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Abstract\nNOVELTY STATEMENTFloating treatment wetlands (FTWs) are natural solutions for purifying polluted water, providing a green surface area and improving city landscape. This study investigated if the efficiency of FTWs can be improved by aeration for treating contaminated canal water. The three used plant species were Canna generalis, Phragmites australis, and Cyperus alternifolius. The experiment was carried out in three FTWs with aeration and three without aeration to compare the removal for COD, NH4+-N, E. coli, PO43−-P, and Fe. In the aerated FTWs, air blowers were installed to run at two different air flow rates of 2.5 L min−1 (Batch 1) and 1.0 L min−1 (Batch 2). Aeration increased the dissolved oxygen concentrations in each tank, which came over 6.5 mg L−1 in both batches. This study sheds light on the positive impact of aeration has on COD and NH4+-N removal: these are nearly three-fold higher compared to non-aeration conditions and reached approximately 99% (1.7-log reduction) for E. coli removal. Additionally, the plant growth rate in the aerated FTWs was higher than in the non-aerated ones. The average shoot growth rate of Phragmites australis was 0.76 cm d−1 for the aerated FTW which was two-fold higher compared to the non-aerated one.This article investigates the treatment performance of Floating Treatment Wetlands (FTWs) coupled with aeration to reduce the diffuse pollution in canal water. The results showed that the aeration enhanced the treatment of organics and nutrients, and the plant growth of the aerated FTWs was two-fold higher than that of non-aerated FTWs, which has a phytoremediation potential for treating canal water in Ho Chi Minh city [ABSTRACT FROM AUTHOR]

Floodplains are heterogeneous systems adjacent to large rivers periodically flooded by water originating from the river's lateral flow. During floods, the water flows into the surrounding channels, ponds and lakes, creating an integrated dynamic system characterized by a mosaic of lotic and lentic habitats and by the exchange of nutrients and inhabiting organisms between the main river and its floodplain. This study included a total of 14 sampling sites in a floodplain of the Danube River, designated as a Ramsar site. Seven study sites were in near natural condition, while seven others were separated from the Danube floodplain by an embankment and thus were anthropogenically disturbed (e.g. by hydro–morphological alterations and pollution from agricultural fields). Odonata nymphs were sampled over a two–year period in each season using a benthos hand net. A total of 20 Odonata species were recorded. Some of the documented species are of national and/or international conservation concern, which confirms the conservation value of the habitats studied. Species richness, abundance, taxonomic and functional diversity of Odonata were significantly higher at the anthropogenically disturbed sites than at the near natural sites within the studied floodplain area and correlated positively with macrophyte assemblage metrics (species richness, abundance, diversity). The macrophyte assemblage metrics, water transparency, copper and nitrate concentrations and oxygen saturation in the water were key environmental factors shaping Odonata assemblages in the studied floodplain. As Odonata are used as bioindicators of freshwater status worldwide, the presented results could be used in the protection of endangered wetland ecosystems and their biota. The importance of aquatic macrophytes for the conservation of the local Odonata diversity should be considered in the management of anthropogenically disturbed habitats in protected areas. [ABSTRACT FROM AUTHOR]

When facing new climate extremes, aquatic plant communities may experience more frequent or increasing durations of water shortages. Aquatic macrophytes of permanently inundated habitats (true hydrophytes) may lack the physiological or morphological characteristics that protect terrestrial plants from drying out. Aquatic hydrophytes with floating or emergent leaves are expected to be more resilient to droughts than completely submerged plants, as they have morphological characteristics adapted to air-exposed conditions. Therefore, we expected the latter to survive longer periods of air exposure and perform better with increasing drought than a completely submerged growing species. Here, we conducted a microcosm experiment and exposed two Potamogeton species—the completely submerged growing Potamogeton perfoliatus and the areal leaf producing Potamogeton nodosus—to different drought conditions (1, 5, and 15 days). We aimed to detect how two species with different growth strategies cope with and respond to increasing air exposures with waterlogged sediment. Both species showed a resistance to 1–5 days of drought but showed high mortality after 15 days. They displayed significant differences in all measured morphological responses (shoot length, side shoot, and leaf counts), plant chemistry (carbon, nitrogen, and phosphate), and the produced biomass (shoot, root, leaves), and reacted significantly to increasing drought durations. Differences in their resistance were observed based on the mortality rate and morphological responses. To prevent long-term droughts and keep mortality low, we recommend to the water managers to identify areas of risk and increase water levels during dry periods. [ABSTRACT FROM AUTHOR]

Lead (Pb) can be deposited in aquatic environments that are especially subject to pollution due to wastewater and sewage disposal. This study aimed to evaluate the tolerance of Echinodorus grandiflorus (Cham. & Schltr.) Micheli to Pb and changes in growth, gas exchange, and leaf anatomy. Experiments were conducted with E. grandiflorus plants exposed to the following Pb concentrations in nutrient solution: [0; 0.75; 1.5; 3.0 and 9.0 μM Pb (NO 3)2] in a greenhouse for 60 days. At the end of the experiment, the lead concentration, growth, leaf gas exchange, and changes in leaf anatomy were evaluated. There was no mortality of E. grandiflorus plants, and they accumulated higher concentrations of Pb proportional to the concentration of the pollutant in the solution. Pb did not cause significant changes in growth, stomatal conductance, transpiration, and Ci/Ca rate but reduced the photosynthesis in E. grandiflorus. The leaf anatomy showed significant changes in the presence of Pb, reducing the epidermis and chlorophyll parenchyma. E. grandiflorus demonstrated tolerance to Pb, surviving and growing under contamination; however, it negatively modified its leaf anatomy and photosynthesis in the presence of the metal. [ABSTRACT FROM AUTHOR]

Watercress (Nasturtium officinale) has spread widely from Europe and commonly occurs in Oklahoma (USA) springs. Watercress is usually an emergent plant and affects water flow patterns and may provide habitat for biota. Although watercress is not considered an invasive species, its impacts in springs have not been reported. With a goal to describe possible impacts of watercress in springs, 14 karst-associated springs (12 with watercress) were surveyed for sediment characteristics, macroinvertebrates, and diatoms in July 2021. The effects of watercress were evident. Sediment particle size was unaffected by the presence of watercress but sediment organic matter was higher under watercress beds than outside of beds. Although there was no difference in total benthic macroinvertebrate density or richness, higher organic matter was associated with slightly higher abundances of detritivorous and predatory macroinvertebrates (SIMPER). Submerged portions of watercress had significantly much lower diatom density than other spring substrates, with diatom composition similar to other plants but different from that of rocks. Self-shading or possible allelopathy may cause the low diatom density. The significantly lower macroinvertebrate density within watercress mats relative to that of other plants may result from a reduced food source because the plant's low diatom density. Only predatory damselflies were more common in watercress than in other plants, which had more abundant grazers. Although watercress can increase heterogeneity in sediments and is sometimes valued as an edible plant, watercress supports low algal and macroinvertebrate densities, such that extensive growth of watercress can have an overall negative impact on spring ecosystems. [ABSTRACT FROM AUTHOR]

