The NIOZ Repository gives free access to the digital collection of the work of the Royal Netherlands Institute for Sea Research. This archive is managed according to the principles of the Open Access Movement, and the Open Archive Initiative. Each publication should be cited to its original source -please use the reference as presented. When using parts of, or whole publications in your own work, permission from the author(s) or copyright holder(s) is always needed.

The Antarctic Circumpolar Current has a high potential for primary production and carbon sequestration through the biological pump. In the current study, two large-scale blooms observed in 2012 during a cruise with R.V. Polarstern were investigated with respect to phytoplankton standing stocks, primary productivity and nutrient budgets. While net primary productivity was similar in both blooms, chlorophyll a –specific photosynthesis was more efficient in the bloom closer to the island of South Georgia (39 °W, 50 °S) compared to the open ocean bloom further east (12 °W, 51 °S). We did not find evidence for light being the driver of bloom dynamics as chlorophyll standing stocks up to 165 mg m−2 developed despite mixed layers as deep as 90 m. Since the two bloom regions differ in their distance to shelf areas, potential sources of iron vary. Nutrient (nitrate, phosphate, silicate) deficits were similar in both areas despite different bloom ages, but their ratios indicated more pronounced iron limitation at 12 °W compared to 39 °W. While primarily the supply of iron and not the availability of light seemed to control onset and duration of the blooms, higher grazing pressure could have exerted a stronger control toward the declining phase of the blooms.

No abstract

The NIOZ Repository gives free access to the digital collection of the work of the Royal Netherlands Institute for Sea Research. This archive is managed according to the principles of the Open Access Movement, and the Open Archive Initiative. Each publication should be cited to its original source -please use the reference as presented. When using parts of, or whole publications in your own work, permission from the author(s) or copyright holder(s) is always needed. and closed using a butterfly-valve closing mechanism. The samplers are mounted on an alltitanium frame and deployed using a poly-aramide hydrowire (Super Aram) with internal power/signal conductors. Upon recovery the complete frame is immediately placed in its own clean-air laboratory unit. Samplers are (i) always closed when onboard, (ii) always mounted on the frame without the need for hand-carrying heavy samplers, and (iii) can be deployed again with minimal (manual) preparation. The PRISTINE ultraclean sampling system was used for the first time during the GA02 GEOTRACES cruises in the West Atlantic Ocean