A study of the diatom-dominated microplankton summer assemblages in coastal waters from Terre Adélie to the Mertz Glacier, East Antarctica (139°E–145°E)

in Polar Biology (2008), 31(9), 1101-1117

In January 2004 the microplankton community from the coastal waters of Terre Adélie and Georges V Land (139°E - 145°E) was studied. Results showed a diatom-dominated bloom with chlorophyll a levels ... [more ▼]

In January 2004 the microplankton community from the coastal waters of Terre Adélie and Georges V Land (139°E - 145°E) was studied. Results showed a diatom-dominated bloom with chlorophyll a levels averaging 0.64 µg.l-1 at 5m depth (range 0.21 - 1.57 µg.l-1). Three geographic assemblages of diatoms were identified, based on principal diatom taxa abundances. The stratified waters near the Mertz Glacier presented highest phytoplankton biomasses (0.28 - 1.57 µg Chl a.l-1 at 5m) and diatom abundances (6 507 - 70 274 cells.l-1 at 5m), but low diversity, dominated by Fragilariopsis spp. Lower biomasses (0.38 – 0.94 µg Chl a.l-1 at 5m) and abundances (394 – 9 058 cells.l-1 at 5m) were observed in the mixed waters around the Astrolabe Glacier with a diverse diatom community characterised by larger species Corethron pennatum and Rhizosolenia spp. Finally an intermediate zone between them over the shallower shelf waters of the Adélie Bank represented by Chaetoceros criophilus, where biomasses (0.21 - 0.35 µg Chl a.l-1 at 5m) and abundances (1 190 - 5 431 cells.l-1 at 5m) were lowest, coinciding with the presence of abundant herbivorous zooplankton. [less ▲]

Combined lipid, fatty acid and digestive tract content analyses: a penetrating approach to estimate feeding modes of Antarctic amphipods

in Polar Biology (2001), 24

Seasonal changes of pCO(2) over a subantarctic Macrocystis kelp bed

in Polar Biology (2000), 23(10), 706-716

The partial pressure of carbon dioxide (pCO(2)), calculated from pH and total alkalinity measurements. was monitored together with chlorophyll a and bacterioplankton biomass in shallow coastal water ... [more ▼]

The partial pressure of carbon dioxide (pCO(2)), calculated from pH and total alkalinity measurements. was monitored together with chlorophyll a and bacterioplankton biomass in shallow coastal water located inside and outside a giant kelp bed (Macrocystis pyrifera) situated in the Kerguelen Archipelago, Southern Ocean. In spite of large changes over a short time-scale pCO(2) variations over the year are large and exhibit a seasonal pattern in which the different stages of the annual biological turnover are well marked. The overall pattern of pCO(2) variations is related to biological activity (development of both photosynthesis and respiration) during almost the whole year. However, physical and thermodynamical constraints exert a strong influence on pCO(2) at meso time-scale (10 days) and/or when biological activity is weak. Macrocystis acts to maintain pCO(2) below saturation almost the whole year and large undersaturations (pCO(2) as low as 20 mu atm) were observed within the kelp bed. Furthermore, primary production of Macrocystis covers a period of 8 similar to 9 months a year from winter to late summer and the kelp bed seems to favour the spring phytoplanktonic bloom. The buffer factor beta indicates that, outside the kelp bed, inorganic carbon dynamics are mainly influenced by air-sea exchange and photosynthesis without calcification. Inside the kelp bed. beta suggests calcification by the epiphytic community. [less ▲]