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Sugarcane vinasse is a byproduct of the ethanol industry that has been associated with environmental impacts, including ecotoxicity. However, several nature-based alternatives have been studied to attenuate environmental pollution, including phytoremediation. In such a scenario, this research aimed to evaluate the phytotoxicity of vinasse to aquatic plants, assessing the tolerance of three free-floating aquatic macrophytes, namely Eichhornia crassipes, Pistia stratiotes, and Salvinia auriculata. Five vinasse proportions (up to 20%) were considered to assess the short-term growth of aquatic plants. P. stratiotes and S. auriculata were more sensitive to vinasse than E. crassipes, which showed resistance at 10 and 20%. Lower dilutions were non-toxic and even stimulated the growth of macrophytes, which might contribute to the uptake of nutrients and potentially toxic elements. The selection of tolerant species contributes to the application of phytotechnologies, and the studied plants might have potential for the phytoremediation of vinasse. HIGHLIGHTS Investigating nature-based solutions like phytoremediation can help address sugarcane vinasse pollution.; Low proportions of vinasse had effects on short-term plant growth, including growth stimulation.; High proportions of vinasse inhibit the growth of aquatic plants and limit their application for phytoremediation.; Eichhornia crassipes was the most tolerant species, even up to 20% of vinasse.;

The glass manufacturing industry produces hazardous effluent that is difficult to manage and causes numerous environmental problems when disposed of in the open. In this study, an attempt was made to study the phytoremediation feasibility of water lettuce (Pistia stratiotes L.), a free-floating aquatic macrophyte, for the removal of six heavy metals from glass industry effluent (GIE) at varying concentrations (0, 25, 50, 75, and 100%). After a 40-day experiment, the results showed that 25% GIE dilution showed maximum removal of heavy metals i.e., Cu (91.74%), Cr (95.29%), Fe (86.47%), Mn (92.95%), Pb (87.10%), and Zn (91.34%), respectively. The bioaccumulation, translocation, and Pearson correlation studies showed that the amount of heavy metals absorbed by vegetative parts of P. stratiotes was significantly correlated with concentrations. The highest biomass production, chlorophyll content, relative growth rate, and biomass productivity were also noted in the 25% GIE treatment. Moreover, the multiple linear regression models developed for the prediction of heavy metal uptake by P. stratiotes also showed good performance in determining the impact of GIE properties. The models showed a high coefficient of determination (R2 > 0.99), low mean average normalizing error (MANE = 0.01), and high model efficiency (ME > 0.99) supporting the robustness of the developed equations. This study outlined an efficient method for the biological treatment of GIE using P. stratiotes to reduce risks associated with its unsafe disposal. [ABSTRACT FROM AUTHOR]

This study investigates the distribution and conservation status of plant species in lentic wetlands of Mediterranean islands. Field data on vascular macrophytes were collected from the online national databases of the "Conservation of the island wetlands of the Mediterranean Basin" (MedIsWet). A comprehensive inventory of wetlands was conducted, and information on the main anthropogenic impacts and conservation priorities was compiled. In addition to all vascular hygro- and hydrophytes, we retained information on those species typically adapted to environments with intermittent or temporary wetness. A significant knowledge gap regarding the distribution and conservation of plant species in Mediterranean wetlands was found. A lower endemism rate was observed particularly in coastal wetlands. However, approximately 25% of species, mainly with relatively wide distribution, were identified as endangered or with unknown conservation status. Including all macrophytes adapted to seasonal wetness is crucial when considering wetland conservation efforts. The research emphasised the importance of considering diverse wetland types, including seasonal and permanent, natural and artificial, for effective plant conservation. Artificial wetlands emerged as potential habitats with considerable biodiversity conservation value. This study provides a comprehensive inventory of wetlands and valuable insights into the distribution, ecology, and conservation relevance of aquatic macrophytes in Mediterranean islands. The research enhances our understanding of biogeographic patterns and processes, offers critical information for the management and conservation of Mediterranean island wetlands, and presents a replicable approach that can be applied to other wetland contexts. [ABSTRACT FROM AUTHOR]

Aquatic macrophyte is a generic denomination for macro-algae with active photosynthetic parts that remain totally or partially submerged in fresh or salty water, in rivers and lakes. Currently, algae monitoring is carried out manually by collecting samples to send for laboratory analysis. In most cases, harmful algal blooms are already widespread when the results are disclosed. This paper proposes the application of a team of heterogeneous Unmanned Aerial Vehicles (UAVs) that cooperate to increase the system’s overall observation range and reduce the reaction time. Leader UAV, featured with a deep-learning-based vision system, covers a pre-determined region and determines high-interest inspection areas in real-time. Through a multi-robot Informative Path Planning (MIPP) approach, the leader UAV coordinates a team of customized quadcopter (named ART2) to reach points of interest, managing their route dynamically. ART2s are able to land on water, and collect and test samples in situ by applying phosphorescence sensors. While path planning, task assignment, and route management are centralized operations, each UAV is conducted by a decentralized trajectory tracking control. Simulations performed in a realistic environment implemented on the Unity platform and experimental proof of concepts demonstrated the reliability of the proposed approach. The presented multi-UAV framework with heterogeneous agents also enables the reconfiguration and expansion of specific objectives, in addition to minimizing the task completion time by executing different processes in parallel. This preventive monitoring enables a plague control action in advance, solving it faster, cheaper, and more effectively. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass is a promising raw material for energy production due to its low cost and sustainability. In this work, Egeria densa, Typha domingensis,Eichhornia crassipes, and Cyperus papyrus 'Nanus' aquatic macrophytes were evaluated as a potential to produce methane, and their biochemical transformations were investigated. All substrate produced biogas by anaerobic fermentation. The values obtained to methane yield were 170.47, 132.42, 121.90, and 180.57 mLCH4 gSV−1, respectively. The hydrolysis rate was higher using E. densa biomass. Total volatile acid concentrations were 32.56 mg L−1 (E. densa), 77.35 mg L−1 (T. domingensis), 22.8 (E. crassipes), and 12.4 mg L−1 (Cyperus papyrus 'Nanus'). The more significant microbiological activity was observed in the reactors using E. densa (RE) and T. domingensis (RT). The total and volatile solids removal order was RE > RT > Rec (E. crassipes) > RP (Cyperus papyrus 'Nanus'). So, for recovery of the bioenergy step, the E. densa biomass obtained the most promising results, and it was selected for hydrothermal pretreatment (HPT). After HPT, the biomass was more suitable for bioprocessing, increasing the carbohydrates available. There was a reduction in the crystallinity index due to the low lignin content and increased type II cellulose amorphous fraction. Also, the samples increased thermal stability (374 °C and 388 °C) and showed morphology with fibers partially disorganized. The methane yield was 4.2% higher as the time increased of the HPT. And the material became more vulnerable to attack by methanogenic microorganisms, resulting in greater energy production, with a potential of E. densa to generate methane. [ABSTRACT FROM AUTHOR]

