ALBERT

Description: Experimental studies linking community composition to functioning are typically confined to small and closed micro- or mesocosms. Such restricted conditions may affect both species’ biology and their environment. Yet, targeting simple features in the behaviour of species may circumvent these constraints. Focusing on ecological functions provided by dung beetles, we test whether large, open-top cages – MESOCLOSURES – will intercept the flight trajectories of beetles, thereby allowing manipulation of local community composition. MESOCLOSURES were built in both tropical forest (Brazil) and temperate grasslands (Finland), thus testing their general efficiency. Within the respective environments, we varied different aspects of MESOCLOSURE design: in the tropical forest, we examined the impact of MESOCLOSURE dimensions on exclusion efficiency, whereas in the temperate grassland, we assessed the potential for selectively excluding and including community members by different mesh sizes. In the temperate environment, we also went from method to application, using MESOCLOSURES to relate community composition to functioning under two simulated grazing regimes. MESOCLOSURES allowed efficient manipulation of dung beetle communities, maintaining dung beetle densities at intended levels in both temperate and tropical systems. In the tropics, the smallest cages (1 × 1 m) offered the highest contrast in beetle densities inside vs. outside of the fence, whereas the largest cages (9 × 9 m) offered the lowest. Nonetheless, densities inside cages never exceed one-fifth of those outside. At the temperate site, manipulations of community structure through mesh size yielded significant differences in functioning and suggested an interaction between small dung-dwelling species and large tunnelling species. Within cages, higher grazing was reflected in augmented dung removal. We conclude that MESOCLOSURES can be effectively used to study dung beetle functions across habitats and latitudes. As applied insights, the present study adds resolution to the significance of different functional groups of dung beetles and shows that grazing pressure may have an important impact on the ecosystem functions that they provide. Overall, this study suggests that targeted manipulation of dispersal may offer new solutions for linking fauna to ecosystem functions with minimal impact on the processes measured.

Description: Food supply is one of the main factors driving cold-water corals (CWC) distribution, which often concentrate on ridges where local near-bed turbulence/strong currents enhance food availability. However, efficiency in food capture is strongly dependent on current velocity. Moreover, seawater temperature may also affect feeding success, since polyp contraction or nematocyst function could be slower at temperatures below the natural thermal range of a species. The non-reef forming CWC Dendrophyllia cornigera occurs in areas at temperatures from 11 to 17 °C, but is apparently absent from most CWC reefs at temperatures constantly below 11 °C. This study thus aimed to assess if a reduction in feeding capacity may contribute to understand the absence of this CWC from strictly cold environments. The efficiency of D. cornigera to capture meso- and macrozooplankton was assessed under different flow speeds (2, 5 and 10 cm s − 1) and temperatures (8, 12, and 16 °C). Flow speeds did not significantly affect the capture of mesozooplankton, whereas capture of macrozooplankton was significantly enhanced with increasing flow speed. Both meso- and macrozooplankton captures were not significantly affected by temperature in D. cornigera. Overall, this CWC species is efficient in capturing zooplankton under a larger range of flow velocities than the widespread CWC Lophelia pertusa, whose capture efficiency significantly decreased from low to high flow speeds. Even if temperature does not directly affect the capture rates of D. cornigera, it may still influence the feeding capacity of this CWC since the capture rates at 8 °C were always in the lowest range of the observed values at each flow speed, and corals maintained at 8 °C required a much longer time to fully expand their polyps once they were placed in the incubation chambers, than corals maintained at 12 and 16 °C.

Description: At the largest time and space scales, the pace of erosion and chemical weathering is determined by tectonic uplift rates. Deviations from equilibrium arise from the transient response of landscape denudation to climatic and tectonic perturbations. We posit that the constraint of mass balance, however, makes it unlikely that such disequilibrium persists at the global scale over millions of years, as has been proposed for late Cenozoic erosion. We synthesize weathering fluxes, global sedimentation rates, sediment yields and tectonic motions to show a remarkable constancy in the pace of Earth-surface evolution over the last 10 Ma and support the null hypothesis – that global rates of landscape change have remained constant over this time period, despite global climate change and mountain building events. This work undermines the hypothesis that increased weathering due to mountain building or climate change was the primary agent for a decrease in global temperatures.

