New insights about the processes leading to marine extinction at the K-Pg boundary using a coupled biogeochemical-ecosystem model

2020 ◽  
Author(s):  
Le Hir Guillaume ◽  
fluteau fréderic ◽  
Hennequin Salome ◽  
Goddéris Yves
Keyword(s):  
Ecological Model ◽  
Abiotic Factors ◽  
Marine Organisms ◽  
Multiple Time Scales ◽  
Multiple Time ◽  
Ecosystem Structure ◽  
Deccan Volcanism ◽  
The Earth ◽  
Chicxulub Impact ◽  
The Impact

<p>If most experts agree that the Cretaceous-Paleogene (K-Pg) extinction (66 Ma) resulted from a combination of the Chicxulub impact and of Deccan volcanism, the chain of reactions (Bond and Wignall, 2014) leading to the extinction is not well constrained. <br> <br> In the present study, we use the GEOCLIM model to explore extreme perturbations induced by the two events and to investigate processes leading to the marine extinction. This state-of-the-art numerical tool (geoclimmodel.wordpress.com) includes in particular a marine ecological model in which food webs are simulated and marine organisms are sensitive to abiotic factors of their environment. The characteristics of each “species” of marine organisms, such as the tolerance to pH or temperature changes or the efficiency of predation, are randomly fixed to avoid any determinism in the response to the environmental perturbations. </p><p>  The response of the Earth system to the onset of Deccan traps and to the Chicxulub impact is explored by forcing the model with the most recent “eruptive sequences”  (Schoene et al., 2019, Sprain et al. 2019) and with the assumption of a pulse-like degassing (Chenet et al. 2009) sequence over 500 kyrs that includes CO2 and SO2. This new approach allows us to take into account the interplays between the sulfur and carbon cycles on multiple time scales (from year to 105  yrs) and to capture the model sensitivity to the uncertainties in atmospheric emissions (duration, timing, nature of gases, intensity of pulses, intensity of the impact).</p><p>  The coupled evolution of the Earth’s climate and oceanic geochemistry during the K-Pg boundary crisis will be presented. Without considering evolution processes, the biotic response (biomass and biodiversity) will be discussed with respect to the ecosystem structure existing before the perturbations. </p>

Time-scale dependent mechanism of atmospheric CO2 concentration drivers of watershed water-energy balance

2021 ◽  
Author(s):  
Jing Zhao
Keyword(s):  
Energy Balance ◽  
River Basin ◽  
Time Scales ◽  
Time Scale ◽  
Hydrological Processes ◽  
Multiple Time Scales ◽  
Multiple Time ◽  
The Wei River Basin ◽  
Balance Dynamics ◽  
The Impact

<p>The elevated atmospheric carbon dioxide concentration (CO<sub>2</sub>), as a key variable linking human activities and climate change, seriously affects the watershed hydrological processes. However, whether and how atmospheric CO<sub>2</sub> influences the watershed water-energy balance dynamics at multiple time scales have not been revealed. Based on long-term hydrometeorological data, the variation of non-stationary parameter n series in the Choudhury's equation in the mainstream of the Wei River Basin (WRB), the Jing River Basin (JRB) and Beiluo River Basin (BLRB), three typical Loess Plateau regions in China, was examined. Subsequently, the Empirical Mode Decomposition method was applied to explore the impact of CO<sub>2</sub> on watershed water-energy balance dynamics at multiple time scales. Results indicate that (1) in the context of warming and drying condition, annual n series in the WRB displays a significantly increasing trend, while that in the JRB and BLRB presents non-significantly decreasing trends; (2) the non-stationary n series was divided into 3-, 7-, 18-, exceeding 18-year time scale oscillations and a trend residual. In the WRB and BLRB, the overall variation of n was dominated by the residual, whereas in the JRB it was dominated by the 7-year time scale oscillation; (3) the relationship between CO<sub>2 </sub>concentration and n series was significant in the WRB except for 3-year time scale. In the JRB, CO<sub>2 </sub>concentration and n series were significantly correlated on the 7- and exceeding 7-year time scales, while in the BLRB, such a significant relationship existed only on the 18- and exceeding 18-year time scales. (4) CO<sub>2</sub>-driven temperature rise and vegetation greening elevated the aridity index and evaporation ratio, thus impacting watershed water-energy balance dynamics. This study provided a deeper explanation for the possible impact of CO<sub>2</sub> concentration on the watershed hydrological processes.</p>

scholarly journals Biotic vs. abiotic forcing on plankton assemblages varies with season and size class in a large temperate estuary

