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1.
The stress responses in early growth stages of the wedge sole have been studied to determine whether the high cortisol levels described in juvenile fish are present from early developmental stages. Whole‐body cortisol, glucose and lactate contents, as well as biometric parameters in wedge sole larvae were measured at three different stocking densities. Stocking density affected growth‐related variables significantly, and larvae in lower stocking densities grew faster. Survival did not significantly differ among treatments. At hatching, the whole‐body cortisol concentration was 0.33 ± 0.01 ng g?1 and varied significantly from 0 to 30 days after hatching (DAH) for each stocking density, though values remained stable for the remaining time in the low‐stocking density group. These hormone levels rose significantly (5.17 ± 2.43 to 22.10 ± 4.95 ng g?1) at the end of the experiment, depending directly on the stocking density. Glucose and lactate‐body concentrations did not vary among treatments. We conclude that the stress responses of wedge sole larvae are detectable from 45 DAH and that stocking density already can be a stressor at that age. As described for juvenile stage, cortisol content values in wedge sole larvae under non‐stressful conditions are one of the highest among those reported in the literature. The captivity conditions could be responsible for this apparently stressful situation, though those values also could be normal in wild specimens.  相似文献   

2.
Physiological responses to a high stocking density were tested in juvenile wedge sole Dicologoglossa cuneata (Moreau). Fish were kept at low (1 kg m−2), medium (3 kg m−2) and high (9 kg m−2) stocking densities for 22 days. No differences in the weight, length, survival and hepatosomatic index were observed among treatments. Basal plasma cortisol and osmolality were found to be directly and positively related to stocking density. A mild increase in plasma glucose was seen at medium density, and plasma protein was elevated at medium and high densities. The liver glucose and glycogen content was inversely related to stocking density. The liver triglyceride level was significantly elevated at the highest density, and the α-amino acid content decreased at the highest density. In muscle, glucose levels were significantly higher in fish kept at the lowest density; the α-amino acid content was elevated in fish kept at high density. In conclusion, plasma cortisol levels indicated an increasing stress level depending on the culture density, but significant changes in energy reserves did not occur in tissue (mainly liver and muscle glycogen and glucose reserves were significantly affected).  相似文献   

3.
Fish held at high stocking densities are generally exposed to chronic stress situations that impose severe energy demands and may predispose the fish to infection. Senegalese sole Solea senegalensis (Kaup) juveniles (78.8±18.9 g body weight) were maintained at low (LSD; 4 kg m?2 at the end of the experiment), medium (MSD; 9 kg m?2) and high (HSD; 14 kg m?2) stocking densities during a period of 63 days. Although disease outbreaks were observed in fish reared at HSD, growth and food consumption did not vary among different treatments. Results from plasma cortisol and free amino acids (FAAs) showed significant differences among different rearing densities pointing to HSD as stressful rearing condition. However, higher plasma glucose and osmolality levels indicated that fish held at MSD may also be under stress. The higher usage of FAAs from the HSD group may be due to the higher demand for energy production in order to cope with stressful rearing conditions, higher rate of protein synthesis or due to synthesis of other important metabolites related to stress response. Therefore, results from the present study point out to HSD as a stressful rearing condition and suggest that crowding stress may affect amino acid requirements.  相似文献   

4.
This study investigated the effects of different stocking densities on growth and serum concentrations of thyroid hormones and cortisol in Amur sturgeon, Acipenser schrenckii. Fish were reared at low, medium, and high stocking densities (initial experimental densities were 0.30, 0.75, and 1.78 kg m−2, respectively) for 70 days. The results showed that high stocking density had negative effects on growth and feeding efficiency, and altered serum levels of thyroid hormones and cortisol in Amur sturgeon. A significant decrease in specific growth rate was observed as stocking density was increased. The feeding rate decreased significantly in the medium and high density groups, indicating that high stocking density reduced the food consumption of sturgeon. Food conversion ratio increased with increasing stocking density, suggesting that high stocking density might inhibit fish growth through decreasing food conversion efficiency. Serum concentrations of total triiodothyronine, free thyroxine, and free triiodothyronine were inversely related to stocking densities, whereas serum total thyroxine level of sturgeon stocked at different densities remained stable. Also, higher stocking density resulted in an elevation of serum cortisol level, indicating that the sturgeon stocked at the higher density experienced density-dependent physiological stress. These results suggest growth suppression caused by high stocking density might be related to both crowding stress and the declines in peripheral circulating levels of thyroid hormones, as well as associated with the reductions in both food consumption and food conversion efficiency.  相似文献   

