982 resultados para Archie Carr National Wildlife Refuge


Relevância:

20.00% 20.00%

Publicador:

Resumo:

The fishery resources of Lake George and Ugandan waters of Lake Edward are described. The main fish species currently observed in the commercial catches were determined and the reasons of changes in species composition of the catches. that occurred in the recent years, are explained. The fishing activity and some economic and nutritional aspects of four fishing villages, selected among the ten present within the Queen Elizabeth National Park boundaries, are analyzed, In the end some suggestions are given for management of the fishery resources of these lakes.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Thyroid hormones (THs) play an important role in the normal development and physiological functions in fish. Environmental chemicals may adversely affect thyroid function by disturbing gene transcription. Perfluorooctane sulfonate (PFOS), a persistent compound, is widely distributed in the aquatic environment and wildlife. In the present study, we investigated whether PFOS could disrupt the hypothalamic-pituitary-thyroid (HPT) axis. Zebrafish embryos were exposed to various concentrations of PFOS (0, 100, 200 and 400 mu g L-1) and gene expression patterns were examined 15 d post-fertilization. The expression of several genes in the HIPT system, i.e., corticotropin-releasing factor (CRF), thyroid-stimulating hormone (TSH), sodium/iodide symporter (NIS), thyroglobulin (TG), thyroid peroxidase (TPO), transthyretin (TTR), ioclothyronine deiodinases (Dio1 and Dio2) and thyroid receptor (TR alpha and TR beta), was quantitatively measured using real-time PCR. The gene expression levels of CRF and TSH were significantly up-regulated and down-regulated, respectively, upon exposure to 200 and 400 mu g L-1 PFOS. A significant increase in NIS and Diol gene expression was observed at 200 mu g L-1 PFOS exposure, while TG gene expression was down-regulated at 200 and 400 mu g L-1 PFOS exposure. TTR gene expression was down-regulated in a concentration-dependent manner. Up-regulation and down-regulation of TR alpha and TR beta gene expression, respectively, was observed upon exposure to PFOS. The whole body thyroxine (T-4) content remained unchanged, whereas triiodothyronine (T-3) levels were significantly increased, which could directly reflect disrupted thyroid hormone status after PFOS exposure. The overall results indicated that PFOS exposure could alter gene expression in the HPT axis and that mechanisms of disruption of thyroid status by PFOS could occur at several steps in the synthesis, regulation, and action of thyroid hormones. (C) 2009 Elsevier Ltd. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Polyfluorinated and perfluorinated compounds (PFCs) are used in numerous commercial products and have been ubiquitously detected in the environment as well as in the blood of humans and wildlife. To assess the combined effects caused by PFCs in mixtures, gene expression profiles were generated using a custom cDNA microarray to detect changes in primary cultured hepatocytes of rare minnows exposed to six individual PFCs (perfluorooctanoic acid, perfluorononanoic acid, perfluorodecanoic acid, perfluorododecanoic acid, perfluorooctane sulfonate, and 8:2 fluorotelomer alcohol) and four formulations of the PFCs mixtures. Mixtures as well as individual compounds consistently regulated a particular gene set, which suggests that these conserved genes may play a central role in the toxicity mediated by PFCs. Specifically, a number of genes regulated by the mixtures were identified in this study, which were not affected by exposure to any single component. These genes are implicated in multiple biological functions and processes, including fatty acid metabolism and transport, xenobiotic metabolism, immune responses, and oxidative stress. More than 80% of the altered genes in the PFOA- and PFOS-dominant mixture groups were of the same gene set, while the gene expression profiles from single PFOA and PFOS exposures were not as similar. This work contributes to the development of toxicogenomic approaches in combined toxicity assessment and allows for comprehensive insights into the combined action of PFCs mixtures in multiple environmental matrices. (C) 2009 Elsevier B.V. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Perfluorooctane sulfonate (PFOS) is widely distributed and persistent in the environment and in wildlife, and it has the potential for developmental toxicity. However, the molecular mechanisms that lead to these toxic effects are not well known. In the present study, proteomic analysis has been performed to investigate the proteins that are differentially expressed in zebrafish embryos exposed to 0.5 mg/l PFOS until 192 h postfertilization. Two-dimensional electrophoresis coupled with mass spectrometry was employed to detect and identify the protein profiles. The analysis revealed that 69 proteins showed altered expression in the treatment group compared to the control group with either increase or decrease in expression levels (more than twofold difference). Of the 69 spots corresponding to the proteins with altered expression, 38 were selected and subjected to matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (TOF/TOF) analysis; 18 proteins were identified in this analysis. These proteins can be categorized into diverse functional classes such as detoxification, energy metabolism, lipid transport/steroid metabolic process, cell structure, signal transduction, and apoptosis. Overall, proteomic analysis using zebrafish embryos serves as an in vivo model in environmental risk assessment and provides insight into the molecular events in PFOS-induced developmental toxicity.