Coastal wetlands perform essential ecosystem functions that may be negatively impacted by anthropogenic activities and environmental change. Coastal wetland degradation has been observed in the Tolomato River estuary, part of the Guana Tolomato Matanzas National Estuarine Research Reserve (GTMNERR), on the east coast of Florida (USA). In some areas, oyster rakes (linear piles of dead oyster shells) form between the river and the tidal wetlands, likely due to boat wakes and sea level rise. While some portions of marsh have well consolidated soil (i.e., “stable”), others have reduced plant vigor and unconsolidated soils (i.e., “unstable”). This study quantified how soil biogeochemical properties differed between stable and unstable marsh soils from 4 different sites. Results indicated ammonium and sulfide concentrations averaged 64% and 28% higher in unstable soils than stable, respectively. Organic matter content, total carbon, total nitrogen, and POXC were all 10-15% greater in stable soils. A complementary intact soil core experiment was also conducted to quantify the impact of nutrient addition on soil denitrification, potential mineralizable nitrogen, methane, and carbon dioxide rates in end-member examples of stable and unstable soils. Unstable soil had 67% higher denitrification and 51% lower in situ CO2, with nutrient addition, while stable soil denitrification was 58% lower in the Nutrient treatment. Our findings suggest land managers can use visual cues of marsh stability to rapidly assess plant and soil physicochemical properties, allowing for informed decision making regarding the need for protection and restoration.
Jennifer Volk
Dr. Lisa Chambers, Advisor
Read More