This study has contributed to the development of the reference condition approach in disturbed landscapes. The reference condition approach has been an important development for the bioassessment of aquatic ecosystems by providing a practical tool for the accurate assessment of river condition. The selection of appropriate reference sites is critical to the success of the predictive model in terms of being able to distinguish between natural variation in biota and the effects of human disturbance. Capturing natural variability and explaining it is a key difference between the reference condition approach and other study designs (e.g. before/after/control/impact). Natural disturbances such as drought or bushfire can significantly alter the ecological condition of streams, and although the ecological condition of streams affected by natural drought or bushfire is part of the natural cycle, this natural variation of the ecological condition is rarely incorporated into many study designs because of a mismatch in time scales. Human disturbance has also significantly altered the condition of landscapes through the development of agriculture and urbanisation. In urban or agricultural landscapes it can be impossible to locate streams that have not been modified by human activity for use as a reference condition. This study looked at the effects of natural disturbance on the reference condition, in terms of the way natural disturbance affects the prediction of stream condition and also the incorporation of the condition of streams experiencing natural disturbance into a predictive model. Additionally this study identified an alternative benchmark for modified landscapes based on the presence of good management practices for river protection, and tested this benchmark for the assessment of streams impacted by urbanisation. Drought and bushfire regularly disturb aquatic ecosystems in Australia, and affected reference sites in the ACT and South Coast region of New South Wales in 2002 and 2003. Drought and bushfire conditions affected macroinvertebrates and environmental variables across these streams, and the majority of sites were assessed as significantly impaired using regional AUSRIVAS (AUstralian RIVers Assessment System) models. This indicated the existing reference conditions for these regions had not incorporated the ecological conditions of reference sites suffering these natural disturbances. Many of the environmental variables used to predict the condition of streams were also affected by drought or bushfire. The changes to environmental variables affected how sites were assessed in models, but the overall assessment was not significantly changed from the initial assessment that drought or bushfire had significantly impaired the ecological condition. To reduce potential assessment errors associated with changes to predictor variables an attempt was made to construct new models with changeable variables excluded. However, it was not possible to completely exclude these types of variables, and subsequent models were no better than the original models in terms of changes to predictor variables affecting the generation of expected taxa lists. The changes to environmental variables did not affect the actual assessment of site condition because although group membership probabilities were changed the probabilities of taxon occurrence did not change significantly. The different reference site groups all contained some common taxa that occurred at most sites and even when group probabilities changed this did not change the probability of these taxa occurring at a test site. For regional models, such as the ACT or NSW South Coast, changes to predictor variables may not significantly affect the assessment of site condition. Incorporating reference sites under drought conditions into a predictive model was an effective way of discriminating the effects of drought from human disturbance. The model only provided two different ecological conditions, a single drought measurement and a single non-drought measurement, so the model did not fully encompass the potential natural variability. The model has value as a starting point and was effective in distinguishing sites affected by human disturbance from sites affected by drought. Good Management Practice (GMP) for river protection is any intervention that minimises human impact on stream condition. Urban sites protected by GMP were used as an alternative benchmark to a minimally impacted reference condition. The criteria used to select reference sites were not sufficiently robust to detect a significant benefit of GMP on physical or chemical characteristics of protected sites, compared to sites without GMP. In general however, the physical and chemical condition of GMP sites was better than sites without GMP and there were significant differences in macroinvertebrate assemblages of GMP and non-GMP sites. A refinement to the site selection process is proposed to include a specific assessment of GMP effectiveness for the protection it is designed to provide. This will substantially improve the robustness of a GMP benchmark and provide a clearer picture of the factors controlling biota in urban streams protected by GMP. The GMP benchmark was developed into a predictive model for the assessment of urban stream health, and in terms of the assessment of test site condition, it did not differ significantly from a model using minimally impacted sites. The purpose of the GMP benchmark was to provide an alternative reference condition for the assessment of stream health in modified landscapes when minimally impacted sites are unavailable or provide an unattainable benchmark. The GMP reference condition as an alternative can provide an attainable and realistic benchmark. The development and application of the suggested site selection protocol will improve the robustness of the GMP benchmark and better account for natural variation in the biota and physical characteristics of the sites used to determine the reference condition.

