Determining particle density distribution of expanded bed adsorbents

This study presents an experimental approach to measure the density distribution of expanded bed adsorption (EBA) matrices. We report on the use of a series of solutions of caesium trifluoroacetate (CsTFA) of varying density spun in a laboratory centrifuge so as to separate representative matrix samples on the basis of bead density. Mass data was used to plot a decumulative density distribution for the matrix. By performing laser light scattering-based measurements on the same samples of matrix the variation in particle size with density was determined. Particle settling velocity distributions were then calculated using these data and compared with a settling velocity distribution calculated on the basis of an assumed constant bead density. The study demonstrates a reliable and simple method for the characterisation of matrix density distribution. For the case of the Streamline matrices tested the particle size distribution is constant with varying bead density. Bead densities varied from 1.5 to 2.1 g/cm3 in the CsTFA solutions. These were then adjusted using bead porosity to give a density range of 1.11-1.33 g/cm3 in aqueous buffer (assumed 1.0 g/cm3) The differences in resultant settling velocity distributions when based upon measured density distribution than when based upon an assumed mean density value were shown to be insignificant. This result confirms experimentally that an assumption of a single constant mean density for EBA particles is acceptable for hydrodynamic modelling and performance prediction purposes.     

白冠长尾雉(Syrmaticus reevesii)在贵州的分布与数量

白冠长尾雉(Syrmaticus reevesii)是我国的珍禽,分布于河北北部和西部、山西、陕西南部、湖北、湖南西北、贵州北部、河南西部、安徽西部及四川东部(郑作新,1978);还发现于甘肃南部的康县(刘乃发,1982)。1974—1982年,在贵州鸟类区系调查时,对于白冠长尾雉的分布、生态及数量曾作过初步研究,复于1983—1985年间,对它的生态生物学进行专门研究。本文仅就它在贵州省的分布和数量予以报道。     

中国翼手目地理分布的环境因子影响分析

利用地理信息系统提取了中国翼手目90个物种已知地理分布点的环境因子数据,并利用主成分分析和逐步回归分析研究了这些环境因子对中国翼手目动物地理分布和种数密度分布的影响程度。结果表明,按其影响程度大小,影响中国翼手目动物地理分布的连续型环境因子依次为年平均气温、大于零度日数、一月份平均气温、无霜期日数、年降雨量、年平均相对湿度、七月份平均气温、海拔高度和年日照时数,其中年日照时数和海拔高度为负影响;影响翼手目种数密度分布的决定环境因子是年降雨量,但年平均气温也有明显作用。作者认为,气候因子影响翼手目动物地理分布的机制是限制性因子的作用,主要受冬眠和活动及摄食时间长短的限制,而种数密度分布则决定于环境资源的丰富度,即主要受到由降雨量决定的食物种类多少的影响。另外,对类别环境因子的研究表明：植被类型对翼手目的种数分布没有明显影响;具有多洞穴特点的喀斯特和火山熔岩地貌具有较多的翼手目种类,但红层地貌由于分布于南方和分散分布的特点而具有最高的翼手目种数密度[动物学报51(3)：413—422,2005]。     

围栏放牧下土壤-植被碳密度空间分布格局

对围封13年且放牧的冷季高寒矮嵩草草甸,进行了从围栏入口到内部不同距离植被和土壤碳密度状况的调查.结果表明:1)入口到50 m植被现存碳密度平均为1298.0gC·m-2,60～180m有所下降(平均为997.3 g C·m-2),200～300 m反而升高(平均为1285.5 g C·m-2).当年净初级生产碳密度分布趋势与其相同,0～50 m、60 ～180 m和200～300 m平均分别为742.5、571.0和745.7 g C·m-2.这种分布趋势与放牧过程中绵羊觅食频度和强度有关.一般在中央地带放牧强度大,绵羊觅食时间长,边缘地带受围栏效应或围栏外环境因素影响,放牧强度相对较弱,一定程度上对植被生长发育起到了保护作用,使边缘地带植被碳密度得到提高.2)从围栏入口到草场内部土壤碳密度变化趋势表现复杂,入口到100 m增加,100～170 m减小,然后略有升高.土壤碳密度最高值出现在95 m处(15.42 g C·m-2),最低值出现在170 m处(14.12 gC· m-2).目前尚不清楚为何出现这种格局,但至少认为,土壤有机质的动态转化过程受多种因素影响,与植被碳密度相比具有一定的迟滞效应.具体如何影响有机质的动态转化及其迟滞效应,有待进一步研究.     

