Cladocerans under conditions of small river damming by man and beavers

In beaver ponds, the species diversity, abundance, biomass, and production of cladocerans and the amount of food consumed by them have increased and the composition of dominant species has changed as compared to those in the stretches of small rivers with running water or dammed by man. The stimulating effect of water from a beaver pond has been confirmed in laboratory experiments. The average number of juvenile Ceriodaphnia affinis produced by one female was considerably greater in this water than in the water from flowing and dammed (by man) river stretches.     

Specific features of phenetic structure of the terrestrial snail <Emphasis Type="Italic">Cepaea vindobonensis</Emphasis> (Pulmonata; Helicidae) in urbanized and natural populations

The phenetic structure of natural and urbanized populations of the terrestrial snail Cepaea vindobonensis has been studied with respect to polymorphism in the shell-band color and pattern. It is noted that C. vindobonensis snails populating different artificial habitats in the city of Nikolaev and its suburbs are characterized by a higher level of both intra-and interpopulation diversity with respect to the type of this polymorphism. In addition, urban populations show a very wide range of variation in the frequencies of particular morphs or their groups. Conversely, natural populations are characterized by a more uniform frequency structure with respect to polymorphism of the shell banding pattern.     

Low abundance of long-tongued pollinators leads to pollen limitation in four specialized hawkmoth-pollinated plants in the Atlantic Rain forest,Brazil

Long-tubed hawkmoth-pollinated species present some of the most remarkable examples of floral specialization depending exclusively on long-tongued hawkmoths for sexual reproduction. Nonetheless, long-tongued hawkmoths do not rely exclusively on specialized plants as nectar sources, which may limit sexual reproduction through pollen limitation. However, very few studies have quantified the level of pollen limitation in plants with highly specialized floral traits in tropical regions. In this context, we studied four sympatric hawkmoth-pollinated species in a highland Atlantic Rain forest and assessed pollen limitation and their dependence on pollinators by analyzing the floral biology, breeding system, pollination mechanisms, and abundance of long-tongued pollinators. We showed that the four species are self-compatible, but are completely dependent on long-tongued hawkmoths to set fruits, and that flower visitation was infrequent in all plant species. Pollen limitation indices ranged from 0.53 to 0.96 showing that fruit set is highly limited by pollen receipt. Long-tongued moths are much less abundant and comprise only one sixth of the hawkmoth fauna. Pollen analyses of 578 sampled moths revealed that hawkmoths visited ca. 80 plant species in the community, but only two of the four species studied. Visited plants included a long-tubed hawkmoth-pollinated species endemic to the lowland forest ca. 15–20 km away from the study site. Specialization index (H ₂ ′?=?0.20) showed that community-level interactions between hawkmoths and plants are generalized. We suggest that sexual reproduction of these highly specialized hawkmoth-pollinated species is impaired by competition among plants for pollinators, in conjunction with the low abundance and diversity of long-tongued pollinators.     

Alteration of dominant cyanobacteria in different bloom periods caused by abiotic factors and species interactions

Freshwater cyanobacterial blooms have drawn public attention because they threaten the safety of water resources and human health worldwide. Heavy cyanobacterial blooms outbreak in Lake Taihu in summer annually and vanish in other months. To find out the factors impacting the cyanobacterial blooms, the present study measured the physicochemical parameters of water and investigated the composition of microbial community using the 16S rRNA gene and internal transcribed spacer amplicon sequencing in the months with or without bloom. The most interesting finding is that two major cyanobacteria, Planktothrix and Microcystis, dramatically alternated during a cyanobacterial bloom in 2016, which is less mentioned in previous studies. When the temperature of the water began increasing in July, Planktothrix appeared first and showed as a superior competitor for M. aeruginosa in NO₃^?-rich conditions. Microcystis became the dominant genus when the water temperature increased further in August. Laboratory experiments confirmed the influence of temperature and the total dissolved nitrogen (TDN) form on the growth of Planktothrix and Microcystis in a co-culture system. Besides, species interactions between cyanobacteria and non-cyanobacterial microorganisms, especially the prokaryotes, also played a key role in the alteration of Planktothrix and Microcystis. The present study exhibited the alteration of two dominant cyanobacteria in the different bloom periods caused by the temperature, TDN forms as well as the species interactions. These results helped the better understanding of cyanobacterial blooms and the factors which contribute to them.     

Changes in the Distribution of Broadleaf Tree Species in the Central Part of the Southern Urals since the 1970s

Russian Journal of Ecology - Changes in the distribution of broadleaf tree species—Tilia cordata Mill., Quercus robur L., Acer platanoides L., and Ulmus glabra Huds.—in the central part...     

Dynamics of Tree and Shrub Vegetation in the Eastern Sayan Mountain Tundra

Russian Journal of Ecology - Climate change entails shifts in the ranges of woody plants along both latitudinal and altitudinal gradients in the boreal forest biome. In this study,...     

