nm (a*320) as well as in the ratio of these two indices (a*320/S275-295, a composite climate forcing index, CF). These changes are likely driven largely by photobleaching of terrestrial DOC during the ice-free season. Closer analysis of five years of data for Lake Oesa in the Canadian Rockies revealed marginally significant relationships between precipitation and the CFOI metrics. Specifically, S275-295 decreased with increasing cumulative precipitation for the 15 day period preceding water sample collection. a*320 increased with cumulative precipitation for the 45 day period preceding water sample collection. Relationships between CFOI metrics and precipitation at other time scales were not significant. While the DOC-quality related CFOI metrics were responsive to precipitation, DOC concentration alone was not. The time scale of precipitation effects on CFOI metrics in Lake Oesa was shorter than those previously observed for lowland lakes. This contrasting response is likely related to differences in the characteristics of the hydrology and catchments of

  6. UV-induced DNA damage in Cyclops abyssorum tatricus populations from clear and turbid alpine lakes

    PubMed Central

    Tartarotti, Barbara; Saul, Nadine; Chakrabarti, Shumon; Trattner, Florian; Steinberg, Christian E. W.; Sommaruga, Ruben

    2014-01-01

    Zooplankton from clear alpine lakes thrive under high levels of solar UV radiation (UVR), but in glacially turbid ones they are more protected from this damaging radiation. Here, we present results from experiments done with Cyclops abyssorum tatricus to assess UV-induced DNA damage and repair processes using the comet assay. Copepods were collected from three alpine lakes of differing UV transparency ranging from clear to glacially turbid, and exposed to artificial UVR. In addition, photoprotection levels [mycosporine-like amino acids (MAAs) and lipophilic antioxidant capacity] were estimated in the test populations. Similar UV-induced DNA damage levels were observed among the copepods from all lakes, but background DNA damage (time zero and dark controls) was lowest in the copepods from the glacially turbid lake, resulting in a higher relative DNA damage accumulation. Most DNA strand breaks were repaired after recovery in the dark. Low MAA concentrations were found in the copepods from the glacially turbid lake, while the highest levels were observed in the population from the most UV transparent lake. However, the highest lipophilic antioxidant capacities were measured in the copepods from the lake with intermediate UV transparency. Photoprotection and the ability to repair DNA damage, and consequently reducing UV-induced damage, are part of the response mechanisms in zooplankton to changes in water transparency caused by glacier retreat. PMID:24616551

  7. Photochemical reactivities of dissolved organic matter (DOM) in a sub-alpine lake revealed by EEM-PARAFAC: An insight into the fate of allochthonous DOM in alpine lakes affected by climate change.

    PubMed

    Du, Yingxun; Zhang, Yuanyuan; Chen, Feizhou; Chang, Yuguang; Liu, Zhengwen

    2016-10-15

    Due to climate change, tree line advance is occurring in many alpine regions. Within the next 50 to 100years, alpine lake catchments are expected to develop increased vegetation cover similar to that of sub-alpine lake catchments which currently exist below the tree line. Such changes in vegetation could trigger increased allochthonous DOM inputs to alpine lakes. To understand the fate of allochthonous DOM in alpine lakes impacted by climate change, the photochemical reactivity of DOM in sub-alpine Lake Tiancai (located 200m below the tree line) was investigated by excitation emission matrix fluorescence combined with parallel factor analysis (EEM-PARAFAC) and UV-Vis spectra analysis. With photo-exposure, a decrease in apparent DOM molecular weight was observed and 32% DOM was photomineralized to CO2. Interestingly, the aromaticity of DOM increased after photodegradation, as evidenced by increases in both the specific UV absorbance at 254nm (SUVA254) and the humification index (HIX). Five EEM-PARAFAC components were identified, including four terrestrially-derived substances (C1, C2, C3 and C4; allochthonous) and one tryptophan-like substance (C5; autochthonous). Generally, allochthonous DOM represented by C2 and C3 exhibited greater photoreactivity than autochthonous DOM represented by C5. C4 was identified as a possible photoproduct with relatively high aromaticity and photorefractive tendencies and contributed to the observed increase in SUVA254 and HIX. UV light facilitated the photodegradation of DOM and had the greatest effect on the removal of C3. This study provides information on the transformation of EEM-PARAFAC components in a sub-alpine lake, which is important in understanding the fate of increased allochthonous DOM inputs to alpine lakes impacted by climate change. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Are lake sediments mere archives of degraded organic matter? - evidence of rapid biotic changes tracked in sediments of pre-alpine Lake Lunz, Austria

    NASA Astrophysics Data System (ADS)

    Hollaus, Lisa-Maria; Khan, Samiullah; Schelker, Jakob; Ejarque, Elisabet; Battin, Tom; Kainz, Martin

    2016-04-01

    Lake sediments are used as sentinels of changes in organic matter composition and dynamics within lakes and their catchments. In an effort to investigate how past and recent hydrological extreme events have affected organic matter composition in lake sediments, we investigated the biogeochemical composition of sediment cores and settling particles, using sediment traps in the pre-alpine, oligotrophic Lake Lunz, Austria. We assessed annual sedimentation rates using 137Cs and 210Pb, time integrated loads of settling particles, analyze stable carbon (δ13C) and nitrogen (δ15N) isotopes to track changes of carbon sources and trophic compositions, respectively, and use source-specific fatty acids as indicators of allochthonous, bacterial, and algal-derived organic matter. Preliminary results indicate that settling particles of Lake Lunz (33 m depth) contain high algae-derived organic matter, as assessed by long-chain polyunsaturated fatty acids (LC-PUFA), indicating low degradation of such labile organic matter within the water column of this lake. However, LC-PUFA decreased rapidly in sediment cores below the sediment-water interface. Concentrations of phosphorous remained stable throughout the sediment cores (40 cm), suggesting that past changes in climatic forcing did not alter the load of this limiting nutrient in lakes. Ongoing work reveals dramatic biotic changes within the top layers of the sediment cores as evidenced by high numbers of small-bodied cladocerans (e.g., Bosmina) and large-bodied zooplankton (e.g., Daphnia) are only detected at lower sediment layers. Current research on these lake sediments is aimed at investigating how organic matter sources changed during the past century as a result of recorded weather changes.

  9. Promise and Pitfalls of Using Grain Size Analysis to Identify Glacial Sediments in Alpine Lake Cores.

    NASA Astrophysics Data System (ADS)

    Clark, D. H.

    2011-12-01

    Lakes fed by glacier outwash should have a clastic particle-size record distinct from non-glacial lakes in the same area, but do they? The unique turquoise color of alpine glacial lakes reflects the flux of suspended clastic glacial rock flour to those lakes; conversely, lakes not fed by outwash are generally clear with sediments dominated by organics or slope-wash from nearby hillslopes. This contrast in sediment types and sources should produce a distinct and measureable different in grain sizes between the two settings. Results from a variety of lakes suggest the actual situation is often more subtle and complex. I compare grain size results to other proxies to assess the value of grain size analysis for paleoglacier studies. Over the past 10 years, my colleagues and I have collected and analyzed sediment cores from a wide variety of lakes below small alpine glaciers in an attempt to constrain the timing and magnitude of alpine glaciation in those basins. The basic concept is that these lakes act as continuous catchments for any rock flour produced upstream by glacier abrasion; as a glacier grows, the flux of rock flour to the lake will also increase. If the glacier disappears entirely, rock flour deposition will also cease in short order. We have focused our research in basins with simple sedimentologic settings: mostly small, high-altitude, stripped granitic or metamorphic cirques in which the cirque glaciers are the primary source of clastic sediments. In most cases, the lakes are fed by meltwater from a modern glacier, but were ice free during the earlier Holocene. In such cases, the lake cores should record formation of and changes in activity of the glacier upstream. We used a Malvern Mastersizer 2000 laser particle size analyzer for our grain size analyses, as well as recording magnetic susceptibility, color, and organics for the same cores. The results indicate that although lakes often experience increases in silt and clay-size (<0.63 mm) clastic

  10. Abundance, Activity, and Diversity of Ammonia-oxidizing Bacteria and Archaea in Oligotrophic Alpine Lakes of Yosemite National Park, California

    NASA Astrophysics Data System (ADS)

    Beman, J.; Hayden, C.

    2013-12-01

    Lakes play critical roles in biogeochemical cycles as integrators of carbon and nitrogen cycling across watersheds. They are also ';sentinels' that may be strongly affected by environmental change--yet the responses of lake biogeochemical processes are dictated by microbial communities that we still know little about. We quantified nitrification rates, carbon respiration rates, and the abundance and diversity of involved microbes, within lakes located along an elevational gradient in Yosemite National Park, USA. Temperature, atmospheric nitrogen (N) deposition, and exposure to UV all vary along this transect, allowing us to test how these variables may act together to influence microbial biogeochemical processes. We found surprisingly high abundances of ammonia-oxidizing bacteria (AOB)--despite low nutrient conditions and high light levels that may favor other organisms, and/or inhibit AOB. We also examined community composition and diversity of AOB and ammonia-oxidizjng archaea (AOA) using Illumina sequencing of 16S rRNA genes, and measured ammonia oxidation rates using 15N tracer. All of these data are indicative of active N cycling by a dynamic microbial community. In Yosemite and other wilderness areas, atmospheric N deposition supplies a critical nutrient that may alter naturally nutrient-poor ecosystems; in the Sierra Nevada, much of this deposition occurs in the form of ammonium, suggesting a key role for nitrification in converting deposited N into more mobile forms. Our data indicate that oligotrophic alpine lakes may be nitrification hotspots in Yosemite.

  11. Soil warming alters microbial substrate use in alpine soils.

    PubMed

    Streit, Kathrin; Hagedorn, Frank; Hiltbrunner, David; Portmann, Magdalena; Saurer, Matthias; Buchmann, Nina; Wild, Birgit; Richter, Andreas; Wipf, Sonja; Siegwolf, Rolf T W

    2014-04-01

    Will warming lead to an increased use of older soil organic carbon (SOC) by microbial communities, thereby inducing C losses from C-rich alpine soils? We studied soil microbial community composition, activity, and substrate use after 3 and 4 years of soil warming (+4 °C, 2007-2010) at the alpine treeline in Switzerland. The warming experiment was nested in a free air CO2 enrichment experiment using depleted (13)CO2 (δ(13)C = -30‰, 2001-2009). We traced this depleted (13)C label in phospholipid fatty acids (PLFA) of the organic layer (0-5 cm soil depth) and in C mineralized from root-free soils to distinguish substrate ages used by soil microorganisms: fixed before 2001 ('old'), from 2001 to 2009 ('new') or in 2010 ('recent'). Warming induced a sustained stimulation of soil respiration (+38%) without decline in mineralizable SOC. PLFA concentrations did not reveal changes in microbial community composition due to soil warming, but soil microbial metabolic activity was stimulated (+66%). Warming decreased the amount of new and recent C in the fungal biomarker 18:2ω6,9 and the amount of new C mineralized from root-free soils, implying a shift in microbial substrate use toward a greater use of old SOC. This shift in substrate use could indicate an imbalance between C inputs and outputs, which could eventually decrease SOC storage in this alpine ecosystem.

  12. Climate regulates alpine lake ice cover phenology and aquatic ecosystem structure

    USGS Publications Warehouse

    Preston, Daniel L.; Caine, Nel; McKnight, Diane M.; Williams, Mark W.; Hell, Katherina; Miller, Matthew P.; Hart, Sarah J.; Johnson, Pieter T.J.

    2016-01-01

    High-elevation aquatic ecosystems are highly vulnerable to climate change, yet relatively few records are available to characterize shifts in ecosystem structure or their underlying mechanisms. Using a long-term dataset on seven alpine lakes (3126 to 3620 m) in Colorado, USA, we show that ice-off dates have shifted seven days earlier over the past 33 years and that spring weather conditions – especially snowfall – drive yearly variation in ice-off timing. In the most well-studied lake, earlier ice-off associated with increases in water residence times, thermal stratification, ion concentrations, dissolved nitrogen, pH, and chlorophyll-a. Mechanistically, low spring snowfall and warm temperatures reduce summer stream flow (increasing lake residence times) but enhance melting of glacial and permafrost ice (increasing lake solute inputs). The observed links among hydrological, chemical, and biological responses to climate factors highlight the potential for major shifts in the functioning of alpine lakes due to forecasted climate change.

  13. Climate regulates alpine lake ice cover phenology and aquatic ecosystem structure

    NASA Astrophysics Data System (ADS)

    Preston, Daniel L.; Caine, Nel; McKnight, Diane M.; Williams, Mark W.; Hell, Katherina; Miller, Matthew P.; Hart, Sarah J.; Johnson, Pieter T. J.

    2016-05-01

    High-elevation aquatic ecosystems are highly vulnerable to climate change, yet relatively few records are available to characterize shifts in ecosystem structure or their underlying mechanisms. Using a long-term data set on seven alpine lakes (3126 to 3620 m) in Colorado, USA, we show that ice-off dates have shifted 7 days earlier over the past 33 years and that spring weather conditions—especially snowfall—drive yearly variation in ice-off timing. In the most well studied lake, earlier ice-off associated with increases in water residence times, thermal stratification, ion concentrations, dissolved nitrogen, pH, and chlorophyll a. Mechanistically, low spring snowfall and warm temperatures reduce summer stream flow (increasing lake residence times) but enhance melting of glacial and permafrost ice (increasing lake solute inputs). The observed links among hydrological, chemical, and biological responses to climate factors highlight the potential for major shifts in the functioning of alpine lakes due to forecasted climate change.

  14. Unexpected response of high Alpine Lake waters to climate warming.

    PubMed

    Thies, Hansjörg; Nickus, Ulrike; Mair, Volkmar; Tessadri, Richard; Tait, Danilo; Thaler, Bertha; Psenner, Roland

    2007-11-01

    Over the past two decades, we have observed a substantial rise in solute concentration at two remote high mountain lakes in catchments of metamorphic rocks in the European Alps. At Rasass See, the electrical conductivity increased 18-fold. Unexpectedly high nickel concentrations at Rasass See, which exceeded the limit in drinking water by more than 1 order of magnitude, cannot be related to catchment geology. We attribute these changes in lake water quality to solute release from the ice of an active rock glacier in the catchment as a response to climate warming. Similar processes occurred at the higher elevation lake Schwarzsee ob Sölden, where electrical conductivity has risen 3-fold during the past two decades.

  15. Fluorscence signatures of dissolved organic material in an alpine lake ecosystem: responses to interannual climate variation and nutrient cycling

    NASA Astrophysics Data System (ADS)

    McKnight, Diane; Olivier, Matt; Hell, Katherina

    2016-04-01

    During snowmelt alpine lakes receive lower concentrations of dissolved organic material (DOM) that originates from the surrounding watershed than sub-alpine and montane lakes at lower elevations. Alpine lakes also have a shorter ice-free period that constrains the summer season of phytoplankton growth. Nonetheless, previous study of the reactive transport and production of DOM in an alpine lake in the Colorado Front Range during snowmelt and the summer ice-free season has shown that changes in DOM sources and the influence of biogeochemical processes can be resolved using fluorescence spectroscopy. Here we examine inter-annual variations in DOM fluorescence signatures during the snowmelt and summer periods in comparison to records of climate, residence time and primary production in the lake during the summer. Our analysis shows that variation in chlorophyll a concentration is a driver for variations in the fluorescence index (FI), as well as for specific ultra-violet absorbance. This result supports the predictions from the previous reactive transport modeling. We also conducted mesocosm experiments with nutrient enrichment to explore the role of nitrogen and phosphorus availability in influencing the fluorescence signature of DOM in summer. These results suggest that monitoring of simple spectroscopic properties of DOM can provide a means to track the biogeochemical consequences for alpine lakes of "too much" summer as climate continues to change.

  16. 75 FR 13253 - Plan Revision for Lake Tahoe Basin Management Unit, Alpine, El Dorado, and Placer Counties, CA...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-19

    ... management plan (forest plan) and will also prepare an environmental impact statement (EIS) for this revised... Be Made The Lake Tahoe Basin Management Unit is preparing an EIS to revise the current forest plan... Forest Service Plan Revision for Lake Tahoe Basin Management Unit, Alpine, El Dorado, and Placer Counties...

  17. Predicted responses of arctic and alpine ecosystems to altered seasonality under climate change.

    PubMed

    Ernakovich, Jessica G; Hopping, Kelly A; Berdanier, Aaron B; Simpson, Rodney T; Kachergis, Emily J; Steltzer, Heidi; Wallenstein, Matthew D

    2014-10-01

    Global climate change is already having significant impacts on arctic and alpine ecosystems, and ongoing increases in temperature and altered precipitation patterns will affect the strong seasonal patterns that characterize these temperature-limited systems. The length of the potential growing season in these tundra environments is increasing due to warmer temperatures and earlier spring snow melt. Here, we compare current and projected climate and ecological data from 20 Northern Hemisphere sites to identify how seasonal changes in the physical environment due to climate change will alter the seasonality of arctic and alpine ecosystems. We find that although arctic and alpine ecosystems appear similar under historical climate conditions, climate change will lead to divergent responses, particularly in the spring and fall shoulder seasons. As seasonality changes in the Arctic, plants will advance the timing of spring phenological events, which could increase plant nutrient uptake, production, and ecosystem carbon (C) gain. In alpine regions, photoperiod will constrain spring plant phenology, limiting the extent to which the growing season can lengthen, especially if decreased water availability from earlier snow melt and warmer summer temperatures lead to earlier senescence. The result could be a shorter growing season with decreased production and increased nutrient loss. These contrasting alpine and arctic ecosystem responses will have cascading effects on ecosystems, affecting community structure, biotic interactions, and biogeochemistry.

  18. Granite weathering and the sensitivity of alpine lakes to acid deposition

    SciTech Connect

    Stauffer, R.E.

    1990-07-01

    Lake chemical data from the National Surface Water Survey (NSWS) were corrected for the effects of regional atmospheric deposition and then used to evaluate the role of weathering in supplying base cations, silica, sulfate, and alkalinity to surface waters in alpine vs. subalpine, and in glaciated vs. unglaciated granitic terrane of the western and southeastern US. Thermodynamic models, idealized reaction stoichiometry, and multivariate regression involving solutes and geographic variables indicate that irreversible weathering can largely account for lake chemistry. By contrast, relatively minor roles are played by reversible ion exchange in soils and sediments, terrestrial bioaccumulation, and transformation in lakes. The regional patterns in lake acidity components (NO{sub 3}, SO{sub 4}, DOC, CO{sub 2}), and statistical relationships between acidity and base cations demonstrate that rock weathering is limited by acid inputs in many alpine catchments prior to fall overturn. The empirical success of the Henriksen alkalinity model depends on a high Ca: Na weathering ration. The latter increase with increasing physical disturbance of the catchment (juvenility), hence under natural circumstances attains a maximum as a result of on-going or recent glaciation. The Henriksen model fails in geochemically old terrane, where cation losses accompanying silicate weathering attain steady state proportions.

  19. Recent dynamics of alpine lakes on the endorheic Changtang Plateau from multi-mission satellite data

    NASA Astrophysics Data System (ADS)

    Yang, Kehan; Yao, Fangfang; Wang, Jida; Luo, Jiancheng; Shen, Zhanfeng; Wang, Chao; Song, Chunqiao

    2017-09-01

    Monitoring of the alpine lakes on the endorheic Changtang Plateau is vitally important in understanding climate impacts on hydrological cycle. Existing studies have revealed an accelerated lake expansion on the Changtang Plateau during the 2000s compared with prior decades. However, the partial hiatus of recent Landsat archive affected the continuation of understanding the lake changes in the recent decade. Here we synergistically used imagery from Landsat and Huanjing satellites to enable a detailed monitoring of lake area dynamics on the Changtang Plateau. Our results present that lakes on the Changtang Plateau continued to expand at a rapid rate of 340.79 km2 yr-1 (1.06% yr-1, p < 0.05) from 2009 to 2014. Changes in endorheic (terminal) lakes contribute to 98% of the net expansion, suggesting that monitoring endorheic lake dynamics is of critical importance for understanding climate changes. Meanwhile, changes in saline lakes, which are mostly endorheic, account for 96% of the net expansion, implying that the proportion of freshwater storage on the Changtang Plateau is likely in decline. Rapid expansion occurred in both glacier-fed and non-glacier-fed lakes, with a rate of 224.94 km2 yr-1 (0.92% yr-1, p < 0.05) and 115.85 km2 yr-1 (1.47% yr-1, p = 0.08), respectively, indicating that glacier retreat alone may not fully explain the recent lake expansion. Intra-annual variations of the selected 24 large lakes fluctuated within 0.22-2.46% (in coefficient of variation) for glacier-fed lakes and 0.17-2.36% for non-glacier-fed lakes. Most of these lakes expanded during the unfrozen period (from May/June to October) and reached to their maximum extents in September or October. By spatially associating our revealed lake changes with climate variables, we observed that the recent lake expansion is more related to precipitation than to temperature, although future efforts are needed for a more comprehensive picture of the lake changing mechanisms.

  20. Diatom Community Changes in Five Sub-alpine Mountain Lakes in Northern California

    NASA Astrophysics Data System (ADS)

    Johnson, B.; Noble, P. J.; Howard, K.; Heyvaert, A.

    2012-12-01

    Sediment cores and/or phytoplankton sampling of five sub-alpine lakes within three northern California mountain ranges show a major shift in diatom phytoplankton communities over the past 20-60 years; however, specific causes of these changes are still under investigation. Diatom analysis of a 20-cm sediment core taken from Castle Lake, a meso-oligotrophic lake located on the eastern slope of the Klammath Mountains, shows the phytoplankton community shifted from being cyclotelloid-dominated to having a larger component of araphids beginning around 1997. In the lower 14 cm of the core, the phytoplankton are dominated by centric diatoms, including the Discostella stelligera-pseudostelligera group (>50% of total diatoms), and the Cyclotella occelata-rossii-tripartita complex (9-18%). The top 6 cm show an increasing shift towards araphids, including Asterionella formosa and the Fragilaria tenera-nanana group, which is consistent with phytoplankton in the lake's epilimnion today. Fallen Leaf Lake (FLL), located at the southern end of the Lake Tahoe basin, has also undergone a similar shift. Presently, A. formosa, the F. tenera-nananna group, and Tabellaria dominate the phytoplankton. Examination of a sediment core from FLL indicates that A. formosa has been present in high abundances since at least 1812. The most prominent shift in the FLL diatom population began in the 1950s when the centric diatoms (eg. Aulacoseira subarctica) declined significantly in favor of araphids. The F. tenera-nanana group was present in trace amounts before 1812 and dramatically increased in abundance after the 1950s. Sediment accumulation rates have increased steadily since 1950 and coincide with increases in lake development and recreational use. A. formosa is also present today in Gilmore Lake, a minimally human-impacted lake located in the watershed above FLL, and in the heavily impacted Manzanita Lake in the northwestern corner of Lassen Volcanic National Park (LAVO) at the southern end

  1. Temperature impact on pH in sensitive high alpine lakes

    SciTech Connect

    Schmidt, R.; Koinig, K.A.; Psenner, R.

    1996-12-31

    Despite the attention given to lake acidification caused by anthropogenic emissions, the question of how climate change might influence the acid-base equilibria of lakes has rarely been explored. High altitude stations and inner alpine valleys are affected by precipitation with mineral acidity of 50 microequivalents per liter, thus exceeding the critical load in very sensitive watersheds. Paleolimnological data show that the acidity on soft-water, remote high altitude lakes situated on crystalline bedrock in the southern central Alps was correlated with regional temperature during the entire nineteenth century, colder years associated with lower pH, e.g., years which can be assigned to the so-called little ice-age. The onset of anthropogenic acid precipitation at the beginning of the present century led to a breakdown of the pH-temperature relationship, with pH dropping steadily to recent values.

  2. Importance of groundwater in the water balance of an alpine headwater lake

    NASA Astrophysics Data System (ADS)

    Hood, Jaime Lynn; Roy, James W.; Hayashi, Masaki

    2006-07-01

    The response of snow- and glacier-fed mountain streams and lakes to climate warming is of growing concern. A full understanding of these systems must include the role of groundwater, but this is poorly understood, especially for high-elevation lakes. This study addresses the role of groundwater in an alpine watershed, located at the continental divide of North America, with a focus on quantifying the groundwater exchange with Lake O'Hara in British Columbia, Canada. This is facilitated using a water balance approach and measurements of electrical conductivity in inflowing streams. The water balance indicates that groundwater inflow is substantial, as it was equivalent to at least 30-67% and 35-74% of the total outflow for the 2004 and 2005 field seasons, respectively. Hydrological and chemical data also suggest contributions from both deep and shallow groundwater flow paths.

  3. The transmission of the NAO signal to alpine lakes in the Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Sánchez, Guiomar; Hernández, Armand; Toro, Manuel; Granados, Ignacio; Sigró, Javier; Pla-Rabes, Sergi; Trigo, Ricardo; Jesús Rubio, María; Giralt, Santiago

    2014-05-01

    The North Atlantic Oscillation (NAO) is one of the main climate circulation patterns ruling winter rainfall and temperature in western Europe. In particular, the NAO pattern controls to a large extent the seasonal and inter-annual precipitation variability in the Iberian Peninsula (IP). Alpine lake ecosystems can be excellent records of NAO influence. They have been shown to respond significantly to local and regional climate variability dominated by large-scale climatic fluctuations, including the NAO. Physical lake parameters seem to reflect these meteorological forcing more immediately and sensitively than other lacustrine ones (i.e biological parameters). Specifically, ice phenology has become one of the most valuable indicators of NAO winter influence. Many studies carried out in lakes located in Northern Hemisphere have in common to find this transmission through air temperature. In addition, only few works have found a significant relationship between NAO signal and other climate variables, such as precipitation or snow. Conversely, to the best of our knowledge this kind of assessments have not been performed yet in Southern Europe. Two alpine lakes, with a glacial origin and located in the Spanish Central Range (IP) have been selected to perform a conceptual model of the transmission of NAO signal to lakes: Cimera (dimictic at 2140 m a.s.l., 384 m long, 177 m wide and 9.4 m deep) and Peñalara (monomictic at 2017 m a.s.l., 115 m long, 71.5 m wide and 4.8 m deep). This conceptual model has been built using Pearson's r correlation coefficients between winter season (December-March) data sets of NAO index, local meteorology (precipitation, temperature and snow days) and limnology (ice phenology records and lake water surface temperatures) available for the period 1993-2011 in Lake Peñalara and for the period 2007-2013 in Lake Cimera. The conceptual model results suggest that NAO winter signal is mainly reflected in ice phenology by air temperature but also by

  4. Seasonal inorganic nitrogen release in alpine lakes on the Colorado western slope

    USGS Publications Warehouse

    Inyan, B.I.; Williams, M.W.; Tonnessen, K.; Turk, J.T.; Campbell, D.H.

    1998-01-01

    In the Rocky Mountains, the association of increases in acidic deposition with increased atmospheric loading of sulfate and direct changes in surface water chemistry has been well established. The importance, though, of increased nitrogen (N) deposition in the episodic acidification of alpine lakes and N saturation in alpine ecosystems is only beginning to be documented. In alpine areas of the Colorado Front Range, modest loadings of N in deposition have been associated with leakage of N to surface waters. On the Colorado western slope, however, no leakage of N to surface waters has been reported. A 1995 study that included early season under-ice water samples that were not available in earlier studies showed that there is, in fact, N leakage to surface waters in some western slope basins. Under-ice nitrate (NO3-) concentrations were as high as 10.5 ??q L-1, and only decreased to detection limits in September. Landscape type appears to be important in leakage of N to surface waters, which is associated with basins having steep slopes, thin soils, and large amounts of exposed bedrock. NO3- leakage compounds the existing sensitivity to episodic acidification from low acid neutralizing capacity (ANC), which is less than 40 ??eq L-1 in those basins.

  5. Impact of internal waves on the spatial distribution of Planktothrix rubescens (cyanobacteria) in an alpine lake.

    PubMed

    Cuypers, Yannis; Vinçon-Leite, Brigitte; Groleau, Alexis; Tassin, Bruno; Humbert, Jean-François

    2011-04-01

    The vertical and horizontal distribution of the cyanobacterium, Planktothrix rubescens, was studied in a deep alpine lake (Lac du Bourget) in a 2-year monitoring program with 11 sampling points, and a 24-h survey at one sampling station. This species is known to proliferate in the metalimnic layer of numerous deep mesotrophic lakes in temperate areas, and also to produce hepatotoxins. When looking at the distribution of P. rubescens at the scale of the entire lake, we found large variations (up to 10  m) in the depth of the biomass peak in the water column. These variations were closely correlated to isotherm displacements. We also found significant variations in the distribution of the cyanobacterial biomass in the northern and southern parts of the lake. We used a physical modeling approach to demonstrate that two internal wave modes can explain these variations. Internal waves are generated by wind events, but can still be detected several days after the end of these events. Finally, our 24-h survey at one sampling point demonstrated that the V1H1 sinusoidal motion could evolve into nonlinear fronts. All these findings show that internal waves have a major impact on the distribution of P. rubescens proliferating in the metalimnic layer of a deep lake, and that this process could influence the growth of this species by a direct impact on light availability.

  6. Alpine Warming induced Nitrogen Export from Green Lakes Valley, Colorado Front Range, USA

    NASA Astrophysics Data System (ADS)

    Barnes, R. T.; Williams, M. W.; Parman, J.

    2012-12-01

    Alpine ecosystems are particularly susceptible to disturbance due to their short growing seasons, sparse vegetation and thin soils. Atmospheric nitrogen deposition and warming temperatures currently affect Green Lakes Valley (GLV) within the Colorado Front Range. Research conducted within the alpine links chronic nitrogen inputs to a suite of ecological impacts, resulting in increased nitrate export. According to NADP records at the site, the atmospheric flux of nitrogen has decreased by 0.56 kg ha-1 yr-1 since 2000, due to a decrease in precipitation. Concurrent with this decrease, alpine nitrate yields have continued to increase; by 32% relative to the previous decade (1990-1999). In order to determine the source(s) of the sustained nitrate increases we utilized long term datasets to construct a mass balance model for four stream segments (glacier to subalpine) for nitrogen and weathering product constituents. We also compared geochemical fingerprints of various solute sources (glacial meltwater, thawing permafrost, snow, and stream water) to alpine stream water to determine if sources had changed over time. Long term trends indicate that in addition to increases in nitrate; sulfate, calcium, and silica have also increased over the same period. The geochemical composition of thawing permafrost (as indicated by rock glacial meltwater) suggests it is the source of these weathering products. Mass balance results indicate the high ammonium loads within glacial meltwater are rapidly nitrified, contributing approximately 0.45 kg yr-1 to the NO3- flux within the upper reaches of the watershed. The sustained export of these solutes during dry, summer months is likely facilitated by thawing cryosphere providing hydraulic connectivity late into the growing season. In a neighboring catchment, lacking permafrost and glacial features, there were no long term weathering or nitrogen solute trends; providing further evidence that the changes in alpine chemistry in GLV are likely

  7. Flood frequency matters: Why climate change degrades deep-water quality of peri-alpine lakes

    NASA Astrophysics Data System (ADS)

    Fink, Gabriel; Wessels, Martin; Wüest, Alfred

    2016-09-01

    Sediment-laden riverine floods transport large quantities of dissolved oxygen into the receiving deep layers of lakes. Hence, the water quality of deep lakes is strongly influenced by the frequency of riverine floods. Although flood frequency reflects climate conditions, the effects of climate variability on the water quality of deep lakes is largely unknown. We quantified the effects of climate variability on the potential shifts in the flood regime of the Alpine Rhine, the main catchment of Lake Constance, and determined the intrusion depths of riverine density-driven underflows and the subsequent effects on water exchange rates in the lake. A simplified hydrodynamic underflow model was developed and validated with observed river inflow and underflow events. The model was implemented to estimate underflow statistics for different river inflow scenarios. Using this approach, we integrated present and possible future flood frequencies to underflow occurrences and intrusion depths in Lake Constance. The results indicate that more floods will increase the number of underflows and the intensity of deep-water renewal - and consequently will cause higher deep-water dissolved oxygen concentrations. Vice versa, fewer floods weaken deep-water renewal and lead to lower deep-water dissolved oxygen concentrations. Meanwhile, a change from glacial nival regime (present) to a nival pluvial regime (future) is expected to decrease deep-water renewal. While flood frequencies are not expected to change noticeably for the next decades, it is most likely that increased winter discharge and decreased summer discharge will reduce the number of deep density-driven underflows by 10% and favour shallower riverine interflows in the upper hypolimnion. The renewal in the deepest layers is expected to be reduced by nearly 27%. This study underlines potential consequences of climate change on the occurrence of deep river underflows and water residence times in deep lakes.

  8. Particle-Dissolved Phase Partition of Polychlorinated Biphenyls in High Altitude Alpine Lakes.

    PubMed

    Nellier, Yann-Michel; Perga, Marie-Elodie; Cottin, Nathalie; Fanget, Philippe; Naffrechoux, Emmanuel

    2015-08-18

    We investigated whether polychlorinated biphenyls (PCBs) partitioning between the dissolved and particulate phases in two high altitude alpine lakes was determined by the quantity, size structure, or composition of suspended particles. Within- and between-lakes differences in water-particulate phase partition coefficient (Kp) were not related to total suspended matter, phytoplankton biomass, or taxonomic composition. Yet, a seasonal relationship between Kp and Kow was detected for both lakes, revealing equilibrium of PCBs partition when lakes were ice covered. On the contrary, PCBs partitioning between particles and water appeared kinetically limited during the open water season. Partition is therefore mainly governed by thermodynamic laws during the ice-covered period, while none of the tested physical or biological parameters seemed to explain the distribution of these particle-reactive contaminants in the open water period. PCBs were always mainly associated with particulate matter, but partitioning within different particulate size-fractions varied between seasons and between years during open water periods. When ice cover is absent, PCBs were mainly adsorbed on microplankton, the largest phytoplanktonic size fraction, which is the least likely to get grazed by pelagic microconsumers.

  9. Effects of oligotrophication on primary production in peri-alpine lakes

    NASA Astrophysics Data System (ADS)

    Finger, David; Wüest, Alfred; Bossard, Peter

    2013-08-01

    During the second half of the 20th century untreated sewage released from housing and industry into natural waters led to a degradation of many freshwater lakes and reservoirs worldwide. In order to mitigate eutrophication, wastewater treatment plants, including Fe-induced phosphorus precipitation, were implemented throughout the industrialized world, leading to reoligotrophication in many freshwater lakes. To understand and assess the effects of reoligotrophication on primary productivity, we analyzed 28 years of 14C assimilation rates, as well as other biotic and abiotic parameters, such as global radiation, nutrient concentrations and plankton densities in peri-alpine Lake Lucerne, Switzerland. Using a simple productivity-light relationship, we estimated continuous primary production and discussed the relation between productivity and observed limnological parameters. Furthermore, we assessed the uncertainty of our modeling approach based on monthly 14C assimilation measurements using Monte Carlo simulations. Results confirm that monthly sampling of productivity is sufficient for identifying long-term trends in productivity and that conservation management has successfully improved water quality during the past three decades via reducing nutrients and primary production in the lake. However, even though nutrient concentrations have remained constant in recent years, annual primary production varies significantly from year to year. Despite the fact that nutrient concentrations have decreased by more than an order of magnitude, primary production has decreased only slightly. These results suggest that primary production correlates well to nutrients availability but meteorological conditions lead to interannual variability regardless of the trophic status of the lake. Accordingly, in oligotrophic freshwaters meteorological forcing may reduce productivity impacting on the entire food chain of the ecosystem.

  10. Sediments as tracers for transport and deposition processes in peri-alpine lakes: A case study

    NASA Astrophysics Data System (ADS)

    Righetti, Maurizio; Toffolon, Marco; Lucarelli, Corrado; Serafini, Michele

    2011-12-01

    SummaryThe benthic sediment fingerprint is analysed in the small peri-alpine lake Levico (Trentino, Italy) to identify the causes of recurrent phenomena of turbidity peaks, particularly evident in a littoral region of the water body. In order to study the sediment transport processes, we exploit the fact that the sediment supply from the major tributary has a specific chemical composition, which differs from that of the nearby lake basin. Three elements (Fe, Al, K) have been used as tracers to identify the source and the deposition patterns of tributary sediments, and another typical element, Si, has been critically analysed because of its dual (allochthonous and autochthonous) origin. Several samples of the benthic material have been analysed using SEM-EDS, and the results of the sedimentological characterisation have been compared with the patterns of sediment accumulation at the bed of the lake obtained using a three-dimensional numerical model, in response to the tributary supply under different external forcing and stratification conditions. The coupled use of field measurements and numerical results suggests that the turbidity phenomena are strongly related to the deposition of the sediments supplied by the tributary stream, and shows that it is possible to reconstruct the process of local transport when the tributary inflow is chemically specific.

  11. Relationship between apparent optical properties and photosynthetic pigments in the sub-alpine Lake Iseo.

    PubMed

    Pepe, M; Giardino, C; Borsani, G; Cardoso, A C; Chiaudani, G; Premazzi, G; Rodari, E; Zilioli, E

    2001-03-14

    The aim of the present study was the evaluation of methods for estimating the content of bio-physical parameters in lake water on the basis of spectral reflectance measured above water surface, in particular the estimation of chlorophyll-a (chl-a) concentrations. Data sets considered refer to some sampling point located in the sub-alpine meso-eutrophic Lake Iseo, surveyed six times over the period March-July and once in November 1998, as these months were very important for the characterization of the springtime algal bloom, which affect the lake waters yearly. At each point station, limnological observations (chlorophyll, total suspended solids, Secchi disk depth) were conducted simultaneously with optical measurements. The latter consisted of water leaving radiance measured by means of a spectroradiometer above the water surface; moreover, a standard reflector radiance was also measured to obtain the water reflectance. Reflectance spectra were transformed according to two well-documented models and correlated to water quality parameters, to investigate their performances as retrieval algorithms under different conditions and referring to different analytical methods. Results outline the sensitivity of the models to chl-a concentrations, different phytoplankton composition, and the sampling depth.

  12. Decadal and Seasonal Variations of Alpine Lakes in Glacierized areas of Central Asia during 1990-2015

    NASA Astrophysics Data System (ADS)

    Li, J.; Warner, T.; Chen, X.; Bao, A.

    2016-12-01

    Central Asia is one of the world's most vulnerable areas responding to global change. Glacier lakes in the alpine regions remain sensitive to climatic change and fluctuate with temperature and precipitation variations. Study shows that glaciers in Central Asia have retreated dramatically, leading to the expansion of the existing glacial lakes and the emergence of many new glacier lakes. The existence of these lakes increases the possibility of outburst flood during the ice melting season, which can bring a disaster to the downstream area. Mapping glacial lakes and monitoring their changes would improve our understanding of regional climate change and glacier-related hazards. Glacial lakes in Central Asia are mainly located at the Tianshan Mountains, the Altai Mountains, the Kunlun Mountains and the Pamirs with average elevation more than 1500 meters. Most of these lakes are supplied with the glaciers or snowmelt water during the summer seasons. Satellite remote sensing provides an efficient and objective tool to analyze the status and variations of glacial lakes. The increased availability of remote sensing sensors with appropriate spatial and temporal resolutions, broad coverage makes lake investigations more feasible and cost-effective. The paper intends to map glacier lake changes in glacierized alpine mountains with Landsat TM/ETM+ imagery. More than 600 scenes of Landsat images in circa 1990, circa 2000, circa 2010 and circa 2015 are used to map the decadal glacial lake changes over the Central Asia, and about 8 expanding glacial lakes are selected to map seasonal changes. Over 12000 glacial lakes were mapped in circa 1990, and in 2015, lake number are more than 16000, most of these new lakes are emerging in the last 10 years. The result shows that the number and area of the glacial lakes in the Altain Mountain remain stable, while the Tianshan Mountain have experienced expanding changes in the last two decades, and about a half number of lake areas are

  13. Transport of pollutants from cow feedlots in eastern Colorado into Rocky Mountain alpine lakes

    NASA Astrophysics Data System (ADS)

    Pina, A.; Denning, S.; Schumacher, R. S.

    2012-12-01

    Concentrated Animal Feeding Operations (CAFOs), also called factory farms, are known for raising tens of millions head of livestock including cows (beef and dairy), swine, and poultry. With as many as 250 head of cattle per acre, a United States Department of Agriculture's (USDA) Agricultural Research Service (ARS) report showed beef cattle from CAFOs in the United States produce as much as 24.1 million tons of manure annually. Gases released from cow manure include methane (CH4), nitrous oxide (N2O), hydrogen sulfide (H2S), and ammonia (NH3). During boreal summers Colorado experiences fewer synoptic weather systems, allowing the diurnal cycle to exert greater control of meteorological events along the mountain-plains interface. Anabatic, or upslope winds induced by the diurnal cycle, contribute largely to the transport of gases and particulates from feedlots in eastern Colorado into the Rocky Mountains, presenting a potential harm to natural alpine ecosystems. This study focuses on locating the source of transport of gases from feedlots along the eastern Front Range of Colorado into alpine lakes of the Rocky Mountains. Source regions are approximated using backward time simulation of a Lagrangian Transport model.

  14. Evaluation of storage and filtration protocols for alpine/subalpine lake water quality samples.

    PubMed

    Korfmacher, John L; Musselman, Robert C

    2007-08-01

    Many government agencies and other organizations sample natural alpine and subalpine surface waters using varying protocols for sample storage and filtration. Simplification of protocols would be beneficial if it could be shown that sample quality is unaffected. In this study, samples collected from low ionic strength waters in alpine and subalpine lake inlets and outlets in the western United States were used to evaluate (1) effects of refrigerated storage time on the chemistry of unfiltered samples, and (2) differences in sample filtration protocols. No analytes exhibited significant changes when stored less than 48 h. Six analytes (pH, sodium, ammonium, potassium, chloride, sulfate) exhibited statistically significant (but small) changes when storage time exceeded 48 h. Two analytes (calcium, nitrate) were significantly higher when samples were field filtered than when filtered in the laboratory, but the differences were also small. For waters similar to those in this test, unfiltered refrigerated samples may be stored up to 48 h without compromising sample quality. The small differences between field and lab filtration do not justify the expense, training, and contamination risk of field filtration.

  15. Identification and Characterization of Dynamic Alpine Subglacial Lakes Using InSAR, Radio- Echo Sounding, and Crevasse Interpretation

    NASA Astrophysics Data System (ADS)

    Capps, D. L.; Rabus, B. T.; Clague, J. J.

    2007-12-01

    We use interferometric synthetic aperture radar (InSAR), radio-echo sounding (RES), and crevasse interpretation to identify and characterize two dynamic alpine subglacial lakes in Glacier Bay National Park, Alaska. Although significant literature exists on large subglacial lakes in Antarctica, little research has been done on alpine subglacial lakes. Subglacial and subaerial glacier-dammed lakes and the catastrophic floods (jokulhlaups) that release are a hazard in glacierized mountain regions around the world. Many glacier-dammed lakes form subglacially during periods of glacier retreat and downwasting, but are not identified until they become subaerially exposed or release a jokulhlaup. The two lakes discussed here are dammed by Brady Glacier in southeast Alaska, 120 km west of Juneau. Initially, a conspicuous, 3-km-long crevasse in the glacier drew our attention to Hinge Lake, so named because of its hinge-like appearance. For the InSAR analysis, we utilized 20 ascending and descending ERS-1 and -2 tandem radar images provided by the European Space Agency. We obtained a DEM from Glacier Bay National Park that was based on data from the SRTM mission, with gaps filled using photogrammetry data. We co-registered and processed raw SAR signal data into complex, single-look images, created interferograms, and unwrapped the phase. To simplify the analysis, we assumed zero horizontal glacier movement. This assumption is valid because ice is flowing into a closed depression and all interferograms analyzed in this study show very little or zero horizontal motion. To further characterize the lakes, we conducted a RES survey to determine ice depths and substrate. We deduced principle stresses by interpreting crevasses patterns in combination with vertical displacement data derived from interferograms. A time series of interferograms shows vertical motion over large areas of the two lakes. A hydraulic connection between the two lakes is inferred from contemporaneous vertical

  16. Monitoring mountain lakes in a changing Alpine cryosphere: the Lago Nero project (Ticino, Switzerland)

    NASA Astrophysics Data System (ADS)

    Scapozza, Cristian; Bruder, Andreas; Domenici, Mattia; Lepori, Fabio; Pera, Sebastian; Pozzoni, Maurizio; Rioggi, Stefano; Colombo, Luca

    2017-04-01

    Mountain lakes and their catchments of the Alpine cryosphere are facing global pressures including climate warming and deposition of atmospheric pollutants. Due to their remoteness, often low buffer capacities and sensitive biotic communities, alpine lake catchments are particularly well suited as sentinels of environmental change. Lago Nero is the object of an intensive survey, aimed at developing predictive models of catchment-wide ecosystem responses to environmental change (Bruder et al. 2016). Lago Nero is located at the head of Val Bavona (Canton Ticino, southern Switzerland), in a southwest-facing catchment, with altitude ranging from 2385 to 2842 m asl. The substrate is dominated by gneissic bedrock with patches of grassy vegetation and shallow soils. The catchment is snow-covered approximately from November to May. For a similar period, the lake is ice-covered. Lago Nero is an oligotrophic, soft-water lake with a surface of approximatively 13 ha and a maximal depth of 73 m. According to the regional model of potential permafrost distribution in the southern Swiss Alps (Scapozza & Mari 2010), the presence of discontinuous permafrost is probable in almost the entire surface of the catchment covered by loose debris. A direct evidence of permafrost occurrence is the presence of a small active/inactive rock glacier in the south-eastern part of the catchment (front altitude: 2560 m asl). Monitoring of the site began in summer 2014, with an initial phase aimed at developing and testing methodologies and at evaluating the suitability of the catchment and the feasibility of the monitoring program. The intensive survey at Lago Nero measures a wide array of ecosystem responses, including runoff quantity and chemistry, catchment soil temperature (also on the rock glacier) and composition of terrestrial vegetation. Sampling frequency depends on the parameter measured, varying from nearly continuous (e.g. runoff and temperature) to five-year intervals (e.g. soil and

  17. Tropical high-altitude Andean lakes located above the tree line attenuate UV-A radiation more strongly than typical temperate alpine lakes.

    PubMed

    Aguilera, Ximena; Lazzaro, Xavier; Coronel, Jorge S

    2013-09-01

    Tropical high-altitude Andean lakes are physically harsh ecosystems. Located above the treeline (≥4000 m a.s.l.), they share common features with temperate alpine lakes, which impose extreme conditions on their aquatic organisms: e.g., strong winds, broad diel variations in water temperature, and intense solar ultraviolet radiation (UVR). However, because of their latitude, they differ in two major ecological characteristics: they lack ice cover during the winter and they do not present summer water column stratification. We sampled 26 tropical high-altitude Andean lakes from three regions of the Bolivian Eastern Andes Cordillera during the wet period (austral summer). We performed an ordination to better describe the typology of Andean lakes in relation to the environmental variables, and we assessed the relationships among them, focussing on the UV-A transparency (360 nm) throughout the water column. We found a positive correlation between UV-A transparency calculated as Z(1%) (the depth which reaches 1% of the surface UV-A), the lake maximum depth and Secchi transparency (r = 0.61). Z(1%) of UV-A was smaller in shallow lakes than in deep lakes, indicating that shallow lakes are less transparent to UV-A than deep lakes. We hypothesize that, compared to shallow lakes, deep lakes (maximum depth > 10 m) may have lower dissolved organic carbon (DOC) concentrations (that absorb UV radiation) due to lower temperature and reduced macrophyte cover. Based on our data, tropical high-altitude Andean lakes are less transparent to UV-A (K(d) range = 1.4-11.0 m(-1); Z(1%) depth range = 0.4-3.2 m) than typical temperate alpine lakes (1-6 m(-1), 3-45 m, respectively). Moreover, they differ in vertical profiles of UV-A, chlorophyll-a, and temperature, suggesting that they may have a distinct ecological functioning. Such peculiarities justify treating tropical high-altitude Andean lakes as a separate category of alpine lakes. Tropical high-altitude Andean lakes have been poorly

  18. Long-term EC measurements over a pre-alpine lake

    NASA Astrophysics Data System (ADS)

    Scholz, Katharina; Hammerle, Albin; Wohlfahrt, Georg

    2016-04-01

    Recent research indicates that inland waters are significant contributors to the global carbon cycle. However, up to now long-term measurements of carbon dioxide (CO2) and methane (CH4) fluxes above freshwater ecosystems are sparse and the knowledge on the magnitude of the fluxes and the involved processes needs to be improved. Most of the research has focused on tropical and boreal regions. Furthermore, many findings were based on short-term measurements or relied on non-continuous floating chamber measurements. This study is part of a cooperation project with the overarching aim to study possible effects of past, present and future hydrological extremes on carbon fluxes at catchment scale. The first step is to establish the complete carbon balance of a lake and therefore also to measure CO2 exchange between the atmosphere and the surface of a temperate lake for the first time continuously all year round. The eddy covariance method is a technique widely used for long-term, continuous measurements of energy and trace gas exchange between the atmosphere and terrestrial ecosystems. Here, we employ this method for year-round monitoring of CO2-, sensible and latent heat fluxes above Lake Lunz, a small pre-alpine lake in lower Austria. In addition, the water temperature profile was measured with high temporal resolution in order to capture the heat storage change of the lake during the ice free period. This together with measurements of the net radiation allows us to also evaluate the energy balance closure. The measurements started in December 2014 and here we present flux data as well as data on the energy balance closure of the first year. A preliminary analysis of the data indicated that the lake acts as a net source of CO2 with stronger emissions during night. The monthly mean amplitudes of the sensible (H) and latent (LE) heat flux were highest during the summer month (July, August), with a clear peak of H in the early morning hours. The water temperature profile

  19. Biogeochemical responses of two alpine lakes to climate change and atmospheric deposition, Jasper and Banff National Parks, Canadian Rocky Mountains

    NASA Astrophysics Data System (ADS)

    Hobbs, W.; Vinebrooke, R. D.; Wolfe, A. P.

    2012-12-01

    The sensitivity of remote alpine ecosystems to global change has been documented by 20th century changes in climate, glacial recession, and terrestrial and aquatic ecosystems. In many cases the magnitude and dominance of abiotic drivers on recent changes in alpine lakes is often mediated by processes within the hydrologic catchment. Here we present sedimentary records of biogeochemical responses in two alpine lake ecosystems to multiple environmental drivers over the last ~ 500 years in Banff and Jasper National parks. We combine paleoecological measures of primary production (fossil microbial pigments) and diatom community structure with geochemical proxies of reactive N (Nr) deposition to describe the nature and rate of recent ecosystem changes. Curator Lake in Jasper shows a strong diatom response to the limnological effects of climate warming (e.g. thermal stratification), but little evidence of changes in Nr cycling over the last ~500 years. The response of McConnell Lake in Banff to climate change is strongly mediated by glacial activity within the catchment, and changing inputs of Nr. Our findings highlight the range of limnological responses that may be expressed by similar ecosystems subjected to comparable abiotic stressors, while further documenting the magnitude of the ecological footprint associated with recent environmental change in mountain park environments.

  20. Air pollution in the shore zone of a Large Alpine Lake - 1 - Road dust and urban aerosols at Lake Tahoe, California-Nevada

    NASA Astrophysics Data System (ADS)

    VanCuren, R.; Pederson, J.; Lashgari, A.; Dolislager, L.; McCauley, E.

    2012-01-01

    Concentrated human activity and limited atmospheric mixing create a high potential for airborne pollutant impacts to alpine lakes developed as mountain resorts. Lake Tahoe is a major alpine resort straddling the California-Nevada border, receiving more than two million visitors each year. The lake's clarity has declined substantially since the inception of intense development in the Tahoe basin in the 1970s. The 2002-2004 Lake Tahoe Atmospheric Deposition Study (LTADS) was conducted as part of a multi-agency effort to develop a water quality management plan for the lake. Estimating aerosol deposition to the lake requires detailed knowledge of the spatial and temporal patterns of aerosol concentration, size distribution, and chemical composition over the entire basin - and developing a management plan requires also that the sources of the aerosols be known with considerable specificity. In lieu of the intensive measurement network implied by this level of detail, we hypothesized that a set of measurements to characterized the temporal, spatial, and size distribution patterns of particles in ambient air and in local emissions in the vicinity of Lake Tahoe could be used to extrapolate long time series of simple measurements to an annual aerosol deposition computation. Here we report the results of our detailed aerosol measurement campaign. Our results show that there are strong systematic and repeating gradients in aerosol loading that occur as functions of location, land use, traffic activity, and time of day, and that road dust is a major source of aerosols around the lake. In addition, we observed strong consistency of particle size distributions as a function of source type, largely independent of particle concentrations. Finally, we demonstrated the use of particle counters to directly observe downwind dispersion and deposition of particles. Together, these findings support the use of imputed location- and time-specific size distributions in annual aerosol

  1. Ciliate community structure and interactions within the planktonic food web in two alpine lakes of contrasting transparency.

    PubMed

    Kammerlander, Barbara; Koinig, Karin A; Rott, Eugen; Sommaruga, Ruben; Tartarotti, Barbara; Trattner, Florian; Sonntag, Bettina

    2016-11-01

    Climate warming is accelerating the retreat of glaciers and recently, many 'new' glacial turbid lakes have been created. In the course of time, the loss of the hydrological connectivity to a glacier causes, however, changes in their water turbidity and turns these ecosystems into clear ones.To understand potential differences in the food-web structure between glacier-fed turbid and clear alpine lakes, we sampled ciliates, phyto-, bacterio- and zooplankton in one clear and one glacial turbid alpine lake, and measured key physicochemical parameters. In particular, we focused on the ciliate community and the potential drivers for their abundance distribution.In both lakes, the zooplankton community was similar and dominated by the copepod Cyclops abyssorum tatricus and rotifers including Polyarthra dolichoptera, Keratella hiemalis, Keratella cochlearis and Notholca squamula. The phytoplankton community structure differed and it was dominated by the planktonic diatom Fragilaria tenera and the cryptophyte alga Plagioselmis nannoplanctica in the glacial turbid lake, while chrysophytes and dinoflagellates were predominant in the clear one.Ciliate abundance and richness were higher in the glacial turbid lake (∼4000-27 800 Ind L(-1), up to 29 species) than in the clear lake (∼570-7150 Ind L(-1), up to eight species). The dominant species were Balanion planctonicum, Askenasia cf. chlorelligera, Urotricha cf. furcata and Mesodinium cf. acarus. The same species dominated in both lakes, except for Mesodinium cf. acarus and some particle-associated ciliates, which occurred exclusively in the glacial turbid lake. The relative underwater solar irradiance (i.e. percentage of PAR and UVR at depth) significantly explained their abundance distribution pattern, especially in the clear water lake. In the glacial turbid lake, the abundance of the dominating ciliate taxa was mainly explained by the presence of predatory zooplankton.Our results revealed an unexpected high

  2. Dissolved greenhouse gas concentrations as proxies for emissions: First results from a survey of 43 Alpine lakes

    NASA Astrophysics Data System (ADS)

    Pighini, Sylvie; Wohlfahrt, Georg; Miglietta, Franco

    2015-04-01

    Up to very recently, freshwater ecosystems were neglected in assessments of the global carbon cycle and considered merely as passive 'pipes' which transport carbon from the land to the oceans. This view has been challenged by an increasing number of studies showing that freshwater ecosystems may negate a substantial fraction of the carbon sink through carbon dioxide (CO2) and in particular methane (CH4) emissions and thus rather should be viewed as 'reactors' which process a large fraction of the terrigenous carbon. Most of our knowledge on freshwater CO2 and CH4 emissions to date derives from studies in tropical and boreal regions, while temperate freshwater ecosystems are understudied. This study is focused on lakes from the Alpine area and their content in dissolved greenhouse gases, CH4 and CO2. We mostly aim to assess the content of dissolved methane and carbon dioxide from the Alpine lakes in order to understand whether Alpine lakes could be potential CH4 and CO2 emitters. We also would like to relate concentrations to lake characteristics and potential biotic and abiotic driving forces. A diverse set of 43 lakes, from Trentino, South Tirol (Italy) and North Tirol (Austria), was selected resulting in a gradient with respect to elevation (from 240 to 1700 m a.s.l.) and latitude (from 45.52° to 47.38°). Complementary to dissolved CH4 and CO2 surface water samples, dissolved oxygen and temperature were measured. Only water surface samples were considered. Analyses were done with a gas chromatographer equipped with a flame ionization detector (FID) for CH4 and a thermal conductivity detector (TCD) for CO2 determination. The first results show that all the sampled lakes were super-saturated in dissolved methane and carbon dioxide concentrations, at least partly to a degree that in the literature has been shown to result in substantial emissions to the atmosphere. To estimate emissions, CO2 and CH4 fluxes will be quantified using the eddy covariance and floating

  3. Erosion under climate and human pressures: An alpine lake sediment perspective

    NASA Astrophysics Data System (ADS)

    Arnaud, Fabien; Poulenard, Jérôme; Giguet-Covex, Charline; Wilhelm, Bruno; Révillon, Sidonie; Jenny, Jean-Philippe; Revel, Marie; Enters, Dirk; Bajard, Manon; Fouinat, Laurent; Doyen, Elise; Simonneau, Anaëlle; Pignol, Cécile; Chapron, Emmanuel; Vannière, Boris; Sabatier, Pierre

    2016-11-01

    We review the scientific efforts over the last decades to reconstruct erosion from continuous alpine lake sediment records. We focused both on methodological issues, showing the growing importance of non-destructive high resolution approaches (XRF core-scanner) as well as progresses in the understanding of processes leading to the creation of an "erosion signal" in lakes. We distinguish "continuous records" from "event-records". Both provide complementary information but need to be studied with different approaches. Continuous regionally-relevant records proved to be particularly pertinent to document regional erosion patterns throughout the Holocene, in particular applying the source to sink approach. Event-based approaches demonstrated and took advantage of the strong non-linearity of sediment transport in high altitude catchment areas. This led to flood frequency and intensity reconstructions, highlighting the influence of climate change upon flood dynamics in the mountain. The combination of different record types, both in terms of location (high vs. low elevation), sedimentology (high vs. low terrigenous contribution) and significance (local vs. regional) is one of the main outputs of this paper. It allows the establishment of comprehensive histories of NW French Alps erosion, but also and consequently, soil dynamics and hydrological patterns throughout the Holocene. We also discuss the influence of glacier dynamics, one of the major agents of erosion in the Alps. A major feature is the growing human influence upon erosion at a local scale since at least the middle of the Bronze Age (3500 cal. BP). However and according to the regional record from Lake Bourget, only few periods of rising erosion at local scales generated a regional record that can be discriminated from wetter climatic periods. Among them, the period between 200 BCE and 400 AD appeared to be marked by a generalised rise in human-triggered erosion at local scales in the northern French Alps

  4. Nonnative salmon alter nitrification in Great Lakes tributaries

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2013-05-01

    Nonnative species can affect the biogeochemistry of an ecosystem. For instance, Pacific salmon have been introduced for sport fishing in many streams and lakes beyond their native range, and their introduction may be altering nitrogen cycling in those ecosystems.

  5. Genetic Diversity and Hybridisation between Native and Introduced Salmonidae Fishes in a Swedish Alpine Lake

    PubMed Central

    Faulks, Leanne; Östman, Örjan

    2016-01-01

    Understanding the processes underlying diversification can aid in formulating appropriate conservation management plans that help maintain the evolutionary potential of taxa, particularly under human-induced activities and climate change. Here we assessed the microsatellite genetic diversity and structure of three salmonid species, two native (Arctic charr, Salvelinus alpinus and brown trout, Salmo trutta) and one introduced (brook charr, Salvelinus fontinalis), from an alpine lake in sub-arctic Sweden, Lake Ånn. The genetic diversity of the three species was similar and sufficiently high from a conservation genetics perspective: corrected total heterozygosity, H’T = 0.54, 0.66, 0.60 and allelic richness, AR = 4.93, 5.53 and 5.26 for Arctic charr, brown trout and brook charr, respectively. There were indications of elevated inbreeding coefficients in brown trout (GIS = 0.144) and brook charr (GIS = 0.129) although sibling relationships were likely a confounding factor, as a high proportion of siblings were observed in all species within and among sampling locations. Overall genetic structure differed between species, Fst = 0.01, 0.02 and 0.04 in Arctic charr, brown trout and brook charr respectively, and there was differentiation at only a few specific locations. There was clear evidence of hybridisation between the native Arctic charr and the introduced brook charr, with 6% of individuals being hybrids, all of which were sampled in tributary streams. The ecological and evolutionary consequences of the observed hybridisation are priorities for further research and the conservation of the evolutionary potential of native salmonid species. PMID:27032100

  6. Lakes as organic matter upgraders - seasonal variation in biochemical compositions of in- and outflowing particles in pre-alpine Lake Lunz, Austria

    NASA Astrophysics Data System (ADS)

    Khan, Samiullah; Hollaus, Lisa-Maria; Schelker, Jakob; Ejarque, Elisabet; Battin, Tom; Kainz, Martin

    2016-04-01

    Lakes are typically recharged by inflowing stream water and discharge into outflowing streams. In this multiannual field study on pre-alpine, oligotrophic Lake Lunz, Lower Austria, we hypothesized that, irrespective of seasons, stream water recharging the lake contains predominantly recalcitrant particular organic matter (POM; >1.2 um particle size), whereas outflowing lake water is mostly composed of more labile, algae-derived POM. We collected POM for 3 years (2013-2015) at a monthly basis from the inflowing and outflowing streams of Lake Lunz, analyzed POM content, its carbon and nitrogen, their stable isotopes, and fatty acids as biochemical indicators of POM sources. Preliminary results show that, independent of seasons, inflowing POM is rich in terrestrial markers, as evidenced by long-chain saturated fatty acids (>C22:0), with little contribution of autochthonous stream POM, such as algae-derived long-chain polyunsaturated fatty acids (LC-PUFA). However, POM in outflowing water contained considerably less terrestrial markers, but clearly higher contents of highly nutritious, algae-derived LC-PUFA. These results suggest that oligotrophic Lake Lunz acts as a biochemical upgrader within the fluvial network of this drainage basin and supplies highly nutritional POM to consumers further downstream. Ongoing research is aimed at identifying how much of the terrestrial and autochthonous POM is retained and processed in the lake (biota, sediments, or respired).

  7. Identification and Characterization of Dynamic Alpine Subglacial Lakes Using a Fusion of InSAR and GIS

    NASA Astrophysics Data System (ADS)

    Capps, D. L.; Rabus, B. T.; Clague, J. J.

    2008-12-01

    We use interferometric synthetic aperture radar (InSAR) and a geographic information system (GIS) to identify and characterize three dynamic alpine subglacial lakes in Glacier Bay National Park, Alaska. Subglacial and subaerial glacier-dammed lakes and the catastrophic floods (jokulhlaups) they release are a hazard in glacierized mountain regions around the world. Many subglacial lakes are not identified until they become subaerially exposed or release a jokulhlaup. The lakes discussed here are dammed by the Brady Glacier in southeast Alaska, 120 km west of Juneau. For InSAR analysis, we utilized 20 ascending and descending ERS-1/-2 tandem radar images (1-day repeat interval) provided by the European Space Agency and a Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM). We processed SAR data into unwrapped interferograms using standard techniques. Two interferograms have very poor coherence and the remaining eight show significant line of sight (LOS) displacement over the surface of the subglacial lakes through time. However, because the displacement is LOS, the relative contributions of horizontal and vertical displacement are ambiguous. We then created horizontal and vertical displacement maps using near concurrent ascending and descending track interferograms and a glacier flow map, which describes horizontal glacier movement. We created the flow map manually by drawing arrows in a GIS in the direction of glacier flow based on observed crevasse patterns, medial moraines, and constraining topography, then interpolated between arrows. The displacement maps have significant areas of error caused by suboptimal imaging geometry that we masked out using a simple script. Horizontal displacement over the subglacial lakes was negligible. We exported the resulting vertical displacement maps to a GIS and quantified the change in volume of the lakes through time. Because there was negligible horizontal displacement around the three lakes, we were able to

  8. Holocene lake level fluctuations of a small alpine lake in the Qilian Mountains, NW China: a comparison of chironomid, ostracod, pollen and geochemistry data.

    NASA Astrophysics Data System (ADS)

    Mischke, S.; Herzschuh, U.

    2003-04-01

    A core of 14 m length was drilled in a small alpine lake in the Qilian Mountains, NW China. The lake Luanhaizi has a drainage area of about 30 km2 and is situated at an altitude of 3200 m which represents the altitude of the present regional upper timberline. Due to the small size of the open-basin lake (surface area about 1 km2) and the sharply outlined catchment area the lake is regarded as a very sensitively and rapidly responding ecosystem. Analyses of ostracod shells, head capsules of larval chironomids and pollen and spores were conducted and the organic and carbonate content (LOI), element concentrations and magnetic susceptibility of core samples determined. Ostracod taxa mainly comprise Candona candida, C. neglecta, C. rawsoni, Cyclocypris ovum, Cypridopsis vidua, Fabaeformiscandona caudata, F. danielopoli, F. hyalina, Herpetocypris chevreuxi, Heterocypris salina, Ilyocypris cf. bradyi, I. echinata, I. lacustris and Limnocythere inopinata. They may be used to distinguish periods of low lake levels corresponding to a dense cover of aquatic plants at the lake bottom from stages of higher lake levels and a corresponding decrease in macrophytes at the core site. Chironomid taxa belonging to Chironomus, Cladopelma, Glyptotendipes, Micropsectra, Paratanytarsus, Polypedilum, Psectrocladius and Tanytarsus further provide information on variations in benthic oxygen availability and lake level fluctuations. Several units of the core show high abundances of pollen and spores of higher aquatic and wetland plants and fungi (Cyperaceae, Hippuris, Myriophyllum and Glomus) indicating low lake levels. In contrast, algae such as Botryococcus, Pediastrum and Tetraedron were regarded to reflect higher water levels. Typha angustifolia-type, Typha latifolia, Alisma and Potamogeton were recorded in low abundances as well. The organic content of core samples averages 6 % displaying four alternating stages of distinct minima and maxima. Lowest values of about 1 % occur at the core

  9. Climate change and Saharan dust drive recent cladoceran and primary production changes in remote alpine lakes of Sierra Nevada, Spain.

    PubMed

    Jiménez, Laura; Rühland, Kathleen M; Jeziorski, Adam; Smol, John P; Pérez-Martínez, Carmen

    2017-08-22

    Recent anthropogenic climate change and the exponential increase over the past few decades of Saharan dust deposition, containing ecologically important inputs of phosphorus (P) and calcium (Ca), are potentially affecting remote aquatic ecosystems. In this study, we examine changes in cladoceran assemblage composition and chlorophyll-a concentrations over the past ~150 years from high-resolution, well-dated sediment cores retrieved from six remote high mountain lakes in the Sierra Nevada Mountains of Southern Spain, a region affected by Saharan dust deposition. In each lake, marked shifts in cladoceran assemblages and chlorophyll-a concentrations in recent decades indicate a regional-scale response to climate and Saharan dust deposition. Chlorophyll-a concentrations have increased since the 1970s, consistent with a response to rising air temperatures and the intensification of atmospheric deposition of Saharan P. Similar shifts in cladoceran taxa across lakes began over a century ago, but have intensified over the past ~50 years, concurrent with trends in regional air temperature, precipitation, and increased Saharan dust deposition. An abrupt increase in the relative abundance of the benthic cladoceran Alona quadrangularis at the expense of Chydorus sphaericus, and a significant increase in Daphnia pulex gr. was a common trend in these softwater lakes. Differences in the magnitude and timing of these changes are likely due to catchment and lake-specific differences. In contrast with other alpine lakes that are often affected by acid deposition, atmospheric Ca deposition appears to be a significant explanatory factor, amongst others, for the changes in the lake biota of Sierra Nevada that has not been previously considered. The effects observed in Sierra Nevada are likely occurring in other Mediterranean lake districts, especially in soft water, oligotrophic lakes. The predicted increases in global temperature and Saharan dust deposition in the future will further

  10. New homogenized daily lake surface water temperature data of three decades from multiple sensors confirm warming of large sub-alpine lake Garda

    NASA Astrophysics Data System (ADS)

    Pareeth, Sajid; Salmaso, Nico; Adrian, Rita; Neteler, Markus

    2016-04-01

    Availability of remotely sensed multi-spectral images from the early eighties covering three decades of voluminous data could help researchers to study the change dynamics in bio-physical characteristics of land and water. However it is very important to homogenize these data originating from multiple sources which follow different standards and quality. In this study, we explored the thermal dynamics of a large sub-alpine lake Garda over last twentyeight years (1986 - 2014) using Lake Surface Water Temperature (LSWT) derived from the thermal bands of moderate resolution sensors - AVHRR/2, AVHRR/3, ATSR1, ATSR2, A(A)TSR and MODIS aboard multiple satellites. We developed a homogenized daily LSWT dataset (12:00 P.M) at 1km spatial resolution combining the data from these sensors using split window technique and performing an acquisition time correction. The gaps in the temporal database due to clouds were filled by applying Harmonic ANalysis of Time Series (HANTS). The results show high correlation (R2 > 90) between satellite derived LSWT (taken into account both individual sensors and the combined data) and the in-situ data. The time correction enable us to perform a trend analysis on unified datasets corrected for its acquisition times. The trend analysis using non-parametric tests shows significant warming in annual trend at the rate of 0.01K yr-1 (p<0.05), while in summer the increasing trend is 0.02K yr-1(p<0.1). The results are in line with similar findings on warming of Alpine lakes. Moreover, the advantage of the spatial coverage at 1 km resolution we are able to characterize the thermal dynamics of the lake Garda at multiple locations of this large lake.

  11. A bacterial disease of perch (Perca fluviatilis L.) in an alpine lake: isolation and preliminary study of the causative organism.

    PubMed

    Michel, C

    1981-10-01

    An epizootic among perch (Perca fluviatilis L.) occurred during the summer and fall of 1979 in an alpine lake (Lake Annecy, Haute-Savoie) in France. Hemorrhagic and ulcerative clinical signs were associated with the height of the mortality. A Gram-negative, non-motile, slow-growing bacterium was isolated from skin lesions is diseased fish. Aeromonas hydrophila often was present. Since the nonmotile bacterium was suspected to be the etiological agent, its characteristics and pathogenicity were determined. The bacterium was pathogenic to perch, possibly pathogenic to rainbow trout, and non-pathogenic to carp. It could be reisolated from infected fish, but its physiologic and biochemical properties have not been assessed to determine the taxonomic position.

  12. A 14,000-year oxygen isotope record from diatom silica in two alpine lakes on Mt. Kenya.

    PubMed

    Barker, P A; Street-Perrott, F A; Leng, M J; Greenwood, P B; Swain, D L; Perrott, R A; Telford, R J; Ficken, K J

    2001-06-22

    Oxygen isotopes are sensitive tracers of climate change in tropical regions. Abrupt shifts of up to 18 per mil in the oxygen isotope ratio of diatom silica have been found in a 14,000-year record from two alpine lakes on Mt. Kenya. Interpretation of tropical-montane isotope records is controversial, especially concerning the relative roles of precipitation and temperature. Here, we argue that Holocene variations in delta(18)O are better explained by lake moisture balance than by temperature-induced fractionation. Episodes of heavy convective precipitation dated approximately 11,100 to 8600, 6700 to 5600, 2900 to 1900, and <1300 years before the present were linked to enhanced soil erosion, neoglacial ice advances, and forest expansion on Mt. Kenya.

  13. Seasonal changes in CH4 emissions from an alpine reservoir, Lake Klöntal, Switzerland

    NASA Astrophysics Data System (ADS)

    Sollberger, S.; Eugster, W.; Schubert, C.; Wehrli, B.