The nematode fauna of a temperate Australian mangrove mudflat; its population density,diversity and distribution

The nematode fauna of an estuarine mangrove Avicennia marina mudflat in Southeastern Australia has been intensively studied. About 85% of the nematodes occur in the top cm of soft mud, but 5–7 species inhabit the deeper anoxic mud down to 10 cm, both at low and high tide. One square metre was intensively sampled from four zones with different nematode faunas. At the low tide zone 58% of the nematodes were epistrate feeders, including many diatom-feeders, but in the mangrove zone selective microbial feeders made up over 60% of the population, while between high water neap and high water spring, above the mangrove zone, omnivore/predators and plant root feeding nematodes increased in relative importance. Random replicate cores reliably sampled species occurrence, but gave a high variance in density estimates. Replicate aliquots from homogenised mud gave lower density variance. Nematode densities (maximum 5 × 10⁶ m^-2) were not as high as have been reported from non-mangrove estuaries in other countries, but were within the range found in mangroves elsewhere in Australia. Margalef Species Richness values ranged from 1.7 to 3.89, which is similar to values found in other mangroves mudflats in Australia. Nematode biomass ranged from 888 mg dry weight m² (383 mg C m^-2) at the low tide zone to 19 mg dry weight m^-2 (8 mg C m^-2) at the upper tide level.     

宁夏宁南山区红庄林场甘肃鼢鼠分布密度与危害研究

通过对红庄林场不同立地条件随机抽样调查,结果表明：山间谷地甘肃鼢鼠平均密度为33只/hm^2;草甸山坡甘肃鼢鼠平均密度为13．3只／hm^2;林地甘肃鼢鼠平均密度为6．3只／hm^2。由于鼢鼠破坏活动,幼林受害率轻者为10％～20％,重者达到70％-80％。鼢鼠危害已制约当地造林工程的发展。     

基于地统计学和CFI样地的浙江省森林碳空间分布研究

基于浙江省2009年CFI固定样地数据、森林资源规划设计调查林相图,利用地统计学方法对浙江省森林碳空间分布进行了模拟分析。结果表明,CFI固定样地数据用于省域范围的森林碳汇空间特征研究是合适的。数据显示,浙江森林植被平均碳密度为22.07Mg/hm2;与四川、福建、海南等地相比,平均碳密度较低。受人类活动、自然环境等因素影响,浙江省森林碳分布主要表现为:总体上森林碳密度空间变化趋势自西向东逐渐降低,与自然空间(海拔、地势等)趋势一致。基于地统计学和CFI固定样地,对省域范围的森林资源空间分布的研究,可以为省域森林碳汇管理提供依据,为我国特别是亚热带南方集体林区利用国家CFI数据进行大区域同类研究提供借鉴。     

Effects of angling on population structure of brown trout,Salmo trutta L., in mountain streams of Northern Spain

Effects of angling exploitation on brown trout populations were assessed by comparing fished sections with close ones unfished for at least 20 years, in mountain streams of Asturias (Northern Spain). Both the fish size and age structure significantly differed among sections in the expected direction according to their exploitation status. The main effects were a significant decrease in age structure complexity (diversity), life span, and percent individuals above the legal limit size in the exploited stocks versus the unexploited ones. Trout above the minimum length limit for fishing (18 cm) averaged 19.47% of the fish caught in the unfished sections (sd = 4.01; n = 5), and 4.72% (sd = 3.46; n = 4) in those subjected to angling. Furthermore, fish older than 4 years represented 39.84% (sd = 8.53) and 1.19% (sd = 1.60) of the catch, respectively. Effects on recruitment (density of young fishes) and growth rates (length at age 1 + to 3 +) were not absolutely consistent, though maximum values were associated with fished sections.     

