Mind the gap: the delayed recovery of a population of the biological control agent Megamelus scutellaris Berg. (Hemiptera: Delphacidae) on water hyacinth after winter.

Cold winter temperatures significantly affect the biological control effort against water hyacinth, Pontederia ( = Eichhornia) crassipes Mart. (Pontederiaceae), in more temperate regions around the world. The population dynamics of the planthopper Megamelus scutellaris Berg. (Hemiptera: Delphacidae), a newly released biological control agent of water hyacinth, were recorded on the Kubusi River in the Eastern Cape Province (South Africa) over 15 months to determine the population recovery post-winter. Megamelus scutellaris incurred a severe population decline at the onset of winter when the water hyacinth plants became frost damaged. The combined effect of a population bottleneck and low minimum winter temperatures (6.12°C) below the agent's lower developmental threshold (11.46°C) caused a post-winter lag in agent density increase. Subsequently, the maximum agent population density was only reached at the end of the following summer growing season which allowed the water hyacinth population to recover in the absence of any significant biological control immediately post-winter. Supplementary releases of agents from mass-reared cultures at the beginning of the growing season (spring) is suggested as a potential method of reducing the lag-period in field populations in colder areas where natural population recovery of agents is slower.

Eichhornia crassipes (Mart.) Solms: Uses, Challenges, Threats, and Prospects.

Water hyacinths pose serious challenges to humanity and the environment. Considering the enormity of the menace associated with the growth and spread of the plant and the difficulty in achieving a single, generally acceptable control method, it is becoming increasingly imperative to explore the potentials of the plant. New water hyacinth-related articles are regularly being published. Recently published articles about the plant were accessed, and the information in these articles is presented in the context of the pros and cons of the plant. Some of the benefits that can be derived from the plant include biogas and biofuel production, medicinal functions, vermicomposting, compost production, and bioremediation. However, clogging of waterways, obstruction of water transportation, and fishing activities; breeding grounds for pests and diseases; and reduction of water quality, loss of biodiversity, and economic downturn in areas invaded by the plant are problems associated with it. The peculiarity in the invasiveness of each situation should determine whether or not the growth of the plant is a problem, especially if the opportunity to harness the potentials of the plant exists. There are three major methods for controlling the plants when control becomes inevitable: mechanical, chemical, and biological. To achieve the best control, integrating two or more control methods is advised.

Phytoremediation of Industrial Sewage Sludge with Eichhornia crassipes, Salvinia molesta and Pistia stratiotes in Batch Fed Free Water Flow Constructed Wetlands.

Phytoremediation of industrial sewage sludge with Eichhornia crassipes, Salvinia molesta and Pistia stratiotes in pilot scale batch fed free water flow constructed wetlands was done in order to assess the suitability of remediated sludge as fertilizer. S. molesta showed the greatest decreases of Zn (36.0%), Fe (26.6%), Cu (32.6%), Cr (58.6%) and Ni, (26.9%) while P. startiotes and E. crassipes, respectively, showed the greatest Cd (27.1%) and Pb (42.4%) decreases. Metals, nutrients (total N and P) and fecal coliform in remediated sludge complied with regulatory standards and P. startiotes showed the greatest electrical conductivity (EC) (65.6%) decrease. The phytotoxicity assay on Lactuca sativa and Brassica oleraceae exhibited more than 50% of germination index from the sludge remediated with S. molesta. The results demonstrate that phytoremediation with hyper accumulators followed by phytotoxicity assay could be used to support decisions for the appropriate use of land disposed industrial sewage sludge.

Effects and Removal of the Antibiotic Sulfadiazine by Eichhornia crassipes: Potential Use for Phytoremediation.

The antibiotic sulfadiazine (SDZ) is a challenging threat to the health of aquatic organisms, as it frequently occurs in aquatic ecosystems. Tolerance mechanisms and accumulation of SDZ in a floating macrophyte (Eichhornia crassipes) under hydroponic conditions were investigated in this study to provide more insight into the SDZ removal process. Results show that the presence of 1 mg L-1 SDZ decreased the quickest and ranged from 669.45 to 165.34 µg L-1 from days 5 to 25. Exposing E. crassipes to SDZ ( < 1 mg L-1) maintained stable leaf photosynthetic efficiency. The overall increase in superoxide dismutase and peroxidase activities with SDZ treatments indicated that leaves were resistant. SDZ was absorbed by E. crassipes, following the sequence of root > aerial parts under all treatments. These findings suggest that E. crassipes has the ability to phytoremediation SDZ contaminated water.

