2020年秋季に宇和島湾で発生した<i>Karenia mikimotoi</i>赤潮と急潮の関係

Abstract

A red tide of the harmful dinoflagellate Karenia mikimotoi occurred in Uwajima Bay from early September to mid-November 2020, the latest occurrence observed in this bay. Although genes of K. mikimotoi had been detected since the winter, low water temperatures associated with the offshore shift of the Kuroshio Current and the existence of competing species apparently delayed its bloom. The Kyucho in mid-and late-August potentially promoted the bloom by raising water temperature, dispersing competing species, and supplying nutrients to the bottom layer. In addition, typhoons approaching in early September appeared to have caused plankton to accumulate in the inner parts of Uwajima Bay by the west wind and to have reduced the duration of sunshine, consequently promoting the bloom of K. mikimotoi.