Assessment of the allelochemical activity of Ostreopsis cf. ovata and the ovatoxins towards competitive benthic microalgae

Type Article
Date 2022-06
Language English
Author(s) Ternon EvaORCID1, 2, 3, Pavaux Anne-Sophie2, Peltekis Alexandra4, Gemin Marin-Pierre5, Jauzein Cecile6, Bailleul Benjamin4, Lemée Rodolphe2, Thomas Olivier P.1, 7
Affiliation(s) 1 : OCA, IRD, Géoazur, CNRS, Université Côte d’Azur, 250 Rue Albert Einstein, 06560, Valbonne, France
2 : Laboratoire d’Océanographie de Villefranche, CNRS UMR7093, Sorbonne Universités, 06234, Villefranche sur Mer, France
3 : Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, 92093, USA
4 : Laboratoire de Biologie du Chloroplaste et Perception de la Lumière chez les Micro-algues, CNRS UMR7141, IBPC, Sorbonne Université, Paris, France
5 : Phycotoxins Laboratory, IFREMER, 44311, Nantes, France
6 : Centre de Brest, DYNECO PELAGOS, IFREMER, 29280, Plouzané, France
7 : Marine Biodiscovery, School of Chemistry and Ryan Institute, National University of Ireland Galway (NUI Galway), University Road, Galway, H91 TK33, Ireland
Source Aquatic Ecology (1386-2588) (Springer Science and Business Media LLC), 2022-06 , Vol. 56 , N. 2 , P. 475-491
DOI 10.1007/s10452-022-09953-x
WOS© Times Cited 4
Keyword(s) Ostreopsis cf, ovata, Allelochemistry, Competition, Ovatoxins, Metabolomics
Abstract

Recurrent blooms of the toxic dinoflagellate Ostreopsis cf. ovata are frequently reported in the Northwestern Mediterranean Sea. The impact of these proliferations on other microalgal species inhabiting the same habitats is of interest from an ecological prospective. In vitro experiments were carried out to investigate the influence of O. cf. ovata on the growth of the co-occurring benthic diatoms Licmophora paradoxa, Navicula arenaria and the benthic dinoflagellates Prorocentrum lima and Coolia monotis. Overall, O. cf. ovata exhibited weak allelopathic effects towards these microalgal species, with a reduction in the cell abundance for L. paradoxa and P. lima only. Interestingly, dead cells of L. paradoxa and N. arenaria were observed embedded in the thick mucus surrounding O. cf. ovata cells, suggesting that the mucous layer could act as a toxic phycosphere, especially for non-motile cells. All competitors were further exposed for 24 h to ovatoxins, the major toxins produced by O. cf. ovata, and the maximum quantum yield efficiency of L. paradoxa, N. arenaria and P. lima was affected at a minimum concentration of 10 µg mL−1. We then hypothesized that the diffusion of solubilized ovatoxins in the culture medium affects only moderately the competitors’ growth, whereas their accumulation in the mucus would yield deleterious effects. More precisely, the competitors’ sensitivity to ovatoxins was enhanced in their stationary phase of growth and resulted from a rapid inhibition of an uncharacterized photosynthetic step downstream photosystem II. Altogether, these results emphasize the predominant role of the O. cf. ovata’s mucus in driving ecological interactions and suggest that it can affect the growth of several benthic microalgae by accumulating the potent ovatoxins.

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Ternon Eva, Pavaux Anne-Sophie, Peltekis Alexandra, Gemin Marin-Pierre, Jauzein Cecile, Bailleul Benjamin, Lemée Rodolphe, Thomas Olivier P. (2022). Assessment of the allelochemical activity of Ostreopsis cf. ovata and the ovatoxins towards competitive benthic microalgae. Aquatic Ecology, 56(2), 475-491. Publisher's official version : https://doi.org/10.1007/s10452-022-09953-x , Open Access version : https://archimer.ifremer.fr/doc/00752/86395/