Drivers of diversity and community structure of bees in an agroecological region of Zimbabwe

Worldwide bees provide an important ecosystem service of plant pollination. Climate change and land-use changes are among drivers threatening bee survival with mounting evidence of species decline and extinction. In developing countries, rural areas constitute a significant proportion of the country's land, but information is lacking on how different habitat types and weather patterns in these areas influence bee populations.This study investigated how weather variables and habitat-related factors influence the abundance, diversity, and distribution of bees across seasons in a farming rural area of Zimbabwe. Bees were systematically sampled in five habitat types (natural woodlots, pastures, homesteads, fields, and gardens) recording ground cover, grass height, flower abundance and types, tree abundance and recorded elevation, temperature, light intensity, wind speed, wind direction, and humidity. Zero-inflated models, censored regression models, and PCAs were used to understand the influence of explanatory variables on bee community composition, abundance, and diversity.Bee abundance was positively influenced by the number of plant species in flower (p < .0001). Bee abundance increased with increasing temperatures up to 28.5°C, but beyond this, temperature was negatively associated with bee abundance. Increasing wind speeds marginally decreased probability of finding bees.Bee diversity was highest in fields, homesteads, and natural woodlots compared with other habitats, and the contributions of the genus Apis were disproportionately high across all habitats. The genus Megachile was mostly associated with homesteads, while Nomia was associated with grasslands.Synthesis and applications. Our study suggests that some bee species could become more proliferous in certain habitats, thus compromising diversity and consequently ecosystem services. These results highlight the importance of setting aside bee-friendly habitats that can be refuge sites for species susceptible to land-use changes

Ecological responses of periphyton dry mass and epilithic diatom community structure for different atrazine and temperature scenarios

Climate change–induced temperature increase may influence the ecotoxicity of agricultural herbicides such as atrazine and consequently negatively impact aquatic biota. The objective of this study was to assess the effects of increased temperature on the ecotoxicity of atrazine to diatom community structure and stream periphyton load using laboratory microcosm experiments. A natural periphyton community from the Mukwadzi River, Zimbabwe, was inoculated into nine experimental systems containing clean glass substrates for periphyton colonisation. Communities were exposed to 0 µg∙L-1 (control), 15 µg∙L-1 and 200 µg∙L-1 atrazine concentrations at 3 temperature levels of 26°C, 28°C and 30°C. Periphyton dry weight and community taxonomic composition were analysed on samples collected after 1, 2 and 3 weeks of colonisation. A linear mixedeffects model was used to analyse the main and interactive effects of atrazine and temperature on dry mass, species diversity, evenness and richness. Temperature and atrazine had significant additive effects on species diversity, richness and dry mass. As temperature increased, diatom species composition shifted from heat-sensitive species such as Achnanthidium affine to heat-tolerant species such as Achnanthidium exiguum and Epithemia adnata. Increasing temperature in aquatic environments contaminated with atrazine results in sensitive and temperature-intolerant diatoms being eliminated from periphyton communities. Climate change will exacerbate effects of atrazine on periphyton dry mass and diatom community structure.Keywords: ecotoxicology, microcosm, biomonitoring, climate chang

Terrestrial threats dominate the waterbird landscape of fear in a savannah pan wetland system

International audienceNatural or anthropogenic disturbances (stimuli that trigger a behavioural response from animals) can have direct conse-quences on fitness and population trends. This study aimed at investigating the relative influence of three types of distur-bances (mammalian herbivores, terrestrial threats from ground predators and aerial threats) on the responses by waterbirds at waterpans in Hwange National Park (HNP, Zimbabwe) and adjacent land uses. Thirteen waterpans were monitored during daylight hours between years 2015 and 2017 and responses of waterbirds to the three forms of disturbances were recorded. Logistic regressions revealed that the likelihood of responding was highest after terrestrial threats; with individu-als/groups that were initially engaged in non-feeding activities that allowed vigilance, responding the most. Wildfowl spe-cies spent significantly longer time flying (compared to waders and generalists), more so in communal areas (CAs) than HNP, and after terrestrial threats compared to aerial threats and herbivore disturbances. We did not find any differences in probability of responding across land uses probably because there is less human disturbance in HNP, but predation risk is high. Further, even though there are less terrestrial predators in CAs, domestic dogs may be maintaining the stimuli. We conclude that terrestrial threats are least tolerated, with species most susceptible to human predation (i.e. wildfowl) losing more time avoiding them. Interestingly, only acute aerial threats induced departure from waterpans. Our findings have a direct implication for waterbird conservation as herbivore and human density in this area are currently increasing

