O sistema de rastreabilidade possibilita a localização do alimento em todos os elos da cadeia produtiva desde a matéria-prima até o varejo; pode prover informações da natureza, origem e qualidade do alimento; permite ao consumidor decidir, conscientemente, sobre a compra dos produtos, e permite ao produtor e à indústria, o retorno a um procedimento ou problema através de rápidos mecanismos de localização (recall). Esta pesquisa teve como objetivo a padronização e rotulagem eletrônica do pescado minimamente processado e rastreado, tendo como foco principal a perspectiva do consumidor final bem como, o levantamento de informações sobre as características do consumo de pescado em ambiente universitário e sua relação com a qualidade de vida. Para tanto, foi utilizado um sistema de coleta de dados por meio do uso da internet. A amostra foi composta por voluntários da comunidade da Universidade de São Paulo (USP). Os resultados permitiram o desenvolvimento de um produto com rotulagem eletrônica que dá acesso as principais informações da cadeia de produção pertinentes ao consumidor. O instrumento que avalia o consumo de pescado compôs, juntamente com o questionário de qualidade de vida (WHOQOL-bref) e do nível de atividade física (IPAQ), ambos da Organização Mundial da Saúde (OMS), um sistema informatizado de coleta de dados por meio dos recursos da internet . Com os dados coletados de 1966 voluntários de sete Campi da USP foi possível realizar a análise estatística de validação do instrumento e levantar os principais pontos relacionados ao consumo de pescado e qualidade de vida. Entre os principais resultados, destacam-se que o processo de rotulagem eletrônica para o pescado minimamente processado e rastreado foi considerado eficiente, rápido e seguro quanto ao acesso às informações da cadeia. O sistema de coleta de dados apresentou-se seguro e de abrangência em toda a USP, facilitando o processo de tabulação e análise de dados, primeiramente para validar os constructos do instrumento apresentando bons indicadores estatísticos, após ajustes. Foi possível observar que dentre os atributos do pescado analisados, os que mais se destacam para os consumidores são a coloração, textura, embalagem e ausência de espinho, entre outros. Apenas 35,60 % consomem entre 100 e 200g de pescado por semana o que já seria suficiente para atender a recomendação de consumo e, dessa forma, garantir os benefícios do consumo de pescado. Dentre os que consomem pescado seguindo a recomendação, 60,9 % apresentaram estado nutricional na faixa de normalidade e 74,3 % indicaram ser ativos fisicamente, sendo a maioria mulheres (59,3%), alunas de graduação (42,7 %) do Campus de São Paulo (60,9 %). A maioria considera a iniciativa de disponibilizar o pescado rastreado boa (31,63 %) ou muito boa (41,6 %). Em relação ao preço, 46,57 % considera o valor pago muito importante. Essa pesquisa permitiu ainda sinalizar os principais problemas de comercialização e aceitação, bem como, a relação do consumo de pescado, saúde e qualidade de vida, o desenvolvimento do sistema informatizado de rastreabilidade aplicado à cadeia de produção do pescado, em específico a tilápia do Nilo (Oreochromis niloticus) / The traceability system gives the food location in all productive linked chain from raw material up to retail; it can provide information from nature, origin and food quality; allow the consumer decide and be aware about the products they are buying, also permit the producer and the industry, a procedure return or problem coming from this fast locator mechanism (recall). This research aimed to standardize and electronic fishing labeling detailed processed and traceability, which the main focus is on consumer perspective to obtain information about fish consumption characteristic in a university environment and its relation with quality of life. Thus, it was used a system to obtain data collection based through internet use. The sample was composed by community voluntaries from University of São Paulo (USP). The results allowed the development of a product with electronic labeling, which gives access to key information of chain production relevant to the consumer. The instrument that evaluates fish consumption consists, together with a quality of life questionnaire (WHOQOL-bref) and physical activity level (IPAQ) both from World Health Organization (WHO), and a computerized system for collecting data through internet resources. Data collected from 1966 voluntaries of seven USP Campuses was possible to make statistic analysis of the instrument validation and raise the main topic related to fish consumption and quality of life. In the main results, highlighted the process of electronic labeling for the fish detailed processed and traceability was considered efficient, fast and safe to the access in the chain information. Data collect system performed safe and comprised around USP, easily making tab and the data analyses, firstly evaluating the construct of the instruments and showing good statistics indicators, after adjust. It was possible to observe that among fish attributes, what most highlighted to the consumer was color, texture, packing and the absence of fish bone, among other. Only 35.60% consume between 100 and 200g of fish per week, what would be sufficient to attend recommended consumption and this way guarantee the benefits of FAO consuming. For those that consume fish following the recommendation, 60.9% show nutritional normality and 74.3% show being physically active, being the majority women (59.3%), under graduating students (42.7%) from São Paulo Campus (60.9%). The initiative to provide consumers tracked fish is considered good (31.63%) and very good (41.6%). In connection to the price, 46.57% consider the price paid very important. This research even allowed showing the main acceptance and trade problems, as the relation to the fish, health and quality of life, the developing of traceability computerized system applied to the fish chain production, specially the Tilapia from Nile (Oreochromis niloticus)

Increasing awareness about the presence and ecological ramifications of toxic, persistent and bioaccumulative contaminants within the Great Lakes system spurred the implementation of numerous bans and emissions restrictions over the past few decades. Due to their high trophic status in food webs and the critical link they serve with human consumers, fish species have historically been monitored to assess the relative success of such remedial efforts within the region and to simultaneously ascertain the current risks posed to local humans. Using Bayesian dynamic linear modelling, this project first aimed to evaluate temporal trends of various organochlorine contaminants within Lake Erie fish communities, the results of which generally indicated decreasing trends through time. The second half of this study used a similar Bayesian approach to propose a framework for updating fish consumption advisories, with specific attention paid to the acknowledgment of uncertainty and natural variability when producing such consumption guidelines.

