西九州周辺海域における有害渦鞭毛藻 Cochlodinium polykrikoides の季節的消長(2006年4月〜2007年4月)

概要

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An unarmored dinoflagellate Cochlodiniurn polyhrihoides has formed red tides responsible for fish mass mortalities especially in ・western Japanese and southern Korean coasts in almost every summer. Optimum temperature for growth of this species is ca. 27°C. Since the species can not survive less than 10°C, it was speculated to overwinter in some certain regions as a motile form or resting cyst, and expanded the distribution after temperature increased up to the tolerable degree for growth. To determine the overwintering regions and migration pattern of C polykrikoides, occurrences of the motile cell were surveyed in the coasts and offshore of western Kyushu, Japan from April 2006 to April 2007. Cells of C polykrikoides were found from 10 of 18 investigated sites for 13 months. Since motile cells occurred through a year in Usuka Bay, Hirado, Nagasaki, it implies that this area is one of the grounds overwintering regions in western Kyushu. From offshore regions of Fukue Island and off Shin-Nagasaki Fishery Harbor of Nagasaki, motile cells of C. polykrikoides were first detected in the late of May, and were continuously found until August. At there sites mo-tile cells appeared before red tides of formation C. polykrikoides reported at coastal areas in western Kyushu.
長崎大学の論文