Hsp70 and p53 expressions and behavior of juvenile pompano, Trachinotus carolinus (Perciformes, Carangidae), at controlled temperature increase

• Trachinotus carolinus juveniles have been submitted to heating at a rate of 2 °C h− 1.
• Fish have presented alteration in its behavior due to temperature increase.
• Immunohistochemistry of tissue samples demonstrated an increase of Hsp70 and p53.
• 50% of fish reached the Lethal Thermal Maximum (LTMax) at 38 °C ± 0.48 °C.
• Thermal stress negatively affects fish survival in many structural levels.

Understanding how temperature affects the fish is particularly useful to elucidate thermal adaptive processes that may occur on both vertebrate and invertebrate organisms. The aims of this study were to evaluate the immunohistochemical expression of Hsp70 and p53 proteins in gill and heart tissues related to thermal adaptations, and to use behavior analysis to examine temperature effects in juvenile pompanos (Trachinotus carolinus). The fish were exposed to a constant rate of water heating (2 °C/h) from 22 °C (control) to 26 °C, 30 °C, 32 °C, 34 °C and 36 °C, then maintained at one of those temperatures for 120 min. In addition, other experiments were held in which fish were submitted to a constant rate of 2 °C/h water heating to the temperature defined as the Lethal Thermal Maximum (LTMax), at which cessation of opercular movements occurred. The fish behavior was frantic until 36 °C and thereafter showed a generalized physiological disorganization. The results demonstrated that the Hsp70 and p53 expressions in tissues varied according to the temperature, indicating that the heating of the water could affect fish negatively. They can already be affected not only at high temperatures like 36 °C and LTMax but also close to environmental temperatures where they are found.