Increasing awareness about the presence and ecological ramifications of toxic, persistent and bioaccumulative contaminants within the Great Lakes system spurred the implementation of numerous bans and emissions restrictions over the past few decades. Due to their high trophic status in food webs and the critical link they serve with human consumers, fish species have historically been monitored to assess the relative success of such remedial efforts within the region and to simultaneously ascertain the current risks posed to local humans. Using Bayesian dynamic linear modelling, this project first aimed to evaluate temporal trends of various organochlorine contaminants within Lake Erie fish communities, the results of which generally indicated decreasing trends through time. The second half of this study used a similar Bayesian approach to propose a framework for updating fish consumption advisories, with specific attention paid to the acknowledgment of uncertainty and natural variability when producing such consumption guidelines.

I investigate the links between mercury use, release, deposition, and population exposure in Tampa Bay, with the focus of identifying levers for reducing population mercury exposures. To achieve this, I investigated the trends in mercury use and release by products and processes in the Tampa Bay area using a Material Flow Analysis. Analysis of USEPA National Emissions Inventory data over time (1999 - 2008) identified relevant air source emission categories, and explored and compared state and regional trends in mercury emissions. To understand source contributions to wet deposited mercury in the Tampa Bay area, I analyzed trends in mercury deposition data from the National Atmospheric Deposition Program, Mercury Deposition Network, and the 2001 Bay Regional Atmospheric Chemistry Experiment. I also collected wet deposition samples for mercury and trace metals in the Tampa Bay area during a 6-month campaign at a site at the University of South Florida (USF) campus. Samples were analyzed using Cold Vapor Atomic Fluorescence Spectrometry (CVAFS) for mercury, and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) for trace metals analysis. Concentration data were analyzed for source contributions using HYSPLIT back-trajectory meteorology-based modeling to assess source locations, and the Positive Matrix Factorization (PMF) statistical receptor model to apportion the deposition data by source type. To explore the factors influencing fish consumption behaviors of the local angler population, I analyzed population surveys collected previously from fisher-folks along the Hillsborough River, in Hillsborough County, Florida. Results from the mercury inventory indicate that mercury releases from industrial sources and dental facilities were the most important sources of mercury to the Tampa Bay area. Furthermore, the solid-waste pool was the most important direct sink in the domain, with air emissions an important indirect sink. Emissions inventory data indicated that coal-fired power plants were the largest contributors of mercury emissions in the Tampa Bay area. Medical and municipal waste incineration also accounted for significant fractions of total mercury releases to the domain. Emissions from sources in Hillsborough County accounted for a significant portion of mercury emissions in the region and state. Measurement data indicated that event mercury concentration was only very weakly correlated with event precipitation depth, with both studies showing agreement with this phenomenon. Back-trajectory simulations reveal that high mercury concentration events were often from air masses with recent trajectories over Florida land (6 and 24 hr), and with previous high precipitation depth events over the trajectory in the long term (72 hr). The statistical PMF results indicate the importance of coal burning power plant emissions, medical and municipal waste incineration, and agrochemicals on mercury in wet deposition in the Tampa Bay area. Changes were observed between the 2001 and 2012 data, including greater mercury concentrations in 2012, and the removal of medical waste incineration as a mercury source in the 2012 model results. Together with local emissions inventory data, these results suggest that sources local to the Tampa Bay area and in Florida likely contribute substantially to mercury deposition in the region. Finally, population survey data suggests that mercury exposure risks are poorly understood by the fishing population in Hillsborough County. Taken together, these results suggest that policies targeting mercury emissions control, particurlarly for coal-fired power plants and municipal waste processing, and fish consumption education may be instrumental to the protection of susceptible populations.

