2009년 하계 황해에서 Calanus sinicus 개체군의 수직적 분포

Abstract

Unlike previous observation, occurrence of Calanus sinicus was reported in the surface waters above 10m in the central area of the Yellow Sea in August 2007. Thus, we visited same area located in the Yellow Sea Cold Bottom Water (YSBCW) and surveyed the diel vertical migration of C. sinicus for confirmation of occurrence of the species in the surface waters in summer. However, we faced with the news of unexpected access of typoon \\\\'MORAKOT\\\\' into the station, thus, sampling was conducted from 15:00 to 21:00 on 5 August 2009. After sunset, total abundance of C. sinicus distinctively increased in the surface waters (0-20m). The increase was driven by upward migration of female adults and immature copepods V stage, which is opposite way to previous observation in the Yellow Sea in full summer. Temperature in the surface mixed layer ranged from 25 to 27.4℃, corresponding to the sub-lethal thermal range of the species. Upward migration of the species was known to be closely related with the feeding mechanisms. However, subsurface chlorophyll maximum formed mostly in the range of 20-40m, indicating that another possible explanation is required for occurrence of the species in the surface waters. Full scale survey of diel vertical migration in the study area is essential to understand the upward migration of the species into the surface waters in the full summer.