Date Thesis Awarded


Access Type

Honors Thesis -- Access Restricted On-Campus Only

Degree Name

Bachelors of Science (BS)




Matthew Kirwan

Committee Members

Gregory Hancock

Randolph Chambers

Rebecca Jiron


Many saltmarshes throughout the world are converting to open water through the development and expansion of ponds. High rates of relative sea level rise are leading to widespread marsh submergence and ponding in the 28,000-acre microtidal Blackwater National Wildlife Refuge (Maryland, USA), but knowledge of the mechanisms involved is limited. Here, we use historic aerial imagery and field-based measurements to quantify pond development and identify the processes involved. Historical photograph analyses indicates that many small ponds emerge on the marsh platform and quickly merge with other nearby ponds, slowing their growth rates with size. A consistent rate of marsh loss in each study area suggests biogeochemical mechanisms such as organic matter decomposition drive pond expansion. Biomass, porewater chemistry, and soil strength measurements from marshes adjacent to stable and unstable ponds suggest pond growth rates are related to surrounding marsh health. Finally, this study finds that the merging of small, unstable ponds rather than the continued singular expansion of large ponds is the primary driver of pond expansion in the Blackwater marshes. .

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