Dynamics of chromophoric dissolved organic matter and dissolved organic carbon in experimental mesocosms

Since CDOM can significantly influence the optical characteristics of Case II waters, we investigated potential sources of CDOM and DOC during a month-long mesocosm experiment. Nutrient additions resulted in a large phytoplankton bloom, followed by a rapid decline. Despite this, DOC and CDOM increased slowly and linearlyand were onlyweakly correlated with Chl a. However, there were stronger correlations between CDOM and bacteria, and sedimentary CDOM fluxes varied from 0 to a value large enough to explain the increase of CDOM in the tanks. These results suggest that bacteria and sediments may be more important in CDOM production than phytoplankton on this time scale.