Zygote culture and zoospore release experiment of a green seaweed Monostroma nitidum Wittrock (Chlorophyta) for possible mass cultivation in Taiwan.

Abstract

Artificial seed production and field culture experiments of Monostroma nitidum Wittrock, a green seaweed grown in Taiwan, was conducted. Mature fronds were collected on February 20, 2017. Gametes were released in the following morning from them and their fusion was observed. Zygotes developed into cyst-like forms called Codiolum-cyst and were cultured under room conditions with temperature range of 23–290C until they grew to 36.3±3.2 μm in August. Dark treatment to induce the maturity was applied to them from September 12 to October 30. On November 1, zygotes kept under dark conditions were taken out to the outdoor tank to release zoospores and to collect them on culture nets, which were then kept for five weeks in the tank. The nets were opened in the sea at Jiang-Mei on December 8, 2017. Young fronds about 5–8 cm in length were observed on January 10, 2018 which grew to over 10 cm in length by February 6, 2018. Through the experiments, the dark treatment proved to be effective in inducing gamete release and to synchronizing zygote maturity of M. nitidum.