No description available.

Using paleolimnological techniques, I have studied surface-water acidification and the effects of liming in Swedish lakes on a decadal to millennial time-scale. The overall objective was to contribute to the discussion on the fulfilment of goals within the Swedish liming program. One of the main goals of this program is to restore lakes to natural or nearly natural conditions, i.e. to a reference condition as termed in the EU Water Framework Directive. In this context, a key issue is to define reference conditions. This is a central theme of my thesis, as lake sediments offer a unique way to study past lake conditions. Past lake-water acidity of 12 reference lakes in the Swedish liming program (ISELAW) was determined using diatom analysis of sediment cores. Pollen, lead, and flyash from coal/oil combustion were used as indicators of impact from land use and atmospheric pollution. A general trend in these lakes is an initial decline in pH after lake formation due to natural soil processes, which was then followed by rather low pH values (pH 5.3-6.5). In six of the lakes pH increased as a result of expansion of agriculture (burning, forest grazing) 2000 to 1000 years ago. Local mining and long-range airborne pollution have also impacted the lakes since medieval time. These results show that the conditions of the study lakes were not natural prior to industrialization and recent (20th century) acidification. The ISELAW lakes were selected on the basis of representing typical limed lakes, and they have been limed and monitored since at least the 1980s. A comparison of chemical/biological monitoring data and the paleolimnological data gives somewhat diverging results. Most of the monitoring data suggest that the lakes were subjected to acidification during the 20th century, but the paleolimnological data can only identify clear evidence of acidification in five of the 12 lakes, hence, all lakes were probably not recently acidified. According to conclusions from monitoring the lakes have recovered following liming. The paleolimnological data give a more complex picture and three different responses have been identified: 1) a return to a diatom composition found in the lake one hundred to several thousand years ago; 2) very small shifts in the diatom composition; or 3) a diatom composition previously not found in the lake. The latter response raised the question whether liming can cause an unnatural diatom community. A comparison of diatoms in surface sediment samples of 31 limed lakes with pre-industrial reference samples from 291 lakes showed that liming does not create an unnatural diatom composition. These results illustrate that the goals for liming were not reached in all of the limed lakes, and that paleolimnology can play an important role for assessments of acidification and liming. The comparative study also highlights the importance of designing monitoring programs that can produce reliable and long data series. Given the results of the paleolimnological investigations, it is obvious that we cannot assume that the 19th century represented a natural or near natural state, and thus is a realistic reference conditions. Natural long-term lake development and previous land-use impacts need to be considered in defining reference conditions. Neither can we disregard the fact that humans always will impact nature. Although paleolimnological studies are time consuming, I believe that they could be simplified to the extent that paleolimnology could become a routine method for environmental management.

<p align="justify"><i>Typologie des cours d’eau en Wallonie et caractérisation par la faune invertébrée</i><br>Vingt-cinq types de cours d’eau ont été définis en Wallonie d’après les termes de la Directive Cadre pour l’Eau en tenant compte des facteurs obligatoires et optionnels rassemblés sous trois critères : la taille (du « ruisseau » à la « très grande rivière »), la pente (faible, moyenne et forte), et cinq régions naturelles (la région limoneuse, le Condroz, la Famenne, l’Ardenne et la Lorraine belge, résumant les facteurs obligatoires altitude, latitude, longitude et géologie). Une approche par analyses multivariées appliquées à un grand nombre d’échantillons (listes taxonomiques) a permis de définir de façon plus précise certains types de rivières et de distinguer sept groupes typologiques montrant des assemblages faunistiques similaires.