Biological invasions are one of the main factors responsible for the imperiled status of freshwater ecosystems, but much remains to be learned about their indirect effects on native communities. The first part of this dissertation examines community effects of long-term efforts to selectively control invasive Eurasian watermilfoil. Results of the first study show that native plants immediately recolonized treated areas and habitat complexity was unaffected. Fish community was not influenced by invasive plant control. Macroinvertebrate communities were highly variable and part of their variability could be explained by plant community attributes. Both fish and macroinvertebrates used invasive watermilfoil, which emphasizes the need for timely restoration of native macrophytes to mitigate for lost habitat. Because fish and macroinvertebrates were more affected by complexity than other attributes of plant assemblage, reestablishment of habitat complexity appears to be a promising restoration strategy. The second study, which examined species interactions after watermilfoil control, found that fish feeding activity was not correlated with invasive plants or habitat complexity and that invasive macrophyte control did not affect characteristics of fish feeding investigated. The relationship between fish and macrophytes was further explored in the context of interactions between an invasive piscivore and its native prey. First, I examined the prey naiveté hypothesis with non-native peacock bass in Paraná River, Brazil. Prey responded to visual and chemical cues of peacock bass and displayed avoidance behaviors similar to those observed with a native predator, meaning that lack of recognition was not responsible for the observed vulnerability of native species to this introduced predator. After confirming lack of naiveté, I assessed direct and indirect effects of this non-native predator on native prey. Peacock bass had no indirect effects on its prey feeding activity. Macrophyte type did not affect indirect predator-prey interactions, whereas direct predator effects slightly decreased in the presence of aquatic vegetation. I discuss implications of these findings for native biodiversity and convene other potential explanations for the observed effects of peacock bass. Both projects contribute to our understanding of the relationship between aquatic plants and their animal communities and effects of invasive species in freshwater habitats.

Efter att EU införde ett ramverk år 2000 rörande regionens vattenanvändning, vattendirektivet, beslöt Sveriges regering att från och med sommaren 2020 ompröva rikets vattendammar. I de fall rådande vattenanvändning inte uppfyller de krav som anges i ramverket kan dammutrivning bli aktuellt. Syftet med studien är undersöka och utveckla en metod att utvärdera förändringar av strömhabitat uppströms ett vattendrag efter en dammutrivning. Studieområdet utgörs och begränsas av datamängden i form av flygfoton insamlade med UAV vid två tillfällen över samma område. Även batymetriska data över vattendragets botten från en bottenskanning har använts således även Lantmäteriets nationella höjdmodell. Två fotogrammetriprogram användes i arbetet, dels för att skapa en ortomosaik från flygfoton men även för att utföra en bildnormalisering. GIS programvaran ArcGIS Pro tillhandahåller flera algoritmer för klassificering av raster. Algoritmerna SVM och RT, viktades mot varandra och SVM användes vidare i metoden. Med olika generaliserings-verktyg kunde strömhabitat identifieras och förstärkas. Även olika terrängmodeller skapades från flygfoton och Lantmäteriets nationella höjdmodell. Dessa granskades mot varandra utifrån olika aspekter som variationer i bland annat detaljrikedom, generaliseringsgrad och återspeglandet av vattenytan.  Slutsatsen av studien är att klassificering av strömhabitat kan göras i ett GIS-program med en lägesosäkerhet på mellan 25 och 40 %, beroende på vilka strömhabitat som ska klassificeras. Efter utrivningen uppstod 17 zoner med förändrade strömhabitat vilket var två mer än vad prognoser förutsatt. Vidare påverkades vattenvolymen markant då en minskning på ca 40 % skedde från 2018 till 2020. En areal av ca 1,5 hektar berördes då gammal älvbotten blev torrlagd i samband med dammutrivningen. Ett samband syntes mellan avståndet från kraftverket och torrlagd botten då dessa ytor sågs minska i storlek i takt med att avståndet ökade. Att undersöka vart vattennivån påverkats som mest var inte möjligt i brist på data. Studien har utvecklat en metod att analysera en dammutrivnings påverkan på ett vattendrag med data från UAV och bottenskanning.

