Fig 1.
Schematic representation of S. muticum identifying the differentiated tissues considered in this study: Tip, receptacle, basal blades and holdfast.
Fig 2.
Alpha-diversity of bacterial communities.
Chao 1 (A), OTU richness (B) and Shannon index (C) alpha diversity measures of bacterial communities associated to S. muticum across seasons at its northern (VC: Viana do Castelo) and southern distribution in Portugal (PC: Porto Covo). Differentiated are the environmental samples of sediments (color circle) and seawater (empty square), and the seaweed structures holdfast (rombe), basal blades (color square), receptacles (color triangle), and tip (empty circle). Values are means ± standard error (n = 3).
Fig 3.
Distribution of bacteria phyla associated with Sargassum muticum.
Relative distribution of the bacteria phyla associated with different structures of the brown seaweed Sargassum muticum, sediments (Sed) and surrounding seawater (SW) in northern (Viana do Castelo (A)) and southern (Porto Covo (B)) Portugal in September, March and July/August. Tissues are holdfast (Hf), basal blades (Bb), receptacle (Rec) and tip (Tip).
Fig 4.
Structure of microbial communities associated with Sargassum muticum.
Canonical Analysis of Principal coordinates of the bacterial communities associated with Sargassum muticum, sediments (+) and seawater (*) samples collected in southern (Porto Covo) and northern (Viana do Castelo) Portugal in September (light blue), March (dark blue) and July-August (orange). Distinguished structures are holdfast (HF) (diamond), basal blades (square), receptacle (Rec) (down facing triangle) and tip (up facing triangle).
Fig 5.
Sargassum muticum consistent bacterial genera across structures.
Venn diagram representing the number of bacterial genera present across all S. muticum structure samples in North (A) and South (B) Portugal in different months. Vertical bars show phylum composition of each month (non-shared genera) and shared among all months.
Fig 6.
Most abundant bacterial classes associated with the different types of S. muticum tissues across seasons between North and South Portugal.
A) Tips; B) Receptacles; C) Basal blades; D) Holdfasts.