Exposição aguda à amônia compromete a reprodução e a viabilidade embrionária do lambari Amazônico Astyanax bimaculatus (Linnaeus, 1758).

Abstract

This study evaluated the effects of acute ammonia exposure on the reproduction and embryonic and larval viability of the Amazonian tetra species (Astyanax bimaculatus). Adult breeders were exposed to a sublethal concentration of ammonia (NH₄Cl, 180 mg/L) for 4 hours before artificial reproduction. The results showed a significant reduction in hatching rates (82.3 ± 0.577 (41,2%) vs. 129 ± 1.73 (64,5%) in the control) and an acceleration in hatching time (1005 ± 2.58 vs. 1026 ± 3.65 minutes). Gonadal histology revealed alterations in gametogenesis, with exposed females exhibiting fewer vitellogenic oocytes and a higher number of post-ovulatory follicular complexes, while males presented a larger number of spermatocytes and interstitial tissue, and a reduction in spermatozoa. In both cases, indicating early release of gametes. Morphometric analysis of larvae from exposed breeders indicated delayed growth at 10 days post-hatching, although no morphological abnormalities were observed. These findings demonstrate the impact of ammonia on reproductive success and larval development in fish, emphasizing the importance of strict water quality management in aquaculture to mitigate such effects.