Sökning: "diatom abundance"

Visar resultat 1 - 5 av 18 avhandlingar innehållade orden diatom abundance.

1. 1. Diatom and Sedimentological Investigations on West Antarctic Shelf Sediment

   Författare :Charlotte Sjunneskog; Bjorg Stabell; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Earth sciences; Antarctica; climate change; diatom abundance; geochemistry; Geovetenskap; Earth sciences; Geovetenskap; Quarternary Geology; kvartärgeologi;

   Sammanfattning : Climate and environmental change following the retreat of the last glacial ice sheet in the Antarctic Peninsula has been interpreted, employing diatom abundance, relative abundance of Chaetoceros resting spores and diatom assemblages as proxies. These together with sedimentological data and radiocarbon dating, suggest four major events that can be further subdivided. LÄS MER

3. 2. Molecular detection of abundance and activity of marine, symbiotic, N2-fixing cyanobacteria

   Författare :Linnéa Ström; Rachel Foster; Daniel Lundin; Katharina Pawlowski; Rehab El-Shehawy; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Diatom Diazotroph Association; Richelia; Iron; Phosphorus; Nitrogen; nifH; pstS; exbB; rnpA; växtfysiologi; Plant Physiology; marinbiologi; Marine Biology;

   Sammanfattning : Marine primary productivity in large parts of the oceans is supported by nitrogen fixers (diazotrophs). Richelia, a genus of multiple closely related species of heterocystous filamentous cyanobacterial diazotrophs, are often found in symbioses with a few genera of diatoms. Several Richelia species: R. euintracellularis, R. LÄS MER

4. 3. Tracing environmental change and human impact as recorded in sediments from coastal areas of the northwestern Baltic Proper

   Författare :Lena Norbäck Ivarsson; Elinor Andrén; Thomas Andrén; Mikael Lönn; John Anderson; Södertörns högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Baltic Sea; paleoecology; diatom stratigraphy; stable nitrogen isotopes; hypoxia; nutrient discharge; eutrophication; Medieval Climate Anomaly; Little Ice Age; Environmental Studies; Miljövetenskapliga studier; Östersjö- och Östeuropaforskning; Baltic and East European studies;

   Sammanfattning : The eutrophication of the Baltic Sea due to increased anthropogenic nutrient loads during the 20th century is well documented and studied. However, in the Baltic Sea drainage area, humans have affected the environment longer than the environmental monitoring can provide data for. LÄS MER

5. 4. Genomic and morphological diversity of marine planktonic diatom-diazotroph associations : a continuum of integration and diversification through geological time

   Författare :Andrea Caputo; Rachel Ann Foster; Monika Quinones Winder; Ramon Massana; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; phytoplankton; diatoms; cyanobacteria; diazotrophs; symbiosis; evolution; phylogenetics; confocal microscopy; qPCR; CARD-FISH; tropics; sub-tropics; Marine Ecology; marin ekologi;

   Sammanfattning : Symbioses between eukaryotes and nitrogen (N2)-fixing cyanobacteria (or diazotrophs) are quite common in the plankton community. A few genera of diatoms (Bacillariophyceae) such as Rhizosolenia, Hemiaulus and Chaetoceros are well known to form symbioses with the heterocystous diazotrophic cyanobacteria Richelia intracellularis and Calothrix rhizosoleniae. LÄS MER

7. 5. Holocene environmental changes recorded by diatom stratigraphy in the southern Baltic Sea

   Författare :Elinor Andrén; Rick W. Batterbee; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; allmän och historisk geologi; General and Historical Geology;

   Sammanfattning : Sediment cores from the southern Baltic Sea and the Oder River estuary are analysed for their siliceous microfossil assemblages and organic carbon content. Long piston cores from the Bornholm and Gotland Basins provide data on the long-term Holocene history of the Baltic proper and serve as a natural background when evaluating the most recent environmental changes recorded in the short gravity cores. LÄS MER