Preparation and Properties of Chitosan–PVA Fibers Produced by Wet Spinning

Chitosan fibers were prepared by wet spinning in three stages. Initially, a polymer solution of chitosan and polyvinyl alcohol (PVA) was solidified in a mixture of potassium hydroxide and ethanol. The polymers were then crosslinked with sodium tripolyphosphate (TPP) or glutaraldehyde, and finally dried in methanol or acetone. The effect of these conditions was evaluated based on scanning electron microscopy images, water-holding capacity, and swelling and mechanical properties. The miscibility of the mixture was evaluated using Fourier Transform Infrared spectroscopy and differential scanning calorimetry. The results obtained showed that chitosan fibers containing 45% (v/v) PVA and crosslinked using TPP have properties similar to those of commercial sutures prepared using other biomaterials.     

Environmental risks of farmed and barren alkaline coal ash landfills in Tuzla, Bosnia and Herzegovina

The disposal of coal combustion residues (CCR) has led to a significant consumption of land in the West Balkan region. In Tuzla (Bosnia and Herzegovina) we studied previously soil-covered (farmed) and barren CCR landfills including management practises, field ageing of CCR and the transfer of trace elements into crops, wild plants and wastewaters. Soil tillage resulted in mixing of cover soil with CCR. Medicago sativa showed very low Cu:Mo ratios (1.25) which may cause hypocuprosis in ruminants. Total loads of inorganic pollutants in the CCR transport water, but not pH ( approximately 12), were below regulatory limits of most EU countries. Arsenic concentrations in CCR transport water were <2microgl(-1) whereas reductive conditions in an abandoned landfill significantly enhanced concentrations in leachates (44microgl(-1)). The opposite pattern was found for Cr likely due to large initial leaching of CrVI. Public use of landfills, including farming, should be based on a prior risk assessment due to the heterogeneity of CCR.     

Can a key boreal Calanus copepod species now complete its life-cycle in the Arctic? Evidence and implications for Arctic food-webs

The changing Arctic environment is affecting zooplankton that support its abundant wildlife. We examined how these changes are influencing a key zooplankton species, Calanus finmarchicus, principally found in the North Atlantic but expatriated to the Arctic. Close to the ice-edge in the Fram Strait, we identified areas that, since the 1980s, are increasingly favourable to C. finmarchicus. Field-sampling revealed part of the population there to be capable of amassing enough reserves to overwinter. Early developmental stages were also present in early summer, suggesting successful local recruitment. This extension to suitable C. finmarchicus habitat is most likely facilitated by the long-term retreat of the ice-edge, allowing phytoplankton to bloom earlier and for longer and through higher temperatures increasing copepod developmental rates. The increased capacity for this species to complete its life-cycle and prosper in the Fram Strait can change community structure, with large consequences to regional food-webs.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01667-y.     

Increased grooming after repeated brood care provides sanitary benefits in a clonal ant

Repeated pathogen exposure is a common threat in colonies of social insects, posing selection pressures on colony members to respond with improved disease-defense performance. We here tested whether experience gained by repeated tending of low-level fungus-exposed (Metarhizium robertsii) larvae may alter the performance of sanitary brood care in the clonal ant, Platythyrea punctata. We trained ants individually over nine consecutive trials to either sham-treated or fungus-exposed larvae. We then compared the larval grooming behavior of naive and trained ants and measured how effectively they removed infectious fungal conidiospores from the fungus-exposed larvae. We found that the ants changed the duration of larval grooming in response to both, larval treatment and their level of experience: (1) sham-treated larvae received longer grooming than the fungus-exposed larvae and (2) trained ants performed less self-grooming but longer larval grooming than naive ants, which was true for both, ants trained to fungus-exposed and also to sham-treated larvae. Ants that groomed the fungus-exposed larvae for longer periods removed a higher number of fungal conidiospores from the surface of the fungus-exposed larvae. As experienced ants performed longer larval grooming, they were more effective in fungal removal, thus making them better caretakers under pathogen attack of the colony. By studying this clonal ant, we can thus conclude that even in the absence of genetic variation between colony members, differences in experience levels of brood care may affect performance of sanitary brood care in social insects.     

