优势菌株生物膜法处理卡那霉素废水

进行了选用优势菌株生物膜法处理卡那霉素废水的工艺条件研究。通过自然驯化污泥挂膜和投加优势菌种挂膜两种工艺的对比试验，揭示了两者在挂膜时间、接触停留时间、进水浓度、耐冲击负荷等方面的不同，指出投加优势菌挂膜系统运行效果优于自然驯化污泥挂膜系统，当进水ＣＯＤｃｒ浓度为３５００￣４０００ｍｇ／Ｌ时，其去除率可稳定达到８８％￣９０％，效果显著。     

Seasonal density dependence, timing of mortality, and sustainable harvesting

Birth-pulse populations are often characterized with discrete-time models, that use a single function to relate the post-breeding population size to the post-breeding size of the previous year. Recently, models of seasonal density dependence have been constructed that emphasize interactions during shorter time periods also. Here, we study two very simple forms of density-dependent mortality, that lead to Ricker and Beverton-Holt type population dynamics when viewed over the whole year. We explore the consequences of harvest timing to equilibrium population sizes under such density dependence. Whether or not individual mortality compensates for the harvested quota, the timing of harvesting has a strong impact on the sustainability of a harvesting quota. Further, we show that careless discretization of a continuous mortality scheme may seriously underestimate the reduction in population size caused by hunting and overestimate the sustainable yield. We also introduce the concept of the demographic value of an individual, which reflects the expected contribution to population size over time in the presence of density dependence. Finally, we discuss the possibility of calculating demographic values as means of optimizing harvest strategies. Here, a Pareto optimal harvest strategy will minimize the loss of demographic value from the population for a given yield.     

Sperm competition and sexual selection: a meta-analysis of paternity studies of birds

Sperm competition (the competition among the sperm of different males for fertilization of the eggs of a female) has been suggested to be an important component of sexual selection, but no general assessment has been made of this proposition. We used a meta-analytic approach to assess the extensive literature on paternity (the proportion of offspring in a focal nest sired by an attending male) in birds based on allozyme and molecular techniques. The relative variance in male mating success was on average increased by a factor of 4.6 over the variance in apparent male success. Males with more extravagant secondary sexual characters had higher paternity in their own nests than less adorned males. There was a weak effect of male age being positively associated with paternity in own nests. Male body size measured as the length of wing and tarsus was weakly positively associated with paternity in own nests. Male survival prospect was positively associated with paternity in own nests. Polygynous males generally had decreased paternity of their broods compared to monogamous males. Paternity of the resident male decreased with increasing population density and breeding asynchrony. The intensity of paternity guards such as within-pair copulation rate and mate guarding were not significantly related to extra-pair paternity. Sperm competition was thus an important component of sexual selection by increasing the variance in male mating success, and by being associated with the expression of secondary sexual characters, in particular in dense and asynchronously breeding populations of birds. Received: 12 February 1998 / Accepted after revision: 31 May 1998     

Influence of environmental properties on macrobenthos in the northwest Indian shelf

The paper deals with the standing stock of macrobenthic infauna and associated environmental factors influencing the benthic community in the shelf region of the northwest Indian coast. The data were collected onboard FORV Sagar Sampada during the winter monsoon (January–February, 2003) to understand the community structure and the factors influencing the benthic distribution. The environmental parameters, sediment characteristics and macrobenthic infauna were collected at 26 stations distributed in the depths between 30 and 200 m extending from nobreak{Mormugao} to Porbander. Total benthic abundance was high in lower depths (50–75 m), and low values noticed at 30 m depth contour was peculiar. Polychaetes were the dominant group and were more abundant in shallow and middle depths with moderate organic matter, clay and relatively high dissolved oxygen. On the other hand crustaceans and molluscs were more abundant in deeper areas having sandy sediment and low temperature. High richness and diversity of whole benthic groups observed in deeper depths counter balanced the opposite trend shown by polychaete species. Generally benthos preferred medium grain sized texture with low organic matter and high organic matter had an adverse effect especially on filter feeders. Deposit feeding polychaetes dominated in shallow depths while carnivore species in the middle depths. Ecologically, benthos were controlled by a combination of factors such as temperature, salinity, dissolved oxygen, sand and organic matter and no single factor could be considered as an ecological master factor.     

