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Orientador: Paulo de Tarso da Cunha Chaves Tese (doutorado) - Universidade Federal do Paraná, Setor de Ciencias Biológicas, Programa de Pós-Graduaçao em Ciencias Biológicas - Zoologia. Defesa: Curitiba, 22/06/2006. Inclui bibliografia Área de concentraçăo: Zoologia

A year-long beach seine survey at the continental margin of Sepetiba Bay, Rio de Janeiro State, Brazil, catching mainly young-of-the-year and juvenile fishes was carried out from July 1983 to June 1984, in order to describe the community structure and their spatial and seasonal variations. Fifty-five monthly samplied carried out in five sites in the marginal surf zone waters yielded 11,463 fishes in 82 species, 59 genera and 31 families. Gerreidae, Engraulidi-dae, Atherinidae and Ariidae families amounted 87.01% of the total catch in number, and 81% in weight. Cerres aprion Cuvier, 1829, Anchoa januaria (Steindachner, 1879), Anchoviella lepidentostole (Fowler, 1911), Atherinella brasiliensis (Quoy & Gaimard, 1824) and Neluma barba (Lacépède, 1803) were the most numerous species, each one contributing more the 4% of total catch. Overall, both spatial and seasonal changes in fish were not evident although most individuais were more abundant in the outer Bay. The high number of fish species in this area, suggest the important role played by the Sepetiba Bay in the fish community to where many species probably migrate from the nearby sea and stay in the Bay during part of their life cycle. Decreasing diversity and high dominance of a few number of species seem to indicated a trend of environmental deterioration in the Sepetiba Bay over the last decade, as this date are compared whith similar sampling program carried out in 1993/94. It same to indicated that changes in fish populations which use this area as rearing grounds, occurred during their early life history.

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2020-05-12T00:47:59Z No. of bitstreams: 1 2012 - Rafael Jardim Albieri.pdf: 4422321 bytes, checksum: cc18a7e71ddf0662cebcdf8902d7d05b (MD5) Made available in DSpace on 2020-05-12T00:48:01Z (GMT). No. of bitstreams: 1 2012 - Rafael Jardim Albieri.pdf: 4422321 bytes, checksum: cc18a7e71ddf0662cebcdf8902d7d05b (MD5) Previous issue date: 2012-08-23 CNPq - Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico Influences of three types of dams on fish community structure along a river from Southeastern Brazil were investigated. Comparison of fish assemblages between above- and below-dam habitats was studied in order to detect possible differences in fish community between these habitats in two seasons (wet and dry). The three types of dams and associated fishways used as models were: (i) total blockage, (ii) partial blockage/side channel and (iii) total blockage with fish ladder. The tested hypothesis was that there are differences in fish assemblage composition between above- and below-dams habitats. We expected an impacted fish assemblage with the highest differences in fish fauna between up and downriver habitats in (i), intermediate in (iii) and less evident in (ii). Additionally, secondary investigations were made using models separately. When we investigated (ii) partial blockage, an impoundment with permanent hydrologic connection and environmental homogeneity between patches, we found that these attributes were not able to avoid the negative impact of river fragmentation on fish assemblage. The above- and below-dam had different fish assemblage composition and structure. Migratory fish species such as Pimelodus maculatus, Pimelodus fur and Prochilodus lineatus were the most affected, and probably are prevented to perform upriver migrations. On the other hand, only adapted species such as Hoplias malabaricus and Hoplosternum littorale successfully colonized the reservoir (above-dam). Therefore, for this investigation, we conclude that the presence of a hydrologic connectivity alone certainly does not guarantee an ecological connectivity and, consequently, fish passage facilities should be monitored and managed to evaluate and improve their functionality and efficiency. Another research was made in (i) total blockage to evaluate the possible impacts of this impoundment, considering two contrasting environmental conditions: wet/summer and dry/winter seasons. A major shift in biotic and abiotic parameters occurred due to contrast between above- and below-dams habitats. The comparatively high habitat complexity and water flow regime of the below-dam downriver zone favored a richer and abundant fish assemblage, especially in the wet season. In this period, the waters cover part of the riparian vegetation, increasing habitat availability and nutrient input. Additionally, the obstruction of upriver migrations of reophilics, mainly in wet season, such as Leporinus copelandii, Pimelodus fur, Pimelodus maculatus and Prochilodus lineatus increases shoals below dams. Although the reservoir represents a simplified ecosystem, highly influenced by non-native top predator species (Cichla kelberi and Plagioscion squamosissimus), cyclic processes (e.g. water level fluctuations and flood pulses) seems to be involved in the structuring of fish assemblages. The five selected environmental variables, although highly influenced by the impoundment, explained 55% of spatio-temporal patterns, defined mainly by turbidity (downriver) temperature, and