Articles | Volume 9, issue 6
Hydrol. Earth Syst. Sci., 9, 707–720, 2005
https://doi.org/10.5194/hess-9-707-2005

Special issue: Water and chemical fluxes through catchments

Hydrol. Earth Syst. Sci., 9, 707–720, 2005
https://doi.org/10.5194/hess-9-707-2005

  31 Dec 2005

31 Dec 2005

Light limitation of primary production in high latitude reservoirs

J. Sahlberg1 and L. Rahm2 J. Sahlberg and L. Rahm
  • 1Swedish Meteorological and Hydrological Institute, S-601 76 Norrkoping, Sweden
  • 2Department of Water and Environmental Studies, Linkoping University, S-581 83, Linkoping, Sweden

Abstract. 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-ε 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.