Effect of water temperature and irradiance on growing crustose stage of Grateloupia divaricata (Rhodophyta)
摘要
Grateloupia divaricata provides a habitat for amphipods in coastal ecosystems as well as serving as a valuable resource for pharmaceutical and food products. The distribution and production of Halymeniales, including G. divaricata, have declined since the mid-1980s in Korea, located at the southern limit of its northwestern Pacific distribution. Therefore, developing seedling production techniques is essential for the conservation and aquaculture of these ecologically and economically important species. This study examined the effects of water temperature and irradiance on the growth of the crust as well as identified optimal growth conditions. Crusts were cultured under 15 experimental conditions, combining five temperatures (10, 15, 20, 25, and 30 °C) and three irradiances (50, 90, and 130 µmol photons m⁻2 s⁻1) for 3 weeks. During the first week, growth rates were higher at 25–30 °C. However, with longer cultivation times, optimal growth consistently occurred at 20 °C across all the irradiance conditions. At the same temperature, growth rates were higher under 90–130 µmol photons m⁻2 s⁻1 than under 50 µmol photons m⁻2 s⁻1. These findings provide insights into the physiological responses of G. divaricata to temperature and irradiance and contribute to seedling production in aquaculture.