Human impact on the ecological performance of Potamogeton species in northwestern Germany

The changes in habitat quality of lowland rivers in Lower Saxony (Germany) during the past 40 years are outlined. Almost all chemical, physical, and morphological parameters have changed, resulting in most cases in an enhanced potential productivity, accompanied by a complex disturbance regime. Historical reconstruction of the change in river vegetation is presented to compare the frequency of macrophyte species 40 years ago with the situation of today. For a total of 289 sampling sites, the floristic change was exactly reconstructed. Nearly all species show a decline in frequency. This trend is also recognizable in Potamogeton, with the exception of two narrow-leaved species.An attempt is made to explain both decline and maintenance in terms of life history characters (vital attributes) allowing the species to react to the changing habitat conditions. The successful species are characterized by certain life history characteristics which enable them to survive under the current disturbance regime. Most important aspects of life history are the ability to reproduce by means of turions and other fragments, a long-lived, deep-rooting rhizome system, phenotypic plasticity of above-ground parts, synchronous shoot polymorphism, and the potential to regenerate quickly from remaining buds after disturbance. The decline of formerly frequent species can be attributed mainly to the lack of certain key characters; however, physiological characters also may be important. The extirpation of some rare species could also be caused by random fluctuations in small populations. The general importance of population ecological research, particularly demography, life history theory, and the modelling of clonal populations in conservation ecology is stressed.     

Distribution,growth, production,and ecological significance of the clam Unio terminalis in Lake Kinneret,Israel

The distribution, body composition, growth rate, and population structure of Unio terminalis were measured at different sites of Lake Kinneret (Israel). Maximum clam density was found on the muddy sand between 0.3–6 m depth. Clams were most abundant in the River Jordan inlet zone, where they showed the highest growth rate. This was probably related to both highest food availability and the highest density of fish hosting Unio glochidia in this area. U. terminalis in Lake Kinneret has a more massive shell and ash content as compared with the European Unio species. The annual P/B ratios of U. terminalis populations at different sites were similar and ranged within 0.17–0.18. The computated filtration capacity and energetic budget permit the assumption that the U. terminalis population plays a substantial role in removal of organic particles from the water in the Kinneret shallow inshore zone (up to 15 m depth), and in nutrient recycling.     

Molecular analyses of ostracod flocks from Lake Baikal and Lake Tanganyika

Ancient lakes are excellent laboratories for evolutionary research, where species can be studied in the cradle where they originated. In this article, we investigate two endemic ostracod species flocks from the two oldest lakes in the world, Lake Baikal (LB) (ca. 28 myr) and Lake Tanganyika (LT) (ca. 12 myr), with DNA sequence data. Nuclear ITS1 failed to resolve the phylogeny of both flocks. Whilst most phylogenetic relationships of the Tanganyika flock are resolved with mitochondrial COI, the Baikalian tree contains multifurications of up to seven different clades. The Tanganyikan Cyprideis flock shows higher genetic variability, which matches its higher morphological variability. A significant deviation from a constant divergence rate through time indicates that the Cytherissa flock most likely experienced explosive speciation events during its earlier history. Comparative analyses of substitution rates furthermore revealed that they are not clock-wise for COI. Ancestral Cytherissa probably radiated in LB 5–8 myr ago, around the time when the cold, oxygenated abyss was formed in LB. The Tanganyikan Cyprideis flock is almost twice as old as the Baikalian Cytherissa flock, and possibly older than LT itself, ca. 15 myr. The Cyprideis flock has survived drastic lake level changes and resulting salinity crises during its entire history.     

青海湖地区芨芨草草地土壤种子库的初步研究

选择青海湖地区的次生芨芨草草地为研究对象,以围栏内封育和围栏外自由放牧的草地做对照,研究了围栏内外土壤种子库的萌发状况、密度和数量、物种多样性,以及土壤种子库与地上植被的关系。结果表明,围栏内外土壤种子库的萌发趋势非常相似,但是萌发种子累计数量不同;围栏内外土壤种子库中萌发种子的平均密度分别为3660和2460粒·m-2,围栏内萌发种子数比围栏外提高了48.8%;围栏内外土壤种子库的物种多样性指数差异较大,围栏内外丰富度指数R1分别为17和13,R2为3.693和2.832,丰富度围栏内大于围栏外,多样性指数和丰富度指数具有相同的规律,均匀度指数围栏内外分别为0.812和0.857,则是围栏外大于围栏内。围栏内外地上植被群落组成存在显著差异,围栏内的封育草地的物种丰富度和多样性指数均大于围栏外的放牧草地,而均匀度指数则呈相反趋势。     

