Influência da turbidez da água do rio Tietê na ocorrência de plantas aquáticas
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Data
2005-06-01
Autores
Carvalho, Fernando Tadeu de [UNESP]
Velini, Edivaldo Domingues [UNESP]
Cavenaghi, A.L. [UNESP]
Negrisoli, E. [UNESP]
Castro, R.M. [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira da Ciência das Plantas Daninhas
Resumo
As plantas aquáticas são estudadas como um efeito do desequilíbrio causado pela poluição e/ou alagamento dos rios. A quantidade excessiva de plantas, conseqüente desse desequilíbrio, dificulta a navegação e a produção de energia elétrica. O objetivo deste trabalho foi identificar as principais plantas aquáticas do rio Tietê e relacioná-las com a turbidez da água dos diferentes reservatórios. Foram avaliados todos os focos de vegetação aquática emersa, flutuante e submersa, presentes em cada reservatório, em toda a sua extensão, sendo consideradas como importantes as espécies que apresentaram o caráter dominante. Foi observado que os represamentos apresentam problema de plantas aquáticas e a qualidade da infestação varia entre os reservatórios. Foram consideradas como dominantes as seguintes espécies: Brachiaria mutica, Brachiaria subquadripara, Eichhornia crassipes, Egeria densa, Egeria najas, Enidra sessilis e Typha angustifolia. Observou-se que houve uma tendência de maior ocorrência de plantas flutuantes e emersas (marginais) nos reservatórios com maior turbidez e de plantas submersas naqueles com menor turbidez. Para as duas braquiárias, observou-se que a freqüência das espécies aumentou com o aumento da turbidez até o limite de 34,93 NTU. O aguapé ocorreu com altos índices de freqüência (acima de 50%) em todos os reservatórios do rio Tietê, independentemente das características da água. em se tratando das egérias, a freqüência das espécies aumentou gradativamente com a redução da turbidez e a taboa não apresentou uma relação com o índice estudado. A espécie E. sessilis se mostrou bastante dependente da qualidade da água, tendo sua freqüência aumentada com o aumento da turbidez.
Aquatic plants are studied as an effect of pollution unbalance and/or river flooding. The excessive amount of plants,as a consequence of such unbalance, hinders navigation and electric power production. The objective of this work was to identify the main aquatic plants of the Tietê River and to relate them with water turbidity of the different reservoirs. All the foci of aquatic immersed, floating and submerged vegetation in each reservoir were evaluated in all their extension. Those species presenting a dominant character were considered important.The reservoirs were found to present aquatic plant problems with the quality of infestation varying among the reservoirs. The following species were considered to be dominant: Brachiaria mutica, Brachiaria subquadripara, Eichhornia crassipes, Egeria densa, Egeria najas, Typha angustifolia and Enidra sessilis.There was a tendency for a greater occurrence of floating and submerged (marginal) plants in the reservoirs with greater turbidity and for a larger occurrence of submerged plants in reservoirs with less turbidity. For the two Brachiarias it was observed that the frequency of the species increased with the increase of turbidity up to the limit of 34.93 NTU. E. crassipes occurred with high frequency indexes (above 50%) in all the Tietê River reservoirs, independent of the characteristic of the water. For Egerias, frequency increased gradually with reduced turbidity and T. angustifolia did not present a relationship with the studied index. The species E. sessilis was found to be rather dependent on the quality of the water,its frequency increasing with increased turbidity.
Aquatic plants are studied as an effect of pollution unbalance and/or river flooding. The excessive amount of plants,as a consequence of such unbalance, hinders navigation and electric power production. The objective of this work was to identify the main aquatic plants of the Tietê River and to relate them with water turbidity of the different reservoirs. All the foci of aquatic immersed, floating and submerged vegetation in each reservoir were evaluated in all their extension. Those species presenting a dominant character were considered important.The reservoirs were found to present aquatic plant problems with the quality of infestation varying among the reservoirs. The following species were considered to be dominant: Brachiaria mutica, Brachiaria subquadripara, Eichhornia crassipes, Egeria densa, Egeria najas, Typha angustifolia and Enidra sessilis.There was a tendency for a greater occurrence of floating and submerged (marginal) plants in the reservoirs with greater turbidity and for a larger occurrence of submerged plants in reservoirs with less turbidity. For the two Brachiarias it was observed that the frequency of the species increased with the increase of turbidity up to the limit of 34.93 NTU. E. crassipes occurred with high frequency indexes (above 50%) in all the Tietê River reservoirs, independent of the characteristic of the water. For Egerias, frequency increased gradually with reduced turbidity and T. angustifolia did not present a relationship with the studied index. The species E. sessilis was found to be rather dependent on the quality of the water,its frequency increasing with increased turbidity.
Descrição
Palavras-chave
hidrófitas, plantas daninhas, alagamento, eutrófico, hydrophytes, weeds, flooding, eutrophic
Como citar
Planta Daninha. Sociedade Brasileira da Ciência das Plantas Daninhas , v. 23, n. 2, p. 359-362, 2005.