DOCSLIB.ORG

Different Pockmark Systems and Their Potential Importance for the Hydrological and Biogeochemical Balance of a Perialpine Lake

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Different Pockmark Systems and Their Potential Importance for the Hydrological and Biogeochemical Balance of a Perialpine Lake Different pockmark systems and their potential importance for the hydrological and biogeochemical balance of a perialpine lake Adeline N.Y. Cojean*, Maciej Bartosiewicz**, Jeremy Zimmermann*, Moritz F. Lehmann**, Katrina Kremer*** and Stefanie B. Wirth* * Centre for Hydrogeology and Geothermics, University of Neuchatel, Rue Emile-Argand 11, CH-2000 Neuchâtel ([email protected]) ** Department of Environmental Sciences, University of Basel, Bernoullistrasse 30, CH-4056 Basel ***Swiss Seismological Service (SED), ETH Zürich, Sonneggstrasse 5, CH-8006 Zürich Lacustrine pockmarks Ø Much less investigated than marine pockmark systems Ø Fluid-flow formation Ø CH4 gas ebullition => Lake Constance (Wessel 2010; Bussmann, 2011) Ø Groundwater discharge => Lake Neuchâtel (Reusch 2015; Wirth et al., in prep.) Pockmarks in Lake Thun, Switzerland Thun Lake Thun Tannmoos Fault gypsum carying bedrock Einigen Fault Zone Spiez Fabbri et al., 2017 Beatenberg Interlaken Research questions Thun Ø Are there more pockmarks in Lake Lake Thun Thun? Ø If yes, where are they? Ø What is their mechanism of formation? Spikes in electrical Taanmoos conductivity Ø What is their influence on the lake hydrological and biogeochemical Einigen budget? Fault Zone Beatenberg karst system Spiez Beatenberg Beaten Connected to Daerligen karst system Interlaken Intensive CH4 bubbling Different pockmarks systems in Lake Thun Thun Lake Thun Connection to karst system leads to groundwater discharge? Tannmoos Einigen Fault Zone Beatenberg karst system Spiez Beatenberg Beaten Daerligen Interlaken Results – Beaten (connected to karst system) Pockmark Sediment overflowSediment overflow Reference Ø More intense groundwater discharge to the lake in the past Ø Episodically active Pockmark Reference Different pockmarks systems in Lake Thun Thun Lake Thun Tannmoos Einigen Fault Zone Beatenberg karst system Spiez Beatenberg Beaten Daerligen Interlaken Results – Därligen (CH4 bubbling) Gas bubbling Pockmark Different pockmarks systems in Lake Thun Thun Lake Thun Tannmoos Einigen Fault Zone Beatenberg karst system Spiez Beatenberg Beaten Spikes in electrical conductivity and more liquefied sediments in Daerligen the pockmark suggest Interlaken groundwater discharge? Results – Tannmoos (groundwater discharge) Results – Tannmoos (groundwater discharge) Pockmark Pockmark Reference Reference Water depth (m) Water Water depth (m) Water Sediment (cm) depth Sediment (cm) depth -1 + -1 Total dissolved Fe concentration (µmol L ) Total dissolved NH4 concentration (µmol L ) Ø NH + concentration is also lower inside the pockmark, particularly in deeper sediment layers 4 + Ø Total dissolved Fe and NH4 display similar vertical profiles Take-home messages Lake Thun Ø Three pockmark systems were found in Lake Thun Ø Variable formation mechanisms; via gas-flow at Därligen and groundwater discharge at Tannmoos and Beatenberg Tannmoos Ø More liquified sediments inside the pockmark than at a reference site + Ø Lower total dissolved Fe and NH4 concentrations inside the pockmark than at a reference site => episodic O2 penetration? Active groundwater discharge? Ø Further experimental work and sampling campaigns will help to better assess the influence of this pockmark system on the lake biogeochemistry .
