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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.

A previous study from Sicily, Italy, indicated that the dominant Mediterranean seagrass Posidonia oceanica forms a dark septate endophytic (DSE) association with a lulworthioid fungus ('Lulwoana sp.'). This conflicts with several other studies from the NW Mediterranean Sea that point at the recently described pleosporalean fungus Posidoniomyces atricolor. I collected P. oceanica roots at eight sites around Sicily and checked them for fungal colonization using light microscopy. At three sites, root fungal symbionts (mycobionts) were isolated into pure cultures and identified using ITS rDNA sequences. Posidoniomyces atricolor represented the most frequent mycobiont (56 isolates), closely followed by lulworthioid fungi (51). The obtained mycobiont spectrum also included Cladosporium (2), Alternaria (1), Corollospora (1), Fusarium (1), Penicillium (1) and Vishniacozyma (1) isolates. The characteristic DSE root colonization, similar to those occurring in terrestrial plants but not known from any other seagrass, was found in all investigated P. oceanica individuals. The microscopy screening suggests that P. atricolor is responsible for the observed DSE colonization. This study extends the known range of Pos. atricolor and the DSE association characteristic for P. oceanica to the southern Tyrrhenian Sea/Sicily. While lulworthioid fungi regularly occur in P. oceanica tissues, including terminal fine roots, their significance and functioning (e.g. parasitic, pathogenic, endophytic) are unknown and require further investigation. However, there is currently no proof that they belong among dark septate endophytes of this seagrass.

Since the corrosion protection of mild steel samples in corrosive media (1 M of hydrochloric acid [HCl]) was cheap and successful, the ethanol extract of Posidonia oceanica leaves based on polyvinylpyrrolidone (P. oceanica/PVP) was analyzed using the weight reduction, the open circuit potential, and the potentiodynamic polarization methods. The obtained results explained that the productivity of hindrance increments had the greatest restraint efficiency of ∼81% at 1,000 ppm, as the concentration of the extract increased. Liable for adsorption as a thin layer on the surface of mild steel to protect it, the creation of kaolin-traced phenolic and polysaccharide compounds was confirmed by the Fourier transform infrared spectroscopy analysis. A scanning electron microscope was used to evaluate the inhibitive action of P. oceanica/PVP against steel in corrosive media and the change in surface morphology was considered. It is presumed that the ethanol removed from the Posidonia oceanica leaves can fill in as a compelling consumption inhibitor for gentle steel in HCL solution (1 M).

On behalf of the Management of the Protected Marine Area of the island of Ventotene and Santo Stefano the Marine Ecology and Biology Institute of Piombino (ITALY) carried out a very in dept study aimed at knowledge of the ecological situation of the Posidonia Oceanica (L.) Delile, 1813 meadows. The most appropriate methodologies were used to be able to identify all the benthic species present in order to evaluate the efficiency of the nursery function of the prairies investigated. The results of the numerous species captured in the juvenile stage have demonstrated the excellent nursery function of the meadows of the island of Ventotene.

Underwater monitoring activities are crucial for the preservation of marine ecosystems. Currently, scuba divers are involved in data collection campaigns that are repetitive, dangerous, and expensive. This article describes the application of Information Communication Technology (ICT) tools to underwater visual data for monitoring purposes. The data refer to a Posidonia Oceanica survey mission carried out by a scuba diver using a Smart Dive Scooter equipped with visual acquisition and acoustic localization systems. An acoustic-based strategy for geo-referencing of the optical dataset is reported. It exploits the synchronization between the audio track extracted from a camera and the transponder pings adopted for the acoustic positioning. The positioning measurements are employed within an extended Kalman filter to estimate the diver's path during the mission. A visual odometry algorithm is implemented within the filter to refine the navigation state estimation of the diver with respect to the acoustic positioning only. Moreover, a smoothing step based on the Rauch-Tung-Striebel smoother is applied to further improve the estimated diver's positions. Finally, the article reports the results of two different data processing for monitoring applications. The first one is an image mosaicking obtained by concatenating subsequent frames, whereas the second one refers to a qualitative distribution of the Posidonia Oceanica over the mission area accomplished through an image segmentation process. The two outcomes are plotted over a satellite image of the surveyed area, showing that the proposed process is an effective tool capable of facilitating divers in their monitoring and inspection activities.

Concentrations of eight trace elements (V, Cr, Ni, Cu, Zn, As, Cd, and Pb) were investigated in Posidonia oceanica leaf blades and sediments sampled from 23 stations along the Turkish-Mediterranean Sea coast. Trace element (TE) concentration in both sediment and P. oceanica showed a statistically significant distribution among sampling stations. Most of the TE concentration in samples varied remarkably among stations without a consistent trend. Concentrations of Zn, Cd, Cu, and Pb in the sediment of all of the sampling stations were determined as non-polluted based on the comparison with the sediment quality guideline index. More than a quarter of the sampling stations were found as moderately or heavily polluted for Cr, Ni, and As. The mean TE concentrations found in the sediment sample in the present study were similar to the concentrations reported from the different parts of the eastern Mediterranean Sea. TE concentrations in P. oceanica were generally lower compared to the concentrations in the sediment except for Cd, Zn, and Cu. While a positive correlation was found for Ni concentrations between sediment and P. oceanica samples, negative correlation was detected for V, Cr, Zn, Cu, As, and Cd concentrations between sediment and P. oceanica. The highest bioaccumulation factor in P. oceanica was calculated for Cd. The study area of the present study, especially the western sites (provinces of Antalya and Mugla), hosts millions of tourists annually and under the influence of intensive human activities in summer. Thus, coastal waters are heavily exposed to TEs and significantly positive correlations were detected between the anthropogenic TE pollutants (As, Cd, Cu, Zn, Pb, and V) and natural sourced TE (Ni and Cr). Based on our data, the Mediterranean Sea coast of Turkey does not present significant levels of Zd, Cd, Cu, and Pb pollution, whereas 65% of the stations were heavily polluted with As. Since As categorized as carcinogenic to humans, seafood sources should be monitored in terms of As concentrations. The current data might be useful in further TE-monitoring studies and TE discharge management strategies.

11 pages, 5 figures, 2 tables, supplementary information https://doi.org/10.1038/s42003-021-02165-3.-- Data availability: The authors declare that the data supporting the findings of this study are available within the paper and its Supplementary Data files, The last hundred years have seen the introduction of many sources of artificial noise in the sea environment which have shown to negatively affect marine organisms. Little attention has been devoted to how much this noise could affect sessile organisms. Here, we report morphological and ultrastructural changes in seagrass, after exposure to sounds in a controlled environment. These results are new to aquatic plants pathology. Low-frequency sounds produced alterations in Posidonia oceanica root and rhizome statocysts, which sense gravity and process sound vibration. Nutritional processes of the plant were affected as well: we observed a decrease in the number of rhizome starch grains, which have a vital role in energy storage, as well as a degradation in the specific fungal symbionts of P. oceanica roots. This sensitivity to artificial sounds revealed how sound can potentially affect the health status of P. oceanica. Moreover, these findings address the question of how much the increase of ocean noise pollution may contribute in the future to the depletion of seagrass populations and to biodiversity loss, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

