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A critical knowledge gap in freshwater plant research is the lack of genetic tools necessary to answer fundamental questions about their demographic histories, adaptation and phylogenetic relationships. One example of this is Typha, a global genus of freshwater plants foundational to wetlands that also is becoming an increasingly problematic biological invader in numerous regions worldwide; although important insights have been discovered for this genus, existing markers are insufficient to answer fundamental questions about their demographic histories, adaptation and phylogenetic relationships; to identify introduced and hybrid lineages; and to examine patterns of hybridisation and introgression.We optimised a library preparation and data processing protocol to develop genome–wide nuclear and plastid resources for studying the evolutionary history, genetic structure and diversity, hybridisation, local adaptation, invasiveness, and geographical expansion dynamics of Typha.We sequenced 140 Typha samples and identified ~120 K nuclear single nucleotide polymorphisms (SNPs) that differentiate T. angustifolia, T. domingensis and T. latifolia, and retrieved their plastome sequences. We observed genetic introgression among the three species.Following a fast, straightforward and cost‐efficient genomic library preparation protocol, we produced a suite of genome‐wide resources to facilitate investigations into the taxonomy and population genetics of Typha and to advance the genomic understanding of wetland plants.The protocol described, the updated chromosome‐level genome assembly of T. latifolia, the catalogue of species‐specific SNPs, and the chloroplast sequences produced in this study comprise permanent resources that can be applied to study the genetic composition of multiple populations and hybrid zones, and will be incorporated into future studies of Typha, an ecologically important and globally invasive macrophyte. [ABSTRACT FROM AUTHOR]

1.Freshwater ecosystems are being exposed to increasing salinisation, often because of pollution from road deicing salts, which is becoming more widely acknowledged. To address this issue, municipalities are turning towards the sodium salt alternatives of CaCl2 and MgCl2, which are marketed as being safer for the environment. However, research into the actual safety of these salts on aquatic plants is lacking.2.We investigated the effects of the most common road salt (NaCl) and two alternatives (MgCl2 and CaCl2) on the productivity of a common freshwater plant (i.e., Elodea canadensis) under three salt concentrations (control, 250, and 1,000 mg Cl−/L). Light‐bottle/dark‐bottle trials were performed to quantify net primary productivity, respiration, and gross primary productivity. These responses were tracked over time (1 vs. 3 weeks) to assess plant acclimation and lag effects under different levels of the three salts.3.We discovered that NaCl and CaCl2 altered these measures of plant metabolism, but MgCl2 had no effects. We also observed instances of acclimation (i.e. salt effects after 1 week that disappeared after 3 weeks) and lag effects (i.e. no salt effect after 1 week, but salt effects after 3 weeks). These impacts are likely to be the results of plant responses to salt at the cell and molecular levels, including short‐ and long‐term changes in photosynthetic pigments. Therefore, the plant responses were salt‐specific, with instances of plant acclimation and lag effects.4.This appears to be the first study of net primary productivity, respiration, and gross primary productivity in freshwater plants across a range of different salts, and it highlights how freshwater salinisation can have substantial effects on plant productivity. These effects will probably have an impact on the growth of macrophytes, which play key ecological roles in aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Simple Summary: Water measurers (Hemiptera: Heteroptera: Hydrometridae) can be found mainly on marginal vegetation or on plants on the surface of freshwater bodies. Recently, two monotypic genera restricted to subterranean habitats were described from Brazil, namely Cephalometra Polhemus & Ferreira, 2018 and Spelaeometra Polhemus & Ferreira, 2018. Here, a second species of Spelaeometra is described based on material collected in a hotspot of subterranean animals in the Serra do Ramalho karst area, Brazil. Spelaeometra Polhemus & Ferreira, 2018 (Hemiptera: Heteroptera: Hydrometridae) is a monotypic and troglobitic genus, recently described based on material collected in the state of Minas Gerais, Brazil. From specimens collected in the Gruna do Enfurnado Cave in the Serra do Ramalho karst area, municipality of Coribe, state of Bahia, Brazil, we describe Spelaeometra hypogea Cordeiro & Moreira, sp. nov. and compare it with Spelaeometra gruta Polhemus & Ferreira, 2018. The new species is diagnosed by the general body color being pale-yellow to light-brown; antennal segments I and II being subequal in length; the reduced gular lobe, not covering any labial segment; the male proctiger without apical projections; and the male paramere with convex dorsal margin after the curvature, with a narrow hook-like apex. [ABSTRACT FROM AUTHOR]

Premise of research. Organisms that reproduce asexually must respond to abiotic stresses in their environment while contending with the potential disadvantage of the reduced ability for genetic variation through recombination. Common duckweed (Lemna minor) is an aquatic plant that reproduces predominantly asexually through the budding of ramets. As a freshwater plant, duckweed experiences stress from salt (e.g., NaCl), which detrimentally affects growth, photosynthesis, and cellular processes. We took a demographic approach to examine whether ancestral exposure to salt stress affects the ability of duckweed offspring to tolerate immediate exposure to the same stress. Methodology. We placed three consecutive clonal generations of duckweed in an environment with 2 g L−1 NaCl (nonlethal salt stress) or 0 g L−1 NaCl (control), followed by an additional zero to three generations in the control environment to vary the presence and schedule of ancestral stress. After these treatments, we used the offspring produced as focal plants for the experiment. Half were placed into the salt stress environment, and half were placed in control conditions; focal plants were tracked longitudinally. Pivotal results. Immediate stress decreased fitness as a result of a slowing of reproduction, suggesting a cost of stress tolerance. The effects of ancestral stress, and the interaction of immediate and ancestral stress, were more complex. Specifically, recent ancestral stress induced plants to produce offspring more quickly but with the potential cost of lowered offspring quality. Conclusions. Our results amplify findings that responses to, and fitness consequences of, current stressors can be contingent on past exposure. [ABSTRACT FROM AUTHOR]

Wetlands are being contaminated by housing developments, effluents, industrial areas, and poor sanitation, resulting in the presence of plastic polymers and the development of biofilms on these materials, which represent an elevated risk to freshwater fauna and flora. The objective of this study was to characterize mesoplastics and microplastics, collected in the Gualí Wetland, Colombia, as well as to verify the presence of biofilms on such polymers. Nine water samples (36 L per sample) were evaluated at three points of the wetland; the size of the particles was determined by image analysis, the type of polymer through FTIR, and the presence of biofilms by microscopy. A total of 79 items/0.135 m3 were collected, 2 macroplastic items, 53 mesoplastic items, and 24 microplastic items. The presence of fragments (70%) and pellets (41%), with transparent (40%) and white (30%) being the predominant ones, was outstanding. Among the polymers, high-density polyethylene (HDPE) dominated, followed by expanded polystyrene. The results of SEM demonstrated the presence of diatoms on the surface of the plastic polymers. Furthermore, the results showed a greater amount of HDPE mesoplastics and microplastics in the shape of fragments and pellets. In addition, the presence of biofilms on these plastic particles can increase the adsorption of contaminants, negatively affecting this ecosystem. The outcome of this study can be used to identify bacteria that reside in biofilms associated with microplastics and mesoplastics. [ABSTRACT FROM AUTHOR]

The current paper presents the first effort to organize a comprehensive review of the Invasive Alien Species (IAS) of Greece. For this purpose, a database was developed with fields of information on the taxonomy, origin, ecology and pathways of introduction of terrestrial, freshwater and marine species. Our database includes a) taxa in the Union's list that are present in Greece, b) taxa already present in Greece and considered to be invasive, and c) taxa highly likely to enter Greece in the next 10 years and become invasive. The Database served as the starting point for the compilation of the National List of Alien Invasive Species (HELLAS-ALIENS) in compliance with the EU Regulation 1143/2014. Overall, the HELLAS-ALIENS comprises 126 species, i.e. 32 terrestrial and freshwater plant species, 14 terrestrial invertebrates, 28 terrestrial vertebrates, 30 freshwater fishes and invertebrates and 22 marine species. Terrestrial invertebrates, birds and mammals are mainly of Asiatic origin. Most of the terrestrial plants have their native geographical distribution in the Americas (North and South). Most of the freshwater invertebrates and fishes are of North American origin, while the majority of the marine species are of Indo-Pacific origin. The first records of IAS concern terrestrial plant species, and date back to the 19th century, while those in freshwater and marine ecosystems seem to have been systematically recorded some decades later. Regarding the pathways of introduction, most of the taxa arrived in Greece or are expected to arrive through escape from confinement and unaided. The majority of the terrestrial, freshwater and marine species have been evaluated as of High-risk for the indigenous biodiversity and only 3% of the species listed have been evaluated of Low-risk. Our results provide an important baseline for management and action plans, as required by the priorities set by the European Union through the Biodiversity Strategy for 2030. [ABSTRACT FROM AUTHOR]