Conventional agriculture is reliant on the application of unsustainably high rates of inorganic fertilizers with detrimental consequences on the environment. The use of invasive aquatic macrophytes as organic fertilizer for crop production represents a unique opportunity for weed control as well as to use this plant material that would typically be disposed of, as a resource instead. Therefore, the goal of the present study was to use Pistia stratiotes and Eichhornia crassipes as organic fertilizer for the growth of a high value vegetable, Capsicum annuum. Furthermore, to evaluate if Euclidean distance can be used as a tool to integrate the data collected into a single meaningful outcome. The results showed that growth on soil amended with plant material from the aquatic macrophytes resulted in improved plant height, number of leaves per plant, leaf length, stalk diameter and the number of fruits produced per plant (characterized by Medium and High OCVs). The outcome from calculation of the Euclidean distance revealed that the best treatments to achieve the desired phenotype were amendments with 100 g P. stratiotes or 400 g E. crassipes. Therefore, it was evident that the tested macrophyte weeds can be used as organic fertilizers to promote plant growth and yield in C. annuum and that assessment of the Euclidean distance is a useful tool to incorporate the findings from a range of parameters into a single summarized outcome. [ABSTRACT FROM AUTHOR]

Abstract Alismataceae is a family of aquatic or semi-aquatic plants with a wide distribution in humid areas, occurring in tropical, subtropical and temperate regions. Although Brazil accounts for 50% of the entire species diversity of this family, there are many gaps in knowledge of the species and their distribution, especially in the southern region of the country. This paper presents the study of Alismataceae species in the Biomes Pampa and Atlantic Forest of Rio Grande do Sul, highlighting taxonomic, ecological and distribution aspects. This study was based on the morphological analysis of specimens deposited in online data repositories and herbaria, as well as specimens collected in wetlands in the extreme south of Brazil. Ten taxa were registered for Rio Grande do Sul state: Echinodorus grandiflorus, E. longiscapus, E. macrophyllus, E. reptilis, E. uruguayensis, Helanthium tenellum, Hydrocleys nymphoides, Sagittaria lancifolia, S. rhombifolia and S. montevidensis. As a result of this study, an identification key for the taxa, morphological descriptions, images of the species and distribution maps are presented. Ecological and phenological data are also provided.

Abstract Aim i) is there a difference in the level of contamination in the different parts of the basin in the water, sediment and aquatic macrophytes compartments? and ii) do the three compartments respond similarly to metal contamination? Methods Samples of water, sediment and aquatic macrophytes (Salvinia auriculata Aubl., Pistia stratiotes L., Ludwigia helminthorrhiza (Mart.) H. Hara and Eichhornia crassipes (Mart.) Solms) were collected at 10 sampling sites in different stretches of a tropical hydrographic basin. We determined the metal concentrations of Fe, Pb, Ni, Zn, Mn, Cr, Cu and Cd, and to the results we applied Principal Component Analysis (PCA), separately for each compartment, to order the sampling sites. Results Fe and Mn had higher concentrations than other metals in plants and sediment. With the exception of Mn, the order of metals was similar between water and sediment. However, the PCAs ordered the sampling sites differently. Our results demonstrated that the ordering of sampling sites by metal concentrations differs among water, sediment and macrophytes. Conclusions We conclude that to evaluate the contamination of aquatic environments by metals and the effects of contamination on the food chain, it is not enough to evaluate them only in water or sediment, but also in an aquatic community.

Abstract Echinodorus is the second largest genus of the aquatic plant family Alismataceae, comprising 28 species, of which 24 occur in Brazil. This study represents the first record of Echinodorus scaber Rataj for the State of Maranhão, based on material collected in the Municipality of Brejo, eastern Maranhão. Echinodorus scaber shares morphological similarities with E. macrophyllus (Kunth) Micheli, but it can be distinguished by (I) a highly branched inflorescence, (II) scabrous peduncles and petioles covered by stellate trichomes, and (II) small flowers with reflexed petals. This new record of E. scaber contributes to a better understanding of this genus’ diversity and distribution in Maranhão and underscores the necessity to broaden collection efforts for a better comprehension of the state’s flooded zones. Comprehensive collection efforts, with a special focus on aquatic plants and in locations far from the state’s main urban center, São Luís, may result in a significant knowledge increase of the flora, especially of the genus Echinodorus, which needs a broad taxonomic study. These recommendations may result in new records, range extensions, and species descriptions, contributing to the conservation of the aquatic environments of Maranhão.

Water resources management requires comprehensive and integrated approaches that jointly consider hydrological, ecological and social factors. The assessment of lakes' environmentally minimum water level is a critical tool for the sustainable management and protection of their ecosystems. This work combines the morphological, hydrological and biological factors of a Mediterranean lake (Lake Volvi, northern Greece) to assess its environmentally minimum water level. Initially, the morphological characteristics of the lake's bottom were analyzed, with consideration given to the protection of the lake's ecosystem and to the need to meet the water requirements for economic activities. Then, a hydromorphological analysis was conducted, relying on the surface water inflows to the lake from its hydrological catchment and the lake's water level -volume relationship. In addition, the water level requirements of the biological communities of macrophytes, benthic macroinvertebrates, and fish, as revealed after samplings were taken from the lake's littoral zone, are considered. Based on the above methodologies, the environmentally minimum water level of Lake Volvi is proposed to be lowered by as much as 35.8 m from February to May and 35.3 m from June to January in order to maintain the ecological integrity of the lake and the sustainable use of its water resources. The present study establishes a foundation for informed water resource management; however, ongoing research can improve methodologies and address emerging questions, fostering advancements in sustainable water management practices. [ABSTRACT FROM AUTHOR]

