Distribution of chaetognaths in the Japan Sea in the winter of 1997 and in the autumn of 1999

Abstract

There was no remarkable difference of chaetognath biomass among station in winter (10.6mg/m^3 in mean) in the Japan Sea. Biomass in autumn ranged from 1.4-45.4mg/m^3 (16.1mg/m^3 in mean) and high biomass was recognized in southern Japan Sea below than 38°N. Two genera ten species was collected in the autumn 1999. Warm water species were not collected in the winter 1997. Many warm water species were transported into the Japan Sea from the south by the Tsushima Current in the autumn and distributed in wide waters of the middle Japan Sea. The proportion of the number of sampling stations located in mixed water and warm water was 75.8% but 11.1% in the winter. Sagitta elegans was the dominant species and distributed below the thermocline in autumn and winter but abundance was high in the 0-100m layer in the northern Japan Sea where the surface layer was not coveved by Tsushima Current water.