Population size in stream-living juveniles of lake-migratory brown trout Salmo trutta L.: the importance of stream discharge and temperature

Abstract –  Based on the analysis of 17 successive year-classes, this investigation attempted to identify the factors determining year-to-year variation in population size of the stream-living juveniles of Lake Hald-dwelling brown trout Salmo trutta L. Population size appeared to be influenced chiefly by annual recruitment that in turn, was determined by stream discharge and temperature. These patterns matched those previously highlighted for a resident population located >2500 km apart and emphasised the importance of environmental (climatic) variability as a major regulating agent of population size in stream brown trout. However, distinctly shaped recruitment–discharge relationships between the two populations suggested different mechanisms in response to environmental variability and thus to persist in time.     

The effect of dietary krill supplementation on epithelium-associated bacteria in the hindgut of Atlantic salmon (Salmo salar L.): a microbial and electron microscopical study

Atlantic salmon (Salmo salar L.) were fed fishmeal protein for 46 days, and 500 g kg⁻¹ of fishmeal protein substituted with meal from Northern krill (Meganyctiphanes norvegica). No differences were observed in weight gain, length gain, feed conversion or specific growth rate between the groups that could be attributed to dietary manipulation. The adherent microbiota in the hindgut of the two rearing groups were further investigated. By substituting fishmeal with krillmeal, the total viable counts of aerobic and facultative aerobic bacteria colonizing the hindgut of Atlantic salmon increased from 8.5 × 10⁴ to 2.2 × 10⁶. Furthermore, dietary krillmeal affected the adherent hindgut microbiota. The Gram‐positive bacteria Carnobacteria piscicola, Microbacterium oxydans, Microbacterium luteolum and Staphylococcus equorum spp. linens and the Gram‐negatives Psychrobacter spp. and Psychrobacter glacincola were not isolated from hindgut of fish fed the krill diet. On the other hand, Pseudomonas fulgida, Pseudomonas reactans and Stenotrophomonas maltophila were not isolated from the control group fed fishmeal. Acinetobacter lwoffi, which is not normally found in the fish gut, was isolated from both feeding groups. Transmission electron microscopy showed bacteria‐like profiles between the hindgut microvilli in both feeding groups indicating autochthonous microbiota. When fish were fed the krill diet, hindgut enterocytes were replete with numerous irregular vacuoles. These vacuoles were not observed in fish fed the fishmeal protein.     

Understanding how built urban form influences biodiversity

This study seeks to contribute to a more complete understanding of how urban form influences biodiversity by investigating the effects of green area distribution and that of built form. We investigated breeding bird diversity in three types of housing development with approximately the same amount of tree cover. No significant differences in terms of bird communities were found between housing types in any of the survey periods. However, detached housing, especially with interspersed trees, had more neotropical insectivores and higher overall diversity of insectivores. Based on our results and theory we suggest a complementary approach to managing biodiversity in urban landscapes – instead of maximising the value and quality of individual patches efforts could go into enhancing over-all landscape quality at the neighbourhood scale by splitting up part of the green infrastructure. The relatively small differences in bird communities also suggest that different stakeholder groups may be engaged in management.     

Bird song diversity influences young people's appreciation of urban landscapes

Increased losses of green areas in cities reduce people's experience of flora and fauna. Earlier studies have shown that biodiversity has benefits for urban inhabitants but the influence of animal sounds on people's experience of green space is poorly known. A sample of young urban people (N = 227) rated their reactions – positive or negative – to three bird song combinations: House Sparrow (Passer domesticus), Willow Warbler (Phylloscopus trochilus), 7 spp. i.e. Willow Warbler, Chaffinch (Fringilla coelebs), Blue Tit (Cyanistes caeruleus), Great Tit (Parus major), European Robin (Erithacus rubecula), Common Blackbird (Turdus merula), Great Spotted Woodpecker (Dendrocopos major), three urban settings (residential areas with varying amount of greenery) and nine combinations of song and setting. Bird song was generally considered positive and singing by several species was more highly rated than singing by a single species. On average, urban settings combined with bird song were more highly appreciated than the settings alone and even more so where there was singing by several species rather than just one. We conclude that our data support the idea that bird song contributes to positive values associated with urban green space. Urban planners should consider preserving a variety of habitats in cities for hosting a diversity of birds and thereby boost conservation of songbird diversity and recreational experiences for urban people.     

