The Mediterranean basin is the second largest global biodiversity hotspot in the world, which coexists with a plethora of anthropogenic stress. This study examines the risks that marine litter poses to Mediterranean biodiversity, using the Special Protection Area of Mediterranean Importance (SPAMI) "Pelagos Sanctuary" as a case study. In this paper, a new survey method and data analysis strategies to assess the impact of marine litter, including microplastics, on Mediterranean organisms, is proposed. A total of 23 species, from invertebrates to cetaceans, were analysed using two main monitoring approaches. In the first approach, the core density distribution areas of 11 megafauna species (elasmobranchs, sea turtles, seabirds, and cetaceans) and 4 invertebrate species were evaluated through an extended field survey. Simultaneously, monitoring of floating macro- and micro-litter was performed to be overlapped with the species distribution and abundance. The second monitoring approach assessed the ingestion of marine litter, microplastics and the levels of plastic additives in 10 stranded megafauna species and in 7 invertebrate and fish species. The final data processing, merging the data on biodiversity and marine litter abundance and distribution in the environment, with the data of ingested marine litter, microplastics, and plastic additives in sentinel species, allowed to: a) create risk maps for the species inhabiting the Pelagos Sanctuary, identifying critical areas for biodiversity conservation; b) identify the most exposed species to the risk of marine litter by an "exposure score"; c) to select sentinel species for pelagic environment.

Marine litter, particularly microplastics, is a growing threat to the Mediterranean Sea, impacting biodiversity and ecosystem health. However, most studies conducted in the Mediterranean Sea have focused on monitoring of only specific environmental compartments, and rarely have highlighted the overall impacts affecting an area. Therefore, using a new multi-compartment monitoring approach and a standardized methodology, this study investigates the abundance, distribution, composition and impact of marine litter on beaches, surface waters, fish and mussels in a coastal area of Tuscany (Italy). Concerning beach macro litter values, significant differences were found among the three beaches analysed, with the highest amount in the Feniglia beach (mean value = 1245 items/100 m). The top items found are cotton bud sticks (32.3 %), which in the winter survey at Feniglia beach, reached a remarkable density of 1983 items/100 m. Microlitter (1-5 mm), was detected in the beach sediments with a mean abundance of 130 items/m2. Regarding floating macrolitter, the transect with the highest values was the Feniglia site at 3 nautical miles in autumn (1083 items/km2) while for floating microlitter the highest concentration (832,683 MPs/km2) was found in front of Scarlino. Of the 234 fish analysed from 5 different species, 67 contained microplastics in the gastrointestinal tract (28 %) with a mean value of 0.4 items per individual. The species with the highest occurrence was the European anchovy (Engraulis encrasicolus) (53 %) followed by the bogue (Boops boops) (40 %). Through the application of the Marine Litter Impact Index (MLII), considering all the compartments analysed, the Feniglia area emerges as the ecosystem most impacted by marine litter (mean MLII = 3.5, high). This study highlights how a multi-compartment monitoring approach is crucial for understanding the complex interactions between land, sea, and biota.

Polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), novel brominated flame retardants (NBFRs), phthalate esters (PAEs) are pervasive environmental pollutants, posing threats to both ecosystems and human health. Although several analytical methods were developed for these compounds, they are not performed simultaneously. This study addresses the need for a sustainable, novel, analytical approach capable of simultaneously determining these diverse chemical classes in edible fish muscles. Employing ultrasound extraction coupled with dispersive solid-phase extraction (d-SPE) as a cleanup procedure, the method was compared to conventional techniques, revealing significant improvements. Analytical parameters were thoroughly assessed, and the innovative method demonstrated notable advantages, reducing extraction and purification times by approximately 74-80 % and solvent consumption by around 94-97 %. Applied to Mediterranean Sea fish samples, the results underscore the method's potential as a viable, sustainable alternative to traditional approaches, promising enhanced efficiency and reduced environmental impact.

Plastic is ubiquitous within the global marine environment, essentially becoming part of the environment and the ecology of these ecosystems. In Mediterranean ecosystems seagrass meadows of Posidonia oceanica provide key ecosystem services like preventing coastal erosion slowing down the water flow velocity and acting as sediment traps. Recent studies have reported how as for sediments particles, seagrass meadows could be also retaining plastic items in their internal structures. In this study, a total of 93 Posidonia oceanica egagropiles were collected floating at sea in two coastal areas of the Balearic Islands during the summer season of 2017. Once at laboratory the perimeter of each egagropiles was measured and plastics inside them were visually sorted under the stereomicroscope to identify whether marine plastic was becoming part of their internal structure. Results indicate that 30 % of the egagropiles from the eastern coast of Mallorca (Cala Ratjada) contained plastics, while only 13 % of the egagropiles from the northern coast (Can Picafort) had plastics inside them. In addition, identified plastics have been validated with ATR-FTIR spectroscopy indicating that marine plastics with different polymeric composition, mainly polyethylene terephthalate, polyethylene and polypropylene are becoming part of these organic structures. Results from this study are important since it could be indicating transference of plastics along different marine coastal habitats.

