@TreeMan - I grew up in the New England area, and you could find Sargassum there, too. At least that's what we were always told it was.
I never cared for it much, but I have known people who used it in salads if it wasn't too bitter. Apparently it is supposed to be a useful cure for goiters, too.
I am interested in the algal seas Sargassum can make in the ocean. What other things besides eels use the seaweed forests? Are there any popular fish that are there?