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The Antarctic continental shelf is known as a critical anthropogenic CO2 (Cant) sink due to its cold waters, high primary productivity, and unique circulation, which allow it to sequester large amounts of organic and inorganic carbon into the deep ocean. However, climate change is currently causing significant alteration to the Antarctic marine carbon cycle, with unknown consequences on the Cant uptake capacity, making model-based estimates of future ocean acidification of polar regions highly uncertain. Here, we investigated the marine carbonate system in the Ross Sea in order to assess the current anthropogenic carbon content and how physical–biological processes can control the Cant sequestration along the shelf-slope continuum. The Winter Water mass generated from convective events was characterized by high Cant level (28 µmol kg−1) as a consequence of the mixed layer break-up during the cold season, whereas old and less-ventilated Circumpolar Deep Water entering the Ross Sea revealed a very scarce contribution of anthropogenic carbon (7 µmol kg−1). The Cant concentration was also different between polynya areas and the shelf break, as a result of their specific hydrographic characteristics and biological processes: surface waters of the Ross Sea and Terra Nova Bay polynyas served as strong CO2 sink (up to −185 mmol m−2), due to the remarkable net community production, estimated from the summertime surface-dissolved inorganic carbon deficit. However, a large amount of the generated particulate organic carbon was promptly consumed by intense microbial activity, giving back carbon dioxide into the intermediate and deep layers of the continental shelf zone. Further Cant also derived from High-Salinity Shelf Water produced during winter sea ice formation (25 µmol kg−1), fueling dense shelf waters with additional input of Cant, which was finally stored into the abyssal sink through continental slope outflow (19 µmol kg−1). Our results suggest that summer biological activity over the Ross Sea shelf is pivotal for the shunt of anthropogenic CO2 between the organic and inorganic carbon pools, enhancing the ocean acidification of the upper mesopelagic zone and the long-term Cant sequestration into the deep ocean.

This study deals with the issue of beach litter pollution in the context of the Descriptor 10 of the Marine Strategy Framework Directive Good Environmental Status of EU waters and Ecological objective 10, Common indicator 22 of IMAP. Analyses of the amount, distribution and categorization of beach litter were conducted on nine beaches during 108 surveys covering the area of 206.620 m2 in Albania, Italy and Montenegro. Our findings showed that the level of beach litter pollution on south Adriatic beaches is significantly above the adopted threshold values, with a median item numbers of 327, 258 and 234 per 100 m of beach stretch for Albania, Italy and Montenegro, respectively. It can be concluded that, when it comes to beach litter pollution, GES has not been achieved. Given the defined baseline and threshold values at the EU level, the process of reducing the total amount of marine litter in southern Adriatic Sea will be very challenging and needs urgent and specific actions.

Description, Subpolar Atlantic dynamics drive Arctic climate at the onset of the 20th century., The recent expansion of Atlantic waters into the Arctic Ocean represents undisputable evidence of the rapid changes occurring in this region. Understanding the past variability of this “Atlantification” is thus crucial in providing a longer perspective on the modern Arctic changes. Here, we reconstruct the history of Atlantification along the eastern Fram Strait during the past 800 years using precisely dated paleoceanographic records based on organic biomarkers and benthic foraminiferal data. Our results show rapid changes in water mass properties that commenced in the early 20th century—several decades before the documented Atlantification by instrumental records. Comparison with regional records suggests a poleward expansion of subtropical waters since the end of the Little Ice Age in response to a rapid hydrographic reorganization in the North Atlantic. Understanding of this mechanism will require further investigations using climate model simulations.

