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排序方式: 共有1408条查询结果,搜索用时 15 毫秒
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Michel Grimaldi Johan Oszwald Sylvain Dolédec Maria del Pilar Hurtado Izildinha de Souza Miranda Xavier Arnauld de Sartre William Santos de Assis Edna Castañeda Thierry Desjardins Florence Dubs Edward Guevara Valery Gond Tâmara Thaiz Santana Lima Raphaël Marichal Fernando Michelotti Danielle Mitja Norberto Cornejo Noronha Mariana Nascimento Delgado Oliveira Bertha Ramirez Gamaliel Rodriguez Max Sarrazin Mário Lopes da Silva Jr. Luiz Gonzaga Silva Costa Simão Lindoso de Souza Iran Veiga Elena Velasquez Patrick Lavelle 《Landscape Ecology》2014,29(2):311-328
Landscape dynamics result from forestry and farming practices, both of which are expected to have diverse impacts on ecosystem services (ES). In this study, we investigated this general statement for regulating and supporting services via an assessment of ecosystem functions: climate regulation via carbon sequestration in soil and plant biomass, water cycle and soil erosion regulation via water infiltration in soil, and support for primary production via soil chemical quality and water storage. We tested the hypothesis that patterns of land-cover composition and structure significantly alter ES metrics at two different scales. We surveyed 54 farms in two Amazonian regions of Brazil and Colombia and assessed land-cover composition and structure from remote sensing data (farm scale) from 1990 to 2007. Simple and well-established methods were used to characterize soil and vegetation from five points in each farm (plot scale). Most ES metrics were significantly correlated with land-use (plot scale) and land-cover (farm scale) classifications; however, spatial variability in inherent soil properties, alone or in interaction with land-use or land-cover changes, contributed greatly to variability in ES metrics. Carbon stock in above-ground plant biomass and water infiltration rate decreased from forest to pasture land covers, whereas soil chemical quality and plant-available water storage capacity increased. Land-cover classifications based on structure metrics explained significantly less ES metric variation than those based on composition metrics. Land-cover composition dynamics explained 45 % (P < 0.001) of ES metric variance, 15 % by itself and 30 % in interaction with inherent soil properties. This study describes how ES evolve with landscape changes, specifying the contribution of spatial variability in the physical environment and highlighting trade-offs and synergies among ES. 相似文献
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John Zachary Koehn Edward H Allison Karen Villeda Zelin Chen Marisa Nixon Emily Crigler Lily Zhao Michelle Chow Bapu Vaitla Shakuntala H Thilsted Joeri Scholtens Christina C Hicks Neil Andrew 《Fish and Fisheries》2022,23(1):125-142
Aquatic foods are rich in micronutrients essential to human health, and fisheries and aquaculture are increasingly recognized for their capacity to contribute to reducing global micronutrient deficiencies and diet-based health risks. Whether fisheries and aquaculture sector and public health nutrition policies align to meet this goal, however, is unclear. Do fisheries and aquaculture policies have explicit nutrition and public health objectives? Do public health nutrition policies recognize the contribution of aquatic foods? Using content analysis, we assessed the alignment of objectives in national fisheries and public health nutrition policies. We further determined conditions associated with varying levels of cohesion among policies in these sectors or domains. We found that 77 of 158 national fisheries policies identified nutrition as a key objective in the sector, and 68 of 165 public health nutrition policies identified the importance of fish and shellfish consumption as key objectives. More recent policies were associated with improved coherence among sectors. International organization presence in policy development was also associated with greater coherence. Countries with higher overweight prevalence had fisheries and public health nutrition policies that were not aligned. There has been a promising recent trend for improved alignment of objectives between fisheries and public health nutrition policies, but more targeted and systematic policy approaches are needed to realize the potential contribution of nutrient-rich fish and shellfish to healthier food systems. 相似文献
995.
Edward Pfeiler 《Fish physiology and biochemistry》1993,12(2):143-148
Undersulfated chondroitin sulfate (i.e., chondroitin sulfate with sulfate: hexosamine molar ratios ranging from 0.06–0.17) has been identified as a principal glycosaminoglycan
(GAG) in whole-body extracts of leptocephalous larvae of four species of marine teleost fishes, representing two orders and
three families. These include the eels (Anguilliformes)Ariosoma balearicum (Congridae),Rhechias dubia (Congridae) and Ophichthus sp. (Ophichthidae) and the ladyfish (Elopiformes: Elopidae: Elops saurus). A second GAG found in relatively large amounts in A. balearicum has been identified as chondroitin. Chondroitin and undersulfated chondroitin sulfate formed distinctive precipitates during
extraction and were easily separated. Undersulfated chondroitin sulfate also was extracted and purified from early metamorphosing
bonefish (Albuliformes: Albulidae: Albula sp.) leptocephali, where it is a minor GAG component, and was shown to be similar in composition to the compounds obtained
from eels and ladyfish. 相似文献
996.
Edward J. Kennedy Shawn M. C. Robinson G. Jay Parsons John D. Castell 《Journal of the World Aquaculture Society》2007,38(1):36-48
This study investigated the effects of dietary minerals and pigments in prepared diets on the somatic growth performance of wild and hatchery‐reared juvenile green sea urchins, Strongylocentrotus droebachiensis, by two feeding trials. In the first feeding trial, a modified Bernhart‐Tomerelli salt mix (BT) at 0, 1.5, 3, 6, and 15% dry mass and a Shur‐Gain/Maple Leaf Foods mineral mix at 3 and 6% dry mass were used to test for mineral effects. Pigment effects were tested by incorporating 1.25% Algro? to the prepared diets (i.e., 250 mg of beta‐carotene per kilogram of diet). Sea urchins (13–15 mm of initial test diameter [TD]) collected from the wild were fed the prepared diets over 154 d. The sea urchins that were fed the pigmented diets had significantly greater test growth than those fed the nonpigmented diets, and mineral concentration in the pigmented diets was directly related to juvenile size at the end of the feeding trial. A sample of juveniles from each treatment group was sacrificed to determine test, gonad, and gut yields and ash concentrations. Ash concentrations in the test and gonad were higher for juveniles fed pigmented diets than for those fed nonpigmented diets with similar mineral concentration, suggesting an interaction between minerals and pigments within the juvenile sea urchins. The second feeding trail used two size cohorts of hatchery‐reared juveniles ranging from 1–2 mm and 2–3 mm of initial TD to compare the growth of sea urchins fed either the pigmented diet with 15% BT (i.e., the best diet in the first feeding trial) or kelp, Laminaria longicruris, over 159 d. Growth performance was similar for both cohorts, indicating no size effect, but the juveniles fed the prepared diet were significantly larger at the end of the feeding trial than those fed kelp. This suggests that prepared diets with pigment and high mineral concentration can outperform kelp, and be utilized for juvenile green sea urchins to increase test growth. 相似文献
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999.
Equine embryo transfer 总被引:2,自引:0,他引:2
Current procedures for collection and transfer of equine embryos are presented. Factors affecting embryo recovery and pregnancy rates after transfer are discussed, and morphologic assessment and development of the embryo are described. 相似文献
1000.