Effect of salinity and body weight on ecophysiological performance of the Pacific white shrimp (Litopenaeus vannamei)

Ecophysiological responses of Litopenaeus vannamei were evaluated as functions of environmental salinity and animal size. Growth rate, routine metabolic rate, limiting oxygen concentration, and marginal metabolic scope were determined for L. vannamei acclimated to, and tested at, salinities of 2, 10, and 28 ppt, all at 28 °C. Routine metabolic rate (RMR), estimated as oxygen-consumption rate per unit body weight for fasted, routinely-active shrimp, was independent of salinity but decreased with increasing shrimp weight. Limiting oxygen concentration for routine metabolism (LOCr) decreased with increased shrimp weight for the 10 and 28 ppt treatments, but not for the 2 ppt treatment. Marginal metabolic scope (MMS = RMR/LOCr) also decreased with increasing shrimp weight and was independent of salinity. Growth rate was significantly less at 2 ppt than at either 10 or 28 ppt, which gave similar growth rates.     

Thermal preference,tolerance and oxygen consumption of adult white shrimp Litopenaeus vannamei (Boone) exposed to different acclimation temperatures

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 90.0 mg O₂ kg⁻¹ h⁻¹ wet weight (w.w.) as the acclimation temperature increased from 20 to 32 °C. The range of temperature coefficient (Q₁₀) 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.     

Whiteleg shrimp (Litopenaeus vannamei, Boone, 1931) isotrypsins: Their genotype and modulation

Based on information about isotrypsins found by substrate-SDS-PAGE in the whiteleg shrimp Litopenaeus vannamei and their segregation, an explanation for the presence of three-trypsin phenotype was sought. Isotrypsins A, B, and C depend on two loci: locus β, which is homozygous, yielding isoenzyme C, and locus α, which is heterozygous, yielding isoenzymes A and B. Segregation in locus α in offsprings from 20 families was analyzed. Results demonstrated that isotrypsins were segregated according to Mendelian rules, and hence, external stimuli did not affect the phenotype. To corroborate this, the phenotype was evaluated in relation to changes in trypsin activity during a digestion process. Trypsin phenotypes found in shrimp feces were also analyzed. Results showed that phenotypes were conserved by individuals. Therefore, changes in trypsin activity found in previous investigations must be related to changes in the concentration of the established isotrypsins.     

An energetic and conceptual model of the physiological role of dietary carbohydrates and salinity on Litopenaeus vannamei juveniles

We are reporting results directed to explain the relation between carbohydrates (CHO), protein metabolism, and the energetic balance of Litopenaeus vannamei juveniles. The interaction of dietary CHO and salinity was measured to try to understand the relation between osmotic control and metabolism, both from a biochemical and energetic point of view. Two experiments were done. In the first experiment, shrimp were fed with 0%, 5%, 33%, and 61% CHO and maintained at 15‰ and 40‰ salinity. Glucose, lactate protein, hemocyanin, ammonia concentration, and osmotic pressure were measured in blood. Digestive gland glycogen (DGG) was measured also. In the second experiment, shrimp were fed with 0% and 38% dietary CHO and maintained at 15‰ and 40‰ salinity. From that shrimp, absorbed energy (Abs) was calculated as: Abs=respiration (R)+ammonia excretion (U) and production (P); assimilated energy (As) was calculated as the product of R×P. Osmotic pressure, hemocyanin, protein, lactate, and blood ammonia increased with the reduction in dietary CHO. In contrast, an increase in blood glucose was observed with an increase in dietary CHO. Digestive gland glycogen (DGG) increased following a saturation curve with a DGG maximum at 33% dietary CHO. Blood metabolites of fasting and feeding shrimp showed the same behavior. Energy balance results showed that shrimp maintained in low salinity and fed without CHO waste more energy in U production than for shrimp maintained in high salinity and fed with high CHO levels. Notwithstanding, the production efficiency was higher in shrimp fed without CHO than that observed in shrimp fed with high CHO independent of salinity. A scheme trying to integrate the relation between CHO and protein metabolism and the way in which both are modulated by salinity is presented. From published and present results, there are two factors that apparently control the use of high dietary CHO levels; α-amylase enzyme-dietary CHO level capacity and glycogen saturation in DG. Production of glucose is limited in shrimp because of saturation of α-amylase when shrimp are fed with diets above 33% CHO. This is the first control point of starch metabolism. The digestive gland is saturated with glycogen in shrimp fed with dietary CHO levels >33%. This is apparently the second control point of CHO metabolism that limits growth rate in such conditions. The high metabolic cost related to high CHO diets could explain why shrimp are well adapted to use protein as a source of energy.     

