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Multiple sources of atmospheric CO2 activated by AMOC recovery at the onset of interglacial MIS 9
No full textUsing high-precision ice core measurements of CO 2 , δ 13 C–CO 2 , CH 4 , and N 2 O, this study provides carbon isotope constraints on a sizeable, centennial-scale CO 2 jump at the onset of Marine Isotope Stage 9 (MIS 9). The very end of the Heinrich stadial (HS) characterizing Termination IV (T-IV, ca. 343 to 333 ka ago) shows a 250-y-long jump in greenhouse gas concentrations, followed by a 1.3 ka gradual decline back to the initial concentration. During this so-called overshoot, CO 2 and CH 4 reach their highest levels (about 303 ppm and 800 ppb, respectively) over the past 800 ka prior to industrialization. The jump in CO 2 is not accompanied by a change in δ 13 C–CO 2, suggesting that multiple mechanisms contributed to the exceptionally elevated CO 2 values. Following the jump, a slow 0.2‰ enrichment in δ 13 C–CO 2 occurs. We propose that during the jump, the sudden resumption of deepwater formation in the North Atlantic (NA) triggered an amplified release of CO 2 from the Southern Ocean (SO) by a northward shift of the Intertropical Convergence Zone (ITCZ) and the SO westerlies, potentially in combination with a rapid land carbon release. The latter is expected from temporally enhanced wildfire activity related to higher fuel load and regionally changing weather conditions in connection to the ITCZ shift. A combination of marine proxy records and box model simulation suggests that the δ 13 C–CO 2 decrease expected from these processes is compensated by a net temperature increase in global sea surface temperature (SST) at the time of the AMOC resumption
Individual mechanical energy expenditure regimens vary seasonally with weather, sex, age and body condition in a generalist carnivore population: support for inter-individual tactical diversity
Get PDFDiverse individual energy-budgeting tactics within wild populations provide resilience to natural fluctuations in food availability and expenditure costs. Although substantial heterogeneity in activity-related energy expenditure has been documented, few studies differentiate between responses to the environment and inter-individual differences stemming from life history, allometry, or somatic stores. Using tri-axial accelerometry, complemented by diet analysis, we investigated inter-individual within-season variation in overall dynamic body acceleration (ODBA; activity intensity measure) and “Activity” (above an ODBA threshold) in a high-density population of European badgers (Meles meles). Weather (including wind speed) affected ODBA and activity according to predictors of earthworm (food) availability and cooling potential. In spring, maximal ODBA expenditure at intermediate rainfall and temperature values suggested that badgers traded foraging success against thermoregulatory losses, where lower-condition badgers maintained higher spring ODBA irrespective of temperature while badgers in better body condition reduced ODBA at colder temperatures. Conversely, in summer, lower-condition badgers modulated ODBA according to temperature, likely in response to super-abundant food supply. Between 35% (spring, summer) and 57% (autumn) of residual total daily ODBA variance related to inter-individual differences unexplained by seasonal predictors, suggesting within-season tactical activity typologies. We propose that this heterogeneity among individual energy-expenditure profiles may contribute to population resilience under rapid environmental change
Penetration of groundwater into crystalline rocks
No full textThe extent to which crystalline rocks formed at high temperatures become infiltrated by groundwater during prolonged residence near the earth’s surface is evaluated. The study was carried out because rock matrix diffusion, defined as diffusion through pore water in crystalline rocks, has been proposed to facilitate the dispersal of radionuclides from buried waste. This assumes that rocks are water-saturated, but ubiquitous granite minerals such as biotite are not stable at low temperatures in the presence of water, irrespective of water composition. Nevertheless, the filling of almost all pores in a 3-mm-diameter core of fine-grained granite over 7 days was demonstrated by in situ X-ray computed tomography. Water infiltration could be inhibited by the formation of reaction products if granite reacted with the water, which was investigated using polished granite cores to facilitate observation of reaction products and etch pits. After 4 weeks at a temperature of 50 °C, etch pits in biotite and plagioclase and small secondary platelets on biotite were observed. At higher temperatures of 100 and 150 °C, secondary growths became more pronounced. To provide a natural analogue of possible water penetration, the history of the Mountsorrel Granite in the UK was examined. Despite > 300 Ma of residing within a few kilometers of the surface, the rock has fresh primary minerals, except for areas very close to spaced joints. Infiltration of groundwater into granite takes place along fractures but penetration of the matrix porosity is strongly inhibited, probably by secondary minerals resulting from hydration reactions
Global health impacts of PAHs based on high-resolution modeling by dynamic simulation and relative emission downscaling
