Alfred Wegener Institute for Polar and Marine Research
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High latitude observation of the Forbush decrease during the May 2024 solar storms with muon and neutron detectors on Svalbard
Get PDFDuring the series of intense solar flares and coronal mass ejections, that occurred in May 2024, a remarkable Forbush decrease in the cosmic ray flux was observed on the Earth. While this event was observed by particle detectors around the world, the archipelago of Svalbard was heavily exposed to it due to the weak geomagnetic shielding in the polar region. In this study, an analysis of the Forbush decrease event was carried out with a unique combination of muon and neutron detectors on Svalbard: at Ny-Alesund three scintillator-based muon telescopes of the Extreme Energy Events (EEE) project, 14 channels of a Bonner Sphere neutron Spectrometer (BSS), and thermal and epithermal neutron sensors used for hydrological monitoring; and, at Barentsburg, a high-energy neutron monitor operated by the Polar Geophysical Institute. Most sensors showed significant responses and correlation during the event. The observed relative magnitude of the Forbush decrease was found to depend on the detector’s energy sensitivity and was ~9% for thermal neutrons, ~8% for high-energy neutrons, and ~3% for muons. The uncertainty of these results strongly depends on factors like the count rate, which ranged from 10^1 to 10^5 cph and resulted in a low signal-to-noise ratio particularly for the BSS. These multi-particle and multi-energy observations provide an unprecendented view on the Earth’s exposure to cosmic rays during solar events
Unraveling the physiological and ultrastructural responses of wheat to combat cobalt stress and the protective role of Jania rubens related to antioxidant defense and cellular integrity
Get PDFCobalt (Co), while beneficial in trace amounts for biological systems, can severely impact plant growth at elevated levels in contaminated soils. This study investigated the physiological, biochemical and subcellular effects of Co toxicity on wheat (Triticum aestivum L.) and evaluated, for the first time, the protective potential of Jania rubens extract. The algal extract analysis demonstrated its rich content of amino acids, minerals, phytohormones, and fatty acids. Wheat seedlings were subjected to cobalt chloride (150 mM) irrigation, which was previously primed with either water or J. rubens extract. Co stress significantly impaired growth by reducing water content and essential nutrients (K, Mg, and Fe), leading to a 42.42 and 23.8% decrease, respectively, in root and shoot biomasses, a 9% reduction in photosynthetic efficiency, visible chlorosis, and root thickening. Stress exposure also induced oxidative damage, shown by 67.1% increase in hydrogen peroxide and a 170.1% rise in malondialdehyde content, accompanied by membrane leakage and reduced antioxidant enzyme activities. Ultrastructural analysis confirmed morphophysiological and biochemical disruptions at the cellular level. Priming with J. rubens extract significantly alleviated these effects by enhancing nutrient uptake, increasing root and shoot biomasses by 78.94% and 58.33%, respectively, reducing oxidative damage and maintaining cellular homeostasis. It also preserved chloroplast structure, nucleus, and cell wall microtubules, maintaining overall cellular integrity and antioxidant efficiency. Our findings demonstrate that Jania rubens extract offers a promising and novel biogenic strategy for enhancing wheat resilience to cobalt contamination through its nutritional and antioxidant properties.</jats:p
Microbes with higher metabolic independence are enriched in human gut microbiomes under stress
Get PDFA wide variety of human diseases are associated with loss of microbial diversity in the human gut, inspiring a great interest in the diagnostic or therapeutic potential of the microbiota. However, the ecological forces that drive diversity reduction in disease states remain unclear, rendering it difficult to ascertain the role of the microbiota in disease emergence or severity. One hypothesis to explain this phenomenon is that microbial diversity is diminished as disease states select for microbial populations that are more fit to survive environmental stress caused by inflammation or other host factors. Here, we tested this hypothesis on a large scale, by developing a software framework to quantify the enrichment of microbial metabolisms in complex metagenomes as a function of microbial diversity. We applied this framework to over 400 gut metagenomes from individuals who are healthy or diagnosed with inflammatory bowel disease (IBD). We found that high metabolic independence (HMI) is a distinguishing characteristic of microbial communities associated with individuals diagnosed with IBD. A classifier we trained using the normalized copy numbers of 33 HMI-associated metabolic modules not only distinguished states of health vs IBD, but also tracked the recovery of the gut microbiome following antibiotic treatment, suggesting that HMI is a hallmark of microbial communities in stressed gut environments.</jats:p
