Assessing the opportunities for upstream migration of non-salmonid fishes in the weir-regulated River Vecht

The degree of obstruction posed by weirs to potential upstream movements of non-salmonid fish (predominantly cyprinids) in the River Vecht, the Netherlands, was assessed. This rain-fed river showed high variability in discharge, providing opportunities for passage at high discharge when weirs were free flowing. Daily recorded discharge and water levels between 1960 and 1984, and an analysis of swimming capacities and migratory behaviour, were used to assess whether hydraulic conditions each day and for each species were suitable for ascent. The assessment demonstrated that migratory opportunities along the six weirs were extremely limited. Only 10 of 32 species were able to ascend all weirs in 5–30% of the years. Opportunities were the greatest for large-sized species during November–March at the downstream-situated weirs, whereas small-sized species had no opportunities year-round. The approach used is widely applicable for barrier assessment in other rivers, because it requires only basic hydraulic measurements that are often available.     

Are the long‐term fluctuations in Atlantic bluefin tuna (Thunnus thynnus) population related to environmental changes?

We tested whether synchronous, long‐term fluctuations in Atlantic bluefin tuna (Thunnus thynnus) trap catches, collected from the ancestral Mediterranean and Atlantic trap fishery, might be related to large‐scale environmental change. Nine time series of trap catches of more than 80 yr long were compared with long time series of three preselected environmental variables, i.e. the North Atlantic Oscillation (NAO), the Length of the Day Index (LOD, a proxy of the atmospheric circulation index) and the temperature. Spectral analyses of trap catches, LOD and temperature displayed similar spectra with peaks at low frequencies, whereas those of the NAO exhibited a broad band spectrum. Regression analyses and tests of correlation did not reveal any clear relationship between trap catches on the one hand and NAO and LOD on the other hand. In contrast, long‐term fluctuations in trap catches appear to be closely and negatively related to long‐term trends in temperature. Underlying processes that could explain such a relationship are discussed, with special focus on changes in migration patterns of the Atlantic bluefin tuna.     

Inhibitory Effect of Dihydroaustrasulfone Alcohol on the Migration of Human Non-Small Cell Lung Carcinoma A549 Cells and the Antitumor Effect on a Lewis Lung Carcinoma-Bearing Tumor Model in C57BL/6J Mice

There are many major causes of cancer death, including metastasis of cancer. Dihydroaustrasulfone alcohol, which is isolated from marine coral, has shown antioxidant activity, but has not been reported to have an anti-cancer effect. We first discovered that dihydroaustrasulfone alcohol provided a concentration-dependent inhibitory effect on the migration and motility of human non-small cell lung carcinoma (NSCLC) A549 cells by trans-well and wound healing assays. The results of a zymography assay and Western blot showed that dihydroaustrasulfone alcohol suppressed the activities and protein expression of matrix metalloproteinase (MMP)-2 and MMP-9. Further investigation revealed that dihydroaustrasulfone alcohol suppressed the phosphorylation of ERK1/2, p38, and JNK1/2. Dihydroaustrasulfone alcohol also suppressed the expression of PI3K and the phosphorylation of Akt. Furthermore, dihydroaustrasulfone alcohol markedly inhibited tumor growth in Lewis lung cancer (LLC)-bearing mice. We concluded that dihydroaustrasulfone alcohol is a new pure compound with anti-migration and anti-tumor growth activity in lung cancer and might be applied to clinical treatment in the future.     

祁连山南坡土壤侵蚀时空变化及迁移特征分析

土壤侵蚀是威胁人类生态环境及社会经济的重要因子。为实现土地资源更加有效的保护与治理,基于RUSLE模型和GIS/RS空间信息技术,分析和讨论了祁连山南坡2000—2019年土壤侵蚀时空变化及土壤侵蚀重心迁移特征。结果表明:祁连山南坡土壤侵蚀模数在空间变化上整体呈现出由西北向东南递减的趋势,土壤侵蚀模数平均值由2000年的1 966.63 t/(km²·a)增加至2005年的3 228.51 t/(km²·a),最后下降至2019年的2 299.06 t/(km²·a); 草地土壤侵蚀量最大,为2.65×10⁷～4.25×10⁷ t/a,虽侵蚀较为严重,但土壤侵蚀重心并未发生较大的迁移,五县中祁连县土壤侵蚀最为严重且重心迁移距离最大,侵蚀量为3.01×10⁷～4.83×10⁷ t/a,共迁移351.89 m,迁移速率为17.59 m/a,说明祁连县土壤侵蚀不稳定,土壤低级侵蚀更容易向高级侵蚀转化; 土地利用类型中冰川迁移最大为367.78 m,迁移速率为18.39 m/a。综合得出,对于土壤侵蚀较轻且重心迁移不大的区域可以采取定点治理,对于祁连县应长时间监测,全力推进祁连县水土保持综合治理工程,缓解水土流失; 相较于其他生态系统,对于草地与林地应加强治理。     

