Color of Cultivated Porphyra and its Fading (Iro-ochi) and Recovery

Iro-ochi as has been called by Nori (Porphyra) farmers is biologically a bleaching phenomenon and has been one of the serious problems in Nori cultivation in Japan. Especially in the last Nori cultivation season, Iro-ochi gave an extremely serious damage to the Nori production in Ariake Bay, Kyushu, Japan, which attracted considerable socio-economic attention in Japan. As early as in late 1960s, we already made fundamental studies on Iro-ochi of Porphyra. (omitted)