Streams are important habitats, providing shelter and feeding opportunities for a wide range of organisms. The species depending on running waters includes a wide array of fish species, using these waters for their whole or parts of their lifecycle. Streams are also the subject of different anthropogenic impact, e.g. hydropower development. Hydropower development usually means lost connectivity, altered flow regimes and channelization. Channelization is one of the major factors causing stream habitat loss and degradation and thereby a threat to biodiversity of running waters. In the present study, the ecological impact of channelization on the fish fauna along a gradient of channelization severeness was examined. Besides channelization, stream velocity and depth were taken in to account. The study was carried out in two adjacent nemoboreal streams, Gavleån and Testeboån. The study was conducted between the 6th of June and the 10th of October 2012 at 15 sites. Sites were selected using historical maps and field observations and graded 0-3 depending on the degree of channelization. Fish community were sampled with, Nordic multi-mesh Stream Survey Net (NSSN). In all, 1.465 fish were captured, representing 15 species and seven families. The sites differed in species richness, abundance and proportion of individuals. Based on the results from rarefaction curves and ANOVA, channelization was found to be the main factor affecting the fish biota, both in abundance as well as species richness and composition. In general the rheophilic species declined along the gradient of increasing channelization severeness, while limnophilic species increased

Coral reefs have one of the highest levels of biodiversity of all ecosystems in the world and are important for both human livelihood and food security throughout many tropical countries. However, due to increased anthropogenic pressure on marine ecosystems, especially during the last couple of decades, coral reefs have become critically over-fished, and many reefs are now in a degraded state and are facing additional future threats due to further over-exploitation, chemical pollution, sedimentation, and effects of climate change. The main aim of this PhD thesis was to understand effects of anthropogenic disturbances on tropical coastal ecosystems and fish connectivity for coastal management purposes. Therefore, linkages between anthropogenic disturbance and corals were investigated (Paper I), as well as interactions between coral reef habitat and associated fish assemblage (Paper II). Furthermore, connectivity between coral reefs and other tropical coastal ecosystems was explored (Paper III), as well as fish migration to reproduction sites (Paper IV), and evaluations of spatial ecology methods (Paper V). The result showed that coral reefs that are already exposed to disturbances, such as freshwater and nutrient run-offs, may be more sensitive to climate change, in terms of increased sea surface temperatures (Paper I). In addition, there were also clear linkages between coral reef quality, in terms of coral coverage, and fish assemblages, which displayed high spatial variability and suggesting patchy recovery after the 1997/1998 bleaching and subsequent coral mass mortality event (Paper II). This highlights the importance of understanding effects of disturbances on corals, especially in terms of synergistic effects between increased water temperatures and other coastal stressors such as decreased salinity and increased nutrients; and the indirect effects of habitat degradation on the fish community. Linkages between fish and different coastal habitats were further explored. The results showed that coral reefs were strongly connected with mangrove and seagrass beds, through ontogenetic migration of fish (Paper III). Migrations to spawning sites of groupers were related to lunar activities when thousands of fish gather for reproduction purposes during new moon, which increases the risk of over-exploitation (Paper IV). The results emphasises the importance of protecting key areas such as nursing grounds and reproduction sites. Furthermore, acoustic telemetry has become an increasingly common method in studies of fish movement, and the results showed that efficiency of acoustic arrays may increase depending on deployment strategies and habitat characteristics (Paper V). In conclusion, the results from this PhD thesis emphasises the importance of protecting coral reef habitats, as well as identifying related susceptible tropical coastal areas, such as nursing grounds and reproduction sites. Indeed, a better scientific understanding of coral reef ecology and indirect and direct effects on fish assemblages are needed for efficient and accurate coastal management decisions. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 5: Manuscript.</p>

