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The search for bioactive natural compounds, traditionally focused on terrestrial environments, has increasingly expanded to the seas and oceans, opening new frontiers for exploration. Among the diverse organisms inhabiting these ecosystems, marine phanerogams have emerged as a promising source of health-promoting bioactive compounds. This review highlights the distinctive chemical diversity of seagrasses including species such as Posidonia oceanica, Zostera marina, and Cymodocea nodosa, among others, and focusses on the growing interest in natural therapies as alternatives to conventional pharmaceuticals. Compounds such as polysaccharides or secondary metabolites such as polyphenol and flavonoids produced by marine plants exhibit a broad range of beneficial properties, including anti-inflammatory, antibacterial, antioxidant, and antidiabetic qualities. This review describes how these compounds can mitigate inflammation, promote skin health, and combat oxidative stress. Moreover, certain marine extracts have demonstrated potential to inhibit cancer cell growth and improve metabolic disorders like obesity and diabetes. The manuscript also discusses the potential of marine plant extracts in the development of novel therapeutic agents to address various illnesses, including infections, chronic diseases, and metabolic disorders. It emphasizes the need for further research to fully elucidate the mechanisms underlying the activity of these bioactive compounds and their potential therapeutic applications. In summary, this study highlights marine plants as a valuable reservoir for identifying organic molecules, paving the way for innovative advancements in medical and healthcare interventions. [ABSTRACT FROM AUTHOR]

An earlier ecosystemic study on carbon balance calculations of a Posidonia oceanica system in the Bay of Calvi [Corsica, France], indicated that the bacterial carbon demand [BCD] between May and October [Temp > 18 °C] in the seagrass meadow could not be sustained by net leaf production of P. oceanica and its epiphytes [NPP]. Hence, the system was clearly heterotrophic as only one autotrophic region was recorded, namely the depth range from 0–10 m. Already published data on the production of algal macrophytes and Cymodocea nodosa meadows and their mapping in the Bay of Calvi allowed a re-evaluation of the carbon budgets for each specific depth range. It was shown that C. nodosa could contribute significantly to covering the bacterial carbon demand of the P. oceanica system and that a positive carbon balance could be obtained for the seagrass meadow due to this carbon input when the temperature was higher than 18 °C, even though the depth ranges between 21–30 m and 31–38 m were negative. The overall trend indicates that the system cannot rely on the phytoplanktonic production of the water column, as BCD is higher than phytoplanktonic carbon production. When integrating BCD and net primary production [NPP] of the water column in summer we noticed a lack of some 97.6 to 104.3 tons of carbon which is not covered by the seagrasses leaf production and the algal macrophytes. The obtained data indicate clearly that other carbon carbon-producing compartments like the microphytobenthos, the NPP of rhizome epiphytes, and the detrital carbon import into the Bay of Calvi need to be investigated. [ABSTRACT FROM AUTHOR]

Two Indian Ocean surgeon fish Paracanthurus hepatus individuals were observed near Saint-Raphaël (Provence, France, north-western Mediterranean Sea) in the late summer of 2024 in Posidonia oceanica seagrass and reef habitats. This species is very popular among aquarium hobbyists in Europe, and a growing number of mega-yachts, such as those which moor in the Saint-Raphaël marina, have seawater aquariums on board. Accidental or deliberate release from one such aquarium is the most probable origin of these individuals. The first individual was speared and the second one was no longer sighted after a September storm. Their establishment is unlikely; however, in the future, with the warming of Mediterranean waters and the rapid increase in the number of mega-yachts, this could change. Yacht owners and their staff should be informed of the risk posed by aquarium discharges. [ABSTRACT FROM AUTHOR]

Posidonia oceanica retains a large amount of carbon within its belowground recalcitrant structure, the 'matte,' which is characterized by low oxygen availability and biodegradation. Fungi may play a pivotal role in carbon sequestration within the matte, even if little/no information is available. To fill this gap, we profiled fungal communities from the upper and lower layers of alive and dead matte, by using an ITS2-5.8S rDNA metabarcoding approach. The study was conducted in a shallow coastal stretch of the Aegean Sea (Crete). Then, 184 operational taxonomic units were identified, predominantly belonging to Ascomycota, in alive and dead matte. Nevertheless, their composition significantly differed: the host-specific Posidoniomyces atricolor was dominant in alive but not in dead matte, while fast-growing saprotrophs, potentially accelerating the decomposition rate, increased in dead matte. These findings lay the groundwork for future investigations on the possible increase of biodegradation under the changing environmental conditions. [ABSTRACT FROM AUTHOR]

Anthropogenic pressures affect large stretches of Mediterranean coastal environments, determining alterations, including chemical pollution, able to impair ecosystem functioning and services. Among the pollutants of major concern for their toxicity and persistence, there are polycyclic aromatic hydrocarbons (PAHs), which can be effectively monitored through bioaccumulation approaches. However, the main biomonitor of PAHs in the Mediterranean Sea, Posidonia oceanica, is currently undergoing extensive regressions due to anthropogenic pressures, forcing the search for alternative biomonitors. In this context, with a view to evaluate the effectiveness of the red alga Laurencia microcladia as an alternative PAH biomonitor, we comparatively investigated the accumulation gradients of 14 PAHs in its thalli, in leaves of P. oceanica and in surface sediments collected from different sites along the Cilento coast (southern Italy). The two species mainly absorb PAHs from water rather than sediments and show comparable PAH concentrations, with a preferential accumulation of low molecular weight PAHs in L. microcladia and of medium molecular weight PAHs in P. oceanica. Although with different accumulation profiles, both macrophytes highlighted comparable concentration gradients of anthracene and benzo[a]pyrene across study sites and the highest concentrations near a harbour. The obtained findings indicate that L. microcladia can be considered an effective biomonitor of PAHs in coastal ecosystems. [ABSTRACT FROM AUTHOR]

