Sökning: "diatoms"

Visar resultat 1 - 5 av 69 avhandlingar innehållade ordet diatoms.

  1. 1. Diatoms in Lake Duluti : Tracking Environmental Variability in Northern Tanzania during the Past 1000 Years

    Detta är en avhandling från Stockholm : Department of Physical Geography and Quaternary Geology, Stockholm University

    Författare :Helena Öberg; Stockholms universitet.; [2011]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Paleolimnology; Tanzania; Diatoms; Climate change; Crater lake; Physical Geography; naturgeografi;

    Sammanfattning : The tropics are the regions which are least understood climatically and new data on past climate variability is necessary for reliable future modeling of climate change. This thesis contributes with new paleoenvironmental information from a small crater lake in northern Tanzania and provides an additional link between the integrated history of climate, environment and socioeconomic variability in tropical Africa. LÄS MER

  2. 2. Benthic diatoms in the Gulf of Bothnia Community analysis and diversity

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Svenja Busse; Uppsala universitet.; [2002]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; Baltic Sea; Biodiversity; Biomass; Community ecology; Diatoms; Multivariate analysis; Navicula; Phytobenthos; Salinity gradient; Scale; Size; Water movement; Ekologi; NATURAL SCIENCES Biology Terrestrial; freshwater and marine ecology; NATURVETENSKAP Biologi Terrestisk; limnisk och marin ekologi; Ecological Botany; Ekologisk botanik;

    Sammanfattning : Benthic diatoms are valuable tools for biological monitoring and paleo-ecological reconstruction of past environmental conditions. This thesis aims at describing size-related properties of benthic diatoms and suggests that data assessment for community analysis can be improved by considering the importance of scale. LÄS MER

  3. 3. Diatoms as indicators of Holocene climate and environmental change in northern Sweden

    Detta är en avhandling från Umeå : Ekologi och geovetenskap

    Författare :Christian Bigler; Umeå universitet.; [2001]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physical geography and sedimentology; diatoms; Holocene; paleolimnology; climate change; lake sediments; transfer functions; quantitative environmental reconstructions; northern Sweden; Abisko; Naturgeografi och sedimentologi; NATURAL SCIENCES Earth sciences Exogenous earth sciences Physical geography; NATURVETENSKAP Geovetenskap Exogen geovetenskap Naturgeografi; naturgeografi; Physical Geography;

    Sammanfattning : The objective of the thesis was to explore the potential of diatoms (Bacillariophyceae) as indicators of Holocene climate and environmental change in northern Sweden (Abisko region, 68°21'N, 18°49'E). A modern surface-sediment calibration set including 100 lakes was developed and lake-water pH, sedimentary organic content (assessed by loss-on-ignition) and temperature were identified as most powerful environmental variables explaining the variance within the diatom assemblages. LÄS MER

  4. 4. Benthic diatoms in lakes

    Detta är en avhandling från Umeå : Ekologi och geovetenskap

    Författare :Steffi Gottschalk; Sveriges lantbruksuniversitet.; [2014]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : In order to protect or improve surface waters ecosystem response to pressures needs to be quantified. Diatoms are frequently used for assessing ecological status in streams and for reconstructing water quality of lakes. However, ecological status assessment of European lakes based on extant diatom assemblages is rare. LÄS MER

  5. 5. Experimental Studies on the Regulation of Pigment Dynamics in Phytoplankton and Copepods by Dissolved Inorganic Nutrients

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Lies Van Nieuwerburgh; Uppsala universitet.; [2004]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biology; Astaxanthin; Baltic Sea; carotenoids; diatoms; eutrophication; food web; mesocosms; microalgae; M74 syndrome; oxidative stress; phytoplankton blooms; zooplankton; Biologi; NATURAL SCIENCES Biology; NATURVETENSKAP Biologi;

    Sammanfattning : This thesis examines the role of dissolved inorganic nutrients in generating changes in phytoplankton community and pigment composition and if such changes can affect the production of the antioxidant astaxanthin in the ecosystem via pelagic copepods. The background of my studies is the possible relationship between eutrophication and a reproductive disturbance in Baltic populations of Atlantic salmon (M74), which is associated with astaxanthin and thiamine deficiencies and oxidative stress. LÄS MER