Sargassum

Seaweeds are an excellent source of bioactive compounds and therefore the use of sustainable and food compatible extraction methods such as enzyme- (EAE) and ultrasound-assisted extraction were applied on Sargassum muticum, Osmundea pinnatifida and Codium tomentosum. Extracts were evaluated for proximate characterization and biological properties. Higher extraction yields were observed for C. tomentosum EAE (48-62%; p<0.05 for Cellulase and Viscozyme), followed by O. pinnatifida (49-55%; p<0.05 except Alcalase) and S. muticum (26-31%; p<0.05). Sargassum muticum extracts presented the highest nitrogen (25±2 mg/glyoph extract) and total phenolics (261±37 gcathecol equiv/glyoph extract) contents whereas higher sugars (78±14 mgglucose equiv/glyoph extract) including sulfated polysaccharides (44±8 mgNa2SO4 acid/glyoph extract) contents characterized O. pinnatifida extracts. Higher effect on hydroxyl-radical scavenging activity (35-50%) was observed for all extracts whereas S. m...

This study represents the efforts of a network of researchers to characterise the large, floating Sargassum (Fucales, Phaeophyceae) biomass that had reached the Brazilian coast in 2014 and 2015. Material collected during these events was identified as Sargassum natans and S. fluitans using morphological characteristics; ITS2 sequences showed low divergence (0%-3%) with sequences of nine other Sargassum species. Several epiphytic macroalgae, invertebrates and fishes were associated with the floating Sargassum. Satellite images did not support the hypothesis of slicks moving south from the Sargasso Sea in the northern Atlantic Ocean. This strengthens the hypothesis that there is a matrix of pelagic Sargassum in the central Atlantic Ocean and that biomass accumulation should be considered a result of the combination of physicochemical seawater conditions and biological interactions. The biomass accumulation of the stranded Sargassum was estimated during four events, peaking in 98 kg m À2 wet weight on a beach on the Amazonian coast. The landing of huge Sargassum biomass represents a potential source of environmental stress, as it can lead to an increase in oxygen demand and eventually synthesise and release chemical compounds with allelopathic properties. On the other hand, these floating islands are a fundamental element of the biogeography and macroecology of tropical environments in the Atlantic Ocean, providing connectivity south/north and east/west among marine biodiversity from Atlantic reef environments. Studies concerning Sargassum effects on local communities are necessary for the proper management of this phenomenon.

Effect of temperature, irradiance and photoperiod on biomass and the alginate content of Sargassum boveanum was evaluated for 42 days under laboratory conditions. The seaweed samples were collected from coast lines of Bandae-e-Lengeh in Hormozgan province (South of Iran) in June 2009. The algae were suspended in aquariums,40.30.60 cm (20 litter) in 3 replicates. The algae were cultured under temperatures gradients ( 15,20 and 25 ºC ), irradiances levels (4700,5700 and 6700 Lux) and three photoperiods (12;12, 14;10 and 16:8 hours, Light:Dark) . The algae were weighted once a week . After 6 weeks of experiments, the algae were collected, dried and weighed. The highest biomass of S. boveanum was obtained at 25° c (48.12 gr.) ,4700 Lux (42.48 gr) 12:12, light: dark (34 gr). Maximum content of alginate (29.67%) was extracted in temperature of 25 ºC. As the results showed, mariculture of this algae should done in spring with optimum of temperature and photoperiod. The alginate content of S. boveanum in this project is high in compare with the other studies.