Le modèle input-output régional environnementalisé développé dans la thèse de M. Cordier suggère qu’il serait possible de restaurer 25% des surfaces naturelles de nourriceries de poissons détruites dans l’estuaire de la Seine entre 1834 et 2004. Le modèle suggère que la mesure de restauration pourrait augmenter de 15% à 23% la biomasse de soles produite dans l’estuaire par rapport à une situation sans mesure. Quant à l’effet des coûts de restauration sur les agrégats macroéconomiques (PIB, emploi, etc.), il génère une diminution qui ne dépasse pas 0,5% par rapport à une situation sans mesure. Le modèle montre cependant que trois secteurs sont particulièrement touchés par la mesure, leur bénéfice étant considérablement réduit. Cela indique le compromis à réaliser entre les objectifs écologiques à long terme et les objectifs économiques sectoriels à court terme. La quantification des compromis par le modèle constitue un atout utile aux processus de décision participatifs multicritère / The regional green input-output model developed in Mateo Cordier's PhD shows that it seems possible to restore 25% of the natural areas of fish nurseries destroyed in the Seine estuary between 1834 and 2004. The model suggests that the restoration measure could increase between 15% and 23% the biomass of sole generated by the estuary compared to a situation without measure. Regarding the impact of restoration costs on macro-economic indicators (GDP, employment, etc.), it generates a decrease that does not exceed 0,5% compared to a situation without measure. However, the model shows that three sectors are particularly impacted by the measure. Their benefits are considerably reduced. This shows the trade-off that occurs between ecological targets on the long run and economic targets on the short run. The quantification of such trade-offs in the model is particularly useful to public participation in decision-making. / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished

BC Hydro’s Water Use Planning (WUP) process is one of the world’s most comprehensive hydroelectric dam operational reviews and has served as a model to revise hydropower operating plans with the participation of an inclusive range of stakeholders, rights holders, and the use of up-to-date scientific information, that meets social and environmental goals alongside economic targets. In 2000, BC Hydro initiated a WUP process in the Jordan River watershed. This watershed hosts a wide diversity of water users, including active resource industry stakeholders (mining, forestry, and hydropower), Indigenous rights holders, and rural community citizens; which is representative of watersheds in British Columbia with established WUPs. BC Hydro finalized the Jordan River WUP in 2003, which focuses on establishing critical freshwater flows for fish habitat and achieving specific recreational values of the local community. However, numerous other issues still remain that were beyond the scope of the WUP process, including water quality concerns that were continually brought up by citizens during the consultative process of the WUP. In addition to these concerns, biological monitoring following the implementation of the WUP suggests that contamination from an inactive copper mine has affected and altered sensitive water quality parameters for a healthy Pacific salmon habitat in Jordan River. Yet, there has not been an extensive water quality study conducted that examines the spatial or seasonal water quality extents of the mining contamination in Jordan River, specifically copper. Consequently, fourteen years after the creation of the WUP, local advocates are still struggling to have their concerns heard by the entity responsible for freshwater flow, BC Hydro, alongside federal and provincial government agencies. Advocates are calling for the creation of a watershed-based group as a mechanism for having greater influence in water planning and governance processes. This study explores the research question: if and how has the WUP process contributed to creating watershed governance capacity? This social science thesis project employs a mixed-methods approach using both quantitative and qualitative data. The study includes a document review of relevant water governance literature and focuses on examining the freshwater quality of the Jordan River. Water quality samples were collected over a five-week period from five sites on the Jordan River beginning in September and concluding in October of 2015 during the most sensitive periods of salmon spawning activity in the lower reaches of the Jordan River. Spatial and seasonal water quality trends were identified, and analysis concluded that copper is the primary contaminate affecting the productivity of a healthy salmon habitat in the Jordan River. Acid mine drainage (AMD) processes were identified throughout the water quality data and are strongly influenced by the proximity of existing mine waste piles sourced from an abandoned copper mine, and unnatural anthropogenic flows from the three BC Hydro dams present in the Jordan River system. The final stage of the research project focuses on assessing the adaptive capacity in the watershed to address the issues of concern outlined in the WUP. There is a current movement to create watershed organizations that are formally supported through new legislation in British Columbia, but questions remain about the capacities of these watershed communities to sustain such a formal institution and if these watershed communities are ready to successfully implement a local watershed governance model. The Gupta et al. (2010) six adaptive capacity dimensions provide a logical framework to explore if these capacities are present such that it could be expected that local watershed organizations would be effective as society adapts to more watershed-based governance approaches. Thirteen semi-structured interviews were conducted from October 2016 to February 2017. Interviews and observational data focused on the WUP process and prospective and current members of the Jordan Watershed Round Table (JWRT). The research evaluated whether these six adaptive capacity dimensions are present in watershed communities that have been subjected to water management processes, specifically the WUP program. Overall, the research concluded that the WUP has contributed to some adaptive capacity for watershed governance in the Jordan River, specifically on building the adaptive capacity dimensions: variety, learning capacity, room for autonomous change, leadership, and resources within the JWRT. / Graduate