Industrial wastewater treatment in internal circulation bioreactor followed by wetlands containing emergent plants and algae.

Wastewater treatment based on ecological principles is a low cost and highly desirable solution for the developing countries like Pakistan. The present study evaluated the effectiveness of biological treatment systems including Internal Circulation (IC) anaerobic bioreactor and constructed wetlands (CWs) containing macrophytes and mixed algal cultures for industrial wastewater treatment. The IC bioreactor reduced COD (52%), turbidity (89%), EC (24%) of the industrial wastewater. However, the effluents of IC bioreactor did not comply with National Environmental Quality Standards (NEQS) of Pakistan. Post-treatment of IC bioreactor effluents was accomplished in CW containing macrophytes (Arundo donax and Eichhornia crassipes) and mixed algal culture. The CWs planted with macrophytes lowered the concentrations of COD (89%) and turbidity (99%). CWs with algal biomass were not effective in further polishing the effluent. Inhibition of algal biomass growth was observed due to physicochemical characteristics of wastewater. The integrated treatment system consisting of IC bioreactor and macrophytes was found more suitable option for industrial wastewater treatment.

Molecular characterization of the endophytic fungal community associated with Eichhornia azurea (Kunth) and Eichhornia crassipes (Mart.) (Pontederiaceae) native to the Upper Paraná River floodplain, Brazil.

Endophytic fungi live in the interior of healthy plants without causing them any damage. These fungi are of biotechnological interest; they may be used in the biological control of pests and plant diseases, and in the pharmaceutical industry. The aquatic macrophytes Eichhornia azurea (Kunth) and Eichhornia crassipes (Mart.) belong to the Pontederiaceae family. The first is a fixed-floating species and the second is a free-floating species that is known for its phytoremediation potential. The fungal endophytes associated with the leaves of E. azurea and E. crassipes, native to the Upper Paraná River floodplain, Brazil, were isolated. The sequencing of the ITS1-5.8S-ITS2 region of ribosomal DNA was performed and the nucleotide sequences obtained were compared with those available in the GenBank database for the molecular identification of the isolates. The construction of phylogenetic trees was performed using the MEGA5 software. The results showed that high colonization frequencies were obtained from the 610 foliar fragments sampled from each plant: 87.86% for E. azurea and 88.85% for E. crassipes. At the genus level, it was possible to identify 19 fungal endophytes belonging to the genera Alternaria, Bipolaris, Cercospora, Diaporthe, Gibberella, Pestalotiopsis, Plectosphaerella, Phoma, and Saccharicola. Two other endophytes were identified at the species level (Microsphaeropsis arundinis). Genera Bipolaris, Cercospora, Microsphaeropsis, and Phoma were found as endophytes in the two macrophytes and the other genera were host-specific, being isolated from only one macrophyte, proving that there is a small difference in the endophytic diversity of the two Eichhornia species analyzed.

Effects of Eichhornia crassipes and Ceratophyllum demersum on Soil and Water Environments and Nutrient Removal in Wetland Microcosms.

Wetland plants are important components that influence the biogeochemistry of wetland ecosystems. Therefore, remediation performance in wetlands can differ depending on the growth forms of plants. In this study, the effects of Eichhornia crassipes (floating plant) and Ceratophyllum demersum (submerged plant) on the wetland soil and water environments were investigated using a microcosm study with simulated hydrology of retention-type wetlands between rainfall events. The C. demersum microcosm (SP) showed the fastest recovery with a diel fluctuation pattern of dissolved oxygen, pH, and oxidation-reduction potential (ORP) from the impacts of nutrient inflow. Moreover, SP exhibited the lowest decrease in sediment ORP, the highest dehydrogenase activity, and more organic forms of nitrogen and phosphorus. E. crassipes microcosms exhibited the lowest water temperature, and efficiently controlled algae. In the presence of plants, the total nitrogen and phosphorus concentrations in water rapidly decreased, and the composition of organic and inorganic nutrient forms was altered along with a decrease in concentration. The results indicate that wetland plants help retain nutrients in the system, but the effects varied based on the wetland plant growth forms.