Bacteria are essential in the maintenance and sustainment of marine environments (e.g., benthic systems), playing a key role in marine food webs and nutrient cycling. These microorganisms can live associated as epiphytic or endophytic populations with superior organisms with valuable ecological functions, e.g., seagrasses. Here, we isolated, identified, sequenced, and exposed two strains of the same species (i.e., identified as Cobetia sp.) from two different marine environments to different nutrient regimes using batch cultures: (1) Cobetia sp. UIB 001 from the endemic Mediterranean seagrass Posidonia oceanica and (2) Cobetia sp. 4B UA from the endemic Humboldt Current System (HCS) seagrass Heterozostera chilensis. From our physiological studies, both strains behaved as bacteria capable to cope with different nutrient and pH regimes, i.e., N, P, and Fe combined with different pH levels, both in long-term (12 days (d)) and short-term studies (4 d/96 h (h)). We showed that the isolated strains were sensitive to the N source (inorganic and organic) at low and high concentrations and low pH levels. Low availability of phosphorus (P) and Fe had a negative independent effect on growth, especially in the long-term studies. The strain UIB 001 showed a better adaptation to low nutrient concentrations, being a potential N2-fixer, reaching higher growth rates (μ) than the HCS strain. P-acquisition mechanisms were deeply investigated at the enzymatic (i.e., alkaline phosphatase activity, APA) and structural level (e.g., alkaline phosphatase D, PhoD). Finally, these results were complemented with the study of biochemical markers, i.e., reactive oxygen species (ROS). In short, we present how ecological niches (i.e., MS and HCS) might determine, select, and modify the genomic and phenotypic features of the same bacterial species (i.e., Cobetia spp.) found in different marine environments, pointing to a direct correlation between adaptability and oligotrophy of seawater.

Foraminiferans are diverse micro- to macroscopic protists abundant especially in (sub)tropical seas, often forming characteristic benthic communities known as “living sands”. Numerous species have migrated through the Suez Canal to the Mediterranean and one of them, i.e., Amphistegina lobifera, turned invasive, gradually outcompeting the indigenous species. At some places, A. lobifera creates thick seabed sediments, thus becoming an important environmental engineer. However, little is known about the turnover of its shells in the invaded ecosystems. Using vital staining, stereomicroscopy, scanning electron microscopy, and cultivation and DNA fingerprinting, I investigated the vital status, destruction/decomposition and mycobiota of A. lobifera in the rhizosphere of the dominant Mediterranean seagrass Posidonia oceanica in an underwater Maltese meadow (average 284 shells g−1, representing 28.5 % of dry substrate weight), in comparison with epiphytic specimens and P. oceanica roots. While 78 % of the epiphytes were alive, nearly all substrate specimens were dead. On average, 80 % of the epiphytes were intact compared to 21 % of the substrate specimens. Abiotic dissolution and mechanical damage played only a minor role, but some bioerosion was detected in 18 % and >70 % of the epiphytic and substrate specimens, respectively. Few bioerosion traces could be attributed to fungi, and the majority probably belonged to photoautotrophs. The seagrass roots displayed fungal colonization typical for this species and yielded 81 identified isolates, while the surface-sterilized substrate specimens surprisingly yielded no cultivable fungi compared to 16 other identified isolates obtained from the epiphytes. While the epiphytes' mycobiota was dominated by ascomycetous generalists also known from terrestrial ecosystems (alongside with, for example, a relative of the “rock-eating” extremophiles), the roots were dominated by the seagrass-specific dark septate endophyte Posidoniomyces atricolor and additionally contained a previously unreported lulworthioid mycobiont. In conclusion, at the investigated locality, dead A. lobifera shells seem to be regularly bioeroded by endolithic non-fungal organisms, which may counterbalance their accumulation in the seabed substrate.

An acoustic resonator was used to measure the low-frequency (1–5 kHz) effective acoustic properties of the leaf blades of two Mediterranean seagrass species (Posidonia oceanica and Cymodocea nodosa). Variability along blades was assessed by measuring the effective change in sound speed per gram blade biomass of the basal and apical halves of P. oceanica leaves separately (−11 and −1.5 m s−1 g−1, respectively). Large differences in the effective sound speed per unit biomass between P. oceanica and C. nodosa (43–52 m s−1 g−1 larger for C. nodosa) are discussed using microscopic imagery of blade cross-sections.

Sediment resuspension is a common process in dynamic coastal settings, but its implications for remineralization and carbon turnover in seagrass meadows are poorly understood. Here, we assessed eelgrass Zostera marina metabolism in the Baltic Sea (SW Finland) using benthic flume-chambers and aquatic eddy covariance to critically evaluate the drivers of benthic O-2 exchange during dynamic flow conditions. During quiescent weather conditions, the 2 methods resolved similar metabolic rates and net ecosystem autotrophy (+/- 11. However, elevated flow speeds and sediment resuspension halfway through the study induced a 5-fold increase in the O-2 uptake rates measured by eddy covariance, whereas chamber fluxes remained relatively unchanged. Following particle resettlement, instruments were redeployed and the benthic O-2 uptake resolved by both techniques was just similar to 302 uptake up to 6-fold, mainly due to the reoxidation of reduced compounds (e.g. FeSx). This process was fully captured by the eddy O-2 fluxes, but not by the chamber incubation. Consequently, the chamber and eddy net ecosystem metabolism amounted to - 17 and -824 mmol C m(-2), respectively, throughout the study period. The rapid reoxidation and long-term effects of resuspension on benthic O-2 dynamics highlight the importance of fully capturing dynamic conditions when assessing the overall carbon turnover in coastal habitats. Future studies on the biogeochemical functioning of coastal environments should aim to capture the natural frequency and duration of resuspension events. Sediment resuspension is a common process in dynamic coastal settings, but its implications for remineralization and carbon turnover in seagrass meadows are poorly understood. Here, we assessed eelgrass Zostera marina metabolism in the Baltic Sea (SW Finland) using benthic flume-chambers and aquatic eddy covariance to critically evaluate the drivers of benthic O2 exchange during dynamic flow conditions. During quiescent weather conditions, the 2 methods resolved similar metabolic rates and net ecosystem autotrophy (±11% of each other). However, elevated flow speeds and sediment resuspension halfway through the study induced a 5-fold increase in the O2 uptake rates measured by eddy covariance, whereas chamber fluxes remained relatively unchanged. Following particle resettlement, instruments were redeployed and the benthic O2 uptake resolved by both techniques was just ~30% of the values measured before resuspension. Laboratory investigations revealed sediment resuspension could potentially increase benthic O2 uptake up to 6fold, mainly due to the reoxidation of reduced compounds (e.g. FeSx). This process was fully captured by the eddy O2 fluxes, but not by the chamber incubation. Consequently, the chamber and eddy net ecosystem metabolism amounted to -17 and -824 mmol C m-2, respectively, throughout the study period. The rapid reoxidation and long-term effects of resuspension on benthic O2 dynamics highlight the importance of fully capturing dynamic conditions when assessing the overall carbon turnover in coastal habitats. Future studies on the biogeochemical functioning of coastal environments should aim to capture the natural frequency and duration of resuspension events.

