Mesoscale spatial variability of ichthyoplankton in the Southwest Atlantic during the autumn–winter period

To gain a better understanding of the mechanisms underlying spatial heterogeneity in ichthyoplankton communities in the SW Atlantic, we examined for the first time the latitudinal and continental shelf–slope gradients in ichthyoplankton structure and oceanographic features in the Campos Basin during the relaxation phase of coastal upwellings (late autumn to early winter). This region, located on SE Brazil's continental margin, is the most productive offshore oil basin in the country and has ecological relevance owing to the existence of areas that experiences mesoscale (tens to hundreds of kilometers) processes (eddies, filaments, and upwelling) caused by the interaction of continental shelf and slope circulation with deep water masses. The present study collected a total of 3892 fish eggs and 10,030 larvae from 36 sampling stations, averaging 22 eggs per 100 m³ and 56 larvae per 100 m³. A total of 250 taxa (5 for fish eggs and 248 for larvae) were identified, encompassing 80 families and 145 genera. Species distribution exhibited a considerable degree of spatial variability, which was related mostly to hydrological characteristics. In general, greater densities were associated with higher nutrient concentrations areas. Through distance-based Redundancy Analysis, some discriminating species were found to associate with certain areas of the continental shelf characterized by colder temperatures. The ichthyoplankton distribution patterns suggested a potential influence from mesoscale oceanographic fronts, specifically those that induce upwelling of the cold and nutrient-rich South Atlantic Central Water. Nonetheless, the methodologies used in this study faced challenges in distinctly identifying these processes.     

薄木饰面杨木集成板材的研制

以人工林杨木为原料,开发生产饰面集成板材,可以大大提高其产品的附加值。最终产品检测结果表明,产品达到了日本(JAS)标准要求。这将为人工林杨木的进一步开发利用提供一条新的途径。     

Arbuscular mycorrhizal fungal hyphae enhance transport of the allelochemical juglone in the field

Allelopathy is a biological phenomenon where plants have harmful effects on growth of surrounding plants through the production of chemical substances. Here we focus on allelochemical processes which operate belowground, can influence plant interactions and therefore potentially affect plant community structure. Soil hyphae of arbuscular mycorrhizal fungi (AMF) may enhance transport processes in the soil matrix by providing direct connections between plants facilitating infochemical exchange.In a two-component field study we showed that soil hyphae likely play a crucial role in movement of allelochemicals in natural soils and greatly expand bioactive zones by providing effective transport pathways for chemical compounds. First, we tested the effects of Juglans regia leaf litter extract addition in intact or disrupted hyphal networks and simultaneously determined growth reducing effects on sensitive Lycopersicon lycopersicum plants. Second, we analyzed the effect of juglone on tomato by directly adding leaf litter. In both approaches we found an increase of juglone transport if a hyphal network was present, resulting in reduced growth of target plants.Our results, together with previous work, add to the body of evidence for hyphae of soil fungi playing an important role in the transfer of allelochemicals and effectively acting as transport highways in the field. We suggest that hyphal connections, mostly formed by AMF, increase the effectiveness of allelochemicals in natural systems and can play a crucial role in chemical interaction processes in the soil.     

Agroecological principles for the redesign of integrated crop–livestock systems

Combining crops and livestock within integrated crop–livestock systems (ICLS) represents an opportunity to improve the sustainability of farming systems. The objective of this paper is to analyse how agroecological principles can help farmers to redesign and improve the resilience, self-sufficiency, productivity, and efficiency of ICLS. Relying on case studies from Brazil and France, we examine how the transformation of two conventional, specialised systems into more integrated-production systems illustrates the different dynamics towards agroecological ICLS. The French case study, based on self-sufficient farming systems belonging to a sustainable agriculture network, highlights that cost-cutting management led to a win–win strategy comprising good economic and environmental performances. The farms decreased their dependence on external inputs and had only a limited loss of production. The past trajectories of the farms illustrate how increasing the interactions between subsystems improved the self-sufficiency and efficiency of the farms. The Brazilian case study compares slash-and-burn agriculture in the Amazonian region with the recovery of degraded grazing area by ICLS. A small increase in chemical inputs linked to a diversification of productions led to a large increase in production and a large decrease in environmental impacts (deforestation). The Brazilian case study also illustrates how the diversification of production increased the resilience of the system to market shocks. Reconstructing the links among soil, crops, and animals following agroecological principles could improve the different performances of ICLS. New agroecological ICLS, benefiting from diversified productions and increased interactions between subsystems, are likely to offset the trade-off between agricultural production and environmental impacts observed in current ICLS.     

