Researcher(s)
- Mackenzie Hennessy, Marine Science, University of Delaware
Faculty Mentor(s)
- Sunita Shah-Walter, Marine Science, University of Delaware
Abstract
Dissolved organic carbon (DOC) plays a vital role in marine biogeochemical cycles, serving as a major reservoir for carbon in the ocean, and facilitating the dynamics of the microbial loop. While the DOC pool in marine environments is large and diverse, it can also be highly dynamic. Estuarine systems, such as the Delaware Bay and lower estuarine region of the Broadkill River, are nutrient-rich, highly-productive and have high concentrations of DOC. Phytoplankton-derived DOC fuels intense secondary production in the Delaware Bay, while terrestrial organic matter delivered from the upper Broadkill River also contributes the total DOC concentration, though likely with a different composition and lower bioavailability. Thus, the composition of DOC is likely to shift with the tides, reflecting shifts in the relative importance of these two organic matter sources. This study aims to characterize how DOC at the transition between the Broadkill River and Delaware Bay changes in response to the tidal shifts. In addition to DOC, we also isolate and describe a fraction of DOC using a recently-described cation exchange chromatography technique. This fraction is likely to be composed of small, polar molecules that are generally thought to be more labile and rapidly cycling than the total DOC reservoir. In this way we are able to characterize the dynamics of a sub-reservoir of DOC that is rarely described in estuarine systems.