ALBERT

Description: Finding the optimal structural design to avoid resonance by shifting eigenfrequencies out of the range of external frequencies has been a goal for decades. Biological structures, such as diatom shells, obtain an overall shape adaptation similar to their mode shapes, which might lead to improved vibration characteristics. The aim of this study was to investigate the eigenfrequency increases of a 1D Bernoulli beam, a 2D Kirchhoff plate and a 3D Timoshenko beam by pre-deforming the structures according to the corresponding mode shapes. Besides the maximisation of single eigenfrequencies, also the simultaneous increase of other eigenfrequencies were analysed. The results showed that the eigenfrequencies can be strongly increased by shaping the structures according to the corresponding mode shapes. Small pre-deformations led already to high eigenfrequency increases. In conclusion, the investigated, easy applicable method allowed a strong eigenfrequency increase by performing only small structural deformations without additional weight increase.

Description: The Antarctic Circumpolar Current (ACC) plays a crucial role in global ocean circulation by fostering deep-water upwelling and formation of new water masses. On geological timescales, ACC variations are poorly constrained beyond the last glacial. Here, we reconstruct changes in ACC strength in the central Drake Passage in vicinity of the modern Polar Front over a complete glacial-interglacial cycle (i.e., the past 140,000 years), based on sediment grain-size and geochemical characteristics. We found significant glacial-interglacial changes of ACC flow speed, with weakened current strength during glacials and a stronger circulation in interglacials. Superimposed on these orbital-scale changes are high-amplitude millennialscale fluctuations, with ACC strength maxima correlating with diatom-based Antarctic winter sea-ice minima, particularly during full glacial conditions. We infer that the ACC is closely linked to Southern Hemisphere millennial-scale climate oscillations, amplified through Antarctic sea ice extent changes. These strong ACC variations modulated Pacific-Atlantic water exchange via the “cold water route” and potentially affected the Atlantic Meridional Overturning Circulation and marine carbon storage.

Description: Humpback whale males are known to sing on their low-latitude breeding grounds, but it is well established that songs are also commonly produced ‘off-season’ on the feeding grounds or during migration. This opens exciting opportunities to investigate migratory aggregations, study humpback whale behavioral plasticity and potentially even assign individual singers to specific breeding grounds. In this study, we analyzed passive acoustic data from 13 recording positions and multiple years (2011–2018) within the Atlantic sector of the Southern Ocean (ASSO). Humpback whale song was detected at nine recording positions in five years. Most songs were recorded in May, austral fall, coinciding with the rapid increase in sea ice concentration at most recording positions. The spatio-temporal pattern in humpback whale singing activity on Southern Ocean feeding grounds is most likely shaped by local prey availability and humpback whale migratory strategies. Furthermore, the comparative analyses of song structures clearly show a differentiation of two song groups, of which one was solely recorded at the western edge of the ASSO and the other song group was recorded throughout the ASSO. This new finding suggests a common feeding ground occupation by multiple humpback whale populations in the ASSO, allowing for cultural and potentially even genetic exchange among populations.

Description: In this work, we analysed aerosol measurements from lidar and PM10 samples around the European Arctic site of Ny-Ålesund during late winter–early spring 2019. Lidar observations above 700 m revealed time-independent values for the aerosol backscatter coefficient (ββ), colour ratio (CR), linear particle depolarisation ratio (δδ) and lidar ratio (LR) from January to April. In contrast to previous years, in 2019 the early springtime backscatter increase in the troposphere, linked to Arctic haze, was not observed. In situ nss-sulphate (nss-SO2−4) concentration was measured both at a coastal (Gruvebadet) and a mountain (Zeppelin) station, a few kilometres apart. As we employed different measurement techniques at sites embedded in complex orography, we investigated their agreement. From the lidar perspective, the aerosol load (indicated by ββ) above 700 m changed by less than a factor of 3.5. On the contrary, the daily nss-SO2−4 concentration erratically changed by a factor of 25 (from 0.1 to 2.5 ng m−3) both at Gruvebadet and Zeppelin station, with the latter mostly lying above the boundary layer. Moreover, daily nss-SO2−4 concentration was remarkably variable (correlation about 0.7 between the sites), despite its long-range origin. However, on a seasonal average basis the in situ sites agreed very well. Therefore, it can be argued that nss-SO2−4 advection mainly takes place in the lowest free troposphere, while under complex orography it is mixed downwards by local boundary layer processes. Our study suggests that at Arctic sites with complex orography ground-based aerosol properties show higher temporal variability compared to the free troposphere. This implies that the comparison between remote sensing and in situ observations might be more reasonable on longer time scales, i.e., monthly and seasonal basis even for nearby sites.

Description: 〈jats:p〉High-accumulation sites are crucial for understanding the patterns and mechanisms of climate and environmental change in Antarctica since they allow gaining high-resolution proxy records from firn and ice. Here, we present new glacio- and isotope-geochemical data at sub-annual resolution from a firn core retrieved from an ice cap on Plateau Laclavere (LCL), northern Antarctic Peninsula, covering the period 2012–2015. The signals of two volcanic eruptions and two forest fire events in South America could be identified in the non-sea-salt sulphur and black carbon records, respectively. Mean annual snow accumulation on LCL amounts to 2500 kg m−2 a−1 and exhibits low inter-annual variability. Time series of δ18O, δD and d excess show no seasonal cyclicity, which may result from (1) a reduced annual temperature amplitude due to the maritime climate and (2) post-depositional processes. The firn core stratigraphy indicates strong surface melt on LCL during austral summers 2013 and 2015, likely related to large-scale warm-air advection from lower latitudes and temporal variations in sea ice extent in the Bellingshausen-Amundsen Sea. The LCL ice cap is a highly valuable natural archive since it captures regional meteorological and environmental signals as well as their connection to the South American continent.〈/jats:p〉

Description: Solar light/dark cycles and seasonal photoperiods underpin daily and annual rhythms of life on Earth. Yet, the Arctic is characterized by severalmonths of permanent illumination (‘‘midnight sun’’). To determine the persistence of 24h rhythms during the midnight sun, we investigated transcriptomic dynamics in the copepod Calanus finmarchicus during the summer solstice period in the Arctic, with the lowest diel oscillation and the highest altitude of the sun’s position. Here we reveal that in these extreme photic conditions, a widely rhythmic daily transcriptome exists, showing that very weak solar cues are sufficient to entrain organisms. Furthermore, at extremely high latitudes and under sea-ice, gene oscillations become re-organized to include 〈24h rhythms. Environmental synchronization may therefore be modulated to include non-photic signals (i.e. tidal cycles). The ability of zooplankton to be synchronized by extremely weak diel and potentially tidal cycles, may confer an adaptive temporal reorganization of biological processes at high latitudes.

Description: Wildfires, as a key disturbance in forest ecosystems, are shaping the world's boreal landscapes. Changes in fire regimes are closely linked to a wide array of environmental factors, such as vegetation composition, climate change, and human activity. Arctic and boreal regions and, in particular, Siberian boreal forests are experiencing rising air and ground temperatures with the subsequent degradation of permafrost soils leading to shifts in tree cover and species composition. Compared to the boreal zones of North America or Europe, little is known about how such environmental changes might influence long-term fire regimes in Russia. The larch-dominated eastern Siberian deciduous boreal forests differ markedly from the composition of other boreal forests, yet data about past fire regimes remain sparse. Here, we present a high-resolution macroscopic charcoal record from lacustrine sediments of Lake Khamra (south-west Yakutia, Siberia) spanning the last ca. 2200 years, including information about charcoal particle sizes and morphotypes. Our results reveal a phase of increased charcoal accumulation between 600 and 900 CE, indicative of relatively high amounts of burnt biomass and high fire frequencies. This is followed by an almost 900-year-long period of low charcoal accumulation without significant peaks likely corresponding to cooler climate conditions. After 1750 CE fire frequencies and the relative amount of biomass burnt start to increase again, coinciding with a warming climate and increased anthropogenic land development after Russian colonization. In the 20th century, total charcoal accumulation decreases again to very low levels despite higher fire frequency, potentially reflecting a change in fire management strategies and/or a shift of the fire regime towards more frequent but smaller fires. A similar pattern for different charcoal morphotypes and comparison to a pollen and non-pollen palynomorph (NPP) record from the same sediment core indicate that broad-scale changes in vegetation composition were probably not a major driver of recorded fire regime changes. Instead, the fire regime of the last two millennia at Lake Khamra seems to be controlled mainly by a combination of short-term climate variability and anthropogenic fire ignition and suppression.

Description: The calving of A-68, the 5,800-km2, 1-trillion-ton iceberg shed from the Larsen C Ice Shelf in July 2017, is one of over 10 significant ice-shelf loss events in the past few decades resulting from rapid warming around the Antarctic Peninsula. The rapid thinning, retreat, and collapse of ice shelves along the Antarctic Peninsula are harbingers of warming effects around the entire continent. Ice shelves cover more than 1.5 million km2 and fringe 75% of Antarctica's coastline, delineating the primary connections between the Antarctic continent, the continental ice, and the Southern Ocean. Changes in Antarctic ice shelves bring dramatic and large-scale modifications to Southern Ocean ecosystems and continental ice movements, with global-scale implications. The thinning and rate of future ice-shelf demise is notoriously unpredictable, but models suggest increased shelf-melt and calving will become more common. To date, little is known about sub-ice-shelf ecosystems, and our understanding of ecosystem change following collapse and calving is predominantly based on responsive science once collapses have occurred. In this review, we outline what is known about (a) ice-shelf melt, volume loss, retreat, and calving, (b) ice-shelf-associated ecosystems through sub-ice, sediment-core, and pre-collapse and post-collapse studies, and (c) ecological responses in pelagic, sympagic, and benthic ecosystems. We then discuss major knowledge gaps and how science might address these gaps. This article is categorized under: Climate, Ecology, and Conservation 〉 Modeling Species and Community Interactions.

Description: We propose to make the damping time scale, which governs the decay of pseudo-elastic waves in the Elastic Viscous Plastic (EVP) sea-ice solvers, independent of the external time step and large enough to warrant numerical stability for a moderate number of internal time steps. A necessary condition is that the forcing on sea ice varies slowly on the damping time scale, in which case an EVP solution may still approach a Viscous Plastic one, but on a time scale longer than a single external time step. In this case, the EVP method becomes very close to the recently proposed modified EVP (mEVP) method in terms of stability and simulated behavior. In a simple test case dealing with sea ice breaking under the forcing of a moving cyclone, the EVP method with an enlarged damping time scale can simulate linear kinematic features which are very similar to those from the traditional EVP implementation, although a much smaller number of internal time steps is used. There is more difference in sea-ice thickness and linear kinematic features simulated in a realistic Arctic configuration between using the traditional and our suggested choices of EVP damping time scales, but it is minor considering model uncertainties associated with choices of many other parameters in sea-ice models.

Description: The variety of Earth’s organisms is manifold. However, it is the small-scale marine community that makes the world goes round. Microbial organisms of pro- and eukaryotic origin drive the carbon supply and nutrient cycling, thus are mediating the primary productivity within the world largest ecosystem called ocean. But due to the ocean’s great size and large number of biogeographically habitats, the total of microbial species can hardly be grabbed and therefore their functional roles not fully described. However, recent advances in high-throughput sequencing technologies are revolutionizing our understanding of the marine microbial diversity, ecology and evolution. Nowadays, research questions on species differentiation can be solved with genomic approaches such as metabarcoding, while transcriptomics offers the possibility to assign gene functions even to a single cell, e.g., single-cell transcriptomics. On the other hand, due to the diversified amount of sequencing data, the certainty of a data crisis is currently evolving. Scientists are forced to broaden their view on bioinformatics resources for analysis and data storage in from of, e.g., cloud services, to ensure the data’s exchangeability. Which is why time resources are now shifting toward solving data problems rather than answering the eco-evolutionary questions stated in the first place. This review is intended to provide exchange on *omics approaches and key points for discussions on data handling used to decipher the relevant diversity and functions of microbial organisms in the marine ecosystem.

Description: Previous scientific ocean drilling expeditions have revealed that sediments deposited in the Kerguelen Plateau region have the potential to provide an out-standing chronicle of regional and global climate changes. In particular, this area is an excellent location to monitor subantarctic and high-latitude climate dynamics and obtain far-field information documenting Antarctic climate history in a world warmer than today. Here we report first results from site survey RV Sonne cruise SO272 that sailed January 11 to March 4 2020 from Port Louis, Mauritius, to Cape Town, South Africa. During the cruise ~4000 km of high resolution seismic reflection data were recorded along 18 seismic profiles across the central and southern Kerguelen Plateau. At 11 stations sediment cores with recoveries of up to 10m were retrieved [GU1] to complement the seismic studies and provide ages of the outcropping sediment at the sea floor. Three gravity cores targeted the Labuan Basin recovering Plio-Pleistocene diatom ooze with drop stones and rhythmic changes in reflectance. Eight gravity cores targeted the Raggatt Basin with the main objective to penetrate through the upper undifferentiated layer of surface sediment and probe the below much older outcropping sediment. Carbonate rich sediments were successfully retrieved at three locations with microfossil assemblages of late Eocene age. X-ray fluorescence core scanning, benthic stable isotope and bio-stratigraphic data will be presented. Seismic and geological datasets will form the base for an IODP full proposal to drill a complete Miocene to Paleocene high latitude sediment package, build upon the #983-Pre IODP proposal.