2020 ◽  
Vol 42 (2) ◽  
pp. 221-237 ◽  
Author(s):  
Gretchen Rollwagen-Bollens ◽  
Stephen Bollens ◽  
Eric Dexter ◽  
Jeffery Cordell
Keyword(s):  
Community Dynamics ◽  
Abiotic Factors ◽  
River Estuary ◽  
Multiple Time Scales ◽  
Nutrient Concentrations ◽  
Winter Period ◽  
Zooplankton Abundance ◽  
Multiple Time ◽  
P Availability ◽  
Lower Estuary

Abstract Large river estuaries experience multiple anthropogenic stressors. Understanding plankton community dynamics in these estuaries provides insights into the patterns of natural variability and effects of human activity. We undertook a 2-year study in the Columbia River Estuary to assess the potential impacts of abiotic and biotic factors on planktonic community structure over multiple time scales. We measured microplankton and zooplankton abundance, biomass and composition monthly, concurrent with measurements of chlorophyll a, nutrient concentrations, temperature and salinity, from a dock in the lower estuary. We then statistically assessed the associations among the abundances of planktonic groups and environmental and biological factors. During the late spring high flow period of both years, the lower estuary was dominated by freshwater and low salinity-adapted planktonic taxa, and zooplankton grazers were more strongly associated with the autotroph-dominated microplankton assemblage than abiotic factors. During the early winter period of higher salinity and lower flow, nutrient (P) availability exerted a strong influence on microplankton taxa, while only temperature and upwelling strength were associated with the zooplankton assemblage. Our results indicate that the relative influence of biotic (grazers) and abiotic (salinity, flow, nutrients and upwelling) factors varies seasonally and inter-annually, and among different size classes in the estuarine food web.

scholarly journals Characterizing the contribution of high temperatures to child undernourishment in Sub-Saharan Africa

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Rachel E. Baker ◽  
Jesse Anttila-Hughes
Keyword(s):  
High Temperatures ◽  
Low Income ◽  
Child Nutrition ◽  
Negative Relationship ◽  
Sub Saharan Africa ◽  
Eastern Africa ◽  
Multiple Time Scales ◽  
Multiple Time ◽  
Sub Saharan ◽  
The Impact

Abstract Despite improvements to global economic conditions, child undernourishment has increased in recent years, with approximately 7.5% of children suffering from wasting. Climate change is expected to worsen food insecurity and increase potential threats to nutrition, particularly in low-income and lower-middle income countries where the majority of undernourished children live. We combine anthropometric data for 192,000 children from 30 countries in Sub-Saharan Africa with historical climate data to directly estimate the effect of temperature on key malnutrition outcomes. We first document a strong negative relationship between child weight and average temperature across regions. We then exploit variation in weather conditions to statistically identify the effects of increased temperatures over multiple time scales on child nutrition. Increased temperatures in the month of survey, year leading up to survey and child lifetime lead to meaningful declines in acute measures of child nutrition. We find that the lifetime-scale effects explain most of the region-level negative relationship between weight and temperature, indicating that high temperatures may be a constraint on child nutrition. We use CMIP5 local temperature projections to project the impact of future warming, and find substantial increases in malnutrition depending on location: western Africa would see a 37% increase in the prevalence of wasting by 2100, and central and eastern Africa 25%.

