No description available.

Nous avons utilisé comme modèle biologique Elodea nuttallii et Elodea canadensis, plantes originaires d'Amérique du Nord et présente en France depuis le dix-neuvième siècle (E. canadensis) et les années 1950 (E. nuttallii). E. nuttallii est actuellement en phase d'expansion tandis que E. canadensis est considérée comme naturalisée en Europe. Notre objectif principal consiste à étudier les conséquences de l’invasion de E. nuttallii sur les communautés de macroinvertébrés. Nous avons d'abord étudié le rôle d'habitat de E. nuttallii et des plantes indigènes Ranunculus peltatus et Callitriche platycarpa pour les macroinvertébrés dans des ruisseaux qui diffèrent par leurs niveaux de trophie. Le principal résultat obtenu montre que le niveau de trophie des cours d'eau est le principal facteur influençant la répartition des invertébrés, l'espèce de macrophyte étant secondaire. E. nuttallii accueille des communautés d'invertébrés à la composition et à la structure intermédiaire par rapport à R. peltatus et C. platycarpa. Les propriétés architecturales des trois macrophytes auraient un rôle dans la répartition des invertébrés entre les différents herbiers. Parmi les invertébrés peuplant les macrophytes, les gammares ont un régime généraliste. Nous avons d'abord validé l’utilisation de Gammarus roeseli comme modèle pour tester l’appétence des macrophytes. Nous avons ensuite évalué l'évolution saisonnière de l'appétence des élodées et mis en évidence les mécanismes évolutifs qui permettent à une espèce invasive de proliférer et de s'intégrer dans les écosystèmes. E. canadensis alloue son énergie à la défense tandis que E. nuttallii a une stratégie de croissance végétative. / We used the exotic macrophytes Elodea nuttallii and Elodea canadensis originating from North-America and introduced in France during the nineteenth century (E. canadensis) and during the 1950s (E. nuttallii). Elodea nuttallii is currently actively spreading whereas E. canadensis is now integrating most of the hydrosystems in Europe. Our main objective was to study the consequences of the invasion of E. nuttallii on the macroinvertebrate communities. We first studied the role of macrophytes as habitat with E. nuttallii and the indigenous species Ranunculus peltatus and Callitriche platycarpa in Northern Vosges streams that differ in their trophic levels. Our main result was that the trophic level had a greater influence than the plant species in the repartition of the macroinvertebrates. The macroinvertebrate community hosted by E. nuttallii was intermediate between the communities hosted by R. peltatus and C. platycarpa. Plant structural complexity appears to play a role in the repartition of the macroinvertebrates. Among the macroinvertebrates associated with the macrophytes, the gammarids have a broad generalist diet. We first validated the use of Gammarus roeseli as herbivores to assess plant palatability. Then, we measured the seasonal variations of the palatability of E. canadensis and E. nuttallii and the different evolutionary strategies that the plants had developed to invade or to integrate the ecosystems. E. canadensis allocates increased resource to defence whereas E. nuttallii allocates its resources mainly to vegetative growth.

