UCLA

Vertical accretion, the aggregation of material on a wetland surface, depends on organic matter accumulation and mineral sedimentation. We measured suspended sediment concentrations by total suspended solids (TSS), sediment deposition and vertical accretion rates in four marsh zones in the central basin of Mugu Lagoon, a salt marsh dominated by Salicornia pacifica. Mean TSS was 21±1 mg l^-1 (Mean±SE) between February and May 2012, which is within the middle of the range of other salt marshes. Mean sediment deposition ranged from 0.00 g m^-2 day^-1 to 1.29 g m^-2 day^-1, which is in the low end of the range of other salt marshes. No net vertical accretion was observed between August 2011 and May 2012. Our results indicate that for high and high-mid marsh zones, sedimentation was highest adjacent to the creek. Interestingly, organic matter concentration in TSS varied with tide height, but mineral content did not. While more data are needed to confirm whether these trends occur over longer time periods, our study is one of the first to characterize spatial and temporal variation in sediment dynamics for a salt marsh dominated by Salicornia species.