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Studies on the Life Cycles of Akinete Forming Cyanobacteria
Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology, Limnology.
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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 Gloeotrichia echinulata as a model organism. Anabaena and Aphanizomenon 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.

Germination of G. echinulata was strongly favoured by light, and recruitment was highest from organic-rich sediments in shallow, sheltered littoral areas, between 0-3 m. Recruitment of Anabaena and Aphanizomenon 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 G. echinulata in the mesotrophic Lake Erken, and 0.03% for both Anabaena and Aphanizomenon 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 G. echinulata.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis , 2003. , p. 39
Series
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 856
Keywords [en]
Biology, limnology, akinete, germination, recruitment
Keywords [sv]
Biologi
National Category
Biological Sciences
Research subject
Limnology
Identifiers
URN: urn:nbn:se:uu:diva-3432ISBN: 91-554-5665-0 (print)OAI: oai:DiVA.org:uu-3432DiVA, id: diva2:162781
Public defence
2003-06-04, Limnologens föreläsningssal, Norbyvägen 20, Uppsala, 10:00
Opponent
Supervisors
Available from: 2003-05-14 Created: 2003-05-14Bibliographically approved
List of papers
1. On the germination of the akinete-forming cyanobacterium Gloeotrichia echinulata, in Lake Erken, Sweden
Open this publication in new window or tab >>On the germination of the akinete-forming cyanobacterium Gloeotrichia echinulata, in Lake Erken, Sweden
1999 In: Algological Studies, Vol. 94, p. 175-180Article in journal (Refereed) Published
Identifiers
urn:nbn:se:uu:diva-90423 (URN)
Available from: 2003-05-14 Created: 2003-05-14Bibliographically approved
2. Benthic growth of Gloeotrichia echinulata
Open this publication in new window or tab >>Benthic growth of Gloeotrichia echinulata
2003 (English)In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 506, no 1, p. 189-193Article in journal (Refereed) Published
Abstract [en]

Gloeotrichia echinulata is an akinete forming cyanobacterium with both a pelagic and a benthic phase. After germination of the akinete there is a short phase of growth on the sediment before the filaments develop gas vacuoles and migrate up into the water. It has been indicated that during the time of growth on the sediment surface the germlings take up nutrients. Those nutrients would be used during the pelagic phase as the pelagic colonies do not have a very efficient nutrient uptake. To test the length of the initial growth period `akinete colonies' were picked out of sediment samples from Lake Erken, Sweden, and placed on a thin layer of sediment in wellplates (Nunclon multidish, 48 wells) in an incubator with 17 °C and a light:dark cycle of 16:8 h. The plates were then studied under a stereomicroscope and pictures were taken one or two times per day for 20 days. Germination occurred in one third of the wells and the growth was recorded. The germlings formed bundles on the surface of the old akinete colony during the experiment. Several bundles were found on the same akinete colony. In the migration traps colonies and filament bundles were found. The morphology of filament bundles found in the migration traps was similar to the filament bundles found in the germination experiment which had reached a stage of development where they would soon be considered colonies.

National Category
Ecology
Identifiers
urn:nbn:se:uu:diva-90424 (URN)10.1023/B:HYDR.0000008570.03256.00 (DOI)
Available from: 2003-05-14 Created: 2003-05-14 Last updated: 2017-12-14Bibliographically approved
3. Factors regulating recruitment from the sediment to the water column in the bloom-forming cyanobacterium Gloeotrichia echinulata
Open this publication in new window or tab >>Factors regulating recruitment from the sediment to the water column in the bloom-forming cyanobacterium Gloeotrichia echinulata
2004 (English)In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 49, no 3, p. 265-273Article in journal (Refereed) Published
Abstract [en]

Summary

1. The influence of light, temperature, sediment mixing and sediment origin (water depth) on the recruitment of the cyanobacterium Gloeotrichia echinulata was examined in the laboratory.

2. Light and temperature were the most important factors initiating germination in G. echinulata.

3. The extent of germination (recruited biovolume) was mainly regulated by temperature and sediment mixing. Furthermore, sediment mixing significantly enhanced the frequency of observed heterocysts and colonies.

4. Despite the fact that the deep and shallow sediments contained a similar number of akinete colonies, the highest recruitment occurred from shallow sediments, indicating that akinetes from shallow sediments have a higher viability than those from deeper parts of the lake.

5. Our results support the hypothesis that shallow sediments are more important than profundal sediments for the recruitment of G. echinulata to the pelagic zone.

