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1.
A variety of parameters associated with breathing and feeding of silver carp were measured in response to declines in dissolved oxygen (DO) levels when the fish were fed microalgae Padorina morum (PM group) and Chlorella ellipsoidea (CE group), respectively, to explore the relationship between breathing and feeding while filtering microalgae particles at different DO levels. The results indicated that (i) respiratory frequency (fR) of the fish in CE group were higher significantly than those in PM group at DO levels of 0.98–7.49 mg/L (P < 0.05); respiratory stroke volume (VS.R), gill ventilation (VG) and VG/VO2 the fish in two groups began to increase sharply while DO levels declined to below 4.04 mg/L (P < 0.05); oxygen extraction efficiency (EO2) of the fish in two groups increased significantly with decline of DO levels from 7.49 mg/L to 0.98 mg/L (P < 0.05); (ii) the infiltration rate (FR) and filtering efficiency (E) of the fish in two groups began to decrease significantly while DO levels declined to below 4.04 mg/L (P < 0.05); clearance rate (CR) of fish in PM group was sixfold higher than that in CE group at DO levels of 0.98–7.49 mg/L (P < 0.05). In addition, antifiltering response appeared at DO levels of 2.21 mg/L and 0.98 mg/L in both groups. This study indicated that ‘filtration effect’ is dominant when the fish filter algae particles larger than its gill raker gaps, while the ‘food sinking effect’ is dominant when the fish filter algae particles smaller than its gill raker gaps.  相似文献   

2.
低氧胁迫对鲻幼鱼生长、能量代谢和氧化应激的影响   总被引：3，自引：0，他引：3  
为研究低氧胁迫对鲻幼鱼生长、能量代谢和氧化应激的影响,实验将其放在溶解氧(DO,mean±SE)含量分别控制在(1.66±0.41)、(4.35±0.53)、(7.03±0.36)mg/L的条件下养殖10 d,然后恢复至接近饱和溶解氧含量7.0 mg/L的条件下养殖30 d,研究其特定生长率、排氨率、耗氧率、氧氮比和血浆、肌肉、肝脏及鳃组织的总抗氧化能力(T-AOC)、过氧化物歧化酶(SOD)活力、抗超氧阴离子活力(ASOR)、丙二醛(MDA)含量、乳酸(LD)含量、总谷胱甘肽(T-GSH)、还原型谷胱甘肽(GSH)和氧化型谷胱甘肽(GSSG)含量。结果表明:低氧胁迫对鲻幼鱼的生长、能量代谢影响显著,较严重缺氧组鲻的体质量、特定生长率(SGR)、耗氧率和排氨率显著低于其他处理,不具有补偿生长的能力;而轻微缺氧组获得完全补偿生长。低氧胁迫对鲻氧化应激指标影响显著,胁迫结束时鲻通过提高某些抗氧化酶的活力来增强抗氧化能力,以提高其应对恢复正常溶解氧环境可能带来的氧化应激的能力,同时在恢复溶氧后鲻氧化应激反应也较强烈。在恢复溶解氧阶段,肝脏中GSH显著增加,说明鲻体内的保护机制被激活。肝脏和鳃中MDA的含量在低氧胁迫后与溶解氧含量呈明显的负相关性,在复氧30 d后仍然高于对照组,表明低氧胁迫加强鲻肝脏和鳃组织脂质过氧化反应。  相似文献   

