As decorative as this brown seaweed may be, it is considered a big nuisance. Japanese sargassum grows quickly and massively, causing lots of problems in harbours (jammed screws), on beaches (stink inconvenience when it dies) and for those that use seawater (cool-water admission, saltwater aquariums). Just like the name indicates, Japanese sargassum comes from Japan. Scientists think that it arrived in the North Sea via Japanese oysters and attached to ships. At any rate, it has been present in the North Sea region since 1973 and in Dutch waters since 1980. Because this species contains many small gas bladders, it is not uncommon for plants to lift up their stony base and drift to other places.