Water quality index calculated from biological, physical and chemical attributes.

To ensure a safe drinking water supply, it is necessary to protect water quality. To classify the suitability of the Orós Reservoir (Northeast of Brazil) water for human consumption, a Water Quality Index (WQI) was enhanced and refined through a Principal Component Analysis (PCA). Samples were collected bi-monthly at seven points (P1 - P7) from July 2009 to July 2011. Samples were analysed for 29 physico-chemical attributes and 4 macroinvertebrate metrics associated with the macrophytes Pistia stratiotes and Eichhornia crassipes. PCA allowed us to reduce the number of attributes from 33 to 12, and 85.32% of the variance was explained in five dimensions (C1 - C5). Components C1 and C3 were related to water-soluble salts and reflect the weathering process, while C2 was related to surface runoff. C4 was associated with macroinvertebrate diversity, represented by ten pollution-resistant families. C5 was related to the nutrient phosphorus, an indicator of the degree of eutrophication. The mean values for the WQIs ranged from 49 to 65 (rated as fair), indicating that water can be used for human consumption after treatment. The lowest values for the WQI were recorded at the entry points to the reservoir (P3, P1, P5, and P4), while the best WQIs were recorded at the exit points (P6 and P7), highlighting the reservoir's purification ability. The proposed WQI adequately expressed water quality, and can be used for monitoring surface water quality.

Phytoremediation of levonorgestrel in aquatic environment by hydrophytes.

Adsorption and degradation of levonorgestrel (LNG) by two hydrophytes, Cyperus alternifolius (CA) and Eichhornia crassipes (EC), were investigated under light-shielding conditions in the water column. Variations of LNG concentrations in water, plant root epidermis, root, stem and leaf of the plants were analyzed. The results indicated that the removal efficiency of LNG by hydrophytes over the period of 50days was significantly greater than the blank control (p<0.05), with the removal rates of 79.80%±3.10% and 78.86%±2.55% for CA and EC, respectively. Compared with bio-adsorption, bio-conversion of LNG was found to be the dominant elimination pathway, evidenced by relatively high conversion rates (77.31%±2.68% for CA and 77.82%±2.95% for EC), while the adsorption rates were lower (1.77%±0.90% for CA and 1.05%±0.40% for EC). The bio-adsorption and conversion of LNG showed no significant differences between the two hydrophytes. Additionally, the mineralization on root epidermis played an important role in the reduction of LNG in water.

Influence of lead-doped hydroponic medium on the adsorption/bioaccumulation processes of lead and phosphorus in roots and leaves of the aquatic macrophyte Eicchornia crassipes.

In this study, lead bioaccumulation by the living free-floating aquatic macrophyte Eicchornia crassipes in different hydroponic conditions with variations in phosphorus and lead concentrations was investigated. A set of growth experiments in hydroponic media doped with lead and phosphorus within a wide concentration range was performed for 32 days in a greenhouse. All experiments were carried out with periodic replacement of all nutrients and lead. The concentration of lead and nutrients in biomass was determined by synchrotron radiation-excited total reflection X-ray fluorescence. By increasing the lead concentration in the medium, a reduction in biomass growth was observed, but a higher phosphorus retention in roots and leaves was shown at lower lead concentrations. In addition, an increase in the amount of bioaccumulated lead and phosphorus in roots was observed for higher lead and phosphorus concentrations in the medium, reaching saturation values of 4 mg Pb g(-1) and 7 mg P g(-1), respectively. Four non-structural kinetic models were tested, to represent the bioaccumulation of lead and phosphorus in roots. Pseudo-second order and irreversible kinetic models described the lead bioaccumulation data well, however, an irreversible kinetic model better fitted phosphorus uptake in roots.

Physico-chemical assessment of paper mill effluent and its heavy metal remediation using aquatic macrophytes--a case study at JK Paper mill, Rayagada, India.

