Thermal Tolerance and Physiological Changes in Mud Crab, <i>Scylla paramamosain</i> Crablet at Different Water Temperatures
2021
Muhammad Nur Syafaat | Mohamad Nor Azra | Faridah Mohamad | Che Zulkifli Che-Ismail | Adnan Amin-Safwan | Mohammad Asmat-Ullah | Mohammad Syahnon | Azmie Ghazali | Ambok Bolong Abol-Munafi | Hongyu Ma | Mhd Ikhwanuddin
This study was carried out to determine the physiological changes (survival, growth, molting cycle, sex differentiation, and gill condition) of mud crab, <i>Scylla paramamosain</i> crablet at different water temperatures of 24, 28 and 32 °C, and ambient temperature of 27 to 30 °C. Thermoregulatory behavior, represented by preferred temperature (29.83 ± SD 2.47 °C), critical thermal minimum (17.33 ± SD 0.58 °C), critical thermal maximum (40 ± SD 0.00 °C), and thermal tolerance interval (22.67 ± SD 0.58 °C), were checked for Crablet 1 stage only (with ambient temperature as acclimation temperature).Both low (24 °C) and high (32 °C) temperatures were associated with lower growth performance, and survival rate (<i>p</i> < 0.05), in comparison with both 28 °C and ambient temperature treatments.Male ratio at low temperaturetreatment (24 °C) was higher (80.09 ± SD 18.86%) than for other treatments (<i>p</i> < 0.05), observed as 44.81 ± D 10.50%, 41.94 ± SD 19.44%, and 76.30 ± SD 5.13% for 28 °C, 32 °C and ambient temperature treatments, respectively. However, there was no significant difference observed between 24 °C, 28 °C, and ambient temperature treatments. Anatomical alterations of gill lamellae of <i>S. paramamosain</i> crablet for both 32 °C, and 24 °C treatments, appeared thinner and paler than at both 28 °C, and ambient temperature treatments. Based on this study, temperature of 28 to 30 °C was recommended as the optimal temperature for the long-term nursery phase of <i>S. paramamosain</i>.
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