Directionality of pre‐ and post‐breeding migrations of a marbled newt population (Triturus marmoratus): implications for buffer zone management

• 1. The marbled newt, Triturus marmoratus, is a vulnerable urodele species (listed on Annex IV of the European Habitats Directive). However, biological information about their migration and the terrestrial habitats they use is relatively scarce. In order to investigate the influence of the surrounding habitats of a local pond on the directions of pre‐ and post‐breeding migrations, adult newts were monitored over two successive years (from February 2000 to June 2001) at a permanent pond in south‐western France using a drift fence and pitfall traps.
• 2. In both sexes the entry and exit directions were non‐randomly distributed. Furthermore, males and females generally followed similar directions facing an oak forest and avoiding barren areas. However, the directions followed by postbreeding migrants leaving the pond differed from those they followed when coming to the pond.
• 3. The distribution of captures around the pond was related to environmental factors, and more precisely to vegetation within the immediate surroundings of the pond.
• 4. The environmental conditions occurring at the end of the spring postbreeding migration differed greatly from those occurring during the winter prebreeding migration. Thus, vegetation does not exert similar attraction during the two migration periods.
• 5. This raises the importance of microhabitat diversity in the vicinity of the breeding pond, which provides a wide range of suitable shelters in different migration periods. Conservation planning must take into account the ecological requirements of this endangered species in managing buffer zones around the breeding sites.

Copyright © 2005 John Wiley & Sons, Ltd.     

Soil reclamation amendments affect long term growth of jack pine following oil sands mining

A retrospective study of reclamation soil properties and associated tree growth was conducted on a former tailings pond site containing a 21-year old jack pine stand. The purpose of the study was to explore possible causes of observed variations in mean tree heights in various portions of the stand. An expected link to total depth of the fine textured glaciolacustrine reclamation capping material was not found. Instead, a strong relationship was found between tree height and organic matter (OM) content (by % dry weight), where OM is in the form of predominantly mesic peat mixed with the capping material at the time of placement. Possible OM-related causes of the height growth effect could include (a) contributions to water holding capacity of the soil and (b) contributions to soil nutrition. Contributions to water holding capacity could not be evaluated in this study, but the lack of correlations to total capping depth suggests that moisture may be of lesser importance as a growth limiting factor on this site. Nitrogen supply was identified as the most likely nutritional deficiency. For current soil OM content, substantial increases in tree heights were measured with OM increases to approximately 8 %, followed by marginal increases in tree height with OM greater than 8 %. This study offers a relatively inexpensive methodology through which oil sands operators can test for similar relationships over a broad range of site and stand conditions, and evaluate the benefits of varying their allocation of OM resources to achieve optimum tree growth benefits at the landscape scale.     

Fixation de la ribonuclease A sur des elements du sol

The immobilization of ribonuclease A on soils constituents (montmorillonite, humic acid, montmorillonite-humic acid complex) is the same with or without sodium cyanoborohydride. The enzyme is not liberated by washing with dilute sodium chloride and this observation is in favor of a great adsorption energy. It is suggested that the different supports inhibited completely ribonuclease activity by combining with the enzyme.     

Detailed genetic analysis of feeding behaviour in Romane lambs and links with residual feed intake

Breeding strategies based on feed efficiency are now implemented in most animal species using residual feed intake (RFI) criteria. Although relevant, the correlated responses of feeding behaviour traits resulting from such selection on RFI are poorly documented. We report the estimated feeding behaviour at three time levels (visit, meal and day) and genetic parameters between the feeding behaviour traits and their links with RFI and its components. Feed intake, feeding duration at three time levels (per visit, meal and day), feeding rate, number of visits and time‐between‐visits were estimated for 951 Romane lambs fed via automatic concentrate feeders. Heritability estimates of feeding behaviour traits ranged from 0.19 to 0.54 with higher estimates for the day level than the visit level. Daily feed intake was not genetically linked to feed intake at the visit level, whereas feeding duration between visit and day levels was moderately correlated (R_g = +0.41 ± 0.12). RFI was not significantly correlated with feeding rate, but was positively linked to feed intake and feeding duration at the day level (+0.73 ± 0.09 and +0.41 ± 0.13, respectively) and negatively at the visit level (?0.33 ± 0.14 and ?0.22 ± 0.17, respectively). Selecting animals with lower RFI values might modify their feeding behaviour by increasing feed intake and feeding duration at the visit level but decrease the number of visits per day (+0.51 ± 0.14).     

