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Very-high-resolution seismic profiles of offshore deposits. Representative seismic sections are shown with the derived stratigraphy (L1, L2 and L3). The contour map represents the thickness of sediments in the offshore area.
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Coastal ecosystems produce and store carbonate particles, which play a significant role in the carbonate dynamics of coastal areas and may contribute to the sediment budget of adjacent beaches. In the nearshore seabed of temperate zones (e.g. Mediterranean Sea and South Australia), marine biogenic carbonates are mainly produced inside seagrass mead...
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Context 1
... seismic surveys enabled assessment of the coastal wedge's thickness and stratigraphy (Fig. 5), finding variable thicknesses, up to a maximum of about 3 m, depending on the morphology of the rocky substrate, which determines the space available for sediments (Fig. 5). To the north, several rocky outcrops limit the coastal wedge to small depositional areas (Line L1). In the central sector the coastal wedge lies on the seaward side of a very shallow rocky outcrop of the substrate (Line L2), whereas to the south a major rocky out- crop clearly separates the submerged beach with bars from the deeper portion of the coastal wedge (Line ...
Context 2
... seismic surveys enabled assessment of the coastal wedge's thickness and stratigraphy (Fig. 5), finding variable thicknesses, up to a maximum of about 3 m, depending on the morphology of the rocky substrate, which determines the space available for sediments (Fig. 5). To the north, several rocky outcrops limit the coastal wedge to small depositional areas (Line L1). In the central sector the coastal wedge lies on the seaward side of a very shallow rocky outcrop of the substrate (Line L2), whereas to the south a major rocky out- crop clearly separates the submerged beach with bars from the deeper portion of the coastal wedge (Line ...
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During the last decades, many scientists worldwide have focused on the study of activity signs of animals. Such signs of various animals have appeared in the geological history since Ediacaran rocks and can be found until today. They can be signs of sedentary lifestyle or tracks of moving of animals (both vertebrates and invertebrates), evidence of...
Citations
... PO meadows constitute the most important, complex and widespread marine ecosystem of the Mediterranean sea's phital system and provide important goods and services to society (PO meadows are biodiversity hotspots, breeding areas for species of fishing interest and large carbon sinks). In turn, ''banquettes'' (accumulations of dead PO leaves on the seashore) play an important role in protecting the coast but are very sensitive to human activities (Boudouresque et al., 2016(Boudouresque et al., , 2017López et al., 2018;De Falco et al., 2017). The extension of PO meadows have decreased in 34% in the last 50 years, approximately 368.800ha due to human impacts (Telesca et al., 2015). ...
Marine Protected Areas (MPAs) are essential tools in the protection and conservation of marine ecosystems. However, very few MPAs are effective and meet their conservation objectives mainly due to a lack of coordination, participation or resources. For instance, in the Mediterranean Sea there are about 1062 MPAs, but 72% of them do not have effective regulations to reduce human impacts on biodiversity and current efforts are insufficient in managing human uses for the conservation and protection of marine biodiversity. This makes necessary to seek new ways or instruments for their management. In this sense, digitalization and Information and Communication Technologies (ICT) can provide tools to facilitate the development of MPAs management in a more effective, participatory and efficient manner because automatic agents report their information and digest the data no matter the situation.
In the specific case of Spain, one of the main problems identified for MPAs management is the overlapping of different kinds of protected areas in the same territory. In addition, these are managed by different administrations (Regional, National). An example of this situation is the Sierra Helada Marine Natural Park (SHMP) in Alicante. Within its territorial scope there are 3 MPAs with different protection figures that overlap each other, SHMP, the Natura 2000 site of Serra Gelada i la Marina Baixa and a fishing protected area. These MPAs are managed by different regional governmental bodies, and have a natural resources action plan in use, supported by a management collaboration agreement with the town councils in the area and the Altea Nautical Club. In the SHMP, Posidonia oceanica (PO) is one of the most important ecosystems and its presence prompted its creation and declaration. PO is a marine angiosperm endemic to the Mediterranean Sea that forms extensive meadows from the sea surface to 30–40 m depth and which provides essential goods and services: it improves water quality and protect beaches against erosion. PO meadows are recognized as biodiversity hotspots, and as major carbon sinks, but they are very sensitive to human activities. However, although many regulations protect PO, there are still significant threats to their conservation.
