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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°C 2 , 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., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

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., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

On the Yucatan Peninsula there is an upwelling which allows access to a body of cold water that controls temperature in this area. This modulates the ecology and distribution of organisms that inhabit the continental shelf. The objective of this study was to determine the effect of different acclimation temperatures on the thermal biology of prey as mollusc, crustacean (Melongena corona bispinosa, Strombus pugilis, Callinectes similis, Libinia dubia) and predators as fish (Ocyurus chrysurus, Centropomus undecimalis) of Octopus maya. Octopus prey preferred temperatures between 23.5°C and 26.0°C, while predators preferred temperatures 26.4-28.5°C. The species with largest thermal windows were M. corona bispinosa (328.8°C(2)), C. similis (322.8°C(2)), L. dubia (319.2°C(2)), C. undecimalis (288.6°C(2)), O. chrysurus (237.5°C(2)), while the smallest thermal window was for S. pugilis (202.0°C(2)). The acclimation response ratios (ARR) estimated for prey ranged from 0.24-0.55 in animals exposed to CTMax and 0.21-0.65 in those exposed to CTMin. Amongst predators, ARR ranged from 0.30 to 0.60 and 0.41 to 0.53 for animals exposed to CTMax and CTMin, respectively. Correlating the optimal temperature limits of prey and predators with surface temperatures on the continental shelf and those 4m deep showed that the main prey, Callinectes similis and L. dubia, shared a thermal niche and that an increase in temperature could force these species to migrate to other sites to find optimal temperatures for their physiological functions. As a consequence the continental shelf community would undergo a structural change. Predators were found to be near their optimal temperatures in surface temperatures on the continental shelf. We conclude that they would remain in the area in a warming scenario. The size of the thermal window was related to the type of ecosystem inhabited by these species. These ARR intervals allowed us to categorize the species as temperate or tropical, according to the oceanographic conditions that prevail on the Yucatan Peninsula., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Thermopreference, tolerance and oxygen consumption rates of early juveniles Octopus maya (O. maya; weight range 0.38-0.78g) were determined after acclimating the octopuses to temperatures (18, 22, 26, and 30°C) for 20 days. The results indicated a direct relationship between preferred temperature (PT) and acclimated temperature, the PT was 23.4°C. Critical Thermal Maxima, (CTMax; 31.8±1.2, 32.7±0.9, 34.8±1.4 and 36.5±1.0) and Critical Thermal Minima, (CTMin; 11.6±0.2, 12.8±0.6, 13.7±1.0, 19.00±0.9) increased significantly (P<0.05) with increasing acclimation temperatures. The endpoint for CTMax was ink release and for CTMin was tentacles curled, respectively. A thermal tolerance polygon over the range of 18-30°C resulted in a calculated area of 210.0°C(2). The oxygen consumption rate increased significantly α=0.05 with increasing acclimation temperatures between 18 and 30°C. Maximum and minimum temperature quotients (Q10) were observed between 26-30°C and 22-26°C as 3.03 and 1.71, respectively. These results suggest that O. maya has an increased capability for adapting to moderate temperatures, and suggest increased culture potential in subtropical regions southeast of México., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

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]

The clownfish Amphiprion ocellaris is widely distributed in the coral reef ecosystems of tropical and subtropical regions of the West Indo Pacific, an area that hosts economically valuable species, and, thus, a suitable candidate for warm water aquaculture. This study determined the preferred temperature, critical threshold limits, represented by critical thermal maximum and critical thermal minimum, thermal window width, and aerobic metabolic scope of A. ocellaris clownfish acclimated to 20, 23, 26, 29, 32, and 35 °C. A positive response (P < 0.05) occurred when the preferred temperature significantly increased with increasing acclimation temperature. The preferred temperature obtained graphically was 30.0 °C. Acclimation temperature significantly affected the thermal tolerance which increased with acclimation temperature. The thermal window calculated for A. ocellaris was 301.5 °C2. The thermal metabolic scope obtained in animals acclimated at the interval from 23 to 32 °C (P > 0.05) had a mean value of 4240.8 mg O2 h−1 kg−1 w.w., revealing that A. ocellaris is a eurythermal species with a range of optimal physiological performance that closely matches the environmental conditions where it can be farmed. Therefore, the highest value of the thermal aerobic scopes corresponded to the intervals of the preferred temperature obtained for A. ocellaris. These results may partially explain their worldwide distribution pattern, as well as their aquaculture potential in tropical regions. [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 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: Thermotolerance (CTMax) was determined in L. vannamei in three salinities and five acclimation temperatures 20, 23, 26, 29 and 32°C. In white shrimp, the CTMax was not significantly affected by salinity (P>0.05). A direct relationship was obtained between CTMax and acclimation temperature. The end point of the CTMax in L. vannamei exposed to different combinations of temperature and salinity was defined as the loss of the righting response (LRR). The acclimation response ratio (ARR) for the juveniles of white shrimp ranged from 0.42 to 0.49; values in agreement with other crustaceans from tropical and sub tropical climates. The osmotic pressure of the hemolymph was measured in control organisms and in organisms exposed to CTMax; significant differences were found in organisms maintained in 10 and 40psu, but there were no significant differences in hemolymph osmotic pressure in those that were acclimated to 26psu. [Copyright &y& Elsevier]

