Evolution of thalli and polysaccharide quality of holopelagic Sargassum species during their drift until their stranding, Stiger-Pouvreau, V.1*, Chatelain, B.1, Kergosien, N.1,2, Deslandes, E.1,Cosquer, N.3, Dromard, C.4, Thouard, E.5, Thibaut, T.6, Changeux, T.6, Berline, L.6, & Connan, S1., Poster EPC8