In the present study, we have developed an efficient system for regenerating Posidonia oceanica via the storage of free cells at low temperature and the initiation of cell encapsulation. This system could help in solving problems related to the intractable nature of in vitro marine phanerogam regeneration. Free cells from enzyme digestion were preserved with glycerol and DMSO at different concentrations and stored at low temperature. Cell encapsulation was performed with sodium alginate and calcium chloride. First, results showed that optimum cell culture was obtained when the initial cell concentration was 104 cells ml-1. Cell scaling allowed exponential growth to produce 2268000 cells at 13 d. Second, treatment based on cell storage with 60% glycerol plus 1.3 M DMSO was a success. The preserved cells grew and produced 1.96 more cells than the initial cell concentration (104 cells ml-1). Third, the encapsulated cells (beads) showed a survival range of 84 to 100% over 4 yr. The divided beads released cells that developed embryos or free cells depending on the culture medium. Cell encapsulation was the only method that was successful to acclimatise the cells to salinity, store artificial material for sowing and obtain embryos. We concluded that encapsulated cells could be used as a starting material for the production of embryos in the regeneration of P. oceanica.

Herein, we investigated for the first time the microbiota from the hepatopancreas of the talitrid amphipod Orchestia montagui and the oniscidean isopod Tylos ponticus, two crustacean species associated with beached leaves of the seagrass Posidonia oceanica (Posidonia banquette). We carried out a metabarcoding analysis based on several hypervariable regions of the bacterial 16S rRNA gene. At the same time, three representative habitats of the supralittoral zone, namely leaf surface of Posidonia banquette, sandy shore and surface seawater were examined by means of bacterial metabarcoding analysis. Our data analyses indicated that the bacterial microbiota from the hepatopancreas and that from the marine habitats form distinct groups in terms of the taxonomic composition. Comparative analyses revealed that some bacteria were associated with the hepatopancreas of the syntopic O. montagui and T. ponticus but were not detected in the supralittoral habitats. This suggests that distinct components of the microbial community may be uniquely adapted within the hepatopancreas. The microbiota from the hepatopancreas of O. montagui was more complex than that of T. ponticus. However, the putative presence of polysaccharide-degrading bacteria in both species indicated symbiotic microbiomes that might be involved in the functionality of the hepatopancreas. A deeper understanding of halophilic hepatopancreatic symbionts in the supralittoral zone also has broad relevance to applied research, particularly to the biotechnological sector related to marine biomass conversion.

Dichloromethane, chloroform, ethyl acetate and ethanol extracts obtained from Posidonia oceanica (L.) leaves, were examined in order to determine their total phenolic, flavonoid, flavonol, anthocyanin and condensed tannins contents as well as their antioxidant and allelopathic activities. The qualitative phytochemical analysis of crude extracts confirmed the presence of coumarins in dichloromethane, chloroform and ethyl acetate extracts. The antioxidant activity estimated using the DPPH assay was significantly more pronounced for the ethyl acetate extract (IC50 = 1.19±0.018 mg/mL) than that of the other extracts. The allelopathic effect against the seeds of Carum carvi (L.) and Foeniculum vulgare (Mill.) indicated that, depending on concentration, the extracts from the leaves of P. oceanic (L.) inhibited or stimulated at different concentrations the germination, shoot and root elongation of seedlings growth. The results of this study suggest that P. oceanica (L.) extracts could be useful as a natural source of health-promoting effects and herbicides. KEY WORDS: Posidonia oceanic (L.), Phytochemical profile, Phenolic compounds, Antioxidant activity, Carum carvi (L.), Foeniculum vulgare (Mill) Bull. Chem. Soc. Ethiop. 2020, 34(3), 437-447. DOI: https://dx.doi.org/10.4314/bcse.v34i3.1

Cyprus relies on seawater desalination for a large part of its drinking water supply, with reverse osmosis providing more than 95% of the total desalination capacity in the country. Nevertheless, the environmental impacts of desalination for the Cypriot environment remain poorly understood. Using a combination of mining existing governmental and corporate survey data and reports, this study explores the scale of desalination in Cyprus, the impacts on the coastal marine environment and its overall carbon footprint. Surveys of Posidonia oceanica seagrass meadows show strongly reduced density of shoots and leaf surface area, respectively. Analysis of the available data relating to the overall production of desalinated water and energy consumption reveals that 68.7 million m3 of desalinated water were produced in Cyprus in 2017, resulting in the release of 160 ktons of CO2 equivalent, representing around 2% of the total carbon emissions in Cyprus. The results are directly applicable for understanding the impacts of brine discharge on seagrass meadows, one of the most common types of Mediterranean seabed ecosystems and useful for providing guidance to decision makers as they are striving to achieve a zero-carbon economy. strategies for achieving greater sustainability in terms of reduced CO2 emissions and less brine discharge are discussed.

Posidonia oceanica is a sea grass belonging to the family Posidoniaceae, which stands out as a substantial reservoir of bioactive compounds. In this study, the secondary metabolites of the P. oceanica rhizome were annotated using UPLC-HRESI-MS/MS, revealing 86 compounds including simple phenolic acids, flavonoids, and their sulphated conjugates. Moreover, the P. oceanica butanol extract exhibited substantial antioxidant and antidiabetic effects in vitro. Thus, a reliable, robust drug delivery system was developed through the encapsulation of P. oceanica extract in gelatin nanoparticles to protect active constituents, control their release and enhance their therapeutic activity. To confirm these achievements, untargeted GC-MS metabolomics analysis together with biochemical evaluation was employed to investigate the in vivo anti-diabetic potential of the P. oceanica nano-extract. The results of this study demonstrated that the P. oceanica gelatin nanoparticle formulation reduced the serum fasting blood glucose level significantly (p < 0.05) in addition to improving the insulin level, together with the elevation of glucose transporter 4 levels. Besides, multivariate/univariate analyses of the GC-MS metabolomic dataset revealed several dysregulated metabolites in diabetic rats, which were restored to normalized levels after treatment with the P. oceanica gelatin nanoparticle formulation. These metabolites mainly originate from the metabolism of amino acids, fatty acids and carbohydrates, indicating that this type of delivery was more effective than the plain extract in regulating these altered metabolic processes. Overall, this study provides novel insight for the potential of P. oceanica butanol extract encapsulated in gelatin nanoparticles as a promising and effective antidiabetic therapy.

Compared to other coasts, Libyan coasts are characterized by low levels of pollution. This makes them a suitable environment for marine diversity, especially seaweeds, which may be considered a source of new compounds that are biologically active in their resistance to microbes. Therefore, the present study was conducted with the aim of testing the bioactivity of leave and rhizome extracts of Posidonia oceanica seaweed (aqueous, ethanol, and acetone) at concentrations (50, 100, and 150) mg/ml against three types of pathogenic bacteria (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa), and fungus (Candida spp.), by a sensitivity test in the form of a disk diffusion method. The results showed that Posidonia oceanica seaweed extracts have good inhibitory activity against S.aureus and Candida spp., and that the concentration of 150 mg/ml is the most effective for all extracts. The results also indicated that rhizome extracts are more efficient than leaf extracts, and the acetone extract is the best in inhibiting the tested microbes. Also, Escherichia coli and Pseudomonas aeruginosa are the most resistant to all extracts, regardless of type and concentration used.

