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排序方式: 共有133条查询结果,搜索用时 15 毫秒
1.
Model uncertainty in the ecosystem approach to fisheries 总被引:2,自引:0,他引:2
Simeon L. Hill George M. Watters ré E. Punt Murdoch K. McAllister Corinne Le Quéré John Turner 《Fish and Fisheries》2007,8(4):315-336
Fisheries scientists habitually consider uncertainty in parameter values, but often neglect uncertainty about model structure, an issue of increasing importance as ecosystem models are devised to support the move to an ecosystem approach to fisheries (EAF). This paper sets out pragmatic approaches with which to account for uncertainties in model structure and we review current ways of dealing with this issue in fisheries and other disciplines. All involve considering a set of alternative models representing different structural assumptions, but differ in how those models are used. The models can be asked to identify bounds on possible outcomes, find management actions that will perform adequately irrespective of the true model, find management actions that best achieve one or more objectives given weights assigned to each model, or formalize hypotheses for evaluation through experimentation. Data availability is likely to limit the use of approaches that involve weighting alternative models in an ecosystem setting, and the cost of experimentation is likely to limit its use. Practical implementation of an EAF should therefore be based on management approaches that acknowledge the uncertainty inherent in model predictions and are robust to it. Model results must be presented in ways that represent the risks and trade‐offs associated with alternative actions and the degree of uncertainty in predictions. This presentation should not disguise the fact that, in many cases, estimates of model uncertainty may be based on subjective criteria. The problem of model uncertainty is far from unique to fisheries, and a dialogue among fisheries modellers and modellers from other scientific communities will therefore be helpful. 相似文献
2.
Bréard E Sailleau C Coupier H Mure-Ravaud K Hammoumi S Gicquel B Hamblin C Dubourget P Zientara S 《Veterinary research》2003,34(6):777-789
Bluetongue (BT) virus serotype 2 (BTV 2) was first confirmed in Tunisia in February 2000 and has since spread northward and westward, infecting several other countries and islands, including Corsica, where clinical disease was reported in October 2000. BT was again reported on the Island in July 2001, some six months after a vaccination campaign against BTV 2. The molecular relationship between isolates of the BTV 2 Corsican wild-type viruses from 2000 and 2001, and the attenuated BTV 2 vaccine were determined by comparing corresponding sequences of genome segments 2, 7 and 10 with each other and with already published sequences available in the genome database. Complete genetic stability was observed between the isolates of the Corsican BTV 2. There was some divergence between the nucleotide sequences of segment 10 obtained from the wild-type and vaccine virus strains. Based on these differences, primers were selected that could be used in RT-PCR to differentiate between the wild-type and the vaccine viruses. 相似文献
3.
Agroforestry has been suggested to produce an array of ecological and socio-economic benefits that not only reach their adopters, but society as a whole. In spite of strong evidence of the benefits of agroforestry, there is a lack of understanding of the public perceptions of those benefits, which prevents the development of benefit-based promotion strategies of agroforestry products. Thus, this study examines the awareness of these benefits among residents and explores whether perceptions vary across individuals with different socio-demographic characteristics. An on-line platform was used to survey three panels of residents from Missouri, Pennsylvania and Texas. Overall, respondents had a neutral perception of the importance of the ecological and socio-economic benefits that agroforestry farms provide to society when compared to farms employing conventional agricultural practices. These results stress the need to increase public awareness of agroforestry practices and their benefits to more strategically position their products among the final consumer. Gender, education level, and residence location were significantly associated with the perceived ecological benefits produced by agroforestry farms and to a lesser extent with the socio-economic benefits. Results also showed that females and young individuals have a greater awareness of several benefits produced by agroforestry farms. Critical marketing implications to stimulate the purchase of agroforestry products (e.g., berries, nuts) among specific groups of consumers are discussed. 相似文献
4.
