Nitrogen Uptake by Size-Fractionated Phytoplankton Populations in Antarctic Surface Waters

Nitogen uptake experiments in surface waters off the coast between Cape Ann and Mawson indicate that reduced nitrogen (ammonium and urea) supplied an average of 58% of phytoplankton requirements. Size-fractionation studies provided evidence for nitrogen resource partitioning between the algae of different size classes at three of the five stations. On average, regenerated production ammounted to 62% for the nanoplankton and 75% for the picoplankton.