Vegetation cover on the sea floor plays an important role in marine health, and sonar systems can provide detailed observation and evaluation of sea floor vegetation under rapidly changing environmental conditions. Various acoustic techniques are available for this purpose. In this study, a split beam echo sounder operating at a frequency of 206 kHz was employed. Simultaneous dive expeditions were performed for direct acoustic observations. The aim of this study was to use the BioSonics EcoSAV software program to generate acoustic estimates of leaf height and create seasonal distribution maps in Posidonia oceanica meadows distributed between Lara and Manavgat in the Gulf of Antalya (Turkey). Calculation of program parameters by species and acoustic identification of P. oceanica were carried out with the aid of the PAST 3.05 (PAleontological STatistics) statistics program, enabling isolation of P. oceanica and other non-target species from the sea floor. The results revealed three major meadow beds in the study area. The maximum leaf height was observed in July (80–90 cm), followed by April/May (70–80 cm), with the shortest leaf height in January (40–50 cm). The biomass of the leaves varied seasonally between 100 and 1000 g/m2 and decreased by the seafloor depth in a year. This method proved effective for mapping and monitoring important seasonal habitat parameters such as the distribution of aquatic vegetation., Deniz tabanındaki bitkiler deniz sağlığının göstergesi olarak önemli bir rol oynarlar ve sonar sistemleri çevre koşuların ani değişimleri durumundadeniz tabanı bitki örtüsünün ayrıntılı gözlem ve değerlendirmesini sağlayabilir. Bu tür çalışmalar için değişik akustik teknikler mevcuttur. Bu çalışmada, 206 kHz frekanslı split beam ekosounder kullanılmıştır. Akustik çalışma esnasında, eşzamanlı dalış seferleri de yapılmıştır. Bu çalışmanın amacı BioSonics EcoSAV ticari yazılımı kullanarak Antalya Körfezi’nin (Türkiye) Lara-Manavgat arasındaki bölgede bulunan Posidonia oceanica yaprak boyu tahmini yapmak ve mevsimsel dağılım haritasını çıkartmaktır. Program parametrelerinin hesaplanması ve deniz tabanındaki hedef olmayan diğer türlerden P. oceanica’nın ayrılabilmesi ve P. oceanica çayırının akustik olarak tanımlanmasında PAST 3.05 (PAleontological STatistics) istatistik programı, kullanılmıştır. Sonuçta, çalışma alanında 3 büyük deniz çayırı yatağının var olduğu tespit edilmiştir. En yüksek yaprak boyu Temmuz ayında ve 80–90 cm olarak, daha kısa yaprak boyu ise Nisan/Mayıs aylarında (70–80 cm) en kısa yaprak boyu ise Ocak ayında (40–50 cm) ölçülmüştür. Yaprak biyokütlesi mevsimsel olarak 100 ve 1000 g/m2 arasında değişmiştir ve deniz tabanı derinliği ile azalmıştır. Bu metodun, sucul bitkilerin dağılımı gibi mevsimsel habitat parametrelerinin haritalanması ve izlenmesinde etkili olduğu ortaya konulmuştur.

The Alghero Bay is a coastal area of high economic value because of the presence of one of the most popular beaches of Sardinia (San Giovanni, Maria Pia, Le Bombarde, Lazzaretto). The organisms living in the meadow of Posidonia oceanica, which densely cover the offshore areas of the bay, represent the most important source of sediments to these beaches. For this reason, a detailed mapping of the local seabed features and distribution of P. oceanica constitutes an important tool for the coastal managing of the area. The integrated use of several methodologies, such as Side Scan Sonar, Remote Operating Vehicle, Drone and direct sediment sampling has allowed us to realize a very detailed seafloor map of the Alghero Bay.

The study was carried out in Gokceada, located in the North Aegean Sea in 2017, during winter and summer seasons and the concentrations of 16 polycyclic aromatic hydrocarbon (PAH) components were determined in P. oceanica type seagrass samples. Total PAH (TPAH) values ranged from 190.8 to 7668.7 ng g−1 dw during the sampling period. In addition, the source of pollution was investigated by using PAH ratios. According to the fluoranthene (FA) /pyrene (PY) ratio in the winter period, the origin of pollution is mostly pyrolytic, while in the summer period, according to the fluoranthene (FA) /pyrene (PY) and benzo(a)anthracene (BaA) /chrysene (CHR) ratio, the pollution origin was found to be petrogenic.

Meiobenthic nematodes are well-known bioindicators in aquatic ecosystem health programs. However, the explored taxa are still limited and practically devoted to the community level. The present study provided a new method of experimental isolation of a species from a pristine nematofauna. In our method, the nematofauna faced two types of sediment, namely, the leaves of Posidonia oceanica and shells of Mytilus galloprovincialis, under controlled laboratory conditions, and several changes in species composition occurred through gradual selection of the most adaptable nematode taxa to the new environments, which were previously defaunated. We used the selected nematode taxon, Marylynnia puncticaudata (Cyatholaimidae), to examine the possible effects of organic enrichment, and the results clearly showed that the body size of the nematodes significantly increased and they became fat when after enrichment using a powder made of marine agar (1200 mg l−1) and cuticles of Crangon crangon (900 mg l−1), but their relative body growth showed no discernible changes.

Epiphytic microalgae attached to Posidonia oceanica leaves play a significant role through primary production, nutrient cycling and trophic fluxes in benthic ecosystems. Due to their sensitivity, epiphytic microalgae respond to environmental alterations more quickly than their host. The aim of this study is therefore to evaluate the ecological quality in Gökçeada Underwater Park (North Aegean) using epiphytic microalgal composition and abundance. In this respect, P. oceanica shoots are collected at 6m, 15m and 28m in May, July, October 2009 and January 2010 to estimate the microalgal composition and abundance. Also, P. oceanica descriptors and physico-chemical parameters in the water column of the meadow lower limit are measured. Leaf surface improvement through greater depths, have provided a convenient substratum for epiphytic colonization. A total of 56 taxa belonging to epiphytic microalgae are composed of Bacillariophyceae (91%), Cyanophyceae (7%) and Dinophyceae (2%). Temporal and bathymetric dynamics of the epiphytic community structure and abundance depend on the environmental parameters; such as leaf surface, nutrients and turbidity. Also, a mucilage phenomenon, resulted in a low diversity due to the dominancy of filamentous cyanobacteria. Necessary data is supplied for a less evaluated region affected by agricultural activities and urbanization in the recent years.

The Mediterranean seagrass Posidonia oceanica, which provides highly valuable ecosystem services, is subject to increasing anthropogenic pressures, causing habitat loss or fragmentation. Whilst airborne images and acoustic data can be used for monitoring seagrass coverage at a macro-scale and over long time periods, monitoring its health in the short term requires precision mapping in order to assess current regression/progression of individual meadows. However, current fine-scale underwater techniques in the field are imprecise and time-demanding. We propose an automatic classification approach based on underwater photogrammetry for an operational, cost- and time-effective fine-scale monitoring method. The method uses a property of the sparse cloud generated during bundle adjustment—the reconstruction uncertainty—to map seagrass patches. The mean precision, recall and F1 score of the method over 21 study sites with different morphologies were 0.79, 0.91 and 0.84, respectively. However, the fragmentation level of the meadows had a significant negative effect on classification performances. The temporal monitoring of 3 sites using this method proved its operability and showed a positive evolution index of the corresponding meadows over a period of 3 yr. This method is generalizable for most encountered configurations and can be integrated in a large monitoring system, as it enables the production of numerous seagrass maps over a short period of time. Moreover, our methodology could be generalized and applied in the study of other submerged aquatic vegetation by adjusting the method’s parameters.