Lagarosiphon major (Ridl.) Moss ex Wager (Hydrocharitaceae) is a submerged freshwater plant native to South Africa, and a destructive invader of waterways across Europe, Australasia and the U.S.A. Native range exploration identified a leaf mining ephydrid fly, Hydrellia lagarosiphon, as a promising biological control candidate agent. Host specificity was conducted on H. lagarosiphon, using laboratory no-choice and paired choice tests. A number of non-target native Potamogeton species sustained feeding damage under no-choice and paired choice testing. To prevent rejection of a potentially safe agent, multi-generational population persistence trials were conducted on select native Potamogetonaceae. The non-target species could not sustain a viable H. lagarosiphon population beyond two generations. A risk assessment, incorporating the preference and relative survival, indicated that three non-target species presented extremely low (<1.3%) risk of sustaining damage relative to that of L. major. Potamogeton polygonifolius and P. x lanceolatus present a reproductive risk of 5.61% and 11.5% respectively but could not support a viable population beyond the 2nd generation. These results, coupled with damage efficacy and predicted colonisation, demonstrate the potential H. lagarosiphon has as a biological control agent for L. major in Ireland. Classical biological control could provide a safe, cost-effective method of control of the invasive submerged weed Lagarosiphon major. Multigenerational population persistence tests strengthen host specificity testing to predict feeding and reproductive risks of a biological control agent. Risk assessment data suggest a low level of Hydrellia lagarosiphon larval feeding could occur on three non-target Potamogeton species. While two native Potamogeton species sustain a relatively low reproductive risk, they failed to sustain the fly beyond the 2nd generation. Classical biological control provides an alternative control strategy to costly mechanical or environmentally unsuitable chemical control as the safety of Hydrellia lagarosiphon has been established in this pre-release testing procedure. The risk assessment presented here could form the basis of an application to the regulatory authorities to release H. lagarosiphon on L. major in Ireland. [ABSTRACT FROM AUTHOR]

Stalter, R. and Lonard, R.I., 2023. Biological flora of coastal freshwater and brackish marshes: Cladium jamaicense Crantz. Journal of Coastal Research, 39(4), 763–776. Charlotte (North Carolina), ISSN 0749-0208. Cladium jamaicense Crantz, also known as sawgrass, has a broad distributional range from the Atlantic coast of Virginia to Florida, to southern Texas, the Caribbean, and along the Atlantic coast of Mexico to Central America, and to Brazil. Cladium jamaicense typically occurs in oligotrophic sloughs and fresh and brackish marshes where optimal salinity values range from 0 to 3.5 ppt. This species is a long-lived perennial with a highly developed rhizome system with rhizomes up to 20 cm long and 2.5 to 10 mm in diameter. Asexual reproduction is common. Its fibrous root system comprises short dauciform roots characterized by a dense number of long root hairs. Culms are 1.0 to 3.0 m tall. Leaf blades are coarse, flat, or broadly involute; leaf margins and the abaxial midvein have sharp, hacksaw-like teeth. Typha domingensis (cattail) is C. jamaicense's most important competitor, especially in sites that have been enhanced with phosphorus. Restoration of sawgrass marshes requires managing long-term changes in ecosystem functions and hydrological management strategies. [ABSTRACT FROM AUTHOR]

Contrary to their terrestrial counterparts, freshwater plants are linked to flooding dynamics associated with their habitats in or around water. Gas diffusivity, light availability, nutrient concentrations, and flow velocity select not only on freshwater eco-physiological adaptive traits but also on general plant functional traits, such as plant height or specific leaf area. Emerging stressors under global change impact freshwater plant functions at different temporal and spatial scales via both trait–trait and trait–environment relationships. Predicting how freshwater plant communities are changing and the reciprocal relationships between freshwater plant functions and the environment will require a focus on the specific conditions and traits important for a life in water. Freshwater ecosystems are of worldwide importance for maintaining biodiversity and sustaining the provision of a myriad of ecosystem services to modern societies. Plants, one of the most important components of these ecosystems, are key to water nutrient removal, carbon storage, and food provision. Understanding how the functional connection between freshwater plants and ecosystems is affected by global change will be key to our ability to predict future changes in freshwater systems. Here, we synthesize global plant responses, adaptations, and feedbacks to present-day and future freshwater environments through trait-based approaches, from single individuals to entire communities. We outline the transdisciplinary knowledge benchmarks needed to further understand freshwater plant biodiversity and the fundamental services they provide. [ABSTRACT FROM AUTHOR]

A growing body of evidence has shown that biological invasions cause shifts in species composition of communities in space and time. Although biological invasions are considered a major driver of biotic homogenisation worldwide, most previous studies were conducted at small spatial scales and over short time periods, which may have underestimated the impacts of exotic species on native communities.Using a unique dataset of aquatic plants sampled in 235 sites over 12 years (2007–2010 and 2015–2019) in a large reservoir (Itaipu Reservoir; 1350 km2), we analysed how the invasion of a non‐native grass Urochloa arrecta affects the species richness, ecological uniqueness (i.e. local contribution to beta diversity—LCBD) and temporal β–diversity of native plant communities.From 3934 surveyed plant communities, U. arrecta was recorded in 2888 samples and it was absent from 1046 samples. Overall, species richness and ecological uniqueness of native plant communities were markedly lower in sites invaded than non‐invaded by U. arrecta. From 2007 to 2019, the ecological uniqueness of native plants was 60% lower in the invaded than non‐invaded sites. Whereas in invaded sites species loss was the dominant process driving native communities over time, in non‐invaded sites gain of new native species was the primary process underlying community trajectories. Moreover, comparing native plant communities before and after the invasion of U. arrecta, species richness, ecological uniqueness and species gains of native plant communities decreased, whereas species losses increased after the invasion of U. arrecta. Finally, the positive relationship between native biodiversity and precipitation was stronger in non‐invaded than invaded sites.Synthesis. Our findings provide comprehensive evidence that an invasive plant is decreasing the spatial and temporal β–diversity of native plant communities through declining species richness, rather than simply correlating with them. This suggests that U. arrecta is driving native plants to become less diverse and homogeneous after the invasion, both spatially and temporally. Our findings illustrate that at broad scales, aquatic plant communities may become increasingly homogeneous with the increasing number of biological invasion events taking place worldwide. [ABSTRACT FROM AUTHOR]

Aim: Decreasing in the diversity and distribution of native submerged plants have been widely observed in recent decades. Global underwater darkening, which is mainly caused by radiation dimming and a decrease in transparency due to, e.g. eutrophication, has emerged as a general trend that strongly hampers the growth of submerged plants in lakes by decreasing the light available for photosynthesis. However, few studies have attempted to compare the responses of native and invasive submerged plants to underwater darkening. In this study, we aimed to compare the effects of light attenuation on the growth and photosynthesis traits of native and invasive submerged plants. Location: East China. Method: Through field investigations and a mesocosm experiment, the responses of functional traits of two representative native [water thyme (Hydrilla verticillata), Eurasian watermilfoil (Myriophyllum spicatum)] and one invasive [Carolina fanwort (Cabomba caroliniana)] plant species to various environmental factors, notably to underwater light attenuation, were studied. Results: Underwater photosynthetically active radiation (PAR) exerted a substantial effect on the relative coverage and abundance of the three studied submerged plants in their natural freshwater habitats. Invasive C. caroliniana showed relatively superior growth (total biomass and relative growth rate) and photosynthesis traits (maximum quantum yield of photosystem II Fv/Fm, chlorophyll a content, chlorophyll b content and the ratio of Chl a and b contents) compared to the two native plants under low underwater PAR conditions. In contrast, under high underwater PAR conditions, C. caroliniana showed the opposite response. Main Conclusions: Light attenuation inhibits the growth of native submerged plants but facilitates the growth of invasive plant species. Restoration of freshwater lakes by reducing deterioration from underwater darkening (for instance, by reducing of external nutrients loading) may therefore constrain the growth and spread of the invasive C. caroliniana. [ABSTRACT FROM AUTHOR]

