Aquatic Macrophyte Species Research Articles

Ecotoxicological effects of the azole antifungal agent clotrimazole on the macrophyte species Lemna minor and Lemna gibba

Pharmaceuticals are a large and diverse group of compounds used to treat, prevent and diagnose disease. Among these, a group that has been recently detected in the aquatic environment is that of the azole compounds, commonly used as antifungals. Clotrimazole (CLO) is a nonbiodegradable persistent azole compound, with broad-spectrum antifungal activity for which virtually no toxicological data are available, especially towards aquatic plants. The few existent data point to a documented interference with cytochrome P450 system of exposed organisms. Therefore, the aim of this paper was to evaluate the ecotoxicological effects of the fungicide CLO on two aquatic macrophyte species, namely, Lemna minor and Lemna gibba. To attain this purpose, an acute assay (96 h) was performed with both species being exposed to CLO, in a concentration range of 0 to 5 μg L−1. The analyzed endpoints were levels of chlorophyll a and b, total, carotenoids, catalase (CAT) and glutathione -s-transferases activities (GSTs). In general, CLO exposure caused some minor alterations in L. minor and L. gibba pigment contents. Antioxidant enzymes exhibited a different pattern in both species, since the highest concentrations of CLO caused an increase on CAT activity, and a decrease on GSTs activity in L. minor, and the opposite in L. gibba, reflected by a decrease on CAT activity and an increase on GSTs activity in all tested concentrations. These results demonstrate that CLO exposure resulted in potential deleterious effects on macrophytes, namely with the involvement of the antioxidant defense mechanisms that were likely deployed to cope with pro-oxidative conditions established by CLO.

Latitudinal variation in global range‐size of aquatic macrophyte species shows evidence for a Rapoport effect

AbstractTo test hypotheses concerning the applicability of the Rapoport effect (RE: “species that occur at higher latitudes tend to have greater geographical range‐size than species which have ranges limited to latitudes closer to the equator”) to aquatic macrophytes at global scale, we analysed the world latitudinal distribution and range‐size of 1,083 vascular aquatic macrophyte species, from 91 genera in 11 families. We targeted macrophyte families strongly associated with inland aquatic habitats (i.e. with a zero, or only very low, proportion of constituent species which occur also in non‐aquatic habitats), and which are distributed across a substantial latitudinal gradient, a necessary condition to test our hypotheses.The macrophyte species present in these families include plants from all the normally accepted life form‐defined functional groups of macrophytes, namely submerged, free‐floating, floating‐leaf rooted and emergent species, and represent the three major vascular taxonomic groups occurring as aquatic macrophytes (ferns/fern allies, monocots, and dicots). For the analysis, we used both latitude‐only and areal measures of macrophyte species geographic range‐size, within a 10 × 10° (latitude × longitude) grid of 238 grid cells, covering the six world ecozones (Palaearctic, Orient, Australasia, Nearctic, Neotropics, Afrotropics) that primarily contain inland freshwater and brackish macrophyte habitats.The results provide new insight into the relationships between global range‐size of macrophytes, latitude, and other potential spatio‐environmental and anthropogenic drivers acting upon these plants at world scale. In particular, the outcomes indicated that: (1) the range‐size versus latitude distribution of macrophytes shows evidence of a strong RE influence, with significantly greater species range‐size at higher latitudes; and (2) the β‐diversity pattern of species distribution along this latitudinal gradient is poorly explained by nestedness organisation, and species turnover is a more likely explanation of the observed changes in species distribution with latitude.Spatio‐environmental and anthropogenic variables other than latitude may also influence the observed global geographical pattern of macrophyte range‐size, although their importance as predictors varies between individual families. Extent of agricultural land use, altitude, and historic (post‐Quaternary) climate change velocity were all significant predictor variables for some families. However, interestingly, neither the area of land nor the area of waterbody present per grid cell were major influences on macrophyte range‐size distribution.Our finding of evidence for an RE, acting at global scale in aquatic macrophytes, contributes to increasing the generality of conclusions so far reached about the large‐scale factors that drive patterns of species range‐size at global scale. The study also provides a baseline for future macroecological work on aquatic plants, and potentially other freshwater organisms, particularly in the context of predicting how the world ranges of freshwater biota will respond to ongoing global environmental change.

