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Richard H.M. Eertman Arco J. Wagenvoort Herman Hummel Aad C. Smaal 《Journal of experimental marine biology and ecology》1993,170(2):179-195
Mussels, Mytilus edulis, were exposed for periods of 6 weeks at various locations in Dutch coastal waters during 1989 and 1990. “Survival in air” showed to be a sensitive response parameter for indicating pollution induced environmental stress in transplanted mussels sampled from eight field sites. Increased tissue contaminant levels, especially PCBs and PAHs, correlated with a reduced survival time during aerial exposure. Three weeks exposure of mussels in the laboratory to 1 μg · 1−1 PCBs affected the aerial survival time negatively. Laboratory experiments did not indicate that lowered salinity influences the “Survival in air” response after sufficient acclimation (15 days), facilitating the use of this response parameter in both marine and estuarine waters. 相似文献
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S. Mays 《American journal of physical anthropology》2012,149(4):485-492
The age‐markers described at the adult acetabulum by Rissech et al. (J Forensic Sci 51 (2006) 213–229) were scored in the Spitalfields collection of skeletons of documented age and sex (N = 161). The purpose of the work was as a contribution to the evaluation of the general utility of these markers for estimating age at death. To this end, their relationship both with age, and with some other factors, was investigated. The latter comprised sex, general tendency toward bone formation in periarticular soft tissue (as measured by the occurrence of diffuse idiopathic skeletal hyperostosis), and occupation (as documented for some of the males). Of the seven Rissech et al. variables, only four were found to show a statistically significant relationship with age. The correlation between a composite score derived from a linear combination of these four variables, and age was similar to or greater than correlations between age and composite scores based on other age indicators reported in the literature for Spitalfields. Male acetabula aged at a greater rate than those of females. There was no relationship with the occurrence of DISH, but for occupation, those in nonmanual professions showed greater acetabular scores‐for‐age than those in manual trades. Am J Phys Anthropol 2012. © 2012 Wiley Periodicals, Inc. 相似文献
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Recent scholarship has revised the once pessimistic view of the Chinese economy in the late 19th and early 20th centuries, but controversy surrounds the distribution effects of economic growth. Did livelihoods improve? Who benefited from the growth? Which regions were better off? Past studies infer an improved standard of living based on sparse data for wages, the output of cotton textiles and movements in grain prices. Height data provide an additional measure of the change in welfare, specifically the biological standard of living. This paper draws on the health examination records conducted at various Chinese government enterprises and agencies during the 1930s and 1940s, and shows a modest improvement in this measure of human welfare in some regions of China from the 1890s to the 1920s. 相似文献
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R. GUERRIERI M. MENCUCCINI L. J. SHEPPARD M. SAURER M.P. PERKS P. LEVY M. A. SUTTON M. BORGHETTI J. GRACE 《Global Change Biology》2011,17(5):1946-1962
This study aimed to evaluate the effects of long‐term repeated aerial nitrogen (N) and sulphur (S) misting over tree canopies of a Sitka spruce plantation in Scotland. We combined δ13C and δ18O in tree rings to evaluate the changes in CO2 assimilation (A) and stomatal conductance (gs) and to assess their contribution to variations in the intrinsic water‐use efficiency (WUEi, i.e., the A/gs ratio). Measurements of δ15N enabled shifts in the ecosystem N cycling following misting to be assessed. We found that: (i) N applications, with or without S, increased the ratio between A and gs in favour of A, thus supporting a fertilizer effect of added N. (ii) After the treatments ceased, the trees quickly adjusted to the reductions of N deposition, but not to the reduction in S deposition, which had a negative effect on WUEi by reducing A. This indicates that the beneficial role of N deposition may be negated in forests that previously received a high load of acid rain. (iii) δ15N in tree rings reflected the N dynamics caused by canopy retention, with the fingerprint also present in the litter, after the experiment stopped. (iv) Both our results (obtained using canopy applications) and a collection of published data (obtained using soil applications) showed that generally WUEi increased in response to an increase of N applications, with the magnitude of the changes related to soil conditions and the availability of other nutrients. The shifts observed in δ15N in tree rings also suggest that both the quantity of the applied N and its quality, mediated by processes occurring during canopy N retention, are important determinants of the interactions between N and C cycles. Stable isotopes are useful probes to understand these processes and to put the results of short‐term experiments into context. 相似文献
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R. Bhatta S. Vaithiyanathan N.P. Singh A.K. Shinde D.L. Verma 《Small Ruminant Research》2005,60(3):273-280