Mandated to fail? Humanitarian agencies and the protection of Palestinian children

This paper considers the efforts of United Nations and international agencies to address the threats to Palestinian children arising from Israeli occupation. It contains an account of the reasons why agencies have failed, over many years, to prevent systematic violations by the Israeli authorities and settlers. The discussion is organised around two inter‐related domains: institutional and political. The paper argues that, in the occupied Palestinian territory (oPt), limitations to the ways in which child protection has been conceptualised and pursued in practice are abundantly evident. Nevertheless, political pressure by Western donor governments serves to constrain an approach to child protection that is more preventative in nature, that addresses more explicitly Israeli violations of international law, and that reflects the experience and aspirations of Palestinian children themselves. Ultimately, therefore, the failure to protect Palestinian children must be seen not only as a result of humanitarian miscalculation but also as a consequence of political strategy.     

Assessment of regional capabilities for agricultural coexistence with genetically modified maize

Background

The coexistence of agricultural production with and without the use of genetically modified (GV) crops is supposed to be made possible in Germany by regulations, which include minimal distances of GV-fields to potentially susceptible crop fields and habitats. To explore the impact of these regulations on region specific coexistence potentials, we broadened the applicability of an existing method for the simulation of the spatial distribution of arable fields cropped with conventional, organic and GV-maize. We used simulations which combine a variety of minimum distances of GV-maize fields to assess regional specific options and limitations for coexistence.

Results

An existing method was extended to be applicable for different spatial scales, from the large (e.g. Federal State) to small (e.g. municipality). Input data consisted of cropping statistics, geometry of arable fields and protected areas. Scenarios of cropping situations included various minimal distances between GV-maize fields and protected areas and various proportions of maize within the areas. The results of the simulations represent possible distribution patterns of non-GV and GV-maize fields as well as the size of the remaining area in which additional GV-maize can be grown without violating the minimal distance rules. As suspected, increasing proportions of GV-maize and increasing minimal distances lower the areas suitable for additional GV-maize. However, the relation between the area of GV-maize grown and those suitable for GV-maize cultivation varied between the scenarios. Moreover, the variability between the municipalities was even more evident, due to varying landscape structure (proportion of maize, the ratio total arable land to maize, proportion of protected areas). Areas with high proportions of GV-maize, of protected areas and of maize could be problematical for coexistence. We discuss these parameters with regard to other coexistence studies.

Conclusions

Our method is suitable to simulate the spatial distribution of fields cultivated with GV-crops and non-GV-crops on various scales. Simulations on the scale of a Federal State reveals those areas, in which coexistence could be problematical. Simulations on a county scale, however, allow more insight into options and restrictions for coexistence in relation to landscape structural characteristics, which also can be transferred to larger scales. On the scale of municipalities simulations can help to analyse the limits of coexistence in areas of high conflict potential, moreover this level is more realistic with regard to practical agricultural decisions on the farm level.

Zusammenfassung

Hintergrund

Die Koexistenz verschiedener landwirtschaftlicher Produktionsformen ?C mit und ohne Anbau von gentechnisch ver?nderten Pflanzen (GVO) ?C soll durch gesetzlich fixierte Regeln erm?glicht werden, die unter anderem die Mindestabst?nde von GVO-Anbaufl?chen zu potenziell empfindlichen anderen Ackerfl?chen und Biotopen festlegen. Hier wurde eine Methode weiterentwickelt zur Simulation der r?umlichen Verteilung der Anbaufl?chen von konventionellem, ?kologischem und GV-Mais um regionsspezifische Koexistenzpotenziale von gentechnisch ver?ndertem Mais, sowie potenzielle Konfliktgebiete zu identifizieren.