Elasmobranchs are priority species for conservation due to their rapid decline determined by the unbalanced struggle between a fragile bio-ecology and strong anthropogenic impacts, such as bycatch from professional fishing. In this context, measuring species resistance to catch of poorly selective gear is of paramount importance. During June–October 2022, five experimental fishing campaigns were carried out in the Asinara Gulf (northern Sardinia) through 35 geographically and bathymetrically representative hauls of an area between 30 and 600 m in depth. Skates prevailed over sharks in the number of species, with seven and five species, respectively. We first evaluated the status of each individual with respect to stress due to the trawl’s catch using a three-graded scale. We also recorded individual biometrics (total and disk length, weight and sex, and maturity for males) on board by implementing the best practices in manipulating individuals for physiological recovery and release at sea. After capture, skates resulted in generally better conditions than sharks, although deepwater species of both groups exhibited a worse state than coastal species. The estimated vitality rates also depended on the size of the individuals. This work provides standardized data on the intermingled effect of size, species type, and inhabited depth on the resistance response of some elasmobranch species against capture by trawl fishery activities.

Most studies examining the occurrence of plastics and microplastics in marine organisms have identified anthropogenic fibres, of natural and synthetic origin, as the most commonly occurring category. Anthropogenic fibres may have been chemically treated with additives making them more persistent and a potential threat to marine organisms. However, fibres have often been excluded from analytical data for the difficulties related to the sampling and analytical procedures, including potential overestimation of the results due to airborne contamination. This review aimed to collect and analyse all studies focusing on the interaction between anthropogenic fibres and marine organisms worldwide, highlighting critical issues that need to be overcome for the analysis fibres on marine organisms. Furthermore, emphasis was placed on the species studied in the Mediterranean Sea, which is particularly affected by this type of pollution. Overall, this review shows that fibre pollution is an underestimated threat to marine organisms and that a specific, harmonised protocol for the analysis of different anthropogenic fibres needs to be developed.

An intercalibration exercise on the characterisation of microplastics in marine sediment and water samples was carried out among five laboratories involved in the implementation of the Marine Strategy Framework Directive (MSFD) in their country. The samples were prepared by mixing cleaned natural sediment and sea water with microplastics sets made of particles of various polymers, shapes and colours. Overall, the errors on total counts were under 25% in absolute value. The risk of non-detection and loss of particles is greater than the risk of contamination during sample analysis. Significant differences are observed among particle types. It appears difficult to obtain reliable and comparable data on the colour of microplastics. A comparison of the errors with regards to the protocols used led to recommend NaCl [1.2 g/cm3] density separation for sediment and one filtering step (200 μm). The operators' experience appears as a key factor for the quality of the results.

Hydrogen represents a possible alternative energy carrier to face the growing request for energy and the shortage of fossil fuels. Photofermentation for the production of H2 constitutes a promising way for integrating the production of energy with waste treatments. Many wastes are characterized by high salinity, and polluted seawater can as well be considered as a substrate. Moreover, the application of seawater for bacterial culturing is considered cost-effective. The aims of this study were to assess the capability of the metabolically versatile freshwater Rhodopseudomonas palustris 42OL of producing hydrogen on salt-containing substrates and to investigate its salt stress response strategy, never described before. R. palustris 42OL was able to produce hydrogen in media containing up to 3 % added salt concentration and to grow in media containing up to 4.5 % salinity without the addition of exogenous osmoprotectants. While the hydrogen production performances in absence of sea salts were higher than in their presence, there was no significant difference in performances between 1 and 2 % of added sea salts. Nitrogenase expression levels indicated that the enzyme was not directly inhibited during salt stress, but a regulation of its expression may have occurred in response to salt concentration increase. During cell growth and hydrogen production in the presence of salts, trehalose was accumulated as a compatible solute; it protected the enzymatic functionality against salt stress, thus allowing hydrogen production. The possibility of producing hydrogen on salt-containing substrates widens the range of wastes that can be efficiently used in production processes.