Monitoring the effects of land transformation on African clawless otters (Aonyx capensis) using fecal glucocorticoid metabolite concentrations as a measure of stress     

Tshepiso L. MAJELANTLE  Trevor MCINTYRE  Andre GANSWINDT 《Integrative zoology》2020,15(4):293-306

In a time of increasing environmental change caused by anthropogenic disturbance, there is a greater need to understand animal adaptations to manmade environments. In this regard, the measurement of stress‐related endocrine markers provides a useful tool to examine the impact of environmental challenges and the physiological consequences for wildlife occupying such space. The aims of the present study were to validate fecal glucocorticoid metabolite (fGCM) concentrations as a measure of stress using samples from a male African clawless otter (Aonyx capensis; n = 1) and to compare fGCM concentrations of otters occurring in a transformed and in 2 natural areas in South Africa. From the 5 different enzyme‐immunoassays (EIA) tested, a cortisol and oxoetiocholanolone (measuring 11,17 dioxoandrostanes) EIA revealed the highest response (74% and 48% increase, respectively) 30 and 24 hours after a stress event (translocation of a captive individual as part of its rehabilitation prior to release), respectively. For both EIAs, fGCM concentrations were comparable for samples collected up to 3 h post‐defecation. Using the cortisol EIA for subsequent analyses, fGCM concentrations of animals from the transformed area (n = 20; mean [± SD]: 0.468 [± 0.539] µg/g dry weight [DW]) were significantly higher (P = 0.013) than those from otters in the natural areas (n = 17; 0.242 [± 0.226] µg/g DW). These preliminary results suggest that African clawless otters may have increased adrenocortical activity that could be due to conditions linked to living in a transformed environment.  相似文献   

Production of the Australian freshwater silver perch, Bidyanus bidyanus (Mitchell), at two densities in earthen ponds     

Stuart J. Rowland  Geoff L. Allan  Matthew Hollis  Trevor Pontifex 《Aquaculture (Amsterdam, Netherlands)》1995,130(4):317-328

Silver perch fingerlings (mean weight 15.3 g) were stocked at densities of 21 000 and 7000 fish/ha in six 0.1-ha earthen ponds and cultured for 10 months. There were three replicate ponds for each density. Ponds were aerated for at least 11 h a day and water was added every 4 weeks to replace that lost by evaporation and seepage. Fish were fed a formulated diet containing 35% crude protein at 4% body weight per day for the first 4 weeks and at rates up to 3% thereafter. The mean annual production rate of 9819 kg/ha of fish stocked at 21 000/ha was significantly higher (P < 0.01) than the annual rate of 3699 kg/ha of fish stocked at 7000/ha. The maximum daily production and growth rates achieved in any pond over a 1-month period during summer were 97.7 kg/ha and 5.1 g/fish, respectively. Stocking density did not significantly (P > 0.05) affect survival rate (treatment means for 21 000 and 7000 fish/ha: 92.8 and 94.7%), daily growth rate (0.2–3.3 and 0.3–3.4 g/fish), weight at harvest (434.9 and 473.2 g), food conversion ratio (1.9:1 and 1.8:1) and cost of feeding ($A1.55 and $A1.47/kg), suggesting that higher stocking densities and production rates are possible. Water temperatures ranged from 11.1 to 30.0 °C. Significantly (P < 0.05) slower growth during December was associated with concentrations of NH₃-N up to 0.65 mg/l. The results demonstrate that silver perch is an excellent species for semi-intensive culture in static earthen ponds with the potential to form the basis of a large industry in Australia, based on high-volume, relatively low-cost production.  相似文献   

Genetic variability and heritability estimates for hardseededness and flowering in balansa clover (Trifolium michelianum Savi) populations     

Ramakrishnan M. Nair  Andy D. Craig  Trevor D. Rowe  Steve R. Biggins  Colleen H. Hunt 《Euphytica》2004,138(3):197-203

Suitability of annual pasture legume species like balansa clover (Trifolium michelianum Savi) in southern Australian farming systems depends on their hardseededness and time to flowering. Late maturing varieties with increased rate of hardseed breakdown, particularly in the late summer—early autumn period are desirable to ensure reliable regeneration in permanent pastures. Two half-sib family balansa clover populations were used to estimate heritability for the rate of breakdown of hardseededness and time to flowering. High narrow-sense heritability estimates (90.5–96.1%, rate of hardseed breakdown; 85.9–94.5%, time to flowering) were obtained, and were mainly attributed to additive gene effects. There was no relationship between rate of hardseed breakdown and time to flowering in Group1 half-sib family, which indicated that selection for both traits could be undertaken independently. In half-sib family Group 2 the relationship between the two traits suggested the possibility of selecting late maturing cultivars with increased rate of hardseed breakdown. Significant differences in time to flowering and rate of hardseed breakdown both within and between the two half-sib family groups suggested that phenotypic recurrent selection would be effective in improving the traits in these populations.  相似文献   

