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Open AccessArticle

The Mediterranean Dune–Beach–Banquette Ecosystem, Its Pivotal Role in Land–Sea Coupling and the Functioning of Coastal Systems, and Some Related Management Issues

by Charles-François Boudouresque, Patrick Astruch, Bruno Belloni, Aurélie Blanfuné, Charlotte Francesiaz, Maële Maury, Frédéric Médail, Guilhan Paradis, Michèle Perret-Boudouresque, Carole Piazza, Philippe Ponel, Pauline Sindou and Thierry Thibaut

Sustainability 2025, 17(10), 4556; https://doi.org/10.3390/su17104556 - 16 May 2025

Viewed by 1320

Abstract

In the Mediterranean, the dune–beach ecosystem is characterized by the presence of thick deposits of dead leaves of the endemic seagrass Posidonia oceanica, called banquettes (Dune–Beach–Banquette ecosystem—DBB). This ecosystem plays an important role in the coupling between sea and land. The banquettes [...] Read more.

In the Mediterranean, the dune–beach ecosystem is characterized by the presence of thick deposits of dead leaves of the endemic seagrass Posidonia oceanica, called banquettes (Dune–Beach–Banquette ecosystem—DBB). This ecosystem plays an important role in the coupling between sea and land. The banquettes provide important ecosystem services: protection of beaches against erosion, contribution to the building of the dune, and a source of nitrogen for coastal vegetation. They are home to a rich and diverse invertebrate fauna that are consumed by other predatory invertebrates and seabirds. A conceptual model of the functioning of the DBB ecosystem and its relation with adjacent ecosystems has been outlined. When dead P. oceanica leaves return to the sea, which is the fate of most of the banquette, they constitute an important source of carbon and nutrients for coastal ecosystems and fisheries. Beach management, with the removal of banquettes and driftwood to meet the supposed requirements of beach users and tourists, is an ecological disaster, in addition to being an economic burden for coastal municipalities. Beach management methods that respect the interactions between the marine and terrestrial realms, which preserve the beaches from erosion and allow the return of the banquettes to the sea, and which take into account the real perceptions of beach users are feasible in the framework of the concept of the ‘ecological beach’. Full article

(This article belongs to the Section Sustainable Oceans)

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14 pages, 3439 KB

Open AccessArticle

Ecological Implications of Posidonia oceanica Banquette Removal: Potential Loss of Natural Capital and Ecosystem Services

by Ilaria Dentamare, Ludovica Capasso, Elena Chianese, Rosalia Calicchio, Pier Paolo Franzese, Umberto Grande, Giovanni Fulvio Russo and Elvira Buonocore

Water 2025, 17(9), 1362; https://doi.org/10.3390/w17091362 - 1 May 2025

Viewed by 792

Abstract

Posidonia oceanica is an endemic seagrass of the Mediterranean Sea, forming extensive meadows and providing valuable ecosystem services underwater as well as on the shore. P. oceanica constantly generates new leaves while shedding the older ones. The latter may be deposited on the [...] Read more.

Posidonia oceanica is an endemic seagrass of the Mediterranean Sea, forming extensive meadows and providing valuable ecosystem services underwater as well as on the shore. P. oceanica constantly generates new leaves while shedding the older ones. The latter may be deposited on the shoreline, forming “banquettes” that exhibit variable thickness, ranging from a few centimeters to several meters. These deposits act as natural barriers against coastal erosion, preventing sand loss and dissipating wave energy. Moreover, the degradation of the washed-up leaves releases large amounts of nutrients, relevant for the coastal food web. However, the presence of banquettes in touristic areas is often perceived as a nuisance, thus leading to their removal by local administrations. This study proposes a multidisciplinary approach for the assessment of P. oceanica banquettes along the coastline of the Campania region (Southern Italy), estimating their biomass and the associated concentrations of nutrients and other chemical elements, with the final aim to assess the potential loss of natural capital and ecosystem services due to their removal. Regional estimates show that approximately 40 tons of C are stored annually in the beached biomass, representing a potential carbon loss associated with their removal. The results highlight the crucial role that P. oceanica banquettes play in the blue carbon cycle and provide valuable insights to support their sustainable management. Full article

