Aquatic Macrophyte Species Research Articles

Growth of Two Aquatic Macrophyte Species in Artificial Floating Islands in an Ohio Wetland: Potential for Nutrient Sequestration

Growth of Two Aquatic Macrophyte Species in Artificial Floating Islands in an Ohio Wetland: Potential for Nutrient Sequestration

Heavy Metals Assimilation by Native and Non-Native Aquatic Macrophyte Species: A Case Study of a River in the Eastern Cape Province of South Africa

There is continuous deterioration of freshwater systems globally due to excessive anthropogenic inputs, which severely affect important socio-economic and ecological services. We investigated the water and sediment quality at 10 sites along the severely modified Swartkops River system in the Eastern Cape Province of South Africa and then quantified the phytoremediation potential by native and non-native macrophyte species over a period of 6 months. We hypothesized that the presence of semi and permanent native and non-native macrophytes mats would reduce water and sediment contamination through assimilation downriver. Our results were variable and, thus, inconsistent with our hypotheses; there were no clear trends in water and sediment quality improvement along the Swartkops River. Although variable, the free-floating non-native macrophyte, Pontederia (=Eichhornia) crassipes recorded the highest assimilation potential of heavy metals in water (e.g., Fe and Cu) and sediments (e.g., Fe and Zn), followed by a submerged native macrophyte, Stuckenia pectinatus, and three native emergent species, Typha capensis, Cyperus sexangularis, and Phragmites australis. Pollution indices clearly showed the promising assimilation by native and non-native macrophytes species; however, the Swartkops River was heavily influenced by multiple non-point sources along the system, compromising the assimilation effect. Furthermore, we emphasise that excessive anthropogenic inputs compromise the system’s ability to assimilate heavy metals inputs leading to water quality deterioration.

Functional macrophyte trait variation as a response to the source of inorganic carbon acquisition.

BackgroundThis study aims to compare variation in a range of aquatic macrophyte species leaf traits into three carbon acquisition groups: HCO3−, free CO2 and atmospheric CO2.MethodsThe leaf functional traits were measured for 30 species from 30 softwater lakes. Macrophyte species were classified into (1) free CO2, (2) atmospheric CO2 and (3) bicarbonate HCO3− groups. In each lake we collected water samples and measured eight environmental variables: depth, Secchi depth, photosynthetically active radiation (PAR), pH of water, conductivity, calcium concentration, total nitrogen and total phosphorus. In this study we applied the RLQ analysis to investigate the relationships between species functional traits (Q) and their relationship with environmental variables (R) constrained by species abundance (L).ResultsThe results showed that: (1) Aquatic macrophytes exhibited high leaf trait variations as a response to different inorganic carbon acquisition; (2) Traits of leaves refer to the acquisition of carbon for photosynthesis and serve to maximise this process; (3) In the wide softwater habitat, macrophyte species exhibited an extreme range of leaf economic spectrum (leaf area, leaf dry weight and specific leaf area) and wide range of shape trait expressed as circularity; (4) Macrophyte leaf traits are the result of adaptation to carbon acquisition in ambient environment.

Evaluating aquatic macrophytes for removing erythromycin from contaminated water: floating or submerged?

Water contamination by antibiotics is an emerging global problem, with impacts on both public health and the environment. Erythromycin has been encountered in bodies of water throughout the world, which demands the development of efficient remediation technologies. We investigated the physiological responses and phytoremediation capacity of four species of aquatic macrophytes, two floating (Salvinia molesta and Lemna minor) and two submerged (Myriophyllum aquaticum and Rotala rotundifolia). The plants were exposed to relevant environmental concentrations of erythromycin (0 and 1.7 µg l−1) in artificially contaminated water for seven days. Physiological evaluations evidenced the ability of that antibiotic to promote oxidative events in those plants, such as the activation of antioxidant enzymes (ascorbate peroxidase and/or catalase). S. molesta exposed to erythromycin demonstrated accumulations of hydrogen peroxide and oxidative damage (lipid peroxidation) that was reflected in growth reductions. The erythromycin removal efficiency of floating plants varied from 9 to 12%, while submerged species varied from 31 to 44%. As such, submerged macrophyte species demonstrated the most efficient removal of erythromycin from contaminated waters, and are therefore more indicated for antibiotic phytoremediation projects.

