Seasonal variation and biological effects on mudflat erodibility in the Minas Basin, Bay of Fundy

Abstract

The goal of this study was to investigate the effects of intertidal mudflat biofilms on sediment erosion in the Minas Basin of the Bay of Fundy, Canada. From April through November 2012, sediment cores were collected biweekly and eroded using a Gust micro- cosm. Half of the cores were eroded without undergoing prior treatment, while the other half were treated with bleach prior to erosion to destroy biofilms. Size-specific sediment retention by biofilms was evaluated by comparing the disaggregated inorganic grain size (DIGS) distributions of sediment resuspended from untreated and treated cores, while seasonal variation in natural sediment erodibility was assessed by focusing on the mass eroded from untreated cores only. Results show that biofilms preferentially retained clays and very fine silts (< 10 μm), and that overall sediment erodibility decreased from spring to fall. Results also indicate that abundance of the infaunal amphipod Corophium volutator and rainfall increased sediment erodibility.