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Les travaux menés durant cette thèse ont visé à évaluer la pertinence de la plante aquatique Myriophyllum aquaticum pour l'étude de la biodisponibilité du cuivre dans des sédiments ainsi que l'intérêt de la technique du gradient de diffusion en couche mince (DGT) comme outil biomimétique de cette plante. Une première expérimentation réalisée avec la plante M.aquaticum exposée selon le protocole du biotest normalisé (sous forme de verticilles) dans des sédiments artificiels dopés en cuivre a montré que ce biotest semble être un outil intéressant pour l'évaluation de la toxicité de sédiments contaminés en cuivre. En outre, aucune corrélation n'a été observée entre les mesures DGT et la bioaccumulation dans la plante M.aquaticum. Ceci est probablement lié aux conditions d'exposition des plantes. En effet, le développement des racines se faisant au cours de l'expérimentation, les processus d'incorporation du métal dans la plante ne sont donc pas constants au cours de l'expérience. Suite à ces résultats nous avons réalisé deux autres séries d'expérimentations (hydroponie et Rhizotest) dans lesquelles, les plantes ont été exposées selon un protocole modifié (plantes ayant déjà développé des racines avant leur exposition dans le sédiment). Ces expérimentations nous ont permis de montrer que la plante M.aquaticum est plutôt sensible au cuivre et qu'elle a une forte capacité à l'accumuler. De plus, les résultats obtenus ont permis de montrer que la technique DGT semble être un bon outil biomimétique de cette plante dans le cas où elle est exposée avec des racines car le prélèvement par la plante est limité par la capacité de la phase solide à réapprovisionner le métal en solution. / The work carried out during this thesis aimed to assess the relevance of the aquatic plant Myriophyllum aquaticum to study the bioavailability of copper in sediments as well as the interest of the technique of diffusion gradient in thin film (DGT) as a biomimetic tool of this plant. A first experiment, performed with the plant M.aquaticum exposed according to the protocol of the standardized bioassay (as whorls) in an artificial sediment spiked with copper, showed that this bioassay appears to be a useful tool for assessing the toxicity of contaminated sediments copper. Furthermore, no correlation was observed between DGT measurements and bioaccumulation in the M.aquaticum plant. This is probably due to the exposure conditions of the plants. In fact, as the root development occurs during the experiment, the process of incorporating the metal into the plant is therefore not constant throughout the experiment.Following these results we conducted two other series of experiments (hydropony and Rhizotest) in which, plants were exposed following a modified protocol (plants having already developed roots before their exposure in the sediment). These experiments showed that the plant M.aquaticum is rather sensitive to copper and has a strong ability to accumulate it. Futhermore, the results have shown that the DGT technique seems to be a good biomimetic tool for this plant when it is exposed by roots because the plant uptake is limited by the capacity of the solid phase to replenish the metal in solution.

