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Haliotis cracherodii is the only abalone species listed as critically endangered (IUCN Red List) and protected under the Endangered Species Act (ESA) since 2009. The population started decreasing in the mid-1980s throughout its biogeographical range due to the "withering syndrome" disease. The objective of this study was to evaluate the thermoregulation of the black abalone, establishing its preferred temperature, locomotion displacement, and critical thermal maximum (CTMax). The preferred temperature (PT) was 13.8 °C. The theoretical temperature for optimal growth of the black abalone was 14.3 °C. The locomotion displacement in the gradient had an interval of 137 to 83 cm h−1. CTMax was evaluated, the first abalone detached from the substrate at a temperature of 25.4 °C and the last one at 31 °C; CTMax of 50% was calculated at 29.7 °C. These data will allow us to maintain and condition the black abalone in captivity with the final goal of producing seed for the restoration of disease-impacted populations on the Baja California Peninsula. ENSO events may also affect the survival of black abalone. We extrapolated the Thermal Safety Margin (TSM) = (28.8 – 18.31 °C) = 10.49 °C in weak ENSOs, but in stronger ENSO the TSM value diminishes to 3.17 °C suggesting that black abalone may be vulnerable to climate change. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of different environmental temperatures in the physiology of Lutjanus guttatus juveniles by analysing their thermoregulatory behaviour, thermal tolerance, oxygen consumption rates and thermal metabolic scope. Jointly, the effect of acclimation and critical temperatures on heat shock protein 70 (Hsp70) and lactate dehydrogenase (Ldh‐a) gene expressions were also analysed using acclimation temperatures of 20, 23, 26, 29 and 32°C. The results showed that the final preferred temperature in juvenile snapper was 26°C with a thermal window of 336.5°C2, which was related to an optimal temperature for their physiology determined by the routine metabolic rate and thermal metabolic scope. At temperatures from 20 to 26°C, the routine metabolic rate and Hsp70 and Ldh‐a genes had the lowest values related to a basal expression level. At acclimation temperatures from 29 to 32°C and after critical thermal maximum (CTmax) limit, the relative expression of Hsp70 and Ldh‐a genes increased significantly, but the main response at CTmax was the upregulation of Hsp70 gene. [ABSTRACT FROM AUTHOR]

Fish actively select an adequate environment that fits their optimum culture/preferred temperature, this mechanism is called thermoregulatory behavior. However, what exactly is this mechanism, how does it work and what can we learn from it? Helped by their thermal limits, fish avoid temperature variations not favorable for their maximum growth. They find a thermal window where optimal temperature culture is located and use it in the best way possible for all activities. The present study is based on thermal biology studies, and its purpose is to learn the aerobic scope functions on Pargo-UNAM juveniles. The importance of this study is related to the fact that Pargo-UNAM fish, being a hybrid, has five different genetic backgrounds. We found that acclimation temperature influenced the preferred temperature of Pargo-UNAM, having a metabolic adjustment in the 20-32°C range; the Final preferendum obtained was 29.5°C. The maximum and minimum range of critical thermal limits was between 39.2-43.5°C and 8-14.9°C, respectively. The thermal window had an area of 355.2°C2. The acclimation response ratio had a 0.40-0.35 interval for CTMax, and 0.52-0.69 for CTmin. Chase method used in Pargo-UNAM caused a maximum aerobic scope at 29°C. Blood lactate concentration was the highest in fish acclimated at 20°C; these values decreased while acclimation temperature increased. Results from Pargo-UNAM juveniles showed that these can be grown successfully in a 26-32°C temperature range, with their greater performance at 29°C, where the aerobic scope was at its maximum capacity. [ABSTRACT FROM AUTHOR]

