Este trabalho foi desenvolvido nos reservatórios, em cascata, que fazem parte do Médio e Baixo Rio Tietê, incluindo os tributários, os Rios Tietê, Piracicaba e Bauru. Foram considerados os pontos de coleta, localizados à montante, jusante, bem como os pontos intermediários dos reservatórios estudados. Considerando-se os períodos referentes a outubro de 1999 fevereiro, maio e julho de 2000, as pesquisas nestes locais abordaram a qualidade ambiental dos reservatórios, com características limnológicas (água, sedimento), a fauna de macroinvertebrados bentônicos, além de testes ecotoxicológicos (Chironomus xanthus). As análises dos sedimentos permitiram evidenciar as frações de silte e argila, o elevado teor de matéria orgânica nos reservatórios situados no início da cascata, além do nitrogênio e fósforo e metais potencialmente biodisponíveis. Elevadas concentrações de nutrientes nitrogenados e fosfatados, material em suspensão (orgânico e inorgânico) e clorofila-a, foram observadas nas amostras de água, o que permitiu classificar os reservatórios como eutróficos, mesotróficos e oligotróficos, de acordo com sua posição no sistema bem como do período amostrado. As concentrações de alguns dos metais encontrados na água estiveram acima do permitido pela Resolução CONAMA (20/96), considerando-se os períodos em estudo. Quanto às relações bióticas, foram obtidas através do índice de Diversidade (H\'), da equitabilidade, a qual foi evidenciada pela distribuição agregadados organismos e a presença de indivíduos pertencentes à mesma espécie, evidenciou a baixa riqueza de taxa. Através do IET/Densidade de Oligochaeta constatou-se para os reservatórios em cascata e os principais tributários características de eutrofizados. A fauna bentônica dos rios Tietê, Piracicaba e Bauru e dos reservatórios dos locais de estudo caracterizou-se pela presença de Tubificidae (Oligochaeta) além de Chironomidae (Díptera), e do grupo Mollusca. Entre os Tubificidae, a espécie Limnodrilus hoffmeisteri, Branchiura sowerbyi e Limnodrilus udekemianus ocorreram em considerável dominância numérica no período de estudo. A Família Chironomidae, foi representada pelos gêneros Goeldichiromus e Coelotanypus e o grupo Mollusca pelo gênero, Haylacostoma e espécie Melanoides tuberculatus (Thiaridae), Corbicula fluminea (Corbiculidae), o gênero Biomphalaria (Planorbidae) e o gênero Lymnaea collumela, (Lymnaiidae). Quanto à Família Naididade foi representada pelas espécies (Prístina americana, Dero nívea, Dero digitata e Allonais chelata), pela família Alluroididae (Brinkhurstia americanus) e pela Família Opistocystidae (Opistocysta funiculus). Os testes de toxicidade com Chironomus xanthus confirmaram os resultados obtidos através das análises físicas e químicas, conferindo características de impactados aos reservatórios situados no início da cascata (Barra Bonita, Bariri e Ibitinga) e aos tributários (Tietê, Piracicaba e Bauru) moderadamente poluídos aos reservatórios intermediários (reservatório de Nova Avanhandava e Promissão) e, com ausência de poluição, o Reservatório de Três Irmãos, situado no final da cascata. Os resultados decorrem dos usos e ocupação do solo, atividades antropogênicas na Bacia Hidrográfica, do aporte de materiais para o sistema na qual se inserem os rios e os reservatórios estudados. / This work was developed in the reservoirs, at waterfalls, which are part of the Medium and Low Tiete River, including its tributaries, the Tiete, the Piracicaba river and the Bauru river. The collecting sites considered were upstream, downstream and those intermediary sites of the reservoirs. Taking into account the different periods of October 1999 and February, May and July of 2000, the researches in those sites were about the environmental quality of the reservoirs with limnologic characteristics (water, sediment), the bentonic macroinvertebrate fauna besides ecotoxilogic tests (Chironomus xanthus). The sediment analysis allowed to evidence the silt and clay fractions, the high organic matter content in the reservoirs located at the waterfall head in addition to nitrogen, phosphur and potentially bio-available metals. High nitrogened and phosphated nutrients, suspended matter (organic and inorganic) and chlorophyl-a were observed in the water samples, which allowed to classify the reservoirs as euthrophic, mesotrophic and oligotrophic according to their location in the system and the sampling period. The concentration of some metals found the water was above the level permitted by CONAMA Resolution (20/96) taking into account the periods of study. As to the biotic relations, they were obtained by means of the Diversity index (H\') of the equitability, which was evidenced by the aggregated distribution of the organisms and the presence of individuals belongingto the same species evidenced the low taxa richness. Through the IET/Oligochaeta abundance, the reservoirs and the tributaries were found to be eutrophitized. The Tiete, Piracicaba and Bauru rivers and the reservoirs studied sites bentonic fauna was characterized by the presence of Tubificidae (Oligochaeta) besides Chironomidae (Diptera) and the Mollusca group. Among the Tubificidae, the Limnodrilus hoffmeisteri, Branchiura sowerbyi e Limnodrilus udekemianus species occurred in considerable numerical dominance in the period of study. The Chironomidae family was represented by the genus Goeldichiromus and Coelotanypus and the Mollusca group by the genus Haylacostoma and Melamoides tuberculatus (Thiaridae) species, Corbicula fluminea (Corbiculidae), the genus Bionphalaria (Planorbidae) and the genus Lymnaea collumela (Lymnaiidae). The Naididae family was represented by the species (Pristina americana, Dero nivea, Dero digitata and Allonais chelata), by the family Alluroididae (Brinkhurstia americanus) and the family Opistocystidae (Opistocysta funiculus).The toxicity tests with Chironomus xanthus confirmed the results obtained through physical and chemical analyses granting characteristics of impacted to the reservoirs located at the waterfall head (Barra Bonita, Bariri and Ibitinga) and the tributaries (Tiete, Piracicaba and Bauru) moderately polluted to the intermediate reservoirs (Nova Avanhandava and Promissão reservoirs) and, absenceof pollution, the Tres Irmãos Reservoir located at the end of the waterfall. The results arise from the uses and occupation of the soli, anthropogenic activities in the hydrographic basis, disclosure of materials into the system in which are the rivers the reservoirs under study are located.

