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排序方式: 共有509条查询结果,搜索用时 31 毫秒
71.
Christopher J. Fulton Charlotte Berkstrm Shaun K. Wilson Rene A. Abesamis Michael Bradley Carolina kerlund Luke T. Barrett Abner A. Bucol Dinorah H. Chacin Karen M. Chong‐Seng Darren J. Coker Martial Depczynski Linda Eggertsen Maria Eggertsen David Ellis Richard D. Evans Nicholas A. J. Graham Andrew S. Hoey Thomas H. Holmes Michel Kulbicki Priscilla T. Y. Leung Paul K. S. Lam Joshua van Lier Paloma A. Matis Mae M. Noble Alejandro Prez‐Matus Camilla Piggott Ben T. Radford Stina Tano Paul Tinkler 《Fish and Fisheries》2020,21(4):700-717
Canopy‐forming macroalgae can construct extensive meadow habitats in tropical seascapes occupied by fishes that span a diversity of taxa, life‐history stages and ecological roles. Our synthesis assessed whether these tropical macroalgal habitats have unique fish assemblages, provide fish nurseries and support local fisheries. We also applied a meta‐analysis of independent surveys across 23 tropical reef locations in 11 countries to examine how macroalgal canopy condition is related to the abundance of macroalgal‐associated fishes. Over 627 fish species were documented in tropical macroalgal meadows, with 218 of these taxa exhibiting higher local abundance within this habitat (cf. nearby coral reef) during at least one life‐history stage. Major overlap (40%–43%) in local fish species richness among macroalgal and seagrass or coral reef habitats suggest macroalgal meadows may provide an important habitat refuge. Moreover, the prominence of juvenile fishes suggests macroalgal meadows facilitate the triphasic life cycle of many fishes occupying diverse tropical seascapes. Correlations between macroalgal canopy structure and juvenile abundance suggests macroalgal habitat condition can influence levels of replenishment in tropical fish populations, including the majority of macroalgal‐associated fishes that are targeted by commercial, subsistence or recreational fisheries. While many macroalgal‐associated fishery species are of minor commercial value, their local importance for food and livelihood security can be substantial (e.g. up to 60% of landings in Kenyan reef fisheries). Given that macroalgal canopy condition can vary substantially with sea temperature, there is a high likelihood that climate change will impact macroalgal‐associated fish and fisheries. 相似文献
72.
Yu Zhang Beth A Lorsbach Scott Castetter William T Lambert Jeremy Kister Nick X Wang Carla J R Klittich Joshua Roth Thomas C Sparks Mike R Loso 《Pest management science》2018,74(9):1979-1991
The relentless need for the discovery and development of new agrochemicals continues as a result of driving forces such as loss of existing products through the development of resistance, the necessity for products with more favorable environmental and toxicological profiles, shifting pest spectra, and the changing agricultural needs and practices of the farming community. These new challenges underscore the demand for novel, high‐quality starting points to accelerate the discovery of new agrochemicals that address market challenges. This article discusses the efforts to identify the optimum ranges of physicochemical properties of agrochemicals through analysis of modern commercial products. Specifically, we reviewed literature studies examining physicochemical property effects and analyzed the properties typical of successful fungicides, herbicides, and insecticides (chewing and sap‐feeding pests). From the analysis, a new set of physicochemical property guidelines for each discipline, as well as building block class, are proposed. These new guidelines should significantly aid in the discovery of next‐generation agrochemicals. © 2018 Society of Chemical Industry 相似文献
73.
74.