Coastal ecosystems are subject to multiple processes that drive pH change over time. Therefore, efforts to understand the variability in the coastal carbonate system are crucial to assess the marine system vulnerability to acidification. The variations of the carbon dioxide (CO2) system were studied, from December 2014 to January 2017, on 6 stations along a transect latitudinally crossing the northern Adriatic, from the Po River delta to the Istrian Peninsula. The study aims to evaluate the influence of riverine inputs and other environmental drivers, such as temperature, air-sea CO2 exchanges and biological processes, on the carbonate system. Riverine discharges significantly affected the carbonate system, as they are an input of total alkalinity and nutrients. High alkalinity concentrations were measured in low salinity waters and a significant negative correlation between salinity and alkalinity was found. The influence of biological processes was underscored by the significant inverse correlation between pHT at a constant temperature (pHT25^°C) and apparent oxygen utilization, and by the positive correlation between chlorophyll a and pHT25^°C in samplings close to flood events. Moreover, thermic and non-thermic partial pressure (p) of CO2 in surface waters was evaluated. pCO2 was more strongly influenced by the thermal effect during summer, while the biological effect prevailed in the other seasons. The analysis of air-sea CO2 fluxes highlighted that the area acts as a sink of CO2 during winter, spring and autumn and as a source during summer. A biogeochemical simulation was used for bottom and surface waters to estimate future changes in northern Adriatic carbonate chemistry with the increase of anthropogenic CO2 and temperature, and to understand how biological processes could affect the expected trends. By 2100, under the IPCC scenario of business as usual and without the effect of biological processes, pHT is expected to decrease by ∼0.3 and the aragonite saturation is expected to decline by ∼1.3, yet not reach undersaturation values. Even though the northern Adriatic is characterized by high alkalinity buffering, pH seasonal variability will likely be more pronounced, due to the strong decoupling of production and respiration processes driven by stratification of the water column.

There is growing evidence that the on-going ocean acidification of the Mediterranean Sea could be favoured by its active overturning circulation. The areas of dense water formation are, indeed, preferential sites for atmospheric carbon dioxide absorption and through them the ocean acidification process can quickly propagate into the deep layers. In this study we estimated the concentration of anthropogenic CO 2 (C ant ) in the dense water formation areas of the middle and southern Adriatic Sea. Using the composite tracer TrOCA (Tracer combining Oxygen, inorganic Carbon, and total Alkalinity) and carbonate chemistry data collected throughout March 2013, our results revealed that a massive amount of C ant has invaded all the identified water masses. High C ant concentration was detected at the bottom layer of the Pomo Pit (middle Adriatic, 96.8±9.7 µmol kg −1 ) and Southern Adriatic Pit (SAP, 85.2±9.4 µmol kg −1 ), associated respectively with the presence of North Adriatic Dense Water (NAdDW) and Adriatic Dense Water (AdDW). This anthropogenic contamination was clearly linked to the dense water formation events, which govern strong CO 2 flux from the atmosphere to the sea and the sinking of dense, CO 2 -rich surface waters to the deep sea. However, a very high C ant level (94.5±12.5 µmol kg −1 ) was also estimated at the intermediate layer, as a consequence of a recent vertical mixing that determined the physical and biogeochemical modification of the water of Levantine origin (i.e. Modified Levantine Intermediate Water, MLIW) and favoured the atmospheric CO 2 intrusion. The penetration of C ant in the Adriatic Sea determined a significant pH reduction since the pre-industrial era (– 0.139±0.019 pH units on average). This estimation was very similar to the global Mediterranean Sea acidification, but it was again more pronounced at the bottom of the Pomo Pit, within the layer occupied by NAdDW (– 0.157±0.018 pH units), and at the intermediate layer of the recently formed MLIW (– 0.143±0.020 pH units). Our results indicate that the Adriatic Sea could potentially be one of the Mediterranean regions most affected by the ocean acidification and also demonstrate its active role in sequestering and storing C ant .

Marine space is three dimensional, the turnover of life forms is rapid, defining a fourth dimension: time. The definition of ecologically significant spatial units calls for the spatio-temporal framing of significant ecological connections in terms of extra-specific (biogeochemical cycles), intra-specific (life cycles), and inter-specific (food webs) fluxes. The oceanic volume can be split in sub-systems that can be further divided into smaller sub-units where ecosystem processes are highly integrated. The volumes where oceanographic and ecological processes take place are splittable into hot spots of ecosystem functioning, e.g., upwelling currents triggering plankton blooms, whose products are then distributed by horizontal currents, so defining Cells of Ecosystem Functioning (CEFs), whose identification requires the collaboration of physical and chemical oceanography, biogeochemistry, marine geology, plankton, nekton and benthos ecology and biology, food web dynamics, marine biogeography. CEFs are fuzzy objects that reflect the instability of marine systems.