Esta pesquisa foi desenvolvida nos reservatórios e tributários do trecho médio e baixo do rio Tietê, estado de São Paulo, com o objetivo de avaliar as modificações ocorridas na ictiofauna em decorrência dos represamentos, da introdução de espécies e a importância dos tributários para as espécies de peixes. Para atender aos objetivos propostos foram utilizados parâmetros usuais em estudos de estrutura de comunidade de peixes, bem como a determinação de variáveis limnológicas, análises de conteúdo estomacal e ecomorfologia. Ampliando a análise temporal (décadas), foram utilizadas pesquisas bibliográficas em período prévio aos represamentos, o que permitiu uma avaliação dos efeitos dos represamentos. A partir dos resultados obtidos constataram-se inúmeras alterações na composição da ictiofauna nos últimos anos e décadas, principalmente em relação à perda de espécies reofílicas e a introdução de espécies exóticas e alóctones. Atualmente os Characiformes são mais abundantes, com espécies adaptadas a ambientes lênticos, verificando-se uma redução da abundância de Siluriformes. Um gradiente de riqueza e diversidade de espécies foi observado nos reservatórios do rio Tietê, ocorrendo redução acentuada do reservatório de Barra Bonita ao de Três Irmãos. No entanto, não foram verificadas diferenças significativas entre os reservatórios e tributários quanto à riqueza e diversidade de espécies. Importante caracterização ecomorfológica e trófica foi realizada nas espécies de peixes dos reservatórios e tributários, permitindo uma avaliação mais ampla da ictiofauna. / This research was developed at reservoirs and tributaries from the medium and low Tietê river section, São Paulo state, aiming to evaluate the modifications occurred on the fish fauna due to the impoundment, introduction of species and environmental modifications layed on the reservoir as a result of its multiple uses. To attend the objectives proposed, usual parameters for fish community structures studies had been used, as well as limnological varieties determination, stomachal content analysisand ecomorphology. To amplify the temporal analysis (decades), bibliographic researchs about an anterior to the impoundments period were used, allowing to evaluate the effects of the impoundments. The results evidenced several alterations on the fish fauna composition in the last years and decades, mainly in relation to the loss of reophilic species and introduction of exotic and alóctone species. At this moment, the Characiphorms are more abundant, with species adaptated to lentic environment, and a reduction on the Siluriforms abundance was verified. A richness and diversity gradient of species had been observed at the Tietê reservoirs, ocurring a clear reduction from Barra Bonita to Três Irmãos reservoirs. However, no significative differences were verified between the reservoirs and tributaries for the species richness and diversity. Important ecomorphological and trophic characterization had been accomplished for the fish species from the reservoirs and tributaries, allowing a wide evaluation of the fish fauna.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-08-31T17:58:21Z No. of bitstreams: 1 2016 - Rafaela de Sousa Gomes.pdf: 1653692 bytes, checksum: 31b6b096a06b65f4844bd7dc42f042a8 (MD5) / Made available in DSpace on 2017-08-31T17:58:21Z (GMT). No. of bitstreams: 1 2016 - Rafaela de Sousa Gomes.pdf: 1653692 bytes, checksum: 31b6b096a06b65f4844bd7dc42f042a8 (MD5) Previous issue date: 2016-11-23 / CAPES / FAPERJ / Shallow coastal marine systems are highly productive and widely recognized by their roles as important habitats for several bottom dwelling or water column fish and invertebrate species. Several mechanisms can influence fish distribution among the coastal marine systems, such as biotic interaction (e.g. predation, competition) and abiotic influences (e.g. type of sediment, turbidity). This study was carried out in sandy beaches of coastal systems that included unsheltered oceanic beaches and sandy beaches in two large embayment (Sepetiba and Ilha Grande). Quarterly samplings were performed to collect fishes, sediment and to measure environmental variables in