5.
Two consecutive experiments were conducted to investigate the physiological responses of Jade perch (Scortom barcoo) to different stocking densities over a 30‐day period and to stress resulting from food deprivation over a 10‐day period. Groups of Jade perch were reared in recirculating tanks at three stocking densities (120, 180 and 270 fish m?3). Fish were weighed and blood samples were taken at the beginning of the experiment (P1) and after 30 days (P2). Feeding was then stopped and fish were sampled again 10 days later (P3). Blood samples were analysed for serum level of cortisol (COR), glucose (GLU), total protein (TP), triglycerides (TG), lysozyme (LYS) activity and alkaline phosphatase (ALP) activity. Significant changes were observed in average body weight and serum COR, TG, LYS and ALP activity in response to stocking density. No significant difference was found between stocking density treatments concerning the serum TP and GLU. The results showed that fish performed better at a stocking density of 180 fish m?3. Food deprivation for 10 days resulted in significant changes in ALP activity and LYS activity, TP and GLU concentrations and final average body weight but not in COR and TG levels.  相似文献   

6.
The sea cucumber Apostichopus japonicus is an economic species mainly distributed along the coast of northern China, south‐eastern Russia, Japan, Republic of Korea and Democratic People's Republic of Korea. Aquaculture industry of A. japonicus has been facing severe challenge of high temperature. In this study, we studied the mRNA expression profiles of eight key metabolic enzymes involved in carbohydrate and amino acids metabolism in A. japonicus under heat stress. The expression of hexokinase, pyruvate kinase and malate dehydrogenase showed downregulated response to heat stress, while the expression of glutamate dehydrogenase, alanine transaminase and branched‐chain aminotransferase showed upregulated response. In addition, the expression of lactate dehydrogenase and glutamate synthase showed no significant difference. We also applied 1H NMR‐based metabolomics to investigate metabolic changes in the intestine tissue of A. japonicus under heat stress, the results of which revealed nine increased and 10 decreased metabolites in the heat stress group. These response genes and metabolites have potential to become markers for identifying severity of heat stress. More importantly, our findings suggest significant links between gene expression and metabolites changing, highlighting regulation networks of carbohydrate and amino acid metabolism in heat‐stressed A. japonicus.  相似文献   

7.
An experimental trial was conducted for 90 days to evaluate the growth performance, immunophysiological response of GIFT strain of Tilapia in biofloc‐based rearing system and to assess the relative percentage survival in 3 days after challenging with the virulent strain of Aeromonas hydrophila. Fingerlings with an average body weight 0.98 ± 0.06 g were stocked in triplicate at different stocking densities of 200 (SD1), 250 (SD2), 300 (SD3) and 350 (SD4) m?3 in biofloc‐based treatments and 150 (C) m?3 in control (clear water). Biofloc‐based units (SD1 and SD2) obtained significantly better (P < 0.05) growth performances at the end of the experimental period. Mean body weight of fish in biofloc‐based units showed a decreasing trend with increase in stocking density with 100% survival in all units including control. The stress parameters were significantly lower in biofloc‐based rearing units especially in treatments SD1 and SD2 as compared to the control. The fish from the biofloc‐based units (SD1 and SD2) possessed significantly (P < 0.05) higher immune status as compared to control and other biofloc treatments in terms of respiratory burst, serum lysozyme and myeloperoxidase activity. Relative survival percentages were significantly better in biofloc treatments with highest in SD1 and SD2 (83.33%) after challenge study. GIFT strain of Tilapia at higher stocking densities 200–250 nos m?3 can be taken as optimum stocking density whereas higher stocking densities up to 350 nos m?3 can be reared in the biofloc systems without compromising the growth and immunity.  相似文献   

