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Sea level changes will significantly drive hydrodynamic, morphological, and ecological development of estuaries. However, the interplay of geomorphology and vegetation at estuary scales remains unclear. To better understand this process, we take the Western Scheldt estuary in the Netherlands as an example to reveal the link between changes in emersion duration and vegetation dynamics in the period 1993–2016. We found that tidal flats in the Western Scheldt become steeper—higher intertidal areas increased in elevation and emersion duration, whereas the low-lying edges of tidal flats experienced a decrease in elevation and emersion duration. We found that longer emersion duration was associated with increased plant diversity and cover. Furthermore, we detected the unique spatiotemporal response patterns of four abundant plant species to geomorphological variations. Our study suggests that on a large estuary scale, geomorphological changes are coupled to the richness and cover of plant communities, and that potential changes in relative sea level can induce structural modifications of the plant communities. It also emphasizes the importance of assessing the potential effects of localized relative sea level changes while considering all aspects of natural processes and direct and indirect human influences. Our study provides a framework to assess the bio-geomorphic processes in a spatially explicit way.

Hidden and perilous rip currents are one of the primary factors leading to drownings of beach swimmers. By identifying the coastal areas with the highest likelihood of generating rip currents, it becomes possible to prevent fatalities and mitigate economic losses associated with these hazardous currents. Rip currents are characterized as streams of water moving towards the open sea, forming within the area where waves break, due to variations in wave-induced radiation stresses and pressure along the coastline. This study utilized nine different Machine Learning (ML) models, including M5 Model Tree (MT), Multivariate Adaptive Regression Spline (MARS), Gene Expression Programming (GEP), Evolutionary Polynomial Regression (EPR), Random Forest (RF), Support Vector Machine (SVM), Extreme Gradient Boosting (XGBoost), Adaptive Boosting (AdaBoost), and Stacked ML models, to estimate the Relative Tide Range (RTR) values for 50 southern beaches in China. Through this approach, we gathered a reliable dataset from prior research conducted on the southern coast of China. In this study, two parameters, namely dimensionless fall velocity parameter (Ω) and tide range (TR) are used to predict the vulnerability of rip current event. The results of the AI models were assessed by various statistical analyses (Correlation of Coefficient [R], Root Mean Square Error [RMSE], violin diagram, heatmap, and taylor diagram) for training and testing stages. Accordingly, the MARS model exhibited superior performance compared to other AI models in accurately predicting the RTR value. The outcomes substantiated the significant effectiveness and capability in estimating the RTR with high accuracy. Southern China coasts have relative high risk level of rip current, necessitating the attention and strategic management of this dangerous current by the beach managers.

Tidal flats and saltmarshes have been a long-standing research focus because of their high socio-economic and ecological values. The evolution of tidal flat–marsh systems is highly complex due to the intertwined processes operating over a variety of spatial and temporal scales. As a traditional research highlight, the role of regular hydrodynamic processes such as tides, waves, and river flows have been explored comprehensively with fruitful outcomes. Over past decades, the changing environment (e.g., sea level rise, increasing anthropogenic activities, and extreme weather conditions) has attracted more attention with many reported insightful results. More recent advances indicate that biological activities play a critical role in tidal flat–marsh morphodynamics but are still poorly understood. The field of research that connects the biological and physical processes is commonly described as “biogeomorphology” and requires the joint efforts by scientists from multiple disciplines ranging from hydraulics, ecology, and geography to sociology. This review aims to provide a synthesis of the current research status of tidal flat–marsh morphodynamics, with a particular emphasis on the understanding of various processes and feedbacks underlying the development of morphodynamic models. Some future research needs and challenges are identified to facilitate a more sustainable management strategy for tidal flats and saltmarshes under climate change.

