17 Nearshore and Estuarine Research: Dynamics and Future Resiliency in the Coastal Zone

This session focuses on drivers of change in coastal environments as well as planning for future resiliency in tidal marshes, mudflats, estuaries, and barrier systems, including human activity impacts, sea level rise, & changing sediment supply.

Monday, 23 March 2026
8:00 AM - 12:00 PM
CCC, Room 22/23

Investigating Salt Marsh Conditions of the Past, Present, and Future: Contributions Towards Restoration Efforts

Paper number: 17-1
Program: Technical Sessions
Time: 8:05 AM – 8:25 AM

Authors

Abstract

This research explores the long-term impacts of colonial-era modifications on the Cousins River marsh in Yarmouth and Freeport, Maine. Due to intricate levying systems and ditches implemented in early agricultural practices, the marsh remains flooded for prolonged periods following a 2010 increase in Mean High Water, leading to an increased loss of vegetated habitat. Restoration efforts to remediate high marsh pooling are in development and this project intends to compile monitoring results to inform these efforts. A collaborative approach is utilized with partners from academic, non-profit, municipal, state, and federal agencies united around effective marsh conservation.

Sedimentation rates calculated through isotopic and stratigraphic analysis reveal 275 years of accumulation trends highlighting effective proxies for elucidating chronological horizons within sedimentary records. Key changes in biodiversity delineate periods of Indigenous settlement, colonization, and agricultural evolution. Coprophilous spores are utilized as an indicator of livestock presence on the marsh and the transition to more extensive epochs of diking during hay harvesting periods as livestock agriculture moved inland. Marsh evolution from pre-colonization to present day is highlighted by transitions in pollen concentrations of Spartina alterniflora demonstrating lower elevation to Spartina patens marking the transition to a higher elevation marsh platform.

Remotely sensed water, quantified through time series of Modified Normalized Difference Water Index, and trends in tide gauge records provide necessary context for restoration efforts and insight into the observed 19 year nodal cycle. Time series of Mean High Water and Mean Sea Level help to demonstrate the current state of the marsh system and the opportunity for effective restoration due to a recent decrease in Mean High Water.

Sediment accumulation trends acquired through sediment traps generate models for minerogenic, vertical accretion vital to the marshes ability to keep pace with sea level rise. Modern sedimentation as a function of elevation is explored to delineate environmental and elevation conditions of time periods relevant to the Cousins River marsh. These trends in sedimentation as a function of elevation are explored relative to tidal datums and highlight the close relationship between tidal inundation frequency and sediment accumulation. The importance of vegetation's ability to trap sediment is demonstrated, further emphasizing the need to restore megapool conditions.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2

doi: 10.1130/abs/2026NE-411156

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