</p> <p align="justify"><i>Conditions de référence types et définition de l’état écologique des rivières en Wallonie à l’aide de métriques biocénotiques basées sur les invertébrés</i><br> Les listes faunistiques et les valeurs métriques de l’IBGN (Indice biologique global normalisé) issues du réseau d’évaluation de la qualité biologique en Wallonie ont été utilisées pour discriminer les types de rivières et pour définir les sites de référence, les conditions de référence et les limites des classes des états écologiques. Au sud du sillon Sambre et Meuse, impliquant quatre groupes typologiques de rivières, les valeurs de référence et la définition des états écologiques ont été basées et calculées sur un réseau de référence de sites de très bon état. Les « valeurs de conditions de référence » ont été définies par les médianes des métriques des sites de « très bon état ». Lorsque aucun site de très bon état n’était disponible, c’est-à-dire pour les groupes typologiques au nord du sillon Sambre et Meuse et pour la Meuse et la Sambre, les conditions de référence (ou le « potentiel écologique maximal ») et les limites de classes ont été basées sur des coefficients appliqués aux sites de « bon état » et sur jugement d’expert.</p> <p align="justify"><i>Exercice pilote d’inter-étalonnage</i><br> Cinquante échantillons ont été sélectionnés parmi les rivières du type d’inter-étalonnage européen R-C3 (petite taille, altitude moyenne, substrat siliceux) en Wallonie (correspondant aux « ruisseaux ardennais ») dans toute la gamme de qualités écologiques, du « très bon » au « mauvais » état. Chaque métrique de l’indice « Intercalibration Common Metrics » (ICM) a été comparée (par régression linéaire et polynomiale) aux valeurs de l’IBGN. La plus forte corrélation a été établie avec l’indice synthétique de l’ICM dont le R² très élevé (0,95) permet un inter-étalonnage précis et fiable. A un EQR (Equivalent Quality Ratio) de l’IBGN = 1 correspond un indice ICM très proche (= 1,004). En conséquence, la métrique « cote de l’IBGN » est proposée comme métrique pour l’évaluation de l’état écologique de la faune invertébrée en Wallonie.</p> <p align="justify"><i>Espèces exotiques et invasives</i><br>L’ouverture récente du canal à grand gabarit Main – Danube en 1992 et la navigation qui en résulte a permis à plusieurs espèces de macroinvertébrés ponto-caspiennes d’envahir successivement les bassins du Rhin et de la Meuse. De 1998 à 2000, le réseau de mesure a enregistré quatre nouvelles espèces exotiques dans la Meuse en Belgique : une polychète (<i>Hypania invalida</i>) et trois crustacés (<i>Hemimysis anomala, Dikerogammarus villosus, D. haemobaphes</i>). Peu avant, en 1995, le bivalve asiatique <i>Corbicula fluminea</i> et l’amphipode nord-américain <i>Crangonyx pseudogracilis</i> ont également été enregistrés pour la première fois. La dynamique des invasions a été étudiée et discutée.</p> <p align="justify">L’<i>état biologique actuel</i> (2000-2002) des masses d’eaux de surface en Wallonie et l’évolution des états biologiques sur une décennie (1990-2002) figurent dans l’étude et sont discutés. Une amélioration globale de la qualité de 6 % est enregistrée pour cette période. L’amélioration de la qualité se manifeste principalement pour les états « mauvais » et « médiocre » s’élevant à l’état « moyen ».</p> <b>Abstract</b> <p align="justify"><i>River typology in Wallonia and invertebrate fauna characterization</i><br>Twenty-five river-types in Wallonia were defined according to the Water Framework Directive taking into account obligatory and optional factors gathered in three criteria: the size (from “brook” to “very large river”), the slope (gentle, medium and strong) and five natural regions (Loess, Condroz, Famenne, Arden and Jurassic summarising the obligatory altitude, latitude, longitude and geology factors). A multivariate approach applied to a large amount of samples (i.e. taxa lists) led to give a more accurate definition of some river-types and to discriminate seven river-type groups exhibiting similar faunal assemblages.</p> <p align="justify"><i>Type-specific reference conditions and ecological status definition of rivers in Wallonia using invertebrate biocenotic metrics</i><br> Faunal lists and IBGN (i.e. "Standardized Global Biological Index IBGN") metric values, evolving from the biological quality assessment network in Wallonia, were used to discriminate the river types and to define the reference sites, the reference conditions and the status class limits. South of the axis made by the Sambre & Meuse Rivers, involving four river-type groups, reference values and ecological status definition were based and calculated on a reference network of sites of high status. The "reference condition values” were defined as the median values of the metrics in all “high status” sites. Where no site of high status was available, i.e. in the others river-type groups north of the same axis and in the Rivers Sambre and Meuse themselves, reference conditions (or maximum ecological potential) and class limits were based on coefficients applied to “good status” sites and on expert judgement.</p> <p align="justify"><i>Intercalibration pilot exercise</i><br> Fifty samples were selected from R-C3 rivers (i.e. small, mid-altitude, siliceous) in Wallonia (corresponding to the “Arden’s brooks”) showing the widest range of ecological quality from high to bad status. Each Intercalibration Common Metric (ICM) was compared (linear and polynomial regression) to IBGN scores. The highest correlation was found with the synthetic ICM index, whose high R² (0.95) allows accurate and reliable intercalibration. To IBGN EQR (i.e. Equivalent Quality Ratio) = 1 corresponds a very close ICM index value (= 1.004). Consequently, the metric IBGN score is being proposed to act as the metric for the assessment of the invertebrate fauna ecological status in Wallonia, Belgium.