<p>&nbsp; &nbsp; Razvojem testova inhibicije rasta na vrstama&nbsp; roda&nbsp;<em> Myriophyllum&nbsp;</em> ispitan je<br />potencijal&nbsp; vrsta <em>Myriophyllum&nbsp; aquaticum</em>&nbsp; (Vell.) Verd.&nbsp; i&nbsp;<em> Myriophyllum spicatum</em>&nbsp; L. u<br />ekolo&scaron;koj proceni rizika&nbsp; od herbicida i kontrole kvaliteta sedimenta. Ispitana je<br />primenljivost&nbsp; kontaktnog testa toksičnosti sedimenta sa vrstom&nbsp; M. aquaticum&nbsp; u<br />retrospektivnoj&nbsp; proceni&nbsp; rizika&nbsp; sedimenta&nbsp; na uzorcima iz prirode&nbsp; &ndash;&nbsp; na sedimentu&nbsp; reka Tami&scaron;, Krivaja i Jegrička.&nbsp; Testom toksičnosti sedimenta obogaćenog atrazinom,<br />analiziran je i potencijal kontaktnog testa u preventivnoj proceni rizika od hemikalija<br />koje pokazuju afinitet vezivanja za sediment. Testovima inhibicije rasta <em>M. aquaticum</em><br />i&nbsp; <em>M. spicatum&nbsp;</em> u voda-sediment sistemu ispitana je osetljivost i mogućnost primene<br />metode u preventivnoj proceni rizika od herbicida i regulatora rasta.<br />&nbsp; &nbsp; Deo rezultata dobijenih u radu uključen je u zavr&scaron;ne izve&scaron;taje internacionalnih<br />testova interkalibracije metoda,&nbsp; a kao rezultat ovih aktivnosti usvojene su nove<br />standardne metode na ukorenjenim akvatičnim makrofitama ISO 16191/2013 i OECD 239/2014.<br />&nbsp; &nbsp; &nbsp; Na osnovu istraživanja, zaključeno je da je kontaktni test toksičnosti<br />sedimenta&nbsp; jednostavan i lak za izvođenje, kao i da je vrsta<em>&nbsp; M. aquaticum</em>&nbsp; u jedno-komponentnom sistemu (sediment)&nbsp; adekvatan test model. Rastom kontrolnih biljaka, niskom varijabilno&scaron;ću i visokom osetljivo&scaron;ću biolo&scaron;kih&nbsp; odgovora zadovoljen je kriterijum validnosti testa. Preporučeno je kori&scaron;ćenje dodatne kontrole&nbsp; u&nbsp; slučajevima kada postoje značajna odstupanja u strukturi između&nbsp; standardnog sintetičkog kontrolnog i&nbsp; testiranog prirodnog sedimenta.&nbsp; Kontaktnim&nbsp; testom toksičnosti sedimenta obogaćenog&nbsp; atrazinom&nbsp; pokazano je da se ovaj test&nbsp; može smatrati potencijalno dobrom metodom za pro&scaron;irenje ekolo&scaron;ke procene rizika od hemikalija koje pokazuju afinitet vezivanja za sediment.<br />&nbsp; &nbsp; Ispitivanjem potencijala&nbsp; testa&nbsp; inhibicije rasta vrsta roda&nbsp;<em> Myriophyllum</em>&nbsp; u voda-sediment sistemu&nbsp; utvrđeno je da su testovi&nbsp; izvodljivi u praksi, da pokazuju&nbsp; visoki stepen stabilnosti, statističku snagu i malu varijabilnost&nbsp; većine&nbsp; ispitivanih parametara rasta. Poređenjem testova sa vrstama&nbsp;<em> M. aquaticum</em>&nbsp; i&nbsp;<em> M. spicatum</em>, nije utvrđena značajna&nbsp; razlika u osetljivosti na odabrane herbicide.&nbsp; Osetljivost&nbsp; testova na vrstama roda&nbsp; <em>Myriophyllum</em>&nbsp; i standardnih&nbsp; Lemna&nbsp; testova je bila slična,&nbsp; osim u slučaju auksin simulatora gde su&nbsp; vrste roda <em>Myriophyllum</em>&nbsp; sp. bile osetljivije,&nbsp; &scaron;to&nbsp; ukazuje&nbsp; na njihovu primenljivost u proceni rizika od pesticida specifičnog mehanizma toksičnog dejstva.<br />&nbsp; &nbsp; Iako&nbsp; obe vrste roda&nbsp; <em>Myriophyllum</em>&nbsp; imaju&nbsp; prednosti i nedostatke&nbsp; kao test<br />organizmi,&nbsp; vrste se&nbsp; mogu&nbsp; smatrati reprezentativnim akvatičnim ukorenjenim<br />makrofitama i predstavljati&nbsp; adekvatne&nbsp; dopunske test vrste u vi&scaron;im nivoima ekolo&scaron;ke<br />procene rizika od herbicida i regulatora rasta.&nbsp; Takođe, vrsta <em>M. aquaticum&nbsp; </em>je pogodna za&nbsp; testiranje u&nbsp; različitim test sistemima,&nbsp; a samim tim&nbsp; ima i veći&nbsp; potencijal primene u preventivnoj, ali i retrospektivnoj ekolo&scaron;koj proceni rizika.