three sandy beaches of each system during 2014 and 2015. The aim were: 1) to determine and compare the relationship fish and benthic invertebrate among the three systems, and to detect eventual influences of environmental variables on the structure of these two biotic communities and, 2) to compare the ichthyofauna in relation to beta diversity, taxonomic distinctiveness and environmental heterogeneity, to test the hypothesis that systems with high environmental heterogeneity have higher beta diversity. Granulometric composition and environmental variables differed among the systems, with comparatively higher turbidity in the Sepetiba Bay, lower nutrient concentrations in the Ilha Grande Bay and higher salinity in the Oceanic Beaches. The highest abundance of benthic invertebrate was found in the bays, whereas the Oceanic Beaches have the lowest numbers, which can be associated to physical dynamic of wave action in the this latter system that can the potentiality to remove invertebrate from the sediments, resulting in their exposure to predation. Fish and benthic invertebrate were influenced by environmental variables but no significant correlation was found between fish and invertebrate communities. However, some specific strong relationship was found between particular species of fish and invertebrate. For example, the flatfish Citharichthys spilopterus was positively related to representant of the Crustacean from Amphipoda and Tanaidacea orders, and from Polychaeta of Opheliida and Polygordiida orders, suggesting a dependence relationship between fish and invertebrates that can be used as fish feeding prey. The coastal systems did not differ in environmental heterogeneity, whereas the beta diversity was highest in the Ilha Grande Bay, which is probably associated to better preservation of their beaches. We did not detect significant relationship between beta diversity and environmental heterogeneity, which can be attributed to the examined environmental variables that did not influence markedly fish distribution. Taxonomic distinctiveness had positive correlation with species richness, thus the higher the richness the higher the taxonomic distinctiveness that can be associated to interspecific relationship, since species closely related tend to compete for similar resources. Thus, the addition of new phylogenetically distant species will occupy different niches. We suggest that fish turnover (beta diversity) should be included in environmental management plans, as a tool to supply the basis to selection size of areas to be priorized for conservation, aiming to protect the maximum of biological diversity. / Ambientes marinhos costeiros rasos s?o altamente produtivos e amplamente reconhecidos como importantes habitats para muitas esp?cies de peixes e invertebrados associados ao substrato ou ? coluna da ?gua. Diversos mecanismos podem influenciar a distribui??o de peixes entre os sistemas costeiros marinhos, como intera??es biol?gicas (e.g., preda??o, competi??o) e abi?ticas (e.g., tipo de sedimento, turbidez). O presente trabalho foi realizado em sistemas costeiros na regi?o sul do estado do Rio de Janeiro, que incluem praias arenosas oce?nicas desprotegidas e praias arenosas dentro de dois grandes sistemas de ba?as (Sepetiba e Ilha Grande). Amostragens de peixes, sedimento e tomada de vari?veis ambientais foram realizadas trimestralmente em tr?s praias arenosas de cada sistema durante os anos de 2014 e 2015. Os objetivos foram: 1) determinar e comparar a rela??o entre peixes e invertebrados bent?nicos entre os tr?s sistemas costeiros, e detectar eventuais influ?ncias das vari?veis ambientais na estrutura destas duas comunidades bi?ticas; e 2) comparar a ictiofauna em rela??o ? diversidade beta, distin??o taxon?mica e heterogeneidade ambiental, visando testar a hip?tese de que ambientes com maior heterogeneidade ambiental apresentam maior diversidade beta. A composi??o granulom?trica e as vari?veis ambientais variaram significativamente entre os sistemas costeiros, com maior turbidez na Ba?a de Sepetiba, maior salinidade nas praias oce?nicas e menores concentra??es de nutrientes na Ba?a da Ilha Grande. A maior abund?ncia de invertebrados bent?nicos foi observada nas ba?as, com a Ba?a de Ilha Grande destacando-se pelo maior n?mero de indiv?duos, enquanto as praias oce?nicas apresentaram as menores ocorr?ncias, o que pode estar associado a fatores f?sicos, principalmente a a??o de ondas, que pode remover invertebrados do sedimento, acarretando numa