    2012-04-01

    Atmospheric methane (CH4) concentration doubled since the pre-industrialized era and its potential as a greenhouse gas is 25 higher than CO2 over a 100-year horizon. Recent studies showed an important contribution of inland waters, including hydropower reservoirs, to the global CH4 cycle. However, the large seasonal and latitudinal variability of emissions reported in the literature highlights the necessity for a better understanding of CH4 emission mechanisms. The aim of this study was to investigate physical factors (water level and temperature) that trigger the seasonal pattern of CH4 emissions in a Swiss alpine reservoir, Lake Klöntal, using multiple methods. Atmospheric CH4 flux was measured using a fast methane analyzer (FMA, Los Gatos Research) and an eddy covariance tower set on a floating platform from April to December 2011 (before ice sets). Emissions were also measured monthly via chambers and calculated from surface water concentrations using Henry's law. Methane ebullition was examined over the lake surface of 5 km2 using a split-beam echosounder. Typical daily variations of CH4 were measured with the eddy covariance setup within the range of 0.23 and 7.4 mg CH4 m-2 d-1 (95% confidence interval) and were mainly related to temperature and solar radiation variability. The seasonal trend shows that average fluxes increase from 3.0 (April) to 3.7 mg CH4 m-2 d-1 in November. Much larger fluctuations can be observed in comparison to the chamber results where the emissions typically increase throughout the day. Furthermore, highest chamber fluxes were measured in July and October, which does not correspond with the FMA results (November). This inconsistency is also observed in the flux estimates calculated from surface concentrations of which the highest fluxes were in September. Ebullition was only observed (Jul., Sep. and Nov.) in a very shallow area where it was not possible to use the echosounder. Hence, our measurements may slightly underestimate the

  14. The epidemiology of illness and injury at the alpine venues during the Salt Lake City 2002 Winter Olympic Games.

    PubMed

    Allen, Todd L; Jolley, Scott J; Cooley, Vernon J; Winn, Robert T; Harrison, Jeffery D; Price, Richard R; Rich, J Charles

    2006-02-01

    The Emergency Medicine literature has described levels of medical care for mass gatherings in the United States, including for the Los Angeles 1984 Summer and Calgary 1988 Winter Olympic Games. However, there are limited data to describe the type and number of illness or injury that may occur during mass gatherings in an alpine winter environment. To describe the epidemiology of illness and injury seen among spectators at the alpine and snowboarding venues during the Salt Lake City 2002 Winter Olympic Games, we conducted a retrospective review of the Salt Lake City 2002 Olympic Medical Care database for all patient encounters during the operational period of the Games at the alpine and snowboarding venues. The three venues included were: Deer Valley Resort (DVR), Park City Mountain Resort (PCM), and Snowbasin Resort (SBA). Each venue had a medical clinic located on site for spectators and another for athletes. Physicians, nurses, emergency medical technicians, and therapists staffed the clinics. The database was created by Inter-mountain Health Care (IHC) in conjunction with Salt Lake City 2002 Winter Olympic staff and consisted of descriptive reports of all patient encounters from all venues including demographic, epidemiology, and outcome information. IHC maintains the database, and was the sole medical provider for the Games. Each venue had at least 6 days of competition events. Over the 19 days of the Olympiad, a total of 410,160 spectators and 3,961 competitive athletes attended the three venues. There were 841 spectators evaluated and treated at the venue clinics, and mobile medical staff treated 262 spectators. The top five spectator clinic diagnostic categories were: sprain/strain (n=108), miscellaneous trauma (n=103), respiratory (n=88), miscellaneous medical (n=69), and digestive (n=52). Fifty spectators required transport to a hospital for additional care: 27 required transfer by ground ambulance and the remainder were transported by private vehicle. The

  15. Where have all the females gone? Male biased sex-ratio in Arctodiaptomus alpinus (Imhof, 1885) in alpine lakes

    NASA Astrophysics Data System (ADS)

    Žibrat, U.; Brancelj, A.

    2009-04-01

    In populations with both males and females sex-ratio is one of the driving forces of population dynamics. It influences fecundity, inbreeding and social interactions. Sex-ratio is affected by several biotic and abiotic factors, either by selective killing of one sex or by inducing migrations. In alpine lakes of Triglav National Park, Slovenia, an extremely male biased sex-ratio in Arctodiaptomus alpinus (Imhof, 1885) was regularly observed since 1992. We analysed population dynamics and sex-ratio of A. alpinus in three alpine lakes (Jezero v Ledvicah, Rjavo jezero and Zgornje Kriško jezero) from Triglav National Park in Slovenia. In addition to seasonal dynamics we also researched long-term changes in sex-ratio (in a period of 11 years from autumn samples) as a result of increased air-temperature, and zooplankton diurnal vertical migrations. Adults of both sexes were found to appear at the same time in the water collumn with males prevailing throughout the season. A similar trend was found in copepodites CV. The percent of adult females began increasing in late summer, when there were no more copepodites and recrutation from copepodites CV to adults stopped, while male mortality increased. All cohorts of A. alpinus were found to perform diurnal vertical migrations. Both adult and CV females remained close to the bottom during the day and migrated vertically during the night. Results of the long-term study show no changes in sex-ratio in autumn.

  16. Floods and sediment transport into the pre-Alpine Lake Mondsee: A dual monitoring of detrital layer deposition in the lake and sediment dynamics in the catchment

    NASA Astrophysics Data System (ADS)

    Kämpf, L.; Müller, P.; Swierczynski, T.; Güntner, A.; Plessen, B.; Dulski, P.; Naumann, R.; Brauer, A.

    2012-04-01

    Lakes form ideal traps in the landscape, continuously recording land surface processes in the catchment. The clastic-detrital fraction of lake sediments is controlled by runoff processes that deliver suspended sediment particles from the catchment (source) to the lake (sink). Discrete detrital layers intercalated within annually laminated (varved) sediments of the pre-Alpine Lake Mondsee (481 m above sea level, Upper Austria) coincide with instrumental records of runoff events in spring and summer and, thus, provide a seasonal archive of floods in pre-instrumental time. A reliable interpretation of the flood layer record, however, especially of variations in layer characteristics and of floods without a coinciding layer, necessitates knowledge about hydrological and sedimentary processes during recent runoff events. For this purpose, a comprehensive monitoring network was set up in the catchment of Lake Mondsee in 2011 following a nested catchment approach. Two chains of sediment traps within the lake, one located 900 m off the main inflow (water depth: 55 m) and one in the deepest part of the lake (61 m), collect sediment on a monthly and 3-day basis. Along the main tributary and its sub-catchments, five monitoring stations were installed, which continuously record precipitation, river water level, water temperature, electric conductivity and turbidity. Samples of suspended sediment were taken automatically during runoff events. Until now, our monitoring data cover the last year from January 13th 2011 to January 3rd 2012 and show considerable variations in hydrological conditions and sedimentation within the lake. Regarding the transport of suspended sediment into Lake Mondsee, four flood events were recorded in January, March, May and August 2011 generated by melting of snow (winter) or intense rainfall (summer). Most of the detrital matter was deposited in the delta area where flux rates exceed values in the deepest part of the lake by up to a factor of 30. The

  17. Anthropogenic climate change has altered primary productivity in Lake Superior.

    PubMed

    O'Beirne, M D; Werne, J P; Hecky, R E; Johnson, T C; Katsev, S; Reavie, E D

    2017-06-09

    Anthropogenic climate change has the potential to alter many facets of Earth's freshwater resources, especially lacustrine ecosystems. The effects of anthropogenic changes in Lake Superior, which is Earth's largest freshwater lake by area, are not well documented (spatially or temporally) and predicted future states in response to climate change vary. Here we show that Lake Superior experienced a slow, steady increase in production throughout the Holocene using (paleo)productivity proxies in lacustrine sediments to reconstruct past changes in primary production. Furthermore, data from the last century indicate a rapid increase in primary production, which we attribute to increasing surface water temperatures and longer seasonal stratification related to longer ice-free periods in Lake Superior due to anthropogenic climate warming. These observations demonstrate that anthropogenic effects have become a prominent influence on one of Earth's largest, most pristine lacustrine ecosystems.

  18. Anthropogenic climate change has altered primary productivity in Lake Superior

    NASA Astrophysics Data System (ADS)

    O'Beirne, M. D.; Werne, J. P.; Hecky, R. E.; Johnson, T. C.; Katsev, S.; Reavie, E. D.

    2017-06-01

    Anthropogenic climate change has the potential to alter many facets of Earth's freshwater resources, especially lacustrine ecosystems. The effects of anthropogenic changes in Lake Superior, which is Earth's largest freshwater lake by area, are not well documented (spatially or temporally) and predicted future states in response to climate change vary. Here we show that Lake Superior experienced a slow, steady increase in production throughout the Holocene using (paleo)productivity proxies in lacustrine sediments to reconstruct past changes in primary production. Furthermore, data from the last century indicate a rapid increase in primary production, which we attribute to increasing surface water temperatures and longer seasonal stratification related to longer ice-free periods in Lake Superior due to anthropogenic climate warming. These observations demonstrate that anthropogenic effects have become a prominent influence on one of Earth's largest, most pristine lacustrine ecosystems.

  19. Bioaccumulation of ultraviolet sunscreen compounds (mycosporine-like amino acids) by the heterotrophic freshwater ciliate Bursaridium living in alpine lakes

    PubMed Central

    Sonntag, Bettina; Kammerlander, Barbara; Summerer, Monika

    2017-01-01

    Abstract Ciliates in shallow alpine lakes are exposed to high levels of incident solar ultraviolet radiation (UVR). We observed the presence of specific sunscreen compounds, the mycosporine-like amino acids (MAAs), in several populations of Bursaridium, a relatively large ciliate species found in such lakes. The populations from 3 highly UV transparent lakes revealed the presence of 7 MAAs (MG, SH, PR, PI, AS, US, and PE) in total concentrations of 3.6–52.4 10−5 μg μg−1 dry weight (DW) per individual, whereas in one glacially turbid and less UV transparent lake, no MAAs were detected in the Bursaridium population. The MAAs in the ciliates generally reflected the composition and relative amounts of the lakes’ seston MAAs, assuming that the ciliates fed on MAA-rich plankton. We experimentally found that naturally acquired MAAs prevented ciliate mortality under simulated UVR and photosynthetically active radiation (PAR) conditions. We further tested the dietary regulation of the MAAs-content in the ciliates under artificial UVR and PAR exposure and found an increase in MAAs concentrations in all treatments. Our assumption was that several stress factors other than irradiation were involved in the synthesis or up-regulation of MAAs. PMID:28690781

  20. Historical deposition of persistent organic pollutants in Lake Victoria and two alpine equatorial lakes from East Africa: Insights into atmospheric deposition from sedimentation profiles.

    PubMed

    Arinaitwe, Kenneth; Rose, Neil L; Muir, Derek C G; Kiremire, Bernard T; Balirwa, John S; Teixeira, Camilla

    2016-02-01

    Information on historical deposition of persistent organic pollutants (POPs) for African lakes is very limited. We investigated historical deposition trends and sources of POPs in sediment cores from Lakes Victoria (SC1), Bujuku (Buju2) and Mahoma (Maho2). The latter two lakes are situated in the Rwenzori mountain range in western Uganda. SC1 was taken from a central depositional area within the Ugandan part of the lake. Profiles in Buju2 and Maho2 were used as a reference for historical atmospheric deposition. For the post-1940 sediment deposits in SC1, average focusing factor-adjusted fluxes (FFFs) of ΣDDTs, polychlorinated biphenyls (ΣPCBs), hexachlorocyclohexanes (ΣHCHs) and chlordanes (ΣCHLs) were 390, 230, 210 and 120 ng m(-2) yr(-1). Higher fluxes of ΣDDTs, ΣPCBs, and ΣCHLs were observed in Buju2 and Maho2. The average FFF of HCB in Buju2 was the highest while the values for Maho2 and SC1 were similar. The endosulfan FFFs in SC1 were lower than in the alpine lake cores. Generally, Buju2 was a better reference for historical atmospheric deposition of POPs than Maho2 probably due to distortion of the latter's profile by Lake Mahoma's forested catchment. Profiles of p,p'-DDE, ΣCHLs and HCB in SC1 were consistent with atmospheric deposition while profiles of PCBs and HCHs were indicative of particle-bound loadings from additional sources. Profiles of endosulfans, DDTs, and chlordanes were consistent with influence of other factors such as anoxia, and dilution. Further studies of spatial resolution of historical deposition, especially in near-shore deposition areas of the lake are recommended.

  1. Aerosol generation and circulation in the shore zone of a Large Alpine lake - 2 - Aerosol distributions over Lake Tahoe, CA

    NASA Astrophysics Data System (ADS)

    VanCuren, R.; Pederson, J.; Lashgari, A.; Dolislager, L.; McCauley, E.

    2012-01-01

    The temporal, spatial, and size-distribution patterns of particles in ambient air over the surface of Lake Tahoe (Nevada and California) were studied as part of the 2003-2004 Lake Tahoe atmospheric deposition study (LTADS). The concentration of population along the shoreline of Lake Tahoe makes accurate characterization of local aerosol generation and transport especially important in estimation of annual particle flux to the surface of the lake. Measurements taken while cruising on the lake show that aerosol concentrations in near shore areas are primarily controlled by a combination of diurnal cycling of land- and lake- breezes and particle emissions driven by cycles of human activity near the shore. These effects were observed to be highly localized. Highest concentrations were found just offshore from urbanized areas, especially shoreline centers of activity; lowest concentrations were found along undeveloped shoreline; low-to-intermediate concentrations were measured over the middle areas of the lake. The on-lake data reported here indicate that aerosols over the lake, and thus dry deposition to the lake, are dominated by the same processes that control onshore emissions, and that the impact is strongest in the near shore areas of the lake.

  2. Numerical simulation of local atmospheric circulations in the pre-Alpine area between Lake Garda and Verona

    NASA Astrophysics Data System (ADS)

    Laiti, L.; Serafin, S.; Zardi, D.

    2010-09-01

    The pre-Alpine area between Lake Garda and Verona displays a very complex and heterogeneous territory, allowing the development of several interacting systems of thermally driven local winds, the major being the lake/land breeze system on the coasts of Lake Garda and the up/down-valley wind system between the plain and the river Adige Valley. In order to investigate the local wind patterns, a series of nested numerical simulations with a horizontal resolution of 500 m were carried out using the ARPS 5.2.9 model (Xue et al. 2000, 2001), considering a fair weather day suitable for a clear development of the expected circulations (15th July 2003). The simulated wind speed and direction, pressure, temperature and water vapour mixing ratio were compared to synoptic scale meteorological charts, to vertical profiles from radiosoundings taken at the major sounding stations of the alpine region and to local scale measurements performed at the surface station of Dolcè (at the inlet of the Adige Valley). Numerical results at all scales were found to be in very good agreement with the available sets of meteorological observations. The analysis of the diurnal evolution of the 3D fields of temperature, moisture content, wind and turbulent kinetic energy allowed the identification of a very shallow and clearly defined breeze front of cold and humid air moving from off-shore towards the Lake Garda coast, from the late morning (10:00 LST) until the evening (20:00 LST). The diurnal up-valley breeze was also well reproduced: the valley atmosphere displays a thick mixed layer dominated by shallow turbulent convection between 11:00 LST and 21:00 LST. Lateral slope winds were also recognized, as they created cross-valley convective cells. While no clear evidence of a nocturnal land breeze was found in the simulations, the nocturnal down-valley wind in the Adige Valley was clearly reproduced. Finally, a scalar transport equation was added to the ARPS model in order to simulate transport

  3. Influence of geomorphic setting on sedimentation of two adjacent alpine lakes, Triglav Lakes Valley (Julian Alps, NW Slovenia)

    NASA Astrophysics Data System (ADS)

    Smuc, Andrej; Skabene, Dragomir; Muri, Gregor; Vreča, Polona; Jaćimović, Radojko; Čermelj, Branko; Turšič, Janja

    2013-04-01

    The Triglav Lakes Valley is elongated, 7km long depression, located high (at places over 2000 m.a.s.l.) in the central part of the Julian Alps (NW Slovenia). It hosts 6 small isolated lakes that formed due to the combination of Neogene tectonic and Pleistocene glaciation. The study is focused on the 5th and 6th Triglav Valley Lakes that characterize lower part of the valley. The lakes are located so close to each other that they are even connected in times of high water. Thus, they share the same bedrock geology, are subjected to the same climatic forcing and share similar vegetation communities. Despite their proximity, the lakes differ in their hydrologic and geomorphic setting. The lakes have no permanent surface tributaries; however 5th is fed periodically, at times of high water level, by the Močivec spring, while additional water flows from the swamp area near its northern shore. An underground spring on the eastern side of 5th represents the lake's only permanent freshwater inflow, while drainage takes place to the west via a small ponor. 6th has only one weak underground spring on the eastern side of the lake. Water levels may fluctuate between 2 and 3 m. Additionally, the lakes have different configuration of lakes shores; the northern shores of the 5th lake are low-angle soil and debris covered plateau, while southern shores of the 5th lake and shores of the 6th lake are represented by heavily karstified carbonate base rock and covered partly by trees. The detailed sedimentary analysis of the lakes record showed some similarities, but also some significant differences. Sediments of both lakes are represented by fine-grained turbidity current deposits that are transported from lake shores during snow melt or storms. The grain-size and sedimentary rates of the lakes are however markedly different. The 5th lake has coarser grained sediments, with mean ranging from 46 to 60 µm and records higher sedimentation rates of ~0,57 cm/year, compared to the 6th lake

  4. Structure and diversity of ssDNA Microviridae viruses in two peri-alpine lakes (Annecy and Bourget, France).

    PubMed

    Zhong, Xu; Guidoni, Baptiste; Jacas, Louis; Jacquet, Stéphan

    2015-10-01

    Microviridae is a subset of single-stranded DNA (ssDNA) viruses infecting bacteria. This group of phages has been previously observed to be very abundant (representing >90% of the total known viral metagenomic sequences) in Lake Bourget. However, this observation was made only during one period (in summer) and from a single sample collected at a single depth (near surface). This result suggests the importance of these viruses, poorly examined thus far, especially in fresh waters. In this study, performed on the two largest natural lakes in France (e.g. Lakes Annecy and Bourget), Microviridae structure was determined each month throughout the year (2011) using PCR-DGGE, with primers that target the major-capsid-protein-encoding gene VP1; cloning/sequencing was used to investigate their diversity. Our results confirm that Microviridae are diverse in peri-alpine lakes and are mainly represented by gokushoviruses. We also found for the first time ssDNA viruses belonging to Alpavirinae, another subfamily within Microviridae recently proposed by Krupovic and Forterre (2011), generally prophages infecting members of the Phylum Bacteroidetes. Our data also support highly variable community composition and dynamics of individual components whose patterns were different between lakes, suggesting distinct host communities and/or abiotic influences between the two ecosystems. We point out that most of the major observed ssDNA Microviridae viruses display boom-bust patterns (with a sharp increase/decline) in their dynamics, with high relative abundances, suggesting brutal control of hosts and rapid regulation of the host community structure.

  5. Detecting chlorophyll, Secchi disk depth and surface temperature in a sub-alpine lake using Landsat imagery.

    PubMed

    Giardino, C; Pepe, M; Brivio, P A; Ghezzi, P; Zilioli, E

    2001-03-14

    Some bio-physical parameters, such as chlorophyll a concentration, Secchi disk depth and water surface temperature were mapped in the sub-alpine Lake Iseo (Italy) using Landsat Thematic Mapper (TM) data acquired on the 7 March 1997. In order to adequately investigate the water-leaving radiance, TM data were atmospherically corrected using a partially image-based method, and the atmospheric transmittance was measured in synchrony with the satellite passage. An empirical approach of relating atmospherically corrected TM spectral reflectance values to in situ measurements, collected during the satellite data acquisition, was used. The models developed were used to map the chlorophyll concentration and Secchi disk depth throughout the lake. Both models gave high determination coefficients (R2 = 0.99 for chlorophyll and R2 = 0.85 for the Secchi disk) and the spatial distribution of chlorophyll concentration and Secchi disk depth was mapped with contour intervals of 1 mg/m3 and 1 m, respectively. A scene-independent procedure was used to derive the surface temperature of the lake from the TM data with a root mean square error of 0.3 degrees C.

  6. Biological cycling of nitrogen in a Rocky Mountain alpine lake, with emphasis on the physiological and ecological effects of acidification

    SciTech Connect

    Angelo, R.T.

    1989-01-01

    This study examined nitrogen cycling interactions occurring among the heterotrophic and autotrophic plankton of a softwater, oligotrophic alpine lake. Its major objectives were (1) to compare the influences of internal (regenerative) and external nitrogen supply processes on watercolumn primary production, (2) to identify the food web components contributing most to regenerative and assimilative fluxes of nitrogen, and (3) to evaluate the sensitivity of the limnetic nitrogen cycle to lake acidification. Field and laboratory experiments were based on isotopic tracer ({sup 15}N, {sup 14}C, {sup 3}H) methodologies plankton size-fractionation and metabolic inhibitor techniques, and short-term bioassay procedures; supporting data were gathered on lake physicochemical and biological properties. Measured aqueous nutrient concentrations, the results of {sup 14}CO{sub 2}-based snowmelt and nutrient enrichment bioassays, and physiological indicators of algal nutrient status collectively demonstrated that phytoplankton nitrogen demand greatly exceeded nitrogen supply. Both NH{sub 4}{sup +} and NO{sub 3}{sup {minus}} were quantitatively important forms of assimilatable nitrogen under ambient conditions. Mass balance considerations indicated that within-lake biogeochemical processes constituted a net sink for NO{sub 3}{sup {minus}}, whereas NH{sub 4}{sup +} production and consumption rates were approximately in balance on an ecosystem scale. Water-column regenerative and assimilative fluxes of NH{sub 4}{sup +} were strongly correlated. Meta- and protozooplankton were the principal sources of regenerated NH{sub 4}{sup +}; heterotrophic bacterioplankton were net consumers of NH{sub 4} {sup +}. Experimental reductions in metazooplankton populations markedly enhanced rates of NH{sub 4}{sup +} regeneration.

  7. Benthic Diatoms of an Alpine Stream/Lake Network in Switzerland

    NASA Astrophysics Data System (ADS)

    Rueegg, J.; Robinson, C. T.; Kawecka, B.

    2005-05-01

    We compared the benthic diatom composition of lakes, and lake inlet and outlet streams in a high elevation catchment (~2600 m a.s.l.). The catchment was separated in a southern and northern basin with different water sources. Streams in both basins flowed through a series of small lakes before converging into a lake with a primary outlet. The south basin had lower water temperatures and 2× higher nitrate-N levels (up to 300 μg/L) while the north basin had 2-4× higher levels of particulate-P, particulate-N, and particulate organic matter. 143 and 109 diatom species was identified in streams and lakes, respectively, with a similar number of species found in each basin. PCA showed a clear separation between basins. Of the 10 most common species, Psammothidium helveticum, Achnanthes helvetica var. minor, Achnanthes marginulata, Achnanthes subatomoides, and Diatoma mesodon were more abundant in south basin, whereas Achnanthidium minutissimum, Aulacoseira alpigena and Luticola goeppertiana were more abundant in the north. In general, lake outlet assemblages were similar to respective downstream lake inlet assemblages. Composition shifted along each basins longitudinal flow path. The spatial patterns in species composition reflected the hierarchical interaction of landscape features (geology, hydrology) on longitudinal gradients (lake position) in the stream/lake network.

  8. Executive summary - Assessing the response of Emerald Lake, an alpine watershed in Sequoia National Park, California, to acidification during snowmelt using a simple hydrochemical model

    SciTech Connect

    Hooper, R.P.; West, C.T.; Peters, N.E. )

    1990-01-01

    A simple process-oriented model, called the Alpine Lake Forecaster (ALF), was constructed using data collected from the Integrated Watershed Study of Emerald Lake, Sequoia National Park, California. ALF is able to capture the basic solute patterns during snowmelt in this alpine catchment where groundwater is a minor contributor to streamflow. It includes an empirical representation of primary mineral weathering as the only alkalinity generating mechanism. During a heavy snow year, such as the one used for calibrating the model, the model accurately simulated the surface water chemical change in response to the initial ionic pulse from the snowpack and to the dilution that occurs at peak snowmelt. Because the model does not consider cation exchange, it over-predicts the acidification during the initial period of snowmelt, and therefore is a conservative predictor. However, the minimum alkalinity observed in the main inflows to Emerald Lake and in the lake outflow is accurately simulated by the model. The representation of the lake as simply a missing volume with no additional chemical reactions is supported by the observation. The model predicts a change of 2 to 5 microequiv/L in the minimum alkalinity of the lake outflow during snowmelt if the deposition would have to increase between two and 18 times the current load-alkalinity of the lake; the precise increase depends on hydrologic conditions and on the pattern of solute release from the snowpack. An acidic rainstorm that exhausted the alkalinity of the lake was observed during summer 1984 after the lake had stratified, and is the likely cause of the acidification of Emerald Lake.

  9. Assessment of Water Quality in a Subtropical Alpine Lake Using Multivariate Statistical Techniques and Geostatistical Mapping: A Case Study

    PubMed Central

    Liu, Wen-Cheng; Yu, Hwa-Lung; Chung, Chung-En

    2011-01-01

    Concerns about the water quality in Yuan-Yang Lake (YYL), a shallow, subtropical alpine lake located in north-central Taiwan, has been rapidly increasing recently due to the natural and anthropogenic pollution. In order to understand the underlying physical and chemical processes as well as their associated spatial distribution in YYL, this study analyzes fourteen physico-chemical water quality parameters recorded at the eight sampling stations during 2008–2010 by using multivariate statistical techniques and a geostatistical method. Hierarchical clustering analysis (CA) is first applied to distinguish the three general water quality patterns among the stations, followed by the use of principle component analysis (PCA) and factor analysis (FA) to extract and recognize the major underlying factors contributing to the variations among the water quality measures. The spatial distribution of the identified major contributing factors is obtained by using a kriging method. Results show that four principal components i.e., nitrogen nutrients, meteorological factor, turbidity and nitrate factors, account for 65.52% of the total variance among the water quality parameters. The spatial distribution of principal components further confirms that nitrogen sources constitute an important pollutant contribution in the YYL. PMID:21695032

  10. How climate changes in the Rocky Mountains contribute to changes in an alpine lake's phytoplankton community

    NASA Astrophysics Data System (ADS)

    Guido, A. S.; Garland, D.; McKnight, D. M.

    2011-12-01

    It is important to track algae in potable water supplies as they are a factor in the production of dissolved organic matter (DOM) that can result in the formation of disinfection byproducts. Disinfection byproducts have been identified by the Environmental Protection Agency (EPA) as a potential carcinogen and have been linked to reproductive and developmental effects in lab animals. Green Lake 4 is located in the Rocky Mountains and is part of the Silver Lake Watershed which provides 40% of Boulder, CO's potable water supply. In 2002, the Rocky Mountain region had below average precipitation and consequently Green Lake experienced a change in its physical and chemical conditions. As a result of the changes experienced in Green Lake 4, a change in the composition of the phytoplankton community was seen. Along with reduced precipitation levels, this area has also experienced an earlier ice-out date. As part of this research, chemical changes, physical changes, and algae changes in Green Lake 4 will be analyzed. Data from 2007 to 2010 will be analyzed; this study will be looking at both the chemical and physical changes of Green Lake 4 as they relate to the change in ice out of the lake and precipitation in the region.

  11. Extensive and drastically different alpine lake changes on Asia's high plateaus during the past four decades

    NASA Astrophysics Data System (ADS)

    Zhang, Guoqing; Yao, Tandong; Piao, Shilong; Bolch, Tobias; Xie, Hongjie; Chen, Deliang; Gao, Yanhong; O'Reilly, Catherine M.; Shum, C. K.; Yang, Kun; Yi, Shuang; Lei, Yanbin; Wang, Weicai; He, You; Shang, Kun; Yang, Xiankun; Zhang, Hongbo

    2017-01-01

    Asia's high plateaus are sensitive to climate change and have been experiencing rapid warming over the past few decades. We found 99 new lakes and extensive lake expansion on the Tibetan Plateau during the last four decades, 1970-2013, due to increased precipitation and cryospheric contributions to its water balance. This contrasts with disappearing lakes and drastic shrinkage of lake areas on the adjacent Mongolian Plateau: 208 lakes disappeared, and 75% of the remaining lakes have shrunk. We detected a statistically significant coincidental timing of lake area changes in both plateaus, associated with the climate regime shift that occurred during 1997/1998. This distinct change in 1997/1998 is thought to be driven by large-scale atmospheric circulation changes in response to climate warming. Our findings reveal that these two adjacent plateaus have been changing in opposite directions in response to climate change. These findings shed light on the complex role of the regional climate and water cycles and provide useful information for ecological and water resource planning in these fragile landscapes.

  12. Submicron Organic Matter in a Peri-alpine, Ultra-oligotrphic Lake

    SciTech Connect

    Chanudet,V.; Filella, M.

    2007-01-01

    Combining organic carbon (OC) measurements with the classic MBTH (3-methyl-2-benzothiazolinone hydrochloride) method for carbohydrate determination and a new voltammetric method for the determination of refractory organic matter (ROM) made it possible, for the first time, to quantify the types, sources and fate of submicron organic matter present in an ultra-oligotrophic lake (Lake Brienz, Switzerland). The lake is extremely rich in suspended glacial flour in summer (glacier melting season). Measurements were taken from June 2004 to October 2005 from 1.2 {mu}m filtered samples. OC concentration remained extremely low throughout the year (below 1 mg C L{sup -1}). MBTH carbohydrate concentration was very low in the lake (0.06-0.43 mg C L{sup -1}) and in the two tributary rivers (0.06-0.25 mg C L{sup -1}). Lake carbohydrate concentration only correlated with phytoplanktonic biomass at the onset of the productivity period. The results suggest that differences in MBTH concentration may sometimes reflect differences in the nature of the carbohydrates rather than differences in carbon concentration. Extensive fibril formation was evidenced by transmission electron microscopy (TEM) observations. ROM concentration in the lake was also very low (0.1-0.2 mg C L{sup -1}). Significant variation in ROM riverine input was due to either annual occurrences (snow melting) or irregular episodes (floods). Melting snow was responsible for about 30% of the lake's annual ROM input. One box mass balance calculations showed that about 25% of ROM was lost within the lake. Evidence gleaned from TEM and STXM (scanning transmission X-ray microscopy) observations clearly indicates that this is mainly caused by ROM sedimentation after association with inorganic colloids.

  13. Isotopic chemical weathering behaviour of Pb derived from a high-Alpine Holocene lake-sediment record

    NASA Astrophysics Data System (ADS)

    Gutjahr, Marcus; Süfke, Finn; Gilli, Adrian; Anselmetti, Flavio; Glur, Lukas; Eisenhauer, Anton

    2017-04-01

    Several studies assessing the chemical weathering systematics of Pb isotopes provided evidence for the incongruent release of Pb from source rocks during early stages of chemical weathering, resulting in runoff compositions more radiogenic (higher) than the bulk source-rock composition [e.g. 1]. Deep NW Atlantic seawater Pb isotope records covering the last glacial-interglacial transition further support these findings. Clear excursions towards highly radiogenic Pb isotopic input in the deep NW Atlantic seen during the early Holocene, hence after the large-scale retreat of the Laurentide Ice Sheet in North America, are interpreted to be controlled by preferential release of radiogenic Pb from U- and Th-rich mineral phases during early stages of chemical weathering that are less resistant to chemical dissolution than other rock-forming mineral phases [2-4]. To date, however, no terrestrial Pb isotope record exists that could corroborate the evidence from deep marine sites for efficient late deglacial weathering and washout of radiogenic Pb. We present a high-resolution adsorbed Pb isotope record from a sediment core retrieved from Alpine Lake Grimsel (1908 m.a.s.l.) in Switzerland, consisting of 117 Pb compositions over the past 10 kyr. This high-Alpine study area is ideally located for incipient and prolonged chemical weathering studies. The method used to extract the adsorbed lake Pb isotope signal is identical to previous marine approaches targeting the authigenic Fe-Mn oxyhydroxides fraction within the lake sediments [5, 6]. The Pb isotope compositions are further accompanied by various elemental ratios derived from the same samples that equally trace climatic boundary conditions in the Grimsel Lake area. The Pb isotopic composition recorded in Lake Grimsel is remarkably constant throughout the majority of the Holocene until ˜2.5 ka BP, despite variable sediment composition and -age, and isotopically relatively close to the signature of the granitic source rock

  14. Bacterial community composition and diversity in Kalakuli, an alpine glacial-fed lake in Muztagh Ata of the westernmost Tibetan Plateau.

    PubMed

    Liu, Keshao; Liu, Yongqin; Jiao, Nianzhi; Xu, Baiqing; Gu, Zhengquan; Xing, Tingting; Xiong, Jinbo

    2017-07-01

    It is widely accepted that bacterial community composition and diversity in remote alpine lakes are structured by environmental conditions such as nutrient status and temperature. However, the mechanisms that underlie and structure bacterial community composition and diversity in alpine lakes remain unclear. We used 16S rRNA gene-based Illumina MiSeq sequencing to investigate the complex ecological interactions between bacterial communities and nutrient status in Kalakuli Lake, an alpine glacial-fed lake in Muztagh Ata of the westernmost Tibetan Plateau. Our results indicated that the bacterial community was dominated by the Actinobacteria and Proteobacteria. The results of threshold estimates showed that there were apparent shifts in dominance from the Proteobacteria to Actinobacteria groups associated with increasing carbon to nitrogen (C:N) ratio, and the change points were 6.794 and 2.448, respectively. Using multiple statistical methods, we found that the abiotic factors of dissolved organic carbon and total nitrogen had substantial impacts on bacterial diversity, while bacterial community compositions were significantly correlated with both the biotic element of bacterial abundance and the abiotic ones, temperature and pH. These findings demonstrated that the C:N ratio played a significant role in shifting dominant bacterial assemblages in the Kalakuli watershed and provided evidence of nutrients affecting bacterial community composition and diversity. We argue that this study could further shed light on how climate change-induced glacial retreat may impact bacterial communities in glacial-fed lakes under future global warming scenarios. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Comparison of optical properties of chromophoric dissolved organic matter (CDOM) in alpine lakes above or below the tree line: insights into sources of CDOM.

    PubMed

    Su, Yaling; Chen, Feizhou; Liu, Zhengwen

    2015-05-01

    Here we investigated absorption and fluorescence properties of chromophoric dissolved organic matter (CDOM) in 15 alpine lakes located below or above the tree line to determine its source and composition. The results indicate that the concentrations of CDOM in below-tree-line lakes are significantly higher than in above-tree-line lakes, as evidenced from the absorption coefficients of a250 and a365. The intensities of the protein-like and humic-like fluorescence in below-tree-line lakes are higher than in above-tree-line lakes as well. Three fluorescent components were identified using parallel factor analysis (PARAFAC) modelling. Component 1 is probably associated with biological degradation of terrestrial humic component. The terrestrial humic-like component 2 is only found in below-tree-line lakes. The protein-like or phenolic component 3 is dominant in above-tree-line lakes, which is probably more derived from autochthonous origin. In this study, (1) higher a250/a365 and S275-295 values indicate smaller molecular weights of CDOM in above-tree-line lakes than in below-tree-line lakes, and smaller molecular weights at the surface than at 2.0 m depth; (2) SUVA254 and FI255 results provide evidence of lower percent aromaticity of CDOM in above-tree-line lakes; and (3) FI310 and FI370 suggest a strong allochthonous origin at the surface in below-tree-line lakes, and more contribution from autochthonous biological and aquatic bacterial origin in above-tree-line lakes.

  16. Atmospheric deposition of particles at a sensitive alpine lake: Size-segregated daily and annual fluxes from passive sampling techniques.

    PubMed

    Tai, Anna Y-C; Chen, L-W Antony; Wang, Xiaoliang; Chow, Judith C; Watson, John G

    2017-02-01

    Lake Tahoe, a North American alpine lake long appreciated for its clear water and geographic setting, has experienced a trend of declining water clarity due to increasing nutrient and particle inputs. Contributions from atmospheric deposition of particulate matter (PM) could be important, yet they are inadequately quantified. This study established a yearlong deposition monitoring network in the northern Lake Tahoe Basin. Dry deposition was quantified on surrogate surfaces while wet deposition was based on particles suspended in precipitation at 24-hour resolution. The particle size ranges by these passive techniques were 1-64μm and 0.5-20μm in diameter for dry and wet deposition, respectively. Dry deposition of submicrometer (0.5-1μm) particles was also estimated by extrapolation of a lognormal size distribution. Higher daily number deposition fluxes (NDFdry and NDFwet) were found at a near-shore site, confirming substantial impacts of commercial and tourist activities. The two more isolated sites indicated a uniform regional background. On average, daily NDFdry is about one order of magnitude lower than daily NDFwet. Dry deposition velocities increased rapidly with particle size, as evidenced by collocated measurements of NDFdry and ambient particle number concentrations, though it seems less so for wet deposition due to different scavenging mechanisms. Despite fewer "wet" days than "dry" days during the monitoring period, wet processes dominated seasonal particle deposition, particularly in winter and spring when most precipitation occurred. Adopting sediment (insoluble, inorganic) particle fraction estimates from the literature, this study reports an annual particle flux of 2.9-5.2×10(10)#m(-2)yr(-1) for sediment particles with 1-20μm diameter and 6.1-11×10(10)#m(-2)yr(-1) for those with 0.5-20μm diameter. Implications of these findings to the current knowledge of atmospheric deposition in the Lake Tahoe Total Maximum Daily Load (TMDL) are discussed

  17. BrGDGT-based quantitative temperature reconstruction over the past 2000 years from an alpine lake in subtropical southwestern China

    NASA Astrophysics Data System (ADS)

    Feng, X.; Zhao, C.

    2016-12-01

    Understand the nature of climate change over the past 2000 years is important to predict future climate change, which would influenced by both anthropogenic and natural forcing. However, limited paleoclimate data have been reported for quantitative temperature reconstruction in the tropical and subtropical region, the source region of the major moisture and heat in global climate system. In this study, we report a quantitative temperature record inferred from branched GDGTs from a sediment core collected at a small alpine lake (Tiancai lake, 26°38'E, 99°43'N, 3898 m asl) in a remote location in subtropical southwestern China. The chronology is well established by both 210Pb and AMS-14C dating methods. We find a significant correlation between brGDGT distributions and instrumental mean annual air temperature (MAAT) (R2=0.84, p<0.001) over the past 60 years. We then establish a local instrumental calibration and apply it to the entire core for MAAT reconstruction over the past 2000 years. Our preliminary results show the reconstructed MAAT varies between 1.11 and 2.87° over the past 2000 years, similar to the instrumental MAAT( 2.24°). Our data indicate four warm intervals at 20-151AD, 373-520AD, 796-1306AD and after 1940AD, and four cold intervals at 182-340AD, 550-643AD, 1540-1736AD, 1810-1948AD. The warm period at 796-1306AD and the cold period at 1540-1736AD are likely corresponding with the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA), respectively, which is consistent with published data in northern China and the northern Hemisphere but shows a higher amplitude of temperature changes. Our result suggests coherent temperature changes in the subtropical and high-latitude northern hemisphere over the past 2000 years, and probably indicate more pronounced centennial-scale climate variations at high-altitude mountain regions.

  18. Chemical characterization of dissolved organic matter in an alpine stream from thawing and collapsing permafrost to Qinghai Lake

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Xu, Y.

    2016-12-01

    The Tibetan Plateau is the world's largest and highest plateau, approximately two thirds of which is covered by permafrost. Due to recent climate warming, large organic carbon stored in the permafrost is thawing and becomes available for transport to aquatic ecosystems (i.e., stream and lake) as dissolved organic matter (DOM) and fine particulate organic matter (POM). These DOM and POM are not only important food sources for the aquatic food web, but also a significant feedback if remineralized during transport. In this work, we collected water samples along a stream from the headwater in the Permafrost region to the downstream in the Qinghai Lake. The concentration and composition of DOM were determined using high temperature combustion analysis, UV- Vis absorption spectroscopy and fluorescence spectroscopy. The concentration of dissolved organic carbon decreased sharply from 13.87 mg/L to 4.32 mg/L from collapsing permafrost area (3850 m a.s.l.) to the foot of the mountain (3200 m a.s.l.), and then fluctuated in a narrow range between 3.00 mg/L and 4.50 mg/L. The DOM with high humic-like fluorescence, specific UV absorbance (SUVA254), and low spectral slope ratio (S275-295) and fluorescence index (FI) was observed in the headwater, which was distinct difference from that at the middle and downstream area where the DOM are less aromatic and low molecular weight. Meanwhile, the freshness index (β/α) increased slightly in mid and down-stream. This increasing trend for FI and β/α indicated a contribution of recently in situ produced DOM by aquatic bacteria and algae in the stream. We speculate that the biological process is an important way to cause the chemical change of DOM composition and concentration, and therefore the thawing and transport of permafrost carbon may play a key role in sustaining the alpine stream ecosystem.

  19. Drought alters carbon fluxes in alpine snowbed ecosystems through contrasting impacts on graminoids and forbs.

    PubMed

    Johnson, David; Vachon, Jérémie; Britton, Andrea J; Helliwell, Rachel C

    2011-05-01

    • Climate change is predicted to increase the frequency of drought events in alpine ecosystems with the potential to affect carbon turnover. • We removed intact turfs from a Nardus stricta alpine snowbed community and subjected half of them to two drought events of 8 d duration under controlled conditions. Leachate dissolved organic carbon (DOC) was measured throughout the 6 wk study period, and a (13)CO(2) pulse enabled quantification of fluxes of recent assimilate into shoots, roots and leachate and ecosystem CO(2) exchange. • The amount of DOC in leachate from droughted cores was 62% less than in controls. Drought reduced graminoid biomass, increased forb biomass, had no effect on bryophytes, and led to an overall decrease in total above-ground biomass compared with controls. Net CO(2) exchange, gross photosynthesis and the amount of (13)CO(2) fixed were all significantly less in droughted turfs. These turfs also retained proportionally more (13)C in shoots, allocated less (13)C to roots, and the amount of dissolved organic (13)C recovered in leachate was 57% less than in controls. • Our data show that drought events can have significant impacts on ecosystem carbon fluxes, and that the principal mechanism behind this is probably changes in the relative abundance of forbs and grasses.

  20. Effects of Short-Term Warming and Altered Precipitation on Soil Microbial Communities in Alpine Grassland of the Tibetan Plateau

    PubMed Central

    Zhang, Kaoping; Shi, Yu; Jing, Xin; He, Jin-Sheng; Sun, Ruibo; Yang, Yunfeng; Shade, Ashley; Chu, Haiyan

    2016-01-01

    Soil microbial communities are influenced by climate change drivers such as warming and altered precipitation. These changes create abiotic stresses, including desiccation and nutrient limitation, which act on microbes. However, our understanding of the responses of microbial communities to co-occurring climate change drivers is limited. We surveyed soil bacterial and fungal diversity and composition after a 1-year warming and altered precipitation manipulation in the Tibetan plateau alpine grassland. In isolation, warming and decreased precipitation treatments each had no significant effects on soil bacterial community structure; however, in combination of both treatments altered bacterial community structure (p = 0.03). The main effect of altered precipitation specifically impacted the relative abundances of Bacteroidetes and Gammaproteobacteria compared to the control, while the main effect of warming impacted the relative abundance of Betaproteobacteria. In contrast, the fungal community had no significant response to the treatments after 1-year. Using structural equation modeling (SEM), we found bacterial community composition was positively related to soil moisture. Our results indicate that short-term climate change could cause changes in soil bacterial community through taxonomic shifts. Our work provides new insights into immediate soil microbial responses to short-term stressors acting on an ecosystem that is particularly sensitive to global climate change. PMID:27446064

  1. Effects of Short-Term Warming and Altered Precipitation on Soil Microbial Communities in Alpine Grassland of the Tibetan Plateau.

    PubMed

    Zhang, Kaoping; Shi, Yu; Jing, Xin; He, Jin-Sheng; Sun, Ruibo; Yang, Yunfeng; Shade, Ashley; Chu, Haiyan

    2016-01-01

    Soil microbial communities are influenced by climate change drivers such as warming and altered precipitation. These changes create abiotic stresses, including desiccation and nutrient limitation, which act on microbes. However, our understanding of the responses of microbial communities to co-occurring climate change drivers is limited. We surveyed soil bacterial and fungal diversity and composition after a 1-year warming and altered precipitation manipulation in the Tibetan plateau alpine grassland. In isolation, warming and decreased precipitation treatments each had no significant effects on soil bacterial community structure; however, in combination of both treatments altered bacterial community structure (p = 0.03). The main effect of altered precipitation specifically impacted the relative abundances of Bacteroidetes and Gammaproteobacteria compared to the control, while the main effect of warming impacted the relative abundance of Betaproteobacteria. In contrast, the fungal community had no significant response to the treatments after 1-year. Using structural equation modeling (SEM), we found bacterial community composition was positively related to soil moisture. Our results indicate that short-term climate change could cause changes in soil bacterial community through taxonomic shifts. Our work provides new insights into immediate soil microbial responses to short-term stressors acting on an ecosystem that is particularly sensitive to global climate change.

  2. Direct versus indirect climate controls on Holocene diatom assemblages in a sub-tropical deep, alpine lake (Lugu Hu, Yunnan, SW China)

    NASA Astrophysics Data System (ADS)

    Wang, Qian; Yang, Xiangdong; Anderson, Nicholas John; Dong, Xuhui

    2016-07-01

    The reconstruction of Holocene environmental changes in lakes on the plateau region of southwest China provides an understanding of how these ecosystems may respond to climate change. Fossil diatom assemblages were investigated from an 11,000-year lake sediment core from a deep, alpine lake (Lugu Hu) in southwest China, an area strongly influenced by the southwest (or the Indian) summer monsoon. Changes in diatom assemblage composition, notably the abundance of the two dominant planktonic species, Cyclotella rhomboideo-elliptica and Cyclostephanos dubius, reflect the effects of climate variability on nutrient dynamics, mediated via thermal stratification (internal nutrient cycling) and catchment-vegetation processes. Statistical analyses of the climate-diatom interactions highlight the strong effect of changing orbitally-induced solar radiation during the Holocene, presumably via its effect on the lake's thermal budget. In a partial redundancy analysis, climate (solar insolation) and proxies reflecting catchment process (pollen percentages, C/N ratio) were the most important drivers of diatom ecological change, showing the strong effects of climate-catchment-vegetation interactions on lake functioning. This diatom record reflects long-term ontogeny of the lake-catchment ecosystem and suggests that climatic changes (both temperature and precipitation) impact lake ecology indirectly through shifts in thermal stratification and catchment nutrient exports.

  3. Annual hydrochemical budgets (1989-2009) and their variability and annual trends for two alpine lake catchments, Snowy Range, Wyoming, USA

    NASA Astrophysics Data System (ADS)

    Stednick, J. D.; Fassnacht, S. R.; Musselman, R. C.

    2011-12-01

    The Glacier Lakes Ecosystem Experiments Site (GLEES) is an alpine-subalpine study area located in the Snowy Range of southern Wyoming approximately 55 km west of Laramie, Wyoming and managed by the USDA Forest Service. GLEES was established in 1986 to study the effects of atmospheric deposition and climate change on alpine-subalpine aquatic and terrestrial ecosystems. Two small coterminous alpine lake catchments, West Glacier Lake and East Glacier Lake have been sampled for precipitation chemistry by the National Atmospheric Deposition Program and dry deposition by CASTNET and streamflow chemistry by the USDA Forest Service. This presentation analyses historical variability and trends in these inputs and outputs over the 21-year monitoring period (1989-2009). The average annual precipitation at GLEES is 1225mm with 85% as snow. The coefficient of variation for annual precipitation was 15%. The annual snowmelt peak flow rate had a coefficient of variation of 33%, while annual water yield varied up to 92%. The mean coefficient of variation for annual precipitation chemistry inputs was 31%, and the variability highest in the nitrogen species. Significant decreases over time were detected in precipitation chemistry for Na+ and Cl- , no other trends were detected. Streamflow outputs were calculated from streamflow chemistry and flow volumes. Even with dilute chemistry (<5mg/L TDS) preferential elution was observed with snowmelt. No significant trends were detected in streamflow chemistry. Variability in streamflow chemistry was greatest for the nitrogen species. There were no significant temporal trends in streamflow outputs. Unlike some Front Range catchments, significant nitrogen retention was observed at GLEES.

  4. Forest Gaps Alter the Total Phenol Dynamics in Decomposing Litter in an Alpine Fir Forest.

    PubMed

    Li, Han; Xu, Liya; Wu, Fuzhong; Yang, Wanqin; Ni, Xiangyin; He, Jie; Tan, Bo; Hu, Yi

    2016-01-01

    The total phenol content in decomposing litter not only acts as a crucial litter quality indicator, but is also closely related to litter humification due to its tight absorption to clay particles. However, limited attention has been focused on the total phenol dynamics in foliar litter in relation to forest gaps. Here, the foliar litter of six representative tree species was incubated on the forest floor from the gap center to the closed canopy of an alpine Minjiang fir (Abies faxoniana) forest in the upper reaches of the Yangtze River and eastern Tibetan Plateau. The dynamics of total phenol concentration in the incubated litter was measured from November 2012 to October 2014. Over two-year incubation, 78.22% to 94.06% of total phenols were lost from the foliar litter, but 52.08% to 86.41% of this occurred in the first year. Forest gaps accelerated the loss of total phenols in the foliar litter in the winter, although they inhibited the loss of total phenols during the growing season in the first year. In comparison with the effects of forest gaps, the variations of litter quality among different species were much stronger on the dynamics of total phenols in the second year. Overall, the loss of total phenols in the foliar litter was slightly higher in both the canopy gap and the expanded gap than in the gap center and under the closed canopy. The results suggest that the predicted decline in snow cover resulting from winter warming or vanishing gaps caused by forest regeneration will retard the loss of total phenol content in the foliar litter of alpine forest ecosystems, especially in the first decomposition year.

  5. Forest Gaps Alter the Total Phenol Dynamics in Decomposing Litter in an Alpine Fir Forest

    PubMed Central

    Li, Han; Xu, Liya; Wu, Fuzhong; Yang, Wanqin; Ni, Xiangyin; He, Jie; Tan, Bo; Hu, Yi

    2016-01-01

    The total phenol content in decomposing litter not only acts as a crucial litter quality indicator, but is also closely related to litter humification due to its tight absorption to clay particles. However, limited attention has been focused on the total phenol dynamics in foliar litter in relation to forest gaps. Here, the foliar litter of six representative tree species was incubated on the forest floor from the gap center to the closed canopy of an alpine Minjiang fir (Abies faxoniana) forest in the upper reaches of the Yangtze River and eastern Tibetan Plateau. The dynamics of total phenol concentration in the incubated litter was measured from November 2012 to October 2014. Over two-year incubation, 78.22% to 94.06% of total phenols were lost from the foliar litter, but 52.08% to 86.41% of this occurred in the first year. Forest gaps accelerated the loss of total phenols in the foliar litter in the winter, although they inhibited the loss of total phenols during the growing season in the first year. In comparison with the effects of forest gaps, the variations of litter quality among different species were much stronger on the dynamics of total phenols in the second year. Overall, the loss of total phenols in the foliar litter was slightly higher in both the canopy gap and the expanded gap than in the gap center and under the closed canopy. The results suggest that the predicted decline in snow cover resulting from winter warming or vanishing gaps caused by forest regeneration will retard the loss of total phenol content in the foliar litter of alpine forest ecosystems, especially in the first decomposition year. PMID:26849120

  6. The influences of the AMO and NAO on an Iberian alpine lake during the Late Holocene

    NASA Astrophysics Data System (ADS)

    Hernández, Armand; Leira, Manel; Trigo, Ricardo; Vázquez-Loureiro, David; Carballeira, Rafael; Sáez, Alberto

    2017-04-01

    High mountain lakes, usually oligotrophic, in the Iberian Peninsula are particularly sensitive to the influence of North Atlantic large-scale modes of climate variability due to their geographical position and the reduced direct anthropic disturbances. In this context, Serra da Estrela (Portugal), in the westernmost of the Sistema Central Range, constitutes a physical barrier to air masses coming from the Atlantic Ocean. However, long-term climate reconstructions have not yet been conducted. We present a climate reconstruction in terms of precipitation and temperature changes of this setting based on facies analysis, X-ray fluorescence core scanning, elemental and isotope geochemistry on bulk organic matter and a preliminary study of diatom assemblages from the sedimentary record of Lake Peixão (1677 m a.s.l.; Serra da Estrela) for the last ca. 3500 years. A multivariate statistical analysis has been performed to recognize the main environmental factors controlling the lake sedimentation. Our results reveal that two main processes explain 70% of the total variance, with PC1 (accumulation of siliciclastic material vs organic matter), and PC2 (variations in lacustrine productivity, related to nutrient inputs from the catchment), explaining 53% and 17% respectively. In mountain lakes, siliciclastic and/or external organic matter accumulation tend to be governed by the snowmelt which, in turn, are frequently controlled by winter and spring temperatures. On the other hand, lake productivity, usually limited by phosphorus and nitrogen, is dependent of internal recycling and/or external inputs, mainly by catchment leaching (climatically driven by summer precipitation) and atmospheric deposition (anthropic influence). The results from Lake Peixão have been compared to other Western Iberia and Northeastern Atlantic records, as well as the Atlantic Multidecadal Oscillation (AMO) and North Atlantic Oscillation (NAO) indices. Thus, a tentative Late Holocene climate

  7. Epigenetic programming alterations in alligators from environmentally contaminated lakes.

    PubMed

    Guillette, Louis J; Parrott, Benjamin B; Nilsson, Eric; Haque, M M; Skinner, Michael K

    2016-11-01

    Previous studies examining the reproductive health of alligators in Florida lakes indicate that a variety of developmental and health impacts can be attributed to a combination of environmental quality and exposures to environmental contaminants. The majority of these environmental contaminants have been shown to disrupt normal endocrine signaling. The potential that these environmental conditions and contaminants may influence epigenetic status and correlate to the health abnormalities was investigated in the current study. The red blood cell (RBC) (erythrocyte) in the alligator is nucleated so was used as an easily purified marker cell to investigate epigenetic programming. RBCs were collected from adult male alligators captured at three sites in Florida, each characterized by varying degrees of contamination. While Lake Woodruff (WO) has remained relatively pristine, Lake Apopka (AP) and Merritt Island (MI) convey exposures to different suites of contaminants. DNA was isolated and methylated DNA immunoprecipitation (MeDIP) was used to isolate methylated DNA that was then analyzed in a competitive hybridization using a genome-wide alligator tiling array for a MeDIP-Chip analysis. Pairwise comparisons of alligators from AP and MI to WO revealed alterations in the DNA methylome. The AP vs. WO comparison identified 85 differential DNA methylation regions (DMRs) with ⩾3 adjacent oligonucleotide tiling array probes and 15,451 DMRs with a single oligo probe analysis. The MI vs. WO comparison identified 75 DMRs with the ⩾3 oligo probe and 17,411 DMRs with the single oligo probe analysis. There was negligible overlap between the DMRs identified in AP vs. WO and MI vs. WO comparisons. In both comparisons DMRs were primarily associated with CpG deserts which are regions of low CpG density (1-2CpG/100bp). Although the alligator genome is not fully annotated, gene associations were identified and correlated to major gene class functional categories and pathways of

  8. The changing microstructural arrangement of graphite during deformation and hydrothermal alteration of amphibolite-facies mylonite, Alpine Fault, New Zealand.

    NASA Astrophysics Data System (ADS)

    Kirilova, M.; Toy, V.; Timms, N.; Craw, D.; Little, T. A.; Halfpenny, A.; Beyssac, O.

    2015-12-01

    Graphitisation in a convergent plate boundary setting, such as the Alpine Fault, New Zealand, is associated both with fault weakening and orogenic gold mineralisation. Previously, these processes have been investigated in rocks that experienced mineralisation at maximum of greenschist-facies conditions. However, metals are most mobile at upper greenschist- to amphibolite-facies. We examine the microstructural record of mobilisation of graphite at these conditions due to dislocation and diffusion creep in the Alpine Fault zone and as a function of varying shear strain magnitude. We have mapped graphite distribution across a strain gradient in samples, recovered from Deep Fault Drilling Project (DFDP) boreholes, by using reflected light and scanning electron microscopy. Raman spectrometry was used to determine the degree of maturity of the carbonaceous material. In the schists and protomylonites, graphite occurs as very fine (1-5μm), dusty grains, dispersed as inclusions in the main mineral phases (quartz, anorthite, muscovite, biotite). Further into the mylonite zone, the modal proportion of graphite increases and it forms clusters and trains, aligned with the foliation. In the brittlely-deformed rocks (cataclasites and gouges on or near the fault principal slip zone) graphite is most abundant (<50%), occurring as clusters and shear plane parallel trains. We infer shear deformation under both ductile and brittle conditions concentrates the graphite. Independent evidence demonstrates fluid transport and consequent alteration was most important in the brittlely deformed rocks (Sutherland et al., 2012, Geology 40, 1143; Schleicher et al., in press. N.Z.J.Geol&Geophys). We thus infer hydrothermal enrichment caused graphite remobilization, re-deposition, and enrichment in structurally controlled microstructural sites. We will discuss implications of these microstructural and mineralogical changes for strain localisation and deformation-induced permeability.

  9. Climate variability during the deglaciation and Holocene in a high-altitude alpine lake deduced from the sedimentary record from Laguna Seca, Sierra Nevada, southern Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Camuera, Jon; Jiménez-Moreno, Gonzalo; José Ramos-Román, María; García-Alix, Antonio; Jiménez-Espejo, Francisco; Anderson, R. Scott

    2017-04-01

    High-resolution X-ray fluorescence (XRF), magnetic susceptibility (MS), color and lithological analyses have been carried out on a 3.6 m-long sediment core from Laguna Seca, a high-elevation dry lake from Sierra Nevada mountain range, southern Spain. This is the longest sedimentary record retrieved from an alpine lake in southern Iberian Peninsula. Besides, alpine lakes are very sensitive environments to climate changes and previous studies showed that Laguna Seca could provide an excellent record to identify millennial-scale climate variations during deglaciation and the whole Holocene. XRF analyses, in particular high calcium and low K/Ca ratios, show aridity phases, very well represented during Last Glacial Maximum (LGM) and the Younger Dryas (YD). Arid events are also shown at ca. 8.1 ka BP, ca. 4.4 ka BP and the latest Holocene. On the other hand, negative values in calcium and positive values in K/Ca appear in the Bølling-Allerød (BA) and during the early Holocene until ca. 6 ka BP, indicating more humidity and higher run-off. A progressive aridification trend is also observed in the Holocene, changing from more humid conditions during the early Holocene to more aridity during the late Holocene.

  10. In situ determination of sulfide turnover rates in a meromictic alpine lake

    SciTech Connect

    Luethy, L.; Fritz, M.; Bachofen, R.

    2000-02-01

    A push-pull method, previously used in groundwater analyses, was successfully adapted for measuring sulfide turnover rates in situ at different depths in the meromictic Lake Cadagno. In the layer of phototrophic bacteria at about 12 m in depth net sulfide consumption was observed during the day, indicating active bacterial photosynthesis. During the night the sulfide turnover rates were positive, indicating a net sulfide production from the reduction of more-oxidized sulfur compounds. Because of lack of light, no photosynthesis takes place in the monimolimnion; thus, only sulfide formation is observed both during the day and the night. Sulfide turnover rates in the oxic mixolimnion were always positive as sulfide is spontaneously oxidized by oxygen and as the rates of sulfide oxidation depend on the oxygen concentrations present. Sulfide oxidation by chemolithotrophic bacteria may occur at the oxicline, but this cannot be distinguished from spontaneous chemical oxidation.

  11. In Situ Determination of Sulfide Turnover Rates in a Meromictic Alpine Lake

    PubMed Central

    Lüthy, Lucas; Fritz, Markus; Bachofen, Reinhard

    2000-01-01

    A push-pull method, previously used in groundwater analyses, was successfully adapted for measuring sulfide turnover rates in situ at different depths in the meromictic Lake Cadagno. In the layer of phototrophic bacteria at about 12 m in depth net sulfide consumption was observed during the day, indicating active bacterial photosynthesis. During the night the sulfide turnover rates were positive, indicating a net sulfide production from the reduction of more-oxidized sulfur compounds. Because of lack of light, no photosynthesis takes place in the monimolimnion; thus, only sulfide formation is observed both during the day and the night. Sulfide turnover rates in the oxic mixolimnion were always positive as sulfide is spontaneously oxidized by oxygen and as the rates of sulfide oxidation depend on the oxygen concentrations present. Sulfide oxidation by chemolithotrophic bacteria may occur at the oxicline, but this cannot be distinguished from spontaneous chemical oxidation. PMID:10653740

  12. Spatial and Temporal Variability of Near-Shore Clarity in an Alpine Lake

    NASA Astrophysics Data System (ADS)

    Shanafield, M.; Taylor, K.; Susfalk, R.

    2003-12-01

    Spatial and temporal variability in localized near-shore locations of Lake Tahoe, CA/NV was investigated using turbidity and light attenuation measurements. Between 2001 and 2003, several areas were identified as turbidity hotspots and chosen for further study. The effects of storms, high winds, snowmelt runoff, and calm conditions on clarity were monitored at these areas. Data was continuously collected at a depth of one meter and displayed in real time. A comparison of the spatially plotted results shows an increase in turbidity after storms and during runoff events concentrated around the Upper Truckee River, Bijou Creek, and Edgewood Creek. Turbidity values ranged from 0.17 ntu in unaffected areas to up to 20 ntu in the most concentrated sections of the plume. In addition to the turbidity measurements, particle analysis was undertaken on water from three areas adjacent streams and from a distance of two kilometers off the mouth of the Upper Truckee River. Particles collected on a 0.1 micron filter

  13. Compound-specific stable isotopes of organic compounds from lake sediments track recent environmental changes in an alpine ecosystem, Rocky Mountain National Park, Colorado

    USGS Publications Warehouse

    Enders, S.K.; Pagani, M.; Pantoja, S.; Baron, J.S.; Wolfe, A.P.; Pedentchouk, N.; Nunez, L.

    2008-01-01

    Compound-specific nitrogen, carbon, and hydrogen isotope records from sediments of Sky Pond, an alpine lake in Rocky Mountain National Park (Colorado, United States of America), were used to evaluate factors contributing to changes in diatom assemblages and bulk organic nitrogen isotope records identified in lake sediments across Colorado, Wyoming, and southern Montana. Nitrogen isotopic records of purified algal chlorins indicate a substantial shift in nitrogen cycling in the region over the past ???60 yr. Temporal changes in the growth characteristics of algae, captured in carbon isotope records in and around Sky Pond, as well as a -60??? excursion in the hydrogen isotope composition of algal-derived palmitic acid, are coincident with changes in nitrogen cycling. The confluence of these trends is attributed to an increase in biologically available nitrogenous compounds caused by an expansion of anthropogenic influences and temporal changes in catchment hydrology and nutrient delivery associated with meltwater dynamics. ?? 2008, by the American Society of Limnology and Oceanography, Inc.

  14. Reconstruction of atmospheric trace metals pollution in Southwest China using sediments from a large and deep alpine lake: Historical trends, sources and sediment focusing.

    PubMed

    Lin, Qi; Liu, Enfeng; Zhang, Enlou; Nath, Bibhash; Shen, Ji; Yuan, Hezhong; Wang, Rong

    2017-09-13

    Atmospheric pollution, one of the leading environmental problems in South and East Asia, and its impact on the terrestrial environmental quality remain poorly understood particularly in alpine areas where both historical and present-day mining and smelting operations might leave an imprint. Here, we reconstructed atmospheric trace metals pollution during the past century using core sediments from a large and deep alpine lake in Southwest China. The implication of in lake and/or in watershed sediment focusing in pollution quantification is discussed by analyzing 15 sediment cores. Factor analysis and enrichment factor indicated Cd, Pb and Sb as the typical pollutants. Distinct peaks of Pb and Sb pollution were observed around the 1920s, but little Pb pollution was detected in recent decades, different from other studies in similar regions. Cadmium pollution was observed until the mid-1980s synchronized with Sb. The distinctive variations in atmospheric trace metal pollution process in Southwest China highlight the regional and sub-regional sources of metal pollutants, which should be primarily attributed to non-ferrous metal smelting emissions. Both natural and anthropogenic metals showed wide concentration ranges though exhibited similar temporal trends in the 15 cores. Spatial variations of anthropogenic metals were influenced by the in-watershed pollutants remobilization, whereas, natural metals were regulated by the detrital materials in the sub-basin. In-lake sediment focusing had little influence on the spatial distributions of all metals, different from the traditional sediment focusing pattern observed in small lakes. Anthropogenic Cd accumulation in sediments ranged from 1.5 to 10.1mgm(-2) in a specific core with an average of 6.5mgm(-2) for the entire lake, highlighting that a reliable whole-lake pollutant budget requires an analysis of multiple cores. Our study suggests that the management of aquatic ecosystem health should take the remobilization of in

  15. Large eddy simulation (LES) of wind-driven circulation in a peri-alpine lake: Detection of turbulent structures and implications of a complex surrounding orography

    NASA Astrophysics Data System (ADS)

    Santo, Marco A.; Toffolon, Marco; Zanier, Giulia; Giovannini, Lorenzo; Armenio, Vincenzo

    2017-06-01

    We investigate wind-driven circulation in a peri-alpine lake (Lake Ledro - Italy) using LES-COAST. Lake Ledro is interesting because its own dimensions are suited for LES and it is surrounded by complex orography, affecting wind distribution. We consider the winter condition when stratification is nearly absent. Two types of time-varying wind stress are used: spatially homogeneous and spatially inhomogeneous respectively. The analysis of the eddy viscosities shows substantial differences with respect to the ocean case characterized by absence of coastal boundaries and homogeneous, steady wind. The quantities exhibit a noticeable inhomogeneous behavior: the horizontal eddy viscosity is larger in the water body far from the boundaries, whereas the vertical one is larger close to the lateral boundaries due to the presence of a boundary layer. The energetic bottom boundary layer, typically occurring in lakes, is not present. This because of the intrinsic unsteadiness of the thermal wind blowing over the lake and due to the absence of large amplitude internal waves, the latter present only in case of stable stratification. In the inhomogeneous wind case, up-welling and down-welling areas are not confined along the shoreline only, but are also generated in the water body due to substantial horizontal velocity divergence, and turbulent mixing, quantified by eddy viscosities, TKE and its dissipation rate, appears enhanced with respect to the homogeneous wind case. Finally, downwelling/upwelling areas along the windward/leeward coastline respectively were observed, whose quantitative estimation may give explanation for the bloom of cyanobacteria at the lake surface observed in winter.

  16. Assessing the response of Emerald Lake, an alpine watershed in Sequoia National Park, California, to acidification during snowmelt by using a simple hydrochemical model

    SciTech Connect

    Hooper, R.P.; West, C.T.; Peters, N.E. )

    1990-01-01

    A sparsely parameterized hydrochemical model has been developed by using data from Emerald Lake watershed, which is a 120-ha alpine catchment in Sequoia National Park, California. Greater than 90% of the precipitation to this watershed is snow; hence, snowmelt is the dominant hydrologic event. A model which uses a single alkalinity-generating mechanism, primary mineral weathering, was able to capture the pattern of solute concentrations in surface waters during snowmelt. An empirical representation of the weathering reaction, which is based on rock weathering stoichiometry and which uses discharge as a measure of residence time, was included in the model. Results of the model indicate that current deposition levels would have to be increased between three-fold and eight-fold to exhaust the alkalinity of the lake during snowmelt if their is a mild acidic pulse in the stream at the beginning of snowmelt as was observed during the study period. The acidic pulse in the inflow stream at the onset of snowmelt was less pronounced than acidic pulses observed in the meltwater draining the snowpack at a point using snow lysimeters or in the laboratory. Sulfate concentrations in the stream water were the most constant; chloride and nitrate concentrations increased slightly at the beginning of snowmelt. Additional field work is required to resolve whether an acidic meltwater pulse occurs over a large area as well as at a point or whether, due to physical and chemical processes within the snowpack, the acidic meltwater pulse is attenuated at the catchment scale. The modest data requirements of the model permit its applications to other alpine watersheds that are much less intensively studied than Emerald Lake watershed.

  17. Sedimentary records of metal deposition in Japanese alpine lakes for the last 250 years: recent enrichment of airborne Sb and In in East Asia.

    PubMed

    Kuwae, Michinobu; Tsugeki, Narumi K; Agusa, Tetsuro; Toyoda, Kazuhiro; Tani, Yukinori; Ueda, Shingo; Tanabe, Shinsuke; Urabe, Jotaro

    2013-01-01

    Concentrations of 18 elements, including Sb, In, Sn, and Bi, were measured in sediment cores from two pristine alpine lakes on Mount Hachimantai, northern Japan, representing the past 250 years. Vertical variations in concentrations are better explained by atmospheric metal deposition than by diagenetic redistribution of Fe and Mn hydroxide and organic matter. Anthropogenic metal fluxes were estimated from (210)Pb-derived accumulation rates and metal concentrations in excess of the Al-normalized mean background concentration before 1850. Anthropogenic fluxes of Sb and In showed gradual increases starting around 1900 in both lakes, and marked increases after 1980. Comparison of Sb/Pb and Pb stable isotope ratios in sediments with those in aerosols of China or northern Japan and Japanese source materials (recent traffic- and incinerator-derived dust) suggest that the markedly elevated Sb flux after 1980 resulted primarily from enhanced long-range transport in aerosols containing Sb and Pb from coal combustion on the Asian continent. The fluxes of In, Sn, and Bi which are present in Chinese coal showed increasing trends similar to Sb for both study lakes. This suggests that the same source although incinerators in Japan may not be ruled out as sources of In. The sedimentary records for the last 250 years indicate that atmospheric pollution of Sb and In in East Asia have intensified during recent decades.

  18. Alpine ecosystems

    Treesearch

    P.W. Rundel; C.I. Millar

    2016-01-01

    Alpine ecosystems are typically defined as those areas occurring above treeline, while recognizing that alpine ecosystems at a local scale may be found below this boundary for reasons including geology, geomorphology, and microclimate. The lower limit of the alpine ecosystems, the climatic treeline, varies with latitude across California, ranging from about 3500 m in...

  19. Response of the phytoplankton community to water quality in a local alpine glacial lake of Xinjiang Tianchi, China: potential drivers and management implications.

    PubMed

    Lu, Xiaotian; Song, Shuai; Lu, Yonglong; Wang, Tieyu; Liu, Zhaoyang; Li, Qifeng; Zhang, Meng; Suriyanarayanan, Sarvajayakesavalu; Jenkins, Alan

    2017-08-31

    Eutrophication has become one of the most serious threats to aquatic ecosystems in the world. With the combined drivers of climate change and human activities, eutrophication has expanded from warm shallow lakes to cold-water lakes in relatively high latitude regions and has raised greater concerns over lake aquatic ecosystem health. A two-year field study was carried out to investigate water quality, phytoplankton characteristics and eutrophication status in a typical alpine glacial lake of Tianchi, a scenic area and an important drinking water source in the Xinjiang Autonomous Region of China, in 2014 and 2015. Clear seasonal and annual variations of nutrients and organic pollutants were found especially during rainy seasons. For the phytoplankton community, Bacillariophyta held the dominant position in terms of both species and biomass throughout the year, suggesting the dominant characteristics of diatoms in the phytoplankton structure in such a high-altitude cold-water lake. This was quite different from plain and warm lakes troubled with cyanobacterial blooming. Moreover, the dominant abundance of Cyclotella sp. in Tianchi might suggest regional warming caused by climate change, which might have profound effects on the local ecosystems and hydrological cycle. Based on water quality parameters, a comprehensive trophic level index TLI (Σ) was calculated to estimate the current status of eutrophication, and the results inferred emerging eutrophication in Tianchi. Results from Canonical Correspondence Analysis (CCA) and correlation analysis of phytoplankton genera and physico-chemical variables of water indicated that abiotic factors significantly influenced the phytoplankton community and its succession in Tianchi Lake. These abiotic factors could explain 77.82% of the total variance, and ammonium was identified as the most discriminant variable, which could explain 41% of the total variance followed by TP (29%). An estimation of annual nutrient loadings to

  20. Alpine lakes preserve mineral dust signatures: Implications for long-range mineral dust transport and Last Glacial Maximum (LGM) tornado frequency in the United States

    NASA Astrophysics Data System (ADS)

    Bhattacharya, A.; Lora, J. M.; Pollen, A.; Vollmer, T.; Thomas, M.; Leithold, E. L.; Mitchell, J.; Tripati, A.

