Shifts in a Pacific Ocean Fish Assemblage: the Potential Influence of Exploitation

Abstract:  As in many regions of the world, marine fishes and invertebrates along the Pacific coast of the United States have long been subjected to overexploitation. Despite this history, however, we lack basic information on the current status of many fishes along this coastline. We used data from a quarter century of fishery-independent, coast-wide trawl surveys to study systematically the demersal fish assemblages along the U.S. Pacific coast. We documented fundamental shifts in this fish assemblage. Average fish size, across a diversity of species, has declined 45% in 21 years. There have been major shifts in the constituent species of the assemblage, with some species achieving annual population growth rates of >10% and others declining in excess of 10% per year. Annual rate of change in population size appeared to be a function of life history interacting with fishing pressure. Negative trends in population size were particularly apparent in rockfish ( Sebastes spp.). However, across all taxa examined, trends in population size were associated with size of maturity, maximum size, and growth rate. Trends in population size were associated inversely with harvest levels, but stocks that mature late tended to decline faster than would be predicted by catch rates alone. Our results are disquieting because they raise the possibility that fishing-induced phase shifts in fish communities may affect the recovery of fishes, even after the implementation of severe fishing restrictions.     

Effects of male removal on female foraging behavior in the Eurasian treecreeper

In old, spruce-dominated forests of central Finland, Eurasian treecreepers Certhia familiaris divide their territories spatially during the breeding season. Females forage primarily on the upper parts of the tree trunks, while males use the lower parts of the tree trunks. In this study we removed males from eight territories in the early nestling period to see if the mate's absence would change the foraging patterns of the resident female. Widowed females foraged at lower heights, thus behaving more like paired males. These females also spent less time on each tree and on each foraging bout than did paired females. We conclude that male removal facilitated the change in a female's foraging niche and foraging time at the trees. Females may re-optimize their foraging site selection owing to the absence of dominant males and a consequent need to increase their parental care. Behavioral plasticity may be the mechanism of niche partitioning between the sexes in this species. Received: 28 June 1996 / Accepted after revision: 27 March 1997     

Electromagnetic field levels in the working environment in radio and TV stations

Electromagnetic field sources used for communication always have been subject of serious interest. There are many publications concerning exposure and risk assessment of the working in such environment. Results of epidemiological study performed in Bulgaria in the 1990's show exceeding of the maximal permissible values especially in radio stations for the personnel in 24 h working shift [Israel et al. (1992). Study of the electromagnetic in its influence on personnel working in radio and TV stations, Report, National Centre of Hygiene, Medical Ecology and Nutrition; Israel and Tomov (2001). Epidemiological study of the effects of radiofrequency radiation on operators in radio, TV and relay stations, Proceeding of the Eastern European Regional Meeting and Workshop “Measurements and Criteria for Standard Harmonization in the field of EMF Exposure” and WHO EMF Standards Harmonization Meeting, Varna, Bulgaria, 28 April—3 May, 2001, pp.145–153]. In the last years the situation is strongly influenced by the development of the technology which leads to changes in equipment in radio and TV stations, using lower power, facilitate the working regime. The paper presents data of exposure assessment of different professional groups in selected radio and TV stations. Assessment is being performed on basis of EMF parameters values and energetic load calculations according to the national legislation. Data are compared with the results of previous investigation to evaluate the new situation in this branch. Exposure levels are much lower than those in the previous study, and lower compared to the exposure limits, as well [Israel et al. (1992). Study of the electromagnetic in its influence on personnel working in radio and TV stations, Report, National Centre of Hygiene, Medical Ecology and Nutrition; Israel and Tomov (2001). Epidemiological study of the effects of radiofrequency radiation on operators in radio, TV and relay stations, Proceeding of the Eastern European Regional Meeting and␣Workshop “Measurements and Criteria for Standard Harmonization in the field of EMF Exposure” and WHO EMF Standards Harmonization Meeting, Varna, Bulgaria, 28 April—3 May, 2001, pp.145–153].     

Numerical computation and characteristic analysis on the center shift of fire whirls in a ship engine room fire

The existence of fire whirls in some ship engine room is studied by using the basic elements of the fire whirls formation. The temperature characteristic of fire whirls are used to study the path shift of fire whirls and the result is nearly circular. The center shift angular velocity of fire whirls is analyzed with the least square fitting in the conditions of the constant wind velocity and the variable wind velocity from four sides. In the situation of the constant wind velocity, the result shows that the center shift angular velocity of fire whirls comply with the change regularity of a cube polynomial with different wind speed. When the wind velocity is more than 6.58 m/s, it strongly affects the change rate of the center shift angular velocity. However, in the situation of variable wind velocity, when the change rule of wind velocity follow increasing or descending regularity, the change law of the center shift angular velocity is proportional to the size of the wind velocity, but when the wind velocity is random variation, the change fluctuation of center shift angular velocity is comparatively small. Computational results have important significance for the structure fireproofing, fire evaluation and shipping design.     