Description: Submarine groundwater discharge (SGD) is an important component of chemical fluxes in the coastal ocean. The composition of SGD is influenced by biogeochemical reactions that take place within the subterranean estuary (STE), the subsurface mixing zone of fresh and saline groundwaters. The STE is characterized by redox gradients that affect the speciation and mobility of redox-sensitive elements (RSEs). We examined the distributions and behavior of the RSEs Mo, U, V, and Cr within the larger redox framework of a shallow STE and evaluated the source-sink function of the STE for these elements. We found that the advection of water through the STE and the apparent respiration of organic matter drives the formation of a “classic” redox sequence typically observed in diffusion-dominated fine-grained sediments. High concentrations of dissolved organic matter (up to 2.9 mM) lead to extensive sulfide production (up to 1.8 mM) within 3 m of the surface. Both Mo and U are quantitatively removed as oxic surface waters mix into ferruginous and sulfidic zones. Molybdenum removal appears to occur where sulfide concentrations exceed ~ 11 μM, a previously reported threshold for quantitative formation of highly particle-reactive thiomolybdate species. Uranium removal apparently occurs via reduction and formation of insoluble phases or sorption to sediments. It is not clear how readily sequestered metals may be returned to solution, but SGD may be an important sink in the marine budget for both Mo and U. In contrast, both V and Cr show non-conservative addition across the salinity mixing gradient. Increases in pH appear to promote dissolution of V from minerals within the shallow aquifer, and mobilization may also be associated with dissolved organic matter. Chromium enrichment is associated with higher dissolved organic matter and is likely due to the formation of soluble Cr-organic complexes. Fluxes of these elements were constrained using SGD volume fluxes, determined using radium isotopes as well as direct discharge measurements by Lee-type seepage meters, and concentrations in directly-sampled seepage (Mo: − 0.21 to − 7.7 μmol m− 2 day− 1; U: − 0.02 to − 0.6 μmol m− 2 day− 1; V: 0.05 to 2.0 μmol m− 2 day− 1; Cr: 0.12 to 4.4 μmol m− 2 day− 1).

Description: Intercellular adhesion molecule-1 (ICAM-1) is distributed and expressed on cell surface and is present in circulation as soluble form (sICAM-1). Tumor necrosis factor-alpha (TNFα) and radical oxygen species (ROS) up-regulate the expression of ICAM-1. This study demonstrates for the first time in 18 Co cells, a myofibroblast cell line derived from human colonic mucosa, an up-regulation of ICAM-1 expression and sICAM-1 release induced by oxidative stress and TNFα stimulation. The intracellular redox state was modulated by L-buthionine-S,R-sulfoximine (BSO) or N-acetylcysteine (NAC), inhibitor and precursor respectively of GSH synthesis. ROS production increases in cells treated with BSO or TNFα, and this has been related to an up-regulation of ICAM-1 expression and sICAM-1 release. The involvement of metalloproteinases in ICAM-1 release has been demonstrated. Moreover, also expression and activation of A disintegrin and metalloproteinase 17, a membrane-bound enzyme known as TNFα-converting enzyme (TACE), have been related to ROS levels. This suggests the possible involvement of TACE in the cleavage of ICAM-1 on cell surface in condition of oxidative stress. NAC down-regulates the expression and release of ICAM-1 as well as the expression and activation of TACE. However, in TNFα stimulated cells NAC treatment reduces only in part ICAM-1 expression and sICAM-1 release. Given this TNFα may also act on these events by a redox-independent mechanism.

Description: The Neoarchean-Paleoproterozoic Transvaal Supergroup in South Africa contains the well-preserved stromatolitic Campbellrand-Malmani carbonate platform, which was deposited in shallow seawater shortly before the 2.40–2.32 Ga Great Oxidation Event (GOE). This platform is composed of alternating stromatolitic carbonates and mudstones and is a prominent candidate for (isotope-) geochemical mapping to investigate the appearance of very small amounts of free oxygen that accumulated in shallow waters preceding the GOE. Mo isotopes in sedimentary archives are widely used as a proxy for redox-changes in modern and ancient environments and recent evidence suggests that oxy-molybdate (MoO42−) is directly transferred from ocean water to inorganic carbonates with negligible fractionation, thus reflecting oceanic Mo isotope signatures. In this study we analyzed major and trace element compositions as well as Mo isotopic compositions of carbonate and mudstone samples from the KMF-5 drill core. Geochemical indicators, such as Fe and Mn concentrations and Fe-to-Mn abundance ratios reveal the preservation of some geochemical indicators despite the widespread silicification and dolomitization of the platform. Heavy δ30Si values of silicified carbonates between 0.53 and 2.35‰ point to Si precipitation from surface water during early diagenesis rather than to a later hydrothermal overprint. This assessment is supported by the frequent observation of rip-up structures of silica (chert) layers within the entire sedimentary succession. The δ98Mo values of whole rock samples throughout the Malmani-Campbellrand platform range between −0.82 and +1.40‰, similar to values reported for deeper slope carbonates from the Griqualand West area, but variations are independent from lithology or depositional water depth. These large variations in δ98Mo values indicate molybdenum redox cycling and thus the presence of free oxygen in the atmosphere-ocean system at that time, in agreement with earlier Mo isotopic studies on Campbellrand carbonates and shales. A similar range in δ98Mo values for carbonates between +0.40 and +0.87‰, however, was also found on the hand specimen scale, indicating the danger of a sample bias on the Mo isotopic stratigraphy of this carbonate platform. Results of previously unpublished adsorption experiments of Mo on CaCO3 clearly indicate that the Mo inventory of Malmani-Campbellrand carbonates was not only influenced by primary adsorption from seawater, but to a much larger degree by secondary processes during early diagenesis, which also affected the Mo isotopic composition of the samples on a local scale. Our results indicate that Mo concentrations and isotopic compositions in ancient stromatolitic carbonates were subject to redox changes within microbial mats and within the soft sediment during early diagenesis and later lithification, and as such cannot be used to quantitatively reconstruct the amount of free atmospheric oxygen or its fluctuations through Earth's history. Nevertheless, we interpret our heavy Mo isotopic signatures from carbonates as a minimum value for Neoarchean seawater and reinforce the assumption that free atmospheric oxygen built up a heavy oceanic Mo reservoir at that time.