Description: We investigated diets of 24 Barents Sea zooplankton taxa to understand pelagic food-web processes during late summer, including the importance of sea ice algae-produced carbon. This was achieved by combining insights derived from multiple and complementary trophic marker approaches to construct individual aspects of feeding. Specifically, we determined proportions of algal-produced fatty acids (FAs) to reflect the reliance on diatom- versus dinoflagellate-derived carbon, highly branched isoprenoid (HBI) lipids that distinguish between ice-associated and pelagic carbon sources, and sterols to indicate the degree of carnivory. Copepods had the strongest diatom signal based on FAs, while a lack of sea ice algae-associated HBIs (IP25, IPSO25) suggested that they fed on pelagic rather than ice-associated diatoms. The amphipod Themisto libellula and the ctenophores Beroë cucumis and Mertensia ovum had a higher contribution of dinoflagellate-produced FAs. There was a high degree of carnivory in this food web, as indicated by the FA carnivory index 18:1(n−9)/18:1(n−7) (mean value 〈 1 only in the pteropod Clione limacina), the presence of copepod-associated FAs in most of the taxa, and the absence of algal-produced HBIs in small copepod taxa, such as Oithona similis and Pseudocalanus spp. The coherence between concentrations of HBIs and phytosterols within individuals suggested that phytosterols provide a good additional indication for algal ingestion. Sea ice algae-associated HBIs were detected in six zooplankton species (occurring in krill, amphipods, pteropods, and appendicularians), indicating an overall low to moderate contribution of ice-associated carbon from late-summer sea ice to pelagic consumption. The unexpected occurrence of ice-derived HBIs in pteropods and appendicularians, however, suggests an importance of sedimenting ice-derived material at least for filter feeders within the water column at this time of year.

Description: Investigating the physical conditions underlying and enabling fast glacier flow is crucial to understanding the future stability of ice sheets, as well as their impact on future sea-level rise. Seismic surveys have been widely used to measure material properties of the ice and substrate, including seismic velocity structure, anisotropy, and bed properties. While traditional seismic surveys rely on natural seismicity or man-made sources such as explosives, anthropogenic noise generated through ice-core drilling can also be used as a seismic source. Placing geophones around an ice-core drilling site therefore presents an exciting opportunity to complement and extend measurements from ice cores to the surrounding area. Here, we present preliminary results from a seismic investigation conducted using noise generated by ice-core drilling activities at the East Greenland Ice Core Project (EGRIP) site. The EGRIP site is located near the onset region of the Northeast Greenland Ice Stream (NEGIS), which drains over 10% of the Greenland Ice Sheet. The ice-core drilling process creates a variety of semi-continuous (e.g., generator-induced) and impulsive (e.g., core break) seismic source signals. As drilling progresses through the ice column, the corresponding variation in seismic signals can be used to generate a vertical profile of seismic properties. In the summer of 2019, nine 3-component surface geophones were deployed at 0, 300, 750, 1500 and 3000 m distance from the drill site along two lines corresponding to the along- and cross-flow directions of the ice stream. The network recorded at a sampling frequency of 400 Hz for 28 days, during which drilling progressed between 1920 and 2110 m depth below the surface. Both continuous and impulsive sources related to the drilling process were recorded at all stations. Impulsive arrivals were identified using STA/LTA phase-picking across multiple components and stations. Because the depth of the drill head at any given time is known, the move-out of each event could then be used to determine the integrated seismic velocity structure along the source-receiver ray path. Additionally, sporadic passive microseismic signals resulting from ice stream motion over the bed were observed at all stations. Both individually distinguishable icequakes and 3-5 minute-long “gliding” tremors were recorded, indicative of stick-slip motion at the bed of NEGIS. Further work will concentrate on modelling these tremors to resolve the shear modulus of the substrate, and on incorporating continuous drill-generated noise into our overall analysis. Our approach demonstrates the added value of opportunistic seismic networks as a complement to ice drilling operations.

Description: Polymetallic nodules 1) Occur on abyssal plains as lumps of aggregated minerals rendering their collection under commercial consideration 2) Provide hard substrate for sessile fauna and influence distribution of local infauna and bacterial communities1

Description: Climate change-driven thermal erosion makes Muostakh Island in the southern Laptev Sea (70°35´ N, 130° 0´ E) a very fragile ecosystem of the Arctic. Thus, understanding its biodiversity, the changes and loss in response to climate is a timely and pressing scientific objective. Here, we characterize the microbiome associated with several ice wedges covering the past ~45,000 years of climate/ecosystem history. Ice wedges are a specific feature in the northern permafrost landscapes. They develop seasonally by spring-melting of snow that runs through permafrost contraction cracks, accumulates and creates ice formations in the wintertime through congelifraction. Such environment offers ideal conditions for the preservation of microbial cells and DNA over geological time. Our work tackles four main research aspects, requiring an interdisciplinary approach with synergies between microbial ecology, geo- and paleo-sciences. First, we characterize the ice wedge mineral composition as an environmental micro-niche. Second, we analyze the biodiversity of the microbial communities via shotgun metagenomics of the ancient DNA (aDNA) extracted from the ice wedges. Third, we investigate the biomass content by recovering and enumerating microbial cells present in the ice wedges. In addition, we apply infrared spectroscopy to obtain cellular fingerprints that can serve as biomarkers. Finally, we assess the physiological state of microorganisms using stable isotope probing (SIP) experiments in microcosms that reproduce the environmental conditions (subzero temperature and anoxic conditions). By integrating microbial biodiversity with activity and environmental context, this study will provide valuable new insights into Muostakh’s ice wedge microbiome and the dynamics underlying its changes over time and climatic conditions.

Description: A thorough and reliable assessment of changes in sea surface water temperatures (SSWTs) is essential for understanding the effects of global warming on long-term trends in marine ecosystems and their communities. The first long-term temperature measurements were established almost a century ago, especially in coastal areas, and some of them are still in operation. However, while in earlier times these measurements were done by hand every day, current environmental long-term observation stations (ELTOS) are often fully automated and integrated in cabled underwater observatories (UWOs). With this new technology, year-round measurements became feasible even in remote or difficult to access areas, such as coastal areas of the Arctic Ocean in winter, where measurements were almost impossible just a decade ago. In this context, there is a question over what extent the sampling frequency and accuracy influence results in long-term monitoring approaches. In this paper, we address this with a combination of lab experiments on sensor accuracy and precision and a simulated sampling program with different sampling frequencies based on a continuous water temperature dataset from Svalbard, Arctic, from 2012 to 2017. Our laboratory experiments showed that temperature measurements with 12 different temperature sensor types at different price ranges all provided measurements accurate enough to resolve temperature changes over years on a level discussed in the literature when addressing climate change effects in coastal waters. However, the experiments also revealed that some sensors are more suitable for measuring absolute temperature changes over time, while others are more suitable for determining relative temperature changes. Our simulated sampling program in Svalbard coastal waters over 5 years revealed that the selection of a proper sampling frequency is most relevant for discriminating significant long-term temperature changes from random daily, seasonal, or interannual fluctuations. While hourly and daily sampling could deliver reliable, stable, and comparable results concerning temperature increases over time, weekly sampling was less able to reliably detect overall significant trends. With even lower sampling frequencies (monthly sampling), no significant temperature trend over time could be detected. Although the results were obtained for a specific site, they are transferable to other aquatic research questions and non-polar regions.

Description: Rapid climate change is placing many marine species at risk of local extinction. Recent studies show that epigenetic mechanisms (e.g. DNA methylation, histone modifications) can facilitate both within and transgenerational plasticity to cope with changing environments. However, epigenetic reprogramming (erasure and re-establishment of epigenetic marks) during gamete and early embryo development may hinder transgenerational epigenetic inheritance. Most of our knowledge about reprogramming stems from mammals and model organisms, whereas the prevalence and extent of reprogramming among non-model species from wild populations is rarely investigated. Moreover, whether reprogramming dynamics are sensitive to changing environmental conditions is not well known, representing a key knowledge gap in the pursuit to identify mechanisms underlying links between parental exposure to changing climate patterns and environmentally-adapted offspring phenotypes. Here, we investigated epigenetic reprogramming (DNA methylation/hydroxymethylation) and gene expression across gametogenesis and embryogenesis of marine stickleback (Gasterosteus aculeatus) under three ocean warming scenarios (ambient, + 1.5 °C and + 4 °C). We found that parental acclimation to ocean warming led to dynamic and temperature-sensitive reprogramming throughout offspring development. Both global methylation/hydroxymethylation and expression of genes involved in epigenetic modifications were strongly and differentially affected by the increased warming scenarios. Comparing transcriptomic profiles from gonads, mature gametes, and early embryonic stages showed sex-specific accumulation and temperature sensitivity of several epigenetic actors. DNA methyltransferase induction was primarily maternally inherited (suggesting maternal control of remethylation), whereas induction of several histone-modifying enzymes was shaped by both parents. Importantly, massive, temperature-specific changes to the epigenetic landscape occurred in blastula, a critical stage for successful embryo development, which could, thus, translate to substantial consequences for offspring phenotype resilience in warming environments. In summary, our study identified key stages during gamete and embryo development with temperature-sensitive reprogramming and epigenetic gene regulation, reflecting potential “windows of opportunity” for adaptive epigenetic responses under future climate change.

Description: The Asian brush-clawed shore crab Hemigrapsus takanoi was introduced to the northern Wadden Sea (southeastern North Sea) in 2009 and now represents one of the most abundant brachyuran crab species. Abundance studies revealed an increase of mean crab densities on mixed reefs of native blue mussels (Mytilus edulis) and Pacific oysters (Magallana gigas) from 18 individuals m−2 in 2011 to 216 individuals m−2 in 2020. Despite its current high densities only little is known about the feeding habits of H. takanoi, its effects on prey populations and on the associated community in the newly invaded habitat. We summarize results of individual field and laboratory experiments that were conducted to assess feeding habits and consumption effects caused by Asian brush-clawed shore crabs and, additionally, compare the feeding ecology of H. takanoi with the one of the native shore crab Carcinus maenas. Field experiments manipulating crab densities revealed that both crab species affected the recruitment success of blue mussels, Pacific oysters and Australian barnacles (Austrominius modestus) with highest number of recruits at crab exclusion. However, endobenthic polychaetes within the reefs were differently affected. Only the native C. maenas caused a significant reduction in polychaete densities, whereas the introduced H. takanoi had no effect. Additional comparative laboratory studies revealed that single C. maenas consume more juvenile blue mussels than Asian brush-clawed shore crabs of the same size class. When offering amphipods as a mobile prey species, we found the same pattern with higher consumption rates by C. maenas than by H. takanoi. For Asian but not for native shore crabs, we detected a sex-dependent feeding behavior with male H. takanoi preferring blue mussels, while females consumed more amphipods. Considering mean crab densities and feeding behavior, our results suggest that despite lower consumption rates of single crabs, Asian brush-clawed shore crabs can cause stronger impacts on prey organisms than the native C. maenas, because H. takanoi exceeds their densities manifold. A strong impact of the invader on prey populations is supported by low amphipod occurrence at sites where H. takanoi density is high in the study area. Thus, the introduced Asian brush-clawed shore crab is an additional consumer with significant effects on the associated community of mixed reefs of mussels and oysters in the Wadden Sea.

Description: 〈jats:p〉Abstract. A realistic simulation of the surface mass balance (SMB) is essential for simulating past and future ice-sheet changes. As most state-of-the-art Earth system models (ESMs) are not capable of realistically representing processes determining the SMB, most studies of the SMB are limited to observations and regional climate models and cover the last century and near future only. Using transient simulations with the Max Planck Institute ESM in combination with an energy balance model (EBM), we extend previous research and study changes in the SMB and equilibrium line altitude (ELA) for the Northern Hemisphere ice sheets throughout the last deglaciation. The EBM is used to calculate and downscale the SMB onto a higher spatial resolution than the native ESM grid and allows for the resolution of SMB variations due to topographic gradients not resolved by the ESM. An evaluation for historical climate conditions (1980–2010) shows that derived SMBs compare well with SMBs from regional modeling. Throughout the deglaciation, changes in insolation dominate the Greenland SMB. The increase in insolation and associated warming early in the deglaciation result in an ELA and SMB increase. The SMB increase is caused by compensating effects of melt and accumulation: the warming of the atmosphere leads to an increase in melt at low elevations along the ice-sheet margins, while it results in an increase in accumulation at higher levels as a warmer atmosphere precipitates more. After 13 ka, the increase in melt begins to dominate, and the SMB decreases. The decline in Northern Hemisphere summer insolation after 9 ka leads to an increasing SMB and decreasing ELA. Superimposed on these long-term changes are centennial-scale episodes of abrupt SMB and ELA decreases related to slowdowns of the Atlantic meridional overturning circulation (AMOC) that lead to a cooling over most of the Northern Hemisphere. 〈/jats:p〉

Description: Estuaries are highly dynamic, spatially complex systems showing large daily fluctuations in salinity. Estuarine organisms, especially small animals with limited locomotory capacities, are thus expected to have variable ecological and morphophysiological strategies. This paper evaluates the responses to salinity challenges in four species of neotropical annelids along a subtropical estuarine gradient by assessing mortality (i.e., tolerance) and changes in body weight (proxy for water fluxes). We selected the nereidids Alitta sp. and Laeonereis acuta, with broad salinity niches, and the nephtyid Nephtys fluviatilis and the melinnid Isolda pulchella, with either narrow salinity niches or a more restricted spatial range. Worms were weighed, exposed to salinities ranging from fresh water to full-strength seawater (0, 5, 15, 25, and 35) for 1, 6, 12, and 24 h, and weighed again after these exposure times. Their mortality (as absence of body movements or vascular circulation) rates were recorded to assess their ranges of tolerance to these treatments or their degree of euryhalinity. Their integument was characterized histologically to show possible morphological links to their tolerances. Both nereidids displayed stable body weights and thick integuments, compatible with the wide range of salinity tolerance and capacity to maintain body hydration. Body weight of Alitta sp. returned to initial values after 1 h at salinities ≥5. Body weight did not change in L. acuta at salinities ≥15; mortalities occurred only at salinity 0 after 12–24 h. Nephtys fluviatilis showed a thin integument and less variation in weight throughout the whole range of tested salinities, but mortality occurred after 24 h at salinity 0, at its reference salinity (3) and at 35. Isolda pulchella showed a lower capacity to maintain body weight/hydration and a thin integument, compatible with its relative stenohalinity and presence restricted to polyhaline marine sectors. Its weight variation was significant at all salinities except 35; mortality occurred at extreme salinities: 0 and 35. Responses of the four species were compatible with their distribution along the estuarine gradient, as an interesting outcome of their autecological traits, morphophysiological adaptations and evolutionary histories.

