한국 남해동부 연안 일광만의 부유성 요각류 Acartia steueri의 현장 알 생산력

Abstract

Egg production rate (EPR) of the planktonic copepod Acartia steueri was investigated in in situ incubations from October 1997 to September 1998 in Ilkwang Bay, southeastern coast of Korea. Water temperature ranged from 11.5 to 25.6°C, and chlorophyll a concentration was 0.99~11.63 mg m-3 with peaks in late February, early April and May-June. A. steueri occurred in the plankton throughout the year, except September and October, with the highest peak in March. The EPR ranged from 3.8 to 10.1 eggs female-1 d-1 (mean: 7.3 eggs female-1 d-1), and the rate was the lowest in December and then increased gradually until June. Seasonal variation of population egg production rate (eggs m-3 d-1) was similar to the abundance of A. steueri in this bay, showing the highest peak in March. Relationship between EPR and chlorophyll a concentration was highly significant and ~85% of EPR was explained by the variation of the chlorophyll a concentration. However, only ~37% of EPR was related to the variation of water temperature. Weight-specific growth rate ranged from 0.022 to 0.071 d-1 (mean: 0.047 d-1) and decreased with increasing body weight of the adult female. The mean EPR in terms of eggs per female per day of A. steueri measured by incubation method was similar to the result from Kang and Kang (1998), in which EPR was estimated using the equation obtained in the laboratory experiment relating temperature and chlorophyll a concentration to egg production.