    2016-12-01

    The net amount of mineral dust accumulation in arid and semi-arid regions might not be entirely sourced locally or even regionally; in fact, new evidence suggests that there could be significant contributions from distal sources. The contribution from the distal sources needs to be identified, and accounted for, in order to accurately understand the meteorological and climatologic factors, both regional and global, that control mineral dust accumulation in arid and semi-arid regions. Most importantly, if identified, the two components of mineral dust accumulation- fine fraction (typically <4 microns) and coarse fraction (typically >25 microns)- could provide critical information about regional as well as global climate. There are large-scale climatological controls on the finer fraction of mineral dust, while the coarser fraction is related to intense invents (i.e., the occurrence of cyclones). However, studies attempting to separate these two size fractions in terrestrial archives have been limited. Here we separate the two size fractions using grain size analysis, and use trace element analysis in each size fraction to identify contributing source regions. We apply this technique to well-dated cores collected from three lakes that are distributed across the western, southwestern and Great Plains in the United States: Pear Lake in the Sierra Nevada Mountains (CA), Senator Beck Lake in the San Juan Mountains (CO), and North Lake (WY). These lakes are uniquely situated to monitor dust fluxes; previous studies have demonstrated that sedimentation in these lakes are dominated by mineral dust accumulation; there is also evidence of remotely and locally sourced dust in these lakes, and of textural differences between the two types of dust fractions. We compare our results with previously published data on dust from loess deposits in the United States, and isotopic modeling (LMDZ). We find evidence that the finer-grain size fraction in alpine lake cores could be of

  1. Sustainable knowledge development across cultural boundaries: Experiences from the EU-project SILMAS (Toolbox for conflict solving instruments in Alpine Lake Management)

    NASA Astrophysics Data System (ADS)

    Fegerl, Michael; Wieden, Wilfried

    2013-04-01

    Increasingly people have to communicate knowledge across cultural and language boundaries. Even though recent technologies offer powerful communication facilities people often feel confronted with barriers which clearly reduce their chances of making their interaction a success. Concrete evidence concerning such problems derives from a number of projects, where generated knowledge often results in dead-end products. In the Alpine Space-project SILMAS (Sustainable Instruments for Lake Management in Alpine Space), in which both authors were involved, a special approach (syneris® ) was taken to avoid this problem and to manage project knowledge in sustainable form. Under this approach knowledge input and output are handled interactively: Relevant knowledge can be developed continuously and users can always access the latest state of expertise. Resort to the respective tools and procedures can also assist in closing knowledge gaps and in developing innovative responses to familiar or novel problems. This contribution intends to describe possible ways and means which have been found to increase the chances of success of knowledge communication across cultural boundaries. The process of trans-cultural discussions of experts to find a standardized solution is highlighted as well as the problem of dissemination of expert knowledge to variant stakeholders. Finally lessons learned are made accessible, where a main task lies in the creation of a tool box for conflict solving instruments, as a demonstrable result of the project and for the time thereafter. The interactive web-based toolbox enables lake managers to access best practice instruments in standardized, explicit and cross-linguistic form.

  2. Impact of Toxic Cyanobacterial Blooms on Eurasian Perch (Perca fluviatilis): Experimental Study and In Situ Observations in a Peri-Alpine Lake

    PubMed Central

    Sotton, Benoît; Guillard, Jean; Bony, Sylvie; Devaux, Alain; Domaizon, Isabelle; Givaudan, Nicolas; Crespeau, François; Huet, Hélène; Anneville, Orlane

    2012-01-01

    Due to the importance of young-of-the-year (YOY) perch in the peri-alpine regions where they are consumed, the microcystin (MC) contamination of YOY perch was analysed both in field (Lake Bourget, France) and experimentally using force-feeding protocols with pure MCs. In-situ, schools of YOY perch present in the epilimnion of the lake were never found in direct contact with the P. rubescens blooms that were present in the metalimnion. However, MCs were detected in the muscles and liver of the fish and were thus assumed to reach YOY perch through dietary routes, particularly via the consumption of MC-containing Daphnia. Force-feeding experiment demonstrates the existence of MC detoxification/excretion processes and suggests that in situ, YOY perch could partly detoxify and excrete ingested MCs, thereby limiting the potential negative effects on perch populations under bloom conditions. However, because of chronic exposure these processes could not allow for the complete elimination of MCs. In both experimental and in situ studies, no histological change was observed in YOY perch, indicating that MC concentrations that occurred in Lake Bourget in 2009 were too low to cause histological damage prone to induce mortality. However, Deoxyribonucleic acid (DNA) damages were observed for both the high and low experimental MC doses, suggesting that similar effects could occur in situ and potentially result in perch population disturbance during cyanobacterial blooms. Our results indicate the presence of MCs in wild perch, the consumption of this species coming from Lake Bourget is not contested but more analyses are needed to quantify the risk. PMID:23272228

  3. Altered energetics and parasitism in juvenile northern pike (Esox lucius) inhabiting metal-mining contaminated lakes.

    PubMed

    Kelly, Jocelyn M; Janz, David M

    2008-07-01

    The objective of this study was to evaluate possible factors that could be contributing to altered bioenergetics of juvenile northern pike (Esox lucius) living in lakes receiving effluent from the Key Lake uranium mill in northern Saskatchewan, Canada. Although glycogen and triglycerides stores in liver and muscle were significantly greater in pike from exposure lakes compared to the reference, triglycerides stores of aquatic insects and spottail shiners that are prey items of juvenile pike showed no overall differences among lakes. Measures of parasitism, on the other hand, were negatively correlated with pike bioenergetics thereby reflecting a possible energetic cost of parasitism on reference lake fishes. The degree of infection, as measured by the abundance and biomass of intestinal parasites and the abundance of monogeneans on pike gills, was greatest in reference fishes and intermediate in low-exposure pike, whereas high-exposure fishes harbored no parasites.

  4. Alpine Microbial Community Responses to Summer Warming

    NASA Astrophysics Data System (ADS)

    Osborne, B. B.; Baron, J.; Wallenstein, M. D.

    2011-12-01

    Remote alpine ecosystems of the western US are vulnerable to anthropogenic drivers of change. Atmospheric nitrogen (N) deposition and a changing climate introduce nutrients, alter hydrological processes, and expose soils to novel temperature regimes. We asked whether terrestrial microbes, specifically nitrifiers that may contribute to already high lake and stream NO3- concentrations, may be responding to changes in important controls of community development and activity associated with a changing climate, namely temperature and moisture. In August 2010 we sampled three soils from the Loch Vale Watershed in Rocky Mountain National Park which fell along a gradient of succession commonly represented in deglaciated alpine catchments. These included well-developed meadow soils, poorly vegetated talus substrate, and newly-exposed glacial outwash. Outwash, talus, and meadow samples were all N-rich and contained NH4-N concentrations ~7 times higher than NO3-N. Soils were incubated for 45 days at 2.5, 10, and 25oC and three moisture levels based on initial field conditions. Nitrifier concentrations were greatest in outwash, intermediate in talus, and lowest in meadow samples. Bacterial nitrifier abundance greatly surpassed archaeal nitrifier levels. Net nitrification was also greatest in outwash, followed by meadow and talus respectively. Moisture, rather than temperature, was a dominant control over both nitrifier abundance and activity. Linking the influence of temperature and moisture on alpine microbial communities will provide insight into control thresholds, optima, and synergistic interactions. This research is part of a larger study of controls on headwater stream and lake NO3-. Characterizing microbial NO3- production in the alpine will help us evaluate the importance of biological, as opposed to physical, sources of stream NO3-. It will also inform our ability to forecast and mitigate consequences of anthropogenic drivers of change on these systems.

  5. Altered precipitation patterns and simulated nitrogen deposition effects on phenology of common plant species in a Tibetan Plateau alpine meadow

    USDA-ARS?s Scientific Manuscript database

    The interactive effects of five seasonal precipitation distribution patterns and two levels of N deposition (ambient and doubled) on phenological traits of six dominant plant species were studied in an alpine meadow of the Tibetan Plateau for two consecutive years. Seasonal precipitation patterns i...

  6. Spatiotemporal drivers of dissolved organic matter in high alpine lakes: Role of Saharan dust inputs and bacterial activity

    PubMed Central

    Mladenov, Natalie; Pulido-Villena, Elvira; Morales-Baquero, Rafael; Ortega-Retuerta, Eva; Sommaruga, Ruben; Reche, Isabel

    2010-01-01

    The effects of many environmental stressors such as UV radiation are mediated by dissolved organic matter (DOM) properties. Therefore, determining the factors shaping spatial and temporal patterns is particularly essential in the most susceptible, low dissolved organic carbon (DOC) lakes. We analyzed spatiotemporal variations in dissolved organic carbon concentration and dissolved organic matter optical properties (absorption and fluorescence) in 11 transparent lakes located above tree line in the Sierra Nevada Mountains (Spain), and we assessed potential external (evaporation and atmospheric deposition) and internal (bacterial abundance, bacterial production, chlorophyll a, and catchment vegetation) drivers of DOM patterns. At spatial and temporal scales, bacteria were related to chromophoric DOM (CDOM). At the temporal scale, water soluble organic carbon (WSOC) in dust deposition and evaporation were found to have a significant influence on DOC and CDOM in two Sierra Nevada lakes studied during the ice-free periods of 2000–2002. DOC concentrations and absorption coefficients at 320 nm were strongly correlated over the spatial scale (n = 11, R2 = 0.86; p < 0.01), but inconsistently correlated over time, indicating seasonal and interannual variability in external factors and a differential response of DOC concentration and CDOM to these factors. At the continental scale, higher mean DOC concentrations and more CDOM in lakes of the Sierra Nevada than in lakes of the Pyrenees and Alps may be due to a combination of more extreme evaporation, and greater atmospheric dust deposition. PMID:20582227

  7. The Response of the Alpine Dwarf Shrub Salix herbacea to Altered Snowmelt Timing: Lessons from a Multi-Site Transplant Experiment

    PubMed Central

    Cortés, Andrés J.; Bossdorf, Oliver; Hoch, Guenter; Lexer, Christian; Wipf, Sonja; Karrenberg, Sophie; van Kleunen, Mark; Rixen, Christian

    2015-01-01

    Climate change is altering spring snowmelt patterns in alpine and arctic ecosystems, and these changes may alter plant phenology, growth and reproduction. To predict how alpine plants respond to shifts in snowmelt timing, we need to understand trait plasticity, its effects on growth and reproduction, and the degree to which plants experience a home-site advantage. We tested how the common, long-lived dwarf shrub Salix herbacea responded to changing spring snowmelt time by reciprocally transplanting turfs of S. herbacea between early-exposure ridge and late-exposure snowbed microhabitats. After the transplant, we monitored phenological, morphological and fitness traits, as well as leaf damage, during two growing seasons. Salix herbacea leafed out earlier, but had a longer development time and produced smaller leaves on ridges relative to snowbeds. Longer phenological development times and smaller leaves were associated with reduced sexual reproduction on ridges. On snowbeds, larger leaves and intermediate development times were associated with increased clonal reproduction. Clonal and sexual reproduction showed no response to altered snowmelt time. We found no home-site advantage in terms of sexual and clonal reproduction. Leaf damage probability depended on snowmelt and thus exposure period, but had no short-term effect on fitness traits. We conclude that the studied populations of S. herbacea can respond to shifts in snowmelt by plastic changes in phenology and leaf size, while maintaining levels of clonal and sexual reproduction. The lack of a home-site advantage suggests that S. herbacea may not be adapted to different microhabitats. The studied populations are thus unlikely to react to climate change by rapid adaptation, but their responses will also not be constrained by small-scale local adaptation. In the short term, snowbed plants may persist due to high stem densities. However, in the long term, reduction in leaf size and flowering, a longer phenological

  8. The Response of the Alpine Dwarf Shrub Salix herbacea to Altered Snowmelt Timing: Lessons from a Multi-Site Transplant Experiment.

    PubMed

    Sedlacek, Janosch; Wheeler, Julia A; Cortés, Andrés J; Bossdorf, Oliver; Hoch, Guenter; Lexer, Christian; Wipf, Sonja; Karrenberg, Sophie; van Kleunen, Mark; Rixen, Christian

    2015-01-01

    Climate change is altering spring snowmelt patterns in alpine and arctic ecosystems, and these changes may alter plant phenology, growth and reproduction. To predict how alpine plants respond to shifts in snowmelt timing, we need to understand trait plasticity, its effects on growth and reproduction, and the degree to which plants experience a home-site advantage. We tested how the common, long-lived dwarf shrub Salix herbacea responded to changing spring snowmelt time by reciprocally transplanting turfs of S. herbacea between early-exposure ridge and late-exposure snowbed microhabitats. After the transplant, we monitored phenological, morphological and fitness traits, as well as leaf damage, during two growing seasons. Salix herbacea leafed out earlier, but had a longer development time and produced smaller leaves on ridges relative to snowbeds. Longer phenological development times and smaller leaves were associated with reduced sexual reproduction on ridges. On snowbeds, larger leaves and intermediate development times were associated with increased clonal reproduction. Clonal and sexual reproduction showed no response to altered snowmelt time. We found no home-site advantage in terms of sexual and clonal reproduction. Leaf damage probability depended on snowmelt and thus exposure period, but had no short-term effect on fitness traits. We conclude that the studied populations of S. herbacea can respond to shifts in snowmelt by plastic changes in phenology and leaf size, while maintaining levels of clonal and sexual reproduction. The lack of a home-site advantage suggests that S. herbacea may not be adapted to different microhabitats. The studied populations are thus unlikely to react to climate change by rapid adaptation, but their responses will also not be constrained by small-scale local adaptation. In the short term, snowbed plants may persist due to high stem densities. However, in the long term, reduction in leaf size and flowering, a longer phenological

  9. The influence of glacial meltwater on alpine aquatic ecosystems: a review.

    PubMed

    Slemmons, Krista E H; Saros, Jasmine E; Simon, Kevin

    2013-10-01

    The recent and rapid recession of alpine glaciers over the last 150 years has major implications for associated aquatic communities. Glacial meltwater shapes many of the physical features of high altitude lakes and streams, producing turbid environments with distinctive hydrology patterns relative to nival systems. Over the past decade, numerous studies have investigated the chemical and biological effects of glacial meltwater on freshwater ecosystems. Here, we review these studies across both lake and stream ecosystems. Focusing on alpine regions mainly in the Northern Hemisphere, we present examples of how glacial meltwater can affect habitat by altering physical and chemical features of aquatic ecosystems, and review the subsequent effects on the biological structure and function of lakes and streams. Collectively or separately, these factors can drive the overall distribution, diversity and behavior of primary producers, triggering cascading effects throughout the food web. We conclude by proposing areas for future research, particularly in regions where glaciers are soon projected to disappear.

  10. Implications for faunal habitat related to altered macrophyte structure in regulated lakes in northern Minnesota

    USGS Publications Warehouse

    Wilcox, Douglas A.; Meeker, James E.

    1992-01-01

    Water-level regulation has altered the plant species composition and thus the structure of nearshore aquatic macrophyte communities in two regulated lakes in northern Minnesota as compared with a nearby unregulated lake. Results of previous faunal studies in the regulated lakes were used as a basis for assessing the effects of vegetation changes on faunal communities. The unregulated lake with mean annual water-level fluctuations of 1.6 m supported structurally diverse plant communities and varied faunal habitat at all depths studied. Mean annual fluctuations on one regulated lake were reduced to 1.1 m, and dense beds of four erect aquatic macrophytes dominated the 1.75-m depth that was never dewatered. We suggest that this lack of plant diversity and structural complexity resulted in diminished habitat for invertebrates, reduced availability of invertebrates as food for waterbirds and fish, reduced winter food supplies for muskrats, and reduced feeding efficiency for adult northern pike, yellow perch, and muskellunge. Mean annual fluctuations in the other regulated lake were increased to 2.7 m, and rosette and mat-forming species dominated the 1.25-m depth that was affected by winter drawdowns. We suggest that the lack of larger canopy plants resulted in poor habitat for invertebrates, reduced availability of invertebrates as food for waterbirds and fish, and poor nursery and adult feeding habitat for many species of fish. In addition, the timing and extent of winter drawdowns reduced access to macrophytes as food for muskrats and as spawning habitat for northern pike and yellow perch. In regulated lakes throughout the world, indirect effects on aquatic fauna resulting from alteration of wetland and aquatic macrophyte communities should be considered when water-level management plans are developed.

  11. Minimal endocrine alterations in rodents after consumption of lake trout (Salvelinus namaycush).

    PubMed

    Gerstenberger, S L; Heimler, I; Smies, R; Hutz, R J; Dasmahapatra, A K; Tripoli, V; Dellinger, J A

    2000-04-01

    Polychlorinated biphenyls (PCBs) and dioxins are known to cause disruptions in circulating hormone concentrations, which may influence fertility and normal fetal development. Structure activity relationships have been determined for individual congeners, but it is unclear what impacts occur due to exposure to complex mixtures of chemicals found in the environment. Most laboratory studies of PCB exposure have used commercial mixtures in high doses, which may not be representative of environmental concentrations of individual congeners, nor accurately represent complex interactions of multiple contaminants. The present study investigated endocrine alterations in rats associated with the consumption of lake trout collected from three specific locations in the Great Lakes. Composite fish samples were analyzed for PCBs, organochlorines, and mercury and ranged from 415 ppb to 1,275 ppb for individual contaminants. Fillet composites were fed to timed-pregnant Long-Evans rats as 30% of their diet. Concentrations of total thyroxine and estrogen were not significantly different in offspring of dosed dams from that of controls. However, aromatase activity was lowered in all dosed groups as compared with controls. This may represent a lowered expression of the CYP 19 gene in exposed rats or may be due to the presence of one or more substances in the contaminants that are capable of altering the affinity of the aromatase enzyme for its normal endogenous substrate. It is also possible that the number of maturing follicles in the lake trout-fed rats may be fewer than controls, which would result in an overall reduction in the enzyme activity. Data regarding the endocrine effects of environmental contaminant mixtures found in fish from the Great Lakes Basin are still controversial. Additionally, information is scarce with respect to the F1 generation of laboratory animals following environmental maternal exposures, therefore, we investigated the reproductive-endocrine alterations

  12. Characterization of rhizosphere and endophytic fungal communities from roots of Stipa purpurea in alpine steppe around Qinghai Lake.

    PubMed

    Lu, Dengxue; Jin, Hui; Yang, Xiaoyan; Zhang, Denghong; Yan, Zhiqiang; Li, Xiuzhuang; Zhao, Yuhui; Han, Rongbing; Qin, Bo

    2016-08-01

    Stipa purpurea is among constructive endemic species in the alpine steppe on the Qinghai-Xizang Plateau. To reveal the fungal community structure and diversity in the rhizosphere and roots of this important grass and to analyze the potential influence of different habitats on the structure of fungal communities, we explored the root endophyte and the directly associated rhizosphere communities of S. purpurea by using internal transcribed spacer rRNA cloning and sequencing methods. We found that the roots of S. purpurea are associated with a diverse consortium of Basidiomycota (59.8%) and Ascomycota (38.5%). Most fungi obtained from rhizosphere soil in S. purpurea have been identified as Ascomycetes, while the high proportion detected in roots were basidiomycetous endophytes. The species richness, diversity, and evenness of fungal assemblages were higher in roots than in the rhizosphere soil. Fungi inhabiting the rhizosphere and roots of S. purpurea are significantly different, and the rhizosphere and endophyte communities are largely independent with little overlap in the dominant phyla or operational taxonomic units. Taken together, these results suggested that a wide variety of fungal communities are associated with the roots and rhizosphere soil of S. purpurea and that the fungal assemblages are strongly influenced by different habitats.

  13. Climate and human impacts on Lake Ammersee - Alterations in a normal range?

    NASA Astrophysics Data System (ADS)

    Vetter, M.; Büche, T.; Weinberger, S.

    2012-04-01

    Throughout the last decades of the 20th century, nutrient concentrations in some continental aquatic ecosystems increased due to human activities in their catchment areas. This is also possible to observe in the Lake Ammersee, situated in South-East of Germany, 30 km away from the City of Munich. The lake and its catchment area are representative of this type of central European water body and therefore will allow for analysis of how the lake responds to this kind of anthropogenic influence. Afterwards, in the middle of the 1980s, the problem of immense input of nutrients in the lake was detected and several management activities were carried out to keep nutrients away from this ecosystem. Hence, a trend of re-oligotrophication at the lake was observed after the middle of the 1990s. Parallel to this process, temperatures have been increasing in the northern hemisphere since the end of the 19th century. In this respect, an investigation of Lake Ammersee will be very appropriate since it may be possible to detect the difference between anthropogenic impact and possible alterations due to climate change. In this contribution, we investigated the direct anthropogenic and supra-regional climatic impacts triggered by global warming on Lake Ammersee during 1984 and 2009. Therefore we address the following questions: How do past water management activities in the Lake Ammersee catchment area affect the trophic development of the lake? What is the relationship between trophic variables chlorophyll-a concentration, water transparency or oxygen content in the lake? Is there a correlation between the signal of a changing climate and the trophic level of the lake? And, is it possible to distinguish between this (global) climate effect and direct anthropogenic pressure by land-use history? The study of dissolved oxygen, total phosphorus and chlorophyll-a, exposed a remarkable improvement in the trophic conditions of the lake. Nevertheless, a more intensive oxygen depletion in

  14. Small Changes in Climate Can Profoundly Alter the Dynamics and Ecosystem Services of Tropical Crater Lakes

    PubMed Central

    Saulnier-Talbot, Émilie; Gregory-Eaves, Irene; Simpson, Kyle G.; Efitre, Jackson; Nowlan, Tobias E.; Taranu, Zofia E.; Chapman, Lauren J.

    2014-01-01

    African tropical lakes provide vital ecosystem services including food and water to some of the fastest growing human populations, yet they are among the most understudied ecosystems in the world. The consequences of climate change and other stressors on the tropical lakes of Africa have been informed by long-term analyses, but these studies have largely focused on the massive Great Rift Valley lakes. Our objective was to evaluate how recent climate change has altered the functioning and services of smaller tropical lakes, which are far more abundant on the landscape. Based on a paired analysis of 20 years of high-resolution water column data and a paleolimnological record from a small crater lake in western Uganda, we present evidence that even a modest warming of the air (∼0.9°C increase over 20 years) and changes in the timing and intensity of rainfall can have significant consequences on the dynamics of this common tropical lake type. For example, we observed a significant nonlinear increase (R2adj = 0.23, e.d.f. = 7, p<0.0001) in thermal stability over the past 20 years. This resulted in the expansion of anoxic waters and consequent deterioration of fish habitat and appears to have abated primary production; processes that may impair ecosystem services for a vulnerable human population. This study on a system representative of small tropical crater lakes highlights the far-reaching effects of global climatic change on tropical waters. Increased research efforts into tropical aquatic ecosystem health and the development of sound management practices are necessary in order to strengthen adaptive capabilities in tropical regions. PMID:24497954

  15. Small changes in climate can profoundly alter the dynamics and ecosystem services of tropical crater lakes.

    PubMed

    Saulnier-Talbot, Émilie; Gregory-Eaves, Irene; Simpson, Kyle G; Efitre, Jackson; Nowlan, Tobias E; Taranu, Zofia E; Chapman, Lauren J

    2014-01-01

    African tropical lakes provide vital ecosystem services including food and water to some of the fastest growing human populations, yet they are among the most understudied ecosystems in the world. The consequences of climate change and other stressors on the tropical lakes of Africa have been informed by long-term analyses, but these studies have largely focused on the massive Great Rift Valley lakes. Our objective was to evaluate how recent climate change has altered the functioning and services of smaller tropical lakes, which are far more abundant on the landscape. Based on a paired analysis of 20 years of high-resolution water column data and a paleolimnological record from a small crater lake in western Uganda, we present evidence that even a modest warming of the air (∼0.9°C increase over 20 years) and changes in the timing and intensity of rainfall can have significant consequences on the dynamics of this common tropical lake type. For example, we observed a significant nonlinear increase (R(2) adj  = 0.23, e.d.f. = 7, p<0.0001) in thermal stability over the past 20 years. This resulted in the expansion of anoxic waters and consequent deterioration of fish habitat and appears to have abated primary production; processes that may impair ecosystem services for a vulnerable human population. This study on a system representative of small tropical crater lakes highlights the far-reaching effects of global climatic change on tropical waters. Increased research efforts into tropical aquatic ecosystem health and the development of sound management practices are necessary in order to strengthen adaptive capabilities in tropical regions.

  16. Homogenised daily lake surface water temperature data generated from multiple satellite sensors: A long-term case study of a large sub-Alpine lake

    PubMed Central

    Pareeth, Sajid; Salmaso, Nico; Adrian, Rita; Neteler, Markus

    2016-01-01

    Availability of remotely sensed multi-spectral images since the 1980’s, which cover three decades of voluminous data could help researchers to study the changing dynamics of bio-physical characteristics of land and water. In this study, we introduce a new methodology to develop homogenised Lake Surface Water Temperature (LSWT) from multiple polar orbiting satellites. Precisely, we developed homogenised 1 km daily LSWT maps covering the last 30 years (1986 to 2015) combining data from 13 satellites. We used a split-window technique to derive LSWT from brightness temperatures and a modified diurnal temperature cycle model to homogenise data which were acquired between 8:00 to 17:00 UTC. Gaps in the temporal LSWT data due to the presence of clouds were filled by applying Harmonic ANalysis of Time Series (HANTS). The satellite derived LSWT maps were validated based on long-term monthly in-situ bulk temperature measurements in Lake Garda, the largest lake in Italy. We found the satellite derived homogenised LSWT being significantly correlated to in-situ data. The new LSWT time series showed a significant annual rate of increase of 0.020 °C yr−1 (*P < 0.05), and of 0.036 °C yr−1 (***P < 0.001) during summer. PMID:27502177

  17. Homogenised daily lake surface water temperature data generated from multiple satellite sensors: A long-term case study of a large sub-Alpine lake

    NASA Astrophysics Data System (ADS)

    Pareeth, Sajid; Salmaso, Nico; Adrian, Rita; Neteler, Markus

    2016-08-01

    Availability of remotely sensed multi-spectral images since the 1980’s, which cover three decades of voluminous data could help researchers to study the changing dynamics of bio-physical characteristics of land and water. In this study, we introduce a new methodology to develop homogenised Lake Surface Water Temperature (LSWT) from multiple polar orbiting satellites. Precisely, we developed homogenised 1 km daily LSWT maps covering the last 30 years (1986 to 2015) combining data from 13 satellites. We used a split-window technique to derive LSWT from brightness temperatures and a modified diurnal temperature cycle model to homogenise data which were acquired between 8:00 to 17:00 UTC. Gaps in the temporal LSWT data due to the presence of clouds were filled by applying Harmonic ANalysis of Time Series (HANTS). The satellite derived LSWT maps were validated based on long-term monthly in-situ bulk temperature measurements in Lake Garda, the largest lake in Italy. We found the satellite derived homogenised LSWT being significantly correlated to in-situ data. The new LSWT time series showed a significant annual rate of increase of 0.020 °C yr‑1 (*P < 0.05), and of 0.036 °C yr‑1 (***P < 0.001) during summer.

  18. Homogenised daily lake surface water temperature data generated from multiple satellite sensors: A long-term case study of a large sub-Alpine lake.

    PubMed

    Pareeth, Sajid; Salmaso, Nico; Adrian, Rita; Neteler, Markus

    2016-08-09

    Availability of remotely sensed multi-spectral images since the 1980's, which cover three decades of voluminous data could help researchers to study the changing dynamics of bio-physical characteristics of land and water. In this study, we introduce a new methodology to develop homogenised Lake Surface Water Temperature (LSWT) from multiple polar orbiting satellites. Precisely, we developed homogenised 1 km daily LSWT maps covering the last 30 years (1986 to 2015) combining data from 13 satellites. We used a split-window technique to derive LSWT from brightness temperatures and a modified diurnal temperature cycle model to homogenise data which were acquired between 8:00 to 17:00 UTC. Gaps in the temporal LSWT data due to the presence of clouds were filled by applying Harmonic ANalysis of Time Series (HANTS). The satellite derived LSWT maps were validated based on long-term monthly in-situ bulk temperature measurements in Lake Garda, the largest lake in Italy. We found the satellite derived homogenised LSWT being significantly correlated to in-situ data. The new LSWT time series showed a significant annual rate of increase of 0.020 °C yr(-1) (*P < 0.05), and of 0.036 °C yr(-1) (***P < 0.001) during summer.

  19. Paleoflood activity and climate change over the last 2000 years recorded by high altitude alpine lake sediments in Western French Alps.

    NASA Astrophysics Data System (ADS)

    Fouinat, Laurent; Sabatier, Pierre; Develle, Anne-Lise; Giguet-Covex, Charline; Poulenard, Jérôme; Doyen, Elise; Crouzet, Christian; Malet, Emmanuel; Reyss, Jean-Louis; Arnaud, Fabien

    2015-04-01

    Extreme precipitation events can trigger floods that may have serious human and economic consequences. The flood represents extreme rainfall event, which in high altitude mountain regions are mostly triggered alternatively by local convective summer storms or, less frequently, by regional widespread rainfall event. The former's precipitation pattern comes from Mediterranean Sea fluxes, dominant in the south; instead of the latter coming from the Atlantic Ocean, dominant in the north of the French Alps. The aim of the study is then to explore which regime dominates in Western French Alps. Paleoflood chronicle is a way to understand past continental climate through the variability of both frequency and intensity. In this study we explore the paleoflood activity as recorded by sediments of the small alpine lake Muzelle (2200 m.a.s.l.) located in the western French Alps. Lake Muzelle catchment area is 5 km² -around 4 % being glacier covered- and is drained by one main stream. Lake Muzelle is 18.8 meters deep and is ice-covered during 7-8 months each year. Moreover, the watershed is being used for pastoral activity for several centuries. In this study, we use sedimentological analysis as well high resolution XRF core scanner geochemistry to identify turbidites interpreted as flood deposits. 256 turbidites were documented in the sediment sequence. Sr/Ti geochemical ratio is used to identify the coarsest grain size fraction of the flood deposit and the thickness of each deposit was measured. Dating was carried out using short-lived-radio-elements (210Pb, 137Cs, 241Am), historical events as well as nine 14C dates and paleomagnetic declination to constrain the age model over the last 2000 years. The study includes also palynological and sediment DNA analysis to understand past human activity on the watershed. As a result, the 31 years frequency shows a stable period from 0 to 1100 AD. Between 1100 and1200 AD the flood frequency presents a brutal increase with a relatively

  20. Fingerprinting of glacial silt in lake sediments yields continuous records of alpine glaciation (35–15 ka), western USA

    USGS Publications Warehouse

    Rosenbaum, Joseph G.; Reynolds, Richard L.; Colman, Steven M.

    2012-01-01

    Fingerprinting glacial silt in last glacial-age sediments from Upper Klamath Lake (UKL) and Bear Lake (BL) provides continuous radiocarbon-dated records of glaciation for the southeastern Cascade Range and northwestern Uinta Mountains, respectively. Comparing of these records to cosmogenic exposure ages from moraines suggests that variations in glacial flour largely reflect glacial extent. The two areas are at similar latitudes and yield similar records of glacial growth and recession, even though UKL lies less than 200 km from the ocean and BL is in the continental interior. As sea level began to fall prior to the global Last Glacial Maximum (LGM), existing glaciers in the UKL area expanded. Near the beginning of the global LGM (26.5 ka), the BL record indicates onset of glaciation and UKL-area glaciers underwent further expansion. Both records indicate that local glaciers reached their maximum extents near the end of the global LGM, remained near their maxima for ~1000 yr, and underwent two stages of retreat separated by a short period of expansion.

  1. Lake surface water temperatures of European Alpine lakes (1989-2013) based on the Advanced Very High Resolution Radiometer (AVHRR) 1 km data set

    NASA Astrophysics Data System (ADS)

    Riffler, M.; Lieberherr, G.; Wunderle, S.

    2015-02-01

    Lake water temperature (LWT) is an important driver of lake ecosystems and it has been identified as an indicator of climate change. Consequently, the Global Climate Observing System (GCOS) lists LWT as an essential climate variable. Although for some European lakes long in situ time series of LWT do exist, many lakes are not observed or only on a non-regular basis making these observations insufficient for climate monitoring. Satellite data can provide the information needed. However, only few satellite sensors offer the possibility to analyse time series which cover 25 years or more. The Advanced Very High Resolution Radiometer (AVHRR) is among these and has been flown as a heritage instrument for almost 35 years. It will be carried on for at least ten more years, offering a unique opportunity for satellite-based climate studies. Herein we present a satellite-based lake surface water temperature (LSWT) data set for European water bodies in or near the Alps based on the extensive AVHRR 1 km data record (1989-2013) of the Remote Sensing Research Group at the University of Bern. It has been compiled out of AVHRR/2 (NOAA-07, -09, -11, -14) and AVHRR/3 (NOAA-16, -17, -18, -19 and MetOp-A) data. The high accuracy needed for climate related studies requires careful pre-processing and consideration of the atmospheric state. The LSWT retrieval is based on a simulation-based scheme making use of the Radiative Transfer for TOVS (RTTOV) Version 10 together with ERA-interim reanalysis data from the European Centre for Medium-range Weather Forecasts. The resulting LSWTs were extensively compared with in situ measurements from lakes with various sizes between 14 and 580 km2 and the resulting biases and RMSEs were found to be within the range of -0.5 to 0.6 K and 1.0 to 1.6 K, respectively. The upper limits of the reported errors could be rather attributed to uncertainties in the data comparison between in situ and satellite observations than inaccuracies of the satellite

  2. Tracking Holocene glacial and high-altitude alpine environments fluctuations from minerogenic and organic markers in proglacial lake sediments (Lake Blanc Huez, Western French Alps)

    NASA Astrophysics Data System (ADS)

    Simonneau, Anaëlle; Chapron, Emmanuel; Garçon, Marion; Winiarski, Thierry; Graz, Yann; Chauvel, Catherine; Debret, Maxime; Motelica-Heino, Mickaël; Desmet, Marc; Di Giovanni, Christian

    2014-04-01

    Holocene palaeoenvironmental evolution and glacial fluctuations at high-altitude in the western French Alps are reconstructed based on a multiproxy approach within Lake Blanc Huez (2550 m a.s.l.) drainage basin. The combination of seismic profiling (3.5 kHz), piston coring and radiocarbon dating in proglacial lacustrine sediments together with a detailed organic analysis of autochthonous and allochthonous supply allows documenting the evolution of glacier activity during the Holocene. Over the last 9700 years, the Holocene lake record has a bimodal pattern whose transition is progressive and occurring between 5400 and 4700 cal BP. During the Early Holocene, the organic lacustrine facies reflects reduced glacial activity in the catchment. This major glacial retreat seems to result from solar forcing and high summer insolation. After 5400 cal BP, lacustrine sedimentation is marked by the gradual increase both of minerogenic supply and soil erosion, suggesting a progressive transition to wetter climatic conditions. This climate change is synchronous both from the gradual decrease of summer insolation and the gradual reorganization of oceanic and atmospheric circulations, characterizing the beginning of the Neoglacial period. Both colder temperature and humid climate induced significant glacier advance, since 4700 cal BP. Over this global trend, three periods are particularly associated with higher runoff processes and higher soil erosion interpreted as wetter time intervals resulting from enhanced northern Westerlies regimes across the North Atlantic and Western Europe. They are dated from 8700 to 7000, 4700 to 2500 and 1200 to 200 cal BP. These wetter phases drastically contrast with periods of reduced glacial activities dated from the Early Bronze Age (ca 3870-3770 cal BP), the Iron Age (ca 2220-2150 cal BP), the Roman period (ca AD115-330) and the Medieval Warm Period (ca AD760-1160). In addition, these dryer periods are associated with mining activities at high-altitude.

  3. Structural and alteration controls on gold mineralization the of the amphibolite facies Detour Lake Deposit, Canada

    NASA Astrophysics Data System (ADS)

    Dubosq, Renelle; Schneider, David

    2016-04-01

    The 15M oz Detour Lake deposit is a Neoarchean orogenic gold ore body located in the northern most region of the Abitibi district within the Superior Province. The mine is an open pit design in the high strain zone of the Sunday Lake Deformation Zone (SLDZ). The ductile-brittle SLDZ parallels the broadly E-W Abitibi greenstone belt and the deposit is situated in a dilation zone between volcanoclastic rocks of the Caopatina Assemblage and Lower Detour Lake Formation, consisting of ultramafic talc-chlorite-sericite schist. The Upper Detour Lake Formation consists of pillowed and massive flows and hyloclastic units crosscut by minor felsic to intermediate dykes. All of the formations are sub-vertical, north-dipping units with stretching lineations indicating dip-slip motion. The Detour deposit differs from other classic ore deposits in the dominantly greenschist facies Abitibi Subprovince by possessing an amphibolite facies metamorphic assemblage of actinolite-biotite-plagioclase-almandine. Consequently, the typical indicator minerals used to identify alteration and mineralization, such as secondary biotite, may not be useful. Petrological and geochemical analyses have revealed at least four populations of biotite: 1) large euhedral crystals located within quartz-carbonate veins, 2) small, euhedral zoned crystals present as alteration haloes, 3) very small, anhedral to subhedral indistinct crystal present in mafic volcanic host rock, and 4) large euhedral crystals defining the main metamorphic foliation in the metasediments. Extensive examination of mineral assemblages, alteration products, and vein structure in rock core across barren and mineralized zones has documented over a dozen vein types which can be grouped into two main categories: 1) sulfidized quartz-carbonate veins associated with biotite alteration and 2) late carbonate veins. Gold grades do not prove to be dependent on vein type but rather on the host rock composition: the highest ore grades are present

  4. Two millennia of torrential activity reconstructed from alpine lake sediments: towards regional patterns of extreme precipitation changes

    NASA Astrophysics Data System (ADS)

    Wilhelm, B.; Arnaud, F.; Giguet-Covex, C.; Sabatier, P.; Crouzet, C.; Delannoy, J. J.

    2012-04-01

    In mountain areas extreme precipitation events trigger torrential floods, characterized by a sudden and intense rise of discharge causing large human and economic losses. Their frequency and/or intensity are expected to increase in the context of global warming. However, the relationship between such events and climate changes remains difficult to assess. Long-term geological records of intense events could enable to extend documented records beyond the observational data for a better understanding of local to regional flood hazard patterns in relation to past climatic changes and hence improving predictive models. In this context, lake sediment records appear a relevant archive as they are continuous records in which the identification of high-energy sediment layers allows to reconstruct flood calendar. In addition, the flood intensity can be reconstructed from the coarse fraction of each flood layer. Frequency and intensity of past torrential floods were thus reconstructed from four high-elevation lake records of the French Alps, in the framework of Pygmalion research program. Studied sites were selected along a north-south transect over this region to investigate the flooding responses to different climatic influences (westerlies in the north and Mediterranean influences in the south). High-resolution geochemical and sedimentological analyses were undertaken for an exhaustive identification of flood layers and several dating methods (short-lived radionuclides, 14C, correlation with historic events, paleomagnetism) were combined to reduce age uncertainties as much as possible. Over the entire French Alps, the torrential-flood frequency increases at a secular timescale during the cold period of the Little Ice Age (LIA; 1300-1900 AD). This increase seems in agreement with a regional high wetness, already described in the literature, possibly related to an increase in cyclonic activity. Superimposed to this secular trend, a pluri-decadal variability appears at

  5. An Intense Ocean-Atmosphere Interaction during the Holocene Optimum: Evidence from Sub-alpine Lake Sediments in Taiwan

    NASA Astrophysics Data System (ADS)

    Kandasamy, S.; Chen, C. A.; Lou, J. Y.; Kao, S.

    2009-12-01

    The Holocene climate reconstructions indicate an optimum climate in terms of either temperature or precipitation or both between ca. 10.5 and 4.5 calendar thousand years before the Present (ka BP). This so called Holocene optimum (HO) exhibits a time lagged phenomenon across the East Asia where the interaction of summer and winter modes of East Asian monsoon (EAM) has produced diverse climatic and environmental finger prints for the entire Holocene (the past ~11.5 ka). Yet, we lack evidence for the role of ocean and atmosphere during the HO given the fact that quantification of such input in the continental archives has not been done earlier, especially on the land-ocean-atmosphere interface. To fulfill this gap, a sediment core (~1.7 m) raised from Retreat Lake in northeastern Taiwan was studied for Relative Grey Index (RGI), bulk density, water content, total organic carbon (TOC), total nitrogen, and selected major and trace elements, including indicator elements for sea salt input (Br, Cl and Na). Time series of RGI shows high values (>80) ~170-155 cm and top ~45 cm of the core due to the presence of white, dense, minerogenic sediments with low water and TOC contents. Such an association of parameters indicates cool-wet and warm-dry climates and respectively corresponds to early Holocene (~10.3-8.6 ka BP) and late Holocene (since 4.5 ka BP). By contrast, sediments ~155-45 cm of the core show low RGI values (mostly <50) due to the presence of dark, less dense, peaty sediments with high water and TOC contents, indicating the warmest perhaps the wettest climate (HO) ~8.6-4.5 ka BP. Interestingly, the peaty sediments of HO show very high Br concentrations of up to 230 μg g-1, almost all values are >150 μg g-1. These values are ~7-12 times higher than Br values found in early and late Holocene sediments (0-20 μg g-1) as well as source rock Br values. Depth profiles of Br, Cl, and Na mimic each other and Br shows a linear relationship with Cl and Na in sediments of

  6. Late Pleistocene and Holocene Hydroclimate Variability in the Tropical Andes from Alpine Lake Sediments, Cordillera de Mérida, Venezuela

    NASA Astrophysics Data System (ADS)

    Larsen, D. J.; Abbott, M. B.; Polissar, P. J.

    2014-12-01

    The tropics play a major role in the global hydrologic cycle and changes to tropical rainfall patterns have critical implications for water resources and ecosystem dynamics over large geographic scales. In tropical South America, late Pleistocene and Holocene precipitation variability has been documented in geologic records and associated with numerous external and internal variables, including changes in summer insolation, South American summer monsoon strength, Pacific Ocean sea surface temperatures, continental moisture recycling, and other climate processes. However, there are few records from the northern hemisphere tropical Americas, a key region for understanding interhemispheric linkages and the drivers of tropical hydroclimate variability. Here, we present a ~13 ka record of coupled hydroclimate and environmental changes from Laguna Brava, a small (~0.07 km2), hydrologically closed lake basin situated at 2400 m asl in the Cordillera de Mérida, Venezuela. Sediment cores collected from varying water depths and proximity to shore are placed in a chronologic framework using radiocarbon ages from terrestrial macrofossils, and analyzed for a suite of physical, bulk geochemical, and stable isotopic parameters. Compound specific hydrogen isotope (D/H) measurements of terrestrial plant waxes (long-chain n-alkanes) show a sharp increase in the late Pleistocene, followed by a long-term trend toward more negative values that suggest a ~20‰ decrease in the D/H ratios of South American tropical precipitation during the Holocene. This pattern is consistent in sign and magnitude to other South American precipitation reconstructions from both hemispheres, indicating interhemispheric similarities in tropical hydroclimate variability. Superimposed on this continent-scale trend are changes in moisture balance and environmental conditions in the Venezuelan Andes. We reconstruct these parameters at Laguna Brava at multidecadal and centennial resolution and evaluate this

  7. Decreased glutathione S-transferase expression and activity and altered sex steroids in Lake Apopka brown bullheads (Ameriurus nebulosus)

    USGS Publications Warehouse

    Gallagher, E.P.; Gross, T.S.; Sheehy, K.M.

    2001-01-01

    A number of freshwater lakes and reclaimed agricultural sites in Central Florida have been the receiving waters for agrochemical and municipal runoff. One of these sites, Lake Apopka, is also a eutrophic system that has been the focus of several case studies reporting altered reproductive activity linked to bioaccumulation of persistent organochlorine chemicals in aquatic species. The present study was initiated to determine if brown bullheads (Ameriurus nebulosus) from the north marsh of Lake Apopka (Lake Apopka Marsh) exhibit an altered capacity to detoxify environmental chemicals through hepatic glutathione S-transferase (GST)-mediated conjugation as compared with bullheads from a nearby reference site (Lake Woodruff). We also compared plasma sex hormone concentrations (testosterone, 17-?? estradiol, and 11 keto-testosterone) in bullheads from the two sites. Female bullheads from Lake Apopka had 40% lower initial rate GST conjugative activity toward 1-chloro-2,4-dinitrobenzene (CDNB), 50% lower activity towards p-nitrobutyl chloride (NBC), 33% lower activity toward ethacrynic acid (ECA), and 43% lower activity toward ??5-androstene-3,17-dione (??5-ADI), as compared with female bullheads from Lake Woodruff. Enzyme kinetic analyses demonstrated that female bullheads from Lake Apopka had lower GST-catalyzed CDNB clearance than did female Lake Woodruff bullheads. Western blotting studies of bullhead liver cytosolic proteins demonstrated that the reduced GST catalytic activities in female Lake Apopka bullheads were accompanied by lower expression of hepatic GST protein. No site differences were observed with respect to GST activities or GST protein expression in male bullheads. Female Lake Apopka bullheads also had elevated concentrations of plasma androgens (testosterone and 11-ketotestosterone) as compared with females from Lake Woodruff. In contrast, male Lake Apopka bullheads had elevated levels of plasma estrogen but similar levels of androgens as compared with

  8. Nonnative Pacific salmon alter hot spots of sediment nitrification in Great Lakes tributaries

    NASA Astrophysics Data System (ADS)

    Levi, Peter S.; Tank, Jennifer L.

    2013-06-01

    Biogeochemical transformations may represent an important pathway influencing the fate of nutrient subsidies in stream ecosystems. Pacific salmon (Oncorhynchus spp.) provide an ammonium (NH4+) subsidy to streams during their annual spawning runs, which may be transformed to nitrate (NO3-) via sediment nitrification. Increases in either forms of dissolved inorganic nitrogen may have ecosystem effects both at the reach and watershed scales, including the fertilization of algal biofilms and elevated export of nutrients to downstream ecosystems. In the nonnative range of salmon, where spawning runs are a relatively new phenomenon, few studies have explored the effect of introduced salmon on ecosystem processes. To assess the effect of nonnative salmon on dissolved inorganic nitrogen dynamics in Great Lakes tributaries, we quantified sediment nitrification in five streams before, during, and after the spawning run in 2009. Overall, sediment nitrification rates were higher in the channel thalweg (mean ± SE = 1.9 ± 0.1 mg N/gAFDM/d) compared to channel margins (mean ± SE = 0.9 ± 0.1 mg N/gAFDM/d). In the two streams with the largest salmon runs, nitrification was highest in the channel thalweg prior to salmon, but margin sediments had higher nitrification during the run. Among all streams, variation in nitrification rates was habitat specific, predicted by exchangeable NH4+ in sediments from the thalweg and predicted by salmon biomass for sediments in the channel margin. Nonnative salmon provide a pulsed source of inorganic nitrogen to Great Lakes tributaries, yet dissimilatory biogeochemical transformations such as nitrification may alter the form of the NH4+ subsidy and potentially influence downstream lakes via export of both NH4+ and NO3-.

  9. Potential for large-bodied zooplankton and dreissenids to alter the productivity and autotrophic structure of lakes.

    PubMed

    Higgins, Scott N; Althouse, B; Devlin, S P; Vadeboncoeur, Y; Vander Zanden, M J

    2014-08-01

    While limnological studies have emphasized the importance of grazers on algal biomass and primary production in pelagic habitats, few studies have examined their potential role in altering total ecosystem primary production and it's partitioning between pelagic and benthic habitats. We modified an existing ecosystem production model to include biotic feedbacks associated with two groups of large-bodied grazers of phytoplankton (large-bodied zooplankton and dreissenid mussels) and estimated their effects on total ecosystem production (TEP), and the partitioning of TEP between phytoplankton and periphyton (autotrophic structure) across large gradients in lake size and total phosphorus (TP) concentration. Model results indicated that these filter feeders were capable of reducing whole-lake phytoplankton production by 20-70%, and increasing whole-lake benthic production between 0% and 600%. Grazer effects on TEP were constrained by lake size, trophic status, and potential feedbacks between grazing and maximum rates of benthic photosynthesis (BP(MAX)). In small (mean depth Z < 10 m) oligotrophic and mesotrophic (TP < 100 mg P/m2) lakes, both large-bodied zooplankton and dreissenids were capable of increasing the benthic fraction (Bf) by 10-50% of TEP. Small lakes were also the only systems where TEP had the potential to increase in the presence of large-bodied grazers, but such increases only occurred if grazer-induced changes in water clarity, macrophyte coverage, or nutrient availability stimulated specific growth rates of periphyton. In other scenarios, TEP declined by a maximum of 50%. In very large lakes (Z > 100 m), Bf was minor (< 10%) in the presence or absence of grazers, but increases in littoral habitat and the stimulation of benthic production in these ecosystems could be of ecological relevance because littoral zones in large lakes contain a relatively high proportion of within-lake biodiversity and are important for whole-lake food webs.

  10. Unexplained gonad alterations in whitefish (Coregonus spp.) from Lake Thun, Switzerland: levels of persistent organic pollutants in different morphs.

    PubMed

    Bogdal, Christian; Naef, Michael; Schmid, Peter; Kohler, Martin; Zennegg, Markus; Bernet, Daniel; Scheringer, Martin; Hungerbühler, Konrad

    2009-01-01

    Since 2000, a surprisingly high number of macroscopical gonad alterations has been reported in whitefish (Coregonus spp.) from Lake Thun, Switzerland. This unique phenomenon is still unexplained and has received much public attention. As one possible trigger for these effects, the presence of persistent, bioaccumulative and toxic compounds acting as endocrine disruptors in the lake has been discussed. In this study, concentrations of selected persistent organic pollutants were examined in two morphs of whitefish from Lake Thun and their link to the observed abnormalities was investigated. Analyzed compound classes included polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and dibenzofurans, polychlorinated naphthalenes, polybrominated diphenyl ethers and hexabromocyclododecanes. The target substances were identified in all samples and concentrations of the analyzed compounds were highly correlated among each other. These correlations show that the analyzed substances have the same distribution pattern throughout the lake and that uptake, accumulation and elimination processes are similar. Significant differences in contaminant levels within the samples existed between the two analyzed morphs of whitefish, most likely due to different age, food patterns and growth rate. No difference in contaminant levels was observed between fish with abnormal gonads and fish with normal gonads, suggesting no causal link between the investigated lipophilic organohalogen compounds present in fish and the observed gonad abnormalities in whitefish from Lake Thun. A comparison to existing data shows that concentrations in Lake Thun whitefish are at the lower bound of contaminant levels in whitefish from Swiss lakes or from European waters.

  11. Do zebra mussels (Dreissena polymorpha) alter lake water chemistry in a way that favours Microcystis growth?

    PubMed

    Bykova, Olga; Laursen, Andrew; Bostan, Vadim; Bautista, Joseph; McCarthy, Lynda

    2006-12-01

    This study examined possible relationships between the presence of zebra mussels (Dreissena polymorpha) and Microcystis spp. abundance. Experiments were conducted in 12 microcosms designed to mimic shallow lake ecosystems. Fresh, aerated water with phytoplankton (pseudokirchneriella spp. and Microcystis spp.) was pumped into each microcosm daily to ensure zebra mussels were exposed to oxygen and food. Microcosms containing zebra mussels experienced significantly higher fluxes of nitrate (p=0.019) and lower fluxes of ortho-phosphate (p=0.047) into sediments. In a second experiment, water column nutrient concentrations were compared in microcosms with and without live zebra mussels. Consistent with results of the previous experiment, microcosms with zebra mussels had significantly less nitrate (p=0.023) and organic nitrogen (p=0.003) in the water column, while ammonium (p=0.074), phosphate (p=0.491), and dissolved organic carbon (p=0.820) in the water column were not different between microcosms with or without zebra mussels. Microcosms with zebra mussels also experienced a reduction in green algae (pseudokirchneriella) (p<0.001) and an increase in abundance of Microcystis (p<0.001) relative to microcosms without zebra mussels. In an experiment without zebra mussels, nutrient ratios (N/P) were manipulated to determine potential links between N/P and relative abundance of each phytoplankton. Manipulation of N/P was intended to mimic differences observed in microcosms with and without zebra mussels in the previous experiment. Low N/P (mimicking microcosms with zebra mussels) was related to an increase in Microcystis (p<0.001) and Microcystis/Pseudokirchneriella biovolume (p<0.001). It is this shift in N/P, and possibly some level of selective feeding, that is believed to have driven changes in the relative abundance of Microcystis. In lakes invaded by zebra mussels, alterations in the processing of nitrogen and phosphorus could contribute to the re-emergence of

  12. Lake

    ERIC Educational Resources Information Center

    Wien, Carol Anne

    2008-01-01

    The lake is blue black and deep. It is a glaciated finger lake, clawed out of rock when ice retracted across Nova Scotia in a northerly direction during the last ice age. The lake is narrow, a little over a mile long, and deep, 90 to 190 feet in places according to local lore, off the charts in others. The author loves to swim there, with a sense…

  13. Do invasive quagga mussels alter CO2 dynamics in the Laurentian Great Lakes?

    NASA Astrophysics Data System (ADS)

    Lin, Peng; Guo, Laodong

    2016-12-01

    The Laurentian Great Lakes have experienced unprecedented ecological and environmental changes, especially after the introduction of invasive quagga mussel (Dreissena rostriformis bugensis). While impacts on ecological functions have been widely recognized, the response of carbon dynamics to invasive species remains largely unknown. We report new CO2 data showing significant increases in pCO2 (up to 800 μatm in Lake Michigan) and CO2 emission fluxes in most of the Great Lakes compared to those prior to or during the early stage of the colonization of invasive quagga mussels. The increased CO2 supersaturation is most prominent in Lakes Huron and Michigan, followed by Lakes Ontario and Erie, but no evident change was observed in Lake Superior. This trend mirrors the infestation extent of invasive quagga mussels in the Great Lakes and is consistent with the decline in primary production and increase in water clarity observed pre- and post-Dreissena introduction, revealing a close linkage between invasive species and carbon dynamics. The Great Lakes have become a significant CO2 source to the atmosphere, emitting >7.7 ± 1.0 Tg-C annually, which is higher than the organic carbon burial rate in global inland-seas and attesting to the significant role of the Laurentian Great Lakes in regional/global CO2 budget and cycling.

  14. Do invasive quagga mussels alter CO2 dynamics in the Laurentian Great Lakes?

    PubMed Central

    Lin, Peng; Guo, Laodong

    2016-01-01

    The Laurentian Great Lakes have experienced unprecedented ecological and environmental changes, especially after the introduction of invasive quagga mussel (Dreissena rostriformis bugensis). While impacts on ecological functions have been widely recognized, the response of carbon dynamics to invasive species remains largely unknown. We report new CO2 data showing significant increases in pCO2 (up to 800 μatm in Lake Michigan) and CO2 emission fluxes in most of the Great Lakes compared to those prior to or during the early stage of the colonization of invasive quagga mussels. The increased CO2 supersaturation is most prominent in Lakes Huron and Michigan, followed by Lakes Ontario and Erie, but no evident change was observed in Lake Superior. This trend mirrors the infestation extent of invasive quagga mussels in the Great Lakes and is consistent with the decline in primary production and increase in water clarity observed pre- and post-Dreissena introduction, revealing a close linkage between invasive species and carbon dynamics. The Great Lakes have become a significant CO2 source to the atmosphere, emitting >7.7 ± 1.0 Tg-C annually, which is higher than the organic carbon burial rate in global inland-seas and attesting to the significant role of the Laurentian Great Lakes in regional/global CO2 budget and cycling. PMID:27996017

  15. Do invasive quagga mussels alter CO2 dynamics in the Laurentian Great Lakes?

    PubMed

    Lin, Peng; Guo, Laodong

    2016-12-20

    The Laurentian Great Lakes have experienced unprecedented ecological and environmental changes, especially after the introduction of invasive quagga mussel (Dreissena rostriformis bugensis). While impacts on ecological functions have been widely recognized, the response of carbon dynamics to invasive species remains largely unknown. We report new CO2 data showing significant increases in pCO2 (up to 800 μatm in Lake Michigan) and CO2 emission fluxes in most of the Great Lakes compared to those prior to or during the early stage of the colonization of invasive quagga mussels. The increased CO2 supersaturation is most prominent in Lakes Huron and Michigan, followed by Lakes Ontario and Erie, but no evident change was observed in Lake Superior. This trend mirrors the infestation extent of invasive quagga mussels in the Great Lakes and is consistent with the decline in primary production and increase in water clarity observed pre- and post-Dreissena introduction, revealing a close linkage between invasive species and carbon dynamics. The Great Lakes have become a significant CO2 source to the atmosphere, emitting >7.7 ± 1.0 Tg-C annually, which is higher than the organic carbon burial rate in global inland-seas and attesting to the significant role of the Laurentian Great Lakes in regional/global CO2 budget and cycling.

  16. Sensitivity of alpine and subalpine lakes to acidification from atmospheric deposition in Grand Teton National Park and Yellowstone National Park, Wyoming

    USGS Publications Warehouse

    Nanus, Leora; Campbell, Donald H.; Williams, Mark W.

    2005-01-01

    The sensitivity of 400 lakes in Grand Teton and Yellowstone National Parks to acidification from atmospheric deposition of nitrogen and sulfur was estimated based on statistical relations between acid-neutralizing capacity concentrations and basin characteristics to aid in the design of a long-term monitoring plan for Outstanding Natural Resource Waters. Acid-neutralizing capacity concentrations that were measured at 52 lakes in Grand Teton and 23 lakes in Yellowstone during synoptic surveys were used to calibrate the statistical models. Three acid-neutralizing capacity concentration bins (bins) were selected that are within the U.S. Environmental Protection Agency criteria of sensitive to acidification; less than 50 microequivalents per liter (?eq/L) (0-50), less than 100 ?eq/L (0-100), and less than 200 ?eq/L (0-200). The development of discrete bins enables resource managers to have the ability to change criteria based on the focus of their study. Basin-characteristic information was derived from Geographic Information System data sets. The explanatory variables that were considered included bedrock type, basin slope, basin aspect, basin elevation, lake area, basin area, inorganic nitrogen deposition, sulfate deposition, hydrogen ion deposition, basin precipitation, soil type, and vegetation type. A logistic regression model was developed and applied to lake basins greater than 1 hectare in Grand Teton (n = 106) and Yellowstone (n = 294). A higher percentage of lakes in Grand Teton than in Yellowstone were predicted to be sensitive to atmospheric deposition in all three bins. For Grand Teton, 7 percent of lakes had a greater than 60-percent probability of having acid-neutralizing capacity concentrations in the 0-50 bin, 36 percent of lakes had a greater than 60-percent probability of having acid-neutralizing capacity concentrations in the 0-100 bin, and 59 percent of lakes had a greater than 60-percent probability of having acid-neutralizing capacity

  17. Mineral magnetism and other characteristics of sediments from a sub-alpine lake (3080 m a.s.l.) in central east China and their implications on environmental changes for the last 5770 years

    NASA Astrophysics Data System (ADS)

    Wang, Hongya; Song, Yaqiong; Cheng, Ying; Luo, Yao; Zhang, Cai'na; Gao, Yishen; Qiu, An'an; Deng, Lei; Liu, Hongyan

    2016-10-01

    A sediment sequence (SQC07) was recovered from Sanqing Chi, a small sub-alpine lake (3080 m a.s.l.) on Taibai (3767 m a.s.l.), the highest mountain in east mainland China (east of 105°). The Mountain is also the highest part and central massif of the Qinling Mountain Range functioning as the boundary between the warm temperate climate zone to the north and sub-tropical climate zone to the south in east China. Soils and debris were also sampled from the catchment of Sanqing Chi. SQC07 was AMS 14C dated. Mineral magnetism was measured for the sediment sequence and catchment samples. Particle-size, TOC and TN analysis were undertaken on SQC07, while pollen analysis was made for the sediment sequence and surface-soil samples. With the mineral magnetism of the catchment materials, the magnetic and other characteristics of SQC07 indicate the environmental changes occurring on the high altitudes of Taibai Mountain during the past 5770 years. Environments were still moderately warm and wet over 5770-5100 cal. yr BP around this sub-alpine lake. Then cold and dry conditions persisted in the period of 5100-4000 cal. yr BP. Local environments began to ameliorate from 4000 cal. yr BP onwards and were thus generally warm and wet over 4000-1200 cal. yr BP. The warmth and wetness culminated in 1200-800 cal. yr BP. During the period of 800-400 cal. yr BP, cold and arid conditions again predominated. Environments have subsequently become warm and humid since ∼400 cal. yr BP. The overall trend of the changes is coincident with what have been identified at several other sites in east mainland China and Taiwan. Presumably, the deterioration over 5100-4000 cal. yr BP marks the termination of the Holocene optimum, corresponds to or encompasses Holocene event 3, while the deterioration occurring in 800-400 cal. yr BP may correspond to LIA cooling. However, they appear to have commenced earlier than the aforementioned sites at relatively low altitudes in east mainland China or even

  18. Crystallization process of zircon and fergusonite during hydrothermal alteration in Nechalacho REE deposit, Thor Lake, Canada

    NASA Astrophysics Data System (ADS)

    Hoshino, M.; Watanabe, Y.; Murakami, H.; Kon, Y.; Tsunematsu, M.

    2012-04-01

    The core samples of two drill holes, which penetrate sub-horizontal mineralized horizons at Nechalacho REE deposit in the Proterozoic Thor Lake syenite, Canada, were studied in order to clarify magmatic and hydrothermal processes that enriched HFSE (e.g. Zr, Nb, Y and REE). Zircon is the most common REE minerals in Nechalacho REE deposit. The zircon is divided into five types as follows: Type-1 zircon occurs as single grain in phlogopite and the chondrite-normalized REE pattern is characterized by a steeply-rising slope from the LREE to the HREE with a positive Ce-anomaly and negative Eu-anomaly. This chemical characteristic is similar to that of igneous zircon. Type-2 zircon consists of HREE-rich magmatic porous core and LREE-Nb-F-rich hydrothermal rim. This type zircon is mostly included in phlogopite and fluorite, and occasionally in microcline. Type-3 zircon is characterized by euhedral to anhedral crystal, occurring in a complex intergrowth with REE fluorocarbonates. Type-3 zircons have high contents of REE, Nb and fluorine. Type-4 zircon consists of porous-core and -rim zones, but their chemical compositions are similar to each other. This type zircon is a subhedral crystal rimmed by fergusonite. Type-5 zircon is characterized by smaller, porous and subhedral to anhedral crystals. The interstices between small zircons are filled by fergusonite. Type-4 and -5 zircons show low REE and Nb contents. Occurrences of these five types of zircon are different according to the depth and degree of the alteration by hydrothermal solutions rich in F- and CO3 of the two drill holes, which permit a model for evolution of the zircon crystallization in Nechalacho REE deposit as follows: (1) type-1 (single magmatic zircon) is formed in miaskitic syenite. (2) LREE-Nb-F-rich hydrothermal zircon formed around HREE-rich magmatic zircon (type-2 zircon); (3) type-3 zircon crystallized thorough F and CO3-rich hydrothermal alteration of type-2 zircon which formed the complex

  19. Large Rock-Slope Failures Impacting on Lakes - Event Reconstruction and Interaction Analysis in Two Alpine Regions Using Sedimentology and Geophysics

    NASA Astrophysics Data System (ADS)

    Knapp, S.; Anselmetti, F.; Gilli, A.; Krautblatter, M.; Hajdas, I.

    2016-12-01

    Massive rock-slope failures are responsible for more than 60% of all catastrophic landslides disasters. Lateglacial and Holocene rock-slope failures often occur as multistage failures, but we have only limited datasets to reconstruct detailed stages and still aim at improving our knowledge of mobility processes. In this context, studying lakes will become more and more important for two main reasons. On the one hand, the lake background sedimentation acts as a natural chronometer, which enables the stratigraphic positioning of events and helps to reconstruct the event history. This way we will be able to improve our knowledge on multistage massive rock-slope failures. On the other hand, climate warming forces us to face an increase of lakes forming due to glacial melting, leading to new hazardous landscape settings. We will be confronted with complex reaction chains and feedback loops related to rock-slope instability, stress adaptation, multistage rock-slope failures, lake tsunamis, entrainment of water and fines, and finally lubrication. As a result, in future we will have to deal more and more with failed rock material impacting on lakes with much longer runout-paths than expected, and which we have not been able to reconstruct in our models so far. Here we want to present the key findings of two of our studies on lake sediments related to large rock-slope failures: We used reflection seismic profiles and sediment cores for the reconstruction of the rockfall history in the landslide-dammed Lake Oeschinen in the Bernese Oberland, Switzerland, where we detected and dated ten events and correlated them to (pre)historical data. As a second project, we have been working on the mobility processes of the uppermost sediments deposited during the late event stadium of the Eibsee rock avalanche at Mount Zugspitze in the Bavarian Alps, Germany. In the reflection seismic profiles we detected sedimentary structures that show high levels of fluidization and thus would hint at

  20. Well construction information, lithologic logs, water level data, and overview of research in Handcart Gulch, Colorado: an alpine watershed affected by metalliferous hydrothermal alteration

    USGS Publications Warehouse

    Caine, Jonathan Saul; Manning, Andrew H.; Verplanck, Philip L.; Bove, Dana J.; Kahn, Katherine Gurley; Ge, Shemin

    2006-01-01

    Integrated, multidisciplinary studies of the Handcart Gulch alpine watershed provide a unique opportunity to study and characterize the geology and hydrology of an alpine watershed along the Continental Divide. The study area arose out of the donation of four abandoned, deep mineral exploration boreholes to the U.S. Geological Survey for research purposes by Mineral Systems Inc. These holes were supplemented with nine additional shallow holes drilled by the U.S. Geological Survey along the Handcart Gulch trunk stream. All of the holes were converted into observation wells, and a variety of data and samples were measured and collected from each. This open-file report contains: (1) An overview of the research conducted to date in Handcart Gulch; (2) well location, construction, lithologic log, and water level data from the research boreholes; and (3) a brief synopsis of preliminary results. The primary purpose of this report is to provide a research overview as well as raw data from the boreholes. Interpretation of the data will be reported in future publications. The drill hole data were tabulated into a spreadsheet included with this digital open-file report.

  1. Spatial and temporal patterns in water chemistry of two high elevation lakes in southeast Wyoming

    Treesearch

    Robert C. Musselman

    1995-01-01

    The Glacier Lakes Ecosystem Experiments Site (GLEES) was established to examine the effects of atmospheric deposition and climate change on alpine and subalpine ecosystems. The site contains East Glacier Lake (3282 m elevation) and West Glacier Lake (3276 m elevation), and their watersheds. These two small lakes are located 120m from each other at the alpine/subalpine...

  2. ALTERATIONS IN SEXUALLY DIMORPHIC BIOTRANSFORMATION OF TESTOSTERONE IN JUVENILE AMERICAN ALLIGATORS (ALLIGATOR MISSISSIPPIENSIS) FROM CONTAMINATED LAKES

    EPA Science Inventory

    The goal of this study was to determine whether hepatic biotransformation of testosterone is normally sexually dimorphic in juvenile alligators and whether living in a contaminated environment affects hepatic dimorphism. Lake Woodruff served as our reference site. Moonshine Bay, ...

  3. ALTERATIONS IN SEXUALLY DIMORPHIC BIOTRANSFORMATION OF TESTOSTERONE IN JUVENILE AMERICAN ALLIGATORS (ALLIGATOR MISSISSIPPIENSIS) FROM CONTAMINATED LAKES

    EPA Science Inventory

    The goal of this study was to determine whether hepatic biotransformation of testosterone is normally sexually dimorphic in juvenile alligators and whether living in a contaminated environment affects hepatic dimorphism. Lake Woodruff served as our reference site. Moonshine Bay, ...

  4. Comparative responses of Dryas octopetala to simulated changes in climate from alpine, low- and high arctic ITEX sites

    SciTech Connect

    Welker, J.M.; Parsons, A.N.; Walker, M.D. |||

    1995-06-01

    Field manipulations of environmental conditions have been established in dry tundra sites on Niwot Ridge, CO, Toolik Lake, AK and on Svalbard, Norway as part of the International Tundra Experiment (ITEX). Dryas octopetala is the dominant species at all three sites where we have examined organismic and ecosystem responses to similar increases in temperature. Leaf and seed mass differ significantly between all sites and warmer temperatures resulted in reductions in leaf mass at both the high and low arctic sites in the initial year, but this was not observed at the alpine site. Reductions in leaf mass were accompanied by changes in leaf demography. Seed masses were inherently different between sites, being largest from plants in the alpine tundra. Plants in the alpine and in the high arctic had higher seed weights when warmed. By the end of the second year, leaf C:N ratios were higher in alpine plants which were warmed. These organismic responses may set the stage for altered colonization of bare ground while changes in C:N ratios may modify decomposition rates linking organismic and ecosystem dynamics.

  5. Snow deposition, melt, runoff, and chemistry in a small alpine watershed, Emerald Lake Basin, Sequoia National Park. Final report, 1 July 1984-31 March 1987

    SciTech Connect

    Dozier, J.; Melack, J.M.; Marks, D.; Elder, K.; Kattelmann, R.

    1987-03-01

    The report describes the first two years of an investigation of the snow chemistry and hydrology of the Emerald Lake Watershed in Sequoia National Park. The investigation examined the impact of acid deposition on high-elevation ecosystems of the Sierra Nevada. The following aspects of snow deposition and melt were studied: energy inputs; pattern of snow deposition and ablation; snowpack, meltwater and runoff chemistry; stream hydrology during the melt period.

  6. Alteration in hematology of Labeo rohita under stress of pollution from Lakes of Bangalore, Karnataka, India.

    PubMed

    Zutshi, Bela; Prasad, S G Raghu; Nagaraja, R

    2010-09-01

    Blood is an indicator of physiological condition of an animal. Therefore, a field study was conducted to investigate the hematological parameters of wild population of rohu, Labeo rohita (Ham). The following aspects were evaluated in blood: hemoglobin content, red blood cell (RBC) and white blood cell (WBC) count, packed cell volume (PCV), and mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC) values, and in plasma: cholesterol, protein, and glucose levels. For this purpose, rohu fish of varying sizes and weights were sampled from Hebbal (receiving a storm water drain) and Chowkalli lake (received domestic sewage and industrial effluents from various sources and was more polluted than Hebbal lake). It revealed noticeable differences in hemoglobin content, RBC and WBC count, and PCV and MCHC values. Severe anemia can be marked by a significant decrease in RBC count (p < 0.5), hemoglobin content, and PCV and MCHC values, whereas an increase in leukocyte count and MCV values were observed in fish from Chowkalli lake. Fish from lake B had fewer RBC and low concentration of serum protein and cholesterol. Serum concentration of glucose showed initial higher levels and then low concentration (900-1,500 g) in fish from lake B when compared to lake A. The variation in values of different parameters can be attributed to exposure of fish to various types of pollutants present mainly in the Chowkalli lake which receives heavy metals, synthetic detergents, petroleum products, and other acid and alkali substances from the nearby local industries. Other observations of these fish include dark body color and aggressive nature of fish.

  7. Meteorological and land use controls on past and present hydro-geomorphic processes in the pre-alpine environment: an integrated lake-catchment study at the Petit Lac d'Annecy, France

    NASA Astrophysics Data System (ADS)

    Foster, G. C.; Dearing, J. A.; Jones, R. T.; Crook, D. S.; Siddle, D. J.; Harvey, A. M.; James, P. A.; Appleby, P. G.; Thompson, R.; Nicholson, J.; Loizeau, J.-L.

    2003-11-01

    A wide range of environmental records is integrated in order to reconstruct the mechanisms of flooding and sediment transport within the 170 km2 Petit Lac catchment, Annecy, France, over time scales of 10-1 to 102 years. These records include sequential lake sediment trap samples and cores, floodplain stratigraphies, dated landform assemblages, hydro-meteorological records, and documented histories of river channel and land-use change. Mineral magnetic measurements are used as the basis for classifying catchment sediment sources and tracing sediment movements through time. Records of magnetic susceptibility for monthly sediment trap samples (1998-99) track seasonal discharge, peaking in winter and spring. Magnetic records in lake sediment cores are compared against and tuned to precipitation records to provide dated proxy records for past discharge spanning sub-annual to decadal time scales back to 1826. Calculated sediment accumulation rates in lake sediment cores are used as proxies for time-averaged catchment sediment load. Analysis of the results reveals that climate and land-use controls on the hydrological and sediment system are complex and vary according to the time scale of observation. In general, cycles of agricultural expansion and deforestation appear to have been the major cause of shifts in the sediment system through the late Holocene. Deforestation in the 18th century may have caused a number of high-magnitude flood and erosion events. As the time scale of observation becomes shorter, changes in climate and hydro-meteorological conditions become progressively more important. Since the mid-19th century, smoothed records of discharge roughly follow annual precipitation; this is in contrast to sediment load, which follows the trend of declining land-use pressures. Episodic erosion events during this recent period seem to be linked to geomorphic evidence for slope instability in the montane and sub-alpine zones, triggered by intense summer rainfall. At

  8. Plants in alpine environments

    USGS Publications Warehouse

    Germino, Matthew J.

