Adolfo Sánchez

The effect of dissolved oxygen and salinity on oxygen consumption, ammonia excretion and osmotic pressure of Penaeus setiferus (Linnaeus) juveniles

Abstract The white shrimp Penaeus setiferus (Linnaeus) is an abundant species in the coastal lagoons and estuaries of the Gulf of Mexico. This species is well adapted to environments of low salinity and can tolerate low levels of dissolved oxygen. This study was designed to measure the effects of prolonged hypoxia and salinity level on: (a) the oxygen consumption and ammonia excretion, (b) the metabolic substrate (O:N) on fasting (24 h) and feeding animals, (c) the osmotic pressure of the hemolymph and, (d) the body water content of P. setiferus juveniles. The shrimp were exposed to different levels of dissolved oxygen (DO of 2, 3, 4 and 5.8 mg l −1 ) and two salinities (15 and 35‰) for a period of 60 days. Results indicate that these animals are oxyregulators between 5.8 and 4 mg l −1 DO and oxygen conformers between 3 and 2 mg l −1 DO in both salinities. There was not a significant effect of salinity on the oxygen consumption in either nutritional condition. Ammonia excretion was significantly greater in 15‰ than in 35‰. In 15‰ the ammonia excretion diminished as a function of the DO. In unfed animals the ammonia excretion diminished in a direct proportion to the decrease of the DO, while in fed animals they were ammonia-regulators between 5.8 and 4 mg l −1 DO. In 35‰ the ammonia excretion increased in the fed animals exposed to 2 and 3 mg l −1 DO. In low salinity the animals fundamentally maintained proteins as their energy substrate at all levels of DO, while in the case of 35‰ of salinity the shrimp changed the metabolic substrate from lipids-proteins (5.8 and 4 mg l −1 DO) to proteins (3 and 2 mg l −1 DO). These results show that P. setiferus juveniles are capable of changing their energy substrate in response to salinity and DO changes. This fact may be related to a possible strategy that allows them to obtain energy from proteins. The stability of osmotic pressure between 35 and 5‰ and the changes which have been observed in the total content of water give rise to the supposition that the pool of free amino acids, whether of muscular or nutritional origin, are the key to this strategy.

Haemolymph metabolic variables and immune response in Litopenaeus setiferus adult males: the effect of an extreme temperature

Abstract The stress of captivity could be the main reason for the loss of sperm quality of Litopenaeus setiferus (L) males in captivity. The aim of this study was focused on the physiological and immunological response of adult male shrimp exposed to a temperature extreme (33 °C) in order to understand how the stress modulates the physiological, immunological and reproductive behavior of L. setiferus males. We used some blood metabolic variables, sperm quality and immune response as indicators of stress measured daily during the 10-day experiment. The high temperature provoked loss of osmotic capacity (OC), a reduction in blood metabolites at day 5, a reduction in hemocyte pro Phenoloxidase (proPO) activity and a dramatic reduction in sperm quality in comparison to that observed in freshly captured wild shrimp populations. The ratio between proPO and granular cells (small granular and large granular cells) (proPO/GC) showed a cyclic behavior with lower peaks at days 3, 7 and 10 and high peaks at days 0, 5–6 and 8–9, evidencing migration and recovery of cells and proPO every 48–96 h, depending on the intensity of the stress. Such hemocyte migration was directed to the ampule and spermatophore where bacterial growth could be enhanced by abnormal and dead sperm cells. In such circumstances, a rapid mobilization of reserves could help to promote tissue regeneration in male testes and vas deferens. Such use of reserves could explain the reduction in blood metabolites observed at day 5 in present study. Although blood metabolites recovered after day 5, the loss of OC suggests that shrimp lose their osmotic homeostasis, possibly associated with the entrance of water due to inflammation of tissues provoked by melanization.

Effect of salinity on survival, growth, and oxygen consumption of postlarvae (PL10-PL21) of Litopenaeus setiferus

The present study was done to establish the lethal salinity (LCsO) and the effects of an abrupt change in the salinity on the oxygen consumption and the growth of postlarvae (PL10-PL21) of Litopenaeus setiferus, and their integration as assimilated energy. Postlarvae of L. setiferus presented a mean LC50 at 8%o, and a time of response of 2 h. Thereafter, LC50 remained constant for the next 96 h. The effect of salinity on oxygen consumption and growth rate changed with the age of postlarvae. From PL10 to PL15, the highest oxygen consumption was obtained at 10%o and the lowest at 40%o. During this time, growth rate increased with salinity with the maximum value in 40%o and lowest at 10%o. From PL15 to PL21, the highest oxygen consumption was obtained at 30 and 40%o. In 30 and 40%0, the growth rate was lower than that observed in animals maintained in 10%o. The assimilation-salinity relationship changed with the age of the organisms. From PL10 to PL15, assimilated energy increased with a decrease in the salinity, and from PL15 to PL21, assimilation increased directly with an increase in the salinity. The inverse relationship between oxygen consumption and growth has been observed in other estuarine organisms and suggests that, when animals are found in an osmotically favorable medium, the processes of capture and distribution of the ingested energy are more efficient. These mechanisms change with age. From PL15 to PL21, an increase in the salinity produced an increase in the assimilation. This was a result of an increase in the respiratory efficiency and, as a consequence, a reduction of the net growth efficiency.

