Efeito da poluição do igarapé do Educandos (Manaus, Amazonas, Brasil) sobre ovos e larvas de Osteocephalus taurinos (Amphibia, Anura, Hylidae)

Abstract

The effects of short and long-term contamination by effluent from an urban stream of Manaus on eggs and tadpoles of Osteocephalus taurinus (Anura, Hylidae) werw evaluated. To evaluate the acute effects of contamination a test CL5096h was done , which exposed eggs and tadpoles in Gosner stage 25 to a gradient of increasing concentrations established in geometric progression over a period of 96 hours. Eggs were less resistant to contamination than the tadpoles. The CL5096h for tadpoles was 47.63 mL/L while for the eggs was 25.19 mL/L. At lower concentrations of the experiment with eggs in which no mortality occurred, the tadpoles showed abdominal edema after 96h. To evaluated the effects of chronic exposure to low concentrations of urban sewage, tadpoles in Gosner stage 25 were exposed to three concentrations (9, 18 and 36 mL/L) of effluent until they reach metamorphosis. There were significant differences in growth rate and the size of metamorphosis between control and treatment. There were no significant differences in the number of survivors and length of time larvae. A concentration of 25 mL/L of effluent tested caused deleterious effects on eggs of Osteocephalus taurinus. A concentration of 36 mL/L caused changes in the parameters of developing larvae, and susceptibility to contamination ranged from egg masses. A concentration of 47mL/L caused deleterious effects on tadpoles free swimming. Concentrations of up to 16 mL/L can cause an increase in the average size of tadpoles