(This article belongs to the Special Issue Implementation of Biodiversity and Ecosystem Services in Marine Ecosystem Management, 3rd Edition)

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13 pages, 544 KB

Open AccessPerspective

Towards Sustainable Management of Beach-Cast Seagrass in Mediterranean Coastal Areas

by Loredana Manfra, Stefania Chiesa, Simone Simeone, Patrizia Borrello, Raffaella Piermarini, Chara Agaoglou, Monia Elbour, Noureddine Zaaboub, Dimitris Vandarakis, Ioannis Kourliaftis, Alfonso Scarpato and Alice Rotini

Sustainability 2024, 16(2), 756; https://doi.org/10.3390/su16020756 - 16 Jan 2024

Cited by 5 | Viewed by 2112

Abstract

Marine environmental conservation and tourist exploitation are often in conflict, particularly where anthropogenic pressure is greatest, such as along the coasts of the Mediterranean Sea. A case in point is the accumulation of beach-cast seagrass, a typical feature of the Mediterranean Sea that [...] Read more.

Marine environmental conservation and tourist exploitation are often in conflict, particularly where anthropogenic pressure is greatest, such as along the coasts of the Mediterranean Sea. A case in point is the accumulation of beach-cast seagrass, a typical feature of the Mediterranean Sea that is nowadays perceived as an “obstacle” to tourist activities and thus treated and removed as waste, leading to environmental impacts. In this paper, we analyzed the legislative context at the Mediterranean basin level and the contribution of twenty virtuous research projects related to the topic. In our opinion, the main benefits for the beach–dune ecosystem would be generated by the use of seagrass banquettes directly within the beach system (temporary displacement, creating beach walkways, dune consolidation), while their uses outside the beach system (agricultural and farm solutions—compost and bedding) should be considered as alternative solutions for a circular economy, in case of consistent biomass deposits along the shores. In this perspective, we support the “Ecological Beach” model which integrates most of the science-derived solutions addressed in this study. This model provides good practices that can be usefully spread and shared along Mediterranean coasts: to achieve this result, it is necessary to create a regional or Mediterranean network involving local communities and stakeholders. Full article

(This article belongs to the Special Issue Life below Water: Marine Biology and Sustainable Ocean—2nd Edition)

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21 pages, 58703 KB

Open AccessFeature PaperArticle

A Four-Year Video Monitoring Analysis of the Posidonia oceanica Banquette Dynamic: A Case Study from an Urban Microtidal Mediterranean Beach (Poetto Beach, Southern Sardinia, Italy)

by Daniele Trogu, Simone Simeone, Andrea Ruju, Marco Porta, Angelo Ibba and Sandro DeMuro

J. Mar. Sci. Eng. 2023, 11(12), 2376; https://doi.org/10.3390/jmse11122376 - 16 Dec 2023

Cited by 4 | Viewed by 2084

Abstract

This paper investigates the dynamics of the cross-shore extensions of banquettes, a sedimentary structure mostly made by rests of Posidonia oceanica (L.) Delile, in a sandy urban beach located in the Gulf of Cagliari, Italy, western Mediterranean. A video monitoring station was installed [...] Read more.