灾害风险视域下避灾移民的迁移机理与现状及对策

灾害胁迫下的人类生产生活面临日益严峻的挑战,自然灾害风险已成为制约可持续发展的重要因素。本文通过对灾害风险的基本内涵、形成机制、主导因素的分析,结合近年来自然灾害、气候变化对避灾移民工程的决策、实施的影响情况,探讨了灾害风险下的避灾移民搬迁机理、现状与对策;总结现阶段包括避灾移民在内的灾害型移民的总体特征,并发现其已有和潜在的问题;最后从系统性调控的角度,探讨了灾害风险视野下避灾移民的理念、方法和路径。     

水生植物生态学研究进展

水生植物研究对于多个领域的研究都有十分重要的价值和意义.为了更清晰地展现近年人们对水生植物的研究动态,本文主要通过对比不同水生植物在环境治理方面的应用及其效果,综述水生植物在鸟类栖息地和迁徙过程中所起作用,以及新技术在水生植物研究中的应用等水生植物生态学的研究进展,详述了水生植物的定义,总结了水生植物治理污水的有效的方法,为水生植物生态学的进一步研究提供参考.     

农牧交错区土地利用重心迁移研究——以河北省沽源县为例

基于Landsat TM数据和GIS技术,通过土地利用变化和重心迁移理论对农牧交错区河北省沽源县30多年土地利用的空间演变情况进行分析。结果表明：研究区农业用地和草地占主要地类,1980—2013年土地利用重心有明显迁移;农业用地重心向东北迁移,迁移距离为4 595.79 m;林地重心向东南方迁移,迁移距离为3 820.62 m;草地和建设用地重心向西北方迁移,迁移距离分别为5 294.75、1 220.91 m;水域重心迁移距离较小;未利用土地重心向西南方迁移,迁移距离为4 552.13 m。自然因素对沽源县土地利用空间变化起到一定的推动作用,政策推动等人类活动干扰则是主要驱动因素。     

模拟酸雨作用下红壤中多环芳烃的释放及纵向迁移特征

以USEPA优先控制的16种多环芳烃为研究对象,通过酸雨的土柱淋溶试验模拟实际降水过程,分析了不同酸度的模拟酸雨淋溶后红壤中多环芳烃残留量的变化及不同性质多环芳烃在土柱中纵向迁移特征。研究结果表明:不同酸度模拟酸雨淋溶后红壤中多环芳烃残留量均较淋溶前减少,pH2.5酸雨淋溶后红壤中多环芳烃含量较淋溶前减小的幅度最大(52.08%),pH5.6酸雨淋溶后减小的幅度最小(21.55%);酸雨破坏土壤微结构,使土壤胶体分散,粘粒下移,与土壤粘粒结合在一起的多环芳烃也一起向下迁移,酸雨pH值越小,多环芳烃在土壤中的纵向迁移能力就越强;酸雨对土壤中不同性质多环芳烃的纵向迁移影响不同,对低环多环芳烃(环数≤4)的迁移影响较大,对高环多环芳烃(环数4)影响较小,主要是由于不同性质多环芳烃在土壤中结合的物质不同而引起的。该研究结果为了解酸雨作用下多环芳烃在土壤介质中的稳定性及其对地下水潜在污染的风险评价提供理论依据。     

Coexistence of anadromous and lacustrine life histories of the shirauo, Salangichthys microdon

The environmental history of the shirauo, Salangichthys microdon, was examined in terms of strontium (Sr) and calcium (Ca) uptake in the otolith, by means of wavelength dispersive X‐ray spectrometry on an electron microprobe. Anadromous and lacustrine type of the shirauo were found to occur sympatric. Otolith Sr concentration or Sr : Ca ratios of anadromous shirauo fluctuated strongly along the life‐history transect in accordance with the migration (habitat) pattern from sea to freshwater. In contrast, the Sr concentration or the Sr : Ca ratios of lacustrine shirauo remained at consistently low levels throughout the otolith. The higher ratios in anadromous shirauo, in the otolith region from the core to 90–230 μm, corresponded to the initial sea‐going period, probably reflecting the ambient salinity or the seawater–freshwater gradient in Sr concentration. The findings clearly indicated that otolith Sr : Ca ratios reflected individual life histories, enabling these anadromous shirauo to be distinguished from lacustrine shirauo.