322 resultados para submersed macrophytes


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The adult and immature stages of two new species of Goeldichironomus are described and figured. Larvae of G. luridus sp. nov., reared in the laboratory from egg masses, are abundant on organically enriched sediments of a chicken slaughter-house effluent treatment lagoon. Larvae of G. petiolicola sp. nov., live inside petioles of aquatic macrophytes such as Eichhornia azurea and Pontederia lanceolata.

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A new species from the Neotropical Region, Stilobezzia (Stilobezzia) pseudopunctulata Cazorla & Ronderos, is described and illustrated based on male and female adults and pupal exuviae. Adults were collected in the Argentinian provinces of Chaco, Formosa, Corrientes and Buenos Aires, and in Santa Cruz, Bolivia. The pupa was collected from mats of floating aquatic macrophytes in a lagoon in Ilha da Marchantería, in the vicinities of Manaus, Brazil. This new species is compared with its similar congener Stilobezzia punctulata Lane, from which it can be mainly distinguished by the wing with only two dark spots, the parameres longer and hook-shaped, the pupal respiratory organ with 11-12 pores and the very short apicolateral processes of the anal segment.

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The aquatic habit and host plants of Paracles klagesi (Rothschild) (Lepidoptera, Erebidae, Arctiinae) in Brazil. The aquatic caterpillar Paracles klagesi (Rothschild, 1910) was collected from the headwaters of a stream in an ecotone between Cerrado and Babaçu forest in northeastern Brazil. The single caterpillar found was observed feeding on the macrophyte Tonina fluviatilis Aubl. (Eriocaulaceae) and other aquatic plants of the family Nymphaeaceae present in the area, but also accepted as food Elodea canadensis Michx. (Hydrocharitaceae) and Cabomba sp. (Cabombaceae) under laboratory conditions.

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Several agencies specify AASHTO T283 as the primary test for field acceptance of moisture susceptibility in hot mix asphalt. When used in this application, logistical difficulties challenge its practicality, while repeatability is routinely scrutinized by contractors. An alternative test is needed which can effectively demonstrate the ability to screen mixtures based on expected performance. The ideal replacement can be validated with field performance, is repeatable, and allows for prompt reporting of results. Dynamic modulus, flow number, AASHTO T283, Hamburg wheel tracking device (HWTD), and the moisture induced sensitivity test (MIST) were performed on plant produced surface mixes in Iowa. Follow-up distress surveys were used to rank the mixes by their performance. The rankings indicate both the quantity of swelling from MIST conditioning and submersed flow number matched the performance ranking of all but one mixture. Hamburg testing parameters also appear effective, namely the stripping inflection point and the ratio between stripping slope and the creep slope. Dynamic modulus testing was ineffective, followed by AASHTO T283 and ratios produced from flow number results of conditioned samples.

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Coastal lagoons where salinity varies within a wide range during the year are colonized by euryhaline macrophytes which can develop extensive beds. Seasonal changes in biomass of Ruppia cirrhosa and Potamogeton pectinatus were studied in Tancada Lagoon (Ebro Delta, NE Spain) in order to reveal the environmental factors controlling their population development. Ruppia cirrhosa occupy a larger area of the lagoon than Potarnogeton pectinatus. Their maximum above ground biomasses are also different (495 g m-2 and 351 g m-2 ash free dry weight, respectively). Below ground biomass of Ruppia cirrhosa is between 9 and 53 % of the above ground biomass, while it is 3-40 % for Potamogeton pectinatus. Chlorophyll a contents show fluctuations similar to biomass. Low salinity and high turbidity caused by freshwater inflows favour Potamogeton expansion, while Ruppia development is favoured by high salinity and transparent water.

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L’objectiu d’aquest projecte ha sigut analitzar la qualitat de l’aigua a la Conca fluvial d’Alinyà i esbrinar quins són els factors que la determinen. Per fer-ho s’han utilitzat els macròfits (mitjançant l’índex IM) com a bioindicadors de la qualitat dels boscos de ribera i de manera indirecta determinar la qualitat de l’aigua. Es conclou que els factors més influents en els resultats són: la maca de diversitat dels macròfits donada l’època de l’any del mostreig (a la tardor), l’augment de les masses forestals homogeneïtzant el paisatge, les fortes pluges d’enguany i la contaminació puntual al nucli urbà d’Alinyà.