A population model for the peach fruit moth, Carposina sasakii Matsumura (Lepidoptera: Carposinidae), in a Korean orchard system

A population model for the peach fruit moth, Carposina sasakii Matsumura, was constructed to understand the population dynamics of this pest species and to develop an effective management strategy for various orchard (apple, peach, apple + peach) systems. The model was structured by the five developmental stages of C. sasakii: egg, larva, pupa, larval-cocoon (overwintering larva), and adult. The model consisted of a series of component models: (1) a bimodal spring adult emergence model, (2) an adult oviposition model, (3) stage emergence models of eggs, larvae, and pupae, (4) a larval survival rate model in fruits, (5) a larval-cocoon formation model, and (6) an insecticide effect model. Simulations using the model described the typical patterns of C. sasakii adult abundance in various orchard systems well, and was specific to the composition of host plants: three adult abundance peaks (first peak, mid-season peak, and last peak) a year with decreased peaks after the first peak in monoculture orchards of late apple, two adult peaks a year with a much higher last peak in monoculture orchards of early peach, and three adult peaks a year with much higher later peaks in mixed orchards of late apple and early peach. The average deviation between model outputs and actual records for first and second adult peak dates was 2.8 and 3.9 d, respectively, in simulations without an insecticide effect. The deviation decreased when insecticide effects were incorporated into the model. We also performed a sensitivity analysis of our model, and suggest possible applications of the model.     

The interplay of sex ratio, male success and density-independent mortality affects population dynamics

Environmental constraints can limit a population to a certain size, which is usually called the carrying capacity of a habitat. Besides to this ‘external’ factor, which is mainly determined by the limitation of resources, we investigate here another set of population-intrinsic factors that can limit a population size significantly below the maximum sustainable size. Firstly, density-independent mortality is a prominent factor in all organisms that show age-related and/or accidental death. Secondly, in sexually reproducing organisms the sex ratio and the success of pairing is important for finding reproductive partners. Using a simple model, we demonstrate how sex ratio, mating success and gender-specific mortality can strongly affect the speed of population growth and the maximum population size. In addition, we demonstrate that density-independent mortality, which is often neglected in population models, adds a very important feature to the system: it strongly enhances the negative influence of unbiased sex ratios and inefficient pairing to the maximum sustainable population size. A decrease of the maximum population size significantly affects a population's survival chance in inter-specific competition. Thus, we conclude that the inclusion of density-independent mortality is crucial, especially for models of species that reproduce sexually. We show that density-independent mortality, together with biased sex ratios, can significantly lower the abilities of a population to survive in conditions of strong inter-specific competition and due to the Allee effect. We emphasize that population models should incorporate the sex ratio, male success and density-independent mortality to make plausible predictions of the population dynamics in a gender-structured population. We show that the population size is limited by these intrinsic factors. This is of high ecological significance, because it means that there will always be resources available in any habitat that allows other species (e.g., invaders) to use these resources and settle successfully, if they are sufficiently adapted.     

A Voronoi diagram based population model for social species of wildlife

A population model is presented that accounts for spatial structure within habitat patches. It is designed for social species of wildlife that form social group home ranges that are much smaller than patch size. The model represents social group home ranges by Voronoi regions that tessellate a patch to form a Voronoi diagram. Neighbouring social groups are linked with habitat-confined shortest paths and form a dispersal network. The model simulates population dynamics and makes use of Voronoi diagrams and dispersal networks as a spatial component. It then produces density maps as outputs. These are maps that show predicted animal densities across the patches of a landscape. A construction procedure for the particular Voronoi diagram type used by the model is described. As a test case, the model is run for the squirrel glider (Petaurus norfolcensis), a small arboreal marsupial native to Australia. A time series of density maps are produced that show squirrel glider density changing across a landscape through time.     