Egg quality,fatty-acid composition and gastrointestinal morphology of layer hens fed whole flaxseed with enzyme supplementation

1. Flaxseed is a rich source of α-linolenic acid (ALA, 18:3 n–3). Feeding flaxseed to hens can increase n–3 fatty acids (FA) in eggs. However, non-starch polysaccharides (NSP) in flaxseed decrease nutrient digestibility and can have a negative impact on egg n–3 FA incorporation. Addition of carbohydrase enzymes to flaxseed-based diets can decrease the anti-nutritive effects of NSP.

2. An experiment was conducted to investigate the effect of enzyme supplementation on FA composition and gastrointestinal morphology in hens fed flaxseed. A total of seventy-two, 51-week old brown layer hens were randomly assigned to one of the four dietary treatments (six replicates with three hens per replicate): corn-soybean based diet containing 0% flax (Control), 10% flax (Flax), Flax+0.05% enzyme (Flax+E1), or Flax+0.1% enzyme (Flax+E2) in a 120-day feeding trial.

3. Egg weight was highest in hens fed Flax+E1 (P < 0.05). Yolk weight was higher in Flax+E1 compared with the control and Flax+E2 and was not different from Flax treatment. ALA and total n–3 FA was highest in eggs from Flax+E2 hens (P < 0.05). Addition of enzyme has no effect of on docosahexaenoic acid (DHA), total long chain (>20-C FA), or n–6:n–3 FA ratio in eggs from hens fed flaxseed-based diets (P > 0.05). Over nine-fold increase in hepatic ALA was observed in the liver of hens fed flaxseed-based diets when compared with the control diet (P < 0.0001). No effect of enzyme supplementation was observed on liver ALA, DHA or long chain n–3 FA (P > 0.05). Enzyme supplementation reduced arachidonic acid, total n–6 and LC n–6 FA in liver tissue from hens fed flaxseed-based diets (P > 0.05).

4. Villi height and width was higher in the duodenum and jejunum of hens fed flax-based diets compared to the control (P < 0.05). Enzyme supplementation led to an increase in villi width in jejunum (P < 0.05) in hens fed Flax+E2 (P < 0.05). No effect of diet was observed in the crypt depth and villi height:crypt depth ratio in the jejunum (P > 0.05).

5. It was concluded that enzyme supplementation enhanced total n–3 FA deposition in eggs and liver and influence gastrointestinal morphology in layer hens fed flaxseed.     

Emotions as Drivers of Wildlife Stewardship Behavior: Examining Citizen Science Nest Monitors’ Responses to Invasive House Sparrows

Growing evidence suggests wildlife stewardship behaviors might be affected by emotional dispositions toward particular species. To test this hypothesis, we studied wildlife management choices made by backyard citizen scientists (N = 448) involved in two North American bird nest monitoring projects. Our exploratory study characterized nest monitors’ efforts to manage invasive house sparrows, which compete with native songbirds for nesting sites, and examined the relative influence of cognitive and affective factors on management orientations. Results revealed that nearly all respondents engaged in some form of house sparrow management, and most respondents favored a combination of lethal and non-lethal management approaches. Core affect, emotional dispositions, and experiential variables were the primary drivers of citizen scientists’ management decisions, with anger toward house sparrows and firsthand contact with house sparrow damage as the strongest positive correlates of lethal management orientations. Findings highlight the potentially powerful influence of affect and emotions on wildlife stewardship actions.     