Em contraposição ao avanço do desmatamento da floresta amazônica em São Félix do Xingu - PA, principalmente pela atividade pecuária, diversas inciativas vêm estimulando a recuperação de áreas degradadas (RAD) por meio da implantação de sistemas agroflorestais com cacau (Theobroma cacao L.) (SAF-cacau). A fim de estudar o potencial SAF-cacau como ferramenta de RAD nesta região, conduzi a pesquisa em quatro hipóteses principais: (1) recupera parcialmente a estrutura florestal; (2) recupera parcialmente a riqueza/diversidade de plantas; (3) recupera a fertilidade do solo; (4) recupera a riqueza/diversidade de grupos de macroinvertebrados do solo. Para tanto, agrupei os SAF\'s em três categorias de sombreamento: sombra inicial (SI), sombra secundária (SS) e sombra abandonada (A), analisando-as comparativamente com Floresta e Pasto. Em paralelo, realizei entrevista socioeconômica e ambiental, pautada na percepção dos produtores rurais, a fim de contextualizar as ações humanas com os usos do solo em estudo. Os principais resultados mostram que os solos são semelhantes em termos de textura e fertilidade, independentemente da situação de uso. Os SAF-cacau são potenciais ferramentas de RAD em termos de estrutura florestal e diversidade florística, necessitando maiores estudos com relação à composição de plantas. A rentabilidade do SAF-cacau mostrou-se expressivamente superior à pecuária, por unidade de área, ocupando menor espaço territorial na propriedade, além de outros benefícios socioambientais, com destaque para provisão de serviços ambientais. / In contrast to the advance of the Amazon rainforest deforestation, mainly by cattle activity, in Sao Felix do Xingu - PA municipality, several initiatives have been stimulating the reclamation of degraded lands (RDL) through the implementation of agroforestry systems with cacao (Theobroma cacao L.) (cacao-AFS). Aiming to study the cacao-AFS as a potential tool to reclaim degraded lands in this region, I based the research in four main hypothesis: (1) it partially reclaims the forestry structure; (2) it partially reclaims the richness/diversity of plants; (3) it reclaims the soil fertility; (4) it reclaims the richness/diversity of soil macroinvertebrates. Thus, I grouped the AFS in three categories: initial shade (IS); secondary shade (SS); abandoned shade (A), comparing them with Forest and Pasture land uses. In parallel, I performed a socioeconomic and environmental interview, based on farmers perception, in order to contextualize the human actions in the studied the land uses. The main results showed similarity in soil\'s texture and fertility, regardless of use situation. The cocoa- AFS are potential tools of RAD in terms of forest structure and floristic diversity, requiring further studies regarding the composition of plants. The profitability of the cacao-AFS was found to be significantly higher than the cattle, per unit area, occupying less territorial space on the property, plus other social and environmental benefits, especially the provision of many environmental services.

