Microbial communities inhabiting shallow hydrothermal vents as sentinels of acidification processes.

Introduction: Shallow hydrothermal vents are considered natural laboratories to study the effects of acidification on biota, due to the consistent CO2 emissions with a consequent decrease in the local pH. Methods: Here the microbial communities of water and sediment samples from Levante Bay (Vulcano Island) with different pH and redox conditions were explored by Next Generation Sequencing techniques. The taxonomic structure was elucidated and compared with previous studies from the same area in the last decades. Results and discussion: The results revealed substantial shifts in the taxonomic structure of both bacterial and archaeal communities, with special relevance in the sediment samples, where the effects of external parameters probably act for a long time. The study demonstrates that microbial communities could be used as indicators of acidification processes, by shaping the entire biogeochemical balance of the ecosystem in response to stress factors. The study contributes to understanding how much these communities can tell us about future changes in marine ecosystems.

Volcanic-associated ecosystems of the Mediterranean Sea: a systematic map and an interactive tool to support their conservation.

Background: Hydrothermal vents, cold seeps, pockmarks and seamounts are widely distributed on the ocean floor. Over the last fifty years, the knowledge about these volcanic-associated marine ecosystems has notably increased, yet available information is still limited, scattered, and unsuitable to support decision-making processes for the conservation and management of the marine environment. Methods: Here we searched the Scopus database and the platform Web of Science to collect the scientific information available for these ecosystems in the Mediterranean Sea. The collected literature and the bio-geographic and population variables extracted are provided into a systematic map as an online tool that includes an updated database searchable through a user-friendly R-shiny app. Results: The 433 literature items with almost one thousand observations provided evidence of more than 100 different volcanic-associated marine ecosystem sites, mostly distributed in the shallow waters of the Mediterranean Sea. Less than 30% of these sites are currently included in protected or regulated areas. The updated database available in the R-shiny app is a tool that could guide the implementation of more effective protection measures for volcanic-associated marine ecosystems in the Mediterranean Sea within existing management instruments under the EU Habitats Directive. Moreover, the information provided in this study could aid policymakers in defining the priorities for the future protection measures needed to achieve the targets of the UN Agenda 2030.

How Rare Are Argonautoidea Octopuses in the Mediterranean? New Data from Stranding Events, Stomach Contents and Genetics.

The present paper represents the first all-encompassing study on all Mediterranean holopelagic octopods belonging to Argonautoidea (Argonauta argo, Ocythoe tuberculata, Tremoctopus gracilis, Tremoctopus violaceus). Argonautoidea octopuses were collected by different sampling methods in the Strait of Messina and southern Tyrrhenian Sea. The aim of this paper was to improve knowledge, using information from different data sources, such as the study of stranded individuals or accidental caught specimens, as well as the analysis of stomach content of large pelagic fishes. Moreover, we investigated their taxonomic profile through the amplification of the mitochondrial cytochrome c oxidase subunit I (COI). Overall, 47 fresh holopelagic octopods were collected, including valuable records of rare males. Moreover, 330 Argonautoidea octopuses were found in the stomachs of 800 predators. The results provided evidence that these cephalopods are more abundant than thought in the past. The molecular approach supported the ecological results with interesting insights. The similarity-based identifications and tree-based methods indicated that three females could be identified as Tremoctopus violaceus in agreement with their morphological classifications. The sequences obtained from the two T. gracilis individuals were clustered with the sequences of Tremoctopus violaceus from the Gulf of Mexico and were differentiated from the sequences attributed to T. gracilis and T. robsoni. The study represents a valuable contribution to the genetic characterization of Mediterranean individuals of the genera Tremoctopus, Argonauta and Ocythoe.

Integrated approach for marine litter pollution assessment in the southern Tyrrhenian Sea: Information from bottom-trawl fishing and plastic ingestion in deep-sea fish.

