Biological responses of Neotropical freshwater fish Lophiosilurus alexandri exposed to ammonia and nitrite

• Published in: The Science of the total environment 2018-03, Vol.616-617, p.1566-1575
• Main Authors: dos Santos Silva, Márcio José, da Costa, Franklin Fernando Batista, Leme, Fabiola Paes, Takata, Rodrigo, Costa, Deliane Cristina, Mattioli, Cristiano Campos, Luz, Ronald Kennedy, Miranda-Filho, Kleber Campos
• Format: Article
• Language: English
• Subjects: Ammonia - toxicity; Animals; Aquaculture; Biomarkers; Catfishes - physiology; Lethal Dose 50; Nitrites - toxicity; Nitrogen Compounds; Nitrogenous compounds; Recovery; Toxicity; Water Pollutants, Chemical - toxicity
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2017.10.157

This study aimed to elucidate the responses of the Neotropical fish Lophiosilurus alexandri exposed to ammonia and nitrite, following a period of recovering. Acute toxicity tests lasted 96h, subchronic toxicity tests lasted eight days and the detoxification trial lasted four days. Groups of 12 juveniles were maintained in 90-L tanks and treated with increasing concentrations of ammonia and nitrite, except during the recovery test. All treatments were performed with two replicates. The median lethal concentrations (LC50) of 24, 48, 72 and 96h were estimated at 30.12; 24.35; 19.24 and 18.68mg·L−1 TA-N; 5.37; 4.57; 3.75 and 3.66mg·L−1 NH3-N and 20.37; 7.78; 7.09 and 5.86mg·L−1 NO2−-N, respectively. The NO2− caused significant decrease in hematocrit and increase in the urea levels during short-term exposure, with recovery of homeostasis after the subchronic and detox period. Acute exposure to ammonia increased the enzyme profile of transaminases, glucose and urea. Urea concentration remained high in the subchronic and detox tests. Histopathologies were observed in animals exposed to ammonia in both toxicity tests. It was highlighted detachment of epithelium, hyperemia and necrosis in the gills. Exposure to NO2− caused epithelium detachment and aneurysm. Vacuolization and swelling of hepatocytes were the most common injury for both nitrogenous compounds. We concluded that the L. alexandri has moderate tolerance to ammonia and nitrite. The recovery period revealed remedial response to ammonia and nitrite exposure. [Display omitted] •Lophiosilurus alexandri can tolerate concentrations of ammonia and nitrite observed in Recirculating Aquaculture Systems-RAS.•The detox period revealed remedial response to the recovery of fish to ammonia and nitrite exposure.•The biomarkers used were useful for detecting adverse effects of the nitrogenous compounds tested.