Seagrass Meadows Reduce Wind-Wave Driven Sediment Resuspension in a Sheltered Environment

Neto, Nery Contti; Pomeroy, Andrew; Lowe, Ryan J.; Ghisalberti, Marco

doi:10.3389/fmars.2021.733542

Cited by 8 publications

(2 citation statements)

References 61 publications

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“…van Wesenbeeck et al, 2022 and consequently increases sedimentation e.g. D' Fagherazzi et al, 2012;Contti Neto et al, 2022. This mechanism is supposed to stabilise landscapes and to allow for vertical bed level accretion to keep up with sea level rise (Kirwan et al, 2016), suggesting that restoration of wetlands is an invariable nature-based solution for coastal protection (Schuerch et al, 2018). This contrasts with the main findings of this study.…”

Section: Multiscale Biomorphodynamic Interactions and Steady Statescontrasting

confidence: 86%

Biogeomorphology shaping coastal and estuarine systems

Boechat Albernaz

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Coastal and estuarine environments are home to a wide variety of habitats and ecosystems. They provide ecosystem services such as nursery grounds and habitats for (non-)commercial fishes and other aquatic species, and offer natural protection to coastlines, shelter for harbors, tourism and leisure. Understanding the morphodynamics of coastal areas is vital as hundreds of millions of people live near the coast around the globe. Due to human pressure and climate change, many deltas and coastal areas are under threat. Therefore, the ability to understand and predict the long-term evolution (i.e. decades to millennium) of these systems is crucial for supporting policies and management towards more sustainable and safe usage of coastal environments. Coastal, fluvial and estuarine landscapes develop through interaction of water, sediments and biota. These landscapes are an ever evolving product of hydrodynamic forces, such as river discharges, tides and waves, sediment transport and interactions with biota on the pre-existing morphology. As such, a landscape is a product of the initial conditions (e.g. the geological legacy), the boundary conditions (tides, waves, fluvial discharges, sediment supply and longer-term sea level fluctuations) and internal conditions (roughness, friction, inertia and turbulence steered by channels, shoals, bars, bedforms and vegetation) controlling the hydrodynamics and sediment transport which in turn modify the morphology and the abiotic conditions for biota. Biota affect the hydrodynamics in various ways and may also directly change morphology by organic material accretion. Thus the landscape is a result of dynamic biogemorphodynamic interactions between water, sediment, morphology and biota. Two major but contrasting methodologies of studying long-term geomorphology and morphodynamics are: historical-paleogeographical reconstructions and morphodynamic modelling. Both methods have their own advantages and disadvantages in reconstructing past conditions, forecasting future conditions and understanding the morphodynamic drivers. Yet, scientific communities tend to concentrate on either method with limited interaction in spite of studying the same systems and processes. The reconstruction and hindcast of past conditions as well as the forecast of future scenarios are challenges for scientists. For example, paleogeographical reconstructions are commonly hampered by the ability to isolate variables and testing alternative hypotheses from often limited past data. On the other hand, morphodynamic models often need to be simplified in their initial and boundary conditions and in the acting mechanisms, in comparison to nature, due to a combination of limited available data (in terms of detailed model inputs), limited physical process formulations and limitations of computational power. That means, predicting the evolution of beaches, tidal basins and estuaries is challenging due to the limitations on our knowledge about the individual and combined effects of changing forces, such as sea level rise and sediment supply, within the morphodynamic feedback; as well as due to shortcomings in our knowledge of physics and the uncertainties of predicting future hydrodynamic conditions, sediment fluxes and composition and the biota composition for decades to centuries ahead. Consequently, there is an urgent need to identify and address important knowledge gaps between paleogeographical reconstructions and morphodynamic models regarding the response of coastal-estuarine systems under varying sediment supply, fluvial discharges and increasing sea level, especially in combination with vegetation. The objective of this thesis is to systematically determine the long-term and large-scale development of coasts, estuaries and tidal basins under combinations of tides, waves, river discharges, sea level rise, sediment supply and vegetation. Hypotheses posed by paleogeographical reconstructions were tested with numerical models.

