Eggshell strength of an obligate brood parasite: a test of the puncture resistance hypothesis

Eggs of several brood parasites have thicker and stronger shells than expected for their size. The present study evaluated the puncture resistance hypothesis for the occurrence of thick-shelled eggs in common cuckoos Cuculus canorus by investigating costs of cuckoo egg ejection in four Acrocephalus warblers—the great reed warbler A. arundinaceus, reed warbler A. scirpaceus, marsh warbler A. palustris and sedge warbler A. schoenobaenus. The three latter species all suffered ejection costs, while ejection was not costly in the larger great reed warbler. The occurrence of ejection costs was negatively related to host bill size. In the marsh warbler, we compared ejection costs in naturally parasitized nests and two experimental treatments, in which broods were parasitized artificially with great reed warbler and conspecific eggs. Hosts damaged their own eggs significantly more often when ejecting the thick-shelled cuckoo eggs than when ejecting the similarly sized but thinner-shelled great reed warbler eggs, providing some support for the puncture resistance hypothesis. Ejection of conspecific eggs did not involve any costs. Furthermore, contrary to predictions derived from the laying damage hypothesis, there was no evidence that egg damage was associated with cuckoo egg laying. Hosts damaging their own eggs during ejection were more likely to subsequently desert their clutches than those that did not. The frequency of clutches smeared with the contents of the ejected egg were positively related to the hypothesized difficulty of foreign egg puncturing. Potential advantages of thicker shells in common cuckoo eggs are discussed.     

新型多级冲击采样器切割粒径的标准粒子实验分析

大气溶胶对环境污染、气候变化以及人体健康有着重要的影响,大气溶胶的采集和分析已成为当前大气环境研究领域中的一个重要课题.论述的新型多级冲击采样器能够实现大气溶胶颗粒物按空气动力学粒径的大小7级分离采集,提供大致均匀的平面样品以进行后续的物理、化学分析,同时保证各分级切割粒径的稳定性.利用振动孔溶胶发生器产生均匀、粒径大致相同、单分散相的1.5～17μm空气动力学粒径标准粒子,对新型多级冲击采样器前三级的切割粒径和收集效率进行鉴定性分析实验,结果表明,能够满足对大气溶胶颗粒物分级采集的要求.     

Methods to prepare biosorbents and magnetic sorbents for water treatment: a review

Access to drinkable water is becoming more and more challenging due to worldwide pollution and the cost of water treatments. Water and wastewater treatment by adsorption on solid materials is usually cheap and effective in removing contaminants, yet classical adsorbents are not sustainable because they are derived from fossil fuels, and they can induce secondary pollution. Therefore, biological sorbents made of modern biomass are increasingly studied as promising alternatives. Indeed, such biosorbents utilize biological waste that would otherwise pollute water systems, and they promote the circular economy. Here we review biosorbents, magnetic sorbents, and other cost-effective sorbents with emphasis on preparation methods, adsorbents types, adsorption mechanisms, and regeneration of spent adsorbents. Biosorbents are prepared from a wide range of materials, including wood, bacteria, algae, herbaceous materials, agricultural waste, and animal waste. Commonly removed contaminants comprise dyes, heavy metals, radionuclides, pharmaceuticals, and personal care products. Preparation methods include coprecipitation, thermal decomposition, microwave irradiation, chemical reduction, micro-emulsion, and arc discharge. Adsorbents can be classified into activated carbon, biochar, lignocellulosic waste, clays, zeolites, peat, and humic soils. We detail adsorption isotherms and kinetics. Regeneration methods comprise thermal and chemical regeneration and supercritical fluid desorption. We also discuss exhausted adsorbent management and disposal. We found that agro-waste biosorbents can remove up to 68–100% of dyes, while wooden, herbaceous, bacterial, and marine-based biosorbents can remove up to 55–99% of heavy metals. Animal waste-based biosorbents can remove 1–99% of heavy metals. The average removal efficiency of modified biosorbents is around 90–95%, but some treatments, such as cross-linked beads, may negatively affect their efficiency.

     

Assessing the impacts of sustainable development projects in the Amazon: the DURAMAZ experiment

Since 1992, a boom of “sustainable development projects” has been registered in the Brazilian Amazon, turning it into a kind of open-air laboratory for sustainability. But their real impacts remain unclear, especially because of inadequate evaluation tools. A new device is therefore needed to unveil the inner mechanisms of development aid despite the difficulties linked with the diversity of contexts or the heterogeneity in the relevant parameters. Those are the challenges we met when we engaged in comparing the impacts of sustainable development programs in 13 sites throughout the Brazilian Amazon in order to identify determining factors of sustainability. To achieve our objective, we conceived an indicator system based on the results of intensive fieldwork, including social, economic, environmental, and biographical issues. Our results show that the most prominent problem of sustainability—evaluation of effectiveness—has not been tackled; life conditions and environmental preservation continue to appear antagonistic. At the same time, variability appears among outwardly coherent social groups, showing that a case-to-case approach is definitely indispensable and confirming the need to go “beyond panaceas” to find resolutions. This article successively addresses three points. First, we present the starting point of our research, or how the Amazon region was turned into a laboratory for sustainability and how our research project aimed at analyzing the consequences of this trend. Second, we discuss how available indicator systems fail to respond to the need for a multidimensional evaluation at the local level and, therefore, how we constituted our own analytical tool. Third, we focus on some results that can be derived from our system, especially in terms of identifying key factors needed to achieve sustainability in the Amazon.     