Temperature is one of the most dominant environmental factor influencing the biology and performance of aquatic ectotherms in the wild and in culture conditions. Thus, the aims of the present study were to investigate thermoregulatory behavior, thermal tolerance and active metabolic scope in Macrobrachium tenellum. To fulfill our goal, we measure, the preferred temperature, critical threshold limits, thermal window width, oxygen consumption routine rate and active metabolic scope in the prawn M. tenellum acclimated to 20, 23, 26, 29 and 32°C. The preferred temperature obtained by the graphic acute method was 28.5°C. Acclimation temperature significantly affected the thermal tolerance which increased with the acclimation temperature. The scope for thermal tolerance had an interval of 25.3 to 27.7°C. The thermal window calculated for M. tenellum was 325°C2. The acclimation response ratios had an interval of 0.42-0.50. These values allow us to characterize these species as inhabitants of subtropical and tropical regions. The oxygen consumption routine rates increased as the acclimation temperature increased from 20 to 32°C. The range of temperature coefficient (Q10) between 29-32°C was the lowest, at 1.98. The active metabolic scope for prawns was the lowest for organisms acclimated to 20 and 32°C and the highest value was obtained at 29°C. The results obtained in the present study are important to determine the optimum conditions in which M. tenellum needs to live in the natural environment and may partially explain their wide distribution pattern along the Mexican Pacific Ocean littoral. [ABSTRACT FROM AUTHOR]

The thermoregulatory behavior of the giant keyhole limpet Megathura crenulata was determined in a horizontal thermal gradient during the day at 18.9 °C and 18.3 °C for the night. The final preferendum determined for giant keyhole limpets was of 18.6±1.2 °C. Limpets' displacement velocity was 10.0±3.9 cm h −1 during the light phase and 8.4±1.6 cm h −1 during the dark phase. The thermotolerance (measured as CTMax at 50%) was determined in a keyhole limpet in three acclimation temperatures 17, 20, and 23 °C. Limpets were subjected to water increasing temperatures at a rate of 1 °C every 30 min, until they detached from the substrate. The critical thermal maximum at 50% was 27.2, 27.9 and 28.3 °C respectively. [ABSTRACT FROM AUTHOR]

The preferred temperature ofCancer antennariusdetermined with the acute method was 15.2 °C, and with the gravitation method was 15.9 ± 1.9 in the day cycle and 13.2 ± 0.6 °C in the night cycle. The critical thermal maximum increased as the acclimation temperature was increased (p < 0.05); the thermal tolerance interval was 1.3, indicating that this species has a low tolerance indicative that it has evolved in highly stable environments. The acclimation response ratio for adults had an interval of 0.10–0.30. These values allow us to characterize this species as inhabiting cold and temperate regions. The oxygen consumption rates increased significantly (p < 0.05) from 6.57 to 9.92.0 mg O2 kg−1 h−1wet weight as the acclimation temperature increased from 15 to 24 °C. The range of temperature coefficient (Q10) between 15 and 18 °C was the lower than 1.70 and corresponds with the intervals of preferred temperature. [ABSTRACT FROM AUTHOR]

Abstract: An inverse and unusual relationship was found between preferred temperature and acclimation temperature in the bullseye puffer, Sphoeroides annulatus. The final preferendum temperature (PT) was 26.8°C. The critical thermal maxima (CTMax) were 37.7, 38.8, 40.0, 40.8 and 41.3°C where the temperatures of acclimation were 19, 22, 25, 28 and 31°C±1°C, respectively, and the endpoint of CTMax was loss of the righting response. The acclimation response ratio presented an interval of 0.22–0.38; these values are in agreement with results for other subtropical and tropical fishes. The temperature significantly affected the oxygen consumption of bullseye puffer juveniles. The oxygen consumption rate (OCR) increased significantly with an increment in the temperature from 19 to 31°C. The range of the temperature coefficient Q 10 in bullseye puffer individuals was lowest between 25 and 28°C, at 1.37. The optimal temperature for growth was 26°C. The results of this study will be useful for optimizing the culture of bullseye puffer juveniles in controlled conditions. [Copyright &y& Elsevier]

Abstract: Final temperature preferendum of white shrimp adults were determined with acute and gravitation methods. The final preferendum was similar, independent of method (26.2–25.6°C). A direct relationship was determined between the critical thermal maxima values and the acclimation temperatures (P<0.05). The end point of Critical Thermal Maxima (CTMax) for adults was defined as the loss of righting response (LRR). The acclimation response ratio (ARR) for adults of white shrimp had an interval of 0.36–0.76, values that agreed with others obtained for crustaceans from tropical and subtropical climates. The oxygen consumption rates increased significantly (P<0.05) from 39.6 up to 90.0mgO2 kg−1 h−1 wet weight (w.w.) as the acclimation temperature increased from 20 to 32°C. The range of temperature coefficient (Q 10) of the white shrimp between 23 and 26°C was the lower 1.60. The results obtained in this work are discussed in relation to the species importance in the reproductive scope and maintenance of breeders. [Copyright &y& Elsevier]