8.
This study aimed to assess the effects of stocking density on the growth, antioxidant status, and physiological response of juvenile turbot. Turbot (average initial weight 70.0 ± 5 g) were reared at three different initial densities (low density [LD], 5.13 ± 0.03 kg/m2; medium density [MD], 7.71 ± 0.11 kg/m2; and high density [HD], 10.8 ± 0.12 kg/m2) for 80 d. At the end of this trial, the final densities were 13.2 ± 0.10, 19.9 ± 0.15, and 25.7 ± 0.12 kg/m2 in the LD, MD, and HD groups, respectively. The growth performances were adversely influenced by a high stocking density. Levels of cortisol, glucose, cholesterol, triglyceride, glutamate pyruvate transaminase, and glutamate oxalate transaminase in the plasma significantly increased in HD treatment. Results of oxidative stress analyses showed that there was a clear decrease in superoxide dismutase, glutathione peroxidase, catalase, glutathione, and total antioxidant capacity, and an obvious increase in malondialdehyde in plasma and/or liver of turbot reared in HD group (P < 0.05). Overall, the results indicated that increasing stocking density reduced the growth performance, modulated the physiological response, and induced oxidative stress in turbot.  相似文献   

9.
In this work, the effects of the stocking density on the physiological stress and biometric features of the brill were studied. No differences for survival rate, feeding efficiency, Conversion Index and feeding intake were not detected among the treatments. The growth rate showed an inverse lineal relationship with stocking density, and there were no significant differences between specimens cultured at medium and high density. Plasma cortisol and osmolality were directly related to stocking density, though the former was not significantly different among the treatments. Plasma glucose and lactate significantly increased, while stocking density rose. Triglycerides enhanced significantly in MSD and HSD with respect to LSD cultured specimens. Differences among treatments were not registered for hepatic glucose, triglycerides and amino acids. However, glycogen showed an inverse lineal relationship with respect to stocking density with significant differences between low and high stocking density. Several lipid classes were different among the treatments, with the high-density specimens presenting the highest values. Liver total lipid was not significantly different among the treatments, but total polar lipid was higher in high density. Muscle metabolites did not vary significantly among the treatments. Concluding, the brill showed a clear secondary response to crowding stress through the mobilization of energy substrates to tissues, evoking a reduction in the growth and other biometric parameters.  相似文献   

10.
In the present study, we investigated the effects of green light illumination on antioxidant systems and immunity in the olive flounder Paralichthys olivaceus. Fish at three different stocking densities (900, 1350, and 2250 fish per 8-ton tank) were compared. The effects of green light illumination were assessed by measuring survival rates, mRNA expression activity of antioxidant enzymes (superoxide dismutase and catalase), an oxidative stress-related parameter (hydrogen peroxide, H2O2), and immune-related parameters (lysozyme and melatonin). Overall, fish survival rates decreased over the 30-day period of the experiment, but survival rates were significantly higher among the groups of fish exposed to green light. In high stocking densities groups, mRNA levels and activities of antioxidant enzymes and H2O2 concentrations had increased at 30 days; however, in fish under green light conditions, significantly lower levels of antioxidant enzyme expression were observed. By contrast, parameters indicating immune responses decreased in high stocking densities groups, although in fish under green light treatment, significantly higher levels of immune response were observed. A comet assay revealed that a high stocking density increased the rate of nuclear DNA damage; however, treatment with green wavelength light reduced the frequency of damage. These results indicate that although high density induces oxidative stress and reduces immune system responses in olive flounder, green wavelength light prevents oxidative stress and boosts the immune system.  相似文献   

11.
Stocking density, representing a potential source of long‐term stress, is widely recognized as a critical factor in aquaculture husbandry. Atlantic salmon were reared at low‐density (LSD, ~9.80–18.41 kg m?3, initial to final density), medium‐density (MSD, ~19.62–36.96 kg m?3) and high‐density (HSD, ~28.79–53.54 kg m?3) stocking levels for 66 days to investigate the stress‐induced changes in fish growth and welfare. At the end of the trial, the salmon in HSD group showed significant lower final weight and higher ration level than those in MSD and LSD groups (P < 0.05). The salmon farmed in LSD group had higher special growth rate (SGR) and lower feed conversion ratio (FCR) (P < 0.05). However, stocking density could not affect the mortality, condition factor and coefficient of variation of salmon. The pectoral fin index of salmon in LSD group was significantly higher than that in HSD group (P < 0.05). Fifteen haematological and serum parameters were detected to assess the stress and welfare levels of salmon. The salmon farmed in HSD group had higher glucose (GLU) level and lower Cl?, haemoglobin (HGB) and red blood cell (RBC) concentrations (P < 0.05). Contrast to the pattern of superoxide dismutase (SOD) activity, the cortisol, maleic dialdehyde (MDA) and alkaline phosphatase (ALP) levels of HSD group were higher than those in other two groups (P < 0.05). All these findings will provide a reference for selecting suitable stocking density in Atlantic salmon farming industry.  相似文献   

