Late Archean biospheric oxygenation and atmospheric evolution

High-resolution geochemical analyses of organic-rich shale and carbonate through the 2500 million-year-old Mount McRae Shale in the Hamersley Basin of northwestern Australia record changes in both the oxidation state of the surface ocean and the atmospheric composition. The Mount McRae record of sulfur isotopes captures the widespread and possibly permanent activation of the oxidative sulfur cycle for perhaps the first time in Earth's history. The correlation of the time-series sulfur isotope signals in northwestern Australia with equivalent strata from South Africa suggests that changes in the exogenic sulfur cycle recorded in marine sediments were global in scope and were linked to atmospheric evolution. The data suggest that oxygenation of the surface ocean preceded pervasive and persistent atmospheric oxygenation by 50 million years or more.     

The relevance of data on genetic diversity for the conservation of Afro-montane regions

Molecular data are shedding new light on our understanding of genetic diversity and biological diversity in general. We examine results of recent genetic studies on African birds that document endemic diversity in small, isolated montane forests of Africa. These studies show that levels of genetic differentiation in these isolated montane regions are substantial and indicate little or no gene flow with their closest populations. Although this pattern of locally distributed montane taxa is not something that has gone unnoticed by traditional taxonomists, we argue that many of the small, often outlying areas run the risk of being devalued in conservation planning because these areas generally have comparatively low levels of overall diversity and endemism (especially at the species level). We strongly suspect that other organisms will possess similar patterns of differentiation in Afro-montane regions of Africa and we argue that this information can be effectively brought to bear to highlight the conservation significance of these smaller areas.     

Spatial dynamics of beetles living on exposed riverine sediments in the upper River Severn: method development and preliminary results

• 1. Exposed riverine sediments (ERS) are habitats for a large number of rare and specialized invertebrates and, as such, are of considerable conservation importance. Actions that threaten ERS specialists operate on a variety of scales and include river engineering, flow regulation and livestock damage. Populations of specific species of ERS specialist beetles are likely to exhibit individual responses to these threats, depending on the spatial structure and dynamics of the population. An understanding of the spatial dynamics of ERS specialist beetles is, therefore, essential if conservation initiatives are to be successful.
• 2. A mark–recapture experiment was used to investigate the spatial dynamics of beetles on a section of the upper River Severn, mid‐Wales, during June and August 2002. Two species of carabid, Bembidion atrocaeruleum Stephens and Bembidion decorum (Zenker), and one elaterid, Fleutiauxellus maritimus (Curtis), were individually marked and released on one of nine discrete patches of ERS demonstrating a range of patch size, sediment size, habitat heterogeneity, degree of shading, vegetation cover and grazing intensity. The methods used to trap, handle and individually mark beetles were all found to be suitable.
• 3. Population size of B. atrocaeruleum was mainly determined by ERS patch size, suggesting that, in contrast to F. maritimus, this species used all ERS microhabitats.
• 4. During the June study, 5.7% of marked and recaptured B. atrocaeruleum and 10% of marked and recaptured B. decorum actively moved between ERS patches over water or through thick vegetation in both upstream and downstream directions. Inter‐patch movements of >65 m for B. atrocaeruleum and >135 m for B. decorum were detected. Movement rates in August were lower. F. maritimus showed no evidence of inter‐patch movement.
• 5. The lower rate of dispersal and more specific habitat requirements are postulated as reasons for the greater rarity of F. maritimus.

Copyright © 2004 John Wiley & Sons, Ltd.     

Canine adder bites in the UK: a retrospective study of cases reported to the Veterinary Poisons Information Service

This retrospective study examined cases with follow-up reported to the Veterinary Poisons Information Service (VPIS) between September 1985 and December 2010. Most bites (69.2 per cent) occurred between April and July, particularly between 15:00 and 16:00 hours. Adder bites were more frequently reported in the south-east of England, particularly in Surrey. Swelling to the face and limbs was common, as was lethargy, depression, hyperthermia and tachycardia. About two-thirds of dogs developed both systemic and local effects, while a third developed local effects alone. Initial clinical effects usually occurred within two hours, with full recovery typically occurring five days after the bite. Antivenom was used in 55.9 per cent of cases and appeared to significantly reduce duration of oedema from an average of 94 to 47 hours. Adder bites can cause significant morbidity (97 per cent of dogs were symptomatic), but mortality is low (4.6 per cent died).     

