Surplus production,compensation, and impact assessments of power plants

For over 60 years, fishery scientists have been using the argument that nature creates surplus, and that the surplus can be used as justification to impose anthropogenic sources of mortality (power plants, fishing, pollution, etc.) on fish populations; otherwise, it is wasted. Surplus production is closely tied to the concept of compensation, a form of density-dependent mortality in which the mortality rate of a cohort is directly related to abundance of that cohort. Scientific arguments have been put forth in assessments of power plant impacts that compensation can at least partially offset impacts imposed by power plants. Although we cannot dismiss the existence of surplus production outright, since in some years environmental conditions are such that a surplus in reproductive effort may occur, we should be assessing the reproductive effort of fish populations in the context of the ecosystem in which they reside. In terms of addressing the risks of power plant mortality, we may be at a point in collection and analyses of biological data, coupled with a greater flexibility in managing power plant technology, to modulate the risks of power plant mortality on fish populations on a more-or-less real-time basis by taking into account environmental influences. For these reasons, assessments of power plant impacts should include analyses of predation forgone and production forgone.     

Assessment of 316(b) impacts on Ohio River fish populations

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.     

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.     

Linkages between fishery habitat quality,stressors, and fishery populations

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.     

Historical overview of the efficacy of two decades of power plant fisheries impact assessment activities in Chesapeake Bay

The Chesapeake Bay is world renowned as an estuary that historically yielded large harvests of a wide variety of fish and shellfish species. Thirteen power plants are located on the mainstem of the Bay and its tributaries in Maryland, drawing out of and discharging into the Bay eight billion gallons per day of the Bay’s waters for cooling purposes. Maryland DNR’s Power Plant Research Program (PPRP) has, since 1974, funded a wide variety of fisheries assessment, entrainment and impingement studies. PPRP’s Potomac River Fisheries Program (PRFP) encompassed multi-year, statistically rigorous, quantitative studies of all life stages of striped bass, from egg to adult, together with estuarine hydrodynamics modeling and water quality assessments, all yielding data integrated to project potential entrainment impacts from a proposed nuclear power plant. PPRP and utility-sponsored monitoring programs at BGE’s Calvert Cliffs NPP, PEPCO’s Chalk Point SES and DP&L’s Vienna SES, as well as other generating facilities throughout the state have provided comprehensive data on impingement, entrainment and receiving water populations of all life stages of potentially impacted resource species. These studies have resulted in unusually complete and long term data sets being available for impact assessment applications, and provide a basis for confirming and validating impact assessment findings and conclusions based on much shorter time series. The state/federal Chesapeake Bay Program has extensively characterized the status and trends of all important resource species in the Bay. We compare and contrast impact conclusions and projections from studies conducted in the 1970s and 1980s with current data and information on the status of and trends in affected fish stocks in Chesapeake Bay. We use that comparison to establish the role that power plant impacts play as factors driving changes in species abundance over time. These comparisons and contrasts between historical and current data and information also illustrate and confirm the methodologies that have proven to be most and least useful for assessing entrainment and impingement impacts.     

316(b) and Quad Cities Station,Commonwealth Edison Company

Quad Cities Station is a 1630 MW_e dual reactor facility located on the Upper Mississippi River approximately 30 miles north of Davenport, Iowa and Rock Island, Illinois. As designed, the Station utilizes river water at the rate of 2270 cfs in an open-cycle mode of operation. From the 316(b) perspective, numerous agencies and intervenors expressed major concern regarding the potential adverse impacts of open-cycle entrainment and impingement effects on the River’s highly valued and diverse fishery. As a result, the fishery has been monitored continuously since 1971 through field surveys directed at measurements of community composition and relative abundance, as well as fish impingement surveys of the Station’s intake. From 1972 to 1983 the Station operated in a closed-cycle or partial closed-cycle mode.Regulatory relief and intervenor approval for open-cycle operation were not granted until 1984, following several years of intensive studies directed at entrainment/impingement and methods to reduce impingement. Beginning in 1978, the freshwater drum was selected as the indicator species most likely to manifest changes in population characteristics potentially resulting from open-cycle operation. Population levels (numbers and biomass), growth, fecundity, sex ratios and survival were all monitored to determine if compensatory responses occurred within the population following increases in impingement under open-cycle operation. Included in the agreement that allowed the return to open-cycle operation was a commitment to construct and operate a fish production facility to mitigate for potential impacts.After 14 years of monitoring under open-cycle operation, there have been no measurable changes in the local fishery and, specifically, none within the freshwater drum population. Naturally occurring environmental conditions have more profound influences on this dynamic and resilient fishery than operation of a large generation facility. Station operation is relatively constant from year to year and impingement monitoring may actually be the most accurate monitoring activity. Fluctuations in annual impingement projections are reflections of conditions within the river and the fishery’s response to them. Increases or decreases in fish numbers impinged at the Station in any given year are primarily due to fluctuations in the fishery and the effects of existing environmental variables and not to Station operation. The fishery fluctuations are reflections of conditions within the river and the fishery’s response to them.     

