<p>In evolutionary robotics there has been research about the pursuit problem with different numbers of predators and prey: (i) one predator and one prey, (ii) many predators against one prey, and (iii) many predators against many prey. However, these different experiments are only involving food chains with two populations (two trophic levels). This dissertation uses three trophic levels to investigate if individuals in the middle trophic level perform equally or better than those that are been evolved in a two trophic level environment.</p><p>The investigation was done in a simulator called YAKS. A statistical analysis was conducted to evalutate the results. The result indicated that a robot with two tasks gets better at hunting and evading than robots with one task (either hunt or evade). Robots from the middle trophic level that are moving in the same direction as the camera is facing, were the best predators and prey. This dissertation is a step towards more complex and animal-like behaviours of robots.</p>

In evolutionary robotics there has been research about the pursuit problem with different numbers of predators and prey: (i) one predator and one prey, (ii) many predators against one prey, and (iii) many predators against many prey. However, these different experiments are only involving food chains with two populations (two trophic levels). This dissertation uses three trophic levels to investigate if individuals in the middle trophic level perform equally or better than those that are been evolved in a two trophic level environment. The investigation was done in a simulator called YAKS. A statistical analysis was conducted to evalutate the results. The result indicated that a robot with two tasks gets better at hunting and evading than robots with one task (either hunt or evade). Robots from the middle trophic level that are moving in the same direction as the camera is facing, were the best predators and prey. This dissertation is a step towards more complex and animal-like behaviours of robots.

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Os recursos pesqueiros estão sendo sobre-explotados mundialmente. A pesca pode conduzir ao efeito de cascata trófica e essa exploração pode ser insustentável. Por isso políticas de manejo são urgentes, mas faltam dados para subsidiar tais políticas e nesse sentido, estudos com pescadores artesanais através de entrevistas têm colaborado com o conhecimento sobre a dinâmica pesqueira. A pesca artesanal brasileira é a principal atividade econômica ou de subsistência e o pescado é a maior fonte de proteínas para populações caboclas ribeirinhas amazônicas e populações de caiçaras que vivem na área litorânea da Mata Atlântica. Esta pesquisa analisou padrões ecológicos espaciais e temporais na pesca artesanal brasileira em dois ecossistemas: a costa sudeste da Mata Atlântica e a Amazônia fluvial, tendo como base de dados entrevistas realizadas com pescadores ao longo de vários projetos de pesquisa. No capítulo 1 analisou-se a produtividade pesqueira no litoral sudeste. Foi testada a variação da biomassa média capturada citada pelos entrevistados em função de fatores temporais (idade do pescador e data em que ocorreu sua última pescaria) e espaciais (região aonde se localiza a comunidade do pescador entrevistado). Foram analisadas entrevistas com 423 pescadores, que indicaram que: a) houve uma diminuição na quantidade de peixes capturados ao longo do tempo; b) a biomassa capturada não foi influenciada pelo fator espacial; c) não houve influência da idade do pescador na biomassa capturada mencionada. O capítulo 2 abordou a costa sudeste da Mata Atlântica e a Amazônia fluvial. Foram analisadas a composição dos peixes, através dos nomes populares citados e seu nível trófico médio. Foram analisadas entrevistas com 658 pescadores da Amazônia fluvial (de 1987 a 2006) e 821 pescadores da costa sudeste da Mata Atlântica (de 1986 a 2009) (n=1479 entrevistados). Não houve variação do nível trófico segundo o tempo, porém o nível trófico variou de acordo com os fatores espaciais (ecossistema e região), sendo que o fator que mais influenciou essa variação foi região. Na costa sudeste da Mata Atlântica há possível substituição das espécies de nível trófico similar por outras espécies de mesmo valor econômico com o tempo. Na Amazônia fluvial esse padrão de substituição das espécies não foi observado. Conclui-se que a diminuição da biomassa capturada ao longo do tempo somada à substituição de determinadas espécies de peixes capturados na costa da Mata Atlântica, podem indicar que a pesca não está sendo sustentável. Medidas preventivas de manejo pesqueiro devem