In response to the challenges posed by coastal erosion and rising sea levels, bio-inspired strucutres represent an innovative solution by combining physical protection with ecological benefits. This study investigates how key structural parameters, including tortuosity, surface roughness, porosity, and structural diversity, affect near-bed shear stress and turbulence around bio-inspired coastal defense modules.Wave flume experiments were conducted using fifty-one different modules, organized in three rows and tested under five monochromatic wave conditions (heights 2.5–10 cm, periods 1–2 s), scaled for Mediterranean deployment. Measurements from resistive wave gauges and Vectrino velocimeters were used to analyse wave energy dissipation, vertical current profiles, turbulence, and bed shear stress.Preliminary results show that structural geometry appears to influence local hydrodynamics, with implications for a better understanding of how the selected parameters affect the surrounding hydrodynamic conditions. The effects of the parameters are ranked to guide the development of efficient, multifunctional, bio-inspired coastal defense solutions. A combination of several of these parameters, within a single module and then at the scale of an entire structure, allowed us to explore the potential benefits of structural complexity in coastal protection systems.

Offshore oblique bars typically follow a net offshore migration (NOM) pattern. However, this kinematic view overlooks how migration relates to sand-grain dynamics, as revealed by grain-size distribution (GSD). In the Gulf of Lions (France), slightly oblique bars identified by LIDAR were analyzed through detailed GSD studies. Formed under southward longshore transport, these sediments show mixed grain populations, deconvoluted using the LNDOGS program. High skewness highlights multimodal distributions. Among the four sedimentary types (STs), ST1 and ST2 are most associated with seaward migration, with ST2 evolving from ST1 via minor variants (SVs). As bars merge with the lower shoreface (LSh) and disappear, GSD distinctions fade, shifting toward unimodal, symmetrical patterns under shoaling influence. The apparent paradox—regional southward transport versus northward bar migration—is explained by the interplay of resuspension, sorting, offshore export, and downdrift transport (RSOED). Together, these processes couple sediment pathways and morphology. This innovative GSD-based approach yields a hypothetical qualitative model based on empirical knowledge of processes not measured in the field that links bar form and composition, offering new insight into mechanisms of net offshore bar migration.

Hard structures like dykes or groins have been recognized for their negative environmental impact and limited durability in the face of climate change (Sutton-Grier et al., 2015). The concept of Shore Soft Engineering (SSE) has allowed ecological considerations to be embedded in the design of coastal protection (Hartig et al., 2011). Among emerging defense structures, nature-based solutions are built with natural materials and rely on physical properties and mechanisms observed in nature. They aim to protect, manage and restore ecosystems while providing some benefit to the human-being and biodiversity (Cohen-Shacham et al., 2016); they offer an interesting alternative to hard structures. However, implementing these solutions in urbanized coastal areas where ecosystems are vulnerable can be challenging. Another alternative approach is using biomimetic solutions, which can provide the functions of natural systems like seagrass, dunes, or coral through robust human-made constructions. Natural habitats exist in a variety of more or less complex forms, ranging from rigid (mangroves, coral) to flexible (seagrass) (Mullarney and Henderson, 2018); and they drive changes in the current profile, in wave dissipation or in sediment motion. Understanding how to mimic these systems, in particular their internal geometry and hydrodynamic effects, is challenging. This complexity makes the development of biomimetic solutions difficult (Perricone et al., 2023). In this context, this study strictly focuses on wave dissipation by flexible systems. Wave dissipation by natural habitats has been extensively studied through laboratory experiments (Houser et al., 2015) and in-situ measurements (Bradley and Houser, 2009). The pioneer analytical model (Dalrymple et al., 1984) depicted aquatic vegetation as rigid cylinders; however, the rigidity assumption fails to capture the inherent flexibility of plants. Alternative strategies emerged to account for this flexibility, such as using an empirical drag coefficient (Mendez and Losada, 2004) or introducing an effective length, representing the length that a rigid cylinder would have to dissipate the same wave height as flexible cylinders (Luhar and Nepf, 2016). However, to define this effective length or an empirical drag coefficient, it is necessary to carry out in-situ measurements. Numerous analytical models based on force balance (Luhar and Nepf, 2016; Leclercq and de Langre, 2018) have been developed to represent the movement of flexible vegetation like seagrass. These models depict the flexible vegetation as a series of segmented rigid stems attached to each other and subjected to oscillating flows. Some models attempt to link stem motion with wave dissipation to integrate this coupling into numerical models (Yin et al., 2022). However, these models still require unknown quantities such as drag and inertial coefficients. The present study aims to develop an analytical model for determining drag and inertial coefficients based solely on the geometry, the structure flexibility and wave forcing. At last, the method could help better represent the dissipation into numerical simulations without the need for prior parametrization.

