Lower Incipient Lethal Temperature Research Articles

Salinity and temperature tolerance of brown-marbled grouper Epinephelus fuscoguttatus

Grouper have to face varied environmental stressors as a result of drastic changes to water conditions during the storm season. We aimed to test the response of brown-marbled grouper to drastic and gradual changes in temperature and salinity to understand the grouper's basic stress response. The results can improve the culture of grouper. Brown-marbled grouper, Epinephelus fuscoguttatus (6.2 ± 0.8 g) were examined for temperature and salinity tolerances at nine different environmental regimes (10, 20, and 33 ‰ combined with 20, 26 and 32 °C), in which the fish were subjected to both gradual and sudden changes in temperature and salinity. The critical thermal maximum (50 % CTMAX) and the upper incipient lethal temperature (UILT) were in the ranges of 35.9-38.3 and 32.7-36.5 °C, respectively. The critical thermal minimum (50 % CTMIN) and the lower incipient lethal temperature (LILT) were in the ranges of 9.8-12.2 and 14.9-22.3 °C, respectively. The critical salinity maximum (50 % CSMAX) and the upper incipient lethal salinity (UILS) were in the ranges of 67.0-75.5 and 54.2-64.8 ‰, respectively. Fish at temperature of 20 °C and a salinity of 33 ‰ tolerated temperatures as low as 10 °C when the temperature was gradually decreased. Fish acclimated at salinities of 10-33 ‰ and a temperature of 32 °C tolerated salinities of as high as 75-79 ‰. All fish survived from accumulating salinity after acute transfer to 20, 10, 5, and 3 ‰. But all fish died while transferred to 0 ‰. Relationships among the UILT, LILT, 50 % CTMAX, 50 % CTMIN, UILS, 50 % CSMAX, salinity, and temperature were examined. The grouper's temperature and salinity tolerance elevated by increasing acclimation temperature and salinity. On the contrary, the grouper's temperature and salinity tolerance degraded by decreasing acclimation temperature and salinity. The tolerance of temperature and salinity on grouper in gradual changes were higher than in drastic changes.

Critical Thermal Minima of Penaeus semisulcatus (Decapoda: Penaeidae) Acclimated to Four Temperature Levels

Abstract Critical thermal minima (CTmin) and lower incipient lethal temperature (LILT) were determined for Penaeus semisulcatus juveniles at four different acclimation temperatures (14, 20, 26, and 32 C). The effect of cooling rate on the CTmin was also investigated. The CTmin of shrimps at these respective acclimation temperatures were 7.1, 8.9, 10.5, 12.6 C and 6.6, 8.0, 9.7, 11.4 C and 6.1, 7.2, 8.3, 9.9 C for the cooling rates of 0.25, 0.5, and 1.0 C/h, respectively. The LILT value of P. semisulcatus were 5.23, 6.14, 7.36, 8.57 C at 14, 20, 26, and 32 C, respectively. The results indicated that both the cooling rate and the acclimation temperature significantly affected the CTmin (P < 0.05). Acclimation temperature had also significant effects on the LILT of P. semisulcatus (P < 0.05). In acclimation temperatures between 14 and 32 C, the acclimation response ratio values were 0.30, 0.26, and 0.21 at the cooling rates of 0.25, 0.5, and 1 C/h, respectively. The cold tolerance zone in which P. semisulcatus can survive for short period in this study ranged from 6.1 to 12.6 C.

Effect of temperature and salinity on low thermal tolerance of Penaeus semisulcatus (Decapoda: Penaeidae)

Critical thermal minima (CTmin) and lower incipient lethal temperature (LILT) were determined for Penaeus semisulcatus juveniles at combinations of four acclimation temperatures (18, 22, 26 and 30 °C) and four salinity levels (20, 25, 30 and 35 ppt). While the CTmin and LILT of shrimps were not affected significantly by salinity (P>0.05), a direct relationship was determined between the thermal minima values (CTmin, LILT) and the acclimation temperature (P<0.05). The acclimation response ratio for the juveniles of P. semisulcatus had an interval of 0.18–0.32 in the current study.

