Could Biological Soil Crusts Act as Natural Fire Fuel Breaks in the Sagebrush Steppe?

For decades, large portions of the semi-arid sagebrush ecosystem have been experiencing increased frequency and extent of wildfire, even though small, infrequent fire is a natural disturbance in this ecosystem (Baker, 2006). Increased wildfire is threatening the existence of sagebrush ecosystems and the wildlife species that depend upon them (Baker, 2006; Coates et al., 2016). Increased wildfire in sagebrush ecosystems is often driven by invasive annual grasses, especially cheatgrass, Bromus tectorum (L.). Invasion can initiate a trajectory toward a “grass-fire cycle”, in which cheatgrass increases fine fuel loadings that promote fire, and native plant species do not recover quickly after fire, leading frequently burned sites to transition to monocultures of cheatgrass (Brooks et al., 2004). Although cheatgrass has been extensively studied in the sagebrush steppe, less attention has been given to the organisms that would have filled the interspaces that cheatgrass replaces, namely, biological soil crusts (“biocrusts”). Semi-arid environments are characterized by sparse cover of vascular plants and substantial cover of biocrusts (Belnap & Lange, 2001). Biocrusts contain organisms that live on the soil surface and include lichens, mosses, and light algal crusts (including cyanobacteria). Although biocrusts were included in some of the first descriptions of the vegetation in the region (Flowers, 1934), biocrusts are rarely included in contemporary studies of sagebrush ecosystems. Comprehensive community studies have concluded consistent negative relationships between abundance of biocrusts and annual invasive grasses, specifically cheatgrass (Condon & Pyke, 2018a,b; Daubenmire, 1970). We postulate that biocrusts, and particularly lichens, facilitate a pattern of small, infrequent, low intensity fire given their association with reduced fine fuels (cheatgrass)

Ecohydrodynamics of Cold-Water Coral Reefs:A Case Study of the Mingulay Reef Complex (Western Scotland)

Ecohydrodynamics investigates the hydrodynamic constraints on ecosystems across different temporal and spatial scales. Ecohydrodynamics play a pivotal role in the structure and functioning of marine ecosystems, however the lack of integrated complex flow models for deep-water ecosystems beyond the coastal zone prevents further synthesis in these settings. We present a hydrodynamic model for one of Earth's most biologically diverse deep-water ecosystems, cold-water coral reefs. The Mingulay Reef Complex (western Scotland) is an inshore seascape of cold-water coral reefs formed by the scleractinian coral Lophelia pertusa. We applied single-image edge detection and composite front maps using satellite remote sensing, to detect oceanographic fronts and peaks of chlorophyll a values that likely affect food supply to corals and other suspension-feeding fauna. We also present a high resolution 3D ocean model to incorporate salient aspects of the regional and local oceanography. Model validation using in situ current speed, direction and sea elevation data confirmed the model's realistic representation of spatial and temporal aspects of circulation at the reef complex including a tidally driven current regime, eddies, and downwelling phenomena. This novel combination of 3D hydrodynamic modelling and remote sensing in deep-water ecosystems improves our understanding of the temporal and spatial scales of ecological processes occurring in marine systems. The modelled information has been integrated into a 3D GIS, providing a user interface for visualization and interrogation of results that allows wider ecological application of the model and that can provide valuable input for marine biodiversity and conservation applications

Genetics of Perceived Family Interaction From 12 to 17 Years of Age

Correction: Volume: 49 Issue: 5 Pages: 484-484 DOI: 10.1007/s10519-019-09963-w Published: SEP 2019We analyzed how the effects of genetic and environmental factors on the perceptions of family interaction change from early to late adolescence. The data were collected by postal surveys on Finnish twins (N=4808) at 12, 14 and 17years of age and analyzed using genetic twin modeling. Additive genetic factors explained a modest share of the variation in perceived relational support (a(2)=0.30 in boys and 0.18 in girls) and relational tensions (a(2)=0.13 and 0.14, respectively) at 12years of age, with the proportions becoming larger through 17years of age (a(2)=0.53 in boys and 0.49 in girls for relational support; a(2)=0.35 in boys and 0.33 in girls for relational tensions). Simultaneously, the role of environment shared by co-twins decreased. These findings suggest that the associations between perceived family interaction and other factors in adulthood should be interpreted with caution, because they partly reflect genetic background, whereas in childhood, they may provide more reliable information on parental characteristics.Peer reviewe

Thermally excited tunneling from a metastable electronic state in a single-Cooper-pair transistor

International audienceMetastable electron traps and two-level systems are common in solid-state devices and lead to background charge movement and charge noise in single-electron and singleCooper-pair transistors. We present measurements of the real-time capture and escape of individual electrons in metastable trapped states at very low temperatures, leading to charge offsets close to 1e. The charge movement exhibits thermal excitation to a hysteretic tunneling transition. The temperature dependence and hysteresis can be explained by the coupling of a two-level system to a quasiparticle trap