12.
Atlantic salmon, Salmo salar L., and brown trout, Salmo trutta L., fry were point and scatter stocked in the early part of June at densities of 63–263 fry 100 m−2 per species in the River Viantienjoki, a small river in northern Finland, and their population densities were assessed in late summer. Both species were always stocked together in similar quantities. Point stocking was used in the first 2 years and scatter stocking in the following 2 years. In point stocking, there was no correlation between the distance from the stocking sites (maximum = 250 m) and parr density in census sites ( r = −0.013 and 0.019 for brown trout and Atlantic salmon, respectively). The stocking density of fry did not influence parr density in August by either method or by species. Stocking density explained only from 11% to 23% of the parr survival depending on the species or stocking method. The mean densities of Atlantic salmon and brown trout parr did not differ significantly from each other at any fishing site ( P > 0.05). Both point and scatter stocking appear to be suitable methods for use in small rivers. The parr densities depend more on the other factors (e.g. habitat quality) than the stocking method, and the choice between methods could be based on the time and labour available.  相似文献   

13.
The feeding trial was conducted in 80 days to assess the effects of stoking densities on growth, digestive enzymes activities, serum biochemical parameters and antioxidant status of juvenile genetically improved farmed tilapia (GIFT, Oreochromis niloticus) reared in in‐pond raceway recirculating culture system (IPRS). Fish (initial body weight: 6.25 ± 0.32g ) were randomly allotted to six in‐pond raceways (22 × 5 × 2.5 m) stocked at three different stocking densities: low stocking density (LSD, 0.28 kg/m3), medium stocking density (MSD, 0.57kg /m3) and high stocking density (HSD, 0.85 kg /m3). The results indicated that no significant differences were observed in final body weight, weight gain and specific growth rate of GIFT reared at different stocking densities on day 20 (p > 0.05). Fish reared in the HSD group showed poor growth than those reared in the LSD and MSD groups on day 50, but fish reared in the MSD and HSD groups showed poor growth than those reared in the LSD group on day 80. There were no significant differences found in digestive enzyme activities, serum cortisol, lysozyme and superoxide dismutase (SOD) content, hepatic catalase (CAT), total SOD, total antioxidant capacity (T‐AOC) activities and malondialdehyde (MDA) content among fish reared at different densities treatments (p > 0.05). Fish reared in the HSD group exhibited significant higher red blood cell number, haematocrit and glucose (GLU) contents on day 80 (p < 0.05). In brief, under this trial conditions, high stocking densities (0.57 kg/m3) resulted in decrease in growth, and GIFT might have an adaptation capability to crowding stress without a change in antioxidant activity, some physiological and immune parameters.  相似文献   

14.
Amino acids (AA) regulate key metabolic pathways, including some immune responses. Therefore, this study aimed to assess whether an increased availability of dietary AA can mitigate the expected increase in plasma cortisol and metabolites levels due to high stocking density and its subsequent immunosuppression. Senegalese sole (Solea senegalensis) were maintained at low stocking density (LSD; 3.5 kg m?2) or high stocking density (HSD; 12 kg m?2) for 18 days. Additionally, both treatments were fed a control or a high protein (HP) diet (LSD, LSD HP, HSD and HSD HP). The HP diet slightly increased the levels of digestible indispensable AA, together with tyrosine and cysteine. HSD was effective in inducing a chronic stress response after 18 days of treatment since fish held at HSD presented higher plasma cortisol, glucose and lactate levels. Moreover, this increase in stress indicators translated in a decrease in plasma lysozyme, alternative complement pathway (ACP) and peroxidase activities, suggesting some degree of immunosuppression. Interestingly, while plasma glucose and lactate levels in HSD HP specimens decreased to similar values than LSD fish, plasma lysozyme, ACP and peroxidase activities increased, with even higher values than LSD groups for ACP activity. It is suggested that the HP diet may be used as functional feed since it may represent a metabolic advantage during stressful events and may counteract immunosuppression in sole.  相似文献   

