Título :	Impactos de pequenas barragens sobre a comunidade de peixes na Amazônia
Autor :	Vasconcelos, Amanda Santos
Orientador(es)::	Dias, Murilo Sversut
Assunto::	Barragens e açudes Peixe tropical Estradas Desmatamento - Amazônia
Fecha de publicación :	10-dic-2024
Data de defesa::	28-jun-2024
Citación :	VASCONCELOS, Amanda Santos. Impactos de pequenas barragens sobre a comunidade de peixes na Amazônia. 2024. 45 f., il. Dissertação (Mestrado em Ecologia) — Universidade de Brasília, Brasília, 2024.
Abstract:	Aquatic ecosystem fragmentation by small dams and road crossings poses a significant threat to the biodiversity of lotic environments, such as streams. These structures have an underestimated and understudied impact due to their small size. In Brazil, especially in Mato Grosso, where road networks exacerbate the problem, many unauthorized and undocumented constructions contribute to the fragmentation of water bodies and habitat degradation. Understanding the effects of these barriers on streams and fish biodiversity is crucial, especially in regions like the Amazon, with vast road networks posing significant environmental threats. The present study investigated the effect of these small structures on streams in the Upper Xingu, Brazil, focusing on assessing environmental changes and the impacts of isolation caused by barriers on fish communities. Additionally, we tested the effect of barrier attributes on the environment and fish fauna. Sampling was conducted in pairs, with each stream sampled twice, upstream and downstream, allowing for comparisons. The studied dams were predominantly small, less than 6 meters in height, built between the late 1980s and throughout the 1990s. Environmental differences between treatments were analyzed using Principal Component Analysis (PCA) and Permutational Multivariate Analysis of Variance (perMANOVA). Mixed linear models were used to identify significant differences in environmental variables between treatments. Total abundance, richness, and species composition of fish were analyzed using mixed-effects linear models, perMANOVA, and represented by Non-metric Multidimensional Scaling (NMDS). Indicator Species Analysis (ISA) was employed to identify species associated with specific treatments, and the effects of dam characteristics (height and age) on environmental dissimilarity and fish community were tested using simple linear models. Significant differences were observed between free-flowing (unbarred) streams and disconnected (barred) streams. The analyses showed marked environmental variation in conductivity, dissolved oxygen, and pH parameters among the analyzed stretches. The fish fauna appears not to be significantly affected by the barriers, with total abundance, richness and species composition based on abundance data being similar between analyzed treatments. However, species composition based on presence/absence data differed significantly, with some species associated with specific locations above or below the barriers. Surprisingly, no effects of barrier characteristics on habitat and fish fauna dissimilarity were found. Our study shows that barriers cause subtle changes in water quality and composition above and below the barriers, but there is no evidence of drastic habitat alterations or local extirpation of species above or below the barriers. Overall, the study provided insights into the impacts of small barriers on stream environments and fish communities, highlighting the importance of considering both environmental and ecological factors in freshwater conservation efforts.
metadata.dc.description.unidade:	Instituto de Ciências Biológicas (IB)
Descripción :	Dissertação (mestrado) — Universidade de Brasília, Instituto de Ciências Biológicas, Programa de Pós-Graduação em Ecologia, 2024.
metadata.dc.description.ppg:	Programa de Pós-Graduação em Ecologia
Licença::	A concessão da licença deste item refere-se ao termo de autorização impresso assinado pelo autor com as seguintes condições: Na qualidade de titular dos direitos de autor da publicação, autorizo a Universidade de Brasília e o IBICT a disponibilizar por meio dos sites www.unb.br, www.ibict.br, www.ndltd.org sem ressarcimento dos direitos autorais, de acordo com a Lei nº 9610/98, o texto integral da obra supracitada, conforme permissões assinaladas, para fins de leitura, impressão e/ou download, a título de divulgação da produção científica brasileira, a partir desta data.
Agência financiadora:	Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).
Aparece en las colecciones:	Teses, dissertações e produtos pós-doutorado

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