牛山湖两种优势小型鱼类空间分布与沉水植被的关系

运用8种网目规格的成套浮性刺网作为鱼类采样工具,于2005年夏季在长江中游浅水草型湖泊牛山湖进行鱼类定量采样,通过比较不同茂密程度黄丝草生境中的小型鱼类组成、数量和大小结构,探讨此类湖泊小型鱼类的空间分布特征及其与沉水植被的关系.采样期间共捕获13种1124尾鱼,依据其等级丰度和出现频次,鳖和红鳍原鲌为该湖优势上层小型鱼类.在调查的沉水植物生物量范围内,鱼类物种丰富度和Shannon多样性指数与沉水植物生物量之间呈现倒抛物线关系;两种优势小型鱼类的种群丰度均与沉水植物生物量有着显著的线性正相关关系,且其平均个体大小在裸地生境较高、沉水植被茂密区较低,幼鱼更倾向群聚于厚密的黄丝草生境中;其他生境因子(水深和离岸距离)对鳖和红鳍原鲐空间分布的影响不显著.黄丝草植被生境是牛山湖两种优势小型鱼类的重要保护生境,应加强对黄丝草等沉水植被的保护及恢复.     

The distribution of submerged aquatic macrophyte biomass in a eutrophic stream,Badfish Creek: the effect of environment

The distribution of biomass of the macrophyte community in Badfish Creek was examined in three sections (A–C) totaling ten kilometers. Biomass samples were taken in a stratified-random manner, with sediment characteristics, depth, current velocity and incident light measured at each site to correlate individual biomass samples with environmental factors. Total community biomass decreased in the downstream section (C), with the biomass ofElodea canadensis decreasing abruptly below section A. The only environmental factors which were correlated with the decrease in macrophyte community biomass, especially that ofPotamogeton pectinatus, in section C was the increase in substrate heterogeneity and sand substrates which lacked surface gravel. The change in substrate was related to channelization. Considering the stream as a whole, the biomass of the dominant species,Potamogeton pectinatus, was correlated with incident light. Other species present wereCeratophyllum demersum andCladophora glomerata. Analysis of riparian vegetation type indicates that tree cover significantly reduced macrophyte biomass by incident light reduction.     

Relationship between distribution and bottom sediment of submerged macrophytes in the Seta River,Shiga Prefecture,Japan

The purpose of this study was to survey the distribution and habitat of submerged macrophytes in the Seta River outflow from Lake Biwa, Shiga Prefecture, Japan. To accomplish this, I instituted a field survey with sampling on January 2009. I collected nine submerged macrophyte species during the diving operation. Sample collection showed that submerged macrophytes flourished on both sides of the river but did not flourish in the central portion of the river. Alien species (Egeria densa and Elodea nuttallii) were collected on all survey lines, while domestic species (Ceratophyllum demersum, Myriophyllum spicatum, Hydrilla verticillata, Vallisneria biwaensis, Vallisneria denseserrulata, Potamogeton maackianus, and Potamogeton malaianus) were collected in large amounts on the survey lines near Lake Biwa. The dominant species in cohesive soil or fine soil was Egeria densa, while the dominant species in sand gravel was Potamogeton maackianus. Although Egeria densa was collected in sand gravel too, Potamogeton maackianus was not collected in cohesive soil or fine soil, which indicates that Egeria densa has high fertility and can survive in an oxygen-poor environment, while Potamogeton maackianus cannot survive in an oxygen-poor environment.     

东太湖水生植物群落结构的演变及其沼泽化

2002年东太湖水生植被调查结果表明,沉水植被和浮叶植被是该湖水生植被的主要生态类型,分布面积分别占全湖总面积73.6%和18.3%。东太湖水生植被主要有9个群丛,其中沉水植被主要的5个群丛是伊乐藻(外来种)群丛、金鱼藻群丛、伊乐藻 微齿眼子菜群丛、菜-伊乐藻 微齿眼子菜群丛、苦草 竹叶眼子菜 黑藻群丛,其分布面积分别占东太湖植被总面积的30.7%、17.2%、16.7%、15.8%、9.3%。随着对东太湖的不断改造和资源的不断利用,20世纪60年代东太湖人工种植沼泽植被菰群丛,20世纪80年代初环湖水陆交错带被围垦而芦苇群丛消失,微齿眼子菜替代竹叶眼子菜而占据东太湖40%的水面。近10a来,东太湖网围养蟹迅速发展,占全湖总植被面积25.6%的沼泽植物——菰群丛及其占40%的微齿眼子菜群丛被清除,外来种伊乐藻和无根植物金鱼藻分布面积达90%的湖区。东太湖水生植被由20世纪50年代的原生演替到现在的次生演替,群落演变激烈,同时东太湖沼泽化进程加剧。     

