The Fish Assemblage of a Newfoundland Estuary: Diel, Monthly and Annual Variation

Twice monthly sampling over two 16 month periods at a shallow site on Newfoundland's east coast showed the fish assemblage to be dominated by four taxa (Gasterosteus aculeatus, G. wheatlandi, Osmerus mordax, Gadus spp.) that accounted for 96% of the individuals collected. Of the 16 479 fish measured, 65% were adults based on the estimated size of first spawning. The fish assemblage was dominated (86%) by species with demersal eggs, several of which spawn at the same shallow sites used by juveniles as nursery sites. Coastal spawning and demersal eggs maintain offspring in coastal nursery areas where survival is thought to be increased. Number of species and number of fish were both correlated with water temperature being highest from mid-summer to early autumn and lowest in winter. Temperature, time of spawning, and movements of juveniles and adults facilitated grouping species into five assemblages based on seasonal abundance: seasonal periodic species (summer and winter), regular species, regular species collected in all seasons except winter, and occasional (rare) species. At the diel scale, two consistent species groupings were observed: species that showed no significant difference between day and night and species caught primarily at night. Number of night species exceeded day species by a factor of two. No seine-caught species in shallow water exhibited significantly higher catches during the day. Observations by SCUBA divers indicated some species were more abundant during day time at slightly deeper depths. This observation in conjunction with day and night seining in shallower water, suggests these species aggregate in deeper water during day and move to shallow waters at night.     

湖南深部构造活化及其浅部响应

湖南深部构造的古老性由其在古元古代的表象所证实,而长期性则由其所分割的岩石圈块体在漫长时期内的活化改造特征所体现。本研究表明,大型的深部构造是构造、岩浆活动和矿产的集中带,沿走向的区域构造、岩浆及成矿历史是深部构造在浅部的响应。深部构造作为多次能量释放带,其交汇处有利于大型或超大型矿物资源的形成和聚集,因而对找矿预测有巨大潜力。     

SOCIAL CONSTRUCTION OF HYDROPOLITICS: THE GEOGRAPHICAL SCALES OF WATER AND SECURITY IN THE INDUS BASIN*

ABSTRACT. The article identifies important themes and future research directions for analyzing water and conflict dynamics at the subnational scale in the Indus Basin. A historical overview of water development in the Indus Basin suggests that the water‐security nexus was always a salient theme in the minds of water developers, even in the nineteenth century. Conflicts over contemporary large‐scale water‐development projects in the Indian and Pakistani parts of the Indus Basin are reviewed. Engineers' single‐minded focus on megaprojects, to the neglect of the wider set of values that societies attach to water resources in the eastern and western Indus Basin are largely to blame for continuing low‐grade conflict in the basin. A review of local‐level conflicts over water supply and sanitation in Karachi and the distribution of irrigation water in Pakistani Punjab illustrates the critical role of governance and differential social power relations in accentuating conflict. The article argues against neo‐Malthusian assumptions about the inevitability of conflict over water because of its future absolute scarcity. Instead, the article seeks to demonstrate that, despite evidence suggesting that international armed conflict over water does not exist, the potential for political instability over domestic water distribution and development issues is real. The question of whether conflict at the subnational scale will culminate in violence will depend on how water‐resources institutions in the basin behave.     

等离子天体物理学与现代等离子体宇宙观

现代科学表明宇宙中99%以上的可观测物质都处于等离子体状态,从小尺度的微观粒子动力学集体过程与能量转换机制到大尺度的宇宙等离子天体结构状态与爆发活动现象,都是等离子天体物理学的研究课题.从宇宙演化历史、大尺度结构形成以及爆发活动现象等方面,系统地论述了等离子天体物理学在现代天文学发展以及现代等离子体宇宙观形成中的重要作用.同时,结合空间卫星科学探测研究及其对现代天文学的巨大影响,进一步阐述了地球磁层和日球层等空间等离子体实地探测研究在等离子天体物理学研究中所扮演的“天然实验室”的独特作用.     

