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Net growth of the bloom-forming dinoflagellate Heterocapsa triquetra and pH: why turbulence matters

2006; Inter-Research Science Center; Volume: 42; Linguagem: Inglês

10.3354/ame042055

1616-1564

Harry Havskum, Per Juel Hansen,

Marine Toxins and Detection Methods

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 42:55-62 (2006) - doi:10.3354/ame042055 Net growth of the bloom-forming dinoflagellate Heterocapsa triquetra and pH: why turbulence matters Harry Havskum*, Per J. Hansen Marine Biological Laboratory, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark *Email: hhavskum@bi.ku.dk ABSTRACT: The effect of turbulence on pH and the proliferation of the phototrophic dinoflagellate Heterocapsa triquetra was monitored for 10 d. Four turbulent energy dissipation rates ranging from 0.0001 to 1 cm2 s–3 were employed. The net growth rate of H. triquetra was on average 0.42 d–1 at all turbulence levels, as long as cell densities were low and pH stayed below 8.9. When cell densities increased and the pH exceeded 9.0, the net growth rate of H. triquetra decreased in all cases. However, at high cell densities, the pH and net growth rate of H. triquetra depended on the turbulence level. At the highest turbulence level, the net growth rate of H. triquetra was higher and the pH lower than at the lowest turbulence level, because turbulence increased the exchange of CO2 between the medium and the atmospheric air. At the second highest turbulence level, the net growth rate of H. triquetra was also higher than the net growth rate at lower turbulence; this was likely to be due to a higher influx of inorganic carbon, even though pH measurements from the middle of the light period did not differ significantly among turbulence levels. However, during the night, pH decreased more at the second highest turbulence level than at the 2 lowest turbulence levels and thereby allowed a higher net growth rate of H. triquetra. Our results suggested that when forming blooms in eutrophic waters under conditions of high pH, H. triquetra will benefit from turbulent energy dissipation rates between 0.05 and 1 cm2 s–3. KEY WORDS: Turbulence · pH · Growth · Phytoplankton blooms · Dinoflagellates · Heterocapsa triquetra Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 42, No. 1. Online publication date: February 06, 2006 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2006 Inter-Research.