Hitchhiking halophytes in wrack and sediment-laden ice blocks contribute to tidal marsh development in the Upper Bay of Fundy

• Published in: Wetlands ecology and management 2022-04, Vol.30 (2), p.375-388
• Main Authors: Rabinowitz, Tasha R. M., Greene, Lyndsay, Glogowski, Alisha D., Bowron, Tony, van Proosdij, Danika, Lundholm, Jeremy T.
• Format: Article
• Language: English
• Subjects: Accretion; Barren lands; Biomedical and Life Sciences; Coastal inlets; Coastal processes; Colonization; Conservation Biology/Ecology; Deposition; Environmental Law/Policy/Ecojustice; Freshwater & Marine Ecology; Germination; Halophytes; Hydrology/Water Resources; Ice; Life Sciences; Marine & Freshwater Sciences; Original Paper; Plant debris; Propagules; Restoration; Salt marshes; Saltmarshes; Sediment; Sediment density; Sediments; Soil; Soil erosion; Tidal marshes; Vegetation; Water Quality/Water Pollution; Wetlands
• ISSN: 0923-4861; 1572-9834
• DOI: 10.1007/s11273-022-09867-3

Salt marshes are a type of coastal wetland that are affected by dynamic coastal processes. Ice blocks and wrack (mats of plant debris) regularly float onto northern marshes and become stranded, affecting vegetation and soil accretion. There is little research regarding the capacity of ice and wrack to transport viable plant propagules onto marshes where they can colonize, which may be particularly important at barren new salt marsh restoration sites. Contributions of sediment by ice may also be important to raise the marsh platform to elevations appropriate for plant colonization. We collected ice ( n  = 27) and wrack ( n  = 18) samples at marshes in the Bay of Fundy, ran germination trials with the contents, and measured the quantity of sediment in the ice. We found viable propagules from halophytic and non-halophytic species in wrack, and viable propagules of Sporobolus pumilus in ice. Additionally, we found sediment densities between 0.01 and 4.75 g/cm 3 in ice blocks that translated to 26.61–21,483.59 kg of total sediment per block, representing a large source of sediment. We found that the number of germinating propagules could not be predicted by wrack size, and that pH, sediment density, sediment weight in ice blocks were variable across the marsh surface, while ice salinity was negatively correlated with elevation and distance from creek. Our results indicate that ice and wrack represent a potential source for vegetation colonization at salt marsh sites and highlights their contributions to facilitating vegetation colonization through building marsh soils.