The exchange of carbon, nitrogen, and phosphorus in dwarf and fringe mangroves of the oligotrophic southern everglades

Authors

Stephen Edwards Davis III, Florida International University

Document Type

Thesis

Degree

Doctor of Philosophy (PhD)

Major/Program

Biology

First Advisor's Name

Daniel Childers

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

Ronald Jones

Third Advisor's Name

Rudolf Jaffe

Fourth Advisor's Name

James Fourqurean

Fifth Advisor's Name

John Day

Date of Defense

7-21-1999

Abstract

Water management has altered both the natural timing and volume of freshwater delivered to Everglades National Park. This is especially true for Taylor Slough and the C - lll basin, as hypersaline events in Florida Bay have been linked to reduced freshwater flow in this area. In light of recent efforts to restore historical flows to the eastern Everglades, an understanding of the impact of this hydrologic shift is needed in order to predict the trajectory of restoration. I conducted a study to assess the importance of season, water chemistry, and hydrologic conditions on the exchange of nutrients in dwarf and fringe mangrove wetlands along Taylor Slough. I also performed mangrove leaf decomposition studies to determine the contribution of biotic and abiotic processes to mass loss, the effect of salinity and season on degradation rates, and the importance of this litter component as a rapid source of nutrients.

Dwarf mangrove wetlands consistently imported total nutrients (C, N, and P) and released N O ₂ + N O ₃', with enhanced release during the dry season. Ammonium flux shifted from uptake to release over the study period. Dissolved phosphate activity was difficult to discern in either wetland, as concentrations were often below detection limits. Fluxes of dissolved inorganic nitrogen in the fringe wetland were positively related to DIN concentrations. The opposite was found for total nitrogen in the fringe wetland. A dynamic budget revealed a net annual export of TN to Florida Bay that was highest during the wet season. Simulated increases and decreases in freshwater flow yielded reduced exports of TN to Florida Bay as a result of changes in subsystem and water flux characteristics. Finally, abiotic processes yielded substantial nutrient and mass losses from senesced leaves with little influence of salinity. Dwarf mangrove leaf litter appeared to be a considerable source of nutrients to the water column of this highly oligotrophic wetland. To summarize, nutrient dynamics at the subsystem level were sensitive to short-term changes in hydrologic and seasonal conditions. These findings suggest that increased freshwater flow has the potential to lead to long-term, system-level changes that may reach as far as eastern Florida Bay.

Identifier

FI14062214

Recommended Citation

Davis, Stephen Edwards III, "The exchange of carbon, nitrogen, and phosphorus in dwarf and fringe mangroves of the oligotrophic southern everglades" (1999). FIU Electronic Theses and Dissertations. 3012.
https://digitalcommons.fiu.edu/etd/3012