ALBERT

Description: The seismic-electromagnetic phenomenon entails the generation of transient electromagnetic signals, which can be observed both simultaneously (co-seismic) and preceding (pre-seismic) a seismic wave arrival. Following the most accredited hypothesis, these signals are mainly due to electrokinetic effects, generated on microscopic scale in porous media containing electrolytic fluids. Thus, the seismic-electromagnetic signals are expected to be suitable for the detection and tracking of crustal fluids. Despite the growing interest in this phenomenon, there is a lack of freely available observational database of earthquake-related electromagnetic signals recorded at co-located seismic and magnetotelluric stations. To fill this gap, we set up two multicomponent monitoring stations in two seismically active areas of Southern Italy: the Gargano Promontory and the High Agri Valley. This work is both aimed to systematically analyse earthquake-generated seismic-electromagnetic recordings and to make the collected database accessible to the scientific community.

Description: Published

Description: 863-872

Description: JCR Journal

Description: The North Sea Basin has been covered by ice sheets originating from both the British Isles and Scandinavia at multiple times during the Pleistocene. The Witch Ground Basin (WGB) in the central northern North Sea is a critical location in terms of interpreting Late Pleistocene glacial to glacimarine history of the North Sea since it was the location of the Witch Ground Ice Stream that was active on multiple occasions during the Mid to Late Pleistocene. We map five mega‐scale glacial lineation flowsets corresponding to the changing ice flow direction of the Witch Ground Ice Stream and investigate the sedimentological fingerprint and corresponding subglacial depositional processes of this palaeo‐ice stream. We show that sorted sand layers within a subglacial traction till represent periodic hydraulic jacking and ice–bed decoupling at the base of the Witch Ground Ice Stream. In contrast to previous studies that have described glacitectonites deposited below the most recent grounded ice in the WGB, we present analysis of sediment cores that recovered primarily massive diamictons without any obvious deformation structures. The most recent ice cover in the WGB (~18–16 ka) was thought to have been sourced from a localized ice cap over Orkney and Shetland. The presence of chalk clasts sourced from NW of the WGB described in this study from the stratigraphically youngest till confirms this interpretation. The transition from subglacial to glacimarine deposition, while acoustically well defined (from opaque to laminated acoustic units), appears surprisingly uniform in the recovered sediment cores, but can be differentiated based on a change in colour including mottling and banding, presence of whole intact shells, and the increased number of silt and sand lenses. 14 C dating of glacimarine muds indicate high sedimentation rates of between 80 and 260 cm ka −1 . The transition from glacimarine to marine deposition is represented by a comparative decrease in sedimentation rate and deposition of Holocene age sandy mud. This study demonstrates a highly dynamic Witch Ground Ice Stream in the northern North Sea during the Late Pleistocene with evolving subglacial hydrology and depositional processes at the ice stream bed that left a distinct geomorphological and sedimentological fingerprint within the WGB.

Description: Discharge of calved ice, runoff and mixing driven by subglacial discharge plumes likely have consequences for marine biogeochemistry in Disko Bay, which hosts the largest glacier in the northern hemisphere, Sermeq Kujalleq. Glacier retreat and increasing runoff may impact the marine silica cycle because glaciers deliver elevated concentrations of dissolved silica (dSi) compared to other macronutrients. However, the annual flux of dSi delivered to the ocean from the Greenland Ice Sheet is poorly constrained because of difficulties distinguishing the overlapping influence of different dSi sources. Here we constrain silica dynamics around Disko Bay, including the Ilulissat Icefjord and four other regions receiving glacier runoff with contrasting levels of productivity and turbidity. Both dissolved silica and Si* ([dSi]‐[NO x − ]) concentrations indicated conservative dynamics in two fjords with runoff from land‐terminating glaciers, consistent with the results of mixing experiments. In three fjords with marine‐terminating glaciers, macronutrient‐salinity distributions were strongly affected by entrainment of nutrients in subglacial discharge plumes. Entrainment of dSi from saline waters explained 93 ± 51% of the dSi enrichment in the outflowing plume from Ilulissat Icefjord, whereas the direct contribution of freshwater to dSi in the plume was likely 0%–3%. Whilst not distinguished herein, other minor regional dSi sources include icebergs and dissolution of amorphous silica (aSi) in either pelagic or benthic environments. Our results suggest that runoff around Greenland is supplemented as a dSi source by minor fluxes of 0.25 ± 0.67 Gmol yr −1 dSi from icebergs and ∼1.9 Gmol year −1 from pelagic aSi dissolution. Plain Language Summary Silica is one nutrient required by marine phytoplankton, specifically siliceous microalgae such as diatoms. Glacier runoff delivers higher concentrations of silica into the ocean compared to other nutrients such as nitrate or phosphate. Changes in the cryosphere, such as glacier retreat and increasing ice discharge or runoff, may therefore have downstream ecological effects due to shifts in the availability, and ratios, of nutrients. However, the magnitude of dissolved silica fluxes into the ocean from the present day Greenland Ice Sheet has proven challenging to determine, with two existing estimates varying by an order of magnitude. This is because of uncertainties in how to disentangle the overlapping influence of different dSi sources. Here, we conducted a detailed survey of the Disko Bay region in west Greenland, including inshore and offshore dSi measurements, to assess how the chemistry of dSi changes in estuaries. In order to further understand estuarine dSi dynamics, we conducted incubation experiments at sea and in the laboratory. Our results reduce uncertainty in the magnitude of dSi supplied to the ocean from Greenland's glaciers and suggest a modest dSi flux from runoff with small additional fluxes from melting icebergs and dSi release from suspended particles. Key Points Both runoff and entrainment in subglacial discharge plumes influence estuarine nutrient dynamics around Disko Bay Entrainment from saline waters explains 93 ± 51% of dSi enrichment in the Ilulissat Icefjord outflow, freshwater 〈3% We estimate 0.25 and ∼1.9 Gmol yr −1 dSi fluxes from Greenland's icebergs and pelagic aSi dissolution, respectively

Description: Winter dissolved nickel (dNi) and particulate nickel (pNi) concentrations were measured in the Southern Ocean (GEOTRACES GIpr07 transect) to investigate biogeochemical cycling within the water column and over seasonal timescales. Concentrations of dNi ranged from 1.98 to 8.21 nmol kg −1 with low surface concentrations and maxima in deepest sampled water masses. Combining our winter data with the GEOTRACES Intermediate Data Product (2021) shows insignificant seasonal dNi variation in surface waters north of the Antarctic Polar Front, indicating the dominance of year‐round mixing processes. However, lower summer concentrations than winter in the Antarctic Zone (∆0.23 nmol kg −1 ) suggest a role for biological processes at high latitudes. For pNi, concentrations ranged from 5 to 49 pmol kg −1 with higher values in surface/near‐surface water masses. Vertical attenuation factors ( b values) for pNi (0.19 ± 0.06) and particulate phosphorus (pP; 0.43 ± 0.10) suggest a greater retention of Ni in particles than P, invoking scavenging processes or refractory Ni phases. Water mass analysis shows that remineralization of pNi contributes a maximum of 6% of the highest measured dNi. Instead, dNi distributions and macronutrient relationships were largely explained by phytoplankton uptake in surface waters, and mixing and advection of Atlantic and Antarctic origin water masses, each with different preformed nutrient compositions. Winter trace metal measurements provide new perspectives regarding the balance between biological and physical drivers in the Southern Ocean. For Ni, the biological component is small with respect to physical mixing processes and over the timescales in which water masses accumulate Ni during their transport. Plain Language Summary Nickel is a nutrient for marine organisms like phytoplankton, which form the base of the marine food web, and are important for globally relevant processes such as carbon cycling. In the ocean, nickel can be dissolved in seawater or associated with particles of diverse compositions. Measuring these nickel forms helps to understand the processes responsible for its distribution throughout the ocean. However, most measurements are from the summer, biasing our understanding toward conditions which favor phytoplankton growth. We therefore measured dissolved and particle‐associated nickel in the Southern Ocean during winter to investigate nickel variability over seasonal timescales, and estimate the relative importance of biological and physical processes. Comparing our winter nickel data to existing summer data in the Southern Ocean, we found significantly higher winter concentrations in surface waters at high latitudes (50–60°S), indicating decreased biological utilization of nickel compared to summer. The resupply of Ni from the breakdown of particles was found to be relatively small in comparison to the nickel transported by the water masses making up the Southern Ocean circulation. As a result, physical water mass mixing processes play a more significant role than biological processes in determining nickel distributions in the Southern Ocean. Key Points Higher winter dissolved nickel in the Antarctic Zone surface mixed layer due to decreased biological uptake compared to summer Ni is retained in the particle phase longer than phosphorus, which impacts their different depth profiles in the Southern Ocean Remineralization of particle‐associated nickel is an insignificant source of dissolved nickel compared to the supply from physical mixing

Description: Community trait variability can arise from the species, genotypic, or individual plastic level. Trait changes on these levels can occur simultaneously, interact, and potentially translate to community functioning. Thus, they are crucial to realistically predict community functional changes. Using a phytoplankton model community comprising a diatom and a coccolithophore each with nine genotypes varying in cell size, we conducted a selection experiment over 130 generations towards nutrient availability. According to our expectations, mean community cell size and total biomass increased with increasing nutrient availability. Interspecifically, these community level changes were driven by shifts in species composition towards the larger diatom. Changes caused by intraspecific shifts did not result from sorting according to genotypes' standing variation in cell size in the first place. Instead, intraspecific changes likely resulted from the selection for a highly plastic diatom genotype, which led to a phenotypic distribution with larger cells in high and smaller cells in lower nutrient concentrations. We suggest that besides interspecific species sorting, the evolution of size plasticity through genotype selection represented an intraspecific contribution to mean community size increase with increasing nutrient availability that ultimately translated to increased total biomass. Our results demonstrate that all three levels on which trait changes can occur, regulate phytoplankton community-level functional changes and thus should be considered when predicting community change on ecological time scales.

Description: Dimethyl sulphide (DMS) and methanethiol (MeSH) emissions from South Pacific surface seawater were determined in deck board Air‐Sea Interface Tanks during the Sea2Cloud voyage in March 2020. The measured fluxes from water to headspace (F) varied with water mass type, with lowest fluxes observed with Subtropical and Subantarctic waters and highest fluxes from Frontal waters. Measured DMS fluxes were consistent with fluxes calculated using a two‐layer model and seawater DMS concentrations. The MeSH:DMS flux ratio was 11%–18% across the three water mass types, confirming that MeSH may represent a significant unaccounted contribution to the atmospheric sulfur budget, with potentially important implications for marine aerosol formation and growth in models. Combining data from the ASITs and ambient surface seawater identified significant Spearman rank correlations for both dissolved DMS and MeSH with nanophytoplankton cell abundance ( p value 〈 0.012), suggesting an important role for this phytoplankton size class in determining regional DMS and MeSH emissions. Applying a nanophytoplankton‐based parameterization to estimate DMS w provided good agreement with a recent DMS climatology. Consequently, the observed relationship between DMS w , MeSH w and nanophytoplankton cell abundances may be applicable for modeling atmospheric fluxes. Plain Language Summary In March 2020, researchers conducted experiments during the Sea2Cloud voyage east of New Zealand in which they measured the emissions of the climate relevant gases dimethyl sulphide (DMS) and methanethiol (MeSH). These sulfur gases are produced by marine microorganisms and their emissions were measured in tanks containing different sea water types. Lowest emissions were observed in Subtropical and Subantarctic waters while the highest were in Frontal waters where Subantarctic and Subtropical seawaters meet and support large phytoplankton blooms. While DMS has been extensively studied, there are far fewer measurements of MeSH which this study confirmed be a significant, relatively constantly scaled to DMS and previously underestimated contributor to atmospheric sulfur levels with potential implications for climate. The study established significant correlations between DMS and MeSH fluxes and nanophytoplankton cell abundance, highlighting the importance of this phytoplankton size class in marine emissions to the atmosphere. The results presented here can help constrain emissions of these sulfur gases in climate models. Key Points Ratio of methanethiol (MeSH) to dimethyl sulphide (DMS) fluxes of 11%–18% is consistent across different water types in Southern Ocean waters Significant correlations between DMS w and MeSH w and nanophytoplankton were observed, enabling development of parameterizations for models