Load more

Recommended publications
  • Human Impact on the Transport of Terrigenous and Anthropogenic Elements to Peri-Alpine Lakes (Switzerland) Over the Last Decades
    Aquat Sci (2013) 75:413–424 DOI 10.1007/s00027-013-0287-6 Aquatic Sciences RESEARCH ARTICLE Human impact on the transport of terrigenous and anthropogenic elements to peri-alpine lakes (Switzerland) over the last decades Florian Thevenon • Stefanie B. Wirth • Marian Fujak • John Pote´ • Ste´phanie Girardclos Received: 22 August 2012 / Accepted: 6 February 2013 / Published online: 22 February 2013 Ó The Author(s) 2013. This article is published with open access at Springerlink.com Abstract Terrigenous (Sc, Fe, K, Mg, Al, Ti) and suspended sediment load at a regional scale. In fact, the anthropogenic (Pb and Cu) element fluxes were measured extensive river damming that occurred in the upstream in a new sediment core from Lake Biel (Switzerland) and watershed catchment (between ca. 1930 and 1950 and up to in previously well-documented cores from two upstream 2,300 m a.s.l.) and that significantly modified seasonal lakes (Lake Brienz and Lake Thun). These three large peri- suspended sediment loads and riverine water discharge alpine lakes are connected by the Aare River, which is the patterns to downstream lakes noticeably diminished the main tributary to the High Rhine River. Major and trace long-range transport of (fine) terrigenous particles by the element analysis of the sediment cores by inductively Aare River. Concerning the transport of anthropogenic coupled plasma mass spectrometry (ICP-MS) shows that pollutants, the lowest lead enrichment factors (EFs Pb) the site of Lake Brienz receives three times more terrige- were measured in the upstream course of the Aare River at nous elements than the two other studied sites, given by the the site of Lake Brienz, whereas the metal pollution was role of Lake Brienz as the first major sediment sink located highest in downstream Lake Biel, with the maximum val- in the foothills of the Alps.
    [Show full text]
  • Constitution of an Automized Processing Chain to Analyse a Meris Time Series of Swiss Lakes
    CONSTITUTION OF AN AUTOMIZED PROCESSING CHAIN TO ANALYSE A MERIS TIME SERIES OF SWISS LAKES Daniel Odermatt a, *, Thomas Heege b, Jens Nieke a, Mathias Kneubühler a and Klaus Itten a a Remote Sensing Laboratories (RSL), Dept. of Geography, University of Zurich, Winterthurerstrasse 190, CH-8050 Zurich, Switzerland - (dodermat, nieke, kneub, itten)@geo.unizh.ch b EOMAP GmbH & Co. KG, Sonderflughafen Oberpfaffenhofen, D-82205 Gilching, Germany - [email protected] KEY WORDS: Inland water, Case II water, lakes, MERIS, water constituents ABSTRACT: The physically based Modular Inversion & Processing System (MIP) is used in an automized processing chain for inland water constituent retrieval from MERIS level 1B data. Preprocessing routines are used to automatically convert the ESA generic data products into MIP input data format. Water/land masking, atmospheric correction and water constituent retrieval are accomplished by simple batch executables from MIP. The accuracy of the constituent retrieval mainly depends on the spectral fit between the image input data and the radiative transfer model results extracted from a database. Therefore, thresholds and initial values for model fitting have to account for all occurring lake specific temporal variations and need careful adjustment. 1. INTRODUCTION Heege, 2000), using the Modular Inversion & Processing System (MIP) (Heege and Fischer, 2004). Monitoring of water quality in lakes is required as an integral part of water resource management, in order to guarantee the In this work, a processing chain to automatically derive water sustainable use of water and to track the effects of constituents from MERIS level 1B data for Swiss lakes is built anthropogenic influences. Simultaneously, adequate monitoring around MIP.
