The Old Woman Creek National Estuarine Research Reserve, located in Erie county, Ohio at the edge of the Western Basin and the southern-most point on the Great Lakes, represents the only freshwater reserve in the NERRS program. Coastal managers and basic ecologists are both interested in developing a field-based management model that may be implemented by workers in the field and applied to various wetland settings. Knowledge of photosynthetic carbon flow rates are requisite for such modeling, since the products of photosynthesis determine the structure and function of higher tropic levels. Primary production measurements were conducted from June to October 1997. The 14C-bottle incubation method was used to measure Nelumbo lutea floating leaves, Potamageton pectinatus, epiphytes, and algal productivity. Water chemistry, solar illumination, percent cover, and water depth data allowed for the coversion of short-term rates into whole estuary values for individual dates and for the growing season. An estimation of annual production rates was determined from the growing season photosynthetic carbon budget. This allows the testing of the hypothesis that macrophytes and their attached epiflora and not phytoplankton, as previously believed, are the preeminent primary producer component in OWC.

Key words: Nelumbo lutea, Old Woman Creek, primary production