    2014-01-01

    Alpine and subalpine plant species are of special interest in ecology and ecophysiology because they represent life at the climate limit and changes in their relative abundances can be a bellwether for climate-change impacts. Perennial life forms dominate alpine plant communities, and their form and function reflect various avoidance, tolerance, or resistance strategies to interactions of cold temperature, radiation, wind, and desiccation stresses that prevail in the short growing seasons common (but not ubiquitous) in alpine areas. Plant microclimate is typically uncoupled from the harsh climate of the alpine, often leading to substantially warmer plant temperatures than air temperatures recorded by weather stations. Low atmospheric pressure is the most pervasive, fundamental, and unifying factor for alpine environments, but the resulting decrease in partial pressure of CO2 does not significantly limit carbon gain by alpine plants. Factors such as tree islands and topographic features create strong heterogeneous mosaics of microclimate and snow cover that are reflected in plant community composition. Factors affecting tree establishment and growth and formation of treeline are key to understanding alpine ecology. Carbohydrate and other carbon storage, rapid development in a short growing season, and physiological function at low temperature are prevailing attributes of alpine plants. A major contemporary research theme asks whether chilling at alpine-treeline affects the ability of trees to assimilate the growth resources and particularly carbon needed for growth or whether the growth itself is limited by the alpine environment. Alpine areas tend to be among the best conserved, globally, yet they are increasingly showing response to a range of anthropogenic impacts, such as atmospheric deposition.

  9. Changes in litter quality induced by nutrient addition alter litter decomposition in an alpine meadow on the Qinghai-Tibet Plateau

    PubMed Central

    Zhu, Wenyan; Wang, Jinzhou; Zhang, Zhenhua; Ren, Fei; Chen, Litong; He, Jin-Sheng

    2016-01-01

    The effects of nitrogen (N) and phosphorus (P) addition on litter decomposition are poorly understood in Tibetan alpine meadows. Leaf litter was collected from plots within a factorial N × P addition experiment and allowed to decompose over 708 days in an unfertilized plot to determine the effects of N and/or P addition on litter decomposition. Results showed that nutrient addition significantly affected initial P and P-related biochemical properties of litter from all four species. However, the responses of litter N and N-related biochemical properties to nutrient addition were quite species-specific. Litter C decomposition and N release were species-specific. However, N and P addition significantly affected litter P release. Ratios of Hemicellulose + Cellulose to N and P were significantly related to litter C decomposition; C:N ratio was a determinant of litter N release; and C:P and (Hemicellulose + Cellulose):P controlled litter P release. Overall, litter C decomposition was controlled by litter quality of different plant species, and strongly affected by P addition. Increasing N availability is likely to affect litter C decomposition more indirectly by shifting plant species composition than directly by improving litter quality, and may accelerate N and P cycles, but shift the ecosystem to P limitation. PMID:27694948

  10. Changes in litter quality induced by nutrient addition alter litter decomposition in an alpine meadow on the Qinghai-Tibet Plateau.

    PubMed

    Zhu, Wenyan; Wang, Jinzhou; Zhang, Zhenhua; Ren, Fei; Chen, Litong; He, Jin-Sheng

    2016-10-03

    The effects of nitrogen (N) and phosphorus (P) addition on litter decomposition are poorly understood in Tibetan alpine meadows. Leaf litter was collected from plots within a factorial N × P addition experiment and allowed to decompose over 708 days in an unfertilized plot to determine the effects of N and/or P addition on litter decomposition. Results showed that nutrient addition significantly affected initial P and P-related biochemical properties of litter from all four species. However, the responses of litter N and N-related biochemical properties to nutrient addition were quite species-specific. Litter C decomposition and N release were species-specific. However, N and P addition significantly affected litter P release. Ratios of Hemicellulose + Cellulose to N and P were significantly related to litter C decomposition; C:N ratio was a determinant of litter N release; and C:P and (Hemicellulose + Cellulose):P controlled litter P release. Overall, litter C decomposition was controlled by litter quality of different plant species, and strongly affected by P addition. Increasing N availability is likely to affect litter C decomposition more indirectly by shifting plant species composition than directly by improving litter quality, and may accelerate N and P cycles, but shift the ecosystem to P limitation.

  11. Asynchronous evolution of the isotopic composition and amount of precipitation in north China during the Holocene revealed by a record of compound-specific carbon and hydrogen isotopes of long-chain n-alkanes from an alpine lake

    NASA Astrophysics Data System (ADS)

    Rao, Zhiguo; Jia, Guodong; Li, Yunxia; Chen, Jianhui; Xu, Qinghai; Chen, Fahu

    2016-07-01

    Both the timing of the maximum East Asian summer monsoon (EASM) intensity in monsoonal China and the environmental significance of the Chinese stalagmite oxygen isotopic record (δ18O) have been debated. Here, we present a ca. 120-year-resolution compound-specific carbon (δ13C) and hydrogen (δD) isotopes of terrestrial long-chain n-alkanes extracted from a well-dated sediment core from an alpine lake in north China. Our δ13C data, together with previously reported pollen data from a parallel core, demonstrate a humid mid-Holocene from ca. 8-5 ka BP. Assuming that the climatic humidity of north China is an indicator of the EASM intensity, then the maximum EASM intensity occurred in the mid-Holocene. Our δD data reveal a similar long-term trend to the δ18O record from nearby Lianhua Cave, indicating that the synchronous δD and δ18O records faithfully record the δD and δ18O of precipitation, respectively. The most negative δD and δ18O values occur in the early-mid Holocene, from ca. 11-5 ka BP. This contrast in the timing of isotopic variations demonstrates a complex relationship between the isotopic composition of precipitation and precipitation amount, or EASM intensity. Further comparisons indicate a possible linkage between the precipitation amount in north China and the west-east thermal gradient in the equatorial Pacific. In addition, the temperature of the moisture source area may play an important role in determining the isotopic composition of precipitation in monsoonal China.

  12. Evidence for orbital and North Atlantic climate forcing in alpine Southern California between 125 and 10 ka from multi-proxy analyses of Baldwin Lake

    NASA Astrophysics Data System (ADS)

    Glover, Katherine C.; MacDonald, Glen M.; Kirby, Matthew E.; Rhodes, Edward J.; Stevens, Lora; Silveira, Emily; Whitaker, Alexis; Lydon, Scott

    2017-07-01

    We employed a new, multi-proxy record from Baldwin Lake (∼125-10 ka) to examine drivers of terrestrial Southern California climate over long timescales. Correlated bulk organic and biogenic silica proxy data demonstrated high-amplitude changes from 125 to 71 ka, suggesting that summer insolation directly influenced lake productivity during MIS 5. From 60 to 57 ka, hydrologic state changes and events occurred in California and the U.S. Southwest, though the pattern of response varied geographically. Intermediate, less variable levels of winter and summer insolation followed during MIS 3 (57-29 ka), which likely maintained moist conditions in Southern California that were punctuated with smaller-order, millennial-scale events. These Dansgaard-Oeschger events brought enhanced surface temperatures (SSTs) to the eastern Pacific margin, and aridity to sensitive terrestrial sites in the Southwest and Southern California. Low temperatures and reduced evaporation are widespread during MIS 2, though there is increasing evidence for moisture extremes in Southern California from 29 to 20 ka. Our record shows that both orbital-scale radiative forcing and rapid North Atlantic temperature perturbations were likely influences on Southern California climate prior to the last glacial. However, these forcings produced a hydroclimatic response throughout California and the U.S. Southwest that was geographically complex. This work highlights that it is especially urgent to improve our understanding of the response to rapid climatic change in these regions. Enhanced temperature and aridity are projected for the rest of the 21st century, which will place stress on water resources.

  13. Seismic properties and effects of hydrothermal alteration on Volcanogenic Massive Sulfide (VMS) deposits at the Lalor Lake in Manitoba, Canada

    NASA Astrophysics Data System (ADS)

    Miah, Khalid H.; Bellefleur, Gilles; Schetselaar, Ernst; Potter, David K.

    2015-12-01

    Borehole sonic and density logs are essential for mineral exploration at depth, but its limited availability to link rock properties of different ore forming geologic structure is a hindrance to seismic data interpretations. In situ density and velocity logs provide first order control on the reflectivity of various lithologic units. We analyzed borehole logs from 12 drill holes over and around the Lalor VMS deposits geographically located in the northern Manitoba, Canada, in an attempt to characterize lithologic units based on its seismic properties. The Lalor Lake deposit is part of the Paleoproterozoic Flin Flon Belt, and associated with an extensive hydrothermal alteration system. Volcanogenic Massive Sulfide (VMS) zones are distributed in several ore lenses with relatively shallower facies comprise solid to solid sulfides, tend to be disseminated or Stringer sulfides, while deeper lenses are gold and silver enriched and occurred in the highly altered footwall region. Our analysis suggests that massive sulfide and diorite have higher acoustic impedance than other rock units, and can produce useful reflection signatures in seismic data. Bivariate distributions of P-wave velocity, density, acoustic impedance and Poisson's ratio in end-member mineral cones were used for qualitative assessment of the extent of alteration of various lithologic units. It can be inferred that hydrothermal alteration has considerably increased P-wave velocity and density of altered argillite and felsic volcanic rocks in comparison to their corresponding unaltered facies. Amphibole, garnet, kyanite, pyrite, sphalerite and staurolite are the dominant end-member alteration minerals affecting seismic rock properties at the VMS site.

  14. Effects of Short-Term Thermal Alteration on Organic Matter in Experimentally-Heated Tagish Lake Observed by Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Chan, Q. H. S.; Nakato, A.; Zolensky, M. E.; Nakamura, T.; Kebukawa, Y.; Maisano, J.; Colbert, M.; Martinez, J. E.

    2017-01-01

    Carbonaceous chondrites exhibit a wide range of aqueous and thermal alteration characteristics, while some are known to demonstrate mineralogical and petrologic evidence of having been thermally metamorphosed after aqueous alteration. This group of meteorites are commonly referred as thermally met-amorphosed carbonaceous chondrites (TMCCs), and their reflectance spectra show resemblances to that of C-type asteroids which typically have low albedos. This suggests that the surfaces of the C-type asteroids are also composed of both hydrous and dehydrated minerals, and thus TMCCs are among the best samples that can be studied in laboratory to reveal the true nature of the C-type asteroids. Although TMCCs are usually meteorites that were previously categorized as CI and CM chondrites, they are not strictly CI/CM because they exhibit isotopic and petrographic characteristics that significantly deviate from typical CI/CM. More appropriately, they are called CI-like and/or CM-like chondrites. Typical examples of TMCCs include the C2-ung/CM2TIV Belgica (B)-7904 and Yamato (Y) 86720. Thermal alteration is virtually complete in these meteorites and thus they are considered typical end-members of TMCCs exhibiting complete dehydration of matrix phyllosilicates. The estimated heating conditions are 10 to 103 days at 700 C to 1 to 100 hours at 890 C, i.e. short-term heating induced by impact and/or solar radiation. While the petrology and chemistry of TMCCs have only recently been extensively characterized, we have just begun to study in detail their organic contents. In order to understand how short-term heating affects the maturity of insoluble organic matter (IOM) in hydrous chondrites, we investigated experimentally-heated Tagish Lake meteorite using Raman spectroscopy, as the chemical and bulk oxygen isotopic compositions of the matrix of the carbonate (CO3)-poor lithology of the Tagish Lake (hereafter Tag) meteorite bears similarities to the TMCCs.

  15. Experimental soil warming and cooling alters the partitioning of recent assimilates: evidence from a (14)C-labelling study at the alpine treeline.

    PubMed

    Ferrari, A; Hagedorn, F; Niklaus, P A

    2016-05-01

    Despite concerns about climate change effects on ecosystems functioning, little is known on how plant assimilate partitioning changes with temperature. Particularly, large temperature effects might occur in cold ecosystems where critical processes are at their temperature limit. In this study, we tested temperature effects on carbon (C) assimilate partitioning in a field experiment at the alpine treeline. We warmed and cooled soils of microcosms planted with Pinus mugo or Leucanthemopsis alpina, achieving daily mean soil temperatures (3-10 cm depth) around 5.8, 12.7 and 19.2 °C in cooled, control and warmed soils. We pulse-labelled these systems with (14)CO2 for one photoperiod and traced (14)C over the successive 4 days. Plant net (14)C uptake increased steadily with soil temperature. However, (14)C amounts in fungal hyphae, soil microbial biomass, soil organic matter, and soil respiration showed a non-linear response to temperature. This non-linear pattern was particularly pronounced in P. mugo, with five times higher (14)C activities in cooled compared to control soils, but no difference between warmed and control soil. Autoradiographic analysis of the spatial distribution of (14)C in soils indicated that temperature effects on the vertical label distribution within soils depended on plant species. Our results show that plant growth, in particular root metabolism, is limited by low soil temperature. As a consequence, positive temperature effects on net C uptake may not be paralleled by similar changes in rhizodeposition. This has important implications for predictions of soil C storage, because rhizodeposits and plant biomass vary strongly in their residence times.

  16. Falling phytoplankton: altered access to the photic zone over 60 years of warming in Lake Baikal, Siberia

    NASA Astrophysics Data System (ADS)

    Hampton, S. E.; Izmest'eva, L. R.; Moore, M.; Katz, S. L.

    2011-12-01

    Vertical stratification of aquatic ecosystems can be strongly reinforced by long-term warming, altering access to suitable habitat differentially across plankton taxa. Surface waters in the world's most voluminous freshwater lake - Lake Baikal in Siberia - are warming at an average rate of 2.01°C century-1, with more dramatic warming in the summer (3.78°C century-1). This long-term warming trend occurs within seasonal cycles of freezing and thawing, and against the larger backdrop of shorter-term climate dynamics, such as those associated with the Pacific Decadal Oscillation and Arctic Oscillation, with which shifting Siberian weather patterns affect the timing of seasonal changes (e.g., stratification) at the lake. While the increasing temperature difference between surface and deeper waters implies stronger stratification in the summer in general, the available long-term temperature data are not sufficiently fine-scaled across depth to further resolve stratification patterns. However, analysis of long-term vertical phytoplankton distributions may give perspectives on the dynamics of the physical environment that plankton experience. For example, many of Lake Baikal's endemic, cold-adapted phytoplankton species are large and heavy diatoms that require strong mixing to remain suspended, a process that is suppressed by stronger summer stratification. Observed vertical patterns of algal distribution are consistent with the predictions of increased warming and intensified stratification with diatoms present in summer increasingly sinking far beyond the photic zone. Specifically, the average depth of diatoms in August, the most reliably stratified month at Lake Baikal, has increased from depths roughly aligned with photic zone (0.1% light penetration) limits (ca. 40 m) in the 1970s to average depths approximately 48 m below the photic zone by the end of the century. Concurrently, smaller motile algae such as cryptomonads have maintained or increased their presence in

  17. Hydrochemical Response to Drought Conditions at an Alpine Watershed, Colorado Front Range

    NASA Astrophysics Data System (ADS)

    Hill, K. R.; Williams, M. W.; Caine, N.; Janke, J. R.; Hartman, M. D.

    2007-12-01

    Extreme climate events play a key role in alpine hydrochemistry by altering source waters and flowpaths. Persistent drought conditions from 2000-2002 at Green Lakes Valley resulted in precipitation and streamflow about 75% of normal for the last 25 years. Surprisingly, both concentrations and fluxes of geochemical weathering products and nutrients increased during the drought at the higher elevation sites. Niwot Ridge LTER has continuously monitored streamflow, precipitation chemistry, and water quality for 25 years in Green Lakes Valley at 8 sites representing an elevation gradient extending from 3250 meters at the valley outlet to 4000 meters at the continental divide. Comparing continuous 5-year blocks of above-average precipitation (1993-1997) vs. below-average years (2000- 2004), both concentrations and fluxes were significantly higher during drought for base cations (p<0.05) throughout upper Green Lakes Valley. DAYCENT modeled predicted discharge correctly during the period of above-average precipitation but underpredicted discharge during drought conditions, suggesting an additional source of water. End Member Mixing Analyses (EMMA) conducted during 1996 constrains streamflow as a mixture of snowmelt, talus water, and groundwater with subsurface flowpaths contributing more than 50% of streamflow, even during snowmelt (Liu, 2004). However, EMMA results during drought years using chemical and isotopic compositions from surface water, talus springs, snowpits, snowmelt, soil water, and groundwater suggest an additional, unidentified source of streamflow. One possible end member is melting permafrost within the basin. We downscaled a qualitative, regional permafrost distribution model of the Colorado Front Range to investigate the potential role of melting permafrost on hydrochemical characteristics in Green Lakes Valley. Model results indicate that increasing mean annual air temperature by 1 degree Celsius results could melt 35% of permafrost in the watershed

  18. Effects of Short-Term Thermal Alteration on Organic Matter in Experimentally-Heated Tagish Lake Observed by Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Chan, Q. H. S.; Nakato, A.; Zolensky, M. E.; Nakamura, T.; Kebukawa, Y.

    2007-01-01

    Carbonaceous chondrites exhibit a wide range of aqueous and thermal alteration characteristics. Examples of the thermally metamorphosed carbonaceous chondrites (TMCCs) include the C2-ung/CM2TIVs Belgica (B)-7904 and Yamato (Y) 86720. The alteration extent is the most complete in these meteorites and thus they are considered typical end-members of TMCCs exhibiting complete dehydration of matrix phyllosilicates [1, 2]. The estimated heating conditions are 10 to 10(sup 3) days at 700 C to 1 to 100 hours at 890 C, i.e. short-term heating induced by impact and/or solar radiation [3]. The chemical and bulk oxygen isotopic compositions of the matrix of the carbonate (CO3)-poor lithology of the Tagish Lake (hereafter Tag) meteorite bears similarities to these TMCCs [4]. We investigated the experimentally-heated Tag with the use of Raman spectroscopy to understand how short-term heating affects the maturity of insoluble organic matter (IOM) in aqueously altered meteorites.

  19. What does a lake sediment terrigenous input record actually tell us? Tentative answers based on a multi-lakes source-to-sink approach in the 4000 km2 Arve-Rhône alpine catchment

    NASA Astrophysics Data System (ADS)

    Arnaud, F.; Révillon, S.; Giguet-Covex, C.; Wilhelm, B.; Jenny, J.-P.; Magny, M.; Von Grafenstein, U.; Poulenard, J.; Ployon, E.

    2012-04-01

    Since the emergence of paleolimnology as a scientific discipline, numerous studies attempted to link terrigenous input to environmental variables. In particular, it has been proposed that the total amount of river-borne sediment should be used as a mirror of "humidity", assuming the erosion flux is mainly driven by climate changes. Alternatively and in a sense, at the opposite, the recent development of Holocene paleo-studies and the growing interest for the reconstruction of past human-environment interactions led to postulate that since at least the Bronze age, humans became the main driver of erosion patterns. Indeed there is not really a scientific debate, each "church" hanging to its position: "pro-human" vs. "pro-climate". In this paper, we attempt to light the debate, based on an original approach which was led in the framework of the Pygmalion program. Rather than studying a single lake record, we tried to integrate results at various time and spatial scales within a 4000 km2, lithologically and morphologically complex catchment. The chosen area lies at the northern edge of French Alps: Arve river catchment, which drains among others the Mont Blanc massif, and its continuation after its junction with river Rhône, downstream Lake Geneva. After a river course of ca. 250 km, Lake Bourget represents a partial sink for erosion products when river Rhône flows within the lake during major floods. In this, Holocene-long sediment cores from Lake Bourget can be interpreted as a regional record of terrigenoux fluxes. Thanks to a set of 20 tributary samples, we led a source-to-sink approach, based on Nd isotopes. This led us to identify from the sediment record fluctuations in the main provenance of sediments. Moreover, the high resolution record of chemical weathering proxies (clay mineralogy and K/Ti ratio) gave important information upon the role of soil genesis in erosion patterns. This approach stated that the Little Ice Age has been an exceptional period of

  20. Altered thyroid status in lake trout (Salvelinus namaycush) exposed to co-planar 3,3',4,4',5-pentachlorobiphenyl.

    PubMed

    Brown, Scott B; Evans, Robert E; Vandenbyllardt, Lenore; Finnson, Ken W; Palace, Vince P; Kane, Andrew S; Yarechewski, Alvin Y; Muir, Derek C G

    2004-03-30

    Recent studies indicate that co-planar 3,3',4,4',5-pentachlorobiphenyl (PCB) congeners or their metabolites may disrupt thyroid function in fishes. Although co-planar PCB have been detected at microgram per kilogram levels in fish from contaminated areas, few studies have examined mechanisms whereby, co-planar PCBs may alter thyroid function in fish. We treated immature lake trout by intraperitoneal (i.p.)-injection or dietary gavage with vehicle containing 0, 0.7, 1.2, 25 or 40 microg 3,3',4,4',5-pentachlorobiphenyl (PCB 126) per kgBW. Blood and tissue samples were collected at various times up to 61 weeks following exposure. The treatments produced sustained dose-dependent elevations of tissue (PCB 126) concentrations. Thyroid epithelial cell height (TECH), plasma thyroxine (T4) and 3,3',5-triiodo-l-thyronine (T3) concentrations, hepatic 5'-monodeiodinase, hepatic glucuronidation of T4 and T3, as well as plasma T4 kinetics and fish growth were analyzed. Exposure to the highest doses of PCB 126 caused increased TECH, plasma T4 dynamics and T4-glucuronidation (T4-G). PCB 126 did not affect 5'-monodeiodinase and T3-glucuronidation (T3-G) and there were no effects on fish growth or condition. Because T3 status and growth were unaffected, the thyroid system was able to compensate for the alterations caused by the PCB 126 exposure. It is clear that concentrations of co-planar PCBs similar to those found in predatory fish from contaminated areas in the Great Lakes are capable of enhancing metabolism of T4. These changes may be of significance when T4 requirements are high for other reasons (e.g. periods of rapid growth, warm temperatures, metamorphosis, and parr-smolt transformation).

  1. Rapid Ecological Change in Two Contrasting Lake Ecosystems: Evidence of Threshold Responses, Altered Species Dynamics, and Perturbed Patterns of Variability

    NASA Astrophysics Data System (ADS)

    Simpson, G. L.

    2015-12-01

    Studying threshold responses to environmental change is often made difficult due to the paucity of monitoring data prior to and during change. Progress has been made via theoretical models of regime shifts or experimental manipulation but natural, real world, examples of threshold change are limited and in many cases inconclusive. Lake sediments provide the potential to examine abrupt ecological change by directly observing how species, communities, and biogeochemical proxies responded to environmental perturbation or recorded ecosystem change. These records are not problem-free; age uncertainties, uneven and variable temporal resolution, and time-consuming taxonomic work all act to limit the scope and scale of the data or complicate its analysis. Here I use two annually laminated records 1. Kassjön, a seasonally anoxic mesotrophic lake in N Sweden, and2. Baldeggersee, a nutrient rich, hardwater lake on the central Swiss Plateau to investigate lake ecosystem responses to abrupt environmental change using ideal paleoecological time series. Rapid cooling 2.2kyr ago in northern Sweden significantly perturbed the diatom community of Kassjön. Using wavelet analysis, this amelioration in climate also fundamentally altered patterns of variance in diatom abundances, suppressing cyclicity in species composition that required several hundred years to reestablish. Multivariate wavelet analysis of the record showed marked switching between synchronous and asynchronous species dynamics in response to rapid climatic cooling and subsequent warming. Baldeggersee has experienced a long history of eutrophication and the diatom record has been used as a classic illustration of a regime shift in response to nutrient loading. Time series analysis of the record identified some evidence of a threshold-like response in the diatoms. A stochastic volatility model identified increasing variance in composition prior to the threshold, as predicted from theory, and a switch from compensatory

  2. Changing climate and sea level alter Hg mobility at Lake Tulane, Florida, U.S.

    PubMed

    Jacobson, G L; Norton, S A; Grimm, E C; Edgar, T

    2012-11-06

    Between 45,000 cal years BP and the beginning of the Holocene, the accumulation rate for Hg in sediments of Lake Tulane, Florida ranged from ≈2 to 10 μg m(-2) yr(-1), compared with 53 μg Hg m(-2) yr(-1) in the 1985-1990 period of anthropogenic input. The locality experienced regional draw-down of the water table during the Wisconsinan glaciation, which lowered global sea level by nearly 130 m. Natural atmospheric deposition of Hg to the surrounding area resulted in long-term (ca. 100,000 years) sequestration of this atmospheric flux of Hg, primarily by adsorption in the oxic Al- and Fe-hydroxide-rich sandy subsoil. Global sea level rise during deglaciation led to a rising regional water table, flooding the oxidized soils surrounding Tulane. Iron and adsorbed Hg were mobilized by reductive dissolution and transported by groundwater flow to Lake Tulane and ultimately to the accumulating sediment. The accumulation rate of Hg (and Fe) increased rapidly about 16,000 cal years BP, peaked at nearly 60 μg Hg m(-2) yr(-1) ca. 13,000-14,000 cal years BP, declined sharply during the Younger Dryas, and then increased sharply to a second 60 μg Hg m(-2) yr(-1) peak about 5000 cal years BP. Thereafter, it declined nearly to background by 900 cal years BP. In similar geologic situations, rapid modern sea level rise will initiate this process globally, and may mobilize large accumulations of Hg and lesser amounts of As, and other redox sensitive metals to groundwater and surface water.

  3. Types and Mechanisms of Alterations on the Mesozoic Ophiolites (Lake Van Region-Turkey): Petrographical and Geochemical Approach

    NASA Astrophysics Data System (ADS)

    Yazıcı, Ömer; Üner, Tijen; Mutlu, Sacit; Depçi, Tolga

    2017-04-01

    Mesozoic ophiolites are widely located in the eastern part of Lake Van Basin. The ophiolitic rocks deformed during the rifting and/or closure period of the Neo-Tethyan Ocean are observed as tectonic slices in the region. These ophiolites are represented by volcano-sedimentary units, isolated dikes, and mafic-ultramafic rocks. The formation, emplacement and post-emplacement processes of these ophiolitic rocks can be understood owing to alterations as rodingitization, serpentinization, and listwaenitization. Three stages of sequent mineralization are detected in the ophiolitic rocks. First stage is pyrometasomatization, represented by metamorphic minerals (garnet, chlorite etc.), observed in intruded dikes. Second stage is hydrothermal alteration of mafic-ultramafic rocks namely serpentinization. Listwaenite alteration is the last stage of mineralization. According to petrographical investigations, garnet+chlorite+diopsite minerals are detected in rodengites. The conversion of the plagioclase minerals to the calcsilicatic minerals in rodengites suggests that these rocks are metasomatic rocks produced by Ca-rich fluids derived from serpentinization of the ultramafic rocks. The serpentine minerals (chrysotile-lizardite) can be distinguished from each other by their morphology as being platy or fibrous. Listwaenite alteration is followed by the formation of carbonate, silica, oxides and hydroxides. Chemical analysis of these rocks show that the listwaenites have an enrichment in Ni and Co contents while the rodingites have low SiO2 and high CaO and MgO values (SiO2 28,50 - 36,67%, CaO 11,99 - 20,88%, and MgO 7,99 - 17,73%). Alteration types observed on the ophiolitic rocks demonstrate that these rocks are metamorphised by low pressure and low to middle temperature conditions (greenshist facies). Serpentinization is pointing out an alteration which occurred during the emplacement of the ophiolites or the latter period. This study has been supported by Project number 2013

  4. CO2 enrichment alters diurnal stem radius fluctuations of 36-yr-old Larix decidua growing at the alpine tree line.

    PubMed

    Dawes, Melissa A; Zweifel, Roman; Dawes, Nicholas; Rixen, Christian; Hagedorn, Frank

    2014-06-01

    To understand how trees at high elevations might use water differently in the future, we investigated the effects of CO2 enrichment and soil warming (separately and combined) on the water relations of Larix decidua growing at the tree line in the Swiss Alps. We assessed diurnal stem radius fluctuations using point dendrometers and applied a hydraulic plant model using microclimate and soil water potential data as inputs. Trees exposed to CO2 enrichment for 9 yr showed smaller diurnal stem radius contractions (by 46 ± 16%) and expansions (42 ± 16%) compared with trees exposed to ambient CO2 . Additionally, there was a delay in the timing of daily maximum (40 ± 12 min) and minimum (63 ± 14 min) radius values for trees growing under elevated CO2 . Parameters optimized with the hydraulic model suggested that CO2 -enriched trees had an increased flow resistance between the xylem and bark, representing a more buffered water supply system. Soil warming did not alter diurnal fluctuation dynamics or the CO2 response. Elevated CO2 altered the hydraulic water flow and storage system within L. decidua trees, which might have contributed to enhanced growth during 9 yr of CO2 enrichment and could ultimately influence the future competitive ability of this key tree-line species.

  5. Evidence for Impact-induced Hydrothermal Alteration at the Lonar Crater, India, and Mistastin Lake, Canada

    NASA Technical Reports Server (NTRS)

    Newsom, H. E.; Hagerty, J. J.

    2003-01-01

    The 50,000 year old, 1.8km diameter Lonar crater is located in Maharashtra, India. This relatively small crater is of particular interest because of its unique morphological and mineralogical properties, which make it a valid analogue for similar craters on the surface of Mars. We show that even in this relatively small crater, substantial hydrothermal alteration of shocked breccias in the floor of the crater has occurred, probably due to the thermal effects of the impact event. The 38 my old, 28 km diameter, Mistastin crater contains an 80 m thick impact melt sheet. We have also documented the presence of alteration phases in the material from this larger crater.

  6. Chemical Compositional Indications of Aqueous Alteration for Whitewater Lake Boxworks, Veneers and Veins at Cape York, Mars

    NASA Astrophysics Data System (ADS)

    Clark, Benton; Gellert, R.; Squyres, S.; Arvidson, R.; Yen, A.; Rice, J.; Athena Science Team

    2013-10-01

    An area of partially-veneered, flat-lying rocks which also includes boxwork and linear veins contains a variety of compositions which are each indicative of minor to major aqueous alteration processes in the Cape York rim of Endeavour Crater. As analyzed by APXS x-ray fluorescence spectroscopy, the sets of unique elemental compositions correspond variously to Al-Si rich clays in boxwork veins, with Fe- and Cl-enriched salt veneers (Esperance samples); swarms of Ca sulfate veins (Ortiz samples); and, as indicated by remote sensing, mafic smectite alteration products in veneers (Chelmsford covering Azilda samples). Multiple offset analyses by APXS reveal clear trends and associations of certain elements, allowing inferences of mineralogies. In contrast to the acidic environment deduced for the genesis of the multiple-sulfate Burns formation sediments and shallow ferric-rich sulfate deposits beneath soils, these alteration products formed at more near-neutral pH, often with major chemical segregations and requiring high water-rock ratios comparable to a wide range of eminently habitable terrestrial environments. Several of these compositions are also rated high with respect to their potential for preservation of organic materials and biomarkers. Within distances of just tens of meters inside this so-called Whitewater Lake unit, this broad diversity exemplifies the tantalizing opportunities as well as challenges for future sample return missions to the red planet, which in this case could also be expanded to include nearby samples of Burns Fm sandstones, hematite concretions, light-toned spherules (Kirkwood), large gypsum veins (Homestake), martian global soils and surface dust.

  7. Waterborne ethynylestradiol induces vitellogenin and alters metallothionein expression in lake trout (Salvelinus namaycush).

    PubMed

    Werner, Julieta; Wautier, Kerry; Evans, Robert E; Baron, Christopher L; Kidd, Karen; Palace, Vince

    2003-02-26

    Estrogenic contaminants isolated from waters receiving sewage treatment plant effluents are known to induce the egg yolk precursor vitellogenin (VTG) in male fish. Levels of the metal binding protein metallothionein (MT) have also been shown to be affected by estrogens in fish. It has been postulated that MT declines in estrogen exposed fish to facilitate transfer of the essential metal Zn to cellular components required for VTG synthesis. To examine the changes in MT and VTG concentrations in fish exposed to an estrogen contaminant, lake trout (Salvelinus namaycush) were exposed to waterborne ethynylestradiol at 0, 4, 40 or 400 ng/l(-1) for 21 days. Blood and tissues were collected after 21 days of exposure to measure circulating levels of VTG as well as MT concentrations in liver and kidney. VTG increased in male and female fish from all three exposure groups compared to control fish. MT in liver significantly decreased in males and females compared to the controls, in the two highest exposures. MT in kidney was significantly higher in both sexes of fish exposed to the two highest concentrations of ethynylestradiol. These data are supportive of a relationship between estrogen exposure and the regulation of MT. Further studies to examine the specific links between estrogen exposure, VTG induction and regulation of essential metals like Zn are required.

  8. Dynamic hypoxic zones in Lake Erie compress fish habitat, altering vulnerability to fishing gears

    USGS Publications Warehouse

    Kraus, Richard T.; Knight, Carey T.; Farmer, Troy M.; Gorman, Ann Marie; Collingsworth, Paris D.; Warren, Glenn J.; Kocovsky, Patrick M.; Conroy, Joseph D.

    2015-01-01

    Seasonal degradation of aquatic habitats from hypoxia occurs in numerous freshwater and coastal marine systems and can result in direct mortality or displacement of fish. Yet, fishery landings from these systems are frequently unresponsive to changes in the severity and extent of hypoxia, and population-scale effects have been difficult to measure except in extreme hypoxic conditions with hypoxia-sensitive species. We investigated fine-scale temporal and spatial variability in dissolved oxygen in Lake Erie as it related to fish distribution and catch efficiencies of both active (bottom trawls) and passive (trap nets) fishing gears. Temperature and dissolved oxygen loggers placed near the edge of the hypolimnion exhibited much higher than expected variability. Hypoxic episodes of variable durations were frequently punctuated by periods of normoxia, consistent with high-frequency internal waves. High-resolution interpolations of water quality and hydroacoustic surveys suggest that fish habitat is compressed during hypoxic episodes, resulting in higher fish densities near the edges of hypoxia. At fixed locations with passive commercial fishing gear, catches with the highest values occurred when bottom waters were hypoxic for intermediate proportions of time. Proximity to hypoxia explained significant variation in bottom trawl catches, with higher catch rates near the edge of hypoxia. These results emphasize how hypoxia may elevate catch rates in various types of fishing gears, leading to a lack of association between indices of hypoxia and fishery landings. Increased catch rates of fish at the edges of hypoxia have important implications for stock assessment models that assume catchability is spatially homogeneous.

  9. Assessing inflow alterations into Lake Baikal from Selenga river basin with respect to changing climate and land use conditions

    NASA Astrophysics Data System (ADS)

    Moreido, Vsevolod; Kalugin, Andrey; Motovilov, Yuri; Millionshchikova, Tatiana

    2017-04-01

    The trans-boundary Selenga river basin is the largest tributary of Lake Baikal, which has been experiencing a profound increase of annual near-surface air temperature - 1.6 to 1.8⁰C during the last 70 years, nearly twice as global increase. A significant drought that has been registered in the Selenga basin for the last 20 years has drawn attention of a number of hydrologists worldwide to investigate its drivers. In this study we used the ECOMAG hydrological modeling software to construct a semi-distributed data-driven hydrological model that accounts for weather forcing, hydrological soil properties and land-use conditions to assess runoff generation in the river basin and its current and future response to climate and land-use alteration. Due to lack of daily weather observation data, the model was driven with EWEMBI weather dataset for calibration and validation purposes. To investigate the possible impact on runoff due to climate change in the XXI century we used an ensemble of 7 GCMs from CMIP5 experiment operating according to 4 IPCC greenhouse gas RCPs. To account for possible land-use changes we used HYDE dataset for the years 1990-2100. The modeling results show that the current drought conditions may be prolonged and intensified according to the most severe RCPs. At the same time, land-use conditions appear to have limited influence on the runoff generation for this area is not subject to heavy irrigation-intensive agriculture.

  10. The altered ecology of Lake Christina: a record of regime shifts, land-use change, and management from a temperate shallow lake.

    PubMed

    Theissen, Kevin M; Hobbs, William O; Hobbs, Joy M Ramstack; Zimmer, Kyle D; Domine, Leah M; Cotner, James B; Sugita, Shinya

    2012-09-01

    We collected two sediment cores and modern submerged aquatic plants and phytoplankton from two sub-basins of Lake Christina, a large shallow lake in west-central Minnesota, and used stable isotopic and elemental proxies from sedimentary organic matter to explore questions about the pre- and post-settlement ecology of the lake. The two morphologically distinct sub-basins vary in their sensitivities to internal and external perturbations offering different paleoecological information. The record from the shallower and much larger western sub-basin reflects its strong response to internal processes, while the smaller and deeper eastern sub-basin record primarily reflects external processes including important post-settlement land-use changes in the area. A significant increase in organic carbon accumulation (3-4 times pre-settlement rates) and long-term trends in δ(13)C, organic carbon to nitrogen ratios (C/N), and biogenic silica concentrations shows that primary production has increased and the lake has become increasingly phytoplankton-dominated in the post-settlement period. Significant shifts in δ(15)N values reflect land-clearing and agricultural practices in the region and support the idea that nutrient inputs have played an important role in triggering changes in the trophic status of the lake. Our examination of hydroclimatic data for the region over the last century suggests that natural forcings on lake ecology have diminished in their importance as human management of the lake increased in the mid-1900s. In the last 50 years, three chemical biomanipulations have temporarily shifted the lake from the turbid, algal-dominated condition into a desired clear water regime. Two of our proxies (δ(13)C and BSi) measured from the higher resolution eastern basin record responded significantly to these known regime shifts.

  11. [Impacts of Ochotona pallasi disturbance on alpine grassland community characteristics].

    PubMed

    Zhao, Guo-qin; Li, Guang-yong; Ma, Wen-hu; Zhao, Dian-zhi; Li, Xiao-yan

    2013-08-01

    Plateau pika is the main fossorial mammal in the alpine grassland in Qinghai Lake Watershed of Northwest China. Based on the field investigation data from 18 alpine grassland quadrats in the Watershed, and by using redundancy analysis (RDA) and the surface fitting offered by 'R-Vegan' , the disturbance intensity of plateau pika (Ochotona pallasi) was classified as four levels. In order to explore the impacts of plateau pika disturbance on the alpine grassland ecosystem and its grazing quality, the community characteristics under different disturbance intensities by plateau pika were analyzed, and a conceptual model about the alpine grassland community succession was proposed. The results showed that with the increase of the disturbance intensity, the dominant species changed from Juncus roemerianus to Poa pratensis and Laux maritima. When the disturbance was small, the community had high quantitative values of coverage, aboveground biomass, biodiversity, and species richness, but the proportion of weeds was also high. When the disturbance was large, the quantitative values were the lowest, while the proportion of weeds was the highest. When the disturbance was moderate, the community had relatively high quantitative values, and the proportion of grasses and sedges was the highest. It was concluded that the community' s characteristic values under low plateau pika disturbance intensity were high but the grazing quality was low, while high disturbance intensity resulted in the grassland degradation. Therefore, the disturbance intensity in the threshold could maintain the stability of alpine grassland ecosystem and improve its grazing quality.

  12. Embryonic critical windows: changes in incubation temperature alter survival, hatchling phenotype, and cost of development in lake whitefish (Coregonus clupeaformis).

    PubMed

    Mueller, Casey A; Eme, John; Manzon, Richard G; Somers, Christopher M; Boreham, Douglas R; Wilson, Joanna Y

    2015-04-01

    The timing, success and energetics of fish embryonic development are strongly influenced by temperature. However, it is unclear if there are developmental periods, or critical windows, when oxygen use, survival and hatchling phenotypic characteristics are particularly influenced by changes in the thermal environment. Therefore, we examined the effects of constant incubation temperature and thermal shifts on survival, hatchling phenotype, and cost of development in lake whitefish (Coregonus clupeaformis) embryos. We incubated whitefish embryos at control temperatures of 2, 5, or 8 °C, and shifted embryos across these three temperatures at the end of gastrulation or organogenesis. We assessed hatch timing, mass at hatch, and yolk conversion efficiency (YCE). We determined cost of development, the amount of oxygen required to build a unit of mass, for the periods from fertilization-organogenesis, organogenesis-fin flutter, fin flutter-hatch, and for total development. An increase in incubation temperature decreased time to 50 % hatch (164 days at 2 °C, 104 days at 5 °C, and 63 days at 8 °C), survival decreased from 55 % at 2 °C, to 38 % at 5 °C, and 17 % at 8 °C, and hatchling yolk-free dry mass decreased from 1.27 mg at 2 °C to 0.61 mg at 8 °C. Thermal shifts altered time to 50 % hatch and hatchling yolk-free dry mass and revealed a critical window during gastrulation in which a temperature change reduced survival. YCE decreased and cost of development increased with increased incubation temperature, but embryos that hatched at 8 °C and were incubated at colder temperatures during fertilization-organogenesis had reduced cost. The relationship between cost of development and temperature was altered during fin flutter-hatch, indicating it may be a critical window during which temperature has the greatest impact on energetic processes. The increase in cost of development with an increase in temperature has not been documented in other fishes and suggests

  13. Altered Sex Hormone Concentrations and Gonadal mRNA Expression Levels of Activin Signaling Factors in Hatchling Alligators From a Contaminated Florida Lake

    PubMed Central

    MOORE, BRANDON C.; KOHNO, SATOMI; COOK, ROBERT W.; ALVERS, ASHLEY L.; HAMLIN, HEATHER J.; WOODRUFF, TERESA K.; GUILLETTE, LOUIS J.

    2014-01-01

    Activins and estrogens participate in regulating the breakdown of ovarian germ cell nests and follicle assembly in mammals. In 1994, our group reported elevated frequencies of abnormal, multioocytic ovarian follicles in 6 month old, environmental contaminant-exposed female alligators after gonadotropin challenge. Here, we investigated if maternal contribution of endocrine disrupting contaminants to the egg subsequently alters estrogen/inhibin/activin signaling in hatchling female offspring, putatively predisposing an increased frequency of multioocytic follicle formation. We quantified basal and exogenous gonadotropin-stimulated concentrations of circulating plasma steroid hormones and ovarian activin signaling factor mRNA abundance in hatchling alligators from the same contaminated (Lake Apopka) and reference (Lake Woodruff) Florida lakes, as examined in 1994. Basal circulating plasma estradiol and testosterone concentrations were greater in alligators from the contaminated environment, whereas activin/inhibin βA subunit and follistatin mRNA abundances were lower than values measured in ovaries from reference lake animals. Challenged, contaminant-exposed animals showed a more robust increase in plasma estradiol concentration following an acute follicle stimulating hormone (FSH) challenge compared with reference site alligators. Aromatase and follistatin mRNA levels increased in response to an extended FSH challenge in the reference site animals, but not in the contaminant-exposed animals. In hatchling alligators, ovarian follicles have not yet formed; therefore, these endocrine differences are likely to affect subsequent ovarian development, including ovarian follicle assembly. PMID:20166196

  14. Altered sex hormone concentrations and gonadal mRNA expression levels of activin signaling factors in hatchling alligators from a contaminated Florida lake.

    PubMed

    Moore, Brandon C; Kohno, Satomi; Cook, Robert W; Alvers, Ashley L; Hamlin, Heather J; Woodruff, Teresa K; Guillette, Louis J

    2010-04-01

    Activins and estrogens participate in regulating the breakdown of ovarian germ cell nests and follicle assembly in mammals. In 1994, our group reported elevated frequencies of abnormal, multioocytic ovarian follicles in 6 month old, environmental contaminant-exposed female alligators after gonadotropin challenge. Here, we investigated if maternal contribution of endocrine disrupting contaminants to the egg subsequently alters estrogen/inhibin/activin signaling in hatchling female offspring, putatively predisposing an increased frequency of multioocytic follicle formation. We quantified basal and exogenous gonadotropin-stimulated concentrations of circulating plasma steroid hormones and ovarian activin signaling factor mRNA abundance in hatchling alligators from the same contaminated (Lake Apopka) and reference (Lake Woodruff) Florida lakes, as examined in 1994. Basal circulating plasma estradiol and testosterone concentrations were greater in alligators from the contaminated environment, whereas activin/inhibin betaA subunit and follistatin mRNA abundances were lower than values measured in ovaries from reference lake animals. Challenged, contaminant-exposed animals showed a more robust increase in plasma estradiol concentration following an acute follicle stimulating hormone (FSH) challenge compared with reference site alligators. Aromatase and follistatin mRNA levels increased in response to an extended FSH challenge in the reference site animals, but not in the contaminant-exposed animals. In hatchling alligators, ovarian follicles have not yet formed; therefore, these endocrine differences are likely to affect subsequent ovarian development, including ovarian follicle assembly. 2010 Wiley-Liss, Inc.

  15. Neutralization of atmospheric acidity by chemical weathering in an alpine drainage basin in the North Cascade mountains

    SciTech Connect

    Drever, J.I.; Hurcomb, D.R.

    1986-03-01

    The most important weathering reaction that neutralizes incoming atmospheric acidity in the South Cascade Lake basin is weathering of calcite, which occurs in trace amounts in veins, on joint surfaces, and as a subglacial surficial deposit. Although the basin is underlain by igneous and high-grade metamorphic rocks, weathering of plagioclase is quantitatively negligible; the principal silicate weathering reaction is alteration of biotite to vermiculite. These conclusions are based on mass-balance calculations involving runoff compositions and on mineralogical observations. For predictive modeling of the effects of increased acid deposition, it is essential to identify the relevant weathering reactions. Feldspar weathering is commonly not an important source of solutes in alpine basins underlain by granitic rocks. 30 references, 2 figures, 1 table.

  16. Ecosystem Alterations and Species Range Shifts: An Atlantic-Mediterranean Cephalaspidean Gastropod in an Inland Egyptian Lake

    PubMed Central

    Malaquias, Manuel António E.

    2016-01-01

    The eastern Atlantic and Mediterranean marine Cephalaspidea gastropod Haminoea orbignyana was collected from Lake Qarun (Fayoum, Egypt), a landlocked lake that has undergone a shift from freshwater to estuarine conditions in the past 100 years. Species identity was confirmed by both morphological (anatomical dissection and scanning electron microscopy) and molecular methods (COI gene phylogeny). Observations suggested a robust population of H. orbignyana in the lake with a density of ca. 64 individuals/m2 and ca. 105 egg masses/m2 during surveys conducted in the summer of 2013. The vast majority of snails and egg masses were found under rocks. Observations of egg masses in the lab showed a gradual change from whitish to yellow-green as the eggs matured and the release of veliger larvae alone after about a week. Although adult cephalaspideans readily consumed filamentous red and green algae, and cyanobacteria, laboratory trials showed that they consumed significantly more of the red alga Ceramium sp., than of the green alga Cladophora glomerata, with consumption of Oscillatoria margaritifera being similar to those on the two algae. When grown on these resources for 16 days, H. orbignyana maintained their mass on the rhodophyte and cyanobacterium, but not in starvation controls. No cephalaspideans grew over the course of this experiment. Lake Qarun has been periodically restocked with Mediterranean fishes and prawns since the 1920s to maintain local fisheries, which represents a possible route of colonization for H. orbignyana. Yet, based on literature records, it seems more likely that invasion of the lake by this gastropod species has occurred only within the last 20 years. As human activities redistribute species through direct and indirect means, the structure of the community of this inland lake has become unpredictable and the long-term effects of these recent introductions are unknown. PMID:27248835

  17. Heat-Wave Effects on Oxygen, Nutrients, and Phytoplankton Can Alter Global Warming Potential of Gases Emitted from a Small Shallow Lake.

    PubMed

    Bartosiewicz, Maciej; Laurion, Isabelle; Clayer, François; Maranger, Roxane

    2016-06-21

    Increasing air temperatures may result in stronger lake stratification, potentially altering nutrient and biogenic gas cycling. We assessed the impact of climate forcing by comparing the influence of stratification on oxygen, nutrients, and global-warming potential (GWP) of greenhouse gases (the sum of CH4, CO2, and N2O in CO2 equivalents) emitted from a shallow productive lake during an average versus a heat-wave year. Strong stratification during the heat wave was accompanied by an algal bloom and chemically enhanced carbon uptake. Solar energy trapped at the surface created a colder, isolated hypolimnion, resulting in lower ebullition and overall lower GWP during the hotter-than-average year. Furthermore, the dominant CH4 emission pathway shifted from ebullition to diffusion, with CH4 being produced at surprisingly high rates from sediments (1.2-4.1 mmol m(-2) d(-1)). Accumulated gases trapped in the hypolimnion during the heat wave resulted in a peak efflux to the atmosphere during fall overturn when 70% of total emissions were released, with littoral zones acting as a hot spot. The impact of climate warming on the GWP of shallow lakes is a more complex interplay of phytoplankton dynamics, emission pathways, thermal structure, and chemical conditions, as well as seasonal and spatial variability, than previously reported.

  18. Lake surface area variation and its responses to climatic change in Yamzhog Yumco Basin, South Tibet during 1970-2010

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Tian, Y.; Sun, R.

    2015-12-01

    The research on lake extraction from multi-source and multi-temporal satellite images and the lake size variation can provide reliable method and indispensable information to deepen the understanding about alpine lake changes with the accelerating warming. With field survey experience in the Yamzhog Yumco Basin, South Tibet, the outlines of five lakes (i.e., Yamzhog Yumco, Chen Co, Kongmu Co, Bajiu Co and Puma Yumco) were delineated by the adoption of 42 scenes of satellite images from Landsat, CBERS and HJ from 1970 to 2010, basing on which the responses of alpine lakes to climate change at different timescales were explored. The results are summarized as follows. (1) The seasonal fluctuation of lake surface area was similar with different trend for the five alpine lakes. As for the last 41 years, the annual variation of lake surface area exhibited two kinds of patterns for the five alpine lakes. And the Yamzhog Yumco declined by 9.41%, while the rest four lakes expanded. (2) The responses of alpine lakes to climate change rely on different timescale and water replenishment types. On the one hand, the precipitation change was the predominant driving forces for the seasonal fluctuation and variation trend of lake size, and the rising temperature accounted for the inter-annual lake surface variation. On the other hand, the two kinds of alpine lakes behaviors were well correspondent with the warming temperature over the Qinghai-Tibetan Plateau. The lakes supplied mainly by precipitation shrunk as a result of increased evaporation, and lakes supplied mainly by glacier and snow meltwater, however, expanded because of the remarkable glacier recession. (3) The quantification of hydrological components would hopefully be improved, according to uncertainties analysis, with the adoption of microwave satellite images and higher resolution ones to disclose the interaction mechanism among climate, glacier, and lake in alpine regions.

  19. Comparison of seasonal changes in fluorescent dissolved organic matter among aquatic lake and stream sites in the Green Lakes Valley

    NASA Astrophysics Data System (ADS)

    Miller, Matthew P.; McKnight, Diane M.

    2010-03-01

    The spectral characteristics of whole water dissolved organic matter (DOM) and fulvic acid were studied in samples collected from an alpine lake, a subalpine lake, and a subalpine stream during snowmelt and the summer growing season. Excitation-emission matrices of whole water DOM and fulvic acid were analyzed by parallel factor analysis (PARAFAC). Allochthonous inputs of terrestrially derived fulvic acid DOM were dominant during snowmelt at the alpine lake, and during both snowmelt and summer at the subalpine sites. At the alpine lake, autochthonous inputs of DOM dominated during the summer phytoplankton bloom, and the spectral characteristics of the whole water DOM diverged from those of the fulvic acid. For example, the quinone-like fluorophores in whole water DOM at the alpine lake were more oxidized and microbially derived than the fulvic acid fraction during the summer. At the subalpine sites, the seasonal changes in the source and redox state of the quinone-like fluorophores of the whole water DOM tracked those of the fulvic acid pool. However, at both lake sites there was a greater contribution of amino acid-like fluorophores in the whole water DOM than the fulvic acid fraction. This trend was not observed at the subalpine stream site. Principal components analysis (PCA) of the PARAFAC components suggests that during snowmelt, the chemical quality of the DOM at the alpine lake was similar to that of the subalpine stream; whereas the alpine site was more similar to the subalpine lake during the summer. Spectral characterization and PCA of the PARAFAC components suggest that nonhumic quinone-like and amino acid-like fluorophores were produced in the alpine lake during the summer phytoplankton bloom. Our results show that different types of water bodies produce different seasonal patterns in whole water DOM and fulvic acid quantity and quality.

  20. Allostratigraphic approach on the Alpine Lateglacial

    NASA Astrophysics Data System (ADS)

    Monegato, Giovanni; Reitner, Jürgen M.

    2017-04-01

    sequence-based glacial stratigraphy: a case study of a Younger Dryas system in the Eastern Alps. Boreas, 45: 537-551. Colucci, R. R., Monegato, G., Žebre, M. (2014). Glacial and proglacial deposits of the Resia Valley (NE Italy): New insights on the onset and decay of the last alpine glacial maximum in the Julian Alps. Alpine and Mediterranean Quaternary, 27: 85-104. Ravazzi, C., Pini, R., Badino, F., De Amicis, M., Londeix, L., Reimer, P.J. (2014). The latest LGM culmination of the Garda Glacier (Italian Alps) and the onset of glacial termination. Age of glacial collapse and vegetation chronosequence. Quaternary Science Reviews, 105: 26-47. Reitner, J.M., Ivy-Ochs, S., Drescher-Schneider, R., Hajdas, I., Linner, M. (2016). Reconsidering the current stratigraphy of the Alpine Lateglacial: Implications of the sedimentary and morphological record of the Lienz area (Tyrol/Austria). E&G Quaternary Science Journal, 65: 113-144. Schmidt, R., Weckström, K., Lauterbach, S., Tessadri, R., Huber, K. (2012). North Atlantic climate impact on early late-glacial climate oscillations in the south-eastern Alps inferred from a multi-proxy lake sediment record. Journal of Quaternary Science, 27: 40-50.

  1. Food Web Topology in High Mountain Lakes.

    PubMed

    Sánchez-Hernández, Javier; Cobo, Fernando; Amundsen, Per-Arne

    2015-01-01

    Although diversity and limnology of alpine lake systems are well studied, their food web structure and properties have rarely been addressed. Here, the topological food webs of three high mountain lakes in Central Spain were examined. We first addressed the pelagic networks of the lakes, and then we explored how food web topology changed when benthic biota was included to establish complete trophic networks. We conducted a literature search to compare our alpine lacustrine food webs and their structural metrics with those of 18 published lentic webs using a meta-analytic approach. The comparison revealed that the food webs in alpine lakes are relatively simple, in terms of structural network properties (linkage density and connectance), in comparison with lowland lakes, but no great differences were found among pelagic networks. The studied high mountain food webs were dominated by a high proportion of omnivores and species at intermediate trophic levels. Omnivores can exploit resources at multiple trophic levels, and this characteristic might reduce competition among interacting species. Accordingly, the trophic overlap, measured as trophic similarity, was very low in all three systems. Thus, these alpine networks are characterized by many omnivorous consumers with numerous prey species and few consumers with a single or few prey and with low competitive interactions among species. The present study emphasizes the ecological significance of omnivores in high mountain lakes as promoters of network stability and as central players in energy flow pathways via food partitioning and enabling energy mobility among trophic levels.

  2. Food Web Topology in High Mountain Lakes

    PubMed Central

    Sánchez-Hernández, Javier; Cobo, Fernando; Amundsen, Per-Arne

    2015-01-01

    Although diversity and limnology of alpine lake systems are well studied, their food web structure and properties have rarely been addressed. Here, the topological food webs of three high mountain lakes in Central Spain were examined. We first addressed the pelagic networks of the lakes, and then we explored how food web topology changed when benthic biota was included to establish complete trophic networks. We conducted a literature search to compare our alpine lacustrine food webs and their structural metrics with those of 18 published lentic webs using a meta-analytic approach. The comparison revealed that the food webs in alpine lakes are relatively simple, in terms of structural network properties (linkage density and connectance), in comparison with lowland lakes, but no great differences were found among pelagic networks. The studied high mountain food webs were dominated by a high proportion of omnivores and species at intermediate trophic levels. Omnivores can exploit resources at multiple trophic levels, and this characteristic might reduce competition among interacting species. Accordingly, the trophic overlap, measured as trophic similarity, was very low in all three systems. Thus, these alpine networks are characterized by many omnivorous consumers with numerous prey species and few consumers with a single or few prey and with low competitive interactions among species. The present study emphasizes the ecological significance of omnivores in high mountain lakes as promoters of network stability and as central players in energy flow pathways via food partitioning and enabling energy mobility among trophic levels. PMID:26571235

  3. Endocrine disruption and altered gonadal development in white perch (Morone americana) from the lower Great Lakes region.

    PubMed Central

    Kavanagh, Richard J; Balch, Gordon C; Kiparissis, Yiannis; Niimi, Arthur J; Sherry, Jim; Tinson, Cheryl; Metcalfe, Chris D

    2004-01-01

    High prevalences of gonadal intersex have been observed in wild fish populations in areas affected by domestic and industrial effluents. For this study, fish were collected in 1998 from the Cootes Paradise region of Hamilton Harbour in western Lake Ontario, Canada, to determine whether gonadal abnormalities, including intersex, were present in young of the year (YOY) fish. No gonadal abnormalities were observed in goldfish (Carassius auratus), common carp (Cyprinus carpio), gizzard shad (Dorosoma cepedianum), brown bullhead (Ictalurus ameiurus), pumpkinseed (Lepomis gibbosus), and bluegill (Lepomis macrochirus). However, intersex gonads were observed in 8 of 16 male white perch (Morone americana) examined in this survey. Subsequently, in 1999 and 2000 white perch estimated to be YOY to approximately 2 years of age were collected from Cootes Paradise and from two other sites in the lower Great Lakes region. Gonadal intersex was observed in male white perch collected from the Bay of Quinte (22-44%) and Lake St. Clair (45%), although the prevalence and the extent of the intersex condition were lower relative to the 83% prevalence in white perch collected in Cootes Paradise. Intersex was not observed in hatchery-reared white perch or in white perch collected from an uncontaminated reference site (i.e., Deal Lake) in the United States. An analysis of plasma collected in the spring of 2002 from male adult white perch in Cootes Paradise revealed high concentrations of vitellogenin, ranging from 49 to 1,711 microg/mL. These observations indicate that male white perch are exposed to estrogenic endocrine-disrupting substances that may be responsible for the induction of gonadal intersex. PMID:15175179

  4. Enrichment of Non-Terrestrial L-Proteinogenic Amino Acids by Aqueous Alteration on the Tagish Lake Meteorite Parent Body

    NASA Technical Reports Server (NTRS)

    Glavin, Daniel P.; Elsila, Jamie E.; Burton, Aaron S.; Callahan, Michael P.; Dworkin, Jason P.; Herd, Christopher D. K.

    2012-01-01

    The distribution and isotopic and enantiomeric compositions of amino acids found in three distinct fragments of the Tagish Lake C2-type carbonaceous chondrite were investigated via liquid chromatography fluorescence detection time-of-flight mass spectrometry and gas chromatography isotope ratio mass spectrometry. Large L-enantiomeric excesses (L(sub ee) approx. 43 to 59%) of the a-hydrogen aspartic and glutamic amino acids were measured in Tagish Lake, whereas alanine, another alpha-hydrogen protein amino acid, was found to be nearly racemic (D approx. L) using both techniques. Carbon isotope measurements of D- and L-aspartic acid and D- and L-alanine in Tagish Lake fall well outside of the terrestrial range and indicate that the measured aspartic acid enantioenrichment is indigenous to the meteorite. Alternate explanations for the Lexcesses of aspartic acid such as interference from other compounds present in the sample, analytical biases, or terrestrial amino acid contamination were investigated and rejected. These results can be explained by differences in the solid-solution phase behavior of aspartic acid, which can form conglomerate enantiopure solids during crystallization, and alanine, which can only form racemic crystals.

  5. Climate change and alpine stream biology: progress, challenges, and opportunities for the future.

    PubMed

    Hotaling, Scott; Finn, Debra S; Joseph Giersch, J; Weisrock, David W; Jacobsen, Dean

    2017-01-20

    In alpine regions worldwide, climate change is dramatically altering ecosystems and affecting biodiversity in many ways. For streams, receding alpine glaciers and snowfields, paired with altered precipitation regimes, are driving shifts in hydrology, species distributions, basal resources, and threatening the very existence of some habitats and biota. Alpine streams harbour substantial species and genetic diversity due to significant habitat insularity and environmental heterogeneity. Climate change is expected to affect alpine stream biodiversity across many levels of biological resolution from micro- to macroscopic organisms and genes to communities. Herein, we describe the current state of alpine stream biology from an organism-focused perspective. We begin by reviewing seven standard and emerging approaches that combine to form the current state of the discipline. We follow with a call for increased synthesis across existing approaches to improve understanding of how these imperiled ecosystems are responding to rapid environmental change. We then take a forward-looking viewpoint on how alpine stream biologists can make better use of existing data sets through temporal comparisons, integrate remote sensing and geographic information system (GIS) technologies, and apply genomic tools to refine knowledge of underlying evolutionary processes. We conclude with comments about the future of biodiversity conservation in alpine streams to confront the daunting challenge of mitigating the effects of rapid environmental change in these sentinel ecosystems.

  6. Understanding and Predicting the Fate of Semivolatile Organic Pesticides in a Glacier-Fed Lake Using a Multimedia Chemical Fate Model.

    PubMed

    Wu, Xiaolin; Davie-Martin, Cleo L; Steinlin, Christine; Hageman, Kimberly J; Cullen, Nicolas J; Bogdal, Christian

    2017-10-06

    Melting glaciers release previously ice-entrapped chemicals to the surrounding environment. As glacier melting accelerates under future climate warming, chemical release may also increase. This study investigated the behavior of semivolatile pesticides over the course of one year and predicted their behavior under two future climate change scenarios. Pesticides were quantified in air, lake water, glacial meltwater, and streamwater in the catchment of Lake Brewster, an alpine glacier-fed lake located in the Southern Alps of New Zealand. Two historic-use pesticides (endosulfan I and hexachlorobenzene) and three current-use pesticides (dacthal, triallate, and chlorpyrifos) were frequently found in both air and water samples from the catchment. Regression analysis indicated that the pesticide concentrations in glacial meltwater and lake water were strongly correlated. A multimedia environmental fate model was developed for these five chemicals in Brewster Lake. Modeling results indicated that seasonal lake ice cover melt, and varying contributions of input from glacial melt and streamwater, created pulses in pesticide concentrations in lake water. Under future climate scenarios, the concentration pulse was altered and glacial melt made a greater contribution (as mass flux) to pesticide input in the lake water.

  7. Field Trip Guide to Serpentinite, Silica-Carbonate Alteration, and Related Hydrothermal Activity in the Clear Lake Region, California

    SciTech Connect

    Fraser Goff; George Guthrie

    1999-06-01

    This guide is designed to familiarize scientists with the geology, structure, alteration, and fluids typical of California serpentinites for purposes of carbon dioxide sequestration (Lackner et al., 1995). Goff et al. (1997) and Goff and Lackner (1998) describe the geology and geochemistry of some of the serpentinites from this area. Mechanisms of silica-carbonate alteration were outlined by Barnes et al. (1973). Donnelly-Nolan et al. (1993) most recently reviewed relations between regional hydrothermal alteration and Quarternary volcanic activity. Stanley et al. (1998) summarized geophysical characteristics of the region.

  8. Hydrothermal alteration of organic matter in uranium ores, Elliot Lake, Canada: Implications for selected organic-rich deposits

    SciTech Connect

    Mossman, D.J.; Nagy, B.; Davis, D.W.

    1993-07-01

    Organic matter in the uraniferous Matinenda Formation, Elliot Lake, is preserved in the forms of syngenetic kerogen and solid bitumen as it is in many of the Oklo uranium deposits and in the Witwatersrand gold-uranium ores. The Elliot Lake kerogen is a vitrinite-like material considered to be remnants of the Precambrian cyanobacterial mats. The kerogen at Elliot Lake has reflectances (in oil) ranging from 2.63-7.31% RO{sub max}, high aromaticity, relatively low (0.41-0.60) atomic H/C ratios, and it contains cryptocrystalline graphite. Bitumen, present primarily as dispersed globules (up to 0.5 mm dia.), has reflectances from 0.72-1.32% RO{sub max}, atomic H/C ratios of 0.71-0.81, and is somewhat less aromatic than the kerogen. Overall similarity in molecular compositions indicates that liquid bitumen was derived from kerogen by processes similar to hydrous pyrolysis. The carbon isotopic composition of kerogen ({minus}15.62 to {minus}24.72%), and the now solid bitumen ({minus}25.91 to {minus}33.00%) are compatible with these processes. Despite having been subjected to several thermal episodes, ca. 2.45 Ga old kerogen of microbiological origin here survived as testimony of the antiquity of life on Earth. U-Pb isotopic data from discrete kerogen grains at Elliot Lake form a scattered array intersecting concordia at 2130 {+-} 100 Ma, correspond to the Nipissing event. U-Pb systems were totally reset by this event. Uranium and lead show subsequently partial mobility, the average of which is indicated by the lower concordia intersect of 550 {+-} 260 Ma. The migrated bitumen contains virtually no uranium and thorium but has a large excess of {sup 206}Pb, which indicates that the once liquid bitumen must have acted as a sink for mobile intermediate decay products of {sup 238}U. Emplacement of the Nipissing diabase may have been responsible for producing the bitumen and, indirectly, for its enrichment in {sup 206}Pb as a result of outgassing of {sup 222}Rn.

  9. The Cariboo Alpine Mesonet

    NASA Astrophysics Data System (ADS)

    MacLeod, S.; Déry, S.

    2006-12-01

    It is projected that climate change will have an amplified impact on the hydroclimate of mountainous areas such as northern British Columbia (BC), Canada. In response to rising air temperatures, permafrost will thaw, glaciers will recede, the seasonal snowpack will thin, and precipitation is likely to increase due to the enhanced water holding capacity of warmer air. Unfortunately, there exist few longterm climatic records at high altitude sites in the North American Cordillera. This poster will describe the recent deployment of the "Cariboo Alpine Mesonet" (CAM) that will partly fill this gap by generating a longterm climatic record for the Quesnel River drainage basin in the Cariboo Mountains of BC. CAM is a network four of meteorological stations installed at high elevation sites within the Quesnel watershed. Stations at Spanish Mountain (el. 1509 m), Blackbear Mountain (el. 1590 m), Browntop Mountain (el. 2030 m), and at the University of Northern British Columbia's Quesnel River Research Centre (el. 743 m) all measure wind speed and direction, precipitation, air temperature, relative humidity, atmospheric pressure, soil temperature, and snow depth. Preliminary results focusing on the effects of elevation on various meteorological quantities will be presented. Future opportunities for the expansion of CAM will also be discussed.

  10. Alpine skiing injuries.

    PubMed Central

    Sahlin, Y

    1989-01-01

    Alpine skiing accidents admitted to the Trondheim Regional and University Hospital during one year were recorded. Of the 339 injured, 67 per cent were male and 33 per cent were female. Eighty-seven per cent were outpatients, and 13 per cent were hospitalized. Falling accidents (67 per cent), followed by collision accidents (17 per cent), were the most common cause of injury. The injuries in the lower extremities were caused by falling and the head injuries were mostly caused by collisions. Knee ligament strains were the most common injuries, and 17 per cent of these were hospitalized and required operative treatment. Of the minor knee strains, all 44 per cent were not fully recovered after two and a half years. Seventeen patients sustained tibial fractures, eleven of them spiral fractures and six transverse fractures. The patients with spiral fractures were younger than the patients with transverse fractures. Head injuries were the most severe injuries, with eleven concussions and two epidural haematomas. PMID:2630001

  11. Large rock-slope failures impacting on lakes - Reconstruction of events and deciphering mobility processes at Lake Oeschinen (CH) and Lake Eibsee (D)

    NASA Astrophysics Data System (ADS)

    Knapp, Sibylle; Anselmetti, Flavio; Gilli, Adrian; Krautblatter, Michael; Hajdas, Irka

    2017-04-01

    Among single event landslide disasters large rock-slope failures account for 75% of disasters with more than 1000 casualties. The precise determination of recurrence rates and failure volumes combined with an improved understanding of mobility processes are essential to better constrain runout models and establish early warning systems. Here we present the data sets from the two alpine regions Lake Oeschinen (CH) and Lake Eibsee (D) to show how lake studies can help to decipher the multistage character of rock-slope failures and to improve the understanding of the processes related to rock avalanche runout dynamics. We focus on such that impacted on a (paleo-) lake for two main reasons. First, the lake background sedimentation acts as a natural chronometer, which enables the stratigraphic positioning of events and helps to reconstruct the event history. This way it becomes possible to (i) decipher the multistage character of the failure of a certain rock slope and maybe detect progressive failure, (ii) determine the recurrence rates of failures at that certain rock slope, and (iii) consider energies based on estimated failure volumes, fall heights and deposition patterns. Hence, the interactions between a rock-slope failure, the water reservoir and the altered rock-slope are better understood. Second, picturing a rock avalanche running through and beyond a lake, we assume the entrainment of water and slurry to be crucial for the subsequent flow dynamics. The entrainment consumes a large share of the total energy, and orchestrates the mobility leading to fluidization, a much higher flow velocity and a longer runout-path length than expected. At Lake Oeschinen (CH) we used lake sediment cores and reflection seismic profiles in order to reconstruct the 2.5 kyrs spanning rock-slope failure history including 10 events, six of which detached from the same mountain flank, and correlated them with (pre-) historical data. The Lake Eibsee records provide insights into the

  12. Advanced seismic imaging of overdeepened alpine valleys

    NASA Astrophysics Data System (ADS)

    Burschil, Thomas; Buness, Hermann; Tanner, David; Gabriel, Gerald; Krawczyk, Charlotte M.

    2017-04-01

    Major European alpine valleys and basins are densely populated areas with infrastructure of international importance. To protect the environment by, e.g., geohazard assessment or groundwater estimation, understanding of the geological structure of these valleys is essential. The shape and deposits of a valley can clarify its genesis and allows a prediction of behaviour in future glaciations. The term "overdeepened" refers to valleys and basins, in which pressurized melt-water under the glacier erodes the valley below the fluvial level. Most overdeepened valleys or basins were thus refilled during the ice melt or remain in the form of lakes. The ICDP-project Drilling Overdeepened Alpine Valleys (DOVE) intends to correlate the sedimentary succession from boreholes between valleys in the entire alpine range. Hereby, seismic exploration is essential to predict the most promising well path and drilling site. In a first step, this DFG-funded project investigates the benefit of multi-component techniques for seismic imaging. At two test sites, the Tannwald Basin and the Lienz Basin, the Leibniz Institute for Applied Geophysics acquired P-wave reflection profiles to gain structural and facies information. Built on the P-wave information, several S-wave reflection profiles were acquired in the pure SH-wave domain as well as 6-C reflection profiles using a horizontal S-wave source in inline and crossline excitation and 3-C receivers. Five P-wave sections reveal the structure of the Tannwald Basin, which is a distal branch basin of the Rhine Glacier. Strong reflections mark the base of the basin, which has a maximum depth of 240 metres. Internal structures and facies vary strongly and spatially, but allow a seismic facies characterization. We distinguish lacustrine, glacio-fluvial, and deltaic deposits, which make up the fill of the Tannwald Basin. Elements of the SH-wave and 6-C seismic imaging correlate with major structures in the P-wave image, but vary in detail. Based on

  13. Detention Basins may Help Reduce Nutrient Loads to Lake Tahoe

    NASA Astrophysics Data System (ADS)

    Green, J. M.