Description: The environmental risks associated to dumped munition, unexploded ordnance (UXO) and sunken war ships gaining more and more attention nowadays. Hundreds of wrecked ships and planes lie at the bottom of the North Sea alone, as well as thousands of tons of conventional and chemical munition. These warfare materials carry a significant risk of chemical leakage, posing a serve threat to marine wildlife. As part of the international EU project North Sea Wrecks (NSW), the present study aimed to assess the hazard potential of pollution by explosives on the marine fauna associated to sunken war ships loaded with munition and UXO. For this purpose, transplanted blue mussels (Mytilus edulis) were exposed for several month at two wrecks loaded with munition (HSM Basilisk and John Mahn) in order to detect leakage of explosives and to characterize the effects of those substances on mussel health. The hazardous potential was assessed using multi-biomarker analysis, which includes the enzyme activity of catalase (CAT), glutathione-S-transferase (GST) and acetylcholinesterase (AChE), as well as the histochemical biomarkers lipofuscin (LIPF), neutral lipids (NL) and glycogen (GLY). In addition, the condition index (CI) and the gonadal status were determined. Here, two cruises were conducted: One test cruise in 2019 to both wrecks, and a second in 2020 to the John Mahn, during which the main investigation took place. Chemical analysis of water samples, passive sampler, mussel tissue and sediments indicated leakage of explosives at both wrecks, as well as subsequent uptake by mussels and diffusion into the sediment. Detected chemical concentrations were in the range of a few nanograms. CI and gonad status indicated comparable mussel conditions between the stations. Biomarker results did not always correlate with increased explosive concentration or when exposed directly next to UXO’s. At most, moderate oxidative stress was detected using CAT and LIPF, but in general the low concentration of explosives and the short exposure time did not alter a biomarker response within mussels. In conclusion, the leakage of chemicals at the HSM Basilisk and the John Mahn was not high enough to endanger mussel health during the short-term experiment. It remains to be seen if the fish samples of the long-term experiment, which were also taken as part of the NSW project, will show more clear effects.

Description: 〈jats:title〉Abstract〈/jats:title〉 〈jats:p〉This article describes some use case studies and self-assessments of FAIR status of de.NBI services to illustrate the challenges and requirements for the definition of the needs of adhering to the FAIR (findable, accessible, interoperable and reusable) data principles in a large distributed bioinformatics infrastructure. We address the challenge of heterogeneity of wet lab technologies, data, metadata, software, computational workflows and the levels of implementation and monitoring of FAIR principles within the different bioinformatics sub-disciplines joint in de.NBI. On the one hand, this broad service landscape and the excellent network of experts are a strong basis for the development of useful research data management plans. On the other hand, the large number of tools and techniques maintained by distributed teams renders FAIR compliance challenging.〈/jats:p〉

Description: 〈jats:p〉Marine microorganisms contribute to the health of the global ocean by supporting the marine food web and regulating biogeochemical cycles. Assessing marine microbial diversity is a crucial step towards understanding the global ocean. The waters surrounding Iceland are a complex environment where relatively warm salty waters from the Atlantic cool down and sink down to the deep. Microbial studies in this area have focused on photosynthetic micro- and nanoplankton mainly using microscopy and chlorophyll measurements. However, the diversity and function of the bacterial and archaeal picoplankton remains unknown. Here, we used a co-assembly approach supported by a marine mock community to reconstruct metagenome-assembled genomes (MAGs) from 31 metagenomes from the sea surface and seafloor of four oceanographic sampling stations sampled between 2015 and 2018. The resulting 219 MAGs include 191 bacterial, 26 archaeal and two eukaryotic MAGs to bridge the gap in our current knowledge of the global marine microbiome.〈/jats:p〉

Description: 〈jats:p〉Planctomycetes are bacteria that were long thought to be unculturable, of low abundance, and therefore neglectable in the environment. This view changed in recent years, after it was shown that members of the phylum Planctomycetes can be abundant in many aquatic environments, e.g., in the epiphytic communities on macroalgae surfaces. Here, we analyzed three different macroalgae from the North Sea and show that Planctomycetes is the most abundant bacterial phylum on the alga Fucus sp., while it represents a minor fraction of the surface-associated bacterial community of Ulva sp. and Laminaria sp. Especially dominant within the phylum Planctomycetes were Blastopirellula sp., followed by Rhodopirellula sp., Rubripirellula sp., as well as other Pirellulaceae and Lacipirellulaceae, but also members of the OM190 lineage. Motivated by the observed abundance, we isolated four novel planctomycetal strains to expand the collection of species available as axenic cultures since access to different strains is a prerequisite to investigate the success of planctomycetes in marine environments. The isolated strains constitute four novel species belonging to one novel and three previously described genera in the order Pirellulales, class Planctomycetia, phylum Planctomycetes.〈/jats:p〉

Description: The Kerguelen Plateau, southern Indian Ocean rises up 2000 m above the surrounding seafloor and hence forms an obstacle for the flow of the Antarctic Circumpolar Current (ACC) and the Antarctic Bottomwater (AABW). The ACC is strongly deviated in its flow towards the north. A branch of the AABW flows northwards along the eastern flank of the plateau and in its path is steered by several basement highs and William’s Ridge. Seismic data collected during RV Sonne cruise SO272 image sediment drifts shaped in the Labuan Basin, which document onset and variabilities in pathway and intensity of this AABW branch in relation to the development of the Antarctic ice sheet and tectonic processes, e.g., the opening of the Tasman gateway. The eastern flank of the Kerguelen shows strong erosion of the post-mid Eocene sequences. In places, the Paleocene/early Eocene sequences are also affected by thinning and erosion. A moat can be observed along the Kerguelen Plateau flank indicating the flowpath of the north setting AAWB branch. Sediment drifts and sediment waves are formed east of the moat. Similar features are observed at the inner, western flank of William’s Ridge thus outlining the recirculation of the AABW branch in the Labuan Basin. The chronological and spatial will be reconstructed via the analysis of those sedimentary structures to provide constraints on climate and ocean circulation variability.

Description: An increasing number of studies report on microplastics (MP) in nature and their interactions with microbial communities. Rivers, as major transport routes for MP into marine systems and as reservoirs for bacteria, are important focal points in understanding these interactions. This study aims to investigate MP as substrates for bacterial colonization and their potential to transport these communities from riverine to marine environments. This transport was simulated via a sequential incubation experiment, where 3 sample types, synthetic (HDPE, tyre wear) and natural (wood) particles, were enclosed in a cage and successively incubated at four sites, from freshwater (Weser estuary) to coastal seawater offshore (Helgoland, North Sea). After each incubation period, a subset of each particle type and surface waters were sampled and the cage moved to the subsequent site. A second cage was simultaneously incubated at the offshore site for the entire period. Bacterial communities differed significantly between sample types at each site and across the salinity gradient. Communities detected on HDPE were the most diverse, while those on tyre wear were the least. Percentage similarities between sample types were low overall while similarities within each type decreased across the salinity gradient. Of the total detected ASVs, only 0.7 % were successively found on HDPE across all sites, none of which were detected on HDPE from the second cage offshore. Our results show an almost complete turnover of bacterial communities on MP transported from riverine to marine systems

Description: Modern digital scientific workflows - often implying Big Data challenges - require data infrastructures and innovative data science methods across disciplines and technologies. Diverse activities within and outside HGF deal with these challenges, on all levels. The series of Data Science Symposia fosters knowledge exchange and collaboration in the Earth and Environment research community. We invited contributions to the overarching topics of data management, data science and data infrastructures. The series of Data Science Symposia is a joint initiative by the three Helmholtz Centers HZG, AWI and GEOMAR Organization: Hela Mehrtens and Daniela Henkel (GEOMAR)

Description: Pelagic chlorophyll-a concentrations are key for evaluation of the environmental status and productivity of marine systems, and data can be provided by in situ measurements, remote sensing and modelling. However, modelling chlorophyll-a is not trivial due to its nonlinear dynamics and complexity. In this study, chlorophyll-a concentrations for the Helgoland Roads time series were modeled using a number of measured water and environmental parameters. We chose three common machine learning algorithms from the literature: the support vector machine regressor, neural networks multi-layer perceptron regressor and random forest regressor. Results showed that the support vector machine regressor slightly outperformed other models. The evaluation with a test dataset and verification with an independent validation dataset for chlorophyll-a concentrations showed a good generalization capacity, evaluated by the root mean squared errors of less than 1 µg L−1. Feature selection and engineering are important and improved the models significantly, as measured in performance, improving the adjusted R2 by a minimum of 48%. We tested SARIMA in comparison and found that the univariate nature of SARIMA does not allow for better results than the machine learning models. Additionally, the computer processing time needed was much higher (prohibitive) for SARIMA. Keywords: time series regression; artificial intelligence; Helgoland Roads time series; support vector machine; multi-layer perceptron; random forest; productivity; SARIMA

Description: The sediment succession of Lake Emanda in the Yana Highlands was investigated to reconstruct the regional late Quaternary climate and environmental history. Hydro‐acoustic data obtained during a field campaign in 2017 show laminated sediments in the north‐western and deepest (up to ̃15 m) part of the lake, where a ̃6‐m‐long sediment core (Co1412) was retrieved. The sediment core was studied with a multi‐proxy approach including sedimentological and geochemical analyses. The chronology of Co1412 is based on 14C AMS dating on plant fragments from the upper 4.65 m and by extrapolation suggests a basal age of c. 57 cal. ka BP. Pronounced changes in the proxy data indicate that early Marine Isotope Stage (MIS) 3 was characterized by unstable environmental conditions associated with short‐term temperature and/or precipitation variations. This interval was followed by progressively colder and likely drier conditions during mid‐MIS 3. A lake‐level decline between 32.0 and 19.1 cal. ka BP was presumably related to increased continentality and dry conditions peaking during the Last Glacial Maximum (LGM). A subsequent rise in lake level could accordingly have been the result of increased rainfall, probably in combination with seasonally high meltwater input. A milder or wetter Lateglacial climate increased lake productivity and vegetation growth, the latter stabilizing the catchment and reducing clastic input into the lake. The Bølling‐Allerød warming, Younger Dryas cooling and Holocene Thermal Maximum (HTM) are indicated by distinct changes in the environment around Lake Emanda. Unstable, but similar‐to‐present‐day climatic and environmental conditions have persisted since c. 5 cal. ka BP. The results emphasize the highly continental setting of the study site and therefore suggest that the climate at Lake Emanda was predominantly controlled by changes in summer insolation, global sea level, and the extent of ice sheets over Eurasia, which influenced atmospheric circulation patterns.

Description: The fate of infrastructure in the Arctic is heavily depending on the stability of frozen ground which it is built on. Climate change and consequent degradation of permafrost will negatively affect various infrastructure types and can cause ultimate failure. Comprehensive pan-Arctic assessments are urgently needed to better quantify environmental, economic and societal risks and to help adaptation planning. The use of physical models can be a powerful tool for risk evaluation, but modelling challenges remain with respect to resolving construction details at infrastructure scales together with decadal-scale climate change impacts. Here we used the dynamic permafrost land-surface model CryoGrid3 to capture both - the effects from the interaction of small-scale infrastructure with permafrost and large-scale climate change effects evolving in the 21century under an extensive warming scenario. We discuss how infrastructure can affect ground temperatures, and how climate change increases the risk of future infrastructure failure. We modelled two exemplary cases of permafrost-affected infrastructure: a gravel road on continuous permafrost at Prudhoe Bay (Alaska), and the case of a diesel tank facility at Norilsk (Siberia) placed on permafrost already subject to degradation under present day climate. We use the latter example to discuss environmental risks from contamination of hazardous legacy waste stored on and in permafrostand discuss the urgency for near-term policy strategies.