Contaminant metal concentrations in three species of aquatic macrophytes from the Coeur d'Alene Lake basin, USA.

The Coeur d'Alene Lake basin in Northwestern USA has extensive contamination from legacy mining waste, which overlaps with aquatic macrophyte habitat. We examined concentrations of arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) in three macrophytes: Elodea canadensis (submerged), Myriophyllum spicatum (submerged), and Sagittaria latifolia (emergent). We collected macrophyte tissues from five contaminated sites and one uncontaminated site. Tissue concentrations were compared to sediment quality guidelines to assess potential toxicity from metal(loid)s to macrophyte-associated biota. We used threshold and probable effect concentrations to screen for potential toxicity. For the submerged species, the highest site means ± SD (analyte mg/kg dry mass) were 96 ± 61 (As), 18 ± 1.7 (Cd), 24 ± 15 (Cu), 610 ± 392 (Pb), and 1425 ± 222 (Zn). For contaminated sites, the probable effect threshold was exceeded in 38% (As), 45% (Cd), 0% (Cu), 74% (Pb), and 67% (Zn) of submerged species concentrations. Metal concentrations in S. latifolia tubers were lower than the submerged species leaves and shoots. Tuber concentrations did not exceed the probable effect threshold for any metal. Spatial differences in concentrations were most distinct for the submerged species. Our work shows significant amounts of metals are accumulating in some macrophytes of the study area and that biota associated with this vegetation may experience toxicity based upon guideline exceedances. Additionally, managers of invasive plants (e.g., M. spicatum) should consider the ramifications of control efforts given the high metal content of some plants (e.g., disposal issue).

Distribution and diversity of aquatic macrophytes and the assessment of physico-chemical parameters of Dakatia beel in Khulna district, Bangladesh

The physico-chemical characteristics of water and aquatic macrophytes from Dakatia Beel under Khulna district in Bangladesh were studied within January, 2020 to February, 2021. Twenty three species of aquatic macrophytes belonging to 15 families have been recorded. The aquatic macrophytes in Dakatia Beel collected from several sites belonging to 23 genera and 15 families (Lemnaceae, Pontederiaceae, Araceae, Convolvulaceae, Amaranthaceae, Asteraceae, Fabaceae, Polygonaceae, Ceratophyllaceae, Onagraceae, Parkeriaceae, Cyperaceae, Poaceae, Euphorbiacee, Nymphaceae). We also observed the different plant groups which comprises 6 species of floating, 10 species of emergent and only 2 species of submerged aquatic macrophytes. Dissolved oxygen ranged between 1.78 to 2.2 mg/L with a mean value 1.95 mg/L. The study area showed maximum total dissolved solid 588 ppm and the minimum in 482 ppm with a mean value of 534 ppm. Maximum value of phosphate was noted in 1029 μg/L and minimum 988 μg/L with a mean value of 1005 μg/L. Asian J. Med. Biol. Res. 2021, 7 (2), 118-125

Unravelling the effects of multiple types of disturbance on an aquatic plant metacommunity in freshwater lakes