Bird tolerance to humans in open tropical ecosystems

AbstractAnimal tolerance towards humans can be a key factor facilitating wildlife–human coexistence, yet traits predicting its direction and magnitude across tropical animals are poorly known. Using 10,249 observations for 842 bird species inhabiting open tropical ecosystems in Africa, South America, and Australia, we find that avian tolerance towards humans was lower (i.e., escape distance was longer) in rural rather than urban populations and in populations exposed to lower human disturbance (measured as human footprint index). In addition, larger species and species with larger clutches and enhanced flight ability are less tolerant to human approaches and escape distances increase when birds were approached during the wet season compared to the dry season and from longer starting distances. Identification of key factors affecting animal tolerance towards humans across large spatial and taxonomic scales may help us to better understand and predict the patterns of species distributions in the Anthropocene.</jats:p

Trends in savannah waterbirds: protected area effect and influence of global threats on differing guilds

Understanding species threats is underpinned by information on their population trends. We investigated the contribution of population drivers associated with 86 waterbird species’ trends at a local scale, Hwange National Park (HNP) and a national scale (Zimbabwe). We used logistic regression models to test whether waterbird population trends differed across migration types, seasons, species traits (guild, weight, index of diet variety, social foraging and breeding systems), scale of use by humans (whether the waterbird species utilisation is documented at local or international scale) and susceptibility to hunting and diseases. In HNP during the wet season, waterbird population trends were mostly stable or increasing. During the dry season, larger species were more likely to be recorded, more so for those threatened by hunting, compared with the species limited by diseases. Colonial resident waterbirds had more increasing population trends in HNP in comparison to the solitary ones. At the Zimbabwean scale, records for 35% of species decreased during the wet season, and the declines were more pronounced in large birds. During thedry season, species threatened by habitat disturbances were more likely to decrease. Habitat disturbances and/or use of waterbirds at the international scale are more associated with declining trends than ecological and life history traits. We have shown that HNP, a protected area with mostly a pan wetland-system is supporting growing waterbird populations despite the species facing global negative population trends. FrenchTitle: Tendances des oiseaux d’eau de la savane: effet des aires protégées et influence des menaces mondiales sur les différentes guildes. La compréhension des menaces pesant sur les espèces repose sur des informations sur les tendances des populations. Nous avons étudié la contribution des facteurs de population associés aux tendances de 86 espèces d’oiseaux d’eau à l’échelle locale (parc national de Hwange (PNH) et à l’échelle nationale (Zimbabwe). Nous avons utilisé des modèles de régression logistique pour tester si les tendances des populations d’oiseaux d’eau variaient selon les types de migration et les saisons. Les caractéristiques des espèces (guilde, poids, indice de variété alimentaire, systèmes de recherche de nourriture et de reproduction), l’échelle d’utilisation par les humains (si l’utilisation des espèces d’oiseaux d’eau est documentée à l’échelle locale ou internationale) et la sensibilité à la chasse et aux maladies. Pendant la saison des pluies, les tendances des populations d’oiseaux d’eau étaient pour la plupart stables ou en augmentation. Pendant la saison sèche, les espèces plus grandes étaient plus susceptibles d’augmenter en nombre, surtout pour celles menacées par la chasse que pour les espèces limitées par les maladies. Les oiseaux aquatiques sédentaires coloniaux avaient des tendances de population plus élevées dans la PNH par rapport aux oiseaux solitaires. A l’échelle zimbabwéenne, 35% des espèces diminuaient pendant la saison des pluies et les déclins étaient les plus prononcés chez les grands oiseaux. Pendant la saison sèche, les espèces menacées par des perturbations de l’habitat étaient plus susceptibles de diminuer. Les perturbations de l’habitat et/ou l’utilisation d’oiseaux d’eau à l’échelle internationale sont davantage associées à des tendances à la baisse qu’à des caractéristiques écologiques et biologiques. Nous avons montré que la PNH, une zone protégée avec principalement un système de zones humides basses, soutient les populations d’oiseaux d’eau en croissance malgré les espèces confrontées à des tendances démographiques mondiales négatives. Keywords: habitat change, Hwange National Park, life history traits, population trends &nbsp