The level of genetic diversity and differentiation of tropical lotus, Nelumbo nucifera Gaertn. (Nelumbonaceae) from Australia, India, and Thailand

BackgroundNelumbo nucifera Gaertn., a perennial aquatic macrophyte species, has been cultivated in several Asian countries for its economic importance, and medicinal uses. Two distinct ecotypes of the species are recognized based on the geographical location where the genotypes are adapted, i.e., tropical lotus and temperate lotus. The genetic diversity levels and differentiation of the tropical lotus from poorly studied geographic regions still remain unclear. Here, the population genetic diversity and structure of 15 tropical lotus populations sampled from the previous understudied natural distribution ranges, including India, Thailand, and Australia, were assessed using nine polymorphic SSR markers.ResultsThe SSR markers used to genotype the 216 individuals yielded 65 alleles. The highest and lowest genetic diversity estimates were found in Thailand and Indian populations, respectively. STRUCTURE analysis revealed three distinct genetic clusters, with relatively low admixtures, supported by PCoA cluster analysis. Low levels of gene flow (mean N⁠m = 0.346) among the three genetic clusters signified the Mantel test for isolation by distance, revealing the existence of a positive correlation between the genetic and geographic distances (r = 0.448, P = 0.004). Besides, AMOVA analysis revealed a higher variation among populations (59.98%) of the three groups. Overall, the populations used in this study exposed a high level of genetic differentiation (FST = 0.596).ConclusionsThe nine polymorphic microsatellite markers used in our study sufficiently differentiated the fifteen tropical N. nucifera populations based on geography. These populations presented different genetic variability, thereby confirming that populations found in each country are unique. The low genetic diversity (HE = 0.245) could be explained by limited gene flow and clonal propagation. Conserving the available diversity using various conservation approaches is essential to enable the continued utilization of this economically important crop species. We, therefore, propose that complementary conservation approaches ought to be introduced to conserve tropical lotus, depending on the genetic variations and threat levels in populations.

ELABORACIÓN DE UN MICROCOSMO INTERCONECTADO PARA PROCESOS DE FITORREMEDIACIÓN A ESCALA DE LABORATORIO UTILIZANDO MACRÓFITAS ACUÁTICAS DE LA CIUDAD DE NEIVA, COLOMBIA.

Wastewater treatment is one of the greatest challenges for men today; one of the solutions has been the use of aquatic macrophytes, a cost-effective biotechnological application that avoids the use of chemicals or other expensive technologies, and that is also environmentally friendly. With this research, an interconnected microcosm was developed as a prototype for phytoremediation processes at laboratory scale. For design and construction, two important elements were taken into account; the first one related to a preliminary botanical inventory in some lentic ecosystems present in the city of Neiva, with the purpose of knowing the existing specimens; as a second element, and taking into account the taxa collected, a brainstorming session was carried out, analyzing in each proposal the habitat, light, temperature, space and substrate requirements. 22 species of aquatic macrophytes were identified, Eleocharis sp., Najas wrightiana and Eichhornia crassipes were selected; in terms of design, 34 ideas were proposed, selecting a proposal formed by 3 modules related to 3 growth habits (floating, submerged and emerging). The modular prototype was adapted to the characteristics of the 3 selected species, taking into account their growth habits.

Taxonomic revision of Strandesia s.s. (Crustacea, Ostracoda) from four Brazilian floodplains, with the description of three new species.

The present paper is a contribution to the taxonomy of the genus Strandesia. Here, we describe three new species: S. thomazi nov. sp., S. galeati nov. sp. and S. nakatanii nov. sp. We also describe the male of Strandesia obtusata (Sars, 1901); this is the first record of sexual populations of a Brazilian Strandesia species. Nine other Strandesia species from the Amazon, Araguaia, Pantanal and Paraná river floodplains are redescribed. We also propose that Strandesia trichosa Roessler, 1990 is a synonym of Strandesia psittacea Sars, 1901. Most of the species analyzed here are endemic to the Neotropical region, with the exception of Strandesia bicuspis (Claus, 1892) G.W. Müller, which occurs also (as an alien invasive species) in the Palaearctic. This genus occurs in water bodies with a wide range of abiotic variables and in many different aquatic macrophyte species. The species analyzed here have a highly conservative soft part morphology, but an impressive variety of carapace shapes.