Immersion Exposure to Okadaic Acid Triggers Neurotoxic and Hepatotoxic Responses in Zebrafish Larvae (Danio rerio)
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Out of sight, but not out of mind: Key issues regarding seafloor macrolitter monitoring Issued by the expert community “International Seafloor Macrolitter Imaging and Quantification”
Get PDFFollowing a number of meetings devoted to knowledge sharing, identification of key issues, and discussing the best ways to move forward, a wide international expert community is now able to provide recommendations regarding the monitoring of seafloor macrolitter through observation and imaging. As the seafloor constitutes a major sink for marine litter including plastics, it is important to acquire robust and extensive data on litter distribution, abundance, types and size ranges across marine habitats. This should be done through widely agreed, harmonised, and non-destructive methods encompassing advanced technologies. Training and capacity building are essential elements in this endeavour. Both new and legacy imagery are needed to establish baseline assessments and trends. Informing policy-making is indispensable for effective action through upstream and targeted measures, with seafloor macrolitter (and megalitter) being a vital part of the evidence base for global mitigation measures
Hard-bottom communities in the deep Fram Strait: patterns, processes, and looming questions
Get PDFHard-bottom habitats, including dropstones and rocky reefs, increase habitat heterogeneity and host unique communities in the Fram Strait. This manuscript synthesizes research on the composition and dynamics of hard-bottom communities over HAUSGARTEN's 25 years, combining known patterns with previously unpublished data. Our research reveals that hard-bottom communities have high biodiversity, including taxa that have not yet been identified or described. Research on reproduction in hard-bottom taxa has been limited. For the most common hard-bottom species, which include sponges, soft corals, and anemones, larvae tend to settle near their parents. Hydroids have much broader-range dispersal and serve as pioneer species in the deep Fram Strait. Results from two novel recruitment experiments (2015–2024, 2019–2024), combined with results from two previous studies, show the process of succession in hard-bottom communities. Initial recruitment of hydroids was followed by tube worms, sponges, and cnidarians, leading to a strong increase in rarefied species richness and differences in species composition over time. Tracking of the hard-bottom fauna on marked stones showed negligible growth and 0–23 % mortality over 5 years (2019–2024). In summary, our research indicates that hard-bottom taxa in the deep Fram Strait have short-range larval dispersal, low recruitment, and slow growth. These characteristics suggest that hard-bottom communities have limited resilience to anthropogenic disturbance
Ice-proximal sea ice reconstruction in the Powell Basin, Antarctica, since the Last Interglacial
Get PDFIn Antarctica, the presence of sea ice not only plays a critical role in the climate system but also contributes to enhancing the stability of the floating ice shelves. Hence, investigating past ice-proximal sea ice conditions, especially across glacial–interglacial cycles, can provide crucial information pertaining to sea ice variability and deepen our understanding of ocean–ice–atmosphere dynamics and feedback. In this study, we apply a multiproxy approach, in combination with numerical climate modeling, to explore glacial–interglacial environmental variability. We analyze the novel sea ice biomarker IPSO25 (a di-unsaturated highly branched isoprenoid (HBI)), open-water biomarkers (tri-unsaturated HBIs; z-/e-trienes), and the diatom assemblage and primary productivity indicators in a marine sediment core retrieved from the Powell Basin, NW Weddell Sea. These biomarkers have been established as reliable proxies for reconstructing near-coastal sea ice conditions in the Southern Ocean (SO), where the typical use of sea-ice-related diatoms can be impacted by silica dissolution. We present the first continuous sea ice records, in close proximity to the Antarctic continental margin, since the penultimate deglaciation. Our data shed new light on the (seasonal) variability in sea ice in the basin and reveal a highly dynamic glacial–interglacial sea ice