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1.
Maria João Feio Trefor B. Reynoldson Verónica Ferreira Manuel Augusto S. Graça 《Hydrobiologia》2007,579(1):55-68
We sampled macroinvertebrates at 75 locations in the Mondego river catchment, Central Portugal, and developed a predictive
model for water quality assessment of this basin, based on the Reference Condition Approach. Sampling was done from June to
September 2001. Fifty-five sites were identified as “Reference sites” and 20 sites were used as “Test sites” to test the model.
At each site we also measured 40 habitat variables to characterize water physics and chemistry, habitat type, land use, stream
hydrology and geographic location. Macroinvertebrates were generally identified to species or genus level; a total of 207
taxa were found. By Unweighted Pair Group Method with Arithmetic mean (UPGMA) clustering and analysis of species contribution
to similarities percentage (SIMPER), two groups of reference sites were established. Using Discriminant Analysis (stepwise
forward), four variables correctly predicted 78% of the reference sites to the appropriate group: stream order, pool quality,
substrate quality and current velocity. Test sites’ environmental quality was established from their relative distance to
reference sites, in MDS ordination space, using a series of bands (BEAST methodology). The model performed well at upstream
sites, but at downstream sites it was compromised by the lack of reference sites. As with the English RIVPACS predictive model,
the Mondego model should be continually improved with the addition of new reference sites. The adaptation of the Mondego model
methodology to the Water Framework Directive is possible and would consist mainly of the integration of the WFD typology and
increasing the number of ellipses that define quality bands.
Handling editor: K. Martens 相似文献
2.
1. Metabolism is the fundamental process that powers life. Understanding what drives metabolism is therefore critical to our understanding of the ecology and behaviour of organisms in nature. 2. Metabolic rate generally scales with body size according to a power law. However, considerable unexplained variation in metabolic rate remains after accounting for body mass with scaling functions. 3. We measured resting metabolic rates (oxygen consumption) of 227 field‐caught wolf spiders. Then, we tested for effects of body mass, species, and body condition on metabolic rate. 4. Metabolic rate scales with body mass to the 0.85 power in these wolf spiders, and there are metabolic rate differences between species. After accounting for these factors, residual variation in metabolic rate is related to spider body condition (abdomen:cephalothorax ratio). Spiders with better body condition consume more oxygen. 5. These results indicate that recent foraging history is an important determinant of metabolic rate, suggesting that although body mass and taxonomic identity are important, other factors can provide helpful insights into metabolic rate variation in ecological communities. 相似文献
3.
《Animal : an international journal of animal bioscience》2018,12(1):106-115
More energy-efficient, readily dimmable, long-lasting and more affordable light-emitting diode (LED) lights are increasingly finding applications in poultry production facilities. Despite anecdotal evidence about the benefits of such lighting on bird performance and behavior, concrete research data were lacking. In this study, a commercial poultry-specific LED light (dim-to-blue, controllable correlated color temperature (CCT) from 4500 to 5300 K) and a typical compact fluorescent light (CFL) (soft white, CCT=2700 K) were compared with regards to their effects on growing performance, activity levels, and feather and comb conditions of non-beak-trimmed W-36 pullets during a 14-week rearing period. A total of 1280-day-old pullets in two successive batches, 640 birds each, were used in the study. For each batch, pullets were randomly assigned to four identical litter-floor rooms equipped with perches, two rooms per light regimen, 160 birds per room. Body weight, BW uniformity (BWU), BW gain (BWG) and cumulative mortality rate (CMR) of the pullets were determined every 2 weeks from day-old to 14 weeks of age (WOA). Activity levels of the pullets at 5 to 14 WOA were delineated by movement index. Results revealed that pullets under the LED and CFL lights had comparable BW (1140±5 g v. 1135±5 g, P=0.41), BWU (90.8±1.0% v. 91.9±1.0%, P=0.48) and CMR (1.3±0.6% v. 2.7±0.6%, P=0.18) at 14 WOA despite some varying BWG during the rearing. Circadian activity levels of the pullets were higher under the LED light than under the CFL light, possibly resulting from differences in spectrum and/or perceived light intensity between the two lights. No feather damage or comb wound was apparent in either light regimen at the end of the rearing period. The results contribute to understanding the impact of emerging LED lights on pullets rearing which is a critical component of egg production. 相似文献
4.
Human migration is nonrandom. In small scale societies of the past, and in the modern world, people tend to move to wealthier, safer, and more just societies from poorer, more violent, less just societies. If immigrants are assimilated, such nonrandom migration can increase the occurrence of culturally transmitted beliefs, values, and institutions that cause societies to be attractive to immigrants. Here we describe and analyze a simple model of this process. This model suggests that long run outcomes depend on the relative strength of migration and local adaptation. When local adaption is strong enough to preserve cultural variation among groups, cultural variants that make societies attractive always predominate, but never drive alternative variants to extinction. When migration predominates, outcomes depend both on the relative attractiveness of alternative variants and on the initial sizes of societies that provide and receive immigrants. 相似文献
5.
