GranÚli, W. Lund University, Dept. of Ecology - Limnology, wilhelm.graneli@limnol.lu.se
Barbosa Anesio, A. Lund University, Dept. of Ecology - Limnology, Alexandre.Anesio@limnol.lu.se
Theil-Nielsen, J. Univ. Copenhagen, Freshwater Biological Laboratory,

 
BACTERIAL UTILIZATION OF DOM FROM DIVERSE PRIMARY PRODUCERS: EFFECTS OF UV RADIATION ON SUBSTRATE QUALITY
 
Bacterial response to photochemically modified dissolved organic matter (DOM) has received considerable interest in recent years. UV irradiation of DOM has been shown to produce both positive and negative effects on bacterial growth. Differences in bacterial response may be connected to the chemical composition of the source of DOM. We have tested this hypothesis using DOM leached from a variety of primary producers: phytoplankton, submerged macrophytes (Zostera, Chara and Myriophyllum), a macrophyte with floating leaves (Hydrocharis), two emergent macrophytes (Phragmites and Glyceria) and leaves from two terrestrial plants (Birch and Beech). DOM was extracted from dead algal/plant material, filter-sterilized and subjected to three treatments: irradiation with UV, with PAR or incubation in darkness. After irradiation a bacterial inoculum was added and the bacterial carrying capacity of the DOM was estimated through analyses of bacterial biomass accumulation, bacterial production and respiration. Contrary to what was expected DOM leached from primary producers with more structural tissue, e. g. emergent macrophytes, supported a higher bacterial biomass compared to some submerged macrophytes. Irradiation of the leachate caused both negative and positive effects on bacteria. There was a trend of irradiated DOM from structurally more complex primary producers having the strongest positive effect on bacteria.
 
Day: Thursday, Feb. 4
Time: 04:45 - 05:00pm
Location: Sweeney Center
 
Code: SS33TH0445S