ALBERT

Description: Pronounced glacial and interglacial climate cycles characterized northern ecosystems during the Pleistocene. Our understanding of the resultant community transformations and past ecological interactions strongly depends on the taxa found in fossil assemblages. Here, we present a shotgun metagenomic analysis of sedimentary ancient DNA (sedaDNA) to infer past ecosystem-wide biotic composition (from viruses to megaherbivores) from the Middle and Late Pleistocene at the Batagay megaslump, East Siberia. The shotgun DNA records of past vegetation composition largely agree with pollen and plant metabarcoding data from the same samples. Interglacial ecosystems at Batagay attributed to Marine Isotope Stage (MIS) 17 and MIS 7 were characterized by forested vegetation (Pinus, Betula, Alnus) and open grassland. The microbial and fungal communities indicate strong activity related to soil decomposition, especially during MIS17. The local landscape likely featured more open, herb-dominated areas, and the vegetation mosaic supported birds and small omnivorous mammals. Parts of the area were intermittently/partially flooded as suggested by the presence of water-dependent taxa. During MIS 3, the sampled ecosystems are identified as cold-temperate, periodically flooded grassland. Diverse megafauna (Mammuthus, Equus, Coelodonta) coexisted with small mammals (rodents). The MIS 2 ecosystems existed under harsher conditions, as suggested by the presence of cold-adapted herbaceous taxa. Typical Pleistocene megafauna still inhabited the area. The new approach, in which shotgun sequencing is supported by metabarcoding and pollen data, enables the investigation of community composition changes across a broad range of taxonomic groups and inferences about trophic interactions and aspects of soil microbial ecology.

Description: The study of environmental ancient DNA provides us with the unique opportunity to link environmental with ecosystem change over a millennial timescale. Paleorecords such as lake sediments contain genetic pools of past living organisms that are a valuable source of information to reconstruct how ecosystems were and how they changed in response to climate in the past. Here, we report on paleometagenomics of a sedimentary record in northern Siberia covering the past 6700 years. We integrated taxonomic with functional gene analysis, which enabled to shed light not only on community compositions but also on eco-physiological adaptations and ecosystem functioning. We reconstructed the presence of an open boreal forest 6700 years ago that over time was gradually replaced by tundra. This vegetation change had major consequences on the environmental microbiome, primarily enriching bacterial and archaeal ammonia oxidizers (e.g., Nitrospira, Nitrosopumilus, and Ca. Nitrosocosmicus) in the tundra ecosystem. We identified a core microbiome conserved through time and largely consisting of heterotrophic bacteria of the Bacteroidetes phylum (e.g., Mucilaginibacter) harboring numerous functional genes for degradation of plant-biomass and abiotic and biotic stress resistance. Archaea were also a key functional guild, involved in nitrogen and carbon cycling, not only methanogenesis but possibly also degradation of plant material via enzymes such as cellulases and amylases. Overall, the paleo-perspective offered by our study can have a profound impact on modern climate change biology, by helping to explain and predict the ecological interplay among multiple ecosystem levels based on past experiences.

Description: While basaltic volcanism is dominate during rifting and continental breakup, felsic magmatism may also comprise important components of some rift margins. During International Ocean Discovery Program (IODP) Expedition 396 on the continental margin of Norway, a graphite-garnet-cordierite bearing dacitic, pyroclastic unit was recovered within early Eocene sediments on Mimir High (Site U1570), a marginal high on the Vøring transform margin. Here, we present a comprehensive textural, mineralogical, and petrological study of the dacite in order to assess its melting origin and emplacement. The major mineral phases (garnet, cordierite, quartz, plagioclase, alkali feldspar) are hosted in a fresh rhyolitic, highly vesicular, glassy matrix, locally mingled with sediments. The xenocrystic major element chemistry of garnet and cordierite, the presence of zircon inclusions with inherited cores, and thermobarometric calculations all support a crustal metapelite origin. While most magma-rich margin models favor crustal anatexis in the lower crust, thermobarometric calculations performed here show that the dacite was produced at upper-crustal depths (〈 5 kbar) and high temperature (750–800 °C) with up to 3 wt% water content. In situ U-Pb analyses on zircon inclusions give a magmatic age of 54.6 ± 1.1 Ma, revealing the emplacement of the dacite post-dates the Paleocene-Eocene Thermal Maximum (PETM). Our results suggest that the opening of the North Atlantic was associated with a phase of low-pressure, high-temperature crustal melting at the onset of the main phase of magmatism.

