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Hydrocotyle ranunculoides L.f. — Habit: Herb. Habitat: LMWF; up to 2 000 m. Distribution: I. Voucher: Upper Imenti Forest, Alt. 2 234 m, 7 Aug. 2015, SAJIT 003801 (HIB). References: Fries & Fries (1927a), Agnew (2013)., Published as part of Zhou, Ya-Dong, Mwachala, Geoffrey, Hu, Guang-Wan & Wang, Qing-Feng, 2022, Annotated checklist of the vascular plants of Mount Kenya, East Africa, pp. 1-108 in Phytotaxa 546 (1) on page 100, DOI: 10.11646/phytotaxa.546.1.1, http://zenodo.org/record/6550464, {"references":["Fries, R. E. & Fries, T. C. E. (1927 a) Beitrage zur Kenntnis der Flora des Kenia, Mt. Aberdare und Mt. Elgon. IX. Notizblatt des Koniglichen Botanischen Gartens und Museums zu Berlin 10 (90): 1130 - 1135. https: // doi. org / 10.2307 / 3994575","Agnew, A. D. Q. (2013) Upland Kenya wild flowers and ferns, 3 rd edn. Nature Kenya Publications, Nairobi, 733 pp."]}

An array of vectors have been identified that pose a risk of spreading invasive alien species (IAS), from personal protective equipment to large equipment such as vehicles and boats. Biosecurity practices that remove and/or kill IAS reduce the risk of accidental spread. The effectiveness of biosecurity protocols suitable for large equipment is little tested and requires development. One widely-used biosecurity method for large equipment is high-pressure hot water spray machines. This study tests the effectiveness of high-pressure hot water spray to induce mortality in two invasive aquatic plants: floating pennywort (Hydrocotyle ranunculoides) and Australian swamp-stonecrop (Crassula helmsii); and two invasive invertebrates: killer shrimp (Dikerogammarus villosus) and zebra mussel (Dreissena polymorpha) in field conditions. IAS were exposed to hot water spray for a range of durations (5–15 seconds) and from a range of distances (10–30 cm). Further treatments of up to 90 seconds were applied to C. helmsii. Complete survival of D. polymorpha, D. villosus and C. helmsii was seen in all control treatments following exposure to cold water spray. Hot water spray caused complete mortality of D. polymorpha and D. villosus at 10 cm for 15 seconds, demonstrating the effectiveness of the hot water treatment in inducing mortality. However, treatments were less effective when applied at longer distances and shorter durations. In contrast, hot water spray was ineffective in causing mortality in C. helmsii, even at 90 seconds of exposure. Fragmentation and complete mortality was seen in H. ranunculoides following exposure to hot and cold water spray, therefore the pressure of the spray was associated with H. ranunculoides mortality. The use of hot water spray is effective against the aquatic invasive animals tested here, however to ensure complete mortality, the importance of both duration and distance of hot water spray application is highlighted. Hot water spray did cause complete mortality in H. ranunculoides but not in C. helmsii, therefore the need for treatment water containment and safe disposal is paramount to prevent spread of potentially viable propagules.

The heavy metal accumulation in the sediment and removal efficiency in stabilization ponds with Hydrocotyle ranunculoides filter were evaluated. Sediment and water were sampled in June, July and August 2018. The sediment sampling for each lagoon was conducted at three sites forming a composite sample. The water samples were collected in the tributary and effluent pipelines to determine the heavy metal concentration and removal efficiency by Hydrocotyle ranunculoides. The determination of heavy metals was performed with the method of atomic flame absorption spectrophotometry. The mean concentration of heavy metals in the sediment, in a descending order, was: Fe > Zn > Pb > Cu > Cd. The concentrations of these metals ranged from 998.0 to 1365.02, from 488.01 to 600.30, from 88.23 to 95.01, from 1.47 to 1.53 and from 0.01 to 0.13 mg/Kg, respectively. In the four stabilization ponds, the pollution factor values for Cd, Cu and Fe qualified as low pollution factor. While for Zn and Pb, they qualified as moderate pollution factors. The heavy metal removal rates from the water varied by metal.

Aquatic invasive alien species (IAS) negatively impact freshwater ecosystems worldwide. As suppression and eradication of established invader populations are often complex, costly and resource-intensive, the prevention of further invader spread is considered a key aspect of proactive management measures. Although broad-spectrum aquatic disinfectants have been suggested as a suitable decontamination mechanism to enhance invader spread-prevention strategies, inconsistencies concerning their effectiveness are reported within the literature. Here, we examine the use of two aquatic disinfectants, which were developed to kill damaging microbes, to induce substantial degradation of the apical fragmentary propagules of five invasive macrophytes: Crassula helmsii (Kirk) Cockayne; Egeria densa Planchon; Elodea canadensis Michx; Hydrocotyle ranunculoides Linnaeus; Lagarosiphon major (Ridley) Moss. Apical fragments were exposed to 0% (0 g L-1), 2% (20 g L-1) or 4% (40 g L-1) solutions of Virkon® Aquatic and Virasure® Aquatic, for submergence treatments of five, fifteen, thirty or sixty minutes. After 28 days, degradation of treated fragments was significantly greater than that of control groups, particularly for 4% solutions and longer exposure times. Despite this, sustained viability in relation to shoot and/or root regrowth was exhibited by almost all plant species. However, new shoot growth rates were significantly reduced following exposure to all treatments. At matched concentrations, there was no significant difference between the two disinfectants. Overall, it appears that the examined aquatic disinfectants will not curtail the spread of these invasive macrophytes. Yet, longer submergence times, multiple applications and synergistic effects of different biosecurity treatments may enhance preventative measures against further spread and this requires investigation.

