Growth, gas exchange, and leaf anatomy of Echinodorus grandiflorus (Cham. & Schltr.) Micheli under Pb contamination.

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.

Fluvial avulsions influence soil fertility in the Pantanal wetlands (Brazil).

River avulsions drive important changes in the Pantanal wetlands, owing to their role in the hydro-sedimentology of the region. Although relevant to numerous ecosystem services, few studies have analyzed the influence of river avulsions on soil fertility in the Pantanal. Here, we use the largest ongoing avulsion in the Taquari River (Caronal region) to evaluate the effects on soil fertility, considering two factors: avulsion stage (1) and aquatic-terrestrial succession (2). Since both factors are influenced by macrophyte abundance, an incident map was created through tasseled cap indices from Sentinel 2 images to guide sampling efforts in flooded soils. The mapped area was split into two zones of alluvial processes, the first from the apex of the Caronal lobe corresponding to the Taquari River megafan (TRM), and the second as the distal Paraguay River floodplain (PRF). Soil macro- and micronutrient levels were evaluated from 42 surface samples (0-0.2 m) distributed across the two alluvial process zones. The macrophyte map's overall accuracy (OA) was analyzed by a confusion matrix using the Sentinel 2 imagery. Finally, we used Random Forest regressions to determine the influence of response variables on soil attributes, including tassel indices, distance from the Caronal crevasse, macrophyte density, and an existing soil fertility map. The macrophyte map obtained an OA of 93 %. Some parameters such as pH (r = -0.62; R2 = 0.57), effective cation exchange capacity (r = -0.49; R2 = 0.79), Mn (r = -0.71; R2 = 0.6), Zn (r = -0.69; R2 = 0.54), and base saturation (r = -0.7; R2 = 0.93) were influenced by the distance or level of maturation of the avulsion stage in the TRM. Our scattering of soil collections was insufficient to test the terrestrialization hypothesis (2). The study results show that river channel avulsions influence the accumulation of mineral and organic nutrients in tropical floodplain soils, which has implications for fertility and biodiversity.

Single and combined phytoextraction of lead and cadmium on submerged plants Potamogeton pusillus L.: removal, bioaccumulation pattern, and phytotoxicity.

Under the present investigation, the submerged plant Potamogeton pusillus has been tested for the removal of lead (Pb) and cadmium (Cd). P. pusillus removal efficiency and accumulation capacity were examined in separated Pb and Cd solutions, at 0.5, 1.0, and 2 mg L-1, and in solutions where both metals were present at the same concentration (0.5, 1.0, and 2 mg L-1), under laboratory conditions for 3, 7, and 10 days. Also, we examined the removal efficiency and accumulation capacity when a set of plants were exposed to 0.5 mg L-1 of Pb (or Cd) and increasing concentrations (0.5, 1, and 2 mg L-1) of Cd (or Pb) for 10 days. The effect of Cd and Pb was assessed by measuring changes in the chlorophylls, carotenoids, and malondialdehyde contents. Results showed that P. pusillus could accumulate Cd and Pb from individual solutions. Roots and leaves accumulated the highest amount of Cd and Pb followed by the stems. Some phytotoxic effects were observed, especially at individual Cd exposures, but these effects were not observed in the two-metal system. The removal and accumulation of Pb by P. pusillus were significantly enhanced in the presence of Cd under certain conditions, presenting a good alternative for the removal of these metals from polluted aquifers. To the extent of our knowledge, this is the first report on both enhanced phytoextraction of Pb in the presence of Cd and bioaccumulation of these heavy metals by P. pusillus.

Removal of enrofloxacin using Eichhornia crassipes in microcosm wetlands.