Combined effects of temperature and salinity on critical thermal minima of pacific white shrimp Litopenaeus vannamei (Crustacea: Penaeidae)

Critical thermal minima (CTMin) were determined for the Pacific white shrimp Litopenaeus vannamei juveniles from four different acclimation temperatures (15, 20, 25, and 30 °C) and salinities (10‰, 20‰, 30‰, and 40‰). The lowest and highest CTMin of shrimp ranged between 7.2 °C at 15 °C/30‰ and 11.44 °C at 30 °C/20‰ at the cooling rate of 1 °C h⁻¹. Acclimation temperature and salinity, as well as the interaction of both parameters, had significant effects on the CTMin values of L. vannamei (P<0.01). Yet, the results showed a much more profound effect of temperature on low thermal tolerance of juveniles. Only 40‰ salinity had an influence on the CTMin values (P<0.01). As the acclimation temperature was lowered from 30 to 15 °C thermal tolerance of the shrimp significantly increased by 3.25–4.14 °C. The acclimation response ratio (ARR) of the Pacific white shrimp exposed to different combinations of salinity and temperature ranged between 0.25 and 0.27. When this species is farmed in sub-tropical regions, its pond water temperature in the over-wintering facilities (regardless of the water salinity level) must never fall below 12 °C throughout the cold season to prevent mortalities.     

A multi-season survey for infectious myonecrosis in farmed shrimp, Litopenaeus vannamei, in Pernambuco, Brazil

Infectious myonecrosis (IMN), caused by infectious myonecrosis virus (IMNV), is the disease of greatest impact on shrimp farming in the northeast region of Brazil. The occurrence of IMN remained restricted to northeastern Brazil until 2006, when its presence was also confirmed in Indonesia. To determine the occurrence and evolution of IMN in Litopenaeus vannamei farmed along the coast of the state of Pernambuco, Brazil, histopathological examinations were performed on 60 samples collected from four farms in both predominant seasons in the northeastern region: dry and wet seasons. Samples made up of ten specimens were collected monthly from each pond. Histopathological results were associated to wet-mount exams and rearing performance data. Lesions suggestive of IMN (coagulative necrosis, hemocytic infiltration in the musculature, ectopic spheroids in the lymphoid organ) were identified in all the farms, with a higher occurrence during the dry season. Longer rearing periods and higher stocking densities were the variables with the most significant influence (p < 0.05) in the occurrence of IMN.     

Effects of temperature, salinity, and irradiance on the growth of the dinoflagellate Akashiwo sanguinea

The effects of temperature, salinity, and irradiance on the growth of the dinoflagellate Akashiwo sanguinea were examined in the laboratory. The irradiance at the light compensation point (I₀) was 14.40 μmol m^− 2 s^− 1 and the irradiance at growth saturation (I_s) was 114 μmol m^− 2 s^− 1. We exposed A. sanguinea to 48 combinations of temperature (5-30 °C) and salinity (5-40) under saturating irradiance; it exhibited its maximum growth rate of 1.13 divisions/day at a combination of 25 °C and salinity of 20. A. sanguinea was able to grow at temperatures from 10 to 30 °C and salinities from 10 to 40. This study revealed that A. sanguinea was a eurythermal and euryhaline organism; in Japan it should have formed blooms in early summer, when salinity was relatively low. In addition, it was noteworthy that A. sanguinea had markedly cold-durability, retaining the motile form of vegetative cells for more than 50 days at 5 °C and at salinities of 25-30.     

