Species‐specific physiological response of dinoflagellates to quantified small‐scale turbulence¹

Abstract

Turbulence has been shown to alter different aspects of the physiology of some dinoflagellates. The response appears to be species-specific and dependent on the experimental design and setup used to generate small-scale turbulence. We examined the variability of the response of three dinoflagellate species to the turbulence, following the same experimental design used by Berdalet (1992) on Akashiwo sanguinea (Hirasaka) Ge. Hansen et Moestrup (=Gymnodinium nelsonii G. W. Martin). In all experiments, turbulence was generated by an orbital shaker at 100 rpm, which corresponded on bulk average, to dissipation rates (e, quantified using an acoustic Doppler velocimeter) of %2 cm 2 AE s )3 . Turbulence did not appreciably affect Gymnodinium sp., a small dinoflagellate. However, Alexandrium minutum Halim and Prorocentrum triestinum J. Schiller exhibited a reduced net growth rate (33% and 28%, respectively) when shaken during the exponential growth phase. Compared to the still cultures, the shaken treatments of A. minutum and P. triestinum increased the mean cell volume (up to 1.4-and 2.5-fold, respectively) and the mean DNA content (up to 1.8-and 5.3-fold, respectively). Cultures affected by turbulence recovered their normal cell properties when returned to still conditions. The swimming speed of the cells exposed to agitation was half that of the unshaken ones. Overall, the response of A. minutum and P. triestinum was similar, but with lower intensity, to that observed previously on A. sanguinea. We found no clear trends related to taxonomy or morphology.

Small-scale turbulence can reduce parasite infectivity to dinoflagellates

“…A scheme of the setup used to perform × estimations can be found in Fig. 1 of Berdalet et al (2007). A complete description of the calculations was provided by Guadayol et al (2009).…”

“…To address this question, we collected field samples during 3 distinct and temporally separated phases of a phytoplankton spring bloom, characterised by the presence of Prorocentrum micans, Scrippsiella trochoidea and the toxic Alexandrium minutum, as well as the parasite Parvilucifera sinerae, which has the capacity to infect the latter 2 dinoflagellate species. We then subjected the samples to laboratory-generated turbulence (using the same experimental setup as in previous studies on turbulence-dinoflagellate interactions; Berdalet et al 2007, Bolli et al 2007, Llaveria et al 2009) or kept them unperturbed. We compared the 2 treatments in terms of dinoflagellate cell abundances and data on the infectivity by P. sinerae.…”

Modulation of ecdysal cyst and toxin dynamics of two <i>Alexandrium</i> (Dinophyceae) species under small-scale turbulence

“…Dinoflagellates appear as the group showing a diversity of particular responses to this, not well understood yet, environmental factor. The available data indicate that the direct effect of turbulence is species-specific and dependent on the experimental conditions (Berdalet and Estrada, 1993;Berdalet et al, 2007), although direct comparison between studies is not straightforward (Peters and Marrasé, 2000). Some studies have found positive (or indifferent) biological responses (Berdalet and Estrada, 1993;Havskum et al, 2005;Havskum and Hansen, 2006).…”

Trait changes induced by species interactions in two phenotypically distinct strains of a marine dinoflagellate

“…Cages were slowly moved up and down three times a day to promote the exchange of medium and dissolved compounds (including allelochemicals) between the two compartments. Experiments were terminated after 24, 48, 72 and 96 h; the first 24 h was considered to be an acclimation phase because dinoflagellates are sensitive to mixing (Berdalet et al, 2007) and often show a prolonged lag-phase after cell culture transfer.…”