Seagrasses are one of the most productive marine ecosystems in the world. Posidonia oceanica, an endemic Mediterranean seagrass, is under high and constant anthropogenic and natural pressures, including climate change and the introduction of invasive species. Percnon gibbesi, a small crab with a tropical and subtropical distribution, was first reported in the Mediterranean Sea in 1999, and today is established across the entire Mediterranean Basin, inhabiting the shallow rocky infra-littoral zone. Given that P. gibbesi and P. oceanica can co-occur in the same environments, an experiment was set up to study their plant–herbivore interaction. Using two experiments at two different temperatures (19 °C and 25 °C), the incidence of herbivory on the seagrass tissues (fruits, leaves, rhizome, and whole shoot) by the invasive crab was assessed. The fruits along with the rhizome were the most consumed tissues, and the leaves of P. oceanica were the least consumed, which could be a consequence of tissue structure characteristics and/or nutrient quality. The incidence of herbivory on the leaves of P. oceanica was not affected by temperature. The herbivory pressure of the exotic crab P. gibbesi on native seagrass P. oceanica will likely be limited to a shallow bathymetric range; however, given the large scale of the invasion, the consumption of P. oceanica could become a relevant ecological issue in the Mediterranean Sea. [ABSTRACT FROM AUTHOR]

The growing demand for sustainable materials has driven the exploration of natural fibers as eco-friendly alternatives to synthetic reinforcements for composites. This study investigates the potential of Posidonia oceanica, an abundant marine biomass, which is often driven to be stacked on the backshore and used so far for energy recovery and low-value applications, as a filler and possible reinforcement in cementitious and polymer composites. Most applications of Posidonia are concentrated in the Mediterranean area and focused on the construction industry. However, its introduction in polymer composites, especially as a source of cellulose or in combination with the use of bio-based matrices, can also be proposed. With this aim, the physical and chemical properties of Posidonia oceanica fibers need to be characterized, and their compatibility with various matrices needs to be evaluated. Experimental results demonstrate that Posidonia oceanica fibers, especially when treated with alkali and silane, or combining both treatments, can exhibit mechanical properties quite comparable to other natural fibers, namely to those obtained from grass species. As with any other type of waste, yet with more interest for its wide accumulation over the coastal line, the use of Posidonia oceanica in composites may contribute to reducing the environmental footprint of these materials, aligning with circular economy principles. This review highlights the dual benefits of utilizing marine biomass by advancing material sustainability while not being detrimental to coastal waste management. [ABSTRACT FROM AUTHOR]

In the Mediterranean Sea, restoration of marine habitats has mostly focused on the endemic seagrass Posidonia oceanica. Despite several transplanting experiments, large-scale projects are rare, and their success is poorly known. The present work describes a restoration project of a large, degraded area in northern Sardinia (Italy) using cuttings harvested from a donor meadow that was destined for destruction due to harbor expansion. The receiving site was selected through a multidisciplinary study including acoustic mapping, ROV surveys, sediment assessment, and analyses of satellite images across ten years to evaluate the site suitability. Plants were manually uprooted from the donor meadow and cuttings were selected and transplanted within 24 h by environmental engineering techniques. The cuttings were transplanted onto degradable mats of natural coconut nets coupled with a double-twist steel mesh and anchored to the bottom. Overall, 7000 patches, each containing 20 cuttings, were transplanted in three periods: June–July 2022, October–November 2022, and February–March 2023. One year after the restoration, all the patches were in situ, with an overall cutting survival of 59%. The results are comparable to those of previous small-scale projects using the same technique and also endorse its suitability for the restoration of large, degraded areas. [ABSTRACT FROM AUTHOR]

This study proposes a rapid and cost-effective method to identify the effects of coastal artificialization on the distribution of shallow Posidonia oceanica meadows. Seven embayed coves were selected along the Ligurian coastline (Italy, NW Mediterranean) to evaluate the influence of the coast geometry on the depth and morphology of the meadow upper limits (i.e., the shallowest depth reached by the plants towards the coastline). The areas under investigation are characterized by rocky coasts and exhibit varying degrees of embayment, resulting in different levels of exposure to wave action. The geometric features of embayed coastlines, along with hydrodynamics and physical parameters, were examined in relation to the structure of P. oceanica meadows within each cove. The results indicated that both natural and anthropogenic (i.e., artificial) coastal geometries influence the spatial distribution of P. oceanica meadows, leading to significant heterogeneity in their upper limits. The configuration of the embayment system produces various types of hydrodynamic circulation. The existence of a cellular circulation pattern leads to the formation of rip or megarip currents, which cause erosion in the shallow portions of the meadows and create sandy channels that disrupt the continuity of the meadows. Establishing a relationship between the hydrodynamics within the coves and the characteristics of the upper limits of the meadows proved to be a valuable method for promptly distinguishing whether the observed conditions stemmed from natural or human influences. This proposed approach enables a preliminary and cost-effective assessment of the origins of erosive processes affecting the shallow portions of P. oceanica meadows. Such an approach represents a clear management advantage in the environmental impact assessment of coastal engineering projects. [ABSTRACT FROM AUTHOR]

In recent years, numerous efforts to transplant Posidonia oceanica have been carried out in the Mediterranean Basin for experimental and large‐scale restoration purposes. However, data on the long‐term outcomes of these initiatives remain scarce. This study aims to address this gap by investigating the long‐term response of transplanted P. oceanica at both the population and plant level in comparison to adjacent natural meadows. We report on two large‐scale transplantation sites in Italy: Santa Marinella in the Central Tyrrhenian Sea and Ischia Porto in the Southern Tyrrhenian Sea, assessing their progress 14 and 10 years after transplantation, respectively. Descriptors of the meadows and of individual plants were investigated through field and laboratory activities. Sampling was conducted in both transplanted and adjacent control areas within the natural P. oceanica meadow. After about a decade, shoot density in the transplanted areas equaled that of the natural ones. Nevertheless, phenological and lepidochronological descriptors in the transplanted areas still did not match those of the natural meadows. Our work provides crucial information into the restoration process of P. oceanica, with implications for managing this habitat in line with recent EU marine legislation. [ABSTRACT FROM AUTHOR]

