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Universidade Federal Rural do Semi-Árido (UFERSA) 2015

Composição e estrutura temporal da ictiofauna do Reservatório de Santa Cruz - Rio Apodi/Mossoró - Semiárido Brasileiro

SOUSA, Marla Melise Oliveira de.

Titre : Composição e estrutura temporal da ictiofauna do Reservatório de Santa Cruz - Rio Apodi/Mossoró - Semiárido Brasileiro

Composition and temporal structure of the fish fauna of the Santa Cruz Reservoir, Apodi/Mossoro River, Brazilian Semiarid

Auteur : SOUSA, Marla Melise Oliveira de.

Université de soutenance : Universidade Federal Rural do Semi-Árido (UFERSA)

Grade : Mestrado em Sanidade e Produção Animal 2015

Résumé
Because they are artificial ecosystems, reservoirs cause unforeseeable events on the water cycle, determining a continuous reorganization of communities, causing an evolution does not happen according to balanced patterns, compromising the productivity of the ecosystem. Thus, the objective of this study was to evaluate the seasonal structure (rain and dry) and temporal (between years) of the fish assemblage of the Santa Cruz reservoir, Brazilian semiarid and verify that the rainfall and reservoir level factors influence the structure of fish assemblage. The samples were collected quarterly from February 2010 and November 2013 in eight points of the reservoir, with gillnets and mesh between 12 and 70mm, exposed by 12h00min in the water at night. The abundance of species, has been transformed into Catch per Unit Effort by numbers (CPUEn). A similarity matrix was constructed with data from CPUE, using similarity coefficient of Bray-Curtis, presented in graphics of non-Metric Multidimensional Scaling (n-MDS) between rainy season (february and may) and dry (august and november) and for years. Permutational Multivariate Analysis of Variance (PERMANOVA) two-away was used to test statistical differences in the temporal structure of the fish assemblage. In the statistical difference between the years, the Similarity Percentage analysis in catches (SIMPER) was used to identify the species that contributed most to the similarity between the years. The fish assemblages of the reservoir was characterized using the following descriptors : i) species richness (S) ; ii) diversity index of Shannon-Wiener (H’) ; and iii) abundance (CPUE). Analysis of Variance (ANOVA) was used to check whether there was a difference over the period studied between the values of S, H’ and CPUE. Pearson correlation was made to verify the relationship between the S data, H’ and CPUE with rainfall and reservoir level. All analyzes were performed using R version 3.1.2 soft. and a significance level of p<0.05. The 9,442 individuals were captured 3 orders, 11 families and 21 species, of which four belonged to introduced species. The order Characiformes was the most representative in number of captured families and individuals, the family Cichlidae was the most representative in number of species. The n-MDS ordination plot showed a separation of fish assemblages and the PERMANOVA indicated significant differences in the structure of assemblages between years and seasons (rain and dry), no significant interaction between factors. ANOVA indicated no differences in the data of richness (5.75 min. and 9.38 max.), diversity (1.47 min. and 2.30 max.) and CPUE (0.97 min. and 7.45 max.), however, the Pearson correlation showed a negative relationship between rainfall and reservoir level with the diversity index and positive relationship between reservoir level and CPUE. We conclude that the structure of the fish assemblage of the Santa Cruz reservoir varied seasonally and temporally and rainfall and reservoir level factors were important in structuring the assemblage

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Page publiée le 15 mars 2019