Marine space is three dimensional, the turnover of life forms is rapid, defining a fourth dimension: time. The definition of ecologically significant spatial units calls for the spatio-temporal framing of significant ecological connections in terms of extra-specific (biogeochemical cycles), intra-specific (life cycles), and inter-specific (food webs) fluxes. The oceanic volume can be split in sub-systems that can be further divided into smaller sub-units where ecosystem processes are highly integrated. The volumes where oceanographic and ecological processes take place are splittable into hot spots of ecosystem functioning, e.g., upwelling currents triggering plankton blooms, whose products are then distributed by horizontal currents, so defining Cells of Ecosystem Functioning (CEFs), whose identification requires the collaboration of physical and chemical oceanography, biogeochemistry, marine geology, plankton, nekton and benthos ecology and biology, food web dynamics, marine biogeography. CEFs are fuzzy objects that reflect the instability of marine systems.

Aim Marine bioconstructions such as coralligenous formations are hotspot of biodiversity and play a relevant ecological role in the preservation of biodiversity by providing carbon regulation, protection and nursery areas for several marine species. For this reason, the European Union Habitat Directive included them among priority habitats to be preserved. Although their ecological role is well established, connectivity patterns are still poorly investigated, representing a limit in conservation planning. The present study pioneers a novel approach for the analysis of connectivity in marine bioconstructor species, which often lack suitable genetic markers, by taking advantage of next‐generation sequencing techniques. We assess the geographical patterns of genomic variation of the sunset cup coral Leptopsammia pruvoti Lacaze‐Duthiers, 1897, an ahermatypic, non‐zooxanthellate and solitary scleractinian coral species common in coralligenous habitats and distributed across the Mediterranean Sea. Location The Italian coastline (Western and Central Mediterranean). Methods We applied the restriction site‐associated 2b‐RAD approach to genotype over 1,000 high‐quality and filtered single nucleotide polymorphisms in 10 population samples. Results The results revealed the existence of a strongly supported genetic structure, with highly significant pairwise FST values between all the population samples, including those collected about 5 km apart from each other. Moreover, genomic data indicate that the strongest barriers to gene flow are between the western (Ligurian–Tyrrhenian Sea) and the eastern side (Adriatic Sea) of the Italian peninsula. Main conclusions The strong differentiation found in L. pruvoti is similar to that found in other species of marine bioconstructors investigated in this area, but it strongly contrasts with the small differences found in many fish and invertebrates at the same geographical scale. All in one, our results highlight the importance of assessing connectivity in species belonging to coralligenous habitats as, due to their limited dispersal ability, they might require specific spatial conservation measures.

12 pages, 3 figures, Climate change is already transforming the seascapes of our oceans by changing the energy availability and the metabolic rates of the organisms. Among the ecosystem-engineering species that structure the seascape, marine animal forests (MAFs) are the most widespread. These habitats, mainly composed of suspension feeding organisms, provide structural complexity to the sea floor, analogous to terrestrial forests. Because primary and secondary productivity is responding to different impacts, in particular to the rapid ongoing environmental changes driven by climate change, this paper presents some directions about what could happen to different MAFs depending on these fast changes. Climate change could modify the resistance or resilience of MAFs, potentially making them more sensitive to impacts from anthropic activities (i.e. fisheries and coastal management), and vice versa, direct impacts may amplify climate change constraints in MAFs. Such changes will have knock-on effects on the energy budgets of active and passive suspension feeding organisms, as well as on their phenology, larval nutritional condition, and population viability. How the future seascape will be shaped by the new energy fluxes is a crucial question that has to be urgently addressed to mitigate and adapt to the diverse impacts on natural system, We also thank the Marie Curie International Outgoing Fellowship project ANIMAL FOREST HEALTH (Grant Agreement Number 327845). This work contributes to the ICTA “Unit of Excellence” (MinECo, MDM2015-0552). We are also grateful with the CALMED project (CTM2016-79547-R) and the AGAUR Generalitat de Catalunya (MERS, 2017 SGR 1588). SR and MS thanks the CAPES-Print Programme and CNPq Research Productivity Fellowship (Brazil)