3.
Fish are potentially submitted to water acidification when reared in recirculating aquaculture systems. This study evaluated the responses of juvenile cobia Rachycentron canadum after acute exposure to acid water. Juvenile cobia (12.6 ± 0.5 g; 14.2 ± 0.2 cm) were acutely exposed to four pH levels (7.9 (control), 6.5, 6.0, and 5.5). After 24 h of exposure to different pH values, fish were sampled for physiological and histopathological evaluation. Acid water affected physiological parameters and induced morphological histopathologies on gill and skin of juvenile cobia, and these effects were more conspicuous with decreasing pH values. Acid stress induced blood acidosis in juvenile cobia, coupled to a decrease in bicarbonate (HCO3?) and saturated O2 (sO2) in fish blood. On the other hand, haematocrit, haemoglobin and glucose concentration increased their values (P < 0.01) comparing to control level. Hyperplasia with completely fusion of secondary lamella was observed in all pH treatments (6.5. 6.0 and 5.5), while telangiectasia and proliferation of chloride cells were present for fish exposed to pH 6.0 and 5.5. In skin hyperplasia and hypertrophy of mucous cells, necrosis of these cells for fish exposed to pH 6.0 and 5.5 was observed. The results of this study demonstrate that acute acid water exposition affected physiology and histopathology in juvenile cobia, especially at pH values below 6.5. Accordingly, particular attention must be given to pH during cobia reared in recirculating aquaculture.  相似文献   

4.
Assessing the responses of lysozyme activity and antioxidant defences to hypoxia is important to understand the adaptation and tolerance strategies of fish under hypoxia. This study investigated the effects of different dissolved oxygen (DO) levels on Carassius auratus, a natural triploid fish, from Qihe River. The content of malondialdehyde (MDA) and the activities of lysozyme and antioxidant enzymes were measured in the kidney and spleen after hypoxic exposure. At the DO concentrations of 1 and 2 mg L?1, the activities of antioxidant enzymes and lysozyme significantly decreased and the content of MDA significantly increased (P < 0.01). This result suggests that hypoxia decreased antioxidant enzyme and lysozyme activities and caused MDA accumulation in a concentration‐dependent manner. The DO level of 4 mg L?1 increased the activities of superoxide dismutase and catalase in the kidney and the activities of glutathione peroxidase and catalase in the spleen (P < 0.05). This result implies that slight hypoxic stress can enhance antioxidant defences to alleviate the damage of oxidative stress. The reduced activities of antioxidant enzymes and the accumulation of MDA at the DO level of ≤2 mg L?1 implied the decrease in antioxidative ability and the occurrence of oxidative stress. The decrement in lysozyme activity indicated that the antibacterial ability was weakened to some degree. Therefore, hypoxic stress at DO levels ≤2 mg L?1 should be removed by aeration to avoid the oxidative damage resulting from the reduced antioxidative ability and prevent the outbreak of diseases caused by weakened antibacterial effects.  相似文献   

5.
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6.
A growth trial was conducted to evaluate the effects and safety of nucleotides in low fish meal diets on the growth performance, antioxidative capacity and intestinal morphology of turbot (Scophthalmus maximus). High fish meal control diet was formulated with 500 g kg?1 fish meal. Seven levels (0.075, 0.15, 0.225, 0.300, 1.5 and 3.0 g kg?1, respectively) of nucleotides were added to a low fish meal basal diet, which was formulated with 400 g kg?1 fish meal. The eight experimental diets were fed to groups of juvenile turbot (initial weight: 6.0 ± 0.03 g) for 60 days. Results showed that compared with high fish meal control diet, low fish meal basal diet treatment had lower total antioxidative capacity (T‐AOC), glutathione peroxidase activity, fold height of proximal and distal intestine, enterocyte height of all evaluated enteric section and microvillus height of mid‐intestine and distal intestine (P < 0.05). However, supplemented nucleotides in diets could significantly improve growth (specific growth rate, SGR), feed utilization, antioxidative capacity and intestinal morphology of turbot (P < 0.05). Broken‐line regression analysis of SGR and T‐AOC showed that the optimal supplemental levels of dietary nucleotide for juvenile turbot were 0.366 and 0.188 g kg?1, respectively. In summary, 0.300 g kg?1 of dietary nucleotides was helpful in improving growth, feed utilization, antioxidative capacity and intestinal morphology of turbot fed with low fish meal diet. Excessive dietary nucleotides (3.0 g kg?1) might cause oxidative stress and morphological damage in intestine and then reduce the growth of turbot.  相似文献   