Description: The rupture behavior of large oceanic strike-slip earthquakes remains largely unresolved using seismic signals recorded thousands of kilometers away from the source area. Large submarine earthquakes, however, generate hydroacoustic T-waves propagating through the ocean over long distances. Here, we show that these T-waves recorded at regional distances on the Ascension hydrophone array of the International Monitoring System can provide critical information on the earthquake location and rupture behavior. We use recordings from 47 events in oceanic transform faults, ranging in magnitude from 5.6 ≤ Mw ≤ 7.1, to investigate the rupture processes. We find that most strike-slip earthquakes show unilateral rupture behavior, while a few larger events were more complex. Furthermore, earthquakes in oceanic transforms have longer ruptures than events of the same magnitude in continental faults. We argue that differences in the scaling relation of oceanic and continental strike-slip earthquakes support a lower rigidity in the oceanic lithosphere caused by hydration. Key Points Hydroacoustic T-waves from 47 oceanic transform fault earthquakes with Mw 5.6–7.1 were recorded by the IMS Ascension hydrophone array Our results show that hydroacoustic energy provides precise constraints on the rupture of strong earthquakes in oceanic transform faults Ruptures of oceanic strike-slip earthquakes are longer than for continental events of the same magnitude, indicating lower rigidity Plain Language Summary Oceanic transform faults are strike-slip faults where one plate moves past another laterally, with new seafloor created at adjacent mid-ocean ridge segments on either side of the transform. At the transforms, plate motion generates strong earthquakes, causing seismic waves to propagate for thousands of kilometers. Nevertheless, due to their remoteness the rupture behavior of oceanic earthquakes and their scaling relationship between magnitude and rupture length is poorly constrained and understood. Here, we use hydroacoustic signals, so-called T-waves, which are excited by seismic deformation of the seafloor. T-waves are readily observable at the International Monitoring System hydrophone triplet near Ascension Island, Atlantic Ocean. We present a new relationship between the magnitude of equatorial Atlantic strike-slip earthquakes and the rupture length from 47 events (MW 5.6–7.1). We found that oceanic earthquakes differ from continental ones, showing longer ruptures for the same magnitude, suggesting that oceanic transform faults are weak.

Description: Phenological responses to climate change frequently vary among trophic levels, which can result in increasing asynchrony between the peak energy requirements of consumers and the availability of resources. Migratory birds use multiple habitats with seasonal food resources along migration flyways. Spatially heterogeneous climate change could cause the phenology of food availability along the migration flyway to become desynchronized. Such heterogeneous shifts in food phenology could pose a challenge to migratory birds by reducing their opportunity for food availability along the migration path and consequently influencing their survival and reproduction. We develop a novel graph-based approach to quantify this problem and deploy it to evaluate the condition of the heterogeneous shifts in vegetation phenology for 16 migratory herbivorous waterfowl species in Asia. We show that climate change-induced heterogeneous shifts in vegetation phenology could cause a 12% loss of migration network integrity on average across all study species. Species that winter at relatively lower latitudes are subjected to a higher loss of integrity in their migration network. These findings highlight the susceptibility of migratory species to climate change. Our proposed methodological framework could be applied to migratory species in general to yield an accurate assessment of the exposure under climate change and help to identify actions for biodiversity conservation in the face of climate-related risks.

Description: Aim: We are using the fossil record of different marine plankton groups to determine how their biodiversity has changed during past climate warming comparable to projected future warming. Location: North Atlantic Ocean and adjacent seas. Time series cover a latitudinal range from 75° N to 6° S. Time period: Past 24,000 years, from the Last Glacial Maximum (LGM) to the current warm period covering the last deglaciation. Major taxa studied: Planktonic foraminifera, dinoflagellates and coccolithophores. Methods: We analyse time series of fossil plankton communities using principal component analysis and generalized additive models to estimate the overall trend of temporal compositional change in each plankton group and to identify periods of significant change. We further analyse local biodiversity change by analysing species richness, species gains and losses, and the effective number of species in each sample, and compare alpha diversity to the LGM mean. Results: All plankton groups show remarkably similar trends in the rates and spatio-temporal dynamics of local biodiversity change and a pronounced non-linearity with climate change in the current warm period. Assemblages of planktonic foraminifera and dinoflagellates started to change significantly with the onset of global warming around 15,500 to 17,000 years ago and continued to change at the same rate during the current warm period until at least 5000 years ago, while coccolithophore assemblages changed at a constant rate throughout the past 24,000 years, seemingly irrespective of the prevailing temperature change. Main conclusions: Climate change during the transition from the LGM to the current warm period led to a long-lasting reshuffling of zoo- and phytoplankton assemblages, likely associated with the emergence of new ecological interactions and possibly a shift in the dominant drivers of plankton assemblage change from more abiotic-dominated causes during the last deglaciation to more biotic-dominated causes with the onset of the Holocene.

Description: 〈jats:title〉Abstract〈/jats:title〉〈jats:sec〉〈jats:title〉Aim〈/jats:title〉〈jats:p〉Within the intensively‐studied, well‐documented latitudinal diversity gradient, the deep‐sea biodiversity of the present‐day Norwegian Sea stands out with its notably low diversity, constituting a steep latitudinal diversity gradient in the North Atlantic. The reason behind this has long been a topic of debate and speculation. Most prominently, it is explained by the deep‐sea glacial disturbance hypothesis, which states that harsh environmental glacial conditions negatively impacted Norwegian Sea diversities, which have not yet fully recovered. Our aim is to empirically test this hypothesis. Specific research questions are: (1) Has deep‐sea biodiversity been lower during glacials than during interglacials? 〈jats:italic〉(〈/jats:italic〉2) Was there any faunal shift at the Mid‐Brunhes Event (MBE) when the mode of glacial–interglacial climatic change was altered?〈/jats:p〉〈/jats:sec〉〈jats:sec〉〈jats:title〉Location〈/jats:title〉〈jats:p〉Norwegian Sea, deep sea (1819–2800 m), coring sites MD992277, PS1243, and M23352.〈/jats:p〉〈/jats:sec〉〈jats:sec〉〈jats:title〉Time period〈/jats:title〉〈jats:p〉620.7–1.4 ka (Middle Pleistocene–Late Holocene).〈/jats:p〉〈/jats:sec〉〈jats:sec〉〈jats:title〉Taxa studied〈/jats:title〉〈jats:p〉Ostracoda (Crustacea).〈/jats:p〉〈/jats:sec〉〈jats:sec〉〈jats:title〉Methods〈/jats:title〉〈jats:p〉We empirically test the deep‐sea glacial disturbance hypothesis by investigating whether diversity in glacial periods is consistently lower than diversity in interglacial periods. Additionally, we apply comparative analyses to determine a potential faunal shift at the MBE, a Pleistocene event describing a fundamental shift in global climate.〈/jats:p〉〈/jats:sec〉〈jats:sec〉〈jats:title〉Results〈/jats:title〉〈jats:p〉The deep Norwegian Sea diversity was not lower during glacial periods compared to interglacial periods. Holocene diversity was exceedingly lower than that of the last glacial period. Faunal composition changed substantially between pre‐ and post‐MBE.〈/jats:p〉〈/jats:sec〉〈jats:sec〉〈jats:title〉Main conclusions〈/jats:title〉〈jats:p〉These results reject the glacial disturbance hypothesis, since the low glacial diversity is the important precondition here. The present‐day‐style deep Norwegian Sea ecosystem was established by the MBE, more specifically by MBE‐induced changes in global climate, which has led to more dynamic post‐MBE conditions. In a broader context, this implies that the MBE has played an important role in the establishment of the modern polar deep‐sea ecosystem and biodiversity in general.〈/jats:p〉〈/jats:sec〉

Description: Microalgae are the main source of the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), essential for the healthy development of most marine and terrestrial fauna including humans. Inverse correlations of algal EPA and DHA proportions (% of total fatty acids) with temperature have led to suggestions of a warming-induced decline in the global production of these biomolecules and an enhanced importance of high latitude organisms for their provision. The cold Arctic Ocean is a potential hotspot of EPA and DHA production, but consequences of global warming are unknown. Here, we combine a full-seasonal EPA and DHA dataset from the Central Arctic Ocean (CAO), with results from 13 previous field studies and 32 cultured algal strains to examine five potential climate change effects; ice algae loss, community shifts, increase in light, nutrients, and temperature. The algal EPA and DHA proportions were lower in the ice-covered CAO than in warmer peripheral shelf seas, which indicates that the paradigm of an inverse correlation of EPA and DHA proportions with temperature may not hold in the Arctic. We found no systematic differences in the summed EPA and DHA proportions of sea ice versus pelagic algae, and in diatoms versus non-diatoms. Overall, the algal EPA and DHA proportions varied up to four-fold seasonally and 10-fold regionally, pointing to strong light and nutrient limitations in the CAO. Where these limitations ease in a warming Arctic, EPA and DHA proportions are likely to increase alongside increasing primary production, with nutritional benefits for a non-ice-associated food web.

Description: Vulcano is one of the seven volcanic islands composing the Aeolian Islands archipelago (Southern Italy), which also includes three other active volcanoes. The island was orig-inally a stratovolcano like Stromboli; afterwards, its shape turned towards a complex structure composed of several volcanic landforms of different sizes. This is due to the great variability of the tectonic and volcanic phenomena, presently showing a volcano made by two calderas, a lava dome complex and two small active cones. The largest of them is the tuff cone of La Fossa, hosted in the middle of a 3- km-wide caldera struc-ture (La Fossa caldera), whose borders are visible on the southern and western sides of the island. Its last eruption occurred in 1888–1890. At present, Vulcano is charac-terized by weak shallow seismicity and intense fumarolic activity mainly concentrated within the crater of the La Fossa cone and along its rims during a recent unrest phase started in 2021, and measured with a multiparametric monitoring network.

