Repair by photoreactivation involves the binding of a repair enzyme (photolyase) to a damaged strand of DNA, absorption of a photon of UV-A or blue light (380-450nm) by the bound enzyme, and subsequent utilization of the absorbed energy to repair the DNA damage. On the other hand, dark repair involves the recognition of structural distortions of DNA, excision of the damaged region, and resynthesis of the excised area using the undamaged strand as the template;

p.210; in ....
Moran M.A., Zepp R.G.; 2000; UV Radiation Effects on Microbes and Microbial Processes; in Kirchman D.L. (ed); Microbial Ecology of the Oceans; Willey-Liss Inc.; New York USA;