Temporal and vertical variation of chlorophyll a concentration, phytoplankton photosynthetic activity and light attenuation in Lake Kinneret: Possibilities and limitations for simulation by remote sensing

Abstract

The relationship between chlorophyll a (Chl a) and primary productivity (PP) in the uppermost water layer and the water column-based (0-15 m) integral values of those variables were examined using measurements taken in Lake Kinneret (Israel) from 1990 to 2003. In 81% of all Chl a profiles examined, the distribution was fairly uniform within the entire 0-15 m water column, and 12.3% of instances showed a prominent subsurface maximum, when the lake phytoplankton was dominated by the dinoflagellate Peridinium gatunense. Chl a can be reliably estimated by remote sensing techniques in the productive and turbid water of Lake Kinneret, since Chl a concentration at surface layers can be extrapolated to the entire water column. Light vertical attenuation coefficient average for wavelengths from 400 to 700 nm, Kd, ranged from 0.203 to 1.954 m -1 and showed high degree of temporal variation. The maximal rate of photosynthetic efficiency, PBopt [average 3.16 (±1.50)], ranged from 0.25 to 8.85 mg C m-3 h-1 mg Chl a-1. Using measured data of Chl a, PBopt, and light as an input, a simple depth-integrated PP model allowed plausible simulation of PP. However, a lack of correlation between photosynthetic activity and temperature (or other variable with remotely sensed potential) renders the use of models that require input of photosynthetic efficiency to calculate integrated PP of little value in the case of productive and turbid Lake Kinneret. © The Author 2006. Published by Oxford University Press. All rights reserved.