Marine litter pollution threatens marine ecosystems and biodiversity conservation, particularly on seafloors where all anthropogenic waste naturally sinks. In this study, we provide new information on the composition, density and origin of seafloor macrolitter as well as on plastic ingestion in deep-sea fish from bottom-trawling by-catch in the southern Tyrrhenian Sea. Plastic constituted the highest fraction of litter in terms of density (64 %) and weight (32 %) and was also retrieved in the gastrointestinal traits of Chlorophthalmus agassizi, Coelorhynchus coelorhynchus and Hoplosthethus mediterraneus. FT-IR spectroscopy analysis on the seafloor macrolitter and the ingested plastics revealed the presence of artificial polymers including PE, PET/polyester, PA widely used for food packaging, plastic bags and several common products, especially Single Use Plastic (SUP). These results underline how poor waste management schemes or their incorrect application strongly contribute to marine litter accumulation on seafloors and plastic ingestion in deep-sea fish.

Importance of the Lunar Cycle on Mesopelagic Foraging by Atlantic Bluefin Tuna in the Upwelling Area of the Strait of Messina (Central Mediterranean Sea).

The influence of the lunar cycle on bluefin tuna foraging in the upwelling area of the Strait of Messina was investigated by exploring trophic interaction with mesopelagic fish and cephalopod prey. To focus on how the lunar cycle could affect availability of mesopelagic prey for this predator, we tested potential differences in the diet related to each lunar phase. Moreover, we considered two potential impacts of the lunar cycle: the lunar irradiance and the strength of currents. Overall, 2672 prey items were mesopelagic fish and cephalopods, representing 60.7% of overall diet by number. The main mesopelagic fish prey items were lanternfishes and dragonfishes, while Onychoteuthis banksii was the most important cephalopod prey. In summary, the Strait of Messina has highly specific hydrodynamic and biological features which strongly depend on upwelling currents, which in turn are influenced by the lunar cycle (new and full moon with strong currents, quarters with fewer currents). Upwelling causes water mixing, bringing to the surface a large amount of mesopelagic fauna which become more readily available to tuna. Lunar irradiance contributes to the variation of prey composition, increasing the success of visual predation on mesopelagic resources at high light in the water column.

Integrated biomarker responses in European seabass Dicentrarchus labrax (Linnaeus, 1758) chronically exposed to PVC microplastics.

Few studies evaluated long-term effects of polyvinyl chloride (PVC) microplastics (MPs) ingestion in fish. The present study aimed to investigate the integrated biomarker responses in the liver and blood of 162 European seabass, Dicentrarchus labrax, exposed for 90 days to control, virgin and marine incubated PVC enriched diets (0.1 % w/w) under controlled laboratory condition. Enzymatic and tissue alterations, oxidative stress, gene expression alterations and genotoxicity were examined. Additives and environmental contaminants levels in PVC-MPs, control feed matrices and in seabass muscles were also detected. The results showed that the chronic exposure at environmentally realistic PVC-MPs concentrations in seabass, cause early warning signs of toxicological harm in liver by induction of oxidative stress, the histopathological alterations and also by the modulation of the Peroxisome proliferator-activated receptors (PPARs) and Estrogen receptor alpha (ER-α) genes expression. A trend of increase of DNA alterations and the observation of some neoformations attributable to lipomas suggest also genotoxic and cancerogenic effects of PVC. This investigation provides important data to understand the regulatory biological processes affected by PVC-MPs ingestion in marine organisms and may also support the interpretation of results provided by studies on wild species.

Benthic litter in the continental slope of the Gulf of Naples (central-western Mediterranean Sea) hosts limited fouling communities but facilitates molluscan spawning.

Seafloor pollution by benthic litter is an emerging phenomenon, although debris colonization by biota remains largely unexplored. We characterized the litter of the continental slope (~400-600 m) of the Gulf of Naples (Mediterranean) and investigated its fouling biota through integrative taxonomic approaches. Plastic pieces (82 %) with land-based origin (96 %) and limited sizes (10-20 cm) were the items most commonly encountered, suggesting a transfer to deep waters through floating and sinking. The majority of the items were not fouled, and the debris hosted an impoverished biota, leading to hypothesize that benthic litter supports wide communities only in shallow waters. Higher colonization rates were observed for gastropod and cephalopod eggs with no preference for materials and sizes, suggesting that even small pieces of soft plastic provide a spawning habitat for molluscs and affect species' connectivity in the deep-sea ecosystem. Holistic approaches are necessary to evaluate interactions between litter and biota.

