Efeito da exposição de ovos e larvas de Osteocephalus taurinus Steindachner, 1862 - (Anura, Hylidae) à água contaminada de dois igarapés de Manaus - AM: toxicidade aguda e crônica

Abstract

This study aimed to verify through exposure to short-and long-term, direct and indirect effects of contaminated water from streams Mindu and Quarenta on anuran larvae, hylid Osteocephalus taurinus. Two experiments were conducted over 96 hours of exposure to a gradient of increasing concentrations, we assessed the acute effects of contamination on eggs and larvae in stage 25 larvae free natantia and without the presence of external gills. There was no mortality and no apparent anomalies in the short term for both streams for both stages of egg, as for the larvae. To assess the effects of chronic exposure, larvae were used in stage 25 of Gosn er, where they were exposed to contaminated water until they reach metamorphosis in an experiment using a one-factor control and two treatment using 100% of the concentration of water in their streams. The nitrogen compounds [ammonium (NH ), nitrite (NO ) and nitrate (NO )] produced in the course of the 4+ 2- 3 experiments were always in a higher concentration for the affluent of Mindu in relation to the Quarenta, while the concentrations o f pH , dissolved oxygen and temperature have remained always close between treatments and also taking all individuals received the same feed in two streams of water treatments, a significant difference in the length of larvae, size of metamorphosis and growth rate compared to control. The period of the larvae in Stream Mindu was lower, with the size and growth rate higher than in the control. In the Stream Quarenta, the situation is reversed, there was a period of larvae increased with the size at metamorphosis and growth rate lower than in control. The effects produced by chronic exposure to contaminated water streams are indications that the continuous contamination of streams and / or urban streams can upset the population dynamics of amphibians, carrying, other ecological changes. These results demonstrate possible consequences of contamination by urban sewage on larval amphibian communities of streams and pools of forest land.