Funder: The David and Claudia Harding Foundation, Background: Invasive alien plant species often have negative environmental and social impacts, such as loss of biodiversity and alteration of ecosystem services. As a result, managing the introduction, establishment, and abundance of invasive species is a major priority. To do this effectively, we need evidence on the effect of management interventions (such as using herbicide or cutting to control invasive plants). This evidence should not only include the effects of these management interventions on invasive alien species, but also on native species and other non-target outcomes such as ecosystem services. Such evidence would allow for comparison of the trade-offs between different management interventions. In the planned review we aim to assess how management interventions to control nine priority invasive alien plants species in England and Wales affect environmental outcomes. These species are: Japanese knotweed (Fallopia japonica) Nuttall’s waterweed (Elodea nuttallii), Chilean rhubarb (Gunnera tinctoria), Giant hogweed (Heracleum mantegazzianum), Floating pennywort (Hydrocotyle ranunculoides), Himalayan balsam (Impatiens glandulifera), Curly waterweed (Lagarosiphon major), American skunk cabbage (Lysichiton americanus), Parrot’s feather (Myriophyllum aquaticum). Methods: Searches will be in English and use bibliographic databases (Scopus, Web of Science Core Collection, Open Access Theses and Dissertations, and Conservation Evidence) and internet searches (Google Scholar), as well as specialist databases. Our methodology will only use the names of each species (scientific names and common names, including synonyms) as our search string (we will not use qualifiers, such as “AND invasive”). This will give low specificity but will increase the likelihood of capturing all relevant information. We will use predefined criteria for study inclusion and data extraction. We will screen publications in two stages: (1) using titles and abstracts and (2) using full texts. Consistency of inclusion will be checked by two people screening a random sample of 10% of titles and abstracts. This dual-screening will be subject to kappa analysis and any disagreements resolved through discussion. We will use critical appraisal to assess study validity by identifying studies that are potentially prone to bias.

The phytosorption potential of metals of Hydrocotyle ranunculoides was evaluated for the mitigation of water pollution in the high Andean wetlands of Peru. The plants were selected from 10 wetland sites in the community of Pomachaca- Tarma and were washed with potable water, dried, ground, weighed, chemically digested and read with Varian AA 240 atomic absorption equipment. The plant showed copper concentrations in the root (12.08 ± 1.67 mg/kg) greater than the stem (7.37 ± 1.00 mg/kg), followed by the leaves (7.37 ± 1.56 mg/kg). Lead concentration in the root was 0.228 ± 0.711 mg/kg, but was not found in the stem or leaves. The highest zinc concentration was in the root (67.52 ± 12.57 mg/kg) to the stem (53.30 ± 0.61 mg/kg), followed by the leaves (43.99 ± 8.49 mg/kg). Finally, iron was higher in the root (5571.28 ± 693.94 mg/kg) than in the leaves (342.76 ±122.09 mg/kg), followed by the stem (291.94 ± 54.84 mg/kg). Surrounding water had pH between 7.2 and 7.6; no copper and lead were found, zinc was 0.005 ± 0.012 mg/L and iron was 0.009± 0.007 mg/L. In the sediment, copper was 26.12 ± 0.65 mg/kg, lead 28.25 ± 2.41 mg/kg, zinc 85.98 ± 11.38 mg/kg and iron 26111.89 ± 614.37 mg/kg. These results indicate that this plant absorbs metals in the order of Fe>Zn>Cu>Pb and is an alternative for the development of phytotechnology, oriented to the treatment of effluents with metals that contaminate water in wetlands. Resumo O potencial de fitoabsorção de metais provenientes de Hydrocotyle ranunculoides foi avaliado para mitigar a contaminação da água nas áreas úmidas altas andinas do Peru. As plantas foram selecionadas de 10 zonas úmidas da comunidade de Pomachaca-Tarma e lavadas com água potável, secas, moídas, pesadas, quimicamente digeridas e lidas com o equipamento de absorção atómica Varian AA 240. A planta apresentava concentrações de cobre na raiz de 12.08 ± 1.67 mg/kg seco, no caule de 7.37 ± 1.00 mg/kg seco e nas folhas de 7.37 ± 1.56 mg/kg seco. Quanto às concentrações de chumbo na raiz foi de 0.228 ± 0.711 mg/kg seco, no caule e nas folhas não foi encontrado. O zinco mais elevado estava na raiz 67.52 ± 12.57 mg/kg seco, no caule 53.30 ± 0.61 mg/kg seco e seguido pelas folhas 43.99 ± 8.49 mg/kg seco. Finalmente, o ferro era mais elevado na raiz com 5571.28 ± 693.94 mg/kg seco, depois nas folhas 342.76 ±122.09 mg/kg seco e seguido do caule 291.94 ± 54.84 mg/kg seco. A água circundante tinha pH entre 7.2 e 7.6. Não foram encontrados cobre e chumbo, o zinco foi 0.005 ± 0.012 mg/L e o ferro 0.009± 0.007 mg/L. No sedimento, o cobre foi 26.12 ± 0.65 mg/kg seco, o chumbo 28.25 ± 2.41 mg/kg seco, o zinco 85.98 ± 11.38 mg/kg seco e o ferro 26111.89 ± 614.37 mg/kg seco. Estes resultados indicam que esta planta absorve metais na ordem de Fe>Zn>Cu>Pb e é uma alternativa para o desenvolvimento da fitotécnica, orientada para o tratamento de efluentes com metais que contaminam a água em zonas úmidas.