Influence of offshore oil and gas structures on seascape ecological connectivity.

Offshore platforms, subsea pipelines, wells and related fixed structures supporting the oil and gas (O&G) industry are prevalent in oceans across the globe, with many approaching the end of their operational life and requiring decommissioning. Although structures can possess high ecological diversity and productivity, information on how they interact with broader ecological processes remains unclear. Here, we review the current state of knowledge on the role of O&G infrastructure in maintaining, altering or enhancing ecological connectivity with natural marine habitats. There is a paucity of studies on the subject with only 33 papers specifically targeting connectivity and O&G structures, although other studies provide important related information. Evidence for O&G structures facilitating vertical and horizontal seascape connectivity exists for larvae and mobile adult invertebrates, fish and megafauna; including threatened and commercially important species. The degree to which these structures represent a beneficial or detrimental net impact remains unclear, is complex and ultimately needs more research to determine the extent to which natural connectivity networks are conserved, enhanced or disrupted. We discuss the potential impacts of different decommissioning approaches on seascape connectivity and identify, through expert elicitation, critical knowledge gaps that, if addressed, may further inform decision making for the life cycle of O&G infrastructure, with relevance for other industries (e.g. renewables). The most highly ranked critical knowledge gap was a need to understand how O&G structures modify and influence the movement patterns of mobile species and dispersal stages of sessile marine species. Understanding how different decommissioning options affect species survival and movement was also highly ranked, as was understanding the extent to which O&G structures contribute to extending species distributions by providing rest stops, foraging habitat, and stepping stones. These questions could be addressed with further dedicated studies of animal movement in relation to structures using telemetry, molecular techniques and movement models. Our review and these priority questions provide a roadmap for advancing research needed to support evidence-based decision making for decommissioning O&G infrastructure.

Microplastics in the bogue, Boops boops: A snapshot of the past from the southern Tyrrhenian Sea.

The present investigation focuses on Boops boops specimens gathered in the Gulf of Patti in 2010. Providing a snapshot from the past, this paper represents, chronologically, the first record of microplastic ingestion in the Mediterranean bogue. The plastic abundance and composition in gastrointestinal tracts of the bogue was assess, in order to improve the knowledge on spatial-temporal variability of microplastics pollution in the Mediterranean basin and in particular, in the southern Tyrrhenian Sea. In a total of 65 specimens, 180 particles of plastic (2.8 items/specimens), mainly belonging to microplastics class, were found. Fragments (63%) and fibres (30%) were the predominant shape categories. Eleven polymers were identified: polypropylene and polyethylene were the most abundant. Several synthetic polymers belonging to the class of elastomers were also observed. The study area is strongly influenced by the absence of trawl fishing activities and a low mixing level of the seabed that, together with the confluence of different watercourses and the presence of different kind of anthropic impact, including motorway, could make it a 'waste disposal site'. Finally, our results suggest the usefulness to retrieve older samples to better understand spatial-temporal changes in marine litter pollution over time.

The waste collector: information from a pilot study on the interaction between the common octopus (Octopus vulgaris, Cuvier, 1797) and marine litter in bottom traps fishing and first evidence of plastic ingestion.

Few studies focused on behaviour adaptations of organisms to marine litter (ML) pollution in Mediterranean Sea. This research, investigates on some behavior traits of Octopus vulgaris, focusing on the interaction with ML during the artisanal fishing activities by the bottom traps in a small coastal area of the southern Tyrrhenian Sea. For the first time, this pilot study uses an integrated approach based on the Fishermen Ecological Knowledge as well as the analysis of ML found in the traps. First assessment of plastic ingestion in this species are also reported. Plastic and metal were the predominant ML categories observed into the bottom traps. A total of 62 plastics, mainly small microplastics and fibres shaped, were ingested. The ML finding in the bottom traps suggests an interesting behavior of the common octopus regarding its interaction with ML, in fact, it seems to bring ML inside its dens, as a collector.

Marine litter pollution associated with hydrothermal sites in the Aeolian archipelago (western Mediterranean Sea).

