The Relation between Primary Production and the Flux of Particulate Organic Matter in the Sub-Arctic Coastal Sea

Abstract

The relation between primary production and the precipitating processes of particulate organic materials was manifested by measuring in situ some size-fractionated (No Screen, <690-μm and <350-μm) organic material fluxes and amino acids composition in the precipitating particles during a spring bloom and autumn in Funka Bay, the sub-Arctic coastal sea. The total flux (No Screen) of particulate organic material, in term of carbon, at a depth of 74 m during the spring bloom and the autumn accounted for, on average, 51% and 57% of primary production, respectively. However, the fluxes of particulate organic carbon in the <690-μm and <350-μm fractions were only, on average, 19% and 9% of primary production during the spring bloom, and 30% and 12% during the autumn, respectively. The composition of protein amino acids, the existence of glucosamine and detectable degrees of non-protein amino acids (γ-aminobutyric acid, β-alanine and ornithine) in the precipitating particles obtained from our sediment trap experiment demonstrated that the precipitating organic particles were dominated by some microzooplankton source materials even in the <350-μm fraction. At the coastal sea, the precipitating organic particles are as few as the phytoplankton itself produced in the euphotic zone, the bulk of the phytoplankton might be removed from a water column by the predation of zooplankton, and a part of the removed phytoplankton might change in larger-sized precipitating zooplankton source materials.