Lakes represent an important source of atmospheric methane (CH4); however, there are few studies on which lake-dwelling invasive aquatic plants generate CH4. Therefore, in this study, CH4 emissions were measured using a floating chamber and gas chromatography in a subtropical lake in China. We considered four community zones of invasive plants (Eichhornia crassipes), emergent vegetation (Zizania latifolia), floating-plant (Trapa natans) and open-water zones. The results indicate that the flux of CH4 emissions varied between −5.38 and 102.68 mg m−2 h−1. The higher emission values were attributed to lake eutrophication. Moreover, the flux of CH4 emissions in the invasive plant zone was 140–220% higher than that in the open-water and the floating-plant zones. However, there was no significant difference in CH4 emissions between the invasive plant and the emergent vegetation zones. This may be due to a higher production of plants, as well as the rapid reproductive rate of the invasive plants. Finally, CH4 emissions were positively associated with the air and water temperature; however, the emissions were also negatively associated with water depth. Our results suggest that invasive plants enhance freshwater CH4 emissions, thus contributing to global warming. [ABSTRACT FROM AUTHOR]

Acarlar Lake is a freshwater floodplain lake that consists of swamps and forests growing up on inorganic soils and exposing to seasonal floods. During the studies carried out in Acarlar Lake Floodplain (Sakarya) between February 2011 and May 2011, three new records were identified for the freshwater algae of Turkey from the samples obtained from Ceratophyllum demersum L. and Typha sp. L. plants. These species are Phacus gigas Cunha, Phacus undulatus var. major (Prescott) Huber-Pestalozzi, and Trachelomonas sydneyensis Playfair belonging to Euglenozoa. [ABSTRACT FROM AUTHOR]

In the current article, a novel geothermal-biomass-powered multi-generation plant was introduced and probed through thermo-economic-environmental aspects plus multi-criteria optimization. To produce various outcomes, like electricity, heating, cooling, as well as hydrogen and freshwater, the plant took advantage of the Rankine cycle, a dual-effect absorption refrigeration unit, a proton exchange membrane water electrolyzer, and a biomass combustor. The plant's environmental consequences were reviewed based on NOx and CO 2 emitting to mark the environmental advantages of burning municipal solid waste as biomass rather than coal. Owing to the investigation, the plant provided 31.68 MW direct power, 39.85 MW heating, 126.36 MW cooling, 23.3 m3/h freshwaters, and 88.12 kg/h hydrogen, besides 58.54% and 16.45% calculated as plant energetic and exergetic efficiencies. By applying the SPECO approach, the total product cost rate was attained at 1.629 $/s. As well, this plant had an exergo-environmental impact factor of 0.9. Moreover, a parametric study was brought out to comprehend the consequences of chief parameter changes. Eventually, a multi-criteria optimization was employed for the plant for the enhancement of the techno-economic operations. In the optimum status, the total cost rate of the product and exergetic efficiency of 1.57 $/s and 17.26% were attainable. [ABSTRACT FROM AUTHOR]

Peatlands are one of the globally important ecosystems. Blanket bogs are a type of peatlands where water is generally supplied by meteorological events (rain, snow). We have been conducting the first detailed algal flora study of blanket bogs of Turkey and found new records of algae genera ever given for Turkey. Here, we report a total of four desmids genera identified as new records for freshwater algal flora of Turkey: Spirotaenia (Spirotaenia condensata, Spirotaenia erythrocephala), Mesotaenium (Mesotaenium macrococcum), Hyalotheca (Hyalotheca dissiliens), and Bambusina (Bambusina borreri). Their ecological habitat is also discussed to highlight the importance of protection and sustainability of these unique areas. [ABSTRACT FROM AUTHOR]

Mateo-Elizalde et al. introduce duckweeds, a family of freshwater plants. [ABSTRACT FROM AUTHOR]

Freshwater biodiversity is severely threatened, and despite many efforts to halt biodiversity loss the decline continues. Here, we used a transplantation approach to explore whether failure to reverse this trend for freshwater plants reflects that restoration measures applied to streams are inadequate for restoring suitable habitat conditions for plant species in decline.We identified declining species within the plant genus Potamogeton and introduced five of these (Potamogeton compressus L., Potamogeton gramineus L., Potamogeton lucens L., Potamogeton praelongus Wulfen., and Potamogeton pusillus L.) into five restored lowland stream reaches in three different habitat types to examine species establishment and growth.We found that plant establishment varied among streams and species, but we did not see any effect of habitat type within streams on either species growth or survival. Potamogeton compressus and P. pusillus failed to overwinter, while P. gramineus, P. lucens, and P. praelongus were all able to establish viable stands and to overwinter successfully in several of the experimental streams.Our results suggest that suitable habitats are available for declining Potamogeton species in restored stream reaches in Denmark, but their continued growth may be challenged by limited overwintering success. Consequently, we find it likely that dispersal constraints prevent declining Potamogeton species from naturally recolonising restored stream reaches.Understanding the importance of life history traits, such as overwintering and dispersal, can be crucial for the recovery of plant diversity in streams. Here we show that species that survived during winter were those with extensive growth of roots and rhizomes making them more adapted to withstand high flows than species relying on seeds and turions for overwintering. The creation of calmer backwater habitats can therefore be crucial when restoring stream reaches since these habitats may facilitate overwintering of species lost from the main channel during winter. [ABSTRACT FROM AUTHOR]

Little is known about the current state of freshwater biodiversity in Canada, one of the countries with the greatest amount of surface waters in the world. To address this knowledge gap, we compiled a list of all available assessments of conservation status for freshwater species (over 3000 taxa) and further evaluated the overall status of six distinct taxonomic groups, focusing on organisms reliant on fresh waters (i.e., aquatic plants, invertebrates (with a focus on freshwater mussels), fishes, herpetofauna (reptiles and amphibians), birds, and mammals). Overall, 11.7% of all freshwater species of plants and animals assessed were found to be "at risk" (i.e., listed as "Threatened", "Endangered", or "Extirpated") and 17.9% identified as "Special Concern". We found that 37.9% of species lacked sufficient data to enable their status to be assessed. Data gaps in Canada's assessment of its freshwater species were most prevalent in invertebrates (excluding freshwater mussels). Given the alarming state of freshwater biodiversity in Canada, we conclude by providing recommendations that focus on evaluating temporal trends and informing conservation actions. [ABSTRACT FROM AUTHOR]

• Toxicity of aged PVC MPs is greater than that of virgin PVC MPs. • MPs affect the growth and intracellular components of C. pyrenoidosa. • MPs promote nitrate uptake and inhibit photosynthesis of C. pyrenoidosa. • Extracellular polymeric substances increase during exposure to aged MPs. • The toxicity of MPs was associated with intercellular oxidative stress levels. The toxicity of microplastics (MPs) on freshwater plants has been widely studied, yet the influence of aged MPs remains largely unexplored. Herein, we investigated the influence of polyvinyl chloride (PVC) MPs, both before and after aging, at different environmentally relevant concentrations on Chlorella pyrenoidosa , a freshwater microalgae species widely recognized as a valuable biomass resource. During a 96-h period, both virgin and aged MPs hindered the growth of C. pyrenoidosa. The maximum growth inhibition rates were 32.40 % for virgin PVC at 250 mg/L and 44.72 % for aged PVC at 100 mg/L, respectively. Microalgae intracellular materials, i.e., protein and carbohydrate contents, consistently decreased after MP exposure, with more pronounced inhibition observed with aged PVC. Meanwhile, the MP aging significantly promoted the nitrogen uptake of C. pyrenoidosa , i.e., 1693.45 ± 42.29 mg/L (p < 0.01), contributing to the production of humic acid-like substances. Additionally, aged PVC induced lower chlorophyll a and Fv/Fm when compared to virgin PVC, suggesting a more serious inhibition of the photosynthesis process of microalgae. The toxicity of MPs to C. pyrenoidosa was strongly associated with intercellular oxidative stress levels. The results indicate that MP aging exacerbates the damage to photosynthetic performance and bioenergy production in microalgae, providing critical insights into the toxicity analysis of micro(nano)plastics on freshwater plants. [Display omitted] [ABSTRACT FROM AUTHOR]