The global consumption of antibiotics leads to their possible occurrence in the environment. In this context, nature-based solutions (NBS) can be used to sustainably manage and restore natural and modified ecosystems. In this work, we studied the efficiency of the NBS free-water surface wetlands (FWSWs) using Eichhornia crassipes in microcosm for enrofloxacin removal. We also explored the behavior of enrofloxacin in the system, its accumulation and distribution in plant tissues, the detoxification mechanisms, and the possible effects on plant growth. Enrofloxacin was initially taken up by E. crassipes (first 100 h). Notably, it accumulated in the sediment at the end of the experimental time. Removal rates above 94% were obtained in systems with sediment and sediment + E. crassipes. In addition, enrofloxacin was found in leaves, petioles, and roots (8.8-23.6 µg, 11-78.3 µg, and 10.2-70.7 µg, respectively). Furthermore, enrofloxacin, the main degradation product (ciprofloxacin), and other degradation products were quantified in the tissues and chlorosis was observed on days 5 and 9. Finally, the degradation products of enrofloxacin were analyzed, and four possible metabolic pathways of enrofloxacin in E. crassipes were described.

Diet composition affects the rearing of Mansonia humeralis (Diptera: Culicidae) immatures under laboratory conditions

ABSTRACT Mansonia Blanchard mosquitoes are aggressive and opportunistic, making it difficult for habitation in certain areas. However, there is no data regarding their rearing in laboratory in Brazil. Therefore, the aim of this study was to evaluate the effect of different diet composition on the development of Mansonia humeralis immatures. The plant Pistia stratiotes was used as a substrate for larval attachment, and fish food (Tetra Marine® Flakes) and baker's yeast (Saccharomyces cerevisiae) in various combinations were used as feed. Eggs and larvae were obtained from mosquitoes collected in the field using protected human catches, and the experiments were conducted in the laboratory (25-27°C and 70-80% relative humidity) with 200 larvae per container (n=15). Mortality rate, larval development time, pupation rate, emergence rate, and the number of eggs and larvae were recorded. Overall, a high mortality rate (0.5 - 0.7) was observed in the first 12 days of the experiment in all diets, up to 50% of adults emerged from the remaining larvae with a male to female ratio of 1.1 to 1.3. The use of yeast in combination with fish food resulted in lower mortality rate (0.52), a shorter larval development time (34 days), a higher pupation rate (0.21) and number of eggs (21 eggs) compared to the other diets. However, fertility was very low (1%) regardless of the diet used. The use of yeast is recommended as part of the diet offered to this mosquito species under the laboratory conditions used in our study.

Land use impact on mercury in sediments and macrophytes from a natural lake in the Brazilian savanna.

Freshwater ecosystems are essential to human and wildlife survival. They harbor a wide biodiversity that contributes to ecosystem services. In the ecosystem of the Brazilian Savanna, anthropic activities related to environmental pollution that includes mercury (Hg) is of concern. We studied total mercury concentrations ([THg]) in bottom sediments and macrophytes to assess its short-term (2012 and 2019) impact on a natural lake. Temporal changes in [Hg] were assessed with the geoaccumulation index (Igeo) and the sediment quality guidelines (SQG). The land use index (LUI) was used to assess differences in anthropogenic activities and the Normalized Difference Aquatic Vegetation Index (NDAVI) was used to assess macrophyte biomass density. The bioaccumulation factor (BAF) was used to assess Hg accumulation in macrophytes relative to sediments. The LUI showed an increase in the intensity of agricultural activities in the vicinities of the lake. The NDAVI indicated an increase in the density of macrophytes in the evaluated period. The Igeo indicated that in all sampling sites, pollution levels in sediments increased in 2019 (Igeo > 0), with concentrations exceeding the SQG in 2019. In 2012, [THg] in sediments ranged from 20.7 to 74.6 ng g-1, and in 2019 they ranged from 129.1 to 318.2 ng g-1. In macrophytes, [THg] ranged from 14.0 to 42.1 ng g-1 in 2012, to 53.0 and 175.3 ng g-1 in 2019. [THg] in bottom sediments and macrophytes were significantly higher in the second collection period (p < 0.05). There was no significant difference in BAF values between the periods and no significant bioaccumulation in macrophytes (BAF <1). Our results demonstrated that the macrophytes are not sensitive indicators of Hg pollution in lentic environments of the Brazilian Savanna; however, the increased land use intensity (agriculture, automotive traffic, and urban infrastructure) could increase Hg accumulation in sediments and macrophytes in a short time interval.

Oxygen consumption and formation of recalcitrant organic carbon from the decomposition of free-floating macrophyte leachates.

