Scripps Institution of Oceanography

The value of any seaweed crop is enhanced by the name under which the seaweed is sold, for the kind and quality of the seaweed product is announced with its name. Thus, though chemists may say that the agar from Gelidium species is the same as that from Gracilaria species, industry will pay more for Gelidium than for Gracilaria. (It might be so because the agarose fraction is higher in Gelidium, and agarose commands a higher price on its own.) In the case of the seaweeds that produce the colloid carrageenan, some species form only kappa-carrageenan (which produces a firm gel), others produce only iota- carrageenan (which forms a soft gel), and still others form only lambda-carrageenan (which does not gel).

In geographic areas or developing countries where the identity of seaweeds is not known or is uncertain, the economic potential for using this untapped seaweed resource is unrealized. For Japan and China, on the contrary, which have and use many named seaweed species, the financial gain in the world market can be more easily accomplished, since demand for certain colloids currently exceeds supply. One of Chile's major exports is seaweed, sold for extraction of colloids in other countries.

We chose to focus on the four economically important seaweeds that have warm-water representatives because the useful temperate algae are fairly well known and do not have taxonomic or nomenclatural problems that approach those in the tropics. The groups we chose are Gelidium, Pterocladia, Gelidiella, Yatabella, Acanthopeltis (treated as one group, the Gelidiales), Gracilaria, Polycavernosa, Eucheuma, and Sargassum.