</p> <p align="justify"><i>Exotic and invasive species</i><br> The recent opening of the canal Danube – Main in 1992 and the subsequent navigation allowed several Ponto-Caspian macroinvertebrate species to invade successively the Rhine and the River Meuse basins. From 1998 to 2000, the monitoring network recorded four new alien species in the River Meuse in Belgium: one Polychaeta (<i>Hypania invalida</i>) and three Crustacea (<i>Hemimysis anomala, Dikerogammarus villosus, D. haemobaphes</i>). Earlier, in 1995, the Asian Bivalvia <i>Corbicula fluminea</i> and the North American Amphipod <i>Crangonyx pseudogracilis</i> were also recorded for the first time. The invasions’ dynamics were studied and discussed.</p> <p align="justify"><i>Present biological status</i> (2000-2002) of surface water-bodies in Wallonia and biological status evolution over a one-decade period (1990-2002) is included and discussed in the study. A global quality improvement of 6 % is recorded for the period. Quality improvement concerns mainly the “bad” and “poor” status raising up to “moderate” status.</p>

Made available in DSpace on 2017-07-10T14:38:35Z (GMT). No. of bitstreams: 1 Renata.pdf: 1386030 bytes, checksum: 535c46b1abd87bc9822da8e752d70575 (MD5) Previous issue date: 2012-08-10 / The identification of minimally impacted sites and the selection of metrics for assessing the effects of human activities on aquatic environments has been a key issue in the management of these ecosystems. This paper presents a practical and easy method to identify reference sites and selection of the most significant metrics that reflect the general attributes of the assemblies, altered by human impacts. For this we evaluated the biotic integrity in some neotropical streams, located in Paraná state, Brazil, through the benthic macroinvertebrates and fish. The identification of reference sites was based on the physical and chemical quality of the habitat, and the physical and chemical variables summarized by principal component analysis, and submitted to cluster analysis to identify the reference sites. Sixteen metrics were calculated, which were submitted to a discriminant analysis to select the most significant metrics. The principal component analysis and cluster analysis showed that the reference sites were selected according to composition ande physical quality of the sediment. These sites were positively correlated with larger particles such as pebbles and negatively associated with smaller particles. The discriminant analysis showed that few metrics are sufficient to identify changes in the assemblies by human activities and that assemblies respond differently to environmental changes. In the pooled analysis of the assemblies the metrics selected for macroinvertebrate were different than metrics selected in the analysis performed solely for that assembly, in the pooled analysis were selected metrics abundance, percentage of tolerant and percentage of shredders, whereas in exclusive analysis were selected metrics richness and percentage of tolerant. Greater richness of macroinvertebrates were observed at pristine sites, while the percentage of tolerance increased with the gradient of impact. On the other hand, for the fish assemblage were selected metrics of richness, diversity and percentage of omnivores. Greatest richness were observed in moderately impacted sites, while higher values of diversity and percentage of omnivores were observed in reference sites. The analysis of the metrics of the two assemblages provided a more robust evaluation the sites categorized according to a gradient of impact, than the separate evaluation of the assemblages. However, the benthic macroinvertebrates assemblage was equally effective to confirm the reference sites. The procedure presented in this paper can easily assist managers in selecting effective methods for protecting and restoring stream ecosystems / A identificação de locais minimamente impactados e a seleção de métricas para a avaliação dos efeitos das atividades humanas sobre os ambientes aquáticos tem sido uma questão chave na gestão desses ecossistemas. Este trabalho apresenta um método protocolo para a identificação de locais de referência e seleção de métricas mais significativas, que refletem os atributos gerais das assembleias, alteradas pelos impactos humanos. Para isso foi avaliada a integridade biótica em alguns riachos neotropicais, localizados no estado do Paraná, Brasil, através da fauna de macroinvertebrados bentônicos e peixes. A identificação dos locais de referência foi realizada com base na qualidade física e química do habitat, sendo as variáveis físicas e químicas