Dense beds of aquatic plants are often perceived as nuisance and therefore mechanically removed, often at substantial cost. Such removal, however, may affect a range of ecosystem functions and consequently also the ecosystem services that benefit society.We studied five cases: River Otra (Norway), River Spree (Germany), Lake Kemnade (Germany), Lake Grand‐Lieu (France) and Hartbeespoort Dam (South Africa). In all, nuisance aquatic plant growth is managed, but dominant species, geographic setting and major societal uses are different. We quantified 12 final ecosystem services as flows per area and year in biophysical and monetary terms. Quantified services were food and fodder production, commercial fisheries, hunting and gathering wild products, hydropower production, drinking and irrigation water production, flood prevention, carbon sequestration, active and passive recreation and biodiversity conservation (nonuse).These services were related to aquatic plant cover via a range of ecosystem functions, and the effects were estimated of three plant removal regimes on the relative importance of the quantified ecosystem services and on the total sum of the monetary estimates (total economic value, TEV). The three removal regimes were 'maximum removal', 'current practice' and 'do nothing'.In all five cases, TEV was dominated by different forms of recreation. TEV was highest for Lake Kemnade, where visitor densities were highest. TEV was most sensitive to the different management regimes in Lake Kemnade, because a threshold in aesthetic appreciation was passed in the 'do‐nothing' regime, and in Hartbeespoort Dam, because of the effect on boating and angling. In the other cases, the different removal regimes had little effect on the estimated TEV.Synthesis and applications. Since recreation dominated the estimated societal benefits in the studied ecosystems, also where provision of hydropower, drinking water or irrigation water were relevant, effects on recreation should be a core consideration in the management of nuisance aquatic plants. Furthermore, aquatic plant management strategies will benefit from taking into account the differences in perceived nuisance among different categories of recreative users before engaging in costly removal. [ABSTRACT FROM AUTHOR]

This document is a compilation of research articles on the topic of phytoremediation, which is the use of plants to remove pollutants from the environment. The articles focus on the potential of different plant species to remediate soil and water contaminated with heavy metals and other toxic substances. They discuss the effectiveness of various plants in removing specific pollutants and highlight the role of microbial communities in supporting phytoremediation efforts. Overall, the research provides valuable insights into the potential of phytoremediation as a sustainable and environmentally friendly approach to pollution cleanup. [Extracted from the article]

Liverworts represent one of six embryophyte lineages that have a Devonian, or earlier, origin, and are, at present, represented by only Marchantia polymorpha as an established model. Ricciocarpos natans is a secondarily monoicous aquatic liverwort with a worldwide distribution, being found on all continents except Antarctica. Ricciocarpos, a monotypic genus, forms a sister relationship with Riccia, the largest genus of the Marchantiopsida (~250 species), diverging from their common ancestor in the mid-Cretaceous. R. natans is typically found on small stagnant ponds and billabongs (seasonal pools), where it assumes a typical ‘aquatic’ form with long scale keels for stabilization on the water surface. But, as water bodies dry, plants may become stranded and subsequently shift their development to assume a ‘terrestrial’ form with rhizoids anchoring the plants to the substrate. We developed R. natans as a model to address a specific biological question — what are the genomic consequences when monoicy evolves from ancestral dioicy where sex is chromosomally determined? However, R. natans possesses other attributes that makes it a model to investigate a variety of biological processes. For example, it provides a foundation to explore the evolution of sexual systems within Riccia, where it appears monoicy may have evolved many times independently. Furthermore, the worldwide distribution of R. natans postdates plate tectonic driven continent separation, and thus, provides an intriguing model for population genomics. Finally, the transition from an aquatic growth form to a terrestrial growth form is mediated by the phytohormone abscisic acid, and represents convergent evolution with a number of other aquatic embryophytes, a concept we explore further here. [ABSTRACT FROM AUTHOR]

Abstract Aerenchyma is a characteristic tissue of aquatic plants, characterized by the presence of air lacunae commonly septated by diaphragms. These are formed by one or more layers of stellate cells, which allow for the passage of gases. Most species of Eleocharis grow in wet or flooded soils and have aerenchyma in their aerial stems. However, extensive studies on this structure, which could contribute to ecological and phylogenetic studies of the group, are lacking. This work describes the structure of the diaphragm in the stem of Eleocharis species and investigates the evolution of this characteristic in the genus. Fifty-three species were analyzed under light and scanning electron microscopy. We analyzed the evolution of the characteristics by reconstructing their ancestral states based on the previously published original phylogeny. The diaphragms in Eleocharis vary mainly in the number of layers, cell shape, and cell wall thickness. The typical diaphragm of the genus is composed of three to four layers of stellate cells, with microprojections and secretory cells. The diaphragm of the group’s ancestor had practically the same characteristics as the genus’s typical diaphragm.

It is known that aquatic macrophytes are an important part of freshwater ecosystems, and that they play a different role in their structure and functioning. Their presence and distribution depends on water temperature and transparency, nutrient content, conductivity, pH, chemical composition and water circulation. Therefore, the goal of our research was to determine the influence and interrelationship of physicochemical parameters of water on the content of photosynthetic pigments in aquatic macrophytes of Lake Necik, in the Ramsar area of Bardača (Republic of Srpska). Content of total chlorophyll (a + b) during the growing season (June–October) ranged from 0.231 to 1.145 mg g−1 FW in Phragmites communis Trin. ex Steud., from 0.061 to 0.541 mg g−1 FW in Salvinia natans L. (All.), from 0.063 to 0.626 mg g−1 FW in Utricularia vulgaris L. and from 0.063 to 0.443 mg g−1 FW in Ceratophyllum demersum L. Research has shown that floating and submerged macrophytes have a lower ratio of chlorophyll a/b compared to emergent hydrophytes, which is most likely the result of stress caused by increased light intensity and temperature. Seasonal variations in the content of photosynthetic pigments indicated that the species Phragmites communis proved to be more tolerant to the stress caused by the influence of various abiotic factors, while Salvinia natans proved to be more sensitive. Spearmon’s correlation coefficient of the physicochemical parameters of water and the concentration of photosynthetic pigments of macrophytes showed a significant influence of certain abiotic factors (temperature, transparency and nutrients) on the content of pigments in the leaves of Phragmites communis, Salvinia natans, Utricularia vulgaris and Ceratophyllum demersum L.