中国斑腿蝗科特有种的分布及特有分布区划分

按照150km×150km对中国陆地部分进行栅格划分,收集整理了中国斑腿蝗科237个特有种在各栅格的分布信息,建立了物种(237)×栅格(168)数据矩阵,研究了中国斑腿蝗科特有种的分布规律并用PAE法进行特有分布区划分。结果表明:除天山山地分布的少数几个种外,中国斑腿蝗科特有种基本分布西南-东北走向。在该范围内南多北少。华南和西南是中国斑腿蝗科特有种最丰富的地区,在秦巴山区、藏东南和浙闽丘陵地带各有一个高密度的分布区。11个特有分布区中5个分布在东洋界部分,两个在中国东部古北和东洋界交界区,天山山地有一个分散的特有分布区,东北有2个特有分布区。特有分布区的分布和划分基本和中国动物地理区划及区系相一致,但台湾地区归入华中区;横断山和秦岭山地的栅格在支序图中多形成未决分类单元,特有分布区划分困难;华南和华中地区的特有分布区可以进一步划分成更小范围的特有分布区;从云南西北的腾冲、保山经过贵州南部到广西桂林的一个东西狭长的区域可以作为一个特有分布区     

植物源异戊二烯及其生态意义

异戊二烯为植物挥的众多有机碳氢化合物中的主要成分,它的合成和释放对全球尺度上的C素平衡、温室效应的大气污染都有极其重要的作用。本文系统论述了影响异戊二烯释放的主要因子,异戊二烯的释放量及其计量方法,以及它可能的生态意义,指出了研究多重环境胁迫与异戊二烯合成和释放的关系的必要性。     

The chrysophycean paleocyst flora of the bottom sediments of Kortowskie Lake (Poland) and its ecological significance

The postglacial sediments of Kortowskie Lake contain well preserved chrysophycean cysts. Forty-six morphotypes were identified by scanning electron microscopy (SEM) and light microscopy (LM). Ten new morphotypes of fossil chrysophycean cysts are described. Some of the most abundant taxa show clear trends associated with the increase in lake trophic status. The cyst flora is divided into four groups: eutrophic forms (Cysta globata, C. cortoviensis, C. vermicularis); oligotrophic forms (Cysta curvicollis); cool-water forms (Cysta carinifera, C. crassicollis, C. microspinosa, C. modica and Cysta stellata), and indifferent forms (all other morphotypes which did not show a clear tendency). The percentage abundance of chrysophycean cysts wa related to climate changes, showing a considerable increase during the Subboreal period. Two factors, lake fertility and water level changes affected the abundance of the fossil cyst flora in the sediments of Kortowskie Lake.     

Source-sink landscape theory and its ecological significance

Exploring the relatiouships between landscape pattern and ecological processes is the key topic of landscape ecology,for which,a large number of indices as well as landscape pattern analysis model were developed.However,one problem faced by landscape ecologists is that it is hard to link the landscape indices with a specific ecological process.Linking landscape pattern and ecological processes has become a challenge for landscape ecologists."Source" and "sink" are common concepts used in air pollution research,by which the movement direction and pattern of different pollutants in air can be clearly identified.In fact,for any ecological process,the research can be considered as a balance between the source and the sink in space.Thus,the concepts of "source" and "sink" could be implemented to the research of landscape pattern and ecological processes.In this paper,a theory of sourcesink landscape was proposed,which include:(1) In the research of landscape pattern and ecological process,all landscape types can be divided into two groups,"source"landscape and "sink" landscape."Source" landscape contributes positively to the ecological process,while "sink" landscape is unhelpful to the ecological process.(2) Both landscapes are recognized with regard to the specific ecological process."Source" landscape in a target ecological process may change into a "sink"landscape as in another ecological process.Therefore,the ecological process should be determined before "source"or "sink" landscape were defined.(3) The key point to distinguish "source" landscape from "sink" landscape is to quantify the effect of landscape on ecological process.The positive effect is made by "source" landscape,and the negative effect by "sink" landscape.(4) For the same ecological process,the contribution of "source" landscapes may vary,and it is the same to the "sink"landscapes.It is required to determine the weight of each landscape type on ecological processes.(5) The sourcesink principle can be applied to non-point source pollution control,biologic diversity protection,urban heat island effect mitigation,etc.However,the landscape evaluation models need to be calibrated respectively,because different ecological processes correspond with different source-sink landscapes and evaluation models for the different study areas.This theory is helpful to further study landscape pattern and ecological process,and offers a basis for new landscape index design.     