This paper investigates the dynamics of the cross-shore extensions of banquettes, a sedimentary structure mostly made by rests of Posidonia oceanica (L.) Delile, in a sandy urban beach located in the Gulf of Cagliari, Italy, western Mediterranean. A video monitoring station was installed above the promontory south of the beach. We analysed a four-year image database and related these dynamics to wave and wind parameters (obtained from the Copernicus and ERA5 databases) from September 2016 to September 2020. Our results showed that banquette deposition occurred in concomitance with the presence of leaf litter in the surf zone associated with mild storm events. Erosion of the banquettes occurred during more intense storms. When leaf litter was not present in the surf zone, banquettes were not deposited even with mild storms. Wind can influence the banquette dynamics: under certain conditions of speed intensity, the banquettes may be removed offshore, supplying litter in the surf zone, or they may be covered by sediment. The permanence of the banquettes on the beaches also depended on their composition: when the banquettes were intertwined with reeds, their removal by the waves did not occur even during intense storms, and this sedimentary structure can protect the beach from flooding. Full article

(This article belongs to the Special Issue Advances in Coastal Hydrodynamic and Morphodynamic Processes under a Changing Climate)

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18 pages, 3003 KB

Open AccessReview

Sustainable Exploitation of Posidonia oceanica Sea Balls (Egagropili): A Review

by Odile Francesca Restaino, Concetta Valeria L. Giosafatto, Seyedeh Fatemeh Mirpoor, Marcella Cammarota, Sondos Hejazi, Loredana Mariniello, Chiara Schiraldi and Raffaele Porta

Int. J. Mol. Sci. 2023, 24(8), 7301; https://doi.org/10.3390/ijms24087301 - 14 Apr 2023

Cited by 22 | Viewed by 7998

Abstract

Posidonia oceanica (L.) Delile is the main seagrass plant in the Mediterranean basin that forms huge underwater meadows. Its leaves, when decomposed, are transported to the coasts, where they create huge banquettes that protect the beaches from sea erosion. Its roots and rhizome [...] Read more.

Posidonia oceanica (L.) Delile is the main seagrass plant in the Mediterranean basin that forms huge underwater meadows. Its leaves, when decomposed, are transported to the coasts, where they create huge banquettes that protect the beaches from sea erosion. Its roots and rhizome fragments, instead, aggregate into fibrous sea balls, called egagropili, that are shaped and accumulated by the waves along the shoreline. Their presence on the beach is generally disliked by tourists, and, thus, local communities commonly treat them as waste to remove and discard. Posidonia oceanica egagropili might represent a vegetable lignocellulose biomass to be valorized as a renewable substrate to produce added value molecules in biotechnological processes, as bio-absorbents in environmental decontamination, to prepare new bioplastics and biocomposites, or as insulating and reinforcement materials for construction and building. In this review, the structural characteristics, and the biological role of Posidonia oceanica egagropili are described, as well as their applications in different fields as reported in scientific papers published in recent years. Full article

(This article belongs to the Special Issue Novel Bio-Based Materials from Renewable Sources)

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13 pages, 2941 KB

Open AccessArticle

Sediment Budget Implications from Posidonia oceanica Banquette Removal in a Starved Beach System

by Simone Simeone, Antonio Gian Luca Palombo, Fabio Antognarelli, Walter Brambilla, Alessandro Conforti and Giovanni De Falco

Water 2022, 14(15), 2411; https://doi.org/10.3390/w14152411 - 3 Aug 2022

Cited by 7 | Viewed by 3027

Abstract

This study discusses the potential impact of removing Posidonia banquette on the sediment budget of a siliciclastic-sediment-starved beach-barrier system. The morphology as well as the sediment volumes of this system were estimated. The banquette’s composition and sediment content were determined with samples collected [...] Read more.