Description: Published

Description: 471-487

Description: OSV4: Preparazione alle crisi vulcaniche

Description: JCR Journal

Description: 〈jats:title〉Abstract〈/jats:title〉〈jats:p〉Numerous policy and international frameworks consider that “destructive fishing” hampers efforts to reach sustainability goals. Though ubiquitous, “destructive fishing” is undefined and therefore currently immeasurable. Here we propose a definition developed through expert consultation: “Destructive fishing is any fishing practice that causes irrecoverable habitat degradation, or which causes significant adverse environmental impacts, results in long‐term declines in target or nontarget species beyond biologically safe limits and has negative livelihood impacts.” We show strong stakeholder support for a definition, consensus on many biological and ecological dimensions, and no clustering of respondents from different sectors. Our consensus definition is a significant step toward defining sustainable fisheries goals and will help interpret and implement global political commitments which utilize the term “destructive fishing.” Our definition and results will help reinforce the Food and Agricultural Organization's Code of Conduct and meaningfully support member countries to prohibit destructive fishing practices.〈/jats:p〉

Description: The Arctic archipelago of Svalbard is a hotspot of global warming and many fjords experience a continuous increase in seawater temperature and glacial melt while sea-ice cover declines. In 1996/1998, 2012–2014, and 2021 macroalgal biomass and species diversity were quantified at the study site Hansneset, Kongsfjorden (W-Spitsbergen) in order to identify potential changes over time. In 2021, we repeated the earlier studies by stratified random sampling (1 × 1 m2, n = 3) along a sublittoral depth transect (0, 2.5, 5, 10, and 15 m) and investigated the lower depth limits of dominant brown algae between 3 and 19 m. The maximum fresh weight (FW) of all seaweeds was 11.5 kg m−2 at 2.5 m and to 99.9% constituted of kelp. Although biomass distribution along the depth transect in 2021 was not significantly different compared to 2012/2013, the digitate kelp community (Laminaria digitata/Hedophyllum nigripes) had transformed into an Alaria esculenta-dominated kelp forest. Consequently, a pronounced shift in kelp forest structure occurred over time as we demonstrate that biomass allocation to thallus parts is kelp species-specific. Over the past decade, kelp demography changed and in 2021 a balanced age structure of kelps (juveniles plus many older kelp individuals) was only apparent at 2.5 m. In addition, the abundances and lower depth limits of all dominant brown algae declined noticeably over the last 25 years while the red algal flora abundance remained unchanged at depth. We propose that the major factor driving the observed changes in the macroalgal community are alterations in underwater light climate, as in situ data showed increasing turbidity and decreasing irradiance since 2012 and 2017, respectively. As a consequence, the interplay between kelp forest retreat to lower depth levels caused by coastal darkening and potential macroalgal biomass gain with increasing temperatures will possibly intensify in the future with unforeseen consequences for melting Arctic coasts and fjord ecosystem services. The Arctic archipelago of Svalbard is a hotspot of global warming and many fjords experience a continuous increase in seawater temperature and glacial melt while sea-ice cover declines. In 1996/1998, 2012–2014, and 2021 macroalgal biomass and species diversity were quantified at the study site Hansneset, Kongsfjorden (W-Spitsbergen) in order to identify potential changes over time. In 2021, we repeated the earlier studies by stratified random sampling (1 × 1 m2, n = 3) along a sublittoral depth transect (0, 2.5, 5, 10, and 15 m) and investigated the lower depth limits of dominant brown algae between 3 and 19 m. The maximum fresh weight (FW) of all seaweeds was 11.5 kg m−2 at 2.5 m and to 99.9% constituted of kelp. Although biomass distribution along the depth transect in 2021 was not significantly different compared to 2012/2013, the digitate kelp community (Laminaria digitata/Hedophyllum nigripes) had transformed into an Alaria esculenta-dominated kelp forest. Consequently, a pronounced shift in kelp forest structure occurred over time as we demonstrate that biomass allocation to thallus parts is kelp species-specific. Over the past decade, kelp demography changed and in 2021 a balanced age structure of kelps (juveniles plus many older kelp individuals) was only apparent at 2.5 m. In addition, the abundances and lower depth limits of all dominant brown algae declined noticeably over the last 25 years while the red algal flora abundance remained unchanged at depth. We propose that the major factor driving the observed changes in the macroalgal community are alterations in underwater light climate, as in situ data showed increasing turbidity and decreasing irradiance since 2012 and 2017, respectively. As a consequence, the interplay between kelp forest retreat to lower depth levels caused by coastal darkening and potential macroalgal biomass gain with increasing temperatures will possibly intensify in the future with unforeseen consequences for melting Arctic coasts and fjord ecosystem services.

Description: The Arctic archipelago of Svalbard is a hotspot of global warming and many fjords experience a continuous increase in seawater temperature and glacial melt while sea-ice cover declines. In 1996/1998, 2012–2014, and 2021 macroalgal biomass and species diversity were quantified at the study site Hansneset, Kongsfjorden (W-Spitsbergen) in order to identify potential changes over time. In 2021, we repeated the earlier studies by stratified random sampling (1 × 1 m2, n = 3) along a sublittoral depth transect (0, 2.5, 5, 10, and 15 m) and investigated the lower depth limits of dominant brown algae between 3 and 19 m. The maximum fresh weight (FW) of all seaweeds was 11.5 kg m−2 at 2.5 m and to 99.9% constituted of kelp. Although biomass distribution along the depth transect in 2021 was not significantly different compared to 2012/2013, the digitate kelp community (Laminaria digitata/Hedophyllum nigripes) had transformed into an Alaria esculenta-dominated kelp forest. Consequently, a pronounced shift in kelp forest structure occurred over time as we demonstrate that biomass allocation to thallus parts is kelp species-specific. Over the past decade, kelp demography changed and in 2021 a balanced age structure of kelps (juveniles plus many older kelp individuals) was only apparent at 2.5 m. In addition, the abundances and lower depth limits of all dominant brown algae declined noticeably over the last 25 years while the red algal flora abundance remained unchanged at depth. We propose that the major factor driving the observed changes in the macroalgal community are alterations in underwater light climate, as in situ data showed increasing turbidity and decreasing irradiance since 2012 and 2017, respectively. As a consequence, the interplay between kelp forest retreat to lower depth levels caused by coastal darkening and potential macroalgal biomass gain with increasing temperatures will possibly intensify in the future with unforeseen consequences for melting Arctic coasts and fjord ecosystem services. The Arctic archipelago of Svalbard is a hotspot of global warming and many fjords experience a continuous increase in seawater temperature and glacial melt while sea-ice cover declines. In 1996/1998, 2012–2014, and 2021 macroalgal biomass and species diversity were quantified at the study site Hansneset, Kongsfjorden (W-Spitsbergen) in order to identify potential changes over time. In 2021, we repeated the earlier studies by stratified random sampling (1 × 1 m2, n = 3) along a sublittoral depth transect (0, 2.5, 5, 10, and 15 m) and investigated the lower depth limits of dominant brown algae between 3 and 19 m. The maximum fresh weight (FW) of all seaweeds was 11.5 kg m−2 at 2.5 m and to 99.9% constituted of kelp. Although biomass distribution along the depth transect in 2021 was not significantly different compared to 2012/2013, the digitate kelp community (Laminaria digitata/Hedophyllum nigripes) had transformed into an Alaria esculenta-dominated kelp forest. Consequently, a pronounced shift in kelp forest structure occurred over time as we demonstrate that biomass allocation to thallus parts is kelp species-specific. Over the past decade, kelp demography changed and in 2021 a balanced age structure of kelps (juveniles plus many older kelp individuals) was only apparent at 2.5 m. In addition, the abundances and lower depth limits of all dominant brown algae declined noticeably over the last 25 years while the red algal flora abundance remained unchanged at depth. We propose that the major factor driving the observed changes in the macroalgal community are alterations in underwater light climate, as in situ data showed increasing turbidity and decreasing irradiance since 2012 and 2017, respectively. As a consequence, the interplay between kelp forest retreat to lower depth levels caused by coastal darkening and potential macroalgal biomass gain with increasing temperatures will possibly intensify in the future with unforeseen consequences for melting Arctic coasts and fjord ecosystem services.

Description: Annual rhythms are observed in living organisms with numerous ecological implications. In the zooplanktonic copepod Calanus finmarchicus, such rhythms are crucial regarding its phenology, body lipid accumulation, and global carbon storage. Climate change drives annual biological rhythms out of phase with the prevailing environmental conditions with yet unknown but potentially catastrophic consequences. However, the molecular dynamics underlying phenology are still poorly described. In a rhythmic analysis of C. finmarchicus annual gene expression, results reveal that more than 90% of the transcriptome shows significant annual rhythms, with abrupt and dramatic upheaval between the active and diapause life cycle states. This work explores the implication of the circadian clock in the annual timing, which may control epigenetic mechanisms to profoundly modulate gene expression in response to calendar time. Results also suggest an increased light sensitivity during diapause that would ensure the photoperiodic entrainment of the endogenous annual clock.

Description: The Arctic archipelago of Svalbard is a hotspot of global warming and many fjords experience a continuous increase in seawater temperature and glacial melt while sea-ice cover declines. In 1996/1998, 2012–2014, and 2021 macroalgal biomass and species diversity were quantified at the study site Hansneset, Kongsfjorden (W-Spitsbergen) in order to identify potential changes over time. In 2021, we repeated the earlier studies by stratified random sampling (1 × 1 m2, n = 3) along a sublittoral depth transect (0, 2.5, 5, 10, and 15 m) and investigated the lower depth limits of dominant brown algae between 3 and 19 m. The maximum fresh weight (FW) of all seaweeds was 11.5 kg m−2 at 2.5 m and to 99.9% constituted of kelp. Although biomass distribution along the depth transect in 2021 was not significantly different compared to 2012/2013, the digitate kelp community (Laminaria digitata/Hedophyllum nigripes) had transformed into an Alaria esculenta-dominated kelp forest. Consequently, a pronounced shift in kelp forest structure occurred over time as we demonstrate that biomass allocation to thallus parts is kelp species-specific. Over the past decade, kelp demography changed and in 2021 a balanced age structure of kelps (juveniles plus many older kelp individuals) was only apparent at 2.5 m. In addition, the abundances and lower depth limits of all dominant brown algae declined noticeably over the last 25 years while the red algal flora abundance remained unchanged at depth. We propose that the major factor driving the observed changes in the macroalgal community are alterations in underwater light climate, as in situ data showed increasing turbidity and decreasing irradiance since 2012 and 2017, respectively. As a consequence, the interplay between kelp forest retreat to lower depth levels caused by coastal darkening and potential macroalgal biomass gain with increasing temperatures will possibly intensify in the future with unforeseen consequences for melting Arctic coasts and fjord ecosystem services. The Arctic archipelago of Svalbard is a hotspot of global warming and many fjords experience a continuous increase in seawater temperature and glacial melt while sea-ice cover declines. In 1996/1998, 2012–2014, and 2021 macroalgal biomass and species diversity were quantified at the study site Hansneset, Kongsfjorden (W-Spitsbergen) in order to identify potential changes over time. In 2021, we repeated the earlier studies by stratified random sampling (1 × 1 m2, n = 3) along a sublittoral depth transect (0, 2.5, 5, 10, and 15 m) and investigated the lower depth limits of dominant brown algae between 3 and 19 m. The maximum fresh weight (FW) of all seaweeds was 11.5 kg m−2 at 2.5 m and to 99.9% constituted of kelp. Although biomass distribution along the depth transect in 2021 was not significantly different compared to 2012/2013, the digitate kelp community (Laminaria digitata/Hedophyllum nigripes) had transformed into an Alaria esculenta-dominated kelp forest. Consequently, a pronounced shift in kelp forest structure occurred over time as we demonstrate that biomass allocation to thallus parts is kelp species-specific. Over the past decade, kelp demography changed and in 2021 a balanced age structure of kelps (juveniles plus many older kelp individuals) was only apparent at 2.5 m. In addition, the abundances and lower depth limits of all dominant brown algae declined noticeably over the last 25 years while the red algal flora abundance remained unchanged at depth. We propose that the major factor driving the observed changes in the macroalgal community are alterations in underwater light climate, as in situ data showed increasing turbidity and decreasing irradiance since 2012 and 2017, respectively. As a consequence, the interplay between kelp forest retreat to lower depth levels caused by coastal darkening and potential macroalgal biomass gain with increasing temperatures will possibly intensify in the future with unforeseen consequences for melting Arctic coasts and fjord ecosystem services.