Get PDFPolycyclic aromatic hydrocarbons (PAHs) are one of the highly toxic pollutants that require strict control. High-resolution distribution of PAHs is crucial for accurately quantifying their population exposure levels. However, due to the high computational cost, few models applying the dynamical approach could simulate global PAHs to evaluate health effects with resolution down to 1–10 km. This study simulated the global distribution of PAHs by combining the IAP-AACM model with a nonlinear downscaling method based on relative anthropogenic emissions and observations. A global high-resolution (0.1° × 0.1°, ∼10 km in middle latitudes) dataset of Benzo[a]pyrene (BaP, the most representative PAHs) in 2013 and 2018 is generated to support exposure studies. The 0.1° × 0.1° results are comparable to the nested simulation and have better consistency with observations than that of the 1° × 1° simulation. The 0.1° × 0.1° estimation shows significantly higher population-weighted total incremental lifetime cancer risks (PTILCR), with an increase larger than 50 %, compared to the 1° × 1° simulation. The PTILCR is greatly higher in winter than in other seasons and it is larger for children and young adults than for adolescents and seniors. The study has significant implications for the reliable assessment of global health risks of PAHs and the development of scientific management strategies for different age groups
The pick of the plot: an evidence‐based approach for selecting and testing suitable plants to use in annual seed mixes to attract insect pollinators
Get PDF•Annual seed mixes are frequently grown in gardens and urban areas because they are considered to be ‘pollinator-friendly’, but choice of which plant species to include is often based on anecdotal evidence. Here, we build an evidence-base for which plants to use in annual seed mixes to attract bumblebees, solitary bees and hoverflies. We conduct a systematic review of plant–insect interactions and use field trials to assess the attractiveness of different seed mixtures.
•We determined which annual plant species are attractive to bees and hoverflies using interaction data extracted from 447 peer-reviewed articles. We then carried out field trials using four commercially available seed mixes to assess insect visitation. The plant list compiled from the literature and the results of the commercial trials were used to develop two novel experimental seed mixes that were assessed for insect visitation and aesthetic appeal.
•We found that seed mixes including non-native, along with native flowering plants, had higher establishment, a longer flowering period, a greater number of pollinator visits and were more aesthetically pleasing to the public. A small number of key plant species were visited frequently in the seed mixes, and these differ between pollinator groups.
•Our findings can be used to provide evidence-based guidance in the selection of plant species to be used in horticultural areas
Setting off on the right path: make your research regulatory relevant
Get PDFScientifically well-established methods do not automatically get used in regulations. Even when there is an urgent need for regulatory relevant test methods, methods need to pass through a so-called standardization process. This involves following specific agreed processes, which define the timeline and requirements (e.g., validation, documentation, approval) before the method can be integrated in regulatory oriented standards or Test Guidelines from the Organization of Economic Cooperation and Development (OECD). The process is often seen as too complex or too resource (and time) consuming by the scientific community, which inhibits method developers from translating their scientific methods and protocols into standards or OECD Test Guidelines. Numerous incentives exist for scientists to be (more) active in the standardization process and allow regulation to keep up with new scientific developments. These include an increase in research impacts, an expansion and diversification of the international expert network, and an access to more fundings. This paper shows scientists how to reach such outcomes, by providing guidance on how to navigate successfully through the standards and OECD Test Guidelines development processes. Especially the requirements for method validation, which is a prerequisite in this process and common across the different standardization bodies. For further details and insights, readers are invited to consult the various freely available resources generated by the NanoHarmony EU project. These are compiled in the OECD Test Guideline Process Mentor ( https://testguideline-development.org/ ). The active participation of scientists along the entire process toward standards and OECD Test Guidelines is key. Only then can their methods be expanded into a wider, regulatory application toward a safer world
Tropical response to ocean circulation slowdown raises future drought risk
No full textProjections of tropical rainfall under global warming remain highly uncertain, largely because of an unclear climate response to a potential weakening of the Atlantic meridional overturning circulation (AMOC). Although an AMOC slowdown can substantially alter tropical rainfall patterns, the physical mechanisms linking high-latitude changes to tropical hydroclimate are poorly understood. Here we demonstrate that an AMOC slowdown drives widespread shifts in tropical rainfall through the propagation of high-latitude cooling into the tropical North Atlantic. We identify and validate this mechanism using climate model simulations and palaeoclimate records from Heinrich Stadial 1 (HS1)—a past period marked by pronounced AMOC weakening. In models, prevailing easterly and westerly winds communicate the climate signal to the Pacific Ocean and Indian Ocean through the transport of cold air generated over the tropical and subtropical North Atlantic. Air–sea interactions transmit the response across the Pacific Ocean and Indian Ocean, altering rainfall patterns as far as Indonesia, the tropical Andes and northern Australia. A similar teleconnection emerges under global warming scenarios, producing a consistent multi-model pattern of tropical hydroclimatic change. These palaeo-validated projections show widespread drying across Mesoamerica, the Amazon and West Africa, highlighting an elevated risk of severe drought for vulnerable human and ecological systems
