The aim of the study is to determine the effect of UV-B on the microbial, and in particular, on the bacterial community over a wide range of aquatic systems. Main focus will be put on the interaction between dissolved organic matter (DOM) and the bacterial consortia responsible for processing this DOM and its modification due to UV-B radiation. Additional measurements on phytoplankton primary production and extracellular release as influenced by UV-B radiation should allow us to estimate the influence of UV-B radiation on the carbon and energy flux through the microbial loop in representative European waters.
UV-B penetration into the water column and the response of the microbial community to UV-B will be assessed in a variety of different European waters ranging from humic acid-rich Nordic to high altitude, oligotrophic Alpine lakes to mesotrophic lakes. These data will be compared to oligotrophic and eutrophic marine situations (Adriatic Sea). UV-B penetration into the water column will be correlated with the concentration of dissolved organic carbon (DOC) and with humic acids.
The photolytic activity of UV-B on dissolved organic matter (DOM) will be evaluated and the availability of this UV-B processed DOM to bacterial consortia compared with unprocessed DOM. The influence of UV-B on bacterial production, growth yield and respiration will be examined and the role of UV-A in activating photorepair mechanisms tested using bacteria previously exposed to UV-B (from surface waters) and from below thermocline waters (assumed not exposed to UV-B).
In mesocosm experiments the role of UV-B on the carbon and energy flux through the microbial loop will be examined. These experiments involve investigations and measurements on phytoplankton composition, phytoplankton primary production and extracellular release, bacterial production and flagellate grazing.
Funding SchemeCSC - Cost-sharing contracts
223 62 Lund