ser implementadas. / Fisheries resources are being over-exploited worldwide. Excessive fishing can lead to trophic cascades and this exploration may be unsustainable. Therefore, management policies are urgent, but data are lacking to support such policies. In this sense, studies addressing interviews with fishermen have collaborated with the knowledge about the dynamics of fishing. The Brazilian artisanal fishing is the main economic and subsistence activity and the main source of protein for riverine Amazonian Caboclo populations and caiçara populations, who live in the coastal area of the Atlantic Forest. This study examined spatial and temporal ecological patterns in Brazilian artisanal fisheries in two ecosystems: the southeast coast of the Atlantic Forest and the fluvial Amazon; the data was based in interviews with fishermen on the course of several research projects. In Chapter 1 it was analyzed the fishery productivity in the southeastern coast. It was checked the variation in the average biomass of fish captured according to the interviews with fishers, due to temporal factors (fishermen’s age and date of their last fishery) and spatial factors (the region where the community of fishermen interviewed is located). There were analyzed interviews with 423 fishers, indicating that: a) there was a decrease in the biomass of fish caught over time, b) the biomass of fish caught was not influenced by the spatial factor c) there was no influence of age of the fisherman on the biomass of fish caught that was mentioned by them. Chapter 2 addressed the southeast coast of the Atlantic Forest and the Inland freshwater Amazon. It was analyzed the composition of fish caught, through their popular names mentioned by fishers and their mean trophic level. There were analyzed interviews with 658 fishers in the Amazon Basin (from 1987 to 2006) and with 821 fishers in to the southeast coast of the Atlantic Forest (from 1986 to 2009) (n = 1479 fishers). There was no variation in trophic level according to the time since the last fishing trip, and according to the spatial factors (ecosystem and region), and the region was the factor that most influenced the variation in trophic level. On the southeast coast of the Atlantic Forest species with similar trophic levels have been probably replaced by species of similar economic value over time. However, in the freshwater Amazon this pattern of species replacement was not observed. It is concluded that the decrease in biomass captured over time and the replacement of species on the Atlantic coast, may indicate that the fishery has been not sustainable. Preventive fisheries management measures should thus be devised.

Os recursos pesqueiros estão sendo sobre-explotados mundialmente. A pesca pode conduzir ao efeito de cascata trófica e essa exploração pode ser insustentável. Por isso políticas de manejo são urgentes, mas faltam dados para subsidiar tais políticas e nesse sentido, estudos com pescadores artesanais através de entrevistas têm colaborado com o conhecimento sobre a dinâmica pesqueira. A pesca artesanal brasileira é a principal atividade econômica ou de subsistência e o pescado é a maior fonte de proteínas para populações caboclas ribeirinhas amazônicas e populações de caiçaras que vivem na área litorânea da Mata Atlântica. Esta pesquisa analisou padrões ecológicos espaciais e temporais na pesca artesanal brasileira em dois ecossistemas: a costa sudeste da Mata Atlântica e a Amazônia fluvial, tendo como base de dados entrevistas realizadas com pescadores ao longo de vários projetos de pesquisa. No capítulo 1 analisou-se a produtividade pesqueira no litoral sudeste. Foi testada a variação da biomassa média capturada citada pelos entrevistados em função de fatores temporais (idade do pescador e data em que ocorreu sua última pescaria) e espaciais (região aonde se localiza a comunidade do pescador entrevistado). Foram analisadas entrevistas com 423 pescadores, que indicaram que: a) houve uma diminuição na quantidade de peixes capturados ao longo do tempo; b) a biomassa capturada não foi influenciada pelo fator espacial; c) não houve influência da idade do pescador na biomassa capturada mencionada. O capítulo 2 abordou a costa sudeste da Mata Atlântica e a Amazônia fluvial. Foram analisadas a composição dos peixes, através dos nomes populares citados e seu nível trófico médio. Foram analisadas entrevistas com 658 pescadores da Amazônia fluvial (de 1987 a 2006) e 821 pescadores da costa sudeste da Mata Atlântica (de 1986 a 2009) (n=1479 entrevistados). Não houve variação do nível trófico segundo o tempo, porém o nível trófico variou de acordo com os fatores