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41.
Jeff K. Waage James W. Woodhall Sam J. Bishop Julian J. Smith David R. Jones Nicola J. Spence 《Agricultural Systems》2008
An analysis is made of the pattern of reported introductions of plant pests (insects, mites, fungi, bacteria and viruses) over the 20th century into Africa and Europe. Rates of reported introductions followed very different patterns between the continents, with European introductions rising over the century, while reported African introductions peaked mid-century and declined thereafter. This pattern is consistent with two quite different, but not mutually exclusive, hypotheses based on (1) continental differences in rates of arrival and establishment of new species and (2) differences in changing capacity to detect and identify new introductions. Patterns of pest taxa introduced, and crops affected, were broadly similar between continents. 相似文献
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Calculations using a simple two-reservoir model indicate that a doubling of the S deposition may in some cases cause the pH in freshwater to decrease by 0.7 to 1.0 pH units or even more, e.g., from about pH 6 to about 5 without assuming changes in soil properties such as base saturation. This is in contrast to the suggestions made by other authors that the shift will be about 0.2 pH units or less. 相似文献
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NLRS is a joint Canadian/Norwegian study of the pace and extent of recovery of lake ecosystems from acidification. Twenty-one oligotrophic lakes within Killarney Park, Ontario were selected as the principal Canadian sites for this study. NLRS objectives for Killarney included: testing of new biomonitoring techniques, assessment of multiple stressor effects on recovery, and development of biological endpoints for critical load modelling. Sampling included: phytobenthos, phytoplankton, pelagic zooplankton, littoral zooplankton, sublittoral chironomids, and fish, as well as sediment cores for paleolimnological assessment of pre-industrial biotic communities. Strong statistical models were developed relating biotic composition to water quality variables. Prediction of future recovery will require additional understanding of the effects of differential colonization rates, climate variability, and the impact of unique events such as the arrival of an exotic species. Recovery proved to be best measured against modern reference data from circumneutral lakes rather than against historic data from acidified systems. 相似文献
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Comparative growth study of wild- and hatchery-produced Arctic charr (Salvelinus alpinus L.) in a coldwater recirculation system 总被引：1，自引：1，他引：0
Sten Ivar Siikavuopio Steinar Skybakmoen Bjrn-Steinar Sther 《Aquacultural Engineering》2009,41(2):122-126
The growth performance of Arctic charr of wild (W) and hatchery (H) origin was compared in a commercial coldwater recirculation system (Villmarksfisk, Bardu, 68°N, 19°E, Norway). The initial individual body mass was 115 g and similar between groups. The rearing temperature was 9.2 °C and the fish were held under continuous light (24:0 L:D). At the end of the experiment (day 240), the average body mass of the H fish was 451 g compared to 231 g in the W fish. The accumulated mortality of wild Arctic charr was about 40%; 10 times higher than the mortality of hatchery-produced Arctic charr (4%). The difference in growth performance and survival rate impose a great disadvantage of using this wild caught fish as compared to commercially available hatchery-produced Arctic charr in coldwater recirculation system. However, further improvements in the production chain (catching, live transport, quarantine, size grading, etc.) may still make production of wild caught Arctic charr profitable, especially as it demands a higher price in niche markets. 相似文献
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Ingebrigt Uglem Kilian Toledo‐Guedes Pablo Sanchez‐Jerez Eva Marita Ulvan Tor Evensen Bjrn Steinar Sther 《Aquaculture Research》2020,51(4):1720-1730
Salmon farms attract large amounts of wild fish, which prey on uneaten feed pellets. The modified diet of the wild fish aggregating at salmon farms may reduce the flesh quality of the fish, influencing the local fisheries. We compared the quality of saithe (Pollachius virens) captured near (farm associated—FA) or more than 5 km away (un‐associated—UA) from salmon farms in Norway. The fish were captured during summer, autumn and spring using two commercial fishing methods (jigging and bottom nets). Overall, the fillet quality of FA saithe was good, although it was clearly reduced for almost 10% of the catch. Moreover, the quality of the FA saithe was significantly reduced compared with UA saithe, but the differences were small. Our results also showed that fish caught with jigging had better quality than fish caught with nets, and that fish that died in the nets were of lower quality than fish that were alive after hauling. There was no clear variation among seasons in fillet quality. Although no major and overall differences in quality were found between FA and UA saithe, reduced quality for even a modest proportion of the fish may influence the value of the total catch. 相似文献