Evaluation of five diagnostic methods for the detection and quantification of Myxobolus cerebralis.

Diagnostic methods were used to identify and quantify Myxobolus cerebralis, a myxozoan parasite of salmonid fish. In this study, 7-week-old, pathogen-free rainbow trout (Oncorhynchus mykiss) were experimentally infected with M. cerebralis and at 7 months postinfection were evaluated with 5 diagnostic assays: 1) pepsin-trypsin digest (PTD) to detect and enumerate spores found in cranial cartilage, 2) 2 different histopathology grading scales that provide a numerical score for severity of microscopic lesions in the head, 3) a conventional single-round polymerase chain reaction (PCR), 4) a nested PCR assay, and 5) a newly developed quantitative real-time TaqMan PCR. There were no significant differences (P > 0.05) among the 5 diagnostic assays in distinguishing between experimentally infected and uninfected control fish. The 2 histopathology grading scales were highly correlated (P < 0.001) for assessment of microscopic lesion severity. Quantification of parasite levels in cranial tissues using PTD and real-time TaqMan PCR was significantly correlated r = 0.540 (P < 0.001). Lastly, 104 copies of the 18S rDNA gene are present in the M. cerebralis genome, a feature that makes this gene an excellent target for PCR-based diagnostic assays. Also, 2 copies of the insulin growth factor-I gene are found in the rainbow trout genome, whose detection can serve both as an internal quality control for amplifiable DNA and as a basis to quantify pathogen genome equivalents present in quantitative PCR assays.     

Effect of triple superphosphate and biowaste compost on mycorrhizal colonization and enzymatic P mobilization under maize in a long‐term field experiment

Phosphorus (P) fertilizers and mycorrhiza formation can both significantly improve the P supply of plants, but P fertilizers might inhibit mycorrhiza formation and change the microbial P cycling. To test the dimension and consequences of P fertilizer impacts under maize (Zea mays L.), three fertilizer treatments (1) triple superphosphate (TSP, 21–30 kg P ha^?1 annually), biowaste compost (ORG, 30 Mg ha^?1 wet weight every third year) and a combination of both (OMI) were compared to a non‐P‐fertilized control (C) in 2015 and 2016. The test site was a long‐term field experiment on a Stagnic Cambisol in Rostock (NE Germany). Soil microbial biomass P (P_mic) and soil enzyme activities involved in P mobilization (phosphatases and ß‐glucosidase), plant‐available P content (double lactate‐extract; P_DL), mycorrhizal colonization, shoot biomass, and shoot P concentrations were determined. P deficiency led to decreased P immobilization in microbial biomass, but the maize growth was not affected. TSP application alone promoted the P uptake by the microbial biomass but reduced the mycorrhizal colonization of maize compared to the control by more than one third. Biowaste compost increased soil enzyme activities in the P cycling, increased P_mic and slightly decreased the mycorrhizal colonization of maize. Addition of TSP to biowaste compost increased the content of P_DL in soil to the level of optimal plant supply. Single TSP supply decreased the ratio of P_DL:P_mic to 1:1 from about 4:1 in the control. Decreased plant‐benefits from mycorrhizal symbiosis were assumed from decreased mycorrhizal colonization of maize with TSP supply. The undesirable side effects of TSP supply on the microbial P cycling can be alleviated by the use of compost. Thus, it can be concluded that the plant‐availability of P from soil amendments is controlled by the amendment‐specific microbial P cycling and, likely, P transfer to plants.     

Assessing the phenotypic and genotypic diversity of <Emphasis Type="Italic">Sclerotinia sclerotiorum</Emphasis> in France

White mould caused by the ascomycete Sclerotinia sclerotiorum affects the production of many economically important crops. The incidence of this disease has recently increased in France, especially in melon crops, which were not affected much in the past. One possible explanation for this situation is the emergence of strains with particular characteristics, including increased aggressiveness to melon. To test this hypothesis, 200 isolates of S. sclerotiorum were collected from six host crops (bean, brassica oilseed rape, carrot, lettuce, melon, witloof chicory) in different regions. They were genotyped with 16 microsatellites markers. A subsample of 96 isolates were assessed for their aggressiveness on melon leaves. Overall, the isolates from melon did not show higher aggressiveness on melon leaves than those which originated from other host plants. Moreover, the melon isolates did not present distinctive genetic characteristics in comparison with those from other crops and shared several of the 128 identified multilocus haplotypes with isolates collected from carrot, witloof chicory and oilseed rape. Furthermore the Bayesian analysis of the genetic structure indicated that the host plant is not a structuring factor of the three genetic clusters identified, and it suggested instead the occurrence of an isolation-by-distance process. Possible consequences of these results for the management of white mould and alternative hypotheses to explain the recent changes in disease incidence are presented.     