This study discusses the potential impact of removing Posidonia banquette on the sediment budget of a siliciclastic-sediment-starved beach-barrier system. The morphology as well as the sediment volumes of this system were estimated. The banquette’s composition and sediment content were determined with samples collected during five sampling campaigns conducted in one year. The carbonate content of the system was estimated by analyzing three 1 m long cores collected along the barrier. Five digital terrain models from DGPS surveys were used to compute the beach’s average morphology to estimate the sediment volumes. The carbonate and siliciclastic sediment content from the cores were used to calculate the overall beach’s sediment mass. Total sediment mass accounted for 126,000 m³, of which ca. 86% was siliciclastic quartz sand and approximately 14% was carbonate sediment. Total banquette deposition during the year accounted for 2300 m³, with a maximum and averaged sediment content of 339 kg m³ and 78 kg m⁻³. A permanent loss of ca. 1.31% of total mass will occur if 5000 m³ of banquette were to be removed. In such beach settings, banquette removal may limit sediment availability, reducing the overall sediment mass and decreasing beach resilience against climate change effects such as sea level rise. Full article

(This article belongs to the Special Issue Coastal Systems Research: Environments, Geomorphology and Sedimentary Processes)

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6 pages, 918 KB

Open AccessCommunication

Deposition Dynamics of Posidonia oceanica “Banquettes” on Calabrian Sandy Beaches (Southern Italy)

by Nicola Cantasano

Coasts 2021, 1(1), 25-30; https://doi.org/10.3390/coasts1010002 - 28 Oct 2021

Cited by 5 | Viewed by 4058

Abstract

The deposition of Posidonia oceanica leaves on the sandy beaches of the Calabrian region could be one of the most important defence mechanisms against erosion processes. The management of Posidonia oceanica leaf litter in Italy has been realised through the mechanical removal and [...] Read more.

The deposition of Posidonia oceanica leaves on the sandy beaches of the Calabrian region could be one of the most important defence mechanisms against erosion processes. The management of Posidonia oceanica leaf litter in Italy has been realised through the mechanical removal and transport in dumping areas of the beach-cast material. This solution, apparently simple and fast, produces a net loss of sediments from sandy beaches and, therefore, a deficit in the sedimentary budget of the coastline, leading the coastal system to possible shore erosions. Instead, it could be better to keep these vegetable deposits in place to warrant a positive sedimentary budget and to increase the tourist value of regional beaches, improving coastal tourism in seaside resorts with opportunities for bathing. Full article

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16 pages, 2306 KB

Open AccessEditor’s ChoiceArticle

Effectiveness of the “Ecological Beach” Model: Beneficial Management of Posidonia Beach Casts and Banquette

by Alice Rotini, Stefania Chiesa, Loredana Manfra, Patrizia Borrello, Raffaella Piermarini, Cecilia Silvestri, Sergio Cappucci, Luca Parlagreco, Saverio Devoti, Marco Pisapia, Carla Creo, Tiziana Mezzetti, Alfonso Scarpato and Luciana Migliore

Water 2020, 12(11), 3238; https://doi.org/10.3390/w12113238 - 19 Nov 2020

Cited by 28 | Viewed by 6291

Abstract

The accumulation of Posidonia oceanica dead leaves on the beaches of the Mediterranean shores is a natural phenomenon. They are either temporary or permanent structures (banquettes) and represent a valuable resource, with important ecosystem functions including coastal protection against erosion. Nevertheless, [...] Read more.

The accumulation of Posidonia oceanica dead leaves on the beaches of the Mediterranean shores is a natural phenomenon. They are either temporary or permanent structures (banquettes) and represent a valuable resource, with important ecosystem functions including coastal protection against erosion. Nevertheless, the perception of these plant accumulations by the different stakeholders (beach managers, local administrations and tourists) is often negative; they consider these deposits a malevolent waste to be removed, rather than a natural and valuable component of the coastline. We propose an integrated/beneficial management model for posidonia deposits, called ECOLOGICAL BEACH, firstly proposed in France, and recently implemented and applied in Italy. The model promotes the preservation of posidonia beach casts on site, with a balanced coexistence of natural and anthropic elements. The model fosters the several important ecosystem services of the beach casts and contributes to coastal preservation. To successfully spread the model, several activities must be implemented: a regulatory framework, the collection of data about the occurrence of beach casts, management protocols and educational programs. The most important activity is the educational one, based on the dissemination of the ecological and economic value of the beach casts, aimed at switching the perception of this phenomenon towards positive appraisal. Full article