Riparian management and stream bank erosion in New Zealand

Improvements in riparian management, such as shrub/tree planting and livestock exclusion, are often assumed to result in reduced stream bank erosion and associated catchment sediment yield. Studies that quantify the effectiveness of riparian interventions aimed at reducing bank erosion and river sediment yields are, however, rare. This paper discusses how bank erosion processes can vary throughout catchments (with particular reference to their scale dependence) and hence how the effectiveness of different riparian interventions can be variable. The findings of known published accounts of the effectiveness of riparian management interventions for reducing stream bank erosion in New Zealand are also summarised. Only nine relevant studies were identified and most used qualitative or semi-quantitative analysis methods. Most studies compared stream banks in pasture catchments (with unlimited livestock access) with stream banks where livestock were excluded and riparian shrubs/trees were present. Many studies reported that managed stream banks were in better condition than unmanaged banks. The exclusion of livestock from riparian areas was generally reported as the principal factor in the measured improvements or differences. Only two studies specifically attributed reduced stream bank erosion to the presence of riparian vegetation. The dearth of research identified here highlights the need for further quantitative studies to determine the effectiveness of riparian management measures for reducing bank erosion.     

The morphological response of a nearshore double sandbar system to constant wave forcing

Results of 2DH morphodynamic computations are presented to quantify the temporal evolution of the crescentic patterns emerging in a double nearshore bar system in response to constant wave boundary forcing. Sixteen different conditions varying both offshore wave height and angle of wave incidence were applied. The mean length scales of the emerging irregular crescentic patterns are linearly proportional to the local longshore velocity over the inner and outer bars. For similar longshore velocities, the length scales of the outer bar are larger than of the inner bar. This is explained by accounting for the difference in water depth above the bar crest. The variable morphological response times can be explained by including additional bathymetrical parameters. The active volume of the bar, defined by the breaker index, plays an important role in this response time. With larger active volumes the bar responds more rapidly to identical boundary conditions. Also, bars with a smaller total volume respond more quickly. This faster response is due to the steeper active volume of the bars. Different initial perturbations resulted in different locations of the emerging features, showing that their location is sensitive to the initial bathymetry. However, the range in length scales and response times due to the different perturbations was significantly smaller than those obtained for the different hydrodynamic conditions. Based on the present findings we hypothesize that morphological length scales in the field are rarely in equilibrium with the concurrent offshore wave height and angle of incidence owing to the slow response of the sandbars under constant conditions relative to the stochastic nature of natural wave forcing.     

Justifying non-compliance: The morality of illegalities in small scale fisheries of Lake Victoria,East Africa

The literature on compliance in small scale fisheries provides evidence of the normative foundations of fishers’ behaviour. However, the mechanisms through which normative reasoning translates into non-compliance remains unclear due to the tendency to conceive non-compliant behaviour simply as an outcome of ‘moral deficit’. This paper identifies such mechanisms by focusing on moral reasons which undermine the legitimacy of fisheries regulations. Taking the case of Lake Victoria, East Africa, the paper explores how non-compliance can be founded on diverse and competing concepts of fairness by creating a typology of the modes of justification used by respondents who engage in illegal fishing. The paper establishes four areas of justification: the principle of superfluousness, the principle of autonomy, the principle of futility, and the principle of necessity. Investigating the evidence for each, the analysis finds that the majority of fisherfolk believe that regulations are necessary and support government action in fisheries management. However, fishers expressed futility in fishing legally, given the extent of illegal fishing, and justified their non-compliant behaviour through reference to the cost of legal fishing compared to illegal and the need for better catches and income associated with illegal fishing.     

线性光谱混合模型的适用观测尺度分析

线性光谱混合模型是目前应用最广泛的光谱混合模型,但由于遥感观测多分辨率的特点,模型的适用性会受到尺度效应的影响。为探索该模型在不同观测尺度下的适用程度,本文从地物辐射原理出发,通过理论推导微面元辐射通量表达式,得出地物辐射通量除了与端元反射率和面积比有关外,也与天顶角存在显著的非线性关系。因此,在线性光谱混合模型和微面元辐射通量的基础上,推导了更具普适性的积分线性光谱混合模型的表达式,再采用数值模拟的方法,计算了两模型的相对差值Δρ,结果表明Δρ的大小仅与探测单元的半瞬时视场角β有关,并通过实测光谱实验对上述推论进行了验证。研究表明,当β13°时,Δρ较小,线性光谱混合模型是积分线性光谱混合模型的一种近似表达形式,β完全可作为确定线性光谱混合模型适用观测尺度的关键依据,并且该模型的适用程度随β的增大而降低。