Seawater acidification could alter the susceptibility of marine organisms to emerging contaminants, such as pharmaceuticals. In this study, the combined effects of seawater acidification and the non-steroidal anti-inflammatory drug diclofenac on survival, growth and oxidative stress-related parameters (catalase activity and lipid peroxidation) in the larvae of the Manila clam Ruditapes philippinarum were investigated for the first time. An experimental flow-through system was set up to carry out a 96-h exposure of clam larvae. Two pH levels (pH 8.0, the control, and pH 7.8, the predicted pH by the end of this century) were tested with and without diclofenac (0.5 μg/L). After 4 days, mortality was dramatically higher under reduced pH, particularly in the presence of diclofenac (62% of the larvae dead). Shell morphology was negatively affected by both acidification and diclofenac from the first day of exposure. The percentage of abnormal larvae was always higher at pH 7.8 than in controls, peaking at 98% in the presence of diclofenac after 96 h. Instead, shell length, shell height or the ratio of these values were only negatively influenced by reduced pH throughout the whole experiment. After 96 h, catalase activity was significantly increased in all larvae kept at pH 7.8, whereas no significant difference in lipid peroxidation was found among the treatments. This study demonstrates a high susceptibility of R. philippinarum larvae to a slight reduction in seawater pH. Furthermore, the results obtained highlight that acidification enhances the sensitivity of clam larvae to environmentally relevant concentrations of diclofenac.

In this paper we investigated, for two years and with a bi-monthly frequency, how physical, chemical, and biological processes affect the marine carbonate system in a coastal area characterized by high alkalinity riverine discharge (Gulf of Trieste, northern Adriatic Sea, Mediterranean Sea). By combining synoptic measurements of the carbonate system with in situ determinations of the primary production (14C incorporation technique) and secondary prokaryotic carbon production (3H-leucine incorporation) along a river–sea gradient, we showed that the conservative mixing between river endmember and off-shore waters was the main driver of the dissolved inorganic carbon (DIC) distribution and seasonal variation. However, during spring and summer seasons also the influence of biological uptake and release of DIC was significant. In the surface water of June 2012, the spreading and persistence of nutrient-rich freshwater stimulated the primary production (3.21 μg C L− 1 h− 1) and net biological DIC decrease (− 100 μmol kg− 1), reducing the dissolved CO2 concentration and increasing the pHT. Below the pycnocline of August 2012, instead, an elevated bacterial carbon production rate (0.92 μg C L− 1 h− 1) was related with net DIC increase (92 μmol kg− 1), low dissolved oxygen concentration, and strong pHT reduction, suggesting the predominance of bacterial heterotrophic respiration over primary production. The flux of carbon dioxide estimated at the air–sea interface exerted a low influence on the seasonal variation of the carbonate system. A complex temporal and spatial dynamic of the air–sea CO2 exchange was also detected, due to the combined effects of seawater temperature, river discharge, and water circulation. On annual scale the system was a sink of atmospheric CO2. However, in summer and during elevated riverine discharges, the area close to the river's mouth acted as a source of carbon dioxide. Also the wind speed was crucial in controlling the air–sea CO2 exchange, with strong Bora events (a typical ENE wind of the Gulf of Trieste) that drastically increased the absorption (− 32.2 mmol m− 2 day− 1) or the release (5.34 mmol m− 2 day− 1) of carbon dioxide.