Salt marshes are among the most common morphological features found in tidal landscapes and provide ecosystem services of primary ecological and economic importance. However, the continued rise in relative sea level and increasing anthropogenic pressures threaten the sustainability of these environments. The alarmingly high rates of salt marsh loss observed worldwide, mainly dictated by the lateral erosion of their margins, call for new insights into the mutual feedbacks among physical, biological, and morphological processes that take place at the critical interface between salt marshes and the adjoining tidal flats. We combined field measurements, remote sensing data, and numerical modeling to investigate the interplays between wind waves and the morphology, ecology, and planform evolution of salt marsh margins in the Venice Lagoon of Italy. Our results confirm the existence of a positive linear relationship between incoming wave power density and rates of salt marsh lateral retreat. In addition, we show that lateral erosion significantly decreases when halophytic vegetation colonizes the marsh margins, and that different erosion rates in vegetated margins are associated with different halophytes. High marsh cliffs and smooth shorelines are expected along rapidly eroding margins, whereas erosion rates are reduced in gently sloped, irregular edges facing shallow tidal flats that are typically exposed to low wind-energy conditions. By highlighting the relationships between the dynamics and functional forms of salt marsh margins, our results represent a critical step to address issues related to conservation and restoration of salt marsh ecosystems, especially in the face of changing environmental forcings.

Morphogenesis is a physical process that sculpts the final functional forms of tissues and organs. Remarkably, the lungs of terrestrial vertebrates vary dramatically in form across species, despite providing the same function of transporting oxygen and carbon dioxide. These divergent forms arise from distinct physical processes through which the epithelium of the embryonic lung responds to the mechanical properties of its surrounding mesenchymal microenvironment. Here we compare the physical processes that guide folding of the lung epithelium in mammals, birds, and reptiles, and suggest a conceptual framework that reconciles how conserved molecular signaling generates divergent mechanical forces across these species., (Copyright © 2024. Published by Elsevier Inc.)

Sandy beaches are land-sea transitional habitats experiencing 'multidirectional' habitat loss due to coastal developments (e.g. armoring and/or conversion of natural vegetation into manmade structures) and beach erosion. This 'coastal squeeze' is a chronic and progressive process; however, its impacts on beach biodiversity across morphodynamic gradients are still to be unveiled. We hypothesized that the effects of multidirectional habitat loss would be more severe on dissipative than on reflective beaches, due to the higher elevation, amount of built up sediment, and width of the backshore compartment of the latter. We, thus, examined the effects of coastal developments and erosion on density and size structure of the Atlantic ghost crab, Ocypode quadrata, on beaches with different morphodynamics. Given that the living area of ghost crabs spans all cross-shore compartments and the whole dissipative-to-reflective morphodynamic gradient, they are appropriate organisms to access the synergic effects of coastal developments and beach erosion under different morphodynamic regimes. On dissipative beaches, density and mean crab size increased with moderate erosion, attributed to the effects of space loss, which might increase territorial competition, favoring the remaining larger individuals. However, mean size and density decreased with high erosion given the more intense reduction in the abundance of large-sized crabs living in up-shore habitats. Mean crab size also decreased in the presence of coastal development while crab density did not vary with loss of backshore habitats occupied by larger individuals. On reflective beaches, both density and crab size decreased with coastal development; the crab size decrease recorded under moderate erosion was more evident in the presence of coastal development. Under high erosion, mean crab sizes declined, reflecting those under low erosion conditions. Overall, populations on reflective beaches appeared more resilient to extreme erosion. Notwithstanding, coastal developments affected population structure across all beach types, and especially in areas subjected to high erosion, exhibiting a synergic effect. We predict that, in combination, these stressors may lead to functionally extinct populations where conditions necessary for individuals to reach sexual maturity (i.e. occurrence of only small-sized and immature individuals) are not met. Thus, the connectivity between water, beach compartments and dunes/coastal plain, on both local and regional scales, may be essential to maintain viable and connected populations of ghost crabs. Further, our results strongly suggest that both size and density (complemented with crab abundance) must be considered equally important and in combination in future efforts to assess anthropogenic stressors on ghost crab populations and when guiding conservation strategies and policies to prevent their local and regional extinctions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

During development of the embryonic mouse lung, the pulmonary mesenchyme differentiates into smooth muscle that wraps around the airway epithelium. Inhibiting smooth muscle differentiation leads to cystic airways, while enhancing it stunts epithelial branching. These findings support a conceptual model wherein the differentiation of smooth muscle sculpts the growing epithelium into branches at precise positions and with stereotyped morphologies. Unfortunately, most approaches to manipulate the differentiation of airway smooth muscle rely on pharmacological or physical perturbations that are conducted ex vivo. Here, we explored the use of diphtheria toxin-based genetic ablation strategies to eliminate airway smooth muscle in the embryonic mouse lung. Surprisingly, neither airway smooth muscle wrapping nor epithelial branching were affected in embryos in which the expression of diphtheria toxin or its receptor were driven by several different smooth muscle-specific Cre lines. Close examination of spatial patterns of Cre activity in the embryonic lung revealed that none of these commonly used Cre lines target embryonic airway smooth muscle robustly or specifically. Our findings demonstrate the need for airway smooth muscle-specific Cre lines that are active in the embryonic lung, and serve as a resource for researchers contemplating the use of these commonly used Cre lines for studying embryonic airway smooth muscle., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2023 Elsevier Inc. All rights reserved.)

