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On October 22, 2024, 8:37:33 PM UTC, Gravatar ckan_admin:

  • Changed title to Algal-Induced Biogeomorphic Feedbacks Lay the Groundwork for Coastal Wetland Development (previously Algal-induced biogeomorphic feedbacks lay the groundwork for coastal wetland development)


  • Updated description of Algal-Induced Biogeomorphic Feedbacks Lay the Groundwork for Coastal Wetland Development from

    Coastal wetlands provide valuable ecosystem services, including biodiverse habitats, carbon sequestration potential and nature-based flood defense. The establishment of saltmarsh vegetation and other key wetland species on bare tidal flats relies on windows of opportunity, which are traditionally linked to physical factors such as hydrodynamic conditions, substrate stability and drainage. However, observations on tidal flats suggest that plant seedlings settle in high densities on raised sedimentary ridges colonized by mats of primitive filamentous algae (Vaucheria sp.). Such algal- covered ridges were previously shown to have higher sediment strength than substrate without algae. Here, we investigated whether these measurements can be explained by physical processes only, or that biological (Vaucheria-induced) processes influence early saltmarsh establishment through the formation of stabilized bedforms. We performed two experiments under controlled mesocosm conditions, to test the hypotheses that i) Vaucheria grows better on elevated topographic relief, ii) the binding force of their algal filaments increases sediment strength, which consequently iii) maintains and creates elevated topographic relief on which algal growth is further facilitated. The existence of this algal-induced biogeomorphic feedback cycle was confirmed in our experiments. Our findings reveal that halophytic plants are not the only important ecosystem engineer in coastal wetlands, but that fast-growing, mat- forming species like Vaucheria also play a major role by creating stable and elevated sedimentary relief. Our study indicates that biota can widen the windows of opportunity for ecosystem establishment, which can be utilized to optimally design managed coastal realignment projects that aim at the restoration of coastal ecosystems.
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    Ecosystem establishment under adverse geophysical conditions is often studied within the framework of windows of opportunity, which predicts ecosystems to establish when geophysical disturbances are temporarily reduced. However, the role of biogeophysical interactions in this framework is less well understood. The establishment of saltmarsh vegetation on tidal flats, for example, is limited by abiotic factors such as hydrodynamics, sediment stability and drainage. On tidal flats, we observe high densities of plant seedlings on raised sediment ridges colonized by algal mats (Vaucheria sp.). Such ridges were previously found to have higher sediment strength than substrate without algae. Here, we investigate whether these measurements can be explained by geophysical factors only, or that biological (Vaucheria-induced) processes influence tidal marsh establishment by forming stabilized bedforms. We perform two experiments under controlled mesocosm conditions, to test the hypotheses that i) Vaucheria grows better on elevated topographic relief, ii) the binding force of their algal filaments increases sediment strength, which consequently iii) creates elevated topographic relief that further facilitates algal growth. Our experimental results confirm the existence of this algal-induced biogeomorphic feedback cycle. These findings reveal that primitive organisms like Vaucheria may contribute significantly to tidal marsh formation by creating elevated and stabilized substrate. We thus show that biogeophysical feedbacks can “widen” the windows of opportunity for further ecosystem establishment. Our results could be useful for the design of managed realignment projects aimed at restoring the unique ecosystem services of coastal wetlands, such as habitat biodiversity, carbon sequestration potential and nature-based flood defense.


  • Changed the version of Algal-Induced Biogeomorphic Feedbacks Lay the Groundwork for Coastal Wetland Development to 3 (previously 2)