Menu

Javascript is not activated in your browser. This website needs javascript activated to work properly.
You are here

Dinophysis blooms in the deep euphotic zone of the Baltic Sea: do they grow in the dark?

Author:
  • L Å Gisselson
  • Per Carlsson
  • E Graneli
  • Jan Pallon
Publishing year: 2002
Language: English
Pages: 401-418
Publication/Series: Harmful Algae
Volume: 1
Issue: 4
Document type: Journal article
Publisher: Elsevier
Additional info: The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Aquatic Ecology (432112234), Nuclear Physics (Faculty of Technology) (011013007)

Abstract english

In situ growth rates of the toxin-producing dinoflagellate Dinophysis norvegica collected in the central Baltic Sea were estimated during the summers of 1998 and 1999. Flow cytometric measurements of the DNA cell cycle of D. norvegica yielded specific growth rates (μ) ranging between 0.1 and 0.4 per day, with the highest growth rates in stratified populations situated at 15–20 m depth. Carbon uptake rates, measured using 14C incubations followed by single-cell isolation, at irradiances corresponding to depths of maximum cell abundance were sufficient to sustain growth rates of 0.1–0.2 per day. The reason for D. norvegica accumulation in the thermocline, commonly at 15–20 m depth, is thus enigmatic. Comparison of depth distributions of cells with nutrient profiles suggests that one reason could be to sequester nutrients. Measurements of single-cell nutrient status of D. norvegica, using nuclear microanalysis, revealed severe deficiency of both nitrogen and phosphorus as compared to the Redfield ratio.



It is also possible that suitable prey or substrate for mixotrophic feeding is accumulating in the thermocline. The fraction of cells containing digestive vacuoles ranged from 2 to 22% in the studied populations. Infection by the parasitic dinoflagellate Amoebophrya sp. was observed in D. norvegica in all samples analysed. The frequency of infected cells ranged from 1 to 3% of the population as diel averages, ranging from 0.2 to 6% between individual samples. No temporal trends in infection frequency were detected. Estimated loss rates based on observed infection frequencies were 0.5–2% of the D. norvegica population daily, suggesting that these parasites were not a major loss factor for D. norvegica during the periods of study.

Keywords

  • Ecology
  • Subatomic Physics

Other

Published
  • Nuclear Microprobe-lup-obsolete
  • ISSN: 1878-1470
Per Carlsson
E-mail: per [dot] carlsson [at] biol [dot] lu [dot] se

Senior lecturer

Division aquatic ecology

+46 46 222 84 35

E-C112

50

Senior lecturer

Aquatic Ecology

50

Research group

Aquatic Ecology

Projects

Marine Pelagic Projects

Doctoral students and postdocs

PhD student, main supervisor

Johanna Stedt

Ceratium