espaciais (ecossistema e região), sendo que o fator que mais influenciou essa variação foi região. Na costa sudeste da Mata Atlântica há possível substituição das espécies de nível trófico similar por outras espécies de mesmo valor econômico com o tempo. Na Amazônia fluvial esse padrão de substituição das espécies não foi observado. Conclui-se que a diminuição da biomassa capturada ao longo do tempo somada à substituição de determinadas espécies de peixes capturados na costa da Mata Atlântica, podem indicar que a pesca não está sendo sustentável. Medidas preventivas de manejo pesqueiro devem ser implementadas. / Fisheries resources are being over-exploited worldwide. Excessive fishing can lead to trophic cascades and this exploration may be unsustainable. Therefore, management policies are urgent, but data are lacking to support such policies. In this sense, studies addressing interviews with fishermen have collaborated with the knowledge about the dynamics of fishing. The Brazilian artisanal fishing is the main economic and subsistence activity and the main source of protein for riverine Amazonian Caboclo populations and caiçara populations, who live in the coastal area of the Atlantic Forest. This study examined spatial and temporal ecological patterns in Brazilian artisanal fisheries in two ecosystems: the southeast coast of the Atlantic Forest and the fluvial Amazon; the data was based in interviews with fishermen on the course of several research projects. In Chapter 1 it was analyzed the fishery productivity in the southeastern coast. It was checked the variation in the average biomass of fish captured according to the interviews with fishers, due to temporal factors (fishermen’s age and date of their last fishery) and spatial factors (the region where the community of fishermen interviewed is located). There were analyzed interviews with 423 fishers, indicating that: a) there was a decrease in the biomass of fish caught over time, b) the biomass of fish caught was not influenced by the spatial factor c) there was no influence of age of the fisherman on the biomass of fish caught that was mentioned by them. Chapter 2 addressed the southeast coast of the Atlantic Forest and the Inland freshwater Amazon. It was analyzed the composition of fish caught, through their popular names mentioned by fishers and their mean trophic level. There were analyzed interviews with 658 fishers in the Amazon Basin (from 1987 to 2006) and with 821 fishers in to the southeast coast of the Atlantic Forest (from 1986 to 2009) (n = 1479 fishers). There was no variation in trophic level according to the time since the last fishing trip, and according to the spatial factors (ecosystem and region), and the region was the factor that most influenced the variation in trophic level. On the southeast coast of the Atlantic Forest species with similar trophic levels have been probably replaced by species of similar economic value over time. However, in the freshwater Amazon this pattern of species replacement was not observed. It is concluded that the decrease in biomass captured over time and the replacement of species on the Atlantic coast, may indicate that the fishery has been not sustainable. Preventive fisheries management measures should thus be devised.

Os recursos pesqueiros estão sendo sobre-explotados mundialmente. A pesca pode conduzir ao efeito de cascata trófica e essa exploração pode ser insustentável. Por isso políticas de manejo são urgentes, mas faltam dados para subsidiar tais políticas e nesse sentido, estudos com pescadores artesanais através de entrevistas têm colaborado com o conhecimento sobre a dinâmica pesqueira. A pesca artesanal brasileira é a principal atividade econômica ou de subsistência e o pescado é a maior fonte de proteínas para populações caboclas ribeirinhas amazônicas e populações de caiçaras que vivem na área litorânea da Mata Atlântica. Esta pesquisa analisou padrões ecológicos espaciais e temporais na pesca artesanal brasileira em dois ecossistemas: a costa sudeste da Mata Atlântica e a Amazônia fluvial, tendo como base de dados entrevistas realizadas com pescadores ao longo de vários projetos de pesquisa. No capítulo 1 analisou-se a produtividade pesqueira no litoral sudeste. Foi testada a variação da biomassa média capturada citada pelos entrevistados em função de fatores temporais (idade do pescador e data em que ocorreu sua última pescaria) e espaciais (região aonde se localiza a comunidade do pescador entrevistado). Foram analisadas entrevistas com 423 pescadores, que indicaram que: a) houve uma diminuição na quantidade de peixes capturados ao longo do tempo; b) a