지리학적 범위를 벗어나 한국 남해연안역에 출현한 요각류 Acartia hongi

Abstract

As a port baseline study of project “Development of Port Environmental Risk Assessment Technology” in Korea, mesozooplankton samples were seasonally taken at four major trading ports (Incheon, Gwangyang, Pusan and Ulsan) in 2007 for coping with the Ballast Water Management Convention. This study was designed to identify existence of non-indigenous zooplankton by investigating the seasonal variation in the species composition and abundances of mesozooplankton within each harbor limit. Incheon port, which located in the western coast of Korea, is biogeographically segregated from the ports of Gwangyang, Pusan and Ulsan in the southern coastal waters. Most species found at the ports during the study periods consisted of commonly occurring species in the coastal waters of Korea. However, coastal copepod Acartia hongi unusually occurred at ports in the southern coastal waters beyond their bioregions. The copepod A. hongi has mainly distributed in the brackish and/or coastal waters in the Yellow Sea. In the present study, A. hongi occurred dominantly at ports of Gwangyang (102-1,654 inds.m-3) and Pusan (37-230 inds.m-3) in spring, while it showed abundances less than 1 inds.m-3 at ports of Gwangyang, Pusan and Ulsan in summer. In contrast, the copepod has been continuously found with high range of averaged abundances (58-4,323 inds.m-3) at Incheon port corresponding to their original habitat during the study periods. Presently, there is no official regulation to prohibit ballast water discharge of ships entering our coastal waters in Korea. Thus, the possible explainable hypotheses about the occurrence of A. hongi beyond their bioregions could be discussed as an introduction by (1) transfer through ship’s ballast water pumped up from domestic ports faced with the Yellow Sea, (2) transfer through ship’s ballast water pumped up from Chinese coastal waters adjacent to the Yellow Sea, and (3) passive transport through “alongshore current” from coastal regions of sou