The Sensitivity of the Ebb Dominance in Tidal Creeks of a Microtidal Mangrove Forest

Abstract Tidal creeks in mangrove forests dissect the mangrove-vegetated forest platforms. Due to the difference in resistance to tidal flows between the mangrove-vegetated platform and the tidal creeks, tidal flows in tidal creeks are typically ebb-dominant. As a result, tidal creeks maintain their depth by the net export of sediments. However, with small tidal ranges, the ebb-dominance of tidal creeks may be smaller and their self-scouring may fall short, possibly resulting in net accretion in the creeks when excess sediment is available. In this study, we performed field measurements to quantify tidal flow velocities through tidal creeks of a microtidal mangrove forest in Bonaire, a small island in the Caribbean Netherlands. We found that the ebb-dominance of the tidal creeks was sensitive to spatial variations in the mangrove forest resistance as well as to temporal variations in tidal range on spring-neap tidal timescales. These findings imply that tidal creeks in microtidal mangroves are not necessarily ebb-dominant, and this may enhance their susceptibility to sediment infilling, the clogging of creeks and the resulting degradation of mangrove forests.