The composition and density of epiphyton on several species of submerged macrophytes — the neutral substrate hypothesis tested

Epiphyton samples same taken from different macrophyte species (three chararaceans Potamogeton pectinatus L.). While some epiphyton taxa were evenly distributed, the density of others differed according to plant part, site or macrophyte species. Diatoms were classified according to host plant species by cluster analysis. Thus, the neutral substrate hypothesis is revised.Differences in epiphyton composition were larger between the closely related species Chara tomentosa L. and C. globularis Thuill. than between Chara tomentosa and Nitellopsis obtusa (Desv.) J. Groves. The latter two species were heavily marl-encrusted. Potamogeton pectinatus was separated from the other macrophyte species by its lower total density of epiphyton and the high abundance of Cocconeis placentula Ehr.     

洪泽湖大型水生植物群落结构和时空格局的GIS模拟

2010—2011年对洪泽湖大型水生植物进行了4个季度全面的调查和研究, 共发现大型水生植物8科12种, 其中沉水植物9种, 挺水植物1种, 浮叶植物2种。马来眼子菜(Potamogeton malaianus)、微齿眼子菜(P. maackianu)、篦齿眼子菜(P. pectinatus)和菹草(P. crispus)为全年优势度较高的水生植物, 但4个季节大型水生植物的优势种类组成差异明显。秋季的水草生物量最高, 其次为夏季和冬季, 春季最低。结合GPS (Global Position System)和GIS (Geographic Information System), 利用GIS的Kring插值法对洪泽湖大型水生植物总生物量及主要优势物种的时空分布进行了可视化模拟。结果发现洪泽湖现阶段大型水生植物分布区域主要集中在湖区北部水质较好、透明度较高且相对封闭的成子湖区。文章也分析了洪泽湖大型水生植物变迁的潜在影响因子, 为水生植物保护和生态系统健康提供了基础依据。     

The impact of the crayfish Orconectes virilis on aquatic macrophytes

SUMMARY. 1. The impact of crayfish on the biomass, density and shoot morphology of four submersed plant species was examined under semi-natural conditions. Male or female crayfish ( Orconectes virilis ) were held for 5 weeks at biomasses of 0, 5, 10 or 18 g m⁻² (live weight) in twelve plastic pools (4.67 m², surface area) containing Potamogeton richardsonii, Myriophyllum exalbescens, Nuphar variegatum and Sparganium eurycarpum .
2. Crayfish significantly affected biomass, density and/or shoot morphology of all four macrophyte species. Differences in the effect of crayfish on macrophyte growth were related to plant species, crayfish sex and activity, and the abundance of alternative foods.
3. The effect of female crayfish on macrophyte growth was generally stimulatory. Myriophyllum and Potamogeton biomass, Potamogeton density and Myriophyllum length increased in the presence of female crayfish, possibly due to the reduction in herbivorous snails as a result of crayfish predation. In contrast, plant growth decreased in the presence of male crayfish: Myriophyllum, Nuphar and Potamogeton biomass, Myriophyllum and Sparganium density, and Sparganium and Poiamogeton length were reduced at male crayfish biomasses between 5 and 18 g m⁻².
4. These results indicate that even relatively low densities of crayfish can greatly affect the growth of submersed aquatic plants. Because of their ability to modify aquatic macrophyte, macroinvertebrate and, ultimately, fish communities, the introduction of crayfish into lakes where they do not occur could have a major effect on the structure and composition of the littoral zone.     

Patch- and reach-scale dynamics of a macrophyte-invertebrate system in a New Zealand lowland stream

Abundant growths of macrophytes are a common feature of streams in open lowland areas of New Zealand during summer, but the values of these to aquatic biota are poorly understood. We studied the temporal dynamics of, and associations amongst, elements of a macrophyte-invertebrate system to provide an improved information base for lowland stream management. The biomass of macrophytes increased significantly over the four quarterly sampling occasions from 43.8 g m^-2 in June to 370.8 g m^-2 in March; biomass was dominated by Egeria densa on all dates, except in December when Potamogeton crispus was dominant. We did not detect strong associations between epiphyton biomass and invertebrate abundance in our study, but this may reflect the fact that we sampled loosely-adhering epiphyton on young, surface-reaching shoots whereas invertebrates were collected from macrophytes growing through the water column. Density of some invertebrate species per gram dry weight of plant material varied by macrophyte type, with the chironomids Tanytarsus vespertinus and Naonella forsythi displaying positive correlations with Egeria and Potamogeton biomass, respectively. The shrimp Paratya curvirostris accounted for 50% of phytophilous invertebrate biomass, with Chironomidae the only other group to comprise more than 9%. Abundance of total phytophilous invertebrates displayed a positive linear relationship with macrophyte biomass in a sample (0.1 m²), and a humped relationship with species richness, such that highest numbers of taxa occurred at macrophyte biomass levels around 400 g dw m^-2. Our study suggests that intermediate macrophyte biomass levels are likely to enhance macroinvertebrate biodiversity in sandy-bottomed lowland streams. This revised version was published online in July 2006 with corrections to the Cover Date.     