sumarizadas pela análise de componentes principais e submetidas à análise de agrupamento para a identificação dos locais de referência. Foram calculadas dezesseis métricas, as quais foram submetidas a uma análise discriminante para a seleção das métricas mais significativas. A análise de componentes principais e a análise de agrupamento revelaram que os locais de referência foram selecionados de acordo com a composição e qualidade física do sedimento. Esses locais foram correlacionados positivamente com partículas maiores, como seixos e, negativamente, com partículas menores. A análise discriminante demonstrou que poucas métricas são suficientes para identificar alterações nas assembleias decorrentes de atividades humanas e que as assembleias respondem de maneira distinta às alterações ambientais. Na análise conjunta das assembleias as métricas selecionadas para macroinvertebrados foram diferentes das métricas selecionadas na análise realizada para essa assembleia exclusivamente, na análise conjunta foram selecionadas as métricas de abundância, percentagem de tolerantes e percentagem de fragmentadores, enquanto que na análise exclusiva foram selecionadas as métricas de riqueza e percentagem de tolerantes. Maiores valores de riqueza de macroinvertebrados foram observados em locais prístinos, enquanto que a percentagem de tolerantes aumentou de acordo com o gradiente de impacto. Por outro lado, para a ictiofauna foram selecionadas as métricas de riqueza, diversidade e percentagem de onívoros. Maiores valores de riqueza foram observados nos locais moderadamente impactados, enquanto que maiores valores de diversidade e percentagem de onívoros foram observados nos locais de referência. A análise das métricas das duas assembleias proporcionou uma avaliação mais robusta dos locais categorizados, segundo um gradiente de impacto, do que a avaliação isolada das assembleias. Entretanto, a assembleia de macroinvertebrados bentônicos foi igualmente eficiente para confirmar os locais de referência. O procedimento apresentado neste trabalho poderá facilmente auxiliar os gestores na seleção de métodos eficazes para a proteção e restauração de ecossistemas lóticos

Le bassin hydrographique de la Seine figure parmi les bassins français les plus anthropisés. Les communautés piscicoles qui le peuplent sont potentiellement marquées par les pressions humaines qui s'exercent sur le milieu aquatique, et dont l'ampleur depuis l'Époque industrielle a été grandissante. L'objectif de ce travail était d'identifier les facteurs à l'origine des modifications de la répartition des peuplements de poissons sur le temps long. Afin de mettre en évidence les possibles changements intervenus durant les deux derniers siècles, ce travail a été mené en croisant deux types d'approches, l'une historique et l'autre écologique. Cette étude, basée sur des données d'observations de poissons dans le bassin de la Seine depuis le début du XIXe siècle, montre une importante modification de la faune piscicole (i.e. introductions et disparitions d'espèces) à l'échelle du bassin. Par ailleurs. L’analyse comparative des données historiques, pour lesquelles existent des mentions d'abondances, et des données écologiques actuelles montre que les aires de répartition de certaines espèces ont été très largement modifiées. Sur différents secteurs du bassin, les résultats témoignent d'évolutions parfois importantes de la composition des peuplements en lien avec différents types de pressions anthropiques exercées sur le milieu à des échelles d'espace et de temps variées. Ce travail confirme l'intérêt d'une approche interdisciplinaire dans la compréhension de l'histoire des écosystèmes. De futures recherches sont néanmoins nécessaires afin de cerner l'importance de facteurs plus locaux sur la répartition des espèces piscicoles. / In France, the Seine River basin has been harshly impacted by anthropogenic pressures since the Industrial revolution. Fish community is expected to be disturbed by these human pressures on aquatic environment. This thesis aimed to highlight the factors involved in the changes of fish species spatial distribution over the last two centuries using both historical and ecological approaches. The analysis of historical data of fish distributions on the Seine River basin showed some important modifications of fish communities (i.e. species introductions and extinctions) at the catchment scale, since the beginning of the XIXth century. The comparative study based on historical abundances and actual data showed that certain species have changed their distribution area. Besides, substantial evolutions in fish assemblages occurred in certain rivers, probably in relation to anthropogenic pressures acting at different spatial and temporal scales. This study confirms the interest of an interdisciplinary approach to improve knowledge of ecosystems' history. Nevertheless, future researches are still needed to better understand the effects of local factors on fish distribution area.