In this regard, the research presented in this paper is the development of an ICT-based software tool, called Smart MPA, that includes an analysis framework based on management and governance indicators specific for PO and a database on PO that includes and combines different sources of information, including the results obtained of the evaluation of the analytical framework, input from information from citizens or MPA users, for example, by sending photos to report infractions in PO at specific points and from satellite images or underwater UAVs. The main objective of the Smart MPA tool is to offer services applied to PO management, either through the analysis of governance indicators or by facilitating the integration of citizen information to be used in management activities. The tool has been tested and used by the management staff of SHMP to be applied to an annual monitoring of management measures to develop an adaptive management of PO and the SHMP. After that, a semi-structured interview was carried out to collect information on the analytical framework co-developed and a survey was created where management staff of SHMP have given their perception on the usability of the tool and on the environmental problems affecting the conservation of PO in SHMP. According to the results obtained, the management of PO in SHMP is efficient, at a general level, with the lack of adequate funding being a limiting factor. The main threats are boat anchoring and organic pollution. In conclusion, the Smart MPA tool and the analytical framework are instruments that can facilitate the management and promote good environmental governance processes for the conservation of PO meadows in SHMP. At the same time, the importance of exploring mobile apps to increase citizen participation and mitigate threats and impacts on PO have been highlighted.
... It also appears that the percentage and size of the bioclastic fraction of beach sands increase in low wave-energy environments where large seagrass meadows (e.g. Short, 2002) or tidal flats (Neal et al., 2002;Weill et al., 2012) promote an intense carbonate production (De Falco et al., 2017), and where shell breaking is moderate. Accordingly, the sediment used in the experiment was composed of an artificial mixture of coarse bioclastic sand and granule, and finer siliciclastic sand. ...
Coastal barriers are dynamic systems, the morphology and architecture of which are controlled by local hydrodynamics, sea‐level fluctuations at different timescales, geological heritage and sediment composition. Coastal barriers may be composed of siliciclastic sediments, bioclastic sediments, or a mixture of both. Mixed siliciclastic–bioclastic sediments (as common as ‘pure’ sediments) are still little represented in the literature. Changes in sediment composition could affect sedimentary processes which are involved in the construction and stability of coastal barriers due to a different hydrodynamic behaviour between bioclastic and siliciclastic particles. In this study, wave‐flume experiments were used to investigate the role of sediment compositional mixing on the morphology and architecture of coastal barriers. Three different siliciclastic/bioclastic mixtures were exposed to regular wave forcing, together with mean water level fluctuations to create regressive and transgressive depositional units. Compositional mixtures responded similarly in first‐order to mean water‐level fluctuations, with the formation of a bar at low water level. Its subsequent on‐shore migration and reworking as berm deposits during rising water level stages, and with the formation of washover deposits during high water level stages. In detail, the increasing content of bioclastic sediment increased the beachface slope and reduced the length of washover deposits. The faster aggradation of washover sheets with bioclastic‐rich mixtures accelerated the barrier recovery after a submersion and breaching event. A strong segregation between the siliciclastic and the bioclastic grains was observed in the different depositional units, which is attributed both to the coarse size (grain‐size control) and to the flat‐shape (compositional control) of the bioclastic particles.
... A quantitative study of the contribution of biogenic sediments produced in Posidonia oceanica meadows and photophilic algal communities to the sediment budget of a Mediterranean beach-dune system of an Italian beach found that 83% of sediments were in the coastal wedge, 16% in the dune fields and only 1% in the subaerial beach (De Falco et al. 2017). These sediments were composed of bioclastic and non-bioclastic grains from various sources, particularly from Posidonia oceanica meadows that were transported to the beachdune system. ...
... It is quite interesting to note that there was no mention of presence of Egagropili in these sediments. There is a possibility that the presence of Egagropili in these sediments were ignored by De Falco et al. (2017). ...