maior exposi??o ? preda??o. As composi??es de peixes e invertebrados bent?nicos foram influenciadas pelas vari?veis ambientais e a comunidade de invertebrados bent?nicos n?o apresentou correla??o significativa com a ictiofauna, entretanto algumas correla??es pontuais consistentes foram observadas entre peixes e invertebrados. Por exemplo, o linguado Citharichthys spilopterus, foi positivamente correlacionado com representantes de Crustacea das ordens Amphipoda e Tanaid?cea e Polychaeta das ordens Opheliida e Polygordiida, o que sugere uma rela??o de depend?ncia destes peixes por estes invertebrados que podem estar sendo utilizados como recursos alimentares. Os sistemas costeiros n?o diferiram quanto ? heterogeneidade ambiental, enquanto a diversidade beta foi maior na Baia da Ilha Grande, o que pode estar associado ao estado de melhor preserva??o dos locais amostrados. N?o foi encontrada rela??o significativa entre a diversidade beta e a heterogeneidade ambiental, o que pode ser atribu?do ? escolha das vari?veis ambientais que n?o influenciam na distribui??o da ictiofauna. A distin??o taxon?mica apresentou correla??o positiva com a riqueza de esp?cies. Assim, quanto maior o n?mero de esp?cies, maior a distin??o taxon?mica e esse fato pode estar relacionado a intera??es interespec?ficas, j? que esp?cies proximamente relacionadas geralmente competem pelos mesmos recursos, assim a adi??o de novas esp?cies distanciadas filogeneticamente ocuparia diferentes nichos. Sugerimos que a rotatividade da ictiofauna (diversidade beta) deve ser considerada em planos de gerenciamento ambiental, j? que esta ferramenta pode fornecer bases para sele??o e delineamento de tamanhos de ?reas priorizadas para a conserva??o, visando proteger o m?ximo da diversidade biol?gica.

To assess the potential influence of coastal development on the quality of estuarine habitat for nekton, we characterized land use and the intensity of land development surrounding small tidal tributaries of Tampa Bay. Based on this characterization, we classified tributaries as undeveloped, industrial, urban or man-made (i.e., mosquito-control ditches). Over one-third (37%) of tributaries were determined to be heavily developed, while fewer than one-third (28%) remain relatively undeveloped. We then examined the nekton community from eleven tributaries in watersheds representing the defined land-use classes. Whereas mean nekton density and species richness were both independent of land use, nekton-community structure differed between non-urban (i.e., undeveloped, industrial, ditches) and urban tributaries. In urban tributaries, the community was skewed towards high densities of poeciliid fishes while typically dominant estuarine taxa were in low abundance or nearly absent. Densities of economically important taxa in urban creeks were also only half that observed in most non-urban creeks, but were similar to those observed in mosquito ditches. Furthermore, six of nine common taxa were found to be in relatively poor condition (6-22% smaller in mass), or were rarely collected, in urban creeks. Reproductive output was reduced for both sailfin mollies (i.e., fecundity) and grass shrimp (i.e., very low densities and few ovigerous females) in urban tributaries. Canonical correspondence analysis differentiated non-urban and urban tributaries based on greater impervious surface, less natural mangrove shoreline, higher frequency of hypoxia and lower, more variable salinities in urban tributaries. These characteristics explained 48% of the variation in nekton data, including the high densities of poeciliid fishes, greater energy reserves in sailfin mollies and low densities of several common nekton and economically important taxa from urban creeks. Our results suggest that urban development in coastal areas has the potential to alter the quality of habitat for nekton in small tidal tributaries as reflected by variation in nekton metrics between urban and non-urban tributaries. To further evaluate the link between coastal development fish-habitat quality, we examined the relationship between landscape development intensity (LDI) and the body condition of juvenile sailfin mollies (Poecilia latipinna), a dominant forage fish in tidal tributaries. Morphometric condition, measured as least-square mean dry weight, did not differ statistically among tributaries (P = 0.85). In contrast, biochemical condition, measured as the concentration of triacylglycerol (TAG), the predominant storage lipid, was significantly