Evaluer, maintenir et restaurer les conditions écologiques des rivières nécessitent des mesures du fonctionnement de leurs écosystèmes. De par leur complexité, notre compréhension de ces systèmes est imparfaite. La prise en compte des incertitudes et variabilités liées à leur évaluation est donc indispensable à la prise de décision des gestionnaires. En analysant des données nationales (~ 1654 sites), les objectifs principaux de cette thèse étaient de (1) tester certaines hypothèses intrinsèques aux bio-indicateurs et (2) d'étudier les incertitudes de l'évaluation écologique associées à la variabilité temporelle des bio-indicateurs et à la prédiction des conditions de référence. (1) Ce travail met en évidence (i) le rôle prépondérant des facteurs environnementaux naturels dans la structuration des communautés aquatiques en comparaison des facteurs anthropiques (définis à l'échelle du bassin versant, du corridor riparien et du tronçon), (ii) les réponses contrastées des communautés aquatiques aux pressions humaines (dégradations hydro-morphologiques et de la qualité de l'eau) et (iii) plus généralement, les forts impacts des barrages et de l'altération de la qualité de l'eau sur les communautés aquatiques. (2) Une méthode Bayésienne a été développée pour estimer les incertitudes liées à la prédiction des conditions de référence d'un indice piscicole (IPR+). Les incertitudes prédictives de l'IPR+ dépendent du site considéré mais aucune tendance claire n'a été observée. Par comparaison, la variabilité temporelle de l'IPR+ est plus faible et semble augmenter avec l'intensité des perturbations anthropiques. Les résultats de ce travail confirment l'avantage d'indices multi-métriques basés sur des traits fonctionnels par rapport à ceux relatifs à la composition taxonomique. Les sensibilités différentes des macrophytes, poissons, diatomées et macro-invertébrés aux pressions humaines soulignent leur complémentarité pour l'évaluation des écosystèmes fluviaux. Néanmoins, de futures recherches sont nécessaires à une meilleure compréhension des effets d'interactions entre types de pressions et entre pressions humaines et environnement. / Sensitive biological measures of ecosystem quality are needed to assess, maintain or restore the ecological conditions of rivers. Since our understanding of these complex systems is imperfect, river management requires recognizing variability and uncertainty of bio-assessment for decision-making. Based on the analysis of national data sets (~ 1654 sites), the main goals of this work were (1) to test some of the assumptions that shape bio-indicators and (2) address the temporal variability and the uncertainty associated to prediction of reference conditions.(1) This thesis highlights (i) the predominant role of physiographic factors in shaping biological communities in comparison to human pressures (defined at catchment, riparian corridor and reach scales), (ii) the differences in the responses of biological indicators to the different types of human pressures (water quality, hydrological, morphological degradations) and (iii) more generally, the greatest biological impacts of water quality alterations and impoundments. (2) A Bayesian method was developed to estimate the uncertainty associated with reference condition predictions of a fish-based bio-indicator (IPR+). IPR+ predictive uncertainty was site-dependent but showed no clear trend related to the environmental gradient. By comparison, IPR+ temporal variability was lower and sensitive to an increase of human pressure intensity. This work confirmed the advantages of multi-metric indexes based on functional metrics in comparison to compositional metrics. The different sensitivities of macrophytes, fish, diatoms and macroinvertebrates to human pressures emphasize their complementarity in assessing river ecosystems. Nevertheless, future research is needed to better understand the effects of interactions between pressures and between pressures and the environment.

