Unsuspected intraspecific variability in the toxin production, growth and morphology of the dinoflagellate Alexandrium pacificum R.W. Litaker (Group IV) blooming in a South Western Mediterranean marine ecosystem, Annaba Bay (Algeria)

Type Article
Date 2020-06
Language English
Author(s) Hadjadji Imen1, 7, Laabir Mohamed7, Frihi Hocine1, Collos Yves8, Shao Zhao Jun3, Berrebi Patrick3, Abadie EricORCID2, Amzil Zouher4, Chomérat NicolasORCID5, Rolland Jean-Luc6, Rieuvilleneuve Fabien7, Masseret Estelle7
Affiliation(s) 1 : Laboratoire « Bioressources marines », Université Badji-Mokhtar-Annaba, BP 12, El-Hadjar, 23000, Annaba, Algeria
2 : Univ Montpellier, MARBEC, UMR 9190, IRD, CNRS, IFREMER, F-34095 Montpellier, France
3 : Univ Montpellier, CNRS, ISEM, IRD, EPHE, Montpellier, France Montpellier, CC065, Place E. Bataillon, 34095, Montpellier, Cedex 5, France
4 : Laboratoire Environnement, Microbiologie et Phycotoxines, Ifremer, Rue de l’Ile d’Yeu BP 21105, Nantes, CEDEX 3 44311, France
5 : IFREMER, Laboratoire Environnement et Ressources Bretagne Occidentale, Station de Biologie Marine, Place de la Croix, 29900, Concarneau, France
6 : IHPE, Université de Montpellier, CNRS, Ifremer, UPVD, Montpellier, France
7 : Univ Montpellier, MARBEC, UMR 9190, IRD, CNRS, IFREMER, F-34095 Montpellier, France
8 : Univ Montpellier, MARBEC, UMR 9190, IRD, CNRS, IFREMER, F-34095 Montpellier, France
Source Toxicon (0041-0101) (Elsevier BV), 2020-06 , Vol. 180 , P. 79-88
DOI 10.1016/j.toxicon.2020.04.005
WOS© Times Cited 6
Keyword(s) Alexandrium pacificum, Mediterranean, Toxin profile, Growth, Intraspecific variability
Abstract

Physiological plasticity gives HABs species the ability to respond to variations in the surrounding environment. The aim of this study was to examine morphological and physiological variability in Alexandrium pacificum R.W. Litaker (Group IV) (former Alexandrium catenella) blooming in Annaba bay, Algeria. Monoclonal cultures of up to 30 strains of this neurotoxic dinoflagellate were established by the germination of single resting cysts from the surface sediment of this southern Mediterranean marine ecosystem. Ribotyping confirmed formally for the first time that A. pacificum is developing in Eastern Algerian waters. Toxin analyses of A. pacificum strains revealed substantial intraspecific variability in both the profile and toxin amount. However, the toxin profile of most strains is characterized by the dominance of GTX6 (up to 96 mol %) which is the less toxic paralytic molecule. The toxin concentrations in the isolated strains varied widely between 3.8 and 30.82 fmol cell−1. We observed an important variation in the growth rate of the studied A. pacificum strains with values ranging from 0.05 to 0.33 d−1. The lag time of the studied strains varied widely and ranged from 4 to 20 days. The intraspecific diversity could be a response to the selection pressure which may be exerted by different environmental conditions over time and which can be genetically and in turn physiologically expressed. This study highlights, for the first time, that the sediment of a limited area holds an important diversity of A. pacificum cysts which give when germinate populations with noticeable physiological plasticity. Consequently, this diversified natural populations allow an exceptional adaptation to specific environmental conditions to outcompete local microalgae and to establish HABs which could explain why this dinoflagellate is successful and expanding worldwide.

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Hadjadji Imen, Laabir Mohamed, Frihi Hocine, Collos Yves, Shao Zhao Jun, Berrebi Patrick, Abadie Eric, Amzil Zouher, Chomérat Nicolas, Rolland Jean-Luc, Rieuvilleneuve Fabien, Masseret Estelle (2020). Unsuspected intraspecific variability in the toxin production, growth and morphology of the dinoflagellate Alexandrium pacificum R.W. Litaker (Group IV) blooming in a South Western Mediterranean marine ecosystem, Annaba Bay (Algeria). Toxicon, 180, 79-88. Publisher's official version : https://doi.org/10.1016/j.toxicon.2020.04.005 , Open Access version : https://archimer.ifremer.fr/doc/00624/73620/