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干旱半干旱区湿地生态系统服务功能对区域环境具有重要的意义.乌梁素海是世界半荒漠地区极为少见的具有很高生态效益的大型多功能湖泊,为典型的草型水体富营养化湖泊.乌梁素海因其独特的地理位置而具有水质净化、野生动物栖息地、野生动物的食物来源地等重要的生态功能,是优越的栖息繁殖和避难场所,是中亚线路的必经之地.近年来,乌梁素海连续暴发了“黄苔”事件,湖泊生态的健康出现了问题,生态的服务功能让人担忧.文章从乌梁素海的生态健康状况入手,分析了生态健康与生态服务功能的变化,特别关注湿地对鸟类营养供给水平的能力,分析了栖息地鸟类的动态演变,对湖泊生态健康变化中的鸟类生态安全问题进行了诠释.分析认为,虽然乌梁素海水质劣,渔业功能下降,但生物量总量变化小,鸟类的种群及数量均有增加. 相似文献
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为了研究冬季乌梁素海浮游藻类群落结构特征,于2012年11月至2013年2月对乌梁素海的浮游植物群落结构及水环境状况进行了调查。结果显示,在采集的32个水样中共采集到浮游植物8门66属。其中,绿藻门20属、硅藻门18属、蓝藻门16属、裸藻门6属、隐藻门、甲藻门各2属,金藻门、黄藻门各1属。冬季乌梁素海浮游植物的种群数量较高,平均数量达3.27×107cell/L。优势种群为栅藻属、衣藻属、弓形藻属、镰形纤维藻属、小环藻属、针杆藻属、脆杆藻属、舟形藻属、菱形藻属、裸藻属、席藻属、尖头藻属、平裂藻属。依据所测定的各项指标,表明冬季乌梁素海水质处于中富—富营养状态,部分样点处于重富营养状态。相关性分析结果表明:乌梁素海浮游植物数量与水温呈显著的正相关,与透明度、COD呈现负相关。 相似文献
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文章阐述了鱼类种群监测和鱼类毒理实验在环境监测方面的应用,并具体介绍了应用化学鱼类监测法、应用浮藻鱼类监测法以及鱼类急性毒性实验法和鱼类致突变试验法。 相似文献
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《环境科学与技术》2021,44(1):108-114
乌梁素海是深受国际社会关注的湿地生态系统保护区。该文以乌梁素海-地下水系统为研究对象,利用数理统计、水化学类型分析等方法探究地下水化学特征及演变规律。基于对区域水文地质资料收集、现场勘测、水样采集分析的基础上,揭示了乌梁素海流域地下水补径排特征,地表水和地下水的水力联系,进而确定出地下水对乌梁素海水分及盐分的补给量,定量分析了地下水补给对乌梁素海的影响。结果表明:(1)地下水从补给区到排泄区,TDS逐渐增加,水化学类型由重碳酸型到硫酸型再到盐酸型;(2)潜水每年约向湖泊补给2 398.7万m~3,76 785.5 t盐分;承压水每年约向乌梁素海补给889.1万m~3,15 895.4 t盐分。(3)地下水对乌梁素海补给量约占湖泊蓄水量11.0%~13.2%,盐量补给约占湖水含盐量的23.6%~28.3%。近年来开展的生态补水工程,初步抑制了乌梁素海"咸化",基本维持了湿地生态系统稳定。 相似文献
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Cooling water intake systems have the potential to adversely impact aquatic organisms though entrainment and impingement (impacts referenced under 316(b) of the Clean Water Act), yet the loss of individual fish does not necessarily mean that a population will suffer a significant decrease in number. The results of utility sponsored studies on Ohio River fish populations provide strong evidence of positive changes in the fishery due to water quality improvements. Despite these improvements, a simulation is needed to determine if a reduction in 316(b) fish losses would result in higher or similar fish population levels. Electrofishing data collected at seven power plant locations from 1981 to 1998 will be used for the population assessments. Potential 316(b) impacts on Ohio River fish populations will be modeled using site specific 316(b) data and a Leslie matrix model. The theoretical maximum population for various fish species, with and without 316(b) impacts, will be compared and the probabilistic risk that fish populations will fall below the threshold for species survival will be assessed. Historically, EPA has allowed 316(b) to be implemented on a case-by-case basis, however, the utilities believe that the first step in assessing potential adverse environmental impacts is to assess the condition of the affected fish populations. 相似文献
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《Environmental Science & Policy》1999,2(6):465-475
Increasing human population densities and development along the coasts of the United States pose a threat to fish populations through alteration of their habitats due to modification of upland watersheds, increased inputs of nutrient and domestic and agricultural chemicals, and direct habitat replacement or destruction. Injuries to these habitats will in turn affect populations of marine and estuarine organisms. To effectively evaluate the impacts of human activities on essential fish habitat we propose a framework to assess the linkages between fishery habitat alteration and modification and fishery production and community structure in coastal environments. Inherent natural variability makes it difficult to detect changes to the population or community. Therefore, we target structural and functional components of fish habitat as assessment endpoints, rather than the fish populations that utilize those habitats. 相似文献
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Predicting fish population dynamics: compensation and the importance of site-specific considerations