    2005-12-01

    Water clarity in Lake Tahoe has been declining at a rate of about one foot per year for more than 35 years. In an attempt to decrease sediment and associated nutrients from reaching the lake, many detention basins have been installed, although their efficiency was uncertain. Many basins were constructed near alpine streams. This setting effectively reduces sediments from reaching surface water, but may allow transport of nutrients by ground water beneath the detention basins possibly discharging to streams farther downgradient or directly to Lake Tahoe. Determining the effectiveness of detention basins in the Lake Tahoe area requires an understanding of the shallow subsurface environment in which nutrients travel. A study was carried out at Cattlemans detention basin, situated adjacent to Cold Creek, a tributary to Lake Tahoe. Ground-water and solute transport models were used to evaluate complex ground-water interactions with Cold Creek near Cattlemans detention basin. Based on observations that urban runoff entering the basin rarely exited as surface water, each model assumes all water entering the basin either infiltrates or is consumed by evapotranspiration. Modeling results indicated that the detention basin has altered the local ground-water flow system while efficiently reducing suspended sediments, although nutrients are not filtered out as readily. Nutrient discharge points were tracked by calculating ground-water flow paths and endpoints. Approximately 45 percent of ground water originating from the detention basin discharges to Cold Creek within the modeled area downstream of the detention basin. The remaining 55 percent of ground water could discharge to evapotranspiration, to Cold Creek farther downstream, or to Lake Tahoe.

  14. Air-Pollution-Mediated Changes in Alpine Ecosystems and Ecotones.

    PubMed

    Rusek, Josef

    1993-08-01

    Soil biological parameters (e.g., Collembola), soil types, soil chemical parameters (pH, humus substances), and plant communities were studied in different ecosystems and ecotones in alpine, subalpine, and spruce forest zones in the Tatra National Park, Slovak Republic. The preliminary, selected data, based on a long-term research program, showed a high sensitivity of some alpine ecotones and ecosystems to long-distance transported acid deposits. The changes in different ecosystem parameters since 1977 were more extensive in alpine grasslands on limestone than on granite. The greatest soil pH decrease was in the plant communities Festucetum versicoloris (-1.5 pH), Geranio-Alchemilletum crinitae (-1.32 pH), and Saxifragetum perdurantis (-1.25 pH), which are restricted to places with snow accumulation and water runoff gullies. In these ecosystems the greatest changes occurred in the leaching of humus substances. Some formerly less abundant and rare soil animals restricted to acid bedrock became dominant in some ecosystems on limestone as well as on granite; other formerly dominant species disappeared from the entire study area (e.g., Folsomia alpina). The aerial extent of some ecosystems changed substantially since 1977, and their surrounding ecotones moved into the space formerly occupied by one of the adjacent ecosystems. These changes are detectable by remote-sensing methods. In Central European mountains, strongly affected by global and regional industrial air pollution (e.g., Krusne Hory, Krkonose, Beskydy), spruce forests started to die back from higher to lower mountain elevations. The effects of air pollution on alpine and subalpine vegetation were not studied there. Strong alterations in alpine ecosystems and ecotones were detected by the author during long-term studies in the High Tatra Mountains, and I suggest that subalpine and mountain forest belts will be affected here in the near future as they were in the more polluted Central European mountains. The

  15. Hydrological significance of soil frost for pre-alpine areas

    NASA Astrophysics Data System (ADS)

    Stähli, Manfred

    2017-03-01

    Soil frost can have a substantial impact on water flows at the soil surface and-potentially-alter the dynamics of catchment runoff. While these findings are mainly based on studies from alpine and Northern-latitude areas (including permafrost areas), little is known about the significance of soil frost for hydrology in pre-alpine areas, i.e. the region at the transition from central European lowlands to high-alpine areas. Here I synthesize soil temperature data and soil frost observations from ten sites in Switzerland to assess the occurrence of soil frost and to determine its impact on catchment runoff. In addition, a well-established numerical model was used to reconstruct the presence of soil frost in two first-order catchments for single runoff events and winters. The data clearly demonstrates that shallow soil frost has formed regularly in this altitudinal range over the past decade. The presence of a frozen soil surface was found to be highly variable among the sites under study and did not significantly correlate with altitude or forest density. For the first-order catchments, it was not possible to relate important flood peaks or increased runoff coefficients to winter situations with substantial soil frost. Thus, the present analysis suggests that although soil frost is widespread and regularly occurring at this altitudinal range, it has no significant impact on winter runoff in pre-alpine watersheds.

  16. Application of near surface geophysical methods to image water table response in an Alpine Meadow, Northern California.

    NASA Astrophysics Data System (ADS)

    Ayers, M.; Blacic, T. M.; Craig, M. S.; Yarnell, S. M.

    2015-12-01

    Meadows are recognized for their value to the ecological, hydrologic, and aesthetic functions of a watershed. As natural water retention sinks, meadows attenuate floods, improve water quality and support herbaceous vegetation that stabilize streambanks and promote high biodiversity. Alpine meadows are especially vital, serving as freshwater sources and distributing to lower lying provinces through ground and surface water interaction. These complexes are highly vulnerable to drought conditions, altered seasonal precipitation patterns, and mismanaged land use. One such location, Van Norden meadow located in the Donner Summit area west of Lake Tahoe, is one of the largest sub-alpine meadows in the Sierra Nevada mountain range of Northern California. Van Norden meadow offers a natural hydrologic laboratory. Ownership transfer of the area from a local land trust to the Forestry Service requires restoration toward natural meadow conditions, and involves notching the dam in 2016 to reduce currently impounded water volumes from 250 to less than 50 acre-feet. To monitor the effects of notching the dam on the upstream meadow conditions, better understanding of the surface and groundwater hydrology both pre-and post-base level alteration is required. Comprehensive understanding of groundwater flux that supports meadow reaches relies on knowledge of their often complex stratigraphic and structural subsurface framework. In recent years hydrogeophysics has emphasized the combination of near surface geophysical techniques, collaborated with well and borehole measures, to qualitatively define these parameters. Building on a preliminary GPR investigation conducted in 2014, in which 44 270 MHz transect lines were collected, we returned to Van Norden meadow in late summer 2015 to collect lower frequency GPR (50 and 100 MHz) and electrical resistivity profiles to better define the groundwater table, sedimentary, and structural features of the meadow.

  17. Chernobyl fallout on Alpine glaciers

    SciTech Connect

    Ambach, W.; Rehwald, W.; Blumthaler, M.; Eisner, H.; Brunner, P.

    1989-01-01

    Measurements of the gross beta activity of snow samples from four Alpine glaciers contaminated by radioactive fallout from the Chernobyl nuclear accident and a gamma-spectrum analysis of selected samples are reported. The results are discussed with respect to possible risks to the population from using meltwater from these glaciers as drinking water.

  18. Alpine Skiing in the Classroom

    ERIC Educational Resources Information Center

    Mendez-Gimenez, Antonio; Fernandez-Rio, Javier

    2012-01-01

    Many students settle indoors in the winter. However, this does not mean that winter should be a period of time with no physical activity. Several snow activities could be practiced during those months, such as ice-skating, ice-hockey, snowshoeing, cross-country skiing, alpine skiing, or snowboarding. In order to counteract the tendency for…

  19. Alpine Skiing in the Classroom

    ERIC Educational Resources Information Center

    Mendez-Gimenez, Antonio; Fernandez-Rio, Javier

    2012-01-01

    Many students settle indoors in the winter. However, this does not mean that winter should be a period of time with no physical activity. Several snow activities could be practiced during those months, such as ice-skating, ice-hockey, snowshoeing, cross-country skiing, alpine skiing, or snowboarding. In order to counteract the tendency for…

  20. Chernobyl fallout on Alpine glaciers.

    PubMed

    Ambach, W; Rehwald, W; Blumthaler, M; Eisner, H; Brunner, P

    1989-01-01

    Measurements of the gross beta activity of snow samples from four Alpine glaciers contaminated by radioactive fallout from the Chernobyl nuclear accident and a gamma-spectrum analysis of selected samples are reported. The results are discussed with respect to possible risks to the population from using meltwater from these glaciers as drinking water.

  1. Ambient Nitrogen Deposition Gradients in the Rocky Mountains and the Effect on Alpine Moist Meadow Ecosystems

    NASA Astrophysics Data System (ADS)

    Churchill, A. C.; Bowman, W. D.

    2012-12-01

    The chronic ambient deposition of nitrogen (N) in alpine ecosystems can have cascading effects on plants, soils and hydrology in both the alpine and areas downstream through leaching and ecosystem export. Nitrogen is traditionally a nutrient limiting for plant growth in the alpine zone and the addition of anthropogenically derived nitrogen has the potential to alter nutrient composition and interactions between soil, plants and hydrology. While deposition is globally widespread its spatial impacts are associated with a proximity to agriculture (fertilizers) and industry (hydrocarbon byproducts), creating gradients of deposition with distance from point sources. Consequently, N deposition levels and potential environmental impacts on ecosystem processes increase in regions with expanding populations and changes in land use. The Rocky Mountains face both enhanced deposition associated with high levels of precipitation at high elevations and increases in anthropogenic sources of nitrogen from conversion of prairie to agricultural fields or development of new roads and housing communities. Our study focuses on linking gradients of ambient nitrogen deposition to responses within the alpine ecosystem, in particular the interactions between plants and soils within moist meadow communities. Previous studies have focused on the effects of N deposition within alpine dry meadows, as these are abundant and generally higher in elevation than other alpine meadow community types. Within these systems critical loads have been estimated to determine at what level N addition directly alters the ecosystem. Alpine moist meadows, however, also cover a substantial portion of the alpine zone, and support a very different plant community with naturally lower species richness. These areas receive heavier snowfall, and are more dependent on the snowpack for ephemeral water availability making them potentially more susceptible to nutrient loading within the snowpack. Along our ambient N

  2. The Glacier Lakes Ecosystem Experiments Site

    Treesearch

    R. C. Musselman

    1994-01-01

    The Glacier Lakes Ecosystem Experiment Site (GLEES), a 600 ha research watershed at 3200-3400 m elevation in the Snowy Range of SE Wyoming, has been established to examine the effects of atmospheric deposition on alpine and subalpine ecosystems. This document provides preliminary data on the landscape habitats, floristics, geology, soils, aquatics, atmospheric...

  3. Seismic properties of rocks affected by hydrothermal alteration: a case study from the Lalor Lake VMS mining camp

    NASA Astrophysics Data System (ADS)

    Miah, K.; Bellefleur, G.; Schetselaar, E.

    2013-12-01

    Global demand of base metals, uranium, diamonds, and precious metals has been pushing technological barrier to find and extract minerals at higher depth, which was not feasible in just a few decades ago. Seismic properties of rocks containing and surrounding ore bodies have been useful in characterizing and modeling geologic structures, and mapping high-resolution images of ore bodies. Although seismic surveys and drill hole sonic and density logs are essential for mineral exploration at depth, limited availability of seismic logs to link rock properties of different ore forming geologic structure is a hindrance to seismic interpretations. Volcanogenic Massive Sulphides (VMS) are rich in minerals and of primary interests among geologists and mining industries alike. VMS deposits occur due to focused discharge of metal-enriched fluids associated in the hydrothermal alteration process, and are rich in Zn, Cu, Pb, Ag, Au, etc. Alteration halos surrounding ore deposits can be widespread, and their locations are easier to determine than the deposits within them. Physical rock properties affected by alteration can provide clues on type and potentially size of ore deposits in the surrounding area. In this context, variations in seismic properties of rocks due to hydrothermal alteration near the deposits can help in improving modeling accuracy, and better interpretation of seismic data for economic mineral exploration. While reflection seismic techniques can resolve ore bodies at higher depths than other conventional geophysical techniques, they are relatively expensive both in terms of field data acquisition and post-processing, especially for high-resolution 3D surveys. Acoustic impedance contrasts of ore lenses with their hosting rock environment; geometry, size and spatial location relative to the surface affect their detection with seismic data. Therefore, apriori knowledge of seismic rock properties from drill hole logs and core samples in the potential survey area

  4. Fischer-Tropsch synthesis of hydrocarbons during sub-solidus alteration of the Strange Lake peralkaline granite, Quebec/Labrador, Canada

    SciTech Connect

    Salvi, S.; Williams-Jones, A.E.

    1997-01-01

    The composition of the carbonic phase(s) of fluid inclusions in pegmatite quartz from the Strange Lake peralkaline complex has been analysed by gas chromatography using online extraction of inclusion contents and a PoraPLOT{reg_sign} Q capillary column. The measured gas species are, in order of abundance, CH{sub 4} H{sub 2}, C{sub 2}H{sub 6}, CO{sub 2}, N{sub 2}, C{sub 3}H{sub 8}, n-C{sub 4}H{sub 10}, n-C{sub 5}H{sub 12}, C{sub 2}H{sub 2}-i-C{sub 4}H{sub 10}, and C{sub 2}H{sub 4}. Minor amounts of i-C{sub 5}H{sub 12}, n-C{sub 6}H{sub 14}, i-C{sub 6}H{sub 14}, and neo-C{sub 6}H{sub 14}, were also detected (but not quantified) in some samples. A suite of quartz samples from Ca-metasomatised pegmatites contains fluid inclusions with a similar distribution of hydrocarbons but much higher proportions of CO{sub 2}. The carbonic fluid coexisted immiscibly with a brine, which on the basis of field and petrographic evidence, was interpreted to have originated from the magma. However, thermodynamic calculations indicate that the above gas species, specifically the hydrocarbons, could not have coexisted at equilibrium in the proportions measured, at any geologically reasonable conditions either prior to or post entrapment. We propose, instead, that the gas compositions measured in the Strange Lake inclusions, and in inclusions from other alkalic complexes, resulted from the production of H{sub 2} during the alteration of arfvedsonite to aegirine, and the subsequent reaction of this H{sub 2} with orthomagmatic CO{sub 2} and CO to form hydrocarbons in a magnetite-catalysed Fischer-Tropsch synthesis. Locally, influx of an oxidised calcic brine, derived externally from the pluton, altered the original composition of the fluid by converting hydrocarbons to CO{sub 2}. 70 refs., 7 figs., 5 tabs.

  5. Hazardous crater lakes studied

    NASA Astrophysics Data System (ADS)

    Kusakabe, Minoru

    Crater lakes usually sit on top of volcanic conduits and act as condensers of magmatic vapor. Studies of crater lakes can therefore provide information on both deep magmatic activity and variations in the degassing state of a shallow magmatic body. The Lake Nyos gas disaster of August 1986 and a similar event in August 1984 at Lake Monoun, both in Cameroon, resulted from the accumulation of magmatic CO2 in the bottom layers of the lakes. Geochemical monitoring of crater lakes is a promising tool for forecasting not only limnic but also volcanic eruptions. Acid-mineralized waters formed by condensation of hot magmatic volatiles in crater lakes are thought to bear some resemblance to hydrothermal fluids acting in the genesis of acid-sulfate alteration and Au-Cu-Ag mineralization of volcanic-hosted precious metal deposits.

  6. Textural, mineralogical and stable isotope studies of hydrothermal alteration in the main sulfide zone of the Great Dyke, Zimbabwe and the precious metals zone of the Sonju Lake Intrusion, Minnesota, USA

    USGS Publications Warehouse

    Li, C.; Ripley, E.M.; Oberthur, T.; Miller, J.D.; Joslin, G.D.

    2008-01-01

    Stratigraphic offsets in the peak concentrations of platinum-group elements (PGE) and base-metal sulfides in the main sulfide zone of the Great Dyke and the precious metals zone of the Sonju Lake Intrusion have, in part, been attributed to the interaction between magmatic PGE-bearing base-metal sulfide assemblages and hydrothermal fluids. In this paper, we provide mineralogical and textural evidence that indicates alteration of base-metal sulfides and mobilization of metals and S during hydrothermal alteration in both mineralized intrusions. Stable isotopic data suggest that the fluids involved in the alteration were of magmatic origin in the Great Dyke but that a meteoric water component was involved in the alteration of the Sonju Lake Intrusion. The strong spatial association of platinum-group minerals, principally Pt and Pd sulfides, arsenides, and tellurides, with base-metal sulfide assemblages in the main sulfide zone of the Great Dyke is consistent with residual enrichment of Pt and Pd during hydrothermal alteration. However, such an interpretation is more tenuous for the precious metals zone of the Sonju Lake Intrusion where important Pt and Pd arsenides and antimonides occur as inclusions within individual plagioclase crystals and within alteration assemblages that are free of base-metal sulfides. Our observations suggest that Pt and Pd tellurides, antimonides, and arsenides may form during both magmatic crystallization and subsolidus hydrothermal alteration. Experimental studies of magmatic crystallization and hydrothermal transport/deposition in systems involving arsenides, tellurides, antimonides, and base metal sulfides are needed to better understand the relative importance of magmatic and hydrothermal processes in controlling the distribution of PGE in mineralized layered intrusions of this type. ?? Springer-Verlag 2007.

  7. Lake whitefish and lake herring population structure and niche in ten south-central Ontario lakes

    USGS Publications Warehouse

    Carl, Leon M.; McGuiness, Fiona

    2006-01-01

    This study compares simple fish communities of ten oligotrophic lakes in south-central Ontario. Species densities and population size structure vary significantly among these lake communities depending on fish species present beyond the littoral zone. Lake whitefish are fewer and larger in the presence of lake herring than in their absence. Diet analysis indicates that lake whitefish shift from feeding on both plankton and benthic prey when lake herring are absent to a primarily benthic feeding niche in the presence of lake herring. When benthic round whitefish are present, lake whitefish size and density decline and they move lower in the lake compared to round whitefish. Burbot are also fewer and larger in lakes with lake herring than in lakes without herring. Burbot, in turn, appear to influence the population structure of benthic coregonine species. Lower densities of benthic lake whitefish and round whitefish are found in lakes containing large benthic burbot than in lakes with either small burbot or where burbot are absent. Predation on the pelagic larvae of burbot and lake whitefish by planktivorous lake herring alters the size and age structure of these populations. As life history theory predicts, those species with poor larval survival appear to adopt a bet-hedging life history strategy of long-lived individuals as a reproductive reserve.

  8. Invasive Mussels Alter the Littoral Food Web of a Large Lake: Stable Isotopes Reveal Drastic Shifts in Sources and Flow of Energy

    PubMed Central

    Ozersky, Ted; Evans, David O.; Barton, David R.

    2012-01-01

    We investigated how establishment of invasive dreissenid mussels impacted the structure and energy sources of the littoral benthic food web of a large temperate lake. We combined information about pre- and postdreissenid abundance, biomass, and secondary production of the littoral benthos with results of carbon and nitrogen stable isotope analysis of archival (predreissenid) and recent (postdreissenid) samples of all common benthic taxa. This approach enabled us to determine the importance of benthic and sestonic carbon to the littoral food web before, and more than a decade after dreissenid establishment. Long term dreissenid presence was associated with a 32-fold increase in abundance, 6-fold increase in biomass, and 14-fold increase in secondary production of the littoral benthos. Dreissenids comprised a large portion of the post-invasion benthos, making up 13, 38, and 56% of total abundance, biomass, and secondary production, respectively. The predreissenid food web was supported primarily by benthic primary production, while sestonic material was relatively more important to the postdreissenid food web. The absolute importance of both sestonic material and benthic primary production to the littoral benthos increased considerably following dreissenid establishment. Our results show drastic alterations to food web structure and suggest that dreissenid mussels redirect energy and material from the water column to the littoral benthos both through biodeposition of sestonic material as well as stimulation of benthic primary production. PMID:23284673

  9. Invasive mussels alter the littoral food web of a large lake: stable isotopes reveal drastic shifts in sources and flow of energy.

    PubMed

    Ozersky, Ted; Evans, David O; Barton, David R

    2012-01-01

    We investigated how establishment of invasive dreissenid mussels impacted the structure and energy sources of the littoral benthic food web of a large temperate lake. We combined information about pre- and postdreissenid abundance, biomass, and secondary production of the littoral benthos with results of carbon and nitrogen stable isotope analysis of archival (predreissenid) and recent (postdreissenid) samples of all common benthic taxa. This approach enabled us to determine the importance of benthic and sestonic carbon to the littoral food web before, and more than a decade after dreissenid establishment. Long term dreissenid presence was associated with a 32-fold increase in abundance, 6-fold increase in biomass, and 14-fold increase in secondary production of the littoral benthos. Dreissenids comprised a large portion of the post-invasion benthos, making up 13, 38, and 56% of total abundance, biomass, and secondary production, respectively. The predreissenid food web was supported primarily by benthic primary production, while sestonic material was relatively more important to the postdreissenid food web. The absolute importance of both sestonic material and benthic primary production to the littoral benthos increased considerably following dreissenid establishment. Our results show drastic alterations to food web structure and suggest that dreissenid mussels redirect energy and material from the water column to the littoral benthos both through biodeposition of sestonic material as well as stimulation of benthic primary production.

  10. A Comparison of Sedimentary Environments in an Alpine Meadow and the Influence on Groundwater Availability, Applying Near Surface Geophysical Methods.

    NASA Astrophysics Data System (ADS)

    Ayers, M.; Galvin, J. L.; Blacic, T. M.; Yarnell, S. M.; Craig, M. S.

    2016-12-01

    Meadows are recognized for their value to the ecological, hydrologic, and aesthetic functions of a watershed as they attenuate floods, improve water quality and support herbaceous vegetation, promoting high biodiversity. During the dry summer growing season, Alpine meadow complexes are dependent on timely groundwater distribution of winter precipitation preserved in snowpack, and are therefore highly vulnerable to altered seasonal precipitation patterns. Comprehensive understanding of groundwater flux that supports meadow reaches relies on knowledge of their complex stratigraphic and structural subsurface framework. Hydrogeophysics has emphasized the combination of near surface geophysical techniques to qualitatively define these parameters. Van Norden meadow located in the Donner Summit area west of Lake Tahoe, one of the largest sub-alpine meadows in the Sierra Nevada mountain range of Northern California, provides a natural hydrologic laboratory. Previous field campaigns in 2014 and 2015 collected GPR frequencies of 50, 100, and 270 MHz as well as electrical resistivity profiles to better define the groundwater table, sedimentary, and structural features. Where the previous field campaigns yielded cross-sections characterizing the meadow proper as fluvial, fine grained alluvial plain to coarser stream gravels, positioned over glacial till, the 2016 transects aim to cover the proto meadow, before the anthropogenic creation of a reservoir Lake Van Norden. To facilitate transfer of this area from a local land trust to the Forestry Service, a drain in the dam supporting Lake Van Norden was opened in 2016, greatly reducing the water volume, exposing a significant area of previously inundated land and decades of lakebed sediments that will allow us to ascertain thickness and distribution to the underlying glacial till. Lakebed sediment accounts for differential infiltration rates and as in other meadow sites there are most likely buried channels that influence

  11. Hydrological Trends in a High Alpine Watershed in Rocky Mountain National Park

    NASA Astrophysics Data System (ADS)

    Pina, A.; Moore, C. E.; Records, R.; Medina, I. D.; Miner, G. L.

    2014-12-01

    Recent studies reveal amplified air temperature warming trends in the Rocky Mountains than global averages, as well as earlier snowmelt timing and decreased snow-water equivalent (SWE) relative to past records in this region. Changes in SWE and snowmelt runoff timing directly impact water availability in alpine watersheds as well as downstream ecosystem services. In this study we evaluated local trends in air temperature, precipitation, snowpack, and streamflow timing to look for similarities to regional trends reported in literature. We assessed two long-term alpine data collection sites in Rocky Mountain National Park: Bear Lake SNOTEL site (2896 m; 1981-2013) and Loch Vale Watershed (3159 m; 1984-2011), using the Mann-Kendall test to examine trends in average monthly temperature, number of days above freezing, peak SWE depth and timing, number of snow-free days, and total precipitation at Bear Lake, as well as streamflow volume and timing metrics at the outlet of Loch Vale. We found seasonal patterns and magnitudes of warming similar to regional trend findings, with significant increasing trends in average monthly mean air temperatures for most months. The average number of days below 0ºC also significantly decreased in fall and winter. However, we found no significant trends in peak SWE, discharge rate, precipitation, accumulated snowfall, or the number of snow-free days at Bear Lake or Loch Vale sites. These results suggest reported regional warming trends are not reflected in localized snowmelt trends in alpine Rocky Mountain watersheds.

  12. Abiotic and biotic controls of spatial pattern at alpine treeline

    USGS Publications Warehouse

    Malanson, George P.; Xiao, Ningchuan; Alftine, K.J.; Bekker, Mathew; Butler, David R.; Brown, Daniel G.; Cairns, David M.; Fagre, Daniel; Walsh, Stephen J.

    2000-01-01

    At alpine treeline, trees and krummholz forms affect the environment in ways that increase their growth and reproduction. We assess the way in which these positive feedbacks combine in spatial patterns to alter the environment in the neighborhood of existing plants. The research is significant because areas of alpine tundra are susceptible to encroachment by woody species as climate changes. Moreover, understanding the general processes of plant invasion is important. The importance of spatial pattern has been recognized, but the spatial pattern of positive feedbacks per se has not been explored in depth. We present a linked set of models of vegetation change at an alpine forest-tundra ecotone. Our aim is to create models that are as simple as possible in order to test specific hypotheses. We present results from a model of the resource averaging hypothesis and the positive feedback switch hypothesis of treelines. We compare the patterns generated by the models to patterns observed in fine scale remotely sensed data.

  13. Nd, Sr, Pb, Ar, and O isotopic systematics of Sturgeon Lake kimberlite, Saskatchewan, Canada: constraints on emplacement age, alteration, and source composition

    NASA Astrophysics Data System (ADS)

    Hegner, E.; Roddick, J. C.; Fortier, S. M.; Hulbert, L.

    1995-06-01

    Rb-Sr isotopic dating of phlogopite megacryst samples separated from Sturgeon Lake kimberlite, Saskatchewan, yields a crystallization age of 98±1 Ma (2 σ, MSWD=1.2; 87Sr/86Sr( t)=0.7059). The 40Ar/39Ar analyses of a phlogopite megacryst sample indicate the presence of large amounts of excess 40Ar and yield an excessively old age of ˜410 Ma. Assessment of the Ar data using isotope correlation plots indicates clustering of the data points about a mixing line between the radiogenic 40Ar component at 98 Ma and a trapped component with uniform 36Ar/40Ar and Cl/40Ar. Values of δ 18O as high as +20‰ (VSMOW) for calcite from the groundmass and a whole-rock sample indicate pervasive low-temperature alteration. The δ 13C of matrix carbonate is -11.3‰ (PDB), slightly lighter than typical values from the literature. The δ 18O values of about +5‰ (VSMOW) for brown phlogopite megacrysts may be primary, green phlogopites are interpreted to be an alteration product of the brown variety and are 2‰ heavier. Initial Nd-Sr-Pb isotopic ratios for a whole-rock sample ( ɛ Nd=+0.8; 87Sr/86Sr=0.7063, 206Pb/204Pb=18.67, 207Pb/204Pb=15.54, 208Pb/204Pb=38.97) suggest an affinity with group I kimberlites. Initial ɛ Nd values of +1.7 and +0.5 (87Sr/86Sr( t)=0.7053 and 0.7050) for eclogitic and lherzolitic garnet megacryst samples, and values of 0.0 for two phlogopite megacryst samples reflect an origin from an isotopically evolving melt due to assimilation of heterogeneous mantle. Lilac high-Cr lherzolitic garnet megacrysts give an unusually high ɛ Nd(98. Ma) of +28.6 (87Sr/86Sr=0.7046) indicating a xenocrystic origin probably from the lithospheric mantle. The very radiogenic 87Sr/86Sr and 206Pb/204Pb ratios of the kimberlite are consistent with melting of EM II (enriched) mantle components.

  14. Europe's battery: The making of the Alpine energy landscape, 1870-1955

    NASA Astrophysics Data System (ADS)

    Landry, Marc D., II

    This study examines the environmental history of hydropower development in the Alps from the mid-nineteenth to the mid-twentieth centuries. Analyzing government archival files, associational journals, conference proceedings, and published contemporary material from several Alpine countries, it seeks to determine how and why Europeans modified the Alpine landscape to generate hydropower, and to explore the consequences of these decisions. I argue that during this time period, Europeans thoroughly transformed the Alpine environment, creating what I call "Europe's Battery": a gigantic system for storing hydropower and distributing it on a continental scale. This study shows how nineteenth-century innovations in energy technology contributed to a dramatic shift in the perception of the Alps as a landscape of "white coal." It demonstrates how at the outset of electrification, Europeans modified Alpine waterways on an unprecedented scale in order to tap into the power of flowing Alpine water. I show how after the turn of the twentieth century, Europeans took advantage of the unique mountain environment to store water, first by converting existing lakes into reservoirs. The practice countered what was perceived to be the greatest disadvantage of white coal: its climate-influenced inconstancy. This study shows the importance of war, and especially the First World War, in the forging of the new Alpine landscape. Finally, this study illustrates how from the interwar period to the aftermath of the Second World War, Europeans put the finishing touches on the new Alpine energy landscape by creating large reservoirs behind dams and feeding Alpine hydroelectricity into a burgeoning European electricity grid. By 1955 the Alps had become one of the most important energy landscapes in Europe. This history of the Alpine energy landscape contributes to a number of historiographical fields. It represents an important chapter in the environmental history of one of the world's most

  15. Landscape History of Grosses Moos, NW Swiss Alpine Foreland.

    NASA Astrophysics Data System (ADS)

    Joanna Heer, Aleksandra; Adamiec, Grzegorz; Veit, Heinz; May, Jan-Hendrik; Novenko, Elena; Hajdas, Irka

    2017-04-01

    The western Swiss Plateau with Lake Neuchâtel is part of the alpine foreland and among the key areas for the reconstruction of environmental changes since the last postglacial. This study was carried out in a landscape located NE of the lake and called Grosses Moos (The Large Fen) - currently designated the Swiss largest, continuous farming area, after the fen was drained in course of landscape engineering projects performed in Switzerland at the end of the 19th century. The study contributes new results from nine excavations of littoral ridges identified in Grosses Moos, and integrates sedimentology, paleo-environmental analysis and three independent chronological methods. Radiocarbon dating, pollen analysis and optically stimulated luminescence (OSL) were applied to the sediments. While pollen and radiocarbon follow the standard procedures, the evaluation of the luminescence age estimates demanded adjustment according to the physical and microdosimetric properties of the alpine quartz, and consideration of the peculiarities of the changing littoral environments of Grosses Moos. The Grosses Moos landscape developed on the temporary surface of the post-Last Glacial sedimentary infill of the over-deepened glacial Aare valley. In this study the landscape history has been fitted into the existing supraregional time scales of NGRIP, the Swiss bio-zones system and the human history based on archaeological and historic records and covers a time span of up to 15'000 yr b2k. The wide-ranging suite of geomorphic features and sedimentary sequences, including littoral lake sediments, beach ridges, dunes, palaeo-channels, peat and colluvial deposits, enable the extensive reconstruction of spatially and temporally variable natural shaping processes. In addition, our results indicate remobilization of soil, colluvium, and sediment due to human settlement activities since the Neolithic - with an important increase in sediment load and spatial variability since the Bronze Age

  16. Alpine 1/Federal: Executive summary final report

    SciTech Connect

    Witcher, J.C.

    1994-04-01

    This summary report overviews a State of Arizona and US Department of Energy funded drilling project to determine if near-term hot dry rock (HDR) geothermal potential exists in the eastern portion of the White Mountains region of Arizona. A 4,505 feet deep slim-hole exploratory well, Alpine1/Federal, was drilled within the Apache-Sitgreaves National Forest at Alpine Divide near the Alpine Divide camp ground about 5 miles north of Alpine, Arizona in Apache County (Figure 1). A comprehensive technical report, in two parts, details the results of the project. Part 1, Alpin1/Federal, Drilling Report discusses the drilling operations, logging program, permitting and site selection for the hole. Part 2, Temperature Gradients, Geothermal Potential, and Geology, summarizes the temperature gradients, heat flow, geothermal potential, and subsurface geology.

  17. Tourism and Water: Themes of the Alpine Convention

    NASA Astrophysics Data System (ADS)

    Imhof, R.

    2012-04-01

    environment. This needs to be accomplished by balancing the local population's interests with environmental needs. Water is considered as a crucial element for different uses such as hydroelectricity production, irrigation or drinking water as well as in biotopes, especially forests, environmental regeneration and diversity and in natural and cultural landscapes features. Aspects of water protection can be found in the protocols on Energy, Nature Conservation and Landscape Protection, Soil Protection, Tourism, Spatial Planning and Sustainable Development, Mountain Agriculture, Mountain Forests and Transport. However a specific protocol on water is not in place. The Reports on the state of the Alps are published regularly by the Alpine Conference. In November 2006 water was chosen as the topic for the second Report on the State of the Alps. The report compiles information from the Alpine Countries on monitoring programmes, chemical quality of water (point sources, diffuse sources and the chemical status of surface and groundwater in the Alps), water abstraction, residual water and hydro-peaking, droughts and water scarcity, reservoirs and regulated lakes as well on river morphology and continuity. Finally, it summarizes information on property rights and provisions for access to water in the different countries, charges regarding the use of water, different management systems for water supply (public or private), hydro power generation in the Alps and water use management conflicts. The Report was adopted by the Ministers during the Xth Alpine Conference in Evian (France) in 2009. This Conference additionally set up a platform on Water management in the Alpine area in order to deal continually with the theme of water in the Alps. Within this platform, objectives that were identified in the second Report on the State of the Alps should be pursued and examples of good practices exchanged. The platform developed inter alia common guidelines for the use of small hydropower in the

  18. Establishment patterns of water-elm at Catahoula Lake, Louisiana

    Treesearch

    Karen S. Doerr; Sanjeev Joshi; Richard F. Keim

    2015-01-01

    At Catahoula Lake in central Louisiana, an internationally important lake for water fowl, hydrologic alterations to the surrounding rivers and the lake itself have led to an expansion of water-elm (Planera aquatic J.F. Gmel.) into the lake bed. In this study, we used dendrochronology and aerial photography to quantify the expansion of water-elm in the lake and identify...

  19. 76 FR 25299 - Alpine County Resource Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-04

    ... Forest Service Alpine County Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of Meeting. SUMMARY: The Alpine County Resource Advisory Committee (RAC) will meet in Markleeville, CA. The... held in Alpine County at the Alpine Early Learning Center, 100 Foothill Road, Markleeville, CA...

  20. Soil warming increases plant species richness but decreases germination from the alpine soil seed bank.

    PubMed

    Hoyle, Gemma L; Venn, Susanna E; Steadman, Kathryn J; Good, Roger B; McAuliffe, Edward J; Williams, Emlyn R; Nicotra, Adrienne B

    2013-05-01

    Global warming is occurring more rapidly above the treeline than at lower elevations and alpine areas are predicted to experience above average warming in the future. Temperature is a primary factor in stimulating seed germination and regulating changes in seed dormancy status. Thus, plant regeneration from seed will be crucial to the persistence, migration and post disturbance recruitment of alpine plants in future climates. Here, we present the first assessment of the impact of soil warming on germination from the persistent alpine soil seed bank. Contrary to expectations, soil warming lead to reduced overall germination from the soil seed bank. However, germination response to soil temperature was species specific such that total species richness actually increased by nine with soil warming. We further explored the system by assessing the prevalence of seed dormancy and germination response to soil disturbance, the frequency of which is predicted to increase under climate change. Seeds of a significant proportion of species demonstrated physiological dormancy mechanisms and germination of several species appeared to be intrinsically linked to soil disturbance. In addition, we found no evidence of subalpine species and little evidence of exotic weed species in the soil, suggesting that the soil seed bank will not facilitate their invasion of the alpine zone. In conclusion, changes in recruitment via the alpine soil seed bank can be expected under climate change, as a result of altered dormancy alleviation and germination cues. Furthermore, the alpine soil seed bank, and the species richness therein, has the potential to help maintain local species diversity, support species range shift and moderate species dominance. Implications for alpine management and areas for further study are also discussed. © 2013 Blackwell Publishing Ltd.

  1. Global Research Initiative in Alpine Environments: A New GLORIA Site in Southwestern Montana

    NASA Astrophysics Data System (ADS)

    Apple, M. E.; Pullman, T. Y.; Mitman, G. G.

    2007-12-01

    Global climate change is expected to have pronounced effects on the alpine environments and thus the alpine plants of western North America. Predicted responses include an upward migration of treelines, altered species compositions, changes in the percentage of land covered by vegetation, and a change in the phenology of alpine plants. To determine the effects of climate change on the alpine flora of southwestern Montana, we are installing a GLORIA (Global Research Initiative in Alpine Environments) site in order to monitor temperature, species composition, and percent cover of vascular plants, lichens, and mosses along an ascending altitudinal gradient. We are including lichens and mosses because of their importance as ecological indicator species. The abundance and spatial distribution of lichens and mosses provides essential baseline data for long-term monitoring of local and global impacts on the environment. Mt. Fleecer (9250 ft.), which is west of the continental divide and semi-isolated from other peaks in the Anaconda-Pintlar Range, is currently the most likely location for the southwestern Montana GLORIA site. Mt. Fleecer is accessible because it does not have the steep and hazardous glaciated talus cirques that characterize many of the neighboring, higher peaks. However, if an accessible and suitable higher summit is found, then it will be included as the highest summit in the GLORIA site. Interesting species at Mt. Fleecer include the whitebark pine, Pinus albicaulis, which is a keystone species in high mountain ecosystems of the western United States and Canada, the green gentian, Frasera speciosa, and the shooting star, Dodecatheon pulchellum. Data from this site will become part of a global network of GLORIA sites with which we will assess changes in alpine flora. Information gained from this GLORIA site can also be used as a link between studies of alpine climate change and related investigations on the timing of snowmelt and its influence on

  2. Effect of dietary alpine butter rich in conjugated linoleic acid on milk fat composition of lactating sows.

    PubMed

    Schmid, Alexandra; Collomb, Marius; Bee, Giuseppe; Bütikofer, Ulrich; Wechsler, Daniel; Eberhard, Pius; Sieber, Robert

    2008-07-01

    Multiparous sows (n 17) were included in a controlled cross-over-study in order to investigate the influence of a natural source of conjugated linoleic acid (CLA) (alpine butter) on the milk fatty acid composition of lactating sows (as an animal model for lactating women) and on the growth performance of their progeny. The usual fat source of a standard lactation diet was replaced by either CLA-rich alpine butter or margarine (control diet). Compared with the margarine diet, feeding the alpine butter-supplemented diet increased (P 0.05) affected. Growth performance of the progeny was similar for both dietary treatments. In summary, the findings show that adding alpine butter to the diet does not provoke a milk fat depression and does not alter the composition of total SFA, MUFA and PUFA in sow milk but increases its CLA concentration.

  3. Seed dormancy in alpine species.

    PubMed

    Schwienbacher, Erich; Navarro-Cano, Jose Antonio; Neuner, Gilbert; Erschbamer, Brigitta

    2011-10-01

    In alpine species the classification of the various mechanisms underlying seed dormancy has been rather questionable and controversial. Thus, we investigated 28 alpine species to evaluate the prevailing types of dormancy. Embryo type and water impermeability of seed coats gave an indication of the potential seed dormancy class. To ascertain the actual dormancy class and level, we performed germination experiments comparing the behavior of seeds without storage, after cold-dry storage, after cold-wet storage, and scarification. We also tested the light requirement for germination in some species. Germination behavior was characterized using the final germination percentage and the mean germination time. Considering the effects of the pretreatments, a refined classification of the prevailing dormancy types was constructed based on the results of our pretreatments. Only two out of the 28 species that we evaluated had predominantly non-dormant seeds. Physiological dormancy was prevalent in 20 species, with deep physiological dormancy being the most abundant, followed by non-deep and intermediate physiological dormancy. Seeds of four species with underdeveloped embryos were assigned to the morphophysiologial dormancy class. An impermeable seed coat was identified in two species, with no additional physiological germination block. We defined these species as having physical dormancy. Light promoted the germination of seeds without storage in all but one species with physiological dormancy. In species with physical dormancy, light responses were of minor importance. We discuss our new classification in the context of former germination studies and draw implications for the timing of germination in the field.

  4. Seed dormancy in alpine species

    PubMed Central

    Schwienbacher, Erich; Navarro-Cano, Jose Antonio; Neuner, Gilbert; Erschbamer, Brigitta

    2011-01-01

    In alpine species the classification of the various mechanisms underlying seed dormancy has been rather questionable and controversial. Thus, we investigated 28 alpine species to evaluate the prevailing types of dormancy. Embryo type and water impermeability of seed coats gave an indication of the potential seed dormancy class. To ascertain the actual dormancy class and level, we performed germination experiments comparing the behavior of seeds without storage, after cold-dry storage, after cold-wet storage, and scarification. We also tested the light requirement for germination in some species. Germination behavior was characterized using the final germination percentage and the mean germination time. Considering the effects of the pretreatments, a refined classification of the prevailing dormancy types was constructed based on the results of our pretreatments. Only two out of the 28 species that we evaluated had predominantly non-dormant seeds. Physiological dormancy was prevalent in 20 species, with deep physiological dormancy being the most abundant, followed by non-deep and intermediate physiological dormancy. Seeds of four species with underdeveloped embryos were assigned to the morphophysiologial dormancy class. An impermeable seed coat was identified in two species, with no additional physiological germination block. We defined these species as having physical dormancy. Light promoted the germination of seeds without storage in all but one species with physiological dormancy. In species with physical dormancy, light responses were of minor importance. We discuss our new classification in the context of former germination studies and draw implications for the timing of germination in the field. PMID:24415831

  5. Moisture and temperature controls on nitrification differ among ammonia oxidizer communities from three alpine soil habitats

    NASA Astrophysics Data System (ADS)

    Osborne, Brooke B.; Baron, Jill S.; Wallenstein, Matthew D.

    2016-03-01

    Climate change is altering the timing and magnitude of biogeochemical fluxes in many highelevation ecosystems. The consequent changes in alpine nitrification rates have the potential to influence ecosystem scale responses. In order to better understand how changing temperature and moisture conditions may influence ammonia oxidizers and nitrification activity, we conducted laboratory incubations on soils collected in a Colorado watershed from three alpine habitats (glacial outwash, talus, and meadow). We found that bacteria, not archaea, dominated all ammonia oxidizer communities. Nitrification increased with moisture in all soils and under all temperature treatments. However, temperature was not correlated with nitrification rates in all soils. Site-specific temperature trends suggest the development of generalist ammonia oxidzer communities in soils with greater in situ temperature fluctuations and specialists in soils with more steady temperature regimes. Rapidly increasing temperatures and changing soil moisture conditions could explain recent observations of increased nitrate production in some alpine soils.

  6. Moisture and temperature controls on nitrification differ among ammonia oxidizer communities from three alpine soil habitats

    USGS Publications Warehouse

    Osborne, Brooke B; Baron, Jill S.; Wallenstein, Matthew D.

    2016-01-01

    Climate change is altering the timing and magnitude of biogeochemical fluxes in many high elevation ecosystems. The consequent changes in alpine nitrification rates have the potential to influence ecosystem scale responses. In order to better understand how changing temperature and moisture conditions may influence ammonia oxidizers and nitrification activity, we conducted laboratory incubations on soils collected in a Colorado watershed from three alpine habitats (glacial outwash, talus, and meadow). We found that bacteria, not archaea, dominated all ammonia oxidizer communities. Nitrification increased with moisture in all soils and under all temperature treatments. However, temperature was not correlated with nitrification rates in all soils. Site-specific temperature trends suggest the development of generalist ammonia oxidizer communities in soils with greater in situ temperature fluctuations and specialists in soils with more steady temperature regimes. Rapidly increasing temperatures and changing soil moisture conditions could explain recent observations of increased nitrate production in some alpine soils.

  7. Fluids preserved in variably altered graphitic pelitic schists in the Dufferin Lake Zone, south-central Athabasca Basin, Canada: implications for graphite loss and uranium deposition

    NASA Astrophysics Data System (ADS)

    Pascal, Marjolaine; Boiron, Marie-Christine; Ansdell, Kevin; Annesley, Irvine R.; Kotzer, Tom; Jiricka, Dan; Cuney, Michel

    2016-06-01

    The Athabasca Basin (Canada) contains the highest grade unconformity-type uranium deposits in the world. Underlying the Athabasca Group sedimentary rocks of the Dufferin Lake Zone are variably graphitic, pelitic schists (VGPS), altered to chlorite and hematite (Red/Green Zone: RGZ). They were locally bleached near the unconformity during paleoweathering and/or later fluid interaction. Overall, graphite was lost from the RGZ and the bleached zone relative to the original VGPS. Fluid inclusions were examined in different generations of quartz veins, using microthermometry and Raman spectroscopy, to characterize and compare the different fluids that interacted with the RGZ and the VGPS. In the VGPS, CH4-, and N2-rich fluid inclusions, which homogenize into the vapor phase between -100 and -74 °C, and -152 and -125 °C, respectively, and CO2-rich fluid inclusions, homogenizing either into vapor or liquid between 20 and 28 °C, are present. Carbonic fluids could be the result of the breakdown of graphite to CH4 + CO2, whereas N2-rich fluid is interpreted to be the result of breakdown of feldspars/micas to NH4 ++N2. In the RGZ, the presence of fluid inclusions with low ice melting temperature (-38 to -16 °C) reflect the presence of CaCl2, and fluid inclusions with halite daughter minerals that dissolve between 190 and 240 °C indicate the presence of highly saline fluids. These fluids are interpreted to be derived from the Athabasca Basin. The circulation of carbonic fluids and brines occurred during two different events related to different P-T conditions of trapping. The carbonic fluids interacted with basement rocks during retrograde metamorphism of the basement rocks before deposition of the Athabasca Basin, whereas the brines circulated after the deposition of the Athabasca Basin. These latter fluids are similar to brines related to uranium mineralization at McArthur River and thus, in addition to possibly being related to graphite depletion in the RGZ, they could

  8. Hybridization and restricted gene flow between native and introduced stocks of Alpine whitefish (Coregonus sp.) across multiple environments

    PubMed Central

    Winkler, Kathrin A; Pamminger-Lahnsteiner, Barbara; Wanzenböck, Josef; Weiss, Steven

    2011-01-01

    Translocations of Baltic whitefish (Coregonus sp.) into Austrian Alpine lakes have created ‘artificial hybrid zones’, threatening the genetic integrity of native lineages. We evaluate the genetic structure of Coregonus in Austrian lakes and characterize hybridization and introgression between native and introduced lineages. Fifteen populations (N= 747) were assessed for allelic variation at eight microsatellite loci and a reduced set (N= 253) for variation across two mtDNA genes (cyt b and NADH-3). Bayesian approaches were used to estimate individual admixture proportions (q-values) and classify genotypes as native, introduced or hybrids. q-value distributions varied among populations highlighting differential hybridization and introgression histories. Many lakes revealed a clear distinction between native and introduced genotypes despite hybridization, whereas some locations revealed hybrid swarms. Genetic structure among lakes was congruent with morphological divergence and novelty raising speculation of multiple taxa, including a population south of the Alps, outside the putative native range of Coregonus. Although statistically congruent with inferences based on nuclear markers, mitochondrial haplotype data was not diagnostic with respect to native and non-native lineages, supporting that the Alpine region was colonized post-glacially by an admixture of mtDNA lineages, which coalesce >1 Ma. Mechanisms promoting or eroding lineage isolation are discussed, as well as a high potential to conserve native Alpine lineages despite the extensive historical use of introduced Baltic stocks. PMID:21199024

  9. Climate-related changes of soil characteristics affect bacterial community composition and function of high altitude and latitude lakes.

    PubMed

    Rofner, Carina; Peter, Hannes; Catalán, Núria; Drewes, Fabian; Sommaruga, Ruben; Pérez, María Teresa

    2016-11-01

    Lakes at high altitude and latitude are typically unproductive ecosystems where external factors outweigh the relative importance of in-lake processes, making them ideal sentinels of climate change. Climate change is inducing upward vegetation shifts at high altitude and latitude regions that translate into changes in the pools of soil organic matter. Upon mobilization, this allochthonous organic matter may rapidly alter the composition and function of lake bacterial communities. Here, we experimentally simulate this potential climate-change effect by exposing bacterioplankton of two lakes located above the treeline, one in the Alps and one in the subarctic region, to soil organic matter from below and above the treeline. Changes in bacterial community composition, diversity and function were followed for 72 h. In the subarctic lake, soil organic matter from below the treeline reduced bulk and taxon-specific phosphorus uptake, indicating that bacterial phosphorus limitation was alleviated compared to organic matter from above the treeline. These effects were less pronounced in the alpine lake, suggesting that soil properties (phosphorus and dissolved organic carbon availability) and water temperature further shaped the magnitude of response. The rapid bacterial succession observed in both lakes indicates that certain taxa directly benefited from soil sources. Accordingly, the substrate uptake profiles of initially rare bacteria (copiotrophs) indicated that they are one of the main actors cycling soil-derived carbon and phosphorus. Our work suggests that climate-induced changes in soil characteristics affect bacterioplankton community structure and function, and in turn, the cycling of carbon and phosphorus in high altitude and latitude aquatic ecosystems.

  10. Quaternary geology of the DFDP-2 drill holes, Alpine Fault, New Zealand

    NASA Astrophysics Data System (ADS)

    Upton, P.; Cox, S.; Howarth, J. D.; Sutherland, R.; Langridge, R.; Barth, N. C.; Atkins, C.

    2015-12-01

    A 240 m-thick Quaternary sediment sequence in Whataroa Valley was much thicker than predicted before drilling. DFDP-2A and DFDP-2B were mostly drilled through the sequence by dual-rotary method using air or water circulation, returning cuttings bagged at 1 or 2 m sample intervals. Some sorting/bias and contamination occurred. Core was retrieved in DFDP-2A from 125-160 m, with highly variable recovery (0-100%) and mixed preservation/quality. The sequence is interpreted to comprise: fluvial-glacial gravels (0-58 m); grading downward into sandy lake delta sediments (59-77 m); overlying a monotonous sequence of lake mud and silts, with rare pebble-cobble diamictite (77-206 m); with a basal unit (206-240 m) containing coarse cobbles and boulders that may represent a distinct till/diamictite. Evidence has yet to be found for any marine influence in lowermost sediments, despite deposition at least 120 m below present day sea level, and potentially 200 m bsl if uplift has occurred on the Alpine Fault. When corrected for uplift the lacustrine sequence broadly correlates to those in present Lakes Rotokina and Wahapo, suggesting a substantial (~100 km2) pro-glacial lake once covered the area. Radiocarbon dating of plant fragments indicate 70 m of upper lacustrine and deltaic sediments (129-59 m) were deposited rapidly between 16350-15800 Cal BP. Overlying alluvial gravels are much younger (<1 ka), but potentially also involved pulses of rapid aggradation. The sequence provides a record of sedimentation on the Alpine Fault hanging wall following late-glacial ice retreat up Whataroa Valley, with uplift and erosion followed by Holocene alluvial gravel deposition. Future work will address: (1) the nature and history of sedimentation, including the lithology and origin of sediments; (2) what, if any, geological record of tectonics (movement) or Alpine Fault earthquakes (shaking) the sediments contain.

  11. Evidence for organochlorine contamination in Lake Tahoe, California

    SciTech Connect

    Datta, S.; Matsumura, F.

    1995-12-31

    Organochlorine pollutants were measured in mature lake trout (Salvelinus namaycush) from Lake Tahoe, California. This is the first report of organochlorine contamination in this lake which is considered to be pristine; Lake Tahoe, an alpine lake, located in the Sierra Nevadas, has not been subject to direct contamination by industrial discharges or agricultural runoff. Multiresidue analysis of chlorinated compounds in the belly flap tissues of lake trout revealed wet weight concentrations of PCBs and DDE in the low ppb range using EIMS and SIM. Full spectra of specific PCB congeners and DDE were obtained using extracts of fish fat tissue. The presence of these pollutants in biota suggests that atmospheric transport may be a significant source of input to the Lake Tahoe ecosystem.

  12. Erosion by an Alpine glacier

    NASA Astrophysics Data System (ADS)

    Herman, Frédéric; Beyssac, Olivier; Brughelli, Mattia; Lane, Stuart N.; Leprince, Sébastien; Adatte, Thierry; Lin, Jiao Y. Y.; Avouac, Jean-Philippe; Cox, Simon C.

    2015-10-01

    Assessing the impact of glaciation on Earth’s surface requires understanding glacial erosion processes. Developing erosion theories is challenging because of the complex nature of the erosion processes and the difficulty of examining the ice/bedrock interface of contemporary glaciers. We demonstrate that the glacial erosion rate is proportional to the ice-sliding velocity squared, by quantifying spatial variations in ice-sliding velocity and the erosion rate of a fast-flowing Alpine glacier. The nonlinear behavior implies a high erosion sensitivity to small variations in topographic slope and precipitation. A nonlinear rate law suggests that abrasion may dominate over other erosion processes in fast-flowing glaciers. It may also explain the wide range of observed glacial erosion rates and, in part, the impact of glaciation on mountainous landscapes during the past few million years.

  13. Erosion by an Alpine glacier.

    PubMed

    Herman, Frédéric; Beyssac, Olivier; Brughelli, Mattia; Lane, Stuart N; Leprince, Sébastien; Adatte, Thierry; Lin, Jiao Y Y; Avouac, Jean-Philippe; Cox, Simon C

    2015-10-09

    Assessing the impact of glaciation on Earth's surface requires understanding glacial erosion processes. Developing erosion theories is challenging because of the complex nature of the erosion processes and the difficulty of examining the ice/bedrock interface of contemporary glaciers. We demonstrate that the glacial erosion rate is proportional to the ice-sliding velocity squared, by quantifying spatial variations in ice-sliding velocity and the erosion rate of a fast-flowing Alpine glacier. The nonlinear behavior implies a high erosion sensitivity to small variations in topographic slope and precipitation. A nonlinear rate law suggests that abrasion may dominate over other erosion processes in fast-flowing glaciers. It may also explain the wide range of observed glacial erosion rates and, in part, the impact of glaciation on mountainous landscapes during the past few million years. Copyright © 2015, American Association for the Advancement of Science.

  14. Spatial and temporal patterns in water chemistry of two high elevation lakes in southeast Wyoming

    SciTech Connect

    Musselman, R.C.

    1995-12-31

    The Glacier Lakes Ecosystem Experiments Site (GLEES) was established to examine the effects of atmospheric deposition and climate change on alpine and subalpine ecosystems. This report documents temporal and spatial trends during 1993 in water chemistry in East and West Glacier Lakes. Data are presented on seasonal and lake depth changes in water chemistry of the two lakes. The application of the results to appropriate sampling protocols for two alpine lakes is discussed. Both lakes were sampled during the same day, at midday. Samples were kept cool, returned to the lab the same day, and filtered for analysis. Samples were analyzed for cations and anions, pH, and conductivity at the Rocky Mountain Station Water Chemistry laboratory. Silica and aluminum were also measured for some sample dates.

  15. Lake Biel Holocene sediment record before and after the Aare river deviation (1878 AD)

    NASA Astrophysics Data System (ADS)

    Jeannet, Alice; Corella, Juan Pablo; Kremer, Katrina; Girardclos, Stéphanie

    2014-05-01

    new river input is also linked to a massive and sudden Ti increase, and inversely abrupt Ca decrease in XRF data. This record reveals the significant alteration in the sediment dynamics, and the lake oxygenation changes that the lake experienced when it shifted from a relatively closed basin to a river and delta-influenced basin. Thank you to Flavio S. Anselmetti, Christine Guido and Frédéric Arlaud for help coring on the field and Stefanie Wirth for help at Limnogeology Laboratory. This study, undertaken as a Master thesis, was financed by the Swiss National Foundation projects 121666 and 146889. Reference Thevenon F. et al. 2013. Human impact on the transport of terrigenous and anthropogenic elements to peri-alpine lakes (Switzerland) over the last decades. Aquatic Sciences 75: 413-424.

  16. Rapid response of alpine timberline vegetation to the Younger Dryas climate oscillation in the Colorado Rocky Mountains, USA

    SciTech Connect

    Reasoner, M.A.; Jodry, M.A.

    2000-01-01

    Paleobotanical records from two high-altitude (>3,300 m) sites in Colorado show a clear and immediate response to the Younger Dryas climate oscillation. The Black Mountain Lake and Sky Pond records indicate that alpine timberline migrated upslope to near-modern elevations during the late Bolling-Allerod (13.6--12.9 ka). Subsequent declines in arboreal pollen percentages and accumulation rates during the Younger Dryas interval (12.9--11.7 ka) reflect a downslope displacement of the alpine timberline ecotone of 60--120 m in elevation. This change translates to a cooling of summer temperature by {approximately}0.4--0.9 C and is consistent with proposed Younger Dryas advances of alpine glaciers in the Rocky Mountains to positions close to Little Ice Age maxima. Alpine timberline readvanced upslope to elevations above both sites between 11.7 and 11.4 ka. The concomitant response of temperature-sensitive alpine timberline vegetation in Colorado and late-glacial changes in North Atlantic thermohaline circulating implicates a rapid, widespread atmospheric transmission of the Younger Dryas climate oscillation.

  17. GENE EXPRESSION ALTERATIONS OBSERVED IN PRIMARY CULTURED RAT HEPATOCYTES AFTER TREATMENT WITH CHLORINATED OR CHLORINATED AND OZONATED DRINKING WATER FROM EAST FORK LAKE, OHIO

    EPA Science Inventory

    Drinking water from East Fork Lake was spiked with iodide and bromide, disinfected with chlorine or ozone + chlorine, concentrated ~100-fold using reverse osmosis, and volatile disinfection by-products (DBPs) added back. Primary rat hepatocytes were exposed to full-strength, 1:10...

  18. GENE EXPRESSION ALTERATIONS OBSERVED IN PRIMARY CULTURED RAT HEPATOCYTES AFTER TREATMENT WITH CHLORINATED OR CHLORINATED AND OZONATED DRINKING WATER FROM EAST FORK LAKE, OHIO

    EPA Science Inventory

    Drinking water from East Fork Lake was spiked with iodide and bromide, disinfected with chlorine or ozone + chlorine, concentrated ~100-fold using reverse osmosis, and volatile disinfection by-products (DBPs) added back. Primary rat hepatocytes were exposed to full-strength, 1:10...

  19. Lake Waiau and Púupōhaku - two unusual lakes on Maunakea volcano, Hawaii

    NASA Astrophysics Data System (ADS)

    Leopold, Matthias; Schorghofer, Norbert

    2017-04-01

    High mountain lakes are often a valuable buffer for water availability throughout the year. This is especially the case in alpine deserts like the high alpine areas of the Hawaiian Volcanoes above 3000 m altitude, since the porous and coarse cinder material and basalt boulders do not favor water storage. Púupōhaku ( 4,000m asl), a cinder cone near the summit of Maunakea volcano, Hawaii, has a sporadic pond of water and also nearby Lake Waiau is perched within a cinder cone known as Púuwaiau ( 3600 m asl) which makes it the highest lake on the Hawaiian Islands. With only 210 mm annual precipitation mostly caused by single storm events, and a potential evaporation of up to 5mm/d, permanent water sources are extremely rare in this environment. Several hypotheses were discussed as a possible cause for perching the water in this environment such as an impermeable permafrost base, a massive block of lava or clay layers. We applied geomorphic mappings and electric resistivity tomography to portray the shallow subsurface in the vicinity of the two water bodies. We also used current and unpublished older temperature loggings to evaluate the thermal regime around the lakes. Based on our results, specific electric resistivity values are too low and ground temperatures are too high to be interpreted either as ice rich permafrost or basaltic massive rock. Much more, fine grained material such as ash and its clay-rich weathering products likely cause the perched water table at both study sites. At Lake Waiau we discovered a layer of high electric conductivity that may constitute a significant water reservoir outside of the lake and further be responsible for perching the water towards the lake. Understanding the nature of the two permanent water bodies will help to manage the sensitive alpine environment which includes several endemic species.

  20. Alpine radar conversion for LAWR

    NASA Astrophysics Data System (ADS)

    Savina, M.; Burlando, P.

    2012-04-01

    The Local Area Weather Radar (LAWR) is a ship-born weather radar system operating in X-band developed by the DHI Group to detect precipitation in urban areas. To date more than thirty units are installed in different settings around the world. A LAWR was also deployed in the Alps, at 3883 m a.s.l. on the Kl. Matterhorn (Valais, Switzerland). This was the highest LAWR of the world and it led to the development of an Alpine LAWR system that, besides featuring important technological improvements needed to withstand the severe Alpine conditions, required the development of a new Alpine Radar COnversion Model (ARCOM), which is the main focus of this contribution. The LAWR system is equipped with the original FURUNO fan-beam slotted antenna and the original logarithmic receiver, which limits the radar observations to the video signal (L) withour providing the reflectivity (Z). The beam is 0.95 deg wide and 20 deg high. It can detect precipitation to a max range of 60 km. In order to account for the limited availability of raw signal and information and the specific mountain set-up, the conversion model had to be developed differently from the state-of-the-art radar conversion technique used for this class of radars. In particular, the ARCOM is based on a model used to simulate a spatial dependent factor, hereafter called ACF, which is in turn function of parameters that take in account climatological conditions, also used in other conversion methods, but additionally accounting for local radar beam features and for orographic forcings such as the effective sampling power (sP), which is modelled by means of antenna pattern, geometric ground clutter and their interaction. The result is a conversion factor formulated to account for a range correction that is based on the increase of the sampling volume, partial beam blocking and local climatological conditions. The importance of the latter in this study is double with respect to the standard conversion technique for this

  1. Mercury Sources and Cycling in the Great Lakes: Dramatic Changes Resulting from Altered Atmospheric Loads and the Near-Shore Shunt

    NASA Astrophysics Data System (ADS)

    Krabbenhoft, D. P.; DeWild, J. F.; Maglio, M. M.; Tate, M. T.; Ogorek, J. M.; Hurley, J. P.; Lepak, R.

    2013-12-01

    Mercury (Hg) contamination of the aquatic food webs across the Great Lakes remains a significant environmental issue. However, our ability to prescribe corrective actions has been significantly hampered by a scarcity of data, particularly for methylmercury (MeHg) the most toxic and bioaccumulative form of mercury in freshwater ecosystems. As part of the Great Lakes Restoration Initiative initiated in 2010, a joint effort was undertaken by the U.S. Geological Survey (USGS) and U.S. Environmental Protection Agency (USEPA) to improve our understanding of total Hg and MeHg concentrations and distributions in the Great Lakes. Since 2010, sampling surveys have been conducted at about 15-20 stations twice annually (April and August) at 15-20 stations per lake to collect data from both cold and warm water conditions. All sampling was conducted using trace-metal free protocols using a sampling rosette equipped with 12 Teflon-lined Niskin. Water samples were collected at predetermined depths: mid-epilimnion, mid-thermocline, deep chlorophyll layer, mid-hypolimnion, and about 2 meters above the bottom. Seston samples were collected from the top 20 meters using plankton nets, while bottom sediments and benthos samples were acquired using a ponar sampler. Water, biota, and sediment samples were all analyzed for Hg and MeHg concentration at the USGS Mercury Research Laboratory in Middleton, Wisconsin. Several important trends are apparent from the water column samples. First, most stations reveal a strong top-to-bottom declining trend total Hg concentration, underscoring the importance of atmospheric deposition to the Great Lakes. Methylmercury profiles, show maximal concentrations at the thermocline or deep chlorophyll layer, suggesting in situ water-column MeHg production. Calculations suggest this in-lake MeHg source is similar in magnitude to tributary loading of MeHg, which heretofore was thought to be the dominant MeHg source. Aqueous total Hg results also suggest that

  2. The formation of glacial lakes in Austria since the Little Ice Age

    NASA Astrophysics Data System (ADS)

    Buckel, Johannes; Otto, Jan-Christoph; Prasicek, Günther

    2017-04-01

    The global temperature rise in the 20th and 21st centuries led to massive deglaciation and the formation of numerous glacial lakes. Glacier lake development and lifetime are controlled by the complex interplay of climate and geological boundary conditions, geomorphological process activity and glacier dynamics. New lakes in formerly glaciated alpine areas significantly contribute to changing geomorphologic, hydrologic and ecologic conditions at high altitudes. Here we present an inventory of lakes in the Austrian Alps. The inventory is a central part of the project FUTURELAKES that aims at understanding and modelling the development of glacier lakes in Austria. We intersect glacier lake locations with glacier inventory data to understand how deglaciation controls lake evolution. The timing of lake formation is reconstructed by comparing emerged lake area with vanished glacier area at five points in time from Little Ice Age (LIA) to 2014 - the longest time period covered by a glacier lake inventory. We discuss lake formation with respect to temperature records at high-alpine climate stations in the study area. The lake inventory contains 1389 mapped lakes with a minimum size of 1000 m2 covering an area of more than 17 km2. Lakes are classified by the damming mechanisms: (a) glacial debris dammed (49.5%), (b) bedrock dammed (49%), (c) glacier ice dammed (0.4%), and (d) debris dammed (1.1%). In Austria, 243 lakes above 1700 m have formed since LIA. Both the total number of glacial lakes and total lake area increased exponentially from LIA to 2014, while glacier area shrunk correspondingly. The number of new lakes per year grew from 0.6 (±0.1, LIA-1920) to 5.8 (2006-2014) and new lake area per year increased from 6,877 ± 513 m2 (LIA-1920) to 74,129 m2 (2006-2014). This development can be linked to rising air temperatures in the Austrian Alps which show an accelerated increase since the 1980s.

  3. Frost resistance in alpine woody plants

    PubMed Central

    Neuner, Gilbert

    2014-01-01

    This report provides a brief review of key findings related to frost resistance in alpine woody plant species, summarizes data on their frost resistance, highlights the importance of freeze avoidance mechanisms, and indicates areas of future research. Freezing temperatures are possible throughout the whole growing period in the alpine life zone. Frost severity, comprised of both intensity and duration, becomes greater with increasing elevation and, there is also a greater probability, that small statured woody plants, may be insulated by snow cover. Several frost survival mechanisms have evolved in woody alpine plants in response to these environmental conditions. Examples of tolerance to extracellular freezing and freeze dehydration, life cycles that allow species to escape frost, and freeze avoidance mechanisms can all be found. Despite their specific adaption to the alpine environment, frost damage can occur in spring, while all alpine woody plants have a low risk of frost damage in winter. Experimental evidence indicates that premature deacclimation in Pinus cembra in the spring, and a limited ability of many species of alpine woody shrubs to rapidly reacclimate when they lose snow cover, resulting in reduced levels of frost resistance in the spring, may be particularly critical under the projected changes in climate. In this review, frost resistance and specific frost survival mechanisms of different organs (leaves, stems, vegetative and reproductive over-wintering buds, flowers, and fruits) and tissues are compared. The seasonal dynamics of frost resistance of leaves of trees, as opposed to woody shrubs, is also discussed. The ability of some tissues and organs to avoid freezing by supercooling, as visualized by high resolution infrared thermography, are also provided. Collectively, the report provides a review of the complex and diverse ways that woody plants survive in the frost dominated environment of the alpine life zone. PMID:25520725

  4. Frost resistance in alpine woody plants.

    PubMed

    Neuner, Gilbert

    2014-01-01

    This report provides a brief review of key findings related to frost resistance in alpine woody plant species, summarizes data on their frost resistance, highlights the importance of freeze avoidance mechanisms, and indicates areas of future research. Freezing temperatures are possible throughout the whole growing period in the alpine life zone. Frost severity, comprised of both intensity and duration, becomes greater with increasing elevation and, there is also a greater probability, that small statured woody plants, may be insulated by snow cover. Several frost survival mechanisms have evolved in woody alpine plants in response to these environmental conditions. Examples of tolerance to extracellular freezing and freeze dehydration, life cycles that allow species to escape frost, and freeze avoidance mechanisms can all be found. Despite their specific adaption to the alpine environment, frost damage can occur in spring, while all alpine woody plants have a low risk of frost damage in winter. Experimental evidence indicates that premature deacclimation in Pinus cembra in the spring, and a limited ability of many species of alpine woody shrubs to rapidly reacclimate when they lose snow cover, resulting in reduced levels of frost resistance in the spring, may be particularly critical under the projected changes in climate. In this review, frost resistance and specific frost survival mechanisms of different organs (leaves, stems, vegetative and reproductive over-wintering buds, flowers, and fruits) and tissues are compared. The seasonal dynamics of frost resistance of leaves of trees, as opposed to woody shrubs, is also discussed. The ability of some tissues and organs to avoid freezing by supercooling, as visualized by high resolution infrared thermography, are also provided. Collectively, the report provides a review of the complex and diverse ways that woody plants survive in the frost dominated environment of the alpine life zone.

  5. Differential exposure of alpine ospreys to mercury: melting glaciers, hydrology or deposition patterns?

    PubMed

    Guigueno, Mélanie F; Elliott, Kyle H; Levac, Joshua; Wayland, Mark; Elliott, John E

    2012-04-01

    Mercury (Hg) is a global contaminant impacting even remote environments. In alpine watersheds, glacial meltwater is a source of Hg, which accumulated in glaciers during the 1960-1980 cooling cycle. The considerable variation observed for Hg exposure of alpine animals in proximal watersheds could result from differences among those watersheds in Hg loading from glacial meltwater. Alternatively, variation may be the result of hydrology, atmospheric Hg deposition patterns, or food web characteristics. To examine those possibilities, we measured Hg in ospreys (Pandion haliaetus), apex predators in 15 watersheds in western Canada. Mercury levels in feathers of nestlings increased with increasing modeled atmospheric deposition rates and decreased with lake size. In eggs mercury decreased with δ(13)C, an indicator of food web structure, and with pH and elevation. Thus, Hg levels in chicks were strongly associated with local patterns relevant when the chicks were growing (e.g. the period post-snow melt: Hg deposition, lake size) while Hg levels in eggs were weakly associated with local patterns relevant during the snow melt (elevation, δ(13)C), with the remainder of the Hg variation in eggs determined by other factors such as possible Hg accumulation by the adult elsewhere. Modeled atmospheric deposition from prevailing upwind locations including Asia, followed by runoff into small lakes, were related to Hg patterns in osprey, with little apparent role for recent melting of glaciers. Our study highlights the importance of physical patterns to the environmental chemistry of top predators.

  6. Lacustrine Paleoseismometers Reveal Spatial and Temporal Patterns of Rupture during the Last Ten Large Earthquakes on the Alpine Fault, New Zealand.

    NASA Astrophysics Data System (ADS)

    Howarth, J. D.; Fitzsimons, S.; Langridge, R.; Clark, K.; Cochran, U. A.; Norris, R. J.; Jacobsen, G. E.

    2014-12-01

    The rarity of long, well-dated paleoseismic records from sites along plate boundary transform faults is a major constraint on the development and evaluation of conceptual models of fault rupture behaviour. This is the case for the 800 km long, high slip rate (27±5 mm yr-1), dextral strike-slip Alpine Fault at the boundary between the Pacific and Australian plates in southern New Zealand. We use lacustrine paleoseismology to evaluate the hypothesis that the Alpine Fault exhibits self-similar behaviour, that is, the fault always produces earthquakes at or near a maximum magnitude of Mw8. The hypothesis is tested using reconstructions of high intensity shaking from five lakes situated along 240 km of the Alpine Fault's Central section. Sedimentological investigation of lake cores shows that high intensity shaking events are recorded in the lake sediments as turbidites formed by subaqueous slumping. These turbidites are overlain by terrigenous sediment from co- and post-seismic landsliding on hillslopes in the lakes' mountainous catchments. Chronologies derived from Bayesian modelling of AMS 14C dates on terrestrial leaf macrofossils precisely constrain the timing of earthquakes at the lake sites, facilitating along-strike correlation. Shaking events correlate between the sites and with known ruptures of the Alpine Fault, confirming the seismic origin of the deposits and allowing thresholds of shaking intensity for deposit formation to be determined using isoseismal modelling. Modelled shaking intensities for the last two Alpine Fault earthquakes show that subaqueous slumping occurs when shaking intensities exceed Modified Mercalli scale (MM) VI-VII, and that increased fluvial sediment fluxes from earthquake-induced landslides occur when shaking intensities exceed MM IX. The record of synchronous MM IX shaking at the lake sites provides first order constraint on the rupture length of the last ten earthquakes on the central Alpine Fault. Rupture scenarios for these

  7. An integrated lake geographical information system on the third pole

    NASA Astrophysics Data System (ADS)

    Gao, Y.; Lu, A.

