黄河流域被子植物和陆栖脊椎动物丰富度格局及其影响因子

生物多样性的大尺度空间分布格局及其形成机制一直是生态学和生物地理学的核心内容。黄河流域是我国重要的生态屏障, 明确该区域动植物多样性分布格局及其影响因素, 对我国黄河流域生态保护和高质量发展具有重要意义。本研究通过收集黄河流域被子植物和陆栖脊椎动物分布数据, 结合气候、环境异质性和人类活动等信息, 探讨了黄河流域被子植物和陆栖脊椎动物物种丰富度格局及其主要影响因素。结果表明, 黄河流域被子植物和陆栖脊椎动物物种丰富度在区域尺度具有相似的分布格局: 南部山地动植物物种丰富度最高, 而东部高寒区和北部干旱区物种丰富度最低。回归树模型表明, 冠层高度范围和净初级生产力范围分别是黄河流域被子植物和陆栖脊椎动物物种丰富度最重要的预测因子; 当移除空间自相关影响后, 环境异质性和气候因子依然对区域尺度的动植物物种丰富度具有较高且相似的解释度。表明环境异质性和气候共同决定了黄河流域被子植物和陆栖脊椎动物物种丰富度格局, 而人类使用土地面积并不是影响黄河流域动植物物种丰富度格局的主要因子。因此, 在未来的研究中若针对不同区域筛选出更精准的环境驱动因子或选用更多不同类别的环境异质性因子进行分析, 将有助于更深入理解物种多样性格局的成因。     

滦河上游——白枕鹤西部种群的重要停歇地

白枕鹤(Grus vipio)为国家II级重点保护野生动物, 被IUCN列为易危(VU)物种。白枕鹤西部种群繁殖于中蒙俄交界处的达乌尔地区, 数量呈下降趋势。我们于2017-2018年在蒙古国东部给白枕鹤西部种群的50只个体佩戴了GPS-GSM跟踪设备。截至2019年5月, 获得春季和秋季迁徙路径各48条。分析结果显示: 春季91.67%和秋季72.91%的跟踪个体在滦河上游(河北省沽源-内蒙古正蓝旗-多伦区域)停歇, 春季停留时间36.16 ± 15.00天、秋季20.26 ± 11.08天, 分别占春季和秋季迁徙时间的75%和67%, 确定了这一区域是西部种群迁徙途中最重要的停歇地。迁徙路线栖息地选择模型结果显示, 白枕鹤常在距离湖泊较近(< 210 km)、海拔1,200-1,500 m, 且坡度小(< 1°)的区域停歇。而滦河上游和整条迁徙路线停歇位点比较的模型结果显示, 滦河上游停歇地的海拔1,200-1,500 m与整条迁徙路线栖息地选择模型的结果一致; 此外这个区域离河流更近(< 70 km), 不仅有湿地和水体的栖息环境, 还有草地和农田可供觅食和栖息。保护空缺分析发现滦河上游现有四处保护地, 但在保护地内的迁徙停歇点不超过总位点的1.63%。综上, 我们建议将滦河上游整体纳入保护地体系进行管理, 为这一受胁物种及其栖息地管理和保护提供可靠保障。     

黄河三角洲潮间带及近岸浅海大型底栖动物物种组成及长周期变化

黄河三角洲湿地是渤海重要的生态功能区, 在生物多样性保护与生态功能恢复方面发挥着重要作用。为系统研究该区域内大型底栖动物群落物种组成及时空分布, 作者在该区域典型潮间带和近岸浅海(5 m以浅水域)布设11个断面, 分别于2016年8月和11月, 2017年5月、8月和11月进行3个季节取样。结果显示: 黄河三角洲潮间带和邻近海域共发现大型底栖动物187种。其中, 潮间带分布119种, 近岸浅海分布99种。黄河三角洲潮间带和近海大型底栖动物物种组成均具有明显的时空差异。与历史资料相比, 黄河三角洲潮间带和近岸浅海大型底栖动物物种组成发生了明显变化, 动物个体呈小型化趋势。总体表现为自20世纪90年代末至今, 个体大的甲壳动物和软体动物经济类群逐渐被个体小且经济价值较低的多毛类、双壳类和甲壳动物取代。引起上述变化的原因复杂, 主要驱动力包括黄河来水量与输沙量的减少、人类活动(过度捕捞、开发力度加大)和互花米草(Spartina alterniflora)入侵。     