Seed-based restoration methods are increasingly recognized as a relevant tool contributing to halt and reverse the loss of seagrass meadows while providing genetic and evolutionary benefit for the conservation of these habitats. Ad-hoc protocols aimed at maximizing the survival of plantlets obtained from seeds in cultivation systems are therefore required. Previous trials of seedling culture of Posidonia oceanica , the dominant seagrass of the Mediterranean Sea, recorded up to 40% loss due to mould development. In this study we aim to (i) identify the putative causal agents of seed decay and (ii) test the efficacy of copper sulphate (0.2 and 2 ppm) and of tannin-based products derived from chestnut, tara and quebracho in reducing seed and seedling decay, while assessing possible phytotoxic effects on plant development. Halophytophthora lusitanica, H. thermoambigua and a putative new Halophytophtora species were identified as possible causal agents of seed loss. The antimicrobial agents (copper and tannins) reduced seed contamination by 20%, although copper sulphate at 2 ppm strongly inhibited the root growth. Among tannins, chestnut and tara reduced seeds germination by up to 75% and decreased shoot and root development, while quebracho showed a less severe phytotoxic effect. The use of copper sulphate at 0.2 ppm is therefore recommended to prevent P. oceanica seedling loss in culture facilities since it reduces seed contamination with no phytotoxic effects. Our results contribute to improving the seedling culture of one the key species of the Mediterranean Sea, increasing propagule availability for restoration purposes. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim Location Methods Results Main Conclusions Seed dispersal plays a key role in shaping the distribution and genetic complexity of seagrass populations and affects their resilience capacity under disturbance. The endemic seagrass Posidonia oceanica is a key component of Mediterranean coastal ecosystems, but knowledge about movement ecology in this species is limited, especially regarding seed movement pathways and dispersal potential.Western coast of Sicily (central Mediterranean).Beach‐cast fruits of the Mediterranean seagrass P. oceanica were collected from nine localities along the Western coast of Sicily, along with adult shoots from eight putative donor meadows. We determined pair‐wise genetic differentiation between established meadows and seed cohorts. Genetic assignment tests were used to infer the most likely meadow of origin of individual seeds and were complemented with forward and backward Lagrangian simulations of dispersal.A significant genetic differentiation was found between seed pools and the most‐likely meadow of origin. The genetic assignment confirmed that seeds from the same cohort originated from multiple meadows and emphasised the presence of long‐distance‐dispersal (LDD) events (up to hundreds of km). Genetic connectivity appeared to be greater than that predicted by oceanographic simulations, which may reflect the longer temporal scales on which gene flow is shaped, in contrast to contemporary dispersal patterns. Lagrangian simulations highlighted that fruits were physically capable of dispersing beyond the study area and that the north Tunisian coast could be a key source of propagules for the populations studied.Our study represents a significant step forward in the understanding of P. oceanica movement ecology and could guide meadows' conservation and restoration actions. Our findings are significant in a broader context outside of the research area and could be the basis of similar studies in other regions, especially considering the increasing number of fruiting events recorded across the Mediterranean likely associated with ocean warming. [ABSTRACT FROM AUTHOR]

PLA biocomposites, incorporating 5% wt. of lignocellulosic fibres (LF) from Posidonia oceanica waste with different degrees of cellulose purification, were obtained by melt blending and compression moulding. The LF were obtained after removing part of the non-cellulosic components by subcritical water extraction at 150 and 170 °C and after bleaching the extracted residues with hydrogen peroxide or sodium chlorite. The non-bleached LF provided the composites with a brown colour and opacity, while the bleached LF impacted the optical properties of composites to a lower extent, depending on their whiteness. The LF composition had a noticeable effect on the composites' mechanical and barrier properties. All LF reduced the water vapour barrier capacity while promoting the oxygen barrier of the films. Bleached LF enhanced the film stiffness and reduced extensibility and resistance to break, whereas non-bleached LF had lower impacts on the tensile parameters. Considering the mechanical and barrier performance of the composites, the fibres obtained at 170 °C and bleached with sodium chlorite exhibited the best behaviour. Nevertheless, if transparency and colour are not limiting for the use of the films, untreated LF allowed for good preservation of the water vapour permeability of PLA films and enhanced the oxygen barrier capacity, with a similar mechanical response as the other non-bleached fractions. [ABSTRACT FROM AUTHOR]

Background/Objectives: Biogenic volatile organic compounds (BVOCs), extensively studied in terrestrial plants with global emissions around 1 PgC yr−1, are also produced by marine organisms. However, benthic species, especially seagrasses, are understudied despite their global distribution (177,000–600,000 km2). This study aims to examine BVOC emissions from key Mediterranean seagrass species (Cymodocea nodosa, Posidonia oceanica, Zostera noltei, and Zostera marina) in marine and coastal lagoon environments. Methods: BVOCs were collected using headspace solid-phase microextraction (HS-SPME) using divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fibers and analyzed by gas chromatography–mass spectrometry (GC-MS). Results: An important chemical diversity was found with a total of 92 volatile compounds (61 for Z. noltei, 59 for C. nodosa, 55 for P. oceanica, and 51 for Z. marina), from different biosynthetic pathways (e.g., terpenoids, benzenoids, and fatty acid derivatives) and with several types of chemical functions (e.g., alkanes, esters, aldehydes, and ketones) or heteroatoms (e.g., sulfur). No differences in chemical richness or diversity of compounds were observed between species. The four species shared 29 compounds enabling us to establish a specific chemical footprint for Mediterranean marine plants, including compounds like benzaldehyde, benzeneacetaldehyde, 8-heptadecene, heneicosane, heptadecane, nonadecane, octadecane, pentadecane, tetradecane, and tridecanal. PLS-DA and Heatmap show that the four species presented significantly different chemical profiles. The major compounds per species in relative abundance were isopropyl myristate for C. nodosa (25.6%), DMS for P. oceanica (39.3%), pentadecane for Z. marina (42.9%), and heptadecane for Z. noltei (46%). Conclusions: These results highlight the potential of BVOCs' emission from seagrass ecosystems and reveal species-specific chemical markers. [ABSTRACT FROM AUTHOR]