Effect of Lactobacillus plantarum isolated from digestive tract of wild shrimp on growth and survival of white shrimp (Litopenaeus vannamei) challenged with Vibrio harveyi

Two hundred and two strains of lactic acid bacteria (LAB) isolated from digestive tracts of cultivated and wild adult shrimp, including Litopenaeus vannamei, Metapenaeus brevicornis and Penaeus merguiensis were selected based on their antibacterial activity against Vibrio harveyi. LAB strain of MRO3.12 exhibiting highest reduction of V. harveyi was identified as Lactobacillus plantarum MRO3.12 based on the nucleotide sequence of its 16S rDNA, which showed 99% (780/786 bp) homology to L. plantarum strain L5 (GenBank accession number DQ 239698.1). Co-cultivation of V. harveyi and L. plantarum MRO3.12 showed complete reduction of V. harveyi at 24 h under aerobic and anaerobic conditions, whereas L. plantarum increased from 5.29 to 9.47 log CFU ml⁻¹. After 6-week feeding trial with L. plantarum supplemented diet, white shrimp (L. vannamei) exhibited significant differences (p < 0.05) in relative growth rate (% RGR), feed conversion ratio (FCR) and survival compared to the control group fed with non-supplemented diet. LAB-fed group showed 98.89% survival, whereas only 68.89% survival was observed in the control group. LAB from the digestive tract of probiotic-fed shrimp showed higher level of 5.0 ± 0.14 log CFU/g than the non-supplemented ones (3.34 ± 0.21 log CFU/g). However, total bacterial and non-fermenting vibrios counts decreased in shrimps fed on L. plantarum. Ten days after infection with V. harveyi (5.3-5.5 log CFU ml⁻¹), significant survival (p < 0.05) of 77% was observed in LAB supplemented shrimp, while only 67% survival was observed in the control.     

Identification of a type of human IgG-like protein in shrimp Penaeus vannamei by mass spectrometry

Recently, infectious diseases have delayed the growth of shrimp aquaculture. Interest has been focused on immune molecules and defense mechanisms to reduce these diseases in shrimp aquaculture. In invertebrates, various immunoglobulin superfamily (IgSF) molecules have been characterized in body tissues and fluids, which play a significant role in innate defense. In the current study, we found that a protein in shrimp serum, referred as an IgG-like protein, could be reacted with goat anti-human IgG, specifically. The IgG-like protein was purified from the serum of shrimp Penaeus vannamei by affinity chromatography using CNBr-activated sepharose 4B. The purified protein was subsequently analysed using one-dimensional sodium sulphate-polyacrylamide gel electrophoresis (1-DE), two-dimensional sodium sulphate-polyacrylamide gel electrophoresis (2-DE) and immunoblotting. Furthermore, matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry and quadrupole time-of-flight (Q-TOF) tandem mass spectrometry methods were used for peptide mass fingerprint (PMF) and sequencing of the protein, respectively. Sequence information and PMF queried against the NCBI database confirmed the identity of the protein as hemocyanin. Conserved domain search showed that there was an Ig-like conserved domain of 252 amino acid residues in the C-terminus of arthropoda hemocyanins. In addition, four and one conserved regions were found between hemocyanin and human Ig heavy chain and Ig kappa chain, respectively. These results indicate that in addition to copper-binding domains hemocyanin has an Ig-like conserved domain, which would confer some new functions to multifunctional respiratory pigment of crustaceans.     