biomassa capturada não foi influenciada pelo fator espacial; c) não houve influência da idade do pescador na biomassa capturada mencionada. O capítulo 2 abordou a costa sudeste da Mata Atlântica e a Amazônia fluvial. Foram analisadas a composição dos peixes, através dos nomes populares citados e seu nível trófico médio. Foram analisadas entrevistas com 658 pescadores da Amazônia fluvial (de 1987 a 2006) e 821 pescadores da costa sudeste da Mata Atlântica (de 1986 a 2009) (n=1479 entrevistados). Não houve variação do nível trófico segundo o tempo, porém o nível trófico variou de acordo com os fatores espaciais (ecossistema e região), sendo que o fator que mais influenciou essa variação foi região. Na costa sudeste da Mata Atlântica há possível substituição das espécies de nível trófico similar por outras espécies de mesmo valor econômico com o tempo. Na Amazônia fluvial esse padrão de substituição das espécies não foi observado. Conclui-se que a diminuição da biomassa capturada ao longo do tempo somada à substituição de determinadas espécies de peixes capturados na costa da Mata Atlântica, podem indicar que a pesca não está sendo sustentável. Medidas preventivas de manejo pesqueiro devem ser implementadas. / Fisheries resources are being over-exploited worldwide. Excessive fishing can lead to trophic cascades and this exploration may be unsustainable. Therefore, management policies are urgent, but data are lacking to support such policies. In this sense, studies addressing interviews with fishermen have collaborated with the knowledge about the dynamics of fishing. The Brazilian artisanal fishing is the main economic and subsistence activity and the main source of protein for riverine Amazonian Caboclo populations and caiçara populations, who live in the coastal area of the Atlantic Forest. This study examined spatial and temporal ecological patterns in Brazilian artisanal fisheries in two ecosystems: the southeast coast of the Atlantic Forest and the fluvial Amazon; the data was based in interviews with fishermen on the course of several research projects. In Chapter 1 it was analyzed the fishery productivity in the southeastern coast. It was checked the variation in the average biomass of fish captured according to the interviews with fishers, due to temporal factors (fishermen’s age and date of their last fishery) and spatial factors (the region where the community of fishermen interviewed is located). There were analyzed interviews with 423 fishers, indicating that: a) there was a decrease in the biomass of fish caught over time, b) the biomass of fish caught was not influenced by the spatial factor c) there was no influence of age of the fisherman on the biomass of fish caught that was mentioned by them. Chapter 2 addressed the southeast coast of the Atlantic Forest and the Inland freshwater Amazon. It was analyzed the composition of fish caught, through their popular names mentioned by fishers and their mean trophic level. There were analyzed interviews with 658 fishers in the Amazon Basin (from 1987 to 2006) and with 821 fishers in to the southeast coast of the Atlantic Forest (from 1986 to 2009) (n = 1479 fishers). There was no variation in trophic level according to the time since the last fishing trip, and according to the spatial factors (ecosystem and region), and the region was the factor that most influenced the variation in trophic level. On the southeast coast of the Atlantic Forest species with similar trophic levels have been probably replaced by species of similar economic value over time. However, in the freshwater Amazon this pattern of species replacement was not observed. It is concluded that the decrease in biomass captured over time and the replacement of species on the Atlantic coast, may indicate that the fishery has been not sustainable. Preventive fisheries management measures should thus be devised.

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / O processo de armazenamento de Ãgua em regiÃes semi-Ãridas tem se tornado um considerÃvel meio de reduzir a escassez deste recurso natural. Assim, à comum em regiÃes, com caracterÃsticas do Nordeste Brasileiro, a construÃÃo de grandes reservatÃrios, que tem servido para atender, com certa regularidade, demandas para os mais diversos usos. Por outro lado, o armazenamento de Ãgua em reservatÃrios acaba tornando essas massas lÃquidas vulnerÃveis a um maior risco de degradaÃÃo. Como se sabe, a Ãgua armazenada fica sujeito a longo tempo de residÃncia, permitindo assim com que algumas importantes reaÃÃes, tanto do ponto de vista quÃmico, como biolÃgico, possam ocorrer. Estas reaÃÃes, associadas com alguns lanÃamentos de