Estimating the abundance and egg production of spawning winter flounder (Pseudopleuronectes americanus) in the Niantic River,CT for use in the assessment of impact at Millstone Nuclear Power Station

The winter flounder is a coastal flatfish with spawning populations associated with specific estuaries or coastal areas. Because of its stock structure, this species is susceptible to localized impacts, including power plant entrainment of larvae. Winter flounder rank second in fish larvae entrained at the Millstone Nuclear Power Station (MNPS), located on Long Island Sound in Waterford, CT, USA. Because of its importance to the state’s fisheries, the population spawning in the nearby Niantic River was selected for impact assessment studies in the early 1970s. Northeast Utilities has consistently monitored annual abundance of adult spawners, characterizing relative abundance by trawl catch-per-unit-effort (CPUE) and absolute abundance using mark and recapture data with the Jolly model for demographically open populations. Trends in these two independent but highly correlated indices provide short-term assessments of winter flounder abundance. Abundance of winter flounder peaked in the early 1980s, but as fishing mortality increased to high levels in the late 1980s, their numbers declined thereafter and presently are very low. Information on sex ratio, length-frequency distribution, and spawning condition allow for calculation of annual egg production using a length-fecundity relationship. This forms the basis for estimating production loss due to larval entrainment, which is used as input to a long-term assessment model of power plant impact, discussed in an accompanying paper (Lorda et al., 2000: Lorda, E., Danila, D.J., Miller, J.D., 2000. Application of a population dynamics model to the probabilistic assessment of CWIS effects of Millstone Nuclear Power Station (Waterford, CT) on a nearby winter flounder spawning stock. Environmental Science & Policy 3, S471–S481).     

Morphological distinctness despite large-scale phenotypic plasticity��analysis of wild and pond-bred juveniles of allopatric populations of Tropheus moorii

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.     

Criteria and procedures for evaluating the quality of fish populations in reservoirs

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.     

地理特征、人口分布及用电负荷对深圳城市热岛效应的影响分析

利用自动站气温资料计算了深圳市的城市热岛强度,并分析了海陆分布、人口密度、道路占地面积百分比及用电负荷等因素对深圳城市热岛效应的影响.结果表明,海陆分布是决定深圳城市热岛强度空间分布格局的主要因子,深圳东西两侧海洋的气候调节作用使得热岛强度相对较低,而中部地区南临香港陆地,海洋调节作用较弱,使得这部分地区成为深圳城市热岛的中心.人口密度和道路占地面积百分比对深圳城市热岛强度空间分布格局均有影响,它们与城市热岛强度之间的相关性显著（p〈0.01）,但道路占地百分比最密集的地区,城市热岛强度值却并不高,这可能与该区域较大的年平均风速有关.对2011年和2010年的数据进行对比分析,发现电力负荷对深圳城市热岛强度有着非常明显的影响,2011年深圳年平均城市热岛强度的增加,极有可能是由于2011年冬季更冷夏季更热导致用电负荷增加而造成的.     

Occurrence and variation of egg cannibalism in brown trout Salmo trutta

Egg cannibalism is a common behavior among fish taxa and is largely studied in species with parental care. Heterocannibalism and filial cannibalism have both been reported in salmonids, a group with no extended parental care, but the topic remained somewhat under-documented, especially in brown trout (Salmo trutta). In the present study, 83 spawning events were recorded finely with high-resolution video in three natural populations. Redd covering dynamics by females and the timing of cannibalism showed that eggs were vulnerable mainly during the first 120 s after spawning. Cannibalism occurred in 25% of spawnings and was principally perpetrated by peripherals but the sires also cannibalized their brood, especially after multiple mating. The probability of cannibalism increased with operational sex ratio but did not correlate with the date in spawning season. Occurrence of cannibalism also differed between populations. Our results suggest that such behavior is frequent and may reduce the fitness of parents. Its evolutionary implications for population ecology should be considered, since it appeared to be controlled by environmental and spatial factors.     