Seagrass meadows are essential for protection of coastal erosion by damping wave and stabilizing the seabed. Seagrass are considered as a source of water resistance which modifies strongly the wave dynamics. As a part of EDF R & D seagrass restoration project in the Berre lagoon, we quantify the wave attenuation due to artificial vegetation distributed in a flume. Experiments have been conducted at Saint-Venant Hydraulics Laboratory wave flume (Chatou, France). We measure the wave damping with 13 resistive waves gauges along a distance L = 22.5 m for the “low” density and L = 12.15 m for the “high” density of vegetation mimics. A JONSWAP spectrum is used for the generation of irregular waves with significant wave height Hs ranging from 0.10 to 0.23 m and peak period Tp ranging from 1 to 3 s. Artificial vegetation is a model of Posidonia oceanica seagrass species represented by slightly flexible polypropylene shoots with 8 artificial leaves of 0.28 and 0.16 m height. Different hydrodynamics conditions (Hs , Tp , water depth hw ) and geometrical parameters (submergence ratio α, shoot density N) have been tested to see their influence on wave attenuation. For a high submergence ratio (typically 0.7), the wave attenuation can reach 67% of the incident wave height whereas for a low submergence ratio ( depending on 2 dimensionless parameters: the Reynolds and Keulegan-Carpenter numbers. These relationships are compared with other similar studies.

International audience; The Red Sea and Indian Ocean seagrass Halophila stipulacea entered the Mediterranean in the late 19th century via the Suez Canal. Here, we report on the discovery of a population of H. stipulacea covering 16.5 ha off the harbour of Cannes, French Riviera, France. This represents the northernmost locality of the species and a jump of 350 km to the north from its closest western Mediterranean locality (Razza di Juncu in Sardinia). At Cannes, it was found dwelling between 11 and 17 m depth on a dead matte of Posidonia oceanica. The species has most probably been introduced through mega-yacht or cruise ship anchoring since the Bay of Cannes is among the most highly-frequented places for luxury yachting and tourism. The lack of effective regulation to prevent the introduction of non-indigenous species in France and Europe is highlighted.

International audience

[EN] Posidonia oceanica meadows are ecosystem engineers that play several roles in marine environment maintenance. In this sense, monitoring of the spatial distribution and health status of their meadows is key to make decisions about protecting them against their degradation. With the aim of checking the ability of a simple low-cost acoustic method to acquire information about the state of P. oceanica meadows as ecosystem indicators, ground-truthing and acoustic data were acquired over several of these meadows on the Levantine coast of Spain. A 200 kHz side scan sonar in a vertical configuration was used to automatically estimate shoot density, canopy height and cover of the meadows. The wide athwartship angle of the transducer together with its low cost and user friendliness entail the main advantages of this system and configuration: both improved beam path and detection invariance against boat rolling. The results show that canopy height can be measured acoustically. Furthermore, the accumulated intensity of the echoes from P. oceanica in the first 30 centimeters above the bottom is indirectly related to shoot density and cover, showing a relation that should be studied deeply., Funding for open access charge: Universitat Politècnica de València

A study was conducted to estimate biometry of an epiphytic micro-calcareous red algae, Hydrolithon boreale found on leaves of a Mediterranean meadow, Posidonia oceanica along the entire Turkish coast of the Mediterranean Sea in time (winter and summer 2019) and space (regions, and bottom type and depth). Percent occurrence of the epiphyte was lower in winter (25%), particularly found in a small bay in the west than summer (44%), entirely along the coast. The epiphyte grew up to 5 mm in diameter, 0.35 mm in thickness of the crust size, and was populated up to 1006 ind/m2 in summer owing to the increased utilization of the carbonate by the epiphyte with the increased water temperature. The size was contrasted to the density (abundance and biomass) in space. The biometry was significantly dependent on the siliciclastic-carbonate deposition as inferred from SiO2 of the water in relation the leaf area index (LAI) of P. oceanica. Therefore, this deposition induced specimens growing in size, followed by the reduced density in relation to N-based nutrient of the water. Further major environmental parameters which negatively affected the biometry were pH and total suspended matter of the water, analogous to the turbidity. Of the trace elements, Ni was negatively correlated with the biometry whereas the LAI was however positively correlated with all the anthropogenic-sourced trace elements (V, Cu, Zn, As, Cd, and Pb) in the leaves. Of the bottom types, the calcite rock had higher density than the other soft bottoms in contrast to the size of the epiphyte.

Anthropogenic impacts on Posidonia oceanica meadows have led to a decline of this ecosystem throughout the Mediterranean. Transplantations have often been prescribed as a compensation measure to mitigate the impacts caused by coastal maritime works. Here a Q methodology approach was used to investigate the stakeholders’ attitudes in four case studies of P. oceanica transplants realized in Italian waters. Twenty-two respondents were asked to score 37 statements, and the resultant Q-sorting was analyzed via an inverse PCA using the KADE software. Four discourses, corresponding to the significant axes in the factorial analysis were identified: science and conservation (F1), oriented at a rigorous scientific approach, engineering and industry (F2), oriented at the economic development, environmentalism and participation (F3), oriented at the conservation of seagrass meadows, and transplantation-oriented (F4), oriented at the realization of transplants as compensation measures. The main conflicts and agreements between discourses are assessed and discussed, based on the analysis of the distinguishing statements that contributed to consensus or disagreement among discourses. The benefits of the Q methodology in the identification and mediation of conflicts in the four case studies are discussed, and its potential as a powerful aid in the development of a good environmental governance is acknowledged.

Seagrass species play a critical role in the mitigation of climate change by acting as valuable carbon sinks and storage sites. Another important ecosystem service of this coastal vegetation is nutrient removal. However, coastal ecosystems are under increasing pressure of global warming and associated establishment of invasive species. To elucidate the respective contributions of seagrass species Posidonia oceanica and Cymodocea nodosa and the non-native macroalga Halimeda incrassata as primary producers and nutrient sinks in coastal habitats we conducted in-situ incubations in the North-western Mediterranean Sea. Measured metabolic activity and nutrient removal as well as calcification rates in these habitats over a 24 h period in spring and summer confirmed that the endemic seagrass P. oceanica represents a valuable ecosystem with high O2 production and considerable carbon capture. The documented regression of P. oceanica meadows with higher temperatures and decline in autotrophy as measured here causes concern for the continuity of ecosystem services rendered by this habitat throughout the Mediterranean Sea with progressing climate warming. In contrast, the enhanced performance of C. nodosa and the calcifying alga H. incrassata with increasing temperatures, under expected rates of future warming is uncertain to mitigate loss of productivity in case of a potential shift in marine vegetation. This could ultimately lead to a decline in ecosystem services, decreased carbon storage and mitigation of climate change. Furthermore, this study provides a first estimate for the growth rate of H. incrassata in the Mediterranean Sea, supporting evidence for the mechanism of its rapid extension., Funding was provided by projects PRD2018/18, from the Conselleria d’Innovació, Recerca i Turisme of Mallorca (Spain) and RTI2018-095441-B-C21 (SUMAECO) from the Spanish Ministry of Science, Innovation and Universities. SF was supported by a “Margalida Comas” postdoctoral scholarship, funded by the Balearic Islands Government.

