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Hydrology and Earth System Sciences Discussions 9, 6 (2005) 707-720
Light limitation of primary production in high latitude reservoirs
J. Sahlberg 1, L. Rahm 2

To explore the effects of vertical mixing on the primary production in a northern reservoir, a Lagrangian particle dispersion model was coupled to a 1-D reservoir model where the vertical mixing was calculated using a k-? model together with an empirically-based deep-water eddy viscosity. The primary production of each phytoplankton cell is assumed to be a function of the ambient light and not to be nutrient limited. The photoadaption follows first-order kinetics where the photoadaptive variables, a, b, and Pm, describe the coefficients of the photosynthesis-irradiance curve. The model is applied to the northern reservoir Akkajaure, which is strongly regulated with a mean and maximum depth of 30 m and 100 m respectively. Based on the release of 1000 particles (plankton), the model calculated the mean primary production of each plankton, during four different growing seasons. Vertical mixing has a substantial effect on the vertical distribution of phytoplankton and, thus, on the primary production in a reservoir. It was found that primary production was greater in a cold summer with weak stratification than in a warm summer when the reservoir was more stratified.
1 :  Sveriges Meteorologiska och Hydrologiska Institut
Sveriges Meteorologiska och Hydrologiska Institut
2 :  Department of Water and Environmental Studies
Linkoping University
Planète et Univers/Interfaces continentales, environnement

Planète et Univers/Océan, Atmosphère

Planète et Univers/Sciences de la Terre
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