Exploring the role of lags and legacies in the productivity of Australian ecosystems

2021 ◽  
Author(s):  
Jon Page ◽  
Martin De Kauwe ◽  
Gab Abramowitz
Keyword(s):  
Climate Change ◽  
Climate Extremes ◽  
Multiple Time Scales ◽  
Plant Responses ◽  
Multiple Time ◽  
Legacy Effects ◽  
Ecological Memory ◽  
Using Data ◽  
The Impact

<p>The vegetation’s response to climate change is a major source of uncertainty in terrestrial biosphere model (TBM) projections. Constraining carbon cycle feedbacks to climate change requires improving our understanding of both the direct plant physiological responses to global change, as well as the role of legacy effects (e.g. reductions in plant growth, damage to the plant’s hydraulic transport system), that drive multi-timescale feedbacks. In particular, the role of these legacy effects - both the timescale and strength of the memory effect - have been largely overlooked in the development of model hypotheses. This is despite the knowledge that plant responses to climatic drivers occur across multiple time scales (seconds to decades), with the impact of climate extremes (e.g. drought) resonating for many years. Using data from 13 eddy covariance sites, covering two rainfall gradients in Australia, in combination with a hierarchical Bayesian model, we characterised the timescales of influence of antecedent drivers on fluxes of net carbon exchange and evapotranspiration. Using our data assimilation approach we were able to partition the influence of ecological memory into both biological and environmental components. Overall, we found that the importance of ecological memory to antecedent conditions increased as water availability declines. Our results therefore underline the importance of capturing legacy effects in TBMs used to project responses in water limited ecosystems.</p>

Excitations of the Earth and Mars’ Variable Rotations by Surficial Fluids

2020 ◽  
Author(s):  
Yonghong Zhou ◽  
Xueqing Xu ◽  
Cancan Xu ◽  
Jianli Chen ◽  
David Salstein
Keyword(s):  
Angular Momentum ◽  
Multiple Time Scales ◽  
Global Dynamics ◽  
Multiple Time ◽  
Earth System ◽  
Polar Ice ◽  
Dynamic Interactions ◽  
Ice Caps ◽  
The Earth ◽  
Atmospheric Excitation

<p>The dynamic interactions that occur between the solid Earth and surficial fluids are related globally by conservation of angular momentum in the Earth system. Owing to this condition, the surficial fluids have shown to be main excitation sources of the Earth’s variable rotation on timescales between a few days and several years. Likewise, the Mars’ rotation changes due to variations of atmospheric circulation and surface pressure, and the variable Martian polar ice caps associated with the CO<sub>2</sub> sublimation/condensation effects. Investigations of the Earth and Mars’ rotations by surficial fluids may further our understandings of the Earth and planetary global dynamics. Here, we present our recent progresses on excitations of the Earth and Mars’ rotational variations on multiple time scales: (1) differences between the NCEP/NCAR and ECMWF atmospheric excitation functions of the Earth’s rotation, and (2) the Mars’ rotational variations and the dust cycles during the Mars Years 24-31.</p>

scholarly journals The Price of Fame: The Impact of Stimulus Familiarity on Proactive Interference Resolution

2011 ◽  
Vol 23 (4) ◽  
pp. 816-831 ◽  
Author(s):  
Ranjani Prabhakaran ◽  
Sharon L. Thompson-Schill
Keyword(s):  
Proactive Interference ◽  
Memory Retrieval ◽  
Recognition Task ◽  
Multiple Time Scales ◽  
Multiple Time ◽  
Short Term ◽  
Stimulus Familiarity ◽  
Resolution Processes ◽  
The Impact

Interference from previously learned information, known as proactive interference (PI), limits our memory retrieval abilities. Previous studies of PI resolution have focused on the role of short-term familiarity, or recency, in causing PI. In the present study, we investigated the impact of long-term stimulus familiarity on PI resolution processes. In two behavioral experiments and one event-related fMRI experiment, long-term familiarity was manipulated through the use of famous and nonfamous stimuli, and short-term familiarity was manipulated through the use of recent and nonrecent probe items in an item recognition task. The right middle frontal gyrus demonstrated greater sensitivity to famous stimuli, suggesting that long-term stimulus familiarity plays a role in influencing PI resolution processes. Further examination of the effect of long-term stimulus familiarity on PI resolution revealed a larger behavioral interference effect for famous stimuli, but only under speeded response conditions. Thus, models of memory retrieval—and of the cognitive control mechanisms that guide retrieval processes—should consider the impact of and interactions among sources of familiarity on multiple time scales.