Sediment and Water Nutrient Characteristics in Patches of Submerged Macrophytes in Running Waters

(1) The relative importance of sediments and water as nutrient sources for submerged macrophytes in running waters is poorly understood. Here we present water and sediment nutrient characteristics within macrophyte patches in Bavarian rivers. (2) No significant differences between early (June/July) and late summer (August/September) sediment nutrient characteristics could be detected within macrophyte patches. Therefore, a single sediment sample per macrophyte patch was considered to be sufficient for characterising nutrient concentrations during the main growing season in running waters. (3) Sediment TP (total phosphorus) is not a useful parameter for predicting trophic status in running waters. Sediment porewater SRP (soluble reactive phosphorus) concentration is not correlated to water body SRP or TP concentration; nor is it correlated with sediment TP content. Potamogeton coloratus, a oligotrophic species, is associated with low overlying and porewater SRP concentrations but high sediment TP content. Eutrophic species, such as Potamogeton pectinatus, are associated with low sediment TP. (4) It is hypothesized that Chara hispida primarily takes up sediment ammonia for nitrogen nutrition. (5) Nutrient characteristics of the water body and the sediment of eight macrophyte species in Bavarian rivers are described.     

Metal content in higher aquatic plants in a small siberian water reservoir

The dynamics of metal content in higher aquatic plants (macrophytes) in a small Bugach water reservoir in 1998–2006 was studied. A comparative estimation of the metal content in six macrophyte species (Typha latifolia L., Typha angustifolia L., Polygonium amphibium L., Potamogeton perfoliatus L., Potamogeton pectinatus L., Phragmites australis (Cav) Trin. Ex Steud.) showed that their metal concentrations do not generally exceed those known from the literature. Cluster analysis showed that the macrophyte species under study form two ecological groups with respect to the metal content, i.e., submerged plants (hydrophytes) and emergent aquatic plants (heliophytes).     

A statistical model predicting the occurrence and dynamics of submerged macrophytes in shallow lakes in the Netherlands

Hydrobiologia - Logistic regression was used to analyse the relationship between six submerged macrophyte taxa (Chara spp., Potamogeton perfoliatus, Potamogeton pectinatus, Potamogeton pusillus,...     

Submerged vegetation development in two shallow, eutrophic lakes

Submerged macrophyte vegetation in two shallow lakes in the Netherlands, Lake Veluwemeer and Lake Wolderwijd, has been affected by eutrophication in the late 1960's and 1970's. Recent changes in the vegetation occurred in the period following lake restoration measures. Between 1987 and 1993, the dominance of Potamogeton pectinatus decreased, while Charophyte meadows expanded over the same time interval. The pattern of change of the dominant macrophyte species might result from changes in the underwater light climate. Seasonally persistent clear water patches associated with the Chara meadows have been observed in the last few years. The interaction between submerged macrophyte vegetation succession and water transparency in the lakes is discussed.     

西太湖水生植物时空变化

水生植物在浅水湖泊生态系统中具有十分重要的作用。根据中国科学院太湖湖泊生态系统研究站1989年以来的常规监测资料,将西太湖（除东太湖以外的湖区）划分为9个区,采用点截法（point intercept method）,于2002～2005年对各区水生植物的种类、生物量和空间分布情况进行了6次调查。结果表明：西太湖现有水生植物16种,分属于11科12属;水生植物总面积约10220hm^2,其中沉水植物分布面积约占64．58％;挺水植物约占0．29％;漂浮植物约占38．16％。各个种之间生物量差异显著,马来眼子菜、荇菜、芦苇的生物量在所有水生植物中居前3位。多样性分析表明,水生植物种类4a来未发生明显变化,但种类和生物量季节性差异较大。水生植物呈环状分布在距湖岸5km以内的水域和部分岛屿周围,东岸和南岸为水生植物的主要集中分布区域,分布区连续性好,且水草种类齐全。挺水植物种类单一,仅有芦苇（Phragmites communis）一种,分布区域多限于水深小于1．6m的湖岸;沉水植物共有8种,为水生植物的主要组成部分,马来眼子菜（Potamogeton malaianus）的分布频度最高,在西山岛周围水域逐年扩张,成为该区域的先锋种;漂浮植物3种,主要以荇菜（Nymphoides peltata）为主,在七都水域有逐渐扩张的趋势。马来眼子菜、芦苇、荇菜表现出对水环境较强的适应能力,目前为西太湖的3个优势种。20世纪50年代以来,西太湖水生植物种类减少了50种,其中水质下降是导致水生植物种类不断减少甚至消失的一个重要原因。围网养殖和不合理的捕捞方式也对局部水域的植物造成极大的破坏。水生植物生存环境日益严峻,种群单一化趋势日益明显。     

