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21.
Environmental correlates of body size distribution in Cyprinidae (Actinopterygians) depend on phylogenetic scale 下载免费PDF全文
Gaël P.J. Denys Pablo A. Tedesco Thierry Oberdorff Philippe Gaubert 《Ecology of Freshwater Fish》2016,25(1):125-132
The pattern of increasing species body size with increasing latitude has been noticed in different groups of animals. Here, we used seven key environmental factors and independent contrasts to assess body size latitudinal clines in Cyprinidae at two phylogenetic levels (inter‐ and intragenera), which were defined using a genus‐level supertree. Model selection procedures revealed that environmental factors shaping body size variation in Cyprinidae differed according to the phylogenetic scale considered. At the higher phylogenetic level, we found that both temperature (negative effect) and habitat availability (positive effect of drainage basin surface area) constituted mechanistic explanations of large‐scale body size distribution. No temperature‐related body size cline was observed at the intragenus level. Instead, competitive interaction (negative effect of species richness), habitat availability (positive effect of drainage basin surface area), migration ability and available energy (positive effects of glacial coverage and actual evapotranspiration) constitute alternative explanations at this lower phylogenetic scale. We conclude that (i) at the intergenus level, cyprinids do show a tendency to be smaller at high temperatures and larger at low temperatures, (ii) this tendency no longer exists at the intragenus level, (iii) latitude per se is a weak predictor of body size clines whatever the taxonomic level analysed, (iv) generalising geographical body size patterns may be rendered difficult by the superimposition of a series of mechanisms across different taxonomic scales, and (v) habitat size, here acting positively at both taxonomic scales, may play a major role in shaping riverine species body size clines. 相似文献
22.
淡水渔业在福建省渔业中占据重要的地位也具有较大的空间。淡水渔业的发展必须依靠淡水渔业科技的先行发展。为此,本文首先介绍福建省淡水渔业的现状;其次,阐述了发展淡水渔业科技首先要解决的几个认识上的问题;最后提出发展我省淡水渔业对本学科提出的几点要求和未来学科发展的几个重点领域,希望本文对淡水渔业科技的发展具有借鉴意义。 相似文献
23.
采用三点弯曲法对大庆红旗泡水库淡水冰试样进行弯曲试验.冰梁发生破坏时,主要经历三个阶段:第一阶段是在杂质和气泡边缘首先产生微裂缝;随着荷载的增加,出现新的微裂缝,并且受拉区达到抗拉强度,此为第二阶段;此后荷载继续增加,冰中微裂缝扩展延伸为宏观裂缝,当施加的荷载大于冰梁的杭拉强度时,冰梁即被破坏,这是第三阶段.在分析上述淡水冰破坏机理的基础上,对试验结果进行研究.结果表明,水库淡水冰弯曲强度与应力速率和冰温有着密切关系.在小于2 kPa/s的应力速率范围内,随着应力速率的增大,弯曲强度减小.冰温在-5℃~15℃范围内,对应的应力速率在30~70 kPa/s范围内时,冰梁弯曲强度达到极限,同时也揭示了极限弯曲强度对应的应力速率随着温度的降低逐渐向低应力速率转化.达到极限弯曲强度后,应力速率继续增加,弯曲强度值呈减小趋势.弯曲强度随着冰温的降低呈增加趋势,且弯曲强度在-15℃时达到最大值2 270 kPa. 相似文献
24.
25.
针对森林生态系统的作用、功能,结合福建省的山地森林,与流域淡水及湿地中的水源水质的密切关系,提出:要保护好森林资源,以及流域内的淡水和湿地;要从系统整体性出发,防范森林退化、破坏,以及流域内的淡水与湿地的破坏与污染问题。 相似文献
26.
Jürgen Weber Jupp Kreutzmann Anita Plantikow Evelyn Claus Werner Manz Peter Heininger 《Journal of Soils and Sediments》2006,6(2):84-91
Goal, Scope and Background Numerous xenobiotics released into surface waters are transferred to suspended particulate matter and finally attached to
sediments. Aquatic organisms may be exposed to them by direct particle feeding, by physical contact with contaminated surfaces
as an exposure route, and by the uptake of dissolved contaminants after equilibration via the free water phase. In order to
assess potential sediment toxicity, each of these exposure routes has to be addressed. This paper presents a newly developed
particle contact assay that uses the fermentation performance of a specific Saccharomyces cerevisiae strain for the assessment
of toxic effects in sediments. The test procedure is based on the characteristic feature of growing yeast cells to attach
to sediment particles, which are also relevant for the accumulation of contaminants. The physical contact with lipophilic
contaminants mirrors an exposition pathway for the direct uptake into the cells. In order to quantitatively characterize the
toxic effects of particle attached pollutants on the fermentation performance, unpolluted native reference sediment was spiked
with representatives for widely distributed anthropogenic contaminants.
Methods Saccharomyces cerevisiae was established as sensitive eukaryotic microorganism for the ecotoxicological assessment of particle
attached anthropogenic contaminants in freshwater sediments. For this purpose, yeast cells were cultivated in sediment samples
and the resulting fermentation performance was continuously measured. Sediments artifically spiked with HCB, PCB, g-HCH, DDT,
and benzo(a)pyrene and solutions of each contaminant were comparatively investigated by means of their adverse effects on
yeast fermentation performance. Additionally, four native river sediments characterized by increasing levels of pollution
were assessed by the yeast particle contact assay, and simultaneously by standard aquatic tests with algae, daphniae, and
luminescent bacteria using pore water and elutriates. Results of the bioassays were related to specific sediment contamination
with respect to metals and organic priority pollutants.
