异质生境中水生植物表型可塑性的研究进展

水生植物是一类以草本植物为主、与水紧密相关的生态类群, 大多数具有克隆性。面对水环境的变化, 水生植物在形态、行为和生理上表现出多样化的表型可塑性, 对异质生境具有很强的适应能力。表型可塑性研究已在陆生植物的多个类群展开, 然而目前对异质生境下水生植物的生态适应对策, 尤其是表型可塑性的研究尚重视不够。本文在阐明克隆植物表型可塑性主要实现方式及其关系、水生环境异质性及其特点的基础上, 重点从形态可塑性、觅食行为、克隆整合、克隆分工和风险分摊等5个方面讨论了水生植物如何通过表型可塑性适应异质性水生环境。在今后的水生植物表型可塑性研究中, 建议着重探讨以下问题: (1)表型可塑性的变化规律及机理; (2)克隆整合对群落和生态系统的影响; (3)克隆整合与克隆片段化的权衡; (4)不同克隆构型的表型可塑性及其内在机制; (5)表型可塑性的适应性进化; (6)水生植物与其他类群/营养级物种的关系; (7)水生生态系统对全球变化的响应。     

水环境中腐殖质-金属离子键合作用研究进展

腐殖质 (主要指腐殖酸和富里酸 )普遍存在于各种水体中 ,它对金属离子的形态、迁移转化、生物可利用性等地球化学行为起着重要作用。本文概述了水环境中腐殖质的一些基本性质 ,以及腐殖质 金属离子之间的键合作用机理、研究方法和影响因素。并且对各种金属离子键合到腐殖质上的现代物理化学模型 ,尤其对ModelⅥ及NICA Donnan模型进行了简要回顾和评述。它们在许多条件下模拟腐殖质 -金属离子键合作用可以得到令人欣喜的结果。还简述了腐殖质对水环境中金属离子各种水环境地球化学行为的影响。但是 ,若要更深入了解和阐述金属离子在水环境中的各种行为 ,还需考虑腐殖质与颗粒物质、胶体物质以及微生物等的相互作用。     

A review on factors affecting microcystins production by algae in aquatic environments

Microcystins, a toxin produced by Microcystis aeruginosa have become a global environmental issue in recent years. As a consequence of eutrophication, microcystins have become widely disseminated in drinking water sources, seriously impairing drinking water quality. This review focuses on the relationship between microcystins synthesis and physical, chemical, and biological environmental factors that are significant in controlling their production. Light intensity and temperature are the more important physical factors, and in many cases, an optimum level for these two factors has been observed. Nitrogen and phosphorus are the key chemical factors causing frequent occurrence of harmful algal blooms and microcystins production. The absorption of nutrients and metabolic activities of algae are affected by different concentrations and forms of nitrogen and phosphorus, leading to variations in microcystins production Metal ions and emerging pollutants are other significant chemical factors, whose comprehensive impact is still being studied. Algae can also interact with biological agents like predators and competitors in aquatic environments, and such interactions are suggested to promote MCs production and release. This review further highlights areas that require further research in order to gain a better understanding of microcystins production. It provides a theoretical basis for the control of microcystins production and releasing into aquatic environments.     

Ecological restoration of aquatic and semi-aquatic ecosystems in the Netherlands: an introduction*

Hydrobiologia - In 1989, a symposium was held under the title `Netherlands-Wetlands', aiming at the presentation of the state of the art of the existing knowledge of structure and functioning...     

