Life at the Edge: The Limits of Occurrence of Insect Larvae
Survival of animals under extreme environmental conditions has always been intriguing to ecologists and physiologists. Examples for an extreme environment are brooks in mountainous areas with different degrees of harshness. Despite the harsh conditions, these rivers are densely populated by chironomids (Diptera: Chironomidae) who are even found close to the mouth of glaciers. We hypothesize that i) different pathways of metabolism are differently affected by very low temperature, ii) carbohydrate metabolism may be more flexible than e.g. lipid metabolism, and iii) these differences are based on subspeciation and not a pure metabolic phenomenon. The study sites for this project are high alpine streams with a harshness gradient located in the Alps and the Tatra Mts. We assume that the harshness gradient must be strong enough to limit the occurrence of chironomid larvae and energy stores of an animal are a good proxy for its health. To study thresholds for survival of the high alpine stream chironomids in the past, lake sediments cores from 3 sites in the Bohemian Forest will be used.
Goals:
Characterization of the harshness gradients; quantification of energy stores in individuals from different sites; tracing of selected genes from endocrine to metabolic regulation; characterization of genetic homogeneity; paleolimnological evidence of past populations’ response to the deglaciation.
Principal investigator: Evžen Stuchlík
Co-investigator: Günther Kletetschka
Grantor: Czech Science Foundation
Duration: 01/01/20 – 12/31/22
Grant number: 20-00892L
Award amount: 5,469,000 CZK ($235,174)
Paleo-records of global range events from lake sedimentary sequence
A multiple evidence from increasing number of sites shows that a major cosmic impact occurred at the end of the Pleistocene. The so-called Younger Dryas Boundary layer (YDB) supports the hypothesis that a fragmented cosmic body slammed into the Earth ~12,800 cal. BP at the time of the Younger Dryas cooling onset. This layer contains a characteristic assemblage of impactrelated particles and elemental composition. Simultaneously, megafaunal extinctions, changes in vegetation cover, human population cultural shifts, and widespread wildfires were documented. In Europe, YBD records are still rare and most of them are known from paleosoils. We have focused on lake sediment sequences and identified the presence of YDB markers in Bohemian Forest lakes, Czech Republic. Our first results suggest environmental contamination of the region by long-range atmospheric transport of pollutants. In the proposed project, we will study history of three selected lake-catchment ecosystems with focus on the YDB transition and identification of Late Glacial and Early Holocene tephra layers.
Goals:
1) Testing of uniqueness of the YBD proxies within the postglacial sedimentary records.
2) Identification of volcanic ash (tephra) layers in lake sediments of Late Glacial and Early Holocene age.
3) Reconstruction of ecosytems’ reaction on the YDB environmental contamination.
Principal investigator: Evžen Stuchlík
Co-investigator: Günther Kletetschka
Grantor: Czech Science Foundation
Duration: 01/01/20 – 12/31/22
Grant number: 20-08294S
Award amount: 9,987,000 CZK ($431,000)
Paleoecology Reconstruction of Global Environmental Changes at the Beginning of Younger Dryas
Goals:
1. To test the hypothesis that the Laacher See volcanic explosion (12900 calibrated years BP) changed freshwater communities in the Bohemian Forest lakes.
2. To test the hypothesis that the Younger Dryas Boundary (YDB) layer (well-known from many North American sedimentary sequences) is also present in sediments of the Bohemian Forest lakes. If yes, this layer has characteristic geochemical and geophysical signal, contains impact-related micro-spherules (MSPs), and could be used as an important tool for regional chronostratigraphy.
3. To test the hypothesis that YDB is present in selected Alaska lakes. If yes, YDB will be compared with YDB found at the Czech sites.
4. To test the hypothesis that the Younger Dryas (YD) onset was characterized by changes in environmental chemistry, a decrease in biota abundances and biodiversity, or a shift in composition of ecological groups in the studied palaeoecosystems. If yes, which factors were responsible for the ecosystem damage and transformation? Was the YD onset more pronounced in Alaska lakes or in the Czech lakes?
5. To determine the timing of the presumed sudden environmental changes at the YD onset in both regions (central Europe and Alaska) and compare the results with the geochemical data from the Greenland ice (especially with the North Greenland Ice Core Project record).
Principal investigator: Günther Kletetschka
Co-investigator: Evžen Stuchlík
Grantor: Ministry of Education, Youth and Sports (Czech Republic) – MEYS
Duration: 01/11/19 – 10/31/22
Grant number: LTAUSA 19141
Award amount: 5,855,000 CZK ($253,000)
Details of Magnetic Reversal and Paleosecular Variations from Sediments
Goal: In this study we will try to identify a magnetic reversal (C5Dn/C5Cr) in Miocene paleolake sediments from the Most Basin, Czech Republic. We plan to resolve any anomalous geomagnetic field fluctuation, in both its direction and intensity, by detailed analyses of magnetic petrology and its relation to magnetic remanence acquisition. The sedimentary cores will be analyzed for secular magnetic variations to constrain any significant magnetic pole migrations. Magnetic data over this time period would provide an additional tool for chronological assessment. For this purpose, we will use detailed paleomagnetism and rock magnetism measurements to figure out the characterization of magnetic reversal and magnetic carriers of sediments. XRF, XRD and Mossbauer measurements will be used to identify elementary and mineralogical composition of the sediment.
Working schedule includes preparing sediment samples, laboratory measurements, analyzing and interpreting the data, finalizing the project and presenting the results. This will be the first detailed paleomagnetism study of the C5Dn/C5Dr reversal on central European lacustrine sediments and fourth study on lacustrine sediments around the Earth in the literature so far. The results are planned to be published in international conferences and journals and as a doctoral thesis.
Principal investigator: Hakan Ucar
Co-investigator: Günther Kletetschka
Grantor: Charles University Grant Agency (GAUK)
Duration: 2021-01 to 2023-12
Grant number: 265321
Award amount: 675,000 CZK ($28,000)