Ces travaux contribuent à caractériser des compartiments environnementaux (i.e. eau, sol et solution du sol, substrat, macrophytes à l’échelle individuelle et des communautés) et leur fonctionnement pour in fine améliorer l’efficacité de zones humides construites (CW) à décontaminer une masse d’eau contaminée en cuivre. Les connaissances sur le maintien de l’homéostasie de Cu chez les végétaux ainsi que sa phytotoxicité aux expositions élevées sont résumées. Les principaux mécanismes physico-chimiques et biologiques intervenant en phytoremédiation d’eaux contaminées en Cu en CW sont également discutés. Plusieurs solutions de phytoremédiation de type phytostabilisation aidée ont été évaluées en lysimètres in situ sur un site de traitement du bois contaminé au Cu, afin d’établir le potentiel de certains amendements à sorber Cu dans le substrat des CW. Les concentrations en éléments traces potentiellement toxiques (PTTE, dont Cu) et macroéléments des lixiviats migrants vers les horizons aquifères ont été quantifiées. Un laitier sidérurgique de type Linz-Donawitz enrichi en P (LDS, 1%) a permis le meilleur développement de Lemna minor L., utilisé ici comme bioindicateur, exposée aux lixiviats. En parallèle, les communautés de macrophytes ont été suivies le long du parcours de la Jalle d’Eysines, une rivière urbaine contaminée en Cu et autres PTTE. Les concentrations en PTTE ont été déterminées dans le sol, l’eau, l’eau interstitielle et les feuilles de 7 espèces de macrophytes. Un modèle statistique multivarié (analyse discriminante linéaire, LDA) a ensuite été élaboré sur la base des concentrations foliaires en PTTE pour biosurveiller l’exposition des macrophytes. Des populations de macrophytes ont aussi été prélevées sur des zones humides de contamination croissante en Cu en Europe (France, Espagne, Portugal et Italie), Biélorussie et Australie. La production de racines chez les macrophytes exposées pendant 3 semaines à des concentrations croissantes en Cu (0,08 ; 2,5 ; 5 ; 15 et 25 µM Cu) montre une variabilité intra-spécifique de la tolérance au Cu pour des populations de Juncus effusus, Schoenoplectus lacustris et Phalaris arundinacea. A l’inverse, une réponse similaire à une tolérance constitutive a été obtenue chez Typha latifolia et Iris pseudacorus, deux espèces à forte production de rhizomes. L’importance des rhizomes est discutée. Phragmites australis produit également des rhizomes, mais a présenté une variabilité intra-spécifique dans sa production racinaire en réponse à une exposition au Cu. En CW, à l’échelle du mésocosme (110 dm3), jusqu’à 99% du Cu de la masse d’eau (concentration initiale: 2.5µM Cu) ont été éliminés dans les trois modalités plantées de Juncus articulatus, P. arundinacea et P. australis, ainsi que dans le contrôle non planté. Les rôles du biofilm microbien, du substrat et des macrophytes en CW ainsi que leurs interactions sont discutés. La sélection d’écotypes de macrophytes tolérants aux PTTE pour leur utilisation en zone humide construite ainsi que les mécanismes moléculaires impliqués dans la variabilité intra-spécifique de cette tolérance, notamment chez P. australis, sont deux thèmes de recherche à promouvoir. / This work aims at characterizing environmental compartments (i.e. water, soil and soil pore water, substrate, macrophytes at the individual and community scale) and their functioning to in fine improve the effectiveness of constructed wetlands (CW) for cleaning Cu-contaminated waters. Knowledge on the homeostasis of Cu in plants and its phytotoxicity at medium and high exposures are summarized. The main physico-chemical and biological mechanisms involved in the phytoremediation of Cu-contaminated water in CW are discussed. Several aided-phytostabilisation options were in situ evaluated in lysimeters at a Cu-contaminated wood preservation site to assess the potential of four amendments to sorb Cu in a CW substrate. Concentrations of potentially toxic trace elements (PTTE, including Cu) and macronutrients of leachates migrating from the root zone to the aquifers were quantified. Based on the responses of Lemna minor L. used as a bioindicator, exposed to the leachates,.Linz-Donawitz slag spiked with P (LDS, 1%) best performed to sorb labile Cu in the root zone. In parallel, macrophyte communities were monitored along the Jalle Eysines River, an urban river slightly contaminated by Cu and other PTTE. The PTTE concentrations were determined in the soil, water, soil pore water, and in the leaves of seven macrophyte species. A multivariate statistical model was developed based on the foliar PTTE concentrations for biomonitoring macrophyte exposures. Populations of macrophytes were also collected in wetlands displaying an increasing Cu contamination in Europe (France, Spain, Portugal, and Italy), Belarus and Australia. Root production of macrophytes exposed for 3 weeks at increasing Cu concentrations (0.08, 2.5, 5, 15 and 25 µM Cu) shows an intra-specific variability of Cu tolerance in populations of Juncus effusus, Schoenoplectus lacustris and Phalaris arundinacea. In contrast, a similar response to constitutive tolerance occurred for Typha latifolia and Iris pseudacorus, two species with high production of rhizomes. The rhizome influence is discussed. Phragmites australis also produces rhizomes but showed intra-specific variability in response to Cu exposure. In a CW at mesocosm scale (110 dm3), up to 99% of Cu in water (initial concentration: 2.5μM Cu) was removed after 2 weeks in the three modalities planted with Juncus articulatus, P. arundinacea and P. australis, and in the unplanted control. The influences of microbial biofilms, the substrate, and the macrophyte species and their interactions in CW are discussed. The selection of PTTE-tolerant macrophytes for their used in CW and the understanding of molecular mechanisms underlying the intra-specific variability in PTTE- tolerance, i.e for P. australis, require further investigations.

No description available.

Resumo: O objetivo deste trabalho foi avaliar o ganho de biomassa de Eichhornia crassipes cultivada em microcosmo em diferentes épocas do ano. O experimento teve duração de 189 dias e ocorreu entre abril e outubro de 2006. Indivíduos de E. crassipes foram cultivados em um sistema de recirculação de água composto por 3 unidades experimentais. O fluxo de água foi contínuo (vazão de 0,25 L min-1) e nutrientes foram adicionados semanalmente. Valores de nitrito, nitrato, ortofosfato, oxigênio dissolvido, condutividade elétrica, turbidez, pH e temperatura da água foram obtidos semanalmente. Os valores médios semanais de temperatura mínima absoluta atmosférica foram calculados através dos dados obtidos pela Estação Meteorológica CEAPLA/UNESP, localizado a aproximadamente 500 metros do local do experimento. Semanalmente as plantas foram pesadas e posteriormente devolvidas as respectivas unidades experimentais. Variações de temperatura atmosférica foram verificadas. O período com os menores valores de temperatura mínima atmosférica (junho e julho) coincidem com o período de menores valores de ganho de biomassa do vegetal. Após este período, os valores de temperatura aumentaram favorecendo o crescimento do vegetal, ocorrendo os maiores valores de ganho de biomassa. / Orientador: Antonio Fernando Monteiro Camargo / Coorientador: Gustavo Henrique Gonzaga da Silva / Banca: Luis Mauricio Bini / Banca: Ciro césar Zanini Branco / Mestre