Description: Aim: Species distribution models (SDMs) are essential tools in ecology and conservation. However, the scarcity of visual sightings of marine mammals in remote polar areas hinders the effective application of SDMs there. Passive acoustic monitoring (PAM) data provide year-round information and overcome foul weather limitations faced by visual surveys. However, the use of PAM data in SDMs has been sparse so far. Here, we use PAM-based SDMs to investigate the spatiotemporal distribution of the critically endangered Antarctic blue whale in the Weddell Sea. Location: The Weddell Sea. Methods: We used presence-only dynamic SDMs employing visual sightings and PAM detections in independent models. We compared the two independent models with a third combined model that integrated both visual and PAM data, aiming at leveraging the advantages of each data type: the extensive spatial extent of visual data and the broader temporal/environmental range of PAM data. Results: Visual and PAM data prove complementary, as indicated by a low spatial overlap between daily predictions and the low predictability of each model at detections of other data types. Combined data models reproduced suitable habitats as given by both independent models. Visual data models indicate areas close to the sea ice edge (SIE) and with low-to-moderate sea ice concentrations (SIC) as suitable, while PAM data models identified suitable habitats at a broader range of distances to SIE and relatively higher SIC. Main Conclusions: The results demonstrate the potential of PAM data to predict year-round marine mammal habitat suitability at large spatial scales. We provide reasons for discrepancies between SDMs based on either data type and give methodological recommendations on using PAM data in SDMs. Combining visual and PAM data in future SDMs is promising for studying vocalized animals, particularly when using recent advances in integrated distribution modelling methods.

Description: Ocean warming is especially pronounced in the Arctic, and phytoplankton will face thermodynamically driven changes in their physiology, potentially pushing them beyond their thermal optimum. We assessed temperature responses of multiple functional traits over their entire thermal window (growth rates, quotas of particulate organic carbon, nitrogen, and chlorophyll a, as well as photophysiological parameters) in three different Arctic phytoplankton species (Thalassiosira hyalina, Micromonas pusilla, and Nitzschia frigida). Temperature response patterns in growth and biomass production rates indicated that all species exhibit wide thermal windows with highest rates at temperatures that exceed current polar temperatures. Species showed different temperature response patterns in cellular elemental quotas, which originate from the interplay of cell division and biomass production: These processes differ in their temperature sensitivity and optima, resulting in U-shaped, bell-shaped, or linear patterns of elemental quotas. Despite unaltered light intensity, higher temperatures increased light acclimation indices in all species while lifetimes of photosystem II reopening decreased in all species, suggesting that warming causes a transition from light saturation to light limitation. Our findings on temperature sensitivities of cell division and biomass production not only indicate that Arctic phytoplankton may benefit from moderate warming, but also highlight that meaningful interpretations of cellular quotas require a consideration of the underlying processes.

Description: Fram Strait, the gateway between the Arctic and Atlantic Oceans, is undergoing major climate change-induced physical and biological transformations. In particular, rapid warming and ongoing “Atlantification” are driving species range shifts and altering food web structures in the Arctic. Understanding and predicting the consequences of these processes on future ecosystems requires detailed assessments of local and pelagic biodiversity. Gelatinous zooplankton (GZP) is an important component of pelagic communities, and recent evidence indicates that such communities are undergoing major changes in the Fram Strait. However, as sampling GZP is challenging, they are regularly underestimated in biodiversity, distribution, and abundance. To overcome this and address existing ecological knowledge gaps, we investigated patterns of pelagic metazoan diversity in Fram Strait using environmental DNA (eDNA) metabarcoding of the cytochrome c oxidase I (COI) gene. We successfully detected a broad range of taxa from the marine metazoan and GZP communities across sampling locations and ocean depth zones. We demonstrate the vertical structuring of diversity and elucidate relationships between taxa and water mass indicators, such as salinity and temperature. Furthermore, when comparing eDNA data with net and video transect data for GZP at the same period and location, we found that eDNA uncovered a higher number of taxa, including several that were not detected by the other methods. This study is a contribution to the formation of baseline Arctic GZP biodiversity datasets, as well as future research on changing marine metazoan biodiversity and community composition.

Description: 〈jats:title〉Abstract〈/jats:title〉〈jats:p〉Magnetic resonance imaging (MRI) was applied to determine the sex of polar cod (〈jats:styled-content style="fixed-case"〉〈jats:italic〉Boreogadus saida〈/jats:italic〉〈/jats:styled-content〉 Lepechin, 1774) (Actinopterygii: Gadidae) and to follow the gonadal development in individual animals over time. Individual unanaesthetised fish were transferred to a measurement chamber inside a preclinical 9.4 T MRI scanner and continuously perfused with aerated seawater. A screening procedure at an average of 3.5 h, consisting of a set of MRI scans of different orientations, was repeated every 4 weeks on the same set of reproducing 〈jats:styled-content style="fixed-case"〉〈jats:italic〉B. saida〈/jats:italic〉〈/jats:styled-content〉 (〈jats:italic〉n〈/jats:italic〉 = 10) with a body length of about 20 cm. Adapted multi‐slice flow‐compensated fast low‐angle shot (FcFLASH) and rapid acquisition with relaxation enhancement (RARE) protocols with an in‐plane resolution of 313 μm and an acquisition time of 2.5 min were used to visualise the morphology of various organs, including the gonads within the field of view (FOV). The MR images provided high resolution, enabling specific sex determination, calculation of gonad volumes, and determination of oocyte sizes. Gonad maturation was followed over 4 months from November 2021 until shortly before spawning in February 2022. The gonad volume increased by 2.3–25.5% for males and by 11.5–760.7% for females during the observation period. From October to February, the oocyte diameter increased from 427 μm (〈jats:italic〉n〈/jats:italic〉 = 1) to 1346 ± 27 μm (〈jats:italic〉n〈/jats:italic〉 = 4). Interestingly, individual oocytes showed changes in MR contrast over time that can be attributed to the morphological development of the oocytes. The results fit well with previous literature data from classical invasive studies. The presented approach has great potential for various ecophysiological applications such as monitoring natural or delayed development of internal organs or sex determination under different environmental conditions.〈/jats:p〉

Description: Shipwrecks and dumped munition continue to be a major hazard, both in the North Sea but also on a global scale. Research within the EU Interreg project North Sea Wrecks (NSW), in cooperation with the German Aerospace Centre, Institute for the Protection of Maritime Infrastructures (DLR), is generating new insights into the status of wrecks, the potential leakage of pollutants from remaining munitions loads and the effects of contamination on exposed marine organisms in the North Sea environment. Further, historical documents are generated from archives to describe ship’s history and sinking scenario. These historical findings were compared to models and images of the visual inspections of the wrecks. Further, samples of water, sediment and organisms are being analysed for traces of explosives. Combining the results of these different fields of research allows for a better understanding of the environmental risks deriving from these wrecks. This process is shown below by focusing on the wreck of the German light cruiser SMS MAINZ, which sank in 1914. Data were compared to three additional wrecks situated also within the southern German Bight. Available data about the wrecks were preliminary assessed using a wreck risk model. Finally, wrecks were ranked according to their potential environmental risk.

Description: Late Quaternary crustal uplift is well recognized in northeast Sicily, southern Italy, a region also prone to damaging earthquakes such as the 1908 “Messina” earthquake (Mw 7.1), the deadliest seismic event reported within the Italian Earthquake Catalogue. Yet it is still understudied if, within the Milazzo Peninsula, crustal uplift rates are varying spatially and temporally and whether they may be either influenced by (i) local upper-plate faulting activity or (ii) deep geodynamic processes. To investigate the long-term crustal vertical movements in northeast Sicily, we have mapped a flight of Middle-Late Pleistocene marine terraces within the Milazzo Peninsula and in its southern area and refined their chronology, using a synchronous correlation approach driven by published age controls. This has allowed a new calculation of the associated crustal uplift rates, along a north–south oriented coastal-parallel transect within the investigated area. Our results show a decreasing uplift rate from south to north across the Milazzo Peninsula and beyond, and that the associated rates of uplift have been constant through the Late Quaternary. This spatially varying yet temporally constant vertical deformation helps to constrain the amount of uplift, allowing us to explore which is the driving mechanism(s), proposing a few related scenarios. We discuss our results in terms of tectonic implications and emphasize the importance of using appropriate approaches, as such applying a synchronous correlation method, to refine chronologies of undated palaeoshorelines when used for tectonic investigations.

Description: In press

Description: OST2 Deformazione e Hazard sismico e da maremoto

Description: JCR Journal

Description: Arnoux's beaked whales (Berardius arnuxii) are generally considered to be uncommon to rare, and likely to prefer deep oceanic waters of the Southern Hemisphere. During many top-predator surveys in the Southern Ocean since 1988 we did not sight the species. However, in April 2022 we encountered three groups in the marginal sea-ice zone of the Weddell Sea. This study provides detailed descriptions of the sighted animals and their environment and report on unpublished sightings of this species from 1986 to 1998. A search of published information on the distribution of the species revealed 108 documented sightings with a total of 1,125 individuals. In combination these sources of information for the Southern Ocean, suggest a frequent occurrence in ice-covered waters, often close to the continental coast and edges of fast ice and ice-shelves. North of 60 S, in the temperate regions of the Southern Hemisphere, the species was also regularly sighted near continents, even far inshore, in fjords surrounded by land.

Description: Many biogeochemical processes change total alkalinity: this has been reported for carbonate precipitation and dissolution, uptake and release of various nitrogen-containing compounds, uptake of phosphate, sulfate reduction combined with methane oxidation. However, the list is not exhaustive. Here we discuss additional processes, namely the uptake of Mg, K, Ca by phytoplankton, and calculate their contribution based on the explicit conservative expression for TA and an extended (compared to Redfield's C : N : P) stoichiometry of phytoplankton. These additional contributions are of the same order of magnitude as that of phosphate uptake and thus much smaller than the contribution from nitrate uptake and of opposite sign to the contribution by nitrate and phosphate uptake.

Description: Understanding the patterns of marine microbial diversity (Bacteria + Archaea) is essential, as variations in their alpha- and beta-diversities can affect ecological processes. Investigations of microbial diversity from global oceanographic expeditions and basin-wide transects show positive correlations between microbial diversity and either temperature or productivity, but these studies rarely captured seasonality, especially in polar regions. Here, using multiannual alpha-diversity data from eight time series in the northern and southern hemispheres, we show that marine microbial community richness and evenness generally correlate more strongly with daylength than with temperature or chlorophyll a (a proxy for photosynthetic biomass). This pattern is observable across time series found in the northern and southern hemispheres regardless of collection method, DNA extraction protocols, targeted 16S rRNA hypervariable region, sequencing technology, or bioinformatics pipeline.

Description: The long-term dynamics of microbial communities across geographic, hydrographic, and biogeochemical gradients in the Arctic Ocean are largely unknown. To address this, we annually sampled polar, mixed, and Atlantic water masses of the Fram Strait (2015–2019; 5–100 m depth) to assess microbiome composition, substrate concentrations, and oceanographic parameters. Longitude and water depth were the major determinants (~30%) of microbial community variability. Bacterial alpha diversity was highest in lower-photic polar waters. Community composition shifted from west to east, with the prevalence of, for example, Dadabacteriales and Thiotrichales in Arctic- and Atlantic-influenced waters, respectively. Concentrations of dissolved organic carbon peaked in the western, compared to carbohydrates in the chlorophyll-maximum of eastern Fram Strait. Interannual differences due to the time of sampling, which varied between early (June 2016/2018) and late (September 2019) phytoplankton bloom stages, illustrated that phytoplankton composition and resulting availability of labile substrates influence bacterial dynamics. We identified 10 species clusters with stable environmental correlations, representing signature populations of distinct ecosystem states. In context with published metagenomic evidence, our microbial-biogeochemical inventory of a key Arctic region establishes a benchmark to assess ecosystem dynamics and the imprint of climate change.

