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排序方式: 共有551条查询结果,搜索用时 562 毫秒
321.
David W. Watkins Jr. Márcia M. G. Alcoforado de Moraes Heidi Asbjornsen Alex S. Mayer Julian Licata Jose Gutierrez Lopez Thomas G. Pypker Vivianna Gamez Molina Guilherme Fernandes Marques Ana Cristina Guimaraes Carneiro Hector M. Nuñez Hayri Önal Bruna da Nobrega Germano 《Environmental management》2015,56(6):1295-1314
322.
323.
Aquaculture studies have revealed that polyunsaturated fatty acids are critical for maintaining substantial growth, survival
and reproductive rates, and high food conversion efficiencies for a wide variety of marine and freshwater organisms. The aim
of this study was to investigate the gross biochemical and fatty acid composition of both neutral and polar lipid compartments
of the razor clam Solen marginatus throughout embryonic and larval development. High levels of stored reserves in S. marginatus eggs allow a short larval development, lasting only 8 days. The energy required for embryogenesis was obtained from stored
proteins. During larval development from D-shaped veliger until settlement, protein, lipid, and carbohydrate reserves were
indistinctly stored for metamorphosis. Although total lipids increased, fatty acids in both neutral and polar lipids decreased
during embryonic development. The depots allow a short larval development in which settlement is reached with lower amounts
of stored neutral and polar lipids than the contents found in the oocytes. Non-methylene-interrupted dienoic fatty acid levels
were similar to those of some polyunsaturated fatty acids, with increasing percentages at the onset of metamorphosis. This
study indicates that S. marginatus exhibits a different pattern in the use of gross biochemical and fatty acid reserves during larval development compared to
other razor clam and bivalve species, mainly due to the large size of its eggs and the short larval development stage reported
in this species. 相似文献
324.
Patricia N. Pochelon Teresa Lopes da Silva Alberto Reis Antonina dos Santos Henrique Queiroga Ricardo Calado 《Marine Biology》2011,158(12):2825-2833
The present study investigated the existence of inter-individual and within-brood variability in the fatty acid (FA) profile
of developing embryos of Nephrops norvegicus. In all surveyed females (n = 5), the quantitatively most important FAs were as follows: 22:6n-3 (20.8 ± 3.9% average of total FA ± standard error),
18:1n-9 (19.5 ± 2.0%), 16:0 (15.2 ± 3.4%), 20:5n-3 (10.2 ± 1.4%), 16:1n-7 (8.9 ± 1.6%), and 18:1n-7 (5.7 ± 1.3%). Differences
in FA profiles of embryos in the same clutch were assessed using brooding chamber side (left and right) and pleopod (1st and
2nd, 3rd and 4th, and 5th) as predictive factors. There were no significant differences in the FA composition of embryos sampled
from both sides of the brooding chamber in 4 of the 5 surveyed females. However, all females exhibited significant differences
in the FA profiles of embryos sampled from different pleopods. Both saturated FA (SFA) and highly unsaturated FA (HUFA) present
in developing embryos exhibited marked differences along the breeding chamber. Overall, FA reserves appeared to vary significantly
within broods, which can ultimately be reflected on early larval survival. A potential cause for the within-brood variation
recorded in the FA profile of developing embryos include (1) differential female investment during ovarian maturation, mainly
due to variation in food quality/availability; (2) differential lipid catabolism during the incubation period of developing
embryos, as a consequence of embryos position within the female’s brooding chamber; or (3) differential female investment
during ovarian maturation amplified by differential lipid catabolism during the incubation period. 相似文献
325.
Mercury and methyl mercury ratios in caimans (Caiman crocodilus yacare) from the Pantanal area, Brazil 总被引:1,自引:0,他引:1
Vieira LM Nunes Vda S Amaral MC Oliveira AC Hauser-Davis RA Campos RC 《Journal of environmental monitoring : JEM》2011,13(2):280-287
The Pantanal region is the largest floodplain area in the world and of great biological importance due to its unique flora and fauna. This area is continuously undergoing increasing anthropogenic threats, and has also experienced mercury contamination associated with gold mining and other anthropogenic activities. Pantanal caimans are top-level predators, and, as such, show great potential to accumulate mercury (Hg) by biomagnification. In this study 79 specimens from four locations in the Pantanal were analyzed for total Hg and methyl mercury (MeHg) by cold vapor atomic absorption spectrometry. Total Hg contents ranged from 0.02 to 0.36 μg g(-1) (ww), and most specimens presented MeHg ratios above 70%. One of the sites, impacted by anthropogenic activities, presented significantly higher total Hg in comparison to three less impacted sites, supporting the hypothesis that caimans can, in fact, be considered effective bioindicators of ecosystem health. 相似文献
326.