The effects of temperature changes on the oxygen consumption of juvenile Chinese shrimp Fenneropenaeus chinensis Osbeck

The effects of temperature changes on oxygen consumption of Chinese shrimp (Fenneropenaeus chinensis Osbeck) were studied. The response of oxygen consumption to a temperature rise was conformed to partial metabolic compensation. No compensatory response was observed at lower temperature. A sudden temperature increase by 12 °C resulted an overshoot in oxygen consumption in shrimp adapted to 19 °C, while a sudden decrease by 12 °C in shrimp adapted to 19 °C resulted in an undershoot in oxygen consumption. The shrimp adapted to 31 °C responded with an undershoot in oxygen consumption when a sudden temperature drop by 12 °C occurred. But overshoot in oxygen consumption did not occur when the shrimps were transferred back from 19 to 31 °C. The amplitude of oxygen consumption was reduced in shrimp during the process of acclimation to the temperature diel fluctuation. After the shrimp had adapted to the temperature fluctuation, the daily mean oxygen consumption of shrimp at diel temperature fluctuation from 24 to 30 °C was significantly lower than those adapted to the constant temperature at 27 °C (P<0.05). The decrease in metabolic rate may account for the increase in the growth rate of shrimp at a diel fluctuating thermal regime.     

Effect of the addition of four potential probiotic strains on the survival of pacific white shrimp (Litopenaeus vannamei) following immersion challenge with Vibrio parahaemolyticus

Four bacterial strains isolated from the gastrointestinal tract of adult shrimp Litopenaeus vannamei, Vibrio alginolyticus UTM 102, Bacillus subtilis UTM 126, Roseobacter gallaeciensis SLV03, and Pseudomonas aestumarina SLV22, were evaluated for potential use as probiotics for shrimp. In vitro studies demonstrated antagonism against the shrimp-pathogenic bacterium, Vibrio parahaemolyticus PS-017. Feeding shrimp with diets containing the potential probiotics showed the best feed conversion ratio in comparison with the control groups. After feeding with the potential probiotics for 28 days, challenge by immersion indicated effectiveness at reducing disease caused by V. parahaemolyticus in shrimp.     

Effects of salinity, temperature and pH on the survival of the nemertean Procephalothrix simulus Iwata, 1952

The salinity, temperature and pH tolerance of Procephalothrix simulus Iwata, 1952, were experimentally studied. In hypo-media, the nemerteans could survive 96 h in 3.3‰ solution at 10 °C (median lethal salinity [LS₅₀] was not determined at this temperature), and 96 h LS₅₀ were 7.3‰ and 13.5‰ at 20 °C and 30 °C, respectively. In hyper-media, 96 h LS₅₀ values were 53.9‰, 47.1‰ and 41.4‰ at 10 °C, 20 °C and 30 °C, respectively. The trend of body weight changes in diluted media indicated that this nemertean is a volume regulator. During a 96-h exposure in media at 0 °C, worms were thanatoid but could recover if the temperature was gradually elevated to 20 °C. In thermal tolerance experiments, the nemertean survived 96 h in seawater of 30 °C, and worms suffered high mortalities when the temperature exceeded 32 °C. Present results suggest that the interaction of temperature and salinity on the lethal effects on P. simulus is significant (P < 0.05). Elevated temperature (range 10-30 °C) decreased the worm's solute tolerance, and elevated salinity (range 18-38‰) decreased the worm's thermal tolerance. The survival pH level for this nemertean ranged from 5.00 to 9.20.     

Development and mortality of the first naupliar stages of Eurytemora affinis (Copepoda, Calanoida) under different conditions of salinity and temperature

As a prevalent species complex in temperate estuaries and salt marshes of the Northern Hemisphere, populations of Eurytemora affinis that inhabit these environments must be adapted to salinity fluctuations. Some populations have invaded freshwater environments. In this work, we focus on the combined effects of temperature and salinity fluctuations on mortality rates and development time of the first naupliar stages under starvation. Two temperatures (10 and 15 °C) and eight salinities, ranging from 0 to 35 psu are investigated. We show (i) that among all experimental conditions the optimal temperature and salinity for naupliar survival and development are 15 psu and 15 °C, and (ii) that only the most extreme salinities (i.e. 0 and 35 psu) have a negative effect on naupliar survival. Nauplii develop faster and reach a higher developmental stage at 15 than at 10 °C, independent of salinity. The relevance of this metabolic adaptive pattern is discussed in the general framework of in situ behavior, tidal forcing and biogeographic variability, as well as the potential sources of the observed individual variability.     