Microplastics (MPs) and antibiotics are ubiquitous in aquatic ecosystems, and their accumulation and combined effects are considered emerging threats that may affect biodiversity and ecosystem function. The particle size of microplastics plays an important role in their combined effects with antibiotics. Submerged macrophytes are crucial in maintaining the health and stability of freshwater ecosystems. However, little is known about the combined effects of different particle size of MPs and antibiotics on freshwater plants, particularly their effects on submerged macrophyte communities. Thus, there is an urgent need to study their effects on the macrophyte communities to provide essential information for freshwater ecosystem management. In the present study, a mesocosm experiment was conducted to explore the effects of three particle sizes (5 µm, 50 µm, and 500 µm) of polystyrene-microplastics (PSMPs) (75 mg/L), tetracycline (TC) (50 mg/L), and their co-pollutants on interactions between Hydrilla verticillata and Elodea nuttallii. Our results showed that the effects of MPs are size-dependent on macrophytes at the community level rather than at the population level, and that small and medium sized MPs can promote the growth of the two test macrophytes at the community level. In addition, macrophytes at the community level have a stronger resistance to pollutant stress than those at the population level. Combined exposure to MPs and TC co-pollutants induces species-specific responses and antagonistic toxic effects on the physio-biochemical traits of submerged macrophytes. Our study provides evidence that MPs and co-pollutants not only affect the morphology and physiology at the population level but also the interactions between macrophytes. Thus, there are promising indications on the potential consequences of MPs and co-pollutants on macrophyte community structure, which suggests that future studies should focus on the effects of microplastics and their co-pollutants on aquatic macrophytes at the community level rather than only at the population level. This will improve our understanding of the profound effects of co-pollutants in aquatic environments on the structure and behavior of aquatic communities and ecosystems. [Display omitted] • Small- and medium-sized microplastics can promote macrophyte growth at community level. • Macrophytes showed stronger resistance at community level than at population level. • The combined toxic effects between MPs and TC exhibited antagonistic. [ABSTRACT FROM AUTHOR]

Limited information exists on the environmental persistence of genetic markers for fecal indicator bacteria (FIB) in treated wastewaters. Here, the decay rate constants of culturable cells and genetic markers for four diverse groups of FIBs, such as enterococci, Clostridium, Escherichia coli, and Bacteroides, were investigated in freshwater microcosms seeded with disinfected and non-disinfected secondary-treated wastewaters. Decay rate constants of genetic markers and culturable cells varied significantly among the different FIB groups. Water temperatures (winter vs. fall/spring/summer) significantly affected the decay of all genetic marker and cell types; however, genetic marker decay were not found to be significantly different in disinfected (chlorination/ultraviolet) and non-disinfected wastewater-seeded microcosms or, for example, lake- and river-receiving waters. No evidence was seen that decay rate constants of FIB genetic markers from treated wastewater were substantially different from those observed in similar, previously reported microcosm studies using raw sewage. Unexpected relationships between decay rate constants of genetic markers and culturable cells of Bacteroides were observed. Results suggest that decay rate constants of FIB genetic markers determined from other studies may be applicable to treated wastewaters. Results of this study should be informative for ongoing efforts to determine the persistence of FIB genetic markers relative to surviving pathogens after wastewater treatment. [ABSTRACT FROM AUTHOR]

Aim: The regionalized patterns of biodiversity distributions are actively studied in terrestrial and marine ecosystems, but much less is known on the geographical patterns of ecoregions founded on freshwater taxa. Here, we studied, for the first time, how well existing freshwater ecoregions describe the geographical distribution of inland water plants. Location: Greenland, continental Canada and USA. Taxon: Freshwater vascular plants of all taxa and multiple functional groups (i.e. growth forms). Methods: Using newly available fine‐grained data on freshwater plant distributions, we studied how ecoregions founded on fish are suitable for freshwater plant regionalization across North America. Specifically, we calculated internal homogeneity and distinctness among neighbouring ecoregions in relation to species replacements and richness differences. We also explored how a complex suite of ecogeographical characteristics affect ecoregion delineation of freshwater plants using spatially explicit regression routines. Results: We found a clear geographical patterning of ecoregion robustness for North American freshwater plants, with communities being more internally homogeneous and more similar to one another in Polar and Subtropical inland waters. The degree of internal homogeneity and ecoregion distinctness were almost equally driven by species replacements and richness differences. Considering different life‐forms, ecoregion delineation performed best for emergent and floating‐leaved plants. Finally, within‐ecoregion homogeneity and distinctness were best explained by annual mean temperature and terrain ruggedness, respectively, with mean water alkalinity, ecoregion area and late Quaternary glacial legacies having supplementary effects. Main conclusions: Our findings suggest that selection through climate filtering (e.g. mean annual temperature) is likely the main mechanistic driver of freshwater plant ecoregions. Geographical regionalizations founded on a particular organismal group may not be directly applicable for all taxa but can be a good basis for further adjustments. Our study is a promising starting point for further investigations of geographical delineations for freshwater taxa other than fish. [ABSTRACT FROM AUTHOR]

Excessive growth of invasive alien aquatic plants threatens local ecosystems and has both ecological and economic impacts. This work highlights morphological and functional aspects of Pistia stratiotes L., first reported in Fez in 2012. The total photosynthetic area of a Pistia plant is highly correlated (R2=0.70) to the product of the length and maximum width of the outer leaf. The total biomass of Pistia was highly related (R2=0.71) to plant size and averaged 67.54±26.35 g dry weight·m-2. Its peak does not necessarily co-occur with flowering and/or high production of stolons. The total nitrogen and phosphorus mineralomasses correspond to 11.46±4.55 kg N·ha-1 and 0.83±0.33 kg P·ha-1. The biomass and mineralomasses of Pistia, estimated under these invasive conditions, ranks it among the least productive Moroccan wetland plants. [ABSTRACT FROM AUTHOR]

The increasing use of artificial light at night has led to ecosystem exposure to light pollution worldwide. Aquatic ecosystems are particularly exposed, since lit road networks, urban development and industrial infrastructure are frequently located along river, lake, and sea shores. Although the negative effects of night‐time lighting on the physiology, behaviour, and life‐history traits of animals have been largely documented, there is a large knowledge gap about the responses of plants, especially regarding leaf functioning and resource‐management strategies. Some authors have proposed contrasting hypotheses of mechanistic responses to dim light at night in plants, but empirical results are still lacking.Based on field measurements of nocturnal irradiance in freshwater ecosystems located in peri‐urban areas, we performed a mesocosm experiment using three species of submerged aquatic plants. After 5 months of exposure to realistic dim light at night, four functional traits related to the resource management at the leaf level were measured.Artificial light at night had significant effects on the leaf physiology or chemistry, affecting their resource acquisition rate, but with different response intensities depending on the species. No effect was found on morphological or biomechanical traits for any of the studied species.These results support the hypothesis that plants could interpret dim light at night as a shaded environment and respond accordingly.We demonstrated that the effects of light at night on plants may have been underestimated in previous work. By modifying biotic interactions (e.g., competition and herbivory), these responses can have profound effects on community structure and ecosystem functioning. [ABSTRACT FROM AUTHOR]

Although planktonic algae are a basic component of freshwater ecosystems, studies on their diversity and species distribution are still not in satisfactory numbers. This study aims to contribute to Turkish freshwater algal flora particularly with the new records reported. A total of 158 Charophyta taxa were determined in the study conducted from 2017 to 2019 in 25 river basins of Turkey. In this study, while the highest Charophyta taxon was found in Sakarya and Batı Akdeniz basins with 50 and 42 taxa, respectively, Burdur basin was the only basin where we did not find the Charophyta species. The highest Charophyta diversity was observed in Girdev Lake (Batı Akdeniz basin) and Işık Dağı Karagöl Lake (Sakarya basin) among the lakes of Turkey’s 25 river basins. Thirty-one of these Charophyta taxa represent new records for the freshwater algal flora of Turkey. Of these, 13 species are commonly distributed, while 18 species have rare distribution areas. Morphology, ecology, and distribution of each taxon were also discussed in details. [ABSTRACT FROM AUTHOR]