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Section: Multiscale Biomorphodynamic Interactions and Steady Statescontrasting

confidence: 86%

Biogeomorphology shaping coastal and estuarine systems

Boechat Albernaz

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“…Previous works showed that vegetation dissipates hydrodynamic energy (e.g., van Wesenbeeck et al., 2022) and consequently increases sedimentation (e.g., Contti Neto et al., 2022; D’Alpaos et al., 2007; Fagherazzi et al., 2012; Nardin et al., 2018). This mechanism is supposed to stabilise landscapes and to allow for vertical bed level accretion to keep up with sea level rise (Kirwan et al., 2016), suggesting that restoration of wetlands is an invariable nature‐based solution for coastal protection (Schuerch et al., 2018).…”

Section: Discussionmentioning

confidence: 99%

Vegetation Reconfigures Barrier Coasts and Affects Tidal Basin Infilling Under Sea Level Rise

et al. 2023

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Tidal basins and associated saltmarshes along barrier coasts are important marine-terrestrial interface environments that provide valuable ecosystem services including coastal protection (Barbier et al., 2011;Zhu et al., 2020) and shelter for harbours. In this article, "barrier coasts" refer to systems composed of mainland-backed tidal basins enclosed from the ocean by barrier islands and spits while connected to the open sea via inlets (Figure 1). Inlet geometry is controlled by waves and littoral drift, which work to narrow and close inlets, and tidal forces, which strive to maintain the connection (De Swart & Zimmerman, 2009). The inlets are bracketed by ebb-and flood-tidal deltas that provide sediment storage and protection against storms for the shallow areas rich in marine and terrestrial ecology (De Swart & Zimmerman, 2009;Moore et al., 2018). The morphological evolution of the barrier coast is driven by the combination of sediments transported by tides and waves (Boyd et al., 1992;Davis & Hayes, 1984;De Swart & Zimmerman, 2009). The combined effects of tides and waves promote water and sediment exchange between the open coast, tidal deltas, and the inner basin. These hydrodynamic forces

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The interaction between vegetation patchiness and tidal flows in a shortleaf seagrass meadow

da Silva,

Mullarney,

Pilditch

et al. 2024

Limnology & Oceanography

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Seagrasses are critical coastal habitats that provide numerous ecosystem services. The inherent patchiness within meadows exerts a significant influence on the flow‐vegetation interaction, which, in turn, affects the array of services provided by these environments. We present field observations of vegetation distribution and hydrodynamic measurements within and surrounding an approximately 2 m diameter gap (bare sediment) in a fragmented seagrass meadow. We show that variability in mean flows and turbulence is correlated with meadow structure at small (O (100 m)) and large (O (102 m)) spatial scales. Our observations reveal that bare gaps within seagrass meadows lead to faster flows and lower bed elevations. Despite slower flow speeds above the dense seagrass adjacent to the gap, the rates of dissipation of turbulent energy above the vegetation are typically around an order of magnitude larger than above the bare bed. Associated with this enhanced dissipation of turbulent energy, we observed a dominance of down‐deceleration events promoting fluid exchange and mixing and driving mass flux into the canopy. Analysis of directional variograms demonstrates that the major continuity axis within NDVI (normalized difference vegetation index) imagery (used as a proxy for vegetation biomass) coincides with the major axis of flow on both gap and meadow scales. Conversely, along the axis of minor flow variance, vegetation remains dense and exhibits greater uniformity. These findings indicate a feedback mechanism between seagrass meadow patchiness and spatial structure through flow modification, which may be beneficial for plant development.

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Seagrass Meadows Reduce Wind-Wave Driven Sediment Resuspension in a Sheltered Environment

Cited by 8 publications

References 61 publications

Biogeomorphology shaping coastal and estuarine systems

Biogeomorphology shaping coastal and estuarine systems

Vegetation Reconfigures Barrier Coasts and Affects Tidal Basin Infilling Under Sea Level Rise

The interaction between vegetation patchiness and tidal flows in a shortleaf seagrass meadow

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