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Dinoflagellate Alexandrium ostenfeldii obtain nutrients from co-occurring phytoplankton Rhinomonas nottbecki (cryptophyte) through allelopathy
Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
2017 (English)Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
Abstract [en]

Blooms of the toxic dinoflagellate Alexandrium ostenfeldii have become more frequent in shallow coastal regions of the Baltic Sea and are associated with high concentrations of dissolved organic nitrogen (DON). Importance of DON is known for several dinoflagellates but unknown for A. ostenfeldii nutrition. Effects of A. ostenfeldii allelopathy (production of substances harmful to surrounding biota) have been shown to a variable extent, against several target organisms. Here, allelopathy as a mechanism to obtain nutrients, e.g. DON and ammonium (NH4+), from co-occurring phytoplankton was studied by considering 1) lytic activity of A. ostenfeldii strain AOF 0919 (in cultivation since 2009) against cryptophyte Rhinomonas nottbecki strain Crypto 07B3, 2) A. ostenfeldii uptake of cryptophyte derived nutrients (N), and 3) bacterial influence on the uptake. An EC50 assay was applied to assess allelopathic activity and revealed maintenance of a high lytic activity of A. ostenfeldii strain AOF 0919. The concentration of A. ostenfeldii causing 50 % decline in target cell concentration, i.e. EC50, was 260 cells ml-1. Uptake of cryptophyte derived N-substrates by A. ostenfeldii was confirmed in an uptake assay using 15N tracers (heavier N-isotope) and the prokaryotic inhibitor chloramphenicol (CAP). Uptake rates in CAP absence (577.3 ± 211.2 fmol N cell-1 h-1) were similar to the uptake rates in presence of CAP (384.4 ± 94.7 fmol N cell-1 h-1). Bacteria might affect conversion of DON but were not crucial for A. ostenfeldii uptake of cryptophyte derived N. The present study highlights a process (i.e. allelopathy as a mechanism to obtain nutrients) that is likely to occur under natural conditions since ecologically relevant cell concentrations were used.

Place, publisher, year, edition, pages
2017. , 20 p.
Keyword [en]
Allelopathy, Alexandrium ostenfeldii, DON, HAB, 15N
National Category
Biological Sciences
Identifiers
URN: urn:nbn:se:lnu:diva-65467OAI: oai:DiVA.org:lnu-65467DiVA: diva2:1111612
Subject / course
Biology
Educational program
Biology Programme, 180 credits
Supervisors
Examiners
Available from: 2017-06-20 Created: 2017-06-19 Last updated: 2017-06-20Bibliographically approved

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CiteExportLink to record
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Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
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  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
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  • asciidoc
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