Premise: Wetland plants regularly experience physiological stresses resulting from inundation; however, plant responses to the interacting effects of water level and inundation duration are not fully understood. Methods: We conducted a mesocosm experiment on two wetland species, sawgrass (Cladium jamaicense) and muhly grass (Muhlenbergia filipes), that co‐dominate many freshwater wetlands in the Florida Everglades. We tracked photosynthesis, respiration, and growth at water levels of −10 (control), 10 (shallow), and 35 cm (deep) with reference to soil surface over 6 months. Results: The response of photosynthesis to inundation was nonlinear. Specifically, photosynthetic capacity (Amax) declined by 25% in sawgrass and by 70% in muhly grass after 1–2 months of inundation. After 4 months, Amax of muhly grass in the deep‐water treatment declined to near zero. Inundated sawgrass maintained similar leaf respiration and growth rates as the control, whereas inundated muhly grass suppressed both respiration and growth. At the end of the experiment, sawgrass had similar nonstructural carbohydrate pools in all treatments. By contrast, muhly grass in the deep‐water treatment had largely depleted sugar reserves but maintained a similar starch pool as the control, which is critical for post‐stress recovery. Conclusions: Overall, the two species exhibited nonlinear and contrasting patterns of carbon uptake and use under inundation stress, which ultimately defines their strategies of surviving regularly flooded habitats. The results suggest that a future scenario with more intensive inundation, due to the water management and climate change, may weaken the dominance of muhly grass in many freshwater wetlands of the Everglades. [ABSTRACT FROM AUTHOR]

Hydrilla verticillata (Hydrocharitaceae) is a submerged freshwater flowering plant within the monotypic genus. Over the geological periods, fossils of this family and genus have shown distinct diversifications between warm and cool fluctuations with more adaptations occurring in warmer periods and suppressions during severely cold paleoclimate changes. Recently, H. verticillata has shown a wide range of adaptive plasticity, allowing successful proliferation into non‐native regions, whilst also undergoing unexplained disappearance from its native localities, and this phenomenon has stimulated this inquiry. Against this somewhat complex background, particular interest for this investigation has been focussed on an understanding of which aspects of climate change have contributed towards global adaptations and distribution patterns of H. verticillata. Whilst it is recognised that some of these changes are natural, other aggravating impacts are due to anthropogenic influences. Identifying the appropriate combinations of these climatic factors (temperature, rainfall, photoperiod), in concert with environmental (water level, CO2, salinity, eutrophication), geographical (altitude, latitude) and other factors (UV‐B) are necessary precursors for instituting appropriate management strategies. In this respect, control measures are needed in non‐native regions and restoration of this plant in native habitats are essential for its ecologically balanced global distribution. [ABSTRACT FROM AUTHOR]

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. ​ [ABSTRACT FROM AUTHOR]

Although there is a sizeable budget for biosecurity management in New Zealand, there will never be sufficient resources to intervene in all incursions of harmful species, including invasive freshwater plants. Given the inherent complexity in making decisions on interventions, responses are often decided in relation to specific incursions as they happen within their particular context. This paper uses New Zealand case studies to test if there are general economic principles related to intervention in invasive freshwater plants which can be used to improve decision-making. The general principles were; the sooner eradication is started and/or the smaller the incursion size, the lower the cost will be; eradication is more expensive than alternative responses in the short term but is cheaper than long term impacts of no intervention and/or ongoing control programs; and preventing new incursions is cheaper in the long run than eradication. The three principles were considered to be logical in an economic sense and can contribute to supporting intervention decision-making at a macro-level (i.e. across the majority of incursions) and provide more holistic outcomes for society in relation to management programs. [ABSTRACT FROM AUTHOR]

The global and seemingly unstoppable spread of invasive alien plants emerges as one of the main topics of current science. This is due to the multiple repercussions of invasive plants on biodiversity and ecosystem functioning, plus huge consequences on human existence. In freshwaters, lots of invaders are extremely competitive by virtue of their idiosyncratic reproductive and adaptive strategies. As "inland islands", freshwaters seem particularly prone to changes when invaded, such as reorganisation of food webs and biotic interactions. Together, these events are self-reinforcing, implying hardly reversible hysteric phenomena. The intention of this paper is to point out: invasion pathways, driving factors, invasion mechanisms, and noticeable effects mediated by plant invaders in freshwaters through an extensive knowledge review. The growing evidence suggests the dawn of a new epochal phase: a globally alien-dominated "bio-historical horizon", tentatively called "Exocene", where invaders play predominant roles that drive freshwaters functioning and successional unexpected stages. In the context of invasion science, Exocene reinforces the need for an ecosystem-based perspective to properly understand the implications of plant invaders in freshwaters. Seven challenging issues emerge to be addressed to better outline the global paths of biodiversity and functioning between biomes when faced with biological invasion. [ABSTRACT FROM AUTHOR]

Although freshwater invasions have not been targeted for maintenance management or eradication as often as terrestrial invasions have, attempts to do so are frequent. Failures as well as successes abound, but several methods have been improved and new approaches are on the horizon. Many freshwater fish and plant invaders have been eliminated, especially by chemical and physical methods for fishes and herbicides for plants. Efforts to maintain invasive freshwater fishes at low levels have sometimes succeeded, although continuing the effort has proven challenging. By contrast, successful maintenance management of invasive freshwater plants is uncommon, although populations of several species have been managed by biological control. Invasive crayfish populations have rarely been controlled for long. Marine invasions have proven far less tractable than those in fresh water, with a few striking eradications of species detected before they had spread widely, and no marine invasions have been substantially managed for long at low levels. The rapid development of technologies based on genetics has engendered excitement about possibly eradicating or controlling terrestrial invaders, and such technologies may also prove useful for certain aquatic invaders. Methods of particular interest, alone or in various combinations, are gene-silencing, RNA-guided gene drives, and the use of transgenes. [ABSTRACT FROM AUTHOR]

Aim: Range size conservatism suggests that closely‐related species maintain geographic ranges of similar extent. However, consensus regarding this suggestion has not been reached. To shed more light on this phenomenon, we studied freshwater plant range size conservatism, range overlap and environmental niche conservatism using congeneric species comparison in two continents. In addition, we investigated whether a phylogenetic signal is found in the range sizes of aquatic plants. Location: Europe and North America. Taxon: Freshwater plants. Methods: Across spatial resolutions (50 km2, 100 km2 and 200 km2), we applied Spearman correlations among 347 and 730 pairs of congeneric species in Europe and North America, respectively, and 63 pairs shared between them. In addition, Spearman correlations were used to evaluate how the degree of spatial overlap influences range sizes and which environmental variables explain variation in range sizes. Brownian evolutionary model was used to assess the phylogenetic signal in species range sizes. Results: We found no evidence of range size conservatism across spatial resolutions for any species and species shared between the continents. In addition, range sizes of more closely related species did not overlap geographically more than those of distantly related ones and no support for environmental niche conservatism was evidenced. Main conclusions: We found that aquatic plants show no range size conservatism in the Northern Hemisphere. This means that it is challenging to define different range sizes of freshwater plants through species traits. Furthermore, we are unable to predict unknown distributions of extant aquatic plant species based on known distributional attributes of closely related species. However, our findings suggest that the interpretations of previous investigations on the range sizes of aquatic plants remain valid due to lack of range size conservatism. These practical implications encourage studying range size conservatism across realms and regions, especially for understudied organismal groups. [ABSTRACT FROM AUTHOR]

Caves are specific ecosystems with both biotic and abiotic characteristics. Turkey has approximately 20,000 caves, and the biology of most of them has yet to be studied. Kaklik Cave is sinkhole-shaped and its entrance is quite large. A mineral-rich spring forms travertine as it enters the cave giving it unique characteristics. The study aims to determine the algal flora of Kaklik Cave. A total of eighty-six taxa were identified. Among them, twenty-one taxa were recorded for the first time as freshwater algal flora of Turkey. Also, the relationships among the most effective environmental parameters, the most frequently found algae taxa composition, and sampling sites were observed. [ABSTRACT FROM AUTHOR]