<p align="justify"><i>Typologie des cours d’eau en Wallonie et caractérisation par la faune invertébrée</i><br>Vingt-cinq types de cours d’eau ont été définis en Wallonie d’après les termes de la Directive Cadre pour l’Eau en tenant compte des facteurs obligatoires et optionnels rassemblés sous trois critères :la taille (du « ruisseau » à la « très grande rivière »), la pente (faible, moyenne et forte), et cinq régions naturelles (la région limoneuse, le Condroz, la Famenne, l’Ardenne et la Lorraine belge, résumant les facteurs obligatoires altitude, latitude, longitude et géologie). Une approche par analyses multivariées appliquées à un grand nombre d’échantillons (listes taxonomiques) a permis de définir de façon plus précise certains types de rivières et de distinguer sept groupes typologiques montrant des assemblages faunistiques similaires.</p><p><p align="justify"><i>Conditions de référence types et définition de l’état écologique des rivières en Wallonie à l’aide de métriques biocénotiques basées sur les invertébrés</i><br> Les listes faunistiques et les valeurs métriques de l’IBGN (Indice biologique global normalisé) issues du réseau d’évaluation de la qualité biologique en Wallonie ont été utilisées pour discriminer les types de rivières et pour définir les sites de référence, les conditions de référence et les limites des classes des états écologiques. Au sud du sillon Sambre et Meuse, impliquant quatre groupes typologiques de rivières, les valeurs de référence et la définition des états écologiques ont été basées et calculées sur un réseau de référence de sites de très bon état. Les « valeurs de conditions de référence » ont été définies par les médianes des métriques des sites de « très bon état ». Lorsque aucun site de très bon état n’était disponible, c’est-à-dire pour les groupes typologiques au nord du sillon Sambre et Meuse et pour la Meuse et la Sambre, les conditions de référence (ou le « potentiel écologique maximal ») et les limites de classes ont été basées sur des coefficients appliqués aux sites de « bon état » et sur jugement d’expert.</p><p><p align="justify"><i>Exercice pilote d’inter-étalonnage</i><br> Cinquante échantillons ont été sélectionnés parmi les rivières du type d’inter-étalonnage européen R-C3 (petite taille, altitude moyenne, substrat siliceux) en Wallonie (correspondant aux « ruisseaux ardennais ») dans toute la gamme de qualités écologiques, du « très bon » au « mauvais » état. Chaque métrique de l’indice « Intercalibration Common Metrics » (ICM) a été comparée (par régression linéaire et polynomiale) aux valeurs de l’IBGN. La plus forte corrélation a été établie avec l’indice synthétique de l’ICM dont le R² très élevé (0,95) permet un inter-étalonnage précis et fiable. A un EQR (Equivalent Quality Ratio) de l’IBGN = 1 correspond un indice ICM très proche (= 1,004). En conséquence, la métrique « cote de l’IBGN » est proposée comme métrique pour l’évaluation de l’état écologique de la faune invertébrée en Wallonie.</p><p><p align="justify"><i>Espèces exotiques et invasives</i><br>L’ouverture récente du canal à grand gabarit Main – Danube en 1992 et la navigation qui en résulte a permis à plusieurs espèces de macroinvertébrés ponto-caspiennes d’envahir successivement les bassins du Rhin et de la Meuse. De 1998 à 2000, le réseau de mesure a enregistré quatre nouvelles espèces exotiques dans la Meuse en Belgique :une polychète (<i>Hypania invalida</i>) et trois crustacés (<i>Hemimysis anomala, Dikerogammarus villosus, D. haemobaphes</i>). Peu avant, en 1995, le bivalve asiatique <i>Corbicula fluminea</i> et l’amphipode nord-américain <i>Crangonyx pseudogracilis</i> ont également été enregistrés pour la première fois. La dynamique des invasions a été étudiée et discutée.</p><p><p align="justify">L’<i>état biologique actuel</i> (2000-2002) des masses d’eaux de surface en Wallonie et l’évolution des états biologiques sur une décennie (1990-2002) figurent dans l’étude et sont discutés. Une amélioration globale de la qualité de 6 % est enregistrée pour cette période. L’amélioration de la qualité se manifeste principalement pour les états « mauvais » et « médiocre » s’élevant à l’état « moyen ».