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]

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 effect of 96 h exposure to sublethal cadmium concentrations on oxygen consumption rate (VO2 mg h-1) and oxygen extraction efficiency (OEE′ %) was determined in juvenile Ctenopharyngodon idella acclimated to 26, 29 and 32 °C for at least two weeks. The relationships among the physiological rates (VO2 and OEE′, body weight and temperature, were fitted by second order polynomial models; the response surfaces generated allowed the evaluation of stress induced by the interaction of those variables. Both VO2 and OEE′ invariably increased as temperature increased. In small animals kept in 0.5 mg Cd L-1, the VO2 increase was compensated by a proportional increase in OEE′, whereas in larger fishes (>1 g) no compensatory response was observed. Both small and large fishes were unable to compensate for a higher VO2 when exposed to higher cadmium concentration. It is concluded that OEE′ in young fish is an early response of stress due to sublethal cadmium exposure. [ABSTRACT FROM AUTHOR]

This study investigated the effect of acclimation temperatures and eyestalk ablation (EA) on the thermal tolerance of juvenile Penaeus vannamei. In each case, the relative expression of genes involved in cell protection (hsp70 and hsp90), oxidative stress (cMnSOD and GPx), and anaerobic metabolism (hif1a) was assessed. For this purpose, shrimp were acclimated to 20, 26, and 32°C for 21 days. After acclimation, the critical thermal maxima (CTmax) was determined in non-eyestalk ablated, unilaterally, and bilaterally eyestalk ablated organisms. An effect of acclimation temperatures on CTmax values was observed, with shrimp acclimated at 32°C having the highest rates. Likewise, EA resulted in lower thermal tolerance to CTmax in organisms acclimated at 20 and 26°C. The shrimp's protective and cellular repair responses were evidenced by increased hsp70 and hsp90 gene expression after CTmax and were intensified by the EA. In contrast, the results showed that cMnSOD was very sensitive to CTmax, and its expression was intensified with EA, while for GPx, there was an increase in the relative gene expression, mainly in shrimp acclimated at 20°C. In the case of hif1a, overexpression was observed at the acclimation temperature of 26°C, showing the activation of compensatory mechanisms such as anaerobic metabolism. EA caused a significant molecular response during CTmax of molecular biomarkers involved in heat stress response, oxidative stress, and compensatory mechanisms. [ABSTRACT FROM AUTHOR]

• Thermal preferences (TP) from laboratory should predict wild occurrences. • A realized thermal niche (RTN) and TP comparison was performed. • The TP reflected the fish RTN since they follow optimal temperatures. • The TP did not reflect invertebrate RTN due to adaptations or dispersal capacity. Temperature is recongnised as the main factor controlling the species fitness and performance. Naturally, the thermal preferences (TP) of aquatic organisms obtained in controlled conditions have been used to relate physiological performance with field data since they are a good proxy to the fundamental niche. Literature suggests that dispersal capabilities, biological interactions, acclimatisation, adaptation, among others might play a role in species distribution; thus, in reality, species are usually occupying a realized thermal niche (RTN). Therefore, this study was designed to inquire into the following questions: Are the TP of tropical aquatic ectotherms found in laboratory conditions similar to their RTN? Can TP be validated with occurrences in the wild? To answer these questions, this study compared the TP obtained from previously published works with the RTN of the crabs Callinectes similis and C. sapidus, the fishes Centropomus undecimalis and Ocyurus chrysurus, the lobster Panulirus argus, and the octopus Octopus maya obtained from occurrences from 1693documents. When RTN values were tested against the TPs obtained in laboratory, no significant differences were found for fish species (P > 0.05); in contrast, differences for the benthic invertebrates were reported (P < 0.05). At least two factors could have been affecting these results: differences in the average tolerances between geographically distinct populations (local adaptation) and the dispersal capabilities that might have been forcing a differentiation between populations If, as proposed, fishes can actively follow thermal optimum, their response to warming scenarios could be faster than benthic organisms. If our hypothesis is true, the uncertainty of climate change could be reduced when the local adaptation is taking into consideration. [ABSTRACT FROM AUTHOR]