In Mexico, the contamination by potentially toxic metals in soil and water represents substantial ecological and health problems. Plants capable to grow on anthropogenically modified grounds reflect their ability of adaptation to diverse environmental conditions. Most of phytoremediation studies are carried out under laboratory conditions, and only few studies evaluate the ability of phytoextraction under in situ conditions. This chapter summarizes the information obtained, by scientific sources, about in situ phytoremediation studies carried out in Mexico. Most of the studies correspond to sites polluted with trace metals by mining activities. The information here described will be useful for planning the remediation of contaminated sites by potentially toxic metals in Mexico and can be extrapolated to different sites contaminated with potentially toxic metals throughout the world. Four trace metal hyperaccumulator plants (Hydrocotyle ranunculoides, Parietaria pensylvanica, and Commelina diffusa for Zn and Rorippa nasturtium-aquaticum for Cu) are here described. The native species must be studied to establish mechanisms of phytoextraction of metals and interaction with water/soil and microorganisms to improve the efficiency of in situ phytoremediation.

En México, la contaminación por elementos potencialmente tóxicos en el suelo y el agua representa importantes problemas ecológicos y de salud. Las plantas capaces de crecer en terrenos antropogénicamente modificados reflejan su capacidad de adaptación a diversas condiciones ambientales. La mayoría de los estudios de fitorremediación se lleva a cabo en condiciones de laboratorio, y sólo unos pocos estudios evalúan la capacidad de fitoextracción in situ. Esta revisión resume la información obtenida de fuentes científicas sobre los estudios de fitorremediación in situ realizados en México. El 85% de los estudios reportados corresponde a sitios contaminados con metales traza por actividades mineras. Se describen plantas con potencial para ser utilizadas como acumuladoras o hyperacumuladoras de elementos potencialmente tóxicos, como Hydrocotyle ranunculoides, Parietaria pensylvanica y Commelina diffusa para Zn; Rorippa nasturtium-aquaticum y Simsia amplexicaulis para Cu; Nicotina glauca, Flaveria angustifolia y Flaveria trinervia para As y Buddleja scordioides para la fitoremediación de suelos contaminados por Pb. Las especies de plantas nativas deben estudiarse para establecer mecanismos de fitoextracción de metales y la interacción agua-suelo-microorganismos para mejorar la eficiencia de la fitorremediación in situ. La información aquí descrita tiene utilidad para planificar la remediación de sitios contaminados por elementos potencialmente tóxicos en México y para diferentes sitios del mundo.

Epiphytic diatoms are an important component of death and fossil assemblages in macrophyte-dominated shallow lakes. In the Argentinean Pampas, the lack of studies on the composition, diversity and distribution of epiphytic diatoms limits the extent of the paleoenvironmental inferences that can be made from their fossil record. We studied the composition of epiphytic diatom biofilms living on five macrophytes in a Pampean shallow lake (Nahuel Rucá, Buenos Aires Province). Samples of emergent, free-floating, rooted-floating and submersed macrophytes were collected in triplicate over one year and analyzed for diatoms. Epiphytic assemblages on the free-floating species Azolla filiculoides and Ricciocarpus natans were dominated by Lemnicola hungarica, whereas the remaining macrophytes (the emergent Schoenoplectus californicus, the submersed Ceratophyllum demersum and the rooted-floating Hydrocotyle ranunculoides) were dominated by Cocconeis placentula. Although all assemblages were dominated by epiphytic taxa, low proportions of planktonic and benthic taxa were also recorded. Composition, diversity, richness and evenness of diatom assemblages found on free-floating macrophytes differed significantly from the rest of the samples analyzed. The strong association of the epiphytic diatom, L. hungarica, with free-floating macrophytes, together with the high dominance of C. placentula on emergent and submersed plants provides a potential method for inferring past fluctuations in aquatic vegetation coverage in the palaeolimnological record of Pampean shallow lakes. Fil: Paredes Rojas, Yesica Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Hassan, Gabriela Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina

Little is known on the influence of invasive aquatic weeds on afro-tropical waterbird communities. We used bird counts in sites of varying floating pennywort Hydrocotyle ranunculoides cover to explore the relationship between the weed and the waterbird community dynamics at Ngamo dam, Antelope Park, Zimbabwe. Waterbird communities in low-to-medium weed cover sites were more diverse and abundant compared to sites of high weed cover. In addition to supporting birds such as African Jacana which are able to forage within dense aquatic plants, high weed cover sites were associated with birds whose diets include invertebrates and fish which are likely more abundant and diverse in these sites. In contrast, low-to-medium weed cover sites were associated with bird species such as Common Moorhen, Great Egret, Pied Kingfisher and African Fish Eagle which require accessible open water and forage for diving, swimming or wading. The increased bird abundance in low-to-medium weed cover sites also likely increases prey for predatory birds. Thus, the negative changes in the waterbird community composition, abundance and diversity in response to increasing floating pennywort cover reflects species-specific tolerances to floating pennywort and its influence on accessible open water, foraging sites and prey availability.