Kumar A. 2022. Egagropili Sand Dunes (Holocene) along the southeastern Gulf of Sirte (Mediterranean Sea) coast of Brega, Libya: their genesis and palaeoenvironmental implications. Geophytology 52(1&2): 29-38. The beaches around the coastal town Brega, Libya, are covered with Posidonia oceanica banquettes and millions of scattered predominantly spherical Egagropili of various sizes. Isolated areas of Egagropili sand sheets and sand dunes are the characteristic geomorphological feature of the Brega coast. Formation of Egagropili sand sheets and sand dunes goes through the following five stages: 1. Formation of Egagropili under shallow marine environment, 2. Deposition of Posidonia oceanica banquettes on the beaches, 3. Desiccation of dead leaves and concentration of Egagropili, 4. Formation of Egagropili sand sheets, and 5. Formation of Egagropili sand dunes. Predominant westerly winds between October and March play a major role in transporting dead leaves of Posidonia oceanica and associated Egagropili from shallow marine environments over the adjacent beaches. Another wind pattern, Ghibli, is a hot and arid wind that blows from south towards north all over Libya several times a year which is responsible for carrying large quantities of sand from the Sahara region to the Mediterranean coast. A combination of these two wind patterns is responsible for the formation of Egagropili sand dunes. These sand dunes are suggested to be of Holocene age, and they are palaeoenvironmentally significant. Egagropili sand dunes of the Brega coast are distinctive Holocene deposits, where all the biological, environmental, and atmospheric factors responsible for their formation can be concurrently observed in modern times.
... The seismic unit U4, characterized by landward prograding reflectors is interpreted as washover deposits of the back-barrier sector (Shan et al., 2016; Mellett et al., 2012). The seismic unit U6, characterized by seaward prograding reflectors is interpreted as the shoreface deposits of the barrier system (De Falco et al., 2017;Pascucci et al., 2018;Salzmann et al., 2013). The seismic units U3a, composed by organic-rich mud, was interpreted as back-barrier lagoonal deposits (Fig. 8). ...
We performed a morpho-stratigraphic study of the Tirso River incised valley (Sardinia Island, western Mediterranean Sea), an erosional feature crossing the Sinis fault, a major normal fault bordering the Campidano basin between the Gulf of Oristano and the western Sardinia shelf. High-resolution seismic reflection profiles and multibeam echosounder data, integrated by age-constrained stratigraphic logs derived from 9 sediment cores enabled us to reconstruct the valley evolution during the Holocene. We found that the Tirso valley is the result of a single event of incision and infill during the last eustatic cycle, strongly controlled by the presence of the Sinis fault. In fact, this structure represents a geological threshold that marks an abrupt change in substrate lithology and seabed slope, which controlled the valley morphology, narrow when downcutting early Pliocene formations along the steeper open shelf, and wider inside the Gulf, in the Pleistocene alluvial deposits of the flatter Gulf of Oristano. The sedimentary record starts with alluvial sediments filling the valley along the shelf during the initial phase of sea level rise, i.e., over 10 ka. During the last ~9.0 ka, a bay head delta developed, with the formation of barriers at the gulf entrance. In the mid-late Holocene, the progressive sea-level rise led to rapid drowning of the barrier system, recorded by marine and estuarine sediments filling the valley. Analysis of ecological associations in the cores, collected along a valley-normal transect, allowed for a detailed reconstruction of the paleo-environmental conditions during the latest phase of the incised valley filling controlled by global climatic variations in the Mediterranean region between ~9.0 and ~ 4.5 ka. Together with eustasy, our work reveals that the evolution and sedimentary infill of the Tirso incised valley was strongly controlled by inherited geological constraints, which influenced the morphology of the valley and the stratigraphic pattern.
... Este fornecimento sedimentar do sistema praial para o dunar ocorre basicamente em três ambientes sedimentares -siliciclástico, carbonático e/ou misto. De Falco et al. (2017) destacam que no caso das praias carbonáticas e mistas, a produção e o acúmulo de partículas carbonáticas nos ecossistemas costeiros nearshore contribui para o balanço sedimentar do sistema praia-duna, onde aproximadamente 28% de tudo que é transportado pelo sistema praia-duna são partículas carbonáticas. Já nas praias com predomínio de material siliciclástico, os principais componentes são comumente os grãos de quartzo e os minerais pesados (Nascimento Jr et al., 2017;Vieira e Manso, 2017). ...
