<p>Cyanobacteria which can form resting cells (in this case akinetes) are common in meso-eutrophic lakes in temperate regions, often dominating the phytoplankton communities during summer. The life cycles of akinete-forming cyanobacteria has been studied with <i>Gloeotrichia echinulata</i> as a model organism. <i>Anabaena</i> and <i>Aphanizomenon</i> were also included in a migration study. The focus of this thesis has been the factors influencing the processes of germination and subsequent growth, the factors influencing migration from the sediment, and the amount of growth occurring in the water. </p><p>Germination of <i>G. echinulata</i> was strongly favoured by light, and recruitment was highest from organic-rich sediments in shallow, sheltered littoral areas, between 0-3 m. Recruitment of <i>Anabaena</i> and <i>Aphanizomenon</i> was less light dependent, yet the highest recruitment occurred from shallow sediments (0-2 m). This means that organic-rich sediments (0-3 m) in shallow areas are the most important seed-banks of akinete-forming cyanobacteria. The inocula contributed only to a minor extent to the maximum pelagic populations. 4% for <i>G. echinulata</i> in the mesotrophic Lake Erken, and 0.03% for both <i>Anabaena</i> and <i>Aphanizomenon</i> in the eutrophic Lake Limmaren. This implies that processes of growth and division in the water are important for the maximum size of the pelagic population. Prolonged recruitment from the sediment strongly promoted establishment of the species in the water, especially <i>G. echinulata</i>. </p>
| Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:uu-3432 |
| Date | January 2003 |
| Creators | Karlsson Elfgren, Irene |
| Publisher | Uppsala University, Limnology, Uppsala : Acta Universitatis Upsaliensis |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, comprehensive summary, text |
| Relation | Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1104-232X ; 856 |
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