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This is the first to conduct Simultaneous determination of microcystin (MC) contaminations in multi-groups of vertebrates (fish, turtle, duck and water bird) from Lake Taihu with Microcystis blooms. MCs (-RR, -YR, -LR) in Microcystis scum was 328 mu g g(-1) DW. MCs reached 235 mu g g(-1) DW in intestinal contents of phytoplanktivorous silver carp, but never exceeded 0.1 mu g g(-1) DW in intestinal contents of other animals. The highest MC content in liver of fish was in Carassius auratus (150 ng g(-1) DW), followed by silver carp and Culter ilishaeformis, whereas the lowest was in common carp (3 ng g(-1) DW). In livers of turtle, duck and water bird, MC content ranged from 18 to 30 ng g(-1) DW. High MC level was found in the gonad, egg yolk and egg white of Nycticorax nycticorax and Anas platyrhynchos, suggesting the potential effect of MCs on water bird and duck embryos. High MC contents were identified for the first time in the spleens of N. nycticorax and A. platyrhynchos (6.850 and 9.462 ng g(-1) DW, respectively), indicating a different organotropism of MCs in birds. Lakes with deaths of turtles or water birds in the literatures had a considerably higher MC content in both cyanobacteria and wildlife than Lake Taihu, indicating that toxicity of cyanobacteria may determine accumulation level of MCs and consequently fates of aquatic wildlife. (C) 2009 Elsevier B.V. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Perfluorooctane sulfonate (PFOS) is widely distributed and persistent in the environment and wildlife. The main aim of this study was to investigate the impact of long-term exposure to low concentrations of PFOS in zebrafish. Zebrafish fry (F-0, 14d post-fertilization, dpf) were exposed via the water for 70d to 0 (control), 10, 50 and 250 mu g L-1 PFOS, followed by a further 30d to assess recovery in clean water. The effects on survival and growth parameters and liver histopathology were assessed. Although growth suppression (weight and length) was observed in fish treated with high concentrations PFOS during the exposure period, no mortality was observed throughout the 70d experiment. Embryos and larvae (F-1) derived from maternal exposure suffered malformation and mortality. Exposure to 50 and 250 mu g L-1 PFOS could inhibit the growth of the gonads (GSI) in the female zebrafish. Histopathological alterations, primary with lipid droplets accumulation, were most prominently seen in the liver of males and the changes were not reversible, even after the fish were allowed to recover for 30d in clean water. The triiodothyronine (T-3)) levels were not significantly changed in any of the exposure groups. Hepatic vitellogenin (VTG) gene expression was significantly up-regulated in both male and female zebrafish, but the sex ratio was not altered. The overall results suggested that lower concentrations of PFOS in maternal exposure could result in offspring deformation and mortality. (c) 2008 Elsevier Ltd. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The purpose of this study was to investigate polychlorinated biphenyls (PCBs) contamination in tilapia (Oreochromis mossambicus) collected from the Manna stream and Ala Wai Canal of O'ahu, an island of the geographically isolated Hawaiian archipelago. Our results show that the average concentrations of PCBs varied from 51.90 to 89.42 ng g(-1) lipid weight for the sampling sites. Relative toxic potencies (RTPs) and toxic equivalencies (TEQs) were determined to be 20.38-40.60 ng TCDD g(-1) lipid weight and 2.89-4.17 ng TEQ g(-1) lipid weight by 7-ethoxy-resorufin-O-deethylase (EROD) activity analysis and calculation of PCB concentrations based on toxic equivalency factors (TEFs), respectively. Penta-chlorinated congeners were found to be predominant, which revealed that Aroclor 1254 was a possible major source of PCBs in our fish samples. PCB 118, an indicator PCBs, constituted more than 55% and 30% of the total PCBs and TEQs, respectively. In addition, PCB 118 was found to have a linear correlation to the total PCBs (R = 0.975) and TEQs (R = 0.782). Detection of concentrated PCBs in Hawaiian waters suggests a potentially adverse impact of this pollutant on human health, as well as ecological systems, and suggests the necessity of environmental monitoring and hazard assessment of PCBs within the Hawaiian Islands. (c) 2008 Published by Elsevier Ltd.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The global trend towards urbanization means that over half of the world's population now lives in cities. Cities use energy in different proportions to national energy use averages, typically corresponding to whether a country is industrialized or developing. Cities in industrialized countries tend to use less energy per capita than the national average while cities in developing countries use more. This paper looks at existing World Bank data in respect to urban energy consumption, the emissions inventory work done by New York City, and discusses how this data highlights the need for a focus on: energy policy for buildings in industrialized cities; masterplanning and new construction standards in developing cities; and how urban energy policy can become more effective in reducing urban greenhouse gas emissions.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Reproductive behaviors are poorly known for the Yangtze finless porpoise Neophocaena phocaenoides asiaeorientalis. In this study, the parentage of an isolated Yangtze finless porpoise population inhabiting the Yangtze Tian-e-Zhou Baiji National Natural Reserve is determined by analysis of microsatellite loci and mitochondrial DNA (mtDNA) control region sequences, and the porpoise's reproductive behaviors are studied. Overall 4 full parentage assignments and additional 3 single parentage assignments were determined for the population of 23 individuals. The analysis shows that their estimated reproductive cycle is shorter than that reported previously and there probably exists an overlapping between gestation and lactation period. The Study also shows that the female does not show fidelity to a particular male for breeding and vice versa, the oldest males did not monopolize mating and the dominance rank could not be so strict for the porpoise society. Moreover, the porpoise's mating pattern and relatedness among candidate parents are discussed here. These results provide important information for making guidelines of management and conservation for this protected population.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