Description: This paper presents a sequentially restored cross-section of the Organyà and Montsec minibasins based on geological mapping, new field observations and available borehole data. The main objective was to describe the geometry and evolution of both basins in terms of salt tectonics and minibasin mobility. To this end, a comprehensive palaeomagnetic database has been used to constrain vertical-axis rotations potentially related to minibasin translation and pivoting. The Organyà minibasin constitutes an asymmetric depocentre formed during the Upper Jurassic-Lower Cretaceous by translation above a southerly inclined salt layer. Salt evacuation and minibasin touchdown induced salt accumulation on the northern side of the basin that culminated in the development of the major Santa Fe unconformity during the late Albian—early Cenomanian. Indicative of salt quiescence is the following isopachous Cenomanian to lower Santonian sequence Salt tectonics resumed during the late Santonian—Palaeocene, with the Montsec minibasin downbuilding coinciding with the onset of Pyrenean convergence. Changes of the base-salt topography reflects regional-scale geodynamic processes. The acceleration of crustal thinning in the North Pyrenean zone during the late Albian-early Cenomanian favoured uplift in the Axial Zone, increasing slope and triggering salt mobilization in the Southern Pyrenees. Likewise, the onset of contraction renewed the downslope gliding of the Organyà and Montsec minbasins, and supports the idea that the early stages of basin inversion were governed by gravity tectonics. The kinematic reconstruction suggests that the more that 30° counterclockwise vertical axis rotation records pivoting during the suprasalt translation of the Organyà minibasin rather than solely the Iberian microplate rotation.

Description: Published

Description: e12846

Description: OSA1: Variazioni del campo magnetico terrestre, imaging crostale e sicurezza del territorio

Description: JCR Journal

Description: Aim: Arctic plants survived the Pleistocene glaciations in unglaciated refugia. The number, ages, and locations of these refugia are often unclear. We use high-resolution genomic data from present-day and Little-Ice-Age populations of Arctic Bell-Heather to re-evaluate the biogeography of this species and determine whether it had multiple independent refugia or a single refugium in Beringia. Location: Circumpolar Arctic and Coastal British Columbia (BC) alpine. Taxon: Cassiope tetragona L., subspecies saximontana and tetragona, outgroup C. mertensiana (Ericaceae). Methods: We built genotyping-by-sequencing (GBS) libraries using Cassiope tetragona tissue from 36 Arctic locations, including two ~250- to 500-year-old populations collected under glacial ice on Ellesmere Island, Canada. We assembled a de novo GBS reference to call variants. Population structure, genetic diversity and demography were inferred from PCA, ADMIXTURE, fastsimcoal2, SplitsTree, and several population genomics statistics. Results: Population structure analyses identified 4–5 clusters that align with geographic locations. Nucleotide diversity was highest in Beringia and decreased eastwards across Canada. Demographic coalescent analyses dated the following splits with Alaska: BC subspecies saximontana (5 mya), Russia (~1.4 mya), Europe (〉200–600 kya), and Greenland (~60 kya). Northern Canada populations appear to have formed during the current interglacial (7–9 kya). Admixture analyses show genetic variants from Alaska appear more frequently in present-day than historic plants on Ellesmere Island. Conclusions: Population and demographic analyses support BC, Alaska, Russia, Europe and Greenland as all having had independent Pleistocene refugia. Northern Canadian populations appear to be founded during the current interglacial with genetic contributions from Alaska, Europe and Greenland. We found evidence, on Ellesmere Island, for continued recent gene flow in the last 250–500 years. These results suggest that a re-analysis of other Arctic species with shallow population structure using higher resolution genomic markers and demographic analyses may help reveal deeper structure and other circumpolar glacial refugia.

Description: Anthropogenic stressors are omnipresent in marine environments and interfere with organisms of all sizes, from large whales to small organisms. We investigated potential interactive multistressor effects of increased temperature with chronic low-frequency sound on the development and movement patterns of the calanoid copepod Acartia tonsa, a model species for small marine zooplankton. Copepods were reared while exposed to chronic low-frequency sound around 15 and 22 dB re 1 μPa2 Hz−1 above control sound pressure levels at frequencies between 110 and 120 Hz, at 21°C (increased temperature) and 18°C (control temperature). For each sound and temperature scenario, we assessed after-incubation development rate, stage distribution, and movement patterns. We found that fewer copepods reached the developmental stages copepodites IV to VI in low-frequency sound conditions, even though warmer conditions increased developmental rate. By using high-speed videography in both control and low-frequency sound conditions, we observed that copepods showed more escape behaviors (drops) and fewer feeding-associated behaviors (helical swimming) when exposed to low-frequency sound (~ 42 dB higher than normal at 142 Hz). Copepods reared with added low-frequency sound showed fewer feeding-associated behaviors and did not reverse these trends despite the absence of added sound in their feeding environment. These significant behavioral changes suggest detrimental negative, life-long, consequences for copepods exposed to low-frequency sound.

Description: In this study, a future projection of marine cold spells (MCSs) over the tropical Indian Ocean is made using a fully coupled regional Earth system model, namely ROM, under two representative concentration pathways (RCPs): RCP4.5 and RCP8.5. In both RCPs, the future MCS properties have been estimated across three distinct time intervals: the near future (NF; 2010–2039), the middle future (MF; 2040–2069), and the far future (FF; 2070–2099). The future MCS computations were examined with respect to fixed historical baseline periods and varying baseline periods. MCSs were frequent, intense, and prolonged during the historical period. ROM effectively simulated these historical MCS metrics and their trends and outperformed the forcing general circulation model as well as the multimodel ensemble mean of Coupled Model Intercomparison Project phase 5 models. In the future, MCSs will cease to occur in ∼13% (4%), ∼56% (66%) and ∼69% (93%) of the area of the tropical Indian Ocean in the NF, MF, and FF respectively under the RCP4.5 (RCP8.5) scenario using a fixed historical baseline period. This departure of MCSs led to the disappearance of events, first identified over the Arabian Sea in both RCPs. The decrease in net heat flux and increase in wind speed contribute to the genesis and severity of MCS events. Further, during the El Niño regime, the MCS events dramatically decrease due to the basin-wide warming, but during the La Niña phase, the MCS intensity and spatial range increase. This study further investigates the sensitivity of MCSs with the choice of baseline period. Adopting varying baseline periods over time does not result in the disappearance of MCSs but does produce declining trends in MCS activity, highlighting the need for careful consideration in choosing a baseline period.

Description: Persistently high marine temperatures are escalating and threating marine biodiversity. The Baltic Sea, warming faster than other seas, is a good model to study the impact of increasing sea surface temperatures. Zostera marina, a key player in the Baltic ecosystem, faces susceptibility to disturbances, especially under chronic high temperatures. Despite the increasing number of studies on the impact of global warming on seagrasses, little attention has been paid to the role of the holobiont. Using an outdoor benthocosm to replicate near-natural conditions, this study explores the repercussions of persistent warming on the microbiome of Z. marina and its implications for holobiont function. Results show that both seasonal warming and chronic warming, impact Z. marina roots and sediment microbiome. Compared with roots, sediments demonstrate higher diversity and stability throughout the study, but temperature effects manifest earlier in both compartments, possibly linked to premature Z. marina die-offs under chronic warming. Shifts in microbial composition, such as an increase in organic matter-degrading and sulfur-related bacteria, accompany chronic warming. A higher ratio of sulfate-reducing bacteria compared to sulfide oxidizers was found in the warming treatment which may result in the collapse of the seagrasses, due to toxic levels of sulfide. Differentiating predicted pathways for warmest temperatures were related to sulfur and nitrogen cycles, suggest an increase of the microbial metabolism, and possible seagrass protection strategies through the production of isoprene. These structural and compositional variations in the associated microbiome offer early insights into the ecological status of seagrasses. Certain taxa/genes/pathways may serve as markers for specific stresses. Monitoring programs should integrate this aspect to identify early indicators of seagrass health. Understanding microbiome changes under stress is crucial for the use of potential probiotic taxa to mitigate climate change effects. Broader-scale examination of seagrass–microorganism interactions is needed to leverage knowledge on host–microbe interactions in seagrasses.

Description: Organic carbon (OC) in permafrost interacts with the mineral fraction of soil and sediments, representing 〈 1% to ~80% of the total OC pool. Quantifying the nature and controls of mineral-OC interactions is therefore crucial for realistic assessments of permafrost-carbon-climate feedbacks, especially in ice-rich regions facing rapid thaw and the development of thermo-erosion landforms. Here, we analyzed sediment samples from the Batagay megaslump in East Siberia, and we present total element concentrations , mineralogy, and mineral-OC interactions in its different stratigraphic units. Our findings indicate that up to 34 ± 8% of the OC pool interacts with mineral surfaces or elements. Interglacial deposits exhibit enhanced OC-mineral interactions, where OC has undergone greater microbial transformation and has likely low degradability. We provide a first-order estimate of ~12,000 tons of OC mobilized annually downslope of the headwall (i.e., the approximate mass of 30 large aircrafts), with a maximum of 38% interacting with OC via complexation with metals or associations to poorly crystalline iron oxides. These data imply that over one-third of the OC exposed by the slump is not readily available for mineralization, potentially leading to prolonged OC residence time in soil and sediments under stable physicochemical conditions.

Description: Amphibians and fishes play a central role in shaping the structure and function of freshwater environments. These organisms have a limited capacity to disperse across different habitats and the thermal buffer offered by freshwater systems is small. Understanding determinants and patterns of their physiological sensitivity across life history is, therefore, imperative to predicting the impacts of climate change in freshwater systems. Based on a systematic literature review including 345 experiments with 998 estimates on 96 amphibian (Anura/Caudata) and 93 freshwater fish species (Teleostei), we conducted a quantitative synthesis to explore phylogenetic, ontogenetic, and biogeographic (thermal adaptation) patterns in upper thermal tolerance (CTmax) and thermal acclimation capacity (acclimation response ratio, ARR) as well as the influence of the methodology used to assess these thermal traits using a conditional inference tree analysis. We found globally consistent patterns in CTmax and ARR, with phylogeny (taxa/order), experimental methodology, climatic origin, and life stage as significant determinants of thermal traits. The analysis demonstrated that CTmax does not primarily depend on the climatic origin but on experimental acclimation temperature and duration, and life stage. Higher acclimation temperatures and longer acclimation times led to higher CTmax values, whereby Anuran larvae revealed a higher CTmax than older life stages. The ARR of freshwater fishes was more than twice that of amphibians. Differences in ARR between life stages were not significant. In addition to phylogenetic differences, we found that ARR also depended on acclimation duration, ramping rate, and adaptation to local temperature variability. However, the amount of data on early life stages is too small, methodologically inconsistent, and phylogenetically unbalanced to identify potential life cycle bottlenecks in thermal traits. We, therefore, propose methods to improve the robustness and comparability of CTmax/ARR data across species and life stages, which is crucial for the conservation of freshwater biodiversity under climate change.

Description: Temperature and resource availability are pivotal factors influencing phytoplankton community structures. Numerous prior studies demonstrated their significant influence on phytoplankton stoichiometry, cell size, and growth rates. The growth rate, serving as a reflection of an organism's success within its environment, is linked to stoichiometry and cell size. Consequently, alterations in abiotic conditions affecting cell size or stoichiometry also exert indirect effects on growth. However, such results have their limitations, as most studies used a limited number of factors and factor levels which gives us limited insights into how phytoplankton respond to environmental conditions, directly and indirectly. Here, we tested for the generality of patterns found in other studies, using a combined multiple-factor gradient design and two single species with different size characteristics. We used a structural equation model (SEM) that allowed us to investigate the direct cumulative effects of temperature and resource availability (i.e., light, N and P) on phytoplankton growth, as well as their indirect effects on growth through changes in cell size and cell stoichiometry. Our results mostly support the results reported in previous research thus some effects can be identified as dominant effects. We identified rising temperature as the dominant driver for cell size reduction and increase in growth, and nutrient availability (i.e., N and P) as dominant factor for changes in cellular stoichiometry. However, indirect effects of temperature and resources (i.e., light and nutrients) on species' growth rates through cell size and cell stoichiometry differed across the two species suggesting different strategies to acclimate to its environment.