Photoprotection of Beauveria bassiana: Testing simple formulations for control of the coffee berry borer     

Steven Edgington  Hector Segura  William De la Rosa  Trevor Williams 《国际虫害防治杂志》2013,59(3):169-176

The entomopathogenic fungus, Beauveria bassiana is considered to be one of the few natural enemies available for use against the coffee berry borer. In an attempt to enhance the efficacy of this pathogen, a range of concentrations of 22 substances was tested in simple laboratory tests using natural sunlight or a UV light source. Unprotected B. bassiana spores were almost completely inactivated by exposure to 60 min of direct sunlight or 20 s of UV light of 302 nm wavelength. Seven of the 22 substances tested showed little or no photoprotective properties and eight of the substances appeared directly detrimental to spore germination. Of the remainder, sucrose, yeast, yeast extract, uric acid, casein, and molasses had limited photoprotective properties. The most effective substances tested were egg albumen and skimmed milk powder which could extend the persistence of B. bassiana spores by a factor of almost three. A mixture of 3% (w/v) albumen and 4% (w/v) milk powder gave the highest degree of spore protection per unit cost. Young coffee plants sprayed with this mixture did not suffer any significant phytotoxic effects. A field trial, involving two applications of spores with or without the milk and albumen mixture, failed to show that improved spore persistence resulted in increased coffee berry borer control. Very lowlevels of pest infestation observed in field plots together with unusual, unfavourable weather conditions may have accounted for this unexpected result.  相似文献   

Compression form-fitted athletic wear: Pressure performance,moisture management properties under different tension ratios,and corresponding psychophysical responses     

Rong Liu  Trevor Little  J. R. Williams 《Fibers and Polymers》2014,15(3):632-644

Pressure performance and moisture management properties (MMP) of compression form-fitted athletic wear (CFA) play important role in achieving their mechanical functionality, wearing comfort, and physiological health for athletes during intensive exercises. Based on the 5Ps model, pressure and liquid moisture transfer attributes and their resultant subjective perceptions are analyzed and discussed through adopting objective and subjective measuring methods in this study. The MMP of eight types of fabric specimens were evaluated when the specimens were stretched at tension ratios of 0 %, 10 % and 20 % by applying an innovatively improved moisture management test method. Most of the tested specimens presented satisfied MMP when tested in a relaxed state. Testing under tension status significantly influenced the MMP of the tested specimens. The changes were mainly reflected in the prolonged wetting time, the increased absorption rates at the skin-contacted fabric surface, the reduced wetted radius and spreading speed at outer side of fabric, and the weakened one-way transfer properties. The tested fabrics with stretch of 20 % showed, in general, better performances in MMP than those with a stretch of 10 %. Pressure characteristic values ranging from 1679.88 to 2752.89 Pa on average were extracted from the different six pressure zones around the tested athletes’ bodies. Our improved MMT test method provides a new approach to study the fabric MMP when fabrics are under different tensions. Five sensory dimensions were used to analyze psychophysical responses to the physical stimulus of pressure and MMP, which revealed complex interactive mechanisms existing between pressure action, moisture transfer attributes and comfort perceptions related to compression athletic wear.  相似文献   

Materials science. A bright bio-inspired future     

Douglas T 《Science (New York, N.Y.)》2003,299(5610):1192-1193

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Blue-light-activated histidine kinases: two-component sensors in bacteria     

Swartz TE  Tseng TS  Frederickson MA  Paris G  Comerci DJ  Rajashekara G  Kim JG  Mudgett MB  Splitter GA  Ugalde RA  Goldbaum FA  Briggs WR  Bogomolni RA 《Science (New York, N.Y.)》2007,317(5841):1090-1093

Histidine kinases, used for environmental sensing by bacterial two-component systems, are involved in regulation of bacterial gene expression, chemotaxis, phototaxis, and virulence. Flavin-containing domains function as light-sensory modules in plant and algal phototropins and in fungal blue-light receptors. We have discovered that the prokaryotes Brucella melitensis, Brucella abortus, Erythrobacter litoralis, and Pseudomonas syringae contain light-activated histidine kinases that bind a flavin chromophore and undergo photochemistry indicative of cysteinyl-flavin adduct formation. Infection of macrophages by B. abortus was stimulated by light in the wild type but was limited in photochemically inactive and null mutants, indicating that the flavin-containing histidine kinase functions as a photoreceptor regulating B. abortus virulence.  相似文献   

