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| Titel |
Modulation of ecdysal cyst and toxin dynamics of two Alexandrium (Dinophyceae) species under small-scale turbulence |
| VerfasserIn |
L. Bolli, G. Llaveria, E. Garcés, Ò. Guadayol, K. Lenning, F. Peters, E. Berdalet |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 4, no. 4 ; Nr. 4, no. 4 (2007-08-01), S.559-567 |
| Datensatznummer |
250001853
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| Publikation (Nr.) |
 copernicus.org/bg-4-559-2007.pdf |
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| Zusammenfassung |
Some dinoflagellate species have shown different physiological responses to
certain turbulent conditions. Here we investigate how two levels of
turbulent kinetic energy dissipation rates (ε = 0.4 and 27 cm² s−3) affect the PSP toxins and ecdysal cyst dynamics of two
bloom forming species, Alexandrium minutum and A. catenella. The most striking responses were observed at
the high ε generated by an orbital shaker. In the cultures of
the two species shaken for more than 4 days, the cellular GTX(1+4) toxin
contents were significantly lower than in the still control cultures. In A. minutum
this trend was also observed in the C(1+2) toxin content. For the two
species, inhibition of ecdysal cyst production occurred during the period of
exposure of the cultures to stirring (4 or more days) at any time during
their growth curve. Recovery of cyst abundances was always observed when
turbulence stopped. When shaking persisted for more than 4 days, the net
growth rate significantly decreased in A. minutum (from 0.25±0.01 day−1 to
0.19±0.02 day−1) and the final cell numbers were lower (ca. 55.4%) than in the still control cultures. In A. catenella, the net growth rate was
not markedly modified by turbulence although under long exposure to shaking,
the cultures entered earlier in the stationary phase and the final cell
numbers were significantly lower (ca. 23%) than in the control flasks.
The described responses were not observed in the experiments performed at
the low turbulence intensities with an orbital grid system, where the
population development was favoured. In those conditions, cells appeared to
escape from the zone of the influence of the grids and concentrated in
calmer thin layers either at the top or at the bottom of the containers.
This ecophysiological study provides new evidences about the sensitivity to
high levels of small-scale turbulence by two life cycle related processes,
toxin production and encystment, in dinoflagellates. This can contribute to
the understanding of the dynamics of those organisms in nature. |
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