Seed dispersal is a crucial component of plant population dynamics. Human landscape modifications, such as habitat destruction and fragmentation, can alter the abundance of fruiting plants and animal dispersers, foraging rates, vector movement, and the composition of the disperser community, all of which can singly or in concert affect seed dispersal. Here, we quantify and tease apart the effects of landscape configuration, namely, fragmentation of primary forest and the composition of the surrounding forest matrix, on individual components of seed dispersal of Heliconia acuminata, an Amazonian understory herb. First we identified the effects of landscape configuration on the abundance of fruiting plants and six bird disperser species. Although highly variable in space and time, densities of fruiting plants were similar in continuous forest and fragments. However, the two largest-bodied avian dispersers were less common or absent in small fragments. Second, we determined whether fragmentation affected foraging rates. Fruit removal rates were similar and very high across the landscape, suggesting that Heliconia fruits are a key resource for small frugivores in this landscape. Third, we used radiotelemetry and statistical models to quantify how landscape configuration influences vector movement patterns. Bird dispersers flew farther and faster, and perched longer in primary relative to secondary forests. One species also altered its movement direction in response to habitat boundaries between primary and secondary forests. Finally, we parameterized a simulation model linking data on fruit density and disperser abundance and behavior with empirical estimates of seed retention times to generate seed dispersal patterns in two hypothetical landscapes. Despite clear changes in bird movement in response to landscape configuration, our simulations demonstrate that these differences had negligible effects on dispersal distances. However, small fragments had reduced densities of Turdus albicollis, the largest-bodied disperser and the only one to both regurgitate and defecate seeds. This change in Turdus abundance acted together with lower numbers of fruiting plants in small fragments to decrease the probability of long-distance dispersal events from small patches. These findings emphasize the importance of foraging style for seed dispersal and highlight the primacy of habitat size relative to spatial configuration in preserving biotic interactions. 相似文献
327.
Alice Bosco-Santos Wanilson Luiz-Silv Emmanoel Vieira da Silva-Filho Monique Dias Corrêa de Souz Elton Luiz Dantas Margareth Sugano Navarro 《环境科学学报(英文版)》2017,29(4):69-76
Fractionation of rare earth elements (REE) and other trace metal concentrations (Th, U, Cd, Cr, Cu, Ni, Pb, and Zn) between mangrove sediments and claw muscles and shells of male crabs (Ucides cordatus) from a subtropical estuary highly impacted by fertilizer industry activities was investigated. This is the first record of REE distribution in these organisms, and the results showed higher accumulations of these metals, U and Th in shells, probably related to the replacement of Ca during molting. Contents of Cd, Cr and Ni were similar in both tissues, but Cu, Zn and Pb were mostly accumulated in the claw muscle with concentrations above those considered safe for human consumption according to the Brazilian legislation. REE fractionation was different in the analyzed tissues being softer in the shells. The results provided evidences that the water absorbed during molting controls the chemistry of REE in shells. In contrast, the chemistry of REE in the claw muscle, in which was observed preferential absorption of light REE, is controlled by diet. REE fractionation obtained for the claw muscles was closely correlated to the observed in the contaminated substrate and in materials related to the production of phosphate fertilizers (contamination source), which supports their transference to this Ucides cordatus tissue without fractionation by the ingestion of sediments. Our results showed the potential use of crab tissues for monitoring REE and trace element sources in mangrove areas, with claw muscle exhibiting the contaminant source fingerprint. 相似文献
328.
da Silva Vilaine Corrêa Elois Mariana Savi Beatriz Pereira Miotto Marília De Dea Lindner Juliano Fongaro Gislaine Souza Doris Sobral Marques 《Food and environmental virology》2023,15(1):1-7
Food and Environmental Virology - Oysters are filter-feeders and retain sewage-derived pathogens in their organs or tissues. Since most enteric viruses involved in outbreaks cannot grow in cell... 相似文献
329.
Hipolito Victor Leibnitz Amorim Vanessa Amorim Gleize Philippe Jean Paul Girotto Edivandro Jnior Amrico Cruz Benavides Roberto Sanchez Saul da Silva Luciano Magnago Rachel Faverzani 《Journal of Material Cycles and Waste Management》2022,24(2):452-465
Journal of Material Cycles and Waste Management - In this article, we present the results of the composite development obtained from polyurethane (PU), polyvinyl chloride (PVC), and aluminum... 相似文献
330.
Roque António José da Silva Paula F. de Almeida Rui Pedro Marques 《Journal of Material Cycles and Waste Management》2022,24(6):2385-2400
Journal of Material Cycles and Waste Management - A crushed concrete aggregate, processed from construction and demolition waste and a siderurgical aggregate, processed from electric arc furnace... 相似文献