Sex‐Dependent Influence of Major Histocompatibility Complex Diversity on Fitness in a Social Mammal
Get PDFParasite infections affect males and females differently across a wide range of species, often due to differences in immune responses. Generally, females tend to have stronger immune defences and lower parasite loads than males. The major histocompatibility complex (MHC) plays a crucial role in the adaptive immune response, and extensive research has explored how variation in this region influences infection and fitness outcomes. However, studies of sex‐specific relationships between MHC variation and infection are scarce, perhaps because MHC genes are located on the autosomes, which are shared by both sexes. Here, we provide evidence of sexually antagonistic selection in a wild, group‐living mammal—the banded mongoose. Using genetic and life history data collected from over 300 individuals across 25 years, we found that both MHC class I (MHC‐I) and MHC class II (MHC‐II) diversity influence lifetime reproductive success differently in males and females. Specifically, higher MHC diversity is linked to increased fitness in males but decreased fitness in females. Furthermore, MHC diversity did not differ between the sexes, indicating an unresolved genetic sexual conflict. Our findings demonstrate that sexually antagonistic selection acts on the MHC and may operate across both MHC classes but differently. This study contributes to the growing body of evidence that sex is a significant factor in shaping host immunity and fitness
Tempo of the Late Ordovician mass extinction controlled by the rate of climate change
Get PDFThe Late Ordovician mass extinction (LOME) included two phases (I and II) of high species turnover that have been hypothetically linked to the Hirnantian glaciation and subsequent rapid warming, respectively. However, the timing and tempo of the LOME remain uncertain, which hinders our understanding of the feedback between the LOME and paleoclimatic change. Here, we present high-precision radioisotopic dates for the Ordovician-Silurian transition in South China that reveal the LOME began at 442.76 + 0.35/−0.22 million years ago, with the two phases lasting for 0.34 + 0.46/−0.34 and 0.06 + 0.31/−0.06 million years, respectively. The rapid switch from icehouse to greenhouse conditions, along with the higher mean rate of temperature change during LOME II, resulted in a much higher mean extinction rate during LOME II than I (71.6% versus 8.4% species loss per 100 thousand years, respectively), implying that the rate of climate change was a primary control on the tempo of the LOME
Biological invasions: a global assessment of geographic distributions, long‐term trends, and data gaps
No full textBiological invasions are one of the major drivers of biodiversity decline and have been shown to have far‐reaching consequences for society and the economy. Preventing the introduction and spread of alien species represents the most effective solution to reducing their impacts on nature and human well‐being. However, implementing effective solutions requires a good understanding of where the species are established and how biological invasions develop over time. Knowledge of the status and trends of biological invasions is thus key for guiding research efforts, informing stakeholders and policymakers, for targeted management efforts, and preparing for the future. However, information about the status and trends of alien species is scattered, patchy, and highly incomplete, making it difficult to assess. Published reports for individual regions and taxonomic groups are available, but large‐scale overviews are scarce. A global assessment therefore requires a review of available knowledge with careful consideration of sampling and reporting biases. This paper provides a comprehensive global assessment of the status and trends of alien species for major taxonomic groups [Bacteria, Protozoa, Stramenopila, Alveolata, and Rhizaria (SAR), fungi, plants, and animals] for Intergovernmental Panel of Biodiversity and Ecosystem Services (IPBES) regions.
The review provides irrefutable evidence that alien species have been introduced to all regions worldwide including Antarctica and have spread to even the most remote islands. The numbers of alien species are increasing within all taxa and across all regions, and are often even accelerating. Large knowledge gaps exist, particularly for taxonomic groups other than vascular plants and vertebrates, for regions in Africa and Central Asia, and for aquatic realms. In fact, for inconspicuous species, such as Bacteria, Protozoa, and to some degree SAR and fungi, we found records for very few species and regions. Observed status and trends are thus highly influenced by research effort. More generally, it is likely that all lists for alien species of any taxonomic group and region are incomplete. The reported species numbers therefore represent minima, and we can expect additions to all lists in the near future. We identified six key challenges which need to be addressed to reduce knowledge gaps and to improve our ability to assess trends and status of biological invasions
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