Aquatic macrophytes contain high levels of hydrosoluble compounds. These compounds disproportionately support microbial breakdown and affect biological oxygen demand in eutrophic waters. In this study, we investigated the fate of leachates from free-floating macrophytes (Pistia stratiotes and Eichhornia crassipes) usually present in eutrophic tropical lacustrine environments. After extraction, the leachates were fractioned into high and low molecular weight compounds and incubated under aerobic conditions, in the dark and at 20.0 ± 1.3 °C. The concentrations of dissolved oxygen and the total, dissolved, and particulate organic carbon (TOC, DOC, and POC) were determined during 60 days. The selected leachates supported the detritus trophic chain of the Barra Bonita Reservoir. High rates of carbon transfer were measured, which were ascribed to the temperature selected (20 °C), nutrient availability, and labile fractions of the leachates. Decomposition occurred mainly through catabolic pathways (mineralization), with the formation of POC (immobilization) being only minor. In the early stages of P. stratiotes and E. crassipes decomposition, the mineralization of leachates (mainly the low molecular weight) led to declines in dissolved oxygen. Owing to the low rates of mass loss, the recalcitrant fractions of these leachates should constitute the main forms of organic carbon exported from the reservoir.

Influence of seasonal variation to the population growth and ecophysiology of Typha domingensis (Typhaceae).

Precipitation is an important climatic element that defines the hydrological regime, and its seasonal variation produces annual dry and wet periods in some areas. This seasonality changes wetland environments and leverages the growth dynamics of macrophytes present, including Typha domingensis Pers. This study aimed to evaluate the influence of seasonal variation on the growth, anatomy and ecophysiology of T. domingensis in a natural wetland. Biometric, anatomical and ecophysiological traits of T. domingensis were evaluated over one year at four-month intervals. Reductions in photosynthesis were evidenced at the end of the wet periods and during the dry periods, and these reductions were associated with thinner palisade parenchymas. Increased stomatal indexes and densities as well as thinner epidermis observed at the beginning dry periods can be associated with higher transpiration rates during this period. The plants maintained their water contents during the dry periods, which may be related to the storage of water in leaf trabecular parenchyma, as this is the first time that results indicate the function of this tissue as a seasonal aquiferous parenchyma. In addition, increasing proportions of aerenchymas were evident during the wet periods, which may be related to a compensation mechanism for soil waterlogging. Therefore, the growth, anatomy and ecophysiology of T. domingensis plants change throughout the year to adjust to both the dry and wet periods, providing conditions for the survival of the plants and modulating population growth.

Cr(III) and Cr(VI) removal in floating treatment wetlands (FTWs) using Typha domingensis.

Floating treatment wetlands (FTWs) are a cost-effective ecological engineering tool for the restoration of polluted water bodies. The aims of this work were to evaluate the removal of Cr(III) and Cr(VI) by FTWs using Typha domingensis, and to assess Cr accumulation and distribution in plant tissues and sediment. Treatments were 5 and 10 mg L-1 of Cr(III), and 5 and 10 mg L-1 of Cr(VI), with and without FTWs, and biological control (BC) with FTW without Cr addition. Both Cr species were efficiently removed from water in all treatments (Cr removal > 80%). Cr concentration in sediments of treatment without FTWs was significantly higher than in sediments of treatments with FTWs, indicating that T. domingensis was directly involved in Cr removal. In sediment, Cr was mainly bound to the organic matter in all treatments with a low risk of future release under FTW conditions. T. domingensis demonstrated tolerance to both Cr species at 5 and 10 mg L-1 with Cr accumulated mainly in the roots in all treatments. The use of FTWs planted with T. domingensis is a suitable tool to remediate water bodies contaminated with Cr.

This study evaluates the removal efficiency of Cr(III) and Cr(V) in Floating Treatment Wetlands planted with Typha domingensis in greenhouse experiments. Cr accumulation and distribution in plant tissues and different sediment fractions were also assessed.

Multiple endpoints of polyethylene microplastics toxicity in vascular plants of freshwater ecosystems: A study involving Salvinia auriculata (Salviniaceae).

