亜熱帶に育つ コンブ科海藻アントクメ

摘要

Eckloniopsis radicosa is the only species which distribute up to the sub torrid zone in the Laminaliales.This alga distributes on the western coast of Izu Peninsula, while on the eastern coast of that Ecklonia cava andEisenia bicyclis distribute. Eckloniopsis radicosa is recently found on the southwestern coast of Manduru Peninsula,and this area is regarded as the new northern limit of distribution area of Eckloniopsis radicosa on the pacific coast.Kanbayashi compared the daily compensation light quantity-temperature curves of Eckloniopsis radicosa and Eckloniacava in order to analyze the mechanism inducing the difference in distribution between those two species, butobtained a result contrary to his expectation that the sporophyte of the former would be more heat-tolerant than thatof the latter. This fact is considered to be due to that Eckloniopsis radicosa is an annual plant while Ecklonia cava aperennial plant. The sporophyte of the former germinates in a winter and discharges spores in a late spring, while thesporophyte of Ecklonia cava needs to pass the summer at least once to get the ability of discharging spores. In boththe algae gametophytes derived from spores is far more heat-tolerant than sporophytes. Since the sporophyte ofEckloniopsis radicosa needs not to pass the summer while that of Ecklonia cava needs to pass the summer at lestonce, the sporophyte of the former is not more heat-tolerant than that of the latter. Eckloniopsis radicosa coulddistribute the southernmost area in the Laminariales in consequence of the change from the perennial type to theannual one in its life cycle.