    2016-12-01

    Alpine lakes on the Third Pole (TP) have been used as an indicator for knowing hydrologic process, evaluating water resources and understanding climate change. However, the main driving forces and climate-driven mechanisms of lake variations still remain debate. One of a reason that limits these researches is lack of the understanding of the lake hydrological characteristics. In this study, we created a lake inventory on TP, and for the first time, we established a comprehensive hydrological network for each lake mainly based on 246 scenes Landsat series images, 236 Chinese topographic maps, and SRTM DEM. According to the lake's location in the hydrological network, the lakes can be classified as closed lake, upstream lake or outflow lake. The closed lake has only inlet with no outlet. Water in the closed lake does not leave the basin by the surface runoff. The upstream lake has inlet and outlet, and the runoff will finally flow into a closed lake. The outflow lake has inlet and outlet, while the runoff will join into rivers and may eventually join into the ocean. These three kinds of lakes have different drainage modes, so their intensity and forms affected by climate change may not the same. It's necessary to distinguish them and consider them separately. The results show that there are 396 closed lakes, 472 supplying lakes and 312 outflow lakes on TP in 2010, with the area of 35,498.2 km2, 7,301.6km2, and 3,373.6 km2, respectively. Meanwhile, we determined the relationship between lakes and their supplying glaciers. What's more, an integrated lake geographical information system on the third pole has been build. This system realizes the information visualization and mainly includes two functions. If you click any lake, you can know the catchment of this lake, the streams how the runoff inputs a lake, and how a lake is connected to another lake or river. And you also can know if there are glaciers supply the lake or not, and the location and area of these

  8. Lake Life.

    ERIC Educational Resources Information Center

    Ohrn, Deborah Gore, Ed.

    1993-01-01

    This quarterly publication of the State Historical Society of Iowa features articles and activities for elementary school students. This summer issue focuses on the topic of lake life. The issue includes the following features: (1) "Where the Lakes Are Map"; (2) "Letter from the Lake"; (3) "Lake People"; (4)…

  9. Erosion by an Alpine glacier

    NASA Astrophysics Data System (ADS)

    Herman, Frédéric; Beyssac, Olivier; Lane, Stuart; Brughelli, Mattia; Leprince, Sebastien; Brun, Fanny

    2015-04-01

    Most mountain ranges on Earth owe their morphology to the action of glaciers and icecaps over the last few million years. Our current understanding of how glaciers have modified mountainous landforms has mainly been driven through landscape evolution models. These have included an array of erosion laws and mainly progressed through the implementation of various levels of sophistication regarding ice dynamics, subglacial hydrology or thermodynamics of water flow. However, the complex nature of the erosion processes involved and the difficulty of directly examining the ice-bedrock interface of contemporary glaciers has precluded the establishment of a prevailing erosion theory. Here we quantify the spatial variations in ice sliding velocity and erosion rate of a fast-flowing Alpine glacier in New Zealand during a 5-month period. By combining high resolution 3D measurements of surface velocity from optical satellite imagery with the quantification of both the production and provenance of sediments by the glacier, we show that erosion rates are proportional to sliding velocity raised to a power of about two. This result is consistent with abrasion theory. Given that the ice sliding velocity is a nonlinear function of ice thickness and ice surface slope, the response of glacial erosion to precipitation changes is highly nonlinear. Finally, our ability to constrain the glacial abrasion law present opportunities to further examine the interaction between glaciation and mountain evolution.

  10. Modelling photochemistry in alpine valleys

    NASA Astrophysics Data System (ADS)

    Brulfert, G.; Chemel, C.; Chaxel, E.; Chollet, J. P.

    2005-03-01

    Road traffic is a serious problem in the Chamonix Valley, France: traffic, noise and above all air pollution worry the inhabitants. The big fire in the Mont-Blanc tunnel made it possible, in the framework of the POVA project (POllution in Alpine Valleys), to undertake measurement campaigns with and without heavy-vehicle traffic through the valley, towards Italy (before and after the tunnel re-opening). Modelling in POVA should make it possible to explain the processes leading to episodes of atmospheric pollution, both in summer and in winter. Atmospheric prediction model ARPS 4.5.2 (Advanced Regional Prediction System), developed at the CAPS (Center for Analysis and Prediction of Storms) of the University of Oklahoma, enables to resolve the dynamics above a complex terrain. This model is coupled to the TAPOM 1.5.2 atmospheric chemistry (Transport and Air POllution Model) code developed at the Air and Soil Pollution Laboratory of the Ecole Polytechnique Fédérale de Lausanne. The numerical codes MM5 and CHIMERE are used to compute large scale boundary forcing. Using 300-m grid cells to calculate the dynamics and the reactive chemistry makes possible to accurately represent the dynamics in the valley (slope and valley winds) and to process chemistry at fine scale. Validation of campaign days allows to study chemistry indicators in the valley. NOy according to O3 reduction demonstrates a VOC controlled regime, different from the NOx controlled regime expected and observed in the nearby city of Grenoble.

  11. Impacts after four years of experimental trampling on alpine/sub-alpine environments in western Tasmania.

    PubMed

    Whinam, Jennie; Chilcott, Nicole M

    2003-04-01

    Experimental trials were undertaken over four years to assess the impact of recreational trampling in undisturbed alpine and sub-alpine vegetation communities in the Western Arthur Range, western Tasmania. Data on 'pad' formation due to human trampling were collected using vegetation cover assessments, biomass estimates and detailed cross-sectional surface profiles. In sub-alpine buttongrass and alpine herbfield, prolonged and sustained damage may occur after 100 passes by walkers. The environmental threshold of the flat alpine herbfield site was breached after 200 passes. Plant morphology was one determinant of resistance and resilience, with upright woody shrubs and tall tussock graminoids most vulnerable to sustained trampling damage. Cushions are susceptible to trampling impacts at 500 passes. Loss of vegetation cover peaks 6-12 months after trampling. Our results show that pads formed with as few as 30-100 passes per annum and tracks form at between 100 and 500 passes per annum. Two years after the cessation of trampling, there is some small recovery in vegetation cover after 30 and 100 passes per annum applied for three years, but no evidence of recovery at the 500 pass treatments. The low trampling threshold and slow recovery rates in western Tasmania suggest that concentrating walkers on a minimal number of sites may be the best management option for these untracked alpine and sub-alpine environments.

  12. 77 FR 48950 - Alpine County Resource Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-15

    ... Forest Service Alpine County Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The Alpine County Resource Adivisory Committee will meet in Markleeville, CA. The... held at the Alpine Early Learning Center, 100 Foothill Road, Markleeville, CA. Written comments may...

  13. Larch dwarf mistletoe not found on alpine larch

    Treesearch

    Robert L. Mathiasen; Brian W. Geils; Clinton E. Carlson; Frank G. Hawksworth

    1995-01-01

    Reports of larch dwarf mistletoe parasitizing alpine larch are based on two collections of this host/parasite combination made by J.R. Weir in Montana during the early 1900s. Examination of host material from these collections indicates that the host is western larch, not alpine larch as previously reported. Attempts to locate larch dwarf mistletoe on alpine larch were...

  14. Encroaching forests decouple alpine butterfly population dynamics.

    PubMed

    Roland, Jens; Matter, Stephen F

    2007-08-21

    Over the past 50 years, the rising tree line along Jumpingpound Ridge in the Rocky Mountains of Alberta, Canada, has reduced the area of alpine meadows and isolated populations that reside within them. By analyzing an 11-year data set of butterfly population sizes for 17 subpopulations along the ridge, we show that forest habitat separating alpine meadows decouples the dynamics of populations of the alpine butterfly Parnassius smintheus. Although the distance between populations is often negatively correlated with synchrony of dynamics, here we show that distance through forest, not Euclidean distance, determines the degree of synchrony. This effect is consistent with previous results demonstrating that encroaching forest reduces dispersal among populations and reduces gene flow. Decoupling dynamics produces more smaller independent populations, each with greater risk of local extinction, but decoupling may produce a lower risk of regional extinction in this capricious environment.

  15. Multilocus Analyses Reveal Postglacial Demographic Shrinkage of Juniperus morrisonicola (Cupressaceae), a Dominant Alpine Species in Taiwan.

    PubMed

    Huang, Chi-Chun; Hsu, Tsai-Wen; Wang, Hao-Ven; Liu, Zin-Huang; Chen, Yi-Yen; Chiu, Chi-Te; Huang, Chao-Li; Hung, Kuo-Hsiang; Chiang, Tzen-Yuh

    2016-01-01

    Postglacial climate changes alter geographical distributions and diversity of species. Such ongoing changes often force species to migrate along the latitude/altitude. Altitudinal gradients represent assemblage of environmental, especially climatic, variable factors that influence the plant distributions. Global warming that triggered upward migrations has therefore impacted the alpine plants on an island. In this study, we examined the genetic structure of Juniperus morrisonicola, a dominant alpine species in Taiwan, and inferred historical, demographic dynamics based on multilocus analyses. Lower levels of genetic diversity in north indicated that populations at higher latitudes were vulnerable to climate change, possibly related to historical alpine glaciers. Neither organellar DNA nor nuclear genes displayed geographical subdivisions, indicating that populations were likely interconnected before migrating upward to isolated mountain peaks, providing low possibilities of seed/pollen dispersal across mountain ranges. Bayesian skyline plots suggested steady population growth of J. morrisonicola followed by recent demographic contraction. In contrast, most lower-elevation plants experienced recent demographic expansion as a result of global warming. The endemic alpine conifer may have experienced dramatic climate changes over the alternation of glacial and interglacial periods, as indicated by a trend showing decreasing genetic diversity with the altitudinal gradient, plus a fact of upward migration.

  16. Nitrogen Critical Loads for an Alpine Meadow Ecosystem on the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Zong, Ning; Shi, Peili; Song, Minghua; Zhang, Xianzhou; Jiang, Jing; Chai, Xi

    2016-03-01

    Increasing atmospheric nitrogen (N) deposition has the potential to alter plant diversity and thus the function and stability of terrestrial ecosystems. N-limited alpine ecosystems are expected to be particularly susceptible to increasing N deposition. However, little is known about the critical loads and saturation thresholds of ecosystem responses to increasing N deposition on the Tibetan Plateau, despite its importance to ecosystem management. To evaluate the N critical loads and N saturation thresholds in an alpine ecosystem, in 2010, we treated an alpine meadow with five levels of N addition (0, 10, 20, 40, and 80 kg N ha-1 year-1) and characterized plant and soil responses. The results showed that plant species richness and diversity index did not statistically vary with N addition treatments, but they both changed with years. N addition affected plant cover and aboveground productivity, especially for grasses, and soil chemical features. The N critical loads and saturation thresholds, in terms of plant cover and biomass change at the community level, were 8.8-12.7 and 50 kg N ha-1 year-1 (including the ambient N deposition rate), respectively. However, pronounced changes in soil inorganic N and net N mineralization occurred under the 20 and 40 kg N ha-1 year-1 treatments. Our results indicate that plant community cover and biomass are more sensitive than soil to increasing N inputs. The plant community composition in alpine ecosystems on the Qinghai-Tibetan Plateau may change under increasing N deposition in the future.

  17. Multilocus Analyses Reveal Postglacial Demographic Shrinkage of Juniperus morrisonicola (Cupressaceae), a Dominant Alpine Species in Taiwan

    PubMed Central

    Chiu, Chi-Te; Huang, Chao-Li; Hung, Kuo-Hsiang; Chiang, Tzen-Yuh

    2016-01-01

    Postglacial climate changes alter geographical distributions and diversity of species. Such ongoing changes often force species to migrate along the latitude/altitude. Altitudinal gradients represent assemblage of environmental, especially climatic, variable factors that influence the plant distributions. Global warming that triggered upward migrations has therefore impacted the alpine plants on an island. In this study, we examined the genetic structure of Juniperus morrisonicola, a dominant alpine species in Taiwan, and inferred historical, demographic dynamics based on multilocus analyses. Lower levels of genetic diversity in north indicated that populations at higher latitudes were vulnerable to climate change, possibly related to historical alpine glaciers. Neither organellar DNA nor nuclear genes displayed geographical subdivisions, indicating that populations were likely interconnected before migrating upward to isolated mountain peaks, providing low possibilities of seed/pollen dispersal across mountain ranges. Bayesian skyline plots suggested steady population growth of J. morrisonicola followed by recent demographic contraction. In contrast, most lower-elevation plants experienced recent demographic expansion as a result of global warming. The endemic alpine conifer may have experienced dramatic climate changes over the alternation of glacial and interglacial periods, as indicated by a trend showing decreasing genetic diversity with the altitudinal gradient, plus a fact of upward migration. PMID:27561108

  18. Modelling photochemistry in alpine valleys

    NASA Astrophysics Data System (ADS)

    Brulfert, G.; Chemel, C.; Chaxel, E.; Chollet, J. P.

    2005-09-01

    Road traffic is a serious problem in the Chamonix Valley, France: traffic, noise and above all air pollution worry the inhabitants. The big fire in the Mont-Blanc tunnel made it possible, in the framework of the POVA project (POllution in Alpine Valleys), to undertake measurement campaigns with and without heavy-vehicle traffic through the Chamonix and Maurienne valleys, towards Italy (before and after the tunnel re-opening). Modelling is one of the aspects of POVA and should make it possible to explain the processes leading to episodes of atmospheric pollution, both in summer and in winter. Atmospheric prediction model ARPS 4.5.2 (Advanced Regional Prediction System), developed at the CAPS (Center for Analysis and Prediction of Storms) of the University of Oklahoma, enables to resolve the dynamics above a complex terrain. This model is coupled to the TAPOM 1.5.2 atmospheric chemistry (Transport and Air POllution Model) code developed at the Air and Soil Pollution Laboratory of the Ecole Polytechnique Fédérale de Lausanne. The numerical codes MM5 and CHIMERE are used to compute large scale boundary forcing.

    This paper focuses on modelling Chamonix valley using 300-m grid cells to calculate the dynamics and the reactive chemistry which makes possible to accurately represent the dynamics in the Chamonix valley (slope and valley winds) and to process chemistry at fine scale. The summer 2003 intensive campaign was used to validate the model and to study chemistry. NOy according to O3 reduction demonstrates a VOC controlled regime, different from the NOx controlled regime expected and observed in the nearby city of Grenoble.

  19. The need for ecological monitoring of freshwaters in a changing world: a case study of Lakes Annecy, Bourget, and Geneva.

    PubMed

    Jacquet, Stéphan; Domaizon, Isabelle; Anneville, Orlane

    2014-06-01

    Lakes Annecy, Bourget, and Geneva are large, deep carbonated peri-alpine lakes in eastern France. They are located in the same ecoregion but have been subject to differing degrees of anthropogenic pressure over the past decades. A comparative analysis of these ecosystems can therefore provide valuable information on how the lakes have responded to changes in phosphorus runoff, fish management practices, and global warming. Each of these lakes has undergone a restoration process, and changes in water quality and trophic state, as measured using parameters like transparency, chlorophyll a, nutrient concentrations, and phytoplankton biomass and structure, can be used to evaluate efforts made to preserve these ecosystems. Our results reveal that (1) peri-alpine lakes are exemplary cases of restoration in the world where freshwater eutrophication is on the increase, and (2) efforts must be maintained because of the new context of climate change, the effects of which on the quality and the ecological functioning of lakes are still poorly understood.

  20. Attribution of sources to metal accumulation in an alpine tarn, the Snowy Mountains, Australia.

    PubMed

    Stromsoe, Nicola; Callow, J Nikolaus; McGowan, Hamish A; Marx, Samuel K

    2013-10-01

    This study analyses 1800 years of heavy metal accumulation in a remote alpine lake experiencing long-range atmospheric contamination and additional inputs of Ag from cloud seeding. In comparison to previous work undertaken on peats, lake sediments show limited post-industrial metal enrichment with enrichment factors of Ag: 1.3, Pb: 1.3, Zn: 1.1, Cu: 1.2 compared to Ag: 2.2, Pb: 3.3, Zn: 2.1, Cu: 4.1 for peat. We show this to be the result of substantial fluvial lithogenic flux of metals (92-97% of total metal flux) to the lake. Total annual metal flux to the lake ranges from: Ag: 4-12 ng/cm(2)/yr to Zn: 3 383-11 313 ng/cm(2)/yr. As a result, any contribution of cloud seeding to additional enrichment of Ag in lake sediments is considered negligible. Results show that metal enrichment is not necessarily ubiquitous through a landscape. This has implications for predicting the impacts of atmospheric metal pollution to complex environmental systems. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Lake Tahoe

    EPA Pesticide Factsheets

    Information on the Lake Tahoe watershed, EPA's protection efforts, water quality issues, effects of climate change, Lake Tahoe Total Maximum Daily Load (TMDL), EPA-sponsored projects, list of partner agencies.

  2. Soil Survey: Fraser Alpine Area, Colorado

    Treesearch

    J. L. Retzer

    1962-01-01

    The Fraser Alpine Area is a rough, mountainous area that lies approximately 50 miles west of Denver, Colo., and covers approximately 134 square miles. About seven-eighths of it is above timberline, and all is within the boundaries of Arapaho National Forest, U.S. Forest Service. The land in the Area is not suitable for cultivation and has never been farmed.

  3. Outdoor Education Project Report, Camp Alpine.

    ERIC Educational Resources Information Center

    Palmer, N. J.

    A report is given of Project Alpine, two summer pilot programs in outdoor education sponsored by the Mesa Public Schools of Arizona. The report outlines the duties of camp personnel and includes an instruction sheet used by camp counselors. Various activities held for the campers (boys and girls from both upper elementary and secondary grades) are…

  4. Monitoring Alpine Transportation Infrastructures Using Space Techniues

    NASA Astrophysics Data System (ADS)

    Strozzi, Tazio; Caduff, Rafael; Wegmuller, Urs; Brandstaetter, Michael; Kuhtreiber, Norbert

    2013-12-01

    Integration of satellite SAR interferometry, terrestrial radar interferometry and GPS is considered for the monitoring of ground motion along Alpine transportation infrastructures. We present results related to large-scale surveys in Switzerland along the Gotthard railway with satellite SAR interferometry and to a local monitoring of an active rockfall above the Pyhrn motorway in Austria using terrestrial radar interferometry and GPS.

  5. An inventory of glacial lakes in the Austrian Alps

    NASA Astrophysics Data System (ADS)

    Buckel, Johannes; Otto, Jan-Christoph; Keuschnig, Markus; Götz, Joachim

    2016-04-01

    The formation of lakes is one of the consequences of glacier retreat due to climate change in mountain areas. Numerous lakes have formed in the past few decades in many mountain regions around the globe. Some of these lakes came into focus due to catastrophic hazard events especially in the Himalayas and the Andes. Glacial lake development and lifetime is controlled by the complex interplay of glacier dynamics, geomorphological process activity and geological boundary conditions. Besides the hazard potential new lakes in formerly glaciated areas will significantly contribute to a new landscape setting and to changing geomorphologic, hydrologic and ecologic conditions at higher alpine altitudes. We present an inventory of high alpine lakes in the Austrian Alps located above an altitude of 1700 m asl. Most of these lakes are assumed to be of glacial origin, but other causes for development, like mass movements are considered as well. The inventory is a central part of the project FUTURELAKES that aims at modelling the potential development of glacial lakes in Austria (we refer to the presentation by Helfricht et al. during the conference for more details on the modelling part). Lake inventory data will serve as one basis for model validation since modelling is performed on different time steps using glacier inventory data. The purpose of the lake inventory is to get new insights into boundary conditions for lake formation and evolution by analysing existing lake settings. Based on these information the project seeks to establish a model of lake sedimentation after glacier retreat in order to assess the potential lifetime of the new lakes in Austria. Lakes with a minimum size of 1000 m² were mapped using multiple aerial imagery sources. The dataset contains information on location, geometry, dam type, and status of sedimentation for each lake. Additionally, various geologic, geomorphic and morphometric parameters describe the lake catchments. Lake data is related to

  6. Modeling glacier beds in the Austrian Alps: How many lakes will form in future?

    NASA Astrophysics Data System (ADS)

    Koehler, Dominik; Geilhausen, Martin; Linsbauer, Andreas

    2014-05-01

    Glacial retreat exposes landscapes with relief characteristics greatly differing from the former ice covered surfaces. If glacial retreat exposes natural basins capable of forming proglacial lakes, then the downstream hydrologic and geomorphic systems in such catchments will be significantly altered due to discharge modifications, sediment trapping, decoupling effects and long term sediment storage (e.g. Geilhausen et al. 2013). Further implications are related to hydropower management, tourism and natural hazards. Consequently, sound knowledge of present day glacier beds ("proglacial zones of tomorrow") and in particular the total number, locations and characteristics of overdeepenings are of importance. For Austria, however, this important information about significant future changes of high alpine regions is yet missing. An interdisciplinary research project is currently in preparation to close this gap. This paper presents results of a pilot study. We used a novel GIS-based approach (GlabTop, cf. Linsbauer et al. 2012) to compute approximate glacier beds in the Austrian Alps. GlabTop ('Glacier bed Topography') is based on an empirical relation between average basal shear stress and elevation range of individual glaciers and makes use of digital elevation models (DEM), glacier outlines and branch lines (i.e. a set of lines covering all important glacier branches). DEMs and glacier outlines were derived from the Austrian glacier inventory (1998) and branch lines were manually digitized. The inventory includes 911 glaciers of which 876 (96%) were considered and 35 were excluded due to size restrictions (< 0.01 km²) or insufficient DEM coverage. We found 165 overdeepenings (> 0.01 km²) with the potential of forming proglacial lakes when glacier retreat reveals the bed. The total area and volume of all overdeepenings is approx. 10 km² and 236 Mio m³ respectively and 33 lakes will be larger than 1 km³. A total glacier volume of 16 ± 5 km³ with an average ice

  7. Riparian vegetation in the alpine connectome: Terrestrial-aquatic and terrestrial-terrestrial interactions.

    PubMed

    Zaharescu, Dragos G; Palanca-Soler, Antonio; Hooda, Peter S; Tanase, Catalin; Burghelea, Carmen I; Lester, Richard N

    2017-12-01

    Alpine regions are under increased attention worldwide for their critical role in early biogeochemical cycles, their high sensitivity to environmental change, and as repositories of natural resources of high quality. Their riparian ecosystems, at the interface between aquatic and terrestrial environments, play important geochemical functions in the watershed and are biodiversity hotspots, despite a harsh climate and topographic setting. With climate change rapidly affecting the alpine biome, we still lack a comprehensive understanding of the extent of interactions between riparian surface, lake and catchment environments. A total of 189 glacial - origin lakes were surveyed in the Central Pyrenees to test how key elements of the lake and terrestrial environments interact at different scales to shape riparian plant composition. Secondly, we evaluated how underlying ecotope features drive the formation of natural communities potentially sensitive to environmental change and assessed their habitat distribution. At the macroscale, vegetation composition responded to pan-climatic gradients altitude and latitude, which captured in a narrow geographic area the transition between large European climatic zones. Hydrodynamics was the main catchment-scale factor connecting riparian vegetation with major water fluxes, followed by topography and geomorphology. Lake sediment Mg and Pb, and water Mn and Fe contents reflected local influences from mafic bedrock and soil water saturation. Community analysis identified four keystone ecosystems: (i) damp ecotone, (ii) snow bed-silicate bedrock, (iii) wet heath, and (iv) calcareous substrate. These communities and their connections with ecotope elements could be at risk from a number of environmental change factors including warmer seasons, snow line and lowland species advancement, increased nutrient/metal input and water level fluctuations. The results imply important natural terrestrial-aquatic linkages in the riparian environment

  8. Phosphorus Fluxes in the Beartooth Mountains: a Record of Detailed P Geochemistry from Island Lake

    NASA Astrophysics Data System (ADS)

    McLennan, D. A.; Latimer, J. C.; Williams, T. M.; Brown, S. R.; Stone, J.; McCune, A.

    2014-12-01

    Island Lake, situated within the Precambrian rocks of the Beartooth Mountains that run along the border of Wyoming and Montana, is a glacial lake located at the tree line with an elevation of 3048 m, a maximum water depth of 33 m, a catchment area of 11.7 km2, and a lake area of 0.61 km2. Like many alpine lakes, Island Lake is highly transparent with a deep chlorophyll maximum. Alpine settings may be more susceptible to small perturbations in climate and thus good sensors for investigating climate change. It is hypothesized that this low-nutrient alpine lake has shifted from a nitrogen-limiting system to one that is limited by phosphorus (P) availability. In summer 2013, a 1.54-m sediment core was collected for diatom and geochemical analyses, including P and metals. Detailed P geochemistry can be used to elucidate landscape evolution and P burial fluxes can provide insight into biogeochemical cycling over time. Changes in landscape due to fire, zonal shifts in vegetation, and shifts in climatological factors such as precipitation can impact the bioavailability of P entering the lake as well as burial fluxes. The sediment record will clarify the role of P in lake biogeochemical cycling at Island Lake through the Holocene. Planktonic diatom abundances have been used to reconstruct a history of Holocene lake stratification, and ongoing detailed P geochemistry using a sequential extraction technique (SEDEX) will be used to identify the role of P fluxes on productivity within the lake. SEDEX can differentiate between P associated with oxides/oxyhydroxides, mineral fractions, and organic matter, and the relative changes in these fractions provide insight into landscape dynamics. Coupled with diatom proxies, P geochemistry can also provide a better understanding of biogeochemical cycling within the lake. This multiproxy approach should provide insight into the responses within the catchment to environmental changes over the Holocene.

  9. Comparison of bacterial growth in response to photodegraded terrestrial chromophoric dissolved organic matter in two lakes.

    PubMed

    Su, Yaling; Hu, En; Feng, Muhua; Zhang, Yongdong; Chen, Feizhou; Liu, Zhengwen

    2017-02-01

    Terrestrial chromophoric dissolved organic matter (CDOM) could subsidize lake food webs. Trophic state and altitude have a pronounced influence on the CDOM concentration and composition of a lake. The impact of future changes in solar radiation on high-altitude lakes is particularly alarming because these aquatic ecosystems experience the most pronounced radiation variation worldwide. Photodegradation experiments were conducted on terrestrial CDOM samples from oligotrophic alpine Lake Tiancai and low-altitude eutrophic Lake Xiaohu to investigate the response of bacterial growth to photodegraded CDOM. During the photo-irradiation process, the fluorescent CDOM intensity evidently decreased in an inflowing stream of Lake Tiancai, with the predominance of humic-like fluorescence. By contrast, minimal changes were observed in the riverine CDOM of Lake Xiaohu, with the predominance of protein-like fluorescence. The kinetic constants of photodegradation indicated that the degradation rate of terrestrial (soil) humic acid in Lake Tiancai was significantly higher than that in Lake Xiaohu (p<0.001). Soil humic and fulvic acids irradiated in the simulated experiment were applied to incubated bacteria. The specific growth rate of bacteria incubated with soil humic substances was significantly higher in Lake Tiancai than in Lake Xiaohu (p<0.05). Furthermore, the utilizing rate of dissolved oxygen (DO) confirmed that the DO consumption by bacteria incubated with terrestrial CDOM in Lake Tiancai was significantly greater than that in Lake Xiaohu (p<0.05). In summary, the exposure of terrestrial CDOM to light significantly enhances its availability to heterotrophic bacteria in Lake Tiancai, an oligotrophic alpine lake, which is of importance in understanding bacterial growth in response to photodegraded terrestrial CDOM for different types of lakes.

  10. Lake Powell

    Atmospheric Science Data Center

    2014-05-15

    article title:  Lake Powell     View Larger Image ... format (14.42 mb)   This true-color image over Lake Powell was acquired by Multi-angle Imaging SpectroRadiometer (MISR) in late March 2000. Lake Powell was formed with the construction of the Glen Canyon Dam in 1963, on ...

  11. Planetary Lake Lander - A Robotic Sentinel to Monitor a Remote Lake

    NASA Technical Reports Server (NTRS)

    Pedersen, Liam; Smith, Trey; Lee, Susan; Cabrol, Nathalie; Rose, Kevin

    2012-01-01

    The Planetary Lake Lander Project is studying the impact of rapid deglaciation at a high altitude alpine lake in the Andes, where disrupted environmental, physical, chemical, and biological cycles result in newly emerging natural patterns. The solar powered Lake Lander robot is designed to monitor the lake system and characterize both baseline characteristics and impacts of disturbance events such as storms and landslides. Lake Lander must use an onboard adaptive science-on-the-fly approach to return relevant data about these events to mission control without exceeding limited energy and bandwidth resources. Lake Lander carries weather sensors, cameras and a sonde that is winched up and down the water column to monitor temperature, dissolved oxygen, turbidity and other water quality parameters. Data from Lake Lander is returned via satellite and distributed to an international team of scientists via web-based ground data systems. Here, we describe the Lake Lander Project scientific goals, hardware design, ground data systems, and preliminary data from 2011. The adaptive science-on-the-fly system will be described in future papers.

  12. Chemotype diversity in Planktothrix rubescens (cyanobacteria) populations is correlated to lake depth.

    PubMed

    Haruštiaková, Danka; Welker, Martin

    2017-04-01

    The cyanobacterial species Planktothrix rubescens is known to preferably inhabit deep, stratified, oligo- to mesotrophic lakes. It is also known for the production of diverse bioactive peptides, including the hepatotoxic microcystins. A number of studies showed that P. rubescens populations generally consist of multiple distinct genotypes or chemotypes, respectively. In the present study, variability of chemotype diversity was analysed. Filaments of P. rubescens were isolated from water samples originating from 10 European lakes and analysed by MALDI-TOF mass spectrometry. In most of the analysed filaments multiple peptides belonging to multiple peptide classes could be detected. A resulting data matrix of 964 filaments and 37 individual peptides was subjected to correspondence analysis and K-means clustering. From the latter analysis the distribution of chemotypes among the lakes was established and diversity estimated by computing Shannon-Indices. Diversity varied strongly among lakes with the lowest diversity found in non-alpine lakes. Further, chemotype diversity was strongly correlated to the maximum depth of the sampled lakes in alpine and non-alpine lakes. The possible influence of both factors, geographic isolation and water column depth, on the observed patterns of chemotype diversity of P. rubescens populations is discussed. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  13. Temporal Changes and Altitudinal Distribution of Aerobic Anoxygenic Phototrophs in Mountain Lakes

    PubMed Central

    Čuperová, Zuzana; Holzer, Evelyn; Salka, Ivette

    2013-01-01

    Aerobic anoxygenic phototrophs (AAPs) are bacteriochlorophyll a-containing microorganisms that use organic substrates for growth but can supplement their energy requirements with light. They have been reported from various marine and limnic environments; however, their ecology remains largely unknown. Here infrared epifluorescence microscopy was used to monitor temporal changes in AAPs in the alpine lake Gossenköllesee, located in the Tyrolean Alps, Austria. AAP abundance was low (103 cells ml−1) until mid-July and reached a maximum of ∼1.3 × 105 cells ml−1 (29% of all prokaryotes) in mid-September. We compared the studied lake with other mountain lakes located across an altitudinal gradient (913 to 2,799 m above sea level). The concentration of dissolved organic carbon and water transparency seem to be the main factors influencing AAP abundance during the seasonal cycle as well as across the altitudinal gradient. While the AAP populations inhabiting the alpine lakes were composed of intensely pigmented large rods (5 to 12 μm), the lakes below the tree line were inhabited by a variety of smaller morphotypes. Analysis of pufM diversity revealed that AAPs in Gossenköllesee were almost exclusively Sphingomonadales species, which indicates that AAP communities inhabiting alpine lakes are relatively homogeneous compared to those in low-altitude lakes. PMID:23956384

  14. Variation of soil hydraulic properties with alpine grassland degradation in the eastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Pan, Tao; Hou, Shuai; Wu, Shaohong; Liu, Yujie; Liu, Yanhua; Zou, Xintong; Herzberger, Anna; Liu, Jianguo

    2017-05-01

    Ecosystems in alpine mountainous regions are vulnerable and easily disturbed by global environmental change. Alpine swamp meadow, a unique grassland type in the eastern Tibetan Plateau that provides important ecosystem services to the upstream and downstream regions of international rivers of Asia and other parts of the world, is undergoing severe degradation, which can dramatically alter soil hydraulic properties and water cycling processes. However, the effects of alpine swamp meadow degradation on soil hydraulic properties and the corresponding influencing mechanisms are still poorly understood. In this study, soil moisture content (SMC), field capacity (FC) and saturated hydraulic conductivity (Ks) together with several basic soil properties under lightly degraded (LD), moderately degraded (MD) and severely degraded (SD) alpine swamp meadow were investigated; the variations in SMC, FC and Ks with alpine swamp meadow degradation and their dominant influencing factors were analysed. The results showed that SMC and FC decreased consistently from LD to SD, while Ks decreased from LD to MD and then increased from MD to SD, following the order of LD > SD > MD. Significant differences in soil hydraulic properties between degradation degrees were found in the upper soil layers (0-20 cm), indicating that the influences of degradation were most pronounced in the topsoils. FC was positively correlated with capillary porosity, water-stable aggregates, soil organic carbon, and silt and clay content; Ks was positively correlated with non-capillary porosity (NCP). Relative to other soil properties, soil porosity is the dominant factor influencing FC and Ks. Capillary porosity explained 91.1 % of total variance in FC, and NCP explained 97.3 % of total variance in Ks. The combined effect of disappearing root activities and increasing sand content was responsible for the inconsistent patterns of NCP and Ks. Our findings suggest that alpine swamp meadow degradation

  15. A Temperate Alpine Glacier as a Reservoir of Polychlorinated Biphenyls: Model Results of Incorporation, Transport, and Release.

    PubMed

    Steinlin, Christine; Bogdal, Christian; Lüthi, Martin P; Pavlova, Pavlina A; Schwikowski, Margit; Zennegg, Markus; Schmid, Peter; Scheringer, Martin; Hungerbühler, Konrad

    2016-06-07

    In previous studies, the incorporation of polychlorinated biphenyls (PCBs) has been quantified in the accumulation areas of Alpine glaciers. Here, we introduce a model framework that quantifies mass fluxes of PCBs in glaciers and apply it to the Silvretta glacier (Switzerland). The models include PCB incorporation into the entire surface of the glacier, downhill transport with the flow of the glacier ice, and chemical fate in the glacial lake. The models are run for the years 1900-2100 and validated by comparing modeled and measured PCB concentrations in an ice core, a lake sediment core, and the glacial streamwater. The incorporation and release fluxes, as well as the storage of PCBs in the glacier increase until the 1980s and decrease thereafter. After a temporary increase in the 2000s, the future PCB release and the PCB concentrations in the glacial stream are estimated to be small but persistent throughout the 21st century. This study quantifies all relevant PCB fluxes in and from a temperate Alpine glacier over two centuries, and concludes that Alpine glaciers are a small secondary source of PCBs, but that the aftermath of environmental pollution by persistent and toxic chemicals can endure for decades.

  16. Climate Change Increasing Calcium and Magnesium Leaching from Granitic Alpine Catchments.

    PubMed

    Kopáček, Jiří; Kaňa, Jiří; Bičárová, Svetlana; Fernandez, Ivan J; Hejzlar, Josef; Kahounová, Marie; Norton, Stephen A; Stuchlík, Evžen

    2017-01-03

    Climate change can reverse trends of decreasing calcium and magnesium [Ca + Mg] leaching to surface waters in granitic alpine regions recovering from acidification. Despite decreasing concentrations of strong acid anions (-1.4 μeq L(-1) yr(-1)) during 2004-2016 in nonacidic alpine lakes in the Tatra Mountains (Central Europe), the average [Ca + Mg] concentrations increased (2.5 μeq L(-1) yr(-1)), together with elevated terrestrial export of bicarbonate (HCO3(-); 3.6 μeq L(-1) yr(-1)). The percent increase in [Ca + Mg] concentrations in nonacidic lakes (0.3-3.2% yr(-1)) was significantly and positively correlated with scree proportion in the catchment area and negatively correlated with the extent of soil cover. Leaching experiments with freshly crushed granodiorite, the dominant bedrock, showed that accessory calcite and (to a lesser extent) apatite were important sources of Ca. We hypothesize that elevated terrestrial export of [Ca + Mg] and HCO3(-) resulted from increased weathering caused by accelerated physical erosion of rocks due to elevated climate-related mechanical forces (an increasing frequency of days with high precipitation amounts and air temperatures fluctuating around 0 °C) during the last 2-3 decades. These climatic effects on water chemistry are especially strong in catchments where fragmented rocks are more exposed to weathering, and their position is less stable than in soil.

  17. Zooplankton Successions in Neighboring Lakes with Contrasting Impacts of Amphibian and Fish Predators

    NASA Astrophysics Data System (ADS)

    Schabetsberger, Robert; Grill, Susanne; Hauser, Gabriele; Wukits, Petra

    2006-06-01

    Two pairs of neighboring subalpine lakes located in the Northern Calcareous Alps of Austria were investigated. Each pair comprised a deeper lake containing European minnows (Phoxinus phoxinus ), and a corresponding shallower lake harboring Alpine newts (Triturus alpestris ) as top predators. Plankton successions within fish and amphibian lakes differed markedly from each other. Throughout the year rotifers numerically dominated within the minnow lakes, while pigmented copepods (Genera Heterocope, Acanthodiaptomus , Arctodiaptomus , Mixodiaptomus ) and Daphnia were prominent in the amphibian lakes, at least early during the ice-free period. We argue that size-selective predation by minnows was the ultimate reason for this predominance of smaller zooplankton. While one of the minnow lakes was characterized by a succession of spatially and temporally segregated rotifer species, the other minnow lake permitted the development of populations of small-sized Bosmina and Ceriodaphnia during summer, probably due to the existence of a strong oxycline allowing zooplankton crustaceans to avoid predation from shore-based shoals of minnows. Once trout were introduced into this lake, minnows were visibly reduced in abundance. Bosmina and Ceriodaphnia disappeared and Daphnia together with a predacious copepod (Heterocope ) emerged either from egg banks or arrived from nearby source populations. We argue that the crustacean communities within the fishless lakes were adapted to the comparatively weak predation rates of Alpine newts.

  18. Multiscale Snow/Icemelt Discharge Simulations into Alpine Reservoirs: adding Glacier Dynamics to a Hydrological Model

    NASA Astrophysics Data System (ADS)

    Schueller, Felix; Förster, Kristian; Hanzer, Florian; Huttenlau, Matthias; Marzeion, Ben; Strasser, Ulrich; Achleitner, Stefan; Kirnbauer, Robert

    2015-04-01

    Glacier and snow runoff in high alpine regions is an essential process in hydrological research for its high relevance on lower altitude areas and hydro-power generation. MUSICALS II (Multiscale Snow/Icemelt Discharge Simulations into Alpine Reservoirs) seeks to identify and quantify water availability and runoff in alpine headwater catchments. The focus is on future changes due to glacier retreat, altering the multi-day and seasonal runoff available for hydropower operations. Our aim is to investigate and improve runoff forecasts by coupling the semi-distributed hydrological model HQSim with a simple glacier evolution model. The glacier model MMBM (Marzeion Mass Balance Model) with its statistical nature allows for fast modelling of the dynamical properties of glaciers. We present the design of the coupled hydrological application for different hydro power headwater catchments in Tyrol. The capabilities of the glacier model to simulate the selected glaciers is shown. Simulated discharge with the original and the coupled model are compared to downstream gauge measurements. Using the multi-objective optimization algorithm AMALGAM (A Multi-ALgorithm, Genetically Adaptive Multiobjective model), we optimize the glacier module parameters fully automatically. The results show the improvements in runoff modelling for past periods, when altering of glaciated catchment parts is considered. This indicates consideration of this process is mandatory for simulating future developments.

  19. Effects of acidic deposition on in-lake phosphorus availability: a lesson from lakes recovering from acidification.

    PubMed

    Kopáček, Jiří; Hejzlar, Josef; Kaňa, Jiří; Norton, Stephen A; Stuchlík, Evžen

    2015-03-03

    Lake water concentrations of phosphorus (P) recently increased in some mountain areas due to elevated atmospheric input of P rich dust. We show that increasing P concentrations also occur during stable atmospheric P inputs in central European alpine lakes recovering from atmospheric acidification. The elevated P availability in the lakes results from (1) increasing terrestrial export of P accompanying elevated leaching of dissolved organic carbon and decreasing phosphate-adsorption ability of soils due to their increasing pH, and (2) decreasing in-lake P immobilization by aluminum (Al) hydroxide due to decreasing leaching of ionic Al from the recovering soils. The P availability in the recovering lakes is modified by the extent of soil acidification, soil composition, and proportion of till and meadow soils in the catchment. These mechanisms explain several conflicting observations of the acid rain effects on surface water P concentrations.

  20. Forecasting alpine vegetation change using repeat sampling and a novel modeling approach.

    PubMed

    Johnson, David R; Ebert-May, Diane; Webber, Patrick J; Tweedie, Craig E

    2011-09-01

    Global change affects alpine ecosystems by, among many effects, by altering plant distributions and community composition. However, forecasting alpine vegetation change is challenged by a scarcity of studies observing change in fixed plots spanning decadal-time scales. We present in this article a probabilistic modeling approach that forecasts vegetation change on Niwot Ridge, CO using plant abundance data collected from marked plots established in 1971 and resampled in 1991 and 2001. Assuming future change can be inferred from past change, we extrapolate change for 100 years from 1971 and correlate trends for each plant community with time series environmental data (1971-2001). Models predict a decreased extent of Snowbed vegetation and an increased extent of Shrub Tundra by 2071. Mean annual maximum temperature and nitrogen deposition were the primary a posteriori correlates of plant community change. This modeling effort is useful for generating hypotheses of future vegetation change that can be tested with future sampling efforts.

  1. Climate Change Forces New Ecological States in Tropical Andean Lakes

    PubMed Central

    Michelutti, Neal; Wolfe, Alexander P.; Cooke, Colin A.; Hobbs, William O.; Vuille, Mathias; Smol, John P.

    2015-01-01

    Air temperatures in the tropical Andes have risen at an accelerated rate relative to the global average over recent decades. However, the effects of climate change on Andean lakes, which are vital to sustaining regional biodiversity and serve as an important water resource to local populations, remain largely unknown. Here, we show that recent climate changes have forced alpine lakes of the equatorial Andes towards new ecological and physical states, in close synchrony to the rapid shrinkage of glaciers regionally. Using dated sediment cores from three lakes in the southern Sierra of Ecuador, we record abrupt increases in the planktonic thalassiosiroid diatom Discostella stelligera from trace abundances to dominance within the phytoplankton. This unprecedented shift occurs against the backdrop of rising temperatures, changing atmospheric pressure fields, and declining wind speeds. Ecological restructuring in these lakes is linked to warming and/or enhanced water column stratification. In contrast to seasonally ice-covered Arctic and temperate alpine counterparts, aquatic production has not increased universally with warming, and has even declined in some lakes, possibly because enhanced thermal stability impedes the re-circulation of hypolimnetic nutrients to surface waters. Our results demonstrate that these lakes have already passed important ecological thresholds, with potentially far-reaching consequences for Andean water resources. PMID:25647018

  2. Climate change forces new ecological states in tropical Andean lakes.

    PubMed

    Michelutti, Neal; Wolfe, Alexander P; Cooke, Colin A; Hobbs, William O; Vuille, Mathias; Smol, John P

    2015-01-01

    Air temperatures in the tropical Andes have risen at an accelerated rate relative to the global average over recent decades. However, the effects of climate change on Andean lakes, which are vital to sustaining regional biodiversity and serve as an important water resource to local populations, remain largely unknown. Here, we show that recent climate changes have forced alpine lakes of the equatorial Andes towards new ecological and physical states, in close synchrony to the rapid shrinkage of glaciers regionally. Using dated sediment cores from three lakes in the southern Sierra of Ecuador, we record abrupt increases in the planktonic thalassiosiroid diatom Discostella stelligera from trace abundances to dominance within the phytoplankton. This unprecedented shift occurs against the backdrop of rising temperatures, changing atmospheric pressure fields, and declining wind speeds. Ecological restructuring in these lakes is linked to warming and/or enhanced water column stratification. In contrast to seasonally ice-covered Arctic and temperate alpine counterparts, aquatic production has not increased universally with warming, and has even declined in some lakes, possibly because enhanced thermal stability impedes the re-circulation of hypolimnetic nutrients to surface waters. Our results demonstrate that these lakes have already passed important ecological thresholds, with potentially far-reaching consequences for Andean water resources.

  3. Are endocrine and reproductive biomarkers altered in contaminant-exposed wild male Largemouth Bass (Micropterus salmoides) of Lake Mead, Nevada/Arizona, USA?

    USGS Publications Warehouse

    Goodbred, Steven L.; Patino, Reynaldo; Torres, Leticia; Echols, Kathy R.; Jenkins, Jill A.; Rosen, Michael R.; Orsak, Erik

    2015-01-01

    Male Largemouth Bass were sampled from two locations in Lake Mead (USA), a site influenced by treated municipal wastewater effluent and urban runoff (Las Vegas Bay), and a reference site (Overton Arm). Samples were collected in summer (July '07) and spring (March '08) to assess general health, endocrine and reproductive biomarkers, and compare contaminant body burdens by analyzing 252 organic chemicals. Sperm count and motility were measured in spring. Contaminants were detected at much higher frequencies and concentrations in fish from Las Vegas Bay than Overton Arm. Those with the highest concentrations included PCBs, DDTs, PBDEs, galaxolide, and methyl triclosan. Fish from Las Vegas Bay also had higher Fulton condition factor, hepatosomatic index, and hematocrit, and lower plasma 11-ketotestosterone concentration (KT). Gonadosomatic index (GSI) and sperm motility did not differ between sites, but sperm count was lower by nearly 50% in fish from Las Vegas Bay. A positive association between KT and GSI was identified, but this association was nonlinear. On average, maximal GSI was reached at sub-maximal KT concentrations. In conclusion, the higher concentration of contaminant body burdens coupled with reduced levels of KT and sperm count in fish from Las Vegas Bay suggest that male reproductive condition was influenced by contaminant exposures. Also, the nonlinear KT-GSI association provided a framework to understand why GSI was similar between male bass from both sites despite their large difference in KT, and also suggested the existence of post-gonadal growth functions of KT at high concentrations.

  4. Are endocrine and reproductive biomarkers altered in contaminant-exposed wild male Largemouth Bass (Micropterus salmoides) of Lake Mead, Nevada/Arizona, USA?

    PubMed

    Goodbred, Steven L; Patiño, Reynaldo; Torres, Leticia; Echols, Kathy R; Jenkins, Jill A; Rosen, Michael R; Orsak, Erik

    2015-08-01

    Male Largemouth Bass were sampled from two locations in Lake Mead (USA), a site influenced by treated municipal wastewater effluent and urban runoff (Las Vegas Bay), and a reference site (Overton Arm). Samples were collected in summer (July '07) and spring (March '08) to assess general health, endocrine and reproductive biomarkers, and compare contaminant body burdens by analyzing 252 organic chemicals. Sperm count and motility were measured in spring. Contaminants were detected at much higher frequencies and concentrations in fish from Las Vegas Bay than Overton Arm. Those with the highest concentrations included PCBs, DDTs, PBDEs, galaxolide, and methyl triclosan. Fish from Las Vegas Bay also had higher Fulton condition factor, hepatosomatic index, and hematocrit, and lower plasma 11-ketotestosterone concentration (KT). Gonadosomatic index (GSI) and sperm motility did not differ between sites, but sperm count was lower by nearly 50% in fish from Las Vegas Bay. A positive association between KT and GSI was identified, but this association was nonlinear. On average, maximal GSI was reached at sub-maximal KT concentrations. In conclusion, the higher concentration of contaminant body burdens coupled with reduced levels of KT and sperm count in fish from Las Vegas Bay suggest that male reproductive condition was influenced by contaminant exposures. Also, the nonlinear KT-GSI association provided a framework to understand why GSI was similar between male bass from both sites despite their large difference in KT, and also suggested the existence of post-gonadal growth functions of KT at high concentrations.

  5. Depth heterogeneity of soil organic carbon dynamics in a heavily grazed alpine meadow on the northeastern Tibetan Plateau: A radiocarbon-based approach

    NASA Astrophysics Data System (ADS)

    Yu, Shi-Yong; He, Honglin; Cheng, Peng; Hou, Zhanfang

    2017-07-01

    A deep understanding of soil organic carbon (SOC) dynamics on the Tibetan Plateau is crucial for predicting the response of the alpine carbon pool to future climate changes. Here we present information about SOC stocks and turnover time in a heavily grazed alpine meadow on the Tibetan Plateau based on radiocarbon (14C) measurements and inverse modeling. Our results reveal that the alpine meadow soil is composed of three distinct carbon pools. The topsoil represents the active carbon pool, which has a carbon inventory-weighted mean turnover time of 64 years. The CO2 efflux due to the mineral soil respiration from this pool is approximately 48.45 g C m-2 yr-1, accounting for 91% of the total heterotrophic soil respiration. The intermediate carbon pool has an inventory-weighted mean turnover time of 780 years, and the rate of mineral soil respiration in this pool is an order of magnitude lower than that in the active carbon pool. The parental materials feature the passive carbon pool, which has millennia-long turnover time and the mineral soil respiration is trivial. Comparing our results with other 14C-based studies suggests that grazing intensity may alter not only the SOC stocks but also the soil respiration rate in the alpine grassland ecosystem. The heavily grazed alpine meadow broadly fits the exponential relationship between turnover time and mean annual air temperature identified by meta-analysis of published data from the Tibetan Plateau, alpine grassland, and forest sites elsewhere.

  6. Solar and atmospheric forcing on mountain lakes.

    PubMed

    Luoto, Tomi P; Nevalainen, Liisa

    2016-10-01

    We investigated the influence of long-term external forcing on aquatic communities in Alpine lakes. Fossil microcrustacean (Cladocera) and macrobenthos (Chironomidae) community variability in four Austrian high-altitude lakes, determined as ultra-sensitive to climate change, were compared against records of air temperature, North Atlantic Oscillation (NAO) and solar forcing over the past ~400years. Summer temperature variability affected both aquatic invertebrate groups in all study sites. The influence of NAO and solar forcing on aquatic invertebrates was also significant in the lakes except in the less transparent lake known to have remained uniformly cold during the past centuries due to summertime snowmelt input. The results suggest that external forcing plays an important role in these pristine ecosystems through their impacts on limnology of the lakes. Not only does the air temperature variability influence the communities but also larger-scale external factors related to atmospheric circulation patterns and solar activity cause long-term changes in high-altitude aquatic ecosystems, through their connections to hydroclimatic conditions and light environment. These findings are important in the assessment of climate change impacts on aquatic ecosystems and in greater understanding of the consequences of external forcing on lake ontogeny. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Contexts for change in alpine tundra

    USGS Publications Warehouse

    Malanson, George P.; Rose, Jonathan P.; Schroeder, P. Jason; Fagre, Daniel B.

    2011-01-01

    Because alpine tundra is responding to climate change, a need exists to understand the meaning of observed changes. To provide context for such interpretation, the relevance of niche and neutral theories of biogeography and the continuum and classification approaches to biogeographic description are assessed. Two extensive studies of alpine tundra, from the Indian Peaks area, Colorado and Glacier National Park, Montana, are combined. The data are ordinated to describe relations. The pattern that emerges is one of a continuum of vegetation, but with the distinctions one might expect from distant sites. The relationships of the similarity of vegetation on all possible pairs of sites to the environmental differences and geographic distances are analyzed using Mantel correlations. Because distance and environmental differences in climate between the two sites are correlated, partial correlations are weak but still significant. More advanced analyses are suggested for this environment prior to interpretation of monitoring efforts such as GLORIA.

  8. Origin and migration of the Alpine Iceman.

    PubMed

    Müller, Wolfgang; Fricke, Henry; Halliday, Alex N; McCulloch, Malcolm T; Wartho, Jo-Anne

    2003-10-31

    The Alpine Iceman provides a unique window into the Neolithic-Copper Age of Europe. We compared the radiogenic (strontium and lead) and stable (oxygen and carbon) isotope composition of the Iceman's teeth and bones, as well as 40Ar/39Ar mica ages from his intestine, to local geology and hydrology, and we inferred his habitat and range from childhood to adult life. The Iceman's origin can be restricted to a few valleys within approximately 60 kilometers south(east) of the discovery site. His migration during adulthood is indicated by contrasting isotopic compositions of enamel, bones, and intestinal content. This demonstrates that the Alpine valleys of central Europe were permanently inhabited during the terminal Neolithic.

  9. Intersex and alterations in reproductive development of a cichlid, Tilapia guineensis, from a municipal domestic water supply lake (Eleyele) in Southwestern Nigeria.

    PubMed

    Adeogun, Aina O; Ibor, Oju R; Adeduntan, Sherifat D; Arukwe, Augustine

    2016-01-15

    The objectives of this study were to develop and validate biomarker techniques for aquatic environmental monitoring of endocrine disrupting chemicals (EDCs) in Nigeria aquatic ecosystems, using the Eleyele Lake, which is a major source of domestic water supply to Ibadan and its surrounding towns, as a model aquatic environment and Tilapia guineensis, as a model organism. A total of 55 male and 28 female fish were used for this study. No significant difference in condition factor was observed between the sexes. Evaluation of gross gonadal morphology of the sampled fish showed 33% intersex prevalence in the sampled population, of which respective 71 and 29% were males and females, with visible testis and ovary developing alongside phenotypic females and males. Plasma concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), 11-ketotestosterone (11-KT) and 17β-estradiol (E2) were performed, showing that male fish had significantly higher plasma LH and E2 concentrations, compared to females. Vitellogenin (Vtg) and zona radiata proteins (Zrp) mRNA levels were significantly higher in males, compared to female fish. Contaminant analysis revealed that PCB 81, 123, 138 and 196 were the only PCB congeners detected in sediment and fish muscle (PCB153 in sediment), while dieldrin was the only organochlorine compound (OC) detected in Eleyele sediment. These responses were used in a multivariate analysis, showing that two principal components were extracted and accounted for 74% of total variation in the dataset. The principal component analysis (PCA) showed that male fish variables were positively correlated with PCB congeners 18 and 123, while female fish showed positive correlations with congener 81, 138, 189, 196, indicating sex-specific pattern of association between PCBs concentrations and biomarker expression. In addition, strong positive correlation between male fish and LH, E2, FSH and Vtg was observed, while female fish positively correlated with

  10. Sensitivity of subalpine tree seedlings and alpine plants to natural and manipulated climate variation: Initial results from an Alpine Treeline Warming Experiment (Invited)

    NASA Astrophysics Data System (ADS)

    Kueppers, L. M.

    2010-12-01

    Niche models and paleoecological studies indicate that future climate change will alter the geographic distributions of plant species. Changes in temperature, snowmelt timing, or moisture conditions at one edge of a species’ range may have different consequences for recruitment, carbon exchange, phenology, and survival than changes at another edge. Similarly, local genetic adaptation may constrain species and community responses to climate change. We have established a new experiment to investigate potential shifts in the distribution of subalpine tree species, and the alpine species they might replace. We are asking how tree species recruitment and alpine species growth and reproduction vary within their current ranges, and in response to temperature and soil moisture manipulations. We are also examining whether genetic provenance and ecosystem processes constrain tree seedling and alpine herb responses. Our Alpine Treeline Warming Experiment is located across three sites at Niwot Ridge, CO, ranging from near the lower limit of subalpine forest to alpine tundra. We use infrared heaters to raise growing season surface soil temperatures by 4-5°C, and to lengthen the growing season. The warming treatment is crossed with a soil moisture manipulation to distinguish effects due to higher temperatures from those due to drier soil. Each plot is a common garden sown with high and low elevation provenances of limber pine (Pinus flexilis) and Engelmann spruce (Picea engelmannii). We established an additional set of experimental plots to examine treatment effects on alpine species phenology, growth and reproduction. Under ambient conditions in 2009, tree seedling germination rate, lifespan, and first season survival was higher within the species’ current range than in the alpine, and for Engelmann spruce, was higher at the low elevation limit than the high elevation limit. Source population (low vs. high elevation) was a significant factor explaining natural variation in

  11. Working toward integrated models of alpine plant distribution

    PubMed Central

    Carlson, Bradley Z.; Randin, Christophe F.; Boulangeat, Isabelle; Lavergne, Sébastien; Thuiller, Wilfried; Choler, Philippe

    2014-01-01

    Species distribution models (SDMs) have been frequently employed to forecast the response of alpine plants to global changes. Efforts to model alpine plant distribution have thus far been primarily based on a correlative approach, in which ecological processes are implicitly addressed through a statistical relationship between observed species occurrences and environmental predictors. Recent evidence, however, highlights the shortcomings of correlative SDMs, especially in alpine landscapes where plant species tend to be decoupled from atmospheric conditions in micro-topographic habitats and are particularly exposed to geomorphic disturbances. While alpine plants respond to the same limiting factors as plants found at lower elevations, alpine environments impose a particular set of scale-dependent and hierarchical drivers that shape the realized niche of species and that require explicit consideration in a modelling context. Several recent studies in the European Alps have successfully integrated both correlative and process-based elements into distribution models of alpine plants, but for the time being a single integrative modelling framework that includes all key drivers remains elusive. As a first step in working toward a comprehensive integrated model applicable to alpine plant communities, we propose a conceptual framework that structures the primary mechanisms affecting alpine plant distributions. We group processes into four categories, including multi-scalar abiotic drivers, gradient dependent species interactions, dispersal and spatial–temporal plant responses to disturbance. Finally, we propose a methodological framework aimed at developing an integrated model to better predict alpine plant distribution. PMID:24790594

  12. Morphometry and average temperature affect lake stratification responses to climate change

    NASA Astrophysics Data System (ADS)

    Kraemer, Benjamin M.; Anneville, Orlane; Chandra, Sudeep; Dix, Margaret; Kuusisto, Esko; Livingstone, David M.; Rimmer, Alon; Schladow, S. Geoffrey; Silow, Eugene; Sitoki, Lewis M.; Tamatamah, Rashid; Vadeboncoeur, Yvonne; McIntyre, Peter B.

    2015-06-01

    Climate change is affecting lake stratification with consequences for water quality and the benefits that lakes provide to society. Here we use long-term temperature data (1970-2010) from 26 lakes around the world to show that climate change has altered lake stratification globally and that the magnitudes of lake stratification changes are primarily controlled by lake morphometry (mean depth, surface area, and volume) and mean lake temperature. Deep lakes and lakes with high average temperatures have experienced the largest changes in lake stratification even though their surface temperatures tend to be warming more slowly. These results confirm that the nonlinear relationship between water density and water temperature and the strong dependence of lake stratification on lake morphometry makes lake temperature trends relatively poor predictors of lake stratification trends.

  13. Geomorphic controls on Pleistocene knickpoint migration in Alpine valleys

    NASA Astrophysics Data System (ADS)

    Leith, Kerry; Fox, Matt; Moore, Jeffrey R.; Brosda, Julian; Krautblatter, Michael; Loew, Simon

    2014-05-01

    Recent insights into sub-glacial bedrock stress conditions suggest that the erosional efficiency of glaciers may reduce markedly following a major erosional cycle [Leith et al., 2013]. This implies that the formation of large glacial valleys within the Alps is likely to have occurred shortly after the onset of 100 ky glacial-interglacial cycles (at the mid-Pleistocene Revolution (MPR)). The majority of landscape change since this time may have therefore been driven by sub-aerial processes. This hypothesis is supported by observations of hillslope and channel morphology within Canton Valais (Switzerland), where major tributary valleys display a common morphology along their length, hinting at a shared geomorphic history. Glaciers currently occupy the headwaters of many catchments, while the upper reaches of rivers flow across extensive alluvial planes before abruptly transitioning to steep channels consisting of mixed bedrock and talus fan deposits. The rivers then converge to flow out over the alluvial plane of the Rhone Valley. Characteristically rough topographies within the region are suggested to mark the progressive transition from a glacial to fluvially-dominated landscape, and correlate well with steepened river channel sections determined from a 2.5 m resolution LiDAR DEM. We envisage a landscape in which ongoing tectonic uplift drives the emergence of Alpine bedrock through massive sedimentary valley infills (currently concentrated in the Rhone Valley), whose elevation is fixed by the consistent fluvial baselevel at Lake Geneva. As fluvial incision ceases at the onset of glaciation, continued uplift causes the formation of knickpoints at the former transition from bedrock to sedimentary infill. These knickpoints will then propagate upstream during subsequent interglacial periods. By investigating channel morphologies using an approach based on the steady-state form of the stream power equation, we can correlate steepened channel reaches (degraded

  14. Subsurface architecture of two tropical alpine desert cinder cones that hold water

    NASA Astrophysics Data System (ADS)

    Leopold, Matthias; Morelli, Amanda; Schorghofer, Norbert

    2016-06-01

    Basaltic lava is generally porous and cannot hold water to form lakes. Here we investigate two impermeable cinder cones in the alpine desert of Maunakea volcano, Hawaii. We present the results of the first ever geophysical survey of the area around Lake Waiau, the highest lake on the Hawaiian Islands, and establish the existence of a second body of standing water in a nearby cinder cone, Pu`upōhaku (~4000 m above sea level), which has a sporadic pond of water. Based on unpublished field notes from Alfred Woodcock (*1905-†2005) spanning the years 1966-1977, more recent observations, and our own geophysical survey using electric resistivity tomography, we find that perched groundwater resides in the crater perennially to a depth of 2.5 m below the surface. Hence, Pu`upōhaku crater hosts a previously unrecognized permanent body of water, the highest on the Hawaiian Islands. Nearby Lake Waiau is also perched within a cinder cone known as Pu`uwaiau. Among other hypotheses, permafrost or a massive block of lava were discussed as a possible cause for perching the water table. Based on our results, ground temperatures are too high and specific electric resistivity values too low to be consistent with either ice-rich permafrost or massive rock. Fine-grained material such as ash and its clay-rich weathering products are likely the impermeable material that explains the perched water table at both study sites. At Pu`uwaiau we discovered a layer of high conductivity that may constitute a significant water reservoir outside of the lake and further be responsible for perching the water toward the lake.

  15. Soil Fauna Affects Dissolved Carbon and Nitrogen in Foliar Litter in Alpine Forest and Alpine Meadow

    PubMed Central

    Liao, Shu; Yang, Wanqin; Tan, Yu; Peng, Yan; Li, Jun; Tan, Bo; Wu, Fuzhong

    2015-01-01

    Dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) are generally considered important active biogeochemical pools of total carbon and nitrogen. Many studies have documented the contributions of soil fauna to litter decomposition, but the effects of the soil fauna on labile substances (i.e., DOC and TDN) in litter during early decomposition are not completely clear. Therefore, a field litterbag experiment was carried out from 13th November 2013 to 23rd October 2014 in an alpine forest and an alpine meadow located on the eastern Tibetan Plateau. Litterbags with different mesh sizes were used to provide access to or prohibit the access of the soil fauna, and the concentrations of DOC and TDN in the foliar litter were measured during the winter (the onset of freezing, deep freezing and thawing stage) and the growing season (early and late). After one year of field incubation, the concentration of DOC in the litter significantly decreased, whereas the TDN concentration in the litter increased. Similar dynamic patterns were detected under the effects of the soil fauna on both DOC and TDN in the litter between the alpine forest and the alpine meadow. The soil fauna showed greater positive effects on decreasing DOC concentration in the litter in the winter than in the growing season. In contrast, the dynamics of TND in the litter were related to seasonal changes in environmental factors, rather than the soil fauna. In addition, the soil fauna promoted a decrease in litter DOC/TDN ratio in both the alpine forest and the alpine meadow throughout the first year of decomposition, except for in the late growing season. These results suggest that the soil fauna can promote decreases in DOC and TDN concentrations in litter, contributing to early litter decomposition in these cold biomes. PMID:26406249

  16. Soil Fauna Affects Dissolved Carbon and Nitrogen in Foliar Litter in Alpine Forest and Alpine Meadow.

    PubMed

    Liao, Shu; Yang, Wanqin; Tan, Yu; Peng, Yan; Li, Jun; Tan, Bo; Wu, Fuzhong

    2015-01-01

    Dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) are generally considered important active biogeochemical pools of total carbon and nitrogen. Many studies have documented the contributions of soil fauna to litter decomposition, but the effects of the soil fauna on labile substances (i.e., DOC and TDN) in litter during early decomposition are not completely clear. Therefore, a field litterbag experiment was carried out from 13th November 2013 to 23rd October 2014 in an alpine forest and an alpine meadow located on the eastern Tibetan Plateau. Litterbags with different mesh sizes were used to provide access to or prohibit the access of the soil fauna, and the concentrations of DOC and TDN in the foliar litter were measured during the winter (the onset of freezing, deep freezing and thawing stage) and the growing season (early and late). After one year of field incubation, the concentration of DOC in the litter significantly decreased, whereas the TDN concentration in the litter increased. Similar dynamic patterns were detected under the effects of the soil fauna on both DOC and TDN in the litter between the alpine forest and the alpine meadow. The soil fauna showed greater positive effects on decreasing DOC concentration in the litter in the winter than in the growing season. In contrast, the dynamics of TND in the litter were related to seasonal changes in environmental factors, rather than the soil fauna. In addition, the soil fauna promoted a decrease in litter DOC/TDN ratio in both the alpine forest and the alpine meadow throughout the first year of decomposition, except for in the late growing season. These results suggest that the soil fauna can promote decreases in DOC and TDN concentrations in litter, contributing to early litter decomposition in these cold biomes.

  17. Keep cool: memory is retained during hibernation in Alpine marmots.

    PubMed

    Clemens, L E; Heldmaier, G; Exner, C

    2009-08-04

    Hibernators display severe changes in brain structure during deep torpor, including alterations in synaptic constitution. To address a possible effect on long-term memory, we examined learning behavior and memory of the hibernator Marmota marmota. In two operant conditioning tasks, the marmots learned to jump on two boxes or to walk through a tube. The animals were trained during their active season. Performance improved during the training phase and remained stable in a last test, four weeks before entrance into hibernation. When retested after six months of hibernation, skills were found to be unimpaired (box: before hibernation: 258.2+/-17.7 s, after hibernation: 275.0+/-19.8 s; tube: before hibernation: 158.4+/-9.0 s, after hibernation: 137.7+/-6.3 s). Contrary to these findings, memory seemed to be less fixed during the active season, since changes in test procedure resulted in impaired test performance. Besides the operant conditioning, we investigated the animals' habituation to a novel environment by repeated open field exposure. In the first run, animals showed exploratory behavior and thus a high locomotor activity was observed (63.6+/-10.7 crossed squares). Upon a second exposure, all animals immediately moved into one corner and locomotion ceased (7.2+/-1.9 crossed squares). This habituation was not altered even after hibernation (6.1+/-1.1 crossed squares). We thus conclude that long-term memory is unaffected by hibernation in Alpine marmots.

  18. Factors influencing legacy pollutant accumulation in alpine osprey: biology, topography, or melting glaciers?

    PubMed

    Elliott, John E; Levac, Joshua; Guigueno, Mélanie F; Shaw, D Patrick; Wayland, Mark; Morrissey, Christy A; Muir, Derek C G; Elliott, Kyle H

    2012-09-04

    Persistent organic pollutants (POPs) can be transported long distances and deposited into alpine environments via cold trapping and snow scavenging processes. Here we examined biotic and abiotic factors determining contaminant variability of wildlife in alpine ecosystems. We measured POPs in eggs and plasma of an apex predator, the osprey (Pandion haliaetus) breeding in 15 mountainous watersheds across a broad latitudinal, longitudinal and altitudinal range in western Canada. After accounting for proximate biotic factors such as trophic level (δ(15)N) and carbon source (δ(13)C), variability in contaminant concentrations, including ΣDDT (sum of trichlorodiphenylethane-related compounds), toxaphene, hexachlorobenzene (HCB), total chlordane, and ΣPCBs (polychlorinated biphenyls) in osprey tissues was explained by interactions among relative size of watersheds, water bodies, elevation, and glacial input. ΣDDT in nestling plasma, for example, decreased with lake elevation, probably as a result of local past inputs from agricultural or public health usage at lower altitude sites. In contrast, toxaphene, never used as an insecticide in western Canada, increased with elevation and year-round snow and ice cover in both plasma and eggs, indicating long-range atmospheric sources as dominant for toxaphene. Lower chlorinated PCBs in plasma tended to decrease with elevation and ice cover consistent with published data and model outcomes. Temporal trends of POPs in osprey eggs are coincident with some modeled predictions of release from melting glaciers due to climate change. Currently we suggest that contaminants largely are released through annual snowpack melt and deposited in large lower elevation lakes, or some smaller lakes with poor drainage. Our study highlights the importance of understanding how biological processes integrate physical when studying the environmental chemistry of wildlife.

  19. Hydrology of the Hamilton lakes and vicinity, Polk County, central Florida

    USGS Publications Warehouse

    Anderson, Warren G.; Simonds, Edward P.

    1983-01-01

    The Hamilton lakes, headwaters of the eastern arm of the Peace River drainage system, consist of Lake Hamilton, Middle Lake Hamilton, and Little Lake Hamilton. The lakes, which are connected by canals that tend to equalize their levels, probably occupy coalesced sinkhole depressions. The drainage basin of Lake Hamilton contains several water-control structures which can alter the effective size of the area contributing water to the Hamilton lakes according to their gate settings. The chemical and biological conditions in the Hamilton lakes are such that the lakes are not sufficiently enriched to cause problems with excessive weed growth or algae blooms. (USGS)

  20. OH zoning in alpine quartz from Austria

    NASA Astrophysics Data System (ADS)

    Hertweck, B.; Niedermayr, G.; Beran, A.

    2003-04-01

    Rock crystals from various alpine clefts in Austria were investigated in terms of morphology, domain structure, and OH defects. Since the formation of alpine clefts is a long lasting and multiphase process, the crystal growth of alpine quartz is dominated by different morphologies and various OH defects. 140 samples were investigated by FTIR spectroscopy and optical methods to reveal complementary information on morphology, twining, hydrogen incorporation, and zoning of the OH defects. IR spectroscopic measurements of colourless and smoky quartz samples revealed six characteristic absorption bands in the range of the OH stretching frequencies at 3315, 3380, 3430, 3480, 3510 and 3595 cm-1. The quantitative analysis of the water content revealed an amount of 0.5-20 ppm H_2O. With a maximum of frequency in the 1-2 ppm range the amount of water incorporation is comparably lower than known from non-alpine deposits. The spectra can be divided in four types characterised by the number and/or the relative band intensities. Among the Austrian samples one type, showing clearly all the six bands, is abundant and has not been found in the spectra from non-alpine sites. A significant relation between spectra type, crystal morphology, mineral deposit (within Austria), and OH content cannot be deduced. Microspectroscopic measurements of profiles through crystals cut perpendicular to the c-axis revealed that the spectra types rarely change within one sample. However, a variation of the water content is commonly related to a change of the relative intensity of the 3480 cm-1 absorption band. Regarding the hydrogen incorporation all samples show a distinct zoning. In addition, the OH zoning as well as the crystal growth appear regularly, leading to different hydrogen amounts in core and mantle zone of the crystals. The average zoning is given by factor 1.2, whereas strong variations were measured up to factor 2.5. The formation of Brazil twin domains often coincides with a distinct

  1. Effects of warming and nitrogen deposition on CH4, CO2 and N2O emissions in alpine grassland ecosystems of the Qinghai-Tibetan Plateau.

