A survey of impounded salt marshes in southern Maine

Linnell, Steven
Michael Simpson, MS
Department of Environmental Studies
Roughly fifty percent of our coastal wetlands have been destroyed. Once thought of as wastelands to be filled or dredged for more “beneficial uses,” salt marshes are finally being recognized for their function in coastal food webs, most notably for their importance to fisheries. Many of the marshes still in existence have been negatively affected by human activity. A major cause of degradation is marsh impoundment and/or attenuation of tidal flow in marshes upstream of road crossings and other berms. This project looks at five different marsh sites in southern Maine and compares soilwater levels, soilwater salinities, relative elevations, soil saturation, and plant cover between the areas of marsh above and below tidal restriction. Water levels, salinities and elevations were all found to be lower in the upper or inland side of the marsh, while plant species diversity was found to be higher. These findings suggest that there is a measurable deleterious effect on the health of salt marshes located above road crossings due to inadequate tidal inundation.

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