INVESTIGATING THE SEDIMENT DYNAMICS OF NEW ENGLAND SALT MARSH POOLS AT REID STATE PARK, MAINE

Saltmarsh pools are shallow, sparsely vegetated depressions on the marsh platform that remain filled with salt water throughout the tidal cycle. Multiple studies have noted an increase in the number and area of pools in recent decades, with different authors attributing these changes to a variety of potential mechanisms. In order to better understand the origin and evolution of pools, and their role in the overall sediment dynamics of marsh platforms, we are studying the sedimentation of multiple pools and the surrounding marsh platform of the Little River saltmarsh in Reid State Park, Maine. Little River marsh was subjected to limited anthropogenic alteration relative to other marshes in the area and is characterized by one of the highest pool densities of any marsh in the region, with pools of varying morphologies and drainage connectivity.

In our research, we are utilizing dated sediment cores and seasonal sediment traps to examine pool evolution and how rates of sediment accumulation vary among pools and the surrounding marsh. In addition, we are using historical aerial imagery to track changes in pool abundance and geometry through time. For this research, we distinguish between “connected” and “disconnected” pools. “Connected” pools indicate late-life cycle pools that have been reconnected to the main channel network and drain for at least part of the tidal cycle, whereas “disconnected” pools adhere to the definition of “saltmarsh pool.” Despite regular sediment delivery and active accumulation on the surrounding marsh, both connected and disconnected pools presently appear to be settings of non-deposition and/or erosion. Analysis of historical imagery reveals little change in the geometry, distribution, and abundance of pools over at least the past five decades. These findings suggest that marsh pools at Little River are a persistent feature of the marsh system independent of past human modifications or recent increases in the rate of relative sea level rise.