National Category
Ecology
Identifiers
urn:nbn:se:uu:diva-90425 (URN)10.1111/j.1365-2427.2004.01182.x (DOI)
Available from: 2003-05-14 Created: 2003-05-14 Last updated: 2017-12-14Bibliographically approved
4. Recruitment and pelagic growth of Gloeotrichia echinulata (Chyanophyceae) in Lake Erken
Open this publication in new window or tab >>Recruitment and pelagic growth of Gloeotrichia echinulata (Chyanophyceae) in Lake Erken
2003 (English)In: Journal of Phycology, ISSN 0022-3646, E-ISSN 1529-8817, Vol. 39, no 6, p. 1050-1056Article in journal (Refereed) Published
Abstract [en]

Different parameters in the life cycle of the colony forming cyanobacterium Gloeotrichia echinulata (J.E. Smith) Richter was evaluated in Lake Erken, Sweden. Recruitment of colonies from the sediments and pelagic abundance were measured during 2 years. These data were then used in a model to evaluate and estimate parameters of the life cycle. In our study, recruitment alone only contributed to a small part (<5%) of the maximum G. echinulata abundance that occurred during late summer. However, recruitment from shallow sediments forms the important seed for the pelagic population. Together with measured rates of migration from the sediment, variations in either pelagic colony division rate or pelagic residence time could explain variations in the measured abundance of G. echinulata in situ.

National Category
Ecology
Identifiers
urn:nbn:se:uu:diva-90426 (URN)10.1111/j.0022-3646.2003.03-030.x (DOI)
Available from: 2003-05-14 Created: 2003-05-14 Last updated: 2017-12-14Bibliographically approved
5. Pelagic growth and colony division of Gloeotrichia echinulata in Lake Erken
Open this publication in new window or tab >>Pelagic growth and colony division of Gloeotrichia echinulata in Lake Erken
2005 (English)In: Journal of Plankton Research, ISSN 0142-7873, E-ISSN 1464-3774, Vol. 27, no 2, p. 145-151Article in journal (Refereed) Published
Abstract [en]

Gloeotrichia echinulata colony development was monitored in Lake Erken, Sweden and studied inenclosure experiments. Significant colonial division did not occur in mesh bags, although the abundance ofthe pelagic population in the lake increased during the experimental periods. On the basis of these findings,it is suggested that circulation of G. echinulata to deeper nutrient rich water supports pelagic growth. Insupport of this, a large part of the buoyant G. echinulata colonies in Lake Erken was found at severalmeters depth. In an experiment with nutrient additions, the only treatment that favoured G. echinulatadevelopment was additions of phosphate, nitrate and iron. Trace element additions had a negative effecton the development of G. echinulata. On the basis of these findings, the nutritional requirements ofG. echinulata are discussed.

National Category
Ecology
Identifiers
urn:nbn:se:uu:diva-90427 (URN)10.1093/plankt/fbh165 (DOI)
Available from: 2003-05-14 Created: 2003-05-14 Last updated: 2017-12-14Bibliographically approved
6. The Importance of Shallow Sediments in the Recruitment of Anabaena and Aphanizomenon (Cyanophyceae)
Open this publication in new window or tab >>The Importance of Shallow Sediments in the Recruitment of Anabaena and Aphanizomenon (Cyanophyceae)
2004 (English)In: Journal of Phycology, ISSN 0022-3646, E-ISSN 1529-8817, Vol. 40, no 5, p. 831-836Article in journal (Refereed) Published
Abstract [en]

Recruitment of Anabaena and Aphanizomenon from the sediments to the water column was investigated in shallow (1-2 m) and deep (6-7 m) areas of Lake Limmaren, central Sweden. Recruitment traps attached to the bottom were sampled weekly throughout the summer season (June through September). A comparison between the two sites shows that the largest part of the recruited cells originated from the shallow site, although recruitment occurred at all depths in the lake. There were also differences between the species, regarding the site as well as the timing of the recruitment. The contribution of the inoculum to the pelagic population was calculated to vary between 0.003% and 0.05% for the different species. From these results we conclude that shallow sediments are more important than deep ones for the recruitment and that the inoculum in Lake Limmaren is small but may still be an important factor in the population dynamics.

National Category
Ecology
Identifiers
urn:nbn:se:uu:diva-90428 (URN)10.1111/j.1529-8817.2004.04070.x (DOI)
Available from: 2003-05-14 Created: 2003-05-14 Last updated: 2018-06-05Bibliographically approved

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