The morphodynamics of the Leucate double-crescent bar system was studied over twenty years using bathymetric data supplemented by satellite images and video monitoring. Eleven different bar typologies were identified, mostly based on existing beach state classifications (Low-Tide Terrace, Transverse Bar and Rip, Rhythmic Bar and Beach), also including new heterogeneous typologies (TBR/LTT, RBB HP/RBB, TBR/RBB). The inner bar shows greater variability, with 10 different typologies observed, while the outer bar shows only three different typologies. Summer low-energy periods are dominated by TBR/LTT and TBR typologies, while RBB, although common throughout the year, dominates winter periods along with disrupted bar configurations. The return to less energetic periods in spring is associated with the establishment of heterogeneous typologies. The outer bar has a fairly stable position, although breaches at the embayments and slight movements of its horns can occur following particularly energetic episodes. The inner bar, on the other hand, is much more dynamic, with more common breaches at the embayments and significant cross-shore movement of the horns. Seasonal changes in bar typology do not lead to bar renewal through destruction/reconstruction. Overall, the morphological and typological characteristics of the bar system described here seem somewhat unique compared to the existing literature.

This study focuses on low-microtidal (average tidal range ≈ 0.3 m) crescentic beaches in the northwestern Mediterranean. The field site is composed of two beach barriers representative of the southern part of the Gulf of Lions (French Mediterranean coast): the Leucate beach backed by a small dune and the La Franqui beach backed by a small lagoon. Offshore winds are dominant and can reach speeds of up to 30 m.s-1. Onshore winds are less frequent and are accompanied by swell. An analysis of the hydrometeorological forcing and the resulting morphological changes during 4 years of the survey allows us to define the key parameters controlling the system, which is then used to develop a conceptual model composed of five main situations. Dominant offshore winds have an erosive action on the backshore and produce progradation resulting from the supply of aeolian sediment to the shoreline; this progradation is concentrated on the horns when concomitant with small fair-weather waves. Moderate intensity waves and storms lead to strong erosion and steepening of the beach face, as well as the migration or construction of a new higher berm in retreat and sediment deposition on the upper beach. The sediment supply due to transport associated with offshore winds during the following weeks and months thus contributes to a reconstruction of the beach face and a return to the initial configuration. The classification of this coast as microtidal should therefore be reconsidered, low microtidal environments generally show fairly similar beach morphodynamics compared with high microtidal environments; the differences between these two types of environment arise from the relatively constant sea level that may enhance the morphogenic impact of fair-weather conditions on the beach face and create a more pronounced berm on the backshore during storm periods.

Projecting the combined effect of management options and the evolving climate is necessary to inform shared sustainable futures for marine activities and biodiversity. However, engaging multisectoral stakeholders in biodiversity-use scenario analysis remains a challenge. Using a French Mediterranean marine protected area (MPA) as a marine social-ecological case study, we coupled codesigned visioning narratives at horizon 2050 with an ecosystem-based model. Our analysis revealed a mismatch between the stated vision endpoints at 2050 and the model prediction narrative objectives. However, the discussions that arose from the approach opened the way for previously unidentified transformative pathways. Hybridizing research and decision-making with iterative collaborative modeling frameworks can enhance adaptive management policies, leveraging pathways toward sustainability.

