Gabriela Gaxiola

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.

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.

Feeding schedule for Penaeus setiferus larvae based on diatoms (Chaetoceros ceratosporum), flagellates (Tetraselmis chuii) and Artemia nauplii

Abstract This paper is the first to present a basic feeding schedule for Penaeus setiferus larvae based on diatoms ( Chaetoceros ceratosporum ), flagellates ( Tetraselmis chuii ) and Artemia nauplii. Growth rate (μm/day), rate of metamorphosis and survival of larvae fed 5 different concentrations of diatoms, flagellates and Artemia nauplii were measured. Survival associated with sudden changes in salinity (quality index QI) of the postlarvae harvested from each treatment was measured. A performance index was calculated from the growth rate, survival and QI. Considering all responses, a feeding schedule for P. setiferus larvae is recommended including a progressive increase in the concentration of diatoms (between protozoea and mysis; 30 and 40 × 10 3 cells/ml, respectively), flagellates (between protozoea and mysis; 2 × 10 3 cells/ml, respectively) and Artemia nauplii (0.5, 1.0 and 1.5 between PZ 3 -M 1 , M 1 -M 2 and M 2 -M 3 , respectively). The increase in concentration of algae and Artemia indicates a pattern of development of the digestive system associated with development of the larvae. This pattern must be considered to improve the production of larvae of this species under controlled conditions.

Effect of a size-based selection program on blood metabolites and immune response of Litopenaeus vannamei juveniles fed different dietary carbohydrate levels

Blood metabolites in wild and seventh-generation cultivated shrimp were measured to determine how size-based selection could alter the nutritional and immunological conditions of Litopenaeus vannamei. Wild L. vannamei juveniles and a sample of seventh-generation cultured shrimp were acclimated under identical conditions. During 55 days, shrimp were fed a high (HCHO: 44%) or a low (LCHO: 3%) carbohydrate diet for 55 days. Wild shrimp showed a direct relation between dietary CHO and lactate, protein and hemocyte levels indicating that dietary CHO was used for protein synthesis via transamination pathways. In seventh-generation cultured shrimp these parameters were inversely proportional to dietary CHO level, indicating the capacity to synthesize protein from dietary CHO was repressed in cultured shrimp. Farmed shrimp showed a limited capacity to respond to LCHO diets demonstrating high protein dependence in their metabolism and immune response. These results demonstrate that during size-based breeding programs other metabolic process than CHO catabolism can be selected. The incapacity of shrimp to use dietary CHO could limit protein reduction of diets and limit the efforts of the shrimp industry to be ecologically and environmentally profitable.

Biofloc Technology (BFT): A Review for Aquaculture Application and Animal Food Industry

© 2013 Emerenciano et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Biofloc Technology (BFT): A Review for Aquaculture Application and Animal Food Industry

Physiological and Biochemical Variations During the Molt Cycle in Juvenile Litopenaeus Vannamei under Laboratory Conditions

Abstract Biochemical changes, specifically in hemocyanin and glucose concentrations in hemolymph, glycogen in the digestive gland, were studied throughout the molt cycle in juveniles of Litopenaeus vannamei in a high salinity condition (36), and related to variations in the osmotic capacity of organisms. Increasing hemolymph volume before molting modifies circulating glucose and hemocyanin concentrations acting on the osmotic capacity. Variations in glucose concentrations are indicators of differential energy requirements throughout the molt cycle. Hemocyanin was used as an indirect indicator of the energy consumed by shrimp in various molt processes that affect the osmotic capacity. The co-variability of these metabolites is the result of the biochemical adaptations displayed by shrimp to maintain homeostasis. Their relation to changes in the osmotic capacity is given as a model to understand and predict events associated with molting under hypo-osmotic conditions.

Physiological and Biochemical Changes of Wild and Cultivated Juvenile Pink Shrimp Farfantepenaeus Duorarum (Crustacea: Penaeidae) During Molt Cycle

ABSTRACT Changes in metabolite levels in hemolymph and hepatopancreas were used as indicators of physiological status of juvenile wild and cultivated Farfantepenaeus duorarum (Burkenroad, 1939), during hyper-osmoregulatory conditions (salinity 22 ppt, 726 mOsm/kg). We analyzed the relationship between biochemical changes of wild and cultivated shrimp at different molt stages by measurement of osmotic capacity, hemocyanin, acylglycerides, cholesterol, glucose, glycogen and total protein. Biochemical analyses of hemolymph (blood) and hepatopancreas showed a decreasing trend in stages closer to molt and an increasing trend before intermolt. Osmotic capacity and blood proteins indicated a significant effect of the molt stage. Stages A, D1′ and D1′″ showed the greatest effect on the biochemical variables. Higher hemocyanin, cholesterol and glycogen concentrations were observed in wild shrimp than in cultivated shrimp. The effect of the molt cycle was associated with changes in cyclic ions and water balance that produced chemical changes in the hemolymph in both wild and cultivated.

The Effect of Copper on the Color of Shrimps: Redder Is Not Always Healthier

The objective of this research is to test the effects of copper on the color of pacific white shrimp (Litopenaeus vannamei) in vivo. Forty-eight shrimps (L. vannamei) were exposed to a low concentration of copper (1 mg/L; experimental treatment) and forty-eight shrimps were used as controls (no copper added to the water). As a result of this experiment, it was found that shrimps with more copper are significantly redder than those designated as controls (hue (500–700 nm): P = 0.0015; red chroma (625–700 nm): P<0.0001). These results indicate that redder color may result from exposure to copper and challenge the commonly held view that highly pigmented shrimps are healthier than pale shrimps.

Seasonal Variability in Trypsin and α-Amylase Activities Caused by the Molting Cycle and Feeding Habits of Juvenile Pink Shrimp Farfantepenaeus duorarum (Burkenroad, 1939)

ABSTRACT In view of the relationship between shifts in diet composition and the activity of digestive enzymes in penaeid shrimp, the present study focused on the analysis of digestive trypsin and &agr;-amylase activities of wild Farfantepenaeus duorarum (Burkenroad, 1939) juveniles and their changes in phenotypic expression, during the molt cycle as endogenous factor and their changes due to different feeding regimes (exogenous factor) in relation with &dgr;13C and &dgr;15N isotopic signature as an index of food assimilation induced by the seasonal availability of food items in the nursery area. Wild juveniles of F. duorarum were captured from April 2007 to February 2008, in the Celestun coastal lagoon, Yucatan, Mexico. Samplings were carried out considering all quarters of the lunar cycle and in each of the recognized seasons for this region: dry, rainy, and the Nortes (North Wind). Copepods and amphipods were the main source of food for juveniles of F. duorarum. Values of &dgr;13C in the muscular tissue were near -20‰ hence the feeding regime of F. duorarum in the lagoon was composed by material of marine origin. Isotopic signature differences were found between the three annual seasons. It is an opportunist generalist organism that is located in the 4th trophic level. The digestive enzymatic activities of both trypsin and &agr;-amylase in fresh hepatopancreas tissue showed an interaction between season and molt stages (p < 0.05). Activity of the trypsin was highest during the Nortes at molt stage C (140 mU mg-1 HP) and activity of &agr;-amylase was higher in the Nortes at stage B2 (674 mU mg-1 HP). The amylase/trypsin ratio also showed significant interaction between season and molt stages (p < 0.05), with higher values in premolt stages during the rainy and Nortes seasons. Isoforms of these digestive enzymes differed in expression according to the molt stage and also to the season with expression generally being greater at stage C.