多类群水鸟共存栖息地网络结构稳定性及其优化方案——以盐城滨海湿地为例

作为新设立的世界自然遗产地,盐城滨海湿地水鸟栖息地保护受到广泛关注。鉴于该区域在全球生物多样性与水鸟栖息地保护中重要性,针对具有空间隔离特征的水鸟栖息地开展网络稳定性研究,对提高遗产地栖息地保护质量具有重要的示范意义。基于此,利用复杂网络理论、生态踏脚石原理和电流模型,分析了盐城滨海湿地多类群水鸟栖息地网络结构现状及不同情景下网络鲁棒性。研究结果显示,三类水鸟重要生境区主要分布在各栖息地内部以及大丰至条子泥栖息地一带,其中,北部生境区数量为18个,南部生境区6个。北部生境区总面积相当于南部生境区的1/2,而平均面积仅相当于1/6。从踏脚石分布来看,其主要分布在重要生境区附近,不同栖息地存在差异。研究区踏脚石网络由35个重要节点和153个一般节点组成,南北部网络结构要素存在差异。最佳保护情景下,网络鲁棒性表现较好,中心度值大的节点对整个网络连通性的支撑作用良好。提出了栖息地网络优化方案。     

Seed dispersal by waterbirds in southern Africa: comparing the roles of ectozoochory and endozoochory

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Changes in biotic communities developing from freshwater wetland sediments under experimental salinity and water regimes

1. Reduction in diversity of both freshwater aquatic and terrestrial ecosystems has been attributed to salinity increase and such increases are a symptom of changes to land use. Hydrological alteration to ground and surface water are likely to be associated with salinity increase and its influence on biodiversity. However the combined effects of salinity and hydrology on aquatic biodiversity have not been elucidated fully in either field or experimental situations. 2. The effect of salinity and water regime on the biota in sediments from seven wetlands from inland south‐eastern Australia was tested experimentally using germination of aquatic plant seeds (five salinity and two water levels) and emergence of zooplankton eggs (five salinity levels). Salinity levels were <300, 1000, 2000, 3000, 5000 mg L^?1 and water regimes were damp (waterlogged) and submerged. 3. Aquatic plant germination and zooplankton hatching was not consistent for all seven wetland sediments. Four of the wetland sediments, Narran Lakes, Gwydir Wetlands, Macquarie Marshes and Billybung Lagoon showed similar responses to salinity and water regime but the other three wetland sediments from Lake Cowal, Great Cumbung Swamp and Darling Anabranch did not. 4. As salinity increased above 1000 mg L^?1 there was a decrease in the species richness and the abundance of biota germinating or hatching from sediment from four of the wetlands. 5. Salinity had a particularly strong effect in reducing germination from sediments in damp conditions when compared to the flooded conditions. In parallel, salts accumulated in the sediment in damp conditions but did not in flooded conditions. 6. There is potential for increasing salinity in freshwater rivers and wetlands to decrease the species richness of aquatic communities and thus of the wetland community as a whole, resulting in loss of wetland biodiversity. This reduction in diversity varies between wetlands and is at least partly related to hydrology. For aquatic plants the reduction in diversity will be more marked for plants germinating from seed banks at the edges of wetlands where plants are not completely submerged than for the same seed bank germinating in submerged conditions.     

The impact of salinity pulses on the emergence of plant and zooplankton from wetland seed and egg banks

