Graduation Year

2025

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Geosciences

Major Professor

Joseph M. Smoak, Ph.D.

Committee Member

Philip Van Beynen, Ph.D.

Committee Member

Ryan P. Moyer, Ph.D.

Keywords

Clam Bay, organic carbon, soil cores, tidal gauge, urbanization

Abstract

The ability of mangrove soils to accrete at a rate that keeps up with the rate of sea-level rise (SLR) is widely debated, especially for soils impacted by variations in influxes of nutrients and alterations in natural flows of water from surrounding urban areas. This study aimed to evaluate the influence of SLR on mangrove soils in Clam Bay (Naples, Florida, USA), which has an extensive system of mangroves that have faced increasing human pressure in recent decades as well as SLR. Cores were collected from two different sites within Clam Bay to identify differences in soil accretion, mass accumulation, and organic carbon accumulation rates in relation to differing hydrological impacts at those sites resulting from human development. Pb-210 dating was used to determine ages of sample intervals and apply rates. Accretion rates have increased by about 78% when comparing the 100-yr mean and 10-yr mean between the two sites studied. Mass accumulation rates and OC accumulation rates of the cores have increased as well, by about 77% and 88% respectively. The 100-yr mean OC accumulation rate was 100 g m-2 yr-1 between both sites, while the 10-yr mean OC accumulation rate was 188 g m-2 yr-1.The results indicate sites that are impacted through significant hydrological alterations have lower accretion rates than sites that maintain their historical hydrological patterns, putting them at greater risk of loss by threats such as SLR. When accretion rates for the most recent 10-yr mean are compared to rates of SLR, the hydrologically impacted site had a 3.93 mm yr-1 deficit versus 3.07 mm yr-1 deficit at the non-impacted site. As such, accretion rates in Clam Bay are unlikely to keep up with current or projected future rates of SLR, especially for the hydrologically impacted site leading to the potential for ecosystem collapse to occur in the near future.

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