The present investigation aims to assess the phytoremediation potential of six aquatic macrophytes, viz. Eichhornia crassipes, Hydrilla verticillata, Jussiaea repens, Lemna minor, Pistia stratiotes and Trapa natans grown in paper mill effluent of JK Paper mill of Rayagada, Orissa, for remediation of heavy metals. The experiment was designed in pot culture experiments. Assessment of physico-chemical parameters of paper mill effluent showed significant decrease in pH, conductivity, total dissolved solids, total suspended solids, chlorine, sulphur, biological and chemical oxygen demand after growth of macrophytes for 20 days. Phytoremediation ability of these aquatic macrophytic species for copper (Cu) and mercury (Hg) was indicated by assessing the decrease in the levels of heavy metals from effluent water. Maximum reduction (66.5 %) in Hg content of untreated paper mill effluent was observed using L. minor followed by T. natans (64.8 %). L. minor showed highest reduction (71.4 %) of Cu content from effluent water followed by E. crassipes (63.6 %). Phytoextraction potential of L. minor was remarkable for Hg and Cu, and bioaccumulation was evident from bioconcentration factor values, i.e. 0.59 and 0.70, respectively. The present phytoremediation approach was considered more effective than conventional chemical treatment method for removing toxic contaminants from paper mill effluent.

Nickel and phosphorous sorption efficiencies, tissue accumulation kinetics and morphological effects on Eichhornia crassipes.

The aim of the research was to assess the uptake efficiencies of Ni and P, their distribution in tissues along time and their toxic effects on the internal and external morphologies of Eichhornia crassipes. Aquaria with plants exposed to 1 mg Ni l(-1) or 5 mg P l(-1) and control were arranged in triplicate. Water and plants (aerial parts and roots) were sampled along 30 days. Ni uptake and tissue bioaccumulation kinetics was significantly faster than that of P. Mean root length, number of leaves, biomass and chlorophyll concentration were negatively affected by Ni, while these parameters were significantly increased by P in comparison with the control. Stele and metaxylem vessel cross-sectional areas (CSA) in the P treatment were significantly lower in comparison with that obtained in the Ni treatment and in control. Metaxylem vessels CSA in plants exposed to Ni were significantly higher while the number of vessels was significantly lower than those obtained in the control. Despite the toxic effects, E. crassipes efficiently accumulated Ni, probably due to the morphological plasticity of its root system.

Phosphorus removal from the hyper-eutrophic Lake Caohai (China) with large-scale water hyacinth cultivation.

A phytoremediation project involving the large-scale cultivation of water hyacinths (Eichhornia crassipes (Mart.) Solms) was conducted in Lake Caohai (China) from May to November during 2011-2013 to remove pollutants and decrease eutrophication. Water hyacinths were cultivated in two areas of Lake Caohai, Neicaohai, and Waicaohai, which are connected and function as a relatively independent water body. The areas for macrophyte growth varied in size from 4.30 km2 in 2011 to 0.85 km2 (2012) and 1.15 km2 (2013). Compared with historical data from 2007, the concentrations of total phosphorus decreased significantly, while dissolved oxygen concentrations increased slightly. After plant cultivation in 2011, the average concentrations of total phosphorus, total dissolved phosphorus, and phosphate anions decreased from 0.54, 0.35, and 0.23 mg L-1 upstream (river estuaries) to 0.15, 0.13, and 0.08 mg L-1 downstream (Xiyuan Channel), respectively. The amount of phosphorus assimilated by the macrophytes (44.31 t) was more than 100% of the total removed phosphorus (40.93 t) from lake water when water hyacinths covered 40.9% of the area, which could indicate sedimentary phosphorus release. Our study showed the great potential of utilizing water hyacinth phytoremediation to remove phosphorus in eutrophic waters.

Contrasting impact of elevated atmospheric CO2 on nitrogen cycle in eutrophic water with or without Eichhornia crassipes (Mart.) Solms.

