Temporal fluctuation of phytoplanktonic chlorophyll a and primary production in a turbid floodplain lake of the River Paraná (Argentina)

IZAGUIRRE, I.; O´FARRELL, I.

GAYANA. BOTANICA

EDICIONES UNIV

Año: 1999 vol. 56 p. 39 - 51

0016-5301

The seasonal pattern of vertical distribution of chlorophyll a and primary production was studied in a floodplain lake of the Lower Paraná River from May 1995 to May 1996. No stable stratification was observed during the study period for lake Montiel, a typical turbulent and shallow lake. Chlorophyll a mainly regulated by the hydrological regimne and by sseasonal changes in temperature and light, attained concentrations which exceeded 10 ug l-1 during late spring and early summer. severe dilution occurred during high water level periods while light limitation in the water column was observed for the driest periods due to sediment resuspension from the bottom. Gross primary production per unit area ranged from 0.114 gm-2h-1 to 1.235 gm-2h-1. In general, production sharply declined with depth because of light attenuation by suspended solids. Net production appeared to be limited by light penetration and by hydrological mechanisms which exerted a significant influence on the limnological parameters of the lake