Claire Laugier Jackie TapprestNathalie Foucher BSc Corinne Sevin BSc 《Journal of Equine Veterinary Science》2009
The frequencies of neurologic diseases and various corresponding causes were analyzed in 4,319 Norman horses examined by autopsy between 1986 and 2006. Five hundred forty-three cases of nervous system disorders were detected, or a total prevalence of 12.6%. One hundred eighty-seven of the 543 horses (34.4%) exhibited lesions of a traumatic origin affecting the skull or the vertebral column at different levels. Their frequency was less in foals younger than 1 month of age and higher in horses aged 6 months to 2 years. Eighty-three cases of cervical vertebral compressive myelopathy (CVCM) (15.3%) were identified. Males and geldings were more often affected than females. CVCM was diagnosed mostly in animals aged 6 months to 2 years. Horses affected with lesions in the mid-cervical region (region C3–C5) were significantly younger than those exhibiting more caudal lesions (region C5–C7). Neonatal maladjustment syndrome was diagnosed in 62 foals younger than 3.5 days (4.8% of the causes of death between birth and 1 month) by using clinical or lesional criteria. The prevalence was higher in Thoroughbreds as well as in the miscellaneous breed category and less in French Standardbreds. Bacterial meningoencephalomyelitis and meningitis represented 9.6% of nervous system disorders (52 cases) and most often affected foals aged 1 to 6 months. The main bacteria identified were beta-hemolytic Streptococci , Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, and Actinobacillus sp. The other causes diagnosed were, in decreasing order of frequency: grass sickness or equine dysautonomia (6.3% of neurologic diseases), hepatic encephalopathy syndrome (5.2%), septic vertebral arthritis or osteitis mainly caused by Rhodococcus equi (2.6%), congenital defects of the nervous system (2.4%), equine herpesvirus 1 myeloencephalopathy (2.2%), botulism (2.2%), malformations of the vertebral column other than CVCM (2%), and neighboring polyneuritis associated with guttural pouch mycosis (1.5%). 相似文献
5.
Charles R. Sweet Giancarlo M. Alpuche Corinne A. Landis Benjamin C. Sandman 《Marine drugs》2014,12(7):4126-4147
Lipid A is the essential component of endotoxin (Gram-negative lipopolysaccharide), a potent immunostimulatory compound. As the outer surface of the outer membrane, the details of lipid A structure are crucial not only to bacterial pathogenesis but also to membrane integrity. This work characterizes the structure of lipid A in two psychrophiles, Psychromonas marina and Psychrobacter cryohalolentis, and also two mesophiles to which they are related using MALDI-TOF MS and fatty acid methyl ester (FAME) GC-MS. P. marina lipid A is strikingly similar to that of Escherichia coli in organization and total acyl size, but incorporates an unusual doubly unsaturated tetradecadienoyl acyl residue. P. cryohalolentis also shows structural organization similar to a closely related mesophile, Acinetobacter baumannii, however it has generally shorter acyl constituents and shows many acyl variants differing by single methylene (-CH2-) units, a characteristic it shares with the one previously reported psychrotolerant lipid A structure. This work is the first detailed structural characterization of lipid A from an obligate psychrophile and the second from a psychrotolerant species. It reveals distinctive structural features of psychrophilic lipid A in comparison to that of related mesophiles which suggest constitutive adaptations to maintain outer membrane fluidity in cold environments. 相似文献
6.
Corinne Valdivia M. Kengo Danda Dekha Sheikh Harvey S. James Jr. Violet Gathaara Grace Mbure Festus Murithi William Folk 《Agriculture and Human Values》2014,31(4):673-681
Genetically modified (GM) cassava is currently being developed to address problems of diseases that threaten the food security of farmers in developing countries. The technologies are aimed at smallholder farmers, in hopes of reducing the vulnerability of cassava production to these diseases. In this paper we examine barriers to farmers’ voice in the development of GM cassava. We also examine the role of a translational research process to enhance farmers’ voice, to understand the sources of vulnerability farmers in a group in Kenya’s Coast face, and to determine if their concerns are consistent with those of the scientists in agriculture addressing farmers’ needs. A two-way communication participatory process provided insights into the complex vulnerability context of farmers, their primary concerns with processing and markets of cassava in order to improve livelihoods, the lack of networks with two way communication flows, and the lack of information on GM technologies. The translational research engaged farmers and scientists in an iterative process where scientists are learning what farmers need, and farmers are learning about the potential benefits and risks from GM technologies, while at the same time expressing their concerns. 相似文献
7.