Description: Foraminifera are a group of mostly marine protists with high taxonomic diversity. Species identification is often complex, as both morphological and molecular approaches can be challenging due to a lack of unique characters and reference sequences. An integrative approach combining state of the art morphological and molecular tools is therefore promising. In this study, we analysed large benthic Foraminifera of the genus Amphisorus from Western Australia and Indonesia. Based on previous findings on high morphological variability observed in the Soritidae and the discontinuous distribution of Amphisorus along the coast of western Australia, we expected to find multiple morphologically and genetically unique Amphisorus types. In order to gain detailed insights into the diversity of Amphisorus, we applied micro CT scanning and shotgun metagenomic sequencing. We identified four distinct morphotypes of Amphisorus, two each in Australia and Indonesia, and showed that each morphotype is a distinct genotype. Furthermore, metagenomics revealed the presence of three dinoflagellate symbiont clades. The most common symbiont was Fugacium Fr5, and we could show that its genotypes were mostly specific to Amphisorus morphotypes. Finally, we assembled the microbial taxa associated with the two Western Australian morphotypes, and analysed their microbial community composition. Even though each Amphisorus morphotype harboured distinct bacterial communities, sampling location had a stronger influence on bacterial community composition, and we infer that the prokaryotic community is primarily shaped by the microhabitat rather than host identity. The integrated approach combining analyses of host morphology and genetics, dinoflagellate symbionts, and associated microbes leads to the conclusion that we identified distinct, yet undescribed taxa of Amphisorus. We argue that the combination of morphological and molecular methods provides unprecedented insights into the diversity of foraminifera, which paves the way for a deeper understanding of their biodiversity, and facilitates future taxonomic and ecological work.

Description: Die Ziele der vorliegenden Bachelorarbeit waren die Messung und Auswertung des Sauerstoffverbrauchs und der ATP-Produktion in isolierten Mitochondrien und permeabilisierten Herzfasern von polaren Fischen. Mitochondrien entstanden gemäß der Endosymbiontentheorie aus der Aufnahme eines, zur Reduktion von Sauerstoff befähigten, Proteobakteriums durch eine eukaryotische Zelle (Barbour, 2014 und Purves, 2011). An diese Reaktion wurde im Laufe der Evolution die Synthese von ATP gekoppelt (Purves, 2011). Die Körpertemperatur von ektothermen Organismen ist direkt von der Habitatstemperatur abhängig und die Temperatur ist einer der wichtigsten abiotischen Umweltfaktoren (Lucassen et al., 2003, Wehner und Gehring, 2013). Da die Geschwindigkeit enzymatischer Prozesse von der Temperatur abhängig ist, RGT-Regel, sollten bei B. saida bei 5 °C der Sauerstoffverbrauch und die ATP-Produktion niedriger als bei S. salar und D. labrax sein. Dazu wurden bei dem Polardorsch Boreogadus saida, sowie bei dem atlantischen Lachs Salmo salar und dem europäischen Wolfsbarsch Dicentrarchus labrax mit polarographischen Sauerstoffsensoren und optischen fluorometrischen Sensoren der Sauerstoffverbrauch und die ATP-Produktion gemessen. Der Sauerstoffverbrauch wurde mittels eines Substrate-Uncoupler-Inhibitor-Titration-Protokolls und die ATP-Produktion mit dem Fluoreszenzfarbstoff Magnesium Green gemessen (Iftikar und Hickey, 2013).

Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Carrier, T. J., Beaulieu, S. E., Mills, S. W., Mullineaux, L. S., & Reitzel, A. M. Larvae of deep-sea invertebrates harbor low-diversity bacterial communities. Biological Bulletin, 241(1), (2021): 65–76, https://doi.org/10.1086/715669.

Description: Microbial symbionts are a common life-history character of marine invertebrates and their developmental stages. Communities of bacteria that associate with the eggs, embryos, and larvae of coastal marine invertebrates tend to be species specific and correlate with aspects of host biology and ecology. The richness of bacteria associated with the developmental stages of coastal marine invertebrates spans four orders of magnitude, from single mutualists to thousands of unique taxa. This understanding stems predominately from the developmental stages of coastal species. If they are broadly representative of marine invertebrates, then we may expect deep-sea species to associate with bacterial communities that are similar in diversity. To test this, we used amplicon sequencing to profile the bacterial communities of invertebrate larvae from multiple taxonomic groups (annelids, molluscs, crustaceans) collected from 2500 to 3670 m in depth in near-bottom waters near hydrothermal vents in 3 different regions of the Pacific Ocean (the East Pacific Rise, the Mariana Back-Arc, and the Pescadero Basin). We find that larvae of deep-sea invertebrates associate with low-diversity bacterial communities (~30 bacterial taxa) that lack specificity between taxonomic groups. The diversity of these communities is estimated to be ~7.9 times lower than that of coastal invertebrate larvae, but this result depends on the taxonomic group. Associating with a low-diversity community may imply that deep-sea invertebrate larvae do not have a strong reliance on a microbiome and that the hypothesized lack of symbiotic contributions would differ from expectations for larvae of coastal marine invertebrates.

Description: TJC was supported by a National Science Foundation (NSF) Graduate Research Fellowship; SEB, SWM, and LSM were supported by NSF (OCE-0424953, OCE-1028862, and OCE-1829773) and the Dalio Explore Fund; and AMR was supported by the Human Frontier Science Program Award RGY0079/2016.

Description: Dataset: Deep-sea larvae for microbiome study

Description: This dataset provides the sampling locations and identifications for larvae collected near three deep-sea hydrothermal vent fields and used in a microbiome study by Carrier et al. (2021). This dataset provides metadata for larval and microbiome genetic sequence data in another repository (Carrier et al., 2021, doi.org/10.5061/dryad.sqv9s4n18). The data table is structured as a Darwin Core occurrence table so that it can be harvested by the Ocean Biodiversity Information System (OBIS) and Global Biodiversity Information Facility (GBIF). In addition to the data table, photographs are provided for some of the specimens. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/839476

Description: NSF Division of Ocean Sciences (NSF OCE) OCE-0424953, NSF Division of Ocean Sciences (NSF OCE) OCE-1028862, NSF Division of Ocean Sciences (NSF OCE) OCE-1829773, NSF Division of Ocean Sciences (NSF OCE) DEB-1558904

Description: The sustainable management of water resources is required to avoid water scarcity becoming widespread. This article explores the potential application of a social-ecological framework, used predominantly in the fields of ecology and conservation, as a tool to improve the sustainability and resilience of water resources. The "red-loop green-loop" (RL-GL) model has previously been used to map both sustainable and unsustainable social-ecological feedbacks between ecosystems and their communities in countries such as Sweden and Jamaica. In this article, we demonstrate the novel application of the RL-GL framework to water resources management using the 2017/18 Cape Town water crisis. We used the framework to analyse the social-ecological dynamics of pre-crisis and planned contingency scenarios. We found that the water resources management system was almost solely reliant on a single, non-ecosystem form of infrastructure, the provincial dam system. As prolonged drought impacted this key water resource, resilience to resource collapse was shown to be low and a missing feedback between the water resource and the Cape Town community was highlighted. The collapse of water resources ("Day Zero") was averted through a combination of government and community group led measures, incorporating both local ecosystem (green-loop) and non-local ecosystem (red-loop) forms of water resource management, and increased rainfall returning to the area. Additional disaster management plans proposed by the municipality included the tighter integration of red and green-loop water management approaches, which acted to foster a stronger connection between the Cape Town community and their water resources. We advocate the wider development and application of the RL-GL model, theoretically and empirically, to investigate missing feedbacks between water resources and their communities.

Description: Despite an increasing understanding of the issue of marine pollution, humanity continues on a largely unsustainable trajectory. This study aimed to identify and classify the range of scientific studies and interventions to address coastal and marine pollution. We reviewed 2417 scientific papers published between 2000 and 2018, 741 of which we analysed in depth. To classify pollution interventions, we applied the systems-oriented concept of leverage points, which focuses on places to intervene in complex systems to bring about systemic change. We found that pollution is largely studied as a technical problem and fewer studies engage with pollution as a systemic social-ecological issue. While recognising the importance of technical solutions, we highlight the need to focus on under-researched areas pertaining to the deeper drivers of pollution (e.g. institutions, values) which are needed to fundamentally alter system trajectories.

Description: Taxonomy as a science has accumulated data and knowledge for more than 250 years. The quality and usefulness of the facts recorded in taxonomic literature has greatly improved from the early descriptive texts to the modern data-rich, hypothesis-driven works. Our work illustrates the application of some of the \xe2\x80\x9ce-taxonomic\xe2\x80\x9d tools and the \xe2\x80\x9cNew Taxonomy\xe2\x80\x9d thinking explored in the introduction. Here, we analyzed specimen data contained in legacy taxonomic literature in Chapters 2 and 3\xe2\x80\x94to observe species distribution of one spider group and genital evolution, respectively\xe2\x80\x94and also explored an integrative perspective that involves describing new taxa and testing phylogenetic hypotheses using molecular and morphological data, as done in Chapter 4 and 5.

Description: New data on 52 non-indigenous mollusks in the Eastern Mediterranean Sea is reported. Fossarus sp. (aff. aptus sensu Blatterer 2019), Coriophora lessepsiana Albano, Bakker & Sabelli, sp. nov., Cerithiopsis sp. aff. pulvis, Joculator problematicus Albano & Steger, sp. nov., Cerithiopsis sp., Elachisina sp., Iravadia aff. elongata, Vitrinella aff. Vitrinella sp. 1 (sensu Blatterer 2019), Melanella orientalis, Parvioris aff. dilecta, Odostomia cf. dalli, Oscilla virginiae, Parthenina cossmanni, Parthenina typica, Pyrgulina craticulata, Turbonilla funiculata, Cylichna collyra, Musculus coenobitus, Musculus aff. viridulus, Chavania erythraea, Scintilla cf. violescens, Iacra seychellarum and Corbula erythraeensis are new records for the Mediterranean. An unidentified gastropod, Skeneidae indet., Triphora sp., Hypermastus sp., Sticteulima sp., Vitreolina cf. philippi, Odostomia (s.l.) sp. 1, Henrya (?) sp., and Semelidae sp. are further potential new non-indigenous species although their status should be confirmed upon final taxonomic assessment. Additionally, the status of Dikoleps micalii, Hemiliostraca clandestina comb. nov. and H. athenamariae comb. nov. is changed to non-indigenous, range extensions for nine species and the occurrence of living individuals for species previously recorded from empty shells only are reported. Opimaphora blattereri Albano, Bakker & Sabelli, sp. nov. is described from the Red Sea for comparison with the morphologically similar C. lessepsiana Albano, Bakker & Sabelli, sp. nov. The taxonomic part is followed by a discussion on how intensive fieldwork and cooperation among institutions and individuals enabled such a massive report, and how the poor taxonomic knowledge of the Indo-Pacific fauna hampers non-indigenous species detection and identification. Finally, the hypothesis that the simultaneous analysis of quantitative benthic death assemblages can support the assignment of non-indigenous status to taxonomically undetermined species is discussed.

Description: Freshwater is an important resource, but at a great risk of species decline due to habitat loss, pollution and over-exploitation, and invasive alien species. European and national regulation dictate the monitoring of freshwater quality in the Water Framework Directive. The biological elements of these assessments focus on the organisms living in freshwater systems, such as fish, macroinvertebrates, and plants. Traditional monitoring of quality relies on labor-intensive and expensive collection and morphological identification of specimens. Recent developments in molecular techniques allow for easier identification through (meta)barcoding and species detection using environmental DNA (eDNA). This thesis explores the possibilities to integrate genetic tools into freshwater quality monitoring and impact assessments, by investigating the ability of DNA-based methods to approximate morphologically determined species occurrences and the influence of their abundance on quality ratios. Additionally, it examines the effects of replication strategies in eDNA sampling, and studies the implications of using eDNA monitoring across several trophic levels of the ecosystem in impact assessments. Combined with a growing body of literature, the findings in this thesis illustrate that molecular techniques will contribute to a better ecosystem understanding and allow for more effective monitoring and management of freshwater systems, safeguarding the ecosystem services provided to humankind.

Description: Cystoliths are large outgrowths of cell wall material and calcium carbonate with a silicon-containing stalk \nfound in the leaves, stems and roots of only a handful of plant families. Each cystolith is contained within a cell \ncalled a lithocyst. In leaves, lithocysts may be found in the mesophyll or the epidermis. Astudy by Koch et al. (2009) \nreported unique, indented features on the surface of superamphiphilic Ruellia devosiana (Acanthaceae) leaves \nwhich the authors named \xe2\x80\x98channel cells\xe2\x80\x99. We report herein that such \xe2\x80\x98channel cells\xe2\x80\x99 in the Acanthaceae are actually lithocysts containing fully formed cystoliths in which only a portion of the lithocyst is exposed at the epidermis, \nforming a leaf epidermal impression. Intact leaves and isolated cystoliths from 28 Acanthaceae species (five in the \nnon-cystolith clade and 23 in the cystolith clade) were examined using light and scanning electron microscopy and \nX-ray microanalysis. All 23 members of the cystolith clade examined contained cystoliths within lithocysts, but not \nall showed leaf epidermal impressions. In four species, the lithocysts were in the leaf mesophyll, did not contact \nthe leaf surface, and did not participate in leaf epidermal impression formation. The remaining 19 species had \nlithocysts in the epidermis and possessed leaf epidermal impressions of differing sizes, depths and morphologies

Description: Captive breeding programmes in zoological institutions can \nbe important tools for conservation. Lemurs are popular zoo \nanimals and are present in hundreds of zoos outside of Madagascar. \nBut are captive lemur populations integrated into exsitu \nconservation efforts? Are lemur species in zoos chosen \nbecause of their conservation value, popular appeal, or some \nother considerations? Here, we address these questions, focusing \non zoological institutions of the European Association \nof Zoos and Aquaria (EAZA) network. We assess whether \nlemur species presence in EAZA zoos is linked to taxonomy, \nInternational Union for the Conservation of Nature (IUCN) \nthreat category and/or biological traits (body mass and diet). \nWe find that a total of 22 of 109 lemur species are currently \nkept in EAZA zoos (July 2021). Our results show that some \nspecies (e.g. Lemur catta, Varecia variegata) and genera (e.g. \nEulemur) are over-represented in zoos, whereas some species- \nrich genera are poorly represented (Microcebus) or not \nrepresented at all (Lepilemur). Body mass and diet are strong \nindicators of presence in captivity, with larger or frugivorous \nspecies overrepresented, and small or folivorous species underrepresented. \nA total of 15 species are currently bred under \ncollaborative European ex-situ programmes. There is no \nlink between severity of IUCN status and species presence \nin zoos, and endangered or critically endangered species are \nnot more likely to be found in captivity. These results suggest \nthat species in EAZA zoos have predominantly been chosen \ndue to their appeal to the public, ease of husbandry or other \npractical and administrative constraints, rather than based on \npotential benefits for conservation. Addressing the imbalance \nbetween the EAZA\xe2\x80\x99s current collection of captive lemur species \nand the lemur species of conservation priority would \nlead to better representation of the threatened biodiversity \nof lemurs under active ex-situ population management, potentially \nacting as a failsafe against extinction.