Large amounts of seaweed are deposited on shores worldwide daily. The presence of this natural pollutant on the coast is not only considered an environmental burden but also often hinders the development of tourism in the affected areas. Depending on the beach surface area, local governments worldwide spend considerable portions of their budgets to remove seaweed from beaches. Moreover, the removed seaweed occupies increasing space in landfills where it is disposed. Seaweed is noncombustible and decomposes slowly over long periods. In this study, we consider the use of seaweed (a natural waste) as a value-added product for insulation and building materials. Seaweed (Posidonia Oceanica) boards with dimensions of 250 mm × 60 mm × 10 mm were obtained by pressing a mixture of processed seaweed and an organic binder. The as-prepared boards were analyzed for their physical-mechanical properties according to the British standards. The boards with a mean humidity level of 9.15% and density of 404.5 g·cm 3 demonstrated a maximum bending resistance of 2.72 × 103 N·m 2 and mean expansion upon water adsorption of ~10% with regards to length and width and ~30% with regards to height. The tested samples showed significant humidity resistance according to the boiling test and an average thermal conductivity of 0.047 W·m 1·K 1, which is comparable to that of polystyrene. Computational analysis of the "seaweed material" model revealed significant thermal and mechanical properties. The mechanical strength of the computed material, including its high Young's and shear moduli, renders it a promising candidate in construction. [ABSTRACT FROM AUTHOR]

The role of seagrasses in providing a complex habitat for marine organisms is globally documented; however, few studies have investigated the trophic incorporation of endemic Mediterranean Posidonia oceanica into marine food webs. Meadows of P. oceanica are declining due to climate change and anthropogenic pressures, emphasising the need to determine its contribution in local trophic dynamics. We investigated whether benthic marine invertebrate (BMI) and fish consumers assimilate carbon directly from P. oceanica seagrass or other sources along the seagrass meadow margins in Malta. We sampled and analysed the δ13C and δ15N isotope values of P. oceanica, particulate organic matter (POM), macroalgae, 14 invertebrate taxa, and 10 fishes at three locations marginal to P. oceanica seagrass meadows. Stable isotope ratios were significantly different between all taxa (F26 = 17.37, R2 = 0.68, p < 0.01) and locations (F2 = 34.22, R2 = 0.10, p < 0.01). The source, invertebrate, and fishes were enriched in both 13C and 15N at Baħar iċ-Ċagħaq relative to the other locations, L'Aħrax and Golden Bay, likely due to the increased effluent. Stable isotope mixing models were somewhat confounded as POM and macroalgae had similar δ13C and δ15N values at each site, hampering efforts to define the resource use of the sampled taxa. However, Posidonia oceanica made the lowest contribution for both consumer groups at all locations, consistent with the results of other Mediterranean studies, suggesting that P. oceanica does not contribute significantly to the diet of consumers at seagrass meadow margins within Maltese waters. [ABSTRACT FROM AUTHOR]

Grazing can impart long‐lasting changes in vegetated ecosystems. How ecosystems respond to herbivory depends on the ecological and evolutionary histories of their foundational species. The overall ecosystem functioning and associated biodiversity depend on these responses but there is still little understanding on how the intensity and duration of herbivory interact and impact vegetated ecosystems. We experimentally tested in the field the responses of three seagrass species with distinct life history traits to increasing intensities of herbivory over time. Specifically, we assessed structural responses (i.e., canopy height and shoot density) to reflect the ecosystem state. Additionally, we used mechanistic models to assess induced and constitutive responses in the different seagrass species. Results show that seagrasses coped with herbivory differentially in relation to their life history traits. Posidonia oceanica (persistent species) was resistant and only registered declines in canopy height, whereas both canopy heigh and shoot density rapidly decreased for Cymodocea nodosa (intermediate‐colonizing species) and Zostera noltei (colonizing species). Seagrasses also differed in the type of structural response, with the colonizing species experiencing reductions in shoot density, and the persistent P. oceanica registering declines in canopy height. After months of exposure to cumulative herbivory, all three species showed signs of stability. Interestingly, none of the species disappeared completely even when exposed to extreme herbivory. Mechanistic models indicate that herbivory‐induced responses are a potential explanation for these patterns. This study suggests that given the long evolutionary history of herbivory, some seagrasses may be remarkably well adapted to both intense and cumulative herbivory. [ABSTRACT FROM AUTHOR]