中国拥有92466 Km2的各类高原湿地,具有湿地退化、过度放牧等相似特征,保护与利用矛盾突出。高寒湿地保护区尽管在制度上以核心区、缓冲区来约束当地的放牧等外来干扰行为,但在实际管理中却不能起到应有的作用。 本研究以四川若尔盖湿地国家级自然保护区为例,应用3S技术,建立保护区多功能动态分区工作流模型,通过不同植被类型的识别和空间特征分析、不同动物类群在上述植被生境中的时空分布特征分析、保护区主要干扰因素的时空分布特征分析,突出对保护区主要保护对象(湿地生态系统)的保护,对保护区进行管理分区,依据野生动物利用特征和植被生长特征对核心区进行年周期动态利用,缓解保护与发展的矛盾,促进保护区的优化管理。 应用归一化植被指数(NDVI)与植被盖度的相关性,将归一化植被指数(NDVI)转化为植被盖度指数(MDVI),结合保护区牧场划分和时空利用特征专家经验,结果表明,MDVI值在1-139之间主要代表着水体、裸地、沙地等;MDVI140-256为草地和高山灌丛;MDVI210是当地夏牧场和秋冬牧场的划分区间值。 合理的区划需要资金、技术和政策的支持,为保证保护区多核心动态分区的实施,本研究提出了生态工程、牧业发展方式转变、湿地特色产业发展、湿地政策、社区参与和科技支撑等六大保障措施。 In China, 92466 Km2 highland or frigid wetlands are (were) facing major management problems, such as wetland degradation and overgazing. Conflict between conservation and utilization on those wetlands can be found anywhere today. Although many nature reserves have been setup for protection of frigid wetland, and core and buffer zone has been declared to forbid any kinds of disturbance, local farmers still use these areas for grazing. As an example by Sichuan Roige Wetlands National Nature Reserve(SRWNRR), we set up a 3S flow model to analyze the character of year-round distribution patters of vegetation, wildlife, and grazing. Combined and overlapped these characters together, we select multi-core zone and buffer zone, then define a dynamic management period in different zone to optimize protection wetland in the reserve. Normalized Difference Vegetation Index(NDVI)is highly related with coverage of vegetation. When convert NDVI to MDVI (coverage index, 1-256), index 139 and 210 can be as inflexion to distinguish among water/sand/bared land, summer pasture, and autumn / winter pasture. We use these to select different layers and analyze grazing pattern. To be more realistic, we put forward some strategies to support our multi-core and dynamic management of wetland in Roige, including ecological restoration engineering, changing of stock raising industry, changing of wetland policy, community based management and technology renovation supports.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The broad acceptance and collective commitment of countries to the tasks involved in the implementation of Agenda 21, Chapter 17, have profound implications vis-à-vis the interplay between coastal zone management (CZM) and national development planning (NDP). It appears that in many countries, CZM has evolved in isolation from the mainstream of national development processes. The paper examines various forms and elements for the effective integration of CZM into NDP.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Several methods for estimating the potential impacts caused by multiple probabilistic risks have been suggested. These existing methods mostly rely on the weight sum algorithm to address the need for integrated risk assessment. This paper develops a nonlinear model to perform such an assessment. The joint probability algorithm has been applied to the model development. An application of the developed model in South five-island of Changdao National Nature Reserve, China, combining remote sensing data and a GIS technique, provides a reasonable risk assessment. Based on the case study, we discuss the feasibility of the model. We propose that the model has the potential for use in identifying the regional primary stressor, investigating the most vulnerable habitat, and assessing the integrated impact of multiple stressors. (C) 2006 Elsevier Ltd. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

