Accumulation of detached kelp biomass in a subtidal temperate coastal ecosystem induces succession of epiphytic and sediment bacterial communities.
|Author(s)||Brunet Maéva1, de Bettignies Florian2, Le Duff Nolwen1, Tanguy Gwenn3, Davoult Dominique2, Leblanc Catherine1, Gobet Angelique1, 4, Thomas François1|
|Affiliation(s)||1 : Sorbonne Université, CNRS, Integrative Biology of Marine Models (LBI2M), Station Biologique de Roscoff (SBR) 29680 Roscoff, France
2 : Sorbonne Université, CNRS, UMR 7144 AD2M, Station Biologique de Roscoff (SBR) 29680 Roscoff ,France
3 : Sorbonne Université, CNRS, FR2424, Genomer, Station Biologique de Roscoff 29680 Roscoff, France
4 : MARBEC, Univ Montpellier, CNRS, Ifremer, IRD Sète, France
|Source||Environmental Microbiology (1462-2912) (Wiley), 2021-03 , Vol. 23 , N. 3 , P. 1638-1655|
Kelps are dominant primary producers in temperate coastal ecosystems. Large amounts of kelp biomass can be exported to the seafloor during the algal growth cycle or following storms, creating new ecological niches for the associated microbiota. Here, we investigated the bacterial community associated with the kelp Laminaria hyperborea during its accumulation and degradation on the seafloor. Kelp tissue, seawater and sediment were sampled during a six‐month in situ experiment simulating kelp detritus accumulation. Evaluation of the epiphytic bacterial community abundance, structure, taxonomic composition and predicted functional profiles evidenced a biphasic succession. Initially dominant genera (Hellea, Litorimonas, Granulosicoccus) showed a rapid and drastic decrease in sequence abundance, probably outcompeted by algal polysaccharide‐degraders such as Bacteroidia members which responded within 4 weeks. Acidimicrobiia, especially members of the Sva0996 marine group, colonized the degrading kelp biomass after 11 weeks. These secondary colonizers could act as opportunistic scavenger bacteria assimilating substrates exposed by early degraders. In parallel, kelp accumulation modified bacterial communities in the underlying sediment, notably favoring anaerobic taxa potentially involved in the sulfur and nitrogen cycles. Overall, this study provides insights into the bacterial degradation of algal biomass in situ, an important link in coastal trophic chains.