1. In this study we compared the emergence of aquatic biota from sediments under 14‐day pulses of high (5000 mg L⁻¹) and low (1000 mg L⁻¹) salinity with emergence under freshwater and equivalent constant salinity levels. We tested the hypothesis that pulses of high salinity and short duration have no impact on the emergence of aquatic plants and zooplankton from wetland sediment. 2. The way salt is moved through the landscape may alter the response of biota to increases in salinity. Under natural hydrological regimes in rivers and floodplains salinity pulses occur often at concentrations that exceed predicted tolerance levels for aquatic biota. The impacts of natural pulses of high salinity followed by rapid return to fresh conditions may be used to inform management guidelines for the potential release of non‐natural saline water into river systems with minimal impact. 3. For both aquatic plants and zooplankton the abundance and richness of the emerging taxa decreased at higher salinities kept at constant levels. In contrast, pulses of salinity followed by return to freshwater conditions did not have a negative impact on the emergence of aquatic plants or zooplankton. For many taxa of zooplankton a positive impact was demonstrated with higher emergence following the salinity pulse. 4. The responses of aquatic plant and zooplankton taxa are grouped into five response types. Type 1: negatively impacted by all salt regimes. Type 2: preference for constant salinities. Type 3: no difference between fresh and either pulse regime. Type 4: preference for high concentration pulses. Type 5: emergence higher under a low concentration pulse. 5. Although previous studies indicate that constant high‐level salinity in rivers and wetlands can decrease the species richness of aquatic communities, this current study shows pulses may not have the same impact. Our results support the hypothesis that pulses of high salinity and short duration do not impact on the emergence of aquatic plants and zooplankton from wetland sediments. For zooplankton, pulses of salt may trigger emergence. 6. These trends may be used to explore the potential to use managed water releases to move salt through the landscape with minimal impact of salinity on aquatic biota. However, before such preliminary results are applied in management of saline water releases we need to determine the implications for interacting processes in natural ecosystems.     

The effects of salinity on aquatic plant germination and zooplankton hatching from two wetland sediments

1. The effect of increasing salinity on the emergence of zooplankton eggs and the germination of aquatic plant seeds from the sediment of two wetlands was examined. Salinity was found to cause reductions in species richness and abundance of aquatic plants and zooplankton at salinities between 1000 and 5000 mg L^?1. Aquatic plants also had an associated decrease in above ground biomass. 2. Individual taxa showed different responses to salinity, and four response patterns were identified: (i) increased number of organisms emerging at 1000 mg L^?1; (ii) decreased number of organisms emerging above 1000 mg L^?1; (iii) decreased number of organisms emerging between 300 and 1000 mg L^?1; (iv) no difference in number of organisms emerging across the range of salinities. Response patterns (iii) and (iv) were common to both plants and zooplankton, whereas response patterns (i) and (ii) were only identified for zooplankton. 3. Results indicate that there is potential for the increasing salinity in Australian rivers and wetlands to decrease the species richness of aquatic communities resulting in loss of wetland biodiversity.     

Oxygen depletion and carbon dioxide and methane production in waters of the Pantanal wetland of Brazil

This study examines dissolved O₂, CO₂ and CH₄ in waters of the Pantanal, a vast savanna floodplain in Brazil. Measurements are presented for 540 samples from throughout the region, ranging from areas of sheet flooding to sluggish marsh streams to the major rivers of the region. Dissolved O₂ is often strongly depleted, particularly in waters filled with emergent vascular plants, which are the most extensive aquatic environment of the region. Median O₂ concentrations were 35 M for vegetated waters, 116 M for the Paraguay River, 95 M for tributary rivers, and 165 M for open lakes (atmospheric equilibrium, 230–290 M). Airwater diffusive fluxes were calculated from dissolved gas concentrations for representative vegetated floodplain waters, based on data collected over the course of an annual cycle. These fluxes reveal about twice as much CO₂ evasion as can be accounted for by invasion of O₂ (overall means in nmol cm^-2 s^-1: O₂ 0.18, CO₂ 0.34, and CH₄ 0.017). Methanogenesis is estimated to account for ca. 20% of the total heterotrophic metabolism in the water column and sediments, with the remainder likely due mostly to aerobic respiration. Anaerobic respiration is limited by the low concentrations of alternate electron acceptors. We hypothesize that O₂ transported through the stems of emergent plants is consumed in aerobic respiration by plant tissues or microorganisms, producing CO₂ that preferentially dissolves into the water, and thus explaining most of the excess CO₂ evasion. This hypothesis is supported by measurements of gases in submersed stems of emergent plants.     