The Aeolian Archipelago, in the western Mediterranean Sea, is an active volcanic arc hosting several hydrothermal sites. This area, considered a Vulnerable Marine Ecosystem by The Food and Agriculture Organization because of its ecological importance and biodiversity value, is affected by various pressures and threats that may act as sources of marine litter. The aim of this paper was to analyse the composition and distribution of marine litter on the seafloor of this archipelago with a specific focus on the hydrothermal areas, using almost 60 h of remotely operated vehicle footage collected at depths of 15 to 411 m. Derelict fishing gear represented the main source of marine debris (71.9% of the overall litter); nevertheless, the observed mean litter density was quite low (0.57 items/100 m2) when compared with other Mediterranean areas, probably because fisheries in the area mainly use pelagic gear that has a low impact on the seabed. No differences were found in litter densities between hydrothermal and non-hydrothermal zones. The occurrence of benthic fauna impacted by debris was rarely recorded (only 10.6% of litter items showed interactions with species) and entanglement was the most commonly observed impact. However, both the density of synthetic fishing gear and its impact on habitats and species are bound to increase over time. Overall, plastics constituted most of the marine litter (79.7%). So, prevention and mitigation measures are needed in order to protect this sensitive ecosystem. To this end, the most effective strategy could be the establishment of a Marine Protected Area or a Site of Community Importance, due to the presence of habitats ("submarine structures made by leaking gases" and "reefs") listed in Annex I of the European Habitats Directive, where all fishing activities could be strictly regulated.

Seafloor litter along the Italian coastal zone: An integrated approach to identify sources of marine litter.

A heterogeneous amount of waste of different origins is continuously generated along Italian coasts in the Mediterranean Sea. In this paper, using information regarding the quantities and the different types of marine litter based on Project AWARE's "Dive Against Debris" data, we try to identify the main sources of this waste. In particular, the methodological approach used associates the origin of marine litter sources with the dataset of geo-localised state-owned maritime concessions, which are loaded by the granting bodies (regions, municipalities, port authorities) on the State Property Information System (Sid). The sources of marine litter were evaluated using the matrix scoring technique (MST). Then, to assess the weight of each source in each station, the community-level weighted mean (CWM) was calculated. Single-use plastic accounted for the highest percentage (19.13%), followed by glass beverage bottles (10.90%), shopping bags (9.03%), aluminium beverage cans (4.91%), and cigarette butts (4.61%). Tourism and beach users contributed to 42.3% of the litter found, followed by fishing (15.7%) and yachting (11.3%). The overlapping of the data collected by scuba divers with the state concessions of activities from offshore and mainland areas was used to distinguish the anthropic pressures that impact the coast. Policy makers and the local administrator may use these results to define new methods of collection and reuse of anthropic waste through a more harmonised approach in the management of marine waste.

The impact of marine litter from fish aggregation devices on vulnerable marine benthic habitats of the central Mediterranean Sea.

The aim of this research was to assess marine litter abundance and its effects on the benthic fauna in an area of the central Mediterranean Sea exploited by fisheries using fish aggregating devices (FAD). The study was carried out by means of a remotely-operated vehicle (ROV). Derelict fishing gear, mainly FAD ropes, represented the main source of marine debris, contributing 96.2% to the overall litter. About 47% of debris items (mostly FAD ropes) entangled colonies of the protected black coral Leiopathes glaberrima. The results of this research will assist in the monitoring of "impact/harm" to the coral and other benthic communities, as recommended by the Marine Strategy Framework Directive and by the Integrated Monitoring and Assessment Programme. Preventive and mitigation measures (i.e., biodegradable fishing gear, onboard technology to locate and retrieve gear, reception and/or payment for old/retrieved gear, and introduction of no-take zones) to reduce the problem are discussed.

A new digestion approach for the extraction of microplastics from gastrointestinal tracts (GITs) of the common dolphinfish (Coryphaena hippurus) from the western Mediterranean Sea.