The morphodynamics of tidal flats responds mainly to the nonlinear interaction between tides and seasonal wave activity. Man-made activities such as reclamation further complicate the morphodynamics by disturbing physical processes acting on the tidal flats. Decoupling the anthropogenic influence from the natural forcing on the tidal-flat morphodynamics is crucial in assessing the adverse effects of man-made activities. Still, it remains a challenge due to inherent difficulties in characterizing spatiotemporal variability of the tidal-flat morphology. A three-year-long field survey using unmanned aviation vehicle (UAV)-assisted photogrammetry, sedimentological and benthic fauna data was conducted on the Shinsi tidal flats near the Saemangeum dike, west coast of Korea, to evaluate the relative significance between natural and anthropogenic influence on the morphologic changes of the tidal flats and benthic community structures. The Shinsi tidal flats exhibited non-seasonal sedimentation patterns and experienced overall erosion despite their sheltered location from the offshore waves. The Saemangeum dike contributed to the sustained erosion by reflecting offshore waves toward the tidal flats during winter to spring. Heavy rainfalls also promoted erosion of the tidal flats in summer. The small-scale embankments complicated the spatial sedimentation trend by protecting tidal flats from offshore waves or promoting erosion with shoaling waves. Notable mud deposition occurred during winter, incompatible with the general hydrodynamic condition, resulting from intensive dredging activity inside and outside the Saemanguem dike. The proliferation of the opportunistic species followed the mud deposition for several months until the enhanced wave activity removed the muddy sediments from the flats. Overall erosion dominance and the temporary occurrence of opportunistic species imply that the Shinsi tidal flats are subject to non-seasonal changes in sedimentology and morphology due to artificial structures and man-made activity, leading to the instability of the benthic communities in the tidal flats., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

In the present study the distribution of chemical elements in beaches adjacent to the Doce River mouth hit by the tailings mud from a mining accident were assessed. Sedimentological and morphological coastal aspects were also considered. The results indicate that wave-exposed delta plain beaches exhibit high resiliency, despite their proximity to potential pollution sources. On the other hand, shore platform beaches tend to accumulate chemical elements, mainly due to limited cross-shore sediment exchanges. Arsenic concentrations in the evaluated shore platform beaches were significantly higher than the delta plain beach. Shore platform beaches are more susceptible to frequent flooding and to higher elemental concentrations at the berm and beach face. Thus, the morphological characteristics of the assessed shore platform beaches, and input from the mud plume must be considered in a joint assessment strategy in order to obtain a broad understanding of the actual scenario regarding beach contamination., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