Description: Biological type specimens are a particular kind of voucher specimen stored in natural history collections. Their special status and practical use are discussed in relation to the description and naming of taxonomic zoological diversity. Our current system, known as Linnaean nomenclature, is governed by the International Code of Zoological Nomenclature. The name of a species is fixed by its name-bearing type specimen, linking the scientific name of a species to the type specimen first designated for that species. The name-bearing type specimen is not necessarily a typical example of the species, while establishment of the boundaries of a species requires empirical taxonomic studies. The International Code of Zoological Nomenclature allows for the naming of new species in the absence of preserved specimens. However, photos and DNA sequences should not function as primary type material, while new species should not be described and named without deposition of at least one type specimen in a collection. Philosophically, species are individuals, spatiotemporally restricted entities. Therefore, Linnaean species names are proper names, which do not define the taxon but serve as a label, providing an ostensive definition of a species. Paratypes have no name-bearing function but, nevertheless, are highly valued specimens in natural history collections. Paratypes should be restricted to those specimens originating from the same sample as the holotype. Diagnosis of a species taxon involves establishment of a connection between a Linnaean name and determination of the boundaries of the species. A first step in this process is the choice of an appropriate species concept. It is not the examination of holotypes and paratypes that necessarily provides the best estimate of the taxonomic boundaries of a species, but this is facilitated by a set of voucher specimens known as the hypodigm. Dissatisfaction with the present nomenclatural code led some researchers to propose emendations. Other taxonomists suggested abandoning Linnaean nomenclature and proposed the alternative PhyloCode, albeit that it relegates the naming of species taxa to the traditional nomenclatural codes.

Description: Dissolved oceanic CO2 concentrations are rising as result of increasing atmospheric partial pressure of CO2 (pCO2), which has large consequences for phytoplankton. To test how higher CO2 availability affects different traits of the toxic dinoflagellate Alexandrium ostenfeldii, we exposed three strains of the same population to 400 and 1,000 µatm CO2, and measured traits including growth rate, cell volume, elemental composition, 13C fractionation, toxin content, and volatile organic compounds (VOCs). Strains largely increased their growth rates and particulate organic carbon and nitrogen production with higher pCO2 and showed significant changes in their VOC profile. One strain showed a significant decrease in both PSP and cyclic imine content and thereby in cellular toxicity. Fractionation against 13C increased in response to elevated pCO2, which may point towards enhanced CO2 acquisition and/or a downscaling of the carbon concentrating mechanisms. Besides consistent responses in some traits, other traits showed large variation in both direction and strength of responses towards elevated pCO2. The observed intraspecific variation in phenotypic plasticity of important functional traits within the same population may help A. ostenfeldii to negate the effects of immediate environmental fluctuations and allow populations to adapt more quickly to changing environments.

Description: Kelps, the marine forest foundation species, are threatened by ocean warming at their warm distributional edges. To mechanistically investigate inheritance of thermal traits, we assessed thermal tolerance of inbred (selfings) and outbred (crosses) sporophytes of the N-Atlantic kelp Laminaria digitata among isolates from the genetically distinct populations of Helgoland (North Sea) and Spitsbergen (Arctic). First, we investigated the upper thermal tolerance of microscopic sporophytes in a 14-day experiment applying 20–23°C. The upper survival temperature was lower for the Spitsbergen selfing (21°C) than for the Helgoland selfing and the reciprocal crosses (22°C). We then subjected 4–7 cm long sporophytes to a control temperature (10°C), moderate (19°C) and sub-lethal heat stress (20.5°C) to assess metabolic regulation via whole-transcriptome analysis in addition to physiological parameters. Growth and optimum quantum yield decreased similarly in both crosses and the Helgoland selfing at 19 and 20.5°C, while inbred Spitsbergen sporophytes died within seven days at both 19 and 20.5°C. At 10°C, the Spitsbergen selfing showed the highest differential gene expression. Considering only the three surviving lineages at 20.5°C, differential gene expression was 61–78% lower in the crosses compared to the Helgoland selfing, including reduced expression of transcripts related to cellular stress responses. This implies that both intraspecific crosses maintained a growth response similar to the Helgoland selfing with reduced metabolic regulation during sublethal heat stress, indicating subtle heterosis (hybrid vigour) as a beneficial effect of outbreeding. Results are discussed in the frame of mariculture and marine forest restoration.

Description: Located 10° further north than any sponge ground yet reported, the population, primarily comprising Geodia parva, G. hentscheli and Stelletta rhaphidiophora individuals, covers the great majority of the Langseth Ridge from ∼1,000 m upward, to a shallowest peak of 580 m depth, at very high abundance1. Sizes of individual sponges varied, with a median diameter of 17 cm (± 0.10 cm SE, n = 10,839, and IQR 11–25 cm); the maximum diameter observed was 110 cm and the smallest were just over 1 cm. This size range equates to a median wet weight of 1.4 kg (± 0.12 kg SE, n = 10,839; IQR 0.4–5 kg; Figure S1). Sponges are opportunistic feeders; although they efficiently retain particulates by filter feeding, dissolved organic matter in seawater often represents the main food source2. The low productivity and nutrient fluxes that characterize this region — due to high latitude, permanent sea ice cover, and distance from land — raise the question of how this abundant biomass is maintained. We analyzed the many trails of interwoven spicules across the seamount peaks. Trails were observed to be several centimeters in height and up to meters in length, often connected directly to living sponges. These trails were particularly visible in areas of low sponge density, that is, where trails crossed bedrock in areas sparsely covered by sediments or organic debris (Figure 1A–E and Video S1). Spicule trails in areas of denser sponge aggregation exhibited a higher vertical thickness than observed elsewhere (Figures 1F and S1A, and Video S1). Our observations also suggest that the spicule trails correlated with the distribution of smaller juvenile sponges (Figure S1A).

Description: Goniodomin A (GDA, 1) is a phycotoxin produced by at least four species of Alexandrium dinoflagellates that are found globally in brackish estuaries and lagoons. It is a linear polyketide with six oxygen heterocyclic rings that is cyclized into a macrocyclic structure via lactone formation. Two of the oxygen heterocycles in 1 comprise a spiro-bis-pyran, whereas goniodomin B (GDB) contains a 2,7-dioxabicyclo[3.3.1]nonane ring system fused to a pyran. When H2O is present, 1 undergoes facile conversion to isomer GDB and to an α,β-unsaturated ketone, goniodomin C (GDC, 7). GDB and GDC can be formed from GDA by cleavage of the spiro-bis-pyran ring system. GDA, but not GDB or GDC, forms a crown ether-type complex with K+. Equilibration of GDA with GDB and GDC is observed in the presence of H+ and of Na+, but the equilibrated mixtures revert to GDA upon addition of K+. Structural differences have been found between the K+ and Na+ complexes. The association of GDA with K+ is strong, while that with Na+ is weak. The K+ complex has a compact, well-defined structure, whereas Na+ complexes are an ill-defined mixture of species. Analyses of in vitro A. monilatum and A. hiranoi cultures indicate that only GDA is present in the cells; GDB and GDC appear to be postharvest transformation products.

Description: Freshening of the oceans is a predicted outcome of climate change. Marine phytoplankton organisms are in general affected by salinity changes and, given their key role in oceanic food webs and geochemical cycles, it is important to investigate the response of phytoplankton species to salinity changes. Diatom species of the genus Pseudo-nitzschia can form massive and, at times, toxic blooms, because several Pseudo-nitzschia species produce the neurotoxin domoic acid. Domoic acid can cause amnesic shellfish poisoning in humans and harm animals in the marine food web. The species Pseudonitzschia seriata can produce domoic acid in cold-water areas, like the Arctic. Hence, it is relevant to investigate the response of P. seriata to different salinity levels. Three strains of P. seriata were exposed to four different salinity levels (15, 20, 30 and 40). None of the strains grew at salinity 15, and maximum growth rates were found at salinity 30. All three strains contained toxins at salinities 20–40, with the highest cellular content occurring at salinity 20. The peak in toxin content was related to a significantly lower growth rate. However, the higher toxin content overrode the lower growth rate, ultimately resulting in a higher toxin potential at salinity 20. In addition to domoic acid, all strains contained isodomoic acid C in surprisingly high amounts, similar to the domoic acid content.

Description: The biochemical composition and fluorescence properties of DOM were assessed in relation to phytoplankton and major aquatic bacterial clades in a regenerative area of the Argentine Shelf. DOM was mainly of autochthonous biological origin, containing humic- and protein-like substances of medium degree of unsaturation and diagenesis. Biochemical-DOM accounted for 25% of total DOC, being dissolved combined amino acids (DCAA) the dominant fraction followed by free carbohydrates. Phytoplankton was the main source of serine, alanine, and valine, and particulate carbohydrates. Gammaproteobacteria abundance correlated negatively with ammonium and positively with DCAA, suggesting a coupling between ammonium consumption and refractory amino acid production. A preferential utilization of alanine, leucine and threonine as nitrogen source was inferred from the distribution of Cytophaga-Flavobacteria-Bacteroidete in relation with dissolved free amino acids (DFAA). Notably, Alpha- and Betaproteobacteria correlated with the large pool (75%) of chemically unidentified DOC and not with DCAA or dissolved combined carbohydrates. Particularly, Alphaproteobacteria (∼40% of EUB total heterotrophic bacteria) either significantly contribute to the production of the “humic”, refractory fraction of marine DOM, or the latter impairs resource control on their abundance. Spatial heterogeneity inherent to coastal-shelf areas drives important regional variability in the biochemical properties of DOM.

Description: It is well known that modern resting cysts with morphologies matching those of species of the fossil genus Spiniferites germinate into motile cells of the genus Gonyaulax. Different Spiniferites species have been connected to a single Gonyaulax species, raising the question of whether they are over-classified. Through germination experiments of cysts with the morphological features of four species of Spiniferites, viz. S. bentorii, S. hyperacanthus, S. ramosus and S. scabratus, we established cyst-theca relationships. Cysts with the morphology of S. bentorii gave rise to vegetative, motile cells of Gonyaulax nezaniae sp. nov., which is characterized by two stout antapical spines. Cysts with S. hyperacanthus and S. ramosus morphologies germinated into Gonyaulax whaseongensis and G. spinifera, respectively. Cysts with S. scabratus morphology lacked a ventral pore and were attributed to Gonyaulax cf. spinifera. Gene sequences for SSU, LSU and/or ITS-5.8S rRNA were obtained from these four species, and from cysts with the morphology of Spiniferites belerius, S. mirabilis, S. lazus, Spiniferites cf. bentorii and Tectatodinium pellitum. The maximum likelihood and Bayesian inference analyses based on LSU and SSU rRNA gene sequences revealed that cysts assignable to Spiniferites formed a polyphyletic group, intermingled with Tectatodinium, Bitectatodinium, Ataxiodinium and Impagidinium, whereas Gonyaulax species appeared as monophyletic. From our results we inferred the phylogenetic positions of S. bentorii, S. mirabilis, S. lazus, S. scabratus, Tectatodinium pellitum and Gonyaulax digitale for the first time, supporting the idea that Spiniferites species are not over-classified and each of them may correspond to different Gonyaulax species.

