Mengesha S., Dehairs F., Fiala M., Elskens M. & Goeyens L. (1998). Seasonal variation of phytoplankton community structure and nitrogen uptake regime in the Indian sector of the southern ocean. Polar Biol., 20(4), 259–272.
Abstract: This study investigates the dynamics of phytoplankton communities and nitrogen uptake in the Indian sector of the Southern Ocean during spring and summer. The study area is oligotrophic (Chl a stocks < 50 mg m-2); nevertheless, a large spatial variation of phytoplankton biomass and community structure was observed. During both seasons the phytoplankton community in the seasonal ice zone showed higher biomasses and was mainly composed of large diatom cells. However, in the permanently open ocean zone the community had low biomass and was chiefly composed of nano- and picoflagellates. In the polar front zone, although biomass was higher, the community structure was similar to the open ocean zone. The results suggest that the variation in phytoplankton community structure on a larger scale resonates with gradients in water column stability and nutrient distribution. However, significant changes in biomass and nutrient stocks but little change in community structure were observed. Absolute nitrogen uptake rates were generally low, but their seasonal variations were highly significant. During spring the communities displayed high specific nitrate uptake (mean rate = 0.0048 h-1). and diatoms (in the seasonal ice zone) as well as nano- and picoflagellates (in the permanently open ocean zone and polar front zone) were mainly based on new production (mean f-ratio = 0.69). The transition to summer was accompanied by a significant reduction in nitrate uptake rate (0.0048 h-1 ? 0.0011 h-1) and a shift from predominantly new to regenerated production (f-ratio 0.69 ? 0.39). Ammonium played a major role in the seasonal dynamics of phytoplankton nutrition. The results emphasize that, despite a large contrast in community structure, the seasonal dynamics of the nitrogen uptake regime and phytoplankton community structure in all three subsystems were similar. Additionally, this study supports our previous conclusion that the seasonal shift in nitrogen uptake regime can occur with, as well as without, marked changes in community structure.
Keywords: Seasonal variation ; Phytoplankton ; Biomass ; Plant community ; Nitrogen cycle ; Absorption ; Southern Ocean ; Indian Ocean ; Algae ; Community structure ; Marine environment ; Thallophyta
Programme: 193
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Gauthier-Clerc M., Le Maho Y., Gendner J.P. & Handrich Y. (2002). Moulting fast and time constraint for reproduction in the king penguin. Polar Biol., 25, 288–295.
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. (2002). Serological survey of King penguin Aptenodytes patagonicus in Crozt archipelago for antibodies to infectious bursal disease, influenza A and Newcastle disease viruses. Polar Biol., 25, 316–319.
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Delettre Y.R.D., Frenot Y., Vernon P. & Chown S.L. (2003). First record of Telmatogeton sp. (Diptera: Chironomidae) at Heard Island. Polar Biol., 26, 423–426.
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Gauthier-Clerc M., Mangin S., Le Bohec C., Gendner J.P. & Le Maho Y. (2003). Comparison of behaviour, body mass, haematocrit level, site fedelity and survival between infested and non-infested king penguin Aptenodytes patagonicus by ticks Ixodes uriae. Polar Biol., 26, 379–382.
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Weimerskirch H., Chastel O., Cherel Y., Henden J.A. & Tveraa T. (2001). Polar Biol., 24, 83–88.
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Lea M.A., Hindell M., Guinet C. & Goldsworthy S. (2002). Variability in the diving activity of Antarctic fur seals, Arctocephalus gazella, at Iles Kerguelen. Polar Biol., 25, 269–279.
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Jouventin P., Bried J. & Micol T. (2003). Insular bird populations can be saved from rats : a long-term experimental study of white-chinned petrels Procellaria aequinoctialis on Ile de la Possession (Crozet archipelago). Polar Biol., 26, 371–378.
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Le Bohec C., Gauthier Clerc M., Gendner J.P., Chatelain N. & Le Maho Y. (2003). Nocturnal predation of king penguins by giant petrels on Crozet islands. Polar Biol., 26, 587–590.
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Thouzeau C., Froget G., Monteil H., Le Maho Y. & Harf Monteil C. (2003). Evidence of stress in bacteria associated with long-term preservation of food in the stomach of incubating king penguins (Aptenodytes patagonicus). Polar Biol., 26, 115–123.
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