O sistema de rastreabilidade possibilita a localização do alimento em todos os elos da cadeia produtiva desde a matéria-prima até o varejo; pode prover informações da natureza, origem e qualidade do alimento; permite ao consumidor decidir, conscientemente, sobre a compra dos produtos, e permite ao produtor e à indústria, o retorno a um procedimento ou problema através de rápidos mecanismos de localização (recall). Esta pesquisa teve como objetivo a padronização e rotulagem eletrônica do pescado minimamente processado e rastreado, tendo como foco principal a perspectiva do consumidor final bem como, o levantamento de informações sobre as características do consumo de pescado em ambiente universitário e sua relação com a qualidade de vida. Para tanto, foi utilizado um sistema de coleta de dados por meio do uso da internet. A amostra foi composta por voluntários da comunidade da Universidade de São Paulo (USP). Os resultados permitiram o desenvolvimento de um produto com rotulagem eletrônica que dá acesso as principais informações da cadeia de produção pertinentes ao consumidor. O instrumento que avalia o consumo de pescado compôs, juntamente com o questionário de qualidade de vida (WHOQOL-bref) e do nível de atividade física (IPAQ), ambos da Organização Mundial da Saúde (OMS), um sistema informatizado de coleta de dados por meio dos recursos da internet . Com os dados coletados de 1966 voluntários de sete Campi da USP foi possível realizar a análise estatística de validação do instrumento e levantar os principais pontos relacionados ao consumo de pescado e qualidade de vida. Entre os principais resultados, destacam-se que o processo de rotulagem eletrônica para o pescado minimamente processado e rastreado foi considerado eficiente, rápido e seguro quanto ao acesso às informações da cadeia. O sistema de coleta de dados apresentou-se seguro e de abrangência em toda a USP, facilitando o processo de tabulação e análise de dados, primeiramente para validar os constructos do instrumento apresentando bons indicadores estatísticos, após ajustes. Foi possível observar que dentre os atributos do pescado analisados, os que mais se destacam para os consumidores são a coloração, textura, embalagem e ausência de espinho, entre outros. Apenas 35,60 % consomem entre 100 e 200g de pescado por semana o que já seria suficiente para atender a recomendação de consumo e, dessa forma, garantir os benefícios do consumo de pescado. Dentre os que consomem pescado seguindo a recomendação, 60,9 % apresentaram estado nutricional na faixa de normalidade e 74,3 % indicaram ser ativos fisicamente, sendo a maioria mulheres (59,3%), alunas de graduação (42,7 %) do Campus de São Paulo (60,9 %). A maioria considera a iniciativa de disponibilizar o pescado rastreado boa (31,63 %) ou muito boa (41,6 %). Em relação ao preço, 46,57 % considera o valor pago muito importante. Essa pesquisa permitiu ainda sinalizar os principais problemas de comercialização e aceitação, bem como, a relação do consumo de pescado, saúde e qualidade de vida, o desenvolvimento do sistema informatizado de rastreabilidade aplicado à cadeia de produção do pescado, em específico a tilápia do Nilo (Oreochromis niloticus) / The traceability system gives the food location in all productive linked chain from raw material up to retail; it can provide information from nature, origin and food quality; allow the consumer decide and be aware about the products they are buying, also permit the producer and the industry, a procedure return or problem coming from this fast locator mechanism (recall). This research aimed to standardize and electronic fishing labeling detailed processed and traceability, which the main focus is on consumer perspective to obtain information about fish consumption characteristic in a university environment and its relation with quality of life. Thus, it was used a system to obtain data collection based through internet use. The sample was composed by community voluntaries from University of São Paulo (USP). The results allowed the development of a product with electronic labeling, which gives access to key information of chain production relevant to the consumer. The instrument that evaluates fish consumption consists, together with a quality of life questionnaire (WHOQOL-bref) and physical activity level (IPAQ) both from World Health Organization (WHO), and a computerized system for collecting data through internet resources. Data collected from 1966 voluntaries of seven USP Campuses was possible to make statistic analysis of the instrument validation and raise the main topic related to fish consumption and quality of life. In the main results, highlighted the process of electronic labeling for the fish detailed processed and traceability was considered efficient, fast and safe to the access in the chain information. Data collect system performed safe and comprised around USP, easily making tab and the data analyses, firstly evaluating the construct of the instruments and showing good statistics indicators, after adjust. It was possible to observe that among fish attributes, what most highlighted to the consumer was color, texture, packing