efluentes, provenientes de zonas urbanas, Ãreas industriais e zonas rurais, acabam por acelerar o processo de envelhecimento dos reservatÃrios, conhecido como âprocesso de EutrofizaÃÃoâ, que depende, fundamentalmente, da disponibilidade de nutrientes no interior dos reservatÃrios. Este trabalho estudou, atravÃs de pesquisa de campo, associada com uma metodologia de cÃlculo de Ãndices de Estado TrÃfico Modificado e Ãndice de Qualidade de Ãgua, as condiÃÃes ambientais do ReservatÃrio Acarape do Meio, no Estado do CearÃ, na busca de uma identificaÃÃo das principais transformaÃÃes nos seus nÃveis trÃficos, bem como, na identificaÃÃo das principais causas de um possÃvel processo de eutrofizaÃÃo do mesmo. Para isso foram utilizados dados de campo em um perÃodo de 2001 a 2006, o que permitiu conhecer as caracterÃsticas pertinentes à estratificaÃÃo deste corpo hÃdrico, no que diz respeito à temperatura e a estratificaÃÃo quÃmica de suas Ãguas. TambÃm, tendo em vista os vÃrios pontos de coletas de dados, foi possÃvel apresentar resultados relativos ao Ãndice de Estado TrÃfico e ao Ãndice de Qualidade de Ãgua, em uma distribuiÃÃo espacial do reservatÃrio, mostrando, assim, os vÃrios pontos crÃticos do mesmo. Nas questÃes pertinentes ao Ãndice de Estado TrÃfico foram usados dois cÃlculos, sendo para o primeiro usado, apenas, a clorofila-a e o fÃsforo, enquanto que no segundo cÃlculo foram utilizados, alÃm dessas duas substÃncias, o ortofosfato solÃvel presente naquelas Ãguas. Os resultados mostram que hà uma forte variabilidade da qualidade das Ãguas deste reservatÃrio, mas que, nos anos de 2004 e 2005, suas Ãguas atingiram um nÃvel hipereutrÃfico, o que representa a presenÃa de um forte aporte de nutrientes provenientes das entradas do reservatÃrio e, provavelmente, das zonas rurais que existem em torno do mesmo. Os resultados mostraram ainda que, mesmo que a variaÃÃo vertical de temperatura nÃo seja tÃo significativa no interior do reservatÃrio, hà uma forte presenÃa de estratificaÃÃo quÃmica nas camadas mais profundas deste corpo hÃdrico. / The process of storage of water in semi-arid regions has become a considerable way of reducing the shortage of this natural resource. Like this, it is common in areas with characteristics of the Brazilian Northeast, the construction of great reservoirs that has been being to assist, with certain regularity, demands for the most several uses. On the other hand, the storage of water in reservoirs bring some vulnerabilities to the water, concerning with the degradation risk. As it is known, the stored water is subject to long residence times, allowing the appearance of some important chemical and biological reactions. These reactions, associated with some sewage releases, that come from urban, industrial, and rural areas, promote the accelerating the process of aging of the reservoirs, known as Eutrophication Process, that depends, fundamentally, of the presence of nutrients inside the reservoirs. This work studied, through field data, associated with a methodology of calculation of Modified Trophic State Index and the Water Quality Index, the environmental conditions of the Acarape do Meio Reservoir, in the State of CearÃ, trying to identificaty the main transformations in their trophic levels, as well as, the identification of the main causes of a possible process of eutrophization of it. The data cover the years 2001 through 2006. With that, it was possible to know the characteristics concerning with the stratification this body of water, with respect to temperature and the chemical process. Also, considering the several points of collections of data, it was possible to present results concerning with the Trophic State Index and the Water Quality Index, a long of the all surface of the reservoir, showing, like this, the several critical points of it. With respect to the Trophic Level Index, two calculations were used, being for the first used, just, the chlorophyll a and the phosphors, while in the second calculation they were used, besides those two substances, the present soluble orthophosphate in those waters. The results show that there is a strong variability of the quality of the waters of this reservoir, but that, in the years of 2004 and 2005, their waters reached a hipereutrophic level, that represents the presence of a fort presence of nutrients coming of the entrances of the reservoir and, probably, of the rural areas that exist around the it. The results showed yet, even if the vertical variation of temperature is not so significant inside the reservoir, there is a strong presence of chemical stratification in the deepest layers of this body of water.

