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31.
Successful species conservation typically results in conflicts between wildlife protection and economic uses of natural resources as in fisheries and aquaculture. This article shows why managing these conflicts require a more comprehensive approach than currently pursued by endangered species conservation programmes. Against the background of several case studies focussing on wildlife conflicts in European waters this article derives two challenges for institutional response: First, the question of mandate—which societal actor initiates management related processes that require multiple actors to collaborate? Second, how can continuous processes of collaboration be sustained? 相似文献
32.
Meredith L. McPherson Victoria J. Hill Richard C. Zimmerman Heidi M. Dierssen 《Estuaries and Coasts》2011,34(6):1150-1160
Water column optical properties of Greater Florida Bay were investigated in the context of their impacts on seagrass distribution.
Scattering played an important role in light attenuation throughout the shallow water system. The northwest region was characterized
by an absence of seagrasses and the highest scattering by particles, mostly from resuspended carbonate sediments. Higher seagrass
densities were observed in the open waters just north of the Florida Keys, where absorption coefficients were dominated by
colored dissolved organic material and scattering was lower than in the northwest region. Patchy dense seagrass meadows were
observed in the clear waters south of the Keys where scattering and absorption were low and contributed equally to light attenuation.
In general, seagrasses were observed in areas where >7.5% of surface irradiance reached the plants and where optical properties
were not dominated by scattering. Although the prevention of eutrophication and nuisance algal blooms may be necessary for
preserving seagrass meadows in this system, our observations and model calculations indicate that nutrient control alone may
be insufficient to permit seagrass recolonization if optical properties are dominated by particulate scattering from resuspended
sediments. 相似文献
33.
Patrick J. Fitzpatrick Imke de Pater Statia Luszcz-Cook Michael H. Wong Heidi B. Hammel 《Astrophysics and Space Science》2014,350(1):65-88
We report observations of Neptune made in H-(1.4–1.8 μm) and K’-(2.0–2.4 μm) bands on 14 and 16 July 2009 from the 10-m W.M. Keck II Telescope using the near-infrared camera NIRC2 coupled to the Adaptive Optics (AO) system. We track the positions of 54 bright atmospheric features over a few hours to derive their zonal and latitudinal velocities, and perform radiative transfer modeling to measure the cloud-top pressures of 50 features seen simultaneously in both bands. We observe one South Polar Feature (SPF) on 14 July and three SPFs on 16 July at ~65?°S. The SPFs observed on both nights are different features, consistent with the high variability of Neptune’s storms. There is significant dispersion in Neptune’s zonal wind velocities about the smooth Voyager wind profile fit of Sromovsky et al. (Icarus, 105:140, 1993), much greater than the upper limit we expect from vertical wind shear, with the largest dispersion seen at equatorial and southern mid-latitudes. Comparison of feature pressures vs. residuals in zonal velocity from the smooth Voyager wind profile also directly reveals the dominance of mechanisms over vertical wind shear in causing dispersion in the zonal winds. Vertical wind shear is not the primary cause of the difference in dispersion and deviation in zonal velocities between features tracked in H-band on 14 July and those tracked in K’-band on 16 July. Dispersion in the zonal velocities of features tracked over these short time periods is dominated by one or more mechanisms, other than vertical wind shear, that can cause changes in the dispersion and deviation in the zonal velocities on timescales of hours to days. 相似文献
34.
The retention of particles within meadows of submerged aquatic vegetation impacts the fate of organic matter, pollen, and larvae. Because flow conditions near the leading edge differ from those over the bulk of the canopy, particle retention is likely to differ as well. In particular, near the leading edge of a wide meadow, flow deceleration generates a vertical updraft, which impacts particle fate. In the fully developed region of the meadow, shear layer vortices at the top of the meadow may also influence particle fate. In this study, the retention of particles was measured along the length of a 10-m model meadow (height h?=?0.1 m) and was connected to the evolving flow field. Two particle sizes, with settling velocity w s50?=?0.00075?,?0.018 m s?1, were released at two heights within the model meadow \( \left(\frac{Z_{rel}}{h}=0.31,0.81\right). \) The retention of particles was measured using microscope slides distributed along the flume bed. Retention increased with distance from the leading edge, associated with the decrease in vertical updraft. Retention was also greater for the particles with higher settling velocity. In the fully developed region of the meadow, particle retention was lower for particles influenced by the shear layer vortices at the top of the meadow (\( \frac{Z_{rel}}{h}=0.81 \)). 相似文献
35.