dissolved oxygen (reservoir). Visual-predators fishes, seasonal changes and eutrophication process were linked to these variables, respectively. Finally, our main hypothesis was accepted but our expectations were not fully matched. Differences of fish assemblage between above- and below-dams habitats were highest in (i) total x blockage. However, partial blockage/side channel (ii) showed higher differences in fish fauna than (iii) total blockage with fish ladder, mainly in wet season, when flood triggers biological features (e.g. dispersal movements and reproductive migration) in Neotropical freshwater fish. Moreover, species richness was higher in downriver habitats, as an effect of habitat heterogeneity and fish concentration down the dams because impairment of migration. We provide information that may contribute to management programs and future projects as well as enhance freshwater ecology data base. Foi investigada a influ?ncia de tr?s tipos de barragens sobre a estrutura da comunidade de peixes ao longo de um rio no Sudeste do Brasil. Foram estudadas compara??es da assembleia de peixes entre habitats a montante e a jusante de barragens para detectar poss?veis diferen?as da comunidade de peixes entre estes dois habitat em duas esta??es do ano (chuvosa e seca). Os tr?s tipos de barragens e passagens de peixes associadas usadas como modelo foram: (i) barramento total, (ii) barramento parcial/ canal lateral e (iii) barramento total com escada de peixes. A hip?tese testada foi que existem diferen?as na composi??o das comunidades de peixes entre os habitats l?nticos acima das barragens (reservat?rios) e seus respectivos trechos de rio (l?tico) a jusante da barragem. Esperou-se uma assembleia de peixes impactada com as maiores diferen?as na ictiofauna entre habitats a montante e a jusante em (i), diferen?as intermedi?rias em (iii) e diferen?as menos evidentes em (ii). Adicionalmente, investiga??es secund?rias foram feitas, contudo utilizando os modelos de estudo separadamente. Quando investigado (ii) o barramento parcial, um barramento com conex?o hidrol?gica permanente e homogeneidade ambiental entre fragmentos, descobriu-se que estes atributos n?o foram capazes de evitar o impacto negativo da fragmenta??o sobre assembleias de peixes do rio. O reservat?rio e o rio a jusante apresentaram diferentes estrutura e composi??o da assembleia. Esp?cies de peixes migrat?rios, como Pimelodus maculatus, Pimelodus fur e Prochilodus lineatus foram os mais afetados, e, provavelmente, s?o impedidos de realizar migra??es rio acima. Por outro lado, apenas esp?cies adaptadas tais como Hoplias malabaricus e Hoplosternum littorale obtiveram sucesso na coloniza??o do reservat?rio. Portanto, conclu?-se que a presen?a de somente a conectividade hidrol?gica, certamente n?o garante a conectividade ecol?gica e, consequentemente, estruturas de passagem de peixes devem ser monitoradas e manejadas para avaliar e melhorar a sua funcionalidade e efici?ncia. Outra pesquisa foi feita no (i) barramento total para avaliar os poss?veis impactos deste represamento, considerando duas condi??es ambientais contrastantes: esta??es chuvosa/ver?o e seca/inverno. Uma mudan?a nos par?metros bi?ticos e abi?ticos ocorreu devido ao contraste entre o reservat?rio e a zona a jusante. A complexidade do habitat relativamente alta e o regime de fluxo de ?gua a jusante favoreceu uma assembleia de peixes mais rica e abund?nte, especialmente na esta??o chuvosa. Neste per?odo, as ?guas cobrem parte da vegeta??o ciliar, aumentando a disponibilidade de habitat e aporte de nutrientes. Al?m disso, a obstru??o das migra??es de peixes rio acima, principalmente na esta??o chuvosa, como Leporinus copelandii, Pimelodus fur, Pimelodus maculatus e Prochilodus lineatus aumentam a concentra??o de cardumes a jusante da barragem. Embora o reservat?rio represente um ecossistema simplificado, altamente influenciado por esp?cies n?onativas predadoras de topo (Cichla kelberi e Plagioscion squamosissimus), processos c?clicos (e. g., flutua??es do n?vel da ?gua e pulsos de inunda??o) parecem estar envolvidos na estrutura??o das assembleias de peixes. As cinco vari?veis ambientais selecionadas explicaram 55% dos padr?es espa?o-temporais, definido principalmente viii pela turbidez (a jusante), temperatura e oxig?nio dissolvido (no reservat?rio). Peixes predadores visuais, mudan?as sazonais e processo de eutrofiza??o foram relacionados a estas vari?veis, respectivamente. Finalmente, a hip?tese principal do estudo foi aceita, mas as expectativas n?o foram totalmente corroboradas. Diferen?as nas assembleia de peixes entre habitats a montante e a jusante foram maiores no (i) bloqueio total. No entanto, o (ii) bloqueio parcial/canal lateral apresentou diferen?as maiores na fauna de peixes do que o (iii) bloqueio total, com escada de peixes, principalmente na esta??o chuvosa, quando cheias funcionam como gatilho para diversas fun??es biol?gicas (e.g. movimentos de dispers?o e migra??o reprodutiva) em peixes de ?gua doce Neotropicais. Adicionalmente, a riqueza de esp?cies foi maior em habitats a jusante, como um efeito da heterogeneidade de habitats e de concentra??o de peixes abaixo das barragens devido ao bloqueio da migra??o. Neste estudo, foram fornecidas informa??es que podem contribuir para os programas de gest?o e projetos futuros, bem como o melhoramento da base de dados da ecologia de ambientes aqu?ticos continentais.