Changes in visible region (400--700 nm) absorption spectra of chromophoric dissolved organic matter (CDOM) resulting from natural photobleaching have not been well characterized in aquatic systems. Photobleaching of CDOM absorption and the resultant changes in the exponential spectral slope in the visible domain are documented in a coastal fjord. Measurements of spectral CDOM absorption were made with a WET Labs ac-9 in situ and in surface water incubated in UV-transparent Tedlar bags at 1 m for 6 days. The exponential slope of the absorption spectrum between 412--560 nm increased as a function of radiation dosage in the first 72 h of the incubations. Higher spectral slope values were observed in surface waters relative to bottom waters, in agreement with our experimental results. The extent to which a CDOM absorption spectrum altered by photobleaching can serve as a signature of the process itself, containing information about absorption loss, was investigated. From these observations, we propose that higher spectral slopes typically associated with oceanic CDOM relative to coastal CDOM may be due to increased cumulative photobleaching as opposed to a shift in the spectral signature of CDOM sources as has been hypothesized.