15.
The osmoregulatory responses of 20 days of acclimation to environmental salinities of 5‰, 15‰, 25‰, 35‰ and 55‰ were assessed in juveniles of wedge sole ( Dicologoglossa cuneata Moreau, 1881). This sole shows a good capacity to adapt to this range of environmental salinities. A direct linear relationship between environmental salinity and plasma osmolality was observed, with a calculated isosmotic point of 10.4‰ (284 mOsm kg−1). Na+, K+-ATPase activity in the gills followed a 'U-shaped' relationship with environmental salinity, and a direct linear relationship in kidney tissue. Plasma cortisol levels were elevated in fish held in extreme salinities, and glucose levels were higher only in the group maintained at the highest environmental salinity. In the liver, a decrease in glycogen, lactate and amino acid contents was observed in specimens acclimated to extreme salinities (5‰ and 55‰), suggesting mobilization of liver metabolites. Metabolite levels in white muscle showed a pattern similar to the liver, with lower values in specimens acclimated to extreme salinities. We conclude that wedge sole is strongly euryhaline, but acclimation to extreme salinities comes with an energetic cost.  相似文献   

16.
Differences in metabolism (enzyme activities, metabolites) between diploid and triploid Salmo trutta f. lacustris were investigated under acclimation and stress conditions. Under acclimation conditions enzyme activities differed for 35% of the 27 investigated key regulatory enzymes and temperature optima for 23%. Muscle and liver metabolites related to energy metabolism and diagnostic indices of blood serum were similar, with exception of acetyl‐CoA being increased in triploids. Metabolic rate was lower and gill ventilation rate higher in triploids in comparison with diploids. During the tested stress situations (24 hr endurance swimming, 3 hr exposure to hypoxia in water with 32% oxygen saturation) muscle and liver glycogen decreased and serum and muscle lactate increased in both ploidy levels. Specifically, for triploids muscle adenylate energy charge and phosphocreatine levels decreased after endurance swimming and muscle and liver adenylate energy charge after exposure to hypoxia. Acetyl‐CoA increased in triploids during both stress situations. In summary, there existed differences in metabolism between the two ploidy levels and the energy metabolism of triploids was less balanced under stress.  相似文献   

17.
密度胁迫对点带石斑鱼幼鱼生长、代谢的影响   总被引：6，自引：1，他引：5  
点带石斑鱼(Epinephelus malabaricus)幼鱼体质量(15±0.5)g,将其随机分为4组,每缸(直径60 cm×水深50cm)分别放养10尾、20尾、30尾、40尾幼鱼,密度分别相当于1.1 kg/m~3,2.1 kg/m~3,3.2 kg/m~3,4.2 kg/m~3,并分别标记记为G,O,G_20,G_30,G_40,每组3个重复,养殖6周后对幼鱼进行生长性能、饲料系数、血液指标及肝脏中相关酶活性进行分析以研究密度胁迫对点带石斑鱼幼鱼生长、代谢的影响.结果表明:1)G_10组幼鱼增重率显著低于其他各组(P<0.05),G_20组增重率最高且显著高于其他组(P<0.05).各组间特定生长率的变化与增重率的变化趋势类似.G_10和G2_20组的饲料系数显著低于G_30组(P<0.05),G_40组饲料系数最高且显著高于其他各组(P<0.05).2)G_30和G_40组间血浆皮质醇含量无显著差异(P>0.05),但均显著高于G_10和G_20组(P<0.05),G_10组皮质醇含量显著低于G_20组((P<0.05).血糖含量呈现与皮质醇含量相同的变化趋势.3)G_30和G_40组谷丙转氨酶活性均显著高于G_10和G_20组(P<0.05),各组谷草转氨酶活性随养殖密度的升高而升高;G_40组乳酸脱氢酶活性最高,与G_30组无明显差异(P>0.05),但G_40与2个低密度组(G_10和G_20)差异显著(P<0.05);乙酞胆碱酯酶活性随养殖密度的升高而降低.结果表明,养殖密度过高或过低都会对点带石斑鱼幼鱼的生长与代谢造成负面影响,20尾/缸(2.1 kg/m~3)是较为适宜的养殖密度.本研究旨在为工厂化养殖点带石斑鱼提供理论依据.  相似文献   

