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D-3.2.2 Studies on changes in distribution of chlorophyll a and phytoplankton in Tsushima Current Area

[Contact Person]

Mitsuyuki Hirai
Japan Sea National Fisheries Research Institute, Fisheries Agency
1-5939-22, Suido-cho, Niigata 951-8121, Japan
Tel: 025-228-0616 Fax: 025-223-7425
E-mail: mithirai@jsnf.affrc.go.jp

Total Budget for FY1996-1998

6,156,000Yen (FY1998; 2,033,000Yen)

Abstract:

In order to estimate the influence of nutrient-rich terrestrial waters from Asian Continent in the Tsushima Current waters, hydrographic observations were carried out in summer when surface low-salinity waters developed. As a result, there was a negative correlation between surface salinity and chlorophyll-a. The distributions of low-salinity and high chlorophyll-a waters were often observed around the Tsushima Western Straits in the Japan Sea. However, nutrient were exhausted in surface layers of low-salinity and high chlorophyll-a waters. These results implied that nutrients supplied from terrestrial waters were immediately consumed within the East China Seas and high chlorophyll-a water extended to the Tsushima Strait. Species diversity of phytoplankton in the high chlorophyl-a waters were lower than that in the southwestern Japan Sea.

[Key Words]

Hydrographic condition, Chlorophyll, Water color, Nutrient, Species composition