Contemporary soil organic matter (SOM) models have been successful at simulating decomposition across a range of spatial and temporal scales using first-order kinetics to represent the decomposition process; however, recent work suggests the simplicity of the first-order representation of decomposition is not adequate to capture the microbially-driven dynamics of SOM decomposition over short timescales. For example, the response of soils to drying-rewetting events may best be explained by microbial and/or exoenzyme controls on decomposition. To test if adding these microbial mechanisms improves the ability of SOM models to simulate the response of soils to short-term environmental changes, we developed four different SOM decomposition models with varying mechanistic complexity and compared their ability to simulate soil respiration from a pulsed drying-rewetting laboratory-based experiment. Specifically, we tested the ability of the models to capture the timing and magnitude of soil CO2 efflux in response to rewetting or constant moisture conditions. The results of the comparison suggest that the inclusion of exoenzyme and microbial controls on decomposition can improve the ability to simulate pulsed rewetting dynamics; however, less mechanistic first-order models prevail under steady-state moisture conditions. These modeling results may have implications for understanding the long-term response of soil carbon stocks in response to local and regional climate change. 相似文献
75.
Emmanuel Senyael Swai A. Kapaga F. Kivaria D. Tinuga G. Joshua P. Sanka 《Veterinary research communications》2009,33(8):927-936
Despite the widespread prevalence of infection with Peste des petits ruminants virus (PPRV) in goats and sheep industry in
Asia and sub-Saharan Africa, there have been few, if any, structured population-based studies examining the epidemiology of
this infection in Tanzania. In this study, we investigated the seroprevalence, and risk factors, of Peste des petitis ruminants(PPR)
in sheep and goat flocks from seven different geographical administration authorities (Ngorongoro, Monduli, Longido, Karatu,
Mbulu, Siha and Simanjiro) located in Northern Tanzania. Serum samples from 657 and 892 sheep and goats, respectively, corresponding
to 91 sheep/goat flocks and 43 villages were collected. Competitive enzyme linked immunosorbent assay (c-ELISA) was used to
detect the presence of antibodies in the serum against PPRV. Chi-square analysis and multivariable logistic regression model
were used to identify risk factors for PPRV seropositivity. Findings suggested that the sero-positive cases were significantly
higher in goats than in sheep (49.5% versus 39.8%; P = 0.002). The overall seroprevalence of PPRV infection in small ruminants
was 45.8%. Highest seroprevalence (42.6–88.02%) was observed in Mbulu, Siha, Longido, Ngorongoro districts, while antibodies
less than 40% to none were found in serum from Monduli, Karatu and Simanjiro, respectively. These findings confirm natural
transmission of PPRV under field condition for the first time in Tanzania. Results may be correlated with variations in the
sheep and goat husbandry practices within different geographic localities, the uncontrolled movement of animals, the levels
of natural immunity and the sharing of grazing field amongst agro and pastoralists. 相似文献
76.
Dietary supplementation with Acanthopanax senticosus extract enhances gut health in weanling piglets
Jun Fang F.Y. Yan X.F. Kong Z. Ruan Z.Q. Liu R.L. Huang T.J. Li M.M. Geng F. Yang Y.Z. Zhang Peng Li Joshua Gong G.Y. Wu M.Z. Fan Y.L. Liu Y.Q Hou Y.L. Yin 《Livestock Science》2009,123(2-3):268-275
The present study was conducted to investigate the effects of Acanthopanax senticosus extract (ASE) as a dietary additive on gut health in weanling piglets by examining diarrhea frequency, intestinal microbiota and morphology. A total of 96 Duroc× (Landrace × Yorkshire) piglets weaned at 21 days of age with an average initial body weight (BW) of 5.6 ± 0.4 kg were randomly assigned to 3 treatment groups with 4 duplicates of 8 piglets each. The piglets were fed basal diet to which had been added 0 or 1 g/kg of ASE, or 0.7 g/kg antibiotics, respectively. Fecal consistence was monitored twice daily and the frequency of diarrhea was calculated. On day 21 after the initiation of supplementation, 8 piglets were randomly selected from each treatment group (2 piglets per pen) and slaughtered. The jejunum, ileum, colon and cecum were then excised and fixed in 10% neutral formalin solution to determine villus height and crypt depth, after their contents were collected to determine microbiota. The results showed that dietary supplementation with ASE increased (P < 0.05) the density of bacterial populations that co-migrated with Lactobacillus amylovorus, Lactobacillus salivarius, Bacillus subtilis, and Clostridium lituseburens, but decreased (P < 0.05) those co-migrating with Staphylococcus aureus, Salmonella typhimurium, Ruminococcus forques, and E. coli O157:H7 in the PCR-DGGE profiling analysis when compared with the control group. The villus height of the duodenum, jejunum and ileum increased (P < 0.05) by 14.8, 13.7 and 10.0%, while the crypt depth decreased (P < 0.05) by 17.9, 9.1 and 12.1%, respectively, in response to dietary ASE supplementation. Additionally dietary supplementation with ASE or an antibiotic decreased (P < 0.05) the frequency of diarrhea by 55.6 and 52.2%, respectively, compared with the control group. In conclusion, these findings suggest that dietary supplementation with ASE could regulate the microbiota composition and maintain a normal morphology of gut mucosa in weanling piglets, thereby decreasing diarrhea that resulted from weaning stress. 相似文献
77.