Description: Naturally occurring neurotoxins belonging to two structurally distinct groups of guanidinium alkaloids known collectively as saxitoxins (STXs) and tetrodotoxins (TTXs) share a high affinity and ion flux blockage capacity for voltage-gated sodium ion channels (NaV). Both toxin groups are produced by marine microorganisms and widely distributed among vector species in the oceans, but are also found in terrestrial species. The STXs are often referred to as paralytic shellfish toxins (PSTs) based on their accumulation in shellfish and the symptoms in humans after consumption of toxic seafood. Biosynthesis of STXs is confirmed in four genera of marine dinoflagellates and among about a dozen species of primarily freshwater and brackish water strains of filamentous cyanobacteria. The origin of the STX biosynthetic genes in dinoflagellates remains controversial and may represent multiple horizontal gene transfer (HGT) events from progenitor bacteria and/or cyanobacteria. The recent identification of the biosynthetic genes for STX analogs in both cyanobacteria and dinoflagellates has yielded insights into mechanisms of toxin heterogeneity among species and the evolutionary origins of the respective elements of the toxin gene cluster. The biogenic origins of TTXs and tetrodotoxicity remain even more enigmatic. The TTXs occur primarily in marine pufferfish species, and hence tetrodotoxicity is frequently described as pufferfish poisoning (PFP) after the toxin syndrome in human consumers of such toxic fish. In marine environments, TTXs also appear in invertebrate species, particularly of benthic feeders on suspended particulates and carnivorous vector species. Symbiotic colonizing bacteria or free-living bacteria sequestered via feeding from the water column or sediments are most often invoked as proximal sources of TTXs in marine macrofauna, but endogenous biosynthesis independent of bacteria cannot be excluded. The TTX biosynthetic pathway has not been completely elucidated, and the biosynthetic genes are unknown.

Description: The effects of climate change are projected to be most severe changes in Arctic environments. Warming has already caused various environmental changes, including a loss of almost 50% Arctic sea-ice coverage since the 1980s. Sea-ice loss strengthens summer stratification and, consequently, hypoxic zones in the deep-water layers may form. The deep fjord systems of the Svalbard archipelago are particularly at risk from this long-lasting stratification. Thus, the present study investigates the hypoxia tolerance in the Arctic key species Polar cod, Boreogadus saida. We measured respiratory capacity (standard, routine and maximum metabolic rates, SMR, RMR, MMR) and swim performance under progressive hypoxia (100% to 5% air saturation) via intermittent-flow and swim-tunnel respirometry. The calculated SMR for Polar cod accounted 0.44 µmol O2∙g-1∙h-1 at full oxygen saturation. RMR followed an oxygen regulating pattern and never fell below SMR until the fish lost equilibrium at about 3% O2 saturation. Under exercise, Polar cod were able to retain a steady MMR until a threshold of 45% PO2 was reached, after which MMR decreased linearily, reaching SMR at about 5% oxygen saturation. Ugait was not significantly affected by hypoxia, albeit the total number of anaerobic bursts and total active swimming time decreased significantly with progressive hypoxia. Despite the common paradigm that polar organisms are not hypoxia tolerant, our study revealed that Polar cod can handle very low oxygen saturations down to a Pcrit of 4.81% air saturation. The loss of anaerobic metabolic capacity under hypoxia however may endanger this species with regard to predator-prey-interactions and loss of escape-reactions.

Description: It is important to understand the historical precedents of current situations to be able to anticipate where the current global environmental and climatic change may lead. Geo-historical data provide information beyond the limitations of instrumental data. This study aims to reconstruct components of the palaeoclimatic and palaeoenvironmental history of the Beagle Channel (BC) during the Late Holocene by using Ameghinomya antiqua shells. We use fossil and modern shells in a comparative analysis through a multiproxy approach, i.e., shell morphometrics, shell growth, and stable oxygen isotope ratios. A holistic analysis of all the proxies indicates that higher productivity occurred around 3542 yr B.P. in the BC, evidenced by more significant growth, size, and longevity in fossil specimens. In addition, smaller ligaments, cardinal teeth, and the pallial sinus in fossil specimens indicate a low-energy environment typical of a marine archipelago. Lastly, palaeotemperatures are estimated to be warmer than today, although the intensity may be overestimated due to the freshwater inflow that would change the salinity of the BC waters. Further analysis in Late-Holocene shells is essential for a more detailed environmental reconstruction around the southern tip of South America.

Description: Gonyaulacales include a considerable number of harmful algae and to understand their origin and rise, knowledge of the evolutionary relationships is necessary. Many scientific names of protists introduced prior to the availability of DNA analytics are ambiguous and impede communication about biological species and their traits in the microbial world. Strains of Lingulodinium polyedra were established from its type locality in the Kiel Fjord (Germany) to clarify its taxonomy. Moreover, the phylogeny of Gonyaulacales was inferred based on 329 rRNA sequence accessions compiled in a curated sequence data base, with as much as possible type material equivalents included. Gonyaulacales were monophyletic and segregated into seven lineages at high systematic level, of which †Lingulodiniaceae constituted the first branch of the Gonyaulacales. Their type species had a plate formula APC (Po, X, cp), 3′ , 3a, 6′ ′ 6c, 6s, 6′ ′ ′ , 2′ ′ ′ ′ and is taxonomically clarified by epitypification. Recommendations for this important taxonomic tool are provided, with a focus on microorganisms. Most gonyaulacalean taxa established at generic rank are monophyletic, with Alexandrium, Coolia and Gonyaulax as notable exceptions. From an evolutionary perspective, gonyaulacalean dinophytes with quinqueform hypotheca are monophyletic and derive from a paraphyletic group showing the sexiform configuration.

Description: Harmful algal blooms (HAB) are recurrent phenomena in northern Europe along the coasts of the Baltic Sea, Kattegat-Skagerrak, eastern North Sea, Norwegian Sea and the Barents Sea. These HABs have caused occasional massive losses for the aquaculture industry and have chronically affected socioeconomic interests in several ways. This status review gives an overview of historical HAB events and summarises reports to the Harmful Algae Event Database from 1986 to the end of year 2019 and observations made in long term monitoring programmes of potentially harmful phytoplankton and of phycotoxins in bivalve shellfish. Major HAB taxa causing fish mortalities in the region include blooms of the prymnesiophyte Chrysochromulina leadbeateri in northern Norway in 1991 and 2019, resulting in huge economic losses for fish farmers. A bloom of the prymesiophyte Prymnesium polylepis (syn. Chrysochromulina polylepis) in the Kattegat-Skagerrak in 1988 was ecosystem disruptive. Blooms of the prymnesiophyte Phaeocystis spp. have caused accumulations of foam on beaches in the southwestern North Sea and Wadden Sea coasts and shellfish mortality has been linked to their occurrence. Mortality of shellfish linked to HAB events has been observed in estuarine waters associated with influx of water from the southern North Sea. The first bloom of the dictyochophyte genus Pseudochattonella was observed in 1998, and since then such blooms have been observed in high cell densities in spring causing fish mortalities some years. Dinoflagellates, primarily Dinophysis spp., intermittently yield concentrations of Diarrhetic Shellfish Toxins (DST) in blue mussels, Mytilus edulis, above regulatory limits along the coasts of Norway, Denmark and the Swedish west coast. On average, DST levels in shellfish have decreased along the Swedish and Norwegian Skagerrak coasts since approximately 2006, coinciding with a decrease in the cell abundance of D. acuta. Among dinoflagellates, Alexandrium species are the major source of Paralytic Shellfish Toxins (PST) in the region. PST concentrations above regulatory levels were rare in the Skagerrak-Kattegat during the three decadal review period, but frequent and often abundant findings of Alexandrium resting cysts in surface sediments indicate a high potential risk for blooms. PST levels often above regulatory limits along the west coast of Norway are associated with A. catenella (ribotype Group 1) as the main toxin producer. Other Alexandrium species, such as A. ostenfeldii and A. minutum, are capable of producing PST among some populations but are usually not associated with PSP events in the region. The cell abundance of A. pseudogonyaulax, a producer of the ichthyotoxin goniodomin (GD),has increased in the Skagerrak-Kattegat since 2010, and may constitute an emerging threat. The dinoflagellate Azadinium spp. have been unequivocally linked to the presence of azaspiracid toxins (AZT) responsible for Azaspiracid Shellfish Poisoning (AZP) in northern Europe. These toxins were detected in bivalve shellfish at concentrations above regulatory limits for the first time in Norway in blue mussels in 2005 and in Sweden in blue mussels and oysters (Ostrea edulis and Crassostrea gigas) in 2018. Certain members of the diatom genus Pseudonitzschia produce the neurotoxin domoic acid and analogs known as Amnesic Shellfish Toxins (AST). Blooms of Pseudo-nitzschia were common in the North Sea and the Skagerrak-Kattegat, but levels of AST in bivalve shellfish were rarely above regulatory limits during the review period. Summer cyanobacteria blooms in the Baltic Sea are a concern mainly for tourism by causing massive fouling of bathing water and beaches. Some of the cyanobacteria produce toxins, e.g. Nodularia spumigena producer of nodularin, which may be a human health problem and cause occasional dog mortalities. Coastal and shelf sea regions in northern Europe provide a key supply of seafood, socioeconomic well-being and ecosystem services. Increasing anthropogenic influence and climate change create environmental stressors causing shifts in the biogeography and intensity of HABs. Continued monitoring of HAB and phycotoxins and the operation of historical databases such as HAEDAT provide not only an ongoing status report but also provide a way to interpret causes and mechanisms of HABs.

Description: The IOC-ICES-PICES Harmful Algal Event Database (HAEDAT) was used to describe the diversity and spatiotemporal distribution of harmful algal events along the Atlantic margin of Europe from 1987 - 2018. The majority of events recorded are caused by Diarrhetic Shellfish Toxins (DSTs). These events are recorded annually over a wide geographic area from southern Spain to northern Scotland and Iceland, and are responsible for annual closures of many shellfish harvesting areas. The dominant causative dinoflagellates, members of the morphospecies ‘Dinophysis acuminata complex’ and D. acuta, are common in the waters of the majority of countries affected. There are regional differences in the causative species associated with PST events; the coasts of Spain and Portugal with the dinoflagellates Alexandrium minutum and Gymnodinium catenatum, north west France/south west England/south Ireland with A. minutum, and Scotland/Faroe Islands/Iceland with A. catenella. This can influence the duration and spatial scale of PST events as well as the toxicity of shellfish. The diatom Pseudo-nitzschia australis is the most widespread Domoic Acid (DA) producer, with records coming from Spain, Portugal, France, Ireland and the UK. Amnesic Shellfish Toxins (ASTs) have caused prolonged closures for the scallop fishing industry due to the slow depuration rate of DA. Amendments to EU shellfish hygiene regulations introduced between 2002 and 2005 facilitated end-product testing and sale of adductor muscle. This reduced the impact of ASTs on the scallop fishing industry and thus the number of recorded HAEDAT events. Azaspiracids (AZAs) are the most recent toxin group responsible for events to be characterised in the ICES area. Events associated with AZAs have a discrete distribution with the majority recorded along the west coast of Ireland. Ciguatera Poisoning (CP) has been an emerging issue in the Canary Islands and Madeira since 2004. The majority of aquaculture and wild fish mortality events are associated with blooms of the dinoflagellate Karenia mikimotoi and raphidophyte Heterosigma akashiwo. Such fish killing events occur infrequently yet can cause significant mortalities. Interannual variability was observed in the annual number of HAEDAT areas with events associated with individual shellfish toxin groups. HABs represent a continued risk for the aquaculture industry along the Atlantic margin of Europe and along the Atlantic margin of Europe and should be accounted for when considering expansion of the industry or operational shifts to offshore areas.

Description: Rapid warming in the Arctic is drastically impacting marine ecosystems, affecting species diversity, distribution, and food web structure. Pelagic Themisto amphipods are a dominant component of the Arctic zooplankton community and represent a key link between secondary producers and marine vertebrates at higher trophic levels. Two co-existing species dominate in the region: Themisto libellula, considered a true Arctic species and Themisto abyssorum, a sub-Arctic, boreal species. Both have exhibited recent changes in abundance and range shifts, likely due to the Atlantification of the Arctic. Many aspects of the ecology and genetic structure of these two species are not well studied, despite their high biomass, importance in the food web and the fact that they are already being affected by rapid climate change in the Arctic. We tested both species for levels of genetic diversity, patterns of spatial genetic structure and demographic history using samples from the Greenland shelf, Fram Strait, and Svalbard. This was achieved using variation at the mitochondrial cytochrome c oxidase subunit 1 gene (mtCOI). These data revealed strikingly different levels of mtCOI diversity: low levels in T. libellula contrasted with high diversity in T. abyssorum. No spatial genetic structure was found, and high levels of connectivity and evidence of historic demographic expansion were exhibited by both species. These patterns of diversity and demographic signatures are likely explained by glaciation events impacting population sizes during the LGM. High population connectivity is likely due to mixing among Themisto populations, caused by the multi-directional currents in the region. The observed low genetic diversity, in combination with its cold adaptions, could cause T. libellula to be more susceptible in the Atlantification of the Arctic. In contrast, high diversity likely increases adaptive potential in T. abyssorum which, combined with its Atlantic affinity, could lead to it benefitting from current warming trends. This study provides new data on the phylogeography of two ecologically important species, which can contribute to predicting how zooplankton communities, species interactions and food web structure will manifest in the Arctic as a result of climate change.

Description: The bacterial composition of permafrost samples taken during drilling of frozen marine sediments in the area of Barentsburg coal mine on the east coast of Grønfjord Bay of Western Spitsbergen has been studied. The study was based on the analysis of the V4 region of the 16S rRNA gene, carried out using next generation sequencing, as well as using classical microbiological methods (direct luminescence microscopy and aerobic cultivation).The total cell number in permafrost samples ranges from 6.73 ± 0.73 × 106 to 3.37 ± 0.19 107 cells per g. The number of cultivable aerobic bacteria in frozen samples on 1/5 TSA and R2A media ranges from 0 to 6.20 ± 0.45 × 104 CFU/g. Isolates of aerobic bacteria were identified by 16S rRNA gene analysis as representatives of the genera Arthrobacter, Pseudarthrobacter, Psychrobacter, and Rhodoferax. The dominant phyla of the domain Bacteria were Actinobacteria, Proteobacteria, Chloroflexi, Nitrospirae and Firmicutes. As a result of phylogenetic analysis of the dominant operational taxonomic units, representatives of methane oxidizing, sulfate reducing bacteria, as well as heterotrophic bacteria involved in the transformation of organic matter were found.

