RESPIRATION AND BIOCHEMICAL-COMPOSITION OF SEDIMENTING ORGANIC-MATTERDURING SUMMER IN THE BARENTS SEA

Sedimentation of particulate carbon and nitrogen, pigments (fluorometr ic and HPLC analysis) as well as the activity of the respiratory elect ron transport system in sedimented matter were studied with unpoisoned , short-term deployed sediment traps during June in the central Barent s Sea. The vertical flux of sedimenting material and its biochemical c omposition in the central Barents Sea was different during summer comp ared to spring with decreased flux of organic matter and decreased rel ative supplies of particulate nitrogen, but increased phaeopigment con centrations. The summer situation in the Barents Sea is characterized by recycling of the bulk of the suspended matter in the upper layers, a comparatively small loss of suspended biomass, but high sinking rate s of some few, large particles, presumed to be faecal pellets. Respira tion calculated as a daily loss rate of carbon in the sedimented mater ial was on average only 1.4% day-1. Loss was strongly temperature depe ndent. At in situ temperatures >5-degrees-C, it is necessary to estima te turnover rates for sedimenting carbon in non-poisoned traps for an accurate elemental budget of a system and for interpretation of estima tes from long-term trap deployments.