Dynamics of microbial communities across the three domains of life over an annual cycle with emphasis on marine mucilage in the Southern Bay of Biscay resolved by microbial fingerprinting

Vanessa Rouaud (1) , Nicolas Susperregui (2) , Anne Fahy (1) , Remy Guyoneaud (1) , Sabrina Bichon (3) , Camilla Liénart (4) , Yolanda del Amo (3) , Nicolas Savoye (3) , Philippe Gaudin (5) , Robert Duran (1) , Béatrice Lauga (1)

1 IPREM - Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux
2 Institut des Milieux Aquatiques
3 EPOC - Environnements et Paléoenvironnements OCéaniques
4 BOREA - Biologie des Organismes et Ecosystèmes Aquatiques
5 ECOBIOP - Ecologie Comportementale et Biologie des Populations de Poissons

Marine mucilage has been described as worldwide phenomena occurring sporadically, or frequently in certain coastal areas. They are transitory phenomena that can remain in the photic zone for several days or weeks. Their occurrence has been more frequent and persistent, and their magnitude has increased during the last decades. Their formation typically reflects an imbalance in the marine microbial communities, and has frequently be linked to global changes. Recurrent marine mucilage events have been observed in recent years in the Southern Bay of Biscay near the French coast, mainly south of the Adour estuary. In this study, we used a fingerprinting method (T-RFLP) targeting 16S and 18S rRNA genes to investigate marine microbial community composition and dynamics over an annual cycle across the three domains of life in coastal water at three depths, in the Adour River upstream of the mouth and in the marine mucilage. In line with studies conducted in marine environments we highlighted that the dynamics of marine microbial communities in the Bay of Biscay coincided with two environmental contexts: winter and spring on one hand and summer and autumn on the other hand. More interestingly, this dynamics affects also the marine pelagic mucilage that was observed during the sampling campaigns. Thus, the composition of the marine mucilage that appears in winter/spring context diverges from the composition of the marine mucilage that occurred during the summer/autumn context. We highlighted also that marine microbial communities were partly different from marine mucilage communities with an enrichment of some microorganisms suggesting that marine mucilage behaves as a microhabitat in seawater and possesses distinct microbial assemblages from the surrounding communities.

Mots clés: Microbial community structure; Mucilage; Littoral; River; Coastal seawater; T-RFLP fingerprinting

Domaines: Sciences de l'environnement; Milieux et Changements globaux

Vanessa Rouaud, Nicolas Susperregui, Anne Fahy, Remy Guyoneaud, Sabrina Bichon, et al.. Dynamics of microbial communities across the three domains of life over an annual cycle with emphasis on marine mucilage in the Southern Bay of Biscay resolved by microbial fingerprinting. Continental Shelf Research, 2019, 186, pp.127-137. ⟨10.1016/j.csr.2019.06.003⟩. ⟨hal-02165465⟩