Effects of environmental factors on the seasonally change of phytoplankton populations in a closed freshwater pond.

The effect of environmental factors affecting the population dynamic of phytoplankton population was studied seasonally in a closed freshwater pond with the natural water of Lake Kasumigaura, Japan. The predominant phytoplankton species in the pond were classified as Oscillatoria tenuis, Synedra ulna, Chlamydomonas cingulata and Cyclotella kutzingiana, with dominant species of Melosira italica, Synechococcus sp. and Cryptomonas ovata. The most important limiting factor for filament length and cell size of most of the phytoplankton community was temperature. Availability of most nutrients had profound effects on the phytoplankton growth as nonlimiting factors. Based on our results, it is suggested that cell cycle progression was also temporally regulated by a multiplicity of external factors such as temperature, nutrients, dissolved oxygen (DO) and pH. At high pH and high temperature, consistent increase of cell division of some phytoplanketers such as Synedra, Cyclotella, Chlamydomonas and Melosira occurs, and there also may be species-specific responses for other species of phytoplankters. In addition, the cell divisions of phytoplankters are differentially regulated in different phytoplankton species.     

Growth rate,reproductive capacity,and survival rate of European water voles taken from natural populations at different phases of the population cycle

Growth rate, reproductive characteristics, and survival rate of European water voles taken from the population at the peak, decline, depression, and increase phases of population cycle were compared under standard vivarium conditions. In November to March, the growth rate of decline-phase males was higher, while that of decline-phase females was lower than in other animals. Decline-phase males were also more successful in reproduction than males taken at other phases. The survival rate of decline-phase females was reduced in the winter period.     

Ecophysiological indicators of the state of animal populations exposed to damaging factors

Indices of abundance and reproduction rate are considered in some groups of aquatic and terrestrial vertebrates from the zones of technogenic disasters. Upon a critical population decline caused by external destructive factors, such as emissions of acute ecotoxicants, the ecophysiological and behavioral compensatory mechanisms are activated, which provide for restoration of the total population size to the optimum within a short period of time. Environmental pollution with substances disturbing the reproductive function has the gravest consequences for animals. In this case, population size may remain fairly high, and, therefore, the effect of enhanced reproduction as a response to population decline does not take place, which eventually leads to a gradual but irreversible destruction of the population. Pathologies of reproduction should be used as a criterion for assessing the state of animals in the zones of technogenic disasters.Translated from Ekologiya, No. 1, 2005, pp. 32–38.Original Russian Text Copyright © 2005 by Shilova, Shatunovskii.     

Demographic structure of Siberian roe deer (Capreolus pygargus Pall.) population in central Yakutia

The dynamics of the sex and age structure of Siberian roe deer in central Yakutia has been analyzed over the period from 1998 to 2011. In the snowy winter of 2004, mass migration and high mortality of the animals were recorded. The following shift of the adult sex ratio in favor of females and increase in the proportion of calves provided for rapid population recovery. Climate warming, accompanied by increase in the amount of snow, has impaired living conditions for Siberian roe deer. Realization of the species reproductive potential is restrained by natural and anthropogenic elimination factors, and prospects for future population growth are poor.     

Ecology of reproduction of the red king crab

Conditions for reproduction of the red king crab Paralithodes camtschatica (Tilesius) on scallop plantations in Primorye have been studied. It has been found that the settling of larvae and the growth of juveniles to the size sufficient for their survival take place only in the cleanest water areas of Peter the Great Bay. Solar activity (expressed as the Wolfer number) is one of the most important abiotic factors affecting P. camtschatica reproduction. The population dynamics of juvenile crabs are characterized by fluctuations with two-year and five-year cycles.     

The South Australian lobster fishery management model

Modelling the rock lobster (Jasus edwardsii) fishery in South Australia was the focus of a three-year data gathering program. In collaboration with fishers, a tool for assisting in the sustainable management of the resource was developed. The goal was to test management policies to allow increases in reproductive output while enhancing economic yield. The model's user interface was developed to an ease of use comparable to commercial software for use by fishers in comanagement of the resource. This paper describes the modelling framework, user interface, and results for management strategies under consideration. The framework is comprised of five principle submodels: catch, effort, growth, economics, and population reproduction, with the lobster population divided into 8 mm length classes by sex and spatial cell. The mortality of lobsters occurs by commercial harvest, natural mortality, incidental release mortality, predation inside pots before retrieval, illegal harvesting, and recreational catch. Five categories of management control scenario were simulated: catch quota, effort regulation (as total pot retrievals), size regulations (allowing minimum, maximum, and mid-range slice length protection), and seasonal and area closures. Model outputs imply that size strategies have limited potential compared with effort limitations and quota.     

