TY - JOUR T1 - 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) A1 - Hadjadji,Imen A1 - Laabir,Mohamed A1 - Frihi,Hocine A1 - Collos,Yves A1 - Shao,Zhao Jun A1 - Berrebi,Patrick A1 - Abadie,Eric A1 - Amzil,Zouher A1 - Chomérat,Nicolas A1 - Rolland,Jean-Luc A1 - Rieuvilleneuve,Fabien A1 - Masseret,Estelle AD - Laboratoire « Bioressources marines », Université Badji-Mokhtar-Annaba, BP 12, El-Hadjar, 23000, Annaba, Algeria AD - Univ Montpellier, MARBEC, UMR 9190, IRD, CNRS, IFREMER, F-34095 Montpellier, France AD - Univ Montpellier, CNRS, ISEM, IRD, EPHE, Montpellier, France Montpellier, CC065, Place E. Bataillon, 34095, Montpellier, Cedex 5, France AD - Laboratoire Environnement, Microbiologie et Phycotoxines, Ifremer, Rue de l’Ile d’Yeu BP 21105, Nantes, CEDEX 3 44311, France AD - IFREMER, Laboratoire Environnement et Ressources Bretagne Occidentale, Station de Biologie Marine, Place de la Croix, 29900, Concarneau, France AD - IHPE, Université de Montpellier, CNRS, Ifremer, UPVD, Montpellier, France AD - Univ Montpellier, MARBEC, UMR 9190, IRD, CNRS, IFREMER, F-34095 Montpellier, France AD - Univ Montpellier, MARBEC, UMR 9190, IRD, CNRS, IFREMER, F-34095 Montpellier, France UR - https://doi.org/10.1016/j.toxicon.2020.04.005 DO - 10.1016/j.toxicon.2020.04.005 KW - Alexandrium pacificum KW - Mediterranean KW - Toxin profile KW - Growth KW - Intraspecific variability N2 - 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. Y1 - 2020/06 PB - Elsevier BV JF - Toxicon SN - 0041-0101 VL - 180 SP - 79 EP - 88 ID - 73620 ER -