Determinants of macrophyte palatability to the pond snail Lymnaea stagnalis

Summary 1. This study aimed to identify the chemical and structural determinants of macrophyte palatability to the pond snail Lymnaea stagnalis . Eleven macrophyte species were investigated, and one of them ( Potamogeton lucens ) was collected at four sites, on two different dates in the year, to study palatability determinants at an intra-specific level.
2. Plant palatability to L. stagnalis was determined through non-choice feeding assays. Dry matter content (DMC), total phenolic content and protein content were measured for each macrophyte species. These parameters, and soluble carbohydrate content, were also measured for each sample of P. lucens .
3. The palatability of macrophytes was positively related to their protein content (between species only) and negatively related to their DMC (both between species and within P. lucens ). No simple relationship was found between the palatability of macrophytes and their phenolic content, but highly palatable macrophytes consistently exhibited a low phenolic content.
4. These results emphasise that macrophyte palatability is a multifactorial attribute, potentially depending on both structural and chemical traits. Because some of these traits were correlated, further investigations are required to assess their respective influence on macrophyte palatability.     

Seasonal dynamics of macrophyte abundance in two regulated streams

This study analysed seasonal dynamics of macrophyte abundance in two perennial lowland regulated streams (Stream 1 and 2) in the Danube basin (Slovakia). Assessments of macrophyte abundance and environmental characteristics were accomplished 7 times during the vegetation period in 2005 within a 100 m long section. Statistically significant differences in total abundance of macrophytes as well as an abundance of macrophyte groups (hydrophytes, amphiphytes, helophytes) and Potamogeton nodosus were detected among months within the vegetation period. Abundance fluctuations for individual macrophyte groups and species were moderate in Stream 1 and much stronger in Stream 2. Only amphiphytes showed bimodal temporal distribution in Stream 1, but the abundance of this group was low, reflecting more or less random occurrence of species in vegetation period. Multiple linear regression revealed that water depths and air temperature are the most significant environmental variables affecting the seasonal pattern of total as well as dominating group abundance in Stream 1 and 2, respectively. In all cases, abundances are significantly influenced by the abundance of the respective group in the preceding month. Culmination time differed between streams for all macrophyte groups except helophytes. Total abundance culminated 0.57 month later in the Stream 1 compared to Stream 2.     

Ecosystem development in different types of littoral enclosures

Macrophyte growth was studied in two enclosure types (gauze and polythene) in a homogeneousPotamogeton pectinatus bed in Lake Veluwe (The Netherlands). The gauze was expected to allow for sufficient exchange with the lake to maintain similar seston densities, the polythene was expected to exclude fish activity and most water exchange. Polythene enclosures held higher totalP. pectinatus biomass (ash-free dry weight, AFDW) than the lake, gauze enclosures were intermediate. The enclosures had a higher abundance of other macrophyte species (Chara sp.,Potamogeton pusillus) than the lake. Seston ash content was not but seston AFDW, periphyton ash content and AFDW were lower in polythene than in gauze enclosures. The difference in plant biomass between gauze and polythene may be attributed to a difference in periphyton density and in seston AFDW due to zooplankton grazing (Rotatoria andDaphnia densities were higher in polythene enclosures). Since seston and periphyton AFDW and ash content were similar in lake and gauze enclosures, the intermediate macrophyte biomass in the gauze enclosures may be explained by reduced wave action and mechanical stress. Alternatively, phytoplankton inhibition by allelopathic excretions from the macrophytes may have caused the high macrophyte biomass in the polythene, and an absence of sediment-disturbing fish the intermediate biomass in the gauze enclosures. Creation of sheltered areas may favour macrophyte growth through both mechanisms and we conclude that this can be an important tool in littoral biomanipulation.     

