基于灯光数据的中国县域城镇建设用地产出效率时空演变特征

本文以灯光密度表征建设用地产出效率,采取KDE、ESDA、SDE等方法对中国县域尺度2000-2015年建设用地产出效率的总体特征、时空演变以及方向分布进行分析,研究发现：① 夜间灯光总亮度与建设用地出产出存在较强的相关关系,说明可用灯光总亮度表征建设用地产出,以灯光密度反映建设用地产出效率具有一定的科学性。② 建设用地产出效率东高西低,持续上升;增长速度西高东低,中部居中,但区域间年均增长率最大相差0.56%,整体较为均衡。③ 虽然建设用地产出效率由2000年的0.008单位灯光/km²持续上升至2015年的0.025单位灯光/km²,但其核密度曲线始终处于中低水平且右侧区间不断扩大,说明中国建设用地产出效率总体水平较低,呈现出中低水平俱乐部收敛的特征。④ 建设用地产出效率的全局 Moran's I指数都大于0,建设用地产出效率存在正向空间分布特征,且其局部空间格局变化较小,存在稳中有动,强中有弱,弱中有强的特点。⑤ 方向分布上,建设用地产出效率的方位角始终在72.420^o与81.066^o之间,说明东北-西南方向为建设用地产出效率的主要方向,且标准差椭圆的主轴与辅轴标准差都有所增加,说明在建设用地产出效率的主要方向与次要方向上都发生了分散现象。     

智利外海茎柔鱼(Dosidicus gigas)耳石外部形态特征分析

根据2008年1—5月智利外海茎柔鱼资源调查中随机采集的663尾样本(雌性464尾,雄性199尾),对其耳石形态特征进行观察与测量。观测表明,茎柔鱼耳石具有长窄的吻区和宽大的翼区。对耳石10项形态参数进行主成分分析,结果显示,耳石总长(TSL)、吻侧区长(RLL)、翼区长(WL)可以作为耳石长度特征的代表,最大宽度(MW)则可代表耳石宽度特征。雌性个体TSL、RLL、WL和MW与胴长(ML)之间为线性关系(Y=a+b×ML)(P0.05),生长系数b在1.9358—2.9607间,其中MW的最小,WL的最大,耳石各区为均匀生长。雄性个体TSL、RLL、WL和MW与ML之间为幂函数关系(Y=c×MLd)(P0.05),生长系数d在0.9165—1.1877间,其中TSL生长速度慢于ML,RLL和MW基本与ML一致,WL则快于ML,耳石各区为非均匀生长。     

The effects of trophic interactions and spatial competition on algal community composition on Hawaiian coral reefs

Much of coral reef ecology has focused on how human impacts change coral reefs to macroalgal reefs. However, macroalgae may not always be a good indicator of reef decline, especially on reefs with significant sea urchin populations, as found in Kenya and Hawaii. This study tests the effects of trophic interactions (i.e. herbivory by fishes and sea urchins) and spatial competition (between algae and coral) on algal community structure of reefs surrounding two Hawaiian Islands that vary in their level of human impacts. Reef‐building organisms (corals and crustose coralline algae) were less abundant and turf algae were more abundant on Maui as compared to Lanai, where human impacts are lower. In contrast to previous studies, we found no evidence that macroalgae increased with human impacts. Instead, low turf and macroalgal abundance were best explained by the interactive effects of coral cover and sea urchin abundance. Fishing sea urchin predators appeared to have cascading effects on the benthic community. The absence of sea urchin predators and high sea urchin densities correspond to a disproportionately high abundance of turf and crustose coralline algae. We propose that high turf algal abundance is a better indicator of reef decline in Hawaii than high macroalgal abundance because turf abundance was highest on reefs with low coral cover and few fish. The results of this study emphasize that understanding changes in community composition are context‐dependent and that not all degraded reefs look the same.     

Role of sea surface temperature and rainfall in determining the stock and fishery of the common octopus (Octopus vulgaris,Mollusca, Cephalopoda) in Tunisia

Octopus (Octopus vulgaris, Mollusca, Cephalopoda) is an important and valuable fishery resource on the eastern and southern coasts of Tunisia, but its landings are highly variable. This paper explores the effect of environment on octopus catch per unit effort (CPUE) during a 12‐year period, through correlation analyses and the incorporation into surplus production models of sea surface temperature (SST) and rainfall data collected during cold (January–May) and hot (August–October) seasons. CLIMPROD software was used to select the appropriate model and fit it to the fishery and environment data. In both seasons, SST significantly contributed to CPUE variability; fishery production was influenced positively by cold season SST but negatively by hot season SST. Due to a poor fit with cold season data, the impact of rainfall was analysed only for the hot season, during which it has a positive effect on production. Results are discussed in view of the life‐cycle of octopus and the dynamics of the Tunisian fishery. This first study of octopus variability in Tunisia highlights the necessity to incorporate environmental influence into stock assessment and management advice.     

