Annual Life Cycle and Productivity of the Laminaria japonica Population in Onagawa Bay, Northeastern Honshu, Japan

Abstract

Annual life cycle and productivity of the Laminaria japonica population were studied by monthly quadrat samplings at depths of 1-2 m in Onagawa Bay, northeastern Honshu, Japan, from November 1998 to December 1999. The annual life cycle was characterized by four phases: germination from December to April, straight growth from April to July, substantialization from July to October and maturation from October to December. The thalli grew slowly, and decayed away quickly in 1999 under a high sea water temperature. The annual net production was estimated to be 1272.9g dry weight/m²/year, with a turnover ratio of 4.1.