海藻という植物

摘要

The members of Sargassaceae make Sargassum beds with productivities no less than those of marineforests made by the members of Laminariaceae. The estimation of the net production in Sargassum beds is, however,more difficult than in marine forests, because the growth is happens at the apical part in Sargassaceae species, whilethat is at the basal part in Laminariaceae species. The volume of matter produced by an individual can be easilyestimate with the punched-hole technique in Laminariaceae species of basal growth, but this technique is not appli-cable to Sargassaceae species of apical growth. Since Sargassacea species resemble terrestrial plants both in mor-phology and growth pattern, the stratified clip method is applicable to the estimation of net production in Sargassumbeds. Taniguti & Yamada') applied this method to estimate the yearly net production in the communities of Sargas-sum patens and S. macrocarpum at 4-6 m depth in Iida Bay of Noto Peninsula, and obtained 5,525.4 and 8,251.9 gdry weight.m-2.year-', respectively. These values are larger than those in tropical rain forests. Murase estimated theyearly net production in the community of S. patens at 8 m depth in Fukawa Bay of Yamaguti Prefecture with thesame method, and obtained 1,600.1 g dry weight.m-2.year'. The difference between both the values in Iida Bay andFukawa Bay is attributable to the difference in depth of the investigation point and length of individuals. The averageindividual length of S. patens is reached about 4 m in Iida Bay, while it was about 2 m in Fukawa Bay. Mikami6)obtained 7,663.5 g dry weight.m-2.year'as the yearly net production in the community of S. patens at 1-4 m depth inSimoda Bay of Izu Peninsula with measuring the photosynthetic activities of thallus segments. This value is farlarger than that in the community of the same species in Iida Bay. The photosynthesis method applied by Mikamican estimate the net production including DOM(Dissolved Organic Matter)'2), while the methods applied by Taniguti& Yamada') and Murase5) can not. Mikami also obtained 2,381.2 and 5,657.3 g dry weight-m-2.yearl as the yearlynet production in the communities of S. ringgoldianum and S. horneri, respectively.