Ergebnisse

Eine für Brandenburg entwickelte GIS-Simulationsmethode wurde durch die Verwendung fl?chendeckend vorhandener Daten so erweitert, dass sie bundesweit übertragbar ist und auf unterschiedlichen r?umlichen Skalenebenen angewandt werden kann, von gro?r?umig (Bundesland) bis lokal (Gemeinde). Als Eingangsdaten wurden Anbaustatistiken sowie Geometrien der Ackerfl?chen und von FFH- und Naturschutzgebieten verwendet. In den Szenarien wurden Abstandsregelungen zwischen Maisanbaufl?chen und zu Schutzgebieten und der GV-Maisanteil variiert. Die Ergebnisse der Simulation sind m?gliche r?umliche Verteilungen von Nicht-GV-Mais und GV-Mais sowie die potenziell für den Anbau von GV-Mais zur Verfügung stehende Fl?che. Mit zunehmendem GV-Maisanteil und Mindestabst?nden zu Schutzgebieten wird die für den GV-Mais zur Verfügung stehende Fl?che st?rker ausgesch?pft. Der Anteil des GV-Mais an der potenziell für den Anbau von GV-Mais zur Verfügung stehenden Fl?che variierte zwischen den Szenarien, und noch st?rker jedoch regional zwischen den Landkreisen, verursacht durch deren verschiedene agrar- und landschaftsstrukturelle Ausstattung (Maisanbauanteil, Verh?ltnis Ackerlandsanteil/Maisanbauanteil, Schutzgebietsanteil). Ein r?umliches Konfliktpotenzial bei der Umsetzung der Koexistenz ist in Gebieten hohen Nutzungsdrucks zu erwarten, d.h. in denen sowohl der Maisanbauanteil an der Ackerfl?che und der Anbauanteil von GV-Mais, als auch der Schutzgebietsanteil hoch sind. Diese Faktoren werden diskutiert in Bezug zu Ergebnissen weiterer Koexistenzstudien.

Schlussfolgerungen

Die vorgestellte Methode ist geeignet, die r?umliche Verteilung des Anbaus von Nicht-GV-Mais und GV-Mais auf unterschiedlichen Skalenebenen zu simulieren: Die Ebene eines Bundeslandes liefert Hinweise auf Gebiete, in denen die Koexistenz problematisch sein k?nnte und kann als Grundlage weiterer Berechnungen, wie zum Beispiel der Modellierung von Genflüssen auf Landesebene dienen. Die Simulation auf der Ebene eines Landkreises oder einer Gemeinde erm?glicht genauere Aussagen über die M?glichkeiten und Grenzen der Koexistenz. Auf der Ebene der Landkreise k?nnen z.B. unterschiedliche agrar- und landschaftsstrukturelle Situationen untersucht und für eine nachfolgende Regionalisierung angewandt werden. Die Ebene der Gemeinden erlaubt die Analyse der Grenzen der Koexistenz für Gebiete mit h?herem r?umlichen Konfliktpotenzial. Simulationen auf lokaler Ebene erscheinen darüber hinaus n?her an den Entscheidungsm?glichkeiten der landwirtschaftlichen Praxis.     

What enables coexistence in plant communities? Weak versus strong species traits and the role of local processes

Explaining the coexistence of species that basically depend on the same resources has been a brainteaser for generations of ecologists. Different mechanisms have been proposed to facilitate coexistence in plant communities, where space is an important resource. Using a stochastic cellular automaton simulation model we analyze - separately and in combination - the influence of different species traits and processes which alter local competition on the coexistence of plant species over a fixed time horizon. We show that different species traits operate on different time scales in competition. We therefore suggest the concept of weak versus strong traits according to short- or long-term exclusion of species differing in these traits. As a consequence, highly non-linear trade-offs between weak and strong traits can result in communities. Furthermore, we found that trade-offs based on physiological species traits such as plant lifetime, dispersal range and plant growth, did not support broad and long-term coexistence—further processes such as density-dependent mortality and light-dependent colonization were necessary. This suggests that coexistence in plant communities requires (stabilizing) local processes to support the (equalizing) trade-offs in species traits.     

Variance in the male reproductive success of western gorillas: acquiring females is just the beginning

Variance in male reproductive success is expected to be high in sexually dimorphic mammals, even when it is modulated by the costs and benefits of group living. Here, we investigate the variance in reproductive success of male western gorillas (Gorilla gorilla), a highly dimorphic primate with long-term male–female associations, using 12.5 years of data collected at Mbeli Bai in northern Congo. Access to mates and offspring survival were both major sources of variance in male reproductive success. Males with larger harems had lower offspring mortality with no apparent reduction in female fertility or observed tenure length, so the size of harems did not seem to be limited by female feeding competition or by the risk of takeovers and infanticide by outsider males. The lower mortality in larger harems may reflect improved vigilance against predators, and females may cluster around males that enhance offspring survival. Thus, this study illustrates how a detailed analysis of the components of male reproductive success can shed light on the interrelated social and ecological aspects that affect it.