Stratigraphic and Ecophysical Characterizations of Salt Pools: Dynamic Landforms of the Webhannet Salt Marsh, Wells, ME, USA

Abstract

Salt pools are water-filled depressions common to north-temperate salt marshes. In Wells, ME, USA, cores reveal a unique salt pool signature consisting of watersaturated dark-gray mud often containing fragments of Ruppia maritima. Cores through pool sediment reenter salt marsh peat, not tidal flat sediment, demonstrating that most pools are of secondary origin. A principal component analysis of attribute data collected from 119 pools defines three distinct pool types: those with (1) surrounding highmarsh vegetation and thick heavily undercut banks (40% of the variance), (2) surrounding low-marsh vegetation and thicker slightly undercut banks (18% of the variance), and (3) surrounding low-marsh vegetation and less thick moderately undercut banks, containing R. maritima and a surficial drainage (15% of the variance). Cores and spatiotemporal analyses of aerial photographs between 1962 and 2003 reveal dramatic salt marsh surface dynamism suggesting that salt pools influence the geomorphological evolution of coastal marshes.

Landscape Patterns of Forb Pannes Across a Northern New England Salt Marsh

“…Clustering of perennial forb pannes near pools reinforces the Miller and Egler (1950) observation about the concentric relationship between perennial forbs and pools. Our results reinforce their notion that the forces governing the occurrence of pools may also facilitate the formation of the perennial forb panne community, including ice plucking, snowpack, and dam collapse (Miller and Egler 1950;Chapman 1977;Wilson et al 2009). The association of forb patches along the river and creek edge reinforces previous explanations that disturbances from tidal flooding, including winter ice scouring and sand and sediment deposition may favor their establishment (Miller and Egler 1950;Redfield 1965;Dionne 1989;Ewanchuk and Bertness 2003;Argow 2006).…”

Probing the Origins and Stratigraphic Signature of Salt Pools from North-Temperate Marshes in Maine, U.S.A

“…Geologic cores collected through pool environments demonstrate similar results, revealing salt-marsh peats beneath pool deposits, thereby confirming a secondary origin (Collins, Collins, and Leopold, 1987;van Huissteden and van de Plassche, 1998). Recent work by Wilson et al (2009) that combines these two methods reveals that pools of the Webhannet Estuary, Wells, Maine are mostly secondary rather than primary landforms, but it is uncertain whether this is typical of the majority of pools located in other Maine salt marshes.…”

“…Salt pools, sometimes referred to as pans, pannes, or potholes, are shallow, water-filled depressions that are common features of many north-temperate salt marshes (Adamowicz and Roman, 2005;Dionne, 1968;MacDonald et al, 2010;Pethick, 1974;Redfield, 1972;Wilson et al, 2009). Debate surrounding salt-pool genesis focuses on whether pools are primary (Yapp, John, and Jones, 1917) or secondary (Redfield, 1972) features of salt marshes.…”

“…Analyses of a time-series of georeferenced aerial photographs will identify newly formed pools, indicating a secondary origin. Alternatively, analyses of geologic cores collected through pool environments will reveal their origin as either primary or secondary depending on whether tidal-flat sediment or saltmarsh peats (respectively) are found directly beneath the pool deposit (Wilson 2006;Wilson et al, 2009). Establishing the origin of salt pools is an important contribution to our understanding of surficial salt-marsh processes.…”

“…To date, the most detailed description of the salt-pool unit is by Wilson et al (2009). They describe pool sediment as a muddy material, dark gray in color, high in water content, and often containing fragments of the submerged aquatic plant Ruppia maritima.…”