Changes in survivorship,behavior, and morphology in native soft‐shell clams induced by invasive green crab predators

Many studies on invasive species show reduced native densities, but few studies measure trait‐mediated effects as mechanisms for changes in native growth rates and population dynamics. Where native prey face invasive predators, mechanisms for phenotypic change include selective predation, or induced behavioral or morphological plasticity. Invasive green crabs, Carcinus maenas, have contributed to declines in native soft‐shell clams, Mya arenaria, in coastal New England, USA. We tested the hypothesis that clam ability to detect chemical cues from predators or damaged conspecifics would induce greater burrowing depth as a refuge from invasive crabs, and greater burrowing would require increased siphon growth. To determine how crab predation affected clam survivorship and phenotypic traits in the field, clams in exclosure, open, and crab enclosure plots were compared. Crab predation reduced clam density, and surviving clams were deeper and larger, with longer siphons. To determine whether the mechanism for these results was selective predation or induced plasticity, phenotypes were compared between clams exposed to chemical cues from crab predation and clams exposed to seawater in laboratory and field experiments. In response to crab predation cues, clams burrowed deeper, with longer siphons and greater siphon mass. Overall, crab predation removed clams with shorter siphons at shallow depths, and crab predation cues induced greater burrowing depths and longer siphons. Longer siphons and greater siphon mass of deeper clams suggests clams may allocate energy to siphon growth in response to crabs. By determining native behavior and morphological changes in response to an invasive predator, this study adds to our understanding of mechanisms for invasive impacts and illustrates the utility of measuring trait‐mediated effects to investigate predator–prey dynamics.     

Biological structures as a source of habitat heterogeneity and biodiversity on the deep ocean margins

Biological structures exert a major influence on species diversity at both local and regional scales on deep continental margins. Some organisms use other species as substrates for attachment, shelter, feeding or parasitism, but there may also be mutual benefits from the association. Here, we highlight the structural attributes and biotic effects of the habitats that corals, sea pens, sponges and xenophyophores offer other organisms. The environmental setting of the biological structures influences their species composition. The importance of benthic species as substrates seems to increase with depth as the complexity of the surrounding geological substrate and food supply decline. There are marked differences in the degree of mutualistic relationships between habitat-forming taxa. This is especially evident for scleractinian corals, which have high numbers of facultative associates (commensals) and few obligate associates (mutualists), and gorgonians, with their few commensals and many obligate associates. Size, flexibility and architectural complexity of the habitat-forming organism are positively related to species diversity for both sessile and mobile species. This is mainly evident for commensal species sharing a facultative relationship with their host. Habitat complexity is enhanced by the architecture of biological structures, as well as by biological interactions. Colony morphology has a great influence on feeding efficiency for suspension feeders. Suspension feeding, habitat-forming organisms modify the environment to optimize their food uptake. This environmental advantage is also passed on to associated filter-feeding species. These effects are poorly understood but represent key points for understanding ecosystems and biodiversity on continental margins. In this paper we explore the contributions of organisms and the biotic structures they create (rather than physical modifications) to habitat heterogeneity and diversity on the deep continental margins.     

海冰爬坡和堆积行为的试验研究

对于浅海区采油平台等设施常采用斜坡式人工岛形式,虽然在一定程度上起到降低海冰对平台的作用,但是海冰沿着斜坡上爬至平台并形成堆积,同样也会对平台设施造成破坏,因此有必要对海冰堆积爬坡的关键参数进行研究。通过在冰排前进方向放置混凝土实体结构物模拟海冰堆积和爬坡过程,分析了模型冰爬坡和下滑角度、最大堆积高度等关键参数以及模型冰断裂长度的统计特性及其与变形模量的关系,试验结果表明水位越高,冰排越容易发生堆积爬坡。破碎的模型冰在结构物前堆积后,形成爬坡角和下滑角。爬坡角随着堆积体的增大而增大,下滑角则逐渐减小。堆积冰高度一定时,高度不再增加,在来冰方向会形成新的堆积。这种现象为浅海区海上结构物的防冰减灾提供了新思路。     

东海陆扰海域铜、铅、锌、镉重金属排海通量及海洋环境容量估算

汇总并分析了20世纪80年代初以来东海陆扰海域重金属排海通量年变化规律及主要来源,应用多介质海洋环境中重金属迁移-转化模型,估算了东海陆扰海域重金属海洋环境容量。20世纪80年代初以来,东海陆扰海域铜、铅、锌、镉排海总量整体上呈不对称的倒"U"形变化趋势,基本符合"环境库兹涅茨曲线",20世纪90年代达到最大值,当前排海总量仍高于20世纪80年代初期的水平。东海陆扰海域铜、铅、锌、镉污染物主要来源于以河流为主的陆源排放,其中88.0%左右来源于河流排放,7.5%左右来源于排污口,只有4.5%左右来源于大气沉降。长江流域排海通量占东海陆扰海域排海总量的比例最大,平均为92.4%左右,钱塘江流域平均只有3.9%左右,闽江流域平均只有3.7%左右。东海陆扰海域铜、铅、锌、镉污染物海洋环境容量分别约为17.0,4.7,113.1,0.71 kt/a。当前铅、锌、镉污染物排海总量没有超过东海陆扰海域海洋环境容量,但铜的排海总量超过其海洋环境容量大约8%。