河西走廊水生植物多样性格局、群落特征及影响因素

PDF HTML阅读 XML下载 导出引用 引用提醒 河西走廊水生植物多样性格局、群落特征及影响因素 DOI: 10.5846/stxb201810242298 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 湖北省教育厅项目（T201701）；科学技术部资助项目（2013FY112300）；国家自然科学基金面上项目（31570366） Biogeographic pattern, main community types, and the influencing factors of aquatic macrophytes in the Hexi Corridor of Northwest China Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:水生植物是湿地生态系统重要组成部分，研究水生植物多样性分布格局及其影响因素对地区水生植物资源保护具有重要意义。通过野外调查并结合气候等环境因素，研究了河西走廊主要水生植物群落类型、数量特征、水生植物多样性分布格局及影响因素，并对中域效应假说进行了验证。研究结果表明：（1）河西走廊地区共有水生植物29科42属84种，群落的聚类分析可将河西走廊水生植物群落划分为15个主要群落类型；（2）河西走廊水生植物群落类型主要受到水温、海拔、经纬度等环境因子影响，群落物种多样性指数与盐度以及溶解性固体总量呈显著性相关；（3）河西走廊水生植物多样性空间格局呈现出"∩"型的单峰格局，中域效应模型能较好地解释该地区水生植物多样性水平的纬度格局及海拔垂直分布格局，对该区域水生植物物种丰富度在纬度和海拔梯度上的变异解释率分别为57.56%、63.5%。分析表明，河西走廊水生植物物种丰富度格局由几何（边界）限制和随机过程及其他未知因素共同控制，且几何（边界）限制和随机过程贡献率较大；同时本研究中未考虑的环境异质性、气候、人为干扰等因素也对河西走廊水生植物多样性空间分布产生重要影响。 Abstract:Aquatic plants are an important part of wetland ecosystems. Studies about the distribution pattern of aquatic plants and its influencing factors can provide important background for the regional protection of aquatic plant resources. In this study, the main aquatic plant community types, quantitative characteristics, species richness patterns, and influencing factors of aquatic plants in the Hexi Corridor were studied using field investigation data. The mid-domain effect hypothesis was used to explain geographical diversity patterns of aquatic macrophytes in the region. The main results are as follows:(1) there were 84 species belonging to 42 genera of 29 families of aquatic plants in the Hexi Corridor. Cluster analysis of the community showed that there were 15 main aquatic plant community types in this region; (2) the aquatic plant community types in the Hexi Corridor were mainly affected by environmental factors such as water temperature, elevation, latitude, and longitude. The community species diversity index was significantly correlated with salinity and total dissolved solids; (3) the spatial pattern of aquatic plant diversity in the Hexi Corridor exhibited a unimodal pattern. The mid-domain effect model better explained the latitudinal pattern and the vertical distribution pattern of aquatic plant diversity in the region, with explanation rates reaching 57.56% and 63.5%, respectively. These results indicate that the patterns of aquatic macrophyte species richness in the Hexi Corridor were determined by geometric (boundary) constraints, random processes, and other unknown processes. Geometric (boundary) constraints and random process showed a higher contribution rate on geographic richness gradients. Also, we highlight that unmeasured factors including environmental heterogeneity, climate, and human disturbance may greatly affect aquatic plant species richness in the Hexi Corridor of Northwest China. 参考文献 相似文献 引证文献

Aquatic macrophyte diversity, distribution, and control in coastal Southern Ghana, with priority on non-native invasive species