Factors affecting the sex ratio in the honeybee mite <Emphasis Type="Italic">Varroa jacobsoni</Emphasis>

Study of the seasonal variation of the sex ratio in the honeybee mite Varroa jacobsoni demonstrated that sex determination was affected by temperature, order of reproductive cycles, and population densities in the host’s brood cell and the honeybee nest. The mechanism of reproduction ensuring adaptation of the mite to parasitism and reproduction on honeybees are discussed.     

Specific Features of the Dynamics of Murine Rodent Communities under the Effects of Urbanization: 2. Maintenance of Population Size

The reproduction dynamics of nonsynanthropic rodents living in urbanized areas was compared with that of rodents from natural communities. The number of females in a community and the number of embryos and placental spots per female were estimated. The mechanisms providing for the maintenance of population size were different in different habitats. In particular, the urban communities of murine rodents proved to have a higher reproductive potential.     

The relative importance of sexual reproduction and clonal propagation in rhizomatous herb Iris japonica Thunb. from two habitats of Jinyun Mountain, Southwest China

Reproductive behaviour of clonal plants might change in contrasting habitats. In field and simulated experiments, we studied the relative importance of sexual reproduction and clonal propagation in rhizomatous herb, Iris japonica Thunb. in two forest habitats (BF, bamboo forest and OAFE, open area of forest edge), and effects of population origin (BF vs. OAFE) and environmental effects (shading) on sexual vs. clonal reproduction. In field experiment, the relative importance of reproduction in I. japonica populations was different in two habitats, which showed predominantly sexual reproduction in OAFE and clonal propagation in BF. In simulated experiment, the effect of population origin and light treatment (shading) was significant for reproduction of I. japonica. Clonal propagation was only influenced by population origin, and sexual reproduction was determined both by population origin and light treatment. A trade-off between two reproductive modes exhibited in both experiments. The trade-offs was more obvious in OAFE than in BF because sexual reproduction, resource and inter-specific competition obviously lacked in BF. The results indicated that the selective forces shaping reproduction of I. japonica in contrasting habitats might demonstrate pronounce adaptive population differentiation among forest habitats. Thus, I. japonica populations formed local differentiation by adaptation of reproduction to local heterogeneous forest habitats.     

A Dynamic model of Cs accumulation by fish of different age classes

A dynamic model of radionuclide accumulation in fish is developed. In the model, the fish population is represented by a set of discrete age classes. Each age class is characterized by a specific growth rate, diet and activity of metabolic processes. The model describes all known types of size effect in the contamination of fish with radiocaesium. The detailed dynamics of ¹³⁷Cs accumulation by fish are demonstrated using the results of the model's application to ichtiofauna in a water body which has a high level of contamination with radiocaesium — namely, the cooling pond of the Chernobyl NPP.     

A performance appraisal of size dependent reproduction and reproductive allocation: A case study of two <Emphasis Type="Italic">Inula</Emphasis> species from Kashmir Himalaya

In this study we investigated the size-dependent reproductive pattern of Inula racemosa and I. royleana (Asteraceae) growing at different reaches in the environs of the Kashmir Himalaya. Size effects on reproductive pattern were evaluated by determining the size-dependency of flowering probability and reproductive effort. The results showed that the probability of flowering increased significantly with the size of the plant in all populations, indicating that individuals do not flower until they reach a threshold size and considerable between-site differences were found in the slope and the intercept of the regression between plant size and flower production. In I. racemosa, populations at high altitudes had significantly lower threshold sizes for reproduction and showed sharp increase in flowering probability with plant size, compared to other populations at lower altitudes. However, no pattern in size-dependent flower production was found relative to the altitude in I. royleana, as flower production at some sites, at high altitudes, increased more steeply with plant size than at other sites. For both taxa, reproductive effort decreased allometrically as adults grew, as can be interpreted from the allometric relationship between reproductive and vegetative biomass. Further studies are required to determine whether population differentiation in size-dependent reproductive pattern is maintained by selection.     