and the absence of fish bone, among other. Only 35.60% consume between 100 and 200g of fish per week, what would be sufficient to attend recommended consumption and this way guarantee the benefits of FAO consuming. For those that consume fish following the recommendation, 60.9% show nutritional normality and 74.3% show being physically active, being the majority women (59.3%), under graduating students (42.7%) from São Paulo Campus (60.9%). The initiative to provide consumers tracked fish is considered good (31.63%) and very good (41.6%). In connection to the price, 46.57% consider the price paid very important. This research even allowed showing the main acceptance and trade problems, as the relation to the fish, health and quality of life, the developing of traceability computerized system applied to the fish chain production, specially the Tilapia from Nile (Oreochromis niloticus)

The effect of fish consumption on the risk of cardiovascular disease has been extensively studied. Omega-3 fatty acids present in fish, namely eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have been found to have beneficial effects through several mechanisms. In addition, selenium, an antioxidant, may be protective. Fish also represents the main human exposure source to the pollutant methylmercury (MeHg), which is associated with elevated cardiovascular risk in previous studies. The aim of this thesis was to evaluate whether MeHg is associated with the risk of myocardial infarction (MI) or stroke, whether EPA+DHA or selenium (Se) have protective associations, and if the overall association between fish consumption and risk of stroke or MI is detrimental or protective. A prospective incident case-control study design was used to study effects on stroke or MI. Three hundred and sixty-nine cases with twice as many matched controls were included in the study on stroke, while 431 cases with 499 controls participated in the MI study, all from the Northern Sweden Health and Disease Study. The data was collected from health examinations of the population from 1986 until 1999. Also, time trends in burdens of mercury (Hg), lead (Pb) and cadmium (Cd) in erythrocytes (Ery) from 1990 to 1999 were examined. The food frequency questionnaire (FFQ) used in the case-control studies was correlated with measurements of fatty acids in erythrocyte membranes as biomarkers of intake. In this northern Swedish population, levels of Ery-Hg and Ery-Pb decreased during the 1990´s, but Ery-Cd decreased only in smoking men. No significant associations were found between Ery-Hg or levels of EPA+DHA and the risk of stroke. Men reporting fish consumption >3 meals/week had an elevated risk of stroke. In the MI study, higher levels of Ery-Hg were associated with lower risk of MI. No clear associations were found for reported fish consumption, levels of EPA+DHA or Ery-Se. The validated FFQ has a fair reliability in estimating intake of fatty acids EPA and DHA. However, the low variation in fish consumption in the general population in combination with different versions of the FFQ (with pre-defined, multiple choice alternatives) decreased the reliability of self-reported fish consumption in the case-control studies on risk of stroke or MI. In conclusion, MeHg has no harmful association regarding the risk of stroke or MI in this population with generally low exposure levels. The protective association regarding risk of MI is probably due to Ery-Hg being a biomarker for consumption of fish, a source of other beneficial nutrients. Thus, in this population the benefits of the nutrients in fish appear to overcome the potential harm of MeHg. The finding of elevated stroke risk related to high fish consumption in men will be investigated further. / PHIME; Public health impact of long-term, low-level mixed element exposure in susceptible population strata

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Os efeitos tóxicos do metil-mercúrio (MeHg) em seres humanos vêm sendo amplamente discutidos, a partir de episódios de contaminação devida a ingestão frequente de peixe contaminado, em Minamata, no Japão, ou ao consumo de pão preparado com cereais tratados com fungicidas a base de metil-mercúrio, no Iraque, indicando que o metil mercúrio pode afetar o sistema nervoso central. A população ribeirinha na região do Pantanal, Brasil, é dependente do peixe, como principal fonte de alimentos e proteínas. Naquela região, o resultado de décadas de mineração de ouro, em pequena escala, foi a contaminação de muitos sistemas aquáticos com mercúrio. Consequentemente, muitas espécies de peixes possuem níveis de MeHg relativamente altos. O objetivo deste trabalho foi avaliar o nível de exposição ao MeHg entre a população ribeirinha do Pantanal. No primeiro artigo, apresentam-se os resultados da validação do método recordatório de 24 horas auto-referido, utilizando-se, como padrão-ouro, o método da pesagem, tendo-se verificado que há aproximadamente um erro de 30% ao estimar a quantidade de peixe consumido por aquela população. Um erro deste pode ser importante em se tratando do consumo de peixes carnívoros, os quais apresentam altos teores de