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Dans le cadre de la recherche de nouveaux composés naturels, les métabolites secondaires de plantes aquatiques indigènes, les potamots Potamogeton pectinatus L., P. lucens L., P. perfoliatus L. et P. crispus L. (Potamogetonaceae), ont été étudiés. Par leur position écologique et évolutive particulière entre environnement terrestre et aquatique, les plantes aquatiques ou macrophytes pourraient en effet avoir sélectionné des composés avec des caractéristiques originales. Les extraits dichlorométhaniques (apolaires) des potamots ont été analysés par HPLCUV, HPLC-MS, HPLC-RMN et GC-MS, et testés contre diverses cibles biologiques. Sur la base de ces résultats, les extraits apolaires de P. pectinatus et P. lucens ont été étudiés de manière plus approfondie. Ils ont été fractionnés sur des colonnes ouvertes et par VLC, LPLC, MPLC, CPC et HPLC semi-préparative. Une partie de leurs constituants ont été isolés et leurs structures déterminées par des méthodes spectroscopiques, en particulier par RMN et par MS. Quinze composés ont été ainsi isolés de P. pectinatus et P. lucens, dont sept sont des nouveaux produits naturels. Parmi ces quinze produits, neuf sont des diterpènes ent-labdanes contenant un noyau furane ou un groupe lactonique, dont six sont décrits ici pour la première fois. Certains de ces diterpènes ont montré une activité algicide, ce qui indique une de leurs fonctions possible dans les potamots, et un de ces labdanes, le méthyl-15,16-époxy-12-oxo-8(17),13(16),14-ent-labatrièn-19-oate, a également des propriétés anti-inflammatoires. Les composés présents dans les extraits méthanoliques (polaires) n?ont pas été isolés, mais quatorze d?entre eux ont pu être identifiés par HPLC-UV, HPLC-MS et HPLCRMN. Une majorité de ces constituants sont des flavonoïdes connus, des dérivés glycosylés de l?apigénine, la lutéoline et le chrysoériol, également présents en tant qu?aglycones. Plusieurs ent-labdanes glycosylés ont pu être également identifiés dans ces extraits, parmi lesquels un nouveau composé dont la structure a pu être partiellement déterminée. En conclusion, ce travail a permis de mieux connaître la phytochimie de plusieurs plantes aquatiques de Suisse, et d?isoler de nouveaux produits naturels avec des propriétés biologiques et pharmacologiques intéressantes.<br/><br/>The secondary metabolites of Swiss freshwater plants, the pondweeds Potamogeton pectinatus L., P. lucens L., P. perfoliatus L. and P. crispus L. (Potamogetonaceae), were investigated. Because of their peculiar habitat, in-between aquatic and terrestrial life, aquatic plants should produce secondary metabolites with original chemical or biological features. Their apolar extracts were analysed by HPLC-UV, HPLC-MS, HPLC-NMR and GCMS, and were tested with different bioassays. Based on these results, the apolar extracts of P. pectinatus and P. lucens were investigated more extensively. They were fractionated on open columns, and by VLC, LPLC, MPLC, CPC and semi-preparative HPLC. Their constituents were isolated and their structures elucidated by spectroscopic methods as MS and NMR. Fifteen compounds could be isolated from P. pectinatus and P. lucens, and seven were new natural products. Nine of them were ent-labdane diterpenes with a furan moiety or a lactone group, and six of these labdanes were reported here for the first time as natural products. Some of these diterpenes showed an algaecide effect. This activity indicated their potential ecological function in pondweeds. One compound, methyl-15,16-epoxy-12-oxo-8(17),13(16),14-ent-labatrien-19-oate, revealed also some anti-inflammatory properties. The constituents of polar extracts were not isolated, but fourteen of them could be identified by HPLC-UV, HPLC-MS and HPLC-NMR. The major part of these compounds was known flavonoids as apigenin, lutolin, chrysoeriol and their glycosylated derivatives. Several glycosylated ent-labdanes were also identified, and the structure of a new labdane dihexoside was partially elucidated. In conclusion this study allowed a better knowledge of the phytochemistry of Swiss aquatic plants, and the isolation of new natural products with interesting biological and pharmacological properties.

