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An intensive observation period was conducted in September 2017 in the central Namib, Namibia, as part of the project Namib Fog Life Cycle Analysis (NaFoLiCA). The purpose of the field campaign was to investigate the spatial and temporal patterns of the coastal fog that occurs regularly during nighttime and morning hours. The fog is often linked to advection of a marine stratus that intercepts with the terrain up to 100 km inland. Meteorological data, including cloud base height, fog deposition, liquid water path, and vertical profiles of wind speed/direction and temperature, were measured continuously during the campaign. Additionally, profiles of temperature and relative humidity were sampled during five selected nights with stratus/fog at both coastal and inland sites using tethered balloon soundings, drone profiling, and radiosondes. This paper presents an overview of the scientific goals of the field campaign; describes the experimental setup, the measurements carried out, and the meteorological conditions during the intensive observation period; and presents first results with a focus on a single fog event.

Functional structure and diversity of soil free-living nematodes in a desert environment depend on plant gender and sampling site. The objective of this study was to compare the composition, abundance and tropic group of soil free-living nematodes in the upper 0–10 cm soil layer under the male and female Acanthosicyos horridus Welw. ex Hook. f. plants and in the inter-shrub open areas (control) in the Namib Desert, Namibia in April 2015. Soil moisture, organic matter (OM) and pH was also analyzed. Free-living nematodes were extracted from 100 g soil using the Baermann funnel procedure, and total number of nematodes was counted under a microscope. Community composition and diversity of soil free-living nematodes were analyzed using 18S rDNA sequences. Results indicated that a total of 67 groups, including 64 species, 2 genera and 1 family were identified. Feeding behavior of 58 species were identified as follows: 15 bacteria-feeding species, 12 fungi-feeding species, 10 plant-parasite species, 5 omnivorous-predator species, 8 animal-parasite species, 5 invertebrate-parasite species and 3 non-free-living nematodes, known as marine species. Moreover, soil free-living nematodes were found to be affected by sampling locations and plant gender, and community composition and density of these nematodes were strongly influenced by soil OM content. Result confirmed that spatial location and plant cover were main factors influencing the diversity of soil free-living nematodes. Moreover, molecular tools were found to be very useful in defining the richness of soil non-free-living nematodes. In conclusion, the results elucidated the importance of biotic variables in determining the composition and abundance of soil free-living nematodes in the Namib Desert, Namibia.

In a xeric environment, plant ecophysiological adaptation helps determine soil microbial-community structure beneath plant canopies. We compared the plant-associated microbiota of the dioecious perennial plant Acanthosicyos horridus (Nara) in the Namib Desert in relation to soil parameters, climate, and plant gender. Abiotic soil attributes (soil moisture, total organic matter, salinity) and plant gender were among the main factors correlating with soil microbial-community biomass, basal respiration, and substrate-induced respiration rates. These varied between an extremely arid Far East (FE) site and a less arid site in the sandy, saline delta ecosystem. A. horridus gender was correlated with soil microbiome composition and activity, and varied between the relatively humid and more xeric environments. This study highlighted the apparent role of plant dimorphism in determining soil biotic composition and diversity in a desert ecosystem; however, the cause of the relationship between plant gender and microbial community remains uncertain. Possible explanations include gender-related variation in the plant itself, a link to certain abiotic soil conditions that incidentally influence plant gender, or a combination of both. This is the first example of gender-related differences in microbiota reported in a plant from an arid environment, and only the second example from the plant world in general.

International audience; Atmospheric aerosols contribute significantly to the uncertainty in radiative forcing effects that influence the climate as well as posing a significant health risk to humans. The climatic implications of aerosols are dependent on many variables, including aerosol size, shape, chemical composition, and position in the atmospheric column. The radiative impact of aerosols transported over the west coast of southern Africa has been found, in particular, to be complicated by the aforementioned aerosol properties. This study investigated the columnar optical properties of aerosols over Gobabeb, Namibia (23.5621° S, 15.0409° E, 405 m asl) using sunphotometer data between December 2014 and November 2015. Aerosol mean optical depth AOD500 had its maximum and minimum values in 2015 August (0.37±0.30) and June (0.06±0.02), respectively. The Angström parameter was mostly above unity during the study period and indicated the prevalence of fine particles for the most part of the year with maximum and minimum values observed in August 2015 (1.44±0.19) and December 2014 (0.57±0.19), respectively. The columnar water vapor was highest in January (2.62±0.79) and lowest in June (0.76±0.27). The volume size distribution showed the fine particles having a mean radius of about 0.16 μm and the coarse mode had variation in sizes with a radius ranging between 3 μm and 7 μm. The single scattering albedo at visible wavelengths ranged between 0.83 and 0.91. The phase function was high at small angles but minimum at about 140° in all seasons. The radiative forcing showed a heating effect in all seasons with maximum and minimum in winter (9.41 Wm-2) and autumn (3.64 Wm-2), respectively. Intercomparison of the sunphotometer data with the Moderate Resolution Imaging Spectroradiometer (MODIS) showed that the satellite sensor overestimates the aerosol loading compared to the ground-based sunphotometer measurements. Both sets of observations were better correlated during the spring and winter seasons than for the summer and autumn.