Ecological impacts of umbrella effects of radiation on the individual members

In order to study the interactions in a model aquatic microcosm, an individual-based computer simulation model was developed. The microcosm consists of Euglena gracilis as an autotroph algae, Tetrahymena thermophila as a heterotroph protozoa and Escherichia coli as a saprotroph bacteria. There exists a strong interaction between Tetrahymena and E. coli as the first is the predator of the second. Ecological toxicity tests were conducted to test the population level impacts of the biological effects of radiation and toxicants on the lethality and mobility factors that influence directly or indirectly growth and reproduction. Radiological effects on lethality of E. coli individuals were translated to the reduction of the equilibrium population of Tetrahymena. A synergistic effect at the community level was also observed by the simulation of a combined exposure of radiation and a toxicant which reduced the feeding efficiency of Tetrahymena.     

Modelling the propagation of effects of chronic exposure to ionising radiation from individuals to populations

This study evaluated the potential effect of ionising radiation on population growth using simple population models and parameter values derived from chronic exposure experiments in two invertebrate species with contrasting life-history strategies. In the earthworm Eisenia fetida, models predicted increasing delay in population growth with increasing gamma dose rate (up to 0.6 generation times at 11 mGy h(-1)). Population extinction was predicted at 43 mGy h(-1). In the microcrustacean Daphnia magna, models predicted increasing delay in population growth with increasing alpha dose rate (up to 0.8 generation times at 15.0 mGy h(-1)), only after two successive generations were exposed. The study examined population effects of changes in different individual endpoints (including survival, number of offspring produced and time to first reproduction). Models showed that the two species did not respond equally to equivalent levels of change, the fast growing daphnids being more susceptible to reduction in fecundity or delay in reproduction than the slow growing earthworms. This suggested that susceptibility of a population to ionising radiation cannot be considered independent of the species' life history.     

长三角地区一体化背景下的人口优化布局研究

人口问题是制约区域全面协调可持续发展的重大问题，是影响区域经济社会发展的关键因素。作为我国重要的经济核心区，长三角地区经济和人口快速集聚，近年来出现了中心城市人口过度膨胀、生态环境敏感区受到挤占、后发地区人口集聚动力不足等问题。从长三角地区一体化发展要求出发，合理布局该区域的人口，已经成为该地区迫切需要解决的问题之一。利用统计数据和GIS空间分析方法，采用多种模型对本区人口规模与增长、人口空间分布特征进行分析，在人口预测与适宜性评价的基础上优化和调控长三角地区的人口布局，将研究区域划分为优化增长区、快速增长区、较快增长区、限制增长区等人口增长类型区     

Postnatal growth and development of the northern mole vole in natural populations in the northwestern part of its range

Long-term studies (1975–1999) and large amounts of field data (collections and observations on marked animals) have been used to analyze the growth and development of the northern mole vole (Ellobius talpinus Pall., 1770). Data are presented on the postnatal development and life spans of particular age groups of this species and on the dynamics of growth and life spans in the resident and migrant parts of the population. It is shown that the population is divided into slowly growing and rapidly growing groups, which is related to population dynamics. The timing of sexual maturation of the northern mole vole depending on the time of birth is clarified. It is shown that stable reproduction of this underground species is accounted for by the presence of seasonal generations.     

Sediment quality in Rio Guadiamar (SW, Spain) after a tailing dam collapse: contamination, toxicity and bioavailability

An integrated assessment of sediment quality in the Guadiamar River after a mining spill was conducted. The concentration of different metals and other conventional parameters were measured in sediments located along the river. Four sediment toxicity tests (Hyalella azteca 28-day survival and growth test; Chironomus riparius 10-day survival and growth test; Hexagenia spp. 21-day survival and growth test; and Tubifex tubifex 28-day reproduction and survival test) were carried out to determine the effects associated with the accidental spill. The geochemical fractions of 6 metals (Fe, Mn, Zn, Cu, Pb, and Cd) were determined to establish the bioavailability of the metals. The relationship found in the concentrations of metals associated with the mobile fractions of the sediments in the sites studied is similar to the toxic mud from tailing pond and confirms that the toxic effects are associated with the metals Zn and Cd originating from the spill.     

Cumulative health risk assessment of 17 perfluoroalkylated and polyfluoroalkylated substances (PFASs) in the Swedish population

