Browsing Earth Sciences by Publication date
Now showing items 1-14 of 14
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Diverse Primitive Basalts from an Extensional Back-arc Setting: Fort Rock Volcanic Field, OregonThe Fort Rock Volcanic Field study area (FRVF) is situated in a highly complex volcanic and tectonic extensional back arc setting, influenced by multiple episodes involving the subduction of the Juan de Fuca Plate under the North American Plate, eruptions from the Western and High Cascades, High Lava Plains (HLPs), Newberry, and extension from the Basin & Range continental rift zone. Hydrovolcanic eruptions created tuff rings/cones and maars, while conventional eruptions created cinder cones, and lava fields in the FRVF area. These landforms contain a diverse array of primitive basalts, with an Mg# (xMgO / (xMgO + xFeO) * 100) > 60 (molar %), deducing information of mantle source regions and melting processes through geochemical analyses of major and trace elements to achieve a greater understanding of the complex tectonic framework and eruptive history of the FRVF. Geochemical data was acquired through X-ray fluorescence (XRF) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) for 75 mafic basaltic samples. FRVF basalts analyzed four diverse primitive magma types; low-K tholeiites (LKTs), calc-alkaline basalts (CABs), high Mg# basaltic andesites (BAs), and ocean island basalts (OIBs). These magma types are further separated into western/central and eastern sections of the FRVF based on their major and trace element variations. These variations suggest the subduction enrichment, mantle fertility, and the depth and degree of partial melting trends of their primary mantle sources depend on their distribution across the FRVF.
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Climatic and Environmental Changes Affecting Communities in Atlantic CanadaSmall rural coastal communities located in Atlantic Canada are vulnerable to the effects of climate and environmental changes. Major storms have impounded the coastline, causing much physical damage and affecting the socio-economics of these communities that are composed of an aging population. The current study relays findings based on interviews completed in 2011–2012, following the 2010 winter storms in Atlantic Canada. It portrays the physical and social–ecological impacts affecting 10 coastal communities located in the provinces of Québec, New Brunswick, and Prince Edward Island. Semi-structured interviews held in these provinces are the basis for the contributions of this research. The findings reveal physical changes related to coastal erosion from high-wave impacts and storm surge causing flooding of the coastal zone. Also considered are strategies preferred and actually implemented by residents, such as building of protection walls, although undesirable. Due to funding constraints, however, many of these large-scale flood protection projects are not possible without governmental support. Instead, it is suggested that development be controlled and some respondents in this study upheld that relocation be used to alleviate the situation. Finally, more work is required to improve emergency planning. Better concerted short- and long-term responses need to be coordinated by local authorities and higher up in the government in order to ensure the sustainability of these coastal communities.
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Chemostratigraphy of the uppermost Cambrian at the Ordovician GSSPChemostratigraphy is an important tool for correlating layered sedimentary rock successions. Preserved/near primary carbon isotope signatures in marine carbonates can provide high-resolution profiles for sedimentary sequences supplementing the need for distinguishing fossils from different depositional environments and those lacking fossil materials. The Global Boundary Stratotype Section and Point (GSSP) of the Cambrian‒Ordovician boundary is located at Green Point in the Green Point Formation of the Cow Head Group in western Newfoundland, Canada. To reconstruct a continuous and high-resolution chemostratigraphy from the Cambrian‒Ordovician boundary to the Furongian Series Stage 10, we included the δ13C results of the Green Point Formation covering the Ordovician GSSP interval (Azmy et al., 2014). The Green Point Formation through the base of Ordovician GSSP consists of alternating dark gray to black shale and thin ribbon limestone rhythmites, with few fossils. The samples are micritic limestone, dolomitic limestone, and dolostone. They were determined to be in primary to near-primary condition based on multiple screening tests. Cathodoluminescence screening reveals dull to bright luminescence of the samples indicative of good preservation for many of them. The δ13Ccarb and δ18O values of the Green Point carbonates range from -6.44‰ to +0.33‰ (VPDB) and from -8.63‰ to -5.67‰ (VPDB), respectively, with poor correlation. Mn/Sr ratios range from 0.63 to 9.82, with no correlation to δ13Ccarb, but with ratios supporting the near primary nature of the δ13C values. Carbon isotope compositions of the Green Point Formation below the Ordovician GSSP fluctuate but remaine essentially invariantly negative. The δ13C values reveal a negative excursion at and below the Cambrian‒Ordovician boundary, which may correlate with the Top of Cambrian Carbon Isotope Excursion (TOCE) and its significant negative excursion. A nadir of -6.44 ‰ at the base of the Eoconodontus conodont zone marks the proposed GSSP for the base of the Furongian Series Stage 10. The lower excursion may be correlated with the Hellnmaria-Red Tops Boundary (HERB) carbon isotope excursion found in sequences in the United States of America, Australia, and north China. Without an adequate record of conodonts, high-resolution chemostratigraphic trends of carbon isotope compositions facilitate the correlation of intercontinental and intracontinental sequences.
