Digital mapping of soil carbon sequestration potential with enhanced vegetation cover over New South Wales,Australia

Digital soil maps of soil organic carbon (SOC) sequestration potential resulting from a hypothetical 10% relative increase in long-term vegetation cover are presented at 100-m resolution across the state of New South Wales (NSW) in southeast Australia. This land management outcome is considered realistically achievable for many land managers, using strategies such as revegetation, grazing management or crop residue management. A mean state-wide potential increase of 5.4 Mg ha⁻¹ over the 0- to 30-cm depth interval was derived. Assuming a 20-year period of re-equilibration, this equates to an average SOC increase of 0.27 Mg ha⁻¹ year⁻¹. Sequestration potential is systematically influenced by a combination of climate, soil parent material and current vegetation cover, for example only 1.6 Mg ha⁻¹ SOC under dry conditions in sandy, infertile soil material with sparse vegetation cover, compared with 15.9 Mg ha⁻¹ under wet conditions in clay-rich, fertile soil material with moderate–high vegetation cover. The outputs could be used to identify locations of highest sequestration potential and thereby help prioritize areas and inform decisions on sequestration programmes. Future application of the method at field scale with high levels of accuracy, together with strategic sampling, may provide statistically reliable estimates of carbon sequestration, for application in carbon trading schemes such as Australia's Emissions Reduction Fund. The modelling involved a conceptually transparent ‘space-for-time substitution’ process. Multiple linear regression (MLR) and random forest (RF) modelling techniques were applied, but only MLR gave consistently meaningful results. The apparent failing of RF in this application warrants further examination.     

Evaluation of Growth Performance and Whole-body Composition of Juvenile Hybrid Striped Bass Morone chrysops × Morone saxatilis and Red Drum Sciaenops ocellatus Fed High-protein and High-lipid Diets

To investigate potential use of increasing nutritional density of diets for rapid growth of warm‐water fishes, a feeding trial was conducted in which growth performance, body indexes, and whole‐body composition of juvenile hybrid striped bass fed diets comprising protein (49, 54, and 59%), lipid (16, 20, 23, and 28%), and energy (22.0–25.1 kJ/g) concentrations beyond established minimum levels were compared to those of fish fed a more typical commercial reference diet (37.5% crude protein, 10.5% crude lipid, and 19.6 kJ/g energy on a dry matter basis). A subset of the experimental diets and the commercial reference diet also were fed to juvenile red drum. After 6 wk of feeding, hybrid striped bass fed the high‐protein and high‐lipid diets showed much greater growth performance compared to fish fed the commercial diet. Increasing dietary protein level, but not lipid level, tended (P ≤ 0.1) to enhance weight gain and feed efficiency of hybrid striped bass. Hepatosomatic index (HSI), intraperitoneal fat (IPF) ratio, and whole‐body protein were significantly (P < 0.01) influenced by dietary protein level. The dietary lipid and associated energy level had significant negative linear effects on daily feed intake. Linear regression analysis showed that dietary energy : protein ratio, largely influenced by dietary protein level, moderately but significantly influenced weight gain, HSI, IPF ratio, and whole‐body protein of hybrid striped bass and red drum. Red drum grew very similar to hybrid striped bass in response to the experimental diets. However, significant differences in HSI, IPF ratio, whole‐body protein, lipid, moisture, and ash between hybrid striped bass and red drum were observed, indicating species differences in protein and energy partitioning. In particular, the excessive lipid in the diet increased HSI and whole‐body lipid of red drum but not of hybrid striped bass.     

