scholarly journals Planktic foraminiferal response to an early Paleocene transient warming event and biostratigraphic implications

2021 ◽  
Author(s):  
André Bornemann ◽  
Sofie Jehle ◽  
Friederike Lägel ◽  
Arne Deprez ◽  
Maria Rose Petrizzo ◽  
...  
Keyword(s):  
Time Scales ◽  
Environmental Changes ◽  
Global Scale ◽  
Global Changes ◽  
Calcareous Nannofossils ◽  
Planktic Foraminifera ◽  
Orbital Parameters ◽  
The North ◽  
Long Run ◽  
Early Paleocene

AbstractThe Latest Danian Event (LDE, ~ 62.2 Ma) is characterized by global changes in the carbon cycle as indicated by two negative δ13C excursions of up to ~ 1‰. These δ13C shifts are accompanied by a 2–3 °C warming of both surface and deep waters based on benthic and planktic foraminiferal δ18O measurements, and the LDE has, thus, been considered as a so-called hyperthermal event. The event lasted for 200 kyr and has been identified in various ocean basins and shallow marine settings. Here, we present a compilation of data from three deep-sea cores covering the Pacific, North and South Atlantic oceans as well as a southern Tethyan shelf section to document the response of planktic foraminifera assemblages to ocean warming. In all studied successions, we observe the disappearance of the planktic foraminifer genus Praemurica on a global scale that took place close to the onset of the LDE. Moreover, on the long run, praemuricids were contemporaneously replaced by morozovellids. Both the decline of Praemurica and a temperature increase started between 200 and 260 kyr before the LDE onset and were punctuated by the LDE itself. In this paper, we propose two mechanisms that have controlled the environmental changes associated with this event, (1) increased activity of the North Atlantic Igneous Province acting on long time-scales, and (2) changes of orbital parameters resulting in insolation changes on shorter time-scales.In contrast to a proposed muted benthic foraminiferal response, the planktic community has been substantially impacted by the LDE as indicated by changes in planktic foraminifera faunas and calcareous nannofossils. Finally, our quantitative and conventional approaches identifying stratigraphically important planktic foraminifera datum levels justify a revision of the upper Danian to lower Selandian planktic foraminifera biozonation.

scholarly journals Threshold effects of hazard mitigation in coastal human–environmental systems

2013 ◽  
Vol 1 (1) ◽  
pp. 503-530
Author(s):  
E. D. Lazarus
Keyword(s):  
Climate Change ◽  
Time Scales ◽  
Human Activities ◽  
Environmental Changes ◽  
Hazard Mitigation ◽  
Coupled System ◽  
Time Frame ◽  
Global Scale ◽  
Coupling Mechanism ◽  
Environmental Systems

Abstract. Despite improved scientific insight into physical and social dynamics related to natural disasters, the financial cost of extreme events continues to rise. This paradox is particularly evident along developed coastlines, where future hazards are projected to intensify with consequences of climate change, and where the presence of valuable infrastructure exacerbates risk. By design, coastal hazard mitigation buffers human activities against the variability of natural phenomena such as storms. But hazard mitigation also sets up feedbacks between human and natural dynamics. This paper explores developed coastlines as exemplary coupled human–environmental systems in which hazard mitigation is the key coupling mechanism. Results from a simplified numerical model of an agent-managed seawall illustrate the nonlinear effects that economic and physical thresholds can impart into coupled-system dynamics. The scale of mitigation action affects the time frame over which human activities and natural hazards interact. By accelerating environmental changes observable in some settings over human time scales of years to decades, climate change may temporarily strengthen the coupling between human and environmental dynamics. However, climate change could ultimately result in weaker coupling at those human time scales as mitigation actions increasingly engage global-scale systems.

scholarly journals First-order estimate of the planktic foraminifer biomass in the modern ocean

2012 ◽  
Vol 4 (1) ◽  
pp. 75-89 ◽  
Author(s):  
R. Schiebel ◽  
A. Movellan
Keyword(s):  
Water Depth ◽  
Marine Ecosystem ◽  
Regional Scale ◽  
Global Scale ◽  
Order Estimate ◽  
Planktic Foraminifera ◽  
First Order ◽  
The North ◽  
Carbon Biomass ◽  
Wide Range