The specific activity of the ('32)P labeled sediment-P taken up by submersed macrophytes was shown to be identical to the specific activity of the sediment mobile P, as measured by isotopic dilution. The mobile P therefore represents the sediment-P available to aquatic macrophytes. / The ability to accurately measure the specific activity of the available sediment-P was applied to problems pertaining to the role of macrophytes in P cycling. The relative contribution of water and sediments in supplying P to macrophytes was measured by growing macrophytes in situ, rooted in ('32)P labeled sediments, and with the shoot in free contact with the unlabeled overlying water. Macrophytes grown in mesotrophic and eutrophic sites derived more than 95% of their P from the sediments alone. When grown in a hypertrophic site, the sediments still supplied 70% of the P. / Rates of P release by macrophytes and significance to their periphyton and surrounding phytoplankton were estimated by using fully labeled plants. The periphyton derived only 6.5% of its P form the macrophytes. Myriophyllum released 0.32 ug.g('-1).h('-1) P, most of which being readily available to phytoplankton. / The high vertical mobility of the available sediment-P was demonstrated both by experimental manipulations and direct observations.

Common Carp, (Cyprinus carpio), have long been associated with the degradation of wetlands worldwide. Through their feeding activities they resuspend sediments leading to reductions in the abundance and diversity of submerged macrophytes, and the alteration of water chemistry which can lead to the phytoplankton-dominated state. This study took in Delta Marsh, a freshwater coastal wetland of Lake Manitoba, in Manitoba, Canada. It was the second part of a four-year study in which baseline data were collected in 2001 from ten ponds (1-13 ha) with varying degrees of connectivity to the main marsh and carp-accessibility. I continued to monitor a subset of the control and altered ponds two and three years following their alteration (2003 and 2004); I included new ponds, including one large open bay (20.3 ha). The overall four-year study has shown that the presence of carp is at least partially responsible for the turbid, phytoplankton-dominated state that exists in Delta Marsh, and that carp abundance is an important factor. Ponds previously isolated then exposed to carp activity, particularly in the spring when they were gathered at high densities, shifted to the turbid, phytoplankton-dominated state with few macrophytes, and the removal of carp from ponds led to the clear-water state, though not necessarily an abundance of macrophytes. Due to the complexity of natural ecosystems, the effects of carp were not as predictable as smaller-scale studies would suggest. In my study, water quality, submerged vegetation biomass and algal growth varied both temporally and spatially in carp-accessible and carp-free ponds. Nutrient deficiency among periphyton assemblages was hypothesized to be alleviated by the presence of carp. Using nutrient diffusing substrata, I found that nutrient deficiencies varied from year to year among carp-free and carp-accessible ponds. In 2003 the hypothesis was supported, however, in 2004 two of the carp-free ponds exhibited no-nutrient limitations to periphyton assemblages while N and P co-limitation became prevalent in one carp-accessible pond. Parameters over which there was no control, such as the spatial and temporal distribution of carp, their density within a pond, water depth and unquantified top-down effects, including zooplankton grazing, may have contributed to the variability of the results.

Common Carp, (Cyprinus carpio), have long been associated with the degradation of wetlands worldwide. Through their feeding activities they resuspend sediments leading to reductions in the abundance and diversity of submerged macrophytes, and the alteration of water chemistry which can lead to the phytoplankton-dominated state. This study took in Delta Marsh, a freshwater coastal wetland of Lake Manitoba, in Manitoba, Canada. It was the second part of a four-year study in which baseline data were collected in 2001 from ten ponds (1-13 ha) with varying degrees of connectivity to the main marsh and carp-accessibility. I continued to monitor a subset of the control and altered ponds two and three years following their alteration (2003 and 2004); I included new ponds, including one large open bay (20.3 ha). The overall four-year study has shown that the presence of carp is at least partially responsible for the turbid, phytoplankton-dominated state that exists in Delta Marsh, and that carp abundance is an important factor. Ponds previously isolated then exposed to carp activity, particularly in the spring when they were gathered at high densities, shifted to the turbid, phytoplankton-dominated state with few macrophytes, and the removal of carp from ponds led to the clear-water state, though not necessarily an abundance of macrophytes. Due to the complexity of natural ecosystems, the effects of carp were not as predictable as smaller-scale studies would suggest. In my study, water quality, submerged vegetation biomass and algal growth varied both temporally and spatially in carp-accessible and carp-free ponds. Nutrient deficiency among periphyton assemblages was hypothesized to be alleviated by the presence of carp. Using nutrient diffusing substrata, I found that nutrient deficiencies varied from year to year among carp-free and carp-accessible ponds. In 2003 the hypothesis was supported, however, in 2004 two of the carp-free ponds exhibited no-nutrient limitations to periphyton assemblages while N and P co-limitation became prevalent in one carp-accessible pond. Parameters over which there was no control, such as the spatial and temporal distribution of carp, their density within a pond, water depth and unquantified top-down effects, including zooplankton grazing, may have contributed to the variability of the results.

No description available.

No description available.