</p> / <p>Growth inhibition tests on <em>Myriophyllum&nbsp; aquaticum</em>&nbsp; (Vell.) Verd.&nbsp; and <em>Myriophyllum spicatum</em>&nbsp; L.&nbsp; were conducted in order to assess their use in refined risk assessment&nbsp; of chemicals, as well as in&nbsp; sediment&nbsp; risk assessment.&nbsp; The applicability, stability and sensitivity of the&nbsp;<em> M.&nbsp; aquaticum&nbsp; </em>sediment contact test on natural sediments (from rivers Tami&scaron;, Krivaja and&nbsp; Jegrička) was assessed for use in retrospective ecological risk assessment (ERA). The potential use of the spiked sediment contact test in risk assessment&nbsp; of&nbsp; sediment bound chemicals was&nbsp; also investigated. The sensitivity and applicability of the growth inhibition tests on&nbsp;<em> M. aquaticum</em>&nbsp; and&nbsp; <em>Myriophyllum </em>spicatum&nbsp; in a water-sediment system was assessed for potential use in prospective ERA of plant protection products.</p><p>A part of the results of this study was included in the final report of the two&nbsp; international ring tests, which resulted with new standardised methods with rooted macrophytes:&nbsp; ISO 16191/2013 i&nbsp; OECD&nbsp; 239/2014. Tests on&nbsp; <em>Myriophyllum</em>&nbsp; species were compared to standard Lemna&nbsp; tests.&nbsp; Test substances in <em>M. aquaticum</em>&nbsp; and&nbsp; <em>Lemna minor&nbsp; L</em>. tests were 3,5 dichlorphenol, atrazine, isoproturon, trifluralin, 2,4 D and dicamba, while substances used in&nbsp;<em> M. spicatum&nbsp;</em> tests were atrazine, isoproturon and 2,4 D.</p><p>The sediment contact test proved to be simple and robust, while <em>M. aquaticum</em> can be considered as an adequate test model in a one-compartment (sediment) test. The validity criteria regarding control plant growth and variability was met. The use of an additional control is suggested when testing of sediments with considerably different properties of the standard synthetic control is taking place.&nbsp; The spiked sediment contact tests with atrazine showed that the method could be applied in prospective risk assessment of sediment bound chemicals.</p><p>The water-sediment growth inhibition test with&nbsp; <em>Myriophyllum</em>&nbsp; species proved to be applicable in practice, with high stability, statistical power and low variability of the majority of the growth parameters.<em>&nbsp; M. aquaticum&nbsp;</em> and&nbsp; M. spicatum&nbsp; didn&rsquo;t show major&nbsp; differences&nbsp; in sensitivity to tested substance.&nbsp; The sensitivity of&nbsp; <em>Myriophyllum</em> and&nbsp; Lemna&nbsp; tests was also similar, except to auxin simulators, where&nbsp; <em>Myriophyllum </em>species were considerably more sensitive, which makes them adequate&nbsp; candidates for use in risk assessment of chemicals with specific mode of action.</p><p>Even though both&nbsp; <em>Myriophyllum</em>&nbsp; species show advantages and disadvantages as test organisms, they can be regarded as representative rooted aquatic macrophyte species and additional test species in refined risk assessment of herbicides and growth regulators. &nbsp;Also,&nbsp; <em>M. aquaticum&nbsp; </em>can be tested in various test syytems, which makes this species &nbsp;applicable in prospective as well as retrospective ecological risk assessment.</p>

Thesis (doctoral)--Universität Jena. / Vita. "Sonderabdruck aus 'Flora oder allg. bot. Zeitung', 1899, Heft 3." Includes bibliographical references.