Hydrocotyle ranunculoides (Araliaceae) is an aquatic plant native to the Americas and invasive in Europe. This work reports laboratory and garden studies on the host range of its main natural enemy, the weevil Listronotus elongatus (Hustache) (Coleoptera: Curculionidae). The genus Hydrocotyle is in a disputed phylogenetic situation such that both Apiaceae and Araliaceae must be included in the test list, but lacking a clear criterion of phylogenetic proximity. For this reason three testing instances were applied: no-choice on excised leaves, no choice on functional plants, and a multiple choice garden experiment. A large initial test-plant list was reduced to a smaller list adjusted by a feeding intensity criterion, survival curves and oviposition levels. Feeding was observed on the excised leaves of 21 out of 36 test plants, but as tests progressed to whole plants L. elongatus showed it could only develop and thrive on its natural host, and possibly survive as adults on Hydrocotyle modesta. Results confirm that typical laboratory starvation tests can provide a dependable ranking of physiological acceptability of different plant species but severely overestimate the actual host range of a specialized herbivore. They also indicate that the phylogenetic criterion for test plant list construction must be approached cautiously if the phylogeny is uncertain or disputed.

The objective of the study was to optimize the operation of the municipal wastewater treatment plant (WWTP) of Sicaya district with Hydrocotyle ranunculoides. The relative growth rate of the macrophyte was determined and so the relationship between the population growth area and the final weight according to the number of days elapsed. Medium fences were implemented and the tributary and effluent of the WWTP were characterized physicochemically and microbiologically. The results of the characterization corresponding to the tributary were: 616 mg of TSS/L, 109.2 mg of BOD5/L, 305.4 mg of COD/L, 30.3 mg of oils and fats/L and 3 500 000 NMP of thermotolerant coliforms/100 ml. Owing to the implementation of two medium grids large suspended solids were retained. The highest efficiency of COD removal with respect to the growth area of H. ranunculoides (2 226.96 m2) was 81.53%. While the efficiency of removal of thermotolerant coliforms was 79.2% at a temperature of 12.32 °C of the water. Using the operational optimization model in the WWTP with H. ranunculoides, an area of 3 291.67 m2 of macrophyte population growth was achieved with a removal efficiency of 93.71% COD and an area of 3 591.67m2 to remove 79.95% of thermotolerant coliforms at a temperature of 13°C.

Phytochelatins (PCs) are peptides that play an important role in homeostasis and detoxification of heavy metal in plants. Furthermore, they have been proposed as earlier potential biomarkers of aquatic pollution by heavy metals. Nowadays, several researchers have reported on current methods for quantification of glutathione (GSH) and the PCs (phytochelatin 2, phytochelatin 3, phytochelatin 4) quantification in plants. However, no method has reported the uncertainty of the measurement, which helps to improve the accuracy and quality assurance in the PC quantification. In this work, a new methodology using ultra-high-performance liquid chromatography coupled to mass spectrometry (UPLC-MS) to measure with high precision and accuracy the PCs in aquatic plants, was validated. Selectivity, linearity, limit of detection, limit of quantification, precision, trueness and uncertainty estimation were examined as parts of the method validation. The described method shows excellent linearity in different ranges for all analytes with coefficients of determination higher than 0.99. The relative standard deviation for intra-day precision was 50%) and recovery (19-44%) were the most important contributors to the total uncertainty. The proposed method was applied to quantify GSH and PCs in the aquatic plants Lemna gibba L., Myriophyllum heterophyllum Michx., Arenaria paludicola and Hydrocotyle ranunculoides L. fil., showing statistical differences in the mass fraction of the analytes.

An alternative for conservation of floristic diversity of region is the ex situ conservation, which depends on various environmental factors such as physical and chemical water conditions, local climate and the selected propagation technique. The objective of this research was to assess propagation technique of best performance by species, and identify environmental factors that influence growth rates, and phenology of selected species. The relationship between growth of 25 species selected and abiotic factors were examined in a term of 23 months. We measured once a month the cover percentage, length, height and basal diameter. Also, we analyzed 12 physical and chemical variables of the water of lake, and daily weather variables. The variation of water levels was main limiting factor for conservation of species ex situ. The species Bidens laevis , Ludwigia hexapetala and Ludwigia peploides showed high rates of growth in contrast to the high mortality of Cotula coronopifolia and Hydrocotyle ranunculoides . The phenological stages of some species were associated with the local climate pattern. Results suggest that the successful establishment of aquatic plants is determined by physical and chemical quality of water, and selected technique. Each technique depends on hydraulic, which is affected by temporal and special variations.