mercúrio. No segundo artigo, ao analisar a associação entre o status neurocognitivo e a concentração de mercúrio no cabelo da população acima, os resultados indicaram que adultos expostos ao metil-mercúrio, através do consumo de peixe, podem ter déficits importantes nas medidas do desempenho neurocomportamental, sem alterações detectáveis no humor ou afetividade. Os efeitos mais importantes do mercúrio, entre os indivíduos analisados, foram detectados nos testes de velocidade e destreza da coordenação motora fina, na inibição da resposta na busca visual, e em tarefas de atenção. No terceiro artigo, considerando-se as associações observadas na concentração de mercúrio no cabelo com alguns desfechos dos testes neuro-psicológicos aplicados, calculou-se a dose-marcadora (BMD) e o limite inferior do intervalo de confiança do BMD (BMDL). Os resultados da dose marcadora e da dose de referência provisória são concordantes com os resultados estimados pelas agências de saúde internacionais.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Os efeitos tóxicos do metil-mercúrio (MeHg) em seres humanos vêm sendo amplamente discutidos, a partir de episódios de contaminação devida a ingestão frequente de peixe contaminado, em Minamata, no Japão, ou ao consumo de pão preparado com cereais tratados com fungicidas a base de metil-mercúrio, no Iraque, indicando que o metil mercúrio pode afetar o sistema nervoso central. A população ribeirinha na região do Pantanal, Brasil, é dependente do peixe, como principal fonte de alimentos e proteínas. Naquela região, o resultado de décadas de mineração de ouro, em pequena escala, foi a contaminação de muitos sistemas aquáticos com mercúrio. Consequentemente, muitas espécies de peixes possuem níveis de MeHg relativamente altos. O objetivo deste trabalho foi avaliar o nível de exposição ao MeHg entre a população ribeirinha do Pantanal. No primeiro artigo, apresentam-se os resultados da validação do método recordatório de 24 horas auto-referido, utilizando-se, como padrão-ouro, o método da pesagem, tendo-se verificado que há aproximadamente um erro de 30% ao estimar a quantidade de peixe consumido por aquela população. Um erro deste pode ser importante em se tratando do consumo de peixes carnívoros, os quais apresentam altos teores de mercúrio. No segundo artigo, ao analisar a associação entre o status neurocognitivo e a concentração de mercúrio no cabelo da população acima, os resultados indicaram que adultos expostos ao metil-mercúrio, através do consumo de peixe, podem ter déficits importantes nas medidas do desempenho neurocomportamental, sem alterações detectáveis no humor ou afetividade. Os efeitos mais importantes do mercúrio, entre os indivíduos analisados, foram detectados nos testes de velocidade e destreza da coordenação motora fina, na inibição da resposta na busca visual, e em tarefas de atenção. No terceiro artigo, considerando-se as associações observadas na concentração de mercúrio no cabelo com alguns desfechos dos testes neuro-psicológicos aplicados, calculou-se a dose-marcadora (BMD) e o limite inferior do intervalo de confiança do BMD (BMDL). Os resultados da dose marcadora e da dose de referência provisória são concordantes com os resultados estimados pelas agências de saúde internacionais.

The many technological processes that products go through can make consumers less related to the systems behind them and their origins. The same thing happens to food. This project highlights the implications of a food system within the global scale of today’s mainstream economy and explores the possibilities for a product that originates from a more sustainable food system. Apart from re-designing a processed everyday food product, the aim of this study is to increase awareness of the pressure that the world’s fish stocks are suffering due to overfishing – an issue that is being aggravated by our current food system. For this reason fish fingers (aka fish sticks), which is a well known food product in Sweden, have been chosen as the primary focus in order to make a complex issue more tangible. By re-evaluating what a fish is, analysing current food systems and food products, making sensory explorations and collaborating with chefs, Havsbitar 1.0 and 2.0 (”Sea Bites” 1.0 and 2.0) have been developed. It is a series of fish fingers that has been designed for a desirable future scenario, where a resilient food system has been implemented. The aesthetics of Havsbitar intends to connect it to its ingredients and to the ecosystem it comes from, while maintaining the key characteristics of the fish finger as we know it today. The acceptance of the concept as a food product is an important variable to this project. The concept is placed in the field of Transition Design. Nevertheless, the design of Havsbitar 1.0 is a proposal that is intended to create possibilities for dialogue about an ideal industrialized commercial product. On the other hand, Havsbitar 2.0 follows a more discursive, critical angle towards the fact that fish fingers do not resemble fish, its main ingredient. Havsbitar 2.0 could then be placed in the field of Critical Food Design and Discursive Design.