Plastic ingestion is one of the main impacts of marine litter on organisms. The occurrence of microplastics (MPs < 5 mm) in the stomachs of Mediterranean species was already reported in several studies. In this context, the present study aims to develop a new approach of digestion for the identification of MPs in the gastrointestinal tracts (GITs) of marine organisms. The new approach combines two digestion protocols, including potassium hydroxide (KOH) and nitric acid (HNO3), to remove most organic and inorganic materials. This digestion allows recording small MPs that are difficult to find via routinely stomach content analysis and also to minimize the overestimation of the phenomenon trough the control of airborne contamination. The new approach was tested on a voracious pelagic opportunistic predator, the common dolphinfish, a fishery resource exploited in several Mediterranean areas. The results showed that a large amount of ingested meso- and microplastics, such as fragments or sheets, was recorded in GITs (F = 65.5 %). The FTIR analysis on litter samples allowed to identify polyethylene, polypropylene and polystyrene as dominant constituent polymers of microplastics. These results confirmed that our novel combined digestion protocol represents a reliable approach to detect MPs in opportunistic pelagic predators.

Common patterns of functional and biotic indices in response to multiple stressors in marine harbours ecosystems.

Evaluating the effects of anthropogenic pressure on the marine environment is one of the focal objectives in identifying strategies for its use, conservation and restoration. In this paper, we assessed the effects of chemical pollutants, grain size and plastic litter on functional traits, biodiversity and biotic indices. The study was conducted on the benthic communities of three harbours in the central Mediterranean Sea: Malta, Augusta and Syracuse, subjected to different levels of anthropogenic stress (high, medium and low, respectively). Six traits were considered, subdivided into 22 categories: reproductive frequency, environmental position, mobility, life habit, feeding habit and bioturbation. Functional diversity indices analysed were: Functional Divergence, Quadratic Entropy, Functional Evenness and Functional Richness. To assess the trait responses to environmental gradients, we applied RLQ analysis, which considers simultaneously the relationship between three components: environmental data (R), species abundances (L) and species traits (Q). From our analyses, significant relationships (P-value = 0.0018 for permutation of samples, and P-value = 0.00027 for permutation of species) between functional traits and environmental data were highlighted. The trait categories significantly influenced by environmental variables were those representing feeding habits and mobility. In particular, the first category was influenced by chemical pollutants (organotin compounds and polycyclic aromatic hydrocarbons) and grain size (silt and sand), while the latter category was influenced only by chemical pollutants. Pearson correlations performed for functional vs biotic and diversity indices confirmed the validity of the chosen conceptual framework for harbour environments. Finally, linear models assessing the influence of stressors on functional parameters underlined the link between environmental data vs benthic and functional indices. Our results highlight the fact that functional trait analysis provides a useful and fast method for detecting in greater depth the effects of multiple stressors on functional diversity in marine ecosystems.

Characterization of seafloor litter on Mediterranean shallow coastal waters: Evidence from Dive Against Debris®, a citizen science monitoring approach.

Citizen science programs carried out by volunteers are fundamental for the collection of scientific data on a wide spatial scale. From 2011 to 2018, 468 survey dives were conducted in 172 coastal locations of the Mediterranean Sea through Project AWARE's citizen science program, Dive Against Debris®. During the dives, information was collected on quantity, typology and distribution of seafloor litter in shallow coastal waters. Overall, the observed average density was 43.55 items/100 m2 and plastic was largely the dominant material (55% of the total collected items) on basin scale. The most abundant seafloor litter items were plastic fragments with 9.46%, followed by beverage cans (7.45%). Single-use plastic items constituted 33% of the total marine litter. The results of the study can be used to inform policymakers of the European Community towards specific management action to contrast the marine litter in relation to the distribution of the recorded litter category.

Are FADs a significant source of marine litter? Assessment of released debris and mitigation strategy in the Mediterranean sea.