Description: Throughout at least the past several centuries, El Niño-Southern Oscillation (ENSO) has played a significant role in human response to climate. Over time, increased attention on ENSO has led to a better understanding of both the physical mechanisms, and the environmental and societal consequences of the phenomenon. The prospects for seasonal climate forecasting emerged from ENSO studies, and were first pursued in ENSO studies. In this paper, we review ENSO's impact on society, specifically with regard to agriculture, water, and health; we also explore the extent to which ENSO-related forecasts are used to inform decision making in these sectors. We find that there are significant differences in the uptake of forecasts across sectors, with the highest use in agriculture, intermediate use in water resources management, and the lowest in health. Forecast use is low in areas where ENSO linkages to climate are weak, but the strength of this linkage alone does not guarantee use. Moreover, the differential use of ENSO forecasts by sector shows the critical role of institutions that work at the boundary between science and society. In a long-term iterative process requiring continual maintenance, these organizations serve to enhance the salience, credibility, and legitimacy of forecasts and related climate services. WIREs Clim Change 2015, 6:17–34. doi: 10.1002/wcc.294.

Description: The analysis of high-resolution vector magnetic data acquired by deep-sea submersibles (DSSs) requires the development of specific approaches adapted to their uneven tracks. We present a method that takes advantage of (1) the varying altitude of the DSS above the seafloor and (2) high-resolution multibeam bathymetric data acquired separately, at higher altitude, by an Autonomous Underwater Vehicle, to estimate the absolute magnetization intensity and the magnetic polarity of the shallow subseafloor along the DSS path. We apply this method to data collected by DSS Nautile on a small active basalt-hosted hydrothermal site. The site is associated with a lack of magnetization, in agreement with previous findings at the same kind of sites: the contrast between nonmagnetic sulfide deposits/stockwork zone and strongly magnetized basalt is sufficient to explain the magnetic signal observed at such a low altitude. Both normal and reversed polarities are observed in the lava flows surrounding the site, suggesting complex history of accumulating volcanic flows.

Description: Current limitations in technology have prevented an extensive analysis of the connections among neurons, particularly within nonmammalian organisms. We developed a transsynaptic viral tracer originally for use in mice, and then tested its utility in a broader range of organisms. By engineering the vesicular stomatitis virus (VSV) to encode a fluorophore and either the rabies virus glycoprotein (RABV-G) or its own glycoprotein (VSV-G), we created viruses that can transsynaptically label neuronal circuits in either the retrograde or anterograde direction, respectively. The vectors were investigated for their utility as polysynaptic tracers of chicken and zebrafish visual pathways. They showed patterns of connectivity consistent with previously characterized visual system connections, and revealed several potentially novel connections. Further, these vectors were shown to infect neurons in several other vertebrates, including Old and New World monkeys, seahorses, axolotls, and Xenopus. They were also shown to infect two invertebrates, Drosophila melanogaster, and the box jellyfish, Tripedalia cystophora, a species previously intractable for gene transfer, although no clear evidence of transsynaptic spread was observed in these species. These vectors provide a starting point for transsynaptic tracing in most vertebrates, and are also excellent candidates for gene transfer in organisms that have been refractory to other methods.

Description: The diversity of stony corals displays one of the most exemplary latitudinal gradients on the planet, yet the evolutionary dynamics that produced this pattern remains unclear. Using both paleontological and distributional data, we compare the origination, extinction and immigration levels between low and high latitudes since the earliest proliferation of the group during the mid‐Triassic. Altogether, first and last occurrence localities in the fossil record do not support a positive preference towards either latitudinal bin. Nonetheless, considering past and present scleractinian fauna, the process of extinction has been apparently more pronounced at higher latitudes based on face values and correlation coefficients. Far above these differences, immigration of extant taxa has been substantially higher towards the tropics than to temperate regions. While the net dispersal toward low latitudes persists in all temporal intervals, the gradient of diversity was largely built up during the Cenozoic Era and only becomes significantly steep from the Neogene Period onwards. This dynamic supports the ‘into the tropical museum’ model, which suggests that tropics have historically acted as a center of accumulation for marine biodiversity.