Estimation of the phytoplankton productivity in three Estonian lakes

Abstract

Diurnal variation of the underwater quantum irradiance, the corresponding primary production profiles, and the integral primary production values were estimated by model calculations in three Estonian lakes (Peipsi, Võrtsjärv, and Harku) for 12 days in the summers of 2007 and 2008. In parallel, in situ measurements of primary production were carried out and the main bio-optical parameters of the water were determined. The concordance of the measured and modelled production profiles was satisfactory. Our results show that a model in which the initial data are daily variation of incoming irradiance in the PAR region combined with episodic measurements of chlorophyll a concentration and diffuse attenuation coefficient in the water is suitable for estimating variation of primary production in lakes.