Abstract Lakes and ponds experience numerous forms of disturbance, including land use (anthropogenic), invasive species (biotic), and eutrophication (abiotic). Although these disturbances act independently or synergistically to affect native species composition, their effects generally are not considered simultaneously, thereby failing to account for appreciable variation or inaccurately attributing joint effects to a single type of disturbance. We assessed defining characteristics (coherence, turnover, and boundary clumping) of a metacommunity of 67 native aquatic macrophyte species that inhabit 104 lakes to determine the extent to which species respond to the same latent environmental gradient and the association of that gradient with multiple interrelated types of disturbance. Species generally responded to the same latent environmental gradient, with their distributions replacing one another along that gradient, resulting in a compartmentalised structure (i.e. Clementsian pattern). The latent environmental gradient was associated with disturbance; different functional or phylogenetic groups of species were associated with high or low levels of disturbance. We used variation partitioning to evaluate whether spatial or environmental attributes were more important in driving variation among lakes along the latent environmental gradient. We accounted for 78.7% of variation among lakes in species composition of native aquatic plants, with 10.0% due to unique attributes of space, 16.4% due to unique attributes of environment, and 52.2% due to spatially structured environmental attributes, highlighting the importance of species sorting. We separated environmental attributes into three subcategories: abiotic (water quality), biotic (invasive species), and anthropogenic (land use). We used variation partitioning on the three environmental subcategories and on spatial attributes to disentangle their independent and joint effects. We then used hierarchical partitioning to unravel the independent and joint effects of each attribute within each subcategory. Abiotic (water quality), biotic (invasive species), and anthropogenic (land use) disturbances each had significant total effects that are highly conflated with each other. Importantly, each subcategory of disturbance had significant unique effects on native aquatic plant composition. By using spatial characteristics as well as abiotic, biotic, and anthropogenic attributes that are related to disturbance, we accounted for most of the variability in species composition among lakes. Of particular importance, invasive species independently, and interactively with other environmental characteristics, affected the metacommunity structure of native species. The emergent compartmentalised structure (Clementsian) of native species in the metacommunity arises because of species‐specific differences in response to a disturbance gradient, resulting in species with distinctive functional characteristics and phylogenetic histories at different ends of a disturbance gradient. ​

Exponential decay: an approach to model nutrient uptake rates of macrophytes

One of the challenges of integrating phytoremediation into a waste treatment system is the sensitivity of plant species to fluctuations in environmental conditions and the difficulty in estimating subsequent changes to their rates of uptake. In this study, we examine a method using the exponential decay equation to approximate the median uptake rate (MUR) of nutrients for three aquatic macrophyte species, Salvinia molesta, Spirodela polyrhiza, and Lemna minor. These MUR values were then used to directly evaluate the phytoremediation performance between species and at varying levels of salinity stress. The results of this study indicate that an exponential decay relationship produced the most accurate models of the nutrient uptake profile for each species, with highest correlation values in 74.1% of tests for the three species at increasing salinity over a period of 14 d. S. polyrhiza and L. minor began to show significant reductions in nutrient uptake and growth at salinity concentration above 10 g/L. Using MUR, direct comparisons can be made between species in a time and mass-independent manner, allowing for the rapid assessment of phytoremediation performance under conditions of increasing salinity stress. Novelty statement In this study, we propose the use of an exponential decay model and the use of median uptake rate (MUR) obtained from the model coefficients as a method for directly comparing species performance under different conditions. Subsequently, we show how the use of MUR values obtained from three species of aquatic macrophytes allows for the direct comparison of species performance under increasing salinity stress. The method proposed in this study would improve the ability for easy comparison between species performance under varying environmental conditions. Future works could further build on the parameters proposed in this study and optimize the performance of phytoremediation systems developed for nutrient-affected wastewater management. This study is especially beneficial to phytoremediation researchers and environmental engineers who are implementing or designing macrophyte phytoremediation systems.

MACROPHYTIC COMMUNITY AS BIOLOGICAL INDICATORS OF POLLUTION IN ANCHAR LAKE OF KASHMIR

The most significant biotic constituent in a lake ecosystem is represented by macrophytes in their diverse forms. Macrophytes, because of their capacity to integrate environmental changes over periods of a few years, and reflect the cumulative effects of successive disturbances, are considered excellent indicators of the ecological state of water bodies Macrophytes are by far the most investigated group used for exploring the effects of water level fluctuation on biological organisms in aquatic ecosystems . In lake ecosystems, Overall 31 species of aquatic macrophytes were reported from Anchar Lake with different morphology, which consisted of emergent (14), rooted floating leaf type (08), submerged (06) and free floating (03). The efforts mainly focus on the relationships between water level fluctuation and the presence, species richness, distribution and cover of macrophytes.

