Sargassum johnsonii Sargassum johnsonii Sargassum johnsonii Chapman, 1961, is a brown seaweed of the genus "Sargassum" that is endemic to the Three Kings Islands in New Zealand. It is sometimes called totara weed because of the resemblance to the foliage of the NZ native tree totara. Its scientific name derives from its discoverer, Magnus Earle Johnson, Three Kings Islands explorer and captain of the yacht "Rosemary", who landed botanists on the islands on several occasions. "Sargassum johnsonii" grows in rocky intertidal habitats, often extending to the subtidal zone up to a depth of 40 m. It is a foundation species, and being
Sargassum muticum around the farming structures, requiring additional maintenance. It also gets entangled with the propellers of the boats. Mechanical removal—however this promotes dissemination of the species and the technique is labor-intensive. Chemical—the use of herbicides is advised against, because it poses a major risk to the environment and others organisms. Biological—there are few natural predators, one example is a little copepod that will eat only the unhealthy and damaged parts of "S. muticum." Currently the distribution is stabilized, and only mechanical removal is performed. There are some potential uses for "Sargassum muticum." In agriculture, algae are used as sources of nitrate