Marsh Mat Flotation in the Louisiana Delta Plain

Abstract

Vertical mat movement in relation to surface-water fluctuations was measured for 1 year at three marshes differing in dominant emergent vegetation and location in the Mississippi River delta plain of coastal Louisiana, U.S.A.. The freshwater marsh, dominated by Panicum hemitomon, floated directly with ambient water levels, provided they were high enough to float the mat. Water levels varied by c. 70 cm and mat movement by 55 cm. An intermediate-salinity marsh closer to the Gulf of Mexico and dominated by Sagittaria falcata moved 35 cm vertically during the study period, and water levels moved 70 cm. A brackish marsh, dominated by Spartina patens, moved only 3 cm in response to c. 40 cm of vertical water movement (...)