Abstract. Ernest A, Ameka GK. 2019. Aquatic macrophyte diversity, distribution, and control in coastal Southern Ghana, with priority on non-native invasive species. Ocean Life 3: 87-93. Southern Ghana has been the focus of research into the variety and distribution of aquatic macrophytes, focusing on invasive species. Greater Accra, the Central Region, the Ashanti Region, the Eastern Region, the Volta Region, and the Western Region were all included in the study. Voucher specimens were obtained from 44 locations and submitted to the Ghana Herbarium. Sixty-two species of aquatic macrophytes were found, representing 48 genera and 30 families. All the aquatic macrophytes seen were classified into two groups, those that were invasive and those that were not; these were further divided into their respective families. With nine species, the Cyperaceae family emerged as the contender. IUCN (2004) criteria were used to determine if a species met the definition of an invasive. Because of this, the observed aquatic macrophytes were classified as invasive or noninvasive. Fifty-two aquatic species were found to be noninvasive, whereas eleven were found to be invasive. The aquatic macrophytes' life histories were also analyzed. There were 41 emergent species (67%), 11 free-floating species (17%), eight submerged species (13%), and two floating-leaf species (3%). Eleven types of invasive aquatic plants were found, and distribution maps were made for each. In the southern region of Ghana, Pistia stratiotes were found in seven different locations, making it the most widespread invasive aquatic plant in the region. All 62 invasive and noninvasive species were recorded in a database. Among these were the species' scientific and colloquial names and their genus and family, description, reproduction, habitat, distribution, and uses. Each method of control for invasive aquatic macrophytes was reviewed to make advantage of the most effective strategies for their management and eradication.

INVENTORY OF AQUATIC MACROPHYTE SPECIES IN COASTAL RIVERS OF THE SÃO PAULO STATE, BRAZIL

The coastal region of the Sao Paulo state (Southeastern Brazil) is marked by the presence of the Serra do Mar, a system of mountain ranges with altitude up to 1,000 m. Due to the difference of proximity of the mountain range to the coastline, the coastal plains have different width. As a consequence, the rivers that cross the plains also have different length, greater or less influence of marine waters and slope variation. We carried on an inventory of aquatic macrophyte species in order to assess the species and life form richness and latitudinal distribution in this region. Macrophytes were inventoried at 100 sampling sites in eight rivers (between 9 and 19 sites per river) in March 2017. General descriptions on taxonomic aspects, life forms and frequency of occurrence of the macrophytes were explored. We recorded 45 taxa of aquatic macrophytes belonging to 24 families. Three species are exotic, but they presented low frequencies of occurrence. The vast majority of the taxa have emergent life form. Floating and submerged macrophytes were found in only two rivers. The most frequent species were Crinum americanum L. (Asparagales, Amaryllidaceae), Spartina alterniflora Loisel. (Poales, Poaceae) and Schoenoplectus californicus (C. A. Mey.) Sojak (Poales, Cyperaceae). Most taxa are rare in terms of occurrence. Only four species occurred along a large part of the north-south stretch sampled and these, possibly, have a wide tolerance to the variation in resource requirements and salinity. The north-south gradient of the taxa occurrence may be related to the diversity of environmental characteristics due to differences in the rivers length and coastal plains width.

Assessment of autochthonous aquatic macrophytes with phytoremediation potential for dairy wastewater treatment in floating constructed wetlands

The phytoremediation potential of autochthonous aquatic plants has been increasingly explored. This study investigated the use of macrophytes found in natural ecosystems in the southern coast of the state of Bahia, Brazil, for treatment of dairy wastewater (DWW) using experimental systems of the floating constructed wetland type. Four species of aquatic macrophytes have been tested using floating platforms made from PET bottles. The chemical oxygen demand (COD), biochemical oxygen demand (BOD), total solids (TS), pH, and temperature of DWW were analyzed for 15 days. On the fifth day, a 74.8% (±7.7) decrease of BOD was achieved. Eichhornia crassipes (86.4%) and Eichhornia paniculata (84.8%) showed the best results, while Polygonum ferrugineum and Borreria scabiosoides achieved the removal of 65% and 74.2% of BOD, respectively. Considering the TS reduction in the DWW diluted with rainwater, the best results were obtained by Eichhornia crassipes (64.3%) and Eichhornia paniculata (65.18%). The macrophytes of the Eichhornia genus showed a greater potential for the treatment of DWW than the macrophytes Polygonum ferrugineum and Borreria scabiosoides, with a hydraulic retention time varying between four and five days.

Ecological aesthetic assessment of a rebuilt wetland restored from farmland and management implications for National Wetland Parks.

