Author(s): Aina Barcelona; Carolyn Oldham; Jordi Colomer; Jordi Garcia-Orellana; Teresa Serra

Linked Author(s): Teresa Serra

Keywords: seagrass meadows, waves, sediment transport, aquatic vegetation

Abstract: Seagrass meadows are known to enhance particle sedimentation. However, the impact of seagrasses in the vertical flux of sediment particles from allochtonous sources that reach a meadow is still unknown. This study aims to determine the amount of particles retained by a seagrass meadow. Different sinks of sediment particles will be considered to perform the budged of sediment particles. Likewise, the blades, the seabed, the within the canopy layer and the above the canopy layer will be considered the possible sinks of sediment particles. A set of laboratory experiments were conducted under different hydrodynamic conditions dominated by waves. This study demonstrates and quantifies that seagrass meadows decrease the volume of suspended sediment by two mechanisms: capturing the suspended sediment by the seagrass blades and promoting the particle sedimentation to the seabed. This study also demonstrates that the amount of sediment particles trapped by single seagrass blades decreases with canopy density. However, when considering the trapping by the total number of blades, the sediment captured by all the blades of the meadow increases with canopy density. Moreover, this study demonstrates that there is a decrease in the suspended particles within the canopy, especially in dense canopies, compared with the bare seabed, which implied an improvement in the water clarity. Therefore, dense canopies produce a positive feedback on the canopy itself. Furthermore, compared with the bare seabed, increasing the canopy density the particle sedimentation increases, making evident the contribution of the vegetation in enhancing sedimentation.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022SS799

Year: 2022