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Waage, S., P. Jonsson and A. Franklin: Evaluation of a cow-side test for detection of Gram-negative bacteria in milk from cows with mastitis. Acta vet. scand. 1994, 207-211.– A modified Limulus amebocyte lysate (LAL) cow-side test was evaluated under field conditions. The principle of the test is to visualize reactions between test components and endotoxin from the cell wall of Gram-negative bacteria. The practical purpose is to detect such bacteria in mastitic milk. Secretions from 789 udder quarters with clinical mastitis were examined by the LAL-test. Parallel quarter milk samples were sent to a mastitis laboratory for microbiological examination. Eleven veterinary surgeons in three veterinary districts in Norway performed the field investigations. Results of the LAL-test and culture agreed in 93% of all milk samples tested, agreement measured by kappa being 0.63. The sensitivity of the test in detecting Gram-negative bacteria was 63%, while the specificity was 97%. The predictive value of a positive test result was 70%, the figure being somewhat higher (75%) when the material was limited to milk samples without antibiotic residues. The predictive value of a negative test result was 95%. The LAL-test is considered to constitute a valuable cow-side test for the veterinary practitioner, aiding the selection of antibacterial drug of choice for the initial treatment of clinical mastitis. 相似文献
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Julian J. Smith Jeff Waage James W. Woodhall Sam J. Bishop Nicola J. Spence 《European journal of plant pathology / European Foundation for Plant Pathology》2008,121(3):365-375
The consequences of a globalisation of trade and climate change present an increased threat from first-entry pests and a challenge
to plant health authorities. In this paper, pest reporting for the continents of Africa and Europe are discussed, and argued
as a barometer of effective Plant Pest Diagnostic Services (PPDS) in terms of human capacity, infrastructure and policy-culture
for phytosanitary issues. To illustrate particular areas of concern, case studies are presented on recent pest events which
include outbreaks of Ralstonia solanacearum on Pelargonium, Xanthomonas campestris pv. musacearum on banana (banana Xanthomonas wilt) and Puccinia graminis f.sp. tritici race Ug99 on wheat (black stem rust). Examples are given of some recent initiatives to invigorate diagnostic capacity in
East Africa, spanning state-of-the-art centres of excellence, traditional capacity building and networking projects, and grass-root
level 'going-public' pest surveillance initiatives. Discussion is presented on the provision of PPDS and the impact of technology,
institutional factors, the private sector, accreditation of services and policy. Emphasis is placed on the role of PPDS in
support of regulatory policy. In recognising the precarious nature of many African cropping systems, the argument is made
for a more consolidated approach to PPDS in and for Africa. The paper is presented from the perspective of European practitioners
in pest diagnostic and risk analysis. 相似文献
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A questionnaire, in which 7 cases of udder disease were described, was distributed to 890 veterinarians in Norway. They were requested to classify the cases according to the diagnostic alternatives listed in the Norwegian Health Card System for Cattle (NHCSC). The NHCSC recordings are used for progeny testing of bulls, for disease monitoring, and for research purposes. The aim of this study was to evaluate the quality of the recordings for udder diseases. The questionnaire was answered by 633 veterinary surgeons. Four cases of clinical mastitis (CM) with abnormal secretion as well as other clinical signs of inflammation were correctly classified as CM by almost 100% of the veterinary surgeons. A cow in the final stage of lactation, showing no clinical signs except for clots in the milk, was considered not to be a clinical case by more than 25% of the veterinary surgeons. A typical case of subclinical mastitis (SM) was reported as SM by 83% of the veterinary surgeons, and as CM by 16%. A subclinical case with a recent history of clots in the secretion was classified as SM by 66% of the veterinary surgeons, but almost 40% either reported CM as their sole diagnosis or considered the case to be CM in combination with SM. Of the clinical cases, those exhibiting marked local signs of inflammation and a systemic reaction were correctly classified as acute clinical mastitis (ACM) by 96%-98% of the veterinary surgeons. In the NHCSC, the diagnostic alternatives for cases of CM are ACM and chronic clinical mastitis (CCM). One case, for which the diagnosis subacute clinical mastitis was appropriate according to standard definitions, was classified as CCM by 66%, and as ACM by 6%. Based on the information given in the questionnaire, the diagnosis for 2 of the clinical cases could have been either ACM or CCM, and for both cases each of these 2 alternatives was reported by more than 43% of the veterinary surgeons. A teat lesion, which was present together with ACM in one cow, was reported by 91% of the veterinary surgeons. 相似文献