Aquatic plants mostly disperse via vegetative means, and plant fragments are the most important vegetative dispersal units. Here we studied the fragment drift in the medium sized River Erft, in which the macrophyte community is dominated by alien aquatic plants. The plant fragments were sampled at six different sites in the drift of the river. We analyzed the drifting biomass, the number of fragments and the number of propagation units (based on the known minimum size of fragments needed for regeneration of each species) as potential propagation units. Overall, we sampled >13,000 drift units of various sizes, from short stem fragments 400 connected plants (Vallisneria spiralis), resulting in >500,000 propagation units. The total number of sampled drift units and propagation units were significantly higher for native than for alien plant species. The number of sampled drift units and biomass was correlated with the total plant mass (TPM, calculated from species abundances per river section and section lengths) of the species in the river. However, the highest numbers of drift and propagation units per unit TPM were found for the four natives Ceratophyllum demersum, Potamogeton pectinatus, Potamogeton crispus and Myriophyllum spicatum, contributing to more than 75 % of the total number of fragments sampled. Conversely, lowest numbers of drift units were found for alien plants Hygrophila polysperma and Hydrocotyle ranunculoides, and no drift units were collected for four aquatic plant species in the river (alien Myriophyllum aquaticum and natives Nuphar lutea, Potamogeton nodosus and Sparganium emersum).

Aquatic environments are widely affected by anthropogenic activities and efficient remediation of these areas requires detailed studies for each natural ecosystem. This research aimed to evaluate the natural phytoremediation potential of Hydrocotyle ranunculoides L., a floating aquatic macrophyte located in a polluted aquatic environment in South of the Rio Grande do Sul, Brazil. Nutrients such as P, K, Ca, Mg, and S and heavy metals such as Cu, Zn, Fe, Mn, Na, Cd, Cr, Ni, Pb, Al, As, Co, and V content in the roots and shoots of the plants were evaluated through nitric perchloric acid digestion (HNO3-HClO4) methods and quantified by ICP-OES. Bioconcentration factor (BCF), translocation factor (TF), plant effective number (PEN), and potential phytoremoval (mg m−2) were carried out. H. ranunculoides showed a substantial ability for phytoextracting P, Na, and As, since showed ability of uptake these elements from the water and translocate them to the shoots of the plants. H. ranunculoides also showed potential for application in rhizofiltration of Mg, S, Cu, Zn, Fe, Mn, Cd, Cr, Ni, Pb, Al, and V, since exhibited high potential to uptake higher levels in the roots. The highest potential for bioremoval (mg m−2) of the H. ranunculoides was detected for K, Ca, P (recommending thus the use for phytoextraction), Fe, and Al (highly recommended for rhizofiltration). Therefore, this species under study showed high potential for in situ phytoremediation at Santa Barbara stream, and as a widespread species, it might be tested for phytoremediation in other sites.

We studied the breakdown rates and the invertebrate abundance and biomass for the litter of five native aquatic plants (Eichhornia crassipes, Eichhornia azurea, Thalia multiflora, Oxycaryum cubense and Hydrocotyle ranunculoides) in a shallow rain-fed lake using litter bags. The diets of the prawn Pseudopalaemon bouvieri and the amphipod Hyalella curvispina were determined and classified into five food items. Litter breakdown was fast (>0.010 day−1) for all species studied, although the breakdown rates were significantly affected by the litter species. The abundance of invertebrates colonizing the litter was significantly different among the species, but the biomass did not differ. The invertebrate taxa that colonized the litter of the different species were broadly similar, consisting primarily of oligochaetes, amphipods, prawns, ostracods, gastropods, water mites and several types of insect larvae (chironomids and mayflies). In terms of the number of individuals, naidid oligochaetes dominated the assemblages. In terms of biomass, P. bouvieri and H. curvispina reached 67.6 and 18.2 % of the total, respectively. Our results indicate that macroconsumers are involved in the breakdown process, since these species consume plant remains and detritus and highlight the importance of leaf litter composition on the abundance of invertebrates that colonize the litter. Fil: Poi, Alicia Susana G.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentina Fil: Galassi, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentina Fil: Carnevali, Romina Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentina Fil: Gallardo, Luciana Irene. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentina

Macrophyte mappings of a 37 km stretch of the thermally abnormal Erft River in 2003, 2005, 2007, 2011 and 2013 documented the presence of nine alien (Azolla filiculoides, Egeria densa, Eichhornia crassipes, Hydrocotyle ranunculoides, Hygrophila polysperma, Lemna minuta, Myriophyllum aquaticum, Pistia stratiotes and Vallisneria spiralis) in addition to 15 native species. During the study period, the number of native plant species decreased significantly in the river sections, while the number of alien species remained constant. The relative plant mass (RPM) of native species decreased from 67 to 33%, while that of the alien species increased. Only two of the nine reported alien species (V. spiralis and P. stratiotes) increased their abundances within the study period and became the most dominant species in the Erft River, while the other introduced species did not show mass development. The highest decline in RPM have been found for native Sparganium emersum and alien E. densa. Summarizing, the evergreen alien V. spiralis and recently P. stratiotes were the most successful invader within this thermally abnormal river since 2003, most likely profiting from the high winter temperatures >10 °C and displacing native vegetation, particularly formerly widespread native S. emersum.