Biomanipulation im Sinne einer top-down Steuerung des Nahrungsnetzes wurde in Standgewässern intensiv erforscht und wird als Mittel zur Verbesserung der Wasserqualität bzw. Verringerung der Eutrophierungserscheinungen eingesetzt. Ebenso könnte die Idee der Biomanipulation genutzt werden, um die Eutrophierung in kleinen Fließgewässern zu verringern. Eine Förderung benthischer herbivorer Schlüsselorganismen (z.B. Eintagsfliegenlarven) durch die Reduzierung des Fischfraßdruckes könnte helfen, Algenmassenentwicklungen zu vermeiden. Studien zur Biomanipulation von Nahrungsnetzen in Standgewässern zeigten allerdings eine zunehmende Entwicklung von planktischen invertebraten Räubern bei Abwesenheit planktivorer Fische. Die Bedeutung des Fraßdruckes invertebrater Räuber in fischfreien Fließgewässernahrungsnetzen ist dagegen noch unbekannt. Aufgrund von letalen und subletalen Fischeffekten könnte die Konsumtion räuberischer Invertebraten bei Fischabwesenheit so stark gefördert werden, dass das Ziel der Biomanipulation verfehlt wird. Invertebrate Räuber haben insgesamt einen relativ hohen Anteil an der Biomasse der Benthosgemeinschaft in Fließgewässernahrungsnetzen. Sie könnten somit potentiell einen ähnlichen Fraßdruck wie vertebrate Räuber (z.B. benthivore Fische) auf die unteren trophischen Ebenen ausüben. Auch der Anteil der Omnivorie ist in Fließgewässernahrungsnetzen hoch. Ziel dieser Arbeit war es deshalb, die Bedeutung invertebrater Prädation im Nahrungsnetz eines kleinen Fließgewässers (Gauernitzbach) unter Berücksichtigung der obligaten Räuber sowie des räuberischen Potentials Omnivorer abzuschätzen. Außerdem wurde der Einfluss benthivorer Fische auf die Populationsentwicklung und das Ernährungsverhalten der wichtigsten invertebraten Räuber und Omnivoren untersucht. Dazu wurde ein Bachabschnitt, der mit benthivoren Fischen (Gobio gobio, Barbatula barbatula) besetzt war, mit einem fischfreien Abschnitt über zwei Jahre verglichen. Nach der Identifizierung wichtiger Räuber- und Omnivorenarten anhand ihrer Biomasse und ihrer trophischen Positionen mittels Isotopenanalyse wurde ihr Gesamtfraßdruck abgeschätzt. Invertebrate Prädatoren im Nahrungsnetz des Gauernitzbaches waren Rhyacophila fasciata und Plectrocnemia conspersa (Trichoptera), Isoperla grammatica (Plecoptera) sowie Dugesia gonocephala (Turbellaria). Wichtige Omnivore aufgrund ihrer hohen Biomassen waren Gammarus pulex (Amphipoda) und Hydropsyche spp. (Trichoptera). Anhand eines Mischungsmodells (ISOSOURCE), das auf der Basis der stabilen Isotopensignaturen d13C und d15N die einzelnen Ressourcenanteile einer gemischten Signatur berechnet, konnte das ausgeprägte räuberische Potential der Omnivoren gezeigt werden, da sie einen hohen tierischen Anteil in der Nahrung aufwiesen (20-90 %). Im Nahrungsnetz des Gauernitzbaches waren Omnivore als Räuber damit ebenso bedeutsam wie obligat räuberische Invertebrate. Der Gesamtfraßdruck der invertebraten Räuber und Omnivoren auf die Beuteorganismen (bis 16 g TM m-2 a-1) in der Fischstrecke war höher als der Fraßdruck der benthivoren Fische (~3 g TM m-2 a-1). Dieser Unterschied lag hauptsächlich in höheren täglichen Konsumtionsraten bei ähnlich hohen Biomassen der Invertebraten begründet. Durch die Analyse der stabilen Isotope von Kohlenstoff und Stickstoff konnten die trophischen Beziehungen im Nahrungsnetz des Gauernitzbaches identifiziert werden. Dabei stellten allochthone Kohlenstoffquellen im Frühjahr und Herbst die bedeutendste Ressource für die Primärkonsumenten dar, während autochthone Ressourcen nur im Frühjahr für wenige Herbivore relevant waren. Dies spiegelte sich ebenso in der Nahrung der Omnivoren wider, die neben Organismen hauptsächlich Detritus nutzten. Ebenso zeigten die invertebraten Räuber eine deutliche Abhängigkeit vom allochthonen Kohlenstoff über die Nutzung der Primärkonsumenten. Letale Effekte der Fische auf die räuberischen und omnivoren Populationen im Gauernitzbach fanden hauptsächlich in Abhängigkeit von den bewohnten Habitaten statt. Die Pool-Arten (P. conspersa, D. gonocephala, G. pulex) entwickelten geringere Biomassen in der Fischstrecke, während die Biomassen riffle-bewohnender Invertebraten (R. fasciata, I. grammatica, Hydropsyche spp.) nicht deutlich reduziert wurden. Dabei waren allerdings meist hohe Biomassen in der Fischstrecke weniger stark ausgeprägt als in der fischfreien Strecke. Die Adulten der untersuchten Arten wurden oft stärker letal beeinflusst als die Juvenilstadien. So war die Emergenzproduktion der räuberischen Köcherfliegen und die Abundanz großer und eiertragender Weibchen von G. pulex in der Fischstrecke deutlich verringert. Subletale Effekte der Fische traten im Gauernitzbach in Abhängigkeit von den Ernährungstypen auf. Während die adulten räuberischen Köcherfliegenarten R. fasciata und P. conspersa keine negative Beeinflussung der Fitness