Posidonia oceanica is a long-living and very slow-growing marine seagrass endemic to the Mediterranean Sea. It produces large amounts of leaf material and rhizomes, which can reach the shore and build important banks known as “banquettes.” In recent years, interest in the potential uses of these P. oceanica banquettes has increased, and it was demonstrated that biomass extracts showed antioxidant, antifungal, and antiviral activities. The discovery of new compounds through the culture of microorganisms is limited, and to overcome this limitation, we performed a metagenomic study to investigate the microbial community associated with P. oceanica banquettes. Our results showed that the microbial community associated with P. oceanica banquettes was dominated by Alphaproteobacteria, Gammaproteobacteria, Bacteroidetes, and Cyanobacteria. Pseudoalteromonas was the dominant genus, followed by Alteromonas, Labrenzia, and Aquimarina. The metagenome reads were binned and assembled into 23 nearly complete metagenome-assembled genomes (MAGs), which belonged to new families of Cyanobacteria, Myxococcota, and Granulosicoccaceae and also to the novel genus recently described as Gammaproteobacteria family UBA10353. A comparative analysis with 60 published metagenomes from different environments, including seawater, marine biofilms, soils, corals, sponges, and hydrothermal vents, indicated that banquettes have numbers of natural products and carbohydrate active enzymes (CAZymes) similar to those found for soils and were only surpassed by marine biofilms. New proteins assigned to cellulosome modules and lignocellulose-degrading enzymes were also found. These results unveiled the diverse microbial composition of P. oceanica banquettes and determined that banquettes are a potential source of bioactive compounds and novel enzymes. IMPORTANCE Posidonia oceanica is a long-living and very slow-growing marine seagrass endemic to the Mediterranean Sea that forms large amounts of leaf material and rhizomes, which can reach the shore and build important banks known as “banquettes.” These banquettes accumulate on the shore, where they can prevent erosion, although they also cause social concern due to their impact on beach use. Furthermore, Posidonia dry material has been considered a source of traditional remedies in several areas of the Mediterranean, and a few studies have been carried out to explore pharmacological activities of Posidonia extracts. The work presented here provides the first characterization of the microbiome associated with Posidonia banquettes. We carried out a metagenomic analysis together with an in-depth comparison of the banquette metagenome with 60 published metagenomes from different environments. This comparative analysis has unveiled the potential that Posidonia banquettes have for the synthesis of natural products, both in abundance (only surpassed by marine biofilms) and novelty. These products include mainly nonribosomal peptides and carbohydrate active enzymes. Thus, the interest of our work lies in the interest of Posidonia “waste” material as a source of new bioactive compounds and CAZymes.

The present study investigates the impacts of low pH on the cell structure of the seagrasses Posidonia oceanica (L.) Delile and Cymodocea nodosa (Ucria) Ascherson. The study was applied with in situ experiments at the Castello Aragonese of Ischia (Naples, Italy), where shallow submarine vents, lowering the pH, can be used as natural laboratories. Shoots of the seagrasses were transferred from the control area (pH 8.1) to the two venting areas (pH 7.8 and 6.8) for different times. Epidermal cells of young leaves were examined using transmission electron microscopy (TEM) and tubulin immunofluorescence. After one week at pH 7.8, the cell structure of Posidonia oceanica was normal, while in Cymodocea nodosa microtubule (MT) network and cell structure were affected. In addition, in C. nodosa, ultrastructural analysis revealed a gradual degradation of the nuclei, a disorganization of the chloroplasts, and an increase in the number of mitochondria and dictyosomes. The exposure of both plants for 3 weeks at pH 6.8 resulted in the aggregation and finally in the dilation of the endoplasmic reticulum (ER) membranes. Tubulin immunofluorescence revealed that after three weeks, the MT cytoskeleton of both plants was severely affected. All these alterations can be considered as indications of an apoptotic like programmed cell death (AL-PCD) which may be executed in order to regulate stress response.

The Mediterranean basin is a hot spot of climate change where the Posidonia oceanica (L.) Delile (PO) and other seagrass are under stress due to its effect on marine habitats and the rising influence of anthropogenic activities (tourism, fishery). The PO and seabed ecosystems, in the coastal environments of Pantelleria and Lampedusa, suffer additional growing impacts from tourism in synergy with specific stress factors due to increasing vessel traffic for supplying potable water, fossil fuels for electrical power generation. Earth Observation (EO) data, provided by high resolution (HR) multi/hyperspectral operative satellite sensors of the last generation (i.e. Sentinel 2 MSI and PRISMA) have been successfully tested, using innovative calibration and sea truth collecting methods, for monitoring and mapping of PO meadows under stress, in the coastal waters of these islands, located in the Sicily Channel, to better support the sustainable management of these vulnerable ecosystems. The area of interest in Pantelleria was where the first prototype of the Italian Inertial Sea Wave Energy Converter (ISWEC) for renewable energy production was installed in 2015, and sea truth campaigns on the PO meadows were conducted. The PO of Lampedusa coastal areas, impacted by ship traffic linked to the previous factors and tropicalization effects of Italy southernmost climate change transitional zone, was mapped through a multi/hyper spectral EO-based approach, using training/testing data provided by side scan sonar data, previously acquired. Some advanced machine learning algorithms (MLA) were successfully evaluated with different supervised regression/classification models to map seabed and PO meadow classes and related Leaf Area Index (LAI) distributions in the areas of interest, using multi/hyperspectral data atmospherically corrected via different advanced approaches.

Posidonia oceanica is an endemic Mediterranean seagrass used as a ‘biological quality element’ in monitoring programmes of the EU Water Framework Directive, providing information about coastal ecosystems status. The regression of P. oceanica meadows caused a growing interest among policy makers to assess the value of seagrasses and to increase their protection. An evaluation of P. oceanica meadows located in the Ligurian-Provençal basin (NW Mediterranean) through a biophysical approach is here developed. Six meadows located in Liguria (Italy) and Corsica (France) were investigated by applying the emergy analysis to assess the natural capital (NC) stocked by leaves and rhizomes components. Results highlighted the importance of carrying out an analysis of the variations in the NC value in both components: rhizomes defined the growth stage and the capacity to store NC over time, leaves provided information on the variability due to disturbances in the water column. Emergy analysis allows defining the NC, in terms of resources needed to maintain the meadows and to provide services to coastal communities. This research is inserted into the effort of incorporating the NC evaluation into marine planning and decision making to achieve nature conservation goals, while ensuring the sustainable exploitation of marine resources.