Using landscape metrics to characterize towns along an urban-rural gradient

Landscape Ecology - Urban-rural gradients are useful tools when examining the influence of human disturbances on ecological, social and coupled systems, yet the most commonly used gradient...     

Correlation between α-amylase gene expression and seedling vigor in rice

Summary This report examines the relationship between seedling vigor, -amylase enzyme activity and -amylase mRNA accumulation in ten varieties of rice (Oryza sativa L.) grown at two temperatures (15°C and 30°C). A significant, positive correlation was observed between seedling vigor, -amylase enzyme activity, and the accumulation of mRNA from one rice -amylase gene (RAmy1A) at both temperature regimens. The results of this study support previous experiments which have correlated -amylase enzyme activity to seedling vigor. We have extended this correlation to the expression of one of ten genes that comprise the rice -amylase multigene family. These results suggest that the expression of -amylase gene RAmy1A is an important, and possibly rate-limiting factor in determining seedling vigor in rice.     

Glyphosate tolerance in maize (Zea mays L.). 2. Selection and characterization of a tolerant somaclone

Summary The progeny of 104 regenerated maize plants were screened for tolerance to the safe broad-spectrum herbicide glyphosate during seed germination and early growth. Seven somaclones showed varying degrees of resistance to the application of the herbicide at 1.2 mM (0.1 kg a.i. in 400 1 ha^-1 of water). Plants capable of a normal growth following treatment with 2.4 mM (0.2 kg ha^-1) glyphosate at the three leaf stage were selfed, and their progeny analyzed. A family able to tolerate the exposure to glyphosate at 2.4 mM was isolated and shown to maintain a photosynthetic rate comparable with control after the application of the herbicide.The selfed progeny of the tolerant somaclone was characterized as to the properties of two targets of glyphosate, the shikimate pathway enzymes 5-enol-pyruvyl-shikimate-3-phosphate (EPSP) synthase and 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthase. In vitro tests ruled out the possibility that the tolerance was due to altered forms of these enzymes. Families showed significant variability with regard to EPSP and DAHP synthase levels, measured at different stages during seedling growth; however, not even these traits were correlated with in vivo response to glyphosate. The possible role of other physiological processes in determining the increased tolerance to the herbicide is discussed.Abbreviations DAHP 3-deoxy-D-arabino-heptulosonate-7-phosphate - EPSP 5-enol-pyruvyl-shikimate-3-phosphate - CER carbon-exchange rate - ID₅₀ concentration causing 50% inhibition     

Well-being in Pregnant Sows: Confinement versus Group Housing with Electronic Sow Feeding

Abstract

Indicators of stress, behaviour in the pen, and lesions of the integument were used as indicators of sow well-being in a comparison of group housing with electronic sow feeding [GH] and confinement in gestation crates [C] in experiment 1, which included 2 × 4 groups of 20–25 sows. Effects of earlier experience with a gestation system on the indicators of stress was investigated in experiment 2, which included 2 × 3 groups of 20–25 sows. Reaction in a novelty test and reactivity in plasma Cortisol to the procedure of blood sampling were used as indicators of stress. Behaviour in the pen as well as lesions of the integument revealed that both gestation systems were suboptimal in some manner. However, following acclimatization for 1–2 weeks, young GH sows experienced less stress than young C sows as measured by reduced fear in the novelty test. In experiment 2 this interpretation was further supported by lower reactivity in plasma Cortisol. It was concluded that sow well-being was higher for the majority of the gestation period in young group-housed animals. Thus, in spite of the inadequate feeding method, well-being of sows may be improved in group housing systems with electronic sow feeding if the system is well functioning with low levels of aggression and vulva bites. One of the major determinants of vulva biting is suggested to be the mechanism of gate control.