(This article belongs to the Special Issue Aquatic Ecosafety: Threats, Disturbances, Environmental Monitors and Bioremediation Actions)

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18 pages, 3861 KB

Open AccessFeature PaperArticle

Posidonia oceanica as a Source of Chromophoric Dissolved Organic Matter for the Oligotrophic NW Mediterranean Coast

by Francesca Iuculano, Carlos M. Duarte, Jaime Otero, Xosé Antón Álvarez-Salgado and Susana Agustí

J. Mar. Sci. Eng. 2020, 8(11), 911; https://doi.org/10.3390/jmse8110911 - 12 Nov 2020

Cited by 2 | Viewed by 2848

Abstract

Posidonia oceanica is a well-recognized source of dissolved organic matter (DOM) derived from exudation and leaching of seagrass leaves, but little is known about its impact on the chromophoric fraction of DOM (CDOM). In this study, we monitored for two years the optical [...] Read more.

Posidonia oceanica is a well-recognized source of dissolved organic matter (DOM) derived from exudation and leaching of seagrass leaves, but little is known about its impact on the chromophoric fraction of DOM (CDOM). In this study, we monitored for two years the optical properties of CDOM in two contrasting sites in the Mallorca Coast (Balearic Islands). One site was a rocky shore free of seagrass meadows, and the second site was characterized by the accumulation of non-living seagrass material in the form of banquettes. On average, the integrated color over the 250–600 nm range was almost 6-fold higher in the beach compared with the rocky shore. Furthermore, the shapes of the CDOM spectra in the two sites were also different. A short incubation experiment suggested that the spectral differences were due to leaching from P. oceanica leaf decomposition. Furthermore, occasionally the spectra of P. oceanica was distorted by a marked absorption increase at wavelength < 265 nm, presumably related to the release of hydrogen sulfide (HS⁻) associated with the anaerobic decomposition of seagrass leaves within the banquettes. Our results provide the first evidence that P. oceanica is a source of CDOM to the surrounding waters. Full article

(This article belongs to the Special Issue Advances in Marine Dissolved Organic Matter Dynamics)

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27 pages, 47227 KB

Open AccessArticle

The Management of the Beach-Cast Seagrass Wracks—A Numerical Modelling Approach

by Andrea Cucco, Giovanni Quattrocchi, Walter Brambilla, Augusto Navone, Pieraugusto Panzalis and Simone Simeone

J. Mar. Sci. Eng. 2020, 8(11), 873; https://doi.org/10.3390/jmse8110873 - 3 Nov 2020

Cited by 14 | Viewed by 3124

Abstract

Seagrass wrack are commonly found on the beach face of the sandy shore all around the world and often persists in situ during the whole year, favouring the emergence of conflicts for the use of the sandy coasts for bathing or for other [...] Read more.

Seagrass wrack are commonly found on the beach face of the sandy shore all around the world and often persists in situ during the whole year, favouring the emergence of conflicts for the use of the sandy coasts for bathing or for other recreational purposes. As a consequence, these deposits are often removed from the beach during the summer months, temporary stocked, and relocated on the shore face in the next autumn or winter season. The selection of the sites on the shoreline where the leaves should be released before the storms season is often an issue, considering the optimization needs between the transportation costs and the oceanographic features of the dumping site. In this study, a numerical approach was proposed to identify the most suitable areas for the autumnal repositioning of the seagrass wracks for two beaches of Sardinia, an island located in the Western Mediterranean Sea where Posidonia oceanica (L. Delile, 1813) is the most widespread seagrass species. The method is based on the use of hydrodynamic, wave, and particle tracking models and provides important indications useful for the management of this type of practice that can be extended to all different type of beaches along the Mediterranean coasts. Full article

(This article belongs to the Special Issue Novel Technologies and Solutions for Coastal Evolution and Management)

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