Efeito agudo da amônia e do nitrito em tilápias Oreochromis niloticus mantidas em baixa salinidade

• Ano de defesa: 2013
• Autor(a) principal: Marcio Jose dos Santos Silva
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Qualidade da água; Aquacultura; Compostos nitrogenados; Tilápia; Toxicidade aguda; Aquicultura; Tilápia (Peixe) Criação; Água Qualidade
• Link de acesso: http://hdl.handle.net/1843/BUOS-9LSHK8

On many occasions the high toxicity of nitrogenous compounds acts by limiting the production of fish. Decrease in growth and increase in mortality may be potentiated by these pollutants mainly in aquaculture systems with low renewal rates and / or high stocking densities. The salinity of water in freshwater fish culture has been adopted with good results as a palliative method, because this practice interferes with the reduction of nitrite toxicity. In this study, Nile tilapia Oreochromis niloticus (1.5 ± 0.2 cm and 0.09 ± 0.03 g) were exposed to acute concentrations of ammonia and nitrite in brackish environment with semi-static system. In each duplicate treatment, 16 fish were kept in 1 L beakers for 96 h at room temperature, approximately 28°C, 12 h photoperiod and pH approximately 7.8. In order to estimate the median lethal concentrations (LC50 96 h) the software Trimmed Spearman Karber method was used. The CL's 50 were estimated at 4.02 and 195.3 mg/L NH3-N and N-NO2-, respectively. Throughout the experimente, biological material was collected in order to study the different histological concentrations. The traditional protocol for histological preparation was used, subsequently observed in optical microscopy. In these studies, acute exposure to nitrogenous compounds was enough to cause damage to the tissues of the organisms tested. It was possible to observe pathologies in the gills, liver, kidney and brain using photomicrographs,. These findings showed that salinity, even low (2 ), reduced the toxicity of nitrite. The tilapia showed damage in different organs after acute exposure, noting the high toxicity of nitrogenous compounds.