This study focuses on the analysis of a carbonate pocket beach located along a coastal sector of the Apulia Ionian-Sea (Le Dune beach). The beach develops for about 800 m and it is exposed to the south-westerly and southerly seas. Coastal sediments range from very coarse to medium-fine and they are mainly composed of bioclasts (more than 90%). The study area is part of a marine protected reserve characterised by 15 different habitats of the typical Mediterranean submerged populations and the presence of Posidonia Oceanica meadows. The absence of sediment-delivering rivers coupled with the significant anthropic pressure in the last decades, have led the Ionian littorals to be affected by erosional processes. Therefore, the aim of our research is to highlight the correlation between physical and biological processes by analysing the textural and compositional characteristics of beach sands, fundamental for pocket beach conservation. This research is part of a multidisciplinary project devoted to the analysis of beaches by integrating sedimentological, geomorphological and geophysical investigations to obtain reliable models for their evolution in space and time.

Since the seagrass Posidonia oceanica is highly sensitive to environmental changes, a monitoring of the physiognomy, phenology and lepidochronology of the meadows was conducted during 2015-2020 at Tremiti Islands Marine Protected Area (Adriatic Sea). The meadow resulted stressed where anthropogenic disturbances occurred, while the implementation of proper management measures proved to trigger the recovery of the habitat. Our results underlined the importance of P. oceanica as a biological indicator to monitor human activities at local scale.

The health of seagrass plants, and thereby the ecosystems they form, is linked to their associated microbial communities. However, the role of the microbiome in holobiont function and health remains poorly understood for most seagrass species and environmental pressures, and there is, therefore, a need to better understand the drivers behind the formation of and external influences on the seagrass microbiome. Using a core microbiome framework, we characterised the leaf microbiomes of 6 estuarine seagrass populations after a precipitation event to explore how the microbiomes vary across different sites and salinities over a regional spatial scale. We found that each estuary had distinct core bacterial community structures (beta-diversity), but shared a more similar fungal core community structure. We hypothesise that the differences in the bacterial members of the microbiomes among estuaries are generally the result of each estuary being influenced by unique watersheds and sources of prokaryotes. In contrast, the similarity in the core fungal communities suggests that the eukaryotic components of the microbiomes are likely under selection or result from similar colonisation pathway(s). We also found that the bacterial taxa driving the differences among estuaries were linked to the salinity of the estuary, likely due to (1) the general epibiotic nature of colonisation (i.e. watershed source and exposure) and (2) members or functional groups within the leaf microbiome assisting seagrasses in coping with the extreme salinities. These results are valuable for linking microbiomes to the resilience of seagrasses living within dynamic estuaries experiencing a range of physicochemical pressures.

Aim: The endemic seagrass Posidonia oceanica is a key component of the coastal seascapes of the Mediterranean Sea, where it provides crucial ecosystem services and promotes the assembly of diverse ecological communities. Although protection policies exist, P.oceanica meadows have been steadily declining in the recent past because of human activities and climate change. Here, we quantitatively analyse basin-wide patterns of seagrass connectivity over a 30-year-long period and identify connectivity hotspots that may serve as priority targets for conservation actions. Location: Mediterranean Sea. Time period: 1987–2016. Major taxa studied: The seagrass P.oceanica. Methods: A biophysical Lagrangian approach is used to simulate dispersal of seagrass fruits operated by marine currents. Connectivity metrics (self-retention, indegree and outdegree) are evaluated on top of Lagrangian simulations to identify the most ecologically connected areas. Time series of local connectivity scores are analysed to study temporal variability and possibly detect trends at different spatial scales. Results: Spatio-temporal variability is an important component of seagrass connectivity in the Mediterranean. Connectivity hotspots are unevenly distributed in all of its four main sub-basins, and along both European and African coastlines. Although statistically significant local trends in connectivity are generally quite infrequent across the whole basin, they appear to be relatively more prevalent in connectivity hotspots. The interannual variability of average connectivity scores seems to be at least partially linked to meteorological fluctuations. Main conclusions: The present study represents a step forward in the application of a quantitative, scalable and replicable methodological framework for the prioritization of seagrass conservation actions in the Mediterranean large marine ecosystem, a challenging environment characterized by complex socio-economic boundary conditions and high sensitivity to the localized effects of global climate change.

The Costa Concordia shipwreck permitted to assess how multiple disturbances affected marine biota at different spatial and temporal scales, evaluating the effects of mechanical and physical disturbances on Posidonia oceanica (L.) Delile, an endemic seagrass species of the Mediterranean Sea. To assess the impacts of the shipwreck and its salvaging from 2012 to 2017 at a population and a landscape level, a diversified approach was applied based on the application of a geographical information system coupled with seascape metrics and structural descriptors. Benthic habitat maps and seascape metrics highlighted cenotic transitions, as well as fragmentation and erosion phenomena, resulting in 9952 m2 of seagrass area impacted. Regression of the meadow was unveiled by both multivariate and interpolation analysis, revealing a clear spatio-temporal gradient of impacts based on distances from the wreck. Results highlighted the effectiveness of the descriptors involved that permitted to reveal temporal changes at both fine and large scales.

A significant example of circular economy application concept is the recycling of wastes through co-composting to obtain techno-soils and composts. The objective of this paper was to demonstrate that the co-composting of Posidonia oceanica residues with decontaminated sediments is an effective method to manage two kinds of waste and transform them in a suitable material for the preparation of growth substrates. To demonstrate the effectiveness of the co-composting process, a protocol, involving physical–chemical, biochemical, and toxicological parameters, has been followed. Moreover, to evaluate the quality of the different Posidonia-based composts, the characteristics have been compared with threshold values proposed in the Italian regulation for plant growth substrates and to specific parameters from the scientific literature. All the obtained composts responded to the main characteristics for composting and growing media preparation provided in national and international regulations, in terms of pH (6.7–7.6), electrical conductivity (0.13–0.30 dS/m), and total organic carbon content (6.62–27.9 C%). Moreover, results about humic carbon (16.6–21.9 C%), germination index (139–158%), enzymatic activities (B-glucosidase: 3538–5367 mmol MUB/kg ds H), bulk density (0.30–0.83 g/cm3), and cation exchange capacity (43.3–126 meq/100 g ds) proved the quality of the P. oceanica and sediment based composts. These results are an endorsement of Posidonia with sediment-based composts use as a constituent of techno-soils and, as a component for the preparation of nursery growth substrate. It is possible to claim that the co-composting process is an alternative management strategy for decontaminated sediments and P. oceanica residues to be recommended. Adequate policies are needed in order to recycle Posidonia oceanica residues and decontaminated sediments, namely two kinds of waste, into a secondary raw material, namely techno-soil, thus implementing the concept of the circular economy.