This study describes the beach profile, characterizes microplastics and correlates their abundance with morphodynamics characteristics on three beaches from the state of São Paulo, Brazil. 745 particles were found in 4 m 2 of sediment, mostly styrofoam. Nearly 90% of the fragments were found in Boracéia, the most dissipative beach, while less than 1% were found in Juréia beach, the most reflective one. The chemical composition of microplastics was identified by near-infrared hyperspectral imaging (HSI-NIR). The correlation between the abundance of particles and the slope plus the extension of the sand strip was high, as well as that found with the waves' height. These preliminary results indicate that there might be an intrinsic relation among the morphodynamical forces, the movement and destination of microplastics in marine environments., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The seasonal and fortnightly erosion and sedimentation pattern as well as the bonding characteristics of the mud deposit at the estuarine turbidity maximum (ETM) zone of the macrotidal Chikugo River estuarine channel were studied during 2005-2008 using the periodical topographic surveys and mud sampling along with continuous monitoring of water level, turbidity and flow velocity. The results revealed that the estuary was influenced by the tidal forcing during the dry season. This tidal forcing accelerated the net landward sediment transport and sedimentation takes place in the estuarine channel. On the contrary, the river discharge dominated the estuary during the rainy season which eroded those mud deposit in the estuarine channel and exported to the downstream and the sandy base layer appeared at the bottom. During the dry season, a mud deposit of 1.5-1.8 m thick was formed which was characterized by 90% of mud (fine silt and clay) and 10% of fine sand. The high viscosity ratio and loss on ignition of this mud deposit revealed that its consolidation begins at the early stages of deposition due to thixotropy and the presence of organic matter. This consolidation process in the natural environment will be several times higher than that of the disturbed mud, which will help the sediment surface to maintain stability against erosion even at high velocities. Moreover, the consolidation of the mud deposit has a strong impact on the seasonal changes in estuarine morphology other than external forcing such as river discharge, tides, wind and availability of sediments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Single-cell RNA-sequencing (scRNA-seq) and related technologies to identify cell types and measure gene expression in space, in time, and within lineages have multiplied rapidly in recent years. As these techniques proliferate, we are seeing an increase in their application to the study of developing tissues. Here, we focus on single-cell investigations of branching morphogenesis. Branched organs are highly complex but typically develop recursively, such that a given developmental stage theoretically contains the entire spectrum of cell identities from progenitor to terminally differentiated. Therefore, branched organs are a highly attractive system for study by scRNA-seq. First, we provide an update on advances in the field of scRNA-seq analysis, focusing on spatial transcriptomics, computational reconstruction of differentiation trajectories, and integration of scRNA-seq with lineage tracing. In addition, we discuss the possibilities and limitations for applying these techniques to studying branched organs. We then discuss exciting advances made using scRNA-seq in the study of branching morphogenesis and differentiation in mammalian organs, with emphasis on the lung, kidney, and mammary gland. We propose ways that scRNA-seq could be used to address outstanding questions in each organ. Finally, we highlight the importance of physical and mechanical signals in branching morphogenesis and speculate about how scRNA-seq and related techniques could be applied to study tissue morphogenesis beyond just differentiation., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Despite relevant advances achieved in recent years, sediment transport and sedimentation problems at tidal inlets are still worldwide issues to be addressed. Furthermore, dredging strategies are carried out following traditional layouts, such as channel deepening, lasting short periods of time despite the high economic expenditures and the potential environmental impacts. This work proposes a new dredging strategy for tidal inlets and analyzes its morphodynamic evolution by means of numerical modeling. This numerical model, used to perform hydro-morphodynamic simulations, is applied to a highly altered tidal inlet (Punta Umbría inlet, Southern Spain) with a navigational capacity being continuously compromised. After calibrated and tested, the model is applied to different dredging strategies, including channel deepening, littoral drift barrier and shoal removal. Among these strategies, the shoal removal, which is a new soft-engineering strategy, is found to be the most efficient to improve the navigational channel operativity, defined as the percentage of navigable hours per year for different vessel drafts; this operativity improves up to 60% compared to the other strategies. This solution, which reduce the frequency of maintenance interventions and hence the environmental impacts, may be suitable for other inlets with compromised navigational capacities due to the presence of ebb shoals. The relation between the main maritime drivers and the morphodynamic changes is analyzed, concluding that the morphodynamic evolution of the navigational channels is closely related not only to the wave energetic content, but largely to the wave directionality. Finally, the shoal removal also increases the flow velocities at the inlet modifying the stability of the mouth and hampering its long-term closure. The potential environmental impacts derived from the shoal removal are also discussed., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The core of Evo-Devo lies in the intuition that the way tissues grow during embryonic development, the way they sustain their structure and function throughout lifetime, and the way they evolve are closely linked. Epithelial tissues are ubiquitous in metazoans, covering the gut and internal branched organs, as well as the skin and its derivatives (ie, teeth). Here, we discuss in vitro, in vivo, and in silico studies on epithelial tissues to illustrate the conserved, dynamical, and complex aspects of their development. We then explore the implications of the dynamical and nonlinear nature of development on the evolution of their size and shape at the phenotypic and genetic levels. In rare cases, when the interplay between signaling and mechanics is well understood at the cell level, it is becoming clear that the structure of development leads to covariation of characters, an integration which in turn provides some predictable structure to evolutionary changes. We suggest that such nonlinear systems are prone to genetic drift, cryptic genetic variation, and context-dependent mutational effects. We argue that experimental and theoretical studies at the cell level are critical to our understanding of the phenotypic and genetic evolution of epithelial tissues, including carcinomas., (© 2016 Elsevier Inc. All rights reserved.)