海南岛干旱地区昌化江径流变化及影响因素

识别降水量和径流量变化过程及其影响因素对流域生态安全有重要意义。以海南岛干旱区昌化江流域主要控制水文站宝桥站58年(1956-2013年)水文资料为基础, 采用肯德尔秩次相关等统计方法和GIS技术研究流域内降水径流的变化特点及变化原因。结果表明: (1)降水和径流序列均呈缓慢上升趋势, 但2003年后径流序列有明显下降。(2)应用有序聚类分析径流系数跳跃成分, 结果显示1989年和2003年前后发生了较大改变。(3)将1956-1988年作为无人类活动影响的基准期, 建立降水-径流关系, 分析人类活动对径流变化过程的影响, 表明人类活动的间接影响使昌化江径流量减小, 流域植被覆盖率减少使蒸发作用加大, 导致径流量降低。(4)2003-2013年人类的活动影响使得昌化江径流量大幅减少, 其中直接影响减少量63.5 mm, 间接影响减少量为53.7 mm, 总减少量为117.1 mm, 人类活动综合影响对径流量下降的贡献率为13.9%。禁止砍伐热带雨林, 减少种植经济作物对维护流域生态安全尤为关键。     

Cryptic speciation in the ectocommensal Bdelloura candida (Platyhelminthes,Tricladida, Maricola) follows habitat specialization of the American horseshoe crab,Limulus polyphemus

In strict symbiotic associations, the genetic structure of the symbiont often mirrors that of its host, with interesting implications for population dynamics and phylogeography. An unresolved case of symbiotic specificity and phylogeographic consequence is the relationship between the marine triclad Bdelloura candida and its host, the American horseshoe crab, Limulus polyphemus. A recent study by Riesgo et al. (2017, Marine Biology, 164, 111) identified a strong genetic break between populations of B. candida in the Gulf of Mexico and the Atlantic Ocean but had minimal sampling around the Florida peninsula such that the exact location of the boundary zone was not specified. To solve this, a comprehensive analysis of 16S rRNA and ITS2 genetic markers was conducted from new collections around the Florida peninsula. A clear and significant genetic break was identified between populations of supposed B. candida between Cumberland Island, Georgia, and Mosquito Lagoon, Florida. This genetic break establishes two cryptic lineages, an Atlantic population as far south as Georgia and a Floridian population inclusive of the entire peninsula and Gulf of Mexico, potentially due to niche partitioning of the unique intertidal habitats of its horseshoe crab hosts in Florida. This result directly refutes the previous hypothesis that a population break exists between the coasts of the Atlantic Ocean and Gulf of Mexico, and instead matches the genetic break of its host. Furthermore, a third cryptic lineage was identified in Key West. Overall, this work demonstrates the challenges in maintaining genetic connections between populations of both B. candida and L. polyphemus across their distributions, and poses meaningful implications for both species in the larger context of marine conservation and biodiversity.     

Concentration of toxic metals and potential risk assessment in edible fishes from Congo River in urbanized area of Kinshasa,DR Congo