Abstract. Planktic foraminifera are heterotrophic mesozooplankton of global marine abundance. The position of planktic foraminifers in the marine food web is different compared to other protozoans and ranges above the base of heterotrophic consumers. Being secondary producers with an omnivorous diet, which ranges from algae to small metazoans, planktic foraminifers are not limited to a single food source, and are assumed to occur at a balanced abundance displaying the overall marine biological productivity at a regional scale. With a new non-destructive protocol developed from the bicinchoninic acid (BCA) method and nano-photospectrometry, we have analysed the protein-biomass, along with test size and weight, of 754 individual planktic foraminifers from 21 different species and morphotypes. From additional CHN analysis, it can be assumed that protein-biomass equals carbon-biomass. Accordingly, the average individual planktic foraminifer protein- and carbon-biomass amounts to 0.845 μg. Samples include symbiont bearing and symbiont-barren species from the sea surface down to 2500 m water depth. Conversion factors between individual biomass and assemblage-biomass are calculated for test sizes between 72 and 845 μm (minimum test diameter). Assemblage-biomass data presented here include 1128 sites and water depth intervals. The regional coverage of data includes the North Atlantic, Arabian Sea, Red Sea, and Caribbean as well as literature data from the eastern and western North Pacific, and covers a wide range of oligotrophic to eutrophic waters over six orders of magnitude of planktic-foraminifer assemblage-biomass (PFAB). A first order estimate of the average global planktic foraminifer biomass production (>125 μm) ranges from 8.2–32.7 Tg C yr−1 (i.e. 0.008–0.033 Gt C yr−1), and might be more than three times as high including neanic and juvenile individuals adding up to 25–100 Tg C yr−1. However, this is a first estimate of regional PFAB extrapolated to the global scale, and future estimates based on larger data sets might considerably deviate from the one presented here. This paper is supported by, and a contribution to the Marine Ecosystem Data project (MAREDAT). Data are available from http://www.pangaea.de (http://doi.pangaea.de/10.1594/PANGAEA.777386).

scholarly journals Demographic history and genomic response to environmental changes in a rapid radiation of wild rats

2021 ◽  
Author(s):  
Deyan Ge ◽  
Anderson Feijó ◽  
Zhixin Wen ◽  
Alexei V Abramov ◽  
Liang Lu ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Demographic History ◽  
Terrestrial Ecosystems ◽  
Tibet Plateau ◽  
Global Changes ◽  
Rapid Radiation ◽  
Protein Functions ◽  
Wild Rats ◽  
Qinghai Tibet Plateau ◽  
Genomic Response

Abstract For organisms to survive and prosper in a harsh environment, particularly under rapid climate change, poses tremendous challenges. Recent studies have highlighted the continued loss of megafauna in terrestrial ecosystems and the subsequent surge of small mammals, such as rodents, bats, lagomorphs, and insectivores. However, the ecological partitioning of these animals will likely lead to large variation in their responses to environmental change. In the present study, we investigated the evolutionary history and genetic adaptations of white-bellied rats (Niviventer Marshall, 1976), which are widespread in the natural terrestrial ecosystems in Asia but also known as important zoonotic pathogen vectors and transmitters. The southeastern Qinghai-Tibet Plateau (QHTP) was inferred as the origin center of this genus, with parallel diversification in temperate and tropical niches. Demographic history analyses from mitochondrial and nuclear sequences of Niviventer demonstrated population size increases and range expansion for species in Southeast Asia, and habitat generalists elsewhere. Unexpectedly, population increases were seen in N. eha, which inhabits the highest elevation among Niviventer species. Genome scans of nuclear exons revealed that among the congeneric species, N. eha has the largest number of positively selected genes. Protein functions of these genes are mainly related to olfaction, taste and tumor suppression. Extensive genetic modification presents a major strategy in response to global changes in these alpine species.

scholarly journals Impact Mechanism of the Ecological Vulnerability of Highly Developed Islands Based on the Bayesian Network Model—Applied to the Changshan Islands

2021 ◽  
Vol 18 (8) ◽  
pp. 4150
Author(s):  
Keyu Qin ◽  
Haijun Huang ◽  
Jingya Liu ◽  
Liwen Yan ◽  
Yanxia Liu ◽  
...  
Keyword(s):  
Bayesian Network ◽  
Network Model ◽  
Geographical Information ◽  
Global Changes ◽  
Bayesian Network Model ◽  
Island Ecosystems ◽  
Impact Mechanism ◽  
The North ◽  
Ecological Vulnerability ◽  
The Impact

