Epsilon Archive for Student Projects

Abstract

The purpose of this study was to examine the effects of glyphosate on fish survival,and aquatic environment parameters in mesocosm experiments. Fishes used in the experiments where Tilapia (Oreochromis niloticus) and Lambari (Astyanax bimaculatus). In a "high concentration" test of glyphosate during a short period of time (6, 12 and 24 hours), survival and growth of young fishes was recorded. In a second experiment, "environmental effects" of glyphosate application for aquatic weed control were evaluated during 9 weeks.
There were no obvious differences in growth and mortality in the "high concentration" experiment, regardless of the different concentrations and times of exposure of glyphosate used.
In the "environmental effects" test, some Tilapia from the higher concentrations had developed exoftalmia (visible swelling in the ocular globe) and some Tilapia in the highest concentration had effects on the liver. Among Lambari, no individuals were effected.
In the "environmental effects" test the initial increase of chlorophyll content seemed to be lower in the control mesocosms than in the glyphosate treatments. Possibly, glyphosate degraded relatively fast, maybe accompanied by an elevated release of nutrients.