Efeito das mudanças climáticas sobre o metabolismo energético, antioxidante e neurológico do tambaqui (cuvier, 1818)

Abstract

Climate change has become one of the most discussed issues worldwide. According to the Intergovernmental Panel on Climate Change (IPCC) (IPCC, 2014), an increase of up to 6 ° C in the atmosphere is predicted for the year 2100. These changes directly affect the Amazonian aquatic environment and its organisms. These include changes in pH, temperature and oxygen, as well as causing damage to organisms by imposing behavioral, biochemical and morphological adjustments. Among these organisms is tambaqui (Colossoma macropomum), a species of high commercial value for the region and that has several adaptations to face periods of variations in temperature and seasonality of oxygen. Thus, the objective of this work was to evaluate how the effect of climatic scenarios and exposure to hypoxia affect the energy, antioxidant and neurological metabolism of individuals of the species. For this, the animals were acclimated for 30 days in scenarios RCP2.6 and RCP8.5 (4.5 ° C and 900 ppm CO2) (N = 42) and subsequently subjected to hypoxia for 6 hours (n = 7), After that, blood samples were collected for hematological analysis and tissues such as liver, brain, muscle and heart for enzymatic analysis and damage. The oxygen consumption variables show us that the species tries to maintain its consumption performance when kept in the extreme scenario in normoxia and hypoxia. For blood parameters, hemoglobin concentration ([Hb]), mean corpuscular hemoglobin (HCM) and mean corpuscular hemoglobin (CHCM) concentration were high (p <0.001), indicating that animals increase circulating hemoglobin to try to better supply tissue oxygen demand. Being observed the elevation of glucose concentrations when hypoxic for both scenarios (p <0.001) that is used by alternative pathways. The catalase (CAT) and glutathione-S-transferase (GST) enzymatic analyzes show us that the species does not present significant responses to the extreme scenario or lipoperoxidation damage. The same is expressed for LDH kinetics for the extreme scenario, and AChE remained almost unchanged for both scenarios, with a difference only in the current hypoxia (p <0.014). Thus, extreme scenarios and hypoxic conditions may condition metabolic stress in the animal interfering with the necessary adjustments. Keywords: Thermal adaptation; tambaqui; hypoxia; oxidative stress