Ethylene and carbon dioxide: Regulation of growth in two perennial aquatic plants, arrowhead and pondweed

The growth of two perennial aquatic plants, arrowhead {Sagittariapygmaea) and pondweed (Potamogeton distinctus) is greatly promotedby C₂H₄ and CO₂ in the dark; C₂H₄ and CO₂ are synergistic inthis response. C₂H₄ is produced by these two species. (Received September 10, 1974; )     

Invasion success of non-indigenous aquatic and semi-aquatic plants in their native and introduced ranges. A comparison between their invasiveness in North America and in France

Aquatic and semi-aquatic plants comprise few species worldwide, yet the introduction of non-indigenous plants represents one of the most severe examples of biological invasions. My goal is to compare the distribution and the biology of aquatic and semi-aquatic plants in their introduced ranges and in their native ranges. The primary objective of this study is to test the hypothesis that invasive species have evolved traits likely to increase their success in the new range. I made two reciprocal comparisons, i.e. I compared European species in France and in North America, and North American species in France and in North America. Twenty-seven species were classified according to their invasiveness in their introduced area. I␣found six invasive macrophyte species in France native to North America and 17 invasive species in North America native to Europe. Four species are invasive in both areas. There is no general tendency for macrophytes to be more vigorous in their introduced ranges. Most non-indigenous aquatic and semi-aquatic species are potentially invasive or widespread and well-established in their introduced country, while few species seem to be restricted in their distribution.     

Organotin compounds and aquatic bacteria: A review

Organotins are toxic to microorganisms. Trisubstituted organotins (R₃SnX) are considered more toxic than disubstituted (R₂SnX₂) or monosubstituted (RSnX₃) compounds, and tetrasubstituted compounds (R₄Sn) are not considered toxic. In the R₃Sn series propyl-, butyl-, pentyl-, phenyl- and cyclohexyltins are the most toxic to microorganisms. Toxicity towards aerobes in the R₃Sn series is related to total molecular surface area and to the octanol: water partition coefficient,Kow, which is a measure of hydrophobicity. Care must be taken when testing the toxicity of tin compounds in the laboratory, for a number of biological, chemical and physical factors can influence the apparent toxicity. Although TBT is generally the most toxic of the butyltins, there are instances where monobutyltin (MBT) is as toxic, or more toxic, than TBT to microorganisms. Thus, debutylation in the sequence TBT→DBT→MBT→Sn does not detoxity TBT for all microorganisms. Some microorganisms can methylate inorganic or organic tins under aerobic or anaerobic conditions. Methylation can also occur by chemical means and the relative contributions of biotic and abiotic mechanisms are not clear. It is difficult to isolate a pure culture which can methylate tin compounds aerobically, and it is difficult to isolate a pure culture which degrades TBT, suggesting that microbial consortiums may be involved in transformations of organotins in the aquatic environment. Methylation and debutylation alter the adsorbtivity and solubility of tin compounds; thus microorganisms can influence the environmental mobility of tin. TBT-resistant microorganisms can be isolated, and in some of them resistance to TBT can be plasmid-mediated. The literature review for this paper was completed in July, 1992.     

湖泊的水生态模型

由于城市化进程的不断加快,大量的污染物排放到湖泊中,打破了湖泊的生态平衡.湖泊的水生态模型不仅能够研究湖泊的富营养化现象,而且还可以模拟工业毒物等污染物对湖泊生态系统的影响,是湖泊管理的有力工具.本文从分析湖泊的污染现状以及污染趋势出发,介绍了湖泊水生态模型的研究现状,并根据模型的模拟对象和空间模拟能力对湖泊水生态模型进行了分类.在此基础上介绍了AQUATOX、PAMOLARE、CAEDYM、WASP、OOMAS等比较成熟的模拟湖泊生态系统的模型软件,阐述了它们的产生、发展、主要特点以及应用,总结了当今湖泊水生态模型在模拟过程中遇到的问题,并对水生态模型的发展趋势进行了展望.本文为湖泊水生态模型的选择提供了建议.     