Combined effect of salinity and temperature on Spirorbis spirorbis L. and Circeus spirillum L. larvae from the White Sea

The combined effect of salinity and temperature on Spirorbis spirorbis L. and Circeus spirillum L. larvae from the White Sea was studied in the laboratory experiments. In the White Sea, S. spirorbis is distributed through the depth of 1-20 m and is affected by all varieties of fluctuations in salinity and temperature. C. spirillum lives in more wide range of depths 1-55 m and is more stenohaline. S. spirorbis larvae are sufficiently more resistant to the low salinity (10‰) than C. spirillum larvae. Both species are stenothermic. Highest survivorship of S. spirorbis larvae was marked under 5 °C in all experimental salinities. Under temperature treatments of 10-15 °C, the larval survivorship was sufficiently restricted in all salinities. Highest survivorship of C. spirillum larvae was also marked under 5 °C but in more narrow salinity range.The number of larvae undergoing metamorphosis in both species was very low, only about 10% of the total number. Highest number of successful attachments in both species was marked in high salinities (25-30‰) and does not exceed 25% of survivors. Experimental data suggests that salinity and temperature affect directly general survivorship of the larvae and secondary-attachment and metamorphosis processes.     

The combined influence of sub-optimal temperature and salinity on the in vitro viability of Perkinsus marinus, a protistan parasite of the eastern oyster Crassostrea virginica

Perkinsus marinus is a major cause of mortality in eastern oysters along the Gulf of Mexico and Atlantic coasts. It is also well documented that temperature and salinity are the primary environmental factors affecting P. marinus viability and proliferation. However, little is known about the effects of combined sub-optimal temperatures and salinities on P. marinus viability. This in vitro study examined those effects by acclimating P. marinus at three salinities (7, 15, 25 ppt) to 10 °C to represent the lowest temperatures generally reached in the Gulf of Mexico, and to 2 °C to represent the lowest temperatures reached along the mid-Atlantic coasts and by measuring changes in cell viability and density on days 1, 30, 60 and 90 following acclimation. Cell viability and density were also measured in 7 ppt cultures acclimated to each temperature and then transferred to 3.5 ppt. The largest decreases in cell viability occurred only with combined low temperature and salinity, indicating that there is clearly a synergistic effect. The largest decreases in cell viability occurred only with both low temperature and salinity after 30 days (3.5 ppt, 2 °C: 0% viability), 60 days (3.5 ppt, 10 °C: 0% viability) and 90 days (7 ppt, 2 °C: 0.6 ± 0.7%; 7 ppt, 10 °C: 0.2 ± 0.2%).     

Effects of temperature and salinity on the standard metabolic rate (SMR) of the caridean shrimp Palaemon peringueyi

The standard metabolic rate (SMR) of the caridean shrimp Palaemon peringueyi to changes in temperature (15-30 °C), salinity (0-45‰) and a combination thereof was investigated. The rate of oxygen consumption of the shrimp was determined using a YSI oxygen meter. At a constant salinity of 35‰ the respiration rate of P. peringueyi increased with an increase in temperature and ranged between 0.260 and 0.982 μl O₂ mg wwt^− 1 h^− 1. The Q₁₀ value over the temperature range 15-25 °C was estimated at 3.13. At a constant temperature of 15 °C the respiration rate of P. peringueyi also increased with an increase in salinity and ranged between 0.231 and 0.860 μl O₂ mg wwt^− 1 h^− 1. For combination experiments the absence of any significant difference in the respiration rate of P. peringueyi at the four temperatures over the salinity range 15-35‰ suggests that the shrimp is well adapted to inhabiting environments characterised by variations in salinity and temperature such as those encountered within the middle and lower reaches of permanently open estuaries with substantial freshwater inflow. On the other hand, the total mortality of the shrimp recorded at salinities < 5‰ at all four temperatures suggests that the upper distribution of the shrimp may reflect physiological constraints. Similarly, the increase in the respiration rate of the shrimp at the four temperatures at salinities > 35‰ suggests that the shrimp may experience osmotic stress in freshwater deprived permanently open and intermittently open estuaries where hypersaline conditions may develop.     

