Primary production, light and vertical mixing in Potter Cove, a shallow coastal Antarctic environment.

SCHLOSS, I.R., G.A. FERREYRA

POLAR BIOLOGY

Año: 2002 p. 41 - 48

0722-4060

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-in-duced turbulent mixing was quanti®ed by means of the root-mean square expected vertical displacement depth of cells in the watercolumn, Zt. The light attenuation coecient was used as a measure of the in¯uence 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 forthe inner and outer cove, respectively. Obvious di.erences between photosynthetic capacity [P*max; averages 2.6 and 0.6 lgC (lg chlorophyll-a)±1 h±1] and photosyn­thetic eciency {a*; 0.073 and 0.0018 lgC (lg chlo- ±1 ±1)±1 rophyll-a)±1 [(lmol m±2 s ]} values were obtained forboth sites dur ing low mixing conditions (Zt from 10 to 20 m), while no di.erences were found forhigh mixing situations (Zt>20 m). This suggests di.erent photoacclimation of phytoplankton responses, induced by modi®cations of the light ®eld, 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.