Description: Scientists have long attempted to explain why closely similar age patterns of death are characteristic of highly diverse human and nonhuman populations. Historical efforts to identify a general "law of mortality" from these patterns that applied across species ended in 1935 when it was declared that such a law did not exist. These early efforts were conducted using mortality curves based on all causes of death. The authors predict that if comparisons of mortality are based instead on "intrinsic" causes of death (i.e., deaths that reflect the basic biology of the organism), then age patterns of mortality consistent with the historical concept of a law might be revealed. Using data on laboratory animals and humans, they demonstrate that age patterns of intrinsic mortality overlap when graphed on a biologically comparable time scale. These results are consistent with the existence of a law of mortality following sexual maturity, as originally asserted by Benjamin Gompertz and Raymond Pearl. The societal, medical, and research implications of such a law are discussed.

Description: The crises of climate change and biodiversity loss are interlinked and must be addressed jointly. A proposed solution for reducing reliance on fossil fuels, and thus mitigating climate change, is the transition from conventional combustion-engine to electric vehicles. This transition currently requires additional mineral resources, such as nickel and cobalt used in car batteries, presently obtained from land-based mines. Most options to meet this demand are associated with some biodiversity loss. One proposal is to mine the deep seabed, a vast, relatively pristine and mostly unexplored region of our planet. Few comparisons of environmental impacts of solely expanding land-based mining versus extending mining to the deep seabed for the additional resources exist and for biodiversity only qualitative. Here, we present a framework that facilitates a holistic comparison of relative ecosystem impacts by mining, using empirical data from relevant environmental metrics. This framework (Environmental Impact Wheel) includes a suite of physicochemical and biological components, rather than a few selected metrics, surrogates, or proxies. It is modified from the “recovery wheel” presented in the International Standards for the Practice of Ecological Restoration to address impacts rather than recovery. The wheel includes six attributes (physical condition, community composition, structural diversity, ecosystem function, external exchanges and absence of threats). Each has 3–5 sub attributes, in turn measured with several indicators. The framework includes five steps: (1) identifying geographic scope; (2) identifying relevant spatiotemporal scales; (3) selecting relevant indicators for each sub-attribute; (4) aggregating changes in indicators to scores; and (5) generating Environmental Impact Wheels for targeted comparisons. To move forward comparisons of land-based with deep seabed mining, thresholds of the indicators that reflect the range in severity of environmental impacts are needed. Indicators should be based on clearly articulated environmental goals, with objectives and targets that are specific, measurable, achievable, relevant, and time bound.

Description: The disturbance of marine organism phenology due to climate change and the subsequent effects on recruitment success are still poorly understood, especially in migratory fish species, such as the Atlantic herring (Clupea harengus; Clupeidae). Here we used the commercial catch data from a local fisher over a 50-year period (1971–2020) to estimate western Baltic spring-spawning (WBSS) herring mean arrival time Q50 (i.e., the week when 50% of the total fish catches had been made) at their spawning ground within the Kiel Fjord, southwest Baltic Sea, and the duration of the spawning season for each year. The relationship between the seawater temperature in the Kiel Bight and other environmental parameters (such as water salinity, North Atlantic and Atlantic multidecadal oscillations) and Q50 was evaluated using a general linear model to test the hypothesis that fish arrived earlier after warm than cold winters. We also estimated the accumulated thermal time to Q50 during gonadal development to estimate the effects of seawater temperature on the variations of Q50. The results of this study revealed a dramatic decrease in herring catches within the Kiel Fjord since the mid-1990s, as documented for the whole southwestern Baltic Sea. Warmer winter seawater temperature was the only factor related to an earlier arrival (1 week for one January seawater temperature degree increase) of herring at their spawning ground. The relationship was found for the first time on week 52 of the year prior to spawning and was the strongest (50% of the variability explained) from the fourth week of January (8 weeks before the mean Q50 among the studied years). A thermal constant to Q50 (~316°C day) was found when temperatures were integrated from the 49th week of the year prior to spawning. These results indicate that seawater temperature enhanced the speed of gonadal maturation during the latest phases of gametogenesis, leading to an early fish arrival under warm conditions. The duration of the spawning season was elongated during warmer years, therefore potentially mitigating the effects of trophic mismatch when fish spawn early. The results of this study highlight the altering effects of climate change on the spawning activity of a migratory fish species in the Baltic Sea where fast global changes presage that in other coastal areas worldwide

