Research station at Lake Dagow, about 100 km north of Berlin,
Germany. The small station consists of four mesocosms.
Actually, each mesocosm is a meshed enclosure which are immersed
down to several meter of depth and are used for scientific experiments.
Anoxygenic phototrophic bacteria |
Some fresh water lakes like Lake Dagow undergo a so-called summer stratification. The sunlight heats up the upper part of the water column what results in a thermic stratification and thus preventing the mixing of both water layers.
In nutrient-rich but not deep lakes, oxygen can be consumed completely at the bottom layer. If sunlight reaches this anoxic part of the water, anoxygenic phototrophic bacteria (including red, green or brownisch sulfurbacteria) are able to evolve.