The Open University ’ s repository of research publications and other research outputs Primary production export flux in Marguerite Bay ( Antarctic Peninsula ) : linking upper water - column production to sediment trap flux

A study was carried out to assess primary production and associated export flux in the coastal waters of the western Antarctic Peninsula at an oceanographic time-series site. New, i.e. exportable, primary production in the upper water-column was estimated in two ways; by nutrient deficit measurements, and by primary production rate measurements using separate C-labelled radioisotope and N-labelled stable isotope uptake incubations. The resulting average annual exportable primary production estimates at the time-series site from nutrient deficit and primary production rates were 13 and 16 mol C m respectively. Regenerated primary production was measured using N-labelled ammonium and urea uptake, and was low throughout the sampling period. The exportable primary production measurements were compared with sediment trap flux measurements from 2 locations; the time-series site and at a site 40 km away in deeper water. Results showed ~1% of the upper mixed layer exportable primary production was exported to traps at 200m depth at the time-series site (total water column depth 520m). The maximum particle flux rate to sediment traps at the deeper offshore site (total water column depth 820m) was lower than the flux at the coastal time-series site. Flux of particulate organic carbon was similar throughout the spring-summer high flux period for both sites. Remineralisation of particulate organic matter predominantly