Effects of phenanthrene on the amazonian fish tambaqui colossoma macropomum: Lc50, growth and haematology

Abstract

Oil spills have increased in frequency worldwide and biodiversity hotspots, such as the Amazon Basin, are under increasing threat of oil spills. The toxic effects of polycyclic aromatic hydrocarbons are poorly known for Amazonian fish species. The acute and sublethal effects of phenanthrene (Phe) on tambaqui (Colossoma macropomum), an important Amazonian food fish, were analysed in the present study. The Trimmed Spearman-Karber method was used to determine 96h-LC50 for Phe, which was 940 μg/L and represented roughly 70% of its regular water solubility at 30°C. Tambaqui specimens were exposed to 47, 235 and 470 μg/L, representing respectively, 5, 25 and 50% 96h-LC50 for Phe, for four weeks to analyse Phe effects on growth and haematological properties. Fish exposed to Phe showed high mucus production, expansion of lower lips, and the loss of both hydrodynamic balance and orientation. The condition factor has decreased by over 10% during the last two weeks of exposure to all Phe concentrations. After four weeks of exposure to 47 μg/L Phe (5% 96h-LC50), there was observed a decrease of nearly 47% for final weight gain, 55% for specific growth rate, and 9% for blood haemoglobin. Additionally, plasma glucose increased up to 49% in animals exposed to 470 μg/L Phe (50% 96h-LC50) and lactate increased up to 37% in animals exposed to 235 μg/L Phe (25% 96h-LC50). The main finding was that tambaqui exposed to Phe even at the lowest level analysed (47 μg/L Phe, 5% of the 96h-LC50 Phe) exhibited disturbances of basic biological and physiological functions.