Le but de ce travail de thèse est de démontrer l’intérêt d’un macrophyte aquatique submergé, Myriophyllum alterniflorum pour la détection de contaminants dans l’environnement. Des études in situ ont été réalisées pendant 28 jours sur cinq milieux aquatiques, affectés par différents types de pression anthropique, durant trois campagnes de terrain (printemps 2015, automne 2015 et printemps 2016), pour déterminer si l’accumulation des contaminants dans la plante et si des biomarqueurs du myriophylle peuvent être utilisés pour détecter la présence de contaminants dans les eaux. L’accumulation des contaminants au cours du temps était corrélée avec les teneurs des contaminants dans l’eau ; l’influence de la durée d’exposition a été étudiée. Au cours des trois campagnes, la réponse des biomarqueurs, teneur en MDA et activité de nitrate réductase était corrélée avec les teneurs en contaminants dans l’eau et dans la plante ; cependant l’influence de la durée d’exposition sur l’évolution de la réponse des biomarqueurs est moindre par rapport à celle de l’accumulation des contaminants. Ainsi, l’étude des biomarqueurs pourrait permettre une évaluation plus fiable de la qualité des masses d’eau que le suivi de l’accumulation dans la plante. Au cours de la campagne printemps 2015, un panel de biomarqueurs plus large a été étudié afin de définir les biomarqueurs les plus pertinents pour détecter spécifiquement les pressions liées aux activités urbaines ou industrielles. Une méthodologie d’évaluation de la qualité des eaux est proposée, en considérant un protocole d’analyse des biomarqueurs : un premier dosage de Chlb et MDA est simple et moins coûteux. Quand aucune preuve d'impact anthropique n'est montrée, aucune analyse complémentaire n'est requise. En revanche, lorsqu’une altération est mise en évidence, l’analyse d'autres biomarqueurs plus spécifiques tels que les activités G6PDH et γ-GCS sera nécessaire. La réponse de l'activité γ-GCS est spécifique du stress métallique, ainsi, la réponse de ce biomarqueur devrait amener à réaliser l’analyse des métaux/métalloïdes dans M. alterniflorum. / The aim of this thesis is to demonstrate the interest of a submerged aquatic macrophyte, Myriophyllum alterniflorum for the detection of contaminants in the environment. In situ studies were conducted over 28 days in five aquatic environments, affected by different levels of anthropogenic pressure, during three field seasons (spring 2015, autumn 2015 and spring 2016), to determine whether the accumulation of contaminants in the plant and whether biomarkers can be used to detect the presence of contaminants in water. The accumulation of contaminants over time was correlated with the levels of contaminants in the water; the influence of the duration of exposure has been studied. In all three campaigns, biomarker response, MDA content, and nitrate reductase activity were correlated with contaminant levels in water and in the plant; however, the influence of the duration of exposure on the evolution of the biomarker response is lower compared to the accumulation of contaminants. Thus, the study of biomarkers could allow a more reliable assessment of the quality of water bodies than the monitoring of contaminant accumulation in the plant. During the spring 2015 campaign, a much broader biomarker panel was investigated to define the most relevant biomarkers for assessing water quality. A methodology for evaluating water quality is proposed, considering a biomarker analysis protocol: a first assay of Chlb and MDA is simple and less expensive. When no evidence of human impact is shown, no further analysis is required. On the other hand, when an alteration is highlighted, the analysis of other more specific biomarkers such as G6PDH and γ-GCS activities will be necessary. The response of γ-GCS activity is specific for metal stress, so the response of this biomarker should lead to the analysis of metals / metalloids in M. alterniflorum.

A 2 x 2 factorial design investigated effects of sediment nitrogen and water potassium levels on autofragment production. Reduced nitrogen levels significantly increased autofragment production whereas potassium levels did not significantly alter production. Up to 50% of autofragment production abscised from parent plants grown under low nitrogen conditions compared to 12% or less under high nitrogen conditions.

Non-native macrophytes structurally impact aquatic assemblages, yet little is known regarding how they influence energy pathways in freshwater ecosystems. Allelopathy in Eurasian watermilfoil- Myriophyllum spicatum has been shown to target basal epiphytic organisms resulting in differences in assemblage structure of colonizing epiphyton between M. spicatum and native M. sibiricum. I conducted a growth chamber experiment to investigate the hypothesis that differences in assemblage structure of colonizing epiphyton between these two macrophytes influence trophic dynamics within aquatic systems. My data suggest M. spicatum produces higher concentrations of allelochemicals, resulting in a more diverse epiphytic assemblage compared to M. sibiricum. This could result in potential transformation of trophic dynamics by decoupling carbon as it flows from primary producer to primary consumer. This work identifies a contributing mechanism responsible for M. spicatum invasiveness and provides new insight in its ecology and management of this non-native macrophyte.