The Banc d'Arguin (BA - Mauritania) has the double originality of being a shallow water platform (SWP) located on the edge of a sandy desert. This arrangement is rare in the world: Shark Bay in Australia, the western edge of the Persian Gulf and the Namibian margin are the main examples. BA's detailed study both in the marine part of the platform and on the coastal plain has highlighted the peculiarities of the Late Holocene parasequence (LH). In the basin, it is made up of two units recognized in seismic reflection: U5 surmounted by U6 / U7 in lateral variation of facies. U7 also constitutes most of the coastal plain, the construction of which Dia (2013) described in 5 stages. On its arrival, the postglacial Nouakchottian sea invaded areas determined by the construction and progression of ergs during the glacial episode (Azefal to the north, Agneitir and Akchar to the south). Their orientation defined the axes of penetration of the sea in the inter-ergs (Ras el Ma, sebkha Acheil). In addition, the estuaries of the paleo-wadis, functional during the wettest episodes, were occupied by the sea (Khatt des Ogols). The ingression thus exceeded 12 km in Ras el Ma and 10 km in the sebkha Acheil. The subsequent development was characterized by the clogging of the bay heads. It mainly used wind sands pushed in the axis of thalwegs and inter-ergs. The stability of the sea level since its arrival at its current level limited accommodation. The accommodation / supply ratio of Cattaneo and Steel (2003) was well below 1. The LH parasequence is therefore generally thin but very extensive on the surface. It is made almost entirely of sandy deposits characteristic of the inter and supratidal coastal environments: beach ridges and sedimentary spits, coastal dunes, large sand-flats which evolved into sabkhas for the oldest, as progradation progressed. The occasional use of the high points of the shore by the Neolithic populations underlined the coastal morphology. The description of the arrangement of the sedimentary subunits formed during the five phases of the period shows that it was formed by progradation with little aggradation during a phase of normal high-level regression. The comparison of the conditions prevailing in the other SWPs identified in the world shows that it is not the transgressive or regressive tendency of the deposits which is their most striking character. The very different lithology of the deposits is more discriminating and underlines the role played by desert sand inputs in the expression or not of other modes of biogenic and/or chemical sediment production. In the case where there are significant wind and fluvial siliciclastic components (northwest coast of Namibia) or significant wind inputs (BA in Mauritania), the production of biogeochemical carbonate components is reduced (Namibia) or even prevented (Mauritania). On the contrary, when the detrital inputs from a nearby desert environment are low (Shark Bay in Western Australia) or inefficient to almost non-existent (west coast of the Persian Gulf), the biogeochemical processes involved in the development of carbonates become predominant and lead to the formation of carbonate platforms. This continuum of models offers the possibility of identifying the amplitude of the desert signature in the paleogeographic reconstructions of certain platforms.

The Gulf of Lions shelf (southern part of the French Mediterranean coast) displays several occurrences of beachrocks, thus offering an exceptional opportunity to determine the stages of the last marine transgression. These beachrocks crop out especially on the outer shelf and near the modern shoreline. In addition, several other exposures are located on the inner shelf between 10 m and 25 m. The absence of exposure on the middle shelf (water depths of 25 to 90 m) is probably related to a higher rate of sea‐level rise. Most of the beachrocks occur at the top of two or three parallel and contiguous barriers. The seaward barriers are generally less lithified than the inner barriers. Each barrier displays an asymmetrical profile, the seaward slope being more accentuated. This gently‐dipping landward slope forms part of the outer trough resulting from resuspension due to enhanced turbulence at the barrier toe. Almost all of these beachrocks are coarse quartz‐rich sandstones and conglomerates, whose large pore space has been first filled by magnesian calcite (ca 11 mol.% MgCO3), which predominantly fills the voids. Secondary sparites or microsparites, also composed of high‐magnesian calcite, may develop locally in the last remaining voids. Finally, more rarely and very locally (for example, Pierres de Sète), a late‐stage cementation of low‐magnesian calcite is observed which expresses a brief episode of influence from a nearby freshwater groundwater table. The δ18O and δ13C values reflect the relative geochemical homogeneity of these Gulf of Lions beachrocks. However, they are quite distinct from other marine cements and, in particular, those of the eastern Mediterranean, expressing lower temperatures and a lack of influence of dissolved carbon linked to terrigenous fluxes. Based on the radiocarbon ages of these calcitic cements, this study proposes new index points on sea‐level positions in the Gulf of Lions from −95 to 108 m to −0.3 m water depths, between ca 18 583 a cal bp and 633 a cal bp.