The variability in stocks and accumulation rates of organic carbon (Corg), nitrogen (N), and carbonate (CaCO3) was studied in fifteen Posidonia oceanica meadows spread throughout the South Aegean Sea (Greece). In addition, the abiotic and biotic drivers determining the pattern of variability in the accumulation rates were assessed by exploring the influence of sediment characteristics, seagrass traits, and environmental settings. The meadows supported on average (±STDEV) 14.6 ± 5.0 kg Corg m−2, 0.47 ± 0.17 kg N m−2, and 249 ± 210 kg CaCO3 m−2 in the top meter of their sediments, with mean accumulation rates over the last 500 years of 33.6 ± 23.6 g Corg m−2 yr−1, 1.00 ± 0.62 g N m−2 yr−1, and 405 ± 336 g CaCO3 m−2 yr−1 across sites. A redundancy analysis (RDA) explained 70% of the variation in Corg, N, and CaCO3 accumulation rates, with three sediment characteristics (i.e., sediment Corg:N and Corg:Cinorg ratios and P. oceanica contribution to the sediment Corg pool) emerging as the primary set of factors shaping the accumulation of matter, followed by seagrass traits (i.e., leaf biomass and rhizome elongation) and environmental variables (i.e., suspended organic matter). The high degree of variability within the region emphasizes the need for fine‐scale assessments to understand the local conditions influencing sequestration. Our findings underscored the critical role of seagrass meadows in carbon and nitrogen sequestration in the region, urging conservation efforts to protect these ecosystems and prevent potential losses of stored carbon and nitrogen following seagrass degradation. Plain Language Summary: In the present study, we explored the abiotic and biotic factors influencing the accumulation patterns of carbon, nitrogen, and carbonate in 15 seagrass (Posidonia oceanica) meadows across the South Aegean Sea (Greece). Sediment characteristics (i.e., sediment Corg:N and Corg:Cinorg ratios and P. ocenica contribution to the sediment Corg pool) mainly drove the pattern of carbon, nitrogen, and carbonate accumulation, with seagrass traits (i.e., leaf biomass and rhizome elongation) and environmental conditions (i.e., suspended organic matter) contributing to a lesser extent. Overall, seagrass meadows play a crucial role in storing carbon and nitrogen in the studied region, serving as important natural sinks, and thus, protecting these ecosystems is important to prevent the loss of these stored elements. Additionally, understanding the factors that shape the variability in Posidonia oceanica storage capacity is crucial for management and conservation efforts. Key Points: Seagrass (Posidonia oceanica) meadows of the South Aegean Sea (Greece) represent important natural sinks for organic carbon, nitrogen, and carbonate.The accumulation pattern of organic carbon, nitrogen, and carbonate in the underlying seagrass sediments was mainly driven by sediment characteristics, followed by seagrass traits and environmental conditions.Fine‐scale assessments are crucial for understanding the local factors shaping the storage capacity of seagrass meadows to support management decisions. [ABSTRACT FROM AUTHOR]

This study investigates the impact of artificial light at night (ALAN) along the Sicilian coasts, using satellite data from 2016 to 2023, focusing on three distinct spatial domains: terrestrial areas within 1 km from the coastline, marine areas extending up to 1 km offshore, and marine areas up to 1 nautical mile from the coast. In coastal zones, ALAN is a significant anthropogenic pressure with potentially detrimental effects on ecosystems. By integrating satellite data with geographic datasets such as Corine Land Cover (CLC), Natura 2000 protected areas, and Posidonia oceanica meadows, this study aims to characterize and analyse the temporal and spatial variations in ALAN across these domains. The findings reveal substantial differences in light pollution between domains and over time, with coastal terrestrial areas exhibiting the highest levels of ALAN. In contrast, marine areas further offshore experience reduced light pollution, particularly within the 1-nautical-mile domain. This study also indicates that protected areas, especially those within the Natura 2000 network, show significantly lower ALAN levels than non-protected areas, highlighting the effectiveness of conservation efforts. Statistical analyses, including ANOVAs, demonstrate that factors such as geographic domain, year, province, and CLC classes significantly influence ALAN distribution. This study advocates for considering ALAN as a critical factor in environmental impact assessments, such as those under the Maritime Spatial Planning Directive (MSP) and Marine Strategy Framework Directive (MSFD), providing valuable insights to support policies aimed at mitigating the environmental impact of light pollution on coastal and marine ecosystems. [ABSTRACT FROM AUTHOR]

The ocean, with its intricate processes, plays a pivotal role in shaping marine life, habitats, and the Earth's climate. This study addresses issues such as beach erosion, the survival of propagules from species like Posidonia oceanica, and nutrient distribution. To tackle these challenges, we propose an innovative sensor that quantifies hydrodynamic velocity by measuring the output voltage derived from detecting changes in light absorption and scattering using LEDs and LDRs. Our results not only demonstrate the effectiveness of the sensor but also the accuracy of the processing algorithm. Notably, the blue LED exhibited the lowest mean relative error of 7.59% in freshwater, while the yellow LED was most precise in chlorophyll-containing water, with a mean relative error of 6.80%. In a runoff simulation, we observed similar velocities with the blue, green, and white LEDs, 6.89 cm/s, 6.99 cm/s, and 7.05 cm/s, respectively, for nearly identical time intervals. It is important to highlight that our proposed sensor is not only effective but also highly cost-efficient, representing less than 0.43% of the cost of a Nortek Vector 6 MHz and 0.18% of the Teledyne Workhorse II 300 kHz Marine. This makes it a key tool for managing marine ecosystems sustainably. [ABSTRACT FROM AUTHOR]

