Thermal tolerance of the male freshwater prawn Cryphiops caementarius exposed to different acclimation temperatures.

The variation in water temperature influences metabolic and biochemical processes in ectothermic organisms, affecting development, behavior, and thermal responses. We conducted laboratory experiments based on different acclimation temperatures to determine the thermal tolerance in male specimens of the freshwater prawn Cryphiops caementarius. During 30 days, male prawns were exposed to acclimation temperatures of 19 °C (control), 24 °C, and 28 °C treatments. The Critical Thermal Maxima (CTMax) values at these acclimation temperatures were 33.42 °C, 34.92 °C, and 36.80 °C; whereas values for the Critical Thermal Minimum (CTMin) were 9.38 °C, 10.57 °C, and 13.88 °C. All acclimation temperature treatments had a positive effect (P < 0.05) on CTMax and CTMin, with high and significant correlations (CTMax: r = 0.992, P < 0.01; CTMin: r = 0.946, P < 0.01). The area of the thermal tolerance polygon over the three acclimation temperatures was 211.32 °C2 and the acclimation response rate values were high (CTMax from 0.30 to 0.47; CTMin from 0.24 to 0.83) but similar to those from other tropical crustacean species. These results demonstrate that adult males of the freshwater prawn C. caementarius can tolerate extreme water temperatures through a thermal plasticity response, which could be advantageous during a global warming scenario.

Trabajos originales Preferencia termal de machos adultos de Cryphiops caementarius previamente aclimatados a diferen- tes temperaturas / Thermal preference of adult males of Cryphiops caementarius previously acclimated at different temperatures

Resumen El objetivo fue determinar la preferencia termal de machos adultos de Cryphiops caementarius previamente aclimatados a diferentes temperaturas. Los camarones se colectaron del río Pativilca. En laboratorio, los camarones se aclimataron durante 30 días en nueve acuarios, cada uno con 10 recipientes circulares. En cada recipiente hubo un camarón (10 por acuario). Las temperaturas de aclimatación fueron de 19, 24 y 28 °C. El sistema de gradiente de temperatura (12 a 33 °C) fue una canaleta de PVC (3 m de longitud y 10 cm de profundidad) con 18 compartimentos. En un extremo de la canaleta se colocaron termorreguladores sumergibles (100W) y en el otro extremo, bolsas con hidrogel congeladas. La preferencia termal se determinó por el método agudo y las pruebas se realizaron entre las 08:00 y 14:00 h. Los camarones aclimatados a 24 °C se desplazaron a compartimentos cuyas temperaturas fueron más altas que la temperatura de aclimatación. Los camarones aclimatados a 24 °C se desplazaron a compartimentos cuyas temperaturas fueron alrededor de la temperatura de aclimatación. Los camarones aclimatados a 28 °C se desplazaron a compartimentos donde las temperaturas fueron más bajas que aquella de aclimatación. La preferencia termal de los camarones aclimatados a 19 °C fue de 22.7 °C, y la de los aclimatados a 24 °C fue de 24.8 °C, ambos sin diferencias significativas (p>0.05). En cambio, en los aclimatados a 28°C fue de 21.1 °C, que solo difirió (p<0.05) con los aclimatados a 19 °C. La preferencia termal final fue de 24.5 °C.

Abstract In this work, we establish the thermal preference of Cryphiops caementarius adult males, previously acclimated at different temperatures. Shrimp were collected from the Pativilca River. In the laboratory, shrimp were acclimated for 30 days in nine aquariums, each with 10 circular containers. In each container, there was a shrimp (10 per aquarium). Acclimation temperatures were 19, 24 and 28 °C. The gradient temperature system (12 to 33 °C) consisted for a PVC gutter (3 m long and 10 cm deep) with 18 compartments. Submersible thermoregulators (100W) were placed at one end of the gutter and the other end, frozen hydrogel bags. The thermal preference was determined by the acute method and the tests were performed between 08:00 and 14:00 h. Shrimp acclimated at 24 °C moved to compartments whose temperatures were higher than the acclimation temperature. Shrimp acclimated at 24 °C moved to compartments whose temperatures were around the acclimation temperature. Shrimp acclimated at 28 °C moved to compartments where temperatures were lower than acclimation. The thermal preference of acclimated shrimp at 19 °C was 22.7 °C, and those acclimated at 24 °C were 24.8 °C, both without significant differences (p>0.05). On the other hand, in acclimated ones at 28 °C it was 21.1 °C, which only differed (p<0.05) with those acclimated at 19 °C. The final thermal preference was 24.5 °C.