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Is It Time to Shift Our Environmental Thinking? A Perspective on Barriers and Opportunities to ChangeIn 2015, the United Nations General Assembly unanimously adopted the 2030 Agenda for Sustainable Development and Sustainable Development Goals. In 2019, the release of the global assessment report of the United Nations’ Intergovernmental Platform on Biodiversity and Ecosystem Services unfortunately demonstrated that our planet may be in more trouble than expected. The main drivers have been identified for many years and relate to human activities such as over-exploitation of natural resources leading to land degradation, deforestation, ocean and atmospheric pollution, and climate change. Despite international agreements and conventions, we are gradually reaching the planet’s boundaries. In this commentary, we present an analysis of the current worldview, discuss the humanist roots of this view, and the barriers to be able to move forward with the transformative changes that are needed for sustainability. We suggest that for these transformative changes to happen, there is a need to reconnect humans with nature, and we propose that some solutions could be devised in areas like education and social media. Changing our mindsets and worldviews are the most urgent courses of action we must undertake to avoid the inevitable
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Host Plant-Derived miRNAs Potentially Modulate the Development of a Cosmopolitan Insect Pest, Plutella xylostellaPlant microRNAs (miRNAs) have recently been reported to be involved in the cross-kingdom regulation of specific cellular and physiological processes in animals. However, little of this phenomenon is known for the communication between host plant and insect herbivore. In this study, the plant-derived miRNAs in the hemolymph of a cruciferous specialist were identified by small RNAs sequencing. A total of 39 miRNAs with typical characteristics of plant miRNAs were detected, of which 24 had read counts ≥ 2 in each library. Three plant-derived miRNAs with the highest read counts were validated, and all of them were predicted to target the hemocyanin domains-containing genes of . The luciferase assays in the S2 cell demonstrated that miR159a and novel-7703-5p could target and respectively, possibly in an incomplete complementary pairing mode. We further found that treatment with agomir-7703-5p significantly influenced the pupal development and egg-hatching rate when reared on the artificial...
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CENTRAL NORTH ATLANTIC PALEOCEANOGRAPHY DURING THE LATE EARLY PLEISTOCENE (SPANNING MARINE ISOTOPE STAGE 21) BASED ON A HIGH-RESOLUTION DINOFLAGELLATE CYST RECORDA high-resolution dinoflagellate cyst record from Integrated Ocean Drilling Program Site U1313, constrained by an ultra-high resolution δ18O record from the same sample set, is established to enhance our understanding of the paleoceanography and structure of Marine Isotope Stage (MIS) 21 in the central North Atlantic. Changes in cyst abundance, composition of cyst assemblages, and their diversity reflect major regional shifts in climate and ocean circulation for this time interval (866–814 ka). The following paleoenvironmental indicators are used: Operculodinium centrocarpum sensu Wall & Dale (North Atlantic Current), Nematosphaeropsis labyrinthus and Impagidinium pallidum (subpolar gyre), total Impagidinium species (subtropical gyre), and protoperidiniacean cysts (biological productivity). The integration of stable isotope and the generated dinoflagellate cyst data shows MIS 21 to have been climatically unstable and interrupted between 830 and 840 ka by two significant cool episodes. These are resolved using the relative abundance of cooler-water species and by tracking the abundance of O. centrocarpum. During MIS 21, Site U1313 was predominantly under the influence of the subtopical gyre until after 835 ka when the NAC was re-established until the end of MIS 21. This study also extends the stratigraphic range of Fibrocysta? fusiforma from its previously documented range top in the Lower Pleistocene at 2.3 Ma to ~812 ka in the present study. An unnamed Spiniferites species (Spiniferites sp. 1) is confined to the latest phase of MIS 22. Two unidentified acritarchs (Acritarch spp. 1 and 2) occur throughout MIS 21 and merit further investigation.