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Flow structures above vegetation canopies have received much attention within terrestrial and aquatic literature. This research has led to a good process understanding of mean and turbulent canopy flow structure. However, much of this research has focused on rigid or semi-rigid vegetation with relatively simple morphology. Aquatic macrophytes differ from this form, exhibiting more complex morphologies, predominantly horizontal posture in the flow and a different force balance. While some recent studies have investigated such canopies, there is still the need to examine the relevance and applicability of general canopy layer theory to these types of vegetation. Here, we report on a range of numerical experiments, using both semi-rigid and highly flexible canopies. The results for the semi-rigid canopies support existing canopy layer theory. However, for the highly flexible vegetation, the flow pattern is much more complex and suggests that a new canopy model may be required.

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Durante abril de 2005 se realizó una campaña de muestreo de la vegetación acuática macroscópica en las cuencas de los ríos Foix, Besòs y Llobregat, sumando un total de 68 estaciones de muestreo. El objetivo principal fue evaluar el estado trófico de dichas cuencas mediante el índice trófico generado en España denominado IVAM (Índice de Vegetación Acuática Macroscópica). Se identificaron un total de 44 táxones, 8 géneros de Cyanophyta, 5 de Rodophyta, 2 de Xantophyceae, 3 de Bacillariophyceae, 15 de Clorophyta, 8 de Spermatophyta, 1 liquen y 2 briófitos (musgos y hepáticas). La cuenca del Llobregat fue la más diversa (37 t´axones), seguida del Besós (33) y el Foix (25). Los táxones más frecuentes fueron Cladophora, Vaucheria, Oedogonium, Apium, Rorippa y Oscillatoria, además de los musgos. Las fanerógamas fueron escasas, destacando los g´eneros Ranunculus, Zannichellia y Potamogeton. Los táxones que alcanzaron una mayor puntuación del IVAM (valor de tolerancia, vt = 8), aunque poco frecuentes, fueron Ranunculus, Cymbella, Rivularia, Nostoc, Tolypothrix, Chroococcus y Lemanea, todos indicadores de aguas oligotr´oficas. En aguas de buena calidad pero algo eutrofizadas (aguas mesotróficas, vt = 6), los táxones más frecuentes fueron Chara, Monostroma y Hildenbrandia, además de las hepáticas y un liquen. Según la calificación de los tramos en clases de estado trófico realizada por el IVAM, el 38.2% de los tramos presentaron una buena calidad (clases I y II) mientras que el 61.8% presentaron un estado trófico alterado (clases III, IV y V). La respuesta del IVAM a la concentración de nutrientes (fosfato, amonio, nitrito y nitrato) fue siempre significativa, destacando la alta correlación alcanzada con el ión fosfato (r = 0.71, p < 0.001), superior a la alcanzada por otros índices de diatomeas y macrófitos de resolución taxonómica específica. Este hecho confirma la ventaja de utilizar el IVAM en la evaluación del estado trófico de los ríos, ya que sin necesidad de alcanzar un nivel taxonómico de especie se obtiene una respuesta adecuada a dicha perturbación.

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1. The implementation of the Water Framework Directive requires EU member states to establish and harmonize ecological status class boundaries for biological quality elements. In this paper, we describe an approach for defining ecological class boundaries that delineates shifts in lake ecosystem functioning and, therefore, provides ecologically meaningful targets for water policy in Europe. 2. We collected an extensive data set of 810 lake-years from nine Central European countries, and we used phytoplankton chlorophyll a, a metric widely used to measure the impact of eutrophication in lakes. Our approach establishes chlorophyll a target values in relation to three significant ecological effects of eutrophication: the decline of aquatic macrophytes, the dominance of potentially harmful cyanobacteria and the major functional switch from a clear water to a turbid state. 3. Ranges of threshold chlorophyll a concentrations are given for the two most common lake types in lowland Central Europe: for moderately deep lakes (mean depth 3–15 m), the greatest ecological shifts occur in the range 10–12 lg L 1 chlorophyll a, and for shallow lakes (<3 m mean depth), in the range 21–23 lg L 1 chlorophyll a. 4. Synthesis and applications. Our study provides class boundaries for determining the ecological status of lakes, which have robust ecological consequences for lake functioning and which, therefore, provide strong and objective targets for sustainable water management in Europe. The results have been endorsed by all participant member states and adopted in the European Commission legislation, marking the first attempt in international water policy to move from physico-chemical quality standards to harmonized ecologically based quality targets.

