Primary production, light and vertical mixing in Potter Cove, a shallow bay in the maritime Antarctic |
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Authors: | Irene R. Schloss Gustavo A. Ferreyra |
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Affiliation: | Instituto Antártico Argentino, Cerrito 1248 (C1010AAZ) Buenos Aires, Argentina,
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Abstract: | Phytoplankton photosynthesis was measured during spring-summer 1991-1992 in the inner and outer part of the shallow Potter Cove, King George Island. Strong winds characterise this area. Wind-induced turbulent mixing was quantified by means of the root-mean square expected vertical displacement depth of cells in the water column, Zt. The light attenuation coefficient was used as a measure of the influence of the large amount of terrigenous particles usually present in the water column; 1% light penetration ranged between 30 and 9 m, and between 30 and 15 m for the inner and outer cove, respectively. Obvious differences between photosynthetic capacity [P*max; averages 2.6 and 0.6 µg C (µg chlorophyll-a)-1 h-1] and photosynthetic efficiency {!*; 0.073 and 0.0018 µg C (µg chlorophyll-a)-1 h-1 [(µmol m-2 s-1)-1]} values were obtained for both sites during low mixing conditions (Zt from 10 to 20 m), while no differences were found for high mixing situations (Zt>20 m). This suggests different photoacclimation of phytoplankton responses, induced by modifications of the light field, which in turn are controlled by physical forcing. Our results suggest that although in experimental work P*max can be high, wind-induced mixing and low irradiance will prevent profuse phytoplankton development in the area. |
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