setting characterized by significant shifts from perennial ice cover to seasonal sea ice cover and an open marine environment over the last 145 kyr. Our results also unveil a stronger deglacial amplitude and warming during the Last Interglacial (LIG; Marine Isotope Stage (MIS) 5e) compared to the current one (Holocene). A short-term sea ice readvance also occurred towards the end of each deglaciation. Finally, despite similar findings between the proxy and model data, notable differences persist between both interglacials – emphasizing the necessity for different Antarctic ice sheet configurations to be employed and more robust paleoclimate data to enhance climate model performance close to the Antarctic continental margin
How to Reproduce in the Siberian Winter: Proteome Dynamics Reveals the Timing of Reproduction‐Related Processes in an Amphipod Species Endemic to Lake Baikal
Get PDFThe winters in the region of the vast global freshwater biodiversity hotspot Lake Baikal are extremely cold. Although the conditions for reproduction may seem unfavorable during winter, the lake is inhabited by a major endemic winter-reproducing amphipod species complex. Compared with Baikal's summer-reproducing amphipod species, the duration of a reproduction cycle in the winter-reproducing species is more extended. We hence hypothesized that in those species, reproduction-related processes dependent on external resources are scheduled to occur outside of winter when the conditions are more advantageous. To receive insights into the ongoing processes, we analyzed sex-specific seasonal proteome dynamics in Eulimnogammarus verrucosus as a representative of the winter-reproducing amphipod species. Individuals of the species were collected during five field samplings from the beginning of fall to the following summer (2019/2020) and their proteomes were analyzed. Especially, the female proteomes were dominated by sampling time point-specific hallmarks of reproduction-related processes and events. It was evident that the formation of the oocytes in female E. verrucosus already took place in the summer. Embryo development, not depending on external resources but fueled by the yolk reserves in the egg, proceeded over the winter, and juveniles hatched from the eggs in the following spring. Adjustments of the amphipods of both sexes to environmental winter conditions were reflected by abundance changes of digestive system-related enzymes, indicating a proteome response to seasonal diet changes, and of enzymes involved in RNA biosynthesis, protein folding, and homeoviscous adaptation processes, possibly related to decreasing water temperatures. The characteristics of the proteome dynamics revealed here, set in relation to season-specific environmental parameters, indicate a strategy of a cold-adapted amphipod to cope with the unique and extreme environmental conditions of Baikal, which is directed to the pace and timing of the resource-dependent reproduction-related processes
Earth Explorer 12 Candidate Mission CryoRad: Innovations in Sea Ice Observations
Get PDFCryoRad consists of a single satellite equipped with a broadband low-frequency microwave radiometer operating in the range 0.4 to 2 GHz with continuous frequency scanning. The CryoRad mission aims to produce key scientific data for advancing cryosphere studies. It will provide temperature profiles of Antarctic and Greenland ice sheets, extending from surface to base, a dataset previously available only through limited borehole observations. The mission will also address uncertainties in sea surface salinity (SSS) measurements in cold waters, overcoming limitations of current L-band radiometers. Furthermore, CryoRad will enhance estimates of sea ice thickness and deliver the first spaceborne observations of sea ice salinity.
In this presentation, we will discuss the potential impact of CryoRad measurements in determining sea ice properties and their benefits for ocean and climate modeling. Moreover we will provide information on uncertainties in determining sea ice parameters, focusing on simulations due to the limited availability of suitable measurements. Models of varying complexity, from one-dimensional thermodynamic sea-ice models to coupled ocean-sea-ice systems, will be used. The analysis will utilize new data from ECMWF’s ORAS6 ocean reanalysis, which includes a multicategory sea-ice model with prognostic salinity, as input for brightness temperature simulations.
ORAS6 will also serve as a baseline to examine the spatio-temporal co-variability of key geophysical parameters (e.g., sea ice concentration, thickness, and salinity) and their relationship to simulated brightness temperature observations. Special attention will be given to the new sea ice salinity forecast parameter in both hemispheres