Description: Biodiversity is temporally dynamic, reflecting historical environmental conditions and influencing ecosystem stability. Colonisation and extinction dynamics frequently exhibit asynchronous patterns, resulting in net imbalances and thus to long-lasting richness trends. If these trends are not functionally random, functional net imbalances between colonisations and extinctions (fNICE) are likely to emerge. Using community time series data of European freshwater fish and North American breeding birds, we investigated how fNICE differs from its taxonomic equivalent (tNICE), to provide a comprehensive picture of biodiversity dynamics. Our findings reveal that taxonomic and functional delays are a prevalent feature, challenging the assumption of an immediate response to environmental changes. Taxonomic delays manifest as extinction debts and colonisation credits, while functional delays indicate a shift in the balance between functional gains and losses over time. Moreover, we found that taxonomic and functional imbalances are not always directly correlated, although some specific patterns were found consistently for fish and birds. Early colonisations outpaced functional gains, indicating that although new species arrived earlier than the extinction of other species, the acquisition of new functional traits lagged. Although this may temporarily stabilise communities, as functional redundancy can mitigate loss of function via local extinctions, excessive redundancy can compromise biodiversity's capacity to respond to environmental variations, thereby undermining long-term resilience. In conclusion, understanding the intricate temporal dynamics of biodiversity responses is paramount for effective conservation practices. While short-term observations may suggest an equilibrium between diversity and the environmental conditions, our results underscore the importance of considering long-term dynamics and the interplay between species traits and changing environments. The metrics tNICE and fNICE are valuable tools for quantifying these temporal dynamics and unravelling their consequences for ecosystem stability. Incorporating these insights into conservation strategies can aid in proactively preserving biodiversity and safeguarding the integrity of ecosystems. Read the free Plain Language Summary for this article on the Journal blog.

Description: The present distribution of Siberian boreal forests that are dominated by larches (Larix spp.) is influenced, to an unknown extent, by glacial history. Knowing the past treeline dynamics can improve our understanding of future treeline shifts under changing climate. Here, we study patterns in the genetic variability of Siberian Larix to help unravel biogeographic migration routes since the Last Glacial Maximum (LGM). We infer the spatial distribution and the postglacial demographic history of Larix using genome-wide single nucleotide polymorphisms (SNPs) derived through genotyping by sequencing (GBS) from 130 individuals sampled across eastern Siberia. Our analysis gives statistical support for two or three clusters, spanning from western to eastern Siberia. These clusters reveal a genetic structure influenced by isolation resulting from geographical distance, barriers imposed by geographic features, and distinct glacial histories. Assuming three clusters, our demographic inference indicates that the common ancestor of the current Larix populations existed in northeast Siberia well before the LGM. This suggests that Larix persisted in the northern region throughout previous glacials. Our genetic studies suggest that Larix likely survived the cold LGM in northern refugia, enabling a fast colonization of Siberia. Instead of complete repopulation from southern areas postglacially, the northernmost Larix expansion during the Holocene seems to have benefitted from refugial populations ahead of the treeline. Present-day migration is expected to be slow initially, due to the absence of current refugial populations in the far north, in contrast to the early-Holocene situation.

Description: Climate change increases the need to understand the effect of predicted future temperature and nutrient scenarios on marine phytoplankton. However, experimental studies addressing the effects of both drivers use a variety of design approaches regarding their temperature change rate and nutrient supply regimes. This study combines a systematic literature map to identify the existing bias in the experimental design of studies evaluating the phytoplankton response to temperature change, with a laboratory experiment. The experiment was designed to quantify how different temperature levels (6°C, 12°C, and 18°C), temperature regimes (abrupt vs. gradual increase), timings of nutrient addition (before or after the temperature change) and nutrient regimes (limiting vs. balanced) alter the growth and stoichiometry of a natural marine phytoplankton community. The systematic map revealed three key biases in marine global change experiments: (1) 66% of the studies do not explicitly describe the experimental temperature change or nutrient regime, (2) 84% applied an abrupt temperature exposure, and (3) only 15% experimentally manipulated the nutrient regime. Our experiment demonstrated that the identified biases in experimental design toward abrupt temperature exposure induced a short-term growth overshoot compared to gradually increasing temperatures. Additionally, the timing of nutrient availability strongly modulated the direction of the temperature effect and strength of growth enhancement along balanced N : P supply ratios. Our study stresses that the rate of temperature change, the timing of nutrient addition and the N : P supply ratio should be considered in experimental planning to produce ecologically relevant results as different setups lead to contrasting directions of outcome.

Description: The availability of alginate, an abundant macroalgal polysaccharide, induces compositional and functional responses among marine microbes, but these dynamics have not been characterized across the Pacific Ocean. We investigated alginate-induced compositional and functional shifts (e.g., heterotrophic production, glucose turnover, hydrolytic enzyme activities) of microbial communities in the South Subtropical, Equatorial, and Polar Frontal North Pacific in mesocosms. We observed that shifts in response to alginate were site-specific. In the South Subtropical Pacific, prokaryotic cell counts, glucose turnover, and peptidase activities changed the most with alginate addition, along with the enrichment of the widest range of particle-associated taxa (161 amplicon sequence variants; ASVs) belonging to Alteromonadaceae, Rhodobacteraceae, Phormidiaceae, and Pseudoalteromonadaceae. Some of these taxa were detected at other sites but only enriched in the South Pacific. In the Equatorial Pacific, glucose turnover and heterotrophic prokaryotic production increased most rapidly; a single Alteromonas taxon dominated (60% of the community) but remained low (〈2%) elsewhere. In the North Pacific, the particle-associated community response to alginate was gradual, with a more limited range of alginate-enriched taxa (82 ASVs). Thus, alginate-related ecological and biogeochemical shifts depend on a combination of factors that include the ability to utilize alginate, environmental conditions, and microbial interactions.

Description: 〈jats:title〉ABSTRACT〈/jats:title〉〈jats:p〉Marine metazoan biodiversity is accretively being explored through environmental DNA (eDNA) metabarcoding of seawater. However, knowledge gaps in the use of eDNA to study changes in diversity resulting from changing abiotic conditions still do exist. In order to address these gaps, we analyzed patterns of marine invertebrate biodiversity based on eDNA from water and sediment samples along a decreasing salinity gradient from the North Sea toward the Baltic Sea. eDNA was collected from surface (SW) and bottom (BW) water, and from the uppermost sediment layer (SE). To supplement the eDNA approach, we conducted parallel zooplankton (ZP) metabarcoding and morphological identification. DNA was extracted from eDNA and ZP samples, amplified using two universal primers that target of the mitochondrial cytochrome c oxidase subunit 1 (COI) and the nuclear ribosomal 18S rRNA genes, and paired‐end sequenced on Illumina Miseq. Metabarcoding detected 279 metazoan species (from 16 phyla) of which > 87% are known from the study area or adjacent regions. Communities identified in SW eDNA were a subset of communities identified in ZP metabarcoding. BW eDNA had additional benthic (mainly bivalve) species. Communities identified in SE eDNA were distinct from those in water eDNA and ZP metabarcoding, and mainly represented by in‐ and meiofauna. Out of all approaches, only ZP metabarcoding uncovered the expected decrease in species richness toward brackish conditions. Neither salinity nor spatial distance had a significant effect on species composition. All approaches revealed regional differences of which SE eDNA was least informative. The detection of holoplanktonic species from SE eDNA provided evidence for sinking of eDNA particles, dead organisms or the presence of resting eggs. Our study confirms the value of metabarcoding to identify the North Sea and Baltic Sea invertebrates and underscores the importance of combining multiple approaches to understand invertebrate biodiversity and its change in the marine realm.〈/jats:p〉

Description: Palearctic water frogs (genus Pelophylax) are an outstanding model in ecology and evolution, being widespread, speciose, either threatened or threatening to other species through biological invasions, and capable of siring hybrid offspring that escape the rules of sexual reproduction. Despite half a century of genetic research and hundreds of publications, the diversity, systematics and biogeography of Pelophylax still remain highly confusing, in no small part due to a lack of correspondence between studies. To provide a comprehensive overview, we gathered 〉13,000 sequences of barcoding genes from 〉1700 native and introduced localities and built multigene mitochondrial (~17 kb) and nuclear (~10 kb) phylogenies. We mapped all currently recognized taxa and their phylogeographic lineages (〉40) to get a grasp on taxonomic issues, cyto-nuclear discordances, the genetic makeup of hybridogenetic hybrids, and the origins of introduced populations. Competing hypotheses for the molecular calibration were evaluated through plausibility tests, implementing a new approach relying on predictions from the anuran speciation continuum. Based on our timetree, we propose a new biogeographic paradigm for the Palearctic since the Paleogene, notably by attributing a prominent role to the dynamics of the Paratethys, a vast paleo-sea that extended over most of Europe. Furthermore, our results show that distinct marsh frog lineages from Eastern Europe, the Balkans, the Near East, and Central Asia (P. ridibundus ssp.) are naturally capable of inducing hybridogenesis with pool frogs (P. lessonae). We identified 14 alien lineages (mostly of P. ridibundus) over ~20 areas of invasions, especially in Western Europe, with genetic signatures disproportionally pointing to the Balkans and Anatolia as the regions of origins, in line with exporting records of the frog leg industry and the stocks of pet sellers. Pelophylax thus emerges as one of the most invasive amphibians worldwide, and deserves much higher conservation concern than currently given by the authorities fighting biological invasions.

Description: Coral reef ecosystems in Indonesia are under threat due to changes in the environment driven by global climate change, along with local disturbances such as sedimentation and eutrophication. Consequently, comprehensive coral reef monitoring \nactivities have been initiated at numerous locations across Indonesia. In this study, the \nfindings from coral reef health surveys across 14 reef sites (within 40 hectares) in the \nBintan area (Riau Archipelago, Indonesia; 100\xe2\x80\x89km southeast of Singapore) revealed a \npotentially novel epizoic yellow sponge species (Phorbas sp.) that overgrows coral colonies. This species, tentatively classified as a new Phorbas sp. (order Poecilosclerida: \nfamily Hymedesmiidae), was identified through a combined approach employing classical taxonomic methods along with DNA barcoding using the cytochrome c oxidase \nI (COI) gene. At every site, three permanent 20-m transects were established to annually monitor live coral coverage and species composition between 2014 and 2017. \nThe survey indicated a notable change in the overall coral cover during this period. \nThe abundance of coral diseases was investigated in 2014 and 2017. Additionally, the \nprogress of Phorbas sp., was closely monitored (i.e., every second day for one week) \nat Bintan Island (site 11) during the dry season in August 2017. This approach aimed \nto approximate the relative impact of each incident on the coral\'s condition. The results indicated that the most comprehensive change occurred due to the overgrowth \nof Phorbas sp., which affected 12 scleractinian coral species across eight genera in \nalmost all sites except one. The abundance of this epizoic sponge infestation was \nhighest at Pulau Beralas Pasir (site 10), constituting 22.9% of all recorded life forms, \nand lowest at Pulau Pangkil-Besar (site 13), with only 0.7%. The expansion of the thin \nyellow sponge tissue was estimated to increase by up to 0.51\xe2\x80\x89\xc2\xb1\xe2\x80\x890.48\xe2\x80\x89cm2 \n per day on \nPorites coral.