This study assesses the characteristics of the metallic trace elements (Fe, Cd, Cu, Pb and Zn) in the Paracentrotus lividus gonads. The physiological indices evolution (RIm and GIm) was adopted in order to determine the laying period of this echinoid; and to support the hypothesis that this species may be considered as an excellent bioindicator in the marine environment. For this purpose, two edible sea urchin populations with a diameter between 41 and 71 mm were sampled. This samples were taken from two different sites, Salamandre area (presence of rocky seabed rich of photophilic algae, with less biodiversity), and Sidi Lakhdarin area (presence photophilic algae and Posidonia oceanica, more biodiversity). Each sample was evaluated by the coupled plasma mass spectrometry (ICP-MS) method. The results obtained show that there is a significant variation (p

The use of Posidonia oceanica (PO) waste biomass for energy production is under consideration in several countries of the Mediterranean region. The aim of this paper is an evaluation of using PO waste as a biomass source for direct combustion in territorial contexts where the presence of large quantities of beached seagrass is a problem for the tourism-orientated economy such as Istrian peninsula in Croatia. The presence of large PO leaves deposits on the Istrian beaches is responsible for some negative inconveniences, such as the odor released during the natural degradation processes. Other problems are connected with the visible appearance of the beach and negative connotation of PO with pollution of the touristic area. This condition reduces the possibility of touristic competitiveness of the hotels, apartments, bars, and restaurants that are located along the seaside promenade or beaches covered with PO biomass. This paper shows data of PO waste properties as a resource for energy generation which can help to decrease costs of their collection and could improve the quality of life of residents and tourists in the nearby areas. From energy properties, the heating values of fresh and dried onshore biomass samples of PO biomass were within the range of main agricultural and forest biomass and it was around 9–11 MJ/kg ; ash content is very high (16–36%) compared with other types of biomass. Due to the abovementioned data, PO waste carries some inherent limitations to its use as biomass in direct combustion and energy generation, primarily due to high ash content. Furthermore, PO waste can be recognized as a potential fuel for combustion or co- combustion due to its low sulphur (1.15–2.36%) and nitrogen (1.47–2.39%) content but the low carbon content (25–32%) is not a favorable characteristic. It can be concluded that PO waste is a potentially interesting source for energy production.

Coastal habitats provide a plethora of ecosystem services, yet they undergo continuous pressure and degradation due to the human-induced climate change. Conservation and management imply continuous monitoring and mapping of their spatial distribution at first. The present study explores the capabilities of the Copernicus Sentinel-2 mission and the contribution of its coastal aerosol band 1 (443 nm) for the mapping of the dominant Mediterranean coastal marine habitats and the bathymetry in three survey sites in the East Mediterranean. The selected sites have shallow to deep habitats and a high variability of oceanographic and seabed morphological conditions. The major findings of our study demonstrate the advantages of the downscaled Sentinel-2 coastal aerosol band 1 for both optically shallow habitat and satellite-derived bathymetry mapping due to its great water penetration. The use of Sentinel-2 band 1 allows detection of Posidonia oceanica seagrass beds down to 32.2 m of depth. Sentinel-2 constellation with its 10-m spatial resolution at most of the spectral bands, 5-day revisit frequency and open data policy can be an important tool to provide crucial missing information on the spatial distribution of coastal habitats and on their bathymetry distribution, especially in data-poor and/or remote areas with large gaps in a retrospective, rapid and non-intrusive manner. As such, it becomes a crucial ally for the conservation and management of coastal habitats globally.

Mediterranean brachiopods are elusive organisms to find alive even if the bathymetric range of some species extends to very shallow waters. We here record an abundant population of Joania cordata (Risso, 1826) and Argyrotheca cuneata (Risso, 1826) in the rhizome layer of a Posidonia oceanica (Linne) Delile, 1813 meadow in Plakias, southwestern Crete from 5 to 20 m depth. Altogether, we collected 963 living individuals and 4309 shells by suction sampling; it is the largest collection of living brachiopods in Posidonia meadows ever reported. Although literature records on the occurrence of shallow-water brachiopods in this habitat are few, we claim that Posidonia rhizomes are a particularly suitable infralittoral habitat for these organisms due to their sciaphilous conditions. Suction sampling is an effective technique to collect them and can enable the discovery of many more populations in the Mediterranean Sea.

In this study a multiscale biomonitoring approach, which encompasses multiple levels of observations (from ultra- to meso- and macroscale, photo mosaicing and SRS), was applied to evaluate the conservation status of a P. oceanica meadow. In particular, the approach included a combination of molecular and biochemical parameters associated to the assessment of plant phenology and large-spatial bed structure and heterogeneity, which have ecological relevance. The aim was to identify a toolbox of reliable and economically feasible indicators to efficiently monitor and manage seagrass meadows. At ultrascale level, the OJIP-test, a screening test based on the quantitative analysis of the chlorophyll a fluorescence, was used for the first time on P. oceanica. At molecular level we tested the expression pattern of a panel of genes involved in the stress and photosynthesis pathways, as fast and sensitive response to stress exposure. At the microscale level, phenological features of P. oceanica were considered; at mesoscale level, the morphology of the meadow was determined by a photomosaicing technique. Finally, at a macroscale level, a spatially extensive map was produced by Remote Sensing approach. An anticipatory signal of pressure impending on the P. oceanica meadows was provided by molecular and biochemical markers, thus confirming the importance of a multiscale approach to asses a risk conditions in a natural environment, before these have a long-term effect.

Diatoms are often the dominating group of benthic microalgae living on different types of bottom substrates. Their effects on invertebrate consumers is not well-documented. We here investigate the effects of feeding on another two benthic diatoms, Cocconeis scutellum and Diploneis sp., isolated from leaves of the seagrass Posidonia oceanica, on the sea urchin Paracentrotus lividus. Our results indicate a noxious effect on sea urchin embryos spawned from adults fed on Diploneis sp., with an increasing number of malformed embryos with respect to those spawned from adults fed on Ulva rigida (used as a feeding control). In contrast C. scutellum did not induce any morphological effect on embryos, similar to control non-diatom diets. Moreover, de novo obtained transcriptome indicated that oxidation-reduction process, translation, proton and electron transmembrane transport, ATP/RNA/GTP/heme/calcium and metal ion binding, NADH dehydrogenase activity, cytochrome c oxidase were affected by feeding of sea urchins on Diploneis sp. Our findings have considerable ecological significance considering that diatom biomass ingested by the sea urchin in these experiments is within the range of cell densities characterizing P. oceanica leaves where sea urchins live and spawn.

Coastal areas include highly complex ecosystems that encompass many different and productive resources worldwide. Although having such great importance, the lack of basic knowledge concerning the marine habitat distribution and biodiversity along the Turkish shoreline is an undeniable reality. In this study, seagrass beds in the bays along the Eastern Aegean Sea coast were located and mapped. Traditionally, sea-truth data used for satellite-image and other analysis are collected through direct observations requiring scuba divers or by aquatic video-camera observation. This study included a combination of acoustic technology, video recording and interpretation, geomorphological, oceanographic, and sedimentological evaluation in order to make significant contributions of current technology. The classification of the evaluated Subbottom Profiler (SBP) records exhibited their high discrimination capacity between different sea-bed features, making them appropriate for ground distinction. Linking of the SBP data sets to the Side Scan Sonar (SSS) records (object-based analysis) provide to full coverage, high resolution benthic habitat maps. For this purpose, Side Scan Sonar, 3.5/10 kHz Subbottom Profiler data were collected to a range of 50 m water depth, the data was recorded for a total 1600 km2 coastal area that consists of approximately a total 3000 km long and 1km wide grid system for Edremit, Çandarlı, Gülbahçe, Ildır, Güllük and Gökova Bays. In the study area, it was determined that the seagrasses are under danger where high human influence is located. Dense distribution of invasive macroalgae (Caulerpa cylindracea, Stypopodium schimperi) were seen at the southern and northern part of the study area subjected to human activities.