The effects of different physical and biogeochemical drivers on the carbonate system were investigated in a semi-enclosed coastal area characterized by high alkalinity riverine discharge (Gulf of Trieste, Northern Adriatic Sea, Mediterranean Sea). Our 2-year time-series showed that a large part of the seasonal carbonate chemistry variation was controlled by the large seasonal change of seawater temperature, though air-sea CO 2 exchange, biological activity (primary production-respiration), and riverine inputs also exerted a significant influence. With the exception of summer, the Gulf of Trieste was a sink of atmospheric carbon dioxide, showing a very strong CO 2 fluxes from atmosphere into the sea (−16.10 mmol m −2 day −1 ) during high wind speed event of north easterly Bora wind. The CO 2 influx was particularly evident in winter, when the biological activity was at minimum and the low seawater temperature enhanced CO 2 solubility. During spring, the drawdown of CO 2 by primary production overwhelmed the CO 2 physical pump, driving a significant decrease of dissolved inorganic carbon (DIC), [CO 2 ], and increase of pH T25 °C . In summer the primary production in surface waters occurred with the same intensity as respiration in the bottom layer, so the net biological effect on the carbonate system was very low and the further reduction of seawater CO 2 concentration observed was mainly due to carbon dioxide degassing induced by high seawater temperature. Finally, during autumn the respiration was the predominant process, which determined an overall increase of DIC, [CO 2 ], and decrease of pH T25 °C . This was particularly evident when the breakdown of summer stratification occurred and a large amount of CO 2 , generated by respiration and segregated below the pycnocline, was released back to the whole water column. Local rivers also significantly affected the carbonate system by direct input of total alkalinity (A T ) coming from the chemical weathering of carbonate rocks, which dominate the river watershed. Our finding clearly demonstrates a high A T concentration in low salinity surface waters (A T max = 2742.8 μmol kg −1 ) and a negative A T -salinity correlation. As a result the Gulf of Trieste revealed a low Revelle factor (10.1) and one of the highest buffer capacities of the Mediterranean Sea (s DIC = 0.31 mmol kg −1 ), which allows the system to store a significant amount of atmospheric CO 2 with a small decrease of seawater pH.

Marine bioconstructions are biodiversity-rich, three-dimensional biogenic structures, regulating key ecological functions of benthic ecosystems worldwide. Tropical coral reefs are outstanding for their beauty, diversity and complexity, but analogous types of bioconstructions are also present in temperate seas. The main bioconstructions in the Mediterranean Sea are represented by coralligenous formations, vermetid reefs, deep-sea cold-water corals, Lithophyllum byssoides trottoirs, coral banks formed by the shallow-water corals Cladocora caespitosa or Astroides calycularis, and sabellariid or serpulid worm reefs. Bioconstructions change the morphological and chemicophysical features of primary substrates and create new habitats for a large variety of organisms, playing pivotal roles in ecosystem functioning. In spite of their importance, Mediterranean bioconstructions have not received the same attention that tropical coral reefs have, and the knowledge of their biology, ecology and distribution is still fragmentary. All existing data about the spatial distribution of Italian bioconstructions have been collected, together with information about their growth patterns, dynamics and connectivity. The degradation of these habitats as a consequence of anthropogenic pressures (pollution, organic enrichment, fishery, coastal development, direct physical disturbance), climate change and the spread of invasive species was also investigated. The study of bioconstructions requires a holistic approach leading to a better understanding of their ecology and the application of more insightful management and conservation measures at basin scale, within ecologically coherent units based on connectivity: the cells of ecosystem functioning.

Marine bioconstructions are biodiversity-rich, three-dimensional biogenic structures, regulating key ecological functions of benthic ecosystems worldwide. Tropical coral reefs are outstanding for their beauty, diversity and complexity, but analogous types of bioconstructions are also present in temperate seas. The main bioconstructions in the Mediterranean Sea are represented by coralligenous formations, vermetid reefs, deep-sea cold-water corals, Lithophyllum byssoides trottoirs, coral banks formed by the shallow-water corals Cladocora caespitosa or Astroides calycularis, and sabellariid or serpulid worm reefs. Bioconstructions change the morphological and chemicophysical features of primary substrates and create new habitats for a large variety of organisms, playing pivotal roles in ecosystem functioning. In spite of their importance, Mediterranean bioconstructions have not received the same attention that tropical coral reefs have, and the knowledge of their biology, ecology and distribution is still fragmentary. All existing data about the spatial distribution of Italian bioconstructions have been collected, together with information about their growth patterns, dynamics and connectivity. The degradation of these habitats as a consequence of anthropogenic pressures (pollution, organic enrichment, fishery, coastal development, direct physical disturbance), climate change and the spread of invasive species was also investigated. The study of bioconstructions requires a holistic approach leading to a better understanding of their ecology and the application of more insightful management and conservation measures at basin scale, within ecologically coherent units based on connectivity: the cells of ecosystem functioning.