Deccan Volcanism or the Chicxulub Impact: The Chicken or Egg Question

2020 ◽  
Author(s):  
Gerta Keller
Keyword(s):  
Mass Extinction ◽  
Impact Crater ◽  
Global Climate ◽  
Mass Extinctions ◽  
Deccan Volcanism ◽  
Asteroid Impact ◽  
Global Climate Warming ◽  
Chicxulub Impact Crater ◽  
Chicxulub Impact ◽  
The Impact

<p>The Cretaceous–Paleogene boundary (KTB or KPB) mass extinction is primarily known for the<br>demise of the dinosaurs, the Chicxulub impact, and the rancorous forty-year-old controversy<br>over the cause of this mass extinction. For the first 30 years, the controversy primarily revolved<br>around the age of the impact claimed as precisely KTB based on the assumption that it caused<br>the mass extinction. The iridium (Ir) anomaly at the KTB was claimed proof of the asteroid<br>impact, but no Ir was ever associated with impact evidence and recent findings reveal no<br>extraterrestrial component in PGEs or the KTB Ir anomaly. Impact melt rock glass spherules are<br>also claimed as indisputable evidence of the KTB age impact, but such spherule layers are<br>commonly reworked from the primary (oldest) layer in late Maastrichtian, KTB and Danian<br>sediments; thus only the oldest impact spherule layer documented near the base of zone CF1<br>~200 ky below the KTB can approximate the impact’s age. Similarly, the impact breccia in the<br>Chicxulub impact crater predates the KTB. The best age derived from Ar/Ar dating of impact<br>glass spherules is within 200 ky of the KTB and thus no evidence for the KTB age. All evidence<br>strongly suggests the Chicxulub impact most likely predates the mass extinction ~ 200 ky and<br>played no role in it.<br>Deccan volcanism (LIP) was dismissed as potential cause or even contributor to the KTB mass<br>extinction despite the fact that all other mass extinctions are associated with Large Igneous<br>Province (LIP) volcanism but none with an asteroid impact. During the last decade, Deccan<br>volcanism gained credence based on a succession of discoveries: 1) the mass extinction in<br>between the longest Deccan lava flows across India; 2) high-precision dating of the entire<br>sequence of Deccan volcanism based on UPb zircon dating; 3) recognition of four distinct<br>eruption pulses all related to global climate warming with the largest pulse beginning 20 ky prior<br>to and ending at the KTB; 4) Identifying the climate link to Deccan volcanism based on age<br>dating and mercury from Deccan eruptions in marine sediments; and 5) Identifying the KTB<br>mass extinction directly related to the major Deccan eruption pulse, hyperthermal warming and<br>ocean acidification all linked to global mercury fallout from Deccan eruptions in marine<br>sediments. Despite this remarkable culmination of evidence, the controversy continues with<br>impact proponents arguing that Deccan volcanism didn’t exist at the KTB – the impact was the<br>sole cause.</p>

scholarly journals Damage Monitoring in Woven Composites Using Fiber-Bragg Grating Sensors on Multiple Time Scales

2008 ◽  
Author(s):  
Adam Propst ◽  
Adam Parker ◽  
Zachary Capps ◽  
Kara Peters ◽  
Mohammed A. Zikry
Keyword(s):  
Fiber Bragg Grating ◽  
Time Scales ◽  
Sensor Response ◽  
Multiple Time Scales ◽  
Bragg Grating ◽  
Multiple Time ◽  
Low Velocity ◽  
Fbg Sensor ◽  
The Impact ◽  
Impact Events

Low-velocity impact events occurring over the span of a few milliseconds cause changes in composite structures through relaxation and delamination propagation which manifest themselves over the span of several seconds. Changes in embedded fiber Bragg grating sensor response allow the damage in the composite structure to be measured in lieu of simply analyzing the impact event itself. By observing the damage progression and subsequent failure of the sample, the sensor signal response can thus be used to predict the lifetime of the structure. In this paper, we expand previous sensor interrogation and damage identification methodologies by using scanning instrumentation capable of operating over multiple time scales. 2D woven composite specimens are subjected to multiple low velocity impacts while the fiber Bragg grating (FBG) sensor response is monitored in time scales of one millisecond to tens of seconds. A high frequency scanning spectrometer is used to determine the peak Bragg wavelength while scanning the FBG sensor at approximately 1 kHz during and immediately after the impact. Also, a high fidelity slow-scan laser source measures the quasi-static sensor response several seconds to minutes following the impact events. Features of the two measurement sets are used to identify the structural integrity of the laminate specimen after each impact event.