Source-sink landscape theory and its ecological significance

Exploring the relationships between landscape pattern and ecological processes is the key topic of landscape ecology, for which, a large number of indices as well as landscape pattern analysis model were developed. However, one problem faced by landscape ecologists is that it is hard to link the landscape indices with a specific ecological process. Linking landscape pattern and ecological processes has become a challenge for landscape ecologists. “Source” and “sink” are common concepts used in air pollution research, by which the movement direction and pattern of different pollutants in air can be clearly identified. In fact, for any ecological process, the research can be considered as a balance between the source and the sink in space. Thus, the concepts of “source” and “sink” could be implemented to the research of landscape pattern and ecological processes. In this paper, a theory of sourcesink landscape was proposed, which include: (1) In the research of landscape pattern and ecological process, all landscape types can be divided into two groups, “source” landscape and “sink” landscape. “Source” landscape contributes positively to the ecological process, while “sink” landscape is unhelpful to the ecological process. (2) Both landscapes are recognized with regard to the specific ecological process. “Source” landscape in a target ecological process may change into a “sink” landscape as in another ecological process. Therefore, the ecological process should be determined before “source” or “sink” landscape were defined. (3) The key point to distinguish “source” landscape from “sink” landscape is to quantify the effect of landscape on ecological process. The positive effect is made by “source” landscape, and the negative effect by “sink” landscape. (4) For the same ecological process, the contribution of “source” landscapes may vary, and it is the same to the “sink” landscapes. It is required to determine the weight of each landscape type on ecological processes. (5) The sourcesink principle can be applied to non-point source pollution control, biologic diversity protection, urban heat island effect mitigation, etc. However, the landscape evaluation models need to be calibrated respectively, because different ecological processes correspond with different source-sink landscapes and evaluation models for the different study areas. This theory is helpful to further study landscape pattern and ecological process, and offers a basis for new landscape index design. __________ Translated from Acta Ecologica Sinica, 2006, 26(5): 1444–1449 [译自: 生态学报]     

Distribution of imino acids in Ptelea and their probable ecological significance

Seed and leaf extracts of 124 populations of all three species of Ptelea were analysed by paper chromatography and high voltage electrophoresis for their imino acids. Proline and pipecolic acid were found to have a wide distribution in the genus with high concentrations of both imino acids restricted to the xeric forms. The ecological significance is discussed.     

Diversity and significance of Burkholderia species occupying diverse ecological niches

Members of the genus Burkholderia are versatile organisms that occupy a surprisingly wide range of ecological niches. These bacteria are exploited for biocontrol, bioremediation and plant growth promotion purposes, but safety issues regarding human infections, especially in cystic fibrosis patients, have not been solved. This minireview gives an overview of the taxonomic and ecological diversity of the genus with particular emphasis on strains belonging to the Burkholderia cepacia complex and addresses the important question whether 'good' and 'bad' strains are actually the same.     

植物功能型及其生态学意义

植物功能型是近年来在全球变化研究中引入的一个新的生态学术语,综 植物功能型概念的由来、划分植物及其生态学意义,用系统生物学的理论与方法理解植物功能型,并指出了植物功能型在全球变化研究中的意义。     

A mass balance evaluation of the ecological significance of historical nitrogen fluxes in Lake Kinneret