Description: Aim: Amazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated with either geographic regions or edaphic forest types. Location: Amazonia. Taxon: Angiosperms (Magnoliids; Monocots; Eudicots). Methods: Data for the abundance of 5082 tree species in 1989 plots were combined with a mega-phylogeny. We applied evolutionary ordination to assess how phylogenetic composition varies across Amazonia. We used variation partitioning and Moran's eigenvector maps (MEM) to test and quantify the separate and joint contributions of spatial and environmental variables to explain the phylogenetic composition of plots. We tested the indicator value of lineages for geographic regions and edaphic forest types and mapped associations onto the phylogeny. Results: In the terra firme and várzea forest types, the phylogenetic composition varies by geographic region, but the igapó and white-sand forest types retain a unique evolutionary signature regardless of region. Overall, we find that soil chemistry, climate and topography explain 24% of the variation in phylogenetic composition, with 79% of that variation being spatially structured (R2= 19% overall for combined spatial/environmental effects). The phylogenetic composition also shows substantial spatial patterns not related to the environmental variables we quantified (R2= 28%). A greater number of lineages were significant indicators of geographic regions than forest types. Main Conclusion: Numerous tree lineages, including some ancient ones (〉66 Ma), show strong associations with geographic regions and edaphic forest types of Amazonia. This shows that specialization in specific edaphic environments has played a long-standing role in the evolutionary assembly of Amazonian forests. Furthermore, many lineages, even those that have dispersed across Amazonia, dominate within a specific region, likely because of phylogenetically conserved niches for environmental conditions that are prevalent within regions.

Description: In the microscopy realm, a large body of dark biodiversity still awaits to be uncovered. Unarmoured dinophytes are particularly neglected here, as they only present inconspicuous traits. In a remote German locality, we collected cells, from which a monoclonal strain was established, to study morphology using light and electron microscopy and to gain DNA sequences from the rRNA operon. In parallel, we detected unicellular eukaryotes in ponds of the Botanical Garden Munich-Nymphenburg by DNA-metabarcoding (V4 region of the 18S rRNA gene), weekly sampled over the course of a year. Strain GeoK*077 turned out to be a new species of Borghiella with a distinct position in molecular phylogenetics and characteristic coccoid cells of ovoid shape as the most important diagnostic trait. Borghiella ovum, sp. nov., was also present in artificial ponds of the Botanical Garden and was the second most abundant dinophyte detected in the samples. More specifically, Borghiella ovum, sp. nov., shows a clear seasonality, with high frequency during winter months and complete absence during summer months. The study underlines the necessity to assess the biodiversity, particularly of the microscopy realm more ambitiously, if even common species such as formerly Borghiella ovum are yet unknown to science.

Description: This paper positions possibilities for human geographies of the sea. The growing volume of work under this banner has been largely qualitative in its approach, reflecting, in turn, the questions posed by oceanic scholars. These questions necessitate corresponding methods. Whilst this is not necessarily a problem, and the current corpus of work has offered many significant contributions, in making sense of the human dimensions of maritime worlds, other questions—and methods—may generate knowledge that is useful within this remit of work. This paper considers the place of quantitative approaches in posing lines of enquiry about shipping, one of the prominent areas of concern under the banner of ‘human geographies of the seas’. There is longstanding work in transport geographies concerned with shipping, logistics, freight movement and global connections, which embraces quantitative methods which could be bridged to ask fresh questions about oceanic spatial phenomena past and present. This paper reviews the state of the art of human geographies of the sea and transport geographies and navigates how the former field may be stimulated by some of the interests of the latter and a broader range of questions about society-sea-space relations. The paper focuses on Automatic Identification Systems (or AIS) as a potentially useful tool for connecting debates, and deepening spatial understandings of the seas and shipping beyond current scholarship. To advance the argument the example of shipping layups is used to illustrate or rather, position, the point.

Description: The toxin-producing dinoflagellate Alexandrium pseudogonyaulax has become increasingly abundant in northern European waters, replacing other Alexandrium species. A. pseudogonyaulax produces goniodomins and lytic substances, which can be cytotoxic toward other organisms, including fish, but we still know little about the environmental conditions influencing its growth and toxicity. Here, we investigated the impacts of different nitrogen sources and light intensities, common bottom-up drivers of bloom formation, on the growth and toxin content of three A. pseudogonyaulax strains isolated from the Danish Limfjord. While the growth rates were significantly influenced by nitrogen source and light intensity, the intracellular toxin contents only showed strong differences between the exponential and stationary growth phases. Moreover, the photophysiological response of A. pseudogonyaulax showed little variation across varying light intensities, while light-harvesting pigments were significantly more abundant under low light conditions. This study additionally highlights considerable physiological variability between strains, emphasizing the importance of conducting laboratory experiments with several algal strains. A high physiological plasticity toward changing abiotic parameters points to a long-term establishment of A. pseudogonyaulax in northern European waters.

Description: The toxin-producing dinoflagellate Alexandrium pseudogonyaulax has become increasingly abundant in northern European waters, replacing other Alexandrium species. A. pseudogonyaulax produces goniodomins and lytic substances, which can be cytotoxic toward other organisms, including fish, but we still know little about the environmental conditions influencing its growth and toxicity. Here, we investigated the impacts of different nitrogen sources and light intensities, common bottom-up drivers of bloom formation, on the growth and toxin content of three A. pseudogonyaulax strains isolated from the Danish Limfjord. While the growth rates were significantly influenced by nitrogen source and light intensity, the intracellular toxin contents only showed strong differences between the exponential and stationary growth phases. Moreover, the photophysiological response of A. pseudogonyaulax showed little variation across varying light intensities, while light-harvesting pigments were significantly more abundant under low light conditions. This study additionally highlights considerable physiological variability between strains, emphasizing the importance of conducting laboratory experiments with several algal strains. A high physiological plasticity toward changing abiotic parameters points to a long-term establishment of A. pseudogonyaulax in northern European waters.

Description: Aim: The efficiency of animal-mediated seed dispersal is threatened by the decline of animal populations, especially in tropical forests. We hypothesise that large-seeded plants with animal-mediated dispersal tend to have limited geographic ranges and face an increased risk of extinction due to the potential decline in seed dispersal by large-bodied fruit-eating and seed-dispersing animals (frugivores). Location: Atlantic Forest, Brazil, South America. Taxon: Angiosperms. Methods: First, we collected dispersal-related traits (dispersal syndrome, fruit size, and seed size), growth form (tree, climber, and other) and preferred vegetation type (open and closed) data for 1052 Atlantic Forest plant species. Next, we integrated these with occurrence records, extinction risk assessments, and phylogenetic trees. Finally, we performed phylogenetic generalised least squares regressions to test the direct and interactive effects of dispersal-related traits and vegetation type on geographical range size. Results: Large-seeded species had smaller range sizes than small-seeded species, but only for species with animal-mediated dispersal, not for those dispersed by abiotic mechanisms. However, plants with abiotic dispersal had overall smaller range sizes than plants with animal-mediated dispersal. Furthermore, we found that species restricted to forests had smaller ranges than those occurring in open or mixed vegetation. Finally, at least 29% of the Atlantic Forest flora is threatened by extinction, but this was not related to plant dispersal syndromes. Main Conclusions: Large-seeded plants with animal-mediated dispersal may be suffering from dispersal limitation, potentially due to past and ongoing defaunation of large-bodied frugivores, leading to small range sizes. Other factors, such as deforestation and fragmentation, will probably modulate the effects of dispersal on range size, and ultimately extinction. Our study sheds light on the relationship between plant traits, mutualistic interactions, and distribution that are key to the functioning of tropical forests.

Description: Aim Species have different distribution patterns across the globe and among biogeographical regions. The Nearctic and Palaearctic regions share lineages because of their parallel biogeographic histories and ecological conditions. As the number of phylogenetic studies increases, there are more insights into past exchange events between these two regions and their effects on the current distribution of diversity. However, several groups have not been tested and an overall generalization is still missing. Here, we analyse the biogeographic history across multiple genera of odonates to elucidate a general process of species exchange, vicariance and species divergence between these two regions. Location The Holarctic, including the entire Nearctic and the East and West Palaearctic. Taxon 14 genera of Odonata (Insecta). Methods We reconstructed a time-calibrated phylogenetic tree for each genus to determine species relationships and divergence time using 3614 COI sequences of 259 species. Biogeographic ancestral range estimation was inferred for each phylogeny using BioGeoBEARS. Preferred habitat (lotic versus lentic) was established for each species. Results Exchange events were not restricted in time, direction or either lentic habitat or lotic habitat. Most genera crossed between both regions only once, and it was mainly across the Beringia, while three diverse anisopteran genera revealed multiple exchanges. Recent exchanges during the Pleistocene were associated with cold-dwelling and lentic species. Main Conclusions Our finding reveals the absence of a generalizable pattern of species exchange and divergence between the Nearctic and Palaearctic regions; instead, we found lineage-specific biogeographic patterns. This finding highlights the complexity of drivers and functional traits that shaped current diversity patterns. Moreover, it emphasizes that general conclusions cannot be formulated based on one single clade.

Description: Molecular techniques like metabarcoding, while promising for exploring diversity of communities, are often impeded by the lack of reference DNA sequences available for taxonomic annotation. Our study explores the benefits of combining targeted DNA barcoding and morphological taxonomy to improve metabarcoding efficiency, using beach meiofauna as a case study. Beaches are globally important ecosystems and are inhabited by meiofauna, microscopic animals living in the interstitial space between the sand grains, which play a key role in coastal biodiversity and ecosystem dynamics. However, research on meiofauna faces challenges due to limited taxonomic expertise and sparse sampling. We generated 775 new cytochrome c oxidase I DNA barcodes from meiofauna specimens collected along the Netherlands' west coast and combined them with the NCBI GenBank database. We analysed alpha and beta diversity in 561 metabarcoding samples from 24 North Sea beaches, a region extensively studied for meiofauna, using both the enriched reference database and the NCBI database without the additional reference barcodes. Our results show a 2.5-fold increase in sequence annotation and a doubling of species-level Operational Taxonomic Units (OTUs) identification when annotating the metabarcoding data with the enhanced database. Additionally, our analyses revealed a bell-shaped curve of OTU richness across the intertidal zone, aligning more closely with morphological analysis patterns, and more defined community dissimilarity patterns between supralittoral and intertidal sites. Our research highlights the importance of expanding molecular reference databases and combining morphological taxonomy with molecular techniques for biodiversity assessments, ultimately improving our understanding of coastal ecosystems.

Description: Aim: The scale of environmental data is often defined by their extent (spatial area, temporal duration) and resolution (grain size, temporal interval). Although describing climate data scale via these terms is appropriate for most meteorological applications, for ecology and biogeography, climate data of the same spatiotemporal resolution and extent may differ in their relevance to an organism. Here, we propose that climate proximity, or how well climate data represent the actual conditions that an organism is exposed to, is more important for ecological realism than the spatiotemporal resolution of the climate data. Location: Temperature comparison in nine countries across four continents; ecological case studies in Alberta (Canada), Sabah (Malaysia) and North Carolina/Tennessee (USA). Time Period: 1960–2018. Major Taxa Studied: Case studies with flies, mosquitoes and salamanders, but concepts relevant to all life on earth. Methods: We compare the accuracy of two macroclimate data sources (ERA5 and WorldClim) and a novel microclimate model (microclimf) in predicting soil temperatures. We then use ERA5, WorldClim and microclimf to drive ecological models in three case studies: temporal (fly phenology), spatial (mosquito thermal suitability) and spatiotemporal (salamander range shifts) ecological responses. Results: For predicting soil temperatures, microclimf had 24.9% and 16.4% lower absolute bias than ERA5 and WorldClim respectively. Across the case studies, we find that increasing proximity (from macroclimate to microclimate) yields a 247% improvement in performance of ecological models on average, compared to 18% and 9% improvements from increasing spatial resolution 20-fold, and temporal resolution 30-fold respectively. Main Conclusions: We propose that increasing climate proximity, even if at the sacrifice of finer climate spatiotemporal resolution, may improve ecological predictions. We emphasize biophysically informed approaches, rather than generic formulations, when quantifying ecoclimatic relationships. Redefining the scale of climate through the lens of the organism itself helps reveal mechanisms underlying how climate shapes ecological systems.

