Secondary production of Acartia steueri and A. omorii (Copepoda: Calanoida) in a small bay, southeastern coast of Korea: The growth rate approach

Abstract

Secondary production of marine calanoid copepod Acartia steueri and A. omorii were measured from 2 October 1991 to 8 October 1992 at a station in a small bay on the southeastern coast of Korea, using the traditional growth rate method. Phytoplankton standing stock ranged from 1.0 to 9.3 mg chl.a m-3. The two Acartia species were present throughout the year, while seasonal variation was found for their abundance. Biomass of A. steueri was averaged at 0.68 mgC m-3 with peaks in November, February, May, and July-early August, and relatively low biomass in September-January. For A. omorii, the biomass was averaged at 0.44 mgC m-3, with peaks in February and July, and relatively low biomass in late summer and fall. Annual production of A. steueri was 25.1 mgC m-3 yr-1 (or 166 mgC m-2 yr-1), showing peaks in November, May, and July-August with a small peak in February, and low production in December-April and September-October. For A. omorii, annual production was 33.5 mgC m-3 yr-1 (or 221 mgC m-2 yr-1), with peaks in February and July. There was no significant relationship of the daily production rate of A. steueri to water temperature or chlorophyll a concentration. However, the daily production rate of A. omorii was significantly correlated with chlorophyll a concentration, indicating that phytoplankton was the major influencing factor for seasonal variation of production of A.omorii in the bPhytoplankton standing stock ranged from 1.0 to 9.3 mg chl.a m-3. The two Acartia species were present throughout the year, while seasonal variation was found for their abundance. Biomass of A. steueri was averaged at 0.68 mgC m-3 with peaks in November, February, May, and July-early August, and relatively low biomass in September-January. For A. omorii, the biomass was averaged at 0.44 mgC m-3, with peaks in February and July, and relatively low biomass in late summer and fall. Annual production of A. steueri was 25.1 mgC m-3 yr-1 (or 166 mgC m-2 yr-1), showing peaks in November1