Sargassum & tropical spp.

Sargassum stands out for its diversity and high productivity across the tropical Indian Ocean, doing well in almost all conditions including high temperature and CO₂ and both oligotrophic and eutrophic conditions, as well as its capacity to live in pelagic condition. This rapidly growing seaweed has a naturally high content of antioxidants, carotenoids, and phenols, including anticancer compounds such as fucoxanthin, making this species a potential source for a range of pharmaceutically relevant products. Left-over material from extraction/production provides material for biofuel or fertilizers, a clever alternative to land crops not requiring deforestation, watering or chemical fertilizers. Sargassum is also particularly relevant for environmental remediation as a low cost and natural biosorbent for wastewater treatment (e.g. fluorides and heavy metals), and for CO₂ uptake with carbon content above average (35% of the dry weight).

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Sargassum C. Agardh is the richest genus of the marine macrophytes and probably the taxonomically most complex genus of the Phaeophyceae. Its species are distributed Worldwide and are especially well represented in tropical and subtropical regions where they structure large submarine thickets. These thickets represent an essential habitat for numerous marine species and may be considered as an equivalent to the Fucales, Cystoseira or Kelp forests of temperate regions (Nizamuddin, 1962; Phillips, 1995; Steneck et al., 2002; Thibaut et al., 2005). Some species have an important economic potential, especially in Asia were they are collected for agrofood, textile, cosmetic and pharmaceutic industries. Despite their ecological and economic significance, identifying a species is very difficult. This is mainly due to important intra-specific morphological variations and the existence of nearly 1,400 described taxa of which less than 25% are recognised as current taxonomically. Placing a species in one of the sections or other subdivisions of the genus is also often a challenge because of a classification system based on ancient material, often fragmentary and not representing the species polymorphy. Since 1985, Sargassum has been the attention of several studies (Abbott 2004), but significant taxonomic revision only really started with the advent and evolution of molecular tools (Stiger et al. 2000, 2003, Phillips & Fredericq 2005, Mattio & Payri 2011, Dixon et al. 2014). Today, the diversity and systematics of the genus Sargassum are better understood but a lot of geographical regions are still waiting to be (re)assessed...