    [Show full text]
  • Active Faulting in Lake Constance (Austria, Germany, Switzerland) Unraveled by Multi-Vintage Reflection Seismic Data
    ORIGINAL RESEARCH published: 11 August 2021 doi: 10.3389/feart.2021.670532 Active Faulting in Lake Constance (Austria, Germany, Switzerland) Unraveled by Multi-Vintage Reflection Seismic Data S.C. Fabbri 1*, C. Affentranger 1, S. Krastel 2, K. Lindhorst 2, M. Wessels 3, Herfried Madritsch 4, R. Allenbach 5, M. Herwegh 1, S. Heuberger 6, U. Wielandt-Schuster 7, H. Pomella 8, T. Schwestermann 8 and F.S. Anselmetti 1 1Institute of Geological Sciences and Oeschger Centre of Climate Change Research, University of Bern, Bern, Switzerland, 2Institute of Geosciences, Christian-Albrechts-Universität zu Kiel, Kiel, Germany, 3Institut für Seenforschung der LUBW, Langenargen, Germany, 4National Cooperative for the Disposal of Radioactive Waste (NAGRA), Wettingen, Switzerland, 5Federal Office of Topography Swisstopo, Wabern, Switzerland, 6Department of Earth Sciences, ETH Zürich, Zürich, Switzerland, 7Landesamt für Geologie, Rohstoffe und Bergbau Baden-Württemberg, Freiburg i. Br., Germany, 8Department of Geology, University of Innsbruck, Innsbruck, Austria Probabilistic seismic hazard assessments are primarily based on instrumentally recorded Edited by: and historically documented earthquakes. For the northern part of the European Alpine Francesco Emanuele Maesano, Istituto Nazionale di Geofisicae Arc, slow crustal deformation results in low earthquake recurrence rates and brings up the Vulcanologia (INGV), Italy necessity to extend our perspective beyond the existing earthquake catalog. The Reviewed by: overdeepened basin of Lake Constance (Austria, Germany, and Switzerland), located Chiara Amadori, within the North-Alpine Molasse Basin, is investigated as an ideal (neo-) tectonic archive. University of Pavia, Italy Alessandro Maria Michetti, The lake is surrounded by major tectonic structures and constrained via the North Alpine University of Insubria, Italy Front in the South, the Jura fold-and-thrust belt in the West, and the Hegau-Lake *Correspondence: Constance Graben System in the North.
    [Show full text]
  • Print Itinerary
    +1 888 396 5383 617 776 4441 [email protected] DUVINE.COM Europe / Switzerland Switzerland Bike Tour Cheese to Chalets in Interlaken, Lucerne, and Beyond © 2021 DuVine Adventure + Cycling Co. Sample Swiss cheese and chocolate right where it’s made Experience the abundance of outdoor landmarks in Interlaken and the jet-set appeal of Gstaad Conquer the Brünig Pass, which links the cities of Interlaken and Lucerne Cycle the shores of Lake Lucerne through quaint communities, Alpine pastures, and vineyards of Riesling and Sauvignon Blanc Arrival Details Departure Details Airport City: Airport City: Geneva, Switzerland Zurich, Switzerland Pick-Up Location: Drop-Off Location: Aigle Train Station Lucerne Train Station Pick-Up Time: Drop-Off Time: 11:30 am 11:00 am NOTE: DuVine provides group transfers to and from the tour, within reason and in accordance with the pick-up and drop-off recommendations. In the event your train, flight, or other travel falls outside the recommended departure or arrival time or location, you may be responsible for extra costs incurred in arranging a separate transfer. Emergency Assistance For urgent assistance on your way to tour or while on tour, please always contact your guides first. You may also contact the Boston office during business hours at +1 617 776 4441 or [email protected]. Travelers Take Note Hiking shoes are recommended for the hike on this tour. We suggest hiking boots or trail shoes with good traction. You may also find moisture-wicking clothing or a daypack useful, but not required. Tour By Day DAY 1 A Very Swiss Beginning Your DuVine guides will greet you in Aigle for a transfer to L'Etivaz, where our tour begins.
    [Show full text]
  • Quaternary Glaciation History of Northern Switzerland
    Quaternary Science Journal GEOzOn SCiEnCE MEDiA Volume 60 / number 2–3 / 2011 / 282–305 / DOi 10.3285/eg.60.2-3.06 iSSn 0424-7116 E&G www.quaternary-science.net Quaternary glaciation history of northern switzerland Frank Preusser, Hans Rudolf Graf, Oskar keller, Edgar krayss, Christian Schlüchter Abstract: A revised glaciation history of the northern foreland of the Swiss Alps is presented by summarising field evidence and chronologi- cal data for different key sites and regions. The oldest Quaternary sediments of Switzerland are multiphase gravels intercalated by till and overbank deposits (‘Deckenschotter’). Important differences in the base level within the gravel deposits allows the distin- guishing of two complex units (‘Höhere Deckenschotter’, ‘Tiefere Deckenschotter’), separated by a period of substantial incision. Mammal remains place the older unit (‘Höhere Deckenschotter’) into zone MN 17 (2.6–1.8 Ma). Each of the complexes contains evidence for at least two, but probably up-to four, individual glaciations. In summary, up-to eight Early Pleistocene glaciations of the Swiss alpine foreland are proposed. The Early Pleistocene ‘Deckenschotter’ are separated from Middle Pleistocene deposition by a time of important erosion, likely related to tectonic movements and/or re-direction of the Alpine Rhine (Middle Pleistocene Reorganisation – MPR). The Middle-Late Pleistocene comprises four or five glaciations, named Möhlin, Habsburg, Hagenholz (uncertain, inadequately documented), Beringen, and Birrfeld after their key regions. The Möhlin Glaciation represents the most extensive glaciation of the Swiss alpine foreland while the Beringen Glaciation had a slightly lesser extent. The last glacial cycle (Birrfeld Glaciation) probably comprises three independent glacial advances dated to ca.