More recently, the number of studies on the impacts of microplastics (MPs) on plants has drawn attention considerably. However, many of these studies focused on terrestrial plants, with vascular plants from freshwater ecosystems being little studied. Thus, we aimed to evaluate the possible effects of exposure of Salvinia auriculata, for 28 days, to different concentrations of polyethylene MPs (PE MPs - diameter: 35.46 ± 18.17 µm) (2.7 ×108 and 8.1 ×108 particles/m3), using different biomarkers. Our data indicated that exposure to PE MPs caused alterations in plant growth/development (inferred by the lower floating frond number, "root" length, and the number of "roots"), as well as lower dispersion of individuals in the experimental units. Plants exposed to PE MPs also showed lower epidermal thickness (abaxial leaf face) and a longer length of the central leaf vein and vascular bundle area. Ultrastructural analyses of S. auriculata exposed to MPs revealed rupture of some epidermal cells and trichomes on the adaxial and abaxial, leaf necrosis, and chlorosis. In the "roots", we observed dehydrated filamentous structures with evident deformations in plants exposed to the pollutants. Both on the abaxial leaf face and on the "roots", the adherence of PE MPs was observed. Furthermore, exposure to PE MPs induced lower chlorophyll content, cell membrane damage, and redox imbalance, marked by reduced catalase and superoxide dismutase activity and increased production of reactive oxygen and nitrogen species as well as malondialdehyde. However, in general, we did not observe the dose-response effect for the evaluated biomarkers. The values of the integrated biomarker response index, the principal component analysis (PCA) results and the hierarchical clustering analysis confirmed the similarity between the responses of plants exposed to different PE MPs concentrations. Therefore, our study sheds light on how PE MPs can affect S. auriculata and reinforces that putting these pollutants in freshwater environments might be hazardous from an ecotoxicological point of view.

Resistance evaluation of Canna indica, Cyperus papyrus, Iris sibirica, and Typha latifolia to phytotoxic characteristics of diluted tequila vinasses in wetland microcosms.

Tequila vinasse has a high contaminating capacity due to its physicochemical characteristics. Efficient and low-cost alternative treatments are required to reduce and control the environmental impacts caused by raw vinasse discharges, mainly from micro and small factories. One option is wetland technologies in which vegetation plays an important role in the proper functioning of the system; thus, the species to be used must be properly selected based on their resistance and tolerance to the toxic effects of vinasse. Therefore, this study aims to evaluate the resistance of four macrophyte species to tequila vinasse in wetland microcosms that is, Canna indica, Cyperus papyrus, Iris sibirica, and Typha latifolia which were exposed to 5, 7, 10, 12, and 15% of vinasse diluted with domestic wastewater. The control parameters (relative content, evapotranspiration, pH, electrical conductivity, and apparent color) showed that the plants in general developed stress symptoms. However, statistical analysis revealed a significant difference (p < 0.05) between plant species and vinasse treatments, further evidencing that I. sibirica is the species with the greatest potential to be used as emergent vegetation in treatment wetlands for the purification of tequila vinasse.

The novelty of this study lies in the fact that different species of macrophytes have been evaluated to find those with the capacity to resist the physicochemical characteristics of tequila vinasses; corroborating that there are more appropriate species than others. I. sibirica stood out mainly based on its better physiological response to the Relative Chlorophyll Content, which is the most important parameter for the evaluation of plant health. In this way, the results of this study will allow the evaluation of different types of constructed wetlands for the treatment of tequila vinasse. The knowledge generated is useful for treating other distillery stillages around the world with wetland technology.

The aquatic macrophyte Salvinia molesta mitigates herbicides (glyphosate and aminomethylphosphonic acid) effects to aquatic invertebrates.

We evaluated the individual and combined effects of different environmentally representative concentrations of glyphosate (0, 25, 50, 75, and 100 µg l-1) and aminomethylphosphonic acid (AMPA; 0, 12.5, 25, 37.5, and 50 µg l-1) on the physiology of Aedes aegypti larvae, as well as the capacity of the aquatic macrophyte Salvinia molesta to attenuate those compounds' toxicological effects. Larvae of Ae. aegypti (between the third and fourth larval stages) were exposed for 48 h to glyphosate and/or AMPA in the presence or absence of S. molesta. Glyphosate and AMPA induced sublethal responses in Ae. aegypti larvae during acute exposures. Plants removed up to 49% of the glyphosate and 25% of AMPA from the water, resulting in the exposure of larvae to lower concentration of those compounds in relation to media without plants. As a result, lesser effects of glyphosate and/or AMPA were observed on larval acetylcholinesterase, P450 reductase, superoxide dismutase, mitochondrial electron transport chain enzymes, respiration rates, and lipid peroxidation. In addition to evidence of deleterious effects by media contamination with glyphosate and AMPA on aquatic invertebrates, our results attest to the ability of S. molesta plants to mitigate the toxicological impacts of those contaminants.