Eurasian watermilfoil (Myriophyllum spicatum) habitat was predicted at multiple scales, including a lake, regional, and national level. This dissertation illustrates how habitat can be predicted for M. spicatum using publically-available data for both presence and environmental variables. Models were generated using statistical procedures and quantative methods to determine where the greatest likelihood of presence was located. For the single lake, presence and absence data were available, but the larger-scale models used presence-only methods of prediction. These models were paired with a Geographic Information System so that data could be visualized on a map. For the selected lake, Pend Oreille (Idaho), spatial analysis using general linear mixed models was used to show that depth and fetch could be used to predict habitat, although differences were seen in their importance between the littoral and pelagic zones. For the states of Minnesota and Wisconsin, Mahalanobis distance and maximum entropy methods were used to demonstrate that available habitat will not always mean presence of M. spicatum. The differing approaches to management in these states illustrated how an aggressive public education campaign can limit spread of M. spicatum, even when habitat is available. Bass habitat appeared to be the largest predictor of M. spicatum in Minnesota, although this was due to the similar environmental preferences by these species. Using maximum entropy, on a national level, presence of M. spicatum appeared to be best predicted by annual precipitation. Again, results showed that habitat is colonized as time permits, and not necessarily as conditions permit.

L’utilisation des plantes aquatiques comme indicateurs de la qualité des eaux de rivière a débuté dès le XXème siècle. Parmi les macrophytes utilisés, le myriophylle à fleurs alternes, Myriophyllum alterniflorum a démontré dans plusieurs études sa capacité bioaccumulatrice des métaux et son intérêt en tant que bioindicatrice de qualité de l’eau. L’objectif de cette étude est d’identifier chez cette espèce des biomarqueurs sensibles pour la détection précoce de pollution d’une rivière par un métal, le cuivre et un métalloïde, l’arsenic. Pour atteindre cet objectif, un milieu synthétique dont la composition est représentative de la qualité des eaux de la rivière Vienne, a été préparé (milieu Vienne). Une fois les conditions opératoires maîtrisées, le développement du macrophyte est suivi dans trois milieux : un milieu témoin, un milieu contaminé en cuivre et un autre en arsenic avec des concentrations d’exposition au polluant de 100 µg/L pendant 21 jours. Durant cette période, des biomarqueurs physiologiques (activités respiratoires et photosynthétiques, potentiel osmotique), biochimiques (les concentrations en chlorophylle a, b et en caroténoïdes, les teneurs en malondialdéhyde, les phytochélatines) ont été analysés. Ces suivis ont été réalisés en système fermé dans des boites de culture de 400mL in vitro en tenant compte de la trophie du milieu (condition eutrophe et oligotrophe), puis en système recirculé dans des aquariums de 150 L, toujours dans le milieu Vienne, mais cette fois en se plaçant dans différentes conditions hydrodynamiques (zones turbulente, laminaire à une vitesse de 3 cm/s et calme). / Alternate watermilfoil, Myriophyllum alterniflorum is an aquatic macrophyte presented in the rivers of the Limousin region in France whose potential for bioindication of metal pollution has been demonstrated. The objective of this study is to identify in this species sensitive biomarkers for the early detection of pollution in a river by a metal copper, and a metalloid, arsenic. To achieve this goal, a synthetic medium whose composition is representative of the water quality of the river Vienne, was prepared (Vienne medium). The composition of the medium studied is verified by ICP-MS and ion chromatography (IC). The development of the macrophyte was followed in a control medium, a copper contaminated medium and another contaminated with arsenic at a concentration of 100 µg/L for 21 days. During this period, the respiratory and photosynthetic activities of Myriophyllum alterniflorum, the concentrations of chlorophyll a, b and carotenoids, levels of malondialdehyde, osmotic potential, and phytochelatins were recorded. This monitoring has been made in a closed system (400mL culture boxes) taking into account the trophy of the medium (eutrophic and oligotrophic conditions), and then in a recirculating system (aquariums of 150 L) taking into account the hydrodynamic conditions (turbulent, laminar and quiet areas).