A probabilistic eruption forecast is provided for seven historically active volcanoes along the Central American Volcanic Arc (CAVA), as a pivotal empirical contribution to multi-disciplinary volcanic hazards assessment. The eruption probabilities are determined with a Kaplan–Meier estimator of survival functions, and parametric time series models are applied to describe the historical eruption records. Aside from the volcanoes that are currently in a state of eruptive activity (Santa María, Fuego, and Arenal), the highest probabilities for eruptions of VEI ≥ 2 occur at Concepción and Cerro Negro in Nicaragua, which are likely to erupt to 70–85 % within the next 10 years. Poás and Irazú in Costa Rica show a medium to high eruption probability, followed by San Miguel (El Salvador), Rincón de la Vieja (Costa Rica), and Izalco (El Salvador; 24 % within the next 10 years). 相似文献
36.
Odd Kolbjørnsen Marita Stien Heidi Kjønsberg Bjørn Fjellvoll Petter Abrahamsen 《Mathematical Geosciences》2014,46(2):205-225
A multigrid Markov mesh model for geological facies is formulated by defining a hierarchy of nested grids and defining a Markov mesh model for each of these grids. The facies probabilities in the Markov mesh models are formulated as generalized linear models that combine functions of the grid values in a sequential neighborhood. The parameters in the generalized linear model for each grid are estimated from the training image. During simulation, the coarse patterns are first laid out, and by simulating increasingly finer grids we are able to recreate patterns at different scales. The method is applied to several tests cases and results are compared to the training image and the results of a commercially available snesim algorithm. In each test case, simulation results are compared qualitatively by visual inspection, and quantitatively by using volume fractions, and an upscaled permeability tensor. When compared to the training image, the method produces results that only have a few percent deviation from the values of the training image. When compared with the snesim algorithm the results in general have the same quality. The largest computational cost in the multigrid Markov mesh is the estimation of model parameters from the training image. This is of comparable CPU time to that of creating one snesim realization. The simulation of one realization is typically ten times faster than the estimation. 相似文献
37.
Heidi Kreibich Philip Bubeck Michael Kunz Holger Mahlke Stefano Parolai Bijan Khazai James Daniell Tobia Lakes Kai Schröter 《Natural Hazards》2014,74(3):2279-2304
Although Germany is not among the most hazard-prone regions of the world, it does experience various natural hazards that have caused considerable economic and human losses in the past. Moreover, risk due to natural hazards is expected to increase in several regions of Germany if efficient risk management is not able to accommodate global changes. The most important natural hazards, in terms of past human and economic damage they caused, are storms, floods, extreme temperatures and earthquakes. They all show a pronounced spatial and temporal variability. In the present article, a review of these natural hazards, associated risks and their management in Germany is provided. This review reveals that event and risk analyses, as well as risk management, predominantly focus on one single hazard, generally not considering the cascading and conjoint effects in a full multi-hazard and risks approach. However, risk management would need integrated multi-risk analyses to identify, understand, quantify and compare different natural hazards and their impacts, as well as their interactions. 相似文献
38.
39.
Li-Cai Deng Heidi Jo Newberg Chao Liu Jeffrey L. Carlin Timothy C. Beers Li Chen Hsu-Tai Lee Carl J. Grillmair Puragra Guhathakurta Zhan-Wen Han Jin-Liang Hou Sebastien Lepine Jing Li Xiao-Wei Liu Kai-Ke Pan J. A. Sellwood Bo Wang Hong-Chi Wang Fan Yang Brian Yanny Hao-Tong Zhang Yue-Yang Zhang Zheng Zheng Zi Zhu 《天体物理学报》2012,(7):735-754
40.
Jeffrey L. Carlin Sebastien Lepine Heidi Jo Newberg Li-Cai Deng Timothy C. Beers Yu-Qin Chen Norbert Christlie Xiao-Ting Fu Shuang Gao Carl J. Grillmair PuragraGuhathakurta Zhan-Wen Han Jin-Liang Hou Hsu-Tai Lee Jing Li Chao Liu Xiao-Wei Liu Kai-Ke Pan J. A. Sellwood Hong-Chi Wang Fan Yang Brian Yanny Yue-Yang Zhan Zheng Zheng Zi Zhu 《天体物理学报》2012,(7):755-771