Description: In recent decades, great research efforts have been made to understand how specific anthropogenic drivers impact coastal marine ecosystems and their services. Nevertheless, we still lack a synthesis of the existing knowledge on single and multiple anthropogenic drivers impacts to coastal marine systems, which is necessary to guide future work. The objective of this paper is to assess the current knowledge on the impacts of anthropogenic drivers and their interactions on coastal marine ecosystem services, with emphasis on abiotic drivers as dissolved nutrients (eutrophication or de-eutrophication), temperature (warming), pH (acidification) and oxygen (hypoxia). We performed a systematic review of the literature consisting of 164 papers using the PRISMA method (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). We only include English-written papers, we exclude non-English papers to avoid potential errors in representing or interpreting scientific information due to language limitations among the authors. The results show that coastal marine ecosystem service research has largely focused on single drivers, while multiple driver assessments are less common. Assessments partially integrate multiple driver complexity, but they do not consider (1) relations and feedbacks between drivers; 2() social processes dynamics; and (3) temporal and spatial scales. Synthesis and applications. We have reviewed the current scientific knowledge on how human drivers affect coastal marine ecosystem services. We found that understanding the combined effects of different drivers and considering various time and space scales is still a pending issue. Ignoring multiple drivers, their interactions and time and space scales limits our understanding of reality, and results in high levels of uncertainty. This affects policies and actions, as they rely on uncertain information. Thus, incomplete knowledge leads to poor management of coastal ecosystem services. To improve this, we propose research framework to better consider multiple drivers and time and space factors.

Description: The late Miocene Monte Capanne and Porto Azzurro plutons are investigated by means of coupled U-Pb zircon and 40Ar/39Ar white mica dating to test the occurrence of long-lived magmatic systems in the upper crust. Zircon crystallized for 〉 1 Myr in both plutonic systems, with supersolidus conditions overlapping for ~220 kyr indicating previously unrecognized co-existence of the two reservoirs. The development of the Porto Azzurro high T-aureole is post-dated by continuous igneous zircon crystallization until ~ 6.0 Ma. By linking crystallization to post-emplacement cooling of late-stage pulses in both western and eastern Elba we constrain long-lived sizeable reservoirs (possibly the same reservoir) in the Tyrrhenian upper crust between ~8 and 6 Ma.

Description: Published

Description: 258-265

Description: OST1 Alla ricerca dei Motori Geodinamici

Description: JCR Journal

Description: The threat from novel marine species introductions is a global issue. When non-native marine species are introduced to novel environments and become invasive, they can affect biodiversity, industry, ecosystem function, and both human and wildlife health. Isolated areas with sensitive or highly specialised endemic species can be particularly impacted. The global increase in the scope of tourism and other human activities, together with a rapidly changing climate, now put these remote ecosystems under threat. In this context, we analyse invasion pathways into South Georgia and the South Sandwich Islands (SGSSI) for marine non-native species via vessel biofouling. The SGSSI archipelago has high biodiversity and endemism, and has historically been highly isolated from the South American mainland. The islands sit just below the Polar Front temperature boundary, affording some protection against introductions. However, the region is now warming and SGSSI increasingly acts as a gateway port for vessel traffic into the wider Antarctic, amplifying invasion likelihood. We use remote Automatic Identification System vessel-tracking data over a 2-year period to map vessel movement and behaviour around South Georgia, and across the ‘Scotia Sea’, ‘Magellanic’ and northern ‘Continental High Antarctic’ ecoregions. We find multiple vessel types from locations across the globe frequently now enter shallow inshore waters and stop for prolonged periods (weeks/months) at anchor. Vessels are active throughout the year and stop at multiple port hubs, frequently crossing international waters and ecoregions. Management recommendations to reduce marine invasion likelihood within SGSSI include initiating benthic and hull monitoring at the identified activity/dispersion hubs of King Edward Point, Bay of Isles, Gold Harbour, St Andrews Bay and Stromness Bay. More broadly, regional collaboration and coordination is necessary at neighbouring international ports. Here vessels need increased pre- and post-arrival biosecurity assessment following set protocols, and improved monitoring of hulls for biofouling to pre-emptively mitigate this threat.

Description: 〈jats:title〉Abstract〈/jats:title〉〈jats:p〉Gut microbiota can influence host gene expression and physiology through metabolites. Besides, the presence or absence of gut microbiome can reprogram host transcriptome and epitranscriptome as represented by 〈jats:italic〉N〈/jats:italic〉〈jats:sup〉6〈/jats:sup〉‐methyladenosine (m〈jats:sup〉6〈/jats:sup〉A), the most abundant mammalian mRNA modification. However, which and how gut microbiota‐derived metabolites reprogram host transcriptome and m〈jats:sup〉6〈/jats:sup〉A epitranscriptome remain poorly understood. Here, investigation is conducted into how gut microbiota‐derived metabolites impact host transcriptome and m〈jats:sup〉6〈/jats:sup〉A epitranscriptome using multiple mouse models and multi‐omics approaches. Various antibiotics‐induced dysbiotic mice are established, followed by fecal microbiota transplantation (FMT) into germ‐free mice, and the results show that bile acid metabolism is significantly altered along with the abundance change in bile acid‐producing microbiota. Unbalanced gut microbiota and bile acids drastically change the host transcriptome and the m〈jats:sup〉6〈/jats:sup〉A epitranscriptome in multiple tissues. Mechanistically, the expression of m〈jats:sup〉6〈/jats:sup〉A writer proteins is regulated in animals treated with antibiotics and in cultured cells treated with bile acids, indicating a direct link between bile acid metabolism and m〈jats:sup〉6〈/jats:sup〉A biology. Collectively, these results demonstrate that antibiotic‐induced gut dysbiosis regulates the landscape of host transcriptome and m〈jats:sup〉6〈/jats:sup〉A epitranscriptome via bile acid metabolism pathway. This work provides novel insights into the interplay between microbial metabolites and host gene expression.〈/jats:p〉

Description: 〈jats:title〉Abstract〈/jats:title〉〈jats:p〉Gut microbiota can influence host gene expression and physiology through metabolites. Besides, the presence or absence of gut microbiome can reprogram host transcriptome and epitranscriptome as represented by 〈jats:italic〉N〈/jats:italic〉〈jats:sup〉6〈/jats:sup〉‐methyladenosine (m〈jats:sup〉6〈/jats:sup〉A), the most abundant mammalian mRNA modification. However, which and how gut microbiota‐derived metabolites reprogram host transcriptome and m〈jats:sup〉6〈/jats:sup〉A epitranscriptome remain poorly understood. Here, investigation is conducted into how gut microbiota‐derived metabolites impact host transcriptome and m〈jats:sup〉6〈/jats:sup〉A epitranscriptome using multiple mouse models and multi‐omics approaches. Various antibiotics‐induced dysbiotic mice are established, followed by fecal microbiota transplantation (FMT) into germ‐free mice, and the results show that bile acid metabolism is significantly altered along with the abundance change in bile acid‐producing microbiota. Unbalanced gut microbiota and bile acids drastically change the host transcriptome and the m〈jats:sup〉6〈/jats:sup〉A epitranscriptome in multiple tissues. Mechanistically, the expression of m〈jats:sup〉6〈/jats:sup〉A writer proteins is regulated in animals treated with antibiotics and in cultured cells treated with bile acids, indicating a direct link between bile acid metabolism and m〈jats:sup〉6〈/jats:sup〉A biology. Collectively, these results demonstrate that antibiotic‐induced gut dysbiosis regulates the landscape of host transcriptome and m〈jats:sup〉6〈/jats:sup〉A epitranscriptome via bile acid metabolism pathway. This work provides novel insights into the interplay between microbial metabolites and host gene expression.〈/jats:p〉

Description: Projected growth in insect production as alternative feedstuffs will yield novel by-products that are potentially valuable for aquafeed applications. We analyzed the nutrient composition of three by-products occurring from black soldier fly larvae production (exuvia, cocoon, imago) and the bioavailability of key nutrients for Pacific Whiteleg shrimp (Litopenaeus vannamei). Protein accounted for 317 g kg−1 in exuviae, 433 g kg−1 in cocoons, and up to 521 g kg−1 in adult flies (imagines). Considerable amounts of essential amino acids were detected in imago meal, which significantly matched the ideal dietary amino acid composition for penaeid shrimp (r2 = 0.66, p = 0.0076). Exuviae and cocoons contained moderate amounts of lipids (64–140 g kg−1), while imagines comprised 356 g kg−1 total lipid. Saturated fatty acids predominated in all insect materials (47%–83% of total fatty acids). Chitin concentration was highest in cocoons and exuviae (154 and 139 g kg−1) and low in imagines (51 g kg−1). A feeding trial with shrimp, L vannamei, revealed apparent digestibility coefficients of 20%–59% for protein, 24%–54% for energy, 25%–49% for carbon, and 27%–68% for copper. Defatting of imago meal increased the digestibility of protein, energy, and carbon by 77%, 64%, and 61%, respectively. Defatted imago meal can serve as a protein supplement for shrimp diets.

Description: Rapidly changing permafrost landscapes are a potential key terrestrial source of greenhouse gases (GHGs) at a global scale, yet, remain poorly characterized regarding GHG origins and environmental controls on emissions. Subsurface ice wedges, commonly found across many permafrost landscapes, harbor GHG-rich gas bubbles. Analyzing these bubbles aids comprehension of subzero temperature GHG formation in permafrost. The Batagay megaslump, Earth's largest known thaw slump in northern Yakutia, provides an opportunity to study mixing ratios and isotopic compositions of both GHGs and non-GHG in ice wedge samples from two stratigraphic units: the Upper Ice Complex (UIC) and the Lower Ice Complex (LIC). The Ar/N2/O2 compositions and bubble shapes indicated that the studied ice wedges were likely formed through dry snow and/or hoarfrost compaction, and microbial activity remained active after ice wedge formation. The high CO2 and CH4 mixing ratios and carbon stable isotope values suggested that CO2 and CH4 primarily originated from microbial sources. N2O showed an “exclusive relation” with CH4—meaning that high N2O is observed only when CH4 is low, and vice versa—and N2O mixing ratios vary at different depths. These findings suggest that GHG formation in ice wedges is not solely controlled by physiochemical conditions, but involves a complex interplay between microbial activity and environmental conditions. Our study contributes to a better understanding of the dynamics involved in GHG formation within degrading permafrost landscapes.

Description: Recent years have seen a dramatic rise in the use of passive acoustic monitoring (PAM) for biological and ecological applications, and a corresponding increase in the volume of data generated. However, data sets are often becoming so sizable that analysing them manually is increasingly burdensome and unrealistic. Fortunately, we have also seen a corresponding rise in computing power and the capability of machine learning algorithms, which offer the possibility of performing some of the analysis required for PAM automatically. Nonetheless, the field of automatic detection of acoustic events is still in its infancy in biology and ecology. In this review, we examine the trends in bioacoustic PAM applications, and their implications for the burgeoning amount of data that needs to be analysed. We explore the different methods of machine learning and other tools for scanning, analysing, and extracting acoustic events automatically from large volumes of recordings. We then provide a step-by-step practical guide for using automatic detection in bioacoustics. One of the biggest challenges for the greater use of automatic detection in bioacoustics is that there is often a gulf in expertise between the biological sciences and the field of machine learning and computer science. Therefore, this review first presents an overview of the requirements for automatic detection in bioacoustics, intended to familiarise those from a computer science background with the needs of the bioacoustics community, followed by an introduction to the key elements of machine learning and artificial intelligence that a biologist needs to understand to incorporate automatic detection into their research. We then provide a practical guide to building an automatic detection pipeline for bioacoustic data, and conclude with a discussion of possible future directions in this field.