The study was carried out to evaluate six different hydrophytes which were tested associated by twos: 1) Lemna gibba and Ceratophyllum demersum, 2) Berula erecta and Lemna gibba, 3) Polygonum punctatum and Hydrocotyle ranunculoides, and 4) Polygonum punctatum and Azolla filiculoides, for the purpose of removing nitrate from the water of Reyes Aztecas Lake, which is located southeast of Mexico City in Tlahuac District, Mexico D.F. The average of removal efficiency was obtained in relation to the different hydrophytes associations based on five sampling stations. The statistical analysis revealed that there were no significant differences among hydrophytes, all show remarkable ability to remove nitrate in water.

The discharge of sewage effluents into low-order streams has negative effects on water quality. Macrophytes can be efficient in the treatment of this wastewater due to the removal of the main pollutants. The genotoxicity of sewage-polluted water discharging into La Choza stream was evaluated by testing with Allium cepa. Also, a phytoremediation assay with continuous recirculation of the residual water was conducted for 12 days. Three treatments were carried out. One treatment (Hr) was performed with a macrophyte (Hydrocotyle ranunculoides), and two treatments were conducted without macrophytes: with lighting (Ai) and without lighting (Ao). The wastewater was toxic according to all the evaluated indexes (mitotic index, frequency of chromosomal aberrations and micronucleus). High concentrations of ammonium, dissolved inorganic nitrogen (DIN), total (TP) and soluble reactive phosphorous (SRP) and indicators of faecal contamination were determined in the wastewater. The ammonium, DIN, SRP and TP loads at the end of the assay were significantly lower in the treatments with light (Hr and Ai). So, the nutrient removal was due to their absorption and adsorption by the periphyton and H. ranunculoides. Our results lead us to recommend the maintenance and planting of macrophytes in lowland streams subject to sewage pollution. Fil: Basílico, Gabriel Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina. Universidad de Flores; Argentina Fil: Magdaleno, Anahí. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina Fil: Paz, Marta Laura. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina Fil: Moretton, Juan Agustin. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina Fil: Faggi, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina. Universidad de Flores; Argentina Fil: de Cabo, Laura Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina. Universidad de Flores; Argentina

Planting multiple species in wetland restoration sites could potentially accelerate ecological succession while enhancing ecological services. Our study of thick-mat floating marsh demonstrated that two species performed better than monocultures for developing a more structurally sound root mat. Although Panicum hemitomon is the typical dominant and focal species of all restoration efforts of this habitat type, we evaluated the effects of additional species, including Sagittaria lancifolia, a ubiquitous floating marsh constituent, and three laterally growing specialists (Alternanthera philoxeroides, Hydrocotyle ranunculoides, and Ludwigia peploides). In a mesocosm experiment, we found greater P. hemitomon biomass in monocultures but greater vegetative cover and total mat biomass with P. hemitomon plus L. peploides, but not greater biomass in the most species-rich treatment or treatment with the greatest initial planting density. We conclude that L. peploides aids restoration of thick-mat floating marsh by increasing mat buoyancy, enhancing lateral growth, and providing greater root mat structural integrity. This type of laterally growing specialist should accelerate coalescence of neighboring constructed and naturally formed mats. Planting species that occupy complementary niches should also minimize competition for key resources.

Hussner A, Van de Weyer K, Gross EM & Hilt S (2010). Comments on increasing number and abundance of non-indigenous aquatic macrophyte species in Germany. Weed Research 50, 519–526. Summary Non-indigenous aquatic plants are a major cause of biodiversity loss in many countries. In this study, our own field data and a literature review have been used to get an overview of the history and the present distribution of non-indigenous aquatic plant species in Germany. Results show that the number of non-indigenous aquatic plant species in Germany rose from 1 in 1860 to 12 in 1980, but doubled to 24 during the following 29 years. Thirteen of these species are naturalised in at least one federal state, 11 are only ephemeral. The number of non-indigenous aquatic plant species in the German federal states is significantly correlated with the population size and area. The increase in species number and abundance is probably caused by enhanced trading and increased invasibility of waters by eutrophication/re-oligotrophication and climate change. We propose a trading ban for some highly invasive non-indigenous aquatic species. This will not stop their natural spread, but should reduce the risk of further unintended entry and thus can be a major control factor.

