Impacts of chronic marine oil pollution and the murre hunt in Newfoundland on thick-billed murre Uria lomvia populations in the eastern Canadian Arctic     

Francis K. Wiese  Gregory J. Robertson 《Biological conservation》2004,116(2):205-216

We developed a deterministic and stochastic age-based matrix projection population model to assess and quantify the impact of mortality caused by chronic oil pollution and legal hunting on thick-billed murre Uria lomvia populations breeding and wintering in eastern Canada. We calculate the potential population growth rate in the absence of anthropogenic mortality sources using a modeling technique that translates absolute number of birds killed from anthropogenic mortality to potential survival rates in the absence of these anthropogenic impacts. The intrinsic growth rate of the deterministic matrix based on vital rates from Coats Island (λ_d=1.0102), as well as the stochastic growth rate (λ_s=1.0098, 95% C.I. 0.9969-1.0226), matched observed population trends. Hunting mortality reduced population growth rate by 0.020 (0.012-0.039), oiling mortality reduced population growth rate by 0.025 (0.012-0.039). Combined these sources reduced the population growth rate by 0.047 (0.033-0.610). Although thick-billed murre populations are stable or slowly growing in eastern Canada, anthropogenic sources of mortality are reducing the ability of the population to grow, and increase vulnerability in these populations to changes in their environment and other pulse perturbations. Our modeling technique could be used to assess specific anthropogenic impacts on populations where a vital rates and numbers killed are known, but no long-term trend information is available.  相似文献   

A comparison of North American avian conservation priority ranking systems     

David W Mehlman  Kenneth V Rosenberg  Bruce Robertson 《Biological conservation》2004,120(3):383-390

The need to prioritize species based on their perceived endangerment has led to the development of systems for categorizing and assessing their degree of vulnerability. Systems with divergent biological and geographical scopes can result in conflicting lists of high-priority species, potentially confusing conservationists and hampering the efficient allocation of resources. To assess conservation priorities for North American birds, we compare three priority-setting systems; those of the International Union for the Conservation of Nature (IUCN), NatureServe, and Partners in Flight (PIF). We found highest correspondence among the three systems in the highest and lowest categories of the respective systems with lower levels of correspondence in intermediate categories. We suggest that this is because the systems, while using different formulations of criteria, are based on the major factors known to be correlated with extinction risk. The few examples of species listed as a high conservation priority by one group but not one or both of the others appear to be the result of differences in availability or interpretation of data. Better communication and collaboration among those responsible for compiling the priority lists for each system is needed.A primary difference among the systems was the total number of species identified as conservation priorities. IUCN identified the fewest species (47) and PIF the most (157). This difference is the result of differences in geographic and taxonomic scope of each system. However, when considered as the percent of the total number of taxa evaluated by each system, all systems identified approximately 20% of species as of conservation concern. To reconcile disparate lists, we urge that conservationists use a hierarchical approach that first considers species that meet thresholds for endangerment under global systems, followed by species considered most vulnerable relative to all continental biota.  相似文献   

Tracing ingestion of 'novel' foods in UK diets for possible health surveillance--a feasibility study     

Robertson C  Best N  Diamond J  Elliott P 《Public health nutrition》2004,7(2):345-352

  相似文献   

Food security in the Baltic Republics     

Pomerleau J  McKee M  McKee M  Robertson A  Vaask S  Pudule I  Grinberga D  Abaravicius A  Bartkeviciute R 《Public health nutrition》2002,5(3):397-404

  相似文献   

Diversity for abiotic and biotic stress resistance in the wild annual Cicer species     

K.B. Singh  B. Ocampo  L.D. Robertson 《Genetic Resources and Crop Evolution》1998,45(1):9-17