Islands are one of the most sensitive interfaces between global changes and land and sea dynamic effects, with high sensitivity and low stability. Therefore, under the dynamic coupling effect of human activities and frequent natural disasters, the vulnerability of the ecological environment of islands shows the characteristics of complexity and diversity. For the protection of island ecosystems, a system for the assessment of island ecosystems and studies on the mechanism of island ecological vulnerability are highly crucial. In this study, the North and South Changshan Islands of China were selected as the study area. Considering various impact factors of island ecological vulnerability, the geographical information systems (GIS) spatial analysis, field surveys, data sampling were used to evaluate island ecological vulnerability. The Bayesian network model was used to explore the impact mechanism of ecological vulnerability. The results showed that the ecological vulnerability of the North Changshan Island is higher than that of the South Changshan Island. Among all the indicators, the proportion of net primary productivity (NPP) and the steep slope has the strongest correlation with ecological vulnerability. This study can be used as references in the relevant departments to formulate management policies and promote the sustainable development of islands and their surrounding waters

scholarly journals Dynamic Relationship Between Real Export, Real Import, Real Exchange Rate, Labor Force and Real Gross Domestic Product in Malaysia

2019 ◽  
Vol 10 (5) ◽  
pp. 20
Author(s):  
Emilda Hashim ◽  
Norimah Rambeli ◽  
Asmawi Hashim ◽  
Norasibah Abdul Jalil ◽  
Shahrun Nizam Abdul Aziz ◽  
...  
Keyword(s):  
Exchange Rate ◽  
Labor Force ◽  
Open Economy ◽  
Unit Root ◽  
Correction Term ◽  
Unit Root Test ◽  
Real Effective Exchange Rate ◽  
Global Changes ◽  
Real Gdp ◽  
Long Run

This study examined short run and long run relationship between endogenous and exogenous variables. Specifically, it studied the relationship between real export, real import, labor force participation and real effective exchange rate (REER) and real GDP in Malaysia from 1988 to 2017. These variables were tested in various tests, namely, unit root test, granger causality test, vector autoregressive (VAR), Johansen Juselius test and Error Correction Term (ECT). The result revealed that all variables were non-stationary at the level form and stationary at first difference in ADF unit root test. The findings also exhibited the existence of bilateral relationships between real export and real GDP, real import and real GDP, as well as labor and real GDP. Nonetheless, there were no relationship found between REER and real GDP. On the other hand, in VAR, the lag optimum was lag 10 because it indicated the smallest value of AIC. Moreover, for Johansen Juselius cointegration test, it showed two cointegrated vector at both, 5% and 1%, level in trace test. In addition, Max-Eigen value test indicated two cointegrated vector at 0.05 and one cointegrated vector at 0.01. As for the Wald test, there were long run cointegration relationship between real GDP and its determinants, namely real export, real import, labor and REER. Apparently, Malaysia, as a small open economy, has relied heavily on foreign trade. Consequently, our domestic economic performance is susceptible to the changes in international markets and exchange rate. Therefore, suitable international policy implementation is vital to ensure Malaysian economy will be able to adjust to current global changes.

Lake and inland dunes as interconnected Systems: The story of Lake Tresssee and an adjacent dune field (Schleswig-Holstein, North Germany)

The Holocene ◽  
2020 ◽  
pp. 095968362098168
Author(s):  
Christian Stolz ◽  
Magdalena Suchora ◽  
Irena A Pidek ◽  
Alexander Fülling
Keyword(s):  
Water Level ◽  
Bronze Age ◽  
Environmental Changes ◽  
High Water ◽  
Alluvial Fan ◽  
Water Levels ◽  
Lake Area ◽  
Dune Field ◽  
The North ◽  
Sand Drift

The specific aim of the study was to investigate how four adjacent geomorphological systems – a lake, a dune field, a small alluvial fan and a slope system – responded to the same impacts. Lake Tresssee is a shallow lake in the North of Germany (Schleswig-Holstein). During the Holocene, the lake’s water surface declined drastically, predominately as a consequence of human impact. The adjacent inland dune field shows several traces of former sand drift events. Using 30 new radiocarbon ages and the results of 16 OSL samples, this study aims to create a new timeline tracing the interaction between lake and dunes, as well, as how both the lake and the dunes reacted to environmental changes. The water level of the lake is presumed to have peaked during the period before the Younger Dryas (YD; start at 10.73 ka BC). After the Boreal period (OSL age 8050 ± 690 BC) the level must have undergone fluctuations triggered by climatic events and the first human influences. The last demonstrable high water level was during the Late Bronze Age (1003–844 cal. BC). The first to the 9th century AD saw slightly shrinking water levels, and more significant ones thereafter. In the 19th century, the lake area was artificially reduced to a minimum by the human population. In the dunes, a total of seven different phases of sand drift were demonstrated for the last 13,000 years. It is one of the most precisely dated inland-dune chronologies of Central Europe. The small alluvial fan took shape mainly between the 13th and 17th centuries AD. After 1700 cal. BC (Middle Bronze Age), and again during the sixth and seventh centuries AD, we find enhanced slope activity with the formation of Holocene colluvia.

