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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

Inventário ictiofaunístico de dois rios de altitude do planalto serrano catarinense, alto rio Uruguai, Brasil

Pereira, Karla Conceição 24 November 2008 (has links)
Made available in DSpace on 2016-06-02T19:29:13Z (GMT). No. of bitstreams: 1 2219.pdf: 2636359 bytes, checksum: f0645ac8007040cc7b64491af2575c03 (MD5) Previous issue date: 2008-11-24 / Universidade Federal de Sao Carlos / The fish presence and abundance in local assemblies are influenced by several biotic and non-biotic factors, which work and interact in different spatial and temporal scales (MATTHEWS, 1998). The present study aimed at performing the ichthyologic inventory in the headwaters of the rivers Caronas (Pelotas River basin) and Caveiras (Canoas River basin), sub-basins from the region of Santa Catarina State s Plateau, Alto Uruguai River basin, Brazil. The samplings took place monthly in two regions (lentic and lotic parts) during the period from February 2006 to January 2007, with a total of 48 samples. Nets varying from 2 to 7 cm in mesh size were disposed during 24 hours (starting from 12 pm) and were checked 3 times. Additionally were used hand line, catueiros , covos and tarrafas fishing devices. The samples were properly labeled and fixed in 10% formalin. A total of 162 specimens were caught, 72 from Caronas river (29 specimens in the lentic part and 43 in the lotic part) and 90 from Caveiras river (46 specimens in the lentic part and 44 in the lotic part), belonging to 9 species, 5 Families and 3 Orders. It was registered the occurrence of an exotic species Oncorhynchus mykiss (rainbow trout) in both rivers. Among the captured individuals, two species of Astyanax were constant on the studied habitats. According to the Jaccard qualitative Index application, it was recorded higher similarity values to the lentic parts from both rivers, although using the Bray-Curtis quantitative Index, it was shown that higher estimated values were seen among the lentic parts from both rivers and the lotic part from the Caveiras River. In general, both the qualitative and quantitative similarities presented relatively higher values, suggesting a great similarity in the ichthyofaunistic composition between the habitats in both rivers. Regarding biomass, similar values were registered to both rivers, corresponding to 6.222,64 g in Caronas River and 7.152,52 g in Caveiras River. The feeding items which presented higher frequencies of occurrence in the stomachs contents were: 22,8% of insects (aquatic stages), nematodes parts (14,3%) and terrestrials plants (13,1%), in Caronas River, and 24,4% of insects (aquatic stages), sand (12,7%), nematodes parts (11,7%), in Caveiras River. It was noticeable that the habitats were very alike in terms of specific richness and dominance. The species Rineloricaria sp, Pimelodus absconditus, Astyanax sp 1, Astyanax sp 2, Oligosarcus brevioris and Oncorhynchus mykiss had occurred in both habitats from both rivers; Hoplias malabaricus was not present only in the lotic part of Caveiras River; Rhamdia quelen was present in the lentic part from both rivers and Hypostomus isbrueckeri was restricted to the lotic part of Caronas River. Comparing the Kr values for the two species of Astyanax sp and analizing the distinct studied habitats, it was verified values upper 1,0 in the lentic part of Caveiras River. The results evidenced relatively low richness of species and low frequencies of occurrence on the ichthyofauna studied. It was also noticeable the predominance of the widely forager species Astyanax sp 1, and the presence of the exotic species rainbow trout in both rivers, which represents a risk to the native fish species at the same time that potentially threaten the fish diversity in those localities. / A presença e a abundância de peixes em assembléias locais são influenciadas por numerosos fatores bióticos e abióticos que funcionam e interagem em escalas espaciais e temporais diversas (MATTHEWS, 1998). O presente estudo teve por objetivo realizar o inventário ictiofaunístico nas cabeceiras de dois rios do planalto catarinense, bacia do alto rio Uruguai, Santa Catarina, Brasil. Nas amostragens mensais em dois ambientes (remanso e corredeira) dos rios Caronas (bacia do rio Pelotas) e Caveiras (bacia do rio Canoas), no período de fevereiro de 2006 a janeiro de 2007 (totalizando 48 coletas), foram utilizadas redes de espera com malhas variando de 2 a 7 cm entre nós adjacentes. As redes, expostas durante 24 horas, a partir das 12 horas nos dias de coleta, foram revisadas ao entardecer, ao amanhecer e no instante final de retirada da água. Complementaram-se as amostras com a utilização de linhas de mão, catueiros, covos e tarrafas. Todo material coletado foi etiquetado, fixado em formalina 10% e identificado. Foram capturados 162 exemplares, sendo 72 no rio Caronas (29 no remanso e 43 na corredeira) e 90 no rio Caveiras (46 no remanso e 44 na corredeira), distribuídos em 9 espécies, 5 Famílias e 3 Ordens. Registrou-se a ocorrência de uma espécie exótica, Oncorhynchus mykiss (truta-arco-íris), para ambos os rios. Dentre os indivíduos capturados, as duas espécies de Astyanax foram as únicas constantes nos quatro ambientes de estudo. Aplicando-se o índice qualitativo de Jaccard, registrou-se o maior valor de similaridade entre os ambientes de remanso dos dois rios, enquanto que para o índice quantitativo de Bray-Curtis, o maior valor estimado foi entre os ambientes remanso e corredeira do rio Caveiras. Tanto a similaridade qualitativa quanto a quantitativa mostraram-se relativamente altas, sugerindo grande semelhança na composição ictiofaunística entre os ambientes de ambos os rios. Quanto à biomassa, registraram-se valores semelhantes para os dois rios, correspondendo ao total de 6.222,64 g no rio Caronas e 7.152,52 g no rio Caveiras. Os itens alimentares encontrados com maior freqüência de ocorrência nos conteúdos estomacais de todos os peixes analisados foram: 22,8% de Insecta - aquáticos, partes de Nematoda (14,3%) e Planta terrestres (13,1%), para o rio Caronas, e 24,4% de Insecta - aquáticos, areia (12,7%) e vestígios de Nematoda (11,7%), para o rio Caveiras. Observouse que os ambientes são muito semelhantes em termos de riqueza específica e dominância. As espécies Rineloricaria sp, Pimelodus absconditus, Astyanax sp 1, Astyanax sp 2, Oligosarcus brevioris e Oncorhynchus mykiss ocorreram nos dois ambientes de ambos os rios; Hoplias malabaricus só não ocorreu no ambiente corredeira do rio Caveiras; Rhamdia quelen ocorreu no ambiente remanso de ambos os rios e Hypostomus isbrueckeri teve ocorrência restrita ao ambiente corredeira do rio Caronas. Comparando o Kr (fator de condição relativo) para as duas espécies de Astyanax, nos distintos ambientes estudados, foi verificado que no remanso do rio Caveiras, para ambas as espécies, os valores foram superiores a 1,0. Os resultados evidenciaram que a ictiofauna esteve representada por um número baixo de espécies e com baixa frequência de ocorrência, sempre com o predomínio da forrageira Astyanax sp 1, e que a presença da truta-arco-íris em ambos os rios, representa um risco para as espécies nativas, tornando a diversidade ictíica destes locais potencialmente ameaçada.

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