水生维管植物研究:II、水生维管植物对干涸的适应

根据实地考察和文献分析 ,研究了水生维管植物对干涸的不同的适应对策 ,归纳为 3类 :(1 )直接适应型 (或称生理适应型 ) ;(2 )间接适应型 ;(3 )休眠适应型。这有助于认识水生植物的适应特征 ,揭示干涸对部分水生植被演替的作用。     

Revised and annotated checklist of aquatic and semi-aquatic Heteroptera of Hungary with comments on biodiversity patterns

A basic knowledge of regional faunas is necessary to follow the changes in macroinvertebrate communities caused by environmental influences and climatic trends in the future. We collected all the available data on water bugs in Hungary using an inventory method, a UTM grid based database was built, and Jackknife richness estimates and species accumulation curves were calculated. Fauna compositions were compared among Central-European states. As a result, an updated and annotated checklist for Hungary is provided, containing 58 species in 21 genera and 12 families. A total 66.8% of the total UTM 10 × 10 km squares in Hungary possess faunistic data for water bugs. The species number in grid cells numbered from 0 to 42, and their diversity patterns showed heterogeneity. The estimated species number of 58 is equal to the actual number of species known from the country. The asymptotic shape of the accumulative species curve predicts that additional sampling efforts will not increase the number of species currently known from Hungary. These results suggest that the number of species in the country was estimated correctly and that the species accumulation curve levels off at an asymptotic value. Thus a considerable increase in species richness is not expected in the future. Even with the species composition changing the chance of species turn-over does exist. Overall, 36.7% of the European water bug species were found in Hungary. The differences in faunal composition between Hungary and its surrounding countries were caused by the rare or unique species, whereas 33 species are common in the faunas of the eight countries. Species richness does show a correlation with latitude, and similar species compositions were observed in the countries along the same latitude. The species list and the UTM-based database are now up-to-date for Hungary, and it will provide a basis for future studies of distributional and biodiversity patterns, biogeography, relative abundance and frequency of occurrences important in community ecology, or the determination of conservation status.     

A comparison of purification efficiencies of various constructed ecosystems (aquatic,semi-aquatic and terrestrial) receiving urban wastewaters

Tests were carried out under controlled conditions in the Experimental Plant of Viville (Arlon, Belgium) to enhance the purification of urban wastewater by natural means. The results demonstrate the need to structure treatment systems in a series of different artificial ecosystems (or a Hierarchical Mosaic of Artificial Ecosystems — MHEA in French). The first two levels we used were made up of an unplanted aquatic ecosystem (stabilization pond) followed by a semi-aquatic ecosystem planted withTypha latifolia L. in which the water flows over the substrate. At a flow rate of 4 m²/PE (1 PE=150 1/day of typical urban wastewaters in Belgian rural zones), this first stage substantially reduces suspended solids (SS), COD and BOD₅, a significant amount of tot-N and tot-P, and reduces pathogens by 100-fold. Further, the system is easy to manage (sludge is eliminated in the first stage and biomass is collected in the second stage) and the treatment system does not clog up.Nevertheless, real and sustainable environmental protection demands even higher performance rates, and these first two stages, both in terms of design and dimension, can only be considered as a satisfactory part of a MHEA system. Artificial aquatic, semi-aquatic, and terrestrial ecosystems were systematically compared at the third and fourth stage of the system to increase the overall removal efficiency.The most complete and efficient system in our tests (i.e., the one that provides the most successful primary (SS), secondary (COD and BOD₅) and tertiary (N and P) treatment and the best pathogens removal rates) was made up of 3 sequential series of ecosystems: an aquatic ecosystem whose flow went into a plantedTypha latifolia system (surface water flow), that flowed into a terrestrial ecosystem planted withAlnus glutinosa (L.) Gaertn (vertical subsurface water flow). A total surface area (stages 1–4) of 8 m²/PE ensured a high performance level whose outflow conformed to the strictest European norms.     

Aluminium in aquatic environments: abundance and ecotoxicological impacts

Aquatic Ecology - Aluminium (Al) is a common chemical element released into the aquatic environment from the Earth’s crust and many anthropogenic activities. It may be present in various...     

A C-assay for photorespiration in aquatic plants

The ¹⁴C-assay developed by Zelitch to evaluate photorespiration was modified for use in submersed aquatic plants in the laboratory and in situ. Results in laboratory cultures of Najas flexilis suggest that photorespiration occurs but is limited in comparison to terrestrial C₃ plants and is related to the rate of diffusion of CO₂ from the plant and to the carrying capacity of water for dissolved oxygen.     