Short-duration exposure of 3-µm polystyrene microplastics affected morphology and physiology of watermilfoil (sp. roraima).

Microplastics are one of the most widely discussed environmental issues worldwide. Several studies have shown the effect of microplastic exposure on the marine environment; however, studies on freshwater systems are lacking. This study was conducted to investigate the effect of microplastics on hydroponically growing emergent freshwater macrophytes, watermilfoil (sp. roraima) under controlled environmental conditions. Plants were exposed to 0 mg L-1 (control), 0.05 mg L-1, 0.25 mg L-1, 1.25 mg L-1, and 6 mg L-1 of 3-µm polystyrene microspheres for 7 days. The oxidative stress, antioxidant response, pigmentations, Fv/Fm, and growth parameters in the above-water and below-water parts were analyzed separately. Microscopic observations were performed to confirm the tissue absorbance of the microplastics. Exposure to microplastics altered some parameters; however, growth was not affected. The effect of microplastics was not linear with the exposure concentration for most of the parameters and between 1.25 and 6 mg L-1 concentrations. The response trends mostly followed the second-order polynomial distributions. Under the 1.25 mg L-1 exposure, there were significant changes in root length, H2O2 content, catalase activity, anthocyanin content, and Fv/Fm. There were differences in parameters between the above-water and below-water parts, and the responses of the microplastics followed different trends. Microscopic observations confirmed the attachment of microplastic particles onto newly formed roots, except for older roots or shoot tissues.

Root anatomy, growth, and development of Typha domingensis Pers. (Typhaceae) and their relationship with cadmium absorption, accumulation, and tolerance.

Typha domingensis Pers. is a plant that grows in marshy environments, where cadmium (Cd) accumulates. The root is the first organ that comes into contact with the metal. The aim of this study was to evaluate the effect of Cd on the roots of T. domingensis. The experiment was conducted in a greenhouse using different Cd concentrations: (1) 0 µM (control), (2) 10 µM, and (3) 50 µM, with 10 replicates for 90 days. The plants were placed in plastic containers containing 5 L of nutrient solution modified with the different Cd concentrations. At the end of the experiment, the roots were measured, sampled, fixed, and subjected to usual plant microtechniques. The slides were observed and photographed under light microscopy and analyzed in ImageJ software. To measure Cd absorption, atomic-absorption spectrometry was used. The data were subjected to analysis of variance and comparison of means by the Scott-Knott test at P < 0.05. When exposed to 50 µM of Cd, the roots accumulated 99.35% of the Cd. At this concentration, there was a reduction in the exodermis but there was an increase in the diameter of the cortical cells and in the proportion of aerenchyma in the cortex. There was an increase in the root cap, which guaranteed the protection of the primary meristems. Therefore, T. domingensis adjusts its root anatomy improving the Cd tolerance and shows potential for phytoremediation purposes.

New low-cost biofilters for SARS-CoV-2 using Hymenachne grumosa as a precursor.