Genetically modified (GM) maize was developed mainly to control lepidopteran pests such as the maize stem borer (Busseola fusca) (Lepidoptera: Noctuidae). Since the first commercialization of GM crops with insecticidal properties, possible non-target effects such as the effect at the third trophic level on important predators for example lacewing species (Chrysoperla spp.) have been of concern. Contradicting results were reported in previous studies with regard to the effect of Cry 1Ab protein produced by Bt maize on the performance of lacewings. Some studies found that Bt proteins had no effect while others reported that C. carnea performed poorly if they consumed prey that consumed Cry 1Ab protein. In South Africa one of the most common chrysopid species in maize ecosystems is Chrysoperla pudica (Navás) (Neuroptera: Chrysopidae). Evolution of Bt resistant pests, such as B. fusca in South Africa facilitates a new pathway for exposure of predators to healthy prey that consumes Cry 1Ab proteins. The aims of this study was to determine the effect of the Cry 1Ab protein expressed in Bt maize on a non-target organism‟s (C. pudica) biology via indirect exposure, and to determine the concentration of Cry 1Ab protein in the plant, prey and predator. Chrysoperla pudica larvae were indirectly exposed to the Bt-toxin through healthy Bt-maize feeding prey (B. fusca larvae) in two feeding experiments and lacewing survival and life history parameters recorded. Bt had a limited effect on some parameters that were evaluated. The larval and pupal periods of C. pudica larvae that were exposed to the Bt-toxin had a significant difference from that of the control treatment. The Bt-toxin had a significant effect on fecundity, fertility and malformation after emergence of C. pudica adults of which larvae fed only on Bt resistant B. fusca larvae, but not on the mortality rate. Cry 1Ab concentration was the highest in the plant, followed by the prey and lacewing larvae. This study showed that the Cry 1Ab protein had a slight adverse effect only on certain life parameters of C. pudica, and that Cry 1Ab protein was hardly detectable in C. pudica larvae. However, since this study represented a worst-case scenario where diverse prey was not available, insignificant effects is expected under field conditions where prey is diverse. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

<p>This thesis is a summary of enclosure and microcosm experiments that aimed to study the impact of allochtonous subsidies on food web dynamics in a heterogeneous food web. In the enclosure studies, a three trophic level littoral food web was used. The food web consisted of two growth forms of primary producers: phytoplankton and periphyton and their associated herbivores: scraping and filtering herbivores. The predator used, YOY perch, affects both pathways in the food web. Manipulation of the openness for the different trophic levels showed that the inflow of phytoplankton and cross-habitat foraging by the herbivore level reinforced the compensatory response between the two growth forms of primary producers </p><p>In the microcosm experiment, the response of an herbivore food web and a microbial community to inflow of resources and food web configuration was studied, using a model food web. The model food web consisted of two forms of primary producers, i.e. phytoplankton and periphyton, and two herbivores, i.e. <i>Daphnia pulex</i> feeding on phytoplankton, and <i>Chydorus sphaericus</i> feeding on both periphyton and phytoplankton. Three different food web configurations, all having the phytoplankton and periphyton, but either one of the herbivores, or both, were set up. The flow regimes consisted of an open treatment receiving a constant supply of phytoplankton, and a closed treatment with an initial resource pool. The effect of the inflow of phytoplankton was affected by the food web configuration. In the presence of <i>D. pulex</i>, the inflow of phytoplankton was made accessible to periphyton, and indirectly to <i>C. sphaericus</i>, which increased to such high densities that <i>D. pulex</i> was negatively affected. The inflow of phytoplankton had an indirect negative effect on the microbial community, since the biomass of herbivores increased, which imposed a higher grazing pressure on all parts of the microbial community.</p>

This thesis is a summary of enclosure and microcosm experiments that aimed to study the impact of allochtonous subsidies on food web dynamics in a heterogeneous food web. In the enclosure studies, a three trophic level littoral food web was used. The food web consisted of two growth forms of primary producers: phytoplankton and periphyton and their associated herbivores: scraping and filtering herbivores. The predator used, YOY perch, affects both pathways in the food web. Manipulation of the openness for the different trophic levels showed that the inflow of phytoplankton and cross-habitat foraging by the herbivore level reinforced the compensatory response between the two growth forms of primary producers In the microcosm experiment, the response of an herbivore food web and a microbial community to inflow of resources and food web configuration was studied, using a model food web. The model food web consisted of two forms of primary producers, i.e. phytoplankton and periphyton, and two herbivores, i.e. Daphnia pulex feeding on phytoplankton, and Chydorus sphaericus feeding on both periphyton and phytoplankton. Three different food web configurations, all having the phytoplankton and periphyton, but either one of the herbivores, or both, were set up. The flow regimes consisted of an open treatment receiving a constant supply of phytoplankton, and a closed treatment with an initial resource pool. The effect of the inflow of phytoplankton was affected by the food web configuration. In the presence of D. pulex, the inflow of phytoplankton was made accessible to periphyton, and indirectly to C. sphaericus, which increased to such high densities that D. pulex was negatively affected. The inflow of phytoplankton had an indirect negative effect on the microbial community, since the biomass of herbivores increased, which imposed a higher grazing pressure on all parts of the microbial community.