Backwater Confluences of the Ohio River: Organic and Inorganic Fingerprints Explain Sediment Dynamics in Wetlands and Marinas

In the Ohio River (OR), backwater confluence sedimentation dynamics are understudied, however, these river features are expected to be influential on the system’s ecological and economic function when integrated along the river’s length. In the following paper, we test the efficacy of organic and inorganic tracers for sediment fingerprinting in backwater confluences; we use fingerprinting results to evidence sediment dynamics controlling deposition patterns in confluences used for wetland and marina functions; and we quantify the spatial extent of tributary drainages with wetland and marina features in OR confluences. Both organic and inorganic tracers statistically differentiate sediment from stream and river end‐members. Carbon and nitrogen stable isotopes produce greater uncertainty in fingerprinting results than inorganic elemental tracers. Uncertainty analysis of the nonconservative tracer term in the organic matter fingerprinting application estimates an apparent enrichment of the carbon stable isotopes during instream residence, and the nonconservativeness is quantified with a statistical approach unique to the fingerprinting literature. Wetland and marina features in OR confluences impact 42% and 11% of tributary drainage areas, respectively. Sediment dynamics show wetland and marina confluences experience deposition from river backwaters with longitudinally linear and nonlinear patterns, respectively, from sediment sources.     

Practitioner Insights into Weed Management on California’s Rangelands and Natural Areas

Working rangelands and natural areas span diverse ecosystems and face both ecological and economic threats from weed invasion. Restoration practitioners and land managers hold a voluminous cache of place-based weed management experience and knowledge that has largely been untapped by the research community. We surveyed 260 California rangeland managers and restoration practitioners to investigate invasive and weedy species of concern, land management goals, perceived effectiveness of existing practices (i.e., prescribed fire, grazing, herbicide use, and seeding), and barriers to practice implementation. Respondents identified 196 problematic plants, with yellow starthistle (Centaurea solstitialis L.) and medusahead (Elymus caput-medusae L.) most commonly listed. Reported adoption and effectiveness of weed management practices varied regionally, but the most highly rated practice in general was herbicide use; however, respondents identified considerable challenges including nontarget effects, cost, and public perception. Livestock forage production was the most commonly reported management goals (64% of respondents), and 25% of respondents were interested in additional information on using grazing to manage invasive and weedy species; however, 19% of respondents who had used grazing for weed management did not perceive it to be an effective tool. Across management practices, we also found common barriers to implementation, including operational barriers (e.g., permitting, water availability), potential adverse impacts, actual effectiveness, and public perception. Land manager and practitioner identified commonalities of primary weeds, management goals, perceived practice effectiveness, and implementation barriers across diverse bioregions highlight major needs that could be immediately addressed through management–science partnerships across the state’s expansive rangelands and natural areas.     

Catalytic oxidation of CO over Pt/Fe3O4 catalysts: Tuning O2 activation and CO adsorption

• Strong metal-support interaction exists on Pt/Fe₃O₄ catalysts. • Pt metal particles facilitate the formation of oxygen vacancies on Fe₃O₄. • Fe₃O₄ supports enhance the strength of CO adsorption on Pt metal particles. The self-inhibition behavior due to CO poisoning on Pt metal particles strongly impairs the performance of CO oxidation. It is an effective method to use reducible metal oxides for supporting Pt metal particles to avoid self-inhibition and to improve catalytic performance. In this work, we used in situ reductions of chloroplatinic acid on commercial Fe₃O₄ powder to prepare heterogeneous-structured Pt/Fe₃O₄ catalysts in the solution of ethylene glycol. The heterogeneous Pt/Fe₃O₄ catalysts achieved a better catalytic performance of CO oxidation compared with the Fe₃O₄ powder. The temperatures of 50% and 90% CO conversion were achieved above 260°C and 290°C at Pt/Fe₃O₄, respectively. However, they are accomplished on Fe₃O₄ at temperatures higher than 310°C. XRD, XPS, and H₂-TPR results confirmed that the metallic Pt atoms have a strong synergistic interaction with the Fe₃O₄ supports. TGA results and transient DRIFTS results proved that the Pt metal particles facilitate the release of lattice oxygen and the formation of oxygen vacancies on Fe₃O₄. The combined results of O₂-TPD and DRIFTS indicated that the activation step of oxygen molecules at surface oxygen vacancies could potentially be the rate-determining step of the catalytic CO oxidation at Pt/Fe₃O₄ catalysts. The reaction pathway involves a Pt-assisted Mars-van Krevelen (MvK) mechanism.     

Muskox status,recent variation,and uncertain future

Ambio - Muskoxen (Ovibos moschatus) are an integral component of Arctic biodiversity. Given low genetic diversity, their ability to respond to future and rapid Arctic change is unknown, although...