Why bioprotection matters to our coastlines?

Coastal cliff retreat is a chronic problem along many rocky coastlines worldwide, threatening coastal assets and livelihoods. Retreat rates depend, in part, on the integrity of intertidal platforms that become exposed at the base of cliffs as they retreat landwards. When these platforms are weathered (e.g., via thermal degradation) and eroded (e.g., via wave action) they become lower, reducing protection of the cliffs behind.

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The weathering and erosion of intertidal platforms can be retarded if covered by bioprotective sessile invertebrates and macroalgae. Known examples of bioprotective intertidal organisms include macroalgae and barnacles, which attenuate temperature variations, retain moisture, and thus reduce rock breakdown via heating-cooling, wetting-drying, and salt crystallization. By limiting rates of platform weathering and erosion, these small bioprotective organisms may ultimately retard the erosion of the cliff line.

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Eroding cliffs are a pervasive feature along the continental Argentinean coastline (33 to 52˚S). Yet, it is unknown if sessile intertidal organisms have bioprotective influences on the consolidated, sedimentary platforms that front these cliffs. Assessing the potential bioprotective roles of common sessile organisms can inform our understanding of coastline dynamics and resilience in the face of ongoing anthropogenic threats to intertidal platforms and their biotic communities (e.g., urbanization, shellfish collection and trampling, climate sea level changes).