    PubMed

    Zhao, Zhenzhen; Dong, Shikui; Jiang, Xiaoman; Liu, Shiliang; Ji, Hanzhong; Li, Yu; Han, Yuhui; Sha, Wei

    2017-08-15

    Increases in nitrogen (N) deposition along with climate warming can change the dynamics of carbon and nitrogen in the soil, and alter greenhouse gases (GHGs) fluxes. To examine how N deposition and warming affect GHGs (CH4, CO2 and N2O) fluxes in alpine grasslands, we conducted experiments in an alpine meadow (AM), alpine-steppe (AS), and alpine cultivated grassland (CG) on the Qinghai-Tibetan Plateau (QTP). We simulated N deposition by treating soil with ammonium nitrate (NH4NO3) (8kgNha(-1)year(-1)), a warming treatment using an open top chamber (OTC) was carried out, and a combined treatment of warming and N deposition (8kgNha(-1)year(-1)) was conducted. The GHGs were collected during early, peak, and late plant growing seasons, i.e., May, August, and October of 2015, respectively, using a static chamber. We found, in general, neither N deposition nor warming solely altered CH4 and N2O fluxes in the alpine grasslands. The N deposition under warming conditions reduced CO2 emission significantly. The reduction of CO2 emission was most significant in the alpine steppe. The effects of climatic warming and N deposition on the GHGs varied greatly across the grassland types and the growing seasons. The cultivated grasslands were much more unstable than the native grasslands in CH4 uptake. In can be concluded the N deposition associated with human activities may buffer the CO2 emission in the alpine grassland ecosystems in terms of climate changes on the QTP. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Generating quantitative palaeoflood data from homogeneous lake sediments: a case-study from Brotherswater, northwest England

    NASA Astrophysics Data System (ADS)

    Schillereff, Daniel; Chiverrell, Richard; Macdonald, Neil; Hooke, Janet

    2016-04-01

    The scarcity of long-term hydrological data is a barrier to reliably determining the likelihood of floods becoming more frequent and/or intense in a warmer world. Lakes and their sediments are increasingly being used to reconstruct long-term, highly-resolved datasets of past floods but the ultimate goal, generating quantitative palaeohydrological data to augment flood frequency analyses, is a persistent challenge. To this end, ascertaining the autogenic and allogenic processes influencing the character and preservation potential of palaeoflood laminations and determining the minimum discharge at which a sedimentary imprint will be deposited in a particular system are two key precursors. Some success has been achieved at lakes containing annually-laminated sequences or where event layers exhibit well-defined lithological contacts. Many non-alpine and non-polar lakes, especially those in temperate regions, are instead characterised by visually-homogeneous, organic-rich sediments from which discrete flood laminations are difficult to discriminate. Working at Brotherswater, a small upland lake in northwest England, we have successfully demonstrated an approach to obtain flood frequency and magnitude data from this type of lake system by integrating a 16 month sediment trap deployment (CE 2013-2014) with the recent (CE 1962 - 2014) depositional record. The geochemical composition and end-member modelling of the trap data shed light on the seasonal variation in background sedimentation dynamics, specifically enhanced sediment supply during winter, spring diatom blooms and heightened summer productivity, which alter the signature of coarse-grained deposition in response to higher flows. Having pinpointed the characteristic flood end-member, comparison of the short-core palaeoflood reconstruction to local river discharge data was able to reveal the hydrological thresholds of this system: flood magnitudes calculated to have a four year recurrence interval are preserved in

  3. Hydrology of Lake Carroll, Hillsborough County, Florida

    USGS Publications Warehouse

    Henderson, S.E.; Hayes, R.D.; Stoker, Y.E.

    1985-01-01

    Lakeshore property around Lake Carroll has undergone extensive residential development since 1960. This development increased the lake shoreline, altered surface water flow to and from the lake, and may have affected lake-stage characteristics. Some areas of the lake were dredged to provide fill material for lakefront property. Water-balance analyses for 1952-60, a predevelopment period, and 1961-80, a period of residential development, indicate that both net surface water flow to the lake and downward leakage from the lake to the Floridan aquifer were greater after 1960. These changes were due more to changes in the regional climate and related changes in ground-water levels than to changes associated with residential development. Results of water quality analyses in 1980-81 are within State limits for surface waters used for recreation and wildlife propagation. (USGS)

  4. Ecosystem Carbon Storage in Alpine Grassland on the Qinghai Plateau

    PubMed Central

    Liu, Shuli; Zhang, Fawei; Du, Yangong; Guo, Xiaowei; Lin, Li; Li, Yikang; Li, Qian; Cao, Guangmin

    2016-01-01

    The alpine grassland ecosystem can sequester a large quantity of carbon, yet its significance remains controversial owing to large uncertainties in the relative contributions of climate factors and grazing intensity. In this study we surveyed 115 sites to measure ecosystem carbon storage (both biomass and soil) in alpine grassland over the Qinghai Plateau during the peak growing season in 2011 and 2012. Our results revealed three key findings. (1) Total biomass carbon density ranged from 0.04 for alpine steppe to 2.80 kg C m-2 for alpine meadow. Median soil organic carbon (SOC) density was estimated to be 16.43 kg C m-2 in alpine grassland. Total ecosystem carbon density varied across sites and grassland types, from 1.95 to 28.56 kg C m-2. (2) Based on the median estimate, the total carbon storage of alpine grassland on the Qinghai Plateau was 5.14 Pg, of which 94% (4.85 Pg) was soil organic carbon. (3) Overall, we found that ecosystem carbon density was affected by both climate and grazing, but to different extents. Temperature and precipitation interaction significantly affected AGB carbon density in winter pasture, BGB carbon density in alpine meadow, and SOC density in alpine steppe. On the other hand, grazing intensity affected AGB carbon density in summer pasture, SOC density in alpine meadow and ecosystem carbon density in alpine grassland. Our results indicate that grazing intensity was the primary contributing factor controlling carbon storage at the sites tested and should be the primary consideration when accurately estimating the carbon storage in alpine grassland. PMID:27494253

  5. Ecosystem Carbon Storage in Alpine Grassland on the Qinghai Plateau.

    PubMed

    Liu, Shuli; Zhang, Fawei; Du, Yangong; Guo, Xiaowei; Lin, Li; Li, Yikang; Li, Qian; Cao, Guangmin

    2016-01-01

    The alpine grassland ecosystem can sequester a large quantity of carbon, yet its significance remains controversial owing to large uncertainties in the relative contributions of climate factors and grazing intensity. In this study we surveyed 115 sites to measure ecosystem carbon storage (both biomass and soil) in alpine grassland over the Qinghai Plateau during the peak growing season in 2011 and 2012. Our results revealed three key findings. (1) Total biomass carbon density ranged from 0.04 for alpine steppe to 2.80 kg C m-2 for alpine meadow. Median soil organic carbon (SOC) density was estimated to be 16.43 kg C m-2 in alpine grassland. Total ecosystem carbon density varied across sites and grassland types, from 1.95 to 28.56 kg C m-2. (2) Based on the median estimate, the total carbon storage of alpine grassland on the Qinghai Plateau was 5.14 Pg, of which 94% (4.85 Pg) was soil organic carbon. (3) Overall, we found that ecosystem carbon density was affected by both climate and grazing, but to different extents. Temperature and precipitation interaction significantly affected AGB carbon density in winter pasture, BGB carbon density in alpine meadow, and SOC density in alpine steppe. On the other hand, grazing intensity affected AGB carbon density in summer pasture, SOC density in alpine meadow and ecosystem carbon density in alpine grassland. Our results indicate that grazing intensity was the primary contributing factor controlling carbon storage at the sites tested and should be the primary consideration when accurately estimating the carbon storage in alpine grassland.

  6. Latest Pleistocene advance of alpine glaciers in the southwestern Uinta Mountains, Utah, USA: Evidence for the influence of local moisture sources

    NASA Astrophysics Data System (ADS)

    Munroe, Jeffrey S.; Laabs, Benjamin J. C.; Shakun, Jeremy D.; Singer, Brad S.; Mickelson, David M.; Refsnider, Kurt A.; Caffee, Marc W.

    2006-10-01

    Cosmogenic surface-exposure 10Be dating of Last Glacial Maximum (LGM) moraines indicates that glaciers in the southwestern Uinta Mountains remained at their maximum positions until ca. 16.8 ± 0.7 ka, ˜2 k.y. after glaciers in the neighboring Wind River Range and Colorado Rockies began to retreat. The timing of the local LGM in the southwestern Uintas overlaps with both the hydrologic maximum of Lake Bonneville and preliminary estimates of the local LGM in the western Wasatch Mountains. This broad synchroneity indicates that Lake Bonneville and glaciers in northern Utah were responding to similar climate forcing. Furthermore, equilibrium line altitudes (ELAs) for reconstructed LGM alpine glaciers increase with distance from the Lake Bonneville shoreline, rising from ˜2600 m to ˜3200 m over the 120 km length of the glaciated Uintas. This pronounced ELA gradient suggests that the magnitude of the latest Pleistocene glacial advance in the western Uintas was due, at least in part, to enhanced precipitation derived from Lake Bonneville; thus, the lake acted as a local amplifier of regional climate forcing. This relationship underscores the sensitivity of alpine glaciers to moisture availability during the latest Pleistocene, and further demonstrates the importance of local moisture sources on glacier mass balance.

  7. High intensity training and energy production during 90-second box jump in junior alpine skiers.

    PubMed

    Gross, Micah; Hemund, Kevin; Vogt, Michael

    2014-06-01

    Alpine ski races can last up to 2.5 minutes and have very high metabolic demands. One limiting factor for performance is insufficient aerobic energy supply. We studied the effects of an 8-day interval training block on aerobic capacity (VO2max) and performance and physiology during the 90-second box jump test (BJ90), a maximal performance test employed to simulate the metabolic demands of alpine ski racing, in elite junior skiers. After 10 high-intensity interval training sessions, performed as cycling, running, or an obstacle course, VO2max increased in all subjects by 2.5 ± 1.9 ml · minute(-1) · kg(-1) (4.3 ± 3.2%), as did maximal blood lactate concentration in a graded cycling test (before: 11.7 ± 1.3 mmol · L(-1), after: 14.8 ± 1.8 mmol · L(-1), both parameters p ≤ 0.05). Performance (total jumps) and aerobic energy contribution (63.3 ± 2.8%) during the BJ90 did not increase as hypothesized; however, subjects altered their pacing strategy, which may have counteracted such an effect. Additionally, the present data support the practicality of the performance test used for mimicking the demands of alpine skiing.

  8. Effect of altitude on the genetic structure of an Alpine grass, Poa hiemata

    PubMed Central

    Byars, Sean G.; Parsons, Yvonne; Hoffmann, Ary A.

    2009-01-01

    Background and Aims The persistence of plants inhabiting restricted alpine areas under climate change will depend upon many factors including levels of genetic variation in adaptive traits, population structure, and breeding system. Methods Using microsatellite markers, the genetic structure of populations of a relatively common alpine grass, Poa hiemata, is examined across three altitudinal gradients within the restricted Australian alpine zone where this species has previously been shown to exhibit local adaptation across a narrow altitudinal gradient. Key Results Genetic variation across six microsatellite markers revealed genetic structuring along altitudinal transects, and a reduction in genetic variation at high and low altitude extremes relative to sites central within transects. There was less genetic variation among transect sites compared with altitudinal gradients within transects, even though distances among transects were relatively larger. Central sites within transects were less differentiated than those at extremes. Conclusions These patterns suggest higher rates of gene flow among sites at similar altitudes than along transects, a process that could assist altitudinal adaptation. Patterns of spatial autocorrelation and isolation by distance changed with altitude and may reflect altered patterns of dispersal via pollen and/or seed. There was evidence for selfing and clonality in neighbouring plants. Levels of gene flow along transects were insufficient to prevent adaptive changes in morphological traits, given previously measured levels of selection. PMID:19208670

  9. Lake-floor sediment texture and composition of a hydrothermally-active, volcanic lake, Lake Rotomahana

    NASA Astrophysics Data System (ADS)

    Pittari, A.; Muir, S. L.; Hendy, C. H.

    2016-03-01

    Young volcanic lakes undergo a transition from rapid, post-eruptive accumulation of volcaniclastic sediment to slower pelagic settling under stable lake conditions, and may also be influenced by sublacustrine hydrothermal systems. Lake Rotomahana is a young (129 year-old), hydrothermally-active, volcanic lake formed after the 1886 Tarawera eruption, and provides a unique insight into the early evolution of volcanic lake systems. Lake-bottom sediment cores, 20-46 cm in length, were taken along a transect across the lake and characterised with respect to stratigraphy, facies characteristics (i.e., grain size, componentry) and pore water silica concentrations. The sediments generally comprise two widespread facies: (i) a lower facies of light grey to grey, very fine lacustrine silt derived from the unconsolidated pyroclastic deposits that mantled the catchment area immediately after the eruption, which were rapidly reworked and redeposited into the lake basin; and (ii) an upper facies of dark, fine-sandy diatomaceous silt, that settled from the pelagic zone of the physically stable lake. Adjacent to sublacustrine hydrothermal vents, the upper dark facies is absent, and the upper part of the light grey to grey silt is replaced by a third localised facies comprised of hydrothermally altered pale yellow to yellowish brown, laminated silt with surface iron-rich encrustations. Microspheres, which are thought to be composed of amorphous silica, although some may be halloysite, have precipitated from pore water onto sediment grains, and are associated with a decrease in pore water silicon concentration. Lake Rotomahana is an example of a recently-stabilised volcanic lake, with respect to sedimentation, that shows signs of early sediment silicification in the presence of hydrothermal activity.

  10. Lake Constance

    Atmospheric Science Data Center

    2013-04-17

    ... Swiss shores of Lake Constance at the town of Rorschach. Eutrophication, or the process of nutrient enrichment, is rapidly accelerated ... of the value of Lake Constance, efforts to mitigate eutrophication were initiated in the 1970's. MISR was built and is managed ...

  11. The Effectiveness of Cattlemans Detention Basin, South Lake Tahoe, California

    USGS Publications Warehouse

    Green, Jena M.

    2006-01-01

    Lake Tahoe (Nevada-California) has been designated as an 'outstanding national water resource' by the U.S. Environmental Protection Agency, in part, for its exceptional clarity. Water clarity in Lake Tahoe, however, has been declining at a rate of about one foot per year for more than 35 years. To decrease the amount of sediment and nutrients delivered to the lake by way of alpine streams, wetlands and stormwater detention basins have been installed at several locations around the lake. Although an improvement in stormwater and snowmelt runoff quality has been measured, the effectiveness of the detention basins for increasing the clarity of Lake Tahoe needs further study. It is possible that poor ground-water quality conditions exist beneath the detention basins and adjacent wetlands and that the presence of the basins has altered ground-water flow paths to nearby streams. A hydrogeochemical and ground-water flow modeling study was done at Cattlemans detention basin, situated adjacent to Cold Creek, a tributary to Lake Tahoe, to determine whether the focusing of storm and snowmelt runoff into a confined area has (1) modified the ground-water flow system beneath the detention basin and affected transport of sediment and nutrients to nearby streams and (2) provided an increased source of solutes which has changed the distribution of nutrients and affected nutrient transport rates beneath the basin. Results of slug tests and ground-water flow modeling suggest that ground water flows unrestricted northwest across the detention basin through the meadow. The modeling also indicates that seasonal flow patterns and flow direction remain similar from year to year under transient conditions. Model results imply that about 34 percent (0.004 ft3/s) of the total ground water within the model area originates from the detention basin. Of the 0.004 ft3/s, about 45 percent discharges to Cold Creek within the modeled area downstream of the detention basin. The remaining 55 percent

  12. Groundwater, springs, and stream flow generation in an alpine meadow of a tropical glacierized catchment

    NASA Astrophysics Data System (ADS)

    Gordon, R.; Lautz, L. K.; McKenzie, J. M.; Mark, B. G.; Chavez, D.

    2013-12-01

    Melting tropical glaciers supply approximately half of dry season stream discharge in glacierized valleys of the Cordillera Blanca, Peru. The remainder of streamflow originates as groundwater stored in alpine meadows, moraines and talus slopes. A better understanding of the dynamics of alpine groundwater, including sources and contributions to streamflow, is important for making accurate estimates of glacial inputs to the hydrologic budget, and for our ability to make predictions about future water resources as glaciers retreat. Our field study, conducted during the dry season in the Llanganuco valley, focused on a 0.5-km2 alpine meadow complex at 4400 m elevation, which includes talus slopes, terminal moraines, and a debris fan. Two glacial lakes and springs throughout the complex feed a network of stream channels that flow across the meadow (~2 km total length). We combined tracer measurements of stream and spring discharge and groundwater-surface water exchange with synoptic sampling of water isotopic and geochemical composition, in order to characterize and quantify contributions to streamflow from different geomorphic features. Surface water inputs to the stream channels totaled 58 l/s, while the stream gained an additional 57 l/s from groundwater inputs. Water chemistry is primarily controlled by flowpath type (surface/subsurface) and length, as well as bedrock lithology, while stable water isotopic composition appears to be controlled by water source (glacial lake, meadow or deep groundwater). Stream water chemistry is most similar to meadow groundwater springs, but isotopic composition suggests that the majority of stream water, which issues from springs at the meadow/fan interface, is from the same glacial source as the up-gradient lake. Groundwater sampled from piezometers in confined meadow aquifers is unique in both chemistry and isotopic composition, but does not contribute a large percentage of stream water exiting this small meadow, as quantified by

  13. Lake Powell

    NASA Image and Video Library

    2007-09-20

    The white ring around Lake Powell tells the story. The surface is down 98 feet. This is critical, because Powell, Lake Mead, and other lakes along the Colorado River provide water for millions of people in five states. We are in the eighth year of a drought on the Colorado River. This year was the driest year ever reported in Southern California, and there is a severe drought in Northern California, down to less than 30-percent of snow pack. This ASTER image of part of Lake Powell was acquired in 2001. The gray area depicts the shrunken, reduced 2007 lake extent compared to the extended, larger black area in 2001. The image covers an area of 24 x 30 km, and is centered near 37.1 degrees north latitude, 111.3 degrees west longitude. This image from NASA Terra satellite. http://photojournal.jpl.nasa.gov/catalog/PIA10614

  14. 75 FR 30366 - Alpine County Resource Advisory Committee (RAC)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-01

    ... Alpine County at the Alpine Early Learning Center, 100 Foothill Road, Markleeville, CA 96120. FOR FURTHER... District, 1536 S. Carson Street, Carson City, NV 89701 (775) 884-8140; E-Mail danielmorris@fs.fed.us... opportunity to address the Committee at that time. Dated: May 21, 2010. Genny E. Wilson, Designated...

  15. 75 FR 74681 - Alpine County Resource Advisory Committee (RAC)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-01

    ... will be held in Alpine County at the Alpine Early Learning Center, 100 Foothill Road, Markleeville, CA... Forest, Carson Ranger District, 1536 S. Carson Street, Carson City, NV 89701 (775) 884-8140; E-MAIL... Committee at that time. Dated: November 22, 2010. Genny E. Wilson, Designated Federal Officer. BILLING...

  16. 75 FR 16069 - Alpine County Resource Advisory Committee (RAC)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-31

    ... Alpine County at the Alpine Early Learning Center, 100 Foothill Road, Markleeville, CA 96120. FOR FURTHER... District, 1536 S. Carson Street, Carson City, NV 89701 (775) 352-1240; E-MAIL mbonesteel@fs.fed.us.... Genny E. Wilson, Designated Federal Officer. BILLING CODE 3410-11-M...

  17. Water resources: Research network to track alpine water

    USDA-ARS?s Scientific Manuscript database

    The water cycle in alpine environments worldwide supplies fresh water to vast downstream areas inhabited by more than half of humanity. The International Network for Alpine Research Catchment Hydrology (INARCH) was launched this year by the Global Energy and Water Exchanges project of the World Clim...

  18. High diversity of protistan plankton communities in remote high mountain lakes in the European Alps and the Himalayan mountains

    PubMed Central

    Kammerlander, Barbara; Breiner, Hans-Werner; Filker, Sabine; Sommaruga, Ruben; Sonntag, Bettina; Stoeck, Thorsten

    2015-01-01

    We analyzed the genetic diversity (V4 region of the 18S rRNA) of planktonic microbial eukaryotes in four high mountain lakes including two remote biogeographic regions (the Himalayan mountains and the European Alps) and distinct habitat types (clear and glacier-fed turbid lakes). The recorded high genetic diversity in these lakes was far beyond of what is described from high mountain lake plankton. In total, we detected representatives from 66 families with the main taxon groups being Alveolata (55.0% OTUs97%, operational taxonomic units), Stramenopiles (34.0% OTUs97%), Cryptophyta (4.0% OTUs97%), Chloroplastida (3.6% OTUs97%) and Fungi (1.7% OTUs97%). Centrohelida, Choanomonada, Rhizaria, Katablepharidae and Telonema were represented by <1% OTUs97%. Himalayan lakes harbored a higher plankton diversity compared to the Alpine lakes (Shannon index). Community structures were significantly different between lake types and biogeographic regions (Fisher exact test, P < 0.01). Network analysis revealed that more families of the Chloroplastida (10 vs 5) and the Stramenopiles (14 vs 8) were found in the Himalayan lakes than in the Alpine lakes and none of the fungal families was shared between them. Biogeographic aspects as well as ecological factors such as water turbidity may structure the microbial eukaryote plankton communities in such remote lakes. PMID:25764458

  19. High diversity of protistan plankton communities in remote high mountain lakes in the European Alps and the Himalayan mountains.

    PubMed

    Kammerlander, Barbara; Breiner, Hans-Werner; Filker, Sabine; Sommaruga, Ruben; Sonntag, Bettina; Stoeck, Thorsten

    2015-04-01

    We analyzed the genetic diversity (V4 region of the 18S rRNA) of planktonic microbial eukaryotes in four high mountain lakes including two remote biogeographic regions (the Himalayan mountains and the European Alps) and distinct habitat types (clear and glacier-fed turbid lakes). The recorded high genetic diversity in these lakes was far beyond of what is described from high mountain lake plankton. In total, we detected representatives from 66 families with the main taxon groups being Alveolata (55.0% OTUs 97%, operational taxonomic units), Stramenopiles (34.0% OTUs 97%), Cryptophyta (4.0% OTUs 97%), Chloroplastida (3.6% OTUs 97%) and Fungi (1.7% OTUs 97%). Centrohelida, Choanomonada, Rhizaria, Katablepharidae and Telonema were represented by <1% OTUs 97%. Himalayan lakes harbored a higher plankton diversity compared to the Alpine lakes (Shannon index). Community structures were significantly different between lake types and biogeographic regions (Fisher exact test, P < 0.01). Network analysis revealed that more families of the Chloroplastida (10 vs 5) and the Stramenopiles (14 vs 8) were found in the Himalayan lakes than in the Alpine lakes and none of the fungal families was shared between them. Biogeographic aspects as well as ecological factors such as water turbidity may structure the microbial eukaryote plankton communities in such remote lakes.

  20. Zooplankton communities and Bythotrephes longimanus in lakes of the montane region of the northern Alps

    PubMed Central

    Horváth, Zsófia; Vad, Csaba F.; Preiler, Christian; Birtel, Julia; Matthews, Blake; Ptáčníková, Radka; Ptáčník, Robert

    2017-01-01

    Abstract Lakes in the Alps represent a considerable fraction of nutrient-poor lakes in Central Europe, with unique biodiversity and ecosystem properties. Although some individual lakes are well studied, less knowledge is available on large-scale patterns essential to general understanding of their functioning. Here, we aimed to describe crustacean zooplankton communities (Cladocera, Copepoda) and identify their environmental drivers in the pelagic zone of 54 oligotrophic lakes in the montane region of the Alps (400–1200 m) in Austria, Germany, and Switzerland, covering a spatial scale of 650 km. Moreover, we aimed to provide data on the distribution and ecological requirements of the North American invader Bythotrephes longimanus in its Central European native range. Communities were mainly dominated by widespread species typical of lowland habitats, and only a few true specialists of oligotrophic alpine lakes were present. The most frequent taxa were the Daphnia longispina complex and Eudiaptomus gracilis, with 48 and 45 occurrences, respectively. Species richness decreased with altitude and increased with lake area. The main structuring factors of community composition were chlorophyll a concentration and depth, which drove an apparent separation of mesotrophic and oligotrophic communities. Bythotrephes had 13 occurrences, showing a preference for deep oligotrophic lakes. Its presence was not coupled with lower crustacean species richness, as was repeatedly observed in North America. Additionally, it frequently co-occurred with the other large predatory cladoceran, Leptodora kindtii. B. longimanus might be considered a truly montane species in Central Europe, given its absence in lowland and alpine lakes. PMID:28824797

  1. Nitrogen and carbon storage in alpine plants.

    PubMed

    Monson, Russell K; Rosenstiel, Todd N; Forbis, Tara A; Lipson, David A; Jaeger, Charles H

    2006-02-01

    Alpine plants offer unique opportunities to study the processes and economics of nutrient storage. The short alpine growing season forces rapid completion of plant growth cycles, which in turn causes competition between vegetative and reproductive growth sinks during the early part of the growing season. Mobilization of stored nitrogen and carbon reserves facilitates competing sinks and permits successful completion of reproduction before the onset of winter stress. We discuss the theoretical framework for assessing the costs and benefits of nutrient storage in alpine plants in order to lay the foundation for interpretation of observations. A principal point that has emerged from past theoretical treatments is the distinction between reserve storage, defined as storage that occurs with a cost to growth, and resource accumulation, defined as storage that occurs when resource supply exceeds demand, and thus when there is no cost to growth. We then discuss two case studies, one already published and one not yet published, pertaining to the storage and utilization of nitrogen and carbon compounds in alpine plants from Niwot Ridge, Colorado. In the first case, we tested the hypothesis that the seasonal accumulation of amino acids in the rhizome of N-fertilized plants of Bistorta bistortoides provides an advantage to the plant by not imposing a cost to growth at the time of accumulation, but providing a benefit to growth when the accumulated N is remobilized. We show that, as predicted, there is no cost during N accumulation but, not as predicted, there is no benefit to future growth. In the presence of N accumulation, reliance on stored N for growth increases, but reliance on current-season, soil-derived N decreases; thus the utilization of available N in this species is a 'zero sum' process. Inherent meristematic constraints to growth cause negative feedback that limits the utilization of accumulated N and precludes long-term advantages to this form of storage. In the

  2. Carbon sequestration in two alpine soils on the Tibetan Plateau.

    PubMed

    Tian, Yu-Qiang; Xu, Xing-Liang; Song, Ming-Hua; Zhou, Cai-Ping; Gao, Qiong; Ouyang, Hua

    2009-09-01

    Soil carbon sequestration was estimated in a conifer forest and an alpine meadow on the Tibetan Plateau using a carbon-14 radioactive label provided by thermonuclear weapon tests (known as bomb-(14)C). Soil organic matter was physically separated into light and heavy fractions. The concentration spike of bomb-(14)C occurred at a soil depth of 4 cm in both the forest soil and the alpine meadow soil. Based on the depth of the bomb-(14)C spike, the carbon sequestration rate was determined to be 38.5 g C/m(2) per year for the forest soil and 27.1 g C/m(2) per year for the alpine meadow soil. Considering that more than 60% of soil organic carbon (SOC) is stored in the heavy fraction and the large area of alpine forests and meadows on the Tibetan Plateau, these alpine ecosystems might partially contribute to "the missing carbon sink".

  3. High bacterial diversity in epilithic biofilms of oligotrophic mountain lakes.

    PubMed

    Bartrons, Mireia; Catalan, Jordi; Casamayor, Emilio O

    2012-11-01

    Benthic microbial biofilms attached to rocks (epilithic) are major sites of carbon cycling and can dominate ecosystem primary production in oligotrophic lakes. We studied the bacterial community composition of littoral epilithic biofilms in five connected oligotrophic high mountain lakes located at different altitudes by genetic fingerprinting and clone libraries of the 16S rRNA gene. Different intra-lake samples were analyzed, and consistent changes in community structure (chlorophyll a and organic matter contents, and bacterial community composition) were observed along the altitudinal gradient, particularly related with the location of the lake above or below the treeline. Epilithic biofilm genetic fingerprints were both more diverse among lakes than within lakes and significantly different between montane (below the tree line) and alpine lakes (above the tree line). The genetic richness in the epilithic biofilm was much higher than in the plankton of the same lacustrine area studied in previous works, with significantly idiosyncratic phylogenetic composition (specifically distinct from lake plankton or mountain soils). Data suggest the coexistence of aerobic, anaerobic, phototrophic, and chemotrophic microorganisms in the biofilm, Bacteroidetes and Cyanobacteria being the most important bacterial taxa, followed by Alpha-, Beta-, Gamma-, and Deltaproteobacteria, Chlorobi, Planctomycetes, and Verrucomicrobia. The degree of novelty was especially high for epilithic Bacteroidetes, and up to 50 % of the sequences formed monophyletic clusters distantly related to any previously reported sequence. More than 35 % of the total sequences matched at <95 % identity to any previously reported 16S rRNA gene, indicating that alpine epilithic biofilms are unexplored habitats that contain a substantial degree of novelty within a short geographical distance. Further research is needed to determine whether these communities are involved in more biogeochemical pathways than

  4. 3D cartography of the Alpine Arc

    NASA Astrophysics Data System (ADS)

    Vouillamoz, N.; Sue, C.; Champagnac, J. D.; Calcagno, P.

    2012-04-01

    We present a 3D cartography of the alpine arc, a highly non-cylindrical mountain belt, built using the 3D GeoModeller of the BRGM (French geological survey). The model allows to handle the large-scale 3D structure of seventeen major crustal units of the belt (from the lower crust to the sedimentary cover nappes), and two main discontinuities (the Insubric line and the Crustal Penninic Front). It provides a unique document to better understand their structural relationships and to produce new sections. The study area comprises the western alpine arc, from the Jura to the Northwest, up to the Bergell granite intrusion and the Lepontine Dome to the East, and is limited to the South by the Ligurian basin. The model is limited vertically 10 km above sea level at the top, and the moho interface at the bottom. We discarded the structural relationships between the Alps sensus stricto and the surrounding geodynamic systems such as the Rhine graben or the connection with the Apennines. The 3D-model is based on the global integration of various data such as the DEM of the Alps, the moho isobaths, the simplified geological and tectonic maps of the belt, the crustal cross-sections ECORS-CROP and NFP-20, and complementary cross-sections specifically built to precise local complexities. The database has first been integrated in a GIS-project to prepare their implementation in the GeoModeller, by homogenizing the different spatial referencing systems. The global model is finally interpolated from all these data, using the potential field method. The final document is a new tri-dimentional cartography that would be used as input for further alpine studies.

  5. Inferring hydraulic properties of alpine aquifers from the propagation of diurnal snowmelt signals

    NASA Astrophysics Data System (ADS)

    Kurylyk, Barret L.; Hayashi, Masaki

    2017-05-01

    Alpine watersheds source major rivers throughout the world and supply essential water for irrigation, human consumption, and hydroelectricity. Coarse depositional units in alpine watersheds can store and transmit significant volumes of groundwater and thus augment stream discharge during the dry season. These environments are typically data scarce, which has limited the application of physically based models to investigate hydrologic sensitivity to environmental change. This study focuses on a coarse alpine talus unit within the Lake O'Hara watershed in the Canadian Rockies. We investigate processes controlling the hydrologic functioning of the talus unit using field observations and a numerical groundwater flow model driven with a distributed snowmelt model. The model hydraulic parameters are adjusted to investigate how these properties influence the propagation of snowmelt-induced diurnal signals. The model results expectedly demonstrate that diurnal signals at the talus outlet are progressively damped and lagged with lower hydraulic conductivity and higher specific yield. The simulations further indicate that the lag can be primarily controlled by a higher hydraulic conductivity upper layer, whereas the damping can be strongly influenced by a lower hydraulic conductivity layer along the base of the talus. The simulations specifically suggest that the talus slope can be represented as a two layer system with a high conductivity zone (0.02 m s-1) overlying a 10 cm thick lower conductivity zone (0.002 m s-1). This study demonstrates that diurnal signals can be used to elucidate the hydrologic functioning and hydraulic properties of shallow aquifers and thus aid in the parameterization of hydrological models.

  6. Is leg compression beneficial for alpine skiers?

    PubMed Central

    2013-01-01

    Background This study examined the effects of different levels of compression (0, 20 and 40 mmHg) produced by leg garments on selected psycho-physiological measures of performance while exposed to passive vibration (60 Hz, amplitude 4-6 mm) and performing 3-min of alpine skiing tuck position. Methods Prior to, during and following the experiment the electromygraphic (EMG) activity of different muscles, cardio-respiratory data, changes in total hemoglobin, tissue oxygenation and oscillatory movement of m. vastus lateralis, blood lactate and perceptual data of 12 highly trained alpine skiers were recorded. Maximal isometric knee extension and flexion strength, balance, and jumping performance were assessed before and after the experiment. Results The knee angle (−10°) and oscillatory movement (−20-25.5%) were lower with compression (P < 0.05 in all cases). The EMG activities of the tibialis anterior (20.2-28.9%), gastrocnemius medialis (4.9-15.1%), rectus femoris (9.6-23.5%), and vastus medialis (13.1-13.7%) muscles were all elevated by compression (P < 0.05 in all cases). Total hemoglobin was maintained during the 3-min period of simulated skiing with 20 or 40 mmHg compression, but the tissue saturation index was lower (P < 0.05) than with no compression. No differences in respiratory parameters, heart rate or blood lactate concentration were observed with or maximal isometric knee extension and flexion strength, balance, and jumping performance following simulated skiing for 3 min in the downhill tuck position were the same as in the absence of compression. Conclusions These findings demonstrate that with leg compression, alpine skiers could maintain a deeper tuck position with less perceived exertion and greater deoxygenation of the vastus lateralis muscle, with no differences in whole-body oxygen consumption or blood lactate concentration. These changes occurred without compromising maximal leg strength, jumping performance or balance

  7. Alpine vegetation communities and the alpine-treeline ecotone boundary in New England as biomonitors for climate change

    Treesearch

    Kenneth D. Kimball; Douglas M. Weihrauch

    2000-01-01

    This study mapped and analyzed the alpine-treeline ecotone (ATE) boundary and alpine plant communities on the Presidential Range, New Hampshire and Mount Katahdin, Maine. These are sensitive biomonitoring parameters for plant community responses to climatic change. The ATE boundary spans a considerable elevational range, suggesting that shorter growing seasons with...

  8. Real-estate lakes

    USGS Publications Warehouse

    Rickert, David A.; Spieker, Andrew Maute

    1971-01-01

    Since the dawn of civilization waterfront land has been an irresistible attraction to man. Throughout history he has sought out locations fronting on oceans, rivers, and lakes. Originally sought for proximity .to water supply and transportation, such locations are now sought more for their esthetic qualities and for recreation. Usable natural waterfront property is limited, however, and the more desirable sites in many of our urban areas have already been taken. The lack of available waterfront sites has led to the creation of many artificial bodies of water. The rapid suburbanization that has characterized urban growth in America since the end of World War II, together with increasing affluence and le-isure time, has created a ready market for waterfront property. Accordingly, lake-centered subdivisions and developments dot the suburban landscape in many of our major urban areas. Literally thousands of lakes surrounded by homes have materialized during this period of rapid growth. Recently, several "new town" communities have been planned around this lake-centered concept. A lake can be either an asset or a liaoility to a community. A clean, clear, attractively landscaped lake is a definite asset, whereas a weed-choked, foul-smelling mudhole is a distinct liability. The urban environment poses both problems and imaginative opportunities in the development of lakes. Creation of a lake causes changes in all aspects of the environment. Hydrologic systems and ecological patterns are usually most severely altered. The developer should be aware of the potential changes; it is not sufficient merely to build a dam across a stream or to dig a hole in the ground. Development of Gl a successful lake requires careful planning for site selection and design, followed by thorough and cc ntinual management. The purpose of this report is to describe the characteristics of real-estate lakes, to pinpoint potential pmblems, and to suggest possible planning and management guidelines

  9. Great Lakes

    NASA Image and Video Library

    2017-09-28

    Bands of lake effect snow drift eastward from the western Great Lakes in this true-color image captured by the NOAA/NASA Suomi NPP satellite's Visible Infrared Imaging Radiometer Suite (VIIRS) instrument on January 5, 2017. National Weather Service forecasters expect light to moderate lake effect snow showers to continue throughout the day today and into Saturday (1/7). Lake-effect snow forms when cold air passes over the warmer waters of a lake. This causes some lake water to evaporate into the air and warm it. This warmer, wetter air rises and cools as it moves away from the lake. When it cools, it releases that moisture and, if it’s cold enough, that moisture turns into snow. Although true-color images like this may appear to be photographs of Earth, they aren't. They are created by combining data from the three color channels on the VIIRS instrument sensitive to the red, green and blue (or RGB) wavelengths of light into one composite image. In addition, data from several other channels are often also included to cancel out or correct atmospheric interference that may blur parts of the image. Credit: NOAA/NASA/Suomi NPP via NOAA's Environmental Visualization Laboratory

  10. Climatic changes and anthropogenic pollution as evidenced by two Alpine lacustrine records, Switzerland.

    NASA Astrophysics Data System (ADS)

    Thevenon, Florian; Poté, John; Guédron, Stéphane; Adatte, Thierry; Chiaradia, Massimo; Loizeau, Jean-Luc; Spangenberg, Jorge; Anselmetti, Flavio S.

    2010-05-01

    This study aims to provide high-resolution records of climatic changes and human impacts on two different Alpine environments: Lake Lucerne is a large (114 km2) lake located at 434 m asl in Central Switzerland, whereas Meidsee is a small (<1 km2) remote lake located at 2661 m asl in the Southern Alps. Two short gravity cores (1.2 and 1.6 m) recovering the industrial history and the last millennia were sampled with a resolution of 1 cm, and investigated for organic (13δC, 15δN, C/N) and/or inorganic (δ13C, δ18O) matter contents, and elemental composition (REE compositions, trace elements, and heavy metals). Both sites exhibit 1) rapid hydrological changes related to variations in winter precipitations, and 2) increases in atmospheric pollution due to human activities. Lead enrichment factors combined to changes in lead isotopic composition (206Pb/207Pb ratio) are used to distinguish natural from anthropogenic sources. The greatest mercury and lead atmospheric emissions occurred during the twentieth century, resulting from the extensive combustion of fossil coal and petroleum in Europe. Although the highest heavy metals fluxes are synchronous with major anthropogenic changes (e.g. Roman mining, industrial revolution), proxies show that in absence of such events, the heavy metals deposition in the sedimentary records is primarily influenced by sedimentological processes linked to climate variations (i.e. runoff and erosion processes).

  11. Conifer density within lake catchments predicts fish mercury concentrations in remote subalpine lakes

    USGS Publications Warehouse

    Eagles-Smith, Collin A.; Herring, Garth; Johnson, Branden L.; Graw, Rick

    2016-01-01

    Remote high-elevation lakes represent unique environments for evaluating the bioaccumulation of atmospherically deposited mercury through freshwater food webs, as well as for evaluating the relative importance of mercury loading versus landscape influences on mercury bioaccumulation. The increase in mercury deposition to these systems over the past century, coupled with their limited exposure to direct anthropogenic disturbance make them useful indicators for estimating how changes in mercury emissions may propagate to changes in Hg bioaccumulation and ecological risk. We evaluated mercury concentrations in resident fish from 28 high-elevation, sub-alpine lakes in the Pacific Northwest region of the United States. Fish total mercury (THg) concentrations ranged from 4 to 438 ng/g wet weight, with a geometric mean concentration (±standard error) of 43 ± 2 ng/g ww. Fish THg concentrations were negatively correlated with relative condition factor, indicating that faster growing fish that are in better condition have lower THg concentrations. Across the 28 study lakes, mean THg concentrations of resident salmonid fishes varied as much as 18-fold among lakes. We used a hierarchal statistical approach to evaluate the relative importance of physiological, limnological, and catchment drivers of fish Hg concentrations. Our top statistical model explained 87% of the variability in fish THg concentrations among lakes with four key landscape and limnological variables: catchment conifer density (basal area of conifers within a lake's catchment), lake surface area, aqueous dissolved sulfate, and dissolved organic carbon. Conifer density within a lake's catchment was the most important variable explaining fish THg concentrations across lakes, with THg concentrations differing by more than 400 percent across the forest density spectrum. These results illustrate the importance of landscape characteristics in controlling mercury bioaccumulation in fish.

  12. Conifer density within lake catchments predicts fish mercury concentrations in remote subalpine lakes.

    PubMed

    Eagles-Smith, Collin A; Herring, Garth; Johnson, Branden; Graw, Rick

    2016-05-01

    Remote high-elevation lakes represent unique environments for evaluating the bioaccumulation of atmospherically deposited mercury through freshwater food webs, as well as for evaluating the relative importance of mercury loading versus landscape influences on mercury bioaccumulation. The increase in mercury deposition to these systems over the past century, coupled with their limited exposure to direct anthropogenic disturbance make them useful indicators for estimating how changes in mercury emissions may propagate to changes in Hg bioaccumulation and ecological risk. We evaluated mercury concentrations in resident fish from 28 high-elevation, sub-alpine lakes in the Pacific Northwest region of the United States. Fish total mercury (THg) concentrations ranged from 4 to 438 ng/g wet weight, with a geometric mean concentration (±standard error) of 43 ± 2 ng/g ww. Fish THg concentrations were negatively correlated with relative condition factor, indicating that faster growing fish that are in better condition have lower THg concentrations. Across the 28 study lakes, mean THg concentrations of resident salmonid fishes varied as much as 18-fold among lakes. We used a hierarchal statistical approach to evaluate the relative importance of physiological, limnological, and catchment drivers of fish Hg concentrations. Our top statistical model explained 87% of the variability in fish THg concentrations among lakes with four key landscape and limnological variables: catchment conifer density (basal area of conifers within a lake's catchment), lake surface area, aqueous dissolved sulfate, and dissolved organic carbon. Conifer density within a lake's catchment was the most important variable explaining fish THg concentrations across lakes, with THg concentrations differing by more than 400 percent across the forest density spectrum. These results illustrate the importance of landscape characteristics in controlling mercury bioaccumulation in fish.

  13. Dilatant plasticity applied to Alpine collision: ductile void growth in the intraplate area beneath the Eifel volcanic field

    NASA Astrophysics Data System (ADS)

    Regenauer-Lieb, Klaus

    1998-11-01

    The Eifel is located in the middle of the European plate far away from any active plate boundary, yet it appears to be a maximum of intraplate tectonic activity. A map of intraplate seismic energy flow shows that the Eifel is linked to the Alpine collisional belt via a narrow seismoactive shear zone. Two parallel Quaternary volcanic zones (the East Eifel Volcanic Zone EEVZ and the West Eifel Volcanic Zone WEVZ) line up with the seismogenic shear zone. Xenoliths ejected from these volcanic lineaments indicate upper mantle shearing by dynamic recrystallization textures and metasomatized chemistry. Important CO 2-dominated mantle degassing observed in mineral springs, lakes or dry degassing suggests a presently ongoing flushing of brines. Here, the hypothesis of intraplate ductile void growth as a consequence of the Alpine collision is tested by finite element models. It is shown that in the tensile domain of Alpine collision, a small amount of dilatancy along shear bands in the upper mantle and lower crust can open pathways for fluids, thus transfer of melts and gases through the lithosphere and thereby controls mantle metasomatism along highly oriented mantle shear zones.

  14. Phospholipid Analyses for Microbial Community Composition in Alpine Acid Rock Drainage

    NASA Astrophysics Data System (ADS)

    Webster, C. E.; Tapp, J. B.; Pfiffner, S. M.

    2008-12-01

    This project is examining factors of non-anthropogenic acid rock drainage that influence microbial community composition in the Peekaboo Gulch drainage basin (Sawatch Range, Colorado). At this site, natural acid rock drainage outflows from acidic springs (pH=2.6) on Red Mountain. The acid drainage converges with South Fork Lake Creek (pH ~ 7.0, prior to convergence) two miles down gradient. Sediment samples were collected across confluences with gradient of pH, temperature, conductivity and metal concentration. In-situ parameter measurements ranged from 2.3 to 7.9 of pH, 3.8 to 16.6 degree Celsius for temperature, and 34.9 to 1820 for conductivity. Biomass as measured by phospholipids ranged from 280 to 95,900 pmol/g sediment. The only relationship between the in situ parameters and the phospholipid profiles is a weak positive correlation between pH and branched monounsaturated fatty acid methyl esters in that at a pH greater than 5.0 these fatty acid methyl esters were detected. The phospholipid profiles were diverse across the samples. These profiles changed with respect to the spatial relationship within the drainage pattern. The highest alpine samples contained greater relative abundances of monounsaturated fatty acid methyl esters compared to the lower alpine samples. Microbial community profiles shifted at each confluence depending on water source chemistry. Continuing research is needed to determine other biogeochemical factors that may influence these community shifts.

  15. Hydrology of Hunters Lake, Hernando County, Florida

    USGS Publications Warehouse

    Henderson, S.E.

    1986-01-01

    The size and shape of Hunters Lake, Florida has been significantly altered by development of the surrounding Spring Hill residential community. The lake is the largest in Hernando County, enlarged by lakeshore excavation and connection to nearby ponds to an area of 360 acres at an average stage of 17.2 ft above sea level. Hunters Lake is naturally a closed lake, but development of Spring Hill has resulted in a surface water outflow from the lake in its southwest corner. Inflow to the lake could occur on the east side during extreme high-water periods. The karst terrain of the Hunters Lake area is internally drained through permeable soils, depressions, and sinkholes, and natural surface drainage is absent. The underlying Floridan aquifer system is unconfined except locally near coastal springs. Flow in the groundwater system is to the west regionally and to the southwest in the immediate area of Hunters Lake. Water level gradients in the groundwater system increase from 1.4 ft/mi east of the lake to about 8 ft/mi southwest of the lake. Hunters Lake is hydraulically connected to the groundwater system, receiving groundwater on the northeast side and losing water to the groundwater system on the southwest side. This close relationship with the groundwater system is demonstrated by graphical and numerical comparison of Hunters Lake stage with water levels in nearby groundwater sites. During 1965-84, the stage of Hunters Lake fluctuated between 12.48 and 20.7 ft above sea level. Because area lakes are all directly affected by groundwater levels, they also show a close relationship with water levels in Hunters Lake. Analysis of water quality data for Hunters Lake indicates that the water of the lake is a soft calcium bicarbonate type with ionic concentrations higher than in water from nearby shallow wells and lower than in water from the Upper Floridan aquifer. Samples collected in 1981-1983 indicate slightly higher levels of ionic concentration than in 1965

  16. Lake Tapps tephra: An early Pleistocene stratigraphic marker in the Puget Lowland, Washington

    USGS Publications Warehouse

    Westgate, J.A.; Easterbrook, D.J.; Naeser, N.D.; Carson, R.J.

    1987-01-01

    The rhyolitic Lake Tapps tephra was deposited about 1.0 myr ago, shortly after culmination of the early phase of the Salmon Springs Glaciation in the Puget Lowland. It is contained within sediments that were deposited in ponds or lakes in front of the reteating glacier. An herb-dominated tundra existed in the southern Puget Lowland at that time. Lake Tapps tephra is most likely the product of an eruption that in part was phreatomagmatic. It forms an early Pleistocene stratigraphic marker across the southern sector of the Puget Lowland and provides a link between Puget lobe sediments of the Cordilleran Ice Sheet and sediments deposited by Olympic alpine glaciers. ?? 1987.

  17. Resource partitioning in two heterochronic populations of Greek Alpine newts, Triturus alpestris veluchiensis

    NASA Astrophysics Data System (ADS)

    Denoël, Mathieu; Schabetsberger, Robert

    2003-04-01

    Current ecological models suggest that the maintenance of trophic polymorphisms is favoured by a different resource use in alternative morphs. Facultative paedomorphosis in newts is an example of phenotypic variation as paedomorphs retain morphological larval traits, such as gills and gill slits. The aim of this study was to find out whether heterochronic morphs occupy particular micro-habitats and focus on specific prey items. Resource partitioning was found between morphs. It concerns mainly food selection with paedomorphs preying more on plankton and less on terrestrial invertebrates than metamorphs. Some habitat specializations were also found with metamorphs being more abundant at the water surface than paedomorphs. Diel variation in habitat use of the two different morphs was minimal. Polymorphism allows Alpine newts to exploit the different resources in the lakes in order to minimize intraspecific competition, but the extent of resource partitioning depends on habitat characteristics.

  18. Effects of acid precipitation on reproduction in alpine plant species. [Erythronium grandiflorum; Aquilegia caerulea

    SciTech Connect

    McKenna, M.A.; Hille-Salgueiro, M.; Musselman, R.C. Dept. of Agriculture, Fort Collins, CO )

    1990-01-01

    A series of experiments were designed to determine the impact of acid rain on plant reproductive processes, a critical component of a species life history. Research was carried out in herbaceous alpine communities at the USDA (United States Department of Agriculture) Forest Service Glacier Lakes Ecosystem Experiments Site in the Snowy Mts. of Wyoming. A range of species were surveyed to monitor the sensitivity of pollen to acidification during germination and growth, and all species demonstrated reduced in vitro pollen germination in acidified media. Field pollinations were carried out in Erythronium grandiflorum and Aquilegia caerulea to determine the reproductive success of plants exposed to simulated ambient precipitation (pH 5.6) or simulated acid precipitation (pH 3.6) prior to pollination. In Erythronium, no differences were observed in seed set and seed weight of fruits resulting from the two pollination treatments. In Aquilegia, fruits resulting from the acid spray treatment produced fewer seeds and lighter seeds.

  19. Simulation of Natural Acid Sulfate Weathering in an Alpine Watershed

    NASA Astrophysics Data System (ADS)

    Bassett, R. L.; Miller, William R.; McHugh, John; Catts, John G.

    1992-09-01

    Streams with acidic sulfate compositions (pH less than 3.5) are naturally generated in the alpine Geneva Creek Basin of the southern Rocky Mountains, an area underlain by Proterozoic metamorphic and igneous rocks that are intruded by Tertiary felsic stocks with associated pyritic alteration. These naturally acidic waters are similar in composition to more familiar man-made acid mine waters or to surface waters acidified by sulfate precipitation. Detailed study of the stream compositions has revealed the principal reactions driving the weathering process and was used to estimate the relative effects of snowpack ionic input versus the solute contribution from acid attack in soil zones and groundwater. In the Geneva Creek Basin, atmospheric sources of solute represent a minor component to the stream water composition, except for chloride, which can be used to determine the fraction of contribution. The weathering process is a balance between oxidation of sulfides, dissolution of silicates, formation of the clay minerals vermiculite, kaolinite, and smectite, carbonate neutralization, and precipitation of ferric and aluminum oxyhydroxides and aluminum sulfate. The chemical analyses of snow samples, multiple samples of water from Geneva Creek and its tributaries, and the composition of primary and secondary minerals identified in the basin serve as input to a mass balance geochemical model, which facilitates the interpretation of the principal geochemical processes.

  20. Metabolic Profiling of Alpine and Ecuadorian Lichens.

    PubMed

    Mittermeier, Verena K; Schmitt, Nicola; Volk, Lukas P M; Suárez, Juan Pablo; Beck, Andreas; Eisenreich, Wolfgang

    2015-10-01

    Non-targeted ¹H-NMR methods were used to determine metabolite profiles from crude extracts of Alpine and Ecuadorian lichens collected from their natural habitats. In control experiments, the robustness of metabolite detection and quantification was estimated using replicate measurements of Stereocaulon alpinum extracts. The deviations in the overall metabolite fingerprints were low when analyzing S. alpinum collections from different locations or during different annual and seasonal periods. In contrast, metabolite profiles observed from extracts of different Alpine and Ecuadorian lichens clearly revealed genus- and species-specific profiles. The discriminating functions determining cluster formation in principle component analysis (PCA) were due to differences in the amounts of genus-specific compounds such as sticticin from the Sticta species, but also in the amounts of ubiquitous metabolites, such as sugar alcohols or trehalose. However, varying concentrations of these metabolites from the same lichen species e.g., due to different environmental conditions appeared of minor relevance for the overall cluster formation in PCA. The metabolic clusters matched phylogenetic analyses using nuclear ribosomal DNA (nrDNA) internal transcribed spacer (ITS) sequences of lichen mycobionts, as exemplified for the genus Sticta. It can be concluded that NMR-based non-targeted metabolic profiling is a useful tool in the chemo-taxonomy of lichens. The same approach could also facilitate the discovery of novel lichen metabolites on a rapid and systematical basis.

  1. Quantified sensitivity of lakes to record historic earthquakes: Implications for paleoseismology

    NASA Astrophysics Data System (ADS)

    Wilhelm, Bruno; Nomade, Jerome; Crouzet, Christian; Litty, Camille; Belle, Simon; Rolland, Yann; Revel, Marie; Courboulex, Françoise; Arnaud, Fabien; Anselmetti, Flavio S.

    2015-04-01

    Seismic hazard assessment is a challenging issue for modern societies. A key parameter to be estimated is the recurrence interval of damaging earthquakes. In moderately active seismo-tectonic regions, this requires the establishment of earthquake records long enough to be relevant, i.e. far longer than historical observations. Here we investigate how lake sediments can be used for this purpose and quantify the conditions that enable earthquake recording. For this purpose, (i) we studied nine lake-sediment sequences to reconstruct mass-movement chronicles in different settings of the French Alpine range and (ii) we compared the chronicles to the well-documented earthquake history over the last five centuries. The studied lakes are all small alpine-type lakes based directly on bedrock. All lake sequences have been studied following the same methodology; (i) a multi-core approach to well understand the sedimentary processes within the lake basins, (ii) a high-resolution lithological and grain-size characterization and (iii) a dating based on short-lived radionuclide measurements, lead contaminations and radiocarbon ages. We identified 40 deposits related to 26 mass-movement (MM) occurrences. 46% (12 on 26) of the MMs are synchronous in neighbouring lakes, supporting strongly an earthquake origin. In addition, the good agreement between MMs ages and historical earthquake dates suggests an earthquake trigger for 88% (23 on 26) of them. Related epicenters are always located at distances of less than 100 km from the lakes and their epicentral MSK intensity ranges between VII and IX. However, the number of earthquake-triggered MMs varies between lakes of a same region, suggesting a gradual sensitivity of the lake sequences towards earthquake shaking, i.e. distinct lake-sediment slope stabilities. The quantification of this earthquake sensitivity and the comparison to the lake system and sediment characteristics suggest that the primary factor explaining this variability is

  2. Analysis of Poyang Lake water balance and its indication of river-lake interaction.

    PubMed

    Zhang, Zengxin; Huang, Yuhan; Xu, Chong-Yu; Chen, Xi; Moss, Elica M; Jin, Qiu; Bailey, Alisha M

    2016-01-01

    In recent years, water shortage is becoming one of the most serious problems in the Poyang Lake. In this paper, the long-term water balance items of the Poyang Lake have been analyzed to reveal the coupling effects of Three Gorges Dam (TGD) and droughts on the water balance of Poyang Lake. The results indicate that: (1) the water balance items of Poyang Lake vary greatly, e.g. lake precipitation and inflow decrease during the past several decades while evaporation and water consumption increase significantly; (2) the water balance of Poyang Lake has been affected by the operation of TGD. Negative lake water balance in recent years leads to a serious water shortage problem in the Poyang Lake. Moreover, the operation of TGD also changed the river-lake relationship in the lower Yangtze River basin; (3) the coupling effects of drought and TGD on the lake water balance has been analyzed by using composite analysis method and it can be found that the operation of TGD has significantly altered the lake water balance. But it is not the only factor that affects the lake water balance, and the droughts might cause their relations to be much more complicated.

  3. Neotectonic fault structures in the Lake Thun area (Switzerland)

    NASA Astrophysics Data System (ADS)

    Fabbri, Stefano C.; Herwegh, Marco; Schlunegger, Fritz; Hübscher, Christian; Weiss, Benedikt J.; Schmelzbach, Cédric; Horstmeyer, Heinrich; Merz, Kaspar; Anselmetti, Flavio S.

    2016-04-01

    Strong historic earthquakes (i.e. intensities I0 ≥ V) in Switzerland are well documented by the earthquake catalogue of Switzerland ECOS-09 (e.g. Frutigen, 1729 AD, Mw=5.2, I0=VI). Many of these strong events can be recognized paleoseismically by large subaquatic, earthquake-triggered mass movements that occur frequently in Swiss Lakes. Some of these represent the occasional occurrence of even stronger earthquakes (i.e. Mw ˜6.5) in the Alpine region (Strasser et al., 2013), which are expected to produce noticeable surface ruptures. However, convincing evidence for Quaternary displacements with offset surface expressions have scarcely been found (e.g., Wiemer et al., 2009). Applying a multi-disciplinary approach, this study presents potential candidates for such faults in the larger Lake Thun area at the edge of the Alps. The overdeepened basin of Lake Thun is situated at the northern Alpine front, which extends orthogonally to the general strike direction of the Alpine nappe front. The northern shoreline is predominantly shaped by the front of the Subalpine Molasse, which is in strong contrast to the south western shore built by the structurally higher units of the Middle and Lower Penninic nappes. This pattern with obvious differences of both lake sides suggests a major fault along the lake axis and high tectonic activity during nappe emplacement, i.e. from Eocene times throughout the Late Miocene. The area is dominated today by a strike-slip stress regime with a slight normal faulting component (Kastrup et al., 2004). As part of a multi-disciplinary study, attempting to find potential neotectonically active fault structures in the Lake Thun area, a 2D ground penetrating radar (GPR) survey was conducted. The aim of the GPR survey was to link observations from a multichannel reflection seismic survey and a multibeam bathymetric survey carried out in Lake Thun with findings in a nearby gravel quarry revealing suspicious deformation features such as rotated gravel

  4. The missing piece: sediment records in remote Mountain lakes confirm glaciers being secondary sources of persistent organic pollutants.

    PubMed

    Schmid, Peter; Bogdal, Christian; Blüthgen, Nancy; Anselmetti, Flavio S; Zwyssig, Alois; Hungerbühler, Konrad

    2011-01-01

    After atmospheric deposition and storage in the ice, glaciers are temporary reservoirs of persistent organic pollutants (POPs). Recently, the hypothesis that melting glaciers represent secondary sources of these pollutants has been introduced by investigations of the historical trend of POPs in a dated sediment core from the proglacial Alpine Lake Oberaar. Here, the hypothesis is further confirmed by the comparison of sediment data gathered from two Alpine lakes with a glaciated and a nonglaciated hydrological catchment. The two lakes (Lake Engstlen and Lake Stein in the Bernese Alps in Switzerland) are situated only 8 km apart at similar altitude and in the same meteorological catchment. In the nonglacial lake sediment of Lake Engstlen, PCBs and DDT (polychlorinated biphenyls and dichlorodiphenyl trichloroethane) levels culminated with the historic usage of these chemicals some 30-50 years ago. In the glacial Lake Stein, this peak was followed by a reincrease in the 1990s, which goes along with the accelerated melting of the adjacent glacier. This study confirms the hypothesis of glaciers being a secondary source of these pollutants and is in accordance with the earlier findings in Lake Oberaar.

  5. Chemical Alteration by Water, Jezero Crater Delta

    NASA Image and Video Library

    2011-11-21

    On ancient Mars, water carved channels and transported sediments to form fans and deltas within lake basins. Spectral data acquired by NASA Mars Reconnaissance Orbiter, indicate chemical alteration by water.

  6. White Lake AOC

    EPA Pesticide Factsheets

    White Lake is in Muskegon County along the eastern shore of Lake Michigan. It was named an Area of Concern on the Great Lakes under the Great Lakes Water Quality Agreement of 1987 and delisted in 2014.

  7. Interaction of various flow systems in small alpine catchments: conceptual model of the upper Gurk Valley aquifer, Carinthia, Austria

    NASA Astrophysics Data System (ADS)

    Hilberg, Sylke; Riepler, Franz

    2016-08-01

    Small alpine valleys usually show a heterogeneous hydraulic situation. Recurring landslides create temporal barriers for the surface runoff. As a result of these postglacial processes, temporal lakes form, and thus lacustrine fine-grained sedimentation intercalates with alluvial coarse-grained layers. A sequence of alluvial sediments (confined and thus well protected aquifers) and lacustrine sediments (aquitards) is characteristic for such an environment. The hydrogeological situation of fractured hard-rock aquifers in the framing mountain ranges is characterized by superficially high hydraulic conductivities as the result of tectonic processes, deglaciation and postglacial weathering. Fracture permeability and high hydraulic gradients in small-scaled alpine catchments result in the interaction of various flow systems in various kinds of aquifers. Spatial restrictions and conflicts between the current land use and the requirements of drinking-water protection represent a special challenge for water resource management in usually densely populated small alpine valleys. The presented case study describes hydrogeological investigations within the small alpine valley of the upper Gurktal (Upper Carinthia, Austria) and the adjacent Höllenberg Massif (1,772 m above sea level). Hydrogeological mapping, drilling, and hydrochemical and stable isotope analyses of springs and groundwater were conducted to identify a sustainable drinking-water supply for approximately 1,500 inhabitants. The results contribute to a conceptual hydrogeological model with three interacting flow systems. The local and the intermediate flow systems are assigned to the catchment of the Höllenberg Massif, whereas the regional flow system refers to the bordering Gurktal Alps to the north and provides an appropriate drinking water reservoir.

  8. Investigating cytoskeletal function in chloroplast protrusion formation in the arctic-alpine plant Oxyria digyna.

    PubMed

    Holzinger, A; Wasteneys, G O; Lütz, C

    2007-05-01

    Arctic and alpine plants like Oxyria digyna have to face enhanced environmental stress. This study compared leaves from Oxyria digyna collected in the Arctic at Svalbard (78 degrees N) and in the Austrian Alps (47 degrees N) at cellular, subcellular, and ultrastructural levels. Oxyria digyna plants collected in Svalbard had significantly thicker leaves than the samples collected in the Austrian Alps. This difference was generated by increased thickness of the palisade and spongy mesophyll layers in the arctic plants, while epidermal cells had no significant size differences between the two habitats. A characteristic feature of arctic, alpine, and cultivated samples was the occurrence of broad stroma-filled chloroplast protrusions, 2 - 5 microm broad and up to 5 microm long. Chloroplast protrusions were in close spatial contact with other organelles including mitochondria and microbodies. Mitochondria were also present in invaginations of the chloroplasts. A dense network of cortical microtubules found in the mesophyll cells suggested a potential role for microtubules in the formation and function of chloroplast protrusions. No direct interactions between microtubules and chloroplasts, however, were observed and disruption of the microtubule arrays with the anti-microtubule agent oryzalin at 5 - 10 microM did not alter the appearance or dynamics of chloroplast protrusions. These observations suggest that, in contrast to studies on stromule formation in Nicotiana, microtubules are not involved in the formation and morphology of chloroplast protrusions in Oxyria digyna. The actin microfilament-disrupting drug latrunculin B (5 - 10 microM for 2 h) arrested cytoplasmic streaming and altered the cytoplasmic integrity of mesophyll cells. However, at the ultrastructural level, stroma-containing, thylakoid-free areas were still visible, mostly at the concave sides of the chloroplasts. As chloroplast protrusions were frequently found to be mitochondria-associated in Oxyria

  9. Organic matter controls of soil water retention in an alpine grassland and its significance for hydrological processes

    NASA Astrophysics Data System (ADS)

    Yang, Fei; Zhang, Gan-Lin; Yang, Jin-Ling; Li, De-Cheng; Zhao, Yu-Guo; Liu, Feng; Yang, Ren-Min; Yang, Fan

    2014-11-01

    Soil water retention influences many soil properties and soil hydrological processes. The alpine meadows and steppes of the Qilian Mountains on the northeast border of the Qinghai-Tibetan Plateau form the source area of the Heihe River, the second largest inland river in China. The soils of this area therefore have a large effect on water movement and storage of the entire watershed. In order to understand the controlling factors of soil water retention and how they affect regional eco-hydrological processes in an alpine grassland, thirty-five pedogenic horizons in fourteen soil profiles along two facing hillslopes in typical watersheds of this area were selected for study. Results show that the extensively-accumulated soil organic matter plays a dominant role in controlling soil water retention in this alpine environment. We distinguished two mechanisms of this control. First, at high matric potentials soil organic matter affected soil water retention mainly through altering soil structural parameters and thereby soil bulk density. Second, at low matric potentials the water adsorbing capacity of soil organic matter directly affected water retention. To investigate the hydrological functions of soils at larger scales, soil water retention was compared by three generalized pedogenic horizons. Among these soil horizons, the mattic A horizon, a diagnostic surface horizon of Chinese Soil Taxonomy defined specially for alpine meadow soils, had the greatest soil water retention over the entire range of measured matric potentials. Hillslopes with soils having these horizons are expected to have low surface runoff. This study promotes the understanding of the critical role of alpine soils, especially the vegetated surface soils in controlling the eco-hydrological processes in source regions of the Heihe River watershed.

  10. The Alpine Cushion Plant Silene acaulis as Foundation Species: A Bug’s-Eye View to Facilitation and Microclimate

    PubMed Central

    Molenda, Olivia; Reid, Anya; Lortie, Christopher J.

    2012-01-01

    Alpine ecosystems are important globally with high levels of endemic and rare species. Given that they will be highly impacted by climate change, understanding biotic factors that maintain diversity is critical. Silene acaulis is a common alpine nurse plant shown to positively influence the diversity and abundance of organisms–predominantly other plant species. The hypothesis that cushion or nurse plants in general are important to multiple trophic levels has been proposed but rarely tested. Alpine arthropod diversity is also largely understudied worldwide, and the plant-arthropod interactions reported are mostly negative, that is,. herbivory. Plant and arthropod diversity and abundance were sampled on S. acaulis and at paired adjacent microsites with other non-cushion forming vegetation present on Whistler Mountain, B.C., Canada to examine the relative trophic effects of cushion plants. Plant species richness and abundance but not Simpson’s diversity index was higher on cushion microsites relative to other vegetation. Arthropod richness, abundance, and diversity were all higher on cushion microsites relative to other vegetated sites. On a microclimatic scale, S. acaulis ameliorated stressful conditions for plants and invertebrates living inside it, but the highest levels of arthropod diversity were observed on cushions with tall plant growth. Hence, alpine cushion plants can be foundation species not only for other plant species but other trophic levels, and these impacts are expressed through both direct and indirect effects associated with altered environmental conditions and localized productivity. Whilst this case study tests a limited subset of the membership of alpine animal communities, it clearly demonstrates that cushion-forming plant species are an important consideration in understanding resilience to global changes for many organisms in addition to other plants. PMID:22655035

  11. The alpine cushion plant Silene acaulis as foundation species: a bug's-eye view to facilitation and microclimate.

    PubMed

    Molenda, Olivia; Reid, Anya; Lortie, Christopher J

    2012-01-01

    Alpine ecosystems are important globally with high levels of endemic and rare species. Given that they will be highly impacted by climate change, understanding biotic factors that maintain diversity is critical. Silene acaulis is a common alpine nurse plant shown to positively influence the diversity and abundance of organisms--predominantly other plant species. The hypothesis that cushion or nurse plants in general are important to multiple trophic levels has been proposed but rarely tested. Alpine arthropod diversity is also largely understudied worldwide, and the plant-arthropod interactions reported are mostly negative, that is,. herbivory. Plant and arthropod diversity and abundance were sampled on S. acaulis and at paired adjacent microsites with other non-cushion forming vegetation present on Whistler Mountain, B.C., Canada to examine the relative trophic effects of cushion plants. Plant species richness and abundance but not Simpson's diversity index was higher on cushion microsites relative to other vegetation. Arthropod richness, abundance, and diversity were all higher on cushion microsites relative to other vegetated sites. On a microclimatic scale, S. acaulis ameliorated stressful conditions for plants and invertebrates living inside it, but the highest levels of arthropod diversity were observed on cushions with tall plant growth. Hence, alpine cushion plants can be foundation species not only for other plant species but other trophic levels, and these impacts are expressed through both direct and indirect effects associated with altered environmental conditions and localized productivity. Whilst this case study tests a limited subset of the membership of alpine animal communities, it clearly demonstrates that cushion-forming plant species are an important consideration in understanding resilience to global changes for many organisms in addition to other plants.

  12. Evaluating Precipitation Elevation Gradients in the Alaska Range using Ice Core and Alpine Weather Station Records

    NASA Astrophysics Data System (ADS)

    McConnell, E.; Osterberg, E. C.; Winski, D.; Kreutz, K. J.; Wake, C. P.; Campbell, S. W.; Ferris, D. G.; Birkel, S. D.

    2016-12-01

    Precipitation in Alaska is sensitive to the Aleutian Low (ALow) pressure system and North Pacific sea-surface temperatures, as shown by the increase in Alaskan sub-Arctic precipitation associated with the 1976 shift to the positive phase of the Pacific Decadal Oscillation (PDO). Precipitation in the high-elevation accumulation zones of Alaskan alpine glaciers provides critical mass input for glacial mass balance, which has been declining in recent decades from warmer summer temperatures despite the winter precipitation increase. Twin >1500-year ice cores collected from the summit plateau of Mount Hunter in Denali National Park, Alaska show a remarkable doubling of annual snow accumulation over the past 150 years, with most of the change observed in the winter. Other alpine ice cores collected from the Alaska and Saint Elias ranges show similar snowfall increases over recent decades. However, although Alaskan weather stations at low elevation recorded a 7-38% increase in winter precipitation across the 1976 PDO transition, this increase is not as substantial as that recorded in the Mt. Hunter ice core. Weather stations at high-elevation alpine sites are comparatively rare, and reasons for the enhanced precipitation trends at high elevation in Alaska remain unclear. Here we use Automatic Weather Station data from the Mt. Hunter drill site (3,900 m a.s.l) and from nearby Denali climber's Base Camp (2,195 m a.s.l.) to evaluate the relationships between alpine and lowland Alaskan precipitation on annual, seasonal, and storm-event temporal scales from 2008-2016. Both stations are located on snow and have sonic snow depth sounders to record daily precipitation. We focus on the role of variable ALow and North Pacific High strength in influencing Alaskan precipitation elevational gradients, particularly in association with the extreme 2015-2016 El Niño event, the 2009-2010 moderate El Niño event, and the 2010-2011 moderate La Niña event. Our analysis will improve our

  13. Changes in Quadriceps Muscle Activity During Sustained Recreational Alpine Skiing

    PubMed Central

    Kröll, Josef; Müller, Erich; Seifert, John G.; Wakeling, James M.

    2011-01-01

    During a day of skiing thousands of repeated contractions take place. Previous research on prolonged recreational alpine skiing show that physiological changes occur and hence some level of fatigue is inevitable. In the present paper the effect of prolonged skiing on the recruitment and coordination of the muscle activity was investigated. Six subjects performed 24 standardized runs. Muscle activity during the first two (PREskiing) and the last two (POSTskiing) runs was measured from the vastus lateralis (VL) and rectus femoris (RF) using EMG and quantified using wavelet and principal component analysis. The frequency content of the EMG signal shifted in seven out of eight cases significantly towards lower frequencies with highest effects observed for RF on outside leg. A significant pronounced outside leg loading occurred during POSTskiing and the timing of muscle activity peaks occurred more towards turn completion. Specific EMG frequency changes were observed at certain time points throughout the time windows and not over the whole double turn. It is suggested that general muscular fatigue, where additional specific muscle fibers have to be recruited due to the reduced power output of other fibers did not occur. The EMG frequency decrease and intensity changes for RF and VL are caused by altered timing (coordination) within the turn towards a most likely more uncontrolled skiing technique. Hence, these data provide evidence to suggest recreational skiers alter their skiing technique before a potential change in muscle fiber recruitment occurs. Key points The frequency content of the EMG signal shifted in seven out of eight cases significantly towards lower frequencies with highest effects observed for RF. General muscular fatigue, where additional specific fibers have to be recruited due to the reduced power output of other fibers, did not occur. A modified skiing style towards a less functional and hence more uncontrolled skiing technique seems to be a key

  14. Principles of lake sedimentology

    SciTech Connect

    Janasson, L.

    1983-01-01

    This book presents a comprehensive outline on the basic sedimentological principles for lakes, and focuses on environmental aspects and matters related to lake management and control-on lake ecology rather than lake geology. This is a guide for those who plan, perform and evaluate lake sedimentological investigations. Contents abridged: Lake types and sediment types. Sedimentation in lakes and water dynamics. Lake bottom dynamics. Sediment dynamics and sediment age. Sediments in aquatic pollution control programmes. Subject index.

  15. Seed dispersal at alpine treeline: long distance dispersal maintains alpine treelines

    NASA Astrophysics Data System (ADS)

    Johnson, J. S.; Gaddis, K. D.; Cairns, D. M.; Krutovsky, K.