Ecological responses of periphyton dry mass and epilithic diatom community structure for different atrazine and temperature scenarios

Climate change–induced temperature increase may influence the ecotoxicity of agricultural herbicides such as atrazine and consequently negatively impact aquatic biota. The objective of this study was to assess the effects of increased temperature on the ecotoxicity of atrazine to diatom community structure and stream periphyton load using laboratory microcosm experiments. A natural periphyton community from the Mukwadzi River, Zimbabwe, was inoculated into nine experimental systems containing clean glass substrates for periphyton colonisation. Communities were exposed to 0 µg∙L-1 (control), 15 µg∙L-1 and 200 µg∙L-1 atrazine concentrations at 3 temperature levels of 26°C, 28°C and 30°C. Periphyton dry weight and community taxonomic composition were analysed on samples collected after 1, 2 and 3 weeks of colonisation. A linear mixed-effects model was used to analyse the main and interactive effects of atrazine and temperature on dry mass, species diversity, evenness and richness. Temperature and atrazine had significant additive effects on species diversity, richness and dry mass. As temperature increased, diatom species composition shifted from heat-sensitive species such as Achnanthidium affine to heat-tolerant species such as Achnanthidium exiguum and Epithemia adnata. Increasing temperature in aquatic environments contaminated with atrazine results in sensitive and temperature-intolerant diatoms being eliminated from periphyton communities. Climate change will exacerbate effects of atrazine on periphyton dry mass and diatom community structure

Integrating Local Ecological Knowledge for Waterbird Conservation: Insights From Kavango-Zambezi Transfrontier Conservation Area, Zimbabwe

International audienc

Stewardship of Wild and Farmed Edible Insects as Food and Feed in Sub-Saharan Africa: A Perspective

Edible insects have gained popularity as alternative food resources in the face of climate change and increasing carbon and environmental footprints associated with conventional agricultural production. Among the positive attributes that make edible insects suitable as food and feed substrates include rapid reproduction, high energy conversion efficiency, wide distribution, diversity, reduced greenhouses gases and ammonia emissions, possibility to reduce waste and high nutritional composition. In Sub-Saharan Africa, considerable scientific data exist on use of insects as food and livestock feed. However, coherent policies regarding safety, sustainability, trade and regulation of insects as food and animal feed are lacking. The benefits associated with edible insects are likely to accrue in Sub-Saharan Africa through use of a combination of approaches such as ensured sustainable utilization of edible insects in the wild, preservation of traditional conservation, harvesting and consumption practices, development of captive mass production schemes and strengthening robust value chains to incentivise indigenous participants. Collectively these approaches are referred to as the steward and use of insects as food and animal feed. This paper examines the policy frameworks that exist to support the use of edible insects as food and feed on the African continent. This investigation employed a literature review focussing on national policies in selected African countries to assess the relevance to edible insects. Using a baseline of more than 10 edible insect species consumed, 10 country cases in Sub-Saharan Africa were used to support our in-depth examination of the policy situation that may support good stewardship of edible insects as food and feed. Focus on how policies encompassing biodiversity, natural resources, culture, education, research, technology development, trade, health and nutrition and how that could be improved to support inclusivity of edible insects is discussed. We conclude by proposing a pathway that may accelerate recognition and valorisation of edible insects as important food and feed resources in Sub-Saharan Africa including improving policies to support good stewardship of these resources for sustainability

Bird tolerance to humans in open tropical ecosystems

Animal tolerance towards humans can be a key factor facilitating wildlife-human coexistence, yet traits predicting its direction and magnitude across tropical animals are poorly known. Using 10,249 observations for 842 bird species inhabiting open tropical ecosystems in Africa, South America, and Australia, we find that avian tolerance towards humans was lower (i.e., escape distance was longer) in rural rather than urban populations and in populations exposed to lower human disturbance (measured as human footprint index). In addition, larger species and species with larger clutches and enhanced flight ability are less tolerant to human approaches and escape distances increase when birds were approached during the wet season compared to the dry season and from longer starting distances. Identification of key factors affecting animal tolerance towards humans across large spatial and taxonomic scales may help us to better understand and predict the patterns of species distributions in the Anthropocene