A study was carried out to determine the effect of feeding different tree leaves as supplements on nutrient digestion, rumen fermentation and blood parameters of sheep grazing on a semi-arid rangeland. Thirty adult Malpura rams of uniform body weight (39.0 ± 0.75) were divided into five groups of six each. They were grazed as a single flock from 08.00 to 17.00 h on a semi-arid rangeland. After the end of the grazing period, the first group (G1), which was not provided with any supplementation, served as the control. The second group (G2) was supplemented with 200 g of a concentrate mixture per head per day, whereas the third, fourth and fifth groups (G3–G5) were provided with approximately 200 g DM d−1 of freshly cut foliage from Prosopis cineraria, Acacia nilotica and Albezia lebbek. The foliage from P. cineraria contained 133.4 g kg−1 DM condensed tannin (CT) with protein precipitating capacity (PPC) of 66 g kg−1 DM, whereas A. nilotica contained 18.9 g kg−1 DM hydrolysable tannin (HT) with PPC of 11.5 g kg−1 DM. However, A. lebbek did not contain any tannin. The protein contents were 119, 139 and 194 g kg−1 DM, respectively. The DMI (g d−1) was 688, 916, 1024, 1003, 999 in G1, G2, G3, G4 and G5, respectively. Digestible crude protein (DCP) and metabolizable energy (ME) intakes in supplemented groups G2–G5 were higher (P < 0.05) than in the control (G1). Supplementation improved the DM digestibility in all groups, whereas CP digestibility was lower (P < 0.05) in G3 compared to G2, G4 and G5. Rumen fermentation study conducted 6 h after supplementation revealed that total N, ammonia N, and total VFA levels were lower (P < 0.05) in G3 compared to the other supplemented groups. Although the haemoglobin (Hb) levels were similar among groups, blood urea N (BUN) was lowest in G3 compared to the other groups. The initial body weights were similar among groups (mean 39 kg). After 60 days of experimental feeding, all groups maintained their body weight, except the control group (G1), which lost body weight. It was observed, that supplementation with tree leaves containing CT like P. cineraria helps in better rumen fermentation pattern by preventing excessive loss of nitrogen. It was concluded that maximum nutritional benefits of tree leaves could be harvested, if used as supplement rather than as a sole feed. 相似文献
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Question: Is there a pattern in growth of annual rings in roots of perennial forbs in relation to climate and climate extremes in grassland ecosystems? Location: Semi‐arid grassland in Duolun (42°27′N, 116°41′E, 1380 m a.s.l.), central Inner Mongolia, China. Methods: Main roots of three perennial species, Potentilla anserina L., Cymbaria dahurica L. and Lespedeza daurica Schindl., were sampled. Cross‐sections (10–15‐μm thick) were produced from the proximal end of sampled roots using a sledge microtome. Annual growth rings in the main roots were identified and measured by differentiating between earlywood and latewood in the secondary xylem. Relationships between annual growth rings and monthly mean temperature and total monthly precipitation were identified using correlation analysis. Differences in an annual ring width to the previous and following years were examined by calculating a distinctness score. Results: The three perennial forbs showed clearly demarcated annual growth rings in all individuals and the same fluctuation patterns. Their ring widths were generally positively correlated with precipitation from April to October (except for August) and with temperature from February to June (except June for L. daurica), September to October, and the annual mean. Strong deviations of annual ring widths from their neighbour rings were observed in 1998 and 2000. The trend of absolute distinctness scores (Dm) increased significantly from 1988 to 2003, indicating an increase in the frequency of annual ring width variation. Conclusions: Annual growth rings in the main roots of three perennial forb species can be used as an indicator of the influence of climate on below‐ground grassland growth. The change in below‐ground conditions and effects on the functioning of grassland should receive more attention in future studies. 相似文献
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The aim of this study is to examine changes in prevalence of overweight and obesity, using International Obesity Task Force criteria, in three cohorts of children and youth living in Cracow, Poland, in 1971, 1983 and 2000. Rates of overweight and obesity doubled among boys and girls, from 7.5% and 6.5% in 1971, to 15.2% and 11.8% in the year 2000. The greatest increases in prevalence occurred in the youngest age groups (7–12 years for boys and 7–10 years for girls), increases being less extensive among adolescents, and lowest of all in the oldest age groups (16–18 years in boys and 14–18 years in girls). The absence of a positive secular trend in BMI among adolescent females relative to males may be due to sociocultural pressures associated with transition to a free market economy in Poland. The extent to which girls attempt to achieve the ideal body, as portrayed by media and society more generally, increases across adolescence. 相似文献
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The arboreal crab Parasesarma leptosoma has been recently discovered at Mngazana, a southerly mangrove system in southern Africa, where crab tree preferences were
studied using an indirect (browse leaf damage) and a direct (tree traps) method. The extent of crab induced leaf damage was
compared for three mangrove species at two sites, one next to a tidal creek and one away from the creek. Using ANOVA, significant
differences were found between tree species (P < 0.001) at different distances from the creek (P < 0.022). Crabs were found to occur on Rhizophora mucronata and Brugueira gymnorrhiza, but not on Avicennia marina. This reflected a gradient in browsing, from well-browsed R. mucronata (100% near the creek and 25.7% away from the creek), to medium browsing of B. gymnorrhiza (51.5% near and 0% away) and no browsing on A. marina (near or away). These differences could be explained in terms of palatability, as both R. mucronata and B. gymnorrhiza are salt excluders, while A. marina secretes salt from its leaves. Leaf consumption levels averaged between 1.73% and 2.6% of leaf area for R. mucronata and 0–1.76% for B. gymnorrhiza. For both R. mucronata and B. gymnorrhiza there was a significant correlation between the number of crabs caught directly and the amount of browse leaf damage (P < 0.01). Crab number was also significantly correlated with tree circumference for R. mucronata (r
