Reproductive strategy of Acartia steueri in Sagami Bay, Japan

Abstract

Reproduction, hatching success and population dynamics of the dominant copepod Acartia steueri were studied in Sagami Bay, Japan from February 2002 to December 2003. A. steueri occurred through the year in the water column, and it produced physiologically different eggs, subitaneous and diapausing. Subitaneous eggs were produced through the experimental period, whereas diapausing ones were restricted from February to August in both years. Population egg production rate (EPR) increased with the abundance of adult males and females from February and reached maximum in June. However, planktonic population of A. steueri did not increase during summer to winter because diapausing eggs occupied a great part of their reproduction (~98%). Recruitment rates in October to December 2002 and September 2003 were higher than population EPR, implying that diapausing eggs of A. steueri had a key role to support the recruitment into water column when the reproductive ability of the population diminished rather than to contribute to an increase of the planktonic population rapidly in their favorable seasons

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