Hal O. Liechty Michael A. Blazier Jason P. Wight Lewis A. Gaston Joshua D. Richardson Robert L. Ficklin 《Forest Ecology and Management》2009
The Southeastern United States has a robust broiler industry that generates substantial quantities of poultry litter as waste. It has historically been applied to pastures close to poultry production facilities, but pollution of watersheds with litter-derived phosphorus and to a lesser extent nitrogen have led to voluntary and in some areas regulatory restrictions on application rates to pastures. Loblolly pine (Pinus taeda L.) forests are often located in close proximity to broiler production facilities, and these forests often benefit from improved nutrition. Accordingly, loblolly pine forests may serve as alternative land for litter application. However, information on the influence of repeated litter applications on loblolly pine forest N and P dynamics is lacking. Results from three individual ongoing studies were summarized to understand the effects of repeated litter applications, litter application rates, and land use types (loblolly pine forest and pasture) on N and P dynamics in soil and soil water. Each individual study was established at one of three locations in the Western Gulf Coastal Plain region. Annual applications of poultry litter increased soil test P accumulation of surface soils in all three studies, and the magnitude of increase was positively and linearly correlated with application rates and frequencies. In one study that was established at a site with relatively high soil test P concentrations prior to poultry litter application, five annual litter applications of 5 Mg ha−1 and 20 Mg ha−1 also increased soil test P accumulation in subsurface soils to a depth of up to 45 cm. Soil test P accumulations were greater in surface soils of loblolly pine stands than in pastures when both land use types received similar rates of litter application. In one study which monitored N dynamics, lower soil organic N, potential net N mineralization, potential net nitrification, and soil water N was found in loblolly pine stands than pastures after two annual litter applications. However, increases in potential net N mineralization, net nitrification, and soil water N with litter application were more pronounced in loblolly pine than in pasture soils. Loblolly pine plantations can be a viable land use alternative to pastures for poultry litter application, but litter application rate and frequency as well as differences in nutrient cycling dynamics between pine plantations and pastures are important considerations for environmentally sound nutrient management decisions. 相似文献
78.
79.
This article examined relationships among hunter perceptions of personal health risks from chronic wasting disease (CWD), knowledge and information about CWD, and perceptions of other hunting, wildlife, and health risks. Data were obtained from surveys of 2,725 deer and elk hunters in Colorado. Cluster analysis grouped hunters into no (42%), slight (44%), and moderate (14%) risk groups based on perceptions of personal health risks from CWD (e.g., concern about health, become ill from CWD). There were minimal differences among groups in demographics, information sources, and knowledge about CWD. Hunters who perceived higher health risks from CWD (i.e., moderate risk), however, perceived greater risks associated with CWD to other humans, CWD to wildlife, hunting to personal health, other diseases to health, and the future of hunting. These findings illustrated the concept of risk sensitivity where hunters who perceived higher risks from CWD were predisposed to rate all other risks as large. 相似文献
80.
Yuanchun Yu Jingyu Yang Shucai Zeng Daoming Wu Douglass F. Jacobs Joshua L. Sloan 《Journal of Soils and Sediments》2017,17(9):2230-2238