    [Show full text]
  • River Corrections and Long-Term Changes in Flood Risk in the Aare Valley, Switzerland
    E3S Web of Conferences7, 11010 (2016) DOI: 10.1051/ e3sconf/20160711010 FLOOD risk 2016 - 3rd European Conference on Flood Risk Management River corrections and long-term changes in flood risk in the Aare valley, Switzerland Andreas Zischg1,a 1Institute of Geography, Oeschger Centre for Climate Change Research, Mobiliar Lab for Natural Risks, University of Bern, 3012 Bern, Switzerland Abstract. Flood risk is changing over time. Beside climatic changes, key drivers for changing flood risks are the modification of the river courses by flood defence structures and the increase in properties exposed to floods due to economic development. In this study, both effects – the modification of the river courses and the increase of economic assets – on the long-term evolution of flood risk were isolated and confronted. To this aim, two states of the river network were compared, one representing the river courses of today and another representing the river courses of the early 19th century before the river corrections took place. Selected observed and well documented flood events of the last decades were modelled on the historic states of the river reaches. The documented flood events were compared with the simulations in terms of inundated area and exposed buildings. Without river corrections, the flooded areas and the number of exposed residential housings would be remarkably higher than observed in recent flood events. The examples show that the effects of the main river corrections are remarkable for today’s economic activities in the floodplains. Therefore, the maintenance of the former river correction works is an important part of today’s risk management practice.
    [Show full text]
  • Published Version
    A peer-reviewed open-access journal ZooKeys 989: 79–162A taxonomic (2020) revision of the whitefish radiation of lakes Brienz and Thun 79 doi: 10.3897/zookeys.989.32822 RESEARCH ARTICLE http://zookeys.pensoft.net Launched to accelerate biodiversity research A taxonomic revision of the whitefish of lakes Brienz and Thun, Switzerland, with descriptions of four new species (Teleostei, Coregonidae) Oliver M. Selz1,2, Carmela J. Dönz1,2, Pascal Vonlanthen1,3, Ole Seehausen1,2 1 Department of Fish Ecology and Evolution, Centre for Ecology, Evolution & Biogeochemistry, Eawag: Swiss Federal Institute of Aquatic Science and Technology, 6047 Kastanienbaum, Switzerland 2 Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland 3 Aquabios GmbH, Les Fermes 57, 1792 Cordast, Switzerland Corresponding author: Oliver M. Selz ([email protected]) Academic editor: M. E. Bichuette | Received 3 January 2019 | Accepted 7 August 2019 | Published 9 November 2020 http://zoobank.org/F78F6D87-9DDB-4CD9-8E4C-60E4883A59B6 Citation: Selz OM, Dönz CJ, Vonlanthen P, Seehausen O (2020) A taxonomic revision of the whitefish of lakes Brienz and Thun, Switzerland, with descriptions of four new species (Teleostei, Coregonidae). ZooKeys 989: 79–162.https:// doi.org/10.3897/zookeys.989.32822 Abstract The alpha taxonomy of the endemic whitefish of lakes Brienz and Thun, Switzerland, is revised. We evaluate the status of seven known species: Coregonus steinmanni sp. nov., Coregonus profundus sp. nov. and Coregonus acrinasus sp. nov. are endemic to Lake Thun; Coregonus brienzii sp. nov. is endemic to Lake Brienz; and C. alpinus, C. albellus, and C. fatioi from lakes Brienz and Thun are redescribed.