7.
Ammonia toxicity and morphological changes in gills of juvenile Japanese flounder Paralichthys olivaceus (5.76 ± 0.12 g) were investigated when fish were separately exposed to normal dissolved oxygen (DO) at 6.5 ± 0.5 mg L?1 and supersaturated oxygen at 16.0 ± 2.0 mg L?1 at different ammonia concentrations. Under normal oxygen, ammonia concentrations were tested from 0.04 (control) to 93.3 mg L?1 total ammonia nitrogen (TAN), whereas under oxygen supersaturation, ammonia concentrations ranged from 0.04 (control) to 226.7 mg L?1 TAN in the trial. After exposure to ammonia for 96 h, the ammonia LC50 for fish was 62.48 mg L?1 TAN (0.50 mg L?1 NH3–N) at normal oxygen and 160.71 mg L?1 TAN (0.65 mg L?1 NH3–N) at oxygen supersaturation. Light microscopic observations confirmed that gill damage in normal oxygen was more profound than in oxygen supersaturation when fish were exposed to the same level of TAN (93.3 mg L?1). Furthermore, electron microscopic scanning also showed more crimple, retraction and fibrosis on the secondary lamella surface in fish exposed to normal oxygen than those in fish exposed to supersaturated oxygen at the same TAN (93.3 mg L?1). This study suggests that supersaturated oxygen can increase ammonia tolerance in Japanese flounder through reducing gill damage by ammonia, which partially explains the merit of using pure oxygen injection in intensive fish farming.  相似文献   

8.
Summer stratification often leads to large areas of hypolimnetic hypoxia in lakes and reservoirs. These areas of hypoxia alter fish behaviours and distributions as well as restrict access to valuable prey resources, yet few studies have examined foraging behaviour of fish in response to low dissolved oxygen (DO) concentrations. We observed foraging behaviour of juvenile largemouth bass, Micropterus salmoides, in response to varying DO concentrations in tanks that simulated a stratified lake water column during the summer: 28°C oxygenated epilimnion, 15°C deoxygenated hypolimnion. Compared with saturated concentrations (8.0–9.0 mg/L), hypolimnetic oxygen concentrations of 3.0 mg/L and 1.5 mg/L resulted in a drastic decrease in prey consumption, handling efficiency and time spent below the thermocline mainly due to avoidance behaviour of hypoxic conditions. However, we found at high hypolimnetic prey densities, individual fish were more willing to venture into reduced oxygen concentrations. Several unique behaviours including transporting prey above the oxycline for consumption, aquatic surface respiration and gill flaring were employed by largemouth bass foraging in low oxygen environments. Reduced hypolimnetic oxygen concentrations may influence and alter feeding strategies, especially for fish that rely on benthic prey resources.  相似文献   

9.
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10.
The aim of this study was to investigate a suitable packing density for the transport of juvenile dusky grouper, Epinephelus marginatus, based on the evaluation of stress responses in blood. After acclimation, fish were placed in plastic bags and transported for 8 hr on paved road at densities of 28, 45 and 64 g/L. Water quality was monitored before and after transport. Blood was collected before, upon arrival (0 hr), after 2 and 24 hr of transport. Plasma cortisol, blood glucose, partial pressures of O2 (pO2) and CO2 (pCO2), blood pH and HCO3? were evaluated. Blood smears were prepared for the verification of leucocyte profile and neutrophils:lymphocyte ratio (N:L). Blood pCO2, pH and HCO3? increased significantly after transport for all treatments compared with pre‐transport. Glucose levels increased at the higher density whereas no effects were observed on plasma cortisol and pO2 levels. Upon arrival, all treatments showed lymphopenia and neutrophilia which increased N:L ratio. Although lymphopenia was observed in higher densities until 2 hr after transport, haematological parameters were fully restored within 24 hr post transport. Furthermore, no mortalities were observed throughout the experimental period. Based on the transient physiological changes observed in this study, juvenile dusky grouper can be safely transported in plastic bags for 8 hr at a density of up to 64 g/L.  相似文献   