</p><p><p><b>Abstract</b><p><p><p align="justify"><i>River typology in Wallonia and invertebrate fauna characterization</i><br>Twenty-five river-types in Wallonia were defined according to the Water Framework Directive taking into account obligatory and optional factors gathered in three criteria: the size (from “brook” to “very large river”), the slope (gentle, medium and strong) and five natural regions (Loess, Condroz, Famenne, Arden and Jurassic summarising the obligatory altitude, latitude, longitude and geology factors). A multivariate approach applied to a large amount of samples (i.e. taxa lists) led to give a more accurate definition of some river-types and to discriminate seven river-type groups exhibiting similar faunal assemblages.</p><p><p align="justify"><i>Type-specific reference conditions and ecological status definition of rivers in Wallonia using invertebrate biocenotic metrics</i><br> Faunal lists and IBGN (i.e. "Standardized Global Biological Index IBGN") metric values, evolving from the biological quality assessment network in Wallonia, were used to discriminate the river types and to define the reference sites, the reference conditions and the status class limits. South of the axis made by the Sambre & Meuse Rivers, involving four river-type groups, reference values and ecological status definition were based and calculated on a reference network of sites of high status. The "reference condition values” were defined as the median values of the metrics in all “high status” sites. Where no site of high status was available, i.e. in the others river-type groups north of the same axis and in the Rivers Sambre and Meuse themselves, reference conditions (or maximum ecological potential) and class limits were based on coefficients applied to “good status” sites and on expert judgement.</p><p><p align="justify"><i>Intercalibration pilot exercise</i><br> Fifty samples were selected from R-C3 rivers (i.e. small, mid-altitude, siliceous) in Wallonia (corresponding to the “Arden’s brooks”) showing the widest range of ecological quality from high to bad status. Each Intercalibration Common Metric (ICM) was compared (linear and polynomial regression) to IBGN scores. The highest correlation was found with the synthetic ICM index, whose high R² (0.95) allows accurate and reliable intercalibration. To IBGN EQR (i.e. Equivalent Quality Ratio) = 1 corresponds a very close ICM index value (= 1.004). Consequently, the metric IBGN score is being proposed to act as the metric for the assessment of the invertebrate fauna ecological status in Wallonia, Belgium.</p><p><p align="justify"><i>Exotic and invasive species</i><br> The recent opening of the canal Danube – Main in 1992 and the subsequent navigation allowed several Ponto-Caspian macroinvertebrate species to invade successively the Rhine and the River Meuse basins. From 1998 to 2000, the monitoring network recorded four new alien species in the River Meuse in Belgium: one Polychaeta (<i>Hypania invalida</i>) and three Crustacea (<i>Hemimysis anomala, Dikerogammarus villosus, D. haemobaphes</i>). Earlier, in 1995, the Asian Bivalvia <i>Corbicula fluminea</i> and the North American Amphipod <i>Crangonyx pseudogracilis</i> were also recorded for the first time. The invasions’ dynamics were studied and discussed.</p><p><p align="justify"><i>Present biological status</i> (2000-2002) of surface water-bodies in Wallonia and biological status evolution over a one-decade period (1990-2002) is included and discussed in the study. A global quality improvement of 6 % is recorded for the period. Quality improvement concerns mainly the “bad” and “poor” status raising up to “moderate” status.</p><p><p> / Doctorat en sciences, Spécialisation biologie animale / info:eu-repo/semantics/nonPublished