The behavioural and metabolic responses of the largemouth bass Micropterus salmoides (Lacépède) to temperature were determined to define optimal thermal conditions. The final preferendum of largemouth bass juveniles determined with acute and gravitation methods was independent of the method (29.0–28.1 °C). The displacement velocity in the horizontal thermal gradient of bass juveniles was 22.4 cm h−1 in the light phase and 22.6 cm h−1 in the dark phase. Oxygen consumption rates in the largemouth bass increased significantly ( P<0.05) from 48.8 to 69.4 mg O2 Kg−1 h−1 with an increase in the acclimation temperature from 20 to 33 °C. The temperature quotient ( Q10) in the juveniles was 1.37–2.00 in the range of acclimation temperatures of 26–29 and 29–32 °C. The optimum temperature range for growth calculated using Jobling's equation was 28.1–28.6 °C and for Q10 values 26–29 °C. The results are discussed in relation to the use of this information in aquaculture. [ABSTRACT FROM AUTHOR]

Abstract: Preferred temperature (PT) of juveniles of Litopenaeus stylirostris was not modified (P>0.05) by salinity. The final preferendum of juveniles was 27.8°C. The critical thermal maxima (CTMax) determined at 42 combinations (6 temperatures×7 salinities) in blue shrimp was not affected significantly by salinity (P>0.05). We obtained a direct relationship between the CTMax and the acclimation temperature. The end point of CTMax in L. stylirostris was defined as the loss of righting response (LRR). The acclimation response ratio (ARR) for the juveniles of blue shrimp had an interval of 0.45–0.50, values that agreed with others obtained for crustaceans from tropical and sub tropical climates. [Copyright &y& Elsevier]

The thermoregulatory behaviour of green abalone Haliotis fulgens and pink abalone H. corrugata was investigated. Haliotis fulgens juveniles ranging in wet weight from 3.0 to 3.3 g and from 28.7 to 30.5 mm shell length and of H. corrugata 2.0 g and 25.7 mm in shell length were exposed to 19°C for 30 days in a flow-through water system. Temperature preference was determined in a horizontal thermal gradient and was found to be 25.4°C for green abalone and 25.0°C for pink abalone. Displacement velocity was 4.3 cm h−1 for H. fulgens and 12.8 cm h−1 for H. corrugata. The optimum temperature for growth calculated for both abalone species was 24.6 and 24.5°C respectively. The critical thermal maxima (CTMax) of H. fulgens and H. corrugata were determined as a measure of thermal tolerance. Abalones were subjected to increasing water temperatures at a rate of 1°C on 30 min until they detached from the substrate. The CTMax at 50% were 33.6 and 32.0°C for green and pink abalone respectively. The results are discussed in relation to site selection and commercial rearing. [ABSTRACT FROM AUTHOR]

(1)Final temperature preferendum of juvenile (0.9–1.9 g) and adult (5.2–12.5 g) angelfish Pterophyllum scalare were determined with acute and gravitation methods. The final preferenda were similar, independent of the method and development stage (29.0–31.1°C).(2)The critical thermal maxima (CTMax) for juveniles were 36.9°C, 37.6°C, 40.6°C, 40.8°C and for adults 38.4°C, 38.6°C, 41.0°C, 42.1°C. Adult angelfish CTMax was slightly higher than in juveniles (1°C; P<0.05); the endpoint of CTMax was the onset of spasms.(3)The acclimation response ratio for both stages had an interval of 0.33–0.44; these values are in agreement with results for subtropical and tropical fishes.(4)Therefore it is recommended that angelfish cultivation should be consistent with temperatures that do not change abruptly throughout the year and temperature maximum does not exceed 30°C. [ABSTRACT FROM AUTHOR]

