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  • Wiley  (57)
  • 2020-2024  (57)
  • 2005-2009
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  • 2021  (45)
  • 1
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    Zircon and Melt Extraction From a Long‐Lived and Vertically Extensive Magma System Underneath Ilopango Caldera (El Salvador) (2021)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-02-07
    Description: The Tierra Blanca (TB) eruptive suite comprises the last four major eruptions of Ilopango caldera in El Salvador (≤45 ka), including the youngest Tierra Blanca Joven eruption (TBJ; ∼106 km3): the most voluminous event during the Holocene in Central America. Despite the protracted and productive history of explosive silicic eruptions at Ilopango caldera, many aspects regarding the longevity and the prevailing physicochemical conditions of the underlying magmatic system remain unknown. Zircon 238U-230Th geochronology of the TB suite (TBJ, TB2, TB3, and TB4) reveals a continuous and overlapping crystallization history among individual eruptions, suggesting persistent melt presence in thermally and compositionally distinct magma reservoirs over the last ca. 80 kyr. The longevity of zircon is in contrast to previously determined crystallization timescales of 〈10 kyr for major mineral phases in TBJ. This dichotomy is explained by a process of rhyolitic melt segregation from a crystal-rich refractory residue that incorporates zircon, whereas a new generation of major mineral phases crystallized shortly before eruption. Ti-in-zircon temperatures and amphibole geothermobarometry suggest that rhyolitic melt was extracted from different storage zones of the magma reservoir as indicated by distinct but synchronous thermochemical zircon histories among the TB suite eruptions. Zircon from TBJ and TB2 suggests magma differentiation within deeper and hotter parts of the reservoir, whereas zircon from TB3 and TB4 instead hints at crystallization in comparatively shallower and cooler domains. The assembly of the voluminous TBJ magma reservoir was also likely enhanced by cannibalization of hydrothermally altered components as suggested by low-δ18O values in zircon (+4.5 ± 0.3‰).
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  • 2
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    Effects of Reversal of Water Flow in an Arctic Floodplain River on Fluvial Emissions of CO 2 and CH 4 (2022)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-02-07
    Description: When organic matter from thawed permafrost is released, the sources and sinks of greenhouse gases (GHGs), like carbon dioxide (CO2) and methane (CH4) in Arctic rivers will be influenced in the future. However, the temporal variation, environmental controls, and magnitude of the Arctic riverine GHGs are largely unknown. We measured in situ high temporal resolution concentrations of CO2, CH4, and oxygen (O2) in the Ambolikha River in northeast Siberia between late June and early August 2019. During this period, the largely supersaturated riverine CO2 and CH4 concentrations decreased steadily by 90% and 78%, respectively, while the O2 concentrations increased by 22% and were driven by the decreasing water temperature. Estimated gas fluxes indicate that during late June 2019, significant emissions of CO2 and CH4 were sustained, possibly by external terrestrial sources during flooding, or due to lateral exchange with gas-rich downstream-flowing water. In July and early August, the river reversed its flow constantly and limited the water exchange at the site. The composition of dissolved organic matter and microbial communities analyzed in discrete samples also revealed a temporal shift. Furthermore, the cumulative total riverine CO2 emissions (36.8 gC-CO2 m−2) were nearly five times lower than the CO2 uptake at the adjacent floodplain. Emissions of riverine CH4 (0.21 gC-CH4 m−2) were 16 times lower than the floodplain CH4 emissions. Our study revealed that the hydraulic connectivity with the land in the late freshet, and reversing flow directions in Arctic streams in summer, regulate riverine carbon replenishment and emissions.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 3
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    Effects of the hydrous domain in the mantle wedge on magma formation and mixing at the Northeast Lau Spreading Centre, SW Pacific (2022)
    (AGU) American Geophysical Union | Wiley
    Details
    Publication Date: 2024-02-07
    Description: Abundant volcanic activity occurs in the back-arc region of the northern Tofua island arc where the Northeast Lau Spreading Centre (NELSC) propagates southwards into older crust causing the formation of numerous seamounts at the propagating rift tip. An off-axis volcanic diagonal ridge (DR) occurs at the eastern flank of the NELSC, linking the large rear-arc volcano Niuatahi with the NELSC. New geochemical data from the NELSC, the southern propagator seamounts, and DR reveal that the NELSC lavas are tholeiitic basalts whereas the rear-arc volcanoes typically erupt lavas with boninitic composition. The sharp geochemical boundary probably reflects the viscosity contrast between off-axis hydrous harzburgitic mantle and dry fertile mantle beneath the NELSC. The new data do not indicate an inflow of Samoa plume mantle into the NELSC, confirming previously published He isotope data. The NELSC magmas form by mixing of an enriched and a depleted Indian Ocean-type upper mantle end-member implying a highly heterogeneous upper mantle composition in this area. Most NELSC lavas are little affected by a slab component implying that melting is adiabatic beneath the spreading center. The DR lavas show the influence of a component from the subducted Louisville Seamount Chain, which was previously thought to be restricted to the nearby arc volcanoes Niuatoputapu and Tafahi. This signature is rarely detected along the NELSC implying little mixing of melts from the low-viscosity hydrous portion of the mantle wedge beneath the rear-arc volcanoes into the melting region of the dry mantle beneath the NELSC.