    2016-12-01

    Alpine treelines are expected to advance to higher elevations in conjunction with global warming. Nevertheless, the importance of reproductive method and seed dispersal distances at the alpine treeline ecotone remains unresolved. We address two research questions at mountain hemlock treelines on the Kenai Peninsula, Alaska: (1) What is the primary mode of reproduction, and (2) are recruits derived from local treeline populations or are they arriving from more distant seed sources? We addressed our research questions by exhaustively sampling mountain hemlock individuals along a single mountain slope and then genotyped DNA single nucleotide polymorphisms using a genotyping by sequencing approach (ddRAD Seq). First we assessed mode of reproduction by determining the proportion of sampled individuals with identical multilocus genotypes that are the product of clonal reproduction. Second, we used a categorical allocation based parentage analysis to identify parent-offspring pairs, so that the proportion of treeline reproduction events could be quantified spatially and dispersal distance measured. We identified sexual reproduction as the primary mode of reproduction at our study site. Seedling establishment was characterized by extensive cryptic seed dispersal and gene flow into the ecotone. The average dispersal distance was 73 meters with long distance dispersal identified as dispersal occurring at distances greater than 450 meters. We show that production of seeds within the alpine treeline ecotone is not a necessary requirement for treelines to advance to higher elevations in response to climate change. The extensive cryptic seed dispersal and gene flow into the alpine treeline ecotone is likely sufficient to propel the ecotone higher under more favorable climate.

  16. Lithological Characteristics of the Alpine Fault Zone from DFDP-1 and Outcrop Observations

    NASA Astrophysics Data System (ADS)

    Toy, V. G.; Boulton, C. J.; Prior, D. J.; Norris, R. J.; Mariani, E.; Faulkner, D. R.; Sutherland, R.; Townend, J.

    2012-12-01

    Approximately 120 m total length of core which was recovered across the Alpine Fault Zone during drilling of DFDP-1 sampled a similar fault rock sequence to that observed in nearby outcrops. Detailed description of core and outcrop samples allows us to characterize the fault rocks in general, and to more clearly define the alteration zone identified by Sutherland et al. (in press; this session). We identify six distinct basement-derived lithologic units that we anticipate will also be encountered in DFDP-2: 1) "Schist-derived mylonite" to ultramylonite with a Pacific Plate quartzo-feldspathic or metabasic protolith, which generally has an amphibolite facies mineralogy; 2) "Brown-green-black ultramylonite" that is finely laminated, displays a hydrous greenschist facies mineralogy, and may in part have formed from Australian Plate protoliths; 3) "Unfoliated cataclasites" primarily derived from Pacific Plate protoliths; 4) "Foliated cataclasites" primarily derived from Pacific Plate protoliths; 5) "Gouges" composed of ultracomminuted material (described in more detail by Boulton et al., this session); and 6) "Footwall cataclasites", so named because they were first encountered beneath the shallowest principal slip zone (PSZ) in DFDP-1B. Unit 6 locally contains feldspar and biotite in textures reminiscent of granite, suggesting it is derived from a footwall protolith. However, we emphasise that, at present, downhole geophysical logs provide clearer distinction between units 3 and 4, and unit 6, than is evident from examination of hand specimens of the core (Townend et al., this session). We anticipate further microscopic and geochemical investigations will allow cataclasites derived from the two different protoliths to be more clearly differentiated. Carbonate cements are common, and phyllosilicates such as chlorite and illite-muscovite are more pervasive within a "primary alteration zone" developed within 20 m of the PSZs in DFDP-1. In a "secondary alteration zone

  17. On the measurement of alpine subscale erosion

    NASA Astrophysics Data System (ADS)

    Konz, N.; Schaub, M.; Prasuhn, V.; Alewell, C.

    2009-04-01

    Institute of Environmental Geosciences, University of Basel, Switzerland Data on quantification of sheet erosion rates in alpine grasslands and their dependency on land use remain scarce but are urgently needed to estimate soil degradation and soil conservation strategies. We determined soil erosion rates based on the Cs-137 method with in-situ measurements and with sediment traps. The Cs-137 method integrates the erosion over the last 22 years (time after the Chernobyl accident), whereas sediment traps provide information on erosion rates over single weeks and months during the vegetation period. Sediment traps can not be applied during winter time in alpine regions because snow amounts flatten and destroy the sediment traps. Three different land use types were investigated: hayfields, pasture with dwarf shrubs and pasture without dwarf shrubs. Our test plots are situated in the Urseren Valley (Central Switzerland) with a mean slope steepness of 37°. Monthly erosion rates measured with sediment traps during the vegetation periods 2007 and 2008 are about 0.01 t ha-1 for hayfields, 0.005 t ha-1 for pastures with dwarf shrubs and 0.05 t ha-1 for pastures without dwarf shrubs. Mean annual soil erosion rates determined with Cs-137 of the investigated sites ranged between 4.7 t ha-1 a-1 for pastures with dwarf shrubs to >15 t ha-1 a-1 at hayfields and pastures without dwarf shrubs and are thus exceedingly high compared to measurements with sediment traps. Cs-137 measurements integrated over the last 22 years, including extreme rainfall events as well as winter processes; whereas sediment traps provide erosion rates based on summer time rainfall events. Our results lead to the assumption that the triggering processes of alpine erosion are due to snow gliding processes during winter time whereas erosion rates due to overland flow and splash effects play a minor role on the entire erosion amount. These different amounts on erosion rates for the vegetation periods in

  18. Evaluation of water quality projects in the Lake Tahoe basin.

    PubMed

    Schuster, S; Grismer, M E

    2004-01-01

    Lake Tahoe is a large sub alpine lake located in the Sierra Nevada Range in the states of California and Nevada. The Lake Tahoe watershed is relatively small (800 km(20) and is made up of soils with a very low nutrient content and when combined with the Lake's enormous volume (156 km(3)) produces water of unparalleled clarity. However, urbanization around the Lake during the past 50 yr has greatly increased nutrient flux into the Lake resulting in increased algae production and rapidly declining water clarity. Lake transition from nitrogen limiting to phosphorous limiting during the last 30 yr suggests the onset of cultural eutrophication of Lake Tahoe. Protecting Lake Tahoe's water quality has become a major public concern and much time, effort, and money has been, and will be, spent on this undertaking. The effectiveness of remedial actions is the subject of some debate. Local regulatory agencies have mandated implementation of best management practices (BMPs) to mitigate the effects of development, sometimes at great additional expense for developers and homeowners who question their effectiveness. Conclusive studies on the BMP effectiveness are also expensive and can be difficult to accomplish such that very few such studies have been completed. However, several project evaluations have been completed and more are underway. Such study usually demonstrates support of the project's effectiveness in decreasing nutrient flux to Lake Tahoe. Here, we review the existing state of knowledge of nutrient loading to the Lake and to highlight the need for further evaluative investigations of BMPs in order to improve their performance in present and future regulatory actions.

  19. Safety in alpine helicopter rescue operations--minimal requirements of alpine skills for rescue personnel.

    PubMed

    Küpper, Thomas; Hillebrandt, David; Steffgen, Juergen; Schöffl, Volker

    2013-11-01

    There is a lack of data to establish minimal requirements for technical alpine climbing skills needed by rescue teams involved in alpine helicopter rescue operations to perform such operations safely. A year of rescue operations (N = 2731) were investigated for the technical difficulties of the terrain. The difficulties were graded according to the Union Internationale des Associations d'Alpinisme (UIAA) scale for rocky terrain and steepness for ice slopes. For 99.7% of the operations, the terrain could be accurately evaluated. In at least 30.7% of all rescue operations, personal advanced alpine climbing skills were required for the rescue personnel, and in 6.0%, the difficulties of the rocky terrain correspond to UIAA scale grade III with another 2.4% to UIAA grade IV or above. About 1.5% of all operations took place in ice faces steeper than 50°. To be able to manage 90% of all operations safely, all crew members, except the pilot, must be competent at climbing rock terrain of UIAA scale grade IV and ice of 50° steepness using appropriate rescue, rope, and belaying techniques. These recommendations include a technical safety margin for adverse conditions, such as bad weather.

  20. Glacial Lake Growth and Associated Glacier Dynamics: Case Study from the Himalayas, Andes, Alaska and New Zealand

    NASA Astrophysics Data System (ADS)

    Binger, D. J.; Haritashya, U. K.; Kargel, J. S.; Shugar, D. H.

    2016-12-01

    Glacial lake growth and associated glacier dynamics: Case study from the Himalayas, Andes, Alaska and New Zealand David J. Binger1, Umesh K. Haritashya1 and Jeffrey S. Kargel21University of Dayton, Dayton, OH 2University of Arizona, Tucson, AZ As a result of climate change most of the world's alpine glaciers are undergoing measurable retreat and dynamic changes. The result of accelerated melting has led to the formation and growth of potentially dangerous glacial lakes. In this study, alpine glaciers and associated lakes from the Himalayas, Andes, Alaska and New Zealand, showing similar geomorphological settings were analyzed to compare differences in regional proglacial lake growth and its relationship with glacier dynamics. Specifically, we analyzed the surface area growth of the lakes, retreat of glacier terminus, changes in glacier velocity, surface temperature and potential glacial lake outburst flood triggers. Using Landsat and ASTER satellite images, Cosi - Corr software, and in house thermal mapping, 10 glaciers were analyzed and compared. Results show a substantial increase in proglacial lake surface area, accelerated velocity and significant calving of the glaciers. Glacier surface temperatures varied by location, with some remaining constant and others 2°C - 4°C increases; although increased surface temperature did not always show a direct correlation with increasing retreat rate. Lakes with high rates of surface area growth paired with glaciers with increased velocity and calving could prove to be unsustainable and lead to an increased risk for glacial lake outburst floods. Overall, result show the changing dynamics of the alpine glaciers in different mountain regions and the growth of their proglacial lakes.

  1. Climate-induced changes in lake ecosystem structure inferred from coupled neo- and paleoecological approaches

    USGS Publications Warehouse

    Saros, Jasmine E.; Stone, Jeffery R.; Pederson, Gregory T.; Slemmons, Krista; Spanbauer, Trisha; Schliep, Anna; Cahl, Douglas; Williamson, Craig E.; Engstrom, Daniel R.

    2015-01-01

    Over the 20th century, surface water temperatures have increased in many lake ecosystems around the world, but long-term trends in the vertical thermal structure of lakes remain unclear, despite the strong control that thermal stratification exerts on the biological response of lakes to climate change. Here we used both neo- and paleoecological approaches to develop a fossil-based inference model for lake mixing depths and thereby refine understanding of lake thermal structure change. We focused on three common planktonic diatom taxa, the distributions of which previous research suggests might be affected by mixing depth. Comparative lake surveys and growth rate experiments revealed that these species respond to lake thermal structure when nitrogen is sufficient, with species optima ranging from shallower to deeper mixing depths. The diatom-based mixing depth model was applied to sedimentary diatom profiles extending back to 1750 AD in two lakes with moderate nitrate concentrations but differing climate settings. Thermal reconstructions were consistent with expected changes, with shallower mixing depths inferred for an alpine lake where treeline has advanced, and deeper mixing depths inferred for a boreal lake where wind strength has increased. The inference model developed here provides a new tool to expand and refine understanding of climate-induced changes in lake ecosystems.

  2. A satellite-based climatology (1989-2012) of lake surface water temperature from AVHRR 1-km for Central European water bodies

    NASA Astrophysics Data System (ADS)

    Riffler, Michael; Wunderle, Stefan

    2013-04-01

    The temperature of lakes is an important parameter for lake ecosystems influencing the speed of physio-chemical reactions, the concentration of dissolved gazes (e.g. oxygen), and vertical mixing. Even small temperature changes might have irreversible effects on the lacustrine system due to the high specific heat capacity of water. These effects could alter the quality of lake water depending on parameters like lake size and volume. Numerous studies mention lake water temperature as an indicator of climate change and in the Global Climate Observing System (GCOS) requirements it is listed as an essential climate variable. In contrast to in situ observations, satellite imagery offers the possibility to derive spatial patterns of lake surface water temperature (LSWT) and their variability. Moreover, although for some European lakes long in situ time series are available, the temperatures of many lakes are not measured or only on a non-regular basis making these observations insufficient for climate monitoring. However, only few satellite sensors offer the possibility to analyze time series which cover more than 20 years. The Advanced Very High Resolution Radiometer (AVHRR) is among these and has been flown on the National Oceanic and Atmospheric Administration (NOAA) Polar Operational Environmental Satellites (POES) and on the Meteorological Operational Satellites (MetOp) from the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) as a heritage instrument for almost 35 years. It will be carried on for at least ten more years finally offering a unique opportunity for satellite-based climate studies. Herein we present the results from a study initiated by the Swiss GCOS office to generate a satellite-based LSWT climatology for the pre-alpine water bodies in Switzerland. It relies on the extensive AVHRR 1-km data record (1985-2012) of the Remote Sensing Research Group at the University of Bern (RSGB) and has been derived from the AVHRR/2

  3. Precipitation overrides warming in mediating soil nitrogen pools in an alpine grassland ecosystem on the Tibetan Plateau

    PubMed Central

    Lin, Li; Zhu, Biao; Chen, Chengrong; Zhang, Zhenhua; Wang, Qi-Bing; He, Jin-Sheng

    2016-01-01

    Soils in the alpine grassland store a large amount of nitrogen (N) due to slow decomposition. However, the decomposition could be affected by climate change, which has profound impacts on soil N cycling. We investigated the changes of soil total N and five labile N stocks in the topsoil, the subsoil and the entire soil profile in response to three years of experimental warming and altered precipitation in a Tibetan alpine grassland. We found that warming significantly increased soil nitrate N stock and decreased microbial biomass N (MBN) stock. Increased precipitation reduced nitrate N, dissolved organic N and amino acid N stocks, but increased MBN stock in the topsoil. No change in soil total N was detected under warming and altered precipitation regimes. Redundancy analysis further revealed that soil moisture (26.3%) overrode soil temperature (10.4%) in explaining the variations of soil N stocks across the treatments. Our results suggest that precipitation exerted stronger influence than warming on soil N pools in this mesic and high-elevation grassland ecosystem. This indicates that the projected rise in future precipitation may lead to a significant loss of dissolved soil N pools by stimulating the biogeochemical processes in this alpine grassland. PMID:27527683

  4. Precipitation overrides warming in mediating soil nitrogen pools in an alpine grassland ecosystem on the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Lin, Li; Zhu, Biao; Chen, Chengrong; Zhang, Zhenhua; Wang, Qi-Bing; He, Jin-Sheng

    2016-08-01

    Soils in the alpine grassland store a large amount of nitrogen (N) due to slow decomposition. However, the decomposition could be affected by climate change, which has profound impacts on soil N cycling. We investigated the changes of soil total N and five labile N stocks in the topsoil, the subsoil and the entire soil profile in response to three years of experimental warming and altered precipitation in a Tibetan alpine grassland. We found that warming significantly increased soil nitrate N stock and decreased microbial biomass N (MBN) stock. Increased precipitation reduced nitrate N, dissolved organic N and amino acid N stocks, but increased MBN stock in the topsoil. No change in soil total N was detected under warming and altered precipitation regimes. Redundancy analysis further revealed that soil moisture (26.3%) overrode soil temperature (10.4%) in explaining the variations of soil N stocks across the treatments. Our results suggest that precipitation exerted stronger influence than warming on soil N pools in this mesic and high-elevation grassland ecosystem. This indicates that the projected rise in future precipitation may lead to a significant loss of dissolved soil N pools by stimulating the biogeochemical processes in this alpine grassland.

  5. Precipitation overrides warming in mediating soil nitrogen pools in an alpine grassland ecosystem on the Tibetan Plateau.

    PubMed

    Lin, Li; Zhu, Biao; Chen, Chengrong; Zhang, Zhenhua; Wang, Qi-Bing; He, Jin-Sheng

    2016-08-16

    Soils in the alpine grassland store a large amount of nitrogen (N) due to slow decomposition. However, the decomposition could be affected by climate change, which has profound impacts on soil N cycling. We investigated the changes of soil total N and five labile N stocks in the topsoil, the subsoil and the entire soil profile in response to three years of experimental warming and altered precipitation in a Tibetan alpine grassland. We found that warming significantly increased soil nitrate N stock and decreased microbial biomass N (MBN) stock. Increased precipitation reduced nitrate N, dissolved organic N and amino acid N stocks, but increased MBN stock in the topsoil. No change in soil total N was detected under warming and altered precipitation regimes. Redundancy analysis further revealed that soil moisture (26.3%) overrode soil temperature (10.4%) in explaining the variations of soil N stocks across the treatments. Our results suggest that precipitation exerted stronger influence than warming on soil N pools in this mesic and high-elevation grassland ecosystem. This indicates that the projected rise in future precipitation may lead to a significant loss of dissolved soil N pools by stimulating the biogeochemical processes in this alpine grassland.

  6. CHARACTERIZATION OF ENDOCRINE-DISRUPTION AND CLINICAL MANIFESTATIONS IN LARGE-MOUTH BASS FROM FLORIDA LAKES

    EPA Science Inventory

    Previous efforts from this laboratory, have documented altered endocrine function and sexual differentiation for alligators and turtles from Lake Apopka in Central Florida. This lake has been exposed to a variety of contaminants which are potentially endocrine-disrupting. Therefo...

  7. CHARACTERIZATION OF ENDOCRINE-DISRUPTION AND CLINICAL MANIFESTATIONS IN LARGE-MOUTH BASS FROM FLORIDA LAKES

    EPA Science Inventory

    Previous efforts from this laboratory, have documented altered endocrine function and sexual differentiation for alligators and turtles from Lake Apopka in Central Florida. This lake has been exposed to a variety of contaminants which are potentially endocrine-disrupting. Therefo...

  8. Lake Powell

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The white ring around Lake Powell tells the story. The surface is down 98 feet. This is critical, because Powell, Lake Mead, and other lakes along the Colorado River provide water for millions of people in five states. We are in the eighth year of a drought on the Colorado River. This year was the driest year ever reported in Southern California, and there is a severe drought in Northern California, down to less than 30-percent of snow pack. This ASTER image of part of Lake Powell was acquired in 2001. The gray area depicts the shrunken, reduced 2007 lake extent compared to the extended, larger black area in 2001.

    The image covers an area of 24 x 30 km, and is centered near 37.1 degrees north latitude, 111.3 degrees west longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  9. Sustainable use of alpine and pre-alpine grassland soils in a changing climate (SUSALPS)

    NASA Astrophysics Data System (ADS)

    Zistl-Schlingmann, Marcus; Beck, Robert; Brandhuber, Robert; Butterbach-Bahl, Klaus; Garcia Franco, Noelia; von Gillhaußen, Phillip; Jentsch, Anke; Kiese, Ralf; Krämer, Alexander; Kögel-Knabner, Ingrid; Köllner, Thomas; Poppenborg, Patrick; Schloter, Michael; Schulz, Stefanie; Wiesmeier, Martin; Wolf, Benjamin; Dannenmann, Michael

    2016-04-01

    The development of ecologically as well as economically sustainable management options for the carbon- and nitrogen rich alpine and pre-alpine grassland soils in a changing climate poses a grand scientific and socio- economical challenge. The transdisciplinary SUSALPS project starting in 2016 aims to essentially improve the knowledge on the functionality of alpine and pre-alpine grassland soils using both natural-scientific/ technical and socio economical approaches. The project is building on existing infrastructure of German grassland-ecosystem-research like the pre-alpine TERENO (Terrestrial ecosystem observation network observatory) observatory sites, the EVENT and SIGNAL sites as well as long term LfL (Bayerische Landesanstalt für Landwirtschaft) sites, plus a new additional high elevation (1400m a.s.l) site in the Bavarian Alps. The site setup along the elevational gradient on the edge of the Alps (1400 m to 300 m) is used for space-for-time climate change experiments which are combined with extensive and intensive management treatments. A key focus of SUSALPS will be the characterization of combined climate change/management effects on carbon and nitrogen biogeochemistry. Hence, we will evaluate the influence of different management options and current and future climate changes on the soil microbiome and associated biogeochemical processes in the plant-soil-system, on nitrogen use efficiency, on biosphere-atmosphere exchange of greenhouse gases as well as on leaching of environmentally relevant compounds. For this purpose, we simulate the predicted climate change in the region by translocation of large lysimeters (1m2, 1.4m depth; TERENO lysimeters, translocated in 2011) for measurements of biosphere-atmosphere hydrosphere exchange of environmentally relevant C and N compounds as well as by newly transferred smaller plant-soil-mesocosms used for destructive biogeochemical process studies. By closely linking this experimental work with biogeochemical and

  10. Arctic and Alpine Vegetations: Similarities, Differences, and Susceptibility to Disturbance

    ERIC Educational Resources Information Center

    Billings, W. D.

    1973-01-01

    Discusses environmental and biological aspects of arctic and alpine vegetations in the New World between the equator and the Arctic Ocean, considering their similarities, differences, and susceptibility to disturbance by man. (JR)

  11. Alpine Fault, New Zealand, SRTM Shaded Relief and Colored Height

    NASA Image and Video Library

    2005-01-06

    The Alpine fault runs parallel to, and just inland of, much of the west coast of New Zealand South Island. This view was created from the near-global digital elevation model produced by NASA Shuttle Radar Topography Mission SRTM.

  12. Arctic and Alpine Vegetations: Similarities, Differences, and Susceptibility to Disturbance

    ERIC Educational Resources Information Center

    Billings, W. D.

    1973-01-01

    Discusses environmental and biological aspects of arctic and alpine vegetations in the New World between the equator and the Arctic Ocean, considering their similarities, differences, and susceptibility to disturbance by man. (JR)

  13. Palinspastic reconstruction of the Alpine thrust belt at the Alpine-Carpathian transition - A geological Sudoku

    NASA Astrophysics Data System (ADS)

    Beidinger, A.; Decker, K.; Zamolyi, A.; Hölzel, M.; Hoprich, M.; Strauss, P.

    2009-04-01

    The palinspastic reconstruction of the Austroalpine thrust belt is part of the project Karpatian Tectonics, which is funded by OMV Austria. The objective is to reconstruct the evolution of the thrust belt through the Early to Middle Miocene in order to obtain information on the palaeogeographic position of the Northern Calcareous Alps (NCA) in the region of the present Vienna Basin. A particular goal of the study is to constrain the position of reservoir rocks within the Rhenodanubic Flysch units and the NCA with respect to the autochthonous Malmian source rocks overlying the European basement below the Alpine-Carpathian thrust wedge, and to constrain the burial history of these source rocks. Reconstruction uses regional 2D seismic lines crossing from the European foreland into the fold-thrust belt, 3D seismic data covering the external thrust sheets, and lithostratigraphic data from a total of 51 selected wells, which were drilled and provided by OMV Austria. The main criterion, whether a well was suitable for palinspastic reconstruction or not, was its penetration of Alpine thrust sheets down to the Autochthonous Molasse of the foreland. Additional wells, which do not penetrate the entire Alpine thrust complex but include the Allochthonous Molasse or the external Alpine-Carpathian nappes (Waschberg and Roseldorf thrust unit, Rhenodanubic Flysch nappes) in their well path, were also taken into account. The well data in particular comprise stratigraphic information on the youngest overthrust sediments of the different thrust units and the underlying Autochthonous foreland Molasse. These data allow constraining the timing of thrust events in the allochthonous thrust units and overthrusting of the Autochthonous Molasse. In the particular case of overthrust Autochthonous Molasse, additionally to the timing of overthrusting, which can be derived from the youngest overthrust sediments, the palaeogeographic position of the Alpine Carpathian thrust front could directly be

  14. Sensitivity of Alpine Snow and Streamflow Regimes to Climate Changes

    NASA Astrophysics Data System (ADS)

    Rasouli, K.; Pomeroy, J. W.; Marks, D. G.; Bernhardt, M.

    2014-12-01

    Understanding the sensitivity of hydrological processes to climate change in alpine areas with snow dominated regimes is of paramount importance as alpine basins show both high runoff efficiency associated with the melt of the seasonal snowpack and great sensitivity of snow processes to temperature change. In this study, meteorological data measured in a selection of alpine headwaters basins including Reynolds Mountain East, Idaho, USA, Wolf Creek, Yukon in Canada, and Zugspitze Mountain, Germany with climates ranging from arctic to continental temperate were used to study the snow and streamflow sensitivity to climate change. All research sites have detailed multi-decadal meteorological and snow measurements. The Cold Regions Hydrological Modelling platform (CRHM) was used to create a model representing a typical alpine headwater basin discretized into hydrological response units with physically based representations of snow redistribution by wind, complex terrain snowmelt energetics and runoff processes in alpine tundra. The sensitivity of snow hydrology to climate change was investigated by changing air temperature and precipitation using weather generating methods based on the change factors obtained from different climate model projections for future and current periods. The basin mean and spatial variability of peak snow water equivalent, sublimation loss, duration of snow season, snowmelt rates, streamflow peak, and basin discharge were assessed under varying climate scenarios and the most sensitive hydrological mechanisms to the changes in the different alpine climates were detected. The results show that snow hydrology in colder alpine climates is more resilient to warming than that in warmer climates, but that compensatory factors to warming such as reduced blowing snow sublimation loss and reduced melt rate should also be assessed when considering climate change impacts on alpine hydrology.

  15. The onset of alpine pastoral systems in the Eastern Alps

    NASA Astrophysics Data System (ADS)

    Oeggl, Klaus; Festi, Daniela; Putzer, Andreas

    2015-04-01

    Since the discovery of the Neolithic glacier mummy "Ötzi" in the nival belt of the main Alpine ridge, the onset of alpine pasture is matter of a highly controversial debate both in archaeology and in palaeo-ecology of the Eastern Alps. The implication is that his sojourn in the high-altitudes of the Alps is considered to be connected with pastoral nomadism. Regrettably any archaeological evidence for the existence of such Neolithic alpine pastoral systems is missing up to now and the assumption is based on palynological data only. However, also the palynological record is ambiguous, because pasture indicators in the alpine regions react positive on grazing as well as on fertilization induced by a higher runoff of precipitation. Thus alpine pasture indicators reflect both grazing pressure and climatic change. Anyhow, alpine pastoral systems are a common practice in Alpine animal husbandry, but from an economic point of view such a seasonal vertical transhumance is costly. There are three main reasons for its practice: i) climatic, ii) economic (mainly in connection with population pressure or mining activities), and iii) cultural ideology. In this study we tested the above mentioned reasons in an interdisciplinary study on the beginning of pastoral activities in high altitudes in the central part of the Eastern Alps. This is conducted by palynological analyses of peat deposits situated in the vicinity of the timberline (1600 - 2400 m a.s.l.) combined with archaeological surveys. The investigated sites are located in traditional Alpine transhumance regions and aligned on a transect through the central part of the Eastern Alps. The studies reveal that grazing pressure is reflected since the Bronze Age, which is corroborated by archaeological findings in the vicinity of the investigated sites.

  16. Quantifying Recent Ecological Changes in Remote Lakes of North America and Greenland Using Sediment Diatom Assemblages

    PubMed Central

    Hobbs, William O.; Telford, Richard J.; Birks, H. John B.; Saros, Jasmine E.; Hazewinkel, Roderick R. O.; Perren, Bianca B.; Saulnier-Talbot, Émilie; Wolfe, Alexander P.

    2010-01-01

    Background Although arctic lakes have responded sensitively to 20th-century climate change, it remains uncertain how these ecological transformations compare with alpine and montane-boreal counterparts over the same interval. Furthermore, it is unclear to what degree other forcings, including atmospheric deposition of anthropogenic reactive nitrogen (Nr), have participated in recent regime shifts. Diatom-based paleolimnological syntheses offer an effective tool for retrospective assessments of past and ongoing changes in remote lake ecosystems. Methodology/Principal Findings We synthesized 52 dated sediment diatom records from lakes in western North America and west Greenland, spanning broad latitudinal and altitudinal gradients, and representing alpine (n = 15), arctic (n = 20), and forested boreal-montane (n = 17) ecosystems. Diatom compositional turnover (β-diversity) during the 20th century was estimated using Detrended Canonical Correspondence Analysis (DCCA) for each site and compared, for cores with sufficiently robust chronologies, to both the 19th century and the prior ∼250 years (Little Ice Age). For both arctic and alpine lakes, β-diversity during the 20th century is significantly greater than the previous 350 years, and increases with both latitude and altitude. Because no correlation is apparent between 20th-century diatom β-diversity and any single physical or limnological parameter (including lake and catchment area, maximum depth, pH, conductivity, [NO3−], modeled Nr deposition, ambient summer and winter air temperatures, and modeled temperature trends 1948–2008), we used Principal Components Analysis (PCA) to summarize the amplitude of recent changes in relationship to lake pH, lake:catchment area ratio, modeled Nr deposition, and recent temperature trends. Conclusions/Significance The ecological responses of remote lakes to post-industrial environmental changes are complex. However, two regions reveal concentrations of sites

  17. Quantifying recent ecological changes in remote lakes of North America and Greenland using sediment diatom assemblages.

    PubMed

    Hobbs, William O; Telford, Richard J; Birks, H John B; Saros, Jasmine E; Hazewinkel, Roderick R O; Perren, Bianca B; Saulnier-Talbot, Emilie; Wolfe, Alexander P

    2010-04-02

    Although arctic lakes have responded sensitively to 20(th)-century climate change, it remains uncertain how these ecological transformations compare with alpine and montane-boreal counterparts over the same interval. Furthermore, it is unclear to what degree other forcings, including atmospheric deposition of anthropogenic reactive nitrogen (Nr), have participated in recent regime shifts. Diatom-based paleolimnological syntheses offer an effective tool for retrospective assessments of past and ongoing changes in remote lake ecosystems. We synthesized 52 dated sediment diatom records from lakes in western North America and west Greenland, spanning broad latitudinal and altitudinal gradients, and representing alpine (n = 15), arctic (n = 20), and forested boreal-montane (n = 17) ecosystems. Diatom compositional turnover (beta-diversity) during the 20(th) century was estimated using Detrended Canonical Correspondence Analysis (DCCA) for each site and compared, for cores with sufficiently robust chronologies, to both the 19(th) century and the prior approximately 250 years (Little Ice Age). For both arctic and alpine lakes, beta-diversity during the 20(th) century is significantly greater than the previous 350 years, and increases with both latitude and altitude. Because no correlation is apparent between 20(th)-century diatom beta-diversity and any single physical or limnological parameter (including lake and catchment area, maximum depth, pH, conductivity, [NO(3)(-)], modeled Nr deposition, ambient summer and winter air temperatures, and modeled temperature trends 1948-2008), we used Principal Components Analysis (PCA) to summarize the amplitude of recent changes in relationship to lake pH, lake:catchment area ratio, modeled Nr deposition, and recent temperature trends. The ecological responses of remote lakes to post-industrial environmental changes are complex. However, two regions reveal concentrations of sites with elevated 20(th)-century diatom beta

  18. Alpine crustal shear zones and pre-Alpine basement terranes in the Romanian Carpathians and Apuseni Mountains

    NASA Astrophysics Data System (ADS)

    Panã, Dinu; Erdmer, Phillippe

    1994-09-01

    The Carpathian orocline formed by complex suturing of small continental fragments to the East European (and Moesian) plate. Remnants of continental fragments belong to three pre-Alpine lithotectonic assemblages: a "greenstone-granite" association and two gneissic assem blages. During Alpine collision, pieces of crust were repeatedly fragmented and welded to accommodate heterogeneous strain along the irregular East European plate boundary. Shallow structural levels of Alpine tectonic discontinuities in which the locus of most intense strain migrated over time are now exposed as wide retrograde greenschist grade belts. Repeated, mainly transpressive deformation resulted in early ductile fabrics being overprinted by local brittle shear strain. Igneous intrusion accompanied different phases of tectonic activity. The age of shearing initiation is probably late Paleozoic, and the configuration of the zones and their Alpine internal structures are consistent with the geometry of the Carpathian arc.

  19. Geophysical Evidence for Holocene Lake-Level Change in Southern California (Dry Lake): Additional Evidence for a Regional Early Holocene High Stand

    NASA Astrophysics Data System (ADS)

    Kirby, M. E.; Bird, B. W.; Howat, I. M.; Tulaczyk, S.

    2007-12-01

    Ground penetrating radar data are used to develop a Holocene history of basin sedimentation in a small, alpine lake in Southern California (Dry Lake). We define three depositional sequences spanning the past 9,000 calendar years before present (cy BP). Although, the basin contains sediments clearly older than the Holocene, we focus on the past 9,000 cy BP to match our similarly aged sediment cores. Sequence I represents the first phase of an early Holocene high stand. A major regression, perhaps following the 8,200 year cold event, separates Sequence I from Sequence II. The timing of this regression is approximately coeval with major regressions at Owens Lake (Bacon et al., 2006) in southeastern California and Tulare Lake (Negrini et al., 2006) in the southern Central Valley of California. Sequence II represents the second phase of the early Holocene high stand. This second high stand phase is also observed at Tulare Lake but not at Owens Lake. Sequence III represents a permanent shift to low or dry lake stands. By 4,000 cy BP, the lake earns rightfully its appellation of Dry Lake as indicated by a permanently contracted central basin. The similarity in ages of early Holocene lake level change across the greater region of Southern California suggests a similar external forcing - perhaps modulation of early Holocene storm activity by insolation (Kirby et al., 2007). The lake level records are less congruous for the mid-to-late Holocene across the region. Specifically for Dry Lake, it is not clear what caused the apparently rapid shift from a deep, early Holocene lake to a permanent shallow or dry lake by the mid-Holocene.

  20. Great Lakes

    USGS Publications Warehouse

    Edsall, Thomas A.; Mac, Michael J.; Opler, Paul A.; Puckett Haecker, Catherine E.; Doran, Peter D.

    1998-01-01

    The Great Lakes region, as defined here, includes the Great Lakes and their drainage basins in Minnesota, Wisconsin, Illinois, Indiana, Ohio, Pennsylvania, and New York. The region also includes the portions of Minnesota, Wisconsin, and the 21 northernmost counties of Illinois that lie in the Mississippi River drainage basin, outside the floodplain of the river. The region spans about 9º of latitude and 20º of longitude and lies roughly halfway between the equator and the North Pole in a lowland corridor that extends from the Gulf of Mexico to the Arctic Ocean.The Great Lakes are the most prominent natural feature of the region (Fig. 1). They have a combined surface area of about 245,000 square kilometers and are among the largest, deepest lakes in the world. They are the largest single aggregation of fresh water on the planet (excluding the polar ice caps) and are the only glacial feature on Earth visible from the surface of the moon (The Nature Conservancy 1994a).The Great Lakes moderate the region’s climate, which presently ranges from subarctic in the north to humid continental warm in the south (Fig. 2), reflecting the movement of major weather masses from the north and south (U.S. Department of the Interior 1970; Eichenlaub 1979). The lakes act as heat sinks in summer and heat sources in winter and are major reservoirs that help humidify much of the region. They also create local precipitation belts in areas where air masses are pushed across the lakes by prevailing winds, pick up moisture from the lake surface, and then drop that moisture over land on the other side of the lake. The mean annual frost-free period—a general measure of the growing-season length for plants and some cold-blooded animals—varies from 60 days at higher elevations in the north to 160 days in lakeshore areas in the south. The climate influences the general distribution of wild plants and animals in the region and also influences the activities and distribution of the human

  1. `Hearing' alpine plants growing after snowmelt: ultrasonic snow sensors provide long-term series of alpine plant phenology

    NASA Astrophysics Data System (ADS)

    Vitasse, Yann; Rebetez, Martine; Filippa, Gianluca; Cremonese, Edoardo; Klein, Geoffrey; Rixen, Christian

    2016-08-01

    In alpine environments, the growing season is severely constrained by low temperature and snow. Here, we aim at determining the climatic factors that best explain the interannual variation in spring growth onset of alpine plants, and at examining whether photoperiod might limit their phenological response during exceptionally warm springs and early snowmelts. We analysed 17 years of data (1998-2014) from 35 automatic weather stations located in subalpine and alpine zones ranging from 1560 to 2450 m asl in the Swiss Alps. These stations are equipped with ultrasonic sensors for snow depth measurements that are also able to detect plant growth in spring and summer, giving a unique opportunity to analyse snow and climate effects on alpine plant phenology. Our analysis showed high phenological variation among years, with one exceptionally early and late spring, namely 2011 and 2013. Overall, the timing of snowmelt and the beginning of plant growth were tightly linked irrespective of the elevation of the station. Snowmelt date was the best predictor of plant growth onset with air temperature after snowmelt modulating the plants' development rate. This multiple series of alpine plant phenology suggests that currently alpine plants are directly tracking climate change with no major photoperiod limitation.

  2. 'Hearing' alpine plants growing after snowmelt: ultrasonic snow sensors provide long-term series of alpine plant phenology.

    PubMed

    Vitasse, Yann; Rebetez, Martine; Filippa, Gianluca; Cremonese, Edoardo; Klein, Geoffrey; Rixen, Christian

    2017-02-01

    In alpine environments, the growing season is severely constrained by low temperature and snow. Here, we aim at determining the climatic factors that best explain the interannual variation in spring growth onset of alpine plants, and at examining whether photoperiod might limit their phenological response during exceptionally warm springs and early snowmelts. We analysed 17 years of data (1998-2014) from 35 automatic weather stations located in subalpine and alpine zones ranging from 1560 to 2450 m asl in the Swiss Alps. These stations are equipped with ultrasonic sensors for snow depth measurements that are also able to detect plant growth in spring and summer, giving a unique opportunity to analyse snow and climate effects on alpine plant phenology. Our analysis showed high phenological variation among years, with one exceptionally early and late spring, namely 2011 and 2013. Overall, the timing of snowmelt and the beginning of plant growth were tightly linked irrespective of the elevation of the station. Snowmelt date was the best predictor of plant growth onset with air temperature after snowmelt modulating the plants' development rate. This multiple series of alpine plant phenology suggests that currently alpine plants are directly tracking climate change with no major photoperiod limitation.

  3. `Hearing' alpine plants growing after snowmelt: ultrasonic snow sensors provide long-term series of alpine plant phenology

    NASA Astrophysics Data System (ADS)

    Vitasse, Yann; Rebetez, Martine; Filippa, Gianluca; Cremonese, Edoardo; Klein, Geoffrey; Rixen, Christian

    2017-02-01

    In alpine environments, the growing season is severely constrained by low temperature and snow. Here, we aim at determining the climatic factors that best explain the interannual variation in spring growth onset of alpine plants, and at examining whether photoperiod might limit their phenological response during exceptionally warm springs and early snowmelts. We analysed 17 years of data (1998-2014) from 35 automatic weather stations located in subalpine and alpine zones ranging from 1560 to 2450 m asl in the Swiss Alps. These stations are equipped with ultrasonic sensors for snow depth measurements that are also able to detect plant growth in spring and summer, giving a unique opportunity to analyse snow and climate effects on alpine plant phenology. Our analysis showed high phenological variation among years, with one exceptionally early and late spring, namely 2011 and 2013. Overall, the timing of snowmelt and the beginning of plant growth were tightly linked irrespective of the elevation of the station. Snowmelt date was the best predictor of plant growth onset with air temperature after snowmelt modulating the plants' development rate. This multiple series of alpine plant phenology suggests that currently alpine plants are directly tracking climate change with no major photoperiod limitation.

  4. Lake Bonneville

    USGS Publications Warehouse

    Gilbert, Grove Karl

    1890-01-01

    This volume is a contribution to the later physical history of the Great Basin. As a geographic province the Great Basin is characterized by a dry climate, changes of drainage, volcanic eruption, and crustal displacement. Lake Bonneville, the special theme of the volume, was a phenomenon of climate and drainage, but its complete history includes an account of contemporaneous eruption and displacement.

  5. Potentially dangerous glacial lakes in Kyrgyzstan - Research overview of 2004-2015

    NASA Astrophysics Data System (ADS)

    Jansky, Bohumir; Yerokhin, Sergey; Sobr, Miroslav; Engel, Zbynek; Cerny, Michal; Falatkova, Kristyna; Kocum, Jan; Benes, Vojtech

    2016-04-01

    Global warming causes intensive melting and retreat of glaciers in most of high mountains all over the world. This process is also evident in the mountain regions of central Tien Shan. Glacier melt water affects changes in hydrological regime of water streams and causes overfilling of high mountain lake basins. The dams of many lakes are very unstable and can burst open. To determine the degree of such risk, it is necessary to analyse the genesis of lakes, to characterize the morphology of the lake basins and to know the particularities of their hydrological regime. According to the latest inventory within territory of Kyrgyzstan, a total of 1328 lakes have been identified as potentially dangerous, 12 lakes are considered as currently dangerous, other 25 feature high potential hazard. Since 1952 more than 70 disastrous cases of lake outburst have been registered. The hazardous alpine lakes are studied in Kyrgyzstan systematically since 1966. Since 2004, Czech-Kyrgyz research team has been operating in Kyrgyzstan in the field of dangerous glacial lakes. Projects were focused primarily on high-mountain glacial lakes risk assessment, propositions of risk mitigation measures, establishment of permanent research station near one of the studied glacier complexes, preparation of risk analysis for selected endangered valleys, evaluation of climatic and hydrological data and glacier development within observed regions. The most significant portion of data and information has been gathered during field work, complemented by satellite image analysis and surveillance flights over the monitored sites.

  6. Monitoring lake level changes by altimetry in the arid region of Central Asia

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Liao, J. J.; Shen, G. Z.; Zhang, X. L.

    2017-07-01

    The study of lake level changes in arid region of Central Asia not only has important significance for the management and sustainable development of inland water resources, but also provides the basis for further study on the response of lakes to climate change and human activities. Therefore, in this paper, eleven typical lakes in Central Asia were observed. The lake edges were obtained through image interpretation using the quasi-synchronous MODIS image, and then water level information with long period (2002-2015) was acquired using ENVISAT/RA-2 and Cryosat-2 satellite borne radar altimeter data. The results show that these 11 lakes all have obvious seasonal changes of water level in a year with a high peak at different month. During 2002 - 2015, their water levels present decreased trend generally except Sarygamysh Lake, Alakol Lake and North Aral Sea. The alpine lakes are most stables, while open lakes’ levels change the most violently and closed lakes change diversely among different lakes.

  7. Soil moisture mediates alpine life form and community productivity responses to warming.

    PubMed

    Winkler, Daniel E; Chapin, Kenneth J; Kueppers, Lara M

    2016-06-01

    Climate change is expected to alter primary production and community composition in alpine ecosystems, but the direction and magnitude of change is debated. Warmer, wetter growing seasons may increase productivity; however, in the absence of additional precipitation, increased temperatures may decrease soil moisture, thereby diminishing any positive effect of warming. Since plant species show individual responses to environmental change, responses may depend on community composition and vary across life form or functional groups. We warmed an alpine plant community at Niwot Ridge, Colorado continuously for four years to test whether warming increases or decreases productivity of life form groups and the whole community. We provided supplemental water to a subset of plots to alleviate the drying effect of warming. We measured annual above-ground productivity and soil temperature and moisture, from which we calculated soil degree days and adequate soil moisture days. Using an information-theoretic approach, we observed that positive productivity responses to warming at the community level occur only when warming is combined with supplemental watering; otherwise we observed decreased productivity. Watering also increased community productivity in the absence of warming. Forbs accounted for the majority of the productivity at the site and drove the contingent community response to warming, while cushions drove the generally positive response to watering and graminoids muted the community response. Warming advanced snowmelt and increased soil degree days, while watering increased adequate soil moisture days. Heated and watered plots had more adequate soil moisture days than heated plots. Overall, measured changes in soil temperature and moisture in response to treatments were consistent with expected productivity responses. We found that available soil moisture largely determines the responses of this forb-dominated alpine community to simulated climate warming.

  8. Tibetan alpine tundra responses to simulated changes in climate: Aboveground biomass and community responses

    SciTech Connect

    Yanqing Zhang; Welker, J.M.

    1996-05-01

    High-elevation ecosystems are predicted to be some of the terrestrial habitats most sensitive to changing climates. The ecological consequences of changes in alpine tundra environmental conditions are still unclear especially for habitats in Asia. In this study we report findings from a field experiment where an alpine tundra grassland on the Tibetan plateau (37{degrees}N, 101{degrees}E) was exposed to experimental warming, irradiance was lowered, and wind speed reduced to simulate a suite of potential changes in environmental conditions. Our warming treatment increased air temperatures by 5{degrees}C on average and soil temperatures were elevated by 3{degrees}C at 5 cm depth. Aboveground biomass of grasses responded rapidly to the warmer conditions whereby biomass was 25% greater than that of controls after only 5 wk of experimental warming. This increase was accompanied by a simultaneous decrease in forb biomass, resulting in almost no net change in community biomass after 5 wk. Lower irradiance reduced grass biomass during the same period. Under ambient conditions total aboveground community biomass increased seasonally from 161 g m{sup -2} in July to a maximum of 351 g m{sup -2} in September, declining to 285 g m{sup -2} in October. However, under warmed conditions, peak community biomass was extended into October due in part to continued growth of grasses and the postponement of senescence. Our finding indicate that while alpine grasses respond favorably to altered conditions, others may not. And, while peak community biomass may actually change very little under warmer summers, the duration of peak biomass may be extended having feedback effects on net ecosystem CO{sub 2} balances, nutrient cycling, and forage availability. 47 refs., 3 figs., 3 tabs.

  9. Nitrogen deposition and warming - effects on phytoplankton nutrient limitation in subarctic lakes.

    PubMed

    Bergström, Ann-Kristin; Faithfull, Carolyn; Karlsson, Daniel; Karlsson, Jan

    2013-08-01

    The aim of this study was to predict the combined effects of enhanced nitrogen (N) deposition and warming on phytoplankton development in high latitude and mountain lakes. Consequently, we assessed, in a series of enclosure experiments, how lake water nutrient stoichiometry and phytoplankton nutrient limitation varied over the growing season in 11 lakes situated along an altitudinal/climate gradient with low N-deposition (<1 kg N ha(-1)  yr(-1) ) in northern subarctic Sweden. Short-term bioassay experiments with N- and P-additions revealed that phytoplankton in high-alpine lakes were more prone to P-limitation, and with decreasing altitude became increasingly N- and NP-colimited. Nutrient limitation was additionally most obvious in midsummer. There was also a strong positive correlation between phytoplankton growth and water temperature in the bioassays. Although excess nutrients were available in spring and autumn, on these occasions growth was likely constrained by low water temperatures. These results imply that enhanced N-deposition over the Swedish mountain areas will, with the exception of high-alpine lakes, enhance biomass and drive phytoplankton from N- to P-limitation. However, if not accompanied by warming, N-input from deposition will stimulate limited phytoplankton growth due to low water temperatures during large parts of the growing season. Direct effects of warming, allowing increased metabolic rates and an extension of the growing season, seem equally crucial to synergistically enhance phytoplankton development in these lakes.

  10. Changes in fungal community composition in response to experimental soil warming at the alpine treeline

    NASA Astrophysics Data System (ADS)

    Solly, Emily; Lindahl, Bjorn; Dawes, Melissa; Peter, Martina; Souza, Romulo; Rixen, Christian; Hagedorn, Frank

    2017-04-01

    Increased CO2 emissions and global warming may alter the composition of fungal communities through the reduction of low temperature limitation in the plant-soil system, faster nitrogen cycling and changes in the carbon allocation of host plants to the rhizosphere. Shifts in fungal community composition due to global changes are likely to affect the routes of carbon and nitrogen flows in the plant-soil system and alter the rates at which organic matter is decomposed. The main aim of our study was to estimate the effects of multiple years of free air CO2 enrichment (ambient concentration +200 ppm) and soil warming (+ 4°C) on the fungal community structure and composition. At an alpine treeline in Switzerland featuring two key high-elevation tree species, Larix decidua and Pinus uncinata, fungal communities within different organic horizons were analysed by high-throughput 454-pyrosequencing of ITS2 amplicons. In addition, we assessed the ectomycorrhizal community composition on root tips and monitored changes in sporocarp productivity of fungal species during the course of the experiment. Three years of experimental warming at the alpine treeline altered the composition of the fungal community in the organic horizons, whereas nine years of CO2 enrichment had only weak effects. Tree species influenced the composition of the fungal community and the magnitude of the responses of fungal functional groups to soil warming differed between plots with Larix and those with Pinus. The abundance of ectomycorrhizal fungi was positively correlated with nitrogen availability, and ectomycorrhizal taxa specialized for conditions of high nitrogen availability proliferated with warming, corresponding to considerable increases in extractable inorganic nitrogen in warmed soils. Changes in productivity of specific fungal fruiting bodies in response to soil warming (e.g. more Lactarius rufus sporocarps and less Hygrophorus speciousus sporocarps) were consistent with the 454-sequencing

  11. Bedload pulses in a hydropower affected alpine gravel bed river

    NASA Astrophysics Data System (ADS)

    Aigner, Johann; Kreisler, Andrea; Rindler, Rolf; Hauer, Christoph; Habersack, Helmut

    2017-08-01

    This study investigated the sediment resupply and transport dynamics at the Upper Drau River upstream of Lienz (Eastern Tyrol, Austria). Due to a hydropower plant, a 24 km long river reach of this alpine gravel bed river is under residual flow conditions, although sediment is still resupplied into the reach through many active torrents and tributaries. As a result, sediment deposition in the residual flow reach intensified, hence increasing maintenance efforts to stabilize this river section and ensure flood protection. In combination with a new sediment management program, a continuous bedload monitoring system was installed 2 km downstream of the residual reach in 2001 to support the development of adapted sediment management strategies. The surrogate bedload monitoring system consists of 16 impact plate geophones, installed over a 17 m wide cross section. The unprecedented 15-year dataset of high-resolution bedload intensity revealed a complex process of gravel storage and intermittent resupply from the residual reach, allowing the authors a detailed analysis of frequently occurring bedload pulses. These transport features are triggered by increased discharges during floods in the residual reach and created pronounced anticlockwise bedload hysteresis or, with a temporal shift to the event peak, caused distinct shifts in the bedload activity downstream. Bedload pulses produce very high bedload fluxes while in transit, tend to increase bedload flux in the post-event phase, and can alter and reduce the upstream sediment storage leading to a lowering of bedload availability for future pulses. The observed time lags between main discharge events and the arrival of the macro-pulses are correlated with mean water discharge during pulse propagation, thus enabling a prediction of the pulse arrival at the monitoring station solely based on the hydrograph. In combination with the hydrological setup of the reach, the observed bedload pulse time lags allowed an estimation of

  12. Ethnobotany of medicinal plants among the communities of Alpine and Sub-alpine regions of Pakistan.

    PubMed

    Kayani, Sadaf; Ahmad, Mushtaq; Sultana, Shazia; Khan Shinwari, Zabta; Zafar, Muhammed; Yaseen, Ghulam; Hussain, Manzoor; Bibi, Tahira

    2015-04-22

    To best of our knowledge it is first quantitative ethno-botanical study from Alpine and Sub-alpine, Western Himalaya of Pakistan. The study aims to report, compare the uses and highlight the ethno-botanical significance of medicinal plants for treatment of various diseases. A total of 290 (278 males and 12 females) informants including 14 Local Traditional Healers (LTHs) were interviewed. Information was collected using semi-structured interviews, analyzed and compared by quantitative ethno-botanical indices such as Informant Consensus Factor (ICF), Relative frequency of citation (RFC), use value (UV), Fidelity Level (FL) and Jaccard index (JI). A total of 125 plant species (Gymnosperms 7 species, Monocotyledons 2 and 116 Di-cotyledons) belonging to 41 families are collected, identified and ethno-botanically assessed. The most dominant family is Ranunculaceae (20 species) followed by Rosaceae (14 species). In diseases treated, gastrointestinal tract (GIT) diseases have highest proportion (27.5%) followed by respiratory diseases (20%) in the mountain communities. The most dominant life form of plants used is herbs (78%) followed by shrubs (19%) while the most commonly used plant parts are leaves (44 reports) followed by underground part, the roots (37 reports). The highest ICF (0.68) is found for ear, nose and eye disease category followed by respiratory disorders (0.46). There are 15 medicinal plants having 100% FL. Use value (UV) and Relative frequency of citation (RFC) range from 0.03 to 0.53 and 0.04 to 0.23 respectively. In comparison, maximum similarity index is found in the studies with JI 19.52 followed by 17.39. Similarity percentage of plant uses range from 1.69% to 19.52% while dissimilarity percentage varies from 0% to 20%. The Alpine and Sub-alpine regions of Pakistan are rich in medicinal plants and still need more research exploration. On the other hand, ethno-botanical knowledge in study areas is decreasing day by day due to high emigration rates

  13. Organic carbon input from atmospheric deposition: a potential driver of nitrogen export from barren alpine ecosystems (Invited)

    NASA Astrophysics Data System (ADS)

    Mladenov, N.; Williams, M. W.; Schmidt, S. K.

    2010-12-01

    There is urgency to improve our understanding of how biogeochemical cycling and surface water quality in high-elevation catchments will respond to a combination of changes in climate, atmospheric deposition of pollutants, and potential increases in dust deposition. Previous work has shown that atmospheric wet and dry deposition is an important source of dissolved organic matter for alpine lakes, with important consequences for aquatic ecosystem functioning. Here we investigate new linkages between atmospheric deposition of organic matter and terrestrial biogeochemical processes, namely nitrification. Our goal is to better understand the substantial increase in mean annual nitrogen (N) export that has been observed in Rocky Mountain and other alpine watersheds, while N deposition rates have remained constant. The combination of increasing temperatures and dust emissions, melting glaciers, and surprisingly high amounts of microbial activity in recently deglaciated soils, suggest that carbon (C) cycling in these barren alpine catchments may have an important and, thus far, unexplored role in nitrification and N export. Our results show that the quantity of atmospheric organic carbon inputs approaches that of biological C fixation in magnitude. We hypothesize that heterotrophic processing of atmospheric and autotrophic C inputs and the resulting increased availability of amine compounds may enhance nitrification and intensify N export from alpine catchments. Results from optical spectroscopy further demonstrate that water soluble organic carbon from atmospheric deposition has low aromaticity, is high in amino acid-like moieties (Figure 1), and may represent a labile carbon source for terrestrial and aquatic alpine microorganisms. Fig 1. TOP: Fluorescence excitation emission matrix (EEM) of a representative wet deposition sample (collected 24-30 June, 2009 at Niwot Ridge, Colorado). FI = fluorescence index; SUVA = specific UV absorbance (L mg-1 m-1); AA = amino acid

  14. ERTS-1 views the Great Lakes

    NASA Technical Reports Server (NTRS)

    Lyons, W. A.; Pease, S. R.

    1973-01-01

    The meteorological content of ERTS images, particularly mesoscale effects of the Great Lakes and air pollution dispersion is summarized. Summertime lake breeze frontal clouds and various winter lake-effect convection patterns and snow squalls are revealed in great detail. A clear-cut spiral vortex over southern Lake Michigan is related to a record early snow storm in the Chicago area. Marked cloud changes induced by orographic and frictional effects on Lake Michigan's lee shore snow squalls are seen. The most important finding, however, is a clear-cut example of alterations in cumulus convection by anthropogenic condensation and/or ice nuclei from northern Indiana steel mills during a snow squall situation. Jet aircraft condensation trails are also found with surprising frequency.

  15. Will loss of snow cover during climatic warming expose New Zealand alpine plants to increased frost damage?

    PubMed

    Bannister, Peter; Maegli, Tanja; Dickinson, Katharine J M; Halloy, Stephan R P; Knight, Allison; Lord, Janice M; Mark, Alan F; Spencer, Katrina L

    2005-06-01

    year. While warmer temperatures might lower frost resistance, they would also reduce the incidence of frosts, and the incidence of frost damage is unlikely to be altered. The relationship of frost resistance with daylength and temperature potentially provides a means of predicting the responses of alpine plants in response to global warming.

  16. Environmental controls on alpine cirque size

    NASA Astrophysics Data System (ADS)

    Delmas, Magali; Gunnell, Yanni; Calvet, Marc

    2014-02-01

    Pleistocene alpine cirques are emblematic landforms of mountain scenery, yet their deceptively simple template conceals complex controlling variables. This comparative study presents a new database of 1071 cirques, the largest of its kind, located in the French eastern Pyrenees. It is embedded in a review of previous work on cirque morphometry and thus provides a perspective on a global scale. First-order cirque attributes of length, width, and amplitude were measured; and their power as predictors of climatic and lithological variables and as proxies for the duration of glacier activity was tested using ANOVA, simple and multiple linear regression, and their various post-hoc tests. Conventional variables such as cirque aspect, floor elevation, and exposure with respect to regional precipitation-bearing weather systems are shown to present some consistency in spatial patterns determined by solar radiation, the morning-afternoon effect, and wind-blown snow accumulation in the lee of ridgetops. This confirms in greater detail the previously encountered links between landforms and climate. A special focus on the influence of bedrock lithology, a previously neglected nonclimatic variable, highlights the potential for spurious relations in the use of cirque size as a proxy of past environmental conditions. Cirques are showcased as complex landforms resulting from the combination of many climatic and nonclimatic variables that remain difficult to rank by order of importance. Apart from a few statistically weak trends, several combinations of different factors in different proportions are shown to produce similar morphometric outcomes, suggesting a case of equifinality in landform development.

  17. Climatic warming disrupts recurrent Alpine insect outbreaks

    PubMed Central

    Johnson, Derek M.; Büntgen, Ulf; Frank, David C.; Kausrud, Kyrre; Haynes, Kyle J.; Liebhold, Andrew M.; Esper, Jan; Stenseth, Nils Chr.

    2010-01-01

    Climate change has been identified as a causal factor for diverse ecological changes worldwide. Warming trends over the last couple of decades have coincided with the collapse of long-term population cycles in a broad range of taxa, although causal mechanisms are not well-understood. Larch budmoth (LBM) population dynamics across the European Alps, a classic example of regular outbreaks, inexplicably changed sometime during the 1980s after 1,200 y of nearly uninterrupted periodic outbreak cycles. Herein, analysis of perhaps the most extensive spatiotemporal dataset of population dynamics and reconstructed Alpine-wide LBM defoliation records reveals elevational shifts in LBM outbreak epicenters that coincide with temperature fluctuations over two centuries. A population model supports the hypothesis that temperature-mediated shifting of the optimal elevation for LBM population growth is the mechanism for elevational epicenter changes. Increases in the optimal elevation for population growth over the warming period of the last century to near the distributional limit of host larch likely dampened population cycles, thereby causing the collapse of a millennium-long outbreak cycle. The threshold-like change in LBM outbreak pattern highlights how interacting species with differential response rates to climate change can result in dramatic ecological changes. PMID:21059922

  18. Annual variability of ozone along alpine hillsides

    NASA Technical Reports Server (NTRS)

    Putz, Erich; Kosmus, Walter

    1994-01-01

    Over a period of more than two years (March 1989 till June 1991) ozone and nitrogen dioxide have been monitored along twelve alpine hillsides in the Austrian alps. The profiles had a height-resolution of 100 m and cover a range between 400 m and 1800 m asl, that is 100 m to 1100 m above the bottom of the valleys. They were situated in remote rural areas as well as in the vicinity of polluted urban and industrial areas. Both trace gases were monitored by means of integral chemical (SAM-surface active monitor) methods with a measuring cycle of two weeks. The concentration of ozone exhibits a substantial annual variation over the entire height range. In summer, highest ozone levels are observed near the ground and at the top of the mountains, whereas in winter the maxima are found mainly in the crest regions. The overall ozone burden shows a relative maximum near the temperature inversion layer in the valleys and an absolute maximum at the crest.

  19. Fungal Biodiversity in the Alpine Tarfala Valley

    PubMed Central

    Coleine, Claudia; Selbmann, Laura; Ventura, Stefano; D’Acqui, Luigi Paolo; Onofri, Silvano; Zucconi, Laura

    2015-01-01

    Biological soil crusts (BSCs) are distributed worldwide in all semiarid and arid lands, where they play a determinant role in element cycling and soil development. Although much work has concentrated on BSC microbial communities, free-living fungi have been hitherto largely overlooked. The aim of this study was to examine the fungal biodiversity, by cultural-dependent and cultural-independent approaches, in thirteen samples of Arctic BSCs collected at different sites in the Alpine Tarfala Valley, located on the slopes of Kebnekaise, the highest mountain in northern Scandinavia. Isolated fungi were identified by both microscopic observation and molecular approaches. Data revealed that the fungal assemblage composition was homogeneous among the BSCs analyzed, with low biodiversity and the presence of a few dominant species; the majority of fungi isolated belonged to the Ascomycota, and Cryptococcus gilvescens and Pezoloma ericae were the most frequently-recorded species. Ecological considerations for the species involved and the implication of our findings for future fungal research in BSCs are put forward. PMID:27682108

  20. Fungal Biodiversity in the Alpine Tarfala Valley.

    PubMed

    Coleine, Claudia; Selbmann, Laura; Ventura, Stefano; D'Acqui, Luigi Paolo; Onofri, Silvano; Zucconi, Laura

    2015-10-10

    Biological soil crusts (BSCs) are distributed worldwide in all semiarid and arid lands, where they play a determinant role in element cycling and soil development. Although much work has concentrated on BSC microbial communities, free-living fungi have been hitherto largely overlooked. The aim of this study was to examine the fungal biodiversity, by cultural-dependent and cultural-independent approaches, in thirteen samples of Arctic BSCs collected at different sites in the Alpine Tarfala Valley, located on the slopes of Kebnekaise, the highest mountain in northern Scandinavia. Isolated fungi were identified by both microscopic observation and molecular approaches. Data revealed that the fungal assemblage composition was homogeneous among the BSCs analyzed, with low biodiversity and the presence of a few dominant species; the majority of fungi isolated belonged to the Ascomycota, and Cryptococcus gilvescens and Pezoloma ericae were the most frequently-recorded species. Ecological considerations for the species involved and the implication of our findings for future fungal research in BSCs are put forward.

  1. Aortic Dissection Type A in Alpine Skiers

    PubMed Central

    Schachner, Thomas; Fischler, Nikolaus; Dumfarth, Julia; Bonaros, Nikolaos; Krapf, Christoph; Schobersberger, Wolfgang; Grimm, Michael

    2013-01-01

    Patients and Methods. 140 patients with aortic dissection type A were admitted for cardiac surgery. Seventy-seven patients experienced their dissection in the winter season (from November to April). We analyzed cases of ascending aortic dissection associated with alpine skiing. Results. In 17 patients we found skiing-related aortic dissections. Skiers were taller (180 (172–200) cm versus 175 (157–191) cm, P = 0.008) and heavier (90 (68–125) kg versus 80 (45–110) kg, P = 0.002) than nonskiers. An extension of aortic dissection into the aortic arch, the descending thoracic aorta, and the abdominal aorta was found in 91%, 74%, and 69%, respectively, with no significant difference between skiers and nonskiers. Skiers experienced RCA ostium dissection requiring CABG in 17.6% while this was true for 5% of nonskiers (P = 0.086). Hospital mortality of skiers was 6% versus 13% in nonskiers (P = 0.399). The skiers live at an altitude of 170 (0–853) m.a.s.l. and experience their dissection at 1602 (1185–3105; P < 0.001) m.a.s.l. In 82% symptom start was during recreational skiing without any trauma. Conclusion. Skiing associated aortic dissection type A is usually nontraumatic. The persons affected live at low altitudes and practice an outdoor sport at unusual high altitude at cold temperatures. Postoperative outcome is good. PMID:23971024

  2. Reintroduction of lake sturgeon in the St. Louis River, western Lake Superior

    USGS Publications Warehouse

    Schram, Stephen T.; Lindgren, John; Evrard, Lori M.

    1999-01-01

    Lake sturgeon Acipenser fulvescens declined in abundance in Lake Superior's St. Louis River during the late 1800s and were eliminated from the river during the early 1900s because of the combined effects of exploitation, pollution, and habitat alteration. Since then, exploitation in the river and in Lake Superior has been reduced. Furthermore, water quality in the St. Louis River has improved, and its upper-estuary spawning habitat has remained relatively unchanged and adequate. Lake sturgeon have been stocked annually in the St. Louis River since 1983; from 1983 to 1994 stockings included 736,000 fry, 128,000 fingerlings, and 500 yearlings of the Lake Winnebago strain. Relative abundance, distribution, and growth were determined by sampling marked fish in the St. Louis River estuary and western Lake Superior with graded-mesh gill nets and bottom trawls. During 1983–1998, 644 lake sturgeon were caught in 15,486 m of gill net, and 196 were caught in 1,200 trawl tows. Lake sturgeon were sampled most frequently near channelized portions of the St. Louis River and stayed in the estuary up to 5 years before entering Lake Superior. Lake sturgeon were not captured in western Lake Superior prior to stocking, but abundance increased dramatically after 1985. Of 582 lake sturgeon sampled along the Wisconsin shore of Lake Superior from 1985 through 1998 (347,000 m of gill nets), 93% were captured in less than 30 m of water. A total of 93 lake sturgeon were reported from assessment netting conducted along the Minnesota shore of Lake Superior from 1992 through 1997. The current range of stocked lake sturgeon extends from the St. Louis River 145 km east to the apostle Islands in Wisconsin and 110 km northeast to Little Marais in Minnesota. Increases in lake sturgeon abundance were directly attributed to the stocking program. We recommend stocking a minimum of 20 year-classes and the use of a Lake Superior egg source, if possible. Final evaluation of the project will be

  3. Integrating Physical and Chemical Characteristics of Lakes into the Glacially Influenced Landscape of the Northern Cascade Mountains, Washington State, USA.

    PubMed

    Larson; Lomnicky; Hoffman; Liss; Deimling

    1999-09-01

    / A basic knowledge of the physical and chemical characteristics of lakes is needed by management to make informed decisions to protect water resources. In this study we investigated some of the physical and chemical characteristics of 58 lakes in alpine, subalpine, and forest vegetation zones in a natural area (North Cascades National Park Service Complex) between 1989 and 1993. The objectives of the study were to: (1) document the time of ice-out relative to lake elevation; (2) determine how a sharp climate gradient west and east of the hydrologic divide affected the time of ice-out for subalpine lakes; and (3) assess how lake water quality was associated with lake elevation, lake depth, and basin geology. As expected, lake ice-out times occurred earlier with decreasing elevation. East-slope subalpine lakes iced-out earlier than did west-slope subalpine lakes because the east slope of the study area was drier and warmer than the west slope. On average, the lakes were relatively cold, neutral in pH, and low in dissolved substances and concentrations of nitrogen and phosphorus. Although some shallow lakes (depth <10 m) exhibited the highest alkalinities, conductivities, and concentrations of phosphorus and nitrogen, most shallow lakes exhibited low values for these variables that were comparable to values observed in deep lakes. Geology did not play a major role in segregating the lakes based on water quality. Overall, lake temperature, pH, alkalinity, conductivity, and concentrations of total phosphorus and total Kjeldahl N increased with decreasing elevation. These changes in water quality with decreasing elevation in this temperate mountainous region corresponded with warmer air temperatures and increased vegetation biomass, soil depth and maturity, and dissolved substances and nutrients.KEY WORDS: Limnology; Mountain lakes; Water quality; North Cascades National Park Service Complex; National Park Servicehttp://link.springer-ny.com/link/service/journals/00267

  4. Synchoronous inter-hemispheric alpine glacier advances during the Late Glacial?

    NASA Astrophysics Data System (ADS)

    Bakke, Jostein; Paasche, Øyvind

    2016-04-01

    The termination of the last glaciation in both hemispheres was a period of rapid climate swings superimposed on the overall warming trend, resulting from large-scale reorganizations of the atmospheric and oceanic circulation patterns in both hemispheres. Environmental changes during the deglaciation have been inferred from proxy records, as well as by model simulations. Several oscillations took place both in northern and southern hemispheres caused by melt water releases such as during the Younger Dryas in north and the Antarctic Cold Reversal in south. However, a consensus on the hemispheric linkages through ocean and atmosphere are yet to be reached. Here we present a new multi-proxy reconstruction from a sub-annually resolved lake sediment record from Lake Lusvatnet in Arctic Norway compared with a new reconstruction from the same time interval at South Georgia, Southern Ocean, suggesting inter-hemispheric climate linkages during the Bølling/Allerød time period. Our reconstruction of the alpine glacier in the lake Lusvatnet catchment show a synchronous glacier advance with the Birch-hill moraine complex in the Southern Alps, New Zealand during the Intra Allerød Cooling period. We propose these inter hemispheric climate swings to be forced by the northward migration of the southern Subtropical Front during the Antarctic Cold Reversal. Such a northward migration of the Subtropical Front is shown in model simulation and in palaeorecords to reduce the Agulhas leakage impacting the strength of the Atlantic meridional overturning circulation. We simply ask if this can be the carrier of rapid climate swings from one hemisphere to another? Our high-resolution reconstructions provide the basis for an enhanced understanding of the tiny balance between migration of the Subtropical Front in the Southern Ocean and the teleconnection to northern hemisphere.

  5. Effects of the duration of cold stratification on early life stages of the Mediterranean alpine plant Silene ciliata.

    PubMed

    García-Fernández, A; Escudero, A; Lara-Romero, C; Iriondo, J M

    2015-03-01

    Cold stratification provided by snow cover is essential to break seed dormancy in many alpine plant species. The forecast reduction in snow precipitation and snow cover duration in most temperate mountains as a result of global warming could threaten alpine plant populations, especially those at the edge of their species distribution, by altering the dynamics of early life stages. We simulated some effects of a reduction in the snow cover period by manipulating the duration of cold stratification in seeds of Silene ciliata, a Mediterranean alpine specialist. Seeds from three populations distributed along an altitudinal gradient were exposed to different periods of cold stratification (2, 4 and 6 months) in the laboratory and then moved to common garden conditions in a greenhouse. The duration of the cold stratification treatment and population origin significantly affected seed emergence percentage, emergence rate and seedling size, but not the number of seedling leaves. The 6-month and 4-month cold stratification treatments produced higher emergence percentages and faster emergence rates than seeds without cold stratification treatment. No significant cold stratification duration x seed population origin interactions were found, thus differential sensitivity to cold stratification along elevation is not supported. © 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.

  6. Increased stem density and competition may diminish the positive effects of warming at alpine treeline.

    PubMed

    Wang, Yafeng; Pederson, Neil; Ellison, Aaron M; Buckley, Hannah L; Case, Bradley S; Liang, Eryuan; Julio Camarero, J

    2016-07-01

    The most widespread response to global warming among alpine treeline ecotones is not an upward shift, but an increase in tree density. However, the impact of increasing density on interactions among trees at treeline is not well understood. Here, we test if treeline densification induced by climatic warming leads to increasing intraspecific competition. We mapped and measured the size and age of Smith fir trees growing in two treelines located in the southeastern Tibetan Plateau. We used spatial point-pattern and codispersion analyses to describe the spatial association and covariation among seedlings, juveniles, and adults grouped in 30-yr age classes from the 1860s to the present. Effects of competition on tree height and regeneration were inferred from bivariate mark-correlations. Since the 1950s, a rapid densification occurred at both sites in response to climatic warming. Competition between adults and juveniles or seedlings at small scales intensified as density increased. Encroachment negatively affected height growth and further reduced recruitment around mature trees. We infer that tree recruitment at the studied treelines was more cold-limited prior to 1950 and shifted to a less temperature-constrained regime in response to climatic warming. Therefore, the ongoing densification and encroachment of alpine treelines could alter the way climate drives their transitions toward subalpine forests.

  7. Biological consequences of earlier snowmelt from desert dust deposition in alpine landscapes

    PubMed Central

    Steltzer, Heidi; Landry, Chris; Painter, Thomas H.; Anderson, Justin; Ayres, Edward

    2009-01-01

    Dust deposition to mountain snow cover, which has increased since the late 19th century, accelerates the rate of snowmelt by increasing the solar radiation absorbed by the snowpack. Snowmelt occurs earlier, but is decoupled from seasonal warming. Climate warming advances the timing of snowmelt and early season phenological events (e.g., the onset of greening and flowering); however, earlier snowmelt without warmer temperatures may have a different effect on phenology. Here, we report the results of a set of snowmelt manipulations in which radiation-absorbing fabric and the addition and removal of dust from the surface of the snowpack advanced or delayed snowmelt in the alpine tundra. These changes in the timing of snowmelt were superimposed on a system where the timing of snowmelt varies with topography and has been affected by increased dust loading. At the community level, phenology exhibited a threshold response to the timing of snowmelt. Greening and flowering were delayed before seasonal warming, after which there was a linear relationship between the date of snowmelt and the timing of phenological events. Consequently, the effects of earlier snowmelt on phenology differed in relation to topography, which resulted in increasing synchronicity in phenology across the alpine landscape with increasingly earlier snowmelt. The consequences of earlier snowmelt from increased dust deposition differ from climate warming and include delayed phenology, leading to synchronized growth and flowering across the landscape and the opportunity for altered species interactions, landscape-scale gene flow via pollination, and nutrient cycling. PMID:19564599

  8. Response of alpine grassland to elevated nitrogen deposition an