Observation of a one-dimensional Tonks-Girardeau gas     

Kinoshita T  Wenger T  Weiss DS 《Science (New York, N.Y.)》2004,305(5687):1125-1128

We report the observation of a one-dimensional (1D) Tonks-Girardeau (TG) gas of bosons moving freely in 1D. Although TG gas bosons are strongly interacting, they behave very much like noninteracting fermions. We enter the TG regime with cold rubidium-87 atoms by trapping them with a combination of two light traps. By changing the trap intensities, and hence the atomic interaction strength, the atoms can be made to act either like a Bose-Einstein condensate or like a TG gas. We measure the total 1D energy and the length of the gas. With no free parameters and over a wide range of coupling strengths, our data fit the exact solution for the ground state of a 1D Bose gas.  相似文献   

The assessment of fishery status depends on fish habitats     

Christopher J. Brown  Andrew Broadley  Maria F. Adame  Trevor A. Branch  Mischa P. Turschwell  Rod M. Connolly 《Fish and Fisheries》2019,20(1):1-14

At the crux of the debate over the global sustainability of fisheries is what society must do to prevent over‐exploitation and aid recovery of fisheries that have historically been over‐exploited. The focus of debates has been on controlling fishing pressure, and assessments have not considered that stock production may be affected by changes in fish habitat. Fish habitats are being modified by climate change, built infrastructure, destructive fishing practices and pollution. We conceptualize how the classification of stock status can be biased by habitat change. Habitat loss and degradation can result in either overly optimistic or overly conservative assessment of stock status. The classification of stock status depends on how habitat affects fish demography and what reference points management uses to assess status. Nearly half of the 418 stocks in a global stock assessment database use seagrass, mangroves, coral reefs and macroalgae habitats that have well‐documented trends. There is also considerable circumstantial evidence that habitat change has contributed to over‐exploitation or enhanced production of data‐poor fisheries, like inland and subsistence fisheries. Globally many habitats are in decline, so the role of habitat should be considered when assessing the global status of fisheries. New methods and global databases of habitat trends and use of habitats by fishery species are required to properly attribute causes of decline in fisheries and are likely to raise the profile of habitat protection as an important complementary aim for fisheries management.  相似文献   

Geographical information systems-based models for offshore floating marine fish cage aquaculture site selection in Tenerife, Canary Islands     

Oscar M Pérez  Trevor C Telfer  & Lindsay G Ross 《Aquaculture Research》2005,36(10):946-961

The present study focuses on the development of a standard methodology for selection of suitable sites for offshore (exposed) marine fish‐cage farming (floating cages) of seabream (Sparus aurata) and seabass (Dicentrarchus labrax) in an island environment, using Tenerife as an example. Site selection is a key factor in any aquaculture operation, affecting both success and sustainability and can solve conflicts between different activities, making a rational use of the coastal space. Site selection was achieved by using geographical information systems (GIS)‐based models and related technology to support the decision‐making process. The framework for spatial multicriteria decision analysis used in this study began with a recognition and definition of the decision problem. Subsequently, 31 production functions (factors and constraints) were identified, defined and subdivided into eight submodels. These were then integrated into a GIS database in the form of thematic layers and later scored for standardization. At this stage, the database was verified by field sampling to establish the quality of data used. The decision maker's preferences were incorporated into the decision model by assigning weights of relative importance to the evaluation under consideration. These, together with the thematic layers, were incorporated using multicriteria evaluation techniques and simple overlays to provide an overall assessment of possible alternatives. The integration, manipulation and presentation of the results by means of GIS‐based models in this sequential and logical flow of steps proved to be very effective for helping the decision‐making process of site selection. Tenerife has very favourable environmental conditions for culture of marine fish and there are no totally unsuitable sites for cage farming identified in this study. On the other hand, there are few very suitable sites (high scores) either, principally due to the heavy use of the coastline and the conflicts between different users. From the 228 km² of available area for siting cages in the coastal regions with depth less than 50 m, the total area suitable for siting cages (scores 6–8) was 37 km². There are only 0.51 km² of very suitable areas (score 8) and approximately 5.37 km² of suitable (score 7), most of these being located in the southeast of the island. These relatively small areas of suitability should be put into the context of the wider use of the coastal environment around Tenerife.  相似文献