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  • 4
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    Polyunsaturated fatty acids cause physiological and behavioral changes in Vibrio alginolyticus and Vibrio fischeri (2021)
    Wiley
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    Publication Date: 2021-10-01
    Electronic ISSN: 2045-8827
    Topics: Biology , Medicine
    Published by Wiley
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  • 5
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    Characterization of the genetic switch from phage ɸ13 important for Staphylococcus aureus colonization in humans (2021)
    Wiley
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    Publication Date: 2021-10-01
    Electronic ISSN: 2045-8827
    Topics: Biology , Medicine
    Published by Wiley
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  • 6
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    Elemental and biochemical nutrient limitation of zooplankton: A meta‐analysis (2022)
    Wiley
    In:  EPIC3Ecology Letters, Wiley, 25(12), pp. 2776-2792, ISSN: 1461-023X
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    Publication Date: 2023-09-22
    Description: Primary consumers in aquatic ecosystems are frequently limited by the quality of their food, often expressed as phytoplankton elemental and biochemical composition. However, the effects of these food quality indicators vary across studies, and we lack an integrated understanding of how elemental (e.g. nitrogen, phosphorus) and biochemical (e.g. fatty acid, sterol) limitations interactively influence aquatic food webs. Here, we present the results of a meta-analysis using 〉100 experimental studies, confirming that limitation by N, P, fatty acids, and sterols all have significant negative effects on zooplankton performance. However, effects varied by grazer response (growth vs. reproduction), specific manipulation, and across taxa. While P limitation had greater effects on zooplankton growth than fatty acids overall, P and fatty acid limitation had equal effects on reproduction. Furthermore, we show that: nutrient co-limitation in zooplankton is strong; effects of essential fatty acid limitation depend on P availability; indirect effects induced by P limitation exceed direct effects of mineral P limitation; and effects of nutrient amendments using laboratory phytoplankton isolates exceed those using natural field communities. Our meta-analysis reconciles contrasting views about the role of various food quality indicators, and their interactions, for zooplankton performance, and provides a mechanistic understanding of trophic transfer in aquatic environments.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 7
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    Measuring stability in ecological systems without static equilibria (2022)
    Wiley
    In:  EPIC3Ecosphere, Wiley, 13(12), ISSN: 2150-8925
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    Publication Date: 2023-09-22
    Description: Ecological stability refers to a range of concepts used to quantify how species and environments change over time and in response to disturbances. Most empirically tractable ecological stability metrics assume that systems have simple dynamics and static equilibria. However, ecological systems are typically complex and often lack static equilibria (e.g., predator–prey oscillations, transient dynamics, chaos). Failing to account for these factors can lead to biased estimates of stability, in particular, by conflating effects of observation error, process noise, and underlying deterministic dynamics. To distinguish among these processes, we combine three existing approaches: state space models; delay embedding methods; and particle filtering. Jointly, these provide something akin to a deterministically “detrended” version of the coefficient of variation, separately tracking variability due to deterministic dynamics versus stochastic perturbations. Moreover, these variability estimates can be used to forecast dynamics, classify underlying sources of stochastic dynamics, and estimate the “exit time” before a state change takes place (e.g., local extinction events). Importantly, the time-delay embedding methods that we employ make very few assumptions about the functions governing deterministic dynamics, which facilitates applications in systems with limited data and a priori biological knowledge. To demonstrate how complex dynamics without static equilibria can bias ecological stability estimates, we analyze simulated time series of abundance dynamics in a system with time-varying carrying capacity and empirically observed abundance dynamics of the green algae Chlamydomonas terricola grown in a diverse microcosm mixture under variable temperature conditions. We show that stability estimates based on raw observations greatly overestimate temporal variability and fail to accurately forecast time to extinction. In contrast, joint application of state space modeling, delay embedding, and particle filters were able to: (1) correctly quantify the contributions of deterministic versus stochastic variability; (2) successfully estimate “true” abundance dynamics; and (3) correctly forecast time to extinction. Our results therefore demonstrate the importance of accounting for effects of complex, nonstatic dynamics in studies of ecological stability and provide an empirically tractable and flexible toolkit for conducting these measurements.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 8
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    Antarctic ecosystem responses following ice‐shelf collapse and iceberg calving: Science review and future research (2021)
    Wiley
    In:  EPIC3WIREs Climate Change, Wiley, 12(1), ISSN: 1757-7780
    Details
    Publication Date: 2023-06-21
