Seasonal and interannual variability of size-fractionated phytoplankton biomass and community structure at station Kerfix, off the Kerguelen islands, Antarctica

• Main Authors: Michel Fiala, Elzbieta E. Kopczynska, Catherine Je, Louise Oriol, Gilles Vetion
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1998
• Subjects: Kerguelen; Kerguelen Islands; Southern Ocean; Antarc*; Antarctica
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.622.3434; http://plankt.oxfordjournals.org/content/20/7/1341.full.pdf

Abstract. Time series of phytoplankton biomass and taxonomic composition have been obtained for the 3 years 1992,1993 and 1994 in the northern part of the Southern Ocean (station Kerfix, 50°40'S, 68°25'E). Autotrophic biomass was low throughout the year (<0.2 mg m~3), except during a short period in summer when a maximum of 1.2 mg chlorophyll (Chi) a nr1 was reached. During winter, the integrated biomass was low (<10 mg m~2) and associated with deeply mixed water, whereas the high summer biomass (>20 mg m~2) was associated with increased water column stability. During summer blooms, the>10 um size fraction contributed 60 % to total integrated biomass. Large autotrophic dinoflagellates, mainly Prorocentrum spp., were associated with the summer phyto-plankton maxima and accounted for>80 % of the total autotroph carbon biomass. In November and December, the presence of the large heterotrophic dinoflagellates Protoperidinium spp. and Gyro-dinium spp. contributed a high proportion of total carbon biomass. During winter, the <10 um size fraction contributed 80 % of total Chi a biomass with domination of the picoplankton size fraction. The natural assemblage included mainly naked flagellates such as species of the Prasinophyceae, Cryptophyceae and Prymnesiophyceae. During spring, picocyanobacteria occurred in sub-surface water with a maximum abundance in September of 106 cells I"1.