A checklist of aquatic macrophytes of the Guaraguaçu river basin reveals a target for conservation in the Atlantic rainforest

Describing and understanding distribution of species in natural ecosystems is the first step to establish conservation efforts. In aquatic habitats, macrophytes play a central role in promoting biodiversity and ecosystem functioning. This study aimed to create the first checklist of aquatic macrophyte species occurring in the Guaraguaçu river, the largest river in Paraná State coast, Brazil. Species herborized, identified and incorporated into the Herbarium collection of the Universidade Federal do Paraná. A total of 47 species were registered corresponding to 37 genera and 29 botanical families; Cyperaceae and Poaceae were the most representative families. In addition, the wide invasion of the non-native species Urochloa arrecta (Hack. ex T. Durand & Schinz) Morrone & Zuloaga was registered and the presence of the floating-leaved non-native species Nymphaea caerulea Savugny was recorded. Even so, the inventory shows a noteworthy richness of aquatic macrophytes species in the Guaraguaçu river, and it is clear macrophyte species reflect a gradient of anthropic impact and salinity in this tidal estuarine river. Our study contributes to the creation of public policies to aid in the protection of this river that represents a central site for biological conservation efforts, yet is constantly threatened by anthropic activities.

Different scales determine the occurrence of aquatic macrophyte species in a tropical stream

Distributions of aquatic macrophyte species are commonly associated with water chemistry characteristics. However, other environmental factors that can lead to the occurrence of aquatic plants in lotic ecosystems, such as dynamic habitats linked to the surrounding landscape, have been underestimated. This study aims to evaluate landscape features that may influence the occurrence of species of euhydrophyte aquatic macrophytes in a tropical river basin. We assessed the occurrence of the following seven species: Egeria densa, Cabomba furcata, Potamogeton pusillus, Potamogeton polygonus, Utricularia foliosa, Pistia stratiotes and Salvinia molesta. We also measured environmental variables related to three spatial scales, local (limnological), channel and riparian landscape, along 25.5 Km of the Itanhaém River basin (São Paulo, Brazil). We found that local (limnological) and channel characteristics were important variables in determining the occurrence of aquatic macrophyte species while the landscape scale had little influence on species composition. Channel depth and margin slope were especially relevant abiotic variables in explaining the occurrence of four of the species but not P. pusillus, P. polygonus and U. foliosa. Our results highlight the importance of channel morphology for understanding aquatic plant occurrence and community composition in tropical rivers.

Effects of the technical ingredient clomazone and its two formulated products on aquatic macrophytes.

One active ingredient can be a component of different types of formulations of pesticides, while the toxicity of its formulations may vary depending on various constituents used in the mixture. The present study focuses on evaluating the effects of the active ingredient clomazone and its formulations (Rampa® EC and GAT Cenit 36 CS, both containing 360g a.i./l of clomazone) on non-target aquatic macrophytes. The two formulation types differ in their active ingredient release and presumed environmental impact. In order to cover different ecological traits, two species of aquatic macrophytes - the floating monocot Lemna minor and the rooted dicot Myriophyllum aquaticum, were used as test models. The results of this study revealed differences in the sensitivity of tested plants to clomazone. Based on the most sensitive parameters, M.aquaticum proved to be more sensitive than L.minor to the technical ingredient and both formulations. The species sensitivity distribution (SSD) approach that was tried out in an attempt to create a higher tier step of risk assessment of clomazone for primary producers indicates that tests on rooted macrophytes can add value in risk assessment of plant protection products. The capsule formulation of clomazone was less toxic than the emulsion for L.minor, but more toxic for M.aquaticum. The most toxic for L.minor was the emulsifiable concentrate formulation Rampa® EC, followed by technical clomazone (EC50 33.3 and 54.0mg a.i./l, respectively), while the aqueous capsule suspension formulation GAT Cenit 36 CS did not cause adverse effects. On the other hand, the most toxic for M.aquaticum was the formulation GAT Cenit 36 CS, followed by technical clomazone and the formulation Rampa® EC, demonstrating a greater effect of the capsule formulation.

