Mixed sand and gravel beaches of Buenos Aires, Argentina. Morphodynamics and stability

Lamarchina, Salvador; Maenza, Reinaldo A.; Isla, Federico Ignacio

doi:10.1007/s11852-021-00830-7

Cited by 4 publications

(1 citation statement)

References 32 publications

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“…The height of these mid intertidal benches varies between 50 and 80 cm, though their top surfaces are relatively level with each other (i.e., height differences are mostly associated with variations in rill depth). Their lower sides and the bottoms of rills are periodically buried and abraded by sand and gravel (both sourced from nearby beaches; see Lamarchina et al, 2021) and, thus, lack biotic cover (Figure 1D). Abrasion and undercutting of the benches is likely a significant mechanism of overall platform erosion independently of the biotic platform-lowering effects investigated here.…”

Section: Study Sitementioning

confidence: 99%

Enhanced Weathering and Erosion of a Cohesive Shore Platform Following the Experimental Removal of Mussels

et al. 2021

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The organisms inhabiting intertidal platforms can affect their weathering and erosion rates. Research on biotic influences on platform integrity has traditionally emphasized the role of bioeroders (i.e., organisms that scrap or bore into platforms via mechanical and chemical means). Yet, recent studies illustrate that covers of sessile organisms on the surfaces of intertidal platforms can have bioprotective effects by reducing the efficacy of physical weathering and erosion agents. Eroding cliffs fronted by cohesive shore platforms are a pervasive feature along the continental Argentinean coastline (37–52°S). In this study, we investigated how mussel (Brachidontes rodriguezii) cover mediates weathering and erosion of a cohesive, consolidated silt platform at Playa Copacabana (5 km north of Miramar, Buenos Aires Province; 38° 14′ S, 57° 46′ W). By means of mussel removal experiments, we found that mussel cover attenuates variations in platform surface temperatures, enhances moisture retention during low tide, reduces rates of salt crystallization within the pores of the platform material, and attenuates hydrodynamic forcing on the platform surface. Mussel removal also led to a 10% decrease in surface hardness and a 2-mm reduction in platform height after 5 months. Collectively, our findings indicate that mussel beds limit substrate breakdown via heating-cooling, wetting-drying, and salt crystallization and provide some of the first experimental field evidence for the direct impacts of biotic cover on platform erosion. As intertidal platforms protect the cliffs behind from the hydraulic impact of waves, which may be enhanced with future sea-level rise, we posit that the protection of platforms by mussels indirectly moderates coastline retreat, especially on soft cohesive shores.

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Section: Study Sitementioning

confidence: 99%