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Are Yellow Sticky Cards and Light Traps Effective on Tea Green Leafhoppers and Their Predators in Chinese Tea Plantations?In Chinese tea plantations, yellow sticky cards and light traps are increasingly used to control insect pests, especially the tea green leafhopper . In this study, a 16-week open-field experiment with daily weather monitoring was designed to test the responses of tea green leafhopper, parasitoids and spiders to yellow sticky cards and three light traps with different wavelengths (covered with sticky cards). An exclosure experiment was also designed to further test the influence of the three light systems (without sticky card) on the same species. The results showed that all three light emitting diode (LED) light traps (white, green and yellow) and yellow sticky cards attracted many more male adults than females during the course of the open field experiment, with less than 25% of trapped adults being females. Parasitoids and spiders were also attracted by these systems. Weather variables, especially rainfall, influenced the trapping efficiency. In the exclosure experiment, the population of leafhoppers in the yellow sticky card treatment did not decline significantly, but the number of spiders significantly decreased. The green and white light treatments without sticky cards showed a significant control of and no obvious harm to spiders. These results suggest that yellow sticky cards and light traps have limited capacity to control tea green leafhoppers. However, light, especially green light, may be a promising population control measure for tea green leafhoppers, not as killing agents in the traps, but rather as a behavioral control system.
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Ecological Risk Assessment of Soil Heavy Metals and Pesticide Residues in Tea PlantationsTea plantations have used many synthetic chemicals to ensure performance and control of pests. This has led to increased contamination of soils and reduced tea growth. We assessed the levels of heavy metals, including Cd, Cr, Pb, Cu, Ni, Zn, Hg, As, and pesticide residues, such as HCHs, biphenyl chrysanthemum ester, methamidophos, imidacloprid, permethrin, in the soil of tea plantations of Taiwan, Tibet, Guangdong, and Fujian. The Potential Ecological Risk Index and the Nemerow comprehensive pollution index were used to analyze the data. The results showed that risk indices in Tibet, Guangdong and Fuzhou were considered as moderate ecological harm level. Ecological risk assessment index of Anxi organic and Anxi conventional tea gardens suggested a "low" risk level. The Nemerow comprehensive pollution indices for soil pesticide residues in the tea plantations of Taiwan, Tibet, Anxi organic and Anxi conventional were considered mild. Guangdong and Fuzhou had values suggesting "slight pollution” levels. According to National Soil Environmental Quality Standard (GB15618-1995), soil in tea plantations in Taiwan, Tibet, and Anxi conventional matched the national first grade of soil quality and those from Guangdong, Fuzhou, and Anxi organic tea garden matched the national second grade.
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Differential Profiles of Gut Microbiota and Metabolites Associated with Host Shift of Plutella xylostellaEvolutionary and ecological forces are important factors that shape gut microbial profiles in hosts, which can help insects adapt to different environments through modulating their metabolites. However, little is known about how gut microbes and metabolites are altered when lepidopteran pest species switch hosts. In the present study, using 16S-rDNA sequencing and mass spectrometry-based metabolomics, we analyzed the gut microbiota and metabolites of three populations of : one feeding on radish (PxR) and two feeding on peas (PxP; with PxP-1 and PxP-17 being the first and 17th generations after host shift from radish to peas, respectively). We found that the diversity of gut microbes in PxP-17 was significantly lower than those in PxR and PxP-1, which indicates a distinct change in gut microbiota after host shift. Kyoto Encyclopedia of Genes and Genomes analysis revealed that the functions of energy metabolism, signal transduction, and xenobiotics biodegradation and metabolism were increased in PxP-17, suggesting their potential roles in host adaptation. Metabolic profiling showed a significant difference in the abundance of gut metabolites between PxR and PxP-17, and significant correlations of gut bacteria with gut metabolites. These findings shed light on the interaction among plants, herbivores, and symbionts, and advance our understanding of host adaptation associated with gut bacteria and metabolic activities
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Mechanism and consequences for avoidance of superparasitism in the solitary parasitoid Cotesia vestalisA parasitoid's decision to reject or accept a potential host is fundamental to its fitness. Superparasitism, in which more than one egg of a given parasitoid species can deposit in a single host, is usually considered sub-optimal in systems where the host is able to support the development of only a single parasitoid. It follows that selection pressure may drive the capacity for parasitoids to recognize parasitized hosts, especially if there is a fitness cost of superparasitism. Here, we used microsatellite studies of two distinct populations of Cotesia vestalis to demonstrate that an egg laid into a diamondback moth (Plutella xylostella) larva that was parasitized by a conspecific parasitoid 10 min, 2 or 6 h previously was as likely to develop and emerge successfully as was the first-laid egg. Consistent with this, a naive parasitoid encountering its first host was equally likely to accept a healthy larva as one parasitized 10 min prior, though handling time of parasitized hosts was extended. For second and third host encounters, parasitized hosts were less readily accepted than healthy larvae. If 12 h elapsed between parasitism events, the second-laid egg was much less likely to develop. Discrimination between parasitized and healthy hosts was evident when females were allowed physical contact with hosts, and healthy hosts were rendered less acceptable by manual injection of parasitoid venom into their hemolymph. Collectively, these results show a limited capacity to discriminate parasitized from healthy larvae despite a viability cost associated with failing to avoid superparasitism.