Temperature and salinity tolerances of yellowfin sea bream,Acanthopagrus latus,at different salinity and temperature levels

Abstract Yellowfin sea bream Acanthopagrus latus (Houttuyn) (0.98 ± 0.27 g) were examined for temperature and salinity tolerances at nine different environmental regimes (0.3, 15 and 33 ppt combined with 10, 25 and 32 °C), in which the fish were subjected to gradual and sudden changes in temperature and salinity respectively. The 50% CTMax (critical thermal maximum) and the UILT (upper incipient lethal temperature) were in the range of 34.8–38.2 °C and 32.8–36.4 °C respectively. The 50% CTMin (critical thermal minimum) and the LILT (lower incipient lethal temperature) were in the ranges of 4.9–9.4 °C and 7.1–17.6 °C respectively. The 50% CSMax (critical salinity maximum) and the UILS (upper incipient lethal salinity) were in the ranges of 54–69‰ and 9–44‰, respectively. The fish at lower temperature (10 °C) and salinity of 33‰ tolerated temperature as low as 6 °C when the temperature was decreased gradually. The fish at 33 and 15‰ and lower temperature (10 °C) tolerated salinity as high as 66–67‰, whereas those at freshwater salinity level (0.3‰) and 32 °C tolerated salinity to 50‰ when salinity was increased gradually. The relationships among UILT, LILT, 50% CTMax, 50% CTMin, UILS, 50% CSMax, salinity and temperature are given.

Temperature tolerance polygon of Poecilia sphenops Valenciennes (Pisces: Poeciliidae)

1. The critical thermal maximum (CTMax) and minimum (CTMin), the upper and lower incipient lethal temperature, and the high and low avoidance temperature of Poecilia sphenops were established. 2. The area of thermal tolerance of P. sphenops upon considering the lethal limits was 863.9 (°C) 2, the estimated area using the critical temperatures, as well as the zone of thermal preference were 959 and 323.4 (°C) 2, respectively. 3. P. sphenops is a species highly eurythermical that possesses a high tolerance, resistance and capacity of adaptation to environmental variations.

Notes: Predicting the Lethality of Fluctuating Low Temperatures to Blue Tilapia

Abstract Lower-lethal-temperature bioassays were performed with blue tilapias Tilapia aurea to test the utility of a lethal-dose model for forecasting cold-kill events. We applied the model to predict resistance times of blue tilapias acclimated to 24°C upon exposure to lower lethal temperatures varying between 5° and 13°C. Regression of predicted versus observed logarithmic median resistance times was significant, and the line of perfect agreement fell within the 95% confidence limits on the regression line. However, the model consistently underestimated the resistance time in tests that lasted longer than a few hours, presumably because fish in these tests achieved some downward thermal acclimation. We also applied a second model, developed for predicting upper incipient lethal temperatures, to the cold-resistance data from blue tilapias in an attempt to estimate the lower incipient lethal temperature (LILT) of fish acclimated to 24°C. Although the model's estimate of LILT, 14. 1°C, is reasonable, there...

Effect of Salinity on the Temperature Preference and Tolerance of Age-0 Mayan Cichlids

Abstract We measured the salinity tolerance, temperature tolerance, and preferred temperature of the Mayan cichlid Cichlasoma urophthalmus to determine if temperature and salinity would limit the range expansion of this introduced species in Florida. Salinity tolerance at 25°C exceeded 37‰. The upper and lower ultimate lethal temperatures in freshwater were 39 and 15°C, respectively. Acclimation to 15‰ salinity had no effect on the lower incipient lethal temperature (15°C). Thermal preference determined in a horizontal temperature gradient was 32.8°C in freshwater, 39.2°C at 15‰, and 26.9°C at 30‰ salinity. Our results indicated that temperature and salinity are not likely to limit range expansion of the Mayan cichlid from its present location in the southern portion of the Everglades National Park, but that the species' spread may be blocked by cold winter temperatures in north Florida.