The elevation of atmospheric CO2 is an inevitable trend that would lead to significant impact on the interrelated carbon and nitrogen cycles through microbial activities in the aquatic ecosystem. Eutrophication has become a common trophic state of inland waters throughout the world, but how the elevated CO2 affects N cycles in such eutrophic water with algal bloom, and how vegetative restoration helps to mitigate N2O emission remains unknown. We conducted the experiments to investigate the effects of ambient and elevated atmospheric CO2 (a[CO2], e[CO2]; 400, 800 µmol﹒mol-1) with and without the floating aquatic plant, Eichhornia crassipes (Mart.) Solms, on N-transformation in eutrophic water using the 15N tracer method. The nitrification could be slightly inhibited by e[CO2], due mainly to the competition for dissolved inorganic carbon between algae and nitrifiers. The e[CO2] promoted denitrification and N2O emissions from eutrophic water without growth of plants, leading to aggravation of greenhouse effect and forming a vicious cycle. However, growth of the aquatic plant, Eichhornia crassipes, slightly promoted nitrification, but reduced N2O emissions from eutrophic water under e[CO2] conditions, thereby attenuating the negative effect of e[CO2] on N2O emissions. In the experiment, the N transformation was influenced by many factors such as pH, DO and algae density, except e[CO2] and plant presence. The pH could be regulated through diurnal photosynthesis and respiration of algae and mitigated the acidification of water caused by e[CO2], leading to an appropriate pH range for both nitrifying and denitrifying microbes. Algal respiration at night could consume DO and enhance abundance of denitrifying functional genes (nirK, nosZ) in water, which was also supposed to be a critical factor affecting denitrification and N2O emissions. This study clarifies how the greenhouse effect caused by e[CO2] mediates N biogeochemical cycle in the aquatic ecosystem, and how vegetative restoration mitigates greenhouse gas emission.

Assessment of pollutant removal processes and kinetic modelling in vertical flow constructed wetlands at elevated pollutant loading.

Constructed wetland (CW), an ecological wastewater treatment technology, is low cost and easily to operate. Vertical flow constructed wetland (VF-CW) systems have been used to treat various wastewaters across the world. The present work exhibits the detail study of five type's multi-layered vertically constructed wetlands operated at 24 h hydraulic retention time under semi-continuous vertical flow mode. Except N-NO3-, all the pollutants were sufficient removal in iron scraps constructed wetland (ISs-CW). The highest average pollutant removal efficiency achieved in ISs-CW was 85.04%, 77.57%, 85.99%, 62.01% and 88.91% for N-NH4+, N-NO2+, total nitrogen, total phosphate and sulphate respectively. The present CWs planted with Eichhornia crassipes is a promising system for municipal wastewater treatment. The first-order kinetic modelling was best suited for the removal rate since it presents higher R2, rate constant (k) and B values.

Trait convergence and niche differentiation of two exotic invasive free-floating plant species in China under shifted water nutrient stoichiometric regimes.

The effects of eutrophication on the growth and phenotypic performance of macrophytes have been widely studied. Experimental evidence suggests that an increase in the water nutrient level would promote the performance of several invasive free-floating macrophytes. However, few studies have focused on how a shift in water nutrient (nitrogen and phosphorus) stoichiometric regimes may influence the performance of invasive free-floating macrophytes. In the present study, two exotic invasive plant species, free-floating Eichhornia crassipes and Pistia stratiotes, were subjected to different water nutrient stoichiometric regimes, and their phenotypic performance was studied. We found that the two species converged in several resource use traits and diverged in lateral root length. This implied that their similarities in fitness-correlated traits and their underwater niche differentiation probably contribute to their stable coexistence in the field. Additionally, the eutrophic conditions in the different N:P regimes scarcely altered the performance of both species compared to their performance in the oligotrophic condition. Based on previous studies, we predicted that moderate eutrophication with slight overloading of nitrogen and phosphorus would not improve the performance of several invasive free-floating plants and thus would scarcely alter the invasive status of these species. However, moderate eutrophication may cause other problems, such as the growth of phytoplankton and algae and increased pollution in the water.

Ecotoxicological effects and accumulation of ciprofloxacin in Eichhornia crassipes under hydroponic conditions.

Antibiotic residues pose a threat to the health of aquatic organisms. The effects and accumulation of antibiotic ciprofloxacin (CIP) in a floating macrophyte (Eichhornia crassipes) under hydroponic conditions were investigated. It was found that E. crassipes exposure to CIP (< 1000 µg L-1) could maintain a stable photosynthesis efficiency. In response to CIP stress, catalase and peroxidase activities of leaves were 7.24-37.51 nmol min-1 g-1 and 98.46-173.16 U g-1, respectively. The presence of CIP did not inhibit the growth of the plant. After 14 days of exposure, tender leaves became white and withered, ascribed to the decline of chlorophyll content and chlorophyll fluorescence parameters. The CIP concentrations, absorbed by E. crassipes, were highest in the roots, followed by white aerial parts and green aerial parts at CIP concentrations of 100 and 1000 µg L-1. These findings demonstrated that E. crassipes could absorb and tolerate CIP in a limited time-scale and imply an alternative solution for phytoremediation in water bodies contaminated with antibiotics.

