Light availability for Chlorobium phaeobacteroides development in Lake Kinneret

Abstract

The green sulfur bacterium Chlorobium phaeobacteroides forms a dense population in the oxygen-devoid layers of Lake Kinneret, Israel, from July throughout November. The typical vertical distribution of the species is characterized by a prominent peak at the center of the metalimnion, but the light available at that depth in Lake Kinneret is far below the values that enable maximal photosynthetic activity of C. phaeobacteroides. In this paper, we report on our findings regarding the characteristics of C. phaeobacteroides development in Lake Kinneret, both in space and time. We further quantified the available light in the metalinmion and suggest a model for the development of C. phaeobacteroides in the lake. Spatial analysis of C. phaeobacteroides suggest that a combination of diurnal north-west wind, diurnal oscillations of the metalimnion and the hours of sunlight result in a situation in which the metalimnion in some parts of the lake is exposed to slightly higher light intensities than the other parts of the lake, and therefore allows higher concentrations of C. phaeobacteroides to develop. The analysis of C. phaeobacteroides with time suggests that it can be described fairly well by the logistic growth model.