Novel insights into the marine phase and river fidelity of anadromous twaite shad Alosa fallax in the UK and Ireland

1. Most research on anadromous fishes has been invested in their freshwater life‐phases, resulting in a relatively sparse understanding of their spatial ecology during marine life‐phases. However, understanding the marine dispersal of anadromous fishes is essential to identify threats and to implement conservation measures that fully encompass their lifecycle.
2. The twaite shad Alosa fallax is an anadromous fish increasingly imperilled across its range due to pollution, harvesting, and impediments to freshwater migration, but little is known about its distribution and movements during its marine life‐phase. Here, the application of acoustic telemetry provided novel insights into the coastal dispersal of twaite shad in the UK and Ireland during 2018–2019, and the freshwater entry of individuals during the 2019 spawning season.
3. Of 73 twaite shad acoustic‐tagged during their upstream migration in the River Severn in May 2018, 58 emigrated from the river. Twelve were subsequently detected 200 km to the south‐west at the Taw–Torridge Estuary between July 2018 and April 2019, where estuarine movements up to 5.8 km inland occurred in summer, winter, and spring. One was subsequently detected in the Munster Blackwater Estuary (Ireland) and then in the River Severn, indicating a minimum movement distance of 950 km. Thirty‐four (59%) of the emigrating individuals from 2018 re‐entered fresh water in the rivers Severn (n = 33) and Wye (n = 2) in April and May 2019.
4. These results suggest year‐round use of estuarine and nearshore habitats by at least a subset of the twaite shad population during their marine phase, providing evidence of potential range overlap between populations that spawn in different areas in the UK and Ireland, which may be facilitated by substantial dispersal. The results also highlight the potential of telemetry for estimating freshwater and marine mortality, and the benefits of sharing detection data across networks.

     

The physiological tolerance of the grey carpet shark (<Emphasis Type="Italic">Chiloscyllium punctatum</Emphasis>) and the epaulette shark (<Emphasis Type="Italic">Hemiscyllium ocellatum</Emphasis>) to anoxic exposure at three seasonal temperatures

The epaulette shark (Hemiscyllium ocellatum) and the grey carpet shark (Chiloscyllium punctatum) are commonly found in periodically hypoxic environments. The ecophysiological time available for these animals to safely exploit these niches during different seasonal temperatures was examined. The time to loss of righting reflex (T _LRR) was examined in response to an open ended anoxic challenge at three seasonal temperatures (23, 25 and 27°C). Ventilation rates were measured in an open ended anoxic challenge at 23°C and during 1.5 h of anoxia followed by 2 h of re-oxygenation at 23 and 25°C. The mean T _LRR of epaulette and grey carpet sharks was inversely proportional to temperature. The T _LRR was similar between species at 23°C; however, grey carpet sharks had significantly reduced T _LRR at higher temperatures. During the standardised anoxic challenge, epaulette sharks entered into ventilatory depression significantly earlier at 25°C. During re-oxygenation, epaulette sharks exposed to anoxia at 23°C had no significant increase in ventilation rates. However, after anoxic challenge and re-oxygenation at 25°C, epaulette sharks showed a significant increase in ventilation rates during re-oxygenation. Grey carpet sharks displayed no evidence of ventilatory depression during anoxia. However, during re-oxygenation, grey carpet sharks had significantly elevated ventilation rates above pre-experimental levels and control animals. These data demonstrate that the anoxia tolerance times of both species were temperature dependent, with a significant reduction in the T _LRR occurring at higher temperatures. Epaulette sharks had a significantly greater T _LRR at higher temperatures than grey carpet sharks, which did not enter into a ventilatory depression.     

Current status of non-residual control methods against stored product pests

There is an increasing dichotomy between the demands of the first world for quality food uncontaminated by insecticidal residues, and the desperate need of third-world populations to maintain and protect their harvested grain from the deprivations of insects, so as to maintain a minimum level of food security. Fumigation is widely regarded as a non-residual treatment and fumigation with phosphine will continue for the immediate future as the mainstay against insect infestation. However, to ensure its continued use, insect resistance to phosphine must be countered by more efficient application techniques. Already, available alternative control technologies such as hermetic storage and the use of controlled atmospheres using either nitrogen or carbon dioxide also rely heavily on well-sealed storage structures, that are rarely available in rigid silos, but easily obtainable with flexible plastic liners. Aeration systems to cool grain bulks and thereby prevent insect development, are being widely used even in warm climates but are only applicable for bulk grain. Other non-residual treatments such as mechanical impaction, irradiation, biological control or heating, are suitable for high-quality commodities or niche situations.     