While wetlands are usually used as a natural approach to remove biodegradable pollutants in surface water, their purification efficiencies coupled with their aesthetic features are of less concern. The water quality, plant landscape, acoustic environment and odour indicators were investigated in the surface water inlet and outlet of the Fujin National Wetland Park (FNWP), restored from farmlands in Northeast China. Major concentrations of pollutants in the inlet and the outlet subjected to surface flow wetland treatment were monitored, and the removal efficiencies were calculated based on 54 water samples (6 sites×3 seasons×3 replicates). The results showed that the total nitrogen (TN) and organic carbon in surface water decreased significantly after the wetland treatment, while the total phosphorus (TP) did not decrease significantly. The removal efficiencies for TN and BOD5 changed seasonally and reached 69.08% and 60.44%, respectively. An ecological aesthetic index (EAI) was developed based on the trophic state index coupled with plant landscape, acoustic and odour indicators, and the calculated EAI showed that the outlet delivered a more aesthetically harmonious appearance than the inlet in spring and autumn, but not in summer. Based on the current aquatic macrophyte species and documented purification efficiencies in FNWP, we recommend an improved ecological aesthetic management approach that utilizes and arranges diverse native plants from the surrounding wetlands (e.g. Scirpus validus) in addition to local Nelumbo nucifera, Nymphaea tetragona and Myriophyllum spicatum, and conserves the indicative and endangered species (Aldrovanda vesiculosa), from the visual appeal of the waterscape.

Evaluation of physiological changes induced by the fluoroquinolone antibiotic ciprofloxacin in the freshwater macrophyte species Lemna minor and Lemna gibba

The worldwide increase in the consumption of antibiotics is becoming a concern for the scientific community, since the presence of their residues in the wild poses specific challenges, especially in ecotoxicological terms. Currently, antibiotics are used for a wide range of purposes, being used against bacterial diseases but also as growth promoters. As a result, their environmental presence can affect wild organisms, especially those from the aquatic environment. This scenario leads to the need of characterizing the toxicity of antibiotics, especially towards non-target organisms. In this study we selected two species of aquatic macrophytes, Lemna minor and Lemna gibba, which are standard plant species inscribed in ecotoxicological testing guidelines. In this work we characterized the toxic effects of the quinolone antibiotic ciprofloxacin (in levels of 0.005, 0.013, 0.031, 0.078, and 0.195 mg/L), focusing on its potential toxicity towards photosynthetic mechanisms, and pro-oxidant effects. These objectives were attained by measuring the concentrations of chlorophyll a and b, and carotenoids levels. The determination of the quantum yield allowed assessing the effects of ciprofloxacin on the photochemical efficiency of the Photosystem II (PSII). The pro-oxidant effects induced by ciprofloxacin were evaluated by measuring oxidative stress biomarkers, such as catalase activity, and also by determining lipoperoxidation levels. The obtained results showed no differences in terms of the content of both chlorophylls a and b, or any change in the photochemical efficiency of the PSII; however, the global carotenoids content of L. gibba were significantly decreased. The activity of the anti-oxidant enzyme catalase was also significantly increased in L. minor. L. gibba showed a decrease in lipid peroxidation levels, but only for the two lowest concentrations of ciprofloxacin. The global set of data shows the activation of the anti-oxidant defensive system of both plant species, a response that was likely activated by the pro-oxidant character of ciprofloxacin. Our data demonstrate the interference of this therapeutic compound at different levels of plant metabolism, at ecologically relevant concentrations. In fact, the obtained results are of ecological relevance since they illustrate deleterious effects that may compromise the physiology of aquatic non-target plant species.

Effect of shipping induced changes in flow velocity on aquatic macrophytes in intensively navigated rivers

In the last decades, the aquatic vegetation of the river Rhine has declined. In order to rehabilitate the vegetation in the river it is vital to gain insights in the environmental factors that affect the occurrence and establishment of aquatic macrophytes. Especially navigation is expected to negatively influence the environmental conditions through generating water displacements that changes flow velocities in the littoral zones. The aim of this study was to assess the effect of navigation on occurrence of aquatic macrophytes species in the river Rhine by 1) deriving a comprehensive overview of their sensitivities to flow velocity with the use of species sensitivity distributions (SSDs), and 2) calculating the potentially not occurring fraction (PNOF) of their species pool based on measurements of flow velocities during ship passages at various types of littoral zones. Maximum flow velocity sensitivity ranged from 43 to 120 cm sö1. Field measured flow velocities fluctuated mostly between 0 and 10 cm sö1. However, maximum measured flow velocities during ship passages ranged between 45 and 74 cm. sö1. This resulted in a PNOF value of almost 0.50, indicating that 50% of the plant species is potentially absent due to ship generated changes in flow velocities. As shipping intensity is expected to increase in the future the likelihood of flow velocities limiting macrophytes is expected to increase. This highlights the need of constructing connected backwaters, side channels and shore channels behind longitudinal training dams as they decrease the influence of navigation on flow velocity.