Liverworts represent one of six embryophyte lineages that have a Devonian, or earlier, origin, and are, at present, represented by only Marchantia polymorpha as an established model. Ricciocarpos natans is a secondarily monoicous aquatic liverwort with a worldwide distribution, being found on all continents except Antarctica. Ricciocarpos, a monotypic genus, forms a sister relationship with Riccia, the largest genus of the Marchantiopsida (~250 species), diverging from their common ancestor in the mid-Cretaceous. R. natans is typically found on small stagnant ponds and billabongs (seasonal pools), where it assumes a typical ‘aquatic’ form with long scale keels for stabilization on the water surface. But, as water bodies dry, plants may become stranded and subsequently shift their development to assume a ‘terrestrial’ form with rhizoids anchoring the plants to the substrate. We developed R. natans as a model to address a specific biological question — what are the genomic consequences when monoicy evolves from ancestral dioicy where sex is chromosomally determined? However, R. natans possesses other attributes that makes it a model to investigate a variety of biological processes. For example, it provides a foundation to explore the evolution of sexual systems within Riccia, where it appears monoicy may have evolved many times independently. Furthermore, the worldwide distribution of R. natans postdates plate tectonic driven continent separation, and thus, provides an intriguing model for population genomics. Finally, the transition from an aquatic growth form to a terrestrial growth form is mediated by the phytohormone abscisic acid, and represents convergent evolution with a number of other aquatic embryophytes, a concept we explore further here.

Floodplain lakes are highly productive and biodiverse ecosystems whose food webs depend on a variety of autochthonous and allochthonous resources. Thus far, the role of attached algae, and epiphytes in particular has been understudied, although often high densities of macrophytes in these lakes may provide extensive substrate for attached algal growth. Our goal was to evaluate spatial and temporal variability in food web dynamics of three floodplain lakes permanently connected to the Usumacinta River, with emphasis on the role of epiphytes as a carbon source for upper trophic levels. To achieve this, we analyzed the physicochemical properties of water and stable isotopes of fish and invertebrate consumers and potential autochthonous (macrophytes, phytoplankton, epiphytes, epipelon) and allochthonous (terrestrial organic matter) basal resources during the rainy and dry seasons. The mixing model output highlighted the crucial role of epiphytes as the main energy pathway supporting secondary production year-round, while aquatic macrophytes were of secondary importance. The contribution of terrestrial organic matter to consumers was low, mostly limited to invertebrates, and overall increased from the rainy to the dry season, countering expectations of higher allochthony following strong seasonal flow pulses. Community-wide metrics further revealed higher trophic diversity among invertebrates as compared to fish. Our findings highlight the importance of preserving epiphytic energy pathways and macrophyte-periphyton linkages, as they provide key support to food webs of these vital fishery ecosystems. [ABSTRACT FROM AUTHOR]

The diel distribution of early juvenile fish communities from two temperate freshwater reservoirs that differed in cover of submerged aquatic vegetation was investigated. In the daytime, about 99.9% of the juvenile fish community from the plant‐rich Žlutice Reservoir was found in the nearshore belt of submerged aquatic vegetation reaching an average abundance of ~7982 inds. 1000 m−3. In contrast, in the pelagic habitat, few fish were found at day. In the plant‐poor Římov Reservoir, 98.9% of juveniles occupied the pelagic habitat during daytime and reached an average abundance of ~333 inds. 1000 m−3. Vertical distribution of fish in the pelagic habitat in both water bodies was affected by steep thermal and oxygen stratification and no individuals occurred below 6 m depth. At night, 88.8% of the juvenile fish community from the plant‐rich Žlutice Reservoir was in the pelagic habitat with an average abundance of ~1423 inds. 1000 m−3. Their diel horizontal shifts were much more pronounced compared to the community from the Římov Reservoir that reached an average nighttime pelagic abundance of ~523 inds. 1000 m−3. Only 1.1% of the juvenile fish community in the Římov Reservoir was found in the littoral during the daytime and 0.7% at night reaching an average daytime abundance of ~1688 inds. 1000 m−3 and average nighttime time abundance of ~1664 inds. 1000 m−3. This study indicates that if a well‐developed littoral zone with abundant aquatic vegetation is present, early juvenile fish will perform diel horizontal movement in temperate stratified reservoirs. [ABSTRACT FROM AUTHOR]

Vegetation has been shown to be a dominant factor that affects flow capacity and flow conditions. Most empirical studies of the effects of plants on flow have been conducted in artificial channels, using plastic leaves or rigid cylindrical materials, and they have focused on hydraulic effects. Relatively few studies have examined plant-induced flow resistance in open channels, the morphological adaptation of plants to flow conditions, or differences in plant responses to competitive environments. In this study, the native species Hygrophila genus were chosen as planting materials to investigate the effects of inter-specific competition and compare responses to flow resistance between two aquatic macrophytes at different flow rates. It was found that the average number of green leaves, leaf area, ratio of vascular bundle area to cross-section area, plant height and root length of Hygrophila pogonocalyx were higher than those of the Hygrophila salicifolia. However, the survival rate of Hygrophila salicifolia was higher than that of Hygrophila pogonocalyx in both the control and experimental groups. When facing a competitive environment, the response mechanism of Hygrophila salicifolia is to reduce plant height, root length and stem section area more significantly than Hygrophila pogonocalyx. Experimental results suggest that the average root length of Hygrophila is reduced for the purpose of adapting to changes in the flow rate when the plants are mixed. Overall, flow-resistance adaptation of Hygrophila was different for both species when mixed species were planted than when species were planted alone, which demonstrates the presence of inter-specific competition. [ABSTRACT FROM AUTHOR]

Vegetation in freshwater and coastal ecosystems modifies flows, retains sediment, protects banks and shorelines from erosion. Hydraulic laboratory studies with live vegetation or artificial plant mimics, or numerical models with abstracted patches, are often used to quantify the effects of vegetation on water flow and sedimentation. However, the choice of plant and patch characteristics is often not supported by field observations of patch dimensions, density or spacing between consecutive patches. The discrepancy between plants in natural conditions and in flume experiments or numerical studies may affect the relevance of these findings for natural ecosystems. In this study, we provide guidelines for building realistic vegetation patches in hydraulic studies. We collected data on four species of fully submerged freshwater aquatic macrophytes that can grow into well-defined patches. We considered three relevant levels: individual plants (inside patches), isolated patches and multiple neighbouring patches. At the plant level, we observed significant differences in biomechanical traits (Young's modulus, flexural stiffness), resulting in stem Cauchy numbers ranging from 85.25 to 325.84, and leaf Cauchy numbers from 163.81 to 2003.97. At the patch level, we found significant relationships between patch length, width and height, showing covariation among different patch characteristics. The relationships among patch dimensions differed significantly among sampling sites for three of the four species, suggesting high intraspecific variability in patch sizes. By providing a first set of guidelines for choosing correct and ecologically relevant plant characteristics, this dataset aims to improve our understanding of the complex processes occurring inside and around submerged vegetated patches. [ABSTRACT FROM AUTHOR]