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Rewilding for human healthExploring the connections between zoonotic diseases, human health and well-being, ecosystem degradation and biodiversity loss.
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An analysis of aquatic invasive species management in the Niagara region of Ontario, Canada: establishment of a database to improve knowledge sharingThe UN Convention on Biological Diversity has declared invasive species a global threat and requested increased data sharing to prevent further impact. Existing worldwide and local databases mainly focus on distribution, abundance, identification, and impacts of invasive species, but very few record management activities. In the Niagara region of Ontario, Canada, no database focuses specifically on invasive species management. The goal of this study was to document current aquatic and riparian invasive species management activities in the Niagara region and develop a database that would become a tool to facilitate collaboration at the regional level. The objectives were to (1) inventory current invasive species detection and control activities in the Niagara region; (2) examine perceived efficacy of control techniques; and (3) develop a database integrated with a GIS mapping component. Seventy-one organizations involved in riparian/aquatic invasive species management in the Niagara region were contacted and 16 in-depth interviews were conducted. In 2017–2018, 35 separate control efforts were reported, involving 10 riparian invasive species and two aquatic invasive species, mostly concentrated along the Niagara River. Collaboration efforts were minimal, occurring for only six specific projects. Recommendations include develop a regional invasive species plan; increase control efforts along the Welland Canal and Lake Erie shoreline; adopt a wider variety of control techniques; and increase collaboration, information-sharing and resource-sharing among organizations. Overall, the newly developed database provides a baseline for the current state of aquatic and riparian invasive species management activities in the region. It can also help bridge the gap between invasive species science and decision-making by forming a tool to identify resource-sharing opportunities, management efficacy, priority areas, areas of improvement, and future resource needs. The database will enrich the global invasive species information network by providing Niagara-specific information. The database could also act as a model for tracking management activities of other invasive species and in other regions of North America.
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From the Book Review Editor of the Special Issue on Climate ChangeClimate change is affecting the lives of many communities and how to prepare for these changes is not always easy to define. To enhance community engagement in both mitigation and adaptation to climate change, there is a need to better assess how the complexity of climate change is affecting not only humans but the ecosystem where they live and the interactions among nature and people. This means also understanding how politics, policies, and other issues may help (or not) to improve engagement of communities in moving from discourse to action.
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How Ecosystem-Based Adaptation to Climate Change Can Help Coastal Communities through a Participatory ApproachCoastal rural communities worldwide face many challenges not only related to climate change but also extreme events, environmental degradation, population growth or aging, and conflict usage of the ecosystem. Historically, the economies of coastal communities have been based on the exploitation of natural resources, thus shaping its socioeconomic development. This has led to some limitations in the way these communities can now adapt to climate change. In Canada, coastal communities are increasingly dealing with climate change consequences. Sea level rise, coastal erosion, and increasing frequency in storm surges threaten the fragility of both natural and human systems. Various approaches have been used to try to reduce the vulnerability and improve adaptive capacity of communities. One approach, promoted by many organizations including the United Nations, is ecosystem-based adaptation. This approach is part of the series of nature-based solutions that help social–ecological systems become more resilient; by promoting biodiversity conservation and ecosystem services, this approach also relates to principles of community engagement and supports adaptive governance and social inclusion. This paper describes and analyzes these principles and considers strategies for ensuring community engagement. Combining ecosystem-based adaptation with a strong community engagement can enhance the long-term sustainability of the social-ecological system.
