Study of Algal Flora on the Sea Urchin Fishing Ground, Amami-Oshima Is., Kagoshima, Japan

Abstract

An investigation was carried out to ascertain the distribution and biomass of macroalgae on the sea urchin (Tripneustes gratilla) fishing ground, Amami-oshima Island, Kagoshima Prefecture, Japan, in the month of June and July 1988. Thirtyeight different species of algae was collected from 7 different localities. A subtropical brown algae Sargassum alternato-pinnatum YAMADA was the dominant species among the samples. It was also found that the Sargassum and the red algae Hypnea and Corallina which attached on the thallus of the Sargassum comprised 75% of the total biomass and mostly contributed natural diet for the urchin on the ground. Standing stocks of algae were estimated as 0.5-1.7 kg wet weight/m². Cluster analysis was also done to distinguish similarity among the localities.