Population genetic structure in six sympatric and widespread aquatic plants inhabiting diverse lake environments in China

Many aquatic plant species are distributed over large areas and diverse environments with populations interconnected by abiotic and biotic mediators. Here, we examined differences and similarities in the population genetic structure of six sympatric and widespread aquatic plant species. We sampled the aquatic species from six Chinese lakes found on plateaus, plains, and different river systems and analyzed them using inter‐simple sequence repeat (ISSR) markers. Samples originating from each lake tended to cluster together. Of the six species, only Nymphoides peltata and Myriophyllum spicatum could be divided into plateau and plain groups, once Taihu Lake individuals were excluded. Genetic similarities between populations connected by the Yangtze River were not consistently higher than unconnected populations. Populations from Taihu Lake and/or Weishanhu Lake were distant from other lake populations for all species except Potamogeton lucens. The Taihu and Weishanhu populations clustered for Ceratophyllum demersum and Typha latifolia. Hydrophilous C. demersum had the lowest gene flow (Nm = 0.913), whereas the entomophilous Hydrocharis dubia (Nm = 2.084) and N. peltata (Nm = 2.204) had the highest gene flow. The genetic relationships among distant populations of aquatic plants reflect the comprehensive effects of environmental selection pressure and biotic and abiotic connectivity. Differences in environmental factors between plateau and plain lakes and long distance hydrochory have limited importance on aquatic plant genetic structures. Among multiple evolutionary forces, gene flow mediated by birds may play the most important role in the formation of genetic patterns in the six species examined. For example, the close genetic relationship between Taihu Lake and Weishanhu Lake populations, each in different river systems and with different climates, may be related to the migration routes of birds. Differences in gene flow among the six aquatic plants may be attributable to different bird‐transport and the fruit traits of each species.     

The state of the art of aquatic and semi-aquatic ecological restoration projects in the Netherlands*

The Netherlands are a small, low-lying delta in W. Europe (42000 km²; 50°–54° N; 3°–8° E), mainly consisting of alluvial deposits from the North Sea and from the large rivers Rhine and Meuse. The country was `created by man'. The conversion of natural aquatic and terrestrial ecosystems into drained agricultural land was a major cultural operation over the past 1000 years. Roughly 55% of the country's surface area is still agricultural land. Some decades ago, The Netherlands' landscape was characterised by an armoured coastline and bridled estuaries, a drastically reduced area of saline and freshwater marshes, fully regulated rivers and streams, and numerous artificial lakes. The aquatic ecosystems beyond the influence of the large rivers, the Pleistocene raised bogs and moor lands, have almost been completely annihilated in the past. Acidification and eutrophication led to the deterioration of the remaining softwater lake vegetation. Last but not least, an artificial drainage system was constructed, leading to an unnatural water table all over the country, high in summer, low in winter. Only very recently, some 25 years ago, the tide has been turned and ecological rehabilitation and restoration of disturbed ecosystems are in full swing now, enhanced by the European Union policy to set aside agricultural land in the Netherlands in favour of the development of `nature'. The state of the art of aquatic and semi-aquatic ecological restoration projects in the Netherlands is given. Starting from the conceptual basis of restoration ecology, the successes and failures of hundreds of restoration projects are given. Numerous successful projects are mentioned. In general, ecological restoration endeavours are greatly benefiting from progressive experience in the course of the years. Failures mainly occur by insufficient application of physical, chemical or ecological principles. The spontaneous colonisation by plants and animals, following habitat reconstruction, is preferred. But sometimes the re-introduction of keystone species (e.g. eelgrass; salmon; beaver) is necessary in case the potential habitats are isolated or fragmented, or when a seed bank is lacking, thus not allowing viable populations to develop. Re-introduction of traditional management techniques (e.g. mowing without fertilisation; low intensity grazing) is important to rehabilitate the semi-natural and cultural landscapes, so characteristic for the Netherlands. For aquatic ecosystems proper (estuaries, rivers, streams, larger lakes) the rule of thumb is that re-establishment of the abiotic habitat conditions is a pre-requisite for the return of the target species. This implies rehabilitation of former hydrological end geomorphological conditions, and an increase in spatial heterogeneity. The `bottom-up' technique of lake restoration, viz. reduction in nutrient loadings, and removal of nutrient-rich organic sediment, is the preferred strategy. The `top-down' approach of curing eutrophicated ecosystems, that is drastic reduction of fish stock, mainly bream, and introduction of carnivorous fish, may be considered as complementary. For semi-aquatic ecosystems (river-fed and rain-fed peat moors, brook valleys, coastal dune slacks) it also counts that the abiotic constraints should be lifted, but here the species-oriented conservation strategy, the enhancement of the recovery of characteristic plant and animal species, is mainly followed. An important pre-requisite for the rehabilitation of the original natural or semi-natural     