Le Rhin a subi d’importantes modifications qui ont altéré la biodiversité de l’ensemble de la plaine alluviale. Des actions de restauration ont été initiées pour lui redonner une part de son fonctionnement hydromorphologique naturel. Le travail de thèse a consisté à évaluer les effets de ces restaurations et à mettre en évidence les processus mis en jeu dans les changements de la biocénose des milieux restaurés. Les résultats ont démontré que les communautés biologiques sont non seulement gouvernées par les modifications physiques post-restauration mais aussi par l’influence discrète de déterminants externes à la restauration tels que les invasions biologiques ou la dynamique interne du fleuve. L’aspect transitoire des bénéfices obtenus a été souligné comme la principale limite de l’injection sédimentaire alors que les épis transversaux artificiels mis en place dans le cadre d’un essai d’érosion maitrisée se sont révélés être les facteurs de durabilité des effets écologiques. / The Rhine River has undergone major engineering works that led to severe alterations which helped to alter the biodiversity of the entire floodplain. Restoration actions have been initiated to give it back a part of its natural hydro morphological functioning. The thesis consisted in evaluating the effects of these restorations and in highlighting the mechanisms and processes involved in biocoenosis changes of the restored environments. The results also showed that the post-restoration biological community is not only defined by post-restoration physical changes but also by the discrete influence of external determinants of restoration such as biological invasions or the internal dynamics of the river. The transitional aspect of the benefits incurred has been identified as the main limit of the gravel augmentation, while the implementation of transverse artificial groynes in the controlled bank erosion has proved to be factors of sustainability of the ecological effects.

Em contraposição ao avanço do desmatamento da floresta amazônica em São Félix do Xingu - PA, principalmente pela atividade pecuária, diversas inciativas vêm estimulando a recuperação de áreas degradadas (RAD) por meio da implantação de sistemas agroflorestais com cacau (Theobroma cacao L.) (SAF-cacau). A fim de estudar o potencial SAF-cacau como ferramenta de RAD nesta região, conduzi a pesquisa em quatro hipóteses principais: (1) recupera parcialmente a estrutura florestal; (2) recupera parcialmente a riqueza/diversidade de plantas; (3) recupera a fertilidade do solo; (4) recupera a riqueza/diversidade de grupos de macroinvertebrados do solo. Para tanto, agrupei os SAF\'s em três categorias de sombreamento: sombra inicial (SI), sombra secundária (SS) e sombra abandonada (A), analisando-as comparativamente com Floresta e Pasto. Em paralelo, realizei entrevista socioeconômica e ambiental, pautada na percepção dos produtores rurais, a fim de contextualizar as ações humanas com os usos do solo em estudo. Os principais resultados mostram que os solos são semelhantes em termos de textura e fertilidade, independentemente da situação de uso. Os SAF-cacau são potenciais ferramentas de RAD em termos de estrutura florestal e diversidade florística, necessitando maiores estudos com relação à composição de plantas. A rentabilidade do SAF-cacau mostrou-se expressivamente superior à pecuária, por unidade de área, ocupando menor espaço territorial na propriedade, além de outros benefícios socioambientais, com destaque para provisão de serviços ambientais. / In contrast to the advance of the Amazon rainforest deforestation, mainly by cattle activity, in Sao Felix do Xingu - PA municipality, several initiatives have been stimulating the reclamation of degraded lands (RDL) through the implementation of agroforestry systems with cacao (Theobroma cacao L.) (cacao-AFS). Aiming to study the cacao-AFS as a potential tool to reclaim degraded lands in this region, I based the research in four main hypothesis: (1) it partially reclaims the forestry structure; (2) it partially reclaims the richness/diversity of plants; (3) it reclaims the soil fertility; (4) it reclaims the richness/diversity of soil macroinvertebrates. Thus, I grouped the AFS in three categories: initial shade (IS); secondary shade (SS); abandoned shade (A), comparing them with Forest and Pasture land uses. In parallel, I performed a socioeconomic and environmental interview, based on farmers perception, in order to contextualize the human actions in the studied the land uses. The main results showed similarity in soil\'s texture and fertility, regardless of use situation. The cocoa- AFS are potential tools of RAD in terms of forest structure and floristic diversity, requiring further studies regarding the composition of plants. The profitability of the cacao-AFS was found to be significantly higher than the cattle, per unit area, occupying less territorial space on the property, plus other social and environmental benefits, especially the provision of many environmental services.

El presente estudio tiene como objetivo proporcionar una base de conocimiento sólida para la restauración ecológica de ríos, basada en la respuesta de comunidades acuáticas a cambios en la conectividad hídrica, factores medioambientales y presión antrópica. La conectividad hídrica lateral resultó ser el factor principal que estructura hábitats y comunidades acuáticas en el Ebro; mientras que la turbidez, salinidad y concentración de nutrientes fueron factores secundarios. La combinación de estos factores establece un marco ecológico que permite realizar predicciones acerca de los patrones taxonómicos y funcionales con más probabilidades de ocurrir en la llanura del Ebro. La posibilidad de que se creen nuevos humedales de forma natural en el Ebro es muy baja, mientras los que quedan están amenazados por una baja renovación del agua. El objetivo de la restauración ecológica debe por tanto consistir en re-establecer un amplio rango de condiciones hídricas, de acuerdo con el potencial sostenible del ecosistema. / The present study aims to provide a solid background for river-floodplain restoration based in the response of aquatic communities, to changes in hydrological connectivity, environmental factors and human pressure across the floodplain of a Mediterranean river.The lateral hydrological connectivity was found to be the key factor structuring the habitats and aquatic communities of the Middle Ebro floodplain, while turbidity, salinity and nutrient status were secondary drivers. These factors created a template for the aquatic community development that enabled predictions about the taxonomic and functional patterns in those aquatic communities more likely to occur under particular conditions. In the Middle Ebro River, there are very few possibilities of new wetlands creation, while the diversity and functionality of the remaining ones are threatened by the limited hydrological connectivity. The objective of floodplains restoration should thus consist in re-establishing a wide range of wetland types in accordance with the river-floodplain potential of sustainability.