Response of benthic algae to environmental conditions in an urban lake recovered from eutrophication, China

Benthic algae communities dominate the primary production in littoral zone of shallow lake. To understand the long-term effect of alteration in the composition of benthic algae community assemblage in such as a lake in China, we analyzed the benthic algae developments and indicators in the Donghu Lake in Wuhan, central China in 2004 and 2014. We compared the benthic algae biomass, compositions, and species richness of aquatic macrophytes and the changes of primary physicochemical parameters. The results show that in the 10-year period, chl a and conductivity declined significantly but nutrient level of the whole lake remained largely stable. The benthic algae biomass doubled and the relative proportion of green algae increased, whereas the benthic diatom ratio decreased. The benthic diatom assemblages and taxa differed in a number of ways, showing more epiphytic diatom species, and the relative abundance and species richness changed markedly. The number of aquatic macrophyte species increased from 3 in 2004 to 15 in 2014, presenting a remarkable recovery from previous eutrophication conditions. The changes of water level, chl a, and conductivity played a crucial role in governing aquatic macrophytes re-colonization in the littoral zones in the period. The ecological characteristics of littoral benthic diatoms reflect habitat coupling as indicated by redundancy analysis. Therefore, the close link between benthic algae and macrophyte recovery demonstrates that the benthic algae metrics are much more useful than nutrient levels to quantify the process of restoration in the lake.

Assessment of a coastal lagoon metal distribution through natural and anthropogenic processes (SE, Brazil)

The present study intends to assess the metal pollution of a eutrophic coastal lagoon, analyzing the long-term and actual metal content in surface sediments, suspended particles, aquatic macrophyte and fish species, and the loads emitted from natural processes and anthropogenic sources, including the relative emission of domestic untreated sewage. Distribution indicated contamination of suspended particles with Cd and the predominance of Pb in the bioavailable form in surface sediments which may explain Cd and Pb contamination in fish. Domestic untreated sewage was an important source of Cu and due to the lagoon's management, this source may be increasing the metal content in the lagoon's surface sediments. Soil loss, atmospheric deposition and solid waste disposal also contributed to metal inputs to the lagoon. Extensive contamination has been prevented by the lagoon's management such as sandbar opening. Metal retention within the watershed soils reduce the effective metal transference and lagoon pollution.

Leaf traits of macrophytes in lakes: Interspecific, plant group and community patterns

In freshwater systems the differentiation between macrophyte groups and growth forms is evident. The plant functional approach was used to understand the patterns of traits seen in the macrophytes of lakes at three levels: interspecific, functional groups and communities. Leaf area (LA), leaf dry weight (LDW) and specific leaf area (SLA) were measured for 31 macrophyte species in 30 lakes in Poland. To investigate the community structure, aquatic macrophyte species were sampled in 30 lakes 100 along 145 sections at the bottoms of the lakes (depth zones at 1.0 m). In total, we collected 14 500 cover-plant samples (quadrat, area = 0.1 m2). For each sample, we estimated the coverage (%) of species by SCUBA diving. Leaf trait variation was examined via mean or community-weighted mean (CWM) comparisons at three levels: interspecific, species grouped into plant functional groups (FGs) and communities. Shifts in leaf trait values were found at the interspecific and FG levels. LA, LDW and SLA varied widely across the 31 macrophyte species and among functional groups. Our results show that there are differences between CWM trait values (LDW, LA) among communities. In summary, we found that SLA decreased with increased water pH and calcium content interspecifically and among communities. Our findings show that different functional patterns predict the functioning of plant communities and FGs in lakes. Furthermore, the diversity in functional traits appears to be part of community assembly for macrophytes. At the functional group level, there are shifts in leaf traits. In contrast, among communities, there are low variations in leaf traits.