Two-dimensional magnetic particles

Single two-dimensional (2D) atomically thick magnetic particles of cobalt and iron with variable size and shape were fabricated by combining a mask technique with standard molecular beam epitaxy. Reduction of the lateral size of in-plane magnetized 2D cobalt films down to about 100 nanometers did not essentially modify their magnetic properties; although the separation of boundaries decreased greatly, neither domain penetrated the particle, nor was any sizable shape anisotropy observed. The mutual interaction of 2D cobalt particles was negligible, and the magnetic state of a single particle could be switched without modifying the state of the neighbors. Perpendicularly magnetized iron particles did not exhibit such responses. These results suggest that only a few atoms forming a 2D in-plane magnetized dot may provide a stable elementary bit for nanorecording.     

Effects of nitrogen and phosphorus fertilization on mycorrhizal formation of two poplar clones (Populus trichocarpa and P. tremula x tremuloides)

Mineral fertilization is a common management practice in short rotation forestry. The mycorrhizal formation of trees can be affected by fertilizer applications, however, very little is known on such effects in arable soils. The effects of a nitrogen (N) and phosphorus (P) fertilization on mycorrhizal formation of two poplar clones (Populus trichocarpa and P. tremula x tremuloides) were investigated at the plantation Abbachhof (South Germany). We determined the ectomycorrhizal colonization and the abundance of VAM spores in the soil during three years, and the species richness of sporocarps during one growing season. Approximately 26 to 73% of the fine roots of P. trichocarpa and 41 to 82% of the fine roots of P. tremula x tremuloides were colonized with ectomycorrhizal fungi. The percentage of ectomycorrizal colonization on P. tremula x tremuloides was significantly reduced after both fertilization treatments. On P. trichocarpa only the P‐fertilization reduced the ectomycorrhizal colonization. The composition of ectomycorrhizal morphotypes was significantly affected by the N and P fertilization on P. tremula x tremuloides, but not on P. trichocarpa. Sporocarps of 12 ectomycorrhizal fungi species were found at the plantation. Cortinarius uliginosus, Lactarius controversus and Krombholziella aurantiaca produced sporocarps only on control plots, whereas Cortinarius croceocaeruleus, Inocybe umbrina, Laccaria tortilis, Paxillus involutus and Rhizopogon roseolus produced sporocarps only on fertilized plots. Inocybe geophylla, I. glabripes, Laccaria laccata and Tuber borchii produced sporocarps on both control and fertilized plots. The density of VAM spores was lower in the rooting zone of Populus trichocarpa than under P. tremula x tremuloides. In an efficient management of these short rotation plantations mineral fertilizer applications must be low enough to avoid undesired suppressions of mycorrhizal formation.     

Evaluation of Digestible Energy and Protein for Growth and Nitrogen Retention in Juvenile Florida Pompano,Trachinotus carolinus

Juvenile Florida pompano (6.3 ± 0.50 g) were fed 1 of 12 diets formulated with an array of crude protein (340, 380, 420, 480, or 500 g/kg diet) and crude lipid (60, 100, 120, 160, or 180 g/kg diet) levels and estimated digestible protein to digestible energy (DP/DE) of 18.9–26.8 mg/kJ. In a second trial, apparent protein and energy digestibilities were empirically determined and coefficients used to calculate actual digestibilities. Digestible energy (DE) intake was 4.2–13.0 kJ/fish/d, and digestible protein (DP) intake was 0.13–0.32 g/fish/d. Average daily gain increased as a function of both DP and energy. Growth increased with increasing DP in all diets containing 24.0 mg/kJ DP/DE or greater until a plateau at 366 g DP/kg. Nitrogen gain was also a function of both DP and DE. Increasing energy at constant protein improved protein utilization. DP to maximize growth and nitrogen gain was between 356 and 366 g/kg. DE to attain maximum growth in juvenile Florida pompano is at least 15.4 MJ/kg with a DP/DE between 23.8 and 25.1 mg/kJ.