... t/século, sendo que 28% deste valor são transportados para o sistema praiaduna, aonde a taxa deposicional moderna de bioclastos na praia-duna é de 46.000±5.000 t/século, o que representa ~1,2% da massa sedimentar do sistema praiaduna (De Falco et al., 2017). Desta forma, evidencia-se a importância de compreender a taxa de produção carbonática no setor marinho raso e o quanto é transportado para o sistema praia-duna. ...
A interação morfosedimentar no sistema praia-duna apresenta importante papel para o balanço sedimentar costeiro, no entanto, o fornecimento carbonático do ambiente marinho-raso para o ambiente litorâneo é pouco compreendido. Desta forma, o objetivo deste trabalho foi analisar a sedimentação de siliciclásticos e de bioclásticos ao longo da superfície interposta do sistema praia-duna num trecho da Praia do Preá, porção Noroeste do Estado do Ceará. Para isto, foram realizadas coletas superficiais de sedimentos na zona de estirâncio e na superfície de deflação eólica. Em complemento, também foram analisados os sedimentos aprisionados em armadilhas de transporte eólico, permitindo compreender o fluxo de transporte eólico de areias marinhas para formação dos campos de dunas parabólicas. Os resultados da análise sedimentar indicam que os principais componentes siliciclásticos foram o quartzo e a mica, enquanto nos materiais de natureza carbonática, houve o predomínio de algas calcárias, moluscos e foraminíferos. Foi verificada uma nítida tendência de granodecrescência, com melhoria no selecionamento e queda percentual dos bioclastos da zona de praia para o sistema eólico, sendo que os principais vetores de transporte são orientados predominantemente entre NNE e E através da hidrodinâmica e aerodinâmica. O fluxo eólico é responsável pelo selecionamento diferencial dos componentes bioclásticos x siliciclásticos, em que as algas calcárias apresentam uma grande contribuição no transporte na fração de areia fina. Este tipo de bioclasto é predominante no sistema eólico, enquanto os moluscos e foraminíferos, principalmente os primeiros, se concentram no sistema praial. A compreensão do selecionamento diferencial entre bioclastos x siliciclásticos é fundamental para o entendimento da dinâmica morfosedimentar entre os ambientes praial e dunares em sistemas de natureza mista siliciclástica-carbonática.
... Despite their small number, seagrasses play a role of paramount importance in coastal habitats worldwide. They provide ecological goods and ecosystem services that contribute to human welfare, e.g., habitat for a wide diversity of species, nursery, enhanced fisheries, nutrient cycling, carbon sequestration, production of sand (the "sand factory"), beach, and shoreline protection [5][6][7][8][9][10]. In the Mediterranean Sea, seven species of seagrasses occur [11,12]. ...
Some species of seagrasses (e.g., Zostera marina and Posidonia oceanica) have declined in the Mediterranean, at least locally. Others are progressing, helped by sea warming, such as Cymodocea nodosa and the non-native Halophila stipulacea. The decline of one seagrass can favor another seagrass. All in all, the decline of seagrasses could be less extensive and less general than claimed by some authors. Natural recolonization (cuttings and seedlings) has been more rapid and more widespread than was thought in the 20th century; however, it is sometimes insufficient, which justifies transplanting operations. Many techniques have been proposed to restore Mediterranean seagrass meadows. However, setting aside the short-term failure or half-success of experimental operations, long-term monitoring has usually been lacking, suggesting that possible failures were considered not worthy of a scientific paper. Many transplanting operations (e.g., P. oceanica) have been carried out at sites where the species had never previously been present. Replacing the natural ecosystem (e.g., sandy bottoms, sublittoral reefs) with P. oceanica is obviously inappropriate in most cases. This presupposes ignorance of the fact that the diversity of ecosystems is one of the bases of the biodiversity concept. In order to prevent the possibility of seagrass transplanting from being misused as a pretext for further destruction, a guide for the proper conduct of transplanting is proposed.
... progradation, erosion), grain size features and castashore organic debris (e.g. macroalgae, driftwood and seagrass dead leaves) during intense storms, over a year span and between years (Simeone et al., 2014(Simeone et al., , 2016De Falco et al., 2017). ...
