Atmospheric CO2 levels are rising exponentially and may double from their current level of 360 ppm to 720 ppm in this century. Elevated levels of atmospheric CO2 directly affect plant metabolism, increasing photosynthetic and growth rates, and altering foliar chemistry. While extensive research has been conducted in terrestrial ecosystems, little is known about the potential effects in aquatic ecosystems. Because many small lakes and headwater streams rely heavily on terrestrially-derived leaf litter to fuel their food webs, elevated CO2-induced alterations in foliar chemistry could have potentially severe impacts in these ecosystems. The objectives of this study were threefold: 1) determine if the elevated CO2-induced effects that occur in green foliage are carried over to senesced leaf litter, 2) determine how CO2-altered leaf litter could affect in situ stream processes, and 3) determine how the feeding ecology of an aquatic detritivore could be altered when consuming CO2-enriched leaf litter.