Vam monitoritzar paràmetres físics i químics, macroinvertebrats bentònics, clorofil·la a, productors primaris i matèria orgànica durant un any (2001-2002) per examinar els efectes d'una font puntual sobre la composició taxonòmica, la estructura de la comunitat, l'organització funcional, la utilització de l'habitat i la estoquiometria al riu la Tordera (Catalunya).Aigües avall de la font puntual, concentració de nutrients, cabal i conductivitat eren majors que al tram d'aigües amunt, mentre que oxigen dissolt era menor. La densitat de macroinvertebrats era més elevada al tram d'aigües avall però la biomassa era similar als dos trams. La riquesa taxonòmica al tram de dalt era un 20% més alt que al tram de baix. Els anàlisis d'ordenació separen clarament els dos trams en el primer eix, mentre que els dos trams presentaven una pauta temporal similar en el segon eix. La similaritat entre els dos trams en composició taxonòmica, densitats i biomasses després de les crescudes d'abril i maig de 2002, indiquen que les pertorbacions del cabal poden actuar com a un mecanisme de reinici de la comunitat bentònica i jugar un paper important per a la restauració d'ecosistemes fluvials.Els dos trams presentaven una biomassa de perifiton, plantes vasculars, CPOM i FPOM similars, mentre que clorofil·la a, algues filamentoses, molses i SPOM eren majors al tram d'aigües avall. La densitat relativa de trituradors era menor sota la font puntual mentre que col·lectors i filtradors van ser afavorits. La biomassa relativa de trituradors també era menor sota la font puntual, però la biomassa de col·lectors i depredadors va augmentar. Les relacions entre densitat de grups tròfics i els seus recursos eren rarament significatives. La relació s'explicava millor amb la biomassa de macroinvertebrats. Els dos trams compartien la mateixa relació per raspadors, col·lectors i filtradors però no per trituradors i depredadors.La densitat i la biomassa de macroinvertebrats es trobaven positivament correlacionades amb la quantitat de recursos tròfics i la complexitat d'habitat, mentre que la riquesa taxonòmica es trobava negativament relacionada amb paràmetres hidràulics. La influència dels substrats inorgànics prenia menor rellevància per a la distribució dels macroinvertebrats. Els anàlisis d'ordenació mostren com les variables del microhabitat de major rellevància eren CPOM, clorofil·la a, algues filamentoses i velocitat. La cobertura de sorra només era significativa per al tram d'aigües amunt i les molses, al d'aigües avall. El número de correlacions significatives entre macroinvertebrats i les variables del microhabitat era més elevat per al tram de dalt que per al de baix, bàsicament per diferències en composició taxonòmica. La biomassa de macroinvertebrats va aportar una informació semblant a la obtinguda per la densitat.Perifiton i molses tenien uns continguts de nutrients similars en els dos trams. Els %C i %N d'algues filamentoses també eren similars en els dos trams però el %P sota la font puntual era el doble que al tram de dalt. Les relacions estoquiomètriques en CPOM, FPOM i SPOM eren considerablement menors sota la font puntual. Els continguts elementals i relacions van ser molt variables entre taxons de macroinvertebrats però no van resultar significativament diferents entre els dos trams. Dípters, tricòpters i efemeròpters presentaven una estoquiometria similar, mentre que el C i el N eren inferiors en moluscs i el P en coleòpters. Els depredadors presentaven un contingut en C i N més elevat que la resta de grups tròfics, mentre que el P era major en els filtradors. Els desequilibris elementals entre consumidors i recursos eren menors en el tram d'aigües avall. A la tardor i l'hivern la major font de nutrients va ser la BOM mentre que a la primavera i a l'estiu va ser el perifiton. / We monitored physical and chemical parameters, benthic macroinvertebrates, chlorophyll a, primary producers, and organic matter for one year (2001-2002) to assess the effect of a point source input on the taxa composition, community structure, functional organization, microhabitat distribution, and elemental stoichiometry in La Tordera stream (Catalonia, NE Spain).Below the point source, nutrient concentrations, discharge, and specific conductance were higher than at the upstream reach, while dissolved oxygen decreased. Total macroinvertebrate density was higher at the downstream reach than at the upstream reach. The two reaches did not differ in macroinvertebrate total biomass. On average, taxa richness at the upstream reach was 20% higher than at the downstream reach. Ordination analysis clearly separated the samples of the two reaches in the first axis and corroborated the effect of the point source on the benthic community. The two reaches followed a similar temporal pattern with respect to the distribution of taxa along the second axis. Higher similarities between the two reaches in taxa composition, densities and biomass after the spates of April and May 2002, suggest that flooding events may act as a reset mechanism for benthic communities and play an important role in stream restoration.The two reaches did not differ in standing stocks of periphyton, vascular plants, CPOM and FPOM. Chlorophyll a, filamentous algae, mosses, and SPOM concentrations were increased by the point source. Relative density of shredders was reduced at the downstream reach, whereas gatherers and filterers were enhanced. Relative biomass of shredders decreased below the point source as well, but gatherers diminished and predators increased. The relationships between density of functional feeding groups and their presumed food resources were rarely significant. The relation between consumers and their food resources was best explained through macroinvertebrate biomass. The two reaches had the same relationship for scrapers, gatherers, and filterers, but differed for shredders and predators.Macroinvertebrate density and biomass were positively correlated with food resources and complexity of habitat architecture while taxa richness was negatively correlated with hydraulic parameters. Inorganic substrate exerted a lesser influence on macroinvertebrate distribution. Ordination analysis revealed that the microhabitat variables of major relevance at the two reaches were CPOM, chlorophyll a, filamentous algae, and maximum water velocity. Sand coverage was only retained at the upstream reach and moss, at the downstream reach. The number of significant correlations between macroinvertebrates and microhabitat variables was higher at the upstream reach than at the downstream reach mainly because of higher taxa richness. Macroinvertebrate biomass provided similar information to that obtained from density in our study case.Periphyton and mosses had similar nutrient contents in the two reaches. The %C and %N filamentous algae was also similar in the two reaches, but %P below the point source was two times higher than that at the upstream reach. Stoichiometric ratios for CPOM, FPOM, and SPOM decreased considerably below the point source. Elemental contents and ratios were highly variable among macroinvertebrate taxa but did not differ significantly between the two reaches, indicating homeostatic regulation. Dipterans, caddisflies, and mayflies had similar elemental contents and stoichiometry, whereas C and N were lower in mollusks and P in beetles. Predators had the higher C and N contents, while %P was higher in filterers and lower in scrapers. Elemental imbalances between consumers and resources were amended at the downstream reach relative to the upstream reach. Macroinvertebrates represented, on average, relatively low nutrient storage in the ecosystem. At the upstream reach, autochthonous production represented the major input of nutrients into the ecosystem food web, whereas the major source of P for heterotrophic production at the downstream reach was represented by allochthonous inputs.

Predation is one of many factors that form the structure of the macroinvertebrate community in lakes, wetlands and watercourses. Earlier studies lack an examination concerning how fish- and waterfowl predation affect macroinvertebrates during shorter periods in the spring. I performed an exclosure study in the shallow eutrophic Lake Tåkern which is located in the western part of Östergötland County, Sweden. The experiment was performed during a three week period (1-21 April 2012) when the water temperature was low and the density of migrating diving ducks was high. The experimental cages used included three out of four different treatments; general predation (open cages), bird exclusion (net with mesh size 90*45mm) and no predation (net with mesh size 1*1mm). In the fourth treatment, which was used to control for cage effects, samples were collected outside the cages. The cages where placed in blocks three and three, one for each the three treatments, on eight different locations in the experiment area. No significant difference was detected between the different treatments concerning diversity (Shannon diversity index: F3,25=1,39; P=0,27 and Simpson diversity index: F3,25=1,47; P=0,25), taxonomic richness (F3,25=1,74; P=0,19) nor density (F2,25=0.41; P=0,75) of the macroinvertebrate fauna. The lack of effect from predation of fish is most likely explained by the low water temperature during the experiment period. The lack of effect from waterfowl predation is most likely due to a low density of diving ducks, despite the season. / Predation är en av flera faktorer som styr makroevertebratfaunans sammansättning i sjöar, våtmarker och vattendrag. Jag genomförde ett utestängningsexperiment i den grunda näringsrika sjön Tåkern i västra Östergötland. Experimentet genomfördes under en treveckorsperiod (1april-21-april) på året då densiteten flyttande dykänder är hög och vattentemperaturen är låg, vilket saknas från tidigare studier. Experimentet innefattade fyra behandlingar; kontrollpunkter utan burar, generell predation (öppna burar), fågelexkludering (nät 45*90mm) samt ingen predation (stängda burar, nät, 1,1mm). Burarna bestod av plastlådor med en volym på 130 liter (Längd*höjd*bredd: 79cm*57cm*42cm). Burarna placerades i block om tre, en för varje behandling, på botten av sjön vid åtta olika provpunkter. Resultatet visade ingen signifikant skillnad mellan de olika behandlingarna gällande makroevertebratfaunans sammansättning, varken i fråga om diversitet (Shannons diversitetsindex: F3,25=1,39; P=0,27 och Simpsons diversitetsindex: F3,25=1,47; P=0,25 ANOVA) eller densitet (F2,25=0.41; P=0,75). Avsaknaden av effekt från fiskpredation förklaras troligen av låg vattentemperatur under experimentperioden vilken påverkar fiskarnas födosökshastighet negativt. Som förväntat såg vi ingen effekt av fågelpredation vilket troligen beror på att densiteten dykänder inte var tillräckligt hög.

Rivers and their catchments are under mounting pressure from direct channel modification, intensification of land use, and from a legacy of decades of channelisation. Recent legislation, in the form of the EU Water Framework Directive, places a greater emphasis on the management of water bodies as holistic systems, and includes the explicit consideration of hydromorphological quality, which describes the hydrologic and geomorphic elements of river habitats. These are defined specifically as hydrological regime, river continuity and river morphology. This appreciates that sediment and flow regimes, along with the channel structure, provides the 'template' on which stream ecological structure and function is built. Invertebrate fauna contribute significantly to the biodiversity of rivers, and often form the basis of monitoring river health. However much of the fundamental ecological knowledge base on the response of invertebrates to hydromorphological change needed to make informed decisions and accurate predictions, is either lacking, inadequate or contradictory. This thesis addresses some of the key potential shortcomings in recent bio-assessment that others have alluded to, but which have rarely been explored in the context of direct channel manipulations. By using two case studies of, realignment in a natural upland catchment, and flood protection engineering in an urban stream, this study investigates the sensitivity of hydromorphological impact assessment methods that rely on biodiversity patterns of benthic riverfly (Ephemeroptera, Plecoptera and Trichoptera) larva. This work employed widely used biomonitoring indices of benthic riverfly larva abundance, species richness, alpha and beta diversity, and community composition, applied over a range of spatial scales, in combination with spatially contemporaneous physical habitat data, to describe and explain community changes in response to disturbance, and patterns of natural variation. The effects of restoration were investigated using a high degree of sample replication within channels and across the wider catchment, as well as contrasting spring and autumn seasons. To assess change in a small urban channel, approaches that explicitly consider spatial elements of community data, using spatial eigenvectors analysis, were applied to spatially detrend community data and directly investigate spatial patterns. Restoration of the Rottal Burn was found to be successful in restoring habitat diversity and geomorphic processes, and in turn increasing reach scale species richness and beta diversity through the gradual arrival of rare and specialist taxa into novel habitats. Catchment scale replication revealed high variation in diversity indices of modified and undisturbed streams, and a strong temporal pattern related to antecedent flow conditions. Channels with greater habitat heterogeneity were able to maintain high gamma diversity during times of high flow stress by providing a number of low flow refuges along their length. The urban Brox Burn had surprisingly high riverfly richness and diversity driven by small scale hydraulic heterogeneity, created by bed roughness resulting in a range of microhabitats. Riverfly community responses to direct channel dredging could not be detected by measurements of average richness and diversity, however distinct changes were seen in gamma diversity, the identity of community members and their arrangement among sample patches. Impacts of sediment pollution release due to engineering were short lived and apparently had little detrimental impact on biodiversity. Strong spatial patterns of community assembly on the stream bed were uncovered, relating to longitudinal, edge and patchy patterns. Significant habitat drivers of community composition were confounded by high amounts of spatial autocorrelation, especially hydraulic variables. Due to the strongly physical and spatial nature of hydromorphological disturbance, turnover of species between sample locations at a range of scales, and the spatial arrangement of habitats and communities is of more use for detecting these types of subtle changes compared to mean richness or diversity. These findings have implications for the targeting of resources for monitoring of restoration, or engineering disturbances, in order to be sensitive to hydromorphological change. Efforts should target the main area of natural variability within the system, either replicating sampling in time or space to distinguish effects of impact. Spatial patterns, measures of beta diversity and species identity can be better exploited to identify systems with functioning geomorphological processes. Channel typologies proved misleading, and quantification of habitat and selection of control sites using multiple pre-defined criteria should be carried out. Studies of restoration operations and engineering impacts provide considerable opportunities for advancing our knowledge of the mechanisms that drive community response under a range of conditions to improve impact detection.

Abstract Describing how and why species composition of ecological communities varies across spatial and temporal scales is a primary objective for ecological research. A key challenge is to distinguish changes in community composition resulting from external factors from the natural background variability. In this thesis I aimed to study: 1) the level of temporal variation in community composition of stream macroinvertebrates, 2) the role of different environmental factors to temporal variability, 3) the effect of temporal variability on bioassessment outcomes, and 4) comparability of different approaches to study community variability through time. A majority of the studied macroinvertebrate communities showed lower level of inter-annual variation, i.e. temporal turnover, than expected by chance. The observation of high community stability was further supported by the low level of inter-annual variation in taxonomic completeness (quotient of observed and expected number of species, O/E). Despite the low absolute variation in O/E, ecological status assessments varied annually. Thus the use of one year data may bias management decisions. Macroinvertebrate communities experienced similar dynamics across several spatial extents, from riffles within a stream to streams among regions, suggesting that large-scale extrinsic factors are the major driver of community dynamics. Especially climatically exceptional years may have a strong imprint on community variability. However, at the within-stream scale, coherence was lower than expected, indicating that community dynamics may be driven by different processes at different spatial extents. Stream macroinvertebrate community dynamics were strongly related to in-stream vegetation, temporal variability decreasing with increasing macrophyte cover. Importantly, the effect of in-stream vegetation on temporal turnover of macroinvertebrate communities was masked by the stochastic effect of habitat connectivity, suggesting that unless stochastic effects are controlled for, the role of deterministic processes may be obscured, thus affecting our ability to understand and predict community changes through time. In addition, different approaches to study temporal variability may disagree on estimates for the level of temporal turnover and factors explaining it – a fact that should be taken into account when planning and comparing studies. / Tiivistelmä Yksi ekologisen tutkimuksen keskeisistä tavoitteista on kuvata, miten ja miksi eliöyhteisöjen koostumus muuttuu paikasta ja ajankohdasta toiseen. On tärkeää pystyä erottamaan erilaisten ulkoisten tekijöiden aiheuttamat muutokset luonnollisesta taustavaihtelusta. Väitöskirjani tavoitteena oli selvittää 1) miten paljon virtavesien pohjaeläinyhteisöissä tapahtuu ajallista vaihtelua 2) mitkä ympäristötekijät vaikuttavat yhteisöjen ajalliseen vaihteluun 3) miten ajallinen vaihtelu vaikuttaa ympäristön tilan arviointiin ja 4) kuinka vertailukelpoisia ovat eri lähestymistavat ajallista vaihtelua tutkittaessa. Valtaosa tutkituista pohjaeläinyhteisöistä vaihteli vuosien välillä vähemmän kuin olisi sattumalta odotettavissa osoittaen varsin suurta ajallista pysyvyyttä. Käsitystä yhteisöjen pysyvyydestä tuki myös vähäinen vuosittainen vaihtelu ekologista tilaa kuvaavassa taksonomisessa eheydessä (=havaitun ja odotetun lajiston suhde O/E). Huolimatta näennäisen pienestä vaihtelusta O/E suhteessa paikkakohtaiset tilaluokka-arviot saattoivat vaihtua vuodesta toiseen. Yhden vuoden aineistoon perustuvat tilan arvioinnit voivat siis johtaa virheellisiin johtopäätöksiin. Pohjaeläinyhteisöjen ajallinen vaihtelu oli samankaltaista eri mittakaavoilla niin peräkkäisten koskipaikkojen kuin eri alueilla sijaitsevien purojen välillä. Suuren mittakaavan ympäristötekijät näyttävät siis säätelevän eliöyhteisöjen ajallista vaihtelua. Erityisesti ilmastotekijöiltään poikkeukselliset vuodet säätelevät eliöyhteisöjä, ja niiden vaikutus voi näkyä vielä useiden vuosien kuluttua. Vaihtelun samankaltaisuus peräkkäisten koskipaikkojen välillä oli kuitenkin odotettua pienempää. Yhteisöjä voivat siis säädellä osittain eri tekijät eri mittakaavoilla. Tutkittujen pohjaeläinyhteisöjen ajallisen vaihtelun voimakkuus liittyi erityisesti vesikasvillisuuden määrään: vaihtelu väheni kasvillisuuden lisääntyessä. Kasvillisuuden määrän vaikutus peittyi kuitenkin satunnaisten tekijöiden alle. Jos satunnaisia tekijöitä ei huomioida, deterministiset syy-seuraussuhteet voivat jäädä huomaamatta heikentäen mahdollisuuksiamme ymmärtää ja ennustaa eliöyhteisöjen vaihtelua. Lisäksi eri lähestymistavat ajallista vaihtelua tutkittaessa voivat johtaa erilaisiin arvioihin vaihtelun suuruudesta ja siihen vaikuttavista tekijöistä, mikä tulisi ottaa huomioon tutkimuksia suunnitellessa ja niiden tuloksia vertailtaessa.

Abstract Streams and rivers have been extensively altered by humans. Channelization and land use have changed stream habitats and water quality with adverse effects on biota and ecosystem functions. Impacted streams have been targets for restoration, but there is considerable lack of understanding how streams should be restored in an ecologically effective way. In this doctoral thesis, I studied the impacts of channelization (for timber floating) and agricultural diffuse pollution on stream biota. I also studied the effectiveness of restorations of forestry impacted streams stressed by excessive sand sedimentation from catchment drainage. Finally, I also studied the effects of mosses, fine sediment and enhanced dispersal on stream macroinvertebrate communities and ecosystem functions. I found that channelization did not have effect on diatom, macrophyte, macroinvertebrate and fish assemblages, whereas diffuse pollution had strong effects, with no interactions between the two stressors. I showed that excessive sedimentation from forest drainage was harmful for stream biota but had no effect on leaf decomposition and algal accrual rate. Restoration with boulders reduced sand cover and was more beneficial for in-stream biodiversity, whereas restoration with wood tended to increase hydrological retention of stream channels, thereby altering riparian plant assemblages toward more natural composition. In a mesocosm experiment, I found mosses to have a strong impact on macroinvertebrate communities and ecosystem functions. Mosses increased organic matter retention and reduced algal accrual rate and leaf decomposition. The effect of mosses on macroinvertebrates was stronger than that of sand sedimentation, and mosses mitigated some of the negative effects of sand. Extensive dispersal had a distinct imprint on invertebrate community composition but did not blur the effect of mosses and sand on communities, suggesting strong local-scale environmental control of composition. My thesis emphasizes that priority in stream restoration should be in the mitigation of diffuse pollution rather than restoration of channel morphology, especially in streams where channel alteration has been fairly modest, as in the case of timber floating. Addition of both boulders and large wood likely yields the best biodiversity response in the restoration of forestry impacted streams. Mosses are a key component of boreal lotic ecosystems; therefore, the recovery of mosses may be a prerequisite for the full recovery of biodiversity and ecosystem integrity of boreal streams. / Tiivistelmä Ihmisen toiminta on laajasti muokannut virtavesiä. Uomien kanavointi ja maankäyttö ovat muuttaneet virtavesien elinympäristöjä ja veden laatua, millä on ollut haitallisia vaikutuksia virtavesien luonnon monimuotoisuuteen ja ekosysteemin toimintaan. Huonokuntoisia virtavesiä on kunnostettu paljon, mutta ymmärrys siitä, kuinka virtavesiä tulisi kunnostaa parhaan ekologisen lopputuloksen saavuttamiseksi, on edelleen vajaata. Tutkin tässä väitöskirjassa uittoperkausten ja maatalouden hajakuormituksen merkitystä ja yhteisvaikutusta virtavesien eliöyhteisöihin. Tutkin myös kunnostusten vaikutusta hiekasta kärsivissä metsätalouden muokkaamissa puroissa, sekä vesisammalten, hiekan ja eliöiden levittäytymisen merkitystä purojen pohjaeläinyhteisöjen ja ekosysteemin toimintojen muovautumisessa. Havaitsin, että uoman perkauksilla ei ollut vaikutusta virtavesien eliöyhteisöihin, mutta hajakuormituksen vaikutus oli voimakas. Perkauksella ja hajakuormituksella ei ollut yhteisvaikutuksia eliöyhteisöihin. Osoitin, että metsäojituksista aiheutuva ylimääräinen hiekan sedimentaatio on haitallista virtavesien eliöille, mutta sillä ei ollut vaikutusta lehtikarikkeen hajotukseen tai päällyslevien tuotantoon. Kunnostukset joissa käytettiin kiveä vähensivät hiekan peittävyyttä ja olivat hyödyllisempiä uoman eliöstölle kuin kunnostukset, joissa tehtiin puurakennelmia. Puukunnostukset kuitenkin lisäsivät uoman vedenpidätyskykyä ja siten muokkasivat rantavyöhykkeen kasvillisuutta luonnontilaisemmaksi. Havaitsin, että vesisammalilla on voimakas vaikutus pohjaeläinyhteisöjen koostumukseen. Sammalet vaikuttivat ekosysteemin toimintoihin lisäämällä eloperäisen aineksen pidättymistä ja vähentämällä lehtikarikkeen hajotusta ja päällyslevien tuotantoa. Sammalten vaikutus pohjaeläimiin oli voimakkaampi kuin hiekan, ja sammalet kykenivät jopa lieventämään joitakin hiekan negatiivisia vaikutuksia. Eliöiden levittäytymisellä oli selvä vaikutus yhteisöjen koostumukseen, mutta se ei hävittänyt hiekan ja sammalen vaikutusta, mikä viittaa korkeaan ympäristötekijöiden merkitykseen yhteisöjen rakentumisessa. Tutkielmani korostaa, että maatalousjokien tilan parantamisessa hajakuormituksen hallinta tulisi olla ensisijainen kunnostustavoite uoman rakenteen kunnostamisen sijaan. Metsätalouden vaikutuksista kärsivissä puroissa kivi- ja puumateriaalin käyttö samanaikaisesti tuottaa luultavimmin laajimman vaikutuksen purojen monimuotoisuuteen. Sammalilla on merkittävä vaikutus muiden eliöiden yhteisökoostumukseen ja ekosysteemin toimintoihin, joten sammalten palautuminen on tärkeä kunnostustavoite virtavesissä, joissa on luonnostaan paljon sammalkasvustoa.