Effects of grazing by fish and waterfowl on the biomass and species composition of submerged macrophytes

Biomanipulation improved water transparency of Lake Zwemlust (The Netherlands) drastically. Before biomanipulation no submerged vegetation was present in the lake, but in summer 1987, directly after the measure, submerged macrophyte stands developed following a clear-water phase caused by high zooplankton grazing in spring. During the summers of 1988 and 1989 Elodea nuttallii was the most dominant species and reached a high biomass, but in the summers of 1990 and 1991 Ceratophyllum demersum became dominant. The total macrophyte biomass decreased in 1990 and 1991. In 1992 and 1993 C. demersum and E. nuttallii were nearly absent and Potamogeton berchtholdii became the dominant species, declining to very low abundance during late summer. Successively algal blooms appeared in autumn of those years reaching chlorophyll-a concentrations between 60–130 µg l^–1. However, in experimental cages placed on the lake bottom, serving as exclosures for larger fish and birds, E. nuttallii still reached a high abundance during 1992 and 1993. Herbivory by coots (Fulica atra) in autumn/winter, and by rudd (Scardinius erythrophthalmus) in summer, most probably caused the decrease in total abundance of macrophytes and the shift in species composition.     

Macrophytes from lakes in the eastern Pyrenees: community composition and ordination in relation to environmental factors

1. Thirty-six species of macrophytes (fourteen flowering plants, two quillworts, sixteen mosses and liverworts, and two algae) were collected in an extensive survey of 116 high mountain lakes in the eastern Pyrenees. Seventy per cent of the lakes showed macrophyte development. 2. The isoetids (Isoetes lacusiris, Isoetes setacea and Subularia aquatica) were the dominant growth form, although the natopotamid Sparganium angusifolium was the most widespread species. Potamids (Potamogeton spp., Ranunculus spp.), the alga Nitella gr. opaca and some mosses (Warnstorfia exannulata, Sphagnum denticulatum) were often present. 3. A multivariate ordination analysis (RDA-redundancy analysis) revealed that water chemistry, altitude and vegetation cover of the catchment, and nutrient availability are major environmental factors associated with macrophyte distribution along the eastern Pyrenean lakes. Isoetids prevailed in softwater oligotrophic lakes, potamids in relatively hardwater oligotrophic lakes, and Potamogeton natans and Callitriche palustris in small and eutrophic water bodies affected by the presence of cattle.     

Macrophyte communities of European streams with altered physical habitat

The impact of altering hydro-morphology on three macrophyte community types was investigated at 107 European stream sites. Sites were surveyed using standard macrophyte and habitat survey techniques (Mean Trophic Rank Methodology and River Habitat Survey respectively). Principal Components Analysis shows the macrophyte community of upland streams live in a more structurally diverse physical habitat than lowland communities. Variables representing the homogeneity and diversity of the physical environment were used to successfully separate un-impacted from impacted sites, e.g. homogeneity of depth and substrate increased with decreasing quality class for lowland sites (ANOVA p < 0.05). Macrophyte attribute groups and structural metrics such as species richness were successfully linked to hydro-morphological variables indicative of impact. Most links were specific to each macrophyte community type, e.g., the attribute group liverworts, mosses and lichens decreased in abundance with increasing homogeneity of depth and decreasing substrate size at lowland sites but not at upland sites. Elodea canadensis, Sparganium emersum and Potamogeton crispus were indicative of impacted lowland sites. Many of the indicator species are also known to be tolerant to other forms of impact. The potential for a macrophyte tool indicative of hydro-morphological impact is discussed. It is concluded one could be constructed by combining indicator species and metrics such as species richness and evenness.     

Macrophyte species composition,distribution and diversity in relation to some physicochemical factors in the littoral zone of Lake Ziway,Ethiopia

The species composition, distribution and diversity of macrophytes in Lake Ziway were determined at the end of dry and wet seasons along nine littoral sites during 2010 using a belt transect method. Some physicochemical parameters were also measured. Fourteen macrophyte species were identified with low species diversity for the lake (H' value of 1.805). The macrophyte species composition of the lake has undergone many changes during the last few decades. Arundo donax, which was never reported earlier, attained the highest relative density (30.7%) and frequency (30.5%) in this study, followed by Echinochloa colona, Potamogeton schweinfurthii, Cyperus articulatus, Typha latifolia and Cyperus papyrus. The average densities of A. donax, C. articulatus, E. colona and Pistia stratiotes were positively correlated with nutrients, whereas the density of the other species had negative correlation with physicochemical variables (CCA). Generally, the present macrophyte composition and abundance indicates healthy ecological condition of the lake. But if nutrient levels continue to increase and water levels continue to decline, we expect further changes in macrophyte composition and especially a shift towards invasive floating species.