The magnitude of the compensatory response inherent to fish population seems to be questioned with each new generation of scientists and regulators. The major reason for this is the demand by some that compensation be completely understood at the process level before compensation can be factored into population predictions. We first discuss several lines of evidence for the existence of compensation, and the reasons why compensation is so difficult to measure at the process level. We then offer life history theory as a general framework for improving our understanding of the likely magnitude of compensation in fish population dynamics. We use detailed, individual-based models and field data for yellow perch-walleye, striped bass, and a lake community to illustrate the complexity of compensation, and to show that predictions for a particular population require site-specific information. Analyses show that the life stage and magnitude of density-dependence can vary for different populations of the same species, and that population responses can depend on the arrangement of the food web. We must stop reinventing the density-dependence wheel; too many resources (both natural and monetary) are at stake. We suggest using three approaches for addressing the compensation issue: (1) life history theory for providing a sound basis for qualitatively understanding fish population dynamics and the magnitude of compensation; (2) age- and stage-structured matrix models for screening-level analyses to identify populations that may be at unacceptable risks of decline and therefore require additional analyses; and (3) individual-based models for better understanding the complexities of compensation at the process level and for impact assessment of at-risk, well-studied populations. 相似文献
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Cichlids are an excellent model to study explosive speciation and adaptive radiation. Their evolutionary success has been attributed to their ability to undergo rapid morphological changes related to diet, and their particular breeding biology. Relatively minor changes in morphology allow for exploitation of novel food resources. The importance of phenotypic plasticity and genetically based differences for diversification was long recognized, but their relationship and relative magnitude remained unclear. We compared morphology of individuals of four wild populations of the Lake Tanganyika cichlid Tropheus moorii with their pond-raised F(1) offspring. The magnitude of morphological change via phenotypic plasticity between wild and pond-bred F(1) fish exceeds pairwise population differences by a factor of 2.4 (mean Mahalanobis distances). The genetic and environmental effects responsible for among population differentiation in the wild could still be recognized in the pond-bred F(1) fish. All four pond populations showed the same trends in morphological change, mainly in mouth orientation, size and orientation of fins, and thickness of the caudal peduncle. As between population differentiation was lower in the wild than differentiation between pond-raised versus wild fish, we suggest the narrow ecological niche and intense interspecific competition in rock habitats is responsible for consistent shape similarity, even among long-term isolated populations. 相似文献
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渔洞水库水质污染严重,污染源于库区养殖业,过量的化肥、农药施用,生活污水及生活垃圾;库区生态环境脆弱,水土流失加剧,人口过载.为保护水源地,应控制水源污染,控制人口数量,提高人口素质,保护生态环境,实施相关政策及产业结构调整,加大管理力度,以实现库区社会经济与环境的协调发展. 相似文献
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Doug Beare Franz Hölker Georg H. Engelhard Eddie McKenzie David G. Reid 《Die Naturwissenschaften》2010,97(9):797-808
Marine protected areas (MPAs) are attaining increasing importance in the management of marine ecosystems. They are effective
for conservation in tropical and subtropical areas (mainly coral and rocky reefs), but it is debated whether they are useful
in the management of migratory fish stocks in open temperate regions. World War II created a large marine area within which
commercial fishing was prevented for 6 years. Here we analyse scientific trawl data for three important North Sea gadoids,
collected between 1928 and 1958. Using statistical models to summarise the data, we demonstrate the potential of MPAs for