Effectiveness of electro-fencing for restricting the ranging behaviour of wildlife: a case study in the degazetted parts of Akagera National Park

Several national parks on the African continent have been fenced to mitigate human–wildlife conflict, but the effectiveness of different fencing strategies seems to vary between regions. Here, we assessed the effectiveness of electro-fencing for restricting movement patterns of several wild ungulates in Akagera National Park (NP), Rwanda. Following the turmoil of the Rwandan genocide and civil war (1991–1995), large numbers of returning war refugees brought about an increasing pressure on land use, after which considerable parts of the western Akagera NP and adjacent Mutara Game Reserve were degazetted, followed by the construction of an electric fence in 2013 and a helicopter-based game-drive of ungulates into the modern park. We conducted distance sampling of wildlife and domestic livestock in the Uruhita plain – now no longer part of Akagera NP but bordering the modern Akagera NP to the west – for extended periods of time (2010–2015) before and after fencing. For abundant species population densities could be calculated, whereas for other species encounter frequencies are reported. We report on continuously high cattle densities, and increasing encounter frequencies of sheep/goats in the Uruhita plain. We found decreasing densities of zebra (Equus quagga) and decreasing encounter frequencies of waterbuck (Kobus ellipsiprymnus), stagnant encounter frequencies in the case of topi (Damaliscus lunatus jimela) and stagnant densities of impala (Aepyceros melampus). The latter species can jump fences, and we argue that competitive release and reduced predation may be the prime factors leading impala to (temporarily) exploit grasslands outside the modern national park.     

Comparison of acid–base and electrolyte changes following administration of 6% hydroxyethyl starch 130/0.42 in a saline and a polyionic solution in anaesthetized dogs

Objective

To evaluate the effects of a 6% hydroxyethyl starch (130/0.42) in either a buffered, electrolyte-balanced (HES-BAL) or saline (HES-SAL) carrier solution on electrolyte concentrations and acid–base parameters in healthy anaesthetized dogs.

Influence of maize–wheat rotation systems on Fusarium head blight infection and deoxynivalenol content in wheat under low versus high disease pressure

Fusarium head blight (FHB) is one of the most destructive fungal diseases of small grain cereals resulting in a reduced grain yield and quality. FHB is the result of a complex interaction between weather conditions and agricultural practices including crop rotation, tillage, fungicide application and host resistance. This study deals with the results of field experiments conducted during the growing seasons 2009–2010 until 2011–2012 at Bottelare (Belgium). The experiments were set up to evaluate the influence of maize–wheat rotation on the visual symptoms of FHB and deoxynivalenol (DON) content in winter wheat. Using a randomised complete block design with four replications, we studied the impact of (a) maize variety as previous crop, (b) maize harvest method (grain or silage maize), (c) tillage method and (d) the influence of the wheat variety resistance on the FHB incidence and DON content. The experimental results showed that the susceptibility of the maize varieties for Fusarium and maize harvest method had only a minor effect on the FHB incidence and DON content of the wheat crop during the subsequent growing season. The tillage method and wheat variety resistance were more important; both factors had a significant influence on the FHB incidence and DON content. Furthermore, the quantitative effect of these factors depended on the disease pressure. The DON content reduction obtained by ploughing and by sowing moderately resistant wheat varieties was higher in case the weather conditions favoured FHB development. Furthermore, it was shown that repeated maize–wheat rotation in combination with favourable weather conditions for FHB could result in an accumulation of inoculum, which, for instance, led to DON contents up to 9.90 mg/kg in August 2012.     

Residual effects of nitrogen sources,sulfur and boron levels on mungbean (Vigna radiata) in a sunflower (Helianthus annuus)–mungbean system

Field experiments were conducted during spring–rainy (kharif) seasons of 2005 and 2006 on a sunflower–mungbean cropping system at the research farm of the Division of Agronomy, Indian Agricultural Research Institute (IARI), New Delhi, India. The objectives of this study were to investigate the residual effect of nitrogen sources, sulfur and boron levels applied to sunflower on productivity, nutrient concentrations and their uptake by the succeeding mungbean crop in a sunflower–mungbean cropping system. The experiment with 19 treatments was laid out in factorial randomized block design for both sunflower and mungbean. The residual effects of nutrients applied to sunflower were significant on the succeeding mungbean crop in terms of biometric parameters, yield attributing characters, seed yield and soil nutrient status. The highest mungbean seed yield (961.2 kg ha^?1) was produced with 50 kg ha^?1 sulfur application to the preceding sunflower crop, which was significantly (p < 0.05) higher than with 0 and 25 kg sulfur ha^?1. The concentrations and uptake of nitrogen, sulfur and boron were also greater in the succeeding mungbean crop due to the residual effects of nutrients applied to the preceding sunflower crop. The soil nutrient status before and after mungbean indicated that the available nitrogen and sulfur were higher due to application to the preceding crop, while available boron after mungbean was even higher than after sunflower due to its slow release and static nature in the soil.