Mistletoes in a changing world: a premonition of a non-analog future?

Botany ◽  
2020 ◽  
Vol 98 (9) ◽  
pp. 479-488
Author(s):  
Francisco E. Fontúrbel
Keyword(s):  
Land Use ◽  
Land Use Changes ◽  
Biodiversity Loss ◽  
Global Scale ◽  
Ecological Interactions ◽  
Human Disturbances ◽  
Climate Change Effects ◽  
Long Run ◽  
Plant Animal Interactions ◽  
Changing World

Mistletoes are a group of flowering plants that have developed a parasitic lifeform through complex eco-evolutionary processes. Despite being considered a pest, mistletoes represent a keystone forest resource and are involved in complex plant–plant and plant–animal interactions. Their parasitic lifeform and specialized ecological interactions make mistletoes an ideal model with which to understand the effects of anthropogenic disturbances in a changing world. The accelerated growth of the human population has altered all ecosystems on Earth, leading to biodiversity loss. Land-use changes (involving habitat loss, fragmentation, degradation, and transformation processes) can alter the ecological scenario for mistletoe by altering hosts, mutualists, and nutrient cycling. Those changes may have large consequences at the community level, changing the spatial structure of mistletoes, as well as interaction effectiveness, facilitation process, interaction disruption, and novel interactions with invasive species, leading to non-analog communities in the long run. Furthermore, climate change effects operate on a global scale, enhancing the effects of land-use changes. As temperatures increase, many species would alter their distribution and phenology, potentially causing spatial and temporal mismatches. But more critical is the fact that water stress is likely to disrupt key ecological interactions. Thus, mistletoes can provide valuable insights for what we can expect in the future, as a result of human disturbances.

Biogeochemical disruptions across the Cretaceous-Paleogene boundary : insights from sulfur isotopes

2021 ◽  
Author(s):  
Arbia Jouini
Keyword(s):  
Mass Extinction ◽  
Environmental Changes ◽  
Sea Water ◽  
Sulfur Isotopes ◽  
Deep Understanding ◽  
Sulfur Cycle ◽  
Mass Extinctions ◽  
Deccan Volcanism ◽  
Organic Carbon Burial ◽  
Early Paleocene

<p><strong>Biogeochemical disruptions across the Cretaceous-Paleogene boundary : insights from sulfur isotopes</strong></p><p> </p><p>Arbia JOUINI<sup>1*</sup>, Guillaume PARIS<sup>1</sup>, Guillaume CARO<sup>1</sup>, Annachiara BARTOLINI<sup>2</sup></p><p><sup>1 </sup>Centre de Recherches Pétrographiques et Géochimiques, CRPG-CNRS, UMR7358, ,15 rue Notre Dame des Pauvres, BP20, 54501Vandoeuvre-lès-Nancy, France, email:[email protected]</p><p><sup>2</sup> Muséum National D’Histoire Naturelle, Département Origines & Evolution, CR2P MNHN, CNRS, Sorbonne Université, 8 rue Buffon CP38, 75005 Paris, France</p><p> </p><p>The Cretaceous–Paleogene (KPg) mass extinction event 66 million years ago witnessed one of the ‘Big Five’ mass extinctions of the Phanerozoic. Two major catastrophic events, the Chicxulub asteroid impact and the Deccan trap eruptions, were involved in complex climatic and environmental changes that culminated in the mass extinction including oceanic biogenic carbonate crisis, sea water chemistry and ocean oxygen level changes. Deep understanding of the coeval sulfur biogeochemical cycle may help to better constrain and quantify these parameters.</p><p>Here we present the first stratigraphic high resolution isotopic compositions of carbonate associated sulfate (CAS) based on monospecific planktic and benthic foraminifers' samples during the Maastrichtian-Danian transition from IODP pacific site 1209C. Primary δ34SCAS data suggests that there was a major perturbation of sulfur cycle around the KPg transition with rapid fluctuations (100-200kyr) of about 2-4‰ (±0.54‰, 2SD) during the late Maastrichtian followed by a negative excursion in δ34SCAS of 2-3‰ during the early Paleocene.</p><p>An increase in oxygen levels associated with a decline in organic carbon burial, related to a collapse in primary productivity, may have led to the early Paleocene δ34SCAS negative shift via a significant drop in microbial sulfate reduction. Alternatively, Deccan volcanism could also have played a role and impacted the sulfur cycle via direct input of isotopically light sulfur to the ocean. A revised correlation between δ34SCAS data reported in this study and a precise dating of the Deccan volcanism phases would allow us to explore this hypothesis.</p><p>Keywords : KPg boundary, Sulphur cycle, cycle du calcium, Planktic and benthic foraminifera</p><p> </p>