11.
Some vertebral anomalies in cultured fish arise from unusual environmental conditions during embryogenesis. We investigated the individual and combined teratogenic effects of short‐term hypercapnia and hypoxia on embryos of red sea bream (RSB), Pagrus major. Ten‐somite stage embryos were exposed to hypercapnia (60 and 120 mg/L dissolved carbon dioxide: DCD) and hypoxia (0%, 10%, 25%, 50%, and 75% dissolved oxygen: DO) independently and concomitantly for seven different periods (0, 30, 60, 90, 120, 150 and 180 min) to examine somitic disturbances at hatching, which are prodromal symptoms of centrum defects. Another experiment examined vertebral anomalies in juveniles raised from eggs exposed to hypercapnia (120 mg/L DCD) and hypoxia (10% DO) independently and concomitantly. Short‐time exposures (30–180 min) to hypercapnia (60 and 120 mg/L) and hypoxia (10% DO or less) independently and additively caused larval somitic disturbances and juvenile centrum defects. The results indicate that short‐term hypercapnia and hypoxia generally have the same teratogenic effect on embryos, although there were some differences in the locations of the somitic disturbances and centrum defects, with additive teratogenicity when the conditions were combined. These results suggest the necessity of maintaining appropriate DCD and DO concentrations during egg incubation and transport and during reproduction in recirculating aquaculture.  相似文献   

12.
Variations in respiratory and acid-base status were studied in turbot (Scophthalmus maximus) during progressive severe hypoxia followed by recovery under normoxic conditions. The first behavioural strategy of turbot under hypoxia was an increase in amplitude and frequency of ventilation. Consequently, standard O2 consumption remained unchanged over a broad range of O2 tensions, until a low critical level of 30 mmHg. The hyperventilation induced a moderate blood alkalosis, compensated by a lactic acidosis. The fact that blood pH did not decrease below control values could be explained by the retention in white muscle of most of the lactate produced and by a high capacity for H+ excretion. During the recovery period, the marked increase in O2 uptake corresponding to an oxygen debt repayment, was partly related to the lactate elimination. When total energy contributions of aerobic and anaerobic processes were assessed in terms of ATP, the anaerobic contribution, estimated at the deepest hypoxia level, was higher than 20% of the total energy budget and appeared to totally compensate for the decline in aerobic metabolism. Moreover, the high value of O2 tension in arterial blood in normoxia and during recovery from hypoxia showed high diffusing capacity of gills in turbot. Our results explain the high tolerance of turbot for O2 deficient waters.  相似文献   

13.
为探究急性低氧对团头鲂(Megalobrama amblycephala)鳃组织氧化还原稳态及细胞凋亡的影响, 本研究通过测定超氧化物歧化酶(superoxide dismutases, SOD)、过氧化氢酶(catalases, CAT)活性及丙二醛(malondialdehyde, MDA)的含量, 检测急性低氧胁迫下鳃组织的氧化应激水平, 并采用 Hoechst 染色法观察了团头鲂鳃组织细胞的凋亡, 同时还利用 qRT-PCR 技术检测了团头鲂鳃组织中凋亡相关基因 Caspase 3、Caspase 8 的表达量。结果显示, 在溶解氧含量为(2.0±0.1) mg/L 的低氧环境下, 团头鲂鳃组织中 SOD、CAT 活性及 MDA 的含量均在 6 h、12 h 时显著增加(P＜0.05); 且 SOD 活性与 MDA 含量的变化趋势相同, 均呈上升趋势。此外, 随低氧胁迫时间的延长, 在 6、 12 及 24 h 时鳃组织细胞凋亡的平均荧光强度分别为 0 h 的 2.19 倍(P＜0.05)、2.32 倍(P＜0.05)及 2.59 倍(P＜0.05), 鳃组织中 Caspase 3 与 Caspase 8 基因表达水平均显著高于 0 h(P＜0