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Previous issue date: 2006-05-05 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Species-environment relationships are important to assess the biological patterns, mainly those related to spatial distribution, since species undergo seletive pressure along their evolutive history, which determine the success in colonizing habitats. In fluvial ecosystems the geomorphology can acts as a constraint for fish species distribution, by determining kinds and levels of habitats structuring to which species are associated. This work aims to address the relationship between fluvial geomorphology and fish assemblages from Paraiba do Sul watershed, in an attempt to explaining the underlying spatial assemblages distribution patterns. Additionally, we assess the use of two river classification systems, developed for temperate regions, to this case study. Thirty-seven sites along the watershed were sampled during the dry season (May-October) between 2003 and 2005. The rivers were classified in three size categories: small (1?. to 3?. Order), medium (4?. to 6?. order) , and larger (> 6?. order), based in fluvial hierarchical classification scale. Fishes and geomorphological variables were sampled in a stretch of approximately 20 times the width for small and medium rivers, and in approximately 1 km for large rivers. Four fish assemblages were detected by cluster analysis and non-metric multidimensional scales MDS; one dominated by Tricomycterus immaculatum and Neoplecostomus microps, corresponding to small and medium rivers from hillslopes, straigths, with high slopes and channel showing bedrock, step-pool, and cascade. The second, dominated by Rhamdia quelen, Astyanax parahybae and Harttia loricariformis and the third, by Phalloceros caudimaculatus and Geophagus brasiliensis, corresponding to meandering rivers, with low and moderated slopes, channels showing pool-riffles, non-entrenchment, with channels associated to floodpains areas. The fourth assemblages is dominated by A. bimaculatus and Oligosarcus hepsetus, which are widely distributed along all watershed; in the lower reaches Loricariichthys spixii occurs in high frequency as well as eurihalines marine species, corresponding to low and medium sinuosity rivers with low slopes, channels showing pool-riffle, dune-ripple and braided, large cross-section, flooplains well developed and bed formed by gravel and sand. Slope, entrenchetment and width-depth ratio were the main constraints controlling the habitat. Our results match the main predictions of the Process Domain Concept (PDC) which postulate that fish assemblages vary in response to local habitat characteristics and the richness is directly associtated to cross-section area, contrasting with the prediction of the River Continuum Concept which postulate that assemblages vary previsible along the longitudinal gradient. / As rela??es esp?cie-ambiente s?o fundamentais para a compreens?o dos padr?es biol?gicos, principalmente aqueles relacionados ? distribui??o espacial, uma vez que as esp?cies sofrem press?es seletivas ao longo da hist?ria evolutiva que determinam seu sucesso na coloniza??o dos habitats. Em ecossistemas fluviais a geomorfologia pode atuar como uma condicionante da distribui??o das assembl?ias de peixes, por determinar os tipos e os n?veis de estrutura??o de habitat aos quais as esp?cies est?o associadas. Esse trabalho teve como objetivo analisar as rela??es entre a geomorfologia fluvial e as assembl?ias de peixes da bacia do rio Para?ba do Sul, na tentativa de explicar os padr?es de distribui??o. Foram amostrados 37 s?tios ao longo da bacia, no per?odo seco (maio-outubro) entre 2003 e 2005. Os rios foram estratificados em tr?s categorias de tamanho: pequeno (1?. a 3?. Ordem), m?dio (4?. a 6?. ordem) , e grande (> 6?. ordem), baseado na hierarquia fluvial. Os peixes e as vari?veis geomorfol?gicas foram amostrados num trecho cerca de 20 vezes a largura nos rios pequenos e m?dios, e num trecho de aproximadamente 1 km nos grandes rios. Quatro assembl?ias de peixes foram detectadas pelas an?lises de agrupamento e escalonamento multidimensional n?o m?trico MDS, uma dominada por Tricomycterus immaculatum, Neoplecostomus microps, e Harttia loricariformis, correspondendo a rios pequenos e m?dios das escarpas dos planaltos, retil?neos, com elevados gradientes de inclina??o do leito (slope), canais tipo bedrock, step-pool, e cascade. A segunda e a terceira assembl?ias s?o dominadas tanto por Astyanax scabripinnis e, Astyanax intermedium, quanto por esp?cies de ampla distribui??o como Rhamdia quelem, Geophagus brasiliensis, Oligosarcus hepsetus, correspondendo a rios sinuosos, com baixos a moderados gradientes, canais do tipo pool-riffles, n?o entalhados, com forma??o de plan?cies de inunda??o. A quarta assembl?ia ? dominada por A. bimaculatus, A. paraybae, G. brasiliensis, O. hepsetus, Pimelodus maculatus, Hypostomus affinis, Hoplosternum littorale, as quais s?o amplamente distribu?das ao longo da bacia, por?m, nas por??es inferiores da bacia as assembl?ias tamb?m apresenta Loricariichthys spixii e esp?cies marinhas eurialinas, correspondendo a rios com m?dia a baixa sinuosidade, baixos a moderados gradientes, canais tipo me?ndrico (pool-riffle), dunas e ondula??es (dune-ripple) e Anastomosado (braided), grande ?rea da se??o transversal, plan?cies de inunda??o bem desenvolvidas e leito formado basicamente por areia e cascalho. O gradiente e as raz?es de Entalhamento e Largura-Profundidade mostraram-se fatores dominantes controlando o habitat. Nossos resultados corroboram as principais predi??es do Conceito dos Dom?nios de Processos (PDC) que postula que as assembl?ias de peixes variam em fun??o das caracter?sticas de h?bitat locais e que a riqueza ? diretamente proporcional ? ?rea da se??o transversal, contrastando com as predi??es do Conceito do Rio Cont?nuo (RCC) que postula que as assembl?ias variam previsivelmente ao longo de um gradiente longitudinal.
| Identifer | oai:union.ndltd.org:IBICT/oai:localhost:tede/474 |
| Date | 05 May 2006 |
| Creators | Estiliano, Eduardo Oliveira |
| Contributors | Ara?jo, Francisco Gerson |
| Publisher | Universidade Federal Rural do Rio de Janeiro, Curso de P?s-Gradua??o em Ci?ncias Ambientais e Florestais, UFRRJ, Brasil, Ci?ncias Agr?rias |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da UFRRJ, instname:Universidade Federal Rural do Rio de Janeiro, instacron:UFRRJ |
| Rights | info:eu-repo/semantics/openAccess |
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