und Größe zeigten, emergierte die omnivore Köcherfliege H. instabilis in der Fischstrecke kleiner als in der fischfreien. Außerdem unterschieden sich die Antworten der omnivoren Arten vermutlich aufgrund ihrer unterschiedlichen Lebenszyklen. G. pulex zeigte als ausschließlich aquatisch lebende Art keine subletalen Kosten (unveränderte Fitness) bei Fischanwesenheit wie dies für die omnivore merolimnische Insektenart H. instabilis beobachtet wurde. Die mittlere Fitness der Populationen (gemessen an der Eiproduktion pro Zeit- und Flächeneinheit) war für alle untersuchten invertebraten Räuber und Omnivoren bei Fischanwesenheit deutlich geringer als in der fischfreien Strecke. Für die Räuber (R. fasciata, P. conspersa) und G. pulex waren vermutlich letale Fischeffekte für den geringen Reproduktionserfolg verantwortlich. Dagegen wurde die Fitness der Population von H. instabilis durch die Kombination aus der geringeren individuellen Körpergröße (subletal) und den schwachen letalen Effekten auf die Emergenz reduziert. Der Einfluss der Fische auf die räuberischen Larven von R. fasciata und P. conspersa resultierte in einem Wechsel der Beutezusammensetzung, nicht in der Reduzierung der täglichen Fraßaktivität. Dies war vermutlich auf eine Aktivitätsänderung des Räubers R. fasciata bzw. auf die veränderte Beuteverfügbarkeit für P. conspersa unter Fischeinfluss zurückzuführen. Eine grundsätzliche Verringerung der Fraßaktivität oder der tierischen Anteile in der Nahrung der omnivoren Arten unter dem Einfluss benthivorer Fische wurde nicht festgestellt. Dagegen änderten sich die Relationen der Ressourcen Omnivorer zueinander, so konnte in der fischfreien Strecke eine flexiblere Ressourcennutzung nachgewiesen werden. Die jährliche Gesamtkonsumtion der räuberischen und omnivoren Invertebraten wurde durch die Anwesenheit der benthivoren Fische um 20-50 % reduziert, wofür hauptsächlich fischinduzierte Biomasseänderungen verantwortlich waren. In der fischfreien Strecke konnte dagegen die erhöhte Konsumtion der Invertebraten den fehlenden Fischfraßdruck mehr als kompensieren. Allerdings änderte sich die beutespezifische Konsumtion der Räuber in der fischfreien Strecke durch den verhaltensinduzierten Wechsel in der Beutezusammensetzung. Damit fand ein erhöhter Fraßdruck auf detritusfressende Arten (z.B. Diptera) statt, während die vermuteten Schlüsselarten einer potentiellen Biomanipulation (grazende Eintagsfliegen) in der fischfreien Strecke relativ unbeeinflusst blieben. Da die invertebrate Prädation in Fließgewässern sehr bedeutend sein kann, ist Biomanipulation nur unter Berücksichtigung aller Populationen räuberischer Invertebraten möglich. Nur durch Einstellung einer optimalen (relativ hohen) Biomasse geeigneter benthivorer Fischarten kann eine ausreichende Hemmung der invertebraten Räuber erreicht werden, so dass grazende Arten indirekt profitieren. / Biomanipulation (top-down control of the food webs) in lakes was intensively studied and can today be regarded as an important tool for improvement of the water quality and eutrophication. Similarly, the idea of biomanipulation can be used to reduce eutrophication phenomena in streams. The enhancement of benthic herbivorous key species (e.g. mayflies) by reduction of fish predation pressure could prevent exploding benthic algae biomass. Studies dealing with trophic cascades in lakes suggested that biomass of planktic invertebrate predators is increasing in the absence of planktivorous fish. But until now the importance of invertebrate predation pressure in fishless stream food webs is hardly known. Due to lethal and sublethal fish effects the consumption of predatory invertebrates could be enhanced by the absence of fish to such an extent that biomanipulation could be off target. In general, the proportion of invertebrate predators to the biomass of the benthic community in stream food webs is relatively high. Therefore, invertebrate predation on benthic prey can be as important as vertebrate predation (e.g. by benthivorous fish). Furthermore, omnivory occurs frequently in streams. Therefore, the aim of this thesis was to assess the importance of invertebrate predation in a food web of a small stream (Gauernitzbach) including the obligatory predators as well as the predatory potential of omnivores. Furthermore, the impact of benthivorous fish on population dynamics and feeding behaviour of the most important predators and omnivores was studied. Therefore, a reach stocked with benthivorous fish (Gobio gobio, Barbatula barbatula) was compared with an upstream fishless reach over a two-year period. After identification of important predators and omnivores based on their biomass and trophic position by stable isotope analyses their total consumption was estimated. Rhyacophila fasciata and Plectrocnemia conspersa (Trichoptera), Isoperla grammatica (Plecoptera) as