different among tributaries (P < 0.0001). LDI explained less of the observed variation in TAG content (R2 = 0.18, P = 0.11) than long-term mean salinity (R2 = 0.81, P < 0.0001), which also tended to be lower in more intensively developed watersheds. We hypothesized that urban land use, characterized by considerably greater impervious surface than undeveloped lands, contributed to altered watershed hydrology, high freshwater runoff and low salinities in urbanized creeks. Together these factors appear to foster conditions conducive to lower energetic cost of osmoregulation in urban creeks, and development of a benthic microalgal community of greater nutritional value than the food resources available in non-urban tributaries. To our knowledge, this is one of the first studies to relate urbanization to the condition of resident fishes. While not directly related to coastal urbanization, the level of predation risk within a habitat is a direct measure of habitat quality that could be reflected by the reproductive strategy of potential prey. To evaluate the use of reproductive metrics of fish-habitat quality, we examined reproduction in P. latipinna from eleven tidal tributaries. Our results revealed a gradient along which females produced many, small offspring at one extreme (mean=42 offspring, 17 mg each) and fewer, larger offspring at the other (24 offspring, 29 mg each). Reproductive allotment ranged from 14.9 - 21.5% maternal biomass. Based on our observation of divergent reproductive strategies, we experimentally tested the null hypothesis of no difference in predation risk among tributaries using a novel quantitative approach to estimate predation. We predicted greater risk in tributaries where mollies produced many, small offspring. Tethering confirmed increasing risk from 16.2 ± 5.3% SE to 54.7 ± 3.6% fish lost h-1 across sites in agreement with observed variation in reproduction. Predation was unexpectedly higher than predicted at one of the four sites suggesting that additional factors (e.g., food) had influenced reproduction there. Our results provide insight into the well-studied concept of predator-mediated variation in prey reproduction by quantitatively demonstrating differential risk for mollies exhibiting divergent reproductive strategies. While the observed range of variation in reproductive traits was consistent with previous studies reporting strong predator effects, higher than expected predation in one case may suggest that the prey response does not follow a continuous trajectory of incremental change with increasing predation risk, but may be better defined as a threshold beyond which a significant shift in reproductive strategy occurs.

This study compared traditional community analysis with stable-isotope trophic analysis to define process-based trophic elements of community structure in the eastern Gulf of Mexico, and developed a predictive capability regarding changes to fish community structure that would be expected from increasing eutrophication. Specifically, it used an existing trawl survey program (SEAMAP) to compare invertebrate herbivore (sponge and sea urchin) isotopes with groundfish isotopes, and then compared the resulting spatial patterns with spatial variation in community structure, as identified by cluster analysis. The comparison was applied to seven NMFS survey zones that extended offshore from the Caloosahatchee River, FL northwest to Mobile Bay, AL. Isotopic patterns were consistent with the presence of an oligotrophic-eutrophic spatial gradient in this region. δ15N values increased in the northwestward direction in herbivores and in each of the 17 fish species examined. In the southern NMFS survey zones, δ13C was elevated in shallow depths for individual fish species, but not in herbivores, indicating a higher proportion of benthically derived biomass contributed to the biomass of fish in the shallow parts of the southern NMFS zones. Fish community analysis using SIMPROF created a similar pattern, with distinct nearshore and offshore communities and also a northwesterly community transition. Among the 17 fish species, five appeared to have obligate dependence on either benthic or planktonic basal resources, while twelve species appeared to be have facultative relationships. Impairment of current water-quality (nutrients, turbidity, light transmission, chlorophyll a) is expected to lead to reductions in the abundance of both obligate and facultative benthic-dependent fishes.

No description available.