Heterogeneity of macrophyte banks affects the structure of fish communities in flooded habitats of the Amazon Basin

In freshwater ecosystems, macrophyte contribute to habitat heterogeneity with their varying structural forms, ranging from free submerged to rooted species. Macrophytes provide substrates that support fish populations, providing food and refuge from predators, especially in semi-lentic environments, like river floodplains, which tend to provide little shelter for small fish. We investigated how the species richness, abundance, and morphological traits of the fish communities of river floodplains in the Amazon region are affected by the heterogeneity of macrophyte beds, based on the relative contribution of each plant species present in these beds. Simple linear regressions were used to investigate the relationship between macrophyte bed heterogeneity and fish species richness, abundance, and morphological traits, evaluated using a community-weighted mean index analysis (CWM). We recorded 16 aquatic macrophyte species and 21 fish species at 34 study sites. Eichhornia azurea and Eichhornia crassipes dominated the macrophyte beds, while the most abundant fish species were Hemigrammus ocellifer and Laimosemion strigatus. The results of the linear regressions of the heterogeneity of the macrophyte beds were only significant for two morphological traits, both linked to fish locomotion. Our results indicate that the heterogeneity of the macrophyte beds acts an environmental filter for the fish species with a high degree of maneuverability, given that these species are able to swim within the macrophyte structures. Although this does not affect the richness and abundance of the fish, the macrophyte beds favor certain species that use this vegetation during the different stages of their life cycle, which present distinct adaptations. The heterogeneity provided by the aquatic macrophytes is thus important to a range of different fish species, by providing shelter and protection for the smaller species with morphological traits that permit their survival in this environment.

The Effects and Level of Catalase Enzyme Activity in Different Species of Aquatic Macrophytes and Their Families in Two Different Locations in Niger Delta, (Ikpoba River in Benin-City and Ethiope River in Abraka), Nigeria

This study was carried out to analyze the levels of oxygen evolved in catalase activity during hydrogen peroxide decomposition reaction in species of different aquatic macrophytes and their selected families, Pontederiaceae, Araceae, Lemnaceae, Ceratophyllaceae, Azollaceae, Nymphaeaceae in two different Rivers in Delta and Edo State. Hydrogen peroxide is formed as a toxic waste product of metabolism which is quickly converted into other less dangerous chemicals. It is an important signal molecule involved in plant development and environmental responses. The enzyme catalase is frequently used to rapidly catalyze the decomposition of hydrogen peroxide into a harmless molecule of oxygen and water. Anthropogenic activities of excess nitrogen and phosphorus nutrient enrichment into water body proliferation result in eutrophication, which most species of aquatic microphytes can use to control them. The catalase levels in species of Eichhornia crassipes followed by Eichhornia natans in Pontederiacea family recorded the highest in their leaves (24.83 ± 0.29) in Ethiope River and (24.20 ± 0.10) in Ikpoba River respectively among the aquatic macrophytes studied. Those species under the family Nymphaeaceae had (23.73 ± 0.64) as in water lily in their leave tissues in Ethiope River, followed by the family Ceratophyllaceae which had (20.33 ± 0.58) in Ikpoba River, Edo State. The lowest catalase activity was recorded in the roots of Azolla africana and Nymphaea lotus (12.00 ± 0.05) and (12.30 ± 0.10) in Ethiope and Ikpoba River. Catalase enzymes present in these species of aquatic macrophytes are useful in commercial cleaning operations in bioremediation for aquatic and terrestrial ecosystems.

