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Sedimentation of Nodularia spumigena and distribution of nodularin in the food web during transport of a cyanobacterial bloom from the Baltic Sea to the Kattegat

Author:
  • Per Carlsson
  • Diego Rita
Publishing year: 2019
Language: English
Pages: 74-83
Publication/Series: Harmful Algae
Volume: 86
Document type: Journal article
Publisher: Elsevier

Abstract english

Nodularia spumigena is a toxic cyanobacteria that blooms in the Baltic Sea every year. In the brackish water of the Baltic Sea, its toxin, nodularin, mainly affects the biota in the surface water due to the natural buoyancy of this species. However, the fate of the toxin is unknown, once the cyanobacteria bloom enters the more saline waters of the Kattegat. In order to investigate this knowledge gap, a bloom of N. spumigena was followed during its passage, carried by surface currents, from the Baltic Sea into the Kattegat area, through the Öresund strait. N. spumigena cells showed an increased cell concentration through the water column during the passage of the bloom (up to 130 103 cells ml−1), and cells (4.2 103 cells ml−1)could be found down to 20 m depth, below a pycnocline. Sedimentation trap samples from below the pycnocline (10–12 m depth)also showed an increased sedimentation of N. spumigena filaments during the passage of the bloom. The toxin nodularin was detected both in water samples (0.3–6.0 μg l−1), samples of sedimenting material (a toxin accumulation rate of 20 μg m-2 day−1), zooplankton (up to 0.1 ng ind.−1 in copepods), blue mussels (70–230 μg kg−1 DW), pelagic and benthic fish (herring (1.0–3.4 μg kg−1 DW in herring muscle or liver)and flounder (1.3-6.2 μg kg−1 DW in muscle, and 11.7-26.3 μg kg−1 DW in liver). A laboratory experiment showed that N. spumigena filaments developed a decreased buoyancy at increased salinities and that they were even sinking with a rate of up to 1,7 m day−1 at the highest salinity (32 PSU). This has implications for the fate of brackish water cyanobacterial blooms, when these reach more saline waters. It can be speculated that a significant part of the blooms content of nodularin will reach benthic organisms in this situation, compared to blooms decaying in brackish water, where most of the bloom is considered to be decomposed in the surface waters.

Keywords

  • Microbiology
  • Baltic Sea
  • Buoyancy
  • Cyanobacteria
  • Food web
  • Kattegat
  • Nodularia spumigena
  • Nodularin
  • Öresund

Other

Published
  • ISSN: 1568-9883
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

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Research group

Aquatic Ecology

Projects

Marine Pelagic Projects

Doctoral students and postdocs

PhD student, main supervisor

Johanna Stedt

Ceratium