Durch die Freisetzung allelopathisch aktiver Substanzen können Makrophyten das Wachstum von Phytoplankton beeinflussen und damit den Klarwasserzustand von Flachseen stabilisieren. Umweltfaktoren beeinflussen allelopathische Effekte und wurden untersucht, um die Bedeutung allelopathischer Effekte im Ökosystem einzuschätzen. Der Gehalt allelopathisch aktiver polyphenolischer Substanzen zeigte Schwankungen bis zu einer Größenordung im Apikalmeristem von Myriophyllum verticillatum L innerhalb von vier Jahren 2004-2007, die nur teilweise durch den Nährstoffgehalt in der Pflanze erklärt wurden. Der Gehalt an Polyphenolen in der Trockenmasse der Pflanze korrelierte mit der Wachstumshemmung von Anabaena variabilis im Biotest und zeigte Maxima im Mai bis Juli wenn Konkurrenz mit dem Phytoplankton um Licht beim Wachstum zur Wasseroberfläche besteht. Mittels HPLC und MS gelang die Identifizierung von Hexahydroxydiphenoyl di- und -tri-galloylglucose Isomeren in den hauptaktiven Fraktionen des Pflanzenextraktes. Abiotische und biotische Einflüsse der Umwelt auf die Allelochemikalie z.B. photolytische und mikrobielle Umwandlungsprozesse führten bei der Modellsubstanz Tanninsäure (TA), die in Struktur und Funktion den gefundenen Allelochemikalien ähnelt, zur Bildung von refraktären hochmolekularen Verbindungen mit anhaltender allelopathischer Wirkung, die mittels LC-OCD den Huminstoffe zugeordnet wurden. Temperatur als weiterer Umweltfaktor beeinflusste artspezifisch die Reaktion der untersuchten Algen auf TA. Dabei waren die Art und das Ausmaß der Reaktion von der Anwesenheit von Bakterien abhängig. Bakterien der Gattung Pseudomonas wurden isoliert, die in der Lage waren, TA abzubauen und deren allelopathische Effekte zu mindern. Es konnten gezeigt werden, dassl Umwelteinflüsse auf die Allelochemikalie, mutualistische Phytoplankton-Bakterien Interaktionen und die Zusammensetzung der Bakteriengemeinschaft allelopathische Effekte qualitativ als auch quantitativ beeinflussten. / Dissolved organic compounds released by macrophytes can have allelopathic effects on phytoplankton and thereby contribute to stabilize the clear water state of shallow lakes. Identifying factors influencing allelopathy enables evaluating allelopathic effects in the ecosystem.One factor is the temporal dynamic of allelopathically active substances and was investigated as total phenolic compounds(TPC). TPC ranged by an order of magnitude in apicals of Myriophyllum verticillatum L. during four years (2004-2007). Nutrient content partly explained TPC dynamic. The highest amounts of TPC in plant tissue corresponded to maximal growth inhibition of Anabaena variabilis in biotest from May to July when macrophytes compete with algae for light to grow to the water surface. Isomers of Hexahydroxydiphenoyl -di- and -trigalloylglucose identified by HPLC and LC-MS were found in the most allelopathically active fractions in the biotest. By the use of analytical and molecularbiological methods photolytic transformation and degradation by bacteria, changes in mutualistic interaction of bacteria and phytoplankton and shifts in bacterial community composition were identified as factors influencing the allelochemical and the phytoplankton response to TA quantitatively and qualitatively. Photolytic and microbial transformation formed long lasting allelopathically active degradation products of an allelopathic test substance, tannic acid (TA). Temperature was shown to influence the phytoplankton response to TA species specifically varying with presence or absence of bacteria. Bacteria community composition mediated phytoplankton response and specific bacteria as Pseudomonas sp.were able to degrade allelochemicals as TA and thereby lowered the allelopathic effect. Thus, allelopathic effects can be influenced by abiotic and biotic factors acting on the allelochemical, the target organisms and on mutualistic interaction between target organisms altering the outcome of allelopathic effects.