Zooplankton Investigations in Yatsushiro-kai, Western Kyushu, I

Regional and Seasonal Occurrences of the Important Zooplankton

Abstract

The occurrence of the zooplankton at 21 stations in Yatsushiro-kai, western Kyushu, was investigated in June, September and November of 1968, and March of 1969. Copepods formed the most predominant constituent among the collected zooplankton. Although Paracalanus parvus was abundant in most of the surveyed region, other copepods occurred. dominantly in the following order when going from the northeastern area toward the southwest:
Oithona nana→Acartia clausi→Microsetella norvegica→Oithona similis→Corycaeusspp. Yatsushiro-kai can be characterized biologically by dividing it into two main regions. The northern half is more embaymental and the southern half is more oceanic, bordered by an area where Microsetella norvegica occurred as the dominant. The area where Acartia clausi occurred dominantly is the most embaymental in the northern half, and the area where Corycaeus spp. occurred dominantly is the most oceanic in the southern half.