Effects of the emergent macrophyte Juncus effusus L. on the chemical composition of interstitial water and bacterial productivity

Release of oxygen from the roots ofaquatic macrophytes into anaerobic sediments canaffect the quantity of interstitial dissolved organicmatter and nutrients that are available to bacteria. Nutrient and dissolved organic carbon (DOC)concentrations were compared between subsurface(interstitial) waters of unvegetated sediments andsediments among stands of the emergent herbaceousmacrophyte Juncus effusus L. in a lotic wetlandecosystem. Concentrations of inorganic nitrogen(NH₄ ⁺, NO₃ ^-, and NO₂ ^-)were greater from sediments of the unvegetatedcompared to the vegetated zone. DOC concentrations ofinterstitial waters were greater in sediments of theunvegetated zone both in the winter and springcompared to those from the vegetated zone. AlthoughDOC concentrations in hydrosoils collected from bothzones increased from winter to spring, bacterialproductivity per mg DOC in spring decreased comparedto winter. Greater initial bacterial productivityoccurred on DOM collected from the vegetated comparedto the unvegetated zone in winter samples (days 1 and4), with increased bacterial productivity on samplescollected from the unvegetated zone at the end of thestudy (day 20). Bacterial productivity wassignificantly greater on all sampling days on DOM fromvegetated samples compared to unvegetated samples. In nutrient enrichment experiments, bacterialproductivity was significantly increased (p < 0.05)with phosphorus but not nitrogen only amendments.     

湖南境内珍稀,濒危水生植物产地的考察

湖南茶陵湖里沼泽（北纬26°50'、东经113°40'）为一山地沼泽,面积0．15平方公里,海拔150米。对该沼泽的生境及水生植物进行了考察。采集到维管植物62种,其中,普通野稻（Oryza rufipogon）、长喙毛莨泽泻（Ranalisma rostrata）等为珍稀、濒危植物,总种数和珍稀、濒危植物种数多于我国大部分湖泊、沼泽。物种多样性程度之高与其水生生境的复杂性与稳定性有关。建议对这些珍稀、濒危水生植物及其生境采取保护措施。     

汉江中下游水生植物多样性及南水北调工程对其影响

１９９７—２０００年对汉江中下游８个江段水生植物种类组成、分布、生物量做了调查。汉江中下游共有水生植物１８科２２属３４种,以世界广布种为主,Ｒ／Ｔ值为０．６７。中游以沉水植物群落为优势,建群种为轮叶黑藻（Ｈｙｄｒｉｌｌａ　ｖｅｒｔｉｃｉｌｌａｔａ）、穿叶眼子菜（Ｐｏｔａｍｏｇｅｔｏｍ　ｐｅｒｆｏｌｉａｔｕｓ）和微齿服于荣（Ｐ．ｍａａｃｋｉａｎｕｓ）;下游主要为挺水植物群落,建群种为东方香蒲（Ｔｙｐｈａ　ｏｒｉｅｎｔａｌｉｓ）和芦苇（Ｐｈｒａｇｍｉｔｅｓ　ｃｏｍｍｕｎｉｓ）,生物量为５７．５—２１００ｇ／ｍ＾２;α－多样性在丹江口最高（０．５４６）,老河口次之（０．５１７）,仙桃员低（０）;生活型多样性在中游丹江口最大（０．４０２）;β—多样性在时间梯度６—８月份在所有样点β＝０,水平梯度β＝０．７９,垂直梯度β＝１．４８;γ—多样性在汉江中游为２９种,在下游为１０种。中游地区水生环境适合水生植物生长,而下游人类活动导致水环境趋于恶化限制了水生植物分布。     

Engineering and biological approaches to the restoration from eutrophication of shallow lakes in which aquatic plant communities are important components