This study determined the physiological and metabolic responses of cultivated Yellowtail Kingfish (Seriola lalandi) juveniles in accordance with their recent thermal history. The fish were acclimated at 20, 23, 26, 29 and 32 °C for 21 days to determine the final preferred temperature, thermal tolerance and the effect of acclimation temperatures on their oxygen uptake and aerobic scope. The final preferred temperature of juveniles was established at 26 °C. The critical thermal maximum (CTmax) ranged from 34.2 to 36.9 °C, while the critical thermal minimum (CTmin) ranged from 10.9 to 17.3 °C, depending on acclimation temperature. With the CTmax and CTmin values, the thermal window was determined to have an area of 258°C2, which is characteristic of subtropical organisms. Although, the metabolic rate was relatively constant (ranging 390.6–449.8 mg O 2 kg−0.8 h−1) between 20 and 26 °C (Q 10 = 1.6, 1.0), an increase to 544.8 mg O 2 kg−0.8 h−1 at 29 °C (Q 10 = 1.9) and decrease of 478.4 mg O 2 kg−0.8 h−1 at 32 °C (Q 10 = 0.6) were observed. The maximum value obtained for aerobic scope was 310.9 mg O 2 kg−0.8 h−1 at 26 °C. These results suggest that the acclimation temperature of 26 °C is an optimum thermal condition for a physiological and metabolic performance of yellowtail kingfish juveniles. On the contrary, the response observed during the evaluation of critical temperatures, oxygen uptake and aerobic scope indicated that yellowtail kingfish in the juvenile state could be vulnerable when it experiences for long periods (e.g., >21 days) temperatures above 29 °C. According to our results, the thermoregulatory behaviour of yellowtail kingfish in the juvenile stages could be one of the most important mechanisms to maintain its optimal physiological performance by actively selecting a stable thermal environment close to 26 °C. In addition, it was determined the limits of the pejus state of juvenile yellowtail kingfish at 29 °C, where an increase of oxygen uptake to maintain the aerobic energy metabolism was observed, this could certainly affect the growth of juveniles in culture systems if they do not return in a thermal range of 23–26 °C. These results can contribute to infer the different effects of acclimation temperature on the growth, thermal tolerance and respiratory capacity of S. lalandi juveniles on aquaculture systems. • Seriola lalandi juveniles have a preferred environmental temperature of 26°C. • S. lalandi juveniles exhibit a thermal tolerance similar to other subtropical fishes. • Extreme temperatures exert pressure on aerobic metabolism of S. lalandi juveniles. [ABSTRACT FROM AUTHOR]

Abstract: Octopus mimus is an important cephalopod species in the coastal zone of Peru and Chile that is exposed to temperature variations from time to time due to El Niño/Southern Oscillation (ENSO) episodes when surface temperatures can reach 24°C, 6°C above typical temperatures in their habitat. The relationships between temperature and food availability are important factors that determine the recruitment of juveniles into the O. mimus population. The present study was to evaluate the relationship between thermoregulatory behavior and the age of paralarvae (summer population) to determine whether changes in this behavior occur during internal yolk consumption, making larvae more vulnerable to environmental temperature change. Oxygen consumption of paralarvae when 1–4d old was determined to establish if respiration could be used to monitor the physiological changes that occur during yolk consumption. Horizontal thermal selection (17–30°C), critical thermal maxima (CTMax), minima (CTMin), and oxygen consumption experiments were conducted with fasting paralarvae 1–4d old at 20°C. Preferred temperatures were dependent on the age of O. mimus paralarvae. One day old paralarvae selected a temperature 1.1°C (23·4°C) higher than 2 – 4d old paralarvae (22·3°C). The CTMax of paralarvae increased with age with values of 31·9±1.1°C in 1-d-olds and 33·4±0.3 to 4-d-olds. CTMin also changed with age with low values in 2-d-old paralarvae (9.1±1·3°C) and 11·9±0·9°C in 4-d-old animals. The temperature tolerance range of paralarvae was age-dependent (TTD=difference between CTMax and CTMin) with higher values in 2 and 3d old paralarvae (25–26°C) as compared to 1d old (23·1°C) and 4d old animals (22.7°C). Oxygen consumption was not affected by the age of paralarvae, suggesting that mechanisms exist that compensate their metabloism until at least 4d of age. The temperature tolerance range of a planktonic paralarvae of octopus species is presented for the first time. This range was dependent on the age of paralarvae, and so rendered the paralarvae more vunerable to a combination of high temperature and food deprivation during first days of life. Results in the present study provide evidence that O. mimus could be under ecological pressure if a climate change causes increased or decreased temperatures into their distribution range. [Copyright &y& Elsevier]