Description: The thermal state of the lithosphere and related geothermal heat flow (GHF) is a crucial parameter to understand a variety of processes related to cryospheric, geospheric, and/or biospheric interactions. Indirect estimates of GHF in polar regions from magnetic, seismological, or petrological data often show large discrepancies when compared to thermal in situ observations. Here, the lack of in situ data represents a fundamental limitation for both investigating thermal processes of the lithosphere and validating indirect heat flow estimates. During RV Polarstern expeditions PS86 and PS118, we obtained in situ thermal measurements and present the derived GHF in key regions, such as the Antarctic Peninsula and the Gakkel Ridge in the Arctic. By comparison with indirect models, our results indicate (1) elevated geothermal heat flow (75 ± 5 mW m−2 to 139 ± 26 mW m−2 ) to the west of the Antarctic Peninsula, which should be considered for future investigations of ice-sheet dynamics and the visco-elastic behavior of the crust. (2) The thermal signature of the Powell Basin characteristic for oceanic crust of an age between 32 and 18 Ma. Further, we propose (3) that at different heat sources at the slow-spreading Gakkel Ridge in the Aurora Vent Field region might explain the geothermal heat flow distribution. We conclude that in situ observations are urgently required to ground-truth and fine-tune existing models and that a multidisciplinary approach is of high importance for the scientific community’s understanding of this parameter.

Description: Between 30 May and 6 June 2019 a series of new eruptions occured in the south-east flanks of Mt. Etna, Italy, forming lava flows and explosive activity that was most intense during the first day of the eruption; as a result, volcanic particles were dispersed towards Greece. Lidar measurements performed at the PANhellenic GEophysical observatory of Antikythera (PANGEA) of the National Observatory of Athens (NOA), in Greece, reveal the presence of particles of volcanic origin above the area the days following the eruption. FLEXible PARTicle dispersion model (FLEXPART) simulations and satellite-based SO2 observations from the TROPOspheric Monitoring Instrument onboard the Sentinel-5 Precursor (TROPOMI/S5P), confirm the volcanic plume transport from Etna towards PANGEA and possible mixing with co-existing desert dust particles. Lidar and modeled values are in agreement and the derived sulfate mass concentration is approximately 15 g/m3. This is the first time that Etna volcanic products are monitored at Antikythera station, in Greece with implications for the investigation of their role in the Mediterranean weather and climate.

Description: Published

Description: 40

Description: 5V. Processi eruttivi e post-eruttivi

Description: JCR Journal

Description: This paper was written by a group of European researchers believing that now is the right time to frame the Space Weather and Space Climate discipline in Europe for future years. It is devoted to openly discussing the organisation and sustainability of the European Space Weather community and its assets in the (near) future. More specifically, we suggest that the European Space Weather community lacks a uniting organisation to help the community to sustain and develop the successful efforts made thus far. Our aim is not to draw a complete and exhaustive panorama of Space Weather throughout the world, nor even throughout Europe. It is not a new white paper on the science and applications: there exist many (e.g. Tsurutani BT et al. 2020. Nonlinear Processes Geophys 27(1): 75–119); nor another roadmap: several important have been published recently (e.g. Schrijver CJ et al. 2015. Adv Space Res 55(12): 2745– 2807; Opgenoorth HJ et al. 2019. J Space Weather Space Clim 9: A37). Our aim is to question our practices and organisation in front of several changes that have occurred in the recent years and to set the ground to provide coordinated answers to these questions being posed in Europe, and to make these answers discussed throughout the world. This group was assembled first through a series of sessions devoted to the sustainability of Space Weather research during the European Space Weather Week (ESWW) series of meetings, specifically: ESWW 14 (2017), ESWW 15 (2018), and ESWW 16 (2019). It then grew from discussions and personal contacts.

Description: Published

Description: 26

Description: 2A. Fisica dell'alta atmosfera

Description: JCR Journal

Description: 〈jats:title〉Abstract〈/jats:title〉〈jats:p〉Firn describes the interstage product between snow and ice in cold regions of the earth, where annual snow fall exceeds the amount of snow melting. The continuing accumulation of snow leads to its densificiation due to overburden stress until it becomes ice. In the field of glaciology various attempts on simulating firn densification have been made and new models are still developed, as the knowledge of the firn column's density structure allows important derivations.〈/jats:p〉〈jats:p〉The presented study reassesses a model description for low density firn based on the process of grain boundary sliding presented by Alley in 1987 [1] using an optimisation approach. By comparing simulation results to 159 measured firn density profiles from Greenland and Antarctica it finds a possible additional dependency of the constitutive relation on the mean surface mass balance. This result is interpreted as an insufficient description of the stress regime.〈/jats:p〉

Description: 〈jats:title〉Abstract〈/jats:title〉〈jats:p〉In cold regions of the earth, like Antarctica, Greenland or mountains at high altitude, the annual amount of deposited snow exceeds the amount of snow melting. Snow, which is more than one year old, is called firn. Over time firn transforms into ice by a sintering process, mainly driven by overburden pressure and temperature. This ultimately leads to the formation of glaciers and ice sheets.〈/jats:p〉〈jats:p〉We simulate firn densification based on the processes of sintering. The constitutive law represents grain boundary sliding, dislocation creep and diffusion. These mechanisms sum up to the overall densification which leads to the transformation of snow to ice. The model aims at obtaining a physics driven simulation tool for firn densification which provides data for a wider range of areas. It will contribute to develop better models and better understanding of the cryosphere.〈/jats:p〉

Description: 42 pages

Description: In this study, we propose an analysis of the earthquake clusters that occurred in North-Eastern Italy and western Slovenia from 1977 to today. Given a mainshock generating alarm in the population, we are interested in forecasting if a similar magnitude earthquake will follow. We classify the earthquake clusters associated with mainshocks of magnitude Mm into two classes: if the strongest aftershock has a magnitude 〉=Mm-1 (swarms or large aftershock seismic sequences) as type A, otherwise (smaller aftershocks seismic sequences) as type B. A large aftershock following a main shock can cause significant damages to already weakened buildings and infrastructures, so a timely advisory information to the civil protection is of great interest for effective decision-making. For the first time, we applied to a new catalogue a pattern recognition algorithm for cluster type forecasting that we developed for all Italy (Gentili and Di Giovambattista, 2017). Thanks to the lower completeness magnitude of the local OGS catalogue, compared to the national one, and to a new version of the algorithm, we were able to lower the threshold of the clusters mainshocks magnitude from 4.5 to 3.7. The method has been validated by rigorous statistical tests. We tested the algorithm on the 1976 highly destructive earthquake cluster (mainshock magnitude 6.5 - the strongest in the last 80 years in the region) and we retrospectively forecasted it as an A cluster. Successful results were obtained also on other three smaller earthquake clusters in 2019.

Description: Published

Description: 106483

Description: 4T. Sismicità dell'Italia

Description: 6T. Studi di pericolosità sismica e da maremoto

Description: JCR Journal

Description: The knowledge of the secular variation of the geomagnetic field at different time scales is important to determine the mechanisms that maintain the geomagnetic field and can help to establish constraints in dynamo theories. We have focused our study on the secular variation at millennial and centennial time scale searching for characteristic periods during the last 10 kyr. The frequency study was performed using four recent updated global paleomagnetic field reconstructions (SHA.DIF.14k, CALS10k.2, BIGMUDI4k and SHAWQ2k) by applying three techniques commonly used in signal analysis: the Fourier transform, the Empirical Mode Decomposition, and the wavelet analysis. Short-term variability of the geomagnetic field energy shows recurrent periods of around 2000, 1000–1400, and 600–800 and 250–400 years. The characteristic time around 600–800 years is well determined in all paleomagnetic reconstructions and it is mostly related to the axial dipole and axial octupole terms, but also observable in the equatorial dipole. In addition to this period, longer characteristic times of around 1000–1400 years are found particularly in the equatorial dipole and quadrupole terms in SHA.DIF.14k, CALS10k.2 and BIGMUDI4k while the 2000 year period is only well determined in the total geomagnetic field energy of SHA.DIF.14k and CALS10k.2. The most detailed paleoreconstructions for younger times also detect shortest characteristic times of around 250–400 years. The long-term variation of the geomagnetic energy is only observable in the axial dipole. A characteristic period of around 7000 years in both SHA.DIF.14k and CALS10k.2 has been found. This long period is related to two decays in the dipole field and a period of increasing intensity. The oldest decay took place between 7000 BCE and 4500 BCE and the present decay that started around 100 BCE. We have modeled the 4500 BCE up to present variation as a combination of a continuous decay, representing the diffusion term of the geomagnetic field, and one pulse that reinforces the strength of the field. Results show a characteristic diffusion time of around 11,000–15,000 years, which is compatible with the diffusion times of the dipole field used in geodynamo theories.

Description: Published

Description: 106656

Description: 1A. Geomagnetismo e Paleomagnetismo

Description: JCR Journal

Description: Abstract: Muon radiography is a technique based on the measurement of absorption profiles of muons as they pass through matter. This measurement allows to obtain an image of the inner structure of large volume objects and is suitable to be applied in several fields, such as volcanology, archaeology and civil engeneering. One of the main applications concerns the study of volcanic structures; indeed it is possible to use this technique to measure the mass distribution inside the edifice of a volcano providing useful information to better understand the possible eruption mechanisms. The MURAVES (MUon RAdiography of VESuvius) project aims to the study of the summital cone of Mt. Vesuvius near Naples in Italy, one of the most dangerous active volcanoes in the world. The MURAVES apparatus is a modular, robust muon hodoscope system with a low power consumption, optimized to be used in inhospitable environments like the surroundings of volcanoes. The complete detection system is an array of identical tracking modules, each with an area of 1 m2 , based on the use of plasic scintillators. The technologies, the status and the data analysis strategy of the experiment will be presented in this paper.

Description: Published

Description: C03014

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: JCR Journal

Description: The Larderello-Travale Geothermal Field in South-West Tuscany (Italy) is the oldest and among the most pro- ductive geothermal fields in the world. A new 3D model of seismic P-wave velocity (V P ) of the upper crust beneath the geothermal field is derived by inverting a set of highly consistent travel-times from local-earth- quakes. Results document a marked correlation of V P with previously described, high-reflectivity horizons. We also determined a low velocity body (V P ∼5 km s −1 ) culminating at depths of about 7 km, with estimated vo- lume of 35–40 km 3 . Such low velocities are consistent with a granite at temperatures above 700 °C, thus in a partially-molten status.

Description: Published

Description: 101731

Description: 1T. Struttura della Terra

Description: JCR Journal

Description: 〈jats:title〉Abstract〈/jats:title〉 〈jats:p〉Devastation associated with tsunamis is well known on the global scale. Flank collapse at volcanic islands is among the mechanisms triggering tsunamis, but very few examples document interaction between landslides and volcanic activity. The study of three well-preserved medieval tsunami deposits recently discovered along the coast of Stromboli volcano (Aeolian Islands, southern Italy) enabled a detailed characterization of the tsunami sequences intercalated with volcaniclastic deposits and primary tephra and allowed reconstruction of the likely sequence of volcanic events. In one case, a violent explosion possibly preceded the tsunami, whereas in the youngest event, the lateral collapse of the volcano flank triggered a tsunami wave that was rapidly followed by sustained explosive magmatic activity and ensuing prolonged ash venting. The hypothesized tsunami-triggering dynamics suggests a close link between volcanic activity and flank collapse, further confirming that the persistent activity at Stromboli makes the volcano particularly susceptible to tsunami generation.〈/jats:p〉

Description: Published

Description: 436-440

Description: 1V. Storia eruttiva

Description: JCR Journal

Description: Numerous sand boils were generated in the alluvial plain at the mouth of the Rio Brice˜no valley (Ecuador) during the Mw 7.8 earthquake of April 2016. The area is characterized by a series of raised marine terraces formed as a consequence of the rapid tectonic coastal uplift during the Quaternary. Boreholes and geotechnical investigations were carried during post-earthquake surveys and for the purpose of mitigating the liquefaction effects. Five lithological units were identified at a site of embankment, which represented continental-marine and transitional sedimentation since the Last Glacial Maximum. A comprehensive study of texture and petrographic composition of sand boils has been performed and compared with sandy silts and silty sands of the buried sedimentary sequence in order to identify the source levels for liquefaction. The petrographic components, in particular the low content of bioclasts and carbonate fragments of the sand boils, allow to pinpoint a source layer made up of fine-grained silty sands located between 2 and 4.5 m depth (Unit 2) whereas the deeper marine sands, richer in bioclasts, were not involved. The results support the idea that earthquake-induced liquefaction phenomena are not restricted to clean sands and well-sorted deposits, but may affect sand layers with significant amount of nonplastic silt.