Characterising populations living close to intensive farming and composting facilities in England

• Bioaerosol emitted from farming and composting facilities may pose health risks. • We describe population characteristics around these sites and infer public concern. • Sites were mapped and overlaid with population, demographic and school data. • Approximately 16% of the population and 15% of schools are located near these sites. • More community health studies need to be conducted around these sites. Bioaerosol exposure has been linked to adverse respiratory conditions. Intensive farming and composting facilities are important anthropogenic sources of bioaerosols. We aimed to characterise populations living close to intensive farming and composting facilities. We also infer whether the public are becoming more concerned about anthropogenic bioaerosol emissions, using reports of air pollution related incidents attributed to facilities. We mapped the location of 1,257 intensive farming and 310 composting facilities in England in relation to the resident population and its characteristics (sex and age), area characteristics (deprivation proxy and rural/urban classification) and school locations stratified by pre-defined distance bands from these bioaerosol sources. We also calculated the average number of air pollution related incidents per year per facility. We found that more than 16% of the population and 15% of schools are located within 4,828 m of an intensive farming facility or 4,000 m of a composting facility; few people (0.01%) live very close to these sites and tend to be older people. Close to composting facilities, populations are more likely to be urban and more deprived. The number of incidents were attributed to a small proportion of facilities; population characteristics around these facilities were similar. Results indicate that populations living near composting facilities (particularly>250 to≤4,000 m) are mostly located in urban areas (80%–88% of the population), which supports the need for more community health studies to be conducted. Results could also be used to inform risk management strategies at facilities with higher numbers of incidents.     

西安黑河流域水体细菌群落分布调查与研究

利用常规细菌培养方法进行分离鉴定,检测黑河流域水体和底泥中的细菌群落,并与水库建成前进行比较,以期对现阶段西安黑河水体微生物分布状况进行分析。结果表明:现阶段黑河水样中细菌群落总数为3 10~800cfu/mL,底泥中细菌群落总数为20×10 3~1100×10 3cfu/m L,主要以气单胞菌属(Aeromonas)、芽孢杆菌属(Bacillus)和微球菌属(Micrococcas)为细菌优势菌群,水库建成前水体中存在的大肠杆菌和占较大比重的条件致病菌无色细菌属和假单胞菌属等此次都没有检测出,表明经过近年来的综合治理,黑河水源得到了较好的保护;但是从微生物角度仍然存在着一定的环境风险。     

Dynamics of a chemostat with three competitive hydrogen oxidizing denitrifying microbial populations and their efficiency for denitrification

In this work, competition for two nitrogen resources (nitrate-, nitrite-nitrogen) between three hydrogen oxidizing denitrifying populations (Acidovorax sp. strain Ic3 (X₁), Paracoccus sp. strain Ic1 (X₂), and Acinetobacter sp. strain Ic2 (X₃)) was examined. The dynamics of three systems of microbial populations (system I: X₁ − X₃, system II: X₂ − X₃, and system III: X₁ − X₂ − X₃), grown in a chemostat, was studied using bifurcation analysis. The chemostat is the most common type of biological reactor used for the study of microbial growth under controlled conditions. The effect of the operating parameters (i.e., dilution rate and feed nitrate nitrogen concentration) on the long-term behavior of the systems showed that X₃ was the predominant population for a wide range of combinations of dilution rate and feed nitrate nitrogen concentration. Also, coexistence of two populations (X₂X₃, X₁X₃) was observed. The results of the bifurcation analysis were also used to determine the denitrification rate and the nitrite nitrogen accumulation for each of the three systems as a function of the dilution rate (up to 0.17 h⁻¹) and the feed nitrate nitrogen concentration (up to 300 mg/L). The highest denitrification rate was achieved by system I (28 mg/Lh). A comparison between the three systems showed that the nitrite nitrogen concentration in system I was less than the one in system III, while the two systems gave similar denitrification rates. The second system had the greatest accumulation of nitrites with the lowest denitrification rate.