Summary
: P vs E experiments determining photosynthetic parameters and daily primary production were carried out east of Kerguelen Island during the KEOPS cruise in January and February 2005. The Kerguelen Plateau region is naturally enriched with iron, while deeper waters (>1000m) nearby may not be. Photosynthetic parameters over the Plateau tended to be higher than elsewhere. Primary production rates and standing stocks of chlorophyll-a over the Kerguelen Plateau were amongst the highest measured in Polar Waters of the Southern Ocean. In deeper waters away from the Plateau and near Heard Island column chlorophyll stocks were much lower, photosynthetic parameters tended to be lower and primary production much lower than over the Plateau. Size-fractionated chlorophyll results showed chlorophyll in the <2 micron size class was typically <1 percent of the total except adjacent to Heard Island, where it contributed about 8 percent. Nanoplankton in the >2 to <10 micron size class contributed up to 65 percent of the total chlorophyll in deep water only. Over the Kerguelen Plateau large diatoms dominated the chlorophyll biomass. These results will be compared to results from low iron regions in the Crozet Basin west of Kerguelen (Antares 4 experiment), and south of Tasmania along the WOCE SR 3 line in the Polar Southern Ocean.