Crassula helmsii, Hydrocotyle ranunculoides, Ludwigia grandiflora and Myriophyllum aquaticum are four well known invasive aquatic plants in European waters. In this study, plant growth at different nutrient availabilities, regeneration capacity and photosynthesis were investigated. Results show high relative growth rates (RGR) of the species of up to 0.132 ± 0.008 g g -1 dry weight (dw) day -1 (H. ranunculoides) and a significant increase in RGR with increasing nutrient availability. All species show a high regeneration capacity and the ability to form new shoots from single nodes, even though it differs between the species. Ludwigia grandiflora and M. aquaticum also show regeneration from single leaves. Species differed in maximal amounts, and in temperature and light optima of net assimilation rates: H. ranunculoides leaves reach maximum photosynthetic rates of up to 3500 μmol CO 2 x h -1 g -1 dw, L. grandiflora (leaves) up to 2200 μmol CO 2 x h -1 g -1 dw, M. aquaticum (shoots) 400 μmol CO 2 × h -1 g -1 dw and C. helmsii (shoots) up to 200 μmol CO 2 x h -1 g -1 dw. Hydrocotyle ranunculoides, L. grandiflora and M. aquaticum preferred high light intensity and high temperatures, whilst C. helmsii was negatively affected by intense sunlight. Summarising, it can be assumed that at least H. ranunculoides, L. grandflora and M. aquaticum can grow well under current and likely future central European climate conditions.

Invasive aquatic weeds negatively affect biodiversity, fluvial dynamics, water quality, and water storage and conveyance for a variety of human resource demands. In California’s Sacramento–San Joaquin River Delta, one submersed species—Brazilian egeria—and one floating species—waterhyacinth—are actively managed to maintain navigable waterways. We monitored the spatial and temporal dynamics of these species and their communities in the Sacramento-San Joaquin River Delta using airborne hyperspectral data and assessed the effect of herbicide treatments used to manage these species from 2003 to 2007. Each year, submersed aquatic plant species occupied about 12% of the surface area of the Delta in early summer and floating invasive plant species occupied 2 to 3%. Since 2003, the coverage of submersed aquatic plants expanded about 500 ha, whereas the coverage of waterhyacinth was reduced. Although local treatments have reduced the coverage of submersed aquatic plants, Delta-wide cover has not been significantly reduced. Locally, multiyear treatments could decrease submersed aquatic plants spread, given that no residual plants outside the treated area were present. In contrast, the spread of waterhyacinth either has been constant or has decreased over time. These results show that (1) the objectives of the Egeria densa Control Program (EDCP) have been hindered until 2007 by restrictions imposed on the timing of herbicide applications; (2) submersed aquatic plants appeared to function as ecosystem engineers by enabling spread to adjacent areas typically subject to scouring action; (3) repeated herbicide treatment of waterhyacinth has resulted in control of the spread of this species, which also appears to have facilitated the spread of waterprimrose and floating pennywort. These results suggest that management of the Delta aquatic macrophytes may benefit by an ecosystem-level implementation of an Integrated Delta Vegetation Management and Monitoring Program, rather than targeting only two problematic species. Nomenclature: Brazilian egeria, Egeria densa Planch.; floating pennywort, Hydrocotyle ranunculoides L. f.

Floating pennywort (Hydrocotyle ranunculoides L.f.), a member of the plant family Araliaceae originating from North America, is an example of an invasive aquatic species posing serious problems to the management of waterways outside of its original distribution area in Australia and Western Europe. As a consequence, its import was banned in the Netherlands. It can be difficult to distinguish H. ranunculoides from other species of the genus on a morphological basis. In this regard, DNA barcoding may become a good alternative once this could be performed on a routine basis. In this study, we show that it is possible to distinguish H. ranunculoides from a series of closely related congeners by using a single plastid DNA sequence, trnH-psbA.

Water resource degradation is one of mankind's greatest worries, as it causes direct and indirect damage to the associated biota. We initiated a water monitoring study in Pelotas Creek in 2003 in order to assess the mutagenic effect of the creek's waters. Allium cepa cells exposed to water samples and a chronically exposed macrophyte were analyzed, through evaluation of the mitotic index, mitotic anomalies, interphase anomalies, and total anomalies. Five points were chosen along the lower course of Pelotas Creek, from which water samples and floating pennywort (Hydrocotyle ranunculoides, Apiaceae) were collected in 2006 and 2007. The enteric bacterium Escherichia coli was found at all sampling points; in the physical-chemical analysis, a few variables exceeded permitted limits, pH (from 6 to 9), chloride (250 mg/L), hardness (from 10 to 200 mg CaCO(3)/L), and conductivity (100 microOmega/cm). There was an increased number of cytogenetic anomalies in exposed A. cepa cells and in the pennywort in 2006 relative to 2007, which may be explained by the increased rainfall, which was three times greater in 2007 at some stations than in 2006.Omega/cm). There was an increased number of cytogenetic anomalies in exposed A. cepa cells and in the pennywort in 2006 relative to 2007, which may be explained by the increased rainfall, which was three times greater in 2007 at some stations than in 2006.