In addition to quantifying the taxonomic diversity of aquatic communities, understanding the patterns of alpha functional diversity (α-diversity) and exploring changes in functional dissimilarity (β-diversity) can improve our understanding on how ecosystems respond to environmental changes. In this study, we quantified functional alpha (α) and beta (β) diversity of macrophytic assemblages from river sites in Greece and then, examined relationships with water quality parameters and hydromorphological factors. We assigned 6 traits (Ellenberg nutrients indicator, Ellenberg light indicator, growth form, leaf size, leaf type, fruit size) to a total of 36 hydrophyte species and calculated three indices of functional diversity (functional richness, functional dispersion and functional evenness). We also estimated the total b-functional diversity and its' main components, turnover and nestedness. To assess the effects of water quality (including physical and chemical variables) we used Generalized Additive Models (GAM) for alpha functional diversity indices and Generalized Dissimilarity Models (GDM) for beta functional diversity. We performed Kruskal-Wallis tests and permutational multivariate analysis of variance (PERMANOVA) to search for significant variations of α- and β-diversity among the hydromorphological factors. Our results showed that macrophyte growth form and light preference were important trait characteristics that explained a large share of the total variance of functional composition. We also found relatively low taxonomic and functional richness, whereas taxonomic and functional dissimilarity were mostly attributed to species turnover, which expresses the changes in taxonomic and functional composition. We found significant relationships between functional dispersion and functional evenness with pH and oxygen saturation, whereas functional dissimilarity was driven only by geographic distance, although the GDM explained a small portion of the total variance. Functional richness, dispersion and evenness were significantly higher at systems with fine substrates and deep waters with low or high flow compared to systems with coarser substrates and riffle habitats. We also found significant variation in functional dissimilarity among the hydromorphological factors, although much of the total variance remained unexplained. Overall, our study highlights the importance of considering the functional diversity of aquatic plant assemblages within the frame of freshwater monitoring and conservation plans. [ABSTRACT FROM AUTHOR]

The analysis of plant trait composition has raised significant interest among freshwater ecologists as a complementary approach for assessing the effects of environmental change on ecosystem functions. In this study, we investigated patterns of functional traits of the aquatic macrophyte assemblages of 74 lotic ecosystems of Greece, and we identified associations between species traits and environmental variables (hydromorphological and physicochemical parameters) through testing the hypothesis that the environmental features determine the spatial structure of traits. We allocated 12 traits to a total of 39 hydrophyte species, and we conducted RLQ and fourth corner analysis to explore relationships between species, trait composition, and environmental gradients. Based on the results of the RLQ, a hierarchical cluster analysis was conducted to identify groups of plants that share common trait characteristics. Plants were discriminated into five discrete groups based mostly on their life form (e.g., free-floating, rooted submerged etc.) and their ecological preference for nitrogen levels. Hydromorphological parameters had a higher contribution than physicochemical variables in explaining the total variance of the trait data, with water abstraction, channel substrate, and hydrologic alteration being the most important. Our analysis did not reveal significant bivariate relationships between single traits and environmental parameters, although the five groups of macrophyte assemblages appeared to associate with certain environmental gradients. Free-floating and emergent plants were related to higher concentrations of nutrients, whereas rooted submerged plants were related to higher oxygen concentration and increased pH. In addition, free-floating plants were highly associated with metrics of hydromorphological change. Our findings showed clear discrimination of macrophytes based on their functional composition and association of traits with environmental gradients. Thus, further research could explore whether macrophyte functional groups can serve as indicators of environmental change and the overall ecosystem health. [ABSTRACT FROM AUTHOR]

In addition to quantifying the taxonomic diversity of aquatic communities, understanding the patterns of alpha functional diversity (α-diversity) and exploring changes in functional dissimilarity (β-diversity) can improve our understanding on how ecosystems respond to environmental changes. In this study, we quantified functional alpha (α) and beta (β) diversity of macrophytic assemblages from river sites in Greece and then, examined relationships with water quality parameters and hydromorphological factors. We assigned 6 traits (Ellenberg nutrients indicator, Ellenberg light indicator, growth form, leaf size, leaf type, fruit size) to a total of 36 hydrophyte species and calculated three indices of functional diversity (functional richness, functional dispersion and functional evenness). We also estimated the total β-functional diversity and its’ main components, turnover and nestedness. To assess the effects of water quality (including physical and chemical variables) we used Generalized Additive Models (GAM) for alpha functional diversity indices and Generalized Dissimilarity Models (GDM) for beta functional diversity. We performed Kruskal-Wallis tests and permutational multivariate analysis of variance (PERMANOVA) to search for significant variations of α- and β-diversity among the hydromorphological factors. Our results showed that macrophyte growth form and light preference were important trait characteristics that explained a large share of the total variance of functional composition. We also found relatively low taxonomic and functional richness, whereas taxonomic and functional dissimilarity were mostly attributed to species turnover, which expresses the changes in taxonomic and functional composition. We found significant relationships between functional dispersion and functional evenness with pH and oxygen saturation, whereas functional dissimilarity was driven only by geographic distance, although the GDM explained a small portion of the total variance. Functional richness, dispersion and evenness were significantly higher at systems with fine substrates and deep waters with low or high flow compared to systems with coarser substrates and riffle habitats. We also found significant variation in functional dissimilarity among the hydromorphological factors, although much of the total variance remained unexplained. Overall, our study highlights the importance of considering the functional diversity of aquatic plant assemblages within the frame of freshwater monitoring and conservation plans.

Wastes from breeding farms have globally increased greenhouse gases and caused a serious pollution to aquatic environments. Biogas treatment polymer bags could significantly reduce organic compounds; however, they could not effectively treat other pollutants in animal wastewater. The objective of this study was to assess removal efficiency of salinity and pollutants associated with pig wastewater using aquatic macrophytes. Four macrophytes namely Acrotichum aureum, Eleocharis dulcis, Typha domengensis, and Limnophyton obtusifolium and a soil control without vegetation were randomly assigned into fifteen mesocosms (1.2 x 0.7 x 0.6m) with 3 replicates for each treatment. Pig wastewater was filled continuously into input chambers of mesocosms in every three day with 5 liters. Water samples were collected from output chambers with 60 and 120 days after treatment while soil and vegetation samples were collected at the beginning and the end of the experiment. The results showed that E. dulcis, T. domengensis, and L. obtusifolium were dominant in removal of N, P, Cu and Zn and suspended solids as well; E. dulcis and T. domengensis significantly increased the dissolved oxygen; whereas the treatment of L. obtusifolium species showed the best efficiency in salt-ion removal. Pollutants of N, P, Cu and Zn tend to accumulate more in the macrophyte roots than in their leaves. Accumulation of N, P, Cu and Zn in the L. obtusifolium’s biomass is the highest compared with other treatments. From findings, it is suggested that a combination of three aquatic macrophytes including E. dulcis, T. domengensis, and L. obtusifolium could establish a constructed wetland system to directly treat pollutants of livestock wastewaters

