Temporal variability in primary and copepod production in Sagami Bay, Japan

Abstract

Seasonal variations in primary production and in abundance, biomass and production of the planktonic copepod community were investigated in the neritic area of Sagami Bay, Kanagawa, Japan, from January 2002 to December 2004. Primary production (PP) determined by 13C in situ incubation was ca. 0-1321.4 μg C L -1 day -1 (or 0.044-4.643 g C m -2 day -1). Copepod abundance, biomass and production rates showed remarkable seasonal and interannual variations, being highest in March 2002, with an overall mean of 3.11 × 10 3 ind. m -3, 8.85 mg C m -3 and 0.94 mg C m23 day, -1, respectively. The depthintegrated copepod secondary (SP) and tertiary production (TP) was 0.0038-0.401 and 0.00079-0.048 g C m -2 day -1, respectively. Transfer efficiencies from PP to SP and TP was 0.3-74.6% (mean: 4.1%) and 0.1-27.5% (mean: 0.8%), respectively. Transfer efficiency of PP-SP and PP-TP decreased exponentially with PP, and there were significant correlations between PP and transfer efficiency of PP-SP and PP-TP, respectively. The depth-integrated food requirement by copepod secondary and tertiary producers was estimated to be 0.012-1.29 and 0.0024-0.185 g C m -2 day -1, corresponding to 1.1-267.6% (mean: 14.3%) and 0.2-105.6% (mean: 2.6%) of PP, respectively. © The Author 2006.