Role of Digestive Gland in the Energetic Metabolism of Penaeus setiferus

We determined the role of the digestive gland in the respiratory metabolism of Penaeus setiferus adult males as a step toward proposing a feeding schedule based on the cycle of activity in the digestive gland. We measured pre- and postprandial values for oxygen consumption rate and hemolymph glucose concentrations in live animals, and oxygen consumption rate and glycogen concentration in excised digestive gland. After the animals were fed, which enhanced general metabolic activity, these indices changed. There was a high correlation between the oxygen consumption rate of the animal and the glucose concentration in the hemolymph, and between the oxygen consumption rate by the digestive gland and the glycogen concentration in the digestive gland, all in relation to time after feeding. Correlations support the hypothesis that the energy demand depends upon the metabolic substrate concentration. In this theory, glucose sustains muscle activity (during ingestion of food) and glycogen is the product of the digestive gland during food assimilation. Our observations of metabolic dynamics during the feeding period allowed us to examine the feeding process. The metabolic activity of the digestive gland was highest 6 h after feeding. This could mean that assimilation, having started 2 h after food intake, peaked 6 h after feeding. Eight hours after feeding, the oxygen consumption rate of the digestive gland decreased and fell to values similar to those recorded for animals subjected to 72 h of fasting.

DAILY VARIATIONS OF OXYGEN-CONSUMPTION AND GLUCOSE HEMOLYMPH LEVEL RELATED TO MORPHOPHYSIOLOGICAL AND ECOLOGICAL ADAPTATIONS OF CRUSTACEA

Abstract 1. 1. Daily variations of oxygen consumption and glucose hemolymph level of seven crustacean species from the continental shelf of the NW Gulf of Mexico were related to the morphophysiological (exoskeleton thickness) and ecological (activity rhythms) adaptations. 2. 2. Metabolic rate and the hemolymph glucose changed with the daily activity patterns observed in the shrimps (Penaeus aztecus: nocturnal; Sicyonia brevirostris: diurnal), the portunid crabs (Callinectes similis, Portunus spinicarpus and P. gibbesii: nocturnal) and the calappids (Calappa sulcata: diurnal; Hepatus ephelyticus: non-selective activity pattern). 3. 3. Rates of oxygen consumption versus glucose concentration were greater in shrimps than in portunids and calappids, and were related to exoskeleton thickness and activity rate. The glucose concentration was considered as the main energy source for the crustacean muscle. 4. 4. Proportion of glucose concentration in relation to oxygen consumption (100%) varies among species, with lowest values for shrimps (55%), against the values recorded in portunid (126%) and calappid crabs (235–423%), indicating the amount of glucose required for chitin synthesis of species with different morphophysiological designs and activity patterns.

Critical dissolved oxygen level to Penaeus setiferus and Penaeus schmitti postlarvae (PL10–18) exposed to salinity changes

Abstract Dissolved oxygen is the most important limiting factor in the intensive cultivation of shrimp species. The critical oxygen level and its effects upon the energy metabolism of postlarvae (PL 10–18 ) of Penaeus setiferus and Penaeus schmitti exposed to diverse salinities were estimated. In both species the critical oxygen level (COL; estimated as the point of inflection of the curve obtained from the relation between the oxygen consumption and the oxygen concentration) was affected by salinity concentration. In P. schmitti , the COL was 5 mg l −1 for salinities of 38, 30, 20 and 15%., and 4.5 mg l −1 for animals kept at 25%. salinity. In P. setiferus , the COL was 5.0 mg l −1 in 37, 30, 25, 20 and 10%. salinities and 4.5 mg l −1 in 15, 5 and 1%. salinities. The energy deficit (END; deficit of metabolic energy) caused by the metabolic oxygen critical concentration was in P. schmitti 13.9% (38%. salinity) and 26.3% (30%. salinity), with intermediate values of 17.2, 22.7 and 24.7% in 25, 20 and 15%. salinities, respectively. For P. setiferus , the END was between 9.1% (l%. salinity) and 25.1% (30%. salinity), with intermediate values for the remaining salinities. Based on these data, the optimum salinity for P. setiferus postlarvae was between 5%. and 15%., and was 25%. for P. schmitti postlarvae. At these salinities the tolerance for the decrease in the oxygen concentration was greater than in the rest of the salinities. The high COL obtained for the postlarvae of both species indicates that the culture conditions must be carefully maintained at this developmental stage to obtain the maximum metabolic performance of the shrimp.