Comparação da retenção de cádmio e chumbo nos tecidos vegetais das macrófitas aquáticas aguapé (Eichhornia sp.) e taboa (Typha sp.) por biossorção e fitorremediação

Tecnologias alternativas como a biossorção e a fitorremediação são eficazes para remoção de metais da água. A fim de comparar essas duas tecnologias, em escala laboratorial, o presente trabalho teve como objetivo avaliar a retenção mássica dos metais tóxicos Cd e Pb nos tecidos vegetais de duas espécies de macrófitas aquáticas, o Aguapé (Eichhornia sp.) e a Taboa (Typha sp.). Na biossorção a biomassa seca das macrófitas aquáticas Eichhornia sp. e Typha sp. permaneceram em contato com soluções contaminadas com Cd (4 mg L-1) e Pb (4 mg L-1) isolados em intervalos de tempo distintos, até 24 horas. As amostras foram coletadas, filtradas e analisadas por ICP OES. No ensaio de fitorremediação as plantas mães permaneceram em processo de aclimatação em solução nutritiva. Após a aclimatação plantas filhas foram coletadas e acondicionadas em frascos de polietileno com soluções nutritivas contaminadas com as mesmas concentrações de Cd e Pb isoladamente. Ao longo do período de ensaio, alíquotas da solução foram coletadas, filtradas e analisadas no ICP OES. Para verificação da concentração de metais acumulados nos tecidos vegetais, após 21 dias de contato com as soluções contaminadas, as plantas foram retiradas dos frascos, lavadas e secas para realização da digestão Nitro-Perclórica seguida da análise no ICP OES. Para ambos os tratamentos, os ensaios foram em triplicatas e para a análise estatística utilizou-se o ANOVA e o Teste-t, com nível de significância de 5%. Os metais retidos nos tecidos vegetais (q) do Aguapé apresentaram os valores máximos de 18,8 mg g-1 (Cd) e de 8,6 mg g-1 (Pb) e a Taboa de 15,0 mg g-1 (Cd) e 4,6 mg g-1 (Pb) na biossorção. Na fitorremediação a concentração de metais nos tecidos vegetais do Aguapé foi de 3,2 mg g-1 (Cd) e 4,28 mg g-1 (Pb) e de 5,0 mg g-1 (Cd) e 2,3 mg g-1 (Pb) na Taboa. Aparentemente, as biomassas secas apresentam um melhor desempenho na remoção de Cd e Pb.

Leaf Soluble Carbohydrates, Free Amino Acids, Starch, Total Phenolics, Carbon and Nitrogen Stoichiometry of 24 Aquatic Macrophyte Species Along Climate Gradients in China.

Leaf soluble carbohydrates (SC), free amino acids (FAA), starch, total phenolics (TOPH), carbon (C), and nitrogen (N) stoichiometry of 24 aquatic macrophyte species were studied at 52 selected sites in eastern, 31 sites in southwestern and 6 sites in western China, including 12 submerged, 6 floating-leaved, 4 emergent and 2 free-floating macrophytes. The leaf stoichiometric characteristics differed significantly among the plant species of the four different life forms, the lowest C content occurring in submerged macrophytes and the highest N content in free-floating macrophytes. Overall, though the variance explained by the linear regression models was low, the C and N contents decreased toward the northern latitudes, the C content and the C:N ratios increased with increasing altitude. Multiple regressions revealed that the stoichiometric characteristics of submerged macrophytes varied significantly across the large spatial and climatic gradients and among the species studied. For floating-leaved and emergent macrophytes, no correlation between climate factors and SC, FAA, starch, TOPH, C, and N contents and C:N ratio was observed. For free-floating macrophytes, the TOPH content was markedly positively correlated with latitude and altitude. We conclude that the C and N contents related more closely to latitude, altitude or mean annual air temperature than did the C and N metabolic indicators for the submerged macrophytes, while the relationships with the metabolic indicators turned out to be insignificant for most species of the other life forms. The results helped us to identify species with significant physiological plasticity across geographic and climatic gradients in China, and such information is useful when conducting restoration of lost aquatic plants in different climate regions.