平庄西露天矿露井联采高陡长大 边坡稳定性监测研究

为掌握平庄西露天矿露井联采顶帮边坡的岩移规律与稳定性状态,揭示地下开采对边坡稳定性的影响,基于对典型滑坡位移-时间特征的 认识,提出用位移历时曲线与位移加速度历时曲线形态判断边坡稳定性状态,并详细对比分析了布置在井工开采边界以及边坡走向与倾向方向 上各监测线的地表位移监测数据。结果表明,平庄西露天矿顶帮现状边坡整体处于稳定状态,II区凸边坡为相对不稳定区域;边坡岩移规律及 稳定性主要受断层、弱层、边坡平面形态、地下开采及其引起的断层活化等因素综合控制;地下开采对边坡稳定性影响范围的边界大约在边坡 表面出露标高+572m。     

DOAS监测排放烟气浓度时谱线漂移处理方法研究

差分吸收光谱法(DOAS)是利用气体在紫外可见光波段对光具有选择吸收的特性来测量气体浓度的一种方法。DOAS法连续监测系统的核心是软件部分,由于吸收谱线漂移现象的存在,光谱解析算法的改进对污染气体浓度的计算带来很大的影响。基于DOAS法研究监测排放烟气浓度时谱线漂移对浓度计算的影响,并提出将相关函数和相关系数结合参与浓度计算,实验的结果表明,可以有效地减小谱线漂移时浓度计算的误差。     

Towards an earthquake-resilient world: from post-disaster reconstruction to pre-disaster prevention

ABSTRACT

Destructive earthquakes in urban or rural areas around the world have caused severe damage to local societies. Pre-disaster prevention and post-disaster reconstruction can significantly reduce the impact of earthquakes on communities. To explore the popular research topics and trends in this area, CiteSpace was used to develop a knowledge map visualization. It was found that the main research into earthquake disaster prevention and reconstruction has been focused on disaster risk reduction planning, disaster mitigation knowledge, participatory disaster governance, and community resilience building. In this Special Issue, there were six distinctive earthquake disaster research papers that covered scientific, social, and institutional aspects. It was concluded that to reduce the effects of earthquake disasters, an interdisciplinary research approach and systems thinking is needed. The investigation also revealed that there has been a paradigm shift from post-disaster reconstruction to pre-disaster prevention to build community and urban resilience.     

The geo-genetic status of earthquake-related hazards and the role of human and policy dimensions in impact mitigation

ABSTRACT

Earthquakes occur in and around active lithospheric-plate margins that are located both in diverging and converging plate-settings. New fault rupture or old active fault reactivation can cause ground shaking, land deformation, land subsidence, landslides, and mass avalanches. The relevant locations of major risk centres around the world are well known. However, the parameters such as trend, pattern, frequency and magnitude are highly variable and very difficult to determine and predict. One result is that many fundamental and universal scientific achievements for mitigating earthquake hazard have often failed in protecting and safe-guarding human life and property. Although naturally occurring events cannot be prevented nevertheless loss of life and property damage could be minimized if an integrated effort and using the wisdom of the relevant professionals are practiced. A paradigm shift of the culture from post-disaster relief and rehabilitation to pre-disaster preparation and practice would reduce the level of destruction from an impending earthquake. Requisite pre-disaster physical planning and appropriate building measures, and pre- and post-disaster risk management should give special attention to public awareness programmes for loss mitigation. However, the fundamental requirement for such achievement is dedicated approach and commitment from the planner, practitioners and end-users of risk mitigation actions.     

An economic evaluation framework for land-use-based conservation policy instruments in a changing climate

Climate change is a key threat to biodiversity. To conserve species under climate change, ecologists and conservation scientists suggest 2 main conservation strategies regarding land use: supporting species’ range shifts to enable it to follow its climatic requirements by creating migration pathways, such as corridors and stepping stones, and conserving climate refugia (i.e., existing habitat areas that are somewhat buffered from climate change). The policy instruments that could be used to implement these conservation strategies have yet to be evaluated comprehensively from an economic perspective. The economic analyses of environmental policy instruments are often based on ecological effectiveness and cost-effectiveness criteria. We adapted these general criteria to evaluate policy instruments for species’ conservation under climate change and applied them to a conceptual analysis of land purchases, offsets, and conservation payments. Depending on whether the strategy supporting species’ range shifts or conserving climate refugia is selected, the evaluation of the policy instruments differed substantially. For example, to ensure ecological effectiveness, habitat persistence over time was especially important for climate refugia and was best achieved by a land-purchase policy instrument. In contrast, for the strategy supporting range shifts to be ecologically effective, a high degree of flexibility in the location of conserved sites was required to ensure that new habitat sites can be created in the species’ new range. Offset programs were best suited for that because the location of conservation sites can be chosen comparatively freely and may also be adapted over time.     

sup>17O-核磁共振研究给水中常见离子对水缔合的影响

给水中通常含有少量的离子,如Na⁺,K⁺,Ca²⁺,Mg²⁺及Cl^-,SO₄^2-,CO₃^2-等.本文测量了不同温度(20～60℃)下的水及由上述离子组成的不同浓度盐溶液(0～1mol/L)的¹⁷O-核磁共振(¹⁷O-NMR)的化学位移和半峰宽根据化学位移和半峰宽的变化与水缔合的关系分析了离子对水缔合的影响结果表明,不同离子对水缔合的影响不同,阳离子促进液态水形成缔合结构,阴离子则破坏水的缔合结构;离子电荷越大,半径越大,对水缔合的影响越大,其中电荷的影响程度更大.