Made available in DSpace on 2014-06-11T19:35:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-04-19Bitstream added on 2014-06-13T20:07:23Z : No. of bitstreams: 1 rondineli_gr_dr_rcla.pdf: 2227830 bytes, checksum: 5627c287ce51efee9419433f5e5ef4bb (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / As microbacias do ribeirão dos Buenos e do rio Guaratinguetá, integrantes da bacia do rio Paraíba do Sul, são sistemas hidrográficos que descem das encostas da serra da Mantiqueira oriental, sendo isoladas de outros sistemas contíguos por formações de relevo. O objetivo deste trabalho foi definir como as comunidades de peixes das microbacias do ribeirão dos Buenos e do rio Guaratinguetá estão estruturadas e como variam suas composições no espaço e no tempo. Estudos sobre a biologia dessas populações foram conduzidos de modo a entender como ocorrem os processos de substituição de espécies. Para contemplar regiões da encosta, do pediplano e do vale foram demarcados 15 pontos de coleta, 8 deles na microbacia do ribeirão dos Buenos e 7 na do rio Guaratinguetá. As coletas aconteceram ao longo de um ano, sendo o aparelho de pesca elétrica, a redinha-de-arrasto e as redes-deespera os apetrechos de pesca utilizados. Variáveis estruturais dos riachos e físicas e químicas da água também foram coletadas. Foram capturados 2805 indivíduos, distribuídos em 34 espécies, 13 famílias e 7 ordens. Na microbacia do ribeirão dos Buenos, ocorreram 27 espécies, das quais 4 foram exclusivas de seus riachos e na microbacia do rio Guaratinguetá 30 espécies foram amostradas, sendo 8 delas também exclusivas de seus riachos. Um gradiente crescente da diversidade, riqueza e equitabilidade foi observado da encosta em direção ao vale. Interações significativas entre ambientes e microbacias para os índices de diversidade e riqueza indicaram que pelo menos um ambiente em uma microbacia diferiu quanto à diversidade e riqueza de espécies. Na dimensão temporal, nenhuma variação significativa nos índices de diversidade, riqueza e equitabilidade foi detectada. Um padrão de adição de espécies, indo da encosta em direção ao pediplano, pode ser observado nas microbacias estudadas... / The watersheds of Buenos and Guaratinguetá streams, integrants of the Paraíba do Sul river basin are systems that comes down the slopes of the serra da Mantiqueira eastern, being isolated from other systems by contiguous relief formations. The aim of this work was to determine how fish communities of the Buenos and Guaratinguetá watersheds are structured and how their composition varies in space and time. Studies on the biology of these populations were conducted in order to understand the processes as species replacement in time and space. In order to include regions of the slope, piedmont and the valley were marked 15 collection points, 8 of them in the Buenos watershed and 7 in the Guaratinguetá watershed. Sampling took place over a year, and the following fishery equipment was used: electric fishing equipment, gill nets and a sieve. Structural variables of streams and physical and chemical properties of water were also collected. We captured 2805 individuals belonging to 34 species, 13 families and 7 orders. In the Buenos watershed, there were 27 species and the Guaratinguetá watershed were captured 30 species. Four species were unique to streams of the Buenos watershed and 8 to streams of the Guaratinguetá watershed. An increasing gradient of diversity, richness and evenness was observed on the slope toward the valley. Significant interactions between environments and watersheds for the contents of richness and diversity indicated that at least one environment in a watershed differed as to the diversity and species richness. In the temporal dimension, no significant variation in diversity, richness and evenness was detected. A standard of species' addition, ranging from the hillside towards the piedmont can be observed in the watersheds studied, whereas from the piedmont to the valley, we noticed a pattern of species replacement. Among the structural variables and physical... (Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:35:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2004Bitstream added on 2014-06-13T20:26:47Z : No. of bitstreams: 1 suarez_yr_dr_rcla.pdf: 1415743 bytes, checksum: da926441413780941456f718c30f0694 (MD5) / Com o objetivo de descrever os principais padrões de organização das comunidades de peixes realizamos amostragens trimestrais em diferentes ambientes da bacia do rio Iguatemi. Os dados de abundância e ocorrência das espécies foram submetidos a métodos uni e multivariados procurando verificar a existência de um padrão longitudinal e sazonal para essas comunidades. Encontramos 