Does intraspecific variability matter in ecological risk assessment? Investigation of genotypic variations in three macrophyte species exposed to copper

To limit anthropogenic impact on ecosystems, regulations have been implemented along with global awareness that human activities are harmful to the environment. Ecological risk assessment (ERA) is the main procedure which allows to assess potential impacts of stressors on the environment as a result of human activities. ERA is typically implemented through different steps of laboratory testing. The approaches taken for ERA evolve along with scientific knowledge, to improve predictions on ecological risks for ecosystems. We here address the importance of intraspecific variability as a potential source of error in the laboratory evaluation of pollutants. To answer this question, three aquatic macrophyte species with different life-history traits but with their leaves directly in contact with the water were chosen; Lemna minor and Myriophyllum spicatum, two OECD model species, and Ceratophyllum demersum. For each species, three or four genotypes were exposed to 7–8 copper concentrations (up to 1.9 mg/L, 2 mg/L or 36 mg/L for C. demersum, L. minor and M. spicatum, respectively). To assess species sensitivity, growth-related endpoints such as Relative Growth Rate (RGR), based either on biomass production or on length/frond production, and chlorophyll fluorescence Fv/Fm, were measured. For each endpoint, the effective concentration 50% (EC50) was calculated. Almost all endpoints were affected by Cu exposure, except Fv/Fm of M. spicatum, and resulted in significant differences among genotypes for Cu sensitivity. Genotypes of L. minor exhibited up to 35% of variation in EC50 values based on Fv/Fm, showing differential sensivity among genotypes. Significant differences in EC50 values were found for RGR based on length for M. spicatum, with up to 72% of variation. Finally, C. demersum demonstrated significant sensitivity differences among genotypes with up to 78% variation for EC50 based on length. Overall, interspecific variation was higher than intraspecific variation, and explained 77% of the variation found among genotypes for RGR based on biomass, and 99% of the variation found for Fv/Fm. Our results highlight that depending on the endpoint, sensitivity can vary greatly within a species, and that pollutant- and species-specific endpoints should be considered in ERA.

Turbulence‐mediated facilitation of resource uptake in patchy stream macrophytes

AbstractMany landscapes are characterized by a patchy, rather than homogeneous, distribution of vegetation. Often this patchiness is composed of single‐species patches with contrasting traits, interacting with each other. To date, it is unknown whether patches of different species affect each other's uptake of resources by altering hydrodynamic conditions, and how this depends on their spatial patch configuration. Patches of two contrasting aquatic macrophyte species (i.e., dense canopy‐forming Callitriche and sparse canopy‐forming Groenlandia) were grown together in a racetrack flume and placed in different patch configurations. We measured 15NH4+ uptake rates and hydrodynamic properties along the centerline and the lateral edge of both patches. When the species with a taller, denser canopy (Callitriche) was located upstream of the shorter, sparser species (Groenlandia), it generated turbulence in its wake that enhanced nutrient uptake for the sparser Groenlandia. At the same time, Callitriche benefited from being located at a leading edge where it was exposed to higher mean velocity, as its canopy was too dense for turbulence to penetrate from upstream. Consistent with this, we found that ammonium uptake rates depended on turbulence level for the sparse Groenlandia and on mean flow velocity for the dense Callitriche, but Total Kinetic Energy was the best descriptor of uptake rates for both species. By influencing turbulence, macrophyte species interact with each other through facilitation of resource uptake. Hence, heterogeneity due to multispecific spatial patchiness has crucial implications for both species interactions and aquatic ecosystem functions, such as nitrogen retention.

Plant root and rhizome strength: Are there differences between and within species and rivers?

AbstractThe strength and architecture of roots and other below‐ground organs of riparian and aquatic plants affect plant resistance to uprooting and contribute to reinforcing river bank, bar and bed materials. Therefore, root properties are an important element in models for estimating river bank stability and such models may focus on the role of plants by using root strength–diameter relationships for the particular plant species that are present.Here we explore the degree to which there appear to be significant differences in strength–diameter relationships between and within species‐specific data sets obtained for two riparian tree/shrub (Populus nigra, Salix alba) and two emergent aquatic macrophyte (Sparganium erectum, Phalaris arundinacea) species in different European river environments.While the analysed data sets were not specifically collected to answer these research questions, the results are sufficiently compelling to make the case for the collection of a more comprehensive data set and its rigorous analysis. This would allow recommendations to be made on the degree to which (i) species‐specific or more general relationships between root/rhizome strength and diameter are appropriate, (ii) such relationships are applicable within and between rivers in different geographical regions and subject to different local environmental conditions, and (iii) further (minimalist) field observations are needed to calibrate such relationships for investigations of new locales or species. © 2018 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.