This study focuses on the dynamics of an intermittent estuary in a wave-dominated (microtidal) area, with low fluvial discharges and strong dominant offshore wind regimes. The aims are to understand the effect of these particular environmental factors in the dynamics of such estuaries. The results allow us to propose a synthetic morphodynamic model of evolution whereby opening phases are predominantly controlled by offshore winds, which have a significant influence in the northern Mediterranean. Inputs from rainfall/karst discharge and the overtopping of storm waves cause the lagoon to fill. Closing phases are controlled by the slight easterly swell which forms a berm at the inlet entrance. On occasion, major storms can also contribute to barrier opening. Nevertheless, offshore wind remains the main controlling factor allowing the surge of lagoon waters behind the beach barrier and the lowering of the berm by wind deflation. This leads to opening of the barrier due to the overflow of lagoon waters at the beach megacusp horns, thus connecting the sub-aerial beach with the inner bar system that is developed on topographically low sectors of the barrier. To the best of the authors’ knowledge, this type of estuary is not described in the literature.

The southern part of the Gulf of Lions, formerly described as a double crescentic nearshore bar, may exhibit a third bar closer to the coastline which we defined as Low Beach Bar (LBB).Locally, the inner bar (IB) horn may be less developed and retreated seaward, leaving a larger accommodation space between it and the coastline.This allows the growth of a third proximal system of sandy plateau or bar, framed laterally by two "classic" IB horns close to the coastline.The dynamic of the LBB is very reactive to changes of hydrodynamic conditions due to their positions in the very shallow water and responds along an increasing morphological continuum from sandy plateaus to disrupted RBB if the energy level increases.The LBB is distinct from other transitory proximal systems observed in the literature such as SPAW or Net Offshore Migration initiation due to its resilience over several years and lack of offshore migration to replace the IB.It does, however, appear to be able to merge and exchange sediments with the beach face.

La collection « Dynamiques et evolution du littoral » rassemble et synthetise les connaissances disponibles afin de faire ressortir, a partir de leur examen, les points essentiels explicatifs de l’evolution du littoral francais. Elle comprend ainsi 10 fascicules metropolitains et 7 fascicules ultramarins correspondant aux « provinces sedimentaires francaises », et un fascicule de synthese national. Chaque fascicule local est organise en cinq grands chapitres thematiques, presentant le contexte physiographique de la province (principales caracteristiques geologiques et morphologiques et habitats naturels participant a l’evolution du littoral), les facteurs hydrodynamiques (principaux facteurs exogenes tels que les parametres climatiques, les niveaux et courants marins, les vagues et l’hydrologie des principaux cours d’eau), les donnees sedimentologiques (nature et repartition des sediments sur les cotes et les fonds marins, ainsi que leurs mouvements le long du littoral), l’impact des activites anthropiques (principaux amenagements realises sur les cotes et leur impact sur l’evolution du littoral, ainsi que les mesures prises pour limiter ces impacts) et enfin l’evolution du littoral et des fonds (bilan des tendances passees d’evolution, ainsi que mouvements sedimentaires ponctuels lies au passage d’evenements tempetueux morphogenes). Ces chapitres traduisent l’etat des connaissances actuelles et evaluent la sensibilite du littoral aux dereglements climatiques en cours. Ces documents pointent egalement les secteurs et thematiques ou les connaissances sont faibles ou en voie d’approfondissement. La « Synthese des connaissances de l’archipel de Saint-Pierre-et-Miquelon » constitue le onzieme fascicule de la collection « Dynamiques et evolution du littoral ». Il presente dans un document unique a la fois les caracteristiques de ces cotes, leurs evolutions passees et actuellement constatees mais se projette egalement dans l’avenir en proposant, sur la base des connaissances les plus recentes, une analyse prospective des evolutions a venir. L’objectif est d’offrir un socle de connaissances suffisant pour comprendre les phenomenes en cours sur le littoral et se preparer aux evolutions de demain.

Summary The topographical complexity of coral reefs is of primary importance for a number of hydrodynamical and ecological processes. The present study is based on a series of high‐resolution seabottom elevation measurements along the Maupiti Barrier Reef, French Polynesia. Several statistical metrics and spectral analysis are used to characterize the spatial evolution of the coral geometrical structure from the reef crest to the backreef. A consistent fractal‐like power law exists in the spectral density of bottom elevation for length scales between 0.1 and 7 m, while at larger scale, the reef structure shows a different pattern. Such a fine characterization of the reef geometrical structure provides key elements to reconstruct the reef history, to improve the representation of reef roughness in hydrodynamical models and to monitor the evolution of coral reef systems in the context of global change. © 2020 John Wiley & Sons, Ltd.