Arsenic removal from waters by bioremediation with the aquatic plants Water Hyacinth (Eichhornia crassipes) and Lesser Duckweed (Lemna minor).

In this study the removal of arsenic by the Water Hyacinth (Eichhornia crassipes) and Lesser Duckweed (Lemna minor) was monitored under a concentration of 0.15mgL(-1) of the element. Plant densities were 1kg/m2 for Lesser Duckweed and 4kg/m2 for Water Hyacinth on a wet basis. The arsenic was determined in foliar tissue and water samples by hydride generation atomic absorption spectroscopy. The element was monitored as a function of time during 21 days. No significant differences were found in the bioaccumulation capability of both species. The removal rate for L. minor was 140mg As/had with a removal recovery of 5%. The Water Hyacinth had a removal rate of 600mg As/had and a removal recovery of 18%, under the conditions of the assay. The removal efficiency of Water Hyacinth was higher due to the biomass production and the more favorable climatic conditions. This specie represents a reliable alternative for arsenic bioremediation in waters.

Performance of a water hyacinth (Eichhornia crassipes) system in the treatment of wastewater from a duck farm and the effects of using water hyacinth as duck feed.

Nowadays, intensive breeding of poultry and livestock of large scale has made the treatment of its waste and wastewater an urgent environmental issue, which motivated this study. A wetland of 688 m2 was constructed on an egg duck farm, and water hyacinth (Eichhornia crassipes) was chosen as an aquatic plant for the wetland and used as food for duck production. The objectives of this study were to test the role of water hyacinth in purifying nutrient-rich wastewater and its effects on the ducks' feed intake, egg laying performance and egg quality. This paper shows that the constructed wetland removed as much as 64.44% of chemical oxygen demand (COD), 21.78% of total nitrogen (TN) and 23.02% of total phosphorus (TP). Both dissolved oxygen (DO) and the transparency of the wastewater were remarkably improved, with its transparency 2.5 times higher than that of the untreated wastewater. After the ducks were fed with water hyacinth, the average daily feed intake and the egg-laying ratio in the test group were 5.86% and 9.79% higher, respectively, than in the control group; the differences were both significant at the 0.01 probability level. The egg weight in the test group was 2.36% higher than in the control group (P < 0.05), but the feed conversion ratios were almost the same. The eggshell thickness and strength were among the egg qualities significantly increased in ducks fed with water hyacinth. We concluded that a water hyacinth system was effective for purifying wastewater from an intensive duck farm during the water hyacinth growing season, as harvested water hyacinth had an excellent performance as duck feed. We also discussed the limitations of the experiment.

[Effects of hurricane "Pauline" (1997) on the fauna associated with the plant Eichhornia crassipes in Laguna Coyuca, South Pacific of Mexico]. / Efectos del huracán "Pauline" (1997) sobre la fauna asociada a la planta Eichhornia crassipes en la Laguna Coyuca, Pacífico sur de México.

Effects of hurricane "Pauline" (1997) on the fauna associated with the plant Eichhornia crassipes in Laguna Coyuca, South Pacific of Mexico. Reports on the effects of hurricanes on marine and coastal environments often deal with coral reefs, but little is known about their effect on the communities associated with the water hyacinth, Eichhornia crassipes. From January 1997 (pre-hurricane) through April 1998 (post-hurricane) we made montly collections of fauna in E. crassipes roots from Laguna Coyuca, Mexico (17 degrees 00' - 16 degrees 54' N, 99 degrees 58'-100 degrees 05' W). The hurricane affected Coyuca on October 9th, 1997 and caused mortalities of that fauna. During the three subsequent months the absence of E. crassipes and its associated fauna in the study area was evident, but in January 1998, we found a partial reestablishment of E. crassipes and its associated fauna. Four months later, this community was almost back to pre-hurricane levels.