scholarly journals The Boltysh impact structure: An early Danian impact event during recovery from the K-Pg mass extinction

2021 ◽  
Vol 7 (25) ◽  
pp. eabe6530
Author(s):  
Annemarie E. Pickersgill ◽  
Darren F. Mark ◽  
Martin R. Lee ◽  
Simon P. Kelley ◽  
David W. Jolley
Keyword(s):  
Mass Extinction ◽  
Crater Lake ◽  
Temporal Association ◽  
Earth System ◽  
Impact Event ◽  
The Earth ◽  
Relationship Of ◽  
Chicxulub Impact ◽  
The Impact ◽  
Impact Events

Both the Chicxulub and Boltysh impact events are associated with the K-Pg boundary. While Chicxulub is firmly linked to the end-Cretaceous mass extinction, the temporal relationship of the ~24-km-diameter Boltysh impact to these events is uncertain, although it is thought to have occurred 2 to 5 ka before the mass extinction. Here, we conduct the first direct geochronological comparison of Boltysh to the K-Pg boundary. Our 40Ar/39Ar age of 65.39 ± 0.14/0.16 Ma shows that the impact occurred ~0.65 Ma after the mass extinction. At that time, the climate was recovering from the effects of the Chicxulub impact and Deccan trap flood volcanism. This age shows that Boltysh has a close temporal association with the Lower C29n hyperthermal recorded by global sediment archives and in the Boltysh crater lake sediments. The temporal coincidence raises the possibility that even a small impact event could disrupt recovery of the Earth system from catastrophic events.

scholarly journals Measuring Behavior in the Home Cage: Study Design, Applications, Challenges, and Perspectives

2021 ◽  
Vol 15 ◽  
Author(s):  
Fabrizio Grieco ◽  
Briana J. Bernstein ◽  
Barbara Biemans ◽  
Lior Bikovski ◽  
C. Joseph Burnett ◽  
...  
Keyword(s):  
Home Cage ◽  
Fine Tuning ◽  
Multiple Time Scales ◽  
Multiple Time ◽  
Human Interference ◽  
Working Definition ◽  
Unambiguous Tracking ◽  
Spontaneous Behavior ◽  
Replication Crisis ◽  
The Impact

The reproducibility crisis (or replication crisis) in biomedical research is a particularly existential and under-addressed issue in the field of behavioral neuroscience, where, in spite of efforts to standardize testing and assay protocols, several known and unknown sources of confounding environmental factors add to variance. Human interference is a major contributor to variability both within and across laboratories, as well as novelty-induced anxiety. Attempts to reduce human interference and to measure more "natural" behaviors in subjects has led to the development of automated home-cage monitoring systems. These systems enable prolonged and longitudinal recordings, and provide large continuous measures of spontaneous behavior that can be analyzed across multiple time scales. In this review, a diverse team of neuroscientists and product developers share their experiences using such an automated monitoring system that combines Noldus PhenoTyper® home-cages and the video-based tracking software, EthoVision® XT, to extract digital biomarkers of motor, emotional, social and cognitive behavior. After presenting our working definition of a “home-cage”, we compare home-cage testing with more conventional out-of-cage tests (e.g., the open field) and outline the various advantages of the former, including opportunities for within-subject analyses and assessments of circadian and ultradian activity. Next, we address technical issues pertaining to the acquisition of behavioral data, such as the fine-tuning of the tracking software and the potential for integration with biotelemetry and optogenetics. Finally, we provide guidance on which behavioral measures to emphasize, how to filter, segment, and analyze behavior, and how to use analysis scripts. We summarize how the PhenoTyper has applications to study neuropharmacology as well as animal models of neurodegenerative and neuropsychiatric illness. Looking forward, we examine current challenges and the impact of new developments. Examples include the automated recognition of specific behaviors, unambiguous tracking of individuals in a social context, the development of more animal-centered measures of behavior and ways of dealing with large datasets. Together, we advocate that by embracing standardized home-cage monitoring platforms like the PhenoTyper, we are poised to directly assess issues pertaining to reproducibility, and more importantly, measure features of rodent behavior under more ethologically relevant scenarios.

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