Project Title

Nitrogen Cycling in Seagrass Systems: Do Macroalgae alter Sediment Conditions?

Presenters

Academic department under which the project should be listed

CSM - Ecology, Evolution, and Organismal Biology

Faculty Sponsor Name

Troy Mutchler

The research does not involve human subjects.

Abstract (300 words maximum)

Anthropogenic nitrogen inputs in estuaries have been linked to eutrophication and global declines in seagrasses. Excess nitrogen can stimulate growth of macroalgae that shade seagrasses and change sediment chemistry. In particular, macroalgae blooms have been associated with decreased dissolved oxygen and increased concentrations of toxic hydrogen sulfide and dissolved inorganic nitrogen. These changes in sediment chemistry have the potential to affect the nitrogen cycle processes that determine whether nitrogen is recycled within the system or exported to the atmosphere. The objective of this research is to explore relationships between macroalgal biomass and physical and chemical sediment characteristics throughout St. Joseph Bay, FL. Porewater and exchangeable ammonium, porewater sulfide, organic matter, sediment grain size, and C:N content will be analyzed to look at sediment chemistry in areas with and without macroalgae cover. Comparisons will be made between sites to examine the effects of macroalgae and location within the bay. In addition, correlations will be used to detect relationships between the sediment characteristics and macroalgal biomass. These data will contribute to a broader study seeking to understand how macroalgae affect the fate of nitrogen inputs in St. Joseph Bay.

Project Type

Poster

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Nitrogen Cycling in Seagrass Systems: Do Macroalgae alter Sediment Conditions?

Anthropogenic nitrogen inputs in estuaries have been linked to eutrophication and global declines in seagrasses. Excess nitrogen can stimulate growth of macroalgae that shade seagrasses and change sediment chemistry. In particular, macroalgae blooms have been associated with decreased dissolved oxygen and increased concentrations of toxic hydrogen sulfide and dissolved inorganic nitrogen. These changes in sediment chemistry have the potential to affect the nitrogen cycle processes that determine whether nitrogen is recycled within the system or exported to the atmosphere. The objective of this research is to explore relationships between macroalgal biomass and physical and chemical sediment characteristics throughout St. Joseph Bay, FL. Porewater and exchangeable ammonium, porewater sulfide, organic matter, sediment grain size, and C:N content will be analyzed to look at sediment chemistry in areas with and without macroalgae cover. Comparisons will be made between sites to examine the effects of macroalgae and location within the bay. In addition, correlations will be used to detect relationships between the sediment characteristics and macroalgal biomass. These data will contribute to a broader study seeking to understand how macroalgae affect the fate of nitrogen inputs in St. Joseph Bay.