Abstract

The objective of this research is to determine the concentration and potential health risks of toxic metals in six most consumed freshwater fish species (Auchenoglanis occidentalis, Bagrus ubangensis, Citharinus gibbosus, Distichondus fasciolatus, Marcusenius moorii, and Schilbe mystus). A total of 126 samples of these fish species were collected from seven sites of Congo River in the vicinity of Kinshasa City, Democratic Republic of the Congo. Toxic metals (Cr, Co, Ni, Zn, Se, Ag, Cd, Sn, Sb, and Pb) levels in fish muscle tissues were determined using Inductively Coupled Plasma Mass Spectrometry whereas Hg analysis was carried out using atomic absorption spectrophotometry. The maximum metal concentration (mg kg^?1 wet weight) of Zn (59.72), Sb (5.98), and Pb (4.96) was detected in muscle tissues of M. moorii, C. gibbosus, and D. fasciolatus, respectively. Pb, Zn, and Hg values in many fish samples exceeded the permissible levels set by Food and Agriculture Organization and World Health Organization for human consumption. Given the concentrations of Pb in all fish species and Zn in M. moorii, human health implications are likely to occur on continuous consumption. Addition, the evaluation of potential health risks for fish consumers indicates that there may or not be adverse effects.     

Geological events play a larger role than Pleistocene climatic fluctuations in driving the genetic structure of Quasipaa boulengeri (Anura: Dicroglossidae)

Paleoclimatic and paleogeological events have been identified as being the two main drivers of genetic structuring in extant organisms. We used a montane stream‐dwelling frog, Quasipaa boulengeri, to explore the relative roles played by these drivers on species in southern China, a region needing thorough studies. We detected four major matrilines, and no broadly distributed haplotypes occurred. The complex orogenesis of south‐western China drove matrilineal divergence in Q. boulengeri into highly structured geographical units. These matrilines subsequently persisted in situ with stable populations rather than undergoing expansions during glacial cycling. The unification of the upper and middle Yangtze River in the Three Gorges mountain region mediated downstream colonization of this frog. Analyses identified geological events as playing a larger role than climatic fluctuations in driving the population history of Q. boulengeri. Nuclear allele analyses indicated gene flow; this maintained genetic cohesion of the species. South‐eastern Sichuan Basin was identified as the area of secondary contact for several matrilines, and this area deserves further study and special protection.     

北京市南沙河沉积物重金属污染特征及风险评价

北京南沙河是海淀北部地区的重要排水和风景观赏性河道,为全面了解南沙河底泥沉积物中重金属的污染特征,采集了表层沉积物样品,分析了重金属元素的含量和形态,并利用单因子指数法、Hakanson综合污染指数法和潜在生态风险指数法对沉积物重金属进行了生态风险评价.结果表明:南沙河表层沉积物各种重金属元素存在较好的同源性,污染程度为:Cr＞Cd＞Zn＞Cu＞Pb＞Ni.基于单项潜在生态风险指数的评价表明,该区域重金属生态风险等级由强至弱依次为:Cd＞Pb＞Cu≈Cr＞Ni≈Zn,其中,仅Cd具有较高的潜在生态风险,综合潜在生态风险指数表明,除了京藏高速桥河段危害等级较高外,南沙河总体处于轻微的生态风险等级.形态分析表明,Cd的酸提取态含量高,迁移性最强,最容易对生物造成直接危害,其次是Pb和Zn,Cu和Ni具有一定程度的潜在环境危害,Cr产生环境危害的可能性较小.     

三峡库区175 m蓄水对小江回水区主要经济鱼类能量来源的影响

2010年三峡大坝首次成功蓄水到175 m.为了探讨175 m蓄水对库区支流鱼类食物网能量来源的影响,采用稳定性同位素方法并结合多源线性混合模型(IsoSource模型)对小江回水区鲫、鲤、蒙古鲌、鲇、大鳍鳠、瓦氏黄颡鱼、光泽黄颡鱼等7种主要经济鱼类能量来源进行了分析.结果表明:蓄水前(2010年7月),微型藻类是7种主要经济鱼类能量的主要来源;蓄水后(2010年12月),微型藻类对7种主要经济鱼类能量来源的贡献比例略有下降,而陆生C4植物的相对贡献比例明显增加,特别是对杂食性鲫和肉食性鲇的贡献率分别达到了38％ ～54％和32％ ～ 50％.蓄水后,鲫和鲇至少有30％的能量来自陆生C4植物.说明三峡大坝的蓄水过程增加了外源性C4植物对鱼类能量的贡献比例.