Jér?me?MathieuEmail author Jean-Pierre?Rossi Michel?Grimaldi Philippe?Mora Patrick?Lavelle Corinne?Rouland 《Biology and Fertility of Soils》2004,40(5):300-305
The influence of three spatially hierarchical factors upon soil macrofauna biodiversity was studied in four pasture plots in eastern Amazonia. The first factor was the local depth of the soil. The second factor was the ground cover type on the soil samples (bare ground, grass tufts, dead trees lying on the ground). The third factor was the dimensions of the grass tufts sampled (size and shape). The effect of each factor upon the morphospecies richness and density of total soil macrofauna was analysed. Detailed results are given for earthworms, termites, ants, beetles and spiders. All factors significantly affected the morphospecies richness and/or density of the soil macrofauna. The type of ground cover had the strongest influence, affecting the total richness and density of the soil macrofauna and of almost all the groups represented. The soil depth affected only the density of the termites and the global morphospecies richness. Interactions between soil depth and ground cover type affected the total macrofauna morphospecies richness and the density of the earthworms. The dimensions of the grass tuft influenced the global morphospecies richness, the morphospecies richness of the ants and the density of the spiders. 相似文献
8.
9.
Major declines in the abundance of vultures and other scavenging raptors in and around the Masai Mara ecosystem, Kenya 总被引:1,自引:0,他引:1
Munir Z. Virani Corinne Kendall Peter Njoroge Simon Thomsett 《Biological conservation》2011,(2):746-752
Vulture population declines have been noted in West and Southern Africa, but have not been assessed in East Africa. Roadside transects conducted in 1976 and 1988 were compared with surveys done from 2003–2005 in and around Masai Mara National Reserve, Kenya. Staggering declines in abundance were found for seven of eight scavenging raptors surveyed. No Egyptian vultures were seen during recent transects. We compared trends between the ungulate migration and non-migration season among three land use types (reserve, buffer, and grazed) and among the species surveyed to establish the causes of declines in scavenging raptors. Large declines during the ungulate migratory period suggest that most scavenging raptor species are declining well beyond the area of study. For all species, except Hooded vultures, substantial declines outside of the reserve indicate an important role of land use change in causing observed declines. In addition, significant declines of populations of Gyps species in the reserve itself, especially during the migration season, provide evidence that human activities occurring in other parts of the species’ range such as poisoning of carcasses may be causing their decline. Declines found in this study suggest that at a minimum African white-backed, Rüppell’s, and Hooded vultures should be relisted as Vulnerable. Management actions that limit land use change around the reserve combined with a countrywide ban on carbamate pesticides will be important for conserving keystone members of the scavenging guild. Future research should further examine possible causes of these declines and quantify the effect of reduced scavenging raptor abundance on scavenging efficiency. 相似文献
10.
Mycorrhizae are ubiquitous symbiosis which can mediate uptake of some plant nutrients. In polluted soils they could be of great importance in heavy metal availability and toxicity to plants. Mycorrhizae have also been reported to protect plants against toxic metals. We investigated the occurrence and infectivity of arbuscular mycorrhizal (AM) spores as affected by heavy metal levels and other soil properties in Norwegian soils collected from heavy metal polluted, high natural background and non-polluted areas. Spore numbers, mycorrhizal infectivity and spore germination of indigenous mycorrhizal fungi and of a reference strain (Glomus mosseae) in soils showed lower values in two soils with high metal concentrations and in one soil with a low pH. Mycorrhizal infectivity was negatively correlated with extractable metals. Spore number and mycorrhizal infectivity in a soil with naturally high heavy metal content were not different to in non-polluted soils, and indigenous AM fungi appeared more tolerant to metals than those in non-polluted soils. Mycorrhizal infectivity, expressed as MSI50 values, was significantly correlated (r′=0.89, P< 0.05) with the percentage of germinating G. mosseae spores in the soils. However, the number of spores per volume of soil was not significantly correlated with infectivity or spore germination of the reference strain. The spore germination method is discussed as a bioassay of heavy metal toxicity in soil. 相似文献