Qualidade da água e Comunidade Íctia do Açude Marengo (Madalena, CE) durante o período de estiagem

Detalhes bibliográficos
Ano de defesa: 2014
Autor(a) principal: Silva, Ana Caroline Bento da
Orientador(a): Não Informado pela instituição
Banca de defesa: Não Informado pela instituição
Tipo de documento: Dissertação
Tipo de acesso: Acesso aberto
Idioma: por
Instituição de defesa: Não Informado pela instituição
Programa de Pós-Graduação: Não Informado pela instituição
Departamento: Não Informado pela instituição
País: Não Informado pela instituição
Palavras-chave em Português:
Link de acesso: http://www.repositorio.ufc.br/handle/riufc/18226
Resumo: In the semiarid region of northeastern Brazil, long scarcity may to cause big changes in limnological variables. Aquatic organisms quickly realize the changes occurring in the environment and they are good tools to understand the preservation of interest area. This research aimed to observe the impacts about the water quality and ichthyofauna of the Marengo reservoir (localized in the Assentamento São Joaquim, Madalena, Ceará) due long scarcity. They were performed seven monthly collections (March to September of 2013) to evaluate the volume of water accumulated, the water’s trophic status and local ichthyofauna. The limnological variables analyzed were the Secchi transparency (euphotic zone), dissolved oxygen, temperature, pH, electrical conductivity, total phosphorus, chlorophyll a, Chemical Oxygen Demand (COD) and total nitrogen. The trophic status was estimated by the Lamparelli (2004) equations. The local ichthyofauna was analyzed by ecological indexes (Shannon’s diversity, Margalef’s richness and Pielou’s eveness). The results showed a significant reduction of 1,60 hm3 in the volume of water of Marengo reservoir, due to absence of rains and high rate of evaporation and population demand. The chlorophyll a and total phosphorus showed values above the maximum limit set by CONAMA Resolution 357/2005. The trophic status by Lamparelli (2004) indicated the reservoir can be eutrophic in all collections points, reaching hypereutrophic level. They were collected 1.129 fishes belong to 12 different species. The eveness showed high abundance of small fishes (A. bimaculatus, C. orientale and S. notonota) in the point 3, due to morphological aspect, giving refuge possibilities. The point 1 was characterized as the most diverse, richest and largest values of eveness, due to high movement of people and animals. The prolonged drought caused reduction of level of water in the Marengo reservoir and it provided high concentration of nutrients in the water column, reaching the highest trophic level (hypereutrophic). Due to poor water quality, the ichthyofauna will may enter into ecological imbalance and reach high rates of mortality for several species, similar to what occurred in Paus Branco reservoir (Madalena, Ceará).