well as Dugesia gonocephala (Turbellaria) were the invertebrate predators in the food web of Gauernitzbach. Because of their high biomasses the most important omnivores were Gammarus pulex (Amphipoda) and Hydropsyche spp. (Trichoptera). Using a mixing model (ISOSOURCE) that estimates the proportions of single resources on a mixed signature on the basis of the stable 13C and 15N isotopes, the predatory potential of both omnivores was pronounced by a high animal food proportion (20-90%). In this stream food web the predation impact of omnivores was comparable to this of obligatory predacous invertebrates. The total invertebrate predation pressure (up to 16 g TM m-2 a-1) in the fish reach was higher than the vertebrate predation pressure (~3 g TM m-2 a-1) mainly caused by the higher daily consumption rates and similar biomass compared to fish. Using stable isotope analyses of carbon and nitrogen the trophic pathways in the food web of Gauernitzbach could be identified. The most important resources for primary consumers in spring and autumn were allochthonous carbon sources. Autochtnonous carbon sources were only utilized by a few herbivores in spring. This was also reflected in the food of omnivores which assimilated mainly detritus beside animal material. Similarly, the predators depended distinctly on the allochthonous pathway by feeding primary consumers. Lethal fish effects on the predatory and omnivorous invertebrate populations were mainly depended on their preferred habitats. Pool-dwelling species (P. conspersa, D. gonocephala, G. pulex) showed decreased biomass in the presence of fish. Contrary, the biomass of riffle-dwelling invertebrates (R. fasciata, I. grammatica, Hydropsyche spp.) was not significantly reduced in the fish reach. Thereby, the highest biomass values in the fish reach could not reach the same level as in the fishless reach. Adults of the investigated species were influenced more lethal than the young stages. Hence, the emergence production of the predatory caddisflies and the abundance of the biggest and gravid females of G. pulex were reduced in the fish reach. Sublethal fish effects existed in dependence on the feeding groups of the invertebrates in Gauernitzbach. Whereas the adult predatory caddisflies R. fasciata and P. conspersa did not show disadvantages in fitness and size, the omnivorous caddisfly H. instabilis emerged with smaller size in the fish reach than in the fishless reach. Different responses of both omnivorous species were observed because of their different life cycles. The exclusively aquatic living G. pulex was not influenced sublethal by fish as the merolimnic insect species H. instabilis. The average fitness of population (measured as egg production per unit time and space) of the studied invertebrate predators and omnivores was distinctly reduced in the fish reach compared to the fishless reach. Probably, lethal fish effects were mainly responsible for the low reproductive success of the predatory species (R. fasciata, P. conspersa) and G. pulex. In contrast, the reduction of population fitness of H. instabilis was caused by the reduced individual adult size (sublethal effect) in combination with the weak lethal effect on emergence. The impact of fish on the feeding behaviour of the predatory larvae of R. fasciata and P. conspersa resulted in a switched prey composition, whereas a reduction in the daily feeding activity was not observed. That was supposed because of changes in the activity pattern by the predator R. fasciata or the changed prey availability for P. conspersa in the fish reach. A general reduction in feeding activity or animal food proportion of the omnivores was not assessed in the presence of fish. In contrast, the relations between the resources switched to a more variable utilisation in the fishless reach. The annual total consumption of invertebrate predators and omnivores was decreased by 20-50% in the fish reach, mainly caused by fish induced biomass reduction. The missing fish consumption could be at least balanced by higher invertebrate consumption in the fishless reach. Contrary, the prey specific consumption of invertebrate predators changed by behavioural-induced switch in the prey composition between the stream reaches. Therefore, a higher predation pressure on detritus feeding species (e.g Diptera) was found in the fishless reach, but not on the supposed key species of the potential biomanipulation (e.g. grazing mayflies). Due to the high importance of invertebrate predation in stream food webs, the aim of biomanipulation can only be reached by considering the populations of predatory invertebrates. Controlling the biomass of suitable benthivorous fish to an optimum (relatively high) level could sufficiently reduce the impact of invertebrate predators leading to an indirect enhancement of grazing species.