Impacts of power-plant cooling systems on estuarine fish populations: the Hudson River after 25 years

In the early 1970s, impacts of power-plant cooling systems on fish populations were a major source of controversy. The most thoroughly studied and controversial power plants were the Indian Point, Bowline, and Roseton generating stations on the Hudson River. The assessments performed for these three plants were unique in employing river-wide sampling data and mathematical models designed to predict the effects of cooling-water withdrawals on the short- and long-term abundance of striped bass and other important fish populations. A Settlement Agreement in 1981 led to the establishment of a long-term monitoring program that continues to generate valuable information concerning the impacts of power-plant cooling systems on estuarine ecosystems. This paper evaluates the results generated by the past quarter century of Hudson River, with the objective of evaluating the utility of the information for future 316(b) assessments. Specific recommendations are made concerning: (1) methods for quantitative assessment of cooling-system impacts at new vs operating facilities; (2) research that would improve the efficiency and accuracy of assessments; and (3) the need to integrate cooling system impact studies into a general framework for management of aquatic ecosystems.     

风电场声环境影响探析——以望江屯风电场二期工程为例

风力发电具有公认的环保优势,但由此产生的风力发电工程对局部生态环境及噪声等影响日益受到人们的关注,主要体现在风轮机的视觉污染、噪音、鸟类安全及电磁干扰等方面。探索风电场污染途径,消除或减缓风电场给环境带来的不良影响,对风电行业可持续发展将具有十分重要意义。目前,鉴于有关风电场运营期声环境影响文献较少,本文基于望江屯风电场二期（49．5MW）工程建设,探析风力发电工程声环境影响,为风电场建设控制噪声污染提供理论依据。     

碳税对我国宏观经济及可再生能源发电技术的影响——基于电力部门细分的CGE模型

本文基于电力行业上市公司年报数据将传统CGE模型中的电力部门细分为7个发电部门,其中包含水电、风电、光伏和生物质电4个可再生能源发电部门.首先基于传统CGE模型和电力部门细分的CGE模型比较了我国引入可再生能源发电技术前后征收碳税对宏观经济的影响,然后分析了单一碳税政策、碳税与可再生能源发电补贴复合政策对可再生能源发电技术发展的影响.研究发现：引入可再生能源发电技术后,征收碳税对宏观经济的负面影响相比没有引入而言将有所降低;征收碳税将促进可再生能源发电技术的发展;在征收碳税的同时如果对特定可再生能源发电技术给予补贴,可能会对未受到补贴且不具备成本比较优势的可再生能源发电技术产生“挤出效应”.     

光伏发电和燃煤发电的生命周期评价比较研究

文章运用生命周期评价（life cycle assessment,LCA）的分类、特征化、量化处理的方法,对多晶硅太阳能光伏发电和燃煤发电的全过程进行环境影响评价.通过收集两者的资源消耗量和污染物排放量,建立两者全生命周期资源消耗及污染物排放清单,得到相应的资源消耗系数和环境影响潜值.综合多晶硅太阳能光伏发电和燃煤发电全生命周期评价结果,从资源消耗和环境影响的角度来看,与传统燃煤发电相比,多晶硅太阳能光伏发电具有明显的优势.     

Recovery of a power plant cooling reservoir ecosystem from selenium bioaccumulation

Hyco Reservoir, a North Carolina power plant cooling impoundment, was impacted by selenium toxicity during the late 1970s. Selenium inputs via coal ash discharge resulted in bioaccumulation through the aquatic food chain which caused reproductive failure and population declines of bluegill, other Lepomis spp., largemouth bass, crappie, yellow perch, and sucker species. Following these declines, green sunfish, satinfin shiner, gizzard shad, eastern mosquitofish, and redbelly tilapia dominated the fish community. During 1990, the power plant converted to a dry fly ash handling system that reduced selenium loading into the reservoir. Construction costs for this system were approximately $48 million and annual operating costs have been approximately $1 million/year. Mean selenium concentrations in reservoir waters at the power plant discharge declined from 8.8 μg/l to 3.2 μg/l within one year of the system operation, and this decline was consistent with a priori mass balance modeling predictions. Depuration of selenium from sediments and tissues of plankton, benthos, and fish has been variable since the system operation. Significant selenium declines have occurred in tissues of aquatic organisms in the eight-year recovery period while little change has been observed in sediments. Recovery of the fish community has been rapid, particularly in areas upstream of the ash pond discharge, and confirmed population-level modeling predictions using a Leslie-matrix demographic model. Diversity of the fish community increased throughout the reservoir and species dominance shifted from a green sunfish and satinfin shiner-dominated system to a bluegill-dominated system within five years after the system operation. Increased bluegill and green sunfish hybridism also occurred during early recovery and coincided with a low abundance of spawning bluegill adults. Sport fisheries have re-developed for largemouth bass and crappie and strategies for managing the recovering fishery have included periodic stock assessments, creel surveys and harvest restrictions, prey fish stocking, and continued contaminant monitoring. This pollution abatement system has been successful in reducing selenium loading into the reservoir and prompting recovery of the aquatic ecosystem.     

