Surface water samples were collected monthly from a site beyond the mouth of the Delaware Bay (38° 50.935' N, 75° 06.456' W) The carbon cycle and other biogeochemical processes in the oceans were thought to be controlled nearly entirely by two types of marine microbes: 1) phototrophs - microbes which, like plants, synthesize organic material using CO2 and other plant nutrients while producing oxygen; and 2) heterotrophs - microbes which, like animals, oxidize organic material back to CO2 and other plant nutrients while using oxygen. Recent studies using molecular approaches have discovered some novel microbes--photoheterotrophs--that combine phototrophy with heterotrophy. Photoheterotrophy would fundamentally alter our understanding of the carbon cycle and other biogeochemical processes in aquatic ecosystems. p This project addresses questions about the diversity, abundance, and activity of photoheterotrophic microbes in the Mid-Atlantic Bight.