Carbon Processing by Benthic and Pelagic Microbial Communities Under Changing Hydrologic Pulses and Presses in Coastal Wetlands

Authors

Kenneth James Anderson, Florida International UniversityFollow

Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Major/Program

Biology

First Advisor's Name

John Kominoski

First Advisor's Committee Title

Committee chair

Second Advisor's Name

Jay Sah

Second Advisor's Committee Title

Committee Member

Third Advisor's Name

Justin Campbell

Third Advisor's Committee Title

Committee Member

Fourth Advisor's Name

Evelyn Gaiser

Fourth Advisor's Committee Title

Committee Member

Fifth Advisor's Name

Christopher Osburn

Fifth Advisor's Committee Title

Committee Member

Keywords

Terrestrial and aquatic ecology

Date of Defense

6-30-2023

Abstract

Wetland ecosystems are rapidly changing as both climate change and human modifications alter their hydrology and biogeochemistry. Coastal wetlands are critical stores of carbon, and how hydrologic presses (e.g., sea-level rise, restoration) and pulses (storms, seasonality) interact to influence carbon cycling in coastal wetlands is uncertain. I investigated how changing nutrient concentrations, carbon sources, and water depths influence carbon cycling in wetlands of the Florida Coastal Everglades, which are both undergoing rapid freshwater restoration and saltwater intrusion from sea-level rise. First, I performed a reciprocal transplant of four dominant species of leaf litter across freshwater-to-marine gradients and showed that marine water is the most consistent driver of increasing litter breakdown across species. I then investigated how gene expression of microbial communities responds to dissolved and particulate chemistries to better understand the effects of seawater on litter breakdown and found a positive correlation between sulfate acquisition and seawater, especially in more anoxic environments. To understand the fate of carbon after litter breakdown, I collected data on the concentration vii and composition of dissolved organic matter from surface waters along wetland transects with higher and lower phosphorus enrichment receiving restorative fresh water. I found that dissolved organic matter in higher-phosphorus wetlands is becoming “greener” (decreasing in concentration and increasing in algal influence), while DOM in lower-phosphorus wetlands is becoming “browner” (increasing in concentration and in detrital influence). To better understand long-term drivers, I used twenty years of long-term data on the concentration and composition of dissolved organic matter across six sites spanning marsh, ecotone, and mangrove habitats in a lower- and a higher-productivity. I found that the higher-productivity Everglades marsh and mangroves are tightly controlled by changing water depths, but the lower-productivity marsh was not. This suggests that higher water depths suppress the production and dilute the fluxes of carbon in higher-productivity marshes; however, they import carbon to lower-productivity marshes and mobilize carbon within mangrove ecosystems. Overall, my research highlights how changes in hydrology and nutrients drivers carbon processing in coastal wetlands and provides a framework for predicting how these ecosystems will be altered by ongoing sea-level rise and restoration.

Identifier

FIDC011100

ORCID

0000-0002-1202-1453

Previously Published In

Anderson, K. J., J. S. Kominoski, A. Nocentini, and S. Hoffman. (2023). Dissolved organic matter in peat and marl marshes varies with nutrient enrichment and restored hydrology. Restoration Ecology 2023: e13905. https://doi.org/10.1111/rec.13905

Recommended Citation

Anderson, Kenneth James, "Carbon Processing by Benthic and Pelagic Microbial Communities Under Changing Hydrologic Pulses and Presses in Coastal Wetlands" (2023). FIU Electronic Theses and Dissertations. 5331.
https://digitalcommons.fiu.edu/etd/5331