The ongoing global spread of COVID-19 (SARS-CoV-2 2019 disease) is causing an unprecedented repercussion on human health and the economy. Despite the primary mode of transmission being through air droplets and contact, the transmission via wastewater is a critical concern. There is a lack of techniques able to provide complete disinfection, along with the uncertainty related to the behavior of SARS-CoV-2 in the natural environment and risks of contamination. This fact makes urgent the research towards new alternatives for virus removal from water and wastewater. Thus, this research aimed to characterize new lost-cost adsorbents for SARS-CoV-2 using Hymenachne grumosa as a precursor and verify its potential for removing SARS-CoV-2 from the solution. The aquatic macrophyte H. grumosa had in natura and activated carbon produced with H. grumosa and zinc chloride (ZnCl2,1:1) impregnation and carbonization (700 °C, 1 h) were incubated for 24 h with inactivated SARS-CoV-2 viral suspension, and then the ribonucleic acid (RNA) was extracted and viral load quantified through reverse transcription-quantitative polymerase chain reaction (RT-qPCR) technique. The results demonstrated the great adsorption potential, achieving removal of 98.44% by H. grumosa "in natura", and 99.61% by H. grumosa with carbon activation, being similar to commercial activated carbon (99.67%). Thus, this study highlights the possibility of low-cost biofilters to be used for SARS-CoV-2 removal, as an excellent alternative for wastewater treatment or watercourses decontamination.

Cr, Ni, and Zn removal from landfill leachate using vertical flow wetlands planted with Typha domingensis and Canna indica.

Chromium (Cr), Nickel (Ni), and zinc (Zn) removal from landfill leachate using mesocosm-scale vertical flow wetlands, the effect of recirculation, and the ability of macrophytes to retain metals were evaluated. Wetlands were filled with coarse sand and light expanded clay aggregates and planted with Typha domingensis or Canna indica. Wetlands were operated using intermittent loading, with and without recirculation. Raw leachate was diluted and spiked with metals to reach the following concentrations: 0.2 mg L-1 Cr , 0.2 mg L-1 Ni, and0.2 mg L-1 Zn and 1.0 mg L-1 Cr, 1.0 mg L-1 Ni, and 1.0 mg L-1 Zn. Wetlands planted with T. domingensis presented higher metal removal than those planted with C. indica. Recirculation enhanced metal removal efficiencies significantly, being for T. domingensis/C. indica: 60/54, 49/47, 61/47% for Cr, Ni, and Zn at 0.2 mg L-1, and 80/71, 76/62, 73/59% for Cr, Ni, and Zn at 1.0 mg L-1, respectively. Metals were efficiently retained by macrophytes. Plant biomass and metal concentrations in roots were significantly higher than in shoots. Scanning electron microscopy and X-ray microanalysis showed that metals were absorbed by internal root tissues. A hybrid wetland planted with T. domingensis may be implemented to improve not only metal but also chemical oxygen demand and total nitrogen removals.

Effect of using forced and free oviposition methods to obtain eggs and larvae of Mansonia (Diptera: Culicidae) females from Rondonia, Brazil (western Amazon)

ABSTRACT Species of the genus Mansonia Blanchard are disease pathogen vectors in some regions of the world and can cause considerable inconvenience due to their bites when present in high numbers. However, little is known regarding their biology in Brazil. The objective of this work was to investigate some reproductive parameters of Mansonia from the western Brazilian Amazon. Females were captured in the field using human landing catches in rural areas of Porto Velho, Rondonia, Brazil. The mosquitoes were identified and separated into two groups for oviposition: forced, i.e., with wing removal, and free oviposition, without wing removal. Daily observations of oviposition and female survival were conducted until oviposition. The eggs and subsequent larvae were counted for fecundity and fertility evaluation, respectively. The species collected in this study were Mansonia amazonensis (Theobald), Mansonia humeralis Dyar & Knab and Mansonia titillans (Walker). The oviposition percentage for Ma. amazonensis was much lower than for Ma. humeralis and Ma. titillans. Forced oviposition resulted in a higher number of ovipositing females only for Ma. humeralis. Fecundity and fertility were not affected by the oviposition method. Egg and larval numbers were generally lower for Ma. amazonensis compared with the other species. Forced oviposition may be a tool to increase the number of ovipositing females depending on the Mansonia species studied in order to establish colonies in the laboratory.

Diverse traits of aquatic plants cannot individually explain their consumption by the generalist gastropod Biomphalairia glabrata.