Concentration of 17α-Methyltestosterone in HormoneTreated Feed: Effects of Analytical Technique, Fabrication, and Storage Temperature

Feed treated with 17α-methyltestosterone (MT) is used to manipulate the gender of early tilapia fry. In the USA, hormone-treated feed is used by selected producers under an Investigational New Animal Drug (INAD) program. While monitoring the fabrication and on-farm use of this treated feed, concerns were raised about the high performance liquid chromatography (HPLC) analytical procedure for detecting MT in feeds, the incorporation of MT in feeds during fabrication, and effects of storage temperature on MT concentration. A series of experiments demonstrated that the analytical procedure for detecting MT in feeds lacked high precision, and, on average, biased results low. MT was uniformly mixed with feed by spraying an MT-alcohol solution on feed while it was blended in an industrial ribbon mixer. Alcohol volumes ranging from 15 mL/kg to 150 mL/kg were equally effective at dispersing MT in feed. The concentrations of MT in feeds consistently declined over time if the storage temperatures were 25 C or higher. Freezing preserved the MT in feed, and the refrigeration of feed fabricated to contain 60 mg MT/kg maintained acceptable MT concentrations during 6 mo of storage.     

A model to evaluate the economic merits of dry season feeding of growing/fattening cattle in the sub-humid tropics

The economic effect of increased stocking rate permitted by the introduction of dry season feedin is evaluated with reference to the growing/fatening system of beef production in the sub-humid tropics. A widely applicable model is derived which requires few input variables, all of which will be easily obtainable in a specific location. The economic break-even point in terms of feeding cost and dry season length can be determined in order to assess the value of local diets or attempt the formulation of new ones. Increae in profitability due to dry season feeding is assessed taking into account increase in stocking rate, seasonal de-stocking practices, length of dry season, growth rates, feed costs and beef price. The model is appropriate for use in developing countries and can be employed manually to determine rapidly those management options worthy of more detailed consideration.     

A geographical approach to identify phosphorus-efficient genotypes among landraces and wild ancestors of common bean

Cultivars of common bean (Phaseolus vulgaris L.) capable of yielding well at low levels of native or added phosphorus (P) are highly desirable in many tropical production systems. The objective of the present study was to identify geographical regions which might be sources of such genotypes. A total of 364 landraces, cultivars and wild genotypes, drawn from a broad geographic range, were divided on the basis of growth habit into four field trials, each comprising two levels of P, stressed and unstressed, on an infertile Andosol in Popayan, Colombia. The regression relationship between grain yield per plant in the presence and in the absence of stress was determined, and each genotype's deviation from this relationship was used as a measure of P-efficiency. There was highly significant variation in efficiency among genotypes in all growth habits, and in climbing beans there were consistent regional differences, superior genotypes being identified with greater frequency among those from Bolivia, West Mexico and South Mexico-West Guatemala. The latter region was promising for prostrate bush genotypes also. Wild beans in general performed relatively poorly; it appears that P-efficiency traits in P. vulgaris have been acquired during or after domestication. These results confirm that genetic differences in P-efficiency exist among common bean genotypes and suggest that these are related to geographic origin. Furthermore, the use of a representative sample of germplasm can help to identify segments of the gene bank that are especially promising as sources of desirable traits. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of xylanase treatments on gelling and water-uptaking properties of psyllium

The effects of a commercial food-grade xylanase on the physicochemical properties of psyllium were evaluated. The enzymatic reactions were conducted in solid state at ambient temperature. The enzyme-treated psyllium preparations were analyzed and compared with the starting psyllium for their water-uptake properties, gelling capacities, soluble and insoluble fiber contents, and surface structures. The solid-state xylanase treatment significantly reduced both water-uptake and gelling capacities of psyllium (p < 0.01), with a slight decrease of soluble fiber content, whereas no effect on insoluble fiber content was observed. The xylanase treatment also resulted in a smoother surface structure of psyllium particles. In addition, no special equipment and operation were required to conduct the enzymatic reaction, which generated no waste. These data indicated a potential to improve the physicochemical properties of psyllium by use of the solid-state xylanase reactions to promote the utilization of psyllium fiber in functional foods for promoting human health.