Data on 228 accessions of eight annual wild Cicer species and 20 cultivated chickpea check lines were evaluated for diversity in response to six of the most serious biotic and abiotic stresses which reduce crop yield and production stability of chickpea, i.e., ascochyta blight, fusarium wilt, leaf miner, bruchid, cyst nematode, and cold. Relative frequencies of score reactions to the above six stresses were recorded from all the annual wild Cicer species and the cultivated taxon. Patterns of distribution and amount of variation of the resistance reactions differed between stresses and species. C. bijugum, C. pinnatifidum and C. echinospermum showed accessions with at least one source of resistance (1 to 4 score reactions) to each stress. Overall, C. bijugum showed the highest frequencies of the highest categories of resistance. Next in performance was C. pinnatifidum followed by C. judaicum, C. reticulatum and C. echinospermum. Furthermore, C. bijugum had the highest number of accessions with multiple resistance to the six stresses; two accessions were resistant to five stresses and 16 to four. According to the Shannon-Weaver diversity indices (H), five species showed discrete mean diversity indices which varied from 0.649 in C. pinnatifidum to 0.526 in C. judaicum, whereas C. chorassanicum, C. cuneatum and C. yamashitae showed the lowest Hs, which were respectively 0.119, 0.174 and 0.216. Pair-wise correlations among the six biotic and abiotic stresses showed the possibility of combining these resistances. Interestingly, multiple resistant accessions were predominantly of Turkish origin.  相似文献   

Estimates of denitrification in soil by remote sensing of thermal infrared emission at different moisture levels     

Kerstin Robertson  Leif Klemedtsson  Sune Axelsson  Thomas Rosswall 《Biology and Fertility of Soils》1993,16(3):193-197

Remote sensing techniques may be one way to narrow the range of uncertainty in extrapolating N₂ emissions from small-scale to large-scale terrestrial ecosystems. In the present work we investigated the correlations between denitrification activity, soil moisture, and soil thermal infrared emissions. A field experiment was performed on two different agricultural soils, one loam and one silty clay. The results indicated that thermal infrared emissions can only be used to estimate the denitrification rate in soil within a limited range of soil moisture levels. Estimates of denitrification activity based on soil texture and moisture are, however, very likely to be a fruitful approach to generating large-scale N fluxes.  相似文献   

Immunization against Marek's disease: influence of strain of chickens, maternal antibody, and type of vaccine   总被引：2，自引：0，他引：2  

J L Spencer  J S Gavora  A A Grunder  A Robertson  G W Speckmann 《Avian diseases》1974,18(1):33-44

  相似文献   

Congenital inguinal hernias associated with a rent in the common vaginal tunic in five foals     

G H Spurlock  J T Robertson 《Journal of the American Veterinary Medical Association》1988,193(9):1087-1088

Five foals were admitted because of colic that developed within 24 hours after birth. Physical examination revealed swelling from the inguinal region to the cranial aspect of the prepuce. Through the skin overlying the swelling, distended loops of bowel could be palpated. The hernias could be reduced with the foals restrained in dorsal recumbency. Surgical exploration showed the swelling to be an inguinal hernia with small bowel herniation through a rent in the common vaginal tunic. Concurrent rupture of the vaginal tunic should be suspected when a congenital inguinal hernia is associated with colic, swelling that extends to the prepuce, or intestine that is easily palpated within the hernial swelling. Repeated manual reduction in these cases would be of little benefit and surgical intervention would be recommended.  相似文献   

A new analgesic drug combination in the horse   总被引：1，自引：0，他引：1  

J T Robertson  W W Muir 《American journal of veterinary research》1983,44(9):1667-1669

A xylazine and butorphanol drug combination produced minimal and transient hemodynamic effects and no significant respiratory depression when administered to 6 healthy horses. Combining xylazine and butorphanol produced a synergistic analgesic effect and provided good chemical restraint for a standing surgical procedure.  相似文献   

Field evaluation of Newcastle disease immunisation by concurrent inactivated oil-emulsion and live B1 vaccines.     

W W Robertson  D Warden  I G Furminger 《The Veterinary record》1976,98(1):14-15

  相似文献