Aim To assess spatial patterns of genetic and species-level diversity for Namib Desert Collembola using mitochondrial DNA cytochrome c oxidase subunit I (COI) gene sequences. Location Namib Desert gravel plains. Taxon Collembola (springtails). Methods A total of 77 soil samples were collected along NE-SW (60 km) and E-W (160 km) transects from within a 4,000 km2 area of the Namib Desert gravel plains. We extracted 434 springtails from the 37 samples which contained Collembola and sequenced them at the COI gene locus. In the absence of specific taxonomic keys and previous genetic data for these taxa, we used Generalized Mixed Yule Coalescent (GMYC) analyses to provide putative species-level designations. Results We obtained 341 successful COI sequences, 175 of which were unique haplotypes. GMYC analyses identified 30 putative species, with up to 28% sequence divergence (uncorrected p-distance). The distribution of genetic variants was disjunct, with 97% of haplotypes and 70% of "GMYC species" found only at single sites. Main conclusions Dispersal events, although rare, may be facilitated by environmental events such as prevailing onshore winds or occasional flow of rainwater to the coast. We conclude that the high genetic diversity we observed is the result of ancient springtail lineages, patchy distribution of suitable habitats, and limited dispersal (gene flow) among habitable locations.

There is increasing interest in using &ldquo, real-world pedagogy&rdquo, to train students in ways that make them better able to contribute toward a more sustainable society. While there is a robust body of literature on the competencies that students need as sustainability professionals, there is a lack of specific guidance in the literature on how to teach for competency development or on how to structure a program or course to support competency development. Our research addresses this gap in the literature through a description and autoethnographic reflection on the design and early implementation of a &ldquo, real-world&rdquo, course. The course is from the Environmental Studies Program at Dartmouth College (Hanover, NH, USA), but it takes place in the environs of the Gobabeb Research and Training Centre in the Namib Desert of Namibia and in nearby Topnaar settlements. Our research objective was to articulate strategies to address the primary pedagogical challenges that we faced during the design and first five iterations of the course. These include: How do we frame this course and communicate it to students in a way that is understandable and works within the particular context and constraints of the course? Can we provide students with a coherent framework that helps them to understand the approach and also provides a platform for thoughtful consideration, acquisition, and retention of appropriate competencies? How do we develop collaborations with our community partners that are ethical and effective? How do we frame these real-world experiences in a way that allows for students to integrate their experience with the theory and broader empiricism they learn on campus? To address these pedagogic challenges, we framed the course as a research-based course, more specifically community-based research (CBR), conducted in a social-ecological system (SES). We developed lower-level strategies for implementing this framing, including preparing students for collaborative research, encouraging student ownership of their learning, linking theory to research, and thoughtfully navigating time constraints. Furthermore, program-level and student-level engagement with community have been critical for avoiding becoming &ldquo, helicopter researchers.&rdquo, Drawing on our personal reflections and those of our community partners, we conclude with a discussion of emergent outcomes and the next steps for continual improvement and adaptation.

CurrentPennisetum glaucum(L.) R. BR. cultivars in Namibia have overall poor performance posing a threat to the nation’s food security because this crop is staple for over 70% of the Namibian population. The crop suffers from undesirable production traits such as susceptibility to diseases, low yield, and prolonged reproductive cycle. This study aimed to understand the genetic diversity of the crop in Namibia by simple sequence repeats (SSRs) and morphology analysis. A total of 1441 genotypes were collected from the National Gene Bank representing all the Namibian landraces. A sample of 96 genotypes was further analyzed by SSR using Shannon-Wiener diversity index and revealed a value of 0.45 indicating low genetic diversity. Ordination using Principal Coordinate Analysis (PCoA) on SSR data confirmed clusters generated by UPGMA for the 96P. glaucumaccessions. UPGMA phenograms of 29 morphological characterized genotypes were generated for SSR and morphology data and the two trees revealed 78% resemblance. Lodging susceptibility, tillering attitude, spike density, fodder yield potential, early vigour, and spike shape were the phenotypic characters upon which some clusters were based in both datasets. It is recommended that efforts should be made to widen the current gene pool in Namibia.