Saving the sagebrush sea: An ecosystem conservation plan for big sagebrush plant communities

Vegetation change and anthropogenic development are altering ecosystems and decreasing biodiversity. Successful management of ecosystems threatened by multiple stressors requires development of ecosystem conservation plans rather than single species plans. We selected the big sagebrush (Artemisia tridentata Nutt.) ecosystem to demonstrate this approach. The area occupied by the sagebrush ecosystem is declining and becoming increasingly fragmented at an alarming rate because of conifer encroachment, exotic annual grass invasion, and anthropogenic development. This is causing range-wide declines and localized extirpations of sagebrush associated fauna and flora. To develop an ecosystem conservation plan, a synthesis of existing knowledge is needed to prioritize and direct management and research. Based on the synthesis, we concluded that efforts to restore higher elevation conifer-encroached, sagebrush communities were frequently successful, while restoration of exotic annual grass-invaded, lower elevation, sagebrush communities often failed. Overcoming exotic annual grass invasion is challenging and needs additional research to improve the probability of restoration and identify areas where success would be more probable. Management of fire regimes will be paramount to conserving sagebrush communities, as infrequent fires facilitate conifer encroachment and too frequent fires promote exotic annual grasses. Anthropogenic development needs to be mitigated and reduced to protect sagebrush communities and this probably includes more conservation easements and other incentives to landowners to not develop their properties. Threats to the sustainability of sagebrush ecosystem are daunting, but a coordinated ecosystem conservation plan that focuses on applying successful practices and research to overcome limitations to conservation is most likely to yield success.     

Evaluation of a direct ELISA for the serodiagnosis of Oestrus ovis infections in sheep.

Oestrosis is a parasitic disease of sheep and goats caused by the nasal bot fly Oestrus ovis. In the United Kingdom the economic losses as a result of infestation can be considered negligible, but the differentiation of O ovis cases from more serious diseases such as listeriosis, gid and sheep scab is of considerable importance. Currently, diagnosis of oestrosis relies on the subjective observation of clinical signs or the demonstration of larvae postmortem. This paper assesses the effectiveness of a direct enzyme-linked immunosorbent assay (ELISA) using a crude somatic antigen from first-stage larvae (L1) in the serodiagnosis of oestrosis. The system has been validated with sera from both endemic and non-endemic areas and the results correlated with the clinical data found postmortem. The sensitivity and specificity of the assay were 97.4 per cent and 97.6 per cent, respectively, using a cut-off point based on 35 per cent binding of a reference positive control serum.     

Health and metabolic responses of young calves housed at -30 degrees C to -8 degrees C.

Newborn, male, Holstein calves, were continuously housed for three weeks in calf hutches at 17 degrees C or in a thermal environment which varied rhythmically on a daily basis either between -20 degrees C and -8 degrees C (experiment A) or between -30 degrees C and -18 degrees C (experiment B). Compared to warm-housed calves, cold-housed calves in experiment A had metabolic rates which were significantly higher (p less than 0.001) in a standing position but which were not significantly different (p less than 0.05) in a recumbent position. Recumbent and standing cold-housed calves in experiment B had an increased (p less than 0.05) metabolic rate compared to warm-housed controls. Heat loss was less (p less than 0.05) for recumbent cold-housed calves in experiment B than for standing calves in a thermoneutral environment. Localized subcutaneous hemorrhages of hindlimbs were a consistent necropsy finding among all cold-housed calves. Average daily gains of cold-housed calves were not significantly different from warm-housed controls. Clinical, physiological and pathological findings indicated that cold treatments used in the present study did not cause serious harm to calves. It was concluded that calves housed in properly managed hutches are remarkably cold tolerant.     