This work focuses on characterising the functioning of one of the last non-diked intermittent inlets in the French Mediterranean: the grau de La Franqui (Aude). The study consists of regular morphological surveys of the beach for more than 2 years with a DGPS-RTK. The deployment of hydrodynamic instruments (pressure sensors and current meter) over 2 months allows us to measure the water level variations on the coast and in the lagoon according to the hydro-meteorological forcing conditions.

Afin de lutter contre l'érosion croissante des plages sableuses du Golfe d'Aigues-Mortes (Occitanie), un rechargement massif en sable a été réalisé pendant l'hiver 2007-2008.Un peu plus d'un million de mètres cube de sables prélevés sur une flèche sous-marine (pointe de l'Espiguette) ont été répartis sur quatre plages soumises à des phénomènes de recul du trait de côte (Palavas, Carnon, Petit Travers et Boucanet).Cet article fait le point sur l'évolution de ce rechargement sur une période de dix ans après l'opération grâce à un suivi topo-bathymétrique annuel.Il met en avant la redistribution spatio-temporelle des sédiments et les relations existantes entre les trois compartiments que sont la plage émergée, la zone de battement du trait de côte et l'avant-côte.Une certaine stabilité semble atteinte seulement quatre ans après le rechargement et le prisme littoral n'a perdu qu'environ 30% du volume de sable initialement rechargé, mais avec de forte disparité entre les sites.Cette étude devrait permettre aux gestionnaires du littoral de mieux appréhender le devenir d'un rechargement au cours du temps et donc de mieux adapter les volumes à prendre en compte et les compartiments préférentiels à recharger.

Many coastal systems are influenced by geologic framework (e.g., bedrock or inherited sedimentary systems), either in their initial development, morphology, or continuously throughout their evolution. This study adds to our understanding of the role of bedrock inheritance by describing the evolution of the Miquelon-Langlade Barrier (NW Atlantic; France). This barrier has a complex coastal planform (Y-shape, 12-km-long, 100-2500-m-wide) with several embedded sedimentary landforms. Ground-penetrating radar and HR seismic data collected along the subaerial and subaqueous portions of the barrier reveal: (i) the bedrock architecture (largely buried by Holocene deposits) and (ii) the presence of specific inherited sedimentary units. Indeed, both the location and early development of the barrier are largely controlled by bedrock morphology; the barrier is perched on a buried bedrock high in its center, and pinned to subaerial bedrock exposures at its northern and southern ends. Moreover, unconsolidated sedimentary shoals, formed and modified by waves and tides during earlier stages of rapid sea-level rise, provided important morphological constrains that influenced barrier development and the resulting complex morphology of the barrier and associated beach-ridge plain. This study demonstrates the utility of using coupled terrestrial and marine geophysical data to map geologic framework units, thereby determining the role of inherited geology in the evolution of coastal systems.

Comprehensive onshore-offshore surficial and sub-surface mapping of a composite barrier (combination of prograded, aggraded, and/or transgressive segments) have provided a better understanding of the (i) mechanisms responsible for the formation and development of coastal barrier systems, (ii) relationships and interactions among individual parts of those systems, and (ii) the overall stratigraphic framework of subaerial and subaqueous segments of the barriers. Here, we investigate these facets of barrier evolution through integration of stratigraphic data from subaqueous high-resolution seismic and subaerial ground-penetrating radar, sedi-mentology (terrestrial cores and seafloor surface samples), and merged topographic and bathymetric mapping of the Miquelon-Langlade Barrier (northwest Atlantic Ocean, south of Newfoundland). This barrier system has two open coasts and evolved in a paraglacial setting, influenced by the reworking of glaciogenic sediment (glacial moraines) in a regime of complex sea-level changes. The barrier stratigraphic sequence is placed within the context of a shifting period from shoreline transgression to one of regression; the resulting sedimentary units reflect the isolated position of the Saint-Pierre-and-Miquelon Archipelago distal from continental influence. Seismic profiles reveal the position of the lowstand shoreline, located 20-25 m below modern sea level, further refining the existing lowstand model of southern Newfoundland. Continuous onshore-offshore subsurface geophysical mapping of the barrier allows for the identification of the relative positioning of distinct sedimentary units interpreted as subaerial barrier (beaches, dunes, spit), shoals, and shoreface deposits, and allows for estimation of the total barrier sediment volume (235 x 106 m(3)) and its relative subaqueous (90%) and subaerial (10%) components. Moreover, it reveals the three distinct morphological units comprising the Holocene barrier: (i) central, regressive, swash-aligned beach-ridge plains developed atop both thin (westward-prograding) and thick (eastward-prograding) shoreface deposits, (ii) drift-aligned, elongating spits located in the northwest and northeast of the island, and (iii) a transgressive barrier located adjacent to the northwest spit, pinned on its landward side to parabolic sand dunes, and currently experiencing erosion and limited overwash. Finally, this study places evolution of this system in the framework of paraglacial barrier evolutionary typology.