72 espécies de peixes em toda a bacia, constatamos que existe variação longitudinal estatisticamente significativa na composição de espécies para os rios Jogui e Iguatemi, mas não existe variação sazonal. A diversidade de espécies não variou longitudinalmente no rio Iguatemi, mas sim no rio Jogui. As espécies apresentam um padrão determinístico de associação, com clara diferenciação ente espécies de riachos de cabeceira e de rios de maior volume. Existem diferenças significativas na composição de espécies entre os ambientes estudados. Contudo estas diferenças não foram relacionadas às características selecionadas dos ambientes estudados. / This paper aims to describe the main patterns of fish communities organization. Tree-monthly samples were realized in different environments of Iguatemi River basin. The abundance and occurrence of species were submitted to uni and multivariate statistical methods in order to verify the existence of a longitudinal and seasonal pattern in fish communities. Seventy two fish species were collected in all basin. We observed longitudinal differences in species composition for Jogui and Iguatemi Rivers. However we did not detect any seasonal variation. The species diversity did not show statistically significant longitudinal variation in Iguatemi River, contrary to Jogui River. Fish species presented a deterministic association pattern in both rivers, with a clear differentiation between headwaters and downstream. Albeit we detected a significant difference in species composition in the whole basin it is not correlated to selected environmental characteristics.

Esta pesquisa foi desenvolvida nos reservatórios e tributários do trecho médio e baixo do rio Tietê, estado de São Paulo, com o objetivo de avaliar as modificações ocorridas na ictiofauna em decorrência dos represamentos, da introdução de espécies e a importância dos tributários para as espécies de peixes. Para atender aos objetivos propostos foram utilizados parâmetros usuais em estudos de estrutura de comunidade de peixes, bem como a determinação de variáveis limnológicas, análises de conteúdo estomacal e ecomorfologia. Ampliando a análise temporal (décadas), foram utilizadas pesquisas bibliográficas em período prévio aos represamentos, o que permitiu uma avaliação dos efeitos dos represamentos. A partir dos resultados obtidos constataram-se inúmeras alterações na composição da ictiofauna nos últimos anos e décadas, principalmente em relação à perda de espécies reofílicas e a introdução de espécies exóticas e alóctones. Atualmente os Characiformes são mais abundantes, com espécies adaptadas a ambientes lênticos, verificando-se uma redução da abundância de Siluriformes. Um gradiente de riqueza e diversidade de espécies foi observado nos reservatórios do rio Tietê, ocorrendo redução acentuada do reservatório de Barra Bonita ao de Três Irmãos. No entanto, não foram verificadas diferenças significativas entre os reservatórios e tributários quanto à riqueza e diversidade de espécies. Importante caracterização ecomorfológica e trófica foi realizada nas espécies de peixes dos reservatórios e tributários, permitindo uma avaliação mais ampla da ictiofauna. / This research was developed at reservoirs and tributaries from the medium and low Tietê river section, São Paulo state, aiming to evaluate the modifications occurred on the fish fauna due to the impoundment, introduction of species and environmental modifications layed on the reservoir as a result of its multiple uses. To attend the objectives proposed, usual parameters for fish community structures studies had been used, as well as limnological varieties determination, stomachal content analysisand ecomorphology. To amplify the temporal analysis (decades), bibliographic researchs about an anterior to the impoundments period were used, allowing to evaluate the effects of the impoundments. The results evidenced several alterations on the fish fauna composition in the last years and decades, mainly in relation to the loss of reophilic species and introduction of exotic and alóctone species. At this moment, the Characiphorms are more abundant, with species adaptated to lentic environment, and a reduction on the Siluriforms abundance was verified. A richness and diversity gradient of species had been observed at the Tietê reservoirs, ocurring a clear reduction from Barra Bonita to Três Irmãos reservoirs. However, no significative differences were verified between the reservoirs and tributaries for the species richness and diversity. Important ecomorphological and trophic characterization had been accomplished for the fish species from the reservoirs and tributaries, allowing a wide evaluation of the fish fauna.