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Macroinvertebrates associated to reed-beds (Phragmites australis) in six shallow natural water bodies along the 220 km of coast of the Comunidad Valenciana (Spain) were studied. These sites were selected to reflect different trophic states, but also, and due to the natural variability of mediterranean wetlands, they greatly differ in salinity and hydroperiod. To unify the sampling, reed bed was chosen to provide data from a habitat common to all wetlands, including the most eutrophic ones where submerged macrophytes have disappeared due to water turbidity. Individual submerged stems of Phragmites australis were sampled along with the surrounding water. The animal density found refers to the available stem surface area for colonization. Forty-one taxa were recorded in total, finding Chironomidae to be the most important group, quantitatively and qualitatively. In freshwater sites it was observed an increase in macroinvertebrate"s density at higher trophic states. Nevertheless each studied region had a different fauna. The PCA analysis with macroinvertebrate groups distinguished three types of environment: freshwaters (characterized by swimming insect larvae, collectors and predators, oligochaetes and Orthocladiinae), saline waters (characterized by crustaceans and Chironominae) and the spring pool, which shares both taxa. Chironomids were paid special attention for being the most abundant. A DCA analysis based on the relative abundance of Chironomids reveals salinity as the main characteristic responsible for its distribution, but trophic state and hydrological regime were also shown to be important factors.

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Metabolic rates were determined by dissolved oxigen changes in light and dark bottles, filled with river water and after input of mixed effluent concentrations. In another experiment, dissolved inorganic nutrients, chlorophyll-alpha and other physico-chemical parameters were analyzed. Water column showed higher decomposition than production rates. Waste inputs increased primary production rates, but in higher concentrations forced the system to heterotrophy. The natural richness of macrophytes and macroalgae could be limiting the phytoplanktonic production by phosphorus assimilation. Observation of the nitrogenated inorganic nutrients suggest that the natural pelagic system is directed to nitrification. Mixed waste input inverted this trend, toward denitrification.

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Climate warming may lead to changes in the trophic structure and diversity of shallow lakes as a combined effect of increased temperature and salinity and likely increased strength of trophic interactions. We investigated the potential effects of temperature, salinity and fish on the plant-associated macroinvertebrate community by introducing artificial plants in eight comparable shallow brackish lakes located in two climatic regions of contrasting temperature: cold-temperate and Mediterranean. In both regions, lakes covered a salinity gradient from freshwater to oligohaline waters. We undertook day and night-time sampling of macroinvertebrates associated with the artificial plants and fish and free-swimming macroinvertebrate predators within artificial plants and in pelagic areas. Our results showed marked differences in the trophic structure between cold and warm shallow lakes. Plant-associated macroinvertebrates and free-swimming macroinvertebrate predators were more abundant and the communities richer in species in the cold compared to the warm climate, most probably as a result of differences in fish predation pressure. Submerged plants in warm brackish lakes did not seem to counteract the effect of fish predation on macroinvertebrates to the same extent as in temperate freshwater lakes, since small fish were abundant and tended to aggregate within the macrophytes. The richness and abundance of most plant-associated macroinvertebrate taxa decreased with salinity. Despite the lower densities of plant-associated macroinvertebrates in the Mediterranean lakes, periphyton biomass was lower than in cold temperate systems, a fact that was mainly attributed to grazing and disturbance by fish. Our results suggest that, if the current process of warming entails higher chances of shallow lakes becoming warmer and more saline, climatic change may result in a decrease in macroinvertebrate species richness and abundance in shallow lakes

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The humic substances were extracted from sediments, water and soil close to the Lagoa dos Patos-MS. The characterization was performed through fluorescence emission. In the HSs it is possible to see strong indications of incorporation of compounds originating from lignin degradation, confirmed by fluorescence emission (EEM and synchronous spectra). These differences observed in HSs may be due to tropical regions displaying a great variety of vascular plants and aquatic macrophytes that contribute natural organic matter. The seasonality effect also causes the entrance of pedogenic material and the suspension of sediments by the action of winds.