Temperature influences swine wastewater treatment by aquatic plants

Studies show that aquatic plants are an efficient alternative to minimize the harmful effects of wastewater. Two species of aquatic macrophytes (Pistia stratiotes and Eichhornia crassipes) were chosen to evaluate the temperature effect on the performance of these macrophytes species in a post-treatment system of swine wastewater. The experiment was carried out in the municipality of Toledo, Paraná State, Brazil. For the experimental system, 24 concrete tanks with 80 L capacity were used, each measuring approximately 1.5 m in length, 0.25 m in width and 0.16 m deep. Wastewater characteristics and variables hydrogen potential (pH), electrical conductivity (EC), and dissolved oxygen (DO) were measured weekly. After, we analyzed the aquatic macrophytes and centesimal composition. The use of aquatic macrophytes was efficient for final swine wastewater polishing. Nitrogen removal showed higher efficiency in the summer period for both species studied. The abiotic variables (pH and EC) presented better results during the winter for both species evaluated. Air and wastewater low temperatures did not influence these variables. Dissolved oxygen presented better results in the summer period for E. crassipes species. There was a significant increase in N and P contents in the plant tissue. This fact proves that the use of aquatic macrophytes is an interesting alternative for swine wastewater treatment.

Species Diversity of selected Flora and Fauna in the river Yamuna at Kalpi (U.P.) India

To evaluate the pollution status species diversity of selected flora and fauna of the Yamuna river at Kalpi stretch was studied for a period of one year. Four sampling stations were selected for sampling purpose. Collected samples are evaluated for flora and fauna specially phytoplankton, aquatic macrophytes, zooplankton and fishes. Selected flora and fauna of studied water are presented by phytoplankton members of Chlorophyceae, Euglenophyceae, Bacillariophyceae and Cyanophyceae, aquatic macrophytes of 8 families, zooplankton members of Protozoa, Rotifera, Cladocera and Copepoda and fishes of 10 families. In these recorded species of different groups of flora and fauna, some pollution indicator species like Scenedesmus quadricauda, Stigeoclonium tenue,Ankistrodesmus falcatus, Chlorella vulgaris, Euglena viridis, Synedra ulna, Cyclotella meneghiniana, Navicula viridula, Nitzschia, Oscillatoria limosa, O. tenuis, O. chlorina, Phormidium uncinatum,Microcystis aeruginosa of phytoplanton, Eichhornea, Potamogeton and Cyperus species of aquatic macrophytes, Brachionus species and Keratella species of zooplankton and Clarias batrachus fish are also presented along with clean water species. Presence of both pollution indicator and clean water species show that water of Yamuna river at Kalpi stretch is moderately polluted. Sustaining the diversity of flora and fauna it is necessary to maintain living status of this river.

Physiological Effects of Exposure to Copper and Chromium in Three Floating Aquatic Macrophyte Species

The ability of plants to resist heavy metals is associated with the development of different ecotypes and intracellular strategies capable of dealing with the prevention, tolerance, and detoxification of heavy metal stress. This study aimed to present the physiological effects of exposure to copper and chromium in Eichhornia crassipes, Salvinia biloba, and Pistia stratiotes by measuring the activity of phytochelatins and glutathione, and oxidation-reducing enzymes (catalase, ascorbate peroxidase, and guaiacol peroxidase) and levels of chlorophyll. The experiment consisted of the exposure of 50 individuals of each species to a solution of chromium III at 150 ppm and copper II at 150 ppm, for 48 h. Chemical analysis of the metals was performed with inductively coupled plasma atomic emission spectrometry; catalase, ascorbate peroxidase, and guaiacol peroxidase and chlorophyll levels were analyzed by colorimetric method in spectrophotometry, and glutathione and phytochelatins by hyphen liquid chromatography. The changes observed in the concentrations of glutathione and phytochelatins highlight that the ascorbate glutathione cycle was activated together with the defense mechanism of the enzymes: catalase, ascorbate peroxidase, and guaiacol peroxidase. Observing the behavior of metal accumulation, and enzymes associated with the activity of the enzymes, it can be said that Eichhornia crassipes has a very efficient defense system, which makes it more resistant to copper, and an accumulator of chromium in the roots; Salvinia biloba and Pistia stratiotes accumulated and transported the two metals from the roots to the leaves; however, they had no defense mechanism and entered senescence in the last hours of the experiment.