Thermal excitation of large charge offsets in a single-Cooper-pair transistor

International audienceCharge offsets and two-level fluctuators are common in single-electron transistors (SET) with a typical magnitude |∆Q| < 0.1e. We now present measurements in a 2e-periodic single-Cooper-pair transistor (SCPT) which exhibited hysteretic charge offsets close to 1e. The real-time capture and escape of individual electrons in metastable trapped states was measured at very low temperatures. This enabled the dynamics of the transitions to be investigated in detail, demonstrating thermal excitation to a hysteretic tunneling transition. We also show that, allowing for the hysteresis, the metastable states are in thermal equilibrium with each other. The observed temperature dependence and hysteresis can be explained by the coupling of a two-level fluctuator to a quasiparticle trap

Photorespiration: metabolic pathways and their role in stress protection

Photorespiration results from the oxygenase reaction catalysed by ribulose-1,5-bisphosphate carboxylase/ oxygenase. In this reaction glycollate-2-phosphate is produced and subsequently metabolized in the photorespiratory pathway to form the Calvin cycle intermediate glycerate-3-phosphate. During this metabolic process, CO2 and NH3 are produced and ATP and reducing equivalents are consumed, thus making photorespiration a wasteful process. However, precisely because of this ine¤ciency, photorespiration could serve as an energy sink preventing the overreduction of the photosynthetic electron transport chain and photoinhibition, especially under stress conditions that lead to reduced rates of photosynthetic CO2 assimilation. Furthermore, photorespiration provides metabolites for other metabolic processes, e.g. glycine for the synthesis of glutathione, which is also involved in stress protection. In this review, we describe the use of photorespiratory mutants to study the control and regulation of photorespiratory pathways. In addition, we discuss the possible role of photorespiration under stress conditions, such as drought, high salt concentrations and high light intensities encountered by alpine plants

Use of the Alaskan Beaufort Sea by Bowhead Whales (Balaena mysticetus) Tagged with Satellite Transmitters, 2006 – 18

We used satellite telemetry to examine bowhead whale movement behavior, residence times, and dive behavior&nbsp;in the Alaskan Beaufort Sea, 2006 – 18. We explored the timing and duration of use of three subregions (western, central, eastern) within the Alaskan Beaufort Sea and applied a two-state switching state-space model to infer bowhead whale behavior state as either transiting or lingering. Transiting whales made direct movements whereas lingering whales changed direction frequently and were presumably feeding. In spring, whales migrated across the Alaskan Beaufort Sea in 7.17 ± 0.41 days, primarily off the continental shelf over deep water. During the autumn migration, whales spent over twice as much time crossing the Alaskan Beaufort Sea than in spring, averaging 18.66 ± 2.30 days, spending 10.05 ± 1.22 days in the western subregion near Point Barrow. Most whales remained on the shelf during the autumn migration and frequently dove to the seafloor, where they spent 45% of their time regardless of behavioral state. Consistent dive behavior in autumn suggests that the whales were looking for food while migrating, and the identification of lingering locations likely reflects feeding. The lack of lingering locations in the eastern and central subregions suggests that prey densities are rarely sufficient to warrant whales pausing their migration for multiple days, unlike in the western subregion near Point Barrow, where bowhead whales regularly&nbsp;lingered for long periods of time.À l’aide de la télémétrie satellitaire, nous avons examiné les comportements de déplacement des baleines boréales,&nbsp;leurs temps de séjour et leurs comportements de plongée dans les eaux alaskiennes de la mer de Beaufort entre 2006 et 2018. Nous avons exploré le moment et la durée d’utilisation de trois sous-régions (ouest, centre et est) des eaux alaskiennes de la mer de Beaufort et appliqué un modèle à changement binaire espace-état afin de déduire l’état du comportement des baleines boréales comme étant soit en mode transit, soit en mode flânerie. Les baleines en mode transit se déplaçaient de manière directe, tandis que celles en mode flânerie changeaient souvent de direction et étaient probablement en train de se nourrir. Au printemps, les baleines migraient dans les eaux alaskiennes de la mer de Beaufort en 7,17 ± 0,41 jours, principalement au large du plateau continental, dans les profondeurs. Durant la migration automnale, les baleines passaient plus de deux fois plus de temps à traverser les eaux alaskiennes de la mer de Beaufort qu’au printemps, en moyenne 18,66 ± 2,30 jours, passant 10,05 ± 1,22 jours dans la sous-région de l’ouest, près de Point Barrow. Pendant la migration automnale, la plupart des baleines restaient dans le plateau continental et plongeaient souvent jusqu’au plancher océanique, où elles passaient 45 % de leur temps, peu importe leur état de comportement. À l’automne, le comportement de plongée régulier suggère que les baleines étaient à la recherche de nourriture pendant leur migration, et les lieux où elles flânaient étaient vraisemblablement indicateurs d’un mode d’alimentation. L’absence de lieux de flânerie dans les sous-régions de l’est et du centre suggère que la densité des proies est rarement suffisante pour que les baleines justifient d’interrompre leur migration pendant plusieurs jours, contrairement à la sous-région de l’ouest, près de Point Barrow, où les baleines boréales flânaient régulièrement pendant de longues périodes