Evaluation of Duroc- vs. Pietrain-sired pigs for growth and composition

Accurate evaluations of growth and composition traits enable better management decisions regarding genetic merit, feeding, and marketing. Sires from Duroc and Pietrain populations were used to produce crossbred pigs, which were evaluated for growth and composition traits. All parents were normal for the ryanodine receptor gene. Boars from each breed were mated to either Yorkshire or F1 Yorkshire-Landrace females with 307 offspring evaluated from birth through 26 wk of age. No significant differences between sire breeds were seen for pig BW from birth through 10 wk of age. Body weight, 10th rib backfat (BF10), last rib backfat (LRF), and loin muscle area (LMA) were serially measured at 10, 13, 16, 19, 22, 24, and 26 wk of age. At 26 wk of age, Duroc-sired progeny were heavier (143.4 vs. 132.7 kg, P < 0.001), had more BF10 (27.1 vs. 23.7 mm, P < 0.001) and LRF (21.2 vs. 19.2 mm, P < 0.001), but had similar LMA (46.4 vs. 47.1 cm2) compared with Pietrain-sired progeny. Mean feed efficiency did not differ between breed of sire in any period of the study. Duroc progeny had a greater ADG (980.1 vs. 892.3 g/d, P < 0.001) from 10 to 26 wk of age than Pietrain-sired pigs. Composition traits of fat-free total lean (FFTOLN), total fat tissue (TOFAT), empty body protein (EBPRO), and empty body lipid (EBLIPID) were calculated. Random regression animal models with polynomial regression on week on-test were fitted to BW, BF10, LRF, LMA, FFTOLN, TOFAT, EBPRO, and EBLIPID from 10 to 26 wk of age. Duroc-sired barrows tended to grow faster but with more fat tissue, and Pietrain-sired gilts were slower growing but leaner, whereas Duroc-sired gilts and Pietrain-sired barrows were intermediate for growth and backfat measures. Serial heritability estimates generally increased from 10 to 26 wk of age with ranges as follows: BW (0.05 to 0.39), BF10 (0.13 to 0.76), LRF (0.11 to 0.79), LMA (0.05 to 0.73), FFTOLN (0.07 to 0.16), TOFAT (0.19 to 0.45), EBPRO (0.02 to 0.55), and EBLIPID (0.12 to 0.60). Pigs sired by Duroc and Pietrain boars had similar lean tissue growth but achieved it through different mechanisms.     

The Sage-Grouse Habitat Mortgage: Effective Conifer Management in Space and Time

Management of conservation-reliant species can be complicated by the need to manage ecosystem processes that operate at extended temporal horizons. One such process is the role of fire in regulating abundance of expanding conifers that disrupt sage-grouse habitat in the northern Great Basin of the United States. Removing conifers by cutting has a beneficial effect on sage-grouse habitat. However, effects may last only a few decades because conifer seedlings are not controlled and the seed bank is fully stocked. Fire treatment may be preferred because conifer control lasts longer than for mechanical treatments. The amount of conservation needed to control conifers at large temporal and spatial scales can be quantified by multiplying land area by the time needed for conifer abundance to progress to critical thresholds (i.e., “conservation volume”). The contribution of different treatments in arresting conifer succession can be calculated by dividing conservation volume by the duration of treatment effect. We estimate that fire has approximately twice the treatment life of cutting at time horizons approaching 100 yr, but, has high up-front conservation costs due to temporary loss of sagebrush. Cutting has less up-front conservation costs because sagebrush is unaffected, but it is more expensive over longer management time horizons because of decreased durability. Managing conifers within sage-grouse habitat is difficult because of the necessity to maintain the majority of the landscape in sagebrush habitat and because the threshold for negative conifer effects occurs fairly early in the successional process. The time needed for recovery of sagebrush creates limits to fire use in managing sage-grouse habitat. Utilizing a combination of fire and cutting treatments is most financially and ecologically sustainable over long time horizons involved in managing conifer-prone sage-grouse habitat.