Biomarker responses of the estuarine brown shrimp Crangon crangon L. to non-toxic stressors: Temperature, salinity and handling stress effects

Biochemical biomarkers in common estuarine species, such as the brown shrimp Crangon crangon, have the potential to provide early warning of contaminant exposure from field collected samples and through the development of in situ tests. The biomarkers acetylcholinesterase (AChE), lactate dehydrogenase (LDH) and glutathione S-transferase (GST) have been shown to provide evidence of exposure to contaminants in a number of species and field situations. As they may naturally respond to the marked physicochemical changes found in estuaries (thus confounding contaminant-induced effects), this work aims to determine the effects of salinity, temperature and handling stressors on these biomarkers in C. crangon.AChE recovery in field-collected shrimp transplanted to clean laboratory conditions suggests the presence of inhibiting factors at the sampling site (River Minho estuary). Maintenance time in stock tanks had effects that led to the choice of a minimum 15-day maintenance period of C. crangon in the laboratory before subsequent use of the enzymes as effect criterions in toxicity assays. Field levels of biomarker activity were unaffected following field-laboratory transportation of C. crangon, making this factor unlikely to jeopardize detection of contaminant associated effects. LDH levels were significantly lower under conditions that mimic a diurnal salinity fluctuation, increasing under low salinity conditions; this potentially indicates increased energy costs associated with raised osmoregulatory demands. It is recommended that a lower limit to field exposure of in situ tests should be based on salinity. Higher temperatures led to higher AChE activities and this is in agreement with the existing evidence of increases of endogenous AChE levels as a function of temperature (within a certain range). To avoid misinterpretation of biomarker responses, studies such as this are an important contribution to the establishment of reference activity levels against which biomarker changes can be estimated and are therefore essential preliminary steps in the development of in situ bioassays using biomarkers.     

Effects of salinity and temperature on the survival and byssal attachment of the lion's paw scallop Nodipecten nodosus at its southern distribution limit

The lion's paw scallop, Nodipecten nodosus, is subject to wide temperature variations on seasonal and short-term scales, and may be exposed to low-salinity events, caused by oceanographic and meteorological processes at its southern distribution limit (Santa Catarina State, Brazil). Such variations may have important implications on the distribution and on aquaculture site selection. The upper and lower temperature tolerances and the percentage of byssal attachment at different temperatures (11 to 35 °C) were studied for spat, juvenile and adult scallops. The lethal and sublethal effects of reduced salinity (13‰ to 33‰) on spat, juvenile and adult scallops were studied at ambient temperature (23.5 °C) and on spat also at low (16 °C) and high (28 °C) temperatures during 96-h bioassays. In addition, the influences of short exposure (1 h) to low salinity (13‰ and 17‰) at different temperatures (16 and 28 °C), and the effects of exposure (2 and 4 h) to high temperature (33 °C) at ambient salinity (33‰) were studied. N. nodosus is a moderately eurythermal but stenohaline tropical species, adults having lower tolerance to high temperature and low salinity than spat. Lethal temperatures for a 48-h exposure (LT₅₀) were 29.8 °C for adult and juveniles, and 31.8 °C for spat. Maximum rate of byssal attachment occurred in a narrower temperature range for juveniles and adults (23 to 27 °C) than for spat (19 to 27 °C), which are suggested as the optimum ranges of temperatures for growth. Lethal salinities (LC₅₀) for a 48-h exposure at ambient temperature were 23.2‰, 23.6‰ and 20.1‰ for adults, juveniles and spat, respectively, but the percent byssal attachment was significantly reduced below salinities of 29‰ indicating that scallops were physiologically stressed. A 1-h exposure to 17‰ was lethal to spat at 28 °C, but at 16 °C there was a 28.5% survival, 96 h after the exposure. Temperatures and salinity in coastal areas of southern Brazil can reach levels leading to sublethal effects, and in some sites, it may surpass the limits of tolerance for the survival of the species.