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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Distribui??o e uso de habitat por peixes recifais em um gradiente ambiental: estudo de caso em recifes aren?ticos

Souza, Thaisa Accioly de 03 July 2015 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-10T23:18:29Z No. of bitstreams: 1 ThaisaAcciolyDeSouza_DISSERT.pdf: 2566489 bytes, checksum: ab1d23c69d224285b34d2fe13e74e6fa (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-05-18T20:17:17Z (GMT) No. of bitstreams: 1 ThaisaAcciolyDeSouza_DISSERT.pdf: 2566489 bytes, checksum: ab1d23c69d224285b34d2fe13e74e6fa (MD5) / Made available in DSpace on 2016-05-18T20:17:17Z (GMT). No. of bitstreams: 1 ThaisaAcciolyDeSouza_DISSERT.pdf: 2566489 bytes, checksum: ab1d23c69d224285b34d2fe13e74e6fa (MD5) Previous issue date: 2015-07-03 / H? diversos fatores abi?ticos relatados na literatura como reguladores da distribui??o das esp?cies de peixes em ambientes marinhos. Dentre eles, destacam-se complexidade estrutural do h?bitat, composi??o bent?nica, profundidade e dist?ncia da costa, comumente relatadas como influenciadores positivos na diversidade de diferentes esp?cies, incluindo os peixes recifais. Estes s?o elementos dominantes em sistemas recifais e considerados de elevada import?ncia ecol?gica e socioecon?mica. A compreens?o de como os fatores supracitados influenciam na distribui??o e uso de habitat das comunidades de peixes recifais tornam-se importantes para seu manejo e conserva??o. Assim, o presente trabalho pretende avaliar a influencia destas vari?veis sobre a comunidade de peixes recifais ao longo de um gradiente ambiental de profundidade e distancia da costa em recifes de base aren?tica na costa do Rio Grande do Norte. Tais vari?veis tamb?m ser?o utilizadas para a cria??o de um modelo preditivo simples da biomassa de peixes recifais para o ambiente estudado. A coleta de dados foi realizada por meio de censos visuais in situ, sendo registrados dados ambientais (complexidade estrutural do h?bitat, tipo de cobertura do substrato, megafauna de invertebrados bent?nicos) e ecol?gicos (riqueza, abundancia e classes de tamanho dos peixes recifais). Como complemento, informa??es sobre a dieta foram levantadas atrav?s de literatura e a biomassa foi estimada a partir da rela??o peso-comprimento de cada esp?cie. No geral, os recifes apresentaram uma baixa cobertura por corais, sendo os recifes Rasos, Intermedi?rios I e II dominados por algas e os Fundos por algas e esponjas. A complexidade aumentou ao longo do gradiente e influenciou positivamente na riqueza e abundancia de esp?cies. Ambos atributos influenciaram a estrutura??o da comunidade de peixes recifais, incrementando a riqueza, abundancia e biomassa dos peixes, bem como diferenciando a estrutura??o tr?fica da comunidade ao longo do gradiente de profundidade e distancia da costa. A distribui??o e utiliza??o do h?bitat pelos peixes recifas foi associada a disponibilidade de alimentos. O modelo preditor identificou a profundidade, rugosidade e a cobertura por algas folhosas, algas calc?rias e corais moles como as vari?veis mais significativas influenciando a biomassa de peixes recifais. Em suma, a descri??o e o entendimento destes padr?es s?o passos importantes para elucida??o dos processos ecol?gicos. Neste sentido, nossa abordagem fornece um novo entendimento da estrutura??o da comunidade de peixes recifais do Rio Grande do Norte, permitindo entender uma parte de um todo e auxiliar futuras a??es de monitoramento, avalia??es, manejo e conserva??o destes e outros recifes do Brasil. / There are several abiotic factors reported in the literature as regulators of the distribution of fish species in marine environments. Among them stand out structural complexity of habitat, benthic composition, depth and distance from the coast are usually reported as positive influencers in the diversity of difentes species, including reef fish. These are dominant elements in reef systems and considered high ecological and socioeconomic importance. Understanding how the above factors influence the distribution and habitat use of reef fish communities are important for their management and conservation. Thus, this study aims to evaluate the influence of these variables on the community of reef fishes along an environmental gradient of depth and distance from shore base in sandstone reefs in the coast of state of Rio Grande do Norte, Brazil. These variables are also used for creating a simple predictive model reef fish biomass for the environment studied. Data collection was performed through visual surveys in situ, and recorded environmental data (structural complexity of habitat, type of coverage of the substrate, benthic invertebrates) and ecological (wealth, abundance and reef fish size classes). As a complement, information on the diet were raised through literature and the biomass was estimated from the length-weight relationship of each species. Overall, the reefs showed a low coverage by corals and the Shallow reefs, Intermediate I and II dominated by algae and the Funds by algae and sponges. The complexity has increased along the gradient and positively influenced the species richness and abundance. Both attributes influenced in the structure of the reef fish community, increasing the richness, abundance and biomass of fish as well as differentiating the trophic structure of the community along the depth gradient and distance from the coast. Distribution and use of habitat by recifas fish was associated with food availability. The predictor model identified depth, roughness and coverage for foliose algae, calcareous algae and soft corals as the most significant variables influencing in the biomass of reef fish. In short, the description and understanding of these patterns are important steps to elucidate the ecological processes. In this sense, our approach provides a new understanding of the structure of the reef fish community of Rio Grande do Norte, allowing understand a part of a whole and assist future monitoring actions, evaluation, management and conservation of these and other reefs of Brazil.

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