umu.sePublications
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Flagellates in the marine microbial food web: the ecology of a mixotrophic nanoflagellate, Ochromonas sp.
1989 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Nanoflagellates were found to be abundant in a coastal area of the northern Bothnian Sea. The maximum concentration of nanoflagellates, approximately 8000 cells ml-1, was observed in July, coinciding with a decrease in the abundance of cyanobacteria. Pigmented and non-pigmented nanoflagellates were approximately equally distributed throughout the year. Most of the identified genera are known as being phagotrophic, independent if autotrophic or not.

A non-cyst-forming pigmented flagellate, Ochromonas sp., was isolated and nutritionally characterized. This chrysophycean flagellate was shown to be a mainly heterotrophic organism: Photosynthesis was too poor to support multiplication of the cells, whereas when feeding on bacteria, high growth rates were obtained. The biological function of the photosynthetic apparatus is suggested to be a survival mechanism during poor bacterial conditions.

The flagellate grazed bacteria selectively, preferring cyanobacteria and large cells of heterotrophic bacteria, presumably depending on size-selective grazing. Despite higher growth rates of the bacteria in the sea during summer (July) than spring (May), heterotrophic bacteria in the sea was observed to be smaller in the summer. Nanoflagellates showed a maximum in July, and by selective grazing of large bacteria they might have caused the decrease in the average size of the bacteria and the decrease in the abundance of cyanobacteria.

During the consumption of bacteria the flagellate was shown to remineralize nutrients at high rates and excrete dissolved free amino acids. Assuming the existence of a protozoan predator-prey chain of several trophic levels, it seems likely that a significant part of the nutrients fixed by primary producers is remineralized in the euphotic zone. Furthermore, data from this work indicate that flagellate activity may be a significant source of dissolved free amino acids, utilizable for the heterotrophic bacteria.

Place, publisher, year, edition, pages
Umeå: Umeå universitet , 1989. , 43 p.
Keyword [en]
Microbial food web, flagellates, Ochromonas sp., mixotrophy, size- selective grazing, remineralisation, excretion of DFAA
National Category
Microbiology
Identifiers
URN: urn:nbn:se:umu:diva-141600ISBN: 91-7174-417-7 OAI: oai:DiVA.org:umu-141600DiVA: diva2:1155711
Projects
digitalisering@umu
Available from: 2017-11-09 Created: 2017-11-09 Last updated: 2017-11-09Bibliographically approved

Open Access in DiVA

fulltext(2517 kB)14 downloads
File information
File name FULLTEXT01.pdfFile size 2517 kBChecksum SHA-512
8198f04eb97e831c6e19cab6634991b719844bb4c05eb8ad0980a73a349b2fb2b4d729fcd6ef8b6aa10b3c9c9edafbae71b8b670023755aeca453270da165b14
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Andersson-Nordström, Agneta
Microbiology

Search outside of DiVA

GoogleGoogle Scholar
Total: 14 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 25 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf