Marine and coastal ecosystems are subject to diverse and increasingly intensive anthropogenic activities, making understanding cumulative effects critically important. However, accurately accounting for the cumulative effects of human impacts can be difficult, with the possibility of multiple stressors interacting and having greater impacts than expected, compounding direct and indirect effects on individuals, populations, communities and ecosystems. Assessment of multiple stressors therefore requires extensive scientific research that directly tests how single or multiple ecological components are affected by stressors, both singly and when combined, and as a consequence, cumulative effects assessments are now increasingly included in environmental assessments. Currently, there is a need to assess these at larger spatial scales, with additional research also urgently needed on the responses of ecological components, processes and functions to single and cumulative stressors. As cumulative environmental impacts could be better addressed by regional stressor effects assessments that combine methods for predicting multiple pressures on ecosystem recovery alongside degradation, this study used several separate approaches that can be used in parallel to give support for local management measures. I tested four completely different methods - a range of multi-metric indices, a food web model (Ecopath), a predictive model (Ecosim) and a Bayesian Belief Network model. Each approach was tested and compared in two shallow water estuarine systems, in Scotland and England, initially concerning the impact of nutrient enrichment and subsequent recovery and was followed by an investigation of how the addition of multiple stressors (nutrient levels, temperature and river-flow rates) would impact the future state of each system. The response to stressors was highly context dependent, varying between and within geographic locations. Overall, each of the four different approaches complemented each other and gave strong support for the need to make big reductions in the pressures and to consider trade-offs between impacting pressures. The models and tools also indicate that in order to reach an improved overall environmental state of each ecosystem, a focus on nutrient reductions are likely to be the most effective of the controls on stressors explored and that cumulative effects of the management of nutrient inputs and increased water temperatures and river-flow are likely to exist.

Enhetschefer är benämningen på den yrkesverksamma grupp som ansvarar för verksamheter som drivs enligt socialtjänstlagen och lagen om stöd och service till vissa funktionshindrade. De befinner sig i en politiskt styrd organisation med socialnämnden som uppdragsgivare. Enhetschefer är identifierade som en yrkesverksam grupp med hög arbetsbelastning och högre risk att utsättas för stress, i jämförelse med andra yrkesgrupper i ledande position. Syftet med studien är att undersöka hur olika stressfaktorer bidrar till upplevelsen av arbetsrelaterad stress hos enhetschefer inom kommunal äldre- och funktionshinderomsorg. Metodvalet är en kvantitativ enkätundersökning med syfte i att nå ut till fler personer och på så sätt få en bred överblick av enhetschefernas arbetssituation. Studien har genomförts i en medelstor svensk kommun där samtliga enhetschefer inom kommunal äldre- och funktionshinderomsorg valts ut. Av resultatet framkommer att de faktorer som i störst utsträckning bidrar till upplevd arbetsrelaterad stress, är för hög arbetsbelastning i förhållande till arbetstiden samt  bristande möjlighet att uppfylla önskemål från brukare. / Middle managers is the name of the professional group who is responsible for institutions that are run by the Social Service Act and Act concerning Support and Service for Persons with Certain Functional impairments. They work in a politically controlled organization with the municipal social welfare committee as the outsourcer. Middle managers are identified as a profession with a high workload and a higher risk of being exposed to stress, in comparison with other occupational groups with a leading position. The aim of the study is to examine how various stressors contribute to work-related stress. The method is a quantitative survey with the aim of reaching out to more people and to get a larger overview of the middle managers work situation. The study has been carried out in a medium-sized Swedish municipality, where all middle managers in municipal elderly and disability care were selected. The result shows that the stressors that contribute most to work-related stress are the high workload in relation to working time and a lack of opportunity to fulfill the client’s wishes.

Aquele chefe que já fez você chorar no banheiro pode ser mais prejudicial à sua saúde do que parece. Assim a mídia escrita principia, no Brasil, a abordagem do tema assédio moral. No amplo cardápio de situações de violência relacionadas ao trabalho, a violência psicológica ganhou visibilidade e interesse de pesquisadores e estudiosos, dos sindicatos, dos trabalhadores e das empresas. Realizamos um estudo exploratório baseado na coleta de fontes primárias referentes ao assédio moral no trabalho, no qual foram estudadas as matérias jornalísticas sobre o tema, veiculadas em três jornais de grande circulação do Estado de São Paulo, no período de 1990 a 2008. A partir da metodologia de análise do discurso foram reconhecidas as práticas discursivas que configuram o fenômeno do assédio moral na sociedade atual, as explicações para sua ocorrência e a repercussão para a saúde dos trabalhadores. O surgimento do tema nos veículos de comunicação deu-se por meio da divulgação de livros, de produções acadêmicas e de legislações sobre o assédio moral. Ocorreu em editorias que tratam de assuntos gerais e, posteriormente, migrou para as editorias de emprego e/ou de caráter econômico-financeiro. O tratamento do tema ganha contornos de alerta relacionado às indenizações judiciais. A terminologia assédio moral tem se firmado relacionada ao trabalho e carece de conceito preciso. As explicações causais tendem a uma interpretação psicológica do fenômeno, acentuando o caráter individualista e privilegiando a relação pessoal, minimizando uma abordagem coletiva. Os discursos banalizam o assédio ao criar caricaturas para os envolvidos. O caráter psicologizante versus a estigmatização produz sentido na sociedade contribuindo para naturalizar o assédio moral no trabalho, compreendido como uma forma de violência no trabalho. / That boss who already made you cry in the bathroom can be more harmful to your health than you think so. This is how the discussion started about psychological harassment at work in Brazil released by daily papers. Among the large number of work related stressors, psychological violence at workplace gained visibility of researchers, labor unions and companies in the past 10 years. The issue started to be discussed in Brazil after publications (aimed to academic and general public) were published, and legislation was established at the municipal and state levels. An exploratory study was carried out about moral harassment at work, based on articles published from 1990 to 2008, by three important daily newspapers of the State of São Paulo, Brazil. Method: An extensive review of the subject including its origins and consequences to workers health was prepared. Discourse analyses were used to recognize the phenomenon, its importance and consequences of the moral harassment at work according the published articles. Results: the articles were first published in editorials, and then they appeared in the employment, economics and finances sections of the papers. The content of the manuscripts also aimed to aware companies about law suits. In spite the terminology of moral harassment has been discussed as work-related, it still lacks a precise concept. The discourses published by the papers trivialized psychological harassment at work, as they created caricatures and stigmatization of the individuals involved. The causal explanations tend to a psychological interpretation of this phenomenon, emphasizing individual and behavioral characteristics, favoring personal relations, and minimizing the collective approach of psychological harassment at the workplace.

Teachers are exposed to stressful situations, of which increasing work demands is but one, leading to an alarming escalation of stress and professional burnout as career risks in the teaching profession. The focus of this study is on stress coping strategies to prevent burnout among primary school teachers in Lesotho. Some of the reasons which urged the researcher to carry out this study pertain to the fact that, although teacher burnout is an international concern, limited studies have addressed burnout and stress coping strategies among staff in the teaching service in Lesotho. Prolonged stress is a social problem leading to mental and physical ill health, with an increasing number of teachers leaving the teaching profession in Lesotho due to burnout. The population for the study was 600 primary school teachers who were engaging in professional development by pursuing a Bachelor of Education in primary education at the National University of Lesotho. This is a part-time programme offered by the University for practising teachers who hold a Diploma in Primary Education. The study followed a mixed-methods research approach, so for the qualitative study, data were collected using semi-structured individual interviews with 20 participants. For the quantitative study, questionnaires were administered to 350 respondents. Qualitative data were analysed using an inductive approach. Quantitative data were analysed using multiple regression, Chi-square and t-test. Key findings revealed that variables such as work overload, organisational climate and role conflict are predictors of burnout among teachers. Other variables predicting teacher burnout pertain to learner indiscipline, teacher personality and insufficient teacher remuneration. Burnout attacks career motivation. It also causes aggressive and violent behaviour among teachers. Teachers buffer stress and prevent burnout by employing constructive, less constructive and neutral stress coping strategies. The Lesotho Ministry of Education and Training can alleviate stress and prevent burnout among teachers by clarifying their job descriptions, instituting formal induction programmes for new teachers and ensuring that teacher salaries are on par with equivalent professional careers. / Onderwysers word aan stresvolle situasies blootgestel, waarvan toenemende werkseise net een is; dit lei tot 'n kommerwekkende styging van stres en professionele uitbranding as loopbaanrisiko's in die onderwysberoep. Hierdie studie fokus op strategieë om stres te hanteer om uitbranding onder laerskoolonderwysers in Lesotho te voorkom. Sommige redes wat die navorser genoop het om die studie te doen, hou verband met die feit dat alhoewel onderwyseruitbranding 'n internasionale bekommernis is, is beperkte studies gedoen om uitbranding en strategieë om stres te hanteer onder onderwysers in Lesotho gedoen. Langdurige stres is 'n sosiale probleem wat tot geestelike en fisiese swak gesondheid kan lei, met 'n toenemende aantal onderwysers wat die beroep verlaat in Lesotho as gevolg van uitbranding. Die populasie vir die studie was 600 laerskoolonderwysers wat by professionele ontwikkeling betrokke was deur vir 'n baccalaureusgraad in Opvoedkunde in primêre onderwys in te skryf by die Nasionale Universiteit van Lesotho. Dit is 'n deeltydse program wat die Universiteit aanbied vir praktiserende onderwysers met 'n Diploma in Primêre Opvoedkunde. Die studie het 'n benadering gebruik van gemengde navorsingsmetodes. Vir die kwalitatiewe studie is data versamel deur semigestruktureerde individuele onderhoude met 20 deelnemers. Vir die kwantitatiewe studie is vraelyste aan 350 respondente gegee. Kwalitatiewe data is ontleed deur 'n induktiewe benadering te gebruik. Kwantitatiewe data is ontleed deur meervoudige regressie, chi-kwadraat en t-toets te gebruik. Sleutelbevindings het getoon dat veranderlikes soos werksoorlading, organisatoriese klimaat en rolkonflik aanwysers van uitbranding onder onderwysers is. Ander veranderlikes wat onderwyseruitbranding aandui hou verband met leerders se gebrek aan dissipline, onderwysers se persoonlikhede en onvoldoende vergoeding vir onderwysers. Uitbranding val loopbaanmotivering aan. Dit lei ook tot aggressiewe en gewelddadige gedrag onder onderwysers. Onderwysers keer stres en voorkom uitbranding deur konstruktiewe, minder konstruktiewe en neutrale strategieë te gebruik om stres te hanteer. Lesotho se Ministerie van Onderwys en Opleiding kan stres verlig en uitbranding onder onderwysers voorkom deur hul posbeskrywings duidelik te maak, formele oriënteringsprogramme vir nuwe onderwysers daar te stel en te verseker dat onderwysers se salarisse ooreenkom met soortgelyke professionele beroepe. / Barutiši ba lebana le maemo a kgatelelo ya monagano, ao go ona a bakwago ke dinyakego tša mošomo o montši, gomme se se feletša go kgolo ya godimo ya kgatelelo ya monagano le go lapa mošomong wa bona wa sephrofešenale bjalo ka go tsena kotsing ya mošomo wa bona ka phrofešeneng ya biorutiši. Nepišo ya dinyakišišo tše e go maano a go kgona go šoma ka fase ga kgatelelo ye ka nepo ya go thibela go lapa kudu gareng ga barutiši ba phoraemari ka Lesotho. A mangwe a mabaka ao a dirilego gore banyakišiši ba dire dinyakišišo tše ke mabapi le taba ya gore, le ge e le gore go lapa kudu ga barutiši ke tlhobaboroko maemong a boditšhabatšhaba, dinyakišišo tše mmalwa fela di boletše ka ga maano a go kgona go šoma ka mathata a go lapa kudu le a ka fase ga kgatelelo ya monagano gareng ga bašomi ka tirelong ya borutiši ka Lesotho. Kgatelelo ya monagano ye e tšeago lebaka le letelele ke bothata bja setšhaba bjo bo feletšago ka bofokodi bja maphelo a monagano le a mmeleng, fao palo ya godimo ya barutiši e tlogelago phrofešene ya borutiši ka Lesotho ka lebaka la go lapa kudu. Batho bao ba botšišwago dipotšišo ka mo dinyakišišong tše ke barutiši ba dikolo tša phoraemari ba 600 bao ba bego ba kgatha tema ka tlhabollong ya sephrofešenale ka go dira Kgrata ya Borutiši ka thuto ya phoraemari ka Yunibesithing ya Bosetšhaba ya Lesotho. Le ke lenaneo la thuto leo le dirwago dinako tše dingwe leo le abjago ke Yunibesithi ye go barutiši bao ba šomago bao ba nago le Tiploma ya Thuto ya Phoraemari. Dinyakišišo di latetše mekgwa ya dinyakišišo ye e kopantšwego, ka fao bjalo ka dinyakišišo tša boleng, datha e kgobokeditšwe ka go šomiša dipotšišo tšeo di beakantšwego ka seripa tšeo di botšišwago motho ka o tee ka o tee fao go nago le bakgathatema ba 20. Go dinyakišišo tša bontši, dipotšišonyakišišo di filwe baarabi ba 350. Datha ya bontši e sekasekilwe ka go šomiša mokgwa wa tirišo ya bohlatse. Datha ya bontši e sekasekilwe ka go šomiša dipalopalo tša go akanya kamano, Chi-square le t-test. Dikutollo tše bohlokwa di utollotše gore dilo tše dingwe tše di fapanego tša go swana le go šoma mošomo o montši go fetišiša, seemo sa ka mošomong le thulano ya go šoma mošomo ke dilo tšeo di bonwago bjalo ka tšeo di bakago go lapa kudu gareng ga barutiši. Dilo tše dingwe tše di fapanego tše di bakago go lapa kudu di mabapi le go se be le maitshwaro a mabotse ga baithuti, semelo sa barutiši le tefelo ya barutiši ye e sego ya lekana. Go lapa kudu go hlasela tlhohleletšo ya go dira mošomo. Gape go baka maitshwaro a go befelwa le a dikgaruru gareng ga barutiši. Barutiši ba fokotša kgatelelo ya monagano le go thibela go lapa kudu ka go diriša maano a go kgona go phela ka kgatelelo ao a kwagalago, ao a kwagala gannyane le a magareng. Kgoro ya Thuto le Tlhahlo ya Lesotho e ka fediša kgatelelo ya monagano le go thibela go lapa kudu gareng ga barutiši ka go hlatholla gabotse mešomo ya bona, ka go hloma mananeo a semmušo a tlwaelo ya barutiši ba baswa le go netefatša gore meputso ya barutiši e lekana le ya mešomo ye mengwe ya go swana le yona ya sephrofešenale. / Educational Management and Leadership / D. Ed. (Educational Management)

Lazarus and Folkman's (1984) transactional stress-strain-coping theory provides the theoretical background for the present thesis. This theory proposes that strain (i.e., burnout) occurs when demands (i.e., work stressors) exceed coping resources (e.g., social support). The current thesis explores the influence of social support on the stress-burnout relationship in nurses. A sample of Australian nurses working across three public hospitals in Brisbane's metropolitan district were recruited to investigate the nature and level of burnout experienced by nurses. Burnout is characterised by emotional exhaustion, depersonalisation and reduced personal accomplishment. The present research addresses gaps in the empirical literature by investigating the key work stressors experienced by Australian nurses and by establishing nurses' referent levels of work stress, social support, and burnout. In addition, the research explores the complex relationships between work stress, social support and burnout. The majority of nursing studies have failed to consider how support from within the nurses' work environment mitigates burnout. The present research builds upon previous nursing literature by examining the "main&qout; and "buffering" effect hypotheses. Studies have consistently found support for the main effect model, however the hypothesis that social support buffers the negative effects of stress has resulted in highly conflicting findings. Some theorists (Cohen & Wills, 1985; Cutrona & Russell, 1990) propose that the buffering effects of social support will only be found if there is an adequate match between the needs elicited by the stressful event and the type of support an individual receives. The present study extends the stress or support matching theory by exploring the matching between specific types of stressors to specific types (i.e., emotional and instrumental) and sources (i.e.,supervisor and coworkers) of support. Cutrona (1990) suggests that the controllability of a stressor is the primary dimension in determining an appropriate match between stressors and types of support. Cutrona proposes that controllable stressful events elicit needs for instrumental support and uncontrollable events elicit needs for emotional support. Heeding Cutrona's advice, independent raters classified nurses' work stressors as controllable or uncontrollable stressful events prior to investigating the stressor-support matching theory. Three sequential studies were undertaken to explore the variables of interest to this research program. In Study 1, focus groups were conducted with 68 nurses (11 males, 34 females) from two public hospitals. The qualitative data was subjected to content analysis. The findings revealed that Australian nurses are exposed to a range of job-specific stressors (i.e., Job Conditions, Job Uncertainty, Interpersonal Conflict and a Lack of Professional Recognition and Support) and generic role stressors (i.e., Role Overload, Role Conflict and Role Ambiguity). The findings prompted the research to utilise Wolfgang's (1988) Health Professions Stress Inventory to measure nurses' job-specific stressors and Osipow and Spokane's (1987) Occupational Roles Questionnaire to measure nurses' role stressors in Study 2. The findings from Study 1 also confirmed that the way nurses perceive work support is consistent with current social support literature. Nurses indicated that their two main sources of support were their coworkers and their supervisor. Furthermore, nurses discussed social support from a multidimensional perspective, recognising different types of support that were broadly classified as emotional and instrumental support. Based on these findings, the researcher developed a work support measure specifically for the purpose of this research. Items were taken from established social support scales and were slightly modified to ensure that they were contextually relevant to nurses. In Study 2, 273 nurses (38 males, 235 females) completed a multi-measure questionnaire. While there was sufficient research evidence to indicate that the Occupational Roles Questionnaire (Osipow & Spokane, 1987) and the Maslach Burnout Inventory (Maslach, Jackson, & Leiter, 1996) possess adequate levels of reliability and validity, less was known about Wolfgang's Health Professions Stress Inventory and the work support scales designed for this research program. Factor analysis of the Health Professions Stress Inventory revealed a four-factor solution: Lack of Professional Recognition and Support, Patient Care Uncertainty, Job Conditions, and Interpersonal Conflict. Cronbach's coefficient alphas ranged from .62 to .83. Factor analysis of the Coworker Support Scale revealed a two-factor solution, representing emotional and instrumental support. Cronbach's coefficient alphas for the Emotional Coworker Support and Instrumental Coworker Support were .92 and .88 respectively. Contrary to expectations, factor analysis of the Supervisor Support Scale revealed a one-factor solution. It was therefore deemed appropriate to examine Supervisor Support as a unidimensional construct in subsequent analyses. Cronbach's coefficient alpha for the Supervisor Support scale was .96. Overall, the results from Study 2 provided supporting evidence to suggest that the measures used in the current research program were psychometrically sound. In Study 3, the data collected in Study 2 was subjected to further statistical analysis. The findings from Study 3 indicated that overall, the sample of Australian nurses reported low to moderate levels of work stress, moderate levels of work support and moderately high levels of burnout. For Emotional Exhaustion, predictor variables accounted for 42.2% of the total variance. Sociodemographic factors explained a small but significant proportion of the variance (2.7%). Work stressors however, were the main predictors of Emotional Exhaustion, explaining 41.5% of the total variance. Role Overload, Job Conditions and Role Conflict were the main determinants of Emotional Exhaustion, with Role Overload explaining most of the variance. For Depersonalisation, the predictor variables accounted for 34.2% of the total variance. Sociodemographic factors (11.5%) and work stressors (33.6%) both explained a significant proportion of the variance. Role Conflict and Patient Care Uncertainty were the main determinants of Depersonalisation, with Role Conflict explaining most of the variance. For Personal Accomplishment, Role Conflict and Role Ambiguity explained 20.5% of the total variance, with Role Conflict explaining most of the variance. Sociodemographic factors and job-specific stressors were not significant Predictors of Personal Accomplishment. Evidence for main effects of work support on burnout were limited. There was no evidence to suggest that work support had significant main effects on Emotional Exhaustion. Supervisor Support had a small, but significant main effect on Depersonalisation (â = -.15, p < .05) and Personal Accomplishment (â = -.24, p < .01). There was no evidence of main effects for Emotional and Instrumental Coworker Support. Furthermore, the present research found no significant evidence to support the buffering effect of work support on burnout. Theoretical and practical implications of these findings are discussed.

Text in Afrikaans / This study ascertains the extent of the experience of stress and the nature of stress management by educators. The literature showed that stress is defined from various theoretical perspectives; various approaches to stress management exist; and educators manage stress in various ways. This study defines stress from a cognitive-transactional perspective. A qualitative research method was used, descriptive data were generated by focus groups and inductively analysed. The results show that educators experienced stress ( much as seen in the literature) due to organisational, management and personal factors. According to this research, educators experience stress on the physical, emotional, social and intellectual levels. Educators' efforts to deal with stress reflect direct techniques such as seeking personal support and using confrontational techniques, as well as indirect techniques which encompass intellectual and physical techniques. Finally the development of a stress management program for educators is recommended. / Educational Studies / M. Ed. (Guidance and Counselling)

Afrikaans text / Die doel van die navorsingstudie was om die voorkoms en hantering van stressors en stres by welsynsorganisasies in die Boland streek te ondersoek ten einde aanbevelings aan die Bestuur van welsynsorganisasies te maak met die oog op voorkoming en vermindering van stres in die werksplek. Vyftien (15) welsynsorganisasies en agtien (18) maatskaplikewerkbestuurders in die Boland streek is by die ondersoek betrek. Slegs veertien (14) maatskaplikewerkbestuurders het aan die ondersoek deelgeneem. Die navorsingsproses is deur kwantitatiewe navorsing gerig en die navorsinginligting is met behulp van literatuurstudie en ‘n gestruktureerde vraelys bekom. Na aanleiding van die empiriese ondersoek is die gevolgtrekking gemaak dat Maatskaplikewerkbestuurders in die Boland streek werkstres ervaar en dat die meeste privaat-; en staatswelsynsorganisasies nie oor programme vir die voorkoming van stres beskik nie. Daar word aanbeveel dat die Bestuur van welsynsorganisasies die verantwoordelikheid moet neem om stres in die werksplek te bestuur deur die daarstelling van stres voorkomingstrategieë. / The purpose of this research study was to investigate the occurrence of stressors and stress in the private-; as well as government welfare organisation in the Boland region and to make recommendations to the Management of welfare organisations regarding the prevention and decrease of stress in the workplace. Fifteen (15) welfare organisations with eighteen (18) social work managers were approached, but only fourteen (14) participated in the investigation. The research process was directed by quantitative research and research information being obtained through literature study and a structured questionnaire. With reference to the empirical study, it was established that social workers in the Boland region experience stress in the workplace and most of the welfare organisations do not have stress prevention programmes available for social work personnel. It is recommended that the Management of welfare organisations institute stress management programmes with the focus on management of stress through stress prevention strategies. / Social Work / M.A. (SS)

Master's thesis deals with the stress applied to the employee in a work process in the company ABC, Ltd. It focuses on the factors that cause stress. It examines its manifestations and effects on health and work performance of employees. The theoretical part includes an overview of this issue. The practical part is analytical, processing questionnaires students - future employees and current employees. Visions of students at secondary and university level of stress that occurs in the process, are compared to the fact how stress manifests itself directly to employees in working conditions. The conclusion presents proposals to reduce or eliminate stress and increase resilience against him.

Attempts to quantify the effects of ocean acidification and warming (OAW) on scleractinian corals provide a growing body of response measurements. However, placing empirical results into an ecological context is challenging, owing to variations that reflect both natural heterogeneity and scientific bias. This study addresses the heterogeneity of climate change induced changes in coral recruitment and calcification. To discern scientific bias and identify drivers of the remaining heterogeneity, 100 publications were analyzed using a combination of weighted mixed effects meta-regression and factorial effect size meta‑analysis. A linear model was applied to quantify the variation caused by differing stress levels across studies. The least squares predictions were then used to standardize individual study outcomes and effect size meta-analysis was performed on original and standardized outcomes separately. On average, increased temperature significantly reduces larval survival, while ocean acidification impedes settlement and calcification. Coral resistance to OAW is likely governed by biological traits (genera and life cycle stage), environmental factors (abiotic variability) and experimental design (feeding regime, stressor magnitude, and exposure duration). Linear models suggest that calcification rates are driven by carbonate and bicarbonate concentrations, which act additively with warming. Standardizing outcomes to linear model predictions proved useful in discerning strong sources of scientific bias. The approach used in this study can improve modelling projections and inform policy and management on changes in coral community structure associated with the expected future intensification of OAW.

Abstract Although flow regime is a key element in determining the structure and function of lotic ecosystems, little is known about the variation of natural flow regimes and its relation to biological communities in highly seasonal northern boreal rivers. Temperature and precipitation patterns at northern latitudes are predicted to change drastically in the future causing severe effects on stream ecosystems. Interactions between climate change impacts and land use might further create unpredictable environmental stress. In this thesis, I first assessed the relationship of natural flow regimes of northern boreal rivers with taxonomic and functional structure of stream macroinvertebrates. Second, I combined hydrological, climate and biological models to study how climate change will alter northern flow and thermal regimes, how macroinvertebrates will respond to these changes and where these changes are going to be most pronounced. Third, I experimentally studied how different stream organisms are responding to flow change, sedimentation and their possible interaction. The role of hydrology in structuring macroinvertebrate assemblages was evident. Streams were predicted to lose much of the flow seasonality in the future, causing drastic changes that even exceeded the effect of future warming on macroinvertebrates. Especially communities within small seasonal streams were predicted to change, highlighting the importance of focusing conservation actions on these systems. Different organism groups exhibited highly variable responses to different stressors. For instance, aquatic fungi, which have been used less in climate change research, responded more strongly to flow change than traditionally used macroinvertebrates. The interactive effects of flow and sand were all antagonistic (i.e. less than the sum of the individual effects), which could be reassuring for management, although it means that both stressors may need to be removed to produce true ecological recovery. The results support the use of hydrological models in ecological studies for predicting current and future hydrological conditions at a site. However, as extreme events have been predicted to become more frequent, instead of modeling change in average conditions, future predictive models should be able to capture extreme fluctuations to gain more realistic view of climate change effects on stream ecosystems. / Tiivistelmä Joen virtaamaolosuhteet ja niiden vaihtelu ovat tärkeimpiä jokiekosysteemien rakenteeseen ja toimintaan vaikuttavia tekijöitä. Tästä huolimatta pohjoisen havumetsävyöhykkeen jokien luonnollisia virtaamaolosuhteita ja niiden yhteyttä virtavesieliöihin on tutkittu vähän. Ilmastonmuutoksen on ennustettu aiheuttavan voimakkaita muutoksia pohjoisten alueiden ilman lämpötilassa ja sadannassa, ja nämä muutokset tulevat mitä todennäköisimmin aiheuttamaan vakavia seurauksia myös jokiekosysteemeissä. Ilmastonmuutoksen ympäristövaikutukset voivat lisäksi aiheuttaa jo olemassa olevien ihmistoiminnasta aiheutuvien ympäristövaikutusten kanssa haitallisia ja vaikeasti ennustettavia yhdysvaikutuksia. Väitöskirjassani arvioin ensin pohjoisten virtavesien luonnollisten virtaamaolosuhteiden suhdetta pohjaeläinyhteisöjen taksonomiseen ja toiminnalliseen rakenteeseen. Tämän jälkeen tarkastelin yhdistämällä erilaisia ilmastonmuutoksen skenaarioita hydrologisen ja biologisen mallin kanssa, miten ilmastonmuutos saattaa tulevaisuudessa vaikuttaa jokien virtaamaolosuhteisiin ja niissä eläviin pohjaeläinyhteisöihin. Lisäksi arvioin missä ja minkälaisissa jokityypeissä ilmastonmuutoksen vaikutukset tulevat esiin kaikkein voimakkaimmin. Lopuksi tutkin kokeellisesti, miten virtaamavaihtelu ja hienojakoinen sedimentti ja näiden mahdolliset yhdysvaikutukset vaikuttavat eri virtavesieliöihin. Tulokset osoittivat, että vuodenajasta riippuvat virtaamavaihtelut vähenevät ilmastonmuutoksen myötä, minkä seurauksena pohjaeläinyhteisöissä tapahtuu voimakkaita muutoksia. Erityisesti pienten jokien pohjaeläinyhteisöjen monimuotoisuus ja koostumus muuttuivat verrattaessa tämän päivän lajistoa tulevaisuuden ennustettuun lajistoon. Eri virtavesieliöryhmät vastasivat hyvin eri tavalla virtaamavaihtelun ja hiekoittumisen aiheuttamaan elinympäristön muutokseen. Esimerkiksi akvaattiset sienet, joita on aikaisemmin harvoin käytetty ilmastonmuutostutkimuksissa, vastasivat voimakkaammin virtaamamuutoksiin kuin tutkimuksissa perinteisesti käytetyt pohjaeläimet. Kaikki kokeessa havaitut yhdysvaikutukset olivat kuitenkin pienempiä kuin yksittäisten vaikutusten summa. Tulos on huojentava vesiensuojelun kannalta, mutta tarkoittaa toisaalta myös sitä, ettei yksittäisten ihmisvaikutusten poistaminen välttämättä takaa vesistön ekologisen tilan parantumista, jos elinympäristöön vaikuttaa yhtaikaisesti useampi tekijä. Väitöskirjani tulokset tukevat hydrologisten mallien hyödyntämistä ekologisessa tutkimuksessa. Ilmastonmuutoksen myötä eri ääri-ilmiöiden, kuten rankkasateiden, on ennustettu tulevan entistä yleisimmiksi. Ääri-ilmiöiden vaikutukset ekologisiin vasteisiin tunnetaan kuitenkin heikosti. Mallien kehittämisessä olisi tämän vuoksi jatkossa tärkeää keskittyä ääri-ilmiöihin ja niiden aiheuttamiin biologisiin muutoksiin, jotta voisimme nykyistä realistisemmin arvioida ilmastonmuutoksen vaikutuksia sisävesiekosysteemeissä.