Aim: Seagrass meadows represent a key marine ecosystem owing to the significant biodiversity they host. Protection actions are often implemented without considering connectivity between habitats. In this article, we project and prioritise Mediterranean seagrass habitats (Posidonia oceanica and Cymodocea nodosa) based on their potential as sources/retention and stepping stones for dispersal propagules of the associated biotic communities. We use this information to identify gaps in the protection of highly ranked habitats. Location: Mediterranean Sea. Methods: We related seagrass observations with marine environmental predictors to run species distribution models and infer the distribution of Mediterranean seagrasses. We then used a network‐based approach (CONEFOR) to rank patches of seagrass suitable areas based on their contribution to the seascape in terms of patch area, potential as source/retention of propagules and stepping stone. Finally, by overlaying our ranking with the spatial distribution of marine protected areas (MPAs), we identified potential gaps in the protection of important seagrass habitats across the Mediterranean and its basins. Results: Most of the identified patches of seagrass suitable areas are not included in MPAs, only reaching a maximum protection coverage of ~50% in the Northwestern Mediterranean. Relatively few patches contribute disproportionately to connectivity, but top‐ranked habitat patches are not included within the existing MPAs network, both at the Mediterranean scale and for most basins. The largest gaps for the source/sink role are in the Aegean and Ionian Sea, and largest gaps for the stepping stone role are in the Adriatic, Ionian and Tyrrhenian Sea. Main Conclusions: Our results suggest that the current MPAs network fails to protect highly relevant patches of seagrass suitable areas in most of the Mediterranean basins. However, this gap could be filled by a few well‐placed MPAs. Overall, we provide novel insights for the identification of key habitats and planning novel coastal MPAs in the region. [ABSTRACT FROM AUTHOR]

The ecosystem status of the Aegean Sea coasts of Türkiye (Eastern Mediterranean) was assessed using the Biotic Index based on Posidonia oceanica (BiPo) and a newly proposed Nondestructive Phytobenthic Index (NPI), according to the requirements of the Water Framework Directive (WFD 2000/60/EC). In addition, their relationships with the Macroalgae-Land Uses Simplified Index (MA-LUSI) were evaluated. The descriptors measured through the NPI included the shoot density, cover, depth and lower limit type of the Posidonia meadows and cover of the other macrophytic communities; Cymodocea/Zostera, canopy-forming brown, coralligenous, opportunistic, and alien macroalgae. The good status was expressed by the mean value of the BiPo (0.69) at 20 sites, while the moderate status was expressed by the NPI (0.59) at 25 sites. Simultaneous implementation of the biotic indices proved their consistency (r = 0.745), while negative relationships between the MA-LUSI and the BiPo (r = -0.243) and NPI (r = -0.450), underlined their capability to assess the degradation of macrophytic communities in anthropized regions. [ABSTRACT FROM AUTHOR]

Endemic Mediterranean seagrass Posidonia oceanica is highly endangered today as it lives in a narrow infralittoral zone intensely exposed to human impact. P. oceanica beds are especially endangered in the Adriatic Sea as the central and northern Adriatic could be considered as a naturally suboptimal area for P. oceanica growth. In this research, we used some standard descriptors of Posidonia meadows at different locations and depths and determined the biochemical parameters (phenolic compounds, photosynthetic pigments, and enzyme activities) in its leaves in order to find possible correlations among the measured parameters and environmental conditions. Photosynthetic pigments were shown to be sensitive biomarkers in the assessment of P. oceanica response to different light conditions, but more research is needed to elucidate the impact of other environmental factors. Overall, the results of this research show that the studied parameters are good bioindicators of a meadow's environmental state, but it is necessary to analyze a number of diverse indicators together to properly characterize the state of a particular P. oceanica meadow. This approach would be very useful in the determination of P. oceanica conservation status, which is the first step towards improving monitoring protocols and implementing appropriate conservation measures. [ABSTRACT FROM AUTHOR]

The anchoring and mooring of boats mechanically damage Posidonia oceanica plants; however, no information is available on the effect of this kind of damage on the plant holobiont, i.e., on the associated bacterial and fungal communities. Indeed, bacterial communities are known to change under different plant stress conditions but the dynamics of seagrass-associated fungi remain largely unexplored. We used DNA metabarcoding to profile the bacterial and fungal colonizers of two nearby P. oceanica patches in the Villefranche-sur-Mer bay (France) differing by the amount of exposure to mechanical stress due to boat transit and anchoring. Bacterial communities showed a significant reduction in diversity with an increase in Vibrio sp. in the rhizome and root samples from the impacted site, where the accumulation of dead organic material favors opportunistic heterotrophs. Conversely, fungal communities showed increased diversity in the leaf samples from the impacted site, where a reduction in the dominant P. oceanica host-specific mutualistic endosymbiont, Posidoniomyces atricolor, was found. This change was probably due to the opening up of new colonizable niches for several fungal species. Although this study represents a preliminary assessment of the effect of mechanical stresses on P. oceanica-associated microbial communities, it further supports their putative use as a seagrass descriptor. [ABSTRACT FROM AUTHOR]

Marine Heat Waves (MHWs) occurrence has been increasing in the Mediterranean Sea. The effects of field simulated MHWs of different intensity (medium and high temperature) on the transcriptome expression of the endemic seagrass Posidonia oceanica were evaluated considering different origins of the plant. The aim of the study was reached through a common garden transplant experiment in the North-west of Sardinia (Italy), where two P. oceanica meadows characterized by different thermal regimes (cold and warm) were chosen. MHWs were simulated in front of a power plant, that creates a natural laboratory by releasing warm water in the sea. Differential gene expression and GO enrichment analyses highlighted differences in the transcriptomic profiles of plants from cold and warm environments suggesting that the MHWs induced different levels of stress due to different tolerance to the heat event. Plants from both origins activated processes to achieve protein homeostasis, but only cold plants activated an antioxidant defense and altered sugar metabolism, both indicators of heat stress. Within plants of the same origin, a different response to MHW intensity was also detected: while warm plants showed the most complex response at high temperature rather than at medium temperature, cold plants seemed to better cope with the medium temperature intensity rather than with high temperature. [ABSTRACT FROM AUTHOR]