expediting the recovery of over-exploited fisheries in open temperate regions. Our age-structured data and population models
suggest that wild fish stocks will respond rapidly and positively to reductions in harvesting rates and that the numbers of
older fish in a population will react before, and in much greater proportion, than their younger counterparts in a kind of
Mexican wave. Our analyses demonstrate both the overall increase in survival due to the lack of harvesting in the War and
the form of the age-dependent wave in numbers. We conclude that large closed areas can be very useful in the conservation
of migratory species from temperate areas and that older fish benefit fastest and in greater proportion. Importantly, any
rise in spawning stock biomass may also not immediately result in better recruitment, which can respond more slowly and hence
take longer to contribute to higher future harvestable biomass levels. 相似文献
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水电站鱼类人工增殖放流标记方法研究概述 总被引:2,自引:0,他引:2
鱼类人工增殖放流是缓解水电建设对鱼类资源影响的一个重要措施,也是一项非常复杂的系统工程。标记放流可以帮助人们准确获得鱼类的种群信息,是鱼类增殖放流效果评估的重要手段之一。目前,国内外常用的标记方法主要有体外标记法、体内标记法、自然标记法、化学标记法、生物遥测法、分子遗传标记法,文章介绍了这些标记方法的特点及应用,分析了中国鱼类标记放流方面存在的问题并提出了加强鱼类标记方法的科学研究、采用多种途径对标记鱼类进行回收、建立科学合理的回收体系和加强鱼类回收后研究的建议。 相似文献
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Renewed interest in the topic of compensation in fish populations has been stimulated by new EPA 316(b) regulations relating to entrainment and impingement looming on the horizon. The purpose of this paper is to revisit the topic of population compensation for fish populations in the context of assessing power generation impacts. I define compensation as the net population-level outcome of changes in growth, survival, and reproduction at the individual fish level that offsets decreases or increases in population density. Potential mechanisms of compensation have been well document in laboratory and field experiments. The process underlying all these mechanisms is that changes in population density can change per capita availability of essential resources such as food and space. The state of science in this area is constrained both retrospectively and prospectively by five technical stumbling blocks. Technological advances have improved our ability to bound the phenotypic plasticity of a species and to assess the potential effects of power generation impacts through a combination of monitoring, special studies, and simulation modeling. Four generalizations concerning compensation are mentioned. Progress has been made over the past three decades, but this topic remains scientifically challenging and politically controversial. 相似文献
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Routine assessments of sport fish populations are necessary for managers to determine whether populations are meeting objectives. An effective assessment technique should entail rating parameters that are measurements of, or are influenced by the three rate functions of recruitment, growth, and mortality. It will enable managers to determine which rate functions may be preventing a population from achieving stated objectives and help them determine if additional management or research efforts are needed. The first requirement of an effective assessment technique is a standard sampling method that captures all sizes of fish that are present in the population. The sampling method should detect changes in population density and size structure, which will then be reflected in sample length frequencies. Other important criteria are the selection of appropriate parameters from the sample data and the setting of objectives for those parameters. An ideal assessment should include parameters that depict recruitment levels, adult density, growth rate, age structure, and size structure. The parameter value should be easy to calculate from sample data. Use of an assessment for white crappies in Missouri’s large reservoirs showed that growth was generally good, but mortality was high. Subsequent research indicated that angler exploitation was the cause of the high mortality, which led to the successful implementation of restrictive harvest regulations. 相似文献