    [Show full text]
  • Hypolimnetic Oxygen Depletion Rates in Deep Lakes: Effects of Trophic State and Organic Matter Accumulation
    Limnol. Oceanogr. 9999, 2020, 1–11 © 2020 The Authors. Limnology and Oceanography published by Wiley Periodicals LLC on behalf of Association for the Sciences of Limnology and Oceanography. doi: 10.1002/lno.11578 Hypolimnetic oxygen depletion rates in deep lakes: Effects of trophic state and organic matter accumulation Thomas Steinsberger ,1 Robert Schwefel ,2,3 Alfred Wüest ,1,3 Beat Müller 1* 1Eawag, Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland 2UC Santa Barbara, Santa Barbara, California 3Physics of Aquatic Systems Laboratory, Margaretha Kamprad Chair, École Polytechnique Fédérale de Lausanne, Institute of Environmental Engineering, Lausanne, Switzerland Abstract This study investigated the consumption of oxygen (O2) in 11 European lakes ranging from 48 m to 372 m deep. In lakes less than ~ 100 m deep, the main pathways for O2 consumption were organic matter (OM) mineralization at the sediment surface and oxidation of reduced compounds diffusing up from the sedi- ment. In deeper lakes, mineralization of OM transported through the water column to the sediment represented a greater proportion of O2 consumption. This process predominated in the most productive lakes but declined with decreasing total phosphorous (TP) concentrations and hence primary production, when TP concentrations − fell below a threshold value of ~ 10 mg P m 3. Oxygen uptake by the sediment and the flux of reduced com- − − pounds from the sediment in these deep lakes were 7.9–10.6 and 0.6–3.6 mmol m 2 d 1, respectively. These parameters did not depend on the lake’s trophic state but did depend on sedimentation rates for the primarily allochthonous or already degraded OM.
    [Show full text]
  • Fly to Zurich, Switzerland Your Day Begins With
    Day One Home pickup / transfer to airport Overnight flight to Zurich, Switzerland Day Two Visit Bern, Switzerland Travel to village of Wengen to check in for six-night stay at Hotel Silberhorn Day Three Day-trip to Interlaken, Switzerland Cog-railway ride to Schynige Platte Steam cruise on Lake Brienz Day Four Optional rail journey to Jungfraujoch Mountain Visit village of Grindelwald Cable car ride through the Alps Day Five Cruise on Lake Thun Journey through the Grosse Scheidegg mountain pass to Schwarzwaldalp Visit famous Reichenbach Falls Day Six Rail excursion to the glacier-carved Lauterbrunnen Valley Visit Trummelbach Falls Cable car ride to Gimmelwald Day 2 - Lauterbrunnen / Wengen Day Seven Arrive in Zurich, board our coach and Walking tour through alpine meadows & travel through the Swiss landscape forests to Staubbachbankeli Overlook past sparkling lakes. Stop in the Day Eight capital city, Bern, to see the Rose Day 1 - Fly to Zurich, Switzerland Gardens & Glockenspiel. Then it's up Travel to Lucerne to see Lion’s Your day begins with chauffeured into the massive Swiss Alps. The Monument & Chapel Bridge home pickup and an overnight flight scenery is increasingly spectacular Continue on to Zurich for a farewell to Zurich, Switzerland. [In Flight as you arrive in Lauterbrunnen, with dinner and one night at the Dorint Hotel Meal] its towering cliffs. Then, travel by cog Day Nine Fly to San Diego Airport transfer to home Hotel Silberhorn - Wengen, Switz. Dorint Hotel - Zurich, Switz. spectacular views. Then, return to Wengen via the Mannlichenbahn cable car. [B, D] Day 5 - Reichenbach Falls Ride the train down to Interlaken and cruise Lake Thun to Grindelwald to board a PTT bus for an excursion over the Grosse Scheidegg to Schwarzwaldalp.