    Description: The calving of A-68, the 5,800-km2, 1-trillion-ton iceberg shed from the Larsen C Ice Shelf in July 2017, is one of over 10 significant ice-shelf loss events in the past few decades resulting from rapid warming around the Antarctic Peninsula. The rapid thinning, retreat, and collapse of ice shelves along the Antarctic Peninsula are harbingers of warming effects around the entire continent. Ice shelves cover more than 1.5 million km2 and fringe 75% of Antarctica's coastline, delineating the primary connections between the Antarctic continent, the continental ice, and the Southern Ocean. Changes in Antarctic ice shelves bring dramatic and large-scale modifications to Southern Ocean ecosystems and continental ice movements, with global-scale implications. The thinning and rate of future ice-shelf demise is notoriously unpredictable, but models suggest increased shelf-melt and calving will become more common. To date, little is known about sub-ice-shelf ecosystems, and our understanding of ecosystem change following collapse and calving is predominantly based on responsive science once collapses have occurred. In this review, we outline what is known about (a) ice-shelf melt, volume loss, retreat, and calving, (b) ice-shelf-associated ecosystems through sub-ice, sediment-core, and pre-collapse and post-collapse studies, and (c) ecological responses in pelagic, sympagic, and benthic ecosystems. We then discuss major knowledge gaps and how science might address these gaps. This article is categorized under: Climate, Ecology, and Conservation 〉 Modeling Species and Community Interactions.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 9
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    Cell size as driver and sentinel of phytoplankton community structure and functioning (2022)
    Wiley
    In:  EPIC3Functional Ecology, Wiley, 36(2), pp. 276-293, ISSN: 0269-8463
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    Publication Date: 2023-09-27
    Description: Body size is a decisive functional trait in many organisms, especially for phytoplankton, which span several orders of magnitude in cell volume. Therefore, the analysis of size as a functional trait driving species’ performance has received wide attention in aquatic ecology, amended in recent decades by studies documenting changes in phytoplankton size in response to abiotic or biotic factors in the environment. We performed a systematic literature review to provide an overarching, partially quantitative synthesis of cell size as a driver and sentinel of phytoplankton ecology. We found consistent and significant allometric relationships between cell sizes and the functional performance of phytoplankton species (cellular rates of carbon fixation, respiration and exudation as well as resource affinities, uptake and content). Size scaling became weaker, absent or even negative when addressing C- or volume-specific rates or growth. C-specific photosynthesis and population growth rate peaked at intermediate cell sizes around 100 µm3. Additionally, we found a rich literature on sizes changing in response to warming, nutrients and pollutants. Whereas small cells tended to dominate under oligotrophic and warm conditions, there are a few notable exceptions, which indicates that other environmental or biotic constraints alter this general trend. Grazing seems a likely explanation, which we reviewed to understand both how size affects edibility and how size structure changes in response to grazing. Cell size also predisposes the strength and outcome of competitive interactions between algal species. Finally, we address size in a community context, where size-abundance scaling describes community composition and thereby the biodiversity in phytoplankton assemblages. We conclude that (a) size is a highly predictive trait for phytoplankton metabolism at the cellular scale, with less strong and nonlinear implications for growth and specific metabolism and (b) size structure is a highly suitable sentinel of phytoplankton responses to changing environments. A free Plain Language Summary can be found within the Supporting Information of this article.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 10
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    In contrast to diatoms, cryptophytes are susceptible to iron limitation, but not to ocean acidification (2022)
    Wiley
    In:  EPIC3Physiologia Plantarum, Wiley, 174(1), ISSN: 0031-9317
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    Publication Date: 2024-05-07
    Description: Previous field studies in the Southern Ocean (SO) indicated an increased occurrence and dominance of cryptophytes over diatoms due to climate change. To gain a better mechanistic understanding of how the two ecologically important SO phytoplankton groups cope with ocean acidification (OA) and iron (Fe) availability, we chose two common representatives of Antarctic waters, the cryptophyte Geminigera cryophila and the diatom Pseudo-nitzschia subcurvata. Both species were grown at 2°C under different pCO2 (400 vs. 900 μatm) and Fe (0.6 vs. 1.2 nM) conditions. For P. subcurvata, an additional high pCO2 level was applied (1400 μatm). At ambient pCO2 under low Fe supply, growth of G. cryophila almost stopped while it remained unaffected in P. subcurvata. Under high Fe conditions, OA was not beneficial for P. subcurvata, but stimulated growth and carbon production of G. cryophila. Under low Fe supply, P. subcurvata coped much better with OA than the cryptophyte, but invested more energy into photoacclimation. Our study reveals that Fe limitation was detrimental for the growth of G. cryophila and suppressed the positive OA effect. The diatom was efficient in coping with low Fe, but was stressed by OA while both factors together strongly impacted its growth. The distinct physiological response of both species to OA and Fe limitation explains their occurrence in the field. Based on our results, Fe availability is an important modulator of OA effects on SO phytoplankton, with different implications on the occurrence of cryptophytes and diatoms in the future.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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