Effects of heavy metal exposure on the condition and health of adult great tits (Parus major)

We examined the possible effects of heavy metal exposure on the quality and health of adult great tits (Parus major) at four study sites along a pollution gradient near a non-ferrous smelter in Belgium. Tarsus length, wing length, body mass and condition of great tits were compared with respect to study site, age (first-year and older great tits), sex and season (birds caught in winter and during breeding). Tarsus length did not differ significantly among study sites. The wing length of great tits was larger at the study site furthest from the smelter, especially for older great tits. The length of the outermost tail feathers, however, did not differ significantly among study sites. We found no signs of loss of body mass or condition towards the pollution source. The body mass and condition was lowest for female great tits at the site furthest from the smelter, especially during winter. Haematocrit values did not differ significantly among sites. Overall, we found no clear significant effects of heavy metal pollution on morphological measurements and health parameters of great tits.     

Host genotype and age have no effect on rejection of parasitic eggs

Egg rejection belongs to a widely used host tactic to prevent the costs incurred by avian brood parasitism. However, the genetic basis of this behaviour and the effect of host age on the probability of rejecting the parasitic egg remain largely unknown. Here, we used a set of 15 polymorphic microsatellite loci, including a previously detected candidate locus (Ase64), to link genotypes of female great reed warblers (Acrocephalus arundinaceus), a known rejecter, with their egg rejection responses in two host populations. We also tested whether host female age, as a measure of the experience with own eggs, plays a role in rejection of common cuckoo (Cuculus canorus) eggs. We failed to find any consistent association of egg rejection responses with host female genotypes or age. It seems that host decisions on egg rejection show high levels of phenotypic plasticity and are likely to depend on the spatiotemporal variation in the parasitism pressure. Future studies exploring the repeatability of host responses towards parasitic eggs and the role of host individual experience with parasitic eggs would greatly improve our understanding of the variations in host behaviours considering the persistence of brood parasitism in host populations with rejecter phenotypes.     

A systematic investigation of carbamate stability constants by 1H NMR

A systematic, experimental investigation into carbamate stability constants using ¹H NMR spectroscopy reveals that both steric hindrance and the acid dissociation constant of the parent amine have a significant effect on the stability of the resulting carbamates. Increasing steric hindrance was found to decrease carbamate stability, while increasing pK of the parent amine was found to increase carbamate stability. The carbamate stability constants of monoethanolamine, propylamine, isobutylamine, 2-amino-1-propanol, aminomethylpropanol and methyldiethanolamine were determined as were the carbamate protonation constants of the first four of these amines.     

Mycorrhizal fungal identity and diversity relaxes plant-plant competition

There is a great interest in ecology in understanding the role of soil microbial diversity for plant productivity and coexistence. Recent research has shown increases in species richness of mutualistic soil fungi, the arbuscular mycorrhizal fungi (AMF), to be related to increases in aboveground productivity of plant communities. However, the impact of AMF richness on plant-plant interactions has not been determined. Moreover, it is unknown whether species-rich AMF communities can act as insurance to maintain productivity in a fluctuating environment (e.g., upon changing soil conditions). We tested the impact of four different AMF taxa and of AMF diversity (no AMF, single AMF taxa, and all four together) on competitive interactions between the legume Trifolium pratense and the grass Lolium multiflorum grown under two different soil conditions of low and high sand content. We hypothesized that more diverse mutualistic interactions (e.g., when four AMF taxa are present) can ease competitive effects between plants, increase plant growth, and maintain plant productivity across different soil environments. We used quantitative PCR to verify that AMF taxa inoculated at the beginning of the experiment were still present at the end. The presence of AMF reduced the competitive inequality between the two plant species by reducing the growth suppression of the legume by the grass. High AMF richness enhanced the combined biomass production of the two plant species and the yield of the legume, particularly in the more productive soil with low sand content. In the less productive (high sand content) soil, the single most effective AMF had an equally beneficial effect on plant productivity as the mixture of four AMF. Since contributions of single AMF to plant productivity varied between both soils, higher AMF richness would be required to maintain plant productivity in heterogeneous environments. Overall this work shows that AMF diversity promotes plant productivity and that AMF diversity can act as insurance to sustain plant productivity under changing environmental conditions.     

Different growth rates between loggerhead sea turtles (<Emphasis Type="Italic">Caretta caretta</Emphasis>) of Mediterranean and Atlantic origin in the Mediterranean Sea

We estimated for the first time the growth rates of loggerhead sea turtles of Mediterranean and of Atlantic origin found in the Mediterranean Sea, combining both skeletochronological and genetic analyses. Our growth models suggested that the growth rate of loggerhead sea turtles of Mediterranean origin was faster than that of their conspecifics with an Atlantic origin exploiting the feeding grounds in the Mediterranean Sea. The age at maturity for Mediterranean origin loggerhead sea turtles, estimated using our best fitting model, was 24 years, which suggests that loggerhead sea turtles nesting in the Mediterranean are not only smaller than those nesting in the western North Atlantic but also younger.