    [Show full text]
  • Extreme Flood Events on the River Aare 1
    Extreme flood events on the River Aare 1 Key findings and results of the EXAR project Extreme flood events on the River Aare Key findings and results of the EXAR project 2 Extreme flood events on the River Aare Key findings and results of the EXAR project Contents 4 The EXAR project provides an important basis for decision-making in order to better protect the population and key infrastructure on the River Aare from flooding in the future. 7 By combining different models and simulation programs, the ex- perts were able to determine the peak discharges of the Aare over a period of almost 300,000 years. 10 Because of the much longer time horizon, the flood peaks on the Aare can be significantly higher than previously expected in the case of extremely rare events. For example, upstream of the point where it joins the Rhine, discharge values of over 7,000 cubic metres per second are possible, around 12 times the average discharge. 14 In the drainage basin, there are six key sites capable of influencing the flow behaviour of the Aare supra-regionally. Highly unlikely dam failures could flood large areas of the Seeland with several metres of water. 19 EXAR provides detailed hazard assessments for five locations, including the sites of the nuclear power plants on the Aare. They show that flooding is possible, especially in the case of structural failures and blockages by large wood. 28 The expert assessments, calculations and simulations of natural processes and technical structural failures are subject to uncertain- ties. Although only an approximation to real events is possible, EXAR will help to improve the assessment of flood hazard on the Aare.
    [Show full text]
  • Genomic Signatures of Relaxed Disruptive Selection Associated with Speciation Reversal in Whitefish Hudson Et Al
    Genomic signatures of relaxed disruptive selection associated with speciation reversal in whitefish Hudson et al. Hudson et al. BMC Evolutionary Biology 2013, 13:108 http://www.biomedcentral.com/1471-2148/13/108 Hudson et al. BMC Evolutionary Biology 2013, 13:108 http://www.biomedcentral.com/1471-2148/13/108 RESEARCH ARTICLE Open Access Genomic signatures of relaxed disruptive selection associated with speciation reversal in whitefish Alan G Hudson1,2,3*, Pascal Vonlanthen1,2, Etienne Bezault1,2,4 and Ole Seehausen1,2 Abstract Background: Speciation reversal: the erosion of species differentiation via an increase in introgressive hybridization due to the weakening of previously divergent selection regimes, is thought to be an important, yet poorly understood, driver of biodiversity loss. Our study system, the Alpine whitefish (Coregonus spp.) species complex is a classic example of a recent postglacial adaptive radiation: forming an array of endemic lake flocks, with the independent origination of similar ecotypes among flocks. However, many of the lakes of the Alpine radiation have been seriously impacted by anthropogenic nutrient enrichment, resulting in a collapse in neutral genetic and phenotypic differentiation within the most polluted lakes. Here we investigate the effects of eutrophication on the selective forces that have shaped this radiation, using population genomics. We studied eight sympatric species assemblages belonging to five independent parallel adaptive radiations, and one species pair in secondary contact. We used AFLP markers, and applied FST outlier (BAYESCAN, DFDIST) and logistic regression analyses (MATSAM), to identify candidate regions for disruptive selection in the genome and their associations with adaptive traits within each lake flock.
    [Show full text]
  • Rellstab, C., B. Keller, S. Girardclos, F.S
    Limnol. Oceanogr., 56(1), 2011, 292–302 E 2011, by the American Society of Limnology and Oceanography, Inc. doi:10.4319/lo.2011.56.1.0292 Anthropogenic eutrophication shapes the past and present taxonomic composition of hybridizing Daphnia in unproductive lakes Christian Rellstab,a,b,1,* Barbara Keller,a,2 Ste´phanie Girardclos,c,3 Flavio S. Anselmetti,a and Piet Spaaka,b a Eawag, Swiss Federal Institute of Aquatic Science and Technology, Du¨bendorf, Switzerland bInstitute of Integrative Biology, Swiss Federal Institute of Technology (ETH) Zu¨rich, Zu¨rich, Switzerland c Geological Institute, ETH Zu¨rich, Zu¨rich, Switzerland Abstract It has been proposed that anthropogenic eutrophication of lakes facilitated the establishment of populations of the cladoceran Daphnia galeata into the originally oligotrophic lakes north of the European Alps in the 1960s. This hypothesis lacks the support of studies on unproductive lakes, in which the past eutrophication is assumed to have never been on the level necessary for D. galeata to reach high abundances and to establish permanently. In order to investigate if such species shifts also happened in unproductive systems, we studied the past and present taxonomic composition of three ultra-oligotrophic Swiss lakes that were only marginally affected by eutrophication using molecular methods on diapausing eggs sampled from sediment cores. D. galeata temporarily established in unproductive lakes, but its colonization success seemed to depend on the general trophic state of the lake and the magnitude of eutrophication. In two of the studied lakes, D. galeata could establish a significant population size, whereas it was not successful in the most unproductive lake with the weakest eutrophication.
    [Show full text]