Engineering approaches (nutrient removal, sediment pumping, hypolimnion oxygenation, alum treatments) may be most appropriate to deep lakes where the aim of restoration from eutrophication is simply to reduce the production and crop of one component, the phytoplankton. They do not always give the desired results because the nutrient loading may only be reduced to a limited extent. There are additional problems in shallow lakes where change of state between community dominance (aquatic plants versus plankton) is wanted. Each community has powerful buffering mechanisms and biomanipulation may be essential to switch one state to another even with considerable nutrient reduction. For the phytoplankton-dominated community the buffers include the advantages of early growth, lower diffusion pathways for CO₂, overhead shading, and an absence of large cladoceran grazers. This later is because open-water shallow environments provide no refuges against predation for the large Cladocera which are both the most efficient grazers and the most favoured prey for fish. Restoration of aquatic plants may then require provision of refuges for the grazers. Different sorts of refuge are discussed using case studies of Hoveton Great Broad and Cockshoot Broad in the Norfolk Broadland.     

A fossil Dendrocygninae (Aves,Anatidae) from the Early Pliocene of the Argentine Pampas and its paleobiogeographical implications

In the present paper, the distal end of a humerus referable to a Dendrocygninae anseriform bird is reported. The specimen was collected at the Monte Hermoso Formation (early Pliocene) of the Farola Monte Hermoso locality (Buenos Aires Province, Argentina). This record constitutes one of the oldest for the group in South America and elsewhere. The overview of the anseriform record in South America indicates a similar pattern to that of other localities across the world. Paleogene localities are dominated by non-Anatinae taxa, whereas more recent faunas are dominated by anatines. Following this pattern, in South America the Anatinae appears in the fossil record as recently as in the Pleistocene, probably arriving from North America during the Great American Biotic Interchange. Pleistocene and Recent anseriform avifaunas are dominated by Anatinae taxa, and this dominance is probably due to some “key characters” regarding reproductive biology. In fact, the anatines exhibit a high reproductive success probably due to the capability of having two molts per year, and that the parental care of the downy young is only conducted by the female. The combination of characters may have allowed anatines to dominate most aquatic environments, surpassing in diversity more plesiomorphic taxa.     

A new genus of the tribe Acratini from the continental Neotropical region (Coleoptera: Curculionoidea,Brentidae)

A group of 10 species belonging to the Neotropical tribe Acratini Alonso-Zarazaga, Lyal, Bartolozzi & Sforzi 1999, is shown to be monophyletic by a phylogenetic analysis based on 48 morphological characters. A new genus, Pertusius n. gen., is described, based on three derived characters of external and genital morphology: venter of prorostrum of males with fine median longitudinal carina, base of elytra with deep pit at the place of insertion on mesonotum, and proximal sclerite of endophallus more or less horseshoe-shaped. Eight species were previously known and, according to former authors, belonged to the genera Acratus Lacordaire 1865 [Pertusius apicalis (Sharp 1895), n. comb., P. errabundus (Kleine 1927), n. comb., P. extrarius (Kleine 1927), n. comb., P. fidus (Kleine 1927), n. comb. and P. telesi (Soares & Meyer 1959), n. comb.] and Proteramocerus Kleine 1921 [Pertusius chalcites (Perty 1832), n. comb., P. filum (Sharp 1895), n. comb., and P. laevis (Germar 1824), n. comb.]. Four new synonymies are proposed: Proteramocerus disparilis Soares & Dias 1971, n. syn. for Acratus apicalis Sharp 1895; Teramocerus laevigatus Boheman 1840, n. syn. for Arrhenodes chalcites Perty 1832; Acratus extraordinarius Kleine 1927, n. syn. for Acratus errabundus Kleine 1927; Proteramocerus diringshofeni Soares & Dias 1971, n. syn. for Acratus filum Sharp 1895. Two new species are described: Pertusius guyanensis n. sp. from French Guiana, and P. mexicanus n. sp. from Mexico (Yucatán Peninsula). Pertusius apicalis is newly cited from Bolivia and Peru, P. chalcites from Argentina and Paraguay, P. extrarius from Ecuador, P. fidus from Peru and P. telesi from Trinidad and Tobago and Venezuela. An identification key to species of the genus is provided.     

