Haematological and oxidative stress responses inPiaractus mesopotamicusunder temperature variations in water

Abstract

In this study, the influence of temperature variation on the blood and oxidative stress parameters of pacu Piaractus mesopotamicus juveniles was evaluated. Fish were subjected to gradual changes of temperature, over 5 days, by 24°C until reaching to experimental temperatures 18, 21, 24 (control), 27 and 30°C. There were significant differences (p < .05) in glucose and lactate of blood in both the haematological relationships and oxidative stress parameters. Glucose levels increased at 30°C and decreased at 21°C. Lactate levels were highest at 18°C. While the haematocrit was higher at all altered temperatures, haemoglobin levels decreased at 21°C and increased at 30°C, causing alterations in haematimetric indices. In the liver, glutathione‐S‐transferase (GST) activity was reduced at 18°C while antioxidant capacity against peroxyl radicals (ACAP) was highest at 30°C. Thiobarbituric acid reactive substances (TBARS) increased at 18, 21 and 27°C. In the muscle, ACAP decreased at 27 and 30°C and TBARS increased at 30°C. The results indicate that the species shows sensitivity to temperature variations. Accordingly, we conclude that with short‐term temperature variations >3°C, it is possible to induce higher alterations in the observed parameters in pacu juveniles.

Secondary stress responses to hypoxia and re‐oxygenation at different temperatures in pacu (Piaractus mesopotamicus) juveniles

“…Low DO and low or high temperature are very common stressors to tropical fish (Copatti, Bolner, et al, 2019;Pinto et al, 2019).…”

“…Low DO and low or high temperature are very common stressors to tropical fish (Copatti, Bolner, et al., 2019; Pinto et al., 2019). High water temperature in synergism with hypoxia impairs the DO availability, the dynamics after recovery events, and fish metabolism (McBryan, Anttila, Healy, & Schulte, 2013).…”

“…In addition, pacu is an established aquaculture species with good potential for intensive aquaculture due to its hardiness including a high tolerance to low DO levels, different temperature ranges, as well as contrasting pH levels and high concentrations of ammonia. It also has high growth performance and produces fillets with excellent nutritional quality that are well‐accepted by the consumer market (Jomori, Carneiro, Malheiros, & Portella, 2003; Nitz et al., 2019; Pellegrin, Nitz, Maltez, Copatti, & Garcia, 2020; Pinto et al., 2019; Sampaio et al., 2008). In fish farms, it is also susceptible to hypoxia conditions due to high stocking density conditions (Bittencourt et al., 2010).…”

“…Continental aquaculture stands out on the global scenario, reaching 51.4 million tons in 2016, which represents 64.25% of the total world aquaculture production (FAO, 2018). With the development of aquaculture, many species end up being confined and changes in water quality variables can occur in specific situations, for example decreased DO levels due to stagnant waters (Baldisserotto et al., 2008), lack of light, because it reduces the photosynthesis of plants and algae (Boyd & Tucker, 2014; Copatti, Bolner, et al., 2019), and variations in water temperature due to the different seasons in temperate and subtropical regions (Pinto et al., 2019). In fish aquaculture, changes in DO levels and temperature can affect several physiological processes (Aboagye & Allen, 2018; Chen et al., 2017), impairing growth performance and health.…”

“…In addition, being tolerant to low temperatures, pacu could be cultivated in a wide range of latitudes (Bechara, Roux, Diaz, Quintana, & Longoni de Meabe, 2005). However, if temperatures exceed tolerance limits, it can trigger undesirable results on pacu growth and health (Barbieri & Bondioli, 2015; Pinto et al., 2019).…”