1. CEFREM-UMR 5110, Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66000 Perpignan, France. nicolas.robin@univ-perp.fr 2. BRGM, Université de Montpellier, 1039 rue de Pinville, 34000 Montpellier, France. 3. Marseille Université, CNRS, IRD, Collège de France, CEREGE, Aix-en-P., France. 4. BRGM, 3 avenue Claude Guillemin, BP 36009, 45060 Orléans Cedex 2, France. 5. BRGM, 117 avenue de Luminy, BP 168, 13276 Marseille Cedex 9, France.

Morphological investigations on the northwest coastal plain of Mauritania (Banc d'Arguin) lead to a revised post 6000 yrs. BP sea-level curve. The region is characterized by extensive sand flats occasionally surmounted by low sand barriers. These barriers pick out a set of paleoshorelines attributed to the six episodes defined by Dia (2013). Morphological evidence of the extreme flatness of the coastal plain is provided by topographic transects based on total-station surveys. Index points distributed throughout the second half of the Holocene are defined in relation to the position of the barrier sole, which is adjusted to the upper limit of the berm uprush. The elevation of index points is related to the mean sea level (MSL) through an assessment of the various errors likely to affect the results. Over the period since ca. 7000 cal yr BP, the measured elevations remain within a few decimetres of the present-day sea level. This implies that, throughout this time interval, sea level in the Mauritanian region oscillated within the usual range of natural variations, whereas oscillations of larger magnitude prevailed elsewhere. Because the study area is tectonically stable, the glacio-eustatic adjustment due to hydro-isostatic effects is of minor importance in Mauritania and the relative sea level (RSL) has responded solely to the eustatic component. Therefore, we would expect to find some record of ocean syphoning through a gradual emergence of the land after the mid-Holocene marine transgression and the subsequent development of vertically stepped paleoshorelines. The absence of such evidence raises the question of whether the drop in RSL was compensated by continuing deglaciation during the post-6000 Holocene.

While slightly oblique nearshore bars seem to be present on most barred beaches worldwide, to date they have been poorly studied due to their great longshore extension that requires large spatial scale data sets. Here, we give a detailed report of the morphology and multi-annual dynamics of these bars using a large set of data (LiDAR, bathymetric profiles and aerial photographs) on two barred beaches of the Gulf of Lions (Mediterranean Sea, France). Slightly oblique bars are characterized by a down-drift longshore gradual increase of their distance from the shoreline over tens of kilometres, forming an angle of 3–4° relative to the shore. Thus, at any time, the bar is in a different phase of the net offshore migration (NOM) cycle according to its longshore extent. Alongshore, a single bar is in the emergence phase of the cycle at its proximal end near the coast, in the phase of seaward migration where it exhibits transition/switching state from on- to offshore position and finally in the decay phase at its distal end where its disappears. On a multi-annual timescale, net offshore migration (NOM) of slightly oblique bars results in an up-drift displacement of the bar pattern, with rates that can reach several metres per day. Thus, a longshore time lag appears in the NOM cycle when the bar is observed on separate cross-shore bathymetric profiles. A global worldwide inventory based on the literature shows that these bars are common to many barred beaches where NOM cycles have been identified. In almost all case, there is a gradual down-drift increase of distance of the bar from the shoreline. However, inter-site comparison of environmental parameters does not allow us to determine the factors controlling the formation of slightly oblique bars. The longshore displacement of the bars is directly related to the cross-shore dynamics. This study emphasizes the important role of slightly oblique bars in nearshore morphodynamics and the need to improve our knowledge of these features.