Ocean acidification processes in coastal and offshore ecosystems

2013/2014Since the beginning of Industrial Revolution a massive amount of atmospheric carbon dioxide, produced by human activity, has been absorbed by the World’s Oceans. This process has led to an acidification of marine waters on a global scale and is one of the most serious threats facing marine ecosystems in this century. The negative impacts of ocean acidification could be much more relevant in coastal ecosystems, where marine life is concentrated and biogeochemical processes are more active. However, future projections of pH reduction in these areas are difficult to estimate because result from multiple physical and biological drivers, including watershed weathering, river-born nutrient inputs, and changes in ecosystem structure and metabolism. In order to assess the sensibility of the Gulf of Trieste to the ocean acidification, high quality determination of the marine carbonate system (pHT, total alkalinity, dissolved inorganic carbon-DIC, buffer capacity) and other related biogeochemical parameters were carried out along a transect from the Isonzo River mouth to the centre of the gulf and at the coastal Long Term Ecological Research station C1. At the same time the biological influence of organic matter production and decomposition on the marine CO2 system was estimated using 14C primary production and heterotrophic prokaryote production (by 3H-leucine incorporation). The two years long measurements revealed a complex dynamic of the marine carbonate system, due to the combined effects of local freshwater inputs, biological processes, and air-sea CO2 exchange. However, it was possible to estimate the influence of the different drivers on a seasonal time scale. In winter the very low seawater temperature (minima = 2.88 °C) and strong Bora events determined a marked dissolution of atmospheric CO2 and elevated DIC concentration. During warm seasons the DIC concentration gradually decreased in the surface layer, due to biological drawdown (primary production) and thermodynamic equilibria (CO2 degassing), whereas under the pycnocline the respiration and remineralisation of organic matter prevailed, causing a temporary acidification of bottom waters. The winter seawater invasion of atmospheric CO2 was balanced by high riverine AT input (maxima ∼ 2933 µmol kg-1), derived mainly from chemical weathering of carbonate rocks of the surrounding karstic area, which increased the buffer capacity of this system and probably could mitigate the effect of ocean acidification. The marine carbonate system was also analysed in the Middle and Southern Adriatic Sea, in order to estimate the concentration of anthropogenic carbon dioxide currently present in this area. The results suggested that the entire water column was contaminated by a large amount of anthropogenic CO2 and very high concentration was detected near the bottom, in correspondence of the North Adriatic Dense Waters. This finding supported the hypothesis that during dense water formation events the very low seawater temperature can favour the physical dissolution of atmospheric carbon dioxide, and also revealed the active role of the North Adriatic Sea in sequestering and storing anthropogenic CO2 into the deep layers of Mediterranean Sea.Dall’inizio della Rivoluzione Industriale ad oggi, una grande quantità di anidride carbonica antropogenica presente in atmosfera è stata assorbita dagli Oceani di tutto il mondo. Questo processo ha portato all’acidificazione del mare su scala globale e rappresenta una delle più gravi minacce per gli ecosistemi marini in questo secolo. L’impatto negativo di tale fenomeno, noto come ocean acidification, potrebbe essere maggiore soprattutto negli ecosistemi costieri, poiché è qui che si concentrano gli organismi marini ed è qui che i cicli biogeochimici risultano più attivi. Tuttavia è difficile stimare il futuro abbassamento del pH in queste aree a causa della loro complessità e della moltitudine dei processi fisici, chimici e biologici coinvolti (cambiamenti dello stato trofico e del metabolismo dell’ecosistema, input fluviale di nutrienti, materia organica e prodotti di dissoluzione delle rocce, ecc.). Allo scopo di valutare la vulnerabilità del Golfo di Trieste rispetto al processo di ocean acidification, per due anni sono state eseguite misure di elevata precisione del sistema carbonatico marino (pHT, alcalinità totale, carbonio inorganico disciolto-DIC, capacità tamponante) e di altri parametri biogeochimici correlati lungo un transetto che congiunge la foce del fiume Isonzo al centro del Golfo e nella stazione C1 sito LTER (Long Time Ecological Research C1). Inoltre, per valutare in maniera più approfondita l’influenza dei processi biologici sulla variabilità del sistema carbonatico, è stata stimata la produzione primaria, attraverso il metodo dell’incorporazione di 14C, e la produzione procariotica eterotrofa, attraverso l’incorporazione di 3H-leucina. I risultati hanno evidenziato una complessa dinamica del sistema carbonatico dovuta all’effetto e all’interazione degli apporti fluviali, dei processi biologici e dello scambio di CO2 tra atmosfera e mare. Su scala stagionale, tuttavia, è stata stimata l’influenza e il contributo dei diversi processi. In inverno, la bassa temperatura dell’acqua, che in un caso estremo ha raggiunto i 2.88 °C, e i forti venti di Bora hanno favorito la dissoluzione della CO2 atmosferica, determinando un incremento della concentrazione di DIC. Durante la primavera e l’estate i livelli di DIC sono diminuiti gradualmente negli strati superficiali, grazie all’effetto combinato della produzione primaria e alla perdita di CO2 verso l’atmosfera per degassamento. Nel periodo tardo estivo-autunnale, invece, al di sotto del picnoclino i processi di respirazione e remineralizzazione della materia organica sono risultati predominanti determinando, a causa dell’elevata concentrazione di CO2 prodotta, una temporanea acidificazione delle acque di fondo. Il forte assorbimento di CO2 atmosferica stimato durante l’inverno era, però, controbilanciato dall’apporto fluviale di alcalinità totale, derivante dal processo di dissoluzione delle rocce calcaree presenti nell’area carsica. Tale fenomeno ha determinato un aumento della capacità tamponante del sistema, mitigando probabilmente il processo di ocean acidification in quest’area. Parallelamente alle analisi nel Golfo di Trieste, il sistema carbonatico marino è stato analizzato anche nel Medio e Sud Adriatico, con lo scopo di stimare la concentrazione di anidride carbonica antropogenica attualmente presente in questi sottobacini. I risultati hanno dimostrato come tutta la colonna d’acqua avesse assorbito una grande quantità di CO2 antropica. In particolare elevate concentrazioni sono state individuate sul fondo, in corrispondenza delle acque dense di origine nord adriatica. Tali risultati hanno confermato l’ipotesi secondo la quale in inverno, durante il processo di formazione di acque dense nel Nord Adriatico, le basse temperature raggiunte dalle acque possono favorire la dissoluzione fisica della CO2 atmosferica. Hanno dimostrato, inoltre, l’importante ruolo svolto da tutto il bacino nord adriatico nel sequestrare e trasportare la CO2 antropica nelle profondità del mare, estendendo il processo di ocean acidification anche ad aree meno contaminate.XXVII Ciclo198