18.
Growth of common sole Solea solea is negatively correlated to density, which affects productivity in culture and hence commercial success. Studies of individual feed intake were performed to examine growth and population dynamics at different densities. Three initial stocking densities: 1.0, 2.1 and 3.9 kg m?2 of individually tagged sole, referred to as low density (LD), medium density and high density HD), were examined during 145 days. Despite that tank productivity (g m?2 day?1), was highest for the HD group, the specific growth rate (SGR) decreased significantly with increase in stocking density. Individual size variation was similar between densities, indicating that growth was not associated with hierarchy and dominant behaviour. Individual data indicated that increased density reduced the growth potential of all individuals in a population. Individual feed intake was positively correlated to both fish size and individual SGR. Feed conversion ratio was likewise positively correlated to feed intake. The relative feed intake (g feed g fish?1) was not correlated to fish size at any density tested, but was significantly highest for the LD population. This explains a substantial part of the better growth in the LD group supported by indications of better utilization of the ingested feed.  相似文献   

19.
This study aimed at investigating the physiological responses of Piaractus mesopotamicus exposed to high stocking density and the potential protective role of supplemented diets. Fish were fed with basal, red seaweed (Pyropia columbina) or β‐carotene‐supplemented diets for 90 days. Then, fish were distributed at low (1.5 g/L) and high (22 g/L) stocking densities for 15 days. Fish exposed to the high density showed increased hepatosomatic index, haemoglobin content and mean corpuscular haemoglobin concentration (all diets); decreased haematocrit, mean corpuscular volume (basal and seaweed) and white blood cells count (all diets) were observed. High density‐exposed fish showed decreased plasmatic metabolites as well as the hepatic lipids content in basal and seaweed diets. Regarding oxidative stress, increased activity of glutathione S‐transferase in high density‐exposed fish muscle (all diets), and lower lipid peroxidation in liver (basal and β‐carotene) and intestine (basal and seaweed) were evidenced. Interactions between diet and stocking density were recorded regarding the triglycerides (decrease in fish exposed to high density fed with basal and seaweed) and hepatic lipids (decrease in fish exposed to high density fed with basal). The major changes occurred in haematologic and metabolic parameters as strategies to cope with overcrowding stress. Fish response to stocking density was not affected by diets.  相似文献   

20.
Pinfish (Lagodon rhomboides Linnaeus) and pigfish (Orthopristis chrysoptera L.) are relatively new, cultured species commonly used as marine baitfish in the south‐eastern United States and currently have no defined protocols for egg incubation. Thus, experiments were conducted to determine efficient egg stocking densities during static and flow‐through incubation that yielded higher quality larvae. Eggs of each species were incubated statically at 250, 500, 1000 and 2000 eggs L?1, and after incubation, egg hatching success, larval survival to first feeding, larval morphometrics and water quality were assessed. Stocking densities above 250 eggs L?1 led to significant reductions in pinfish hatching success and water quality degradation, evident from decreased dissolved oxygen and pH levels and increased nitrogenous wastes. Increased stocking densities for pigfish also resulted in significant water quality degradation, although hatching success was unaffected up to a density of 1000 eggs L?1. A high flow‐through water exchange rate of 2000% daily resulted in significant reductions in nitrogenous wastes and greater stability in dissolved oxygen and pH levels during incubation when compared to static treatments of the same egg density. Additionally, the high exchange rate of 2000% was critical in maintaining high hatching success and larval survival to first feeding at stocking densities of 1000 eggs L?1 for pinfish and up to 4000 eggs L?1 for pigfish. No clear patterns in larval morphometrics were observed among stocking densities. Static incubation densities of 250 and 1000 eggs L?1 are recommended for pinfish and pigfish, respectively.  相似文献   

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