How coniferous trees in northern China changed their distribution ranges in response to Quaternary climatic oscillations remains largely unknown. Here we report a study of the phylogeography of Pinus tabulaeformis, an endemic and dominant species of coniferous forest in northern China. We examined sequence variation of maternally inherited, seed-dispersed mitochondrial DNA (mtDNA) (nad5 intron 1 and nad4/3-4) and paternally inherited, pollen- and seed-dispersed chloroplast DNA (cpDNA) (rpl16 and trnS-trnG) within and among 30 natural populations across the entire range of the species. Six mitotypes and five chlorotypes were recovered among 291 trees surveyed. Population divergence was high for mtDNA variation (G(ST) = 0.738, N-ST = 0.771) indicating low levels of seed-based gene flow and significant phylogeographical structure (N-ST > G(ST), P < 0.05). The spatial distribution of mitotypes suggests that five distinct population groups exist in the species: one in the west comprising seven populations, a second with a north-central distribution comprising 15 populations, a third with a southern and easterly distribution comprising five populations, a fourth comprising one central and one western population, and a fifth comprising a single population located in the north-central part of the species' range. Each group apart from the fourth group is characterized by a distinct mitotype, with other mitotypes, if present, occurring at low frequency. It is suggested, therefore, that most members of each group apart from Group 4 are derived from ancestors that occupied different isolated refugia in a previous period of range fragmentation of the species, possibly at the time of the Last Glacial Maximum. Possible locations for these refugia are suggested. A comparison of mitotype diversity between northern and southern subgroups within the north-central group of populations (Group 2) showed much greater uniformity in the northern part of the range both within and between populations. This could indicate a northward migration of the species from a southern refugium in this region during the postglacial period, although alternative explanations cannot be ruled out. Two chlorotypes were distributed across the geographical range of the species, resulting in lower levels of among-population chlorotype variation. The geographical pattern of variation for all five chlorotypes provided some indication of the species surviving past glaciations in more than one refugium, although differentiation was much less marked, presumably due to the greater dispersal of cpDNA via pollen.