Lake Kinneret (LK) is a monomictic lake that has undergone significant biological and chemical changes over the last three decades of the twentieth century. The transition between the 1970s and the 1980s attracted a lot of scientific attention as it was marked by significant changes in the ecology of the lake. In the early 1980s, phytoplankton biomass increased, apparently in response to an increase in the external soluble reactive phosphorus (SRP) load. This period was marked by a rise in hypolimnetic levels of ammonium (NH₄) and SRP as well as surface water dissolved oxygen (DO) and pH. Cconcomitantly, in surface waters in winter levels of NH₄ increased and NO₃ decreased. In this study interrelationships amongst these observations were examined with a mass balance modelling approach, including simulation of individual nutrient sources and sinks, focusing on nitrogen fluxes in winter. The step-like rise in phytoplankton biomass in 1981 may have been triggered by the increase in winter external loads of SRP, as P is likely to be the growth-limiting nutrient during this season. The additional P load led to a sequence of changes including greater summer phytoplankton biomass, followed by enhanced sedimentation of organic matter. Furthermore, higher organic matter mineralization fluxes within the hypolimnion resulted in elevated levels of NH₄ and SRP in this layer through the 1980s, with a feedback to productivity in the trophogenic zone following seasonal destratification in early winter. In an apparent transition period (late 1970s to early 1980s), an increase in the modelled rate of nitrate (NO₃) production occurred via nitrification together with increased uptake of the additional nitrate by phytoplankton. These results are consistent with increased phytoplankton abundance and elevated levels of surface water NH₄ and DO during this period. Through this period the increase in phytoplankton uptake of NO₃ predominated over the increase in nitrification, and NO₃ concentrations in the 1980s were reduced compared with the previous decade, with increased partitioning of N in biomass and NH₄.     

Diet and some ecological features of the most widespread commercial crab species in the northwestern Sea of Japan in early spring

Results of the study of feeding habits of the commercial crab species Chionoecetes opilio, Ch. japonicus, Paralithodes platypus, P. camtschaticus, and Erimacrus isenbeckii in early spring 2009 are presented. The composition, distribution, and quantitative characteristics of benthos in the areas of sampling are analyzed. The generalized pattern of distribution of the considered crabs is shown with the maximum and mean densities. These crabs were found to consume at least three to four single portions of food during 10–12 hours of daylight. The lowest feeding intensity was observed in the opilio snow crab in March and April. Cannibalism proved to be typical for all the studied crab species in the spring. It was most developed in the deepwater red snow crab, in whose diet representatives of the same species constituted a one-third share. It was also noted that the diet of the studied crabs included a major proportion of crabs and shrimps, which was unusual for the feeding habits of the same species in other Far Eastern seas.     

Dominance of putative marine benthic Archaea in Qinghai Lake, north-western China

Recent studies have revealed important and versatile roles that Archaea play in a wide variety of environmental processes on Earth. In this study, we investigated the abundance and diversity of archaeal communities in lake water and a 5 m sediment core collected from Qinghai Lake on the Tibetan Plateau, north-western China. An integrated approach was employed including geochemistry, quantitative polymerase chain reaction (Q-PCR) and 16S rRNA gene analysis. Here, we show that Archaea dominated the prokaryotic community in the lake sediments. Members of putative marine benthic groups [Marine Benthic Group (MBG)-B, -C and -D] and Miscellaneous Crenarchaeotic Group (MCG) were dominant, many of which were previously reported to be predominantly present in deep-sea environments. These results demonstrate that these groups are not limited to marine sediments. Despite their ubiquitous presence in aquatic environments, metabolic functions of these important groups largely remain unknown. Whereas many of these groups (such as MBG-B and -D) have typically been found in methane-hydrate deposits in marine environments, our carbon isotopic and molecular results from Qinghai Lake sediments indicate a lacustrine origin.     

Environment-dependent inbreeding depression: its ecological and evolutionary significance

Inbreeding depression is a major evolutionary and ecological force that influences population dynamics and the evolution of inbreeding-avoidance traits such as mating systems and dispersal. There is now compelling evidence that inbreeding depression is environment-dependent. Here, we discuss ecological and evolutionary consequences of environment-dependent inbreeding depression. The environmental dependence of inbreeding depression may be caused by environment-dependent phenotypic expression, environment-dependent dominance, and environment-dependent natural selection. The existence of environment-dependent inbreeding depression challenges classical models of inbreeding as caused by unconditionally deleterious alleles, and suggests that balancing selection may shape inbreeding depression in natural populations; loci associated with inbreeding depression in some environments may even contribute to adaptation to others. Environment-dependent inbreeding depression also has important, often neglected, ecological and evolutionary consequences: it can influence the demography of marginal or colonizing populations and alter adaptive optima of mating systems, dispersal, and their associated traits. Incorporating the environmental dependence of inbreeding depression into theoretical models and empirical studies is necessary for understanding the genetic and ecological basis of inbreeding depression and its consequences in natural populations.