This abstract presents an overview of aquatic macrophytes and their importance for the structure and function of aquatic ecosystems. It also discusses the effect of water quality and nutrient enrichment on macrophyte distribution, and the development of survey and monitoring techniques for characterizing waterside habitats. Finally, it highlights the need for detailed data for detecting changes at individual sites. Physicochemical parameters are major factors when considering the quality of water samples with the presence of macrophytes in an aquatic ecosystem. A study carried out from January to March in 2019 shows that the mean value of the water temperature was the highest in February, with a mean value of 26.5 °C; the PH, alkalinity, sulfate (SO42−), and nitrate (NO3−) were the highest in January, while the conductivity, total hardness of the water, magnesium, biological oxygen demand (BOD), and phosphate were the highest in March. Moreover, the water was 100% transparent during the whole study period. Twelve (12) macrophytes belonging to ten (10) families were encountered. The most abundant macrophytes encountered were the species Bumbusa vulgaris (Poaceae family). A single emergent macrophyte Ipomoea aquatic (Convolvulaceae family) was encountered. Free-floating and submerged macrophytes were absent due to the high flow rate of the river. It was observed that the physiocochemical parameters of River Ethiope fall under the normal range of good quality water, supporting Macrophytic vegetation. [ABSTRACT FROM AUTHOR]

Coeur d'Alene Lake (the Lake) has received significant contamination from legacy mining. Aquatic macrophytes provide important ecosystem services, such as food or habitat, but also have the ability to accumulate contaminants. We examined contaminants (arsenic, cadmium, copper, lead, and zinc) and other analytes (e.g., iron, phosphorus, and total Kjeldahl nitrogen (TKN)) in macrophytes from the Lake. Macrophytes were collected in the Lake from the uncontaminated southern end to the outlet of the Coeur d'Alene River (main contaminant source) located northward and mid lake. Most analytes showed significant north to south trends (Kendall's tau p ≤ 0.015). Concentrations of cadmium (18.2 ± 12.1), copper (13.0 ± 6.6), lead (195 ± 193), and zinc (1128 ± 523) were highest in macrophytes near the Coeur d'Alene River outlet (mean ± standard deviation in mg/kg dry biomass). Conversely, aluminum, iron, phosphorus, and TKN were highest in macrophytes from the south, potentially related to the Lake's trophic gradient. Generalized additive modelling confirmed latitudinal trends, but revealed that longitude and depth were also important predictors of analyte concentration (40–95% deviance explained for contaminants). We used sediment and soil screening benchmarks to calculate toxicity quotients. Quotients were used to assess potential toxicity to macrophyte associated biota and delineate where macrophyte concentrations exceeded local background concentrations. Exceedances (toxicity quotient > one) of background levels by macrophyte concentrations were highest for zinc (86%), followed by cadmium (84%), lead (23%), and arsenic (5%). [ABSTRACT FROM AUTHOR]

We report the first record of Utricularia breviscapa from the state of Maranhão, northeastern Brazil. We collected this species in the municipality of Chapadinha, eastern Maranhão, within the Cerrado domain. This work adds new information on the flora of Maranhão and on the distribution of U. breviscapa. Illustrations and descriptions are also provided.

This study was conducted to assess the phytoremediation potential of Pistia stratiotes for post-treatment of Ni(II) and Cr(III)-containing industrial wastewater effluents in mono (synthetic wastewater) and bimetallic systems (real wastewater). Differences were seen in metal uptake, growth performance, and metal accumulation of the plants. In the monometallic system, the highest removal efficiency was calculated as 77.50% for Cr(III) and 70.79% for Ni(II) at 5 mg L−1 concentration. At 1.25 mg L−1 concentration, the bioconcentration factor of P. stratiotes was calculated as 734.2 for Ni(II) and 799.0 for Cr(III). To assess the effects of metal stress on plants, photosynthetic pigments and percent growth rates were also investigated. The percent growth rate increased from 38.22 to 81.74% for Ni and decreased from 87.53 to 43.18% for Cr(III) when the metal concentrations increased from 1.25 to 5 mg L−1. Toxicity symptoms were less severe in plants exposed to low Ni concentrations. The greatest reduction in chlorophyll was observed at 5 mg L−1 Ni concentration. P. stratiotes showed better performance in the monometallic system. It was concluded based on present findings that P. stratiotes could potentially be used for the post-treatment of wastewaters containing Ni and Cr. Novelty Statement Previous phytoremediation studies were mostly conducted only in either mono- or multi-metallic systems. In this study, mono- and bimetallic systems were assessed together and the feasibility of research findings on a large scale was investigated in detail. Present findings may also aid in the development of phyto-remedial strategies and the identification of Ni and Cr toxicity in macrophytes. Pistia stratiotes are already known for its incredible potential in removing metals and other contaminants from wastewater effluents. However, most studies only present data regarding the plant performance in laboratory studies (synthetic wastewater), while this study provides some important additional information on natural effluent conditions, which transform the presented data more interesting from a practical point of view. [ABSTRACT FROM AUTHOR]

Macrophyte (aquatic plant) recovery has occurred in rivers worldwide, but assemblage patterns and habitat requirements are generally not well understood. We examined patterns of species composition and macrophyte abundance in the Upper Mississippi River (UMR), spanning 22 years of monitoring and a period of vegetation recovery. Non-metric multidimensional scaling (NMDS) ordination revealed a gradient of macrophyte abundance and diversity for 25 species, which were associated with water velocity, depth, wind fetch, and water clarity. Three macrophyte genera of ecological and restoration interest (Zizania aquatica, Vallisneria americana, and Sagittaria spp.) occupied different ecological niches. Trends of NMDS values showed that Z. aquatica first co-occurred in shallow areas with Sagittaria spp. but then expanded into deeper, lotic habitats where V. americana often resided. Curve Fit regression analysis identified large areas of significant increases in the relative abundance of V. americana and percent cover of Z. aquatica in several reaches of the UMR from 1998–2019. Sagittaria spp. were more spatiotemporally dynamic, which may indicate specific habitat requirements and sensitivity to environmental gradients. Our analyses showed that these three ecologically important genera are spatiotemporally dynamic but have somewhat predictable habitat associations, which can guide macrophyte management and restoration in the UMR and other large, floodplain rivers. [ABSTRACT FROM AUTHOR]