Results and Discussion In sediments spiked with PCB and benzo(a)pyrene fermentation, performance was affected extensively below concentrations inhibiting
fermentation in contaminant solutions. This suggests a high efficiency of the exposure route by physical contact. The fermentation
performance was only slightly affected by single lipophilic pollutants, whereas mixtures of individually spiked sediments
caused critically reduced fermentation performance suggesting additive synergistic effects. Native river sediments modestly
to critically polluted by hazardous organic compounds lead to a slightly to dangerously reduced fermentation performance in
the yeast contact assay. These inhibitory effects were much less pronounced in the standard bioassays conducted with algae,
daphniae and luminescent bacteria, applying pore waters and elutriates as sample matrices. Using pore water, inhibition was
measured only in the most polluted sediment, elutriates lead to a slight inhibition of the algal growth in the undiluted sample
only. These results indicate an improved sensitivity of the yeast particle contact assay compared to the standard assays,
due to uptake and physical cell contact as additional routes of exposure.
Conclusion The yeast particle contact assay is a valuable tool for the assessment of ecotoxicological potential in freshwater sediments.
Since the assay addresses physical contact as an exposure route, it indicates bioavailability of lipophilic compounds in sediments.
Outlook The sensitive indication of bioavailable contaminants associated to sediment particles by the newly developed yeast particle
contact assay recommends it as a complementary microbial bioassay in a test battery for assessing major pathways of contaminants
in whole sediments. 相似文献
27.
Goal, Scope and Background
Distribution of hydrophobic organic contaminants in abiotic compartments is essential for describing their transfer and fate in aquatic ecosystems. Taihu Lake is the third largest freshwater lake in China. Water quality of Taihu Lake has deteriorated greatly during the last decades and has threatened the water supply. The aim of the present study was to investigate the partitioning of polycyclic aromatic hydrocarbons (PAHs) among overlying water, suspended particulate matter (SPM), sediments, and pore water in Meiliang Bay, Taihu Lake and to provide useful information for the ecological engineering in this area.Materials and Methods
Overlying water and surface sediment were sampled from six sites in Meiliang Bay, Taihu Lake, China. Within 72 h of sampling, sediments were centrifuged to obtain the pore water. Overlying water samples were filtered to separate dissolved and SPM samples. After extraction, samples were purified following a clean-up procedure. PAH fraction was obtained by elution with a mixture of hexane: DCM (7:3, V/V) and analyzed by GC/MS.Results
PAHs concentrations in overlying water varied from 37.5 ng/L to 183.5 ng/L. Concentrations of PAHs in pore water were higher than those in overlying water. The total concentrations of 16 priority PAHs in sediments ranged from 2091.8 ng/g-dw to 4094.4 ng/g-dw. PAHs concentrations on SPM were decreased with suspended solid concentrations (SSC). Total PAHs concentrations on SPM varied in the range of 3369.6 ng/g-dw to 7531.1 ng/g-dw. The partition coefficients between sediment and overlying water (log K oc) for PAHs with log K ow<5 were positively correlated with their octanol-water partition coefficients (log K ow) (n=39, r=0.79, p<0.0001). Partition coefficients between sediment and pore water (log K oc′) for all PAHs were also significantly correlated with their log K ow values (n=48, r=0.82, p<0.0001).Discussion
In general, PAHs derived from combustion sources tend to bind strongly to soot particles in natural sediment. Consequentially, K oc values observed in the natural environment could be orders of magnitude higher than those predicted by linear correlation relationships under laboratory conditions. In the present study, the ratio of log K oc values to log K ow values falls consistently above 1, indicating that the sediment soot carbon in the bay was more attractive for PAHs than n-octanol. The log K oc′ was also higher than that predicted under laboratory conditions, suggesting that the measured pore water PAH concentrations were lower than those predicted. That is to say, not all the sediment PAHs can be available to partition rapidly into sediment pore waters. A variation in soot content is a possible reason. Furthermore, concentrations of PAHs on SPM were higher than those in sediments. The compositions of PAHs on SPM and in sediments were similar, indicating the importance of re-suspension process of sediments in the partitioning process of the shallow lake.Conclusions
The results indicated the equilibrium partitioning model could be used to predict PAHs distribution in various phases of a shallow lake in the stagnation period, but re-suspension processes should be considered to modify the relationship between log K ocs and log K ows.Recommendations and Perspectives
Concentration, particle size and composition of resuspended particles could affect the relationship between log K ocs and log K ows. Further work should be done under field conditions, especially where a steady thermodynamic equilibrium state could be assumed.28.
29.
[目的]探讨非洲淡水鳉鱼的生存要素和日常管理。[方法]以贡氏假腮鳉为例,从水质、水温、光照和日常管理等方面来探讨贡氏假腮鳉的生存要素和日常管理。[结果]贡氏假鳃鳉幼鱼对水质和水温的要求很高。若水温过低,幼鱼的生病几率会大大增加,还可能出现畸变情况。另外,光照对成鱼的色彩也有很大影响。[结论]在贡氏假鳃鳉的日常饲养中,水中的溶氧量一般保持在6 mg/L以上。 相似文献
30.
淡水养殖鱼类主要细菌性传染病快速诊断的研究——鱼病诊断箱的应用试验 总被引:2,自引:0,他引:2
应用以葡萄球菌A蛋白协同凝集试验(SPA-COA)为主要检测手段的鱼病诊断箱,于1995 ̄1997年在吉林,辽宁等7省进行现场检测试验。结果,61个渔场11个品种的516尾病鱼有菌生长的285尾,经SPA-COA鉴定阳性数为239尾,占有菌生长的83.86%,12个渔场5个品种1216尾假定健康鱼有菌生长的为28尾,经SPA-COA鉴定阳性数为22尾,占有菌生长的78.57%,认为本诊断箱适用于基 相似文献