This study aims at assessing the reserve effect on fish assemblage in a small urban fully protected and highly enforced Marine Protected Area (MPA), Larvotto MPA (Monaco, Mediterranean Sea). The data about fish density, size, and biomass was collected by underwater visual census in the MPA and unprotected areas in two habitats, artificial rocky substrates and Posidonia oceanica meadows. On artificial rocky substrates, we recorded significantly higher fish biomass within the MPA compared to unprotected areas, while no significant difference was detected on Posidonia , with this suggesting the habitat-specific responses of fish assemblages to protection. Here we highlight the potential effectiveness of highly enforced small-sized urban MPAs, such as the Larvotto MPA, in generating ecological benefits, and speculate about their potential role in supporting networks of MPAs. This study supports increased attention to urban MPAs in conservation efforts, emphasizing the need for efficient management strategies in the face of ongoing coastal expansion. [ABSTRACT FROM AUTHOR]

This study examined the adsorption ability of Ni(II) metal ions from aqueous solutions on a physically activated adsorbent of Posidonia oceanica seagrass (AC-PO), which is both economically and naturally available. The effects of pH, amount of adsorbent, concentration of nickel ions, temperature, and contact time, which are among the parameters affecting the adsorption of Ni(II) ions on AC-PO, were examined. The kinetic data fit well with the pseudo-second-order model. The adsorption of Ni(II) ions showed compliance with Langmuir, Freundlich, and D-R isotherms. The Langmuir model showed better representation of data (0.9993). The maximum adsorption capacity of AC-PO for nickel ions was 138.89 mg·g−1.at 25 °C The thermodynamic parameters such as ∆G°, ∆H°, and ∆S° were calculated for the Ni(II) ion, and it was determined that the adsorption was spontaneous and endothermic. In qualitative chemical analysis by energy dispersive spectroscopy (EDS), it was found that there was ion exchange with adsorption of nickel ions on the AC-PO adsorbent. According to the results obtained from this study, it can be said that the adsorption ability of the AC-PO adsorbent is quite high in the removal of Ni(II) ions from aqueous solutions. [ABSTRACT FROM AUTHOR]

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Plastic pollution and microplastic (MP) debris are some of the most significant solid waste pollutants, threatening the marine environment and causing sediment accumulation. Coastal seagrass areas are usually important habitats that support multiple living species and provide several ecosystem services. This study aimed to determine the abundance, characteristics, and composition of microplastics on the southern side of the Tunisian Mediterranean Sea by using Posidonia oceanica (P. oceanica) as a crucial trap for microplastics. Samples of Posidonia leaves were collected from the Tunisian coastal area of Gabes-City. The characterization of microplastic detritus was carried out by stereomicroscopy, and acid digestion of Posidonia tissue leaves was performed for qualitative and quantitative analysis of MPs using NMR spectroscopy. The study revealed pellets, threads, and fragments of polymers as the frequent forms found in MPs. Polyethylene, polystyrene, and bis(2-ethyl-hexyl) phthalates were the most abundant materials detected. P. oceanica leaves contributed notably to microplastic subsidence, seafloor horizontal migration, and sediment burial. Thus, marine flora appeared to be a good tool to detect and monitor plasticizers, and further studies of the P. oceanica seagrass areas will help in developing a more comprehensive knowledge of chemicals spreading over a geographical zone. The results obtained will be used for developing baseline data on plasticizer contamination on the wide-ranging marine coast. [ABSTRACT FROM AUTHOR]

This work presents the first ecosystem accounts for Marine-Based Tourism (MBT) in Italy. We develop a methodological approach to connect biophysical and economic information required to fill ecosystem accounting supply and use tables. Coherent with the System of Environmental Economic Accounting – Ecosystem Accounting (SEEA EA) framework, this approach starts by estimating the extent and the condition of marine ecosystems, showing the urgency in improving the availability, organisation and accessibility of biophysical data. This work provides valuable insights into understanding MBT from an ecosystem accounting perspective. We focus on the Posidonia oceanica and its role in the MBT sector in Italy, providing a physical quantification of such contribution and converting this flow into monetary terms. Our findings show that such habitat significantly contributes to the tourism sector, resulting in exchange values of MBT of €6 million in 2019 and €3.7 million in 2021.

Abstract Restoration of vulnerable marine habitats is becoming increasingly popular to cope with widespread habitat loss and the resulting decline in biodiversity and ecosystem services. Lately, restoration strategies have been employed to enhance the recovery of degraded meadows of the Mediterranean endemic seagrass Posidonia oceanica. Typically, habitat restoration success is evaluated by the persistence of foundation species after transplantation (e.g., plant survival and growth) on the short and long-term, although successful plant responses do not necessarily reflect the recovery of ecosystem biodiversity and functions. Recently, soundscape (the spatial, temporal and frequency attribute of ambient sound and types of sound sources characterizing it) has been related to different habitat conditions and community structures. Thus, a successful restoration action should lead to acoustic restoration and soundscape ecology could represent an important component of restoration monitoring, leading to assess successful habitat and community restoration. Here, we evaluated acoustic community and metrics in a P. oceanica restored meadow and tested whether the plant transplant effectiveness after one year was accompanied by a restored soundscape. With this goal, acoustic recordings from degraded, transplanted and reference meadows were collected in Sardinia (Italy) using passive acoustic monitoring devices. Soundscape at each meadow type was examined using both spectral analysis and classification of fish calls based on a catalogue of fish sounds from the Mediterranean Sea. Seven different fish sounds were recorded: most of them were present in the reference and transplanted meadows and were associated to Sciaena umbra and Scorpaena spp. Sound Pressure Level (SPL, in dB re: 1 μPa-rms) and Acoustic Complexity Index (ACI) were influenced by the meadow type. Particularly higher values were associated to the transplanted meadow. SPL and ACI calculated in the 200–2000 Hz frequency band were also related to high abundance of fish sounds (chorus). These results showed that meadow restoration may lead to the recovery of soundscape and the associated community, suggesting that short term acoustic monitoring can provide complementary information to evaluate seagrass restoration success.