For the first time, a macrophyte-based assessment of ecological status was related to the accumulated heavy metals and trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Zn) in aquatic plants. Three moss and two vascular plant species were applied as biomonitors: Fontinalis antipyretica Hedw., Leptodictyum riparium (Hedw.) Warnst., Platyhypnidium riparioides (Hedw.) Dixon, invasive Elodea canadensis Michx., and Myriophyllum spicatum L. Three streams were assessed as good at a high ecological status which correlated with low contamination based on calculated contamination factors (CFs) and metal pollution index (MPI). Two sites evaluated in moderate ecological status were revealed to be in heavy trace element contamination. The most significant was the accumulation of moss samples from the Chepelarska River under mining impact. Mercury exceeded the environmental quality standard (EQS) for biota in three of the studied upland river sites. [ABSTRACT FROM AUTHOR]

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Small shallow lakes (SSLs) have great conservation value and support numerous ecosystem services. However, these small ecosystems are faced with many threats, including eutrophication, which tends to shift biodiverse SSLs to a turbid state dominated by phytoplankton. The ecological quality of SSLs still remains poorly evaluated because of the lack of adapted tools. We propose a new trophic index—TIM2S—based on the tolerance range of 245 macrophyte species to total phosphorus. As a single trophic index can favour oligotrophic ecosystems and their associated species to the detriment of more eutrophic but rare species, we converted TIM2S into a predictive reference-based model. Then, we compared TIM2S with five existing trophic indices in their efficiency to discriminate trophic levels and disentangle eight anthropogenic or internal pressures. TIM2S was the only index strongly correlated with total phosphorus and able to discriminate trophic levels. Most existing trophic indices are expert-based, and reflect community alteration rather than eutrophication. These expert-based indices are also dependent on numerous environmental factors, highlighting the need for robust predictive models to evaluate ecological statuses accurately. TIM2S is Water Framework Directive-compatible and can be used widely in Europe to evaluate the trophic status and trophic alterations of SSLs. [ABSTRACT FROM AUTHOR]

Najas marina is the dominant macrophyte species in Velenjsko jezero. It appeared in the lake in 1997 and soon prevailed over the species Myriophyllum spicatum L. and Potamogeton crispus L., which used to be the two most abundant species in the lake in the past. The physicochemical and geomorphological characteristics of the lake are discussed in relation to the attributes of Najas marina, presenting competitive advantages in this environment. Conditions in the lake such as warm water and unstable sediment enabled successful growth and life strategy of Najas marina, which is a summer-annual plant with short life cycle, quick propagation from seeds and a very extensive root system.

Abstract: Aim Evaluate the structure of the aquatic macrophytes assembly of the Jacarecica II Dam, Areia Branca, Sergipe, and verify if distance from the margin is a driver for species richness, and composition in this environment. Methods We settled transects where we plotted quadrats and subplots. The transects were perpendicular in relation to the reservoir margin, and the first quadrat was placed on the margin with the four following ones completely over the water surface. We estimated cover area for each macrophyte species in each quadrat. Each species was also classified according to its life form. We calculated community indexes and tested the influence of the distance from the margin on the structure of macrophyte assemblies. Results We sampled 10 emergent and four free-floating species, resulting in a richness of 14 species. The species with higher importance value were weedy and ruderal species (Salvinia auriculata and Eichhornia crassipes). The distance to the margin caused changes in macrophyte assembly and presented negative relation with species richness. Conclusions The studied assembly presents few species, with some presenting great dominance. This dominance reflects the anthropization of these habitats. Besides, the species composition and richness are modified in the sense that emergent and free-floating species co-occur in marginal quadrats, but only free-floating species occur in quadrats that are in areas that are more distant from the reservoir margin.

This research investigated four different species of aquatic macrophytes with natural occurrence in an urban environment highly anthropized in Southern Brazil. The aim of the research was to compare the phytoremediation potential among the species E. anagallis, H. grumosa, H. ranunculoides, and S. montevidensis through Pearson´s correlation analysis and cluster analysis, using the heavy metal content identified through HNO3 - HClO4 and phytoremediation indexes. The results highlighted the bioconcentration factor (BCF) of H. ranunculoides, with outstanding results for Cu BCF = 667.09, Zn BCF = 149.93, Cd BCF = 26.85, Cr BCF = 31.77, Ni BCF = 35.47, and Pb BCF= 126.29. Additionally, H. grumosa and S. montevidensis were also highlighted, considering the potential phytoremoval (g ha−1). Therefore, this study demonstrates the tolerance and potential for removal of heavy metals Cu, Cr, Cd, Pb, Ni, and Zn by the evaluated aquatic macrophyte species and elucidates the outstanding potential of application in phytoremediation purposes. [ABSTRACT FROM AUTHOR]

Toxic cyanobacterial blooms are a well-known problem in eutrophic water bodies, but cyanobacterial toxicity in ambient springs is unexplored. Therefore, we studied the toxin content and effects of two extracts obtained from epilithic and benthic microbial mats containing different algae and filamentous cyanobacteria, Phormidium breve and Oscillatoria limosa, respectively, on fresh biomass, number of roots, and pigment content in duckweed Spirodela polyrhiza and on survivorship of Daphnia magna (Cladocera). Mat samples, used to prepare extracts for bioassays, were collected in the anthropogenically transformed limnocrenic Górecko spring, located (50°31′08″ N and 22°57′10″ E) in the Roztocze region (Eastern Poland). It drains an abundant aquifer built with Cretaceous sediments. Neither anatoxin-a (ANTX) nor microcystins (MCs) were detected in the extracts using HPLC techniques; however, negative effects of the extracts on tested organisms were observed. The Phormidium extract contained concentrations of cyanobacterial metabolites a few times higher than the Oscillatoria extract. In general, both extracts affected plants in a dose-dependent manner; however, the Oscillatoria extract influenced pigment production without a clear trend. The highest concentrations of Phormidium extract (p < 0.05) significantly decreased the number of roots and the content of chlorophylls and carotenoids in S. polyrhiza. The Oscillatoria extract caused a statistically significant (p < 0.05) decrease in biomass and number of roots; however, it generally positively influenced the production of pigments. The extract containing O. limosa metabolites was more toxic to D. magna than the extract containing higher amounts of metabolites of P. breve. Cyanobacteria inhabiting temperate springs may negatively affect hydrobionts by producing secondary metabolites other than ANTX and MCs; however, the contribution of algae cannot be excluded. Extensive research on cyanobacteria in springs, their metabolites, and their effects on living organisms should be conducted. [ABSTRACT FROM AUTHOR]