Lemur responses to edge effects in the Vohibola III classified forest, Madagascar

Forest edges are dynamic zones characterized by the penetration (to varying depths and intensities) of conditions from the surrounding environment (matrix) into the forest interior. Although edge effects influence many tropical organisms, they have not been studied directly in primates. Edge effects are particularly relevant to lemurs because of the highly fragmented forest landscapes found in Madagascar. In this study, data are presented regarding how the densities of six lemur species (Avahi laniger, Cheirogaleus major, Eulemur rubriventer, Hapalemur griseus griseus, Microcebus rufus, and Propithecus diadema edwardsi) varied between six 500-m interior transects and six 500-m edge transects in the Vohibola III Classified Forest in SE Madagascar. Diurnal (n = 433) and nocturnal (n = 128) lemur surveys were conducted during June-October 2003 and May-November 2004. A. laniger, E. rubriventer, and H. g. griseus exhibited a neutral edge response (no differences in densities between habitats). M. rufus and P. d. edwardsi had a positive edge response (higher densities in edge habitats), which may be related to edge-related variations in food abundance and quality. Positive edge responses by M. rufus and P. d. edwardsi may ultimately be detrimental due to edge-related anthropogenic factors (e.g., hunting by local people). The negative edge response exhibited by C. major (lower densities in edge habitats) may result from heightened ambient temperatures that inhibit torpor in edge habitats.     

Cercariometry for detection of transmission sites for schistosomiasis

Cercariometry provided information on diurnal fluctuation, seasonal and spatial distribution of cercariae in the suitable natural water bodies. There was an apparent mismatch between the results of cercariometry and snail sampling. Water, which cercariometry showed to contain cercariae was potentially infective, although the resultant worm load of sentinel rodents may not bear a linear relationship with cercarial density. Cercariometry has some weakness in practices and analysis of data, however, it provides the valuable information on the active transmission sites of schistosomiasis.     

Do haddock select habitats to maximize condition?

Haddock Melanogrammus aeglefinus in the North sea increased their distributional range when more abundant, but this density dependent habitat selection (DDHS) explained only a small part of the year‐on‐year variation in distribution patterns. The condition of haddock was examined at 24 sites in the North Sea in August and September 2004 and related to their abundance, to examine if the ideal free distribution theory (IFD), which assumes that organisms select habitats that maximize their rate of food intake, can be used to explain this variation in large scale distribution patterns. At a given temperature, condition (hepato‐somatic index, I _H) was better at stations where haddock were most abundant. Therefore, haddock were not distributed perfectly according to the IFD in 2004. The positive correlation between abundance and I _H, however, indicated there was some habitat selection by haddock, as in the total absence of habitat selection no correlation between I _H and abundance, and no spatial variation in abundance was expected. DDHS may only explain a small part of the yearly variation in the distribution because haddock did not equalize and maximize their fitness at the scale of the North Sea. In addition, stable isotope analysis of muscle samples showed that haddock did not avoid competition for food when at high abundance by feeding at a lower or wider range of trophic levels.     

Space-time heterogeneities of the zooplankton distribution in La Concepción reservoir (Istán,Málaga; Spain)

Space-time distribution of the zooplankton (Rotifera, Cladocera and Copepoda) density along the central axis (horizontally and vertically) and the shores of La Concepción reservoir have been studied for one year. Results show that the distribution along the central axis and the shores follows similar patterns both in space and time. Rotifera and Copepoda mainly appear during the first part of the mixing period and Cladocera during stratification. Horizontal distribution is characterized by the occurrence of density gradients from the intake to the dam. Vertical distribution present density maximum at the Secchi depth during mixing and at two times Secchi depth, during stratification. Zooplankton distribution is related to physical-chemical and biotic factors.     

A survey of the distribution and density of the primates of Guyana

In January through February 1994, we conducted the first broad-scale survey of Guyanese primates since 1975. Our goals were (1) to follow up questions raised in the earlier survey, (2) to compare population densities, and (3) to locate potential sites for future long-term research. We used distributional survey methods along trails and rivers and interviewed local inhabitants in each region. We surveyed five general areas, two of which had been studied in 1975. The distribution reported in 1975 for five monkey species—Alouatta seniculus, Cebus olivaceus, Pithecia pithecia, Chiropotes satanas,and Saimiri sciureus—was confirmed. However, questions were raised concerning the western extent of the range of three species: Ateles paniscus, Cebus apella,and Saguinus midas.In comparing densities between 1994 and 1975, we found a significant drop in group densities over the past 20 years and a shift in relative proportions of individual primate species over time. For example, although the total number of kilometers surveyed was identical, group densities were three times higher in 1975 than in 1994. Further, group densities of Ateles, Alouatta,and Pitheciawere much lower, while those of Saguinuswere similar in both years. These findings strongly suggest that habitat destruction and continued hunting pressure are affecting the primate populations.     