Several experimental studies on aquatic plants have reported the prevalence of chemical defense mechanism against herbivory, as opposed to structural, life-forms or other traits. Here, our laboratory feeding experiments and integrative analysis explored the relationship among palatability (fresh or reconstituted plants used as artificial diet) and various chemical/nutritional traits (i.e., contents of dry mass, ash, nitrogen, protein, and phenols) of diverse aquatic plants and their susceptibility to consumption by the generalist gastropod Biomphalaria glabrata. Biomphalaria glabrata consumed all of the assayed aquatic plants in a hierarchical yet generalized way, with the consumption of fresh plants, their reconstituted forms and defensive properties of lipophilic extracts not being significantly correlated with plant physical or chemical traits to determine the feeding preference of the gastropod. Our results do not reveal a prevalence for a specific plant attribute contributing to herbivory. Instead, they indicate that the susceptibility of aquatic plants to generalist consumers is probably related to a combination of their chemical and physical properties, resulting in moderate grazing rates by generalist consumers.

Evaluation of Mansonia spp. Infestation on Aquatic Plants in Lentic and Lotic Environments of the Madeira River Basin in Porto Velho, Rondônia, Brazil.

The females of Mansonia are voraciously hematophagous. The spiracular apparatus of the immature, larval, and pupal forms is adapted to perforate submerged aquatic vegetation, from whose aeriferous aerenchyma they obtain the oxygen necessary for breathing. The proliferation of aquatic plants, in some cases linked to anthropic modifications that reduce water flow and/or increase organic matter content, may therefore contribute to the spread of these mosquitoes. This study aims to assess the presence of immature individuals of Mansonia in different aquatic plants of the Madeira River basin in 10 lentic and lotic environments and correlate their population density with abiotic factors such as water pH, dissolved O2, conductivity, and temperature. The sampling lasted from February 2016 to June 2018, a 29-month period during which 31,287 specimens belonging to the genus Mansonia were captured. Of the 12 species of macrophytes inspected, Eichhornia crassipes made up 70.1% of the samples. Lentic environments accounted for 58.9% of the samples and lotic environments for 41.1%. Immature individuals were most commonly found on Eichhornia crassipes, with this plant accounting for an average of 96.2% of all individuals, with a percentage ranging between 58.2% and 77.1% in different breeding areas. Only at the Foz do Igarapé Jirau site was a different distribution observed, with the number of aquatic plants more nearly equal: 83.3% of the larvae were found in Eichhornia crassipes, 9.2% in Ceratopteris pteridoides, 3.6% in E. azurea, 2.0% in Salvinia sp., and 1.9% in Pistia sp. The greatest richness was found in Iguapé do Raul. Concerning the larval/plant relationship, although less frequent, E. azurea had a higher larval density of Mansonia spp. It is important to emphasize that this finding may indicate a possible selection for this plant. Egg deposition by Mansonia spp. was more abundant in sample areas with Eichhornia crassipes and Pistia sp. The number of specimens collected was positively correlated with temperature, pH, and conductivity. These correlations showed a marked increase in the rainy season. Therefore, we were able to establish preliminary parameters of how environmental changes influence the ecology of this important genus of mosquitoes, the species of which are critical disease vectors.

Potential of Egeria densa and Pistia stratiotes for the phytoremediation of water contaminated with saflufenacil.

Saflufenacil is an herbicide that is leachable in soil and has the potential to contaminate groundwater, besides having moderate toxicity to aquatic organisms. Some macrophyte species may interfere with the availability of herbicides in water, increasing dissipation in this environment. Thus, the objective of this work was to evaluate the absorption and dissipation of 14C-saflufenacil in water by Egeria densa and Pistia stratiotes. Dissipation was performed with 14C-saflufenacil applied directly in water and quantified by liquid scintillation spectrometry (LSS). The evaluation times were 0, 3, 6, 24, 48, 72 and 96 h after application (HAA) for E. densa and 0, 12, 24, 36, 48, 60, 84 and 108 HAA for P. stratiotes. Absorption was analyzed through plant combustion in a biological oxidizer. The presence of the macrophytes increased the dissipation of 14C-saflufenacil in water. The half-life time (DT50) of the herbicide decreased by 82.6% in the presence of E. densa at 96 HAA. For P. stratiotes, the reduction in DT50 was 94.8% at 108 HAA. The absorption of 14C-saflufenacil was low for both macrophytes during the evaluated time. However, the macrophytes E. densa and P. stratiotes showed potential for the phytoremediation of water contaminated with saflufenacil.