Thermopreference, tolerance and metabolic rate of early stages juvenile Octopus maya acclimated to different temperatures.

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.

Skeleton weight-free oxygen consumption related to adaptations to environment and habits of six crustacean species

Abstract 1. 1. Oxygen consumption in six crustacean species from the continental shelf of the NW Gulf of Mexico was related to the ash free weight per dry weight (afdw) gram of the tissue excluding the exoskeleton, suggesting a close relationship to their life strategies. 2. 2. Dry weight exoskeleton proportion varied among species, with highest values recorded in callapid brachyuran crab species (46.8–52.5%) against the values recorded in portunid crab (45.8–48%) and the shrimp species (26.7–35.7%). 3. 3. Oxygen consumption was related to afdw in each species according to the expression y = ax b , with b values ranging from 0.68 to 2.92. 4. 4. Rates of oxygen consumption per afdw/dw were larger in shrimps than in portunids and callapids, and was related to the morphophysiology and lifestyle of six species described; the former as the morphological design of the exoskeleton versus the muscle content in the species and the latter as the activity rate in the environment. 5. 5. The oxygen extraction efficiency, calculated from oxygen consumption, was higher in the eurytopic species Penaeus aztecus and Callinecies similis than in species restricted to the marine environment, hence considered as a response to environmental fluctuations.

Acclimation of Adult Males of Litopenaeus Setiferus Exposed at 27 °C and 31 °C: Bioenergetic Balance

The reduction of reproductive performance of adult males of Litopenaeus setiferus in captivity has been limiting the massive nauplii production, mainly by lowering the spermatophore attachment success associated with the male reproductive tract degenerative and the male reproductive melanization syndromes. Both syndromes had been related to the captivity and management stress. In this study the bioenergetic alterations were measured after seven days in captivity through absorption efficiency (AE), absorption (A), routine respiratory rate (R ROUT ), apparent heat increment (R AHI ), ammonia excretion (U) and post-prandial nitrogen excretion (PPNE), as indexes of captivity stress in adult males of L. setiferus kept at 27 and 31 °C. All this parameters were integrated through the production equation (P T ) = A − (R AHI + R ROUT + U) At 31 °C, the equation values were higher than those observed at 27 °C, except for R ROUT and ammonia excretion. The amount of energy directed to P T at 31 oC was 1784.99 J g−1 afdw d−1, in contrast with shrimp exposed at 27 °C, where it was 1269.22 J g−1 afdw d−1 (P > 0.05). The O:N ratio obtained was lower than 10, indicating the use of a proteic substrate (P > 0.05). The reduction of the metabolic responses at high temperature shows what the adaptation capability of this shrimp is to tolerate a wide range of temperatures, also reflecting the adaptation mechanisms associated with its distribution in shallow coastal waters.

Oxygen consumption and metabolic amplitude of decapod crustaceans from the northwest continental shelf of the gulf of mexico

1. 1. The aim of this study was to analyse seasonal fluctuations in the respiration rate of pre-adults of Penaeus aztecus, P. setiferus, Scycionia brevirostris and Caltinectes similis, and juveniles of Portunus spinicarpus, Hepatus ephelyticus and Calappa sulcata. 2. 2. A flow respirometer was used to determine the oxygen consumption of these decapods, which was measured every 2hr during a 24 hr cycle in September (27 ± 1C) and in April (22 ± 1C). 3. 3. The respiration rates of seven species revealed uni-, bi- and trimodal patterns during the 24 hr cycle during both seasons. Metabolic amplitude of the shrimp species was reduced by 42% during the coldest months of the year. In winter, when H. ephelyticus was absent, the metabolic amplitude of C. sulcata in that community was two-fold the value recorded in the summer. The metabolic amplitude of portunids and calappid species in summer proved to be significantly reduced (P < 0.05) by 0.72 and 0.91 % in relation to values recorded for P. aztecus and S. brevirostris, respectively. 4. 4. These results suggest a coupling of the respiration rate of seven species with their nictimeral activity rhythms and the seasonal temperature variations that enhance their chances of resource exploitation in avoiding predation and reducing the competitive interactions with co-occurring shelf-faunal components.