scholarly journals Technical Note: On methodologies for determining the size-normalised weight of planktic foraminifera

2010 ◽  
Vol 7 (7) ◽  
pp. 2193-2198 ◽  
Author(s):  
C. J. Beer ◽  
R. Schiebel ◽  
P. A. Wilson
Keyword(s):  
Wall Thickness ◽  
North Atlantic ◽  
Technical Note ◽  
Sieve Method ◽  
Planktic Foraminifera ◽  
Test Size ◽  
The North ◽  
Sieve Fraction ◽  
Error Bar ◽  
Fraction Method

Abstract. The size-normalised weight (SNW) of planktic foraminifera, a measure of test wall thickness and density, is potentially a valuable palaeo-proxy for marine carbon chemistry. As increasing attention is given to developing this proxy it is important that methods are comparable between studies. Here, we compare SNW data generated using two different methods to account for variability in test size, namely (i) the narrow (50 μm range) sieve fraction method and (ii) the individually measured test size method. Using specimens from the 200–250 μm sieve fraction range collected in multinet samples from the North Atlantic, we find that sieving does not constrain size sufficiently well to isolate changes in weight driven by variations in test wall thickness and density from those driven by size. We estimate that the SNW data produced as part of this study are associated with an uncertainty, or error bar, of about ±11%. Errors associated with the narrow sieve fraction method may be reduced by decreasing the size of the sieve window, by using larger tests and by increasing the number tests employed. In situations where numerous large tests are unavailable, however, substantial errors associated with this sieve method remain unavoidable. In such circumstances the individually measured test size method provides a better means for estimating SNW because, as our results show, this method isolates changes in weight driven by variations in test wall thickness and density from those driven by size.

scholarly journals Characteristics of Spatial-Temporal Evolution of Meteorological Drought in the Ningxia Hui Autonomous Region of Northwest China

Water ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 992 ◽  
Author(s):  
Yuan Fang ◽  
Hui Qian ◽  
Jie Chen ◽  
Han Xu
Keyword(s):  
Time Scales ◽  
Wavelet Coefficient ◽  
Meteorological Drought ◽  
Northwest China ◽  
Scientific Basis ◽  
The North ◽  
Ningxia Hui Autonomous Region ◽  
Frequency Domains ◽  
Drought Disaster ◽  
Wavelet Variance

This study focuses on the intensity, duration, and frequency of meteorological droughts in Ningxia, northwest China, from 1960 to 2016. The analysis was conducted using the interannual characteristics of droughts, which were studied by the standardized precipitation evapotranspiration index (SPEI) at different timescales. Additionally, the correlation, mutability, and periodicity of two series in both the time and frequency domains in multi-time scales were scientifically analyzed using the wavelet analysis method. The results showed that the occurrence of drought had increased at different timescales (i.e., SPEI1, SPEI3, and SPEI12) during the past 57 years. The autumn drought had the largest share; spring is the high-occurrence season of extreme drought and the overall drought intensity increases towards the north. The periodical change of droughts was described with the wavelet coefficient real part value, wavelet power spectrum, and wavelet variance. The results showed that the 13- and 8-year time scales had the strongest oscillation and energy, and they were the first and the second major periods of drought. Moreover, the drought mutational fluctuations are in better agreement with that characterized by the SPEI12 and actual conditions. The results help to understand the occurrence and evolution of droughts in Ningxia, and to provide a scientific basis to reduce and prevent the drought disaster.

Sign in / Sign up

Export Citation Format

Share Document