Submarine caves at the Cape of Otranto in South-Eastern Italy host eccentric stalactites which have been recently recognised as completely biogenic. The possibility to use the calcareous tubules of Polichaete forming the inner texture of the stalactites as suitable samples for radiocarbon dating is described. AMS radiocarbon dating analyses performed on samples taken at different positions along the longitudinal axis of three different stalactites allowed to obtain information about the duration of the formation phase, to determine the growth-rate at different stages of evolution and to establish the complete submarine origin of the stalactites. The comparison of the radiocarbon data obtained for the different studied structures reveal also similarities as well as important differences between single stalactites, supplying new information about their response to environmental changes in the same, confined ecosystem.

Submarine caves at the Cape of Otranto (SE, Italy) host pseudostalactites. Only recently have they been recognised as originating mainly from the marine tube worm Protula tubularia (Serpulidae, Polychaeta). Their formation depends on the adaptability, life history and behaviour of that species in the cave habitat. The dating of calcareous tubes in the pseudostalactite core represents the first attempt to describe the formation of such bio-construction, and the gregarious behaviour of the species. Calcareous tubes along the core axis of three pseudostalactites removed from the cave lu Lampiu`ne (Otranto, South East Italy) have been dated using the 14C method. Measures established ages from 2600 to 5000 years for the three structures. This extremely long period (when compared with the life span of each worm) suggests that each tube aggregation is the result of punctuated growth periods alternated with long standstill phases. At the end of a growth period, each tube aggregation was covered with a brownish concretion, completing the pseudostalactite.

International audience; Most global ocean models are based on the assumption of a " steady state " ocean. Here, we investigate the validation of this hypothesis for the anthropized Mediterranean Sea. In order to do so, we calculated the mixing coefficients of the water masses detected in this sea via an optimum multiparameter analysis referred to as the MIX approach, using data from the BOUM (2008) and MedSeA (2013) cruises. The comparison of the mixing coefficients of each water mass, between 2008 and 2013, indicates that some of their proportions have significantly changed. Surface water mass proportions did not change significantly (∆ 0.05-0.1), while intermediate and deep water mass mixing coefficients of both Eastern and Western basins were significantly modified (~∆ 0.35). This study clearly shows that the Mediterranean seawater is not in a " steady state " .

Although CO2 capture and storage in deep, offshore reservoirs is a proven technology, as illustrated by over 15 years of operation of the Sleipner site in the Norwegian North Sea, potential leakage from such sites into the overlying water column remains a concern for some stakeholders. Therefore, we are obliged to carefully assess our ability to predict and monitor the migration, fate, and potential ecosystem impact of any leaked CO2. The release of bubbles from the sea floor, their upward movement, and their dissolution into the surrounding water controls the initial boundary conditions, and thus an understanding of the behavior of CO2 bubbles is critical to address such issues related to monitoring and risk assessment. The present study describes results from an in situ experiment conducted in 12 m deep marine water near the extinct volcanic island of Panarea (Italy). Bubbles of a controlled size were created using natural CO2 released from the sea floor, and their evolution during ascent in the water column was monitored via both video and chemical measurements. The obtained results were modelled and a good fit was obtained, showing the potential of the model as a predictive tool. These preliminary results and an assessment of the difficulties encountered are examined and will be used to improve experimental design for the subsequent phase of this research.

In the frame of the INTERREG III CISM project, sediment cores were collected at 2 stations in the Gulf of Vlorë to study the plankton resting stage assemblages. A total of 87 morphotypes were identified and produced by Dinophyta, Ciliophora, Rotifera, and Crustacea. In 22 cases, the cyst belonged to a species absent from the plankton of the same period. The most abundant resting stages were those produced byScrippsiellaspecies (Dinophyta). Some calcareous cysts were identified as fossil species associated with Pleistocene to Pliocene sediment, although they were also found in surface sediments and some of them successfully germinated, thus proving their modern status. Total abundance generally decreased with sediment depth at station 40, while station 45 showed distinct maxima at 3 and 8 cm below the sediment surface. The depth of peak abundance in the sediment varied with species. This paper presents the first study of the plankton resting stages in the Bay of Vlorë. The study confirmed the utility of this type of investigation for a more correct evaluation of species diversity. In addition, the varying distribution with sediment depth suggests that this field could be of some importance in determining the history of species assemblages.