Effects of Habitat Fragmentation on Effective Population Size in the Endangered Rio Grande Silvery Minnow

Abstract:  We assessed spatial and temporal patterns of genetic diversity to evaluate effects of river fragmentation on remnant populations of the federally endangered Rio Grande silvery minnow ( Hybognathus amarus ). Analysis of microsatellite and mitochondrial DNA detected little spatial genetic structure over the current geographic range, consistent with high gene flow despite fragmentation by dams. Maximum-likelihood analysis of temporal genetic data indicated, however, that present-day effective population size ( N_eV ) of the largest extant population of this species was 78 and the ratio of effective size to adult numbers ( N_eV/N ) was ∼ 0.001 during the study period (1999 to 2001). Coalescent-based analytical methods provided an estimate of historical (river fragmentation was completed in 1975) effective size ( N_eI  ) that ranged between 10⁵ and 10⁶. We propose that disparity between contemporary and historical estimates of N_e and low contemporary N_e/N result from recent changes in demography related to river fragmentation. Rio Grande silvery minnows produce pelagic eggs and larvae subject to downstream transport through diversion dams. This life-history feature results in heavy losses of yearly reproductive effort to emigration and mortality, and extremely large variance in reproductive success among individuals and spawning localities. Interaction of pelagic early life history and river fragmentation has altered demographic and genetic dynamics of remnant populations and reduced N_e to critically low values over ecological time.     

重碳酸型地下水矿化度测定方法的探讨——以洛阳市浅层地下水为例

矿化度是地下水化学成份测定的重要指标，在环境监测中，用重量法测定矿化度是目前普遍采用的方法。其缺点主要为费时，繁琐，耗电。本文通过测定洛阳市地下水的电导率，分析对比电导率与矿化度的关联，并进一步用回归方程确定电导率与矿化度之间的数量关系，探索出用电导率法间接测定地下水矿化度，具有快速，经济，准确的优点。     

上海城市人为灾害的灰色预测

应用灰色预测ＧＭ（１，１）模型，导出其响应函数，对上海市的火灾发灾频次作了实例预测。然后对预测模型作了检验，预测精度是２级，检验结论符合要求。对城市人为灾害的灰色预测，为防灾减灾的决策部署提供了依据。     

ECONOMIC IMPACTS OF GUIDED WHITEWATER RAFTING: A STUDY OF FIVE RIVERS1

ABSTRACT: This paper presents estimates of the statewide economic impacts of guided whitewater rafting on five rivers in six states: the Nantahala (North Carolina), Gauley (West Virginia), Kennebec (Maine), Middle Fork of the Salmon (Idaho), and Chattooga (Georgia-South Carolina). Except for the Chattooga and Middle Fork, rafting is dependent on upstream dam releases. Guide fees range from about $15 per trip on the Nantahala to over $1,000 on the Middle Fork. Economic impacts per nonresident 1000 visitors increase along with length of the rafting trip and remoteness of the river. Total industrial output per 1000 nonresident visitors ranged from $95,000 on the Nantahala to over $2.5 million on the Middle Fork. However, because of differences in annual visitation levels, total impacts were greatest at the Nantahala, at over $14 million in 1993. Multipliers for all economic measures were relatively consistent over the rivers. Employment multipliers (Type III) ranged from 1.67 to 1.90, income multipliers from 2.0 to 2.4, and industrial output multipliers from 2.1 to 2.5.     

DEVELOPING BIOLOGICAL INFORMATION SYSTEMS FOR WATER QUALITY MANAGEMENT1

ABSTRACT. Management of aquatic ecosystems requires a clear understanding of the goals to be achieved, appropriate information and the means to achieve the goals. Control measures applied to aquatic ecosystems, in the absence of information on the condition of the system, are apt to be inappropriate and thus may overprotect the receiving system at times and underprotect it at other times since the ability of ecosystems to receive wastes is not constant. A major determinant of the effectiveness and efficiency of ecological quality control is the lag time in the feedback of information. If the lag is too great, the control measures may repeatedly overshoot or undershoot the desired goal. Present techniques for measuring the responses of aquatic organisms and communities require days or weeks, whereas information for ecosystem quality control and prevention of ecological crises should be generated in minutes or hours as is the case for other quality control systems. Two biological monitoring systems have been developed to generate information rapidly. One system measures changes in the movement and breathing of fish in order to provide an early warning of developing toxicity in the wastes of an industrial plant. The other system measures changes in the diversity of algal comunities in streams by means of laser holography. The incorporation and use of these systems in industrial plants is discussed.     

WATER QUALITY MANAGEMENT: THE CASE FOR RIVER BASIN AUTHORITIES1

ABSTRACT: There is a lamentable absence of comprehensive planning in the current cursade to improve water quality. A serious shortcoming is the lack of evaluation of the effects of waste water treatment upon environmental quality. At some point in time the public may ask what they have obtained for their money. The nature of pollution in a river basin demands a coordinated attack against it. Engineering and economic criteria suggest that a properly empowered river basin authority would be the logical organization to plan and operate a water quality management system. Several forms of such authorities have operated effectively and efficiently for many years in the United States and other industrialized countries. Examples of successful river basin authorities and their advantages and methods of operation are discussed.     

论多自然型河流治理法对河流生态环境的影响

本文首先介绍了成都府河望江公园段多自然型护岸工程的由来,然后通过简述国外多自然型河川治理常用方法论述了对河流生态环境的改善作用,最后在对府河多自然型护岸设计介绍的基础上提出了试验工程的深远意义及其对今后工作的启迪     

宿迁城北构造地貌特征及其成因分析

京杭大运河在宿迁附近走向发生东西方向的拐折,研究认为系与该区存在近东西向断裂有关。文中应用人工地震和地质钻孔资料详细论述了这一地区的地貌特征,并对发生拐折的成因作了分析。     

论中国城市灾害科学的现状研究及新构想

城市是一个国家和地区的经济、政治、文化中心,是一个综合了社会、心理、地理、工程、功能、生态等学科在内的复杂系统工程,是人双重属性(自然与社会)的一个载体。面对现状及21世纪我国城市建设的挑战,本文认为不仅应研究优美的景观、平衡的生态、高效的功能及无障碍特性,还必须提高一个现代化城市抗御灾害的综合能力。“国际减灾十年”全球统一行动应同环境治理一样,成为衡量城市现代化的标志。     

WATER QUALITY MODELING IN THE UPPER REACHES OF THE CHOWAN RIVER1

ABSTRACT: The Chowan River system consists of three rivers in southeast Virginia that form two confluences before flowing into Albermarle Sound in North Carolina. A computer program was written to simulate flows through the river system to determine flow rates, velocities, and depths. The output of the flow program was input into a second program that calculated the concentrations of BOD₅, COD, DO, and four nitrogen parameters (organic, ammonia, nitrite-nitrate and algal-N). Measured field data were used to calibrate the model. The effect of reducing the concentration of nutrients from overland runoff on algal concentrations at the mouth of the river was studied. The program was also run to simulate the water quality of the watershed in a primitive condition, in which the watershed was assumed to consist only of forests. The results of the computer program indicate that the major changes in the water quality of the river are simulated satisfactorily. The program can be used to assess the impact of any management scheme to improve water quality.