I have a broad interest in aquatic ecosystem ecology but the consistent underlying theme of my research has been investigations into the role of dissolved organic carbon (DOC) in freshwater ecosystems. Dissolved organic carbon is widely recognized to be a major structuring agent of aquatic ecosystems, having a profound influence on the transparency, heat budget, water column stability, pH, and metabolism of lakes. My work has encompassed 3 broad areas related to DOC and lakes: 1) aquatic ecosystem productivity, 2) aquatic ecosystem optics, and 3) photolytic transformation of DOC. Much of my scholarly work is collaborative in nature, being conducted with multidisciplinary teams of scientists. My role in these collaborative projects typically relies on my expertise in the area of DOC composition and dynamics or my expertise in the role of DOC in structuring optical properties of aquatic ecosystems. An additional role for me in many of these collaborative projects is in the quantifying and characterizing (either chemically or optically) DOC, for which my laboratory is uniquely suited.