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The overall purpose of this thesis was to increase the knowledge on the biogeochemistry of rural acid sulphate (AS) soil environments and urban forest ecosystems near small towns in Western Finland. In addition, the potential causal relationship between the distribution of AS soils and geographical occurence of multiple sclerosis (MS) disease was assessed based on a review of existing literature and data. Acid sulphate soils, which occupy an area of approximately 17–24 million hectare worldwide, are regarded as the nastiest soils in the world. Independent of the geographical locality of these soils, they pose a great threat to their surrounding environment if disturbed. The abundant metal-rich acid drainage from Finnish AS soils, which is a result of sulphide oxidation due to artificial farmland drainage, has significant but spatially and temporally variable ecotoxicological impacts on biodiversity and community structure of fish, benthic invertebrates and macrophytes. This has resulted in mass fish kills and even eradication of sensitive fish species in affected waters. Moreover, previous investigations demonstrated significantly enriched concentrations of Co, Ni, Mn and Al, metals which are abundantly mobilised in AS soils, in agricultural crops (timothy grass and oats) and approximately 50 times higher concentrations of Al in cow milk originating from AS soils in Western Finland. Nevertheless, the results presented here demonstrate, in general, relatively moderate metal concentrations in oats and cabbage grown on AS soils in Western Finland, although some of the studied fields showed anomalous values of metals (e.g. Co and Ni) in both the soil and target plants (especially oats), similar to that of the previous investigations. The results indicated that the concentrations of Co, Ni, Mn and Zn in oats and Co and Zn in cabbage were governed by soil geochemistry as these metals were correlated with corresponding concentrations extracted from the soil by NH4Ac-EDTA and NH4Ac, respectively. The concentrations of Cu and Fe in oats and cabbage were uncorrelated to that of the easily soluble concentrations in the soils, suggesting that biological processes (e.g. plant-root processes) overshadow geochemical variation. The concentrations of K and Mg in cabbage, which showed a low spread and were strongly correlated to the NH4Ac extractable contents in the soil, were governed by both the bioavailable fractions in the topsoil and plant-uptake mechanisms. The plant´s ability to regulate its uptake of Ca and P (e.g. through root exudates) seemed to be more important than the influence of soil geochemistry. The distribution of P, K, Ca, Mg, Mn and S within humus, moss and needles in and around small towns was to a high degree controlled by biological cycling, which was indicated by the low correlation coefficients for P, K, Ca, Mg and S between humus and moss, and the low spread of these nutrients in moss and needles. The concentration variations of elements in till are mainly due to natural processes (e.g. intrusions, weathering, mineralogical variations in the bedrock). There was a strong spatial pattern for B in humus, moss and needles, which was suggested to be associated with anthropogenic emissions from nearby town centres. Geogenic dust affected the spatial distribution of Fe and Cr in moss, while natural processes governed the Fe anomaly found in the needles. The spatial accumulation patterns of Zn, Cd, Cu, Ni and Pb in humus and moss were strong and diverse, and related to current industry, the former steel industry, coal combustion, and natural geochemical processes. An intriguing Cu anomaly was found in moss. Since it was located close to a main railway line and because the railway line´s electric cables are made of Cu, it was suggested that the reason for the Cu anomaly is corrosion of these cables. In Western Finland, where AS soils are particularly abundant and enrich the metal concentrations of stream waters, cow milk and to some extent crops, an environmental risk assessment would be motivated to elucidate if the metal dispersion affect human health. Within this context, a topic of concern is the distribution of multiple sclerosis as high MS prevalence rates are found in the main area of AS soils. Regionally, the AS soil type in the Seinäjoki area has been demonstrated to be very severe in terms of metal leaching, this area also shows one of the highest MS rates reported worldwide. On a local scale, these severe AS soil types coincide well with the corresponding MS clustering along the Kyrönjoki River in Seinäjoki. There are reasons to suspect that these spatial correlations are causal, as multiple sclerosis has been suggested to result from a combination of genetic and environmental factors.