Variation in mesozooplankton community structure in the Japan/East Sea (1991–1999) with possible influence of the ENSO scale climatic variability

Seasonal and interannual change in mesozooplankton community structure in the offshore Tsushima Current area of the Japan/East Sea was studied in relation to climatic events and temporal variability of the upper water column environment from 1991 to 1999. We observed a clear seasonal succession in zooplankton community structure from a cold-water copepod-dominated community in winter and spring to a gelatinous, carnivorous and warm-water copepod-dominated community in summer and autumn. The mean abundance (inds. m⁻³) of the spring community was 3–4-fold higher than that of the other season. The spring community structure varied considerably between years: the community characterized by the summer–autumn type zooplankton assemblage appeared in 1991–1993 and 1998, while the community characterized by high abundance of cold-water copepods appeared in the mid 1990s. Time series profiles of water density and nutrients showed the thickness of the surface warm Tsushima Current and the cold subsurface water increased and decreased, respectively, limiting nutrient supply to the surface water in 1992 and 1998. These results suggest that a thick, warm surface layer might reduce the reproductive success and survival ratio of the cold-water copepods both directly and indirectly, by hindering their upward migration to the surface where food is available, and by limiting phytoplankton growth due to nutrient depletion, respectively. A Monsoon Index (MOI) showed weaker winter wind stress in 1992 and 1998, which might have attenuated formation of the cold subsurface layer in the northern Japan/East Sea and been responsible for surface warming of the study area. Since 1992 and 1998 were El Niño years, this study revealed that ENSO related climatic variability on an interannual time scale considerably influenced the lower trophic level ecosystem in the Japan/East Sea.     

2001/2002年夏季南极普里兹湾及其邻近海域的浮游植物

报道了 2 0 0 1 /2 0 0 2年夏季南极普里兹湾邻近海域 3 7个大面测站浮游植物的调查结果。经初步鉴定共有浮游植物 3门 3 7属 86种 ,其中硅藻在种类和细胞丰度上占绝对优势 ,其次为甲藻。主要优势种为克格伦拟脆杆藻 (Fragilariopsiskerguelensis)、细条伪菱形藻 (Pseu do nitzschialineola)、短拟脆杆藻 (Fragilariopsiscurta)和赖氏束盒藻 (Trichotoxonreinboldii)等南极特有种类和常见种类。调查区浮游植物分为两个群集 ,分布在 6 7°S以南的普里兹湾内的群集主要以克格伦拟脆杆藻、短拟脆杆藻、胡克星脐藻 (Asteromphalushookeri)和南极弯角藻 (Eu campiaantarctica)等南极特有种类和常见种类为主 ;分布在 6 7°S以北的大洋海域的群集主要以细条伪菱形藻、赖氏束盒藻、拟膨胀伪菱形藻 (Pseudo nitzschiaturgiduloides)和羽状环毛藻(Corethronpennatum)等南极常见种为主。调查区浮游植物的平均细胞丰度为 (8796± 2 92 85 )ind/L ,细胞多分布于海水的表层 ,密集区分布在 6 7°S以南的普里兹湾内 ,浮游植物的细胞丰度同硝酸盐的浓度密切相关。调查区浮游植物的多样性程度是低的。     

Foregone harvests and neoliberal policies: Creating opportunities for rural,small-scale,community-based fisheries in southern Alaskan coastal villages

Neoliberal policies of effort limitation and privatization have reduced commercial salmon and other fishing opportunities available to the coastal, predominantly Alaska Native, villages of southern Alaska. However, there are a variety of circumstances, including the manner in which the current commercial fishery is prosecuted, that lead to surpluses of unharvested salmon, and potentially other species, available in certain areas. This paper will define the concept of “foregone harvests”, discuss the environmental and managerial conditions that lead to “foregone harvests” and describe the possibilities such conditions create for the development of small-scale, local and community-based fisheries. Case studies of possible Huna Tlingit (Hoonah) and Kaigani Haida (Hydaburg) salmon fisheries will be presented. Alternative arrangements of salmon fisheries and institutions in southeast Alaska are presented through case studies of the villages of Yakutat and Metlakatla. These examples demonstrate how such fisheries could be built on local and traditional knowledge, as well as currently used subsistence technologies resulting in new economic opportunities compatible with local cultural patterns and interests and buttressing local identities and commitments.     