Is there a risk of addiction to ketamine during the treatment of depression? A systematic review of available literature

Background: Ketamine has demonstrated both rapid and sustained efficacy in treating depression, especially in treatment-resistant cases. However, concerns regarding the addictive potential of ketamine during long-term depression treatment persist among clinicians. Aim: This review aimed to summarise the evidence on addiction phenomena associated with ketamine treatment of depression. Methods: A comprehensive search was conducted in MEDLINE, Embase, PsycInfo and Global Health databases, with additional relevant studies identified through reference lists. Sixteen studies were included, comprising six randomised controlled trials, three single-arm open-label studies, one retrospective study, three case series and three case reports, for a total of 2174 patients. Results: The studies employed various routes of administration, including intravenous, intramuscular, intranasal, oral and sublingual. Ketamine was administered in the racemic form, except for the studies that utilised intranasal esketamine. Among the included population, four patients were reported to exhibit clear signs of tolerance to the antidepressant effect of ketamine or dependence on the drug, while the majority did not. Cases of addiction phenomena reported in studies that did not meet the inclusion criteria are also discussed. Conclusions: Despite the heterogeneity in study designs and outcome assessment methods, the review underscores the relative safety of ketamine treatment for adult patients with depression, emphasising the importance of medically supervised administration, vigilant monitoring and judicious dosing. Future long-term studies employing quantitative scales to assess dependence phenomena could contribute to strengthening the evidence for the safe and effective use of ketamine in the treatment of depression.</p

Plankton Resting Stages in the Marine Sediments of the Bay of Vlorë (Albania)

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

Greening of Svalbard in the twentieth century driven by sea ice loss and glaciers retreat

Abstract The greening of previously barren landscapes in the Arctic is one of the most relevant responses of terrestrial ecosystem to climate change. Analyses of satellite data (available since ~1980) have revealed a widespread tundra advance consistent with recent global warming, but the length is insufficient to resolve the long-term variability and the precise timing of the greening onset. Here, we measured plant-derived biomarkers from an Arctic fjord sediment core as proxies for reconstructing past changes in tundra vegetation during the transition from the Little Ice Age to modern warming. Our findings revealed a rapid expansion of the tundra since the beginning of the twentieth century, largely coinciding with the decline of summer sea ice extent and glacier retreat. The greening trend inferred from biomarker analysis peaked significantly in the late 1990s, along with a shift in the tundra community towards a more mature successional stage. Most of these signals were consistent with the biomolecular fingerprints of vascular plant species that are more adapted to warmer conditions and have widely expanded in proglacial areas during recent decades. Our results suggest that the greening of Arctic fjords may have occurred earlier than previously thought, improving our mechanistic understanding of vegetation-climate-cryosphere interactions that will shape tundra vegetation under future warming projections

The Atlantification process in Svalbard: a broad view from the SIOS Marine Infrastructure network (ARiS)

Arctic marine systems are vital to the Earth’s ecological and climatic balance and harbour a unique biodiversity adapted to extreme conditions. However, they are under unprecedented threat from climate change, in particular from “Atlantification”, i.e., the loss of sea ice and the increasing influence of Atlantic Water (AW) in this region. Long-term observatories are crucial to detect even small changes in these dynamic ecosystems. Svalbard, with its easily accessible infrastructure, is a strategic location for studying these changes. We have identified marine time series that clearly illustrate the signature of Atlantification in the Svalbard region over the last two decades. These time series provide insight into the propagation of AW and the interaction between the continental slope, the shelf and the fjord systems. Seasonal and multi-year temperature and salinity patterns illustrate the varying influence of AW, with long-term variability showing, among others, a freshening phase since 2018, possibly related to North Atlantic freshwater anomalies

Rapid Atlantification along the Fram Strait at the beginning 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

A population genomics insight by 2b‐RAD reveals populations' uniqueness along the Italian coastline in Leptopsammia pruvoti (Scleractinia, Dendrophylliidae)

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

Changes of energy fluxes in marine animal forests of the Anthropocene: factors shaping the future seascape

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 systems.Funding Agency European Union (EU) 327845 ICTA "Unit of Excellence" (MinECo) MDM2015-0552 CALMED project CTM2016-79547-R AGAUR Generalitat de Catalunya (MERS) 2017 SGR 1588 National Council for Scientific and Technological Development (CNPq)info:eu-repo/semantics/publishedVersio