Huot, Y. Dalhousie University, yhuot@raptor.ocean.dal.ca
Cullen, J. Dalhousie University, John.Cullen@dal.ca
Jeffrey, W. H. University of West Florida, wjeffrey@uwf.edu
Davis, R. F. Dalhousie University, Richard.Davis@dal.ca

 
A MODEL FOR DNA DAMAGE AND REPAIR IN BACTERIOPLANKTON AS INFLUENCED BY VERTICAL MIXING
 
Many effects of ultraviolet radiation (UV) on plankton have been described, as well as their potential consequences on biogeochemical cycling. Although the relative importance of these effects is unresolved, DNA damage seems to be the primary cause of microbial death by UV and should be quantified. We present a numerical model of UV-induced DNA damage (dimers per mega base pair) in bacterioplankton that includes two repair processes (photoreactivation and excision repair) and vertical mixing. Time- and depth-resolved DNA damage in the water column is generated using modeled solar irradiance and an advection-corrected random-walk model for mixing. Damage and photoreactivation are governed by different action spectra while the excision repair process is light-independent. We show that mixing will reduce the accumulation of damage in the water column. Modeled results are consistent with DNA dosimeters and measurements of dimer accumulation in situ and are also shown to support published qualitative descriptions of bacterial processes in surface layers as influenced by UV and mixing. The model is simple and versatile, and can be used to assess quantitatively the effects of colored dissolved organic matter and ozone depletion on DNA damage as well as on almost any irradiance-related process in the water column.
 
Day: Wednesday, Feb. 3
Time: 12:15 - 12:30pm
Location: Hilton of Santa Fe
 
Code: SS38WE1215H