Seasonal, Topographical and Geographical Distribution of the Red Alga Gloiopeltis complanata (Harvey) Yamada in the Islands of Okinawa

Abstract

This paper deals with the seasonal, topographical and geographical distribution of edible red alga Gloiopeltis complanata in the islands of Okinawa. Survey using a quadrat was carried out from 1990 to 1991. This species occurs in the northern and northeastern parts of Okinawa island and the vicinity islands such as Ikei, Ie, and Kume. It has been previously reported from the islands of Zamami and Tokasiki of the Kerama. This species has never been observed in the islands of Sakishima. Thus, it seems that the southern limit of the distribution of G. complanata is the island of Okinawa and its immediate vicinity (26° latitude north) . The habitat of this species is the spray zone in the lateral coral reef. It grows on the rocky substrata of phyllite and sandstone. These substrata are prefered because they have greater capacity to hold moisture than Ryukyu limestone. The maximum biomass reached 610 g/m² in March when the maximum length was 2 cm. The germination starts in the beginning of November and the thalli alga disappear in the beginning of June.