Jarle Tryti Nordeide 《Journal of fish biology》2020,96(2):288-296
This paper highlights possible effects of physical and chemical mechanisms of formalin fixation and preservation on biological tissue and reviews the consequent potential inaccuracies on estimates of body mass of small fishes fixed and preserved in formalin. Twenty-six papers including 65 independent experiments with 35 species which examine effects of formalin on body mass estimates on small fishes are included. The effect of the formalin on the specimens depends on the salinity of the water used to dilute the commercial formalin (usually 1:9 formalin: water) before being used to fixate and preserve fish. Mean wet body mass of the specimens from the studies using seawater or fresh water diluted formalin deceases by 13% and increases by 7%, respectively, from before to after being immersed in formalin. The same trend is found with condition factor in the few papers that report this parameter. Body length decreases on average by c. 2% in fixated and preserved fish regardless of whether the formalin is diluted in seawater or fresh water. 相似文献
6.
CONRAD J. HOSKIN HAMISH McCALLUM † 《Biological journal of the Linnean Society. Linnean Society of London》2007,92(3):593-603
Parasites could differentially impact intraspecific host lineages due to genetic, phenotypic, ecological, or behavioural differences between the lineages, or the development of reproductive isolation between them. Batrachomyia (Diptera: Chloropidae) are flies that exclusively parasitize Australian frogs, and in the Wet Tropics rainforest of north‐east Australia larvae are largely restricted to the green‐eyed tree frog Litoria genimaculata (Anura: Hylidae). This frog species consists of two highly divergent genetic lineages that overlap in two nearby, but independent, contact zones. At one contact zone there has been extensive phenotypic divergence and speciation between the lineages whereas, at the other contact relatively lower levels of phenotypic divergence and reproductive isolation suggest that speciation has not occurred. In the present study we tested: (1) whether the deep phylogeographic divergence between northern and southern host populations is mirrored by congruent genetic structuring in the parasite populations and (2) whether the host lineages are differentially impacted by parasitism. We found that the two divergent frog lineages are parasitized by a single lineage of Batrachomyia, which exhibits strikingly little phylogeographic structuring. We found a significant difference in Batrachomyia prevalence between the host lineages at mixed lineage sites in both contact zones, with the magnitude and direction of this effect being consistent in both. The pattern did not differ between the two contacts even though recent phenotypic divergence and speciation has occurred between the lineages at one contact but not the other. Taken together, this suggests a fundamental difference in susceptibility between the genetically divergent host lineages. Using weight relative to body length as a measure of body condition, we found no differential impact of parasitism on the body condition of each host lineage, and no evidence that parasitism impacts the body condition of the host in general. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92 , 593–603. 相似文献
7.
I. A. Catalán † E. Berdalet † M. P. Olivar † C. Roldán † 《Journal of fish biology》2007,70(2):391-405
Six condition indices based on RNA, total soluble protein and two metabolic enzymes [lactate dehydrogenase (LDH) and citrate synthase (CS)] were analysed in muscle tissue of individual larvae, post-flexion reared sea bass Dicentrarchus labrax using DNA and total soluble protein as standards for size. In addition, the effect of 2 days of food deprivation on the cell proliferation rates was assessed. The RNA:DNA best reflected short-term changes in feeding conditions. If standardized by DNA content, LDH activity was a better indicator of condition than any other index but RNA:DNA. Further, the analysis of cell proliferation rates in muscle from 26 day-old larvae proved useful in distinguishing continuously fed larvae from individuals subjected to 2 days of fast. 相似文献
8.
小麦—天兰偃麦草—黑麦三属杂种花粉植株诱导条件的研究 总被引:3,自引:1,他引:2
研究表明,三属杂种处于单核中晚期阶段的花粉最适于诱导形成愈伤组织。低温预处理对促进三属杂种花粉愈伤组织的诱导有一定的作用。利用以马铃薯提取物为基础物质的马铃薯-Ⅱ培养基作诱导培养基,其愈伤组织诱导与分化的频率比目前两个较好的合成培养基要高。同一个三属杂种F_1春、秋播种植株之间在形成愈伤组织的能力上有较大的差异,秋播材料形成愈伤组织的能力明显高于春播材料。F_(?)杂种植株诱导愈伤组织和分化植株的频率均比F_1杂种明显提高。 相似文献
9.
D. T. WILLIAMSON 《African Journal of Ecology》1991,29(2):105-117
Information on condition, growth and reproduction was collected from a sample of 155 female lechwe in the Linyanti Swamp, northern Botswana. Condition varied significantly with age, reproductive state and season and indications were found of relationships between body mass and the attainment of puberty in young females and body mass and the fertility of adult females. There were also indications that the population was under nutritional stress because of high water levels and that this had caused reductions in the growth rate and fertility of young females. It is suggested that the sensitivity of young females to adverse environmental conditions could be exploited to optimize population monitoring for conservation purposes by using them as an indicator class, rather than monitoring the entire population. Because of relationships between condition, growth and reproduction, it is also suggested that long-term monitoring of condition should form part of any effort to understand population dynamics. 相似文献
10.