Description: Published

Description: 102737

Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica

Description: JCR Journal

Description: The Campi Flegrei caldera (Italy) has been undergoing unrest over the past five decades including episodes of rapid ground deformation, seismicity, and variations in gas emissions. Hydrothermal fluids and gases are released most vigorously in the central sector of the caldera at the fumarolic fields of Solfatara volcano and Pisciarelli. We conducted a high‐precision gravity survey coupledwith inverse modeling to image the shallow (〈2‐km depth) structure of the hydrothermal feeder system. Results indicate the presence of three low density bodies beneath Pozzuoli, Astroni volcano and the Solfatara/Pisciarelli fumarolic fields. The first two are inferred to be sealed hydrothermal systems trapped beneath impermeable cap rock, while the latter depicts a plume‐like geothermal feeder system reaching the surface via a combination of Solfatara's maar‐diatreme structure and the intersection of NW‐SE and NE‐SW trending regional faults. The density contrasts of the reservoirs from background values are best explained by a multiphase mixture of caldera fill containing a secondary and interconnected void volume fraction of between 0.2 and 0.3 that hosts a vapor volume fraction ψv of between 0.38 and 1 and a liquid volume fraction ψl fraction of between 0 and 0.62. This work highlights the control of volcano‐tectonic structures on fluid movement in the shallow crust of hydrothermally active volcanic systems undergoing sustained or periodic unrest.

Description: Published

Description: e2019JB019231

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: JCR Journal

Description: Improving the knowledge of the seismic history of a region plays a key role in the evaluation of recurrence relations for probabilistic seismic hazard analyses. In this study we present the results of an investigation carried out in two local historical archives in NE Sicily, Italy. Several letters, petitions, and reports describing the effects of some earthquakes that occurred between the 17th and the 18th centuries in the Gulf of Patti area were found and analyzed. This contributed to filling the knowledge gap about a series of moderate-to-large seismic events that were overshadowed by catastrophic earthquakes with major impact both on human losses and cultural heritage damages. We describe this experience in the hope that other historians will take up the work, looking for other NE Sicily local archives to investigate because we believe this is the right way toward a better definition of the seismic history of one of the most seismically active regions of Italy.

Description: INGV Sezione di Milano

Description: Published

Description: 1011–1025

Description: 4T. Sismicità dell'Italia

Description: JCR Journal

Description: Terrestrial laser scanning (TLS) and drone-based structure-from-motion (SfM) photogrammetry allowed the study of soil de formations due to blast-induced liquefaction during an experiment carried out on 4 June 2018. The research aimed at both evaluating the measurement quality and estimating the rammed aggregate piers (RAPs) effectiveness in mitigating the effects of soil liquefaction. These effects mainly consist of subsidence and deposits of ejected and extruded materials. The comparison between multitemporal 3D models provided surface variation maps and volume changes. In addition, classical topographical leveling allowed the measurement of subsurface vertical displacement along a specific cross section. The results pointed out a significant reduction, higher than 50% of soil deformation in areas improved by RAPs installation; moreover, the corresponding volume variations were no more than about 37% of those occurred in the not improved area. Finally, a critical comparison between remote sensing and leveling suggested that surface variation maps could under-estimate the area lowering up to 15% in this kind of terrain.

Description: Published

Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica

Description: JCR Journal

Description: In Portugal, particularly in the greater Lisbon area, there are widespread alluvial sandy deposits, which need to be carefully assessed in terms of liquefaction susceptibility and risk zonation. For this purpose, a pilot site has been set up, as part of the European H2020 LIQUEFACT project. An extensive database of geological and geotechnical reports was collected and a comprehensive site investigation campaign was carried out, including boreholes with standard penetration (SPT), piezocone penetrometer and seismic dilatometer tests as well as geophysical methods, complemented by undisturbed soil sampling for laboratory characterisation. The assessment of liquefaction susceptibility based on field tests was made using the simplified procedure, considering the factor of safety against liquefaction ( FSliq), which relates the cyclic resistance ratio (CRR) with the cyclic stress ratio (CSR). While the computation of the CSR is relatively straightforward, the reliability of the CRR strongly depends on the adopted in situ testing technique. Alternative approaches to liquefaction assessment have been proposed, based on quantitative liquefaction damage indexes, namely the Liquefaction Potential Index (LPI) and Liquefaction Severity Number. In this paper, the geotechnical field data is integrated in these distinct approaches to liquefaction assessment. A comparative and in-depth analysis of the conventional approach is presented and the inclusion of specific information on soil type, as a means to overcome the observed differences, is discussed particularly for SPT and VS results. The combination of these criteria enabled to clearly identify the most critical layers, in terms of liquefaction potential and severity.

Description: Published

Description: 109-138

Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica

Description: JCR Journal

Description: In fall 2018, we have observed, by means of an underground ring laser gyroscope, the microseismic (MS) activity induced by the Mediterranean Sea in the 2–5 s period range. In the amplitude spectra, a clear peak highly correlated with a collocated seismometer appears during a large storm activity ranging from 24 November to 1 December 2018. The peak of the spectra, both for rotation rate and acceleration, are located at 3.3 s. The peak amplitudes are of 8×10−10  rad/s−1 and 3×10−6  ms−2⁠, respectively, for vertical rotation rate and horizontal acceleration. We perform the source direction estimation by maximizing the correlation of the vertical rotation rate with the transverse acceleration. The local estimation of the direction of the wavefield is then compared with the sea state hindcasts that provide a modeling of the possible MS noise sources.

Description: Published

Description: 1730–1737

Description: 7A. Geofisica per il monitoraggio ambientale

Description: JCR Journal

Description: In Antarctica, the near-source exposures of volcanic eruption deposits are often limited as they are not well preserved in the dynamic glacial environment, thus making volcanological reconstructions of explosive eruptions extremely challenging. Fortunately, pyroclastic deposits from explosive eruptions are preserved in Southern Ocean sediments surrounding Antarctica, and the tephrostratigraphy of these sequences offers crucial volcanological information including the timing and tempo of past eruptions, their magnitude, and eruption dynamics. Here we report the results of a tephrostratigraphy and tephrochronology study focused on four sediment cores recovered from the Wood Bay area in the western Ross Sea, Antarctica. In all these sedimentary sequences, we found a well-stratified primary tephra of considerable thickness, up to 80 cm, hereafter named the Aviator Tephra (AVT). According to the characteristics of the tephra deposit and its distribution, the AVT was associated with an eruption of considerable intensity, potentially representing one of the largest Holocene eruptions recorded in Antarctica. Based on the major and trace element geochemistry and the mineral assemblage of the tephra, Mount Rittmann was identified as the source of the AVT. A Holocene age of ∼11 ka was determined by radiocarbon dating organic material within the sediments and 40Ar-39Ar dating of alkali-feldspar crystals included in the tephra. Eruption dynamics were initially dominated by hydromagmatic magma fragmentation conditions producing a sustained, relatively wet and ash-rich eruptive cloud. The eruption then evolved into a highly energetic, relatively dry magmatic Plinian eruption. The last phase was characterized by renewed efficient magma-water interaction and/or collapse of the eruptive column producing pyroclastic density currents and associated co-ignimbritic plumes. The distal tephra deposits might be linked to the widespread lag breccia layer previously identified on the rim of the Mount Rittmann caldera which share the same geochemical composition. Diatoms found in the sediments surrounding the AVT and the primary characteristics of the tephra indicate that the Wood Bay area was open sea at the time of the eruption, which is much earlier than previously thought. AVT is also an excellent tephrostratigraphic marker for the Wood Bay area, in the Ross Sea, and a useful marker for future synchronization of continental ice and marine archives in the region.

Description: Published

Description: 106629

Description: 1V. Storia eruttiva

Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici

Description: 1A. Geomagnetismo e Paleomagnetismo

Description: 5A. Ricerche polari e paleoclima

Description: JCR Journal

Description: Over the last decade machine learning has become increasingly popular for the analysis and characterization of volcano-seismic data. One of the requirements for the application of machine learning methods to the problem of classifying seismic time series is the availability of a training dataset; that is a suite of reference signals, with known classification used for initial validation of the machine outcome. Here, we present PICOSS (Python Interface for the Classification of Seismic Signals), a modular data-curator platform for volcano-seismic data analysis, including detection, segmentation and classification. PICOSS has exportability and standardization at its core; users can select automatic or manual workflows to select and label seismic data from a comprehensive suite of tools, including deep neural networks. The modular implementation of PICOSS includes a portable and intuitive graphical user interface to facilitate essential data labelling tasks for large-scale volcano seismic studies.

Description: Published

Description: 104531

Description: 8T. Sismologia in tempo reale

Description: JCR Journal

Description: The Planch´on – Peteroa Volcanic Complex exhibits two active degassing areas: Peteroa crater, PC, and peripheral hydrothermal areas, analyzed in three sampling sites, namely Valle Ba˜nos del Azufre, VBA, Valle del Pe˜n´on, VP and Valle Valenzuela, VZ. This prospective study was designed to investigate the soil diffuse emissions of CO2 at this volcanic complex. The survey consisted of 560 measurements of CO2 soil diffuse flux and temperature carried out at PC, VBA, VP. The results of this work show that diffuse CO2 is emitted at PC through two welldefined diffuse degassing structures and flux distribution that can be modeled by combining two log-normal populations. Here, the main source of soil CO2 is a shallow aquifer recharged by steam condensation and meteoric fluids that interact with rising magmatic gases. The carbon isotopic signature reveals that CO2 diffuse degassing is affected by secondary soil processes during its ascent. The total diffuse CO2 output at the surveyed area of PC, which covers ̴77,000 m2 around the crater fumarolic field, is 6.49 ± 0.32 t d􀀀 1. Soil diffuse emissions at the hydrothermal peripheral sites, VBA and VP, were studied covering a total area of 5̴ 90,000 m2. These emissions are characterized by poorly defined diffuse degassing structures and flux distributions that can be modeled by combining three log-normal populations, which suggest that multiple sources feed CO2 diffuse emissions. In concordance, the isotopic analysis also suggests a mixed source of CO2 and degassing affected by secondary processes that modify the original isotope composition. CO2 soil degassing at VZ shows a clear relation with the vegetated areas of the soil. The minimum endogenous CO2 output estimation here proposed for the Plancho´n – Peteroa Volcanic Complex is that of PC, 6̴ .5 t d􀀀 1. The thermal energy release was computed for PC, and the estimation is 2.57 ± 0.53 MW.

Description: Published

Description: 102930

Description: 4V. Processi pre-eruttivi

Description: JCR Journal

Description: In volcanic areas, accurate localization of earthquakes requires detailed velocity and, possibly, attenuation models, taking into account wide lithological variability and high geothermal gradients. Ischia island (Campania region, Italy) is a seismically-active volcano recently affected by a Mw 3.9 event (Casamicciola, August 21, 2017, 1 km depth). Due to the lack of a specific velocity model, the earthquakes occurred on the island were localized using the one developed for the nearby Campi Flegrei caldera. The aim of this work is the definition of a mean representative 1D shear-wave velocity (Vs) and attenuation (Q) model of the shallower crust (up to 2 km depth) of Ischia. Seismic noise array and spectral ratios techniques were applied to broad band seismic signals recorded by temporary and permanent networks updated after the August 2017 earthquake. The values of both shear-wave velocity (Vs) and quality factor (Q) are realistic, with Q values comparable with those obtained for Campi Flegrei and Stromboli volcanic areas. By taking into account stratigraphic information from deep wells and ultrasonic measurements of velocity on granite and trachytic lava samples, a geological interpretation of the resulting velocity model is provided. Such a model can have significant implications for understanding the dynamics of a volcano, mainly those leading to seismic activity.

Description: Published

Description: 106970

Description: 1T. Struttura della Terra

Description: JCR Journal

Description: Study of the climate in the Mediterranean basin during different historical periods has taken on a particular importance, particularly regarding its role (together with other factors) in the evolution of human settlement patterns. Although the Roman age is traditionally considered a period with a favourable climate, recent studies have revealed considerable complexity in terms of regional climate variations. In this paper, we compare the hydrological change from speleothem proxy records with flood reconstructions from archaeological sites for Northern Tuscany (central Italy). We identify a period of oscillating climatic conditions culminating in a multidecadal dry event during the 1st century BC, followed by a century of increased precipitation at the beginning of the Roman Empire and subsequently a return to drier conditions in the 2nd century AD. The period of rainfall increase documented by the speleothems agrees with both the archaeological flood record as well as historical flood data available for the Tiber River, ca. 300 km to the south. These data also suggest a return to wetter conditions following the 3nd and 4rd centuries AD.

Description: Published

Description: 791-802

Description: 5A. Ricerche polari e paleoclima

Description: JCR Journal

Description: It has been recently proposed DeVito [(2019) On the meaning of Fermi's paradox. Futures, 389–414] that a minimal number of contacts with alien radio-communicative civilizations could be justified by their logarithmically slow rate of growth in the Galaxy. Here we further develop this approach to the Fermi paradox, with the purpose of expanding the ensemble of the possible styles of growth that are consistent with the hypothesis of a minimal number of contacts. Generalizing the approach in DeVito (2019), we show that a logarithmic style of growth is still found. We also find that a style of growth following a power law would be admissible, however characterized by an exponent less than one, hence describing a sublinear increase in the number of communicative civilizations, still qualitatively in agreement with DeVito (2019). No solutions are found indicating a superlinear increase in the number of communicative civilizations, following for example an exponentially diverging law, which would cause, in the long run, an unsustainable proliferation. Although largely speculative, our findings corroborate the idea that a sublinear rate of increase in the number of communicative civilizations in the Galaxy could constitute a further resolution of Fermi paradox, implying a constant and minimal – but not zero – number of contacts.

Description: Published

Description: 314-319

Description: 1TR. Georisorse

Description: JCR Journal