Cholesterol is required for the formation of regulated and constitutive secretory vesicles from the trans-Golgi network

We studied the role of cholesterol in regulated protein secretion in neuroendocrine cells by manipulating the cholesterol content of AtT-20 cells. Depletion of cellular cholesterol levels caused a reversible block of immature secretory granule biogenesis at the level of the trans -Golgi-network, whereas increased cholesterol levels promoted immature secretory granule formation. Cholesterol depletion also blocked the formation of constitutive secretory vesicles, but did not inhibit the transport between the endoplasmic reticulum and the Golgi complex. Our results indicate that the assembly of cholesterol-based lipid microdomains is required for the biogenesis of both regulated and constitutive secretory vesicles from the trans -Golgi-network in neuroendocrine cells.     

京津冀城市群生态网络构建与优化

生态安全是人类生活的基本保障,快速城镇化致使大型生态源地破碎化、岛屿化,生态环境问题日益严重。构建生态网络不仅能加强生态源地间的连通性,完善生态功能,还能提高生态系统的综合能力,改善恶化的生态环境问题。以京津冀为研究区,基于地理空间分析技术确定京津冀生态源地,对研究区内的林地、湿地、草地,结合生态红线等进行区域叠加从而完成源地提取;基于最小成本路径方法,考虑土地利用及高程影响因子,提取京津冀城市群生态廊道,分析统计廊道分布情况;结合重力模型与重要生态源地连通性筛选出京津冀重要生态廊道,叠加现有国道、河流构建生态网络,对重要生态节点进行分析。研究结果表明,生态源地面积占研究区总面积比例为21.76%,林地、湿地、草地面积占总生态源地面积分别为82.78%,11.05%,6.17%;不同地貌区域生态源地类型不同,林地主要分布在山区,湿地主要分布在平原区域,草地主要分布在研究区西北部;景观成本值平原区域高于草原和山区,北京、天津、石家庄城区及周边景观成本值最高;采用最小成本路径模型提取廊道579条,其中张家口、承德区域生态网络较好,平原区域生态源地及生态节点缺失较为严重。最后,对北京、天津、白洋淀、衡水湖等重点生态区域提出修复和保护意见,为京津冀城市群发展提供参考。此外,本研究对其他地区生态网络的构建提供理论依据与技术支持。     

Fruits and seeds of Ruppia (Potamogetonaceae) from the Pliocene of Yushe Basin, Shanxi, northern China and their ecological implications

Numerous fruits and seeds of Ruppia are reported from the Upper Pliocene (2.3–3.5 Myr ago) Zhangcun Formation in Yushe Basin, Shanxi, northern China. They are the first fossil Ruppia from China and demonstrate the importance of fruit and seed fossils in recording genera not represented by fossil leaves. These Ruppia are characterized by possessing a small oval endocarp, smooth endocarp surface, distinct elliptical external depressions, distinct apical mucro, slightly curved seed shape and conspicuous globose hilum. A new species, R. yushensis Zhao, Collinson and Li, is described from these endocarp and seed features. Comparison with the two European Miocene species, R. palaeomaritima Negru and R. maritime-miocenica Szafer, indicates the existence at that time of three different geographical and stratigraphical species. R. yushensis constitutes the first Pliocene record of Ruppia and extends the range of fossils of this genus from Europe to eastern Asia. R. yushensis is the only aquatic plant in the uppermost middle part of the Zhangcun Formation. This monotypic occurrence indicates a brackish, clear, tranquil and shallow lake in this region in the Late Pliocene. The smooth endocarp surface further suggests a warm temperate or temperate palaeoclimate.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 145 , 317–329.     

A modular xylanase from mesophilic Cellulomonas fimi contains the same cellulose-binding and thermostabilizing domains as xylanases from thermophilic bacteria

Abstract The xynC gene from mesophilic Cellulomonas fimi encodes a large 125 kDa modular xylanase (XYLC), consisting of six distinct functional domains. In addition to a single Family 10 catalytic domain, XYLC contains a domain homologous with the nodulation protein, NodB, from nitrogen-fixing bacteria and therrnostabilizing and cellulose-binding domains found previously only in xylanases from thermophilic bacteria.     