Sandy beaches, together with the foredune and the dune, form a morphological, functional and ecological complex, the beach-dune complex. This complex provides ecosystem services which have by far the highest value in the coastal areas, both marine and terrestrial habitats considered; it requires an overall management approach. Sandy beaches are often wrongly perceived by the public at large and by stakeholders as 'ecological deserts', the value of which is mainly economic. In fact, beaches harbour an extraordinary range of biological diversity, with dozens of species, plant and animal, which are specific to them. This biological diversity is sometimes not very visible, due to the small size of the individuals, the fact that they live hidden in the sand and their rarity on beaches artificialized by inappropriate management. Mediterranean beaches are unique worldwide by virtue of the permanent, or not, presence of accumulations of dead leaves of the endemic seagrass Posidonia oceanica. These accumulations, up to 2.5 m in thickness, are called banquettes. They play a prominent role in protecting beaches from erosion. In addition, they contribute to the construction of the dune. Eventually, sooner or later, dead leaves from the banquette will return to the sea, where they constitute a major source of organic matter and nutrients, for the benefit of coastal ecosystems and artisanal fisheries. The Mediterranean coastal regions welcome much of the world's tourism. This tourism is to a large extent seaside beach-based tourism. In the 1980s, after a century of Posidonia-compatible seaside tourism, tourism operators and mayors of coastal cities began to 'sell' Posidonia-free beaches and accustom tourists to unnatural, groomed, 'clean' beaches. Clean beaches were now free of human-made detritus, which is a positive factor, but also of naturally beach-cast P. oceanica dead leaves, seaweed, driftwood and even shells. It is not clear whether the concept of Posidonia-free beaches actually corresponds to tourists' requirements, or to the tour-operators' and mayors' own perceptions. Experiments involving maintaining in place the Posidonia banquettes, with information boards explaining the ecological and management issues, seem to indicate the latter. In any case, removing banquettes, driftwood, etc., results in a dramatic impoverishment of the beach biota: until recently, beaches were anything but deserts, but that is what they are becoming-24-now! In addition, the Posidonia-free beach doctrine has resulted in catastrophic economic losses. Beaches, the cornerstone of seaside tourism, now unprotected, are washed away by storms and costly sand replenishment accelerates their erosion in a kind of vicious circle. This represents a paradigm example of mismanagement and of its costly consequences. It is probably time to promote the spread of 'ecological beaches', i.e. Posidonia-compatible beaches, in order to save the seaside tourism industry, the financial resources of local authorities and, of course, Mediterranean biodiversity. Well-managed beaches are a typical example of what is now referred to as a socio-ecosystem: an ecosystem of which man is a part. This of course means that they must be managed in a sustainable way, retaining their natural characteristics, or most of them, their long-term durability, and finally their value as a symbol of the Mediterranean identity, a vital asset for 21 st century tourism. Résumé. La grande valeur patrimoniale des plages de sable de Méditerranée, avec une attention spéciale pour les banquettes de Posidonia oceanica : une revue. Les plages, associées à l'avant-dune et à la dune d'arrière-plage, constituent un écosystème, c'est-à-dire un ensemble géomorphologique, écologique et fonctionnel qui ne peut pas être dissocié, que ce soit du point de vue de l'écologie, des services écosystémiques et de la gestion des usages. Les services écosystémiques (les bénéfices que la nature fournit à l'Homme) que produit l'écosystème plage-dune sont exceptionnellement élevés : plus de 100 000 $/ha/an, soit 4 fois plus que les herbiers marins et presque 30 fois plus que les forêts terrestres. Le public et les gestionnaires considèrent parfois les plages comme un désert biologique, avec quelques 'mauvaises herbes' près de la dune. C'est pourtant tout le contraire. Les plages hébergent une incroyable diversité biologique, avec des dizaines d'espèces (crustacés, insectes, araignées, plantes, etc.) qui leur sont spécifiques et des milliers d'individus par mètre carré. Cette richesse est