The goal of this study was to investigate the effects of treated urban wastewater and different harvesting times on the yield and yield components of Sorghum (cv. Speed feed) in the greenhouse condition. The research was done based on a completely randomized design including 3 replications as pot planting in Ferdowsi university of Mashhad in 2016. In this study, the effects of four mixtures consisting of the moderations use of the treated urban wastewater and freshwater (0, 25, 75 and 100 percent mixture of treated urban wastewater and freshwater) and three harvesting times level (preflowering, after 50 percent of the plant to flowering, and grain filling stage) on the yield and yield components of Sorghum were evaluated. The results inducted that the effect of different moderations of irrigation regimes on all of them parameter was highly significant (P<0.01), but plant height was non-significant; it was also revealed that the effect of harvesting times on all of the parameters was highly significant (P<0.01), but leaf width was non-significant. The results also exhibited that the interaction effects of irrigated regimes and harvesting times on the leaf number, panicle length and width, leaf, panicle, and stem was highly significant (P<0.01), but plant height, stem diameter, branches number, and leaf length and width were significant at the 5 percent level (P<0.05). Also, the use of 25, 75, and 100 percent mixture of wastewater resulted in the forage yield of 37.5, -29.3, and 12.9 percent (pre-flowering); -31, -15.3, and -47.4 percent (after 50 percent of the plant to flowering), and -11.8, -35.7 and -28.4 percent (grain filling stage), respectively. The highest forage weights (46.2 g per plant) showed, in the study, irrigated by a mixture of 75 treated wastewater and 25 freshwater, and harvesting the plant after 50 percent in flowering stage; on the other hand, the best treatment in this study irrigation by the mixture of 75 treated wastewater and 25 freshwater and harvesting the plant after 50 percent in the flowering stage, Thus, using the treatment in farm experiment required the field research. [ABSTRACT FROM AUTHOR]

To comprehensively understand the impact of anthropogenic activities on biodiversity, we must understand how biodiversity has changed over time and what are the underlying processes. A growing body of evidence has shown that beta diversity reveals more about temporal changes in biodiversity compared with alpha diversity. Temporal beta diversity indicates, for example, degrees of change in species composition at single locations through time.We examined whether freshwater plant communities showed different patterns in temporal beta diversity in relation to concomitant changes in environmental conditions across decades. To do this, we used presence–absence data of lake plants for five decades (1940s–2010s) from southern Finland and calculated temporal beta diversity indices (TBI) for each lake between pairs of decades to the whole community, hydrophytes and helophytes. To get insights into possible processes behind the observed trends, we decomposed TBIs into beta diversity contributed by either temporal losses or temporal gains of species. We related TBIs and their loss and gain components to lake landscape position and changes in environmental variables.Based on comparisons of TBIs between the survey decade pairs, the temporal change in aquatic plant communities was modest through decades. Hydrophyte assemblages have changed more than helophyte assemblages. The main changes in temporal beta diversity occurred from the 1940s to the 1970s, when the gain of new species was the dominant process in the lakes throughout the landscape. Following that period, there was only modest changes, but from the 2000s to the 2010s, the dominant process was the loss of species. Temporal changes in environmental conditions played a key role in explaining the TBI.Our results showed that relying on only two survey points in time can result in limited knowledge of the ecological phenomenon under study and, for example, an exceptional year in terms of weather conditions can hinder detecting overall long‐term trends in compositional changes. Therefore, future studies should try to combine data from several decades to overcome the typical limitations of temporal information. [ABSTRACT FROM AUTHOR]

With the rapidly expanding global nuclear industry, more efficient and direct radiological monitoring approaches are needed to ensure the associated environmental health impacts and risk remain fully assessed and undertaken as robustly as possible. Conventionally, radiological monitoring in the environment consists of measuring a wide range of anthropogenically enhanced radionuclides present in selected environmental matrices and using generic transfer values for modelling and prediction that are not necessarily suitable in some situations. Previous studies have found links between taxonomy and radionuclide uptake in terrestrial plants and freshwater fish, but the marine context remains relatively unexplored. This preliminary study was aimed at investigating a similar relationship between brown seaweed, an important indicator in radiological monitoring programmes in the marine environment, and Caesium-137, an important radionuclide discharged to the marine environment. A linear mixed model was fitted using REsidual Maximum Likelihood (REML) to activity concentration data collected from literature published worldwide and other databases. The output from REML modelling was adjusted to the International Atomic Energy Agency (IAEA) quoted transfer value for all seaweed taxa in order to produce mean estimate transfer value for each species, which were then analysed by hierarchical ANalysis Of VAriance (ANOVA) based on the taxonomy of brown seaweeds. Transfer value was found to vary between taxa with increasing significance up the taxonomic hierarchy, suggesting a link to evolutionary history. This novel approach enables contextualisation of activity concentration measurements of important marine indicator species in relation to the wider community, allows prediction of unknown transfer values without the need to sample specific species and could, therefore, enhance radiological monitoring by providing accurate, taxon specific transfer values for use in dose assessments and models of radionuclide transfer in the environment. • Pre-existing data collated for Cs137 activity in brown seaweeds. • REML generated TFs are more representative of the brown seaweed community. • Taxonomic patterns provide useful tool for prediction and dose assessment. [ABSTRACT FROM AUTHOR]

Questions: The historical composition of landscapes is recognized as an important factor for explaining plant diversity, because species assemblages are not only patterned by current ecological conditions, but also represent legacies of the past. Contrary to terrestrial ecosystems, the influence of history has rarely been considered for aquatic communities. Here, we examined the effect of past land use on aquatic plant communities of freshwater shallow lakes. We first aimed to identify the relevant scale for studying landscape effects on macrophyte communities and then to test the relative influence of environmental variables and past and recent land use on aquatic plant assemblages. Location: Atlantic coastline, southwestern France. Methods: We surveyed shoreline macrophyte communities of 17 lakes and used species accumulation curves to estimate taxonomic richness. We used water chemistry and lakes' morphological features as environmental variables and reconstructed land‐use occupancies of lakes' watershed with aerial pictures of 1945, 1965, 1985 (past) and 2002 (recent). We examined landscape change with principal component analysis and taxonomic composition with non‐metrical multidimensional scaling. We then evaluated the relative influence of morphological, chemical, past and recent land‐use factors on taxonomic richness and composition with variation partitioning methods. Results: We found that the studied landscapes exhibit a trend toward an increase of urban and arable fields areas at the expense of semi‐natural ones. Water chemical composition and past land use of the whole watershed (particularly urban and semi‐urban areas) were strongly inter‐correlated, and explained the major part of the variation of taxonomic richness and composition. Conclusions: These results underline the importance of historical factors in explaining aquatic plant diversity and suggest delayed responses of communities to anthropogenic pressures. Integrating historical factors in future analyses of aquatic ecosystems would thus greatly contribute to understanding ecological processes, and is crucial for the conservation and management of macrophyte communities. [ABSTRACT FROM AUTHOR]

In the Palaeogene, pollen assemblages at low and mid latitudes are characterized by abundant palm and palm-like (PPL) taxa. Although these taxa have been widely reported, their occurrence in the Palaeogene of Myanmar remains poorly documented. Here we report on the morphology of PPL pollen along a middle to upper Eocene sedimentary sequence in central Myanmar and discuss their nearest living relatives (NLRs). Principal components analysis (PCA) indicates that Palmaepollenites kutchensis , Dicolpopollis and Longapertites were dispersed from freshwater plants, whereas the parent taxon of Proxapertites operculatus was probably a member of the coastal vegetation in the manner of Spinizonocolpites. This, with sedimentological data, suggests a palaeoenvironmental change from a brackish, tidally influenced environment to a fully freshwater setting through the late Eocene. Additionally, we mapped and compared the geographical distribution of selected Eocene palm taxa and their NLRs, and found that their distributions shrank after the Eocene. Moreover, in the Palaeogene, species diversity of selected PPL taxa seems lower in Myanmar than in the Indian subcontinent and other regions in South-East Asia. We hypothesize that in the Eocene the Indo–Asian collision zone formed a 'hotspot' for palm diversity, which is reflected in species-rich palynofloras. However, the local palm diversity declined after the Eocene, whereas, at the global level, palm distribution was distinctly reduced between the Eocene and the present. We propose that the retreat of the palms may have occurred as early as the Eocene – Oligocene Transition (EOT), but this remains to be confirmed by the study of EOT pollen records in tropical regions. [ABSTRACT FROM AUTHOR]