Description: The Banda Sea is of crucial importance for the circulation of the world's oceans, as it is part of the connection between the Pacific to the Indian Ocean. One peculiarity of the upper ocean hydrography in the Banda Sea is the occurrence of barrier layers. The regionality and temporal variability of barrier layer thickness (BLT) in the Banda Sea are examined in this study utilizing in-situ observations and ocean reanalysis output. It is found that a barrier layer occurs in over 90 % of the observational data profiles, and in over 72 % of those profiles, the BLT is shallower than 10 m. Furthermore, we find a seasonal cycle in BLT with a maximum thickness of about 60 m occurring during austral autumn and winter and coinciding with the presence of low saline waters fed by the regional river discharge and rainfall from the Java Sea and Makassar Strait. In addition, we identify the existence of a quasi-permanent anticyclonic circulation cell in the Banda Sea that may support the trapping of surface freshwater by retention. The anticyclonic circulation is most likely wind-driven because it coincides with the regional Ekman pumping pattern. Modulation of the anticyclone is via seasonal variability in the wind stress curl which in turn may explain the efficiency of freshwater retention and thus the BLT. The annual mean BLT distribution in the Banda Sea shows a preferential region of thickened barrier layers around 6o-8oS and 124o-126oE and resampling the pattern of the monthly mean climatology. Key Points: - First study estimating barrier layer thickness (BLT) in the Banda Sea using comprehensive observations - A quasi-permanent barrier layer exists in the Banda Sea with seasonal variation in occurrence and thickness - The intrusion of low saline waters and anticyclonic circulation are identified as the main mechanisms for creating and modulating the local BLT

Description: Key Points: - We reconstruct the temporal evolution of seawater isotope ratios of boron, strontium, lithium, and osmium over the last 65 million years - The evolution of seawater boron isotope ratio shows similarity to the evolution of strontium, lithium and osmium isotope ratios - Randomly drawn, smooth time series are provided for use in uncertainty propagation in calculation of palaeo pH The boron isotope ratio of seawater (δ11Bsw) is a parameter which must be known to reconstruct palaeo pH and CO2 from boron isotope measurements of marine carbonates. Beyond a few million years ago, δ11Bsw is likely to have been different to modern. Palaeo δ11Bsw can be estimated by simultaneously constraining the vertical gradients in foraminiferal δ11B (Δδ11B) and pH (ΔpH). A number of subtly different techniques have been used to estimate ΔpH in the past, all broadly based on assumptions about vertical gradients in oxygen, and/or carbon, or other carbonate system constraints. In this work we pull together existing data from previous studies, alongside a constraint on the rate of change of δ11Bsw from modeling. We combine this information in an overarching statistical framework called a Gaussian Process. The Gaussian Process technique allows us to bring together data and constraints on the rate of change in δ11Bsw to generate random plausible evolutions of δ11Bsw. We reconstruct δ11Bsw, and by extension palaeo pH, across the last 65Myr using this novel methodology. Reconstructed δ11Bsw is compared to other seawater isotope ratios, namely ,87/86 Sr, 187/188 Os , and δ7Li, which we also reconstruct with Gaussian Processes. Our method provides a template for incorporation of future δ11Bsw constraints, and a mechanism for propagation of uncertainty in δ11Bsw into future studies.

Description: The spectral composition of light is an important factor for the metabolism of photosynthetic organisms. Several blue light-regulated metabolic processes have already been identified in the industrially relevant microalga Monoraphidium braunii. However, little is known about the spectral impact on this species' growth, fatty acid (FA), and pigment composition. In this study, M. braunii was cultivated under different light spectra (white light: 400–700 nm, blue light: 400–550 nm, green light: 450–600 nm, and red light: 580–700 nm) at 25°C for 96 h. The growth was monitored daily. Additionally, the FA composition, and pigment concentration was analyzed after 96 h. The highest biomass production was observed upon white light and red light irradiation. However, green light also led to comparably high biomass production, fueling the scientific debate about the contribution of weakly absorbed light wavelengths to microalgal biomass production. All light spectra (white, blue, and green) that comprised blue-green light (450–550 nm) led to a higher degree of FA unsaturation and a greater concentration of all identified pigments than red light. These results further contribute to the growing understanding that blue-green light is an essential trigger for maximized pigment concentration and FA unsaturation in green microalgae.

Description: This article presents risk factors that are associated with the handling of unexploded ordnance (UXO) during explosive ordnance disposal (EOD) operations in German waters. The construction of offshore wind parks and the German immediate action program are expected to increase the number of EOD operations. Existing literature and guidelines do not offer a structured and reproducible framework for assessing EOD risk. To fill this gap, a network of EOD risk factors was developed by means of a literature review and validation via expert consultation. The study was scoped to “personnel and equipment at the EOD location” as the risk receptor and “undesired detonation” as the undesired event under investigation. Factors are subdivided into UXO factors that depend on the object that should be handled and factors that describe the object's surrounding environment. While the former can be researched by an EOD expert, the latter must be measured on site or acquired from a model. Each of these factors contributes to risk, some directly and others indirectly via other factors. The complexity of the resulting network, with its 33 factors, demonstrates the need for a reliable and reproducible model to quantify EOD risk. Its purpose is not to replace EOD experts but to aid them in their decision‐making process. Such a tool can provide valuable support for the high‐cost and high‐risk EOD operations.