地理探测器方法下北京市人口空间格局变化与自然因素的关系研究

人口空间分布具有尺度特征,从乡镇街道尺度研究自然因素对城市人口空间格局的影响有利于得出更精细的结果,并为城市人口合理布局和规划提供科学依据。论文利用第五、六次人口普查乡镇街道数据,分析北京市人口空间格局特征,利用地理探测器研究自然因素对人口分布的影响。研究表明：1）自然因素对不同类型人口空间格局影响具有差异性。对常住人口作用强度由大到小的自然因素分别是适宜建设用地面积、地形起伏度、坡度、海拔高程和河网密度,对外来人口作用力由大到小的自然因素分别是地形起伏度、适宜建设用地面积、坡度、海拔高程和河网密度;2）自然因素对不同地区人口空间格局影响具有差异性。除适宜建设用地面积外,坡度和河网密度分别对六环内、外区域人口密度影响较大。高程和地形起伏度对六环外人口格局作用力高于六环内地区;3）两类自然因素叠加对人口密度作用的强化方式体现为因素相互协同或因素作用力非线性增加。5类自然因素对人口密度的影响力交互作用探测值为1,各类自然因素对城市人口空间格局的影响力协同增强。     

环境变化对鸟类种群结构的影响研究

文章将镇江市域内主要优势种树麻雀作为指示种,通过对种群数量、时空分布、不同生境分布、栖息地和森林植被等方面对树麻雀的生态影响进行了调查研究。结果表明：各生境中,分布密度以乡村与城镇最高,农田次之,森林、灌丛及水域最低;植被变化、城乡建设、以及农药、化肥的施用是引起某些鸟类数量变化的重要原因;以鸟类为代表的野生动物与环境关系密切,其分布区域和种群数量的变化以及群落参数变化反映和预示了环境的变化趋势。     

福岛核事故对中国核电站厂址选择影响研究

日本福岛核事故源于两个直接因素--地震和海啸,以及两因素的叠加,并导致放射性泄漏对周围居民产生重大影响。针对这些问题,分析中国大陆核电站厂址的地震发生概率、海啸发生概率和人口分布因素,由此评价我国核电站厂址选择的安全性。结果证明:我国大陆核电站远离地震带;沿海不会发生特大海啸;核电站周围人口分布密度符合安全标准,我国核电站具有较高的固有安全性。同时,此次福岛事故也是对我国核电发展的警示,要求不可忽视小概率的超基准设计事故以及多个超基准设计事故叠加的情况;要重新审查中国抗震和海啸等极限事故的标准;要考虑人口密度;要避免两个核电站建设过密的情况。目前,我国已经采取安全检查等措施确保核电站的安全性。这次福岛事故对我国乃至世界核电的发展都是宝贵的经验教训。     

An equal sex ratio followed by differential sex mortality causes overestimation of females in gall midges: no evidence for sex ratio regulation

Monogeny, the production of unisexual broods by individual females, has been recognized for nearly 80?years. The genetic nature of gall midges' sex determination predicts an equal numbers of male-producing and female-producing females in the populations such that the overall sex ratio is expected to be nearly 1:1. However, observations of some strictly monogenous populations with biased sex ratio, mainly toward females, have raised the question of whether gall midges are able to adjust their offspring sex ratio in response to changes in environmental conditions, and some authors have even considered sex ratio regulation as a strong force in the course of the evolution of monogeny. In this paper, first, by studying the sex ratio variations of the predatory gall midge, Aphidoletes aphidimyza within a generation, we showed that adult males emerge up to 1?day earlier and have shorter life span than females (less than 4?days and up to 6?days, respectively). Although, the sex ratio of A. aphidimyza at the time of emergence was nearly 1:1 (52.41?% males), a simple population simulation indicated that the differential mortality of sexes can lead to a female-biased sex ratio estimation (57.88?% females) under random sampling in the natural environments. Our results imply that the primary sex ratio of monogenous gall midges is nearly 1:1 and that the arrhenogenic/thelygenic gall midges are not able to alter the number of their male/female progenies in response to changes in environmental conditions.