Growth of Sargassum fusiforme, Undaria pinnatifida and Meristotheca papulosa when cultivated in different water temperature conditions from the Seto Inland Sea to Bungo Channel

Abstract

Experimental cultivation of Sargassum fusiforme, Undaria pinnatifida and Meristotheca papulosa was conducted at six sites with different water temperature conditions from the Seto Inland Sea to eastern Bungo Channel (Uwa Sea). Among the sites, the maximum difference in water temperature was 5°C observed during February to March. Growth of S. fusiforme was better at the sites in the Uwa Sea except for Ainan, the southernmost site in the Uwa Sea, than at the sites in the Seto Inland Sea where the water temperature was mostly lower than 15°C during the cultivation period. In Ainan, the warmest site, most of S. fusiforme thalli were lost up to February. Undaria grew in the Seto Inland Sea and northern Uwa Sea, but thalli were also lost at the southern Uwa Sea sites. Scars marked on basal parts of these algae left on culturing ropes indicated signs of having been browsed by herbivorous fish. Meristotheca papulosa, which was cultured in cages, exhibited better growth at the warmer Uwa Sea sites. M. papulosa did not grow and died during winter at the sites of the Seto Inland Sea, though it exhibited a slight growth in spring when the mean water temperature exceeded 15°C.