Ongoing global environmental changes such as rising atmospheric CO2 concentration ([CO2]) and eutrophication are in some parts thought to facilitate exotic plant species invasions in freshwater systems. Although an increasing number of studies have documented the impacts of these factors on native and invasive freshwater plant species, relatively little is known about how they might interact to affect naturalised exotic species. We investigated the growth and biomass allocation responses of five naturalised ornamental freshwater plant species (Ludwigia palustris, Mentha aquatica, Mentha pulegium, Nasturtium officinale and Zantedeschia aethiopica) to varied levels of CO2 (ambient and elevated) and nutrient (low and high) concentrations. We found limited evidence that these factors interacted to affect plant growth and biomass allocation. However, the relative growth rate (RGR) of most of the species was enhanced under elevated [CO2] and/or nutrient enrichment. These results suggest that most of the tested study species will likely be of management concern under future global environmental change conditions. However, it is important that future research efforts test the potential shifts in the competitive interactions between native and exotic naturalised freshwater species in response to global environmental changes in order to determine community-level consequences of these changes. [ABSTRACT FROM AUTHOR]

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

The freshwater plant species Lemna minor suffers significantly in nutrient uptake and biomass accumulation performance when grown in saline effluents, such as those produced in brackish aquaculture operations. To determine the exact impact of salinity to these plant traits, this study measured the nutrient uptakes and biochemical composition of L. minor grown in synthetic aquaculture medium of increasing salinity levels. The overall trend for biomass growth showed that higher salinity levels resulted in lower growth with a mass gain of about 13% in 12.5 ppt medium compared with 96% in the control. However, the NO3– uptake appeared to be unaffected by differences in salinity. NH4+ uptake was significantly affected only at salinity concentrations of 10 ppt and 12.5 ppt. The relationship between PO43– uptake and salinity was less clear, as PO43– levels appeared to decrease linearly for all test groups and were shown to be statistically insignificant. At the end of the experiment period, the control medium showed the lowest measured COD levels, 17 mg/L while the 12.5 ppt solution has the highest COD level, 61 mg/L. Protein content showed a decline with increasing salinity of growth medium, while carbohydrate content was shown to be increasing. These preliminary data identify the general relationship between salinity and the measured criteria of L. minor and will subsequently serve as the basis for further remediation studies and the development of salinity mitigation methods. [ABSTRACT FROM AUTHOR]

Aims: Climate change (extreme rainfall) and water management activities have led to variation in hydrological regimes, especially inundation, which may alter the function and structure of wetlands as well as wetland-atmosphere carbon (C) exchange. However, the degree to which different inundation depths (standing water depth above the soil surface) affect ecosystem CH4 fluxes, ecosystem respiration (Reco) and net ecosystem CO2 exchange (NEE) remains uncertain in wetland ecosystems. Methods: We conducted a field inundation depth manipulation experiment (no inundation, i.e. only natural precipitation; 0, water-saturated; 5, 10, 20, 30 and 40 cm inundation depth) in a freshwater wetland of the Yellow River Delta, China. The CH4 fluxes, Reco and NEE were measured with a static chamber technique during the growing seasons (May–October) of 2018 and 2019. Results: Inundation depth significantly increased plant shoot density, above-water level leaf area index (WLAI), above-water level plant shoot height (WHeight), aboveground and belowground biomass of the dominant grass Phragmites australis in both years. Meanwhile, inundation depth increased the CH4 fluxes, Reco (except for 0 cm) and NEE compared to no inundation, which could be attributed partly to the increased plant productivity (shoot density, WLAI, WHeight, biomass). Additionally, the CH4 fluxes, Reco or NEE exhibited parabolic responses to inundation depth. Furthermore, global warming potential (GWP) was significantly decreased under different inundation depths during the growing season, especially from 5 to 40 cm inundation depth in 2019. NEE was the largest contributor to the seasonal GWP, which indicates that the inundated wetlands are a net sink of C and have a cooling climate effect in the Yellow River Delta. Conclusions: Inundation depth substantially affects the magnitude of CH4 fluxes, Reco and NEE, which were correlated with altered plant traits in wetland ecosystems. Inundation depth could mitigate greenhouse gas emissions in the P. australis wetlands during the growing season. Inundation depth-induced ecosystem C exchange should be considered when estimating C sequestration capacity of wetlands due to climate change and water management activities, which will assist to accurately predict the impact of hydrological regimes on C cycles in future climate change scenarios. [ABSTRACT FROM AUTHOR]

The paper presents the results of the analysis of diatoms from surface sediments (stones, sands) and macroflora (seagrass, macroalgae) collected at 16 sampling sites located along the inner coastal zone of Puck Bay (southern Baltic Sea) along the Hel Peninsula. The main diatom species of epilithon, epipsammon and epiphyton were characterized with respect to their autecological preferences (habitat, salinity, trophic status, saprobity). Three groups of diatoms were distinguished with respect to the type of substrate based on the results of benthic flora analysis: diatoms (i) of one type of substrate, (ii) of two types and (iii) those occurring on all types of substrates. Moreover, the distribution of benthic diatom communities indicates ecological differences in the study area. Marine and brackish-water species were observed in large numbers in the coastal zone of the Outer Puck Bay, whereas freshwater flora occurred with a higher frequency in the coastal zone of the Puck Lagoon. The content of polysaprobionts and of α-mesosaprobionts indicates that the region of the Hel Tip is highly eutrophicated and very polluted. The coast in the vicinity of Kuznica is less polluted, whereas the best environmental conditions are found in the Jurata–Jastarnia region, as evidenced by the frequency of diatoms that are β-mesosaprobionts. [ABSTRACT FROM AUTHOR]

• Abundances, δ2H and δ13C values of n -alkanes were measured from plants across a coastal wetland. • Most of the geochemical proxies differed among plant habitats and between leaves and roots. • Differences in the isotopic values are larger among plants than between the leaves and roots. • PCA is a valuable tool differentiating organic matter source in coastal wetland sediments. Reconstructing past responses of coastal wetlands to climate change contextualizes ongoing and future developments in these globally important ecosystems. The molecular distributions and stable isotope ratios (δ2H and δ13C) of sedimentary plant wax n -alkanes are frequently used to infer past vegetation and hydroclimate changes in wetland systems. However, there is limited modern information available about these compounds in subtropical wetlands. Here we analyzed mature leaves from 30 typical plant species and roots from 6 plant species collected in the Florida Everglades, including tree island plants, freshwater wetland plants, mangroves, and seagrass. The n -alkane abundance (2 to 884 µg/g dry weight), percent of aquatic plants ratio (P aq , 0 to 1), average chain length (ACL 23-33 , 24.0–30.7), concentration weighted average (CWA) δ2H (−231 to −78‰) and δ13C values (−38.9 to −14.4‰) spanned wide ranges with plant growth habit. Significant differences in n -alkane abundances, P aq , ACL 23-33 , CWA δ2H and δ13C values were found to exist between the leaves and roots of some emergent aquatic plants. Simple mass balance calculations of wetland aquatic plants suggest that long chain n -alkanes (e.g., C 29 n -alkanes) are predominantly derived from leaves rather than roots in wetland surface sediments/soils. However, the contribution from mid-chain n -alkanes (e.g., C 23 n -alkane) from roots may be equal to or greater than those from leaves. This implies that the differences in the isotopic compositions between root and leaf derived material need to be taken into account when interpreting down core changes in mid-chain n -alkane δ2H and δ13C values, which may be derived from variable contributions from leaves and roots rather than a change in hydroclimate or vegetation. Considering the large variation in both n -alkane distribution proxies and isotopic composition, no single molecular index or stable isotope ratio can capture multivariate changes of wetland ecosystems in the past. Nevertheless, principal component analysis shows promising potential to resolve different plant functional types. Paleo-reconstruction of subtropical aquatic ecosystems using n -alkanes will be most useful if the full molecular and isotopic distribution information of plant waxes are used. [ABSTRACT FROM AUTHOR]