A poorly known form of marine litter known as Abandoned, Lost or otherwise Discarded Fishing (ALDFG) derives from fishing activities using FADs (Fish Aggregating Devices). In the Mediterranean Sea, this activity is widespread in southern Italy, Tunisia, Malta and Majorca (Spain). The way of constructing FADs, from a functional point of view, is very similar throughout the Mediterranean and consists mainly of the use of different materials for the floats and for the cables and blocks for anchoring. Every year, for at least 30 years, about 60,000 FADs have been placed at sea and in most cases are not recovered. In this study, through analysis of the scientific and grey literature, a historical reconstruction of the use of FADs in the Mediterranean Sea was made, including their spatial distribution, the number of objects and the materials used to build the devices. It has been estimated that approximately 1.6 million FADs were abandoned in the Mediterranean Sea between 1961 and 2017. The largest fishing areas are off Malta (34,465 km2) and Tunisia (23,033 km2). The greatest numbers of abandoned plastic sheets (452,742) and concrete blocks (905,483) were estimated to be around Tunisia, while the greatest amount, in terms of length, of polyethylene cable (399,423 km) was estimated to be around Sicily. About 30% of FADs used all over the world are used in the Mediterranean and are only of the anchored type (corresponding to about 90% of those anchored used worldwide). The legislation on the use of Mediterranean FADs is still poor and does not address environmental issues. An analysis of the possible environmental impacts of the FAD litter was made. Overall, reducing the number of FADs and introducing new types of FADs equipped with specific technological systems appear to be the most suitable strategies to mitigate the impact of FADs on the environment and resources, as well as measures and incentives to involve fishermen in their better management.

The last stage in the life history of the European conger eel Conger conger: a transformation before death.

The taxonomic, morphological and meristic features of a dark eel caught by commercial trawling off the Gulf of Patti, southern Tyrrhenian Sea, Mediterranean Sea, February 17, 2017, showed it to be a female Conger conger. Histological analysis of gonads demonstrated that the individual was in a post-spawning phase. X-ray radiographs showed widespread decalcification of skeleton and teeth loss, confirming a strong mobilisation of somatic energy reserves needed for reproductive development.

Colonization of floats from submerged derelict fishing gears by four protected species of deep-sea corals and barnacles in the Strait of Messina (central Mediterranean Sea).

The distribution of floating litter in marine waters, influenced by currents and wind drag, often determines the dispersal of its encrusting fauna. In the present paper, we observed for the first time the colonization of rafting floats from abandoned, lost or derelict fishing gears (ALDFG) by the four protected deep-sea species: Errina aspera, Desmophyllum pertusum, Madrepora oculata Pachylasma giganteum. Overall, 41 floats, colonized by deep benthic species, were found stranded on the shore of the Sicilian coast of the Strait of Messina, between 2016 and 2019. Species composition, number and occurrence of colonizing organisms were analyzed. On the basis of the species composition (the association between E. aspera, P. giganteum and Megabalanus tulipiformis), the knowledge on their ecology, biogeography, path of local currents, it was possible to define that the area of origin of the most part of these fishing net floats was the Strait of Messina.

Marine litter from fishery activities in the Western Mediterranean sea: The impact of entanglement on marine animal forests.

The anthropogenic marine debris, especially abandoned, lost or otherwise discarded Fishing Gear (ALDFG), represents a rising concern, because of its potential harmful impact on the marine animal forests. We carried out 13 km of video recordings, by means of a remotely operated vehicle, from 10 to 210 m depth, in an anthropised area of the Tyrrhenian Sea (Mediterranean Sea). This site, for its high ecological importance and biodiversity value, has been identified for the establishment of a new marine protected area (MPA). The aim of this paper was to assess marine litter abundance and its effects on the benthic fauna. The debris density, in the study area, ranged from 0.24 to 8.01 items/100 m2, with an average of 3.49 (±0.59) items/100 m2. The derelict fishing gear, mainly fishing lines, were the main source of marine debris, contributing 77.9% to the overall litter. The impacts of debris on the benthic fauna were frequently recorded, with 28.5% of the litter entangling corals and impacting habitats of conservation concern. These impacts were exclusively caused by the derelict fishing gear (91.2% by longlines), and the highest percentage (49.1%) of ALDFG causing impacts was observed from 41 to 80 m depth, in the coralligenous biocenosis. The results of the present study will help the fulfilment of "harm" monitoring, as recommended by the Marine Strategy Framework Directive (MSFD) and the UN Environment/MAP Regional Plan on the marine litter management in the Mediterranean Sea. Regarding the actions to reduce the derelict fishing gear, preventive measures are usually preferred instead of the extensive removals based on cost-effectiveness and sustainability. The establishment of a new MPA in the area could be a good solution to reduce ALDFG, resulting in the improvement of the ecological status of this coastal area.