Interspecific competition constrains local abundance in highly suitable areas

Sites with high environmental suitability for species’ occurrence, in terms of abiotic conditions, may hold populations with higher local abundances by increasing reproductive and survival rates and decreasing extinction rate. Interspecific competition, however, may affect this relationship. Here we tested the hypothesis that local abundance of the gray slender opossum Marmosops incanus is affected by the local richness of potential competitors and environmental suitability derived from ecological niche models (ENMs). We also discuss the ability of distinct modelling methods to predict species’ abundance. We compiled occurrence records and information about M. incanus’ relative abundance from museums and published articles. Environmental suitability was derived from five algorithms using seven environmental predictors. To assess our hypothesis, we chose the best statistical models among generalised linear models and quantile regressions, and then tested whether the effects of richness of competitors on local abundance are stronger under highly suitable conditions. We found that environmental suitability given by presence-only methods are positively related to the maximum abundance of M. incanus. That is, species’ local abundance is low when suitability is low but can be either low or high when suitability is high. The richness of competitors, in turn, explains the abundance variation within sites with high environmental suitability. We strongly recommend that the relationship between abundance and suitability must be carefully interpreted when using ENMs to predict species’ distribution because biotic interactions can be the main driver of local abundance within highly suitable environments.     

Some aspects of the synanthropization of nine species of the Turdidae family in Kaliningrad

Numbers, dynamics of distribution for ten years, and relations between density and the rate of urbanization in nine species of Turdidae are calculated. During the last ten years the area of spatial distribution of most species increased by 2–15 times. A positive relationship between the numbers of birds and the rate of urbanization is revealed in the Redstart (R_{N 142} = 0.16; p = 0.049) and the Black Redstart (R_{N 134} = 0.25; p = 0.03), a negative relationship was observed in the Nightingale (R_{N 134} = ?0.23; p = 0.006) and the Robin (R_{N 43} = ?0.28; p = 0.06). The numbers of Whinchat, Wheatear, and thrushes does not depend on the rate of urbanization.     

Distribution and density of populations of goldsinny wrasse (Ctenolabrus rupestris) on the west coast of Scotland

A field survey of populations of goldsinny wrasse ( Ctenolabms rupestris ) was undertaken on selected areas of rocky coast of west Scotland. Observations by sub-aqua diving were used to determine distribution, habitat preference, and population density, and their seasonal variations. Availability of the preferred refuge type (crevices on rock faces, or between boulders, where two or more entrances exist) was essential in determining goldsinny presence. Goldsinny were not always present in areas or at depths where the influences of freshwater runoff (low temperatures and salinities) were likely, even if the preferred habitat type was available. In areas remote from these influences, and where there were suitable refuges, depth of water (0–44 m), macroalgal cover and high current speeds (2.1–3.6 ms⁻¹) did not affect goldsinny distribution. Observed densities of goldsinny reached a peak in summer months with a maximum of 4.0 m⁻² in areas of shallow boulder scree, but only 1.0 m⁻² in shallow areas with little scree, or at deeper study sites. Numbers of goldsinny observed actively swimming decreased after October, with a rapid disappearance in November. A gradual reappearance was recorded in late April, and early May. Changes in activity may be influenced by both water temperature and photoperiod. Young-of-the-year goldsinny were first observed in August in shallow water (0–8 m) areas typified by rock/boulder scree and/or high macroalgal cover. Where adults also inhabited these nursery areas, 0+ fish could make up over 50% of the total population. After their first winter, juvenile goldsinny may migrate away from inshore sites.     

Abundance and distribution of a brown trout (Salmo trutta, L.) population in a remote high mountain lake

Brown trout (Salmo trutta) population of a remote high mountain lake (Lake Redó, Pyrenees, 2240 m above sea level) were studied during autumn using hydroacoustic techniques. This acoustic technique was for the first time used on fish at such high altitude in Spain. Sampling using multimesh nets fish catches and echosounding recording were carried out in September 1998. Mean density of fish was estimated to be 1.82 fish per 1000 m³ (597 fish ha^–1). The results exhibited mainly a littoral habitat, with the brown trout being preferentially in the 10–25 m deep layer, where the water was warmer and the richness and diversity of macroinvertebrates higher. The sampling by hydroacoustic technique found a length frequency range of fish higher than the multimesh gill nets but both of them estimated similar fish proportion for the common length range. The more frequent target strength (TS) for the population was –38 dB (TS range –37 to –39 dB). Good correlation was found between TS frequency distribution obtained by echosounding and that predicted by means of a model based on the log of the fish total length from multimesh gill nets captures.