人类活动排放的CO2及气溶胶对20世纪70年代末中国东部夏季降水年代际转折的影响

全球变暖背景下,中国东部夏季降水在20世纪70年代末开始较19世纪呈现东北及长江中、下游地区多雨,华北及华南少雨的特征。与此同时,人类活动排放的CO₂及气溶胶量也发生了明显的年代际变化。文中利用地球系统耦合模式（CESM）诊断了中国东部夏季的水分收支对人类活动排放的CO₂及气溶胶年代际变化的响应。发现CO₂排放量增加后,江淮流域的水汽辐合以及中国南方的水汽辐散主要是与质量辐散有关的动力项及与湿度梯度相关的热力项共同作用的结果,但动力作用更显著。气溶胶效应则主要通过动力作用使得江淮流域水汽辐合,而中国南方地区水汽辐散。虽然CO₂和气溶胶对辐射量及温度的影响差别很大,但通过改变温度梯度,热成风效应产生的动力作用都会导致江淮流域上升运动增强,降水增多;而中国南方下沉运动显著,降水减少,与观测结果一致,且CO₂相较于气溶胶的影响更为显著,证实了20世纪70年代末人类活动对中国东部夏季降水年代际转折的影响。      

城市脆弱性的动态演变与模拟预测

针对目前对我国西部城市的城市脆弱性综合研究比较缺乏的现状,以乌鲁木齐市为主要研究对象,筛选出50个具体评价指标,从资源、生态、社会和经济等四个方面构建了城市脆弱性评价指标体系,并采用综合指数分析法,对乌鲁木齐市2006—2016年的城市脆弱性进行了综合评价。结果表明：2006—2016年乌鲁木齐市城市综合脆弱性指数处于下降状态;生态脆弱性和经济脆弱性呈现出不同程度的下降趋势,资源脆弱性整体上较为平稳,但社会脆弱性逐渐增长,尤其是在2014—2016年的增长趋势更加明显。此外,构建了三套预测模型,并从中优选出精度最高的模型对乌鲁木齐市城市脆弱性进行了预测。得出2016—2019年乌鲁木齐市的城市脆弱性会呈现上升,2019年后趋于下降。最后,有针对性地提出了乌鲁木齐市在未来城市发展中减少城市脆弱性需要注意和改善的问题。相关内容可为乌鲁木齐市城市脆弱性的调控决策提供科学依据,为我国其他中西部城市的城市脆弱性研究提供参考。     

The use of time-series data in the assessment of macrobenthic community change after the cessation of sewage-sludge disposal in Liverpool Bay (UK)

Sewage sludge was disposed of in Liverpool Bay for over 100 years. Annual amounts increased from 0.5 million tonnes per annum in 1900 to approximately 2 million tonnes per annum by 1995. Macrofauna and a suite of environmental variables were collected at a station adjacent to, and a reference station distant from, the disposal site over 13 years, spanning a pre- (1990-1998) and post- (1999-2003) cessation period. Univariate and multivariate analyses of the time-series data showed significant community differences between reference and disposal site stations and multivariate analyses revealed station-specific community development post-disposal. Temporal variability of communities collected at the disposal station post-cessation was higher than during years of disposal, when temporally stable dominance patterns of disturbance-tolerant species had established. Alterations of community structure post-disturbance reflected successional changes possibly driven by facilitation. Subtle faunistic changes at the Liverpool Bay disposal site indicate that the near-field effects of the disposal of sewage sludge were small and therefore could be considered environmentally acceptable.     

Theorizing food insecurity: building a livelihood vulnerability framework for researching food insecurity

Food insecurity and increasing impoverishment of the masses in developing countries constitute a challenge for social scientists, whose theories have tried to catch up with the enormous challenges of diversity, dynamism and the impacts of the forces of­‘glocalisation’. This article reviews the efforts in the social sciences towards understanding food insecurity and suggests a framework incorporating dynamism and diversity in rural communities in the research process. Structural changes affecting peasant economies and peasant responses make existing general theories inappropriate without a contextual treatment. Insights from existing theories are used to construct a livelihood vulnerability framework for researching and understanding food insecurity in rural areas.