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Upwelling processes bring nutrient-rich waters from the deep ocean to the surface. Areas of upwelling are often associated with high productivity, offering great economic value in terms of fisheries. The sensitivity of spring/summer-time coastal upwelling systems to climate change has recently received a lot of attention. Several studies have suggested that their intensity may increase in the future while other authors have shown decreasing intensity in their equatorward portions. Yet, recent observations do not show robust evidence of this intensification. The Senegalo-Mauritanian upwelling system (SMUS) located at the southern edge of the north Atlantic system (12°N–20°N) and most active in winter/spring has been largely excluded from these studies. Here, the seasonal cycle of the SMUS and its response to climate change is investigated in the database of the Coupled Models Inter comparison Project Phase 5 (CMIP5). Upwelling magnitude and surface signature are characterized by several sea surface temperature and wind stress indices. We highlight the ability of the climate models to reproduce the system, as well as their biases. The simulations suggest that the intensity of the SMUS winter/spring upwelling will moderately decrease in the future, primarily because of a reduction of the wind forcing linked to a northward shift of Azores anticyclone and a more regional modulation of the low pressures found over Northwest Africa. The implications of such an upwelling reduction on the ecosystems and local communities exploiting them remains very uncertain.

Abstract Solar mirrors for concentrated solar power (CSP) plants are expected to last at least 30 years. As this delay is far too long to obtain useful information regarding in-service degradation, accelerated approaches to weathering testing are performed by manufacturers and research laboratories in order to quickly assess the lifetime of commercial or new technologies. However, most published studies that have been performed in the CSP field are based on phenomenological approaches. The characterization of the degradation, which mostly considers reflectance loss, has rarely been linked to physical or chemical processes that are responsible for the degradation of properties. Furthermore, the general laws that can be established from these data to establish material behaviour are empirical. Ageing tests have been used for many years in other fields, particularly in the domain of polymeric materials. The impacts on the material properties of stress factors such as temperature, irradiation and humidity have been extensively studied, and models have been proposed for different kinds of materials, even though most are based on empirical observations. One of the goals of this article is to determine how these models could be applied to the weathering of solar mirrors, and as such, the goal of this paper is to provide a critical review of the various models that are most used and accepted by the scientific community. All of these models include material-dependent parameters, and the values that have been determined in these studies are reported here to list their order of magnitude.

AbstractStream microbes that occur in the Mediterranean Basin have been shown to possess heightened sensitivity to intensified water stress attributed to climate change. Here, we investigate the effects of long-term drought (150 days), storms and rewetting (7 days) on the diversity and composition of archaea, bacteria and fungi inhabiting intermittent streambed sediment (surface and hyporheic) and buried leaves. Hydrological alterations modified the archaeal community composition more than the bacterial community composition, whereas fungi were the least affected. Throughout the experiment, archaeal communities colonizing sediments showed greater phylogenetic distances compared to those of bacteria and fungi, suggesting considerable adaptation to severe hydrological disturbances. The increase in the class abundances, such as those of Thermoplasmata within archaea and of Actinobacteria and Bacilli within bacteria, revealed signs of transitioning to a drought-favoured and soil-like community composition. Strikingly, we found that in comparison to the drying phase, water return (as sporadic storms and rewetting) led to larger shifts in the surface microbial community composition and diversity. In addition, microhabitat characteristics, such as the greater capacity of the hyporheic zone to maintain/conserve moisture, tended to modulate the ability of certain microbes (e.g., bacteria) to cope with severe hydrological disturbances.

Laboratory rotational spectra of norbornadiene and its cyano derivatives were recorded using chirped-pulse millimetre-wave spectroscopy. These molecules were then searched for in the starless core TMC-1 using the QUIJOTE line survey.

The photoactive Orange Carotenoid Protein (OCP) photoprotects cyanobacteria cells by quenching singlet oxygen and excess excitation energy. Its N-terminal domain is the active part of the protein, and the C-terminal domain regulates the activity. Recently, the characteristics of a family of soluble carotenoid-binding proteins (Helical Carotenoid Proteins [HCPs]), paralogs of the N-terminal domain of OCP, were described. Bioinformatics studies also revealed the existence of genes coding for homologs of CTD. Here, we show that the latter genes encode carotenoid proteins (CTDHs). This family of proteins contains two subgroups with distinct characteristics. One CTDH of each clade was further characterized, and they proved to be very good singlet oxygen quenchers. When synthesized in Escherichia coli or Synechocystis PCC 6803, CTDHs formed dimers that share a carotenoid molecule and are able to transfer their carotenoid to apo-HCPs and apo-OCP. The CTDHs from clade 2 have a cysteine in position 103. A disulfide bond is easily formed between the monomers of the dimer preventing carotenoid transfer. This suggests that the transfer of the carotenoid could be redox regulated in clade 2 CTDH. We also demonstrate here that apo-OCPs and apo-CTDHs are able to take the carotenoid directly from membranes, while HCPs are unable to do so. HCPs need the presence of CTDH to become holo-proteins. We propose that, in cyanobacteria, the CTDHs are carotenoid donors to HCPs.

Abstract Trees adjust their architecture to acclimate to various external stressors, which regulates ecological functions that are needed for growth, reproduction, and survival. Human activities, however, are fragmenting natural habitats apace and could affect tree architecture and allometry, but quantitative assessments remain lacking. Here, we leverage ground surveys of terrestrial LiDAR in Central Amazonia to comprehensively assess forest edge effects on tree architecture and allometry, and their associated impacts on the forest biomass 40 years after fragmentation. We found that young trees colonising the forest fragments have thicker branches and architectural traits that maximise light capture, and can produce 50% more wood than their counterparts of similar stem size and height in interior forests. Large trees that have survived disturbances arising from forest fragmentation are able to acclimate and maintain their wood production, but damages that reduce tree height near the edges can lead to a 30% decline of their woody volume. Despite the large wood production of colonising trees, changes in tree architecture lead to a net loss of 6.6 Mg ha-1 of the forest aboveground biomass, which account for 20% of all edge-related aboveground biomass losses of fragmented Amazonian forests (34.3 Mg ha-1). Our findings show a strong influence of edge effects on tree architecture and allometry, and reveal an additional unaccounted factor that exacerbates carbon losses in fragmented forests.