Variation in Surface Sediment Deposition on Salt Marshes in the Bay of Fundy

Abstract

The purpose of this study is to document the magnitude and variability in surface sediment deposition in salt marshes along the New Brunswick coast of the Bay of Fundy. We measured the thickness of sediment accumulated over clay marker horizons for the period of one year. Sediments were sampled at seven sites from the head of the Bay to the outer Bay, distributed to span a gradient in tidal range (6-12 m). Within each marsh sample plots were located to control for relative elevation, distance from vegetated edge, and vegetation zone. Accumulated sediment was greater than 4 cm on some plots. Sediment accumulation generally decreases with relative elevation and distance from vegetated edge within marshes and increases with tidal range, which tends to co-vary with suspended sediment concentration. We conclude that changes in sediment supply will have the greatest impact on low marsh accretion while changes in sea level or marsh hydrology will be most important to high marsh accretion.