certes peu visible, en raison de la petite taille des individus, de leur mode de vie caché dans le sable (surtout le jour) et de leur rareté sur les plages déstructurées par un mode de gestion inapproprié. Toutefois, cette diversité biologique joue un rôle important dans le fonctionnement de l'écosystème, en relation avec les autres écosystèmes littoraux, par exemple par l'intermédiaire des oiseaux. Beaucoup de ces espèces sont devenues tellement rares qu'elles sont aujourd'hui considérées comme menacées. Une des originalités, à l'échelle mondiale, des plages méditerranéennes est la présence, permanente ou non, de feuilles mortes de la magnoliophyte (plante à fleurs) endémique Posidonia oceanica. On nomme 'banquettes' (en français comme en anglais ; un terme issu du vocabulaire des pêcheurs provençaux) ces accumulations de feuilles mortes, qui peuvent atteindre, dans des cas exceptionnels, 2.5 m d'épaisseur. Les banquettes jouent un rôle écologique et économique important. Elles protègent directement les plages contre l'érosion et le départ du sable. Elles alimentent la dune en feuilles mortes et en sels nutritifs et contribuent à son édification et, indirectement, à la stabilité de la plage. Les feuilles mortes de la banquette ont vocation à retourner en grande partie, au gré des tempêtes, au milieu marin, où elles constituent une ressource alimentaire majeure, directe pour les écosystèmes littoraux et indirecte pour la ressource halieutique dont dépend la pêche artisanale. La Méditerranée constitue la première destination touristique mondiale. Le tourisme y est basé sur le patrimoine culturel, gastronomique, paysager, mais aussi, parfois surtout, sur les plages et les activités balnéaires. Il représente une part importante du PNB des pays riverains. Dans les années 1980s, après un siècle de tourisme posidonies-compatible et des millénaires de plages dévolues aux banquettes de posidonies, les opérateurs du tourisme et certains maires de communes littorales ont 'vendu' le concept de plages artificiellement 'propres', c'est-à-dire libres de posidonies, et ont accoutumé les touristes à les revendiquer. Le 'nettoyage' des plages, qui fait souvent appel à des engins lourds, constitue la première étape d'un dramatique 'cercle vicieux'. Les plages, désormais non-protégées, sont emportées lors des tempêtes ; il s'ensuit de coûteuses opérations de ré-ensablement ; ce sable, emporté à son tour, ensevelit et détruit les herbiers adjacents de P. oceanica ; or ces herbiers protègent également les plages contre l'érosion ; leur régression accélère donc le recul des plages.-25-Au total, il s'agit d'un cas d'école pour la définition d'un 'cercle vicieux' très coûteux pour l'environnement comme pour les finances des communes littorales. Les usagers, les touristes en particulier, demandent-ils réellement des plages sans banquettes, ou cette demande constitue-t-elle une construction due aux opérateurs du tourisme ? Il semble bien que la réponse soit : un artéfact construit, en particulier, par les opérateurs du tourisme. En effet, partout où les banquettes sont maintenues en place, y compris en été, dans le cadre du concept de 'plages écologiques', c'est-à-dire d'un nettoyage préservant les feuilles de posidonies et les bois flottés naturels, et où les usagers sont informés des enjeux (par des panneaux, des brochures, la presse, les agents du parc, etc.), l'acceptation est bonne et la fréquentation ne diminue pas. Les plages sont tout sauf des déserts : ce sont au contraire des habitats d'une grande richesse biologique et d'une grande valeur patrimoniale. C'est une gestion inadaptée qui les transforme en déserts, déserts par ailleurs coûteux pour l'économie (tourisme et pêche en particulier). Les plages de Méditerranée constituent l'exemple-paradigme des conséquences économiques et écologiques négatives d'une gestion naïve, contre-productive et à très court terme. Les 'plages écologiques', posidonies-compatibles, constituent au contraire un symbole fort de l'identité méditerranéenne et un atout pour le tourisme durable, en plus de la préservation de la biodiversité, et bien au-delà des espaces protégés qui ont vu naître le concept. Les plages bien gérées constituent un exemple typique de ce que l'on désigne aujourd'hui sous le nom de socio-écosystème : un écosystème dont l'homme fait partie. Cela implique bien sûr qu'elles soient gérées de façon durable, en conservant leurs caractéristiques naturelles, ou la plupart d'entre elles, et non comme des systèmes artificiels, des sortes d'anthroposystèmes.