The latitudinal diversity gradient hypothesis suggests that species richness should be highest at low latitudes, whereas Rapoport's rule states that largest ranges ought to be found for species at high latitudes. However, there is no consensus over these patterns and their underlying drivers in the freshwater realm.We investigated species richness and mean range size of freshwater plants in 50 × 50 km grid cells across Europe (40°N–71°N) and North America (25°N–78°N), supplemented with data based on 1° latitudinal bands for mean range size. We were especially interested to find out whether there are similarities and differences in these ecogeographical patterns and their underlying drivers between the continents due to their contrasting historical characteristics, spatial extent and topography.First, we used partial regression to reveal whether species richness and mean range size of freshwater plants have a linear or quadratic relationship with latitude. Second, we employed variation partitioning based on partial regression to model relationships between plant species richness and mean range size and four explanatory variable groups (i.e. environmental features, current climate, historical climate and geographical location). Third, we utilized boosted regression tree analysis to further investigate species richness and mean range size of freshwater plants in relation to a set of explanatory variables.Our results revealed that species richness showed relatively similar patterns in relation to latitude between the continents. Similarly, mean range size trends were alike in North America whether we used 50 × 50 km grid cell data or 1° latitudinal bands. Instead, different patterns in mean range size emerged between the used datasets in Europe. For both species richness and mean range size, current climate (with different individual predictor variables) was the main driver in both the continents, but historical effects had a small influence on the response variables.Synthesis. Our findings indicated that major ecogeographical rules can strongly vary for the same taxonomic group across broad scales between continents. It is also premature to rely solely on well‐known terrestrial taxonomic groups when drawing generalizations about ecogeographical rules. [ABSTRACT FROM AUTHOR]

The circadian clocks in chlorophyte algae have been studied in two model organisms, Chlamydomonas reinhardtii and Ostreococcus tauri. These studies revealed that the chlorophyte clocks include some genes that are homologous to those of the angiosperm circadian clock. However, the genetic network architectures of the chlorophyte clocks are largely unknown, especially in C. reinhardtii. In this study, using C. reinhardtii as a model, we characterized RHYTHM OF CHLOROPLAST (ROC) 75, a clock gene encoding a putative GARP DNA-binding transcription factor similar to the clock proteins LUX ARRHYTHMO (LUX, also called PHYTOCLOCK 1 [PCL1]) and BROTHER OF LUX ARRHYTHMO (BOA, also called NOX) of the angiosperm Arabidopsis thaliana. We observed that ROC75 is a day/subjective day-phase-expressed nuclear-localized protein that associates with some night-phased clock genes and represses their expression. This repression may be essential for the gating of reaccumulation of the other clock-related GARP protein, ROC15, after its light-dependent degradation. The restoration of ROC75 function in an arrhythmic roc75 mutant under constant darkness leads to the resumption of circadian oscillation from the subjective dawn, suggesting that the ROC75 restoration acts as a morning cue for the C. reinhardtii clock. Our study reveals a part of the genetic network of C. reinhardtii clock that could be considerably different from that of A. thaliana. Author summary: Circadian clock genes are not well-conserved during evolution, and the evolutionary history of circadian clocks is largely unknown. Green plants consist of two main clades: the Streptophyta (includes land plants and a part of freshwater green algae), and the Chlorophyta (includes a wide range of marine and freshwater green algae). Although the circadian clocks in chlorophyte algae include some components that are homologous to those of the circadian clock in flowering plants, it is not fully understood whether the chlorophyte clocks tick in the same manner as the flowering plant clocks. In this study, we characterized ROC75, a clock-related putative transcription factor, in the freshwater green alga Chlamydomonas reinhardtii. We found that ROC75 is a daytime repressor for the circadian clock in this alga, in contrast to its homologous protein, LUX (PCL1), which is known as a nighttime repressor for the flowering plant clock. Our study can serve as a step toward understanding the evolutionary history of circadian clocks in green plants. [ABSTRACT FROM AUTHOR]

Background and Aims Ottelia alismoides (Hydrocharitaceae) is a freshwater macrophyte that, unusually, possesses three different CO2-concentrating mechanisms. Here we describe its leaf anatomy and chloroplast ultrastructure, how these are altered by CO2 concentration and how they may underlie C4 photosynthesis. Methods Light and transmission electron microscopy were used to study the anatomy of mature leaves of O. alismoides grown at high and low CO2 concentrations. Diel acid change and the activity of phosphoenolpyruvate carboxylase were measured to confirm that CAM activity and C4 photosynthesis were present. Key Results When O. alismoides was grown at low CO2, the leaves performed both C4 and CAM photosynthesis whereas at high CO2 leaves used C4 photosynthesis. The leaf comprised an upper and lower layer of epidermal cells separated by a large air space occupying about 22 % of the leaf transverse-section area, and by mesophyll cells connecting the two epidermal layers. Kranz anatomy was absent. At low CO2, chloroplasts in the mesophyll cells were filled with starch even at the start of the photoperiod, while epidermal chloroplasts contained small starch grains. The number of chloroplasts in the epidermis was greater than in the mesophyll cells. At high CO2, the structure was unchanged but the thicknesses of the two epidermal layers, the air space, mesophyll and the transverse-section area of cells and air space were greater. Conclusions Leaves of O. alismoides have epidermal and mesophyll cells that contain chloroplasts and large air spaces but lack Kranz anatomy. The high starch content of mesophyll cells suggests they may benefit from an internal source of CO2, for example via C4 metabolism, and are also sites of starch storage. The air spaces may help in the recycling of decarboxylated or respired CO2. The structural similarity of leaves at low and high CO2 is consistent with the constitutive nature of bicarbonate and C4 photosynthesis. There is sufficient structural diversity within the leaf of O. alismoides to support dual-cell C4 photosynthesis even though Kranz anatomy is absent. [ABSTRACT FROM AUTHOR]

We investigated the effect of nano‐ and microplastics on the freshwater duckweed species Spirodela polyrhiza, a vascular plant. S. polyrhiza was exposed for 120 h to concentrations ranging from 102 to 106 particles·mL−1. We assessed effects on growth and chlorophyll production, and explored adsorption and absorption by way of confocal microscopy. For both nano‐ and microsized particles, no concentration‐dependent effects on growth were found (expressed as fresh weight, frond, and root sizes). In addition, chlorophyll concentrations were not significantly affected. Confocal microscopy indicated that nanosized plastic particles adsorbed externally to the duckweed, especially to the roots. Internalized plastic particles could not be detected. Nevertheless, given their important role in ecosystems as a food source for a range of organisms, the adsorption of plastic particles to S. polyrhiza roots as detected in this study can result in the transfer of plastic particles to diverse herbivorous species within the ecosystem. [ABSTRACT FROM AUTHOR]

Parallel with the research of Bacillariophyta flora in the well with shadoof on the area of Semberija was researched Bacillariophyta flora of other freshwater systems that are located in the near or distant environment from the researched wells, such as Drenovaĉa swamp, Sava river, Jelaz canal, artesian wells and ephemeral swamps. It is very interesting to compare Bacillariophyta flora that inhabits wells and Bacillariophyta flora of Drenovaĉa swamp that is only a dozen meters away from the researched well of Lazić Mijo, a local in the village Velino Selo. All identified Bacillariophyta in researched well belong to aerophile, which indicates on certain ecology of the well, that is a specific life conditions that are present in wells as anthropogenic creations. Contrary to the well flora, Bacillariophyta flora of Drenovaĉa swamp is composed party of algae belonging to benthos. In Lazić Mijo well were identified 33Bacillariophyta, all aerophile, while in Drenovaĉa swamp were identified 57 Bacillariophyta, from which only 18 are aerophile and others belong to benthos. Considering that Bacillariophyta is a component of aeroplankton, and that via air currents can be transmitted over long distances, it is assumed that similarly aerophile Bacillariophyta were transmitted on mosses associations on the well wall, manifested their adaptive attributes in such biotopes, and by that became autochthonous flora of the well. Large qualitative differences in Bacillariophyta flora in wells with shadoof and in Bacillariophyta flora of Drenovaĉa swamp also indicate on autochthony of Bacillariophyta flora of the well, which means that species were not transmitted from the neighborhood. [ABSTRACT FROM AUTHOR]

We report the freshwater heteronemertean Apatronemertes albimaculosa Wilfert & Gibson, 1974 for the first time from Taiwan based on specimens collected under stones and rocks on gravelly bottom near the shore of a brook in Nantun District, Taichung City. Species identification was corroborated by mitochondrial cytochrome c oxidase subunit I gene sequences. The species had been reported from aquaria with tropical freshwater plants in Germany, Austria, USA, Spain, and Japan, before it was discovered from wild environment in Panama. Our report represents the second instance of field-caught A. albimaculosa in the world. [ABSTRACT FROM AUTHOR]