Analysis of the linker region joining the adenylation and carrier protein domains of the modular nonribosomal peptide synthetases

Nonribosomal peptide synthetases (NRPSs) are multimodular proteins capable of producing important peptide natural products. Using an assembly line process, the amino acid substrate and peptide intermediates are passed between the active sites of different catalytic domains of the NRPS while bound covalently to a peptidyl carrier protein (PCP) domain. Examination of the linker sequences that join the NRPS adenylation and PCP domains identified several conserved proline residues that are not found in standalone adenylation domains. We examined the roles of these proline residues and neighboring conserved sequences through mutagenesis and biochemical analysis of the reaction catalyzed by the adenylation domain and the fully reconstituted NRPS pathway. In particular, we identified a conserved LPxP motif at the start of the adenylation‐PCP linker. The LPxP motif interacts with a region on the adenylation domain to stabilize a critical catalytic lysine residue belonging to the A10 motif that immediately precedes the linker. Further, this interaction with the C‐terminal subdomain of the adenylation domain may coordinate movement of the PCP with the conformational change of the adenylation domain. Through this work, we extend the conserved A10 motif of the adenylation domain and identify residues that enable proper adenylation domain function. Proteins 2014; 82:2691–2702. © 2014 Wiley Periodicals, Inc.     

Analyzing network topological characteristics of eco-industrial parks from the perspective of resilience: A case study

Realizing the stable operation of an eco-industrial park (EIP) as a complex system consisting of a variety of the enterprises and embedded relations is challenging. The topological structure plays an important role to understand the balance of network resilience and eco-efficiency in the operation process of a given EIP. In this paper, Ningdong Coal Chemical Eco-industrial Park (Ningdong CCEIP) is used as a case study in Ningxia Hui Autonomous Region of China. Based on complex network theory, we focus on topological characteristics analysis of symbiotic network from the perspective of resilience. Results reveal that Ningdong CCEIP has scale-free characteristics as well as the small world ones. Compared with the node-level metrics, the important degree of node considering ecological factor is a more crucial index measuring the importance of a particular node in the network. The removal of top 10% node contributes to 60% decrease of network efficiency, which indicates the decline of resilience in the studied case. Protecting the most important nodes is critical to safeguard the potential “vulnerability” in the development of EIPs. This study can help us better understand the strategies for avoiding disruptions, improving the resilience of EIP and safeguarding the stable operation.     

Correlations between observed dispersal capabilities and patterns of genetic differentiation in populations of four aquatic insect species from the Arizona White Mountains, U.S.A.

SUMMARY 1. Dispersal ability is an important ecological factor that can influence population structure. In an attempt to determine the extent that the pattern of genetic differentiation is correlated with dispersal ability in stream-dwelling aquatic insects, we used the amplified fragment length polymorphism (AFLP) technique to characterise genetic variation in four aquatic insect species: Gumaga griseola (Trichoptera: Sericostomatidae), Helicopsyche mexicana (Trichoptera: Helicopsychidae), Psephenus montanus (Coleoptera: Psephenidae) and Ambrysus thermarum (Hemiptera: Naucoridae). Individuals were sampled from several sites within two adjacent catchments in the Arizona White Mountains. In addition to the genetic analyses, a 20-week-long trapping study was used to determine the relative dispersal ability of adults of the four species examined.
2. We obtained hierarchical indicators of genetic differentiation for catchments, sites within catchments and sites across the region examined. Overall, average estimators of genetic differentiation ( F -statistics) were consistent with direct observations of organismal movement, although it was our direct observations on adult insect flight that permitted us to interpret our results correctly. This was because of the fact that a lack of genetic differentiation across watersheds can be interpreted in two ways.
3. In contrast to F -statistics, patterns of genetic isolation by distance for each species more clearly reflected dispersal ability, suggesting that such analytical approaches provide less ambiguous information about the importance of gene flow in the hierarchical partitioning of genetic variation in stream organisms.