Restoration of vulnerable marine habitats is becoming increasingly popular to cope with widespread habitat loss and the resulting decline in biodiversity and ecosystem services. Lately, restoration strategies have been employed to enhance the recovery of degraded meadows of the Mediterranean endemic seagrass Posidonia oceanica. Typically, habitat restoration success is evaluated by the persistence of foundation species after transplantation (e.g., plant survival and growth) on the short and long-term, although successful plant responses do not necessarily reflect the recovery of ecosystem biodiversity and functions. Recently, soundscape (the spatial, temporal and frequency attribute of ambient sound and types of sound sources characterizing it) has been related to different habitat conditions and community structures. Thus, a successful restoration action should lead to acoustic restoration and soundscape ecology could represent an important component of restoration monitoring, leading to assess successful habitat and community restoration. Here, we evaluated acoustic community and metrics in a P. oceanica restored meadow and tested whether the plant transplant effectiveness after one year was accompanied by a restored soundscape. With this goal, acoustic recordings from degraded, transplanted and reference meadows were collected in Sardinia (Italy) using passive acoustic monitoring devices. Soundscape at each meadow type was examined using both spectral analysis and classification of fish calls based on a catalogue of fish sounds from the Mediterranean Sea. Seven different fish sounds were recorded: most of them were present in the reference and transplanted meadows and were associated to Sciaena umbra and Scorpaena spp. Sound Pressure Level (SPL, in dB re: 1 μPa-rms) and Acoustic Complexity Index (ACI) were influenced by the meadow type. Particularly higher values were associated to the transplanted meadow. SPL and ACI calculated in the 200–2000 Hz frequency band were also related to high abundance of fish sounds (chorus). These results showed that meadow restoration may lead to the recovery of soundscape and the associated community, suggesting that short term acoustic monitoring can provide complementary information to evaluate seagrass restoration success. [ABSTRACT FROM AUTHOR]

Posidonia oceanica significantly contributes to the health of oceans and coastal areas; however, its progressive decline is becoming an increasing source of concern. The present preliminary study aims to assess the chemical parameters that describe the state of preservation of the aforementioned plant meadows located in the Tremiti Islands archipelago. To better understand the plants' response to external factors, the emission of biogenic volatile organic compounds (BVOCs) was investigated using Posidonia oceanica as a biological indicator. Subsequently, the heavy metal concentrations (Ag, Al, As, Ba, Be, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Se, Sn, Ti, Tl, V, Zn) in sediments, leaves, and seawater were determined and pollution indicators were calculated to assess the deviation from the natural background levels of sediments. The dimethyl sulfoniopropionate (DMSP) to dimethyl sulfoxide (DMSO) ratio was calculated to evaluate the oxidative stress levels in the meadows because the DMSP naturally present in Posidonia oceanica is oxidized to DMSO and decreases the ratio of DMSP/DMSO. BVOC analysis revealed dimethyl sulphide (DMS) as the most abundant molecule. Morphological features led to variations in metal concentrations across sampling sites, with sheltered bays displaying a higher metal content. Degradation is indicated by a greater DMSO content in the outer leaves. In accordance with the metal content, the bioindicator ratio confirms greater degradation on the south side, which aligns with increased oxidative stress. [ABSTRACT FROM AUTHOR]

Posidonia oceanica is an endemic species of the Mediterranean Sea, but recently it is actually exposed to anthropogenic pressures by numerous activities of various origins (coastal developments, trawling, anchoring, turbidity, erosion and beach nourishment). The aim of this study is to evaluate the ecological status of P. oceanica meadows around Rachgoun Island of Algerian west coast. The entire island is protected according to the Ramsar Convention and a marine protected area in the process of being classified. The ecological study revealed that the density values reveal a dense to sparse meadow, and the cover rates are among similar values on the Algerian coasts, between 70 % and 88.32%. The analysis carried out on structural features shows that these parameters are strongly influenced by multiple factors (depth, hydrodynamics and anthropogenic actions). The biometric parameters and phenological study (length and width of leaves, leaf surface, coefficient A and leaf area index) of P. oceanica show that the Rachgoun Island meadows are, globally, in good health status. [ABSTRACT FROM AUTHOR]

The environmental risk of coastal sunscreen pollution and ocean warming to seagrass meadows seems to be greatly intensified in the Mediterranean basin, due to its semi-enclosed nature that limits water renewal and the high influx of tourists it receives every year. Both stress factors could be interacting synergistically, thus, contributing to the current decline of Posidonia oceanica meadows. Our study aimed to determine the response of P. oceanica to the combined effects of elevated seawater temperature and sunscreen addition in a short-term laboratory experiment, testing an environmentally relevant sunscreen concentration in Mallorca, Spain (20 mg L-1) and a control (0 mg L-1) with the ambient temperature in spring (15°C) and a worst-case scenario of estimated temperature increase by 2100 (ambient + 5°C). Sunscreen addition promoted net primary production rates in the seagrass under ambient temperature, possibly due to nutrient enrichment from the mixture. Alkaline phosphatase activity (APA) in young leaves was enhanced under increased temperature only. Early-warning signs of the impacts of combined elevated temperature with sunscreen exposure in P. oceanica were the drastic decrease in leaf chlorophyll concentrations and inhibition of the nitrogen fixation associated with rhizomes (more than 50%), along with greater oxidative stress biomarkers in leaves (i.e., catalase activity and polyphenols content) and APA in roots (4-fold increase). The current investigation has revealed how the negative effects of coastal sunscreen pollution in this seagrass species may be exacerbated under climate change factors, such as ocean warming, with possible implications in the nutrient cycling and photosynthetic process of the plant. Investigations focused on determining the impacts of these contaminants in P. oceanica meadows and their interaction with additional stress factors in the environment is of great relevance for the future management of this declining ecosystem. [ABSTRACT FROM AUTHOR]