Floating Pennywort ( Hydrocotyle ranunculoides L.fil.), a native to North America and naturalized in Central and South America, is an invasive aquatic weed in western Europe and several other regions worldwide. H. ranunculoides settles primarily in stagnant to slow-flowing waters (e.g. ditches, canals, rivers, lakes and ponds). The species prefers sunny and nutrient-rich sites and forms dense interwoven mats, which can quickly cover the surface of infested waters. In this study, the effect of three different water levels on growth of Floating Pennywort was investigated. Plants were cultivated on high-nutrient soils under waterlogged, semi-drained and drained conditions. Highest relative growth rates (RGR) of 0.097±0.004 g g −1 dw d −1 were reached under waterlogged conditions. This was significantly higher than RGR of plants cultivated semi-drained and drained. Floating Pennywort showed some phenological adaptations to drained soil conditions, including significant differences in the relative amounts of leaf, petiole and shoot biomass, whilst the relative amount of root biomass was not significantly influenced by the water level. Furthermore, Floating Pennywort reached under drained conditions lower relative water contents (RWC) of leaves, petioles and shoots, a significant shorter length of internodes, a significant lower extent of shoot porosity (POR), a lower chlorophyll content and an increased Chl a :Chl b ratio. In addition, maximum gas exchange of drained cultivated plants is significantly lower, due to strongly decreased leaf conductance under reduced water availability. Overall, H. ranunculoides showed ability to grow under different water levels, but performed best under waterlogged conditions.

Floating Pennywort (Hydrocotyle ranunculoides L. fil.) is a worldwide distributed aquatic plant. The species is native to North America and quite common also in Central and South America. In Europe, Japan and Australia it is known as an alien plant, sometimes causing serious problems for affected ecosystems and human use of water bodies. Starting from Western Europe with an eastwards directed spread, Floating Pennywort was recorded in Germany in 2004 for the first time. Since then, the species spread out and got established in western parts of Central Europe. For a definite prediction of the potential of a further spread, data about biology, in particular growth and photosynthesis are needed. Here, regeneration capacity, growth at different nutrient availabilities and photosynthesis of H. ranunculoides were investigated. In addition biomass samples were taken in the field. Results show an enormous regeneration capacity (e.g., by forming new shoots from small shoot fragments), increasing growth rates under increasing nutrient availability and a maximum increase of biomass reaching 0.132±0.008 g g−1 dw d−1. Dense populations of H. ranunculoides growing in ponds and oxbows were found at high nutrient content of the substrate, the biomass reaching there up to 532.4±14.2 g dw m−2. Gas exchange analysis showed a physiological optimum of H. ranunculoides CO2 uptake at temperatures between 25 and 35 °C and high photon flux densities (PPFD) above ∼800 μmol photons m−2 s−1. In comparison, native Hydrocotyle vulgaris showed an optimum of net photosynthesis at 20–30 °C and a light saturation of CO2 gas exchange at ∼350 μmol photons m−2 s−1.

A retrospective analysis shows that invasive, alien, free-floating and emergent aquatic weeds in Europe are good targets for classical biological control, and that genus-specific chrysomelid and curculionid beetles offer the most potential. Ludwigia spp., Azolla filiculoides, Lemna minuta, Crassula helmsii and Hydrocotyle ranunculoides should be prioritised as targets. Fungal pathogens have been under-utilised as classical agents but, whilst they may have some potential against free-floating weeds, they appear to be poor candidates against submerged species, although the suitability of arthropod agents against these difficult targets still merits investigation. The use of indigenous pathogens as inundative agents (mycoherbicides) shows some promise.

The spatial distribution of two biological groups of macrophytes (submerged and emergent) was studied in relation to the current velocity and stream morphometric variables (width, depth and width/wetted perimeter ratio) in three plain streams of the Buenos Aires province, Argentina. The frequency of the different species along 40 transects crossing the streams was determined. The most commonly found species were Egeria densa Planch. among the submerged plants and Rorippa nasturtium-aquaticum (L.) Hayek, Hydrocotyle ranunculoides L. and Eleocharis dunensis Kuk. among the emergent ones. In spite of the narrow range of current velocities found (0.3–39 cm/s), the two biological groups were mainly found in the lower current velocity zones, especially the submerged species. The pattern of distribution in relation to the stream width, depth and width/wetted perimeter ratio was not as evident as that related to the current velocity. The submerged species were very scarce in narrow and shallow reaches, while the distribution of the emergent species was more independent from these variables. Regarding the unbroken cross-sectional covers, the bigger ones corresponded to the submerged plants; instead the emergent plants had a larger proportion of the smaller patches. The bigger patches (up to 1050 cm) are found in zones where the current velocity is slower than 10 cm/s. Above this value, the patches do not exceed 210 cm of extension and belong to the emergent species only. These last ones do not form extensive patches, and remain constrained almost only to the banks of the streams. There is a general wide overlapping habitat, as shown by the Horn’s index (0.85–0.89). The number of species per patch varied between 1 and 8, and particularly when the cross cover occupied the whole width of the stream only 5% had one species and the most frequent figure was four species. This can be related to the effects of the macrophytes as habitat modifiers, making that the positive interactions within the patches prevail over the negative interactions.

Hydrocotyle ranunculoides L.f. is reported in this paper to be present at only 29 sites in the south east of England and in South Wales, in a wide range of water body types, which are typically slow-flowing and eutrophic. The current infestation is likely to have originated from various introductions from a single clone available at aquatic garden centres and nurseries in the U.K., Experiments on the optimum chemical control method have shown that the plant is most susceptible to the herbicide 2,4-D amine applied at 4.23 kg ha -1 active ingredient (a.i.). Initial observations suggest that the species is resistant to the herbicide glyphosate applied at 2.16 kg a.i. ha -1 . This resistance is postulated to be due to insufficient uptake of the herbicide through the leaf cuticle.