Macrophytes as indicators of the ecological status of a tropical rehabilitated wetland ecosystem: Application of multivariate statistics and Ecological State Macrophyte Index (ESMI)

The present study used the Ecological State Macrophyte Index (ESMI) and the multivariate statistical methods to assess the ecological status and the variation of macrophytes in a tropical wetland system. Six sites were selected from rehabilitated and non-rehabilitated areas of an urban tropical wetland and the water quality parameters (water pH, temperature, conductivity, total dissolved solids (TDS), dissolved oxygen (DO), visibility, biological oxygen demand 5 days after incubation (BOD 5 ), chemical oxygen demand (COD), nitrate, chlorophyll-a and total phosphorus concentrations), sediment quality parameters (pH, organic matter content, percentage sand, silt and clay content) and abundance of aquatic macrophytes were measured. Shannon Weiner diversity index, percentage vegetation under anthropo-pressure, macrophyte settlement rate and ESMI were calculated. Significant variations in the water and sediment quality parameters were observed and ten species of aquatic macrophytes were recorded. Salvinia melosta and Cypreus iria were recorded only from the non-rehabilitated sites. Although there was no significant difference in the percentage anthropo-pressure among study sites, the rehabilitated sites were displayed low anthropo-pressure. The sites in the non-rehabilitated area showed a significantly lower macrophyte settlement rate. ESMI and macrophyte abundance showed significant correlations with water quality parameters. Based on the results, it can be recommended that applications based on ESMI and multivariate statistics can be used to assess the ecological status of tropical wetlands.

Urban ecosystems as locations of distribution of alien aquatic plants

Abstract Peculiarities of alien macrophytes invasions into aquatic ecosystems located at urban landscapes were investigated on an example of water bodies, rivers and streams located within the Kyiv City (Ukraine). There have been recognised seven species of alien aquatic macrophytes established at the territory of Kyiv City, representing 11% of the hydrophilic flora of the city. The representatives of the recent invasions Egeria densa, Elodea nuttallii and Pistia stratiotes in comparison with Elodea canadensis were characterized by a wider ecological valence concerning the contents of nitrogen compounds in water. Significant variability of morphometric parameters of coenopopulations of alien species formed in different environmental conditions was recognised. There was observed that the individuals of Pistia stratiotes from eutrophic water bodies formed significantly larger surface organs, and the individuals from meso-eutrophic reservoir had a larger number of leaves in the rosette, and more numerous and longer roots. The alien macrophytes species dwelling in the water bodies of the city were characterized by wide ecological amplitudes, high stress tolerance, high reproduction rate, high naturalization degree, allowing these species to use the resources of their new environment inaccessible for the local species and significantly affecting the ecosystem homeostasis and transformation.

Association Between the Distributions and Chemical Composition of Aquatic Macrophytes and Bacterial Community Structure in Some Irrigation Canals (Rayahs) of the Nile River, Egypt

Variations in distribution, species composition, and chemical constituents of aquatic macrophytes of Al-Rayah El Tawfiky (T) and Al-Rayah El Monoufy (M) in addition to their relations with bacterial communities structure and water variables were studied over the period from spring 2014 to winter 2015. Ten of the aquatic macrophytes species related to 7 families and 9 genera were recorded. Myriophyllum spicatum was the most dominant species, the autumn season and Al-Rayah (M) were the richest in species numbers. Protein, lipid, nitrogen, phosphorus, and potassium were detected at higher concentrations in Ceratophyllum demersum from Al-Rayah (T), however organic matter and nitrogen-free extracts contents attended their highest values in Potamogeton nodosus from Al-Rayah (M). Microbial analyses indicated the presence of total bacterial counts and the total diazotrophs in high population densities (Up to 105). However, total and fecal coliforms populations are exceeding the permissible limits cited by World Health Organization, recorded their highest numbers in spring at the site of Al Rayah (M) which was occupied by Potamogeton nodose and Myriophyllum spicatum. A significant difference in chemical composition, distribution pattern, the community structure of aquatic macrophytes, and bacteria attributed to the seasons and site differences, in addition to the nutritional potential of the analyzed macrophytes species especially submerged ones were recorded.