2 = 0.67) and B. gymnorrhiza (r
2 = 0.76, P < 0.05), with crabs more prevalent on the former tree species and no crabs trapped on A. marina (91.7%, 38.3% and 0% catches, respectively), thus reflecting the results obtained by the indirect method. Total Nitrogen
and Phosphate were measured for both sediment and leaves of the three mangrove species at the two sites. Leaf comparisons
showed significant differences (P < 0.01) for both Total Nitrogen and Phosphate with R. mucronata having the highest values, followed by A. marina and lastly B. gymnorrhiza. Total Nitrogen was significantly higher for both B. gymnorrhiza and R. mucronata compared with A. marina, while leaf phosphate was significantly lower for B. gymnorrhiza when compared with both R. mucronata and A. marina. No significant differences were found for leaf nutrients between sites, with the exception of A. marina and R. mucronata Total Nitrogen, which was significantly higher at the near creek sites (P < 0.05). Sediment analysis showed no significant differences (P > 0.05) in either nutrients or median particle size. Thus, R. mucronata, especially near the creek, had higher nutrient value and was probably more palatable and could explain observed differences
in crab distribution. Very little browse damage was encountered in saplings below 10 cm. Most poles chopped by the local communities
are R. mucronata in the 15–20 cm category, which coincides with peak crab frequencies in the 15–25 cm size classes for R. mucronata and B. gymnorrhiza, so that this selective harvesting is affecting this crab population maximally. Predictions were made as to the effect of
crab loss, tree replacement rate and alternatives to chopping, which would boost community socio-economic levels and reduce
the anthropogenic pressure on this biodiverse southerly mangrove system. 相似文献
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Heiko Hillgrtner Andr Strasser 《Palaeogeography, Palaeoclimatology, Palaeoecology》2003,200(1-4):43-63
When quantifying sedimentary processes on shallow carbonate platforms, it is important to know the high-frequency accommodation changes through time. Accommodation changes in cyclic successions are often analysed by simply converting cycle thickness to Fischer plots. This approach is not satisfactory, because it does not account for differential compaction, possible erosion, sea-level fall below the depositional surface, or subtidal cycles. An attempt is made here to reconstruct a realistic, high-frequency accommodation and sea-level curve based on a detailed facies and cyclostratigraphical analysis of Middle Berriasian to Lower Valanginian sections in the French Jura Mountains. The general depositional environment was a shallow-marine carbonate platform on a passive margin. Our approach includes the following steps: (1) facies interpretation; (2) cyclostratigraphical analysis and identification of Milankovitch parameters in a well-constrained chronostratigraphic framework; (3) differential decompaction according to facies; (4) estimation of depth ranges of erosion and vadose zone; (5) estimation of water-depth ranges at sequence boundaries and maximum flooding intervals; (6) estimation of mean subsidence rate; (7) classification of depositional sequences according to types of facies evolution: ‘catch-up’, ‘catch-down’, ‘give-up’, or ‘keep-up’; (8) classification of depositional sequences according to long-term sea-level evolution: ‘rising’, ‘stable’, ‘falling’; (9) calculation of ‘eustatic’ sea-level change for each depositional sequence using the parameters inferred from these scenarios, assuming that sea-level cycles were essentially symmetrical (which is probable in Early Cretaceous greenhouse conditions); (10) calculation of a sea-level curve for each studied section; (11) comparison of these curves among each other to filter out differential subsidence; (12) construction of a ‘composite eustatic’ sea-level curve for the entire studied platform; (13) spectral analysis of the calculated sea-level curves. Limitations of the method are those common to every stratigraphic analysis. However, the method has the potential to improve the original cyclostratigraphical interpretations and to better constrain the high-frequency sea-level changes that control carbonate production and sediment fluxes. 相似文献
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Gerhard Scholtz 《Acta zoologica》2013,94(2):218-221
Scholtz G. in press. A plea for ‘genealogical thinking’ in comparative biology – a rebuttal to the reply of Szucsich, Wirkner, and Pass to my article ‘Deconstructing Morphology’. —Acta Zoologica (Stockholm) 00 : 1–4. Szucsich et al. (in press) claim that – in contrast to my statement – morphological thinking has to be ‘cladistic.’ Based on this premise, they stress the difference between the relationships among states of characters versus those among structures assigned to the same character state as implemented in numerical cladistic reasoning. SEA claim that my approach to the homology concept only deals with the problem of the integration of various character states into the same character, whereas the necessary relationships among structures assigned to the same state are not covered. Based on this distinction, SEA also criticise the application of similarity in my definition of homology. Furthermore, they address the issue of evolutionarily independent units. 相似文献