Emergent aquatic plants: Biological and economic perspectives

One of the most productive, but least exploited, biomass resources is the group classified as the emergent aquatic plants. The objective of this paper is to present information concerning the biological and economic factors that must be considered if emergent aquatic plants are to become viable feedstocks for multipurpose systems. Feedstock purposes highlighted include fuel and/or chemical production.Species identified as potential candidates for production in biomass systems include Arundo donax, Cyperus papyrus, Phragmites communis, Saccharum spontaneum, Spartina alterniflora, and Typha latifolia. If these species are to be viable candidates in biomass systems, a number of research areas must be further investigated. Issues such as development of baseline yield data for managed systems, mechanisation and harvesting conceptualisation, genetic (crop) improvement, identification of secondary plant products, and economic considerations require refinement. However, the potential pay-off for developing emergent aquatic systems will be significant if successful.     

The effect of land usage on aquatic and semi-aquatic vegetation at high altitudes in Southern Africa

Summary The high altitude regions of Southern Africa (2300 m/7500 feet and above) are vitally important source areas for many large rivers. Land usage, until recently mainly of an intermittent pastoral type, is now, with increasing density of permanent human and animal populations, exerting a heavy pressure on vegetation, especially the aquatic and semi-aquatic plants, while concurrently another factor, diamond mining, is also affecting it. There are both economic and agricultural problems.

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Zussammenfassung Die höheren Zonen des südlicheren Afrikas (2300 m/7500 Fuss und mehr) sind lebenswichtige Ursprunggebiete mancher grossen Flüsse. Bis neulich wurde das Land hauptsächlich absatzweise als Weiden benutzt; jetzt aber mit zunehmender Dichte menschlicher und tierlicher Bevölkerung und mit der Entwicklung der Diamantausgrabungen wird ein steter Druck auf die Vegetation, besonders auf die Wasser- und Halbwasserpflanzen, ausgeübt. Das Problem des Quellenschutzes ist wirtschaftlich sowohl wie landwirtschaftlich.

     

Phylodynamics and movement of Phycodnaviruses among aquatic environments

Phycodnaviruses have a significant role in modulating the dynamics of phytoplankton, thereby influencing community structure and succession, nutrient cycles and potentially atmospheric composition because phytoplankton fix about half the carbon dioxide (CO₂) on the planet, and some algae release dimethylsulphoniopropionate when lysed by viruses. Despite their ecological importance and widespread distribution, relatively little is known about the evolutionary history, phylogenetic relationships and phylodynamics of the Phycodnaviruses from freshwater environments. Herein we provide novel data on Phycodnaviruses from the largest river system on earth—the Amazon Basin—that were compared with samples from different aquatic systems from several places around the world. Based on phylogenetic inference using DNA polymerase (pol) sequences we show the presence of distinct populations of Phycodnaviridae. Preliminary coarse-grained phylodynamics and phylogeographic inferences revealed a complex dynamics characterized by long-term fluctuations in viral population sizes, with a remarkable worldwide reduction of the effective population around 400 thousand years before the present (KYBP), followed by a recovery near to the present time. Moreover, we present evidence for significant viral gene flow between freshwater environments, but crucially almost none between freshwater and marine environments.