Humans are simultaneously exposed to a multitude of chemicals. Human health risk assessment of chemicals is, however, normally performed on single substances, which may underestimate the total risk, thus bringing a need for reliable methods to assess the risk of combined exposure to multiple chemicals. Per- and polyfluoroalkylated substances (PFASs) is a large group of chemicals that has emerged as global environmental contaminants. In the Swedish population, 17 PFASs have been measured, of which the vast majority lacks human health risk assessment information. The objective of this study was to for the first time perform a cumulative health risk assessment of the 17 PFASs measured in the Swedish population, individually and in combination, using the Hazard Index (HI) approach. Swedish biomonitoring data (blood/serum concentrations of PFASs) were used and two study populations identified: 1) the general population exposed indirectly via the environment and 2) occupationally exposed professional ski waxers. Hazard data used were publicly available toxicity data for hepatotoxicity and reproductive toxicity as well as other more sensitive toxic effects. The results showed that PFASs concentrations were in the low ng/ml serum range in the general population, reaching high ng/ml and low μg/ml serum concentrations in the occupationally exposed. For those congeners lacking toxicity data with regard to hepatotoxicity and reproductive toxicity read-across extrapolations was performed. Other effects at lower dose levels were observed for some well-studied congeners. The risk characterization showed no concern for hepatotoxicity or reproductive toxicity in the general population except in a subpopulation eating PFOS-contaminated fish, illustrating that high local exposure may be of concern. For the occupationally exposed there was concern for hepatotoxicity by PFOA and all congeners in combination as well as for reproductive toxicity by all congeners in combination, thus a need for reduced exposure was identified. Concern for immunotoxicity by PFOS and for disrupted mammary gland development by PFOA was identified in both study populations as well as a need of additional toxicological data for many PFAS congeners with respect to all assessed endpoints.     

生态恢复过程中的种群遗传学考虑

生态恢复是生态科学的最终实验，从种群角度看，恢复的目标是使种群（尤其是优势种或建群种）到具有生长、繁殖和适应进化变化的能力。要达到这个目标，种群遗传学知识必不可少。遗传变异是物种适应变化环境的基础，而局部适应则是种群适应局部环境遗传分化的结果，它们在生态恢复中起着重要的作用。分析了生态恢复过程中影响种群遗传变异因素，主要有取样误差和小种群效应（主要是瓶颈或建立者事件及其以后的近交和漂变等），在进行     

Projecting current and potential future distribution of the Fire-bellied toad Bombina bombina under climate change in north-eastern Germany

Environmental change is likely to have a strong impact on biodiversity, and many species may shift their distribution in response. In this study, we aimed at projecting the availability of suitable habitat for an endangered amphibian species, the Fire-bellied toad Bombina bombina, in Brandenburg (north-eastern Germany). We modelled a potential habitat distribution map based on (1) a database with 10,581 presence records for Bombina from the years 1990 to 2009, (2) current estimates for ecogeographical variables (EGVs) and (3) the future projection of these EGVs according to the statistical regional model, respectively, the soil and water integrated model, applying the maximum entropy approach (Maxent). By comparing current and potential future distributions, we evaluated the projected change in distribution of suitable habitats and identified the environmental variables most associated with habitat suitability that turned out to be climatic variables related to the hydrological cycle. Under the applied scenario, our results indicate increasing habitat suitability in many areas and an extended range of suitable habitats. However, even if the environmental conditions in Brandenburg may change as predicted, it is questionable whether the Fire-bellied toad will truly benefit, as dispersal abilities of amphibian species are limited and strongly influenced by anthropogenic disturbances, that is, intensive agriculture, habitat destruction and fragmentation. Furthermore, agronomic pressure is likely to increase on productive areas with fertile soils and high water retention capacities, indeed those areas suitable for B. bombina. All these changes may affect temporary pond hydrology as well as the reproductive success and breeding phenology of toads.     

Hunting Selectivity and Its Influence on the Structure of Sable Populations in the Cis-Ural Region

The structure of commercial sable samples from the Cis-Ural region was studied taking into account hunting method (shooting or trapping). The proportion of adult animals was found to be significantly lower in samples taken during the first half of the hunting season, compared to the second half, indicating predominant harvesting of young animals. To estimate the degree of hunting selectivity (I), the ratios of demographic groups among shot and trapped animals were calculated. The results confirmed the fact of selective hunting for underyearlings both by shooting (I = 1.49–1.60 for the Cis-Ural region and I = 2.46–3.37 for the Western Sayan Mountains) and by trapping (I = 2.80–4.37), especially during the first half of winter. Samples taken during the second half of the season were characterized by prevalence of adult animals making up the reproductive core of the population (I = 1.43–2.07). It is considered that the process of reproduction in Cis-Ural sable populations in the 1960s to 1980s was stimulated by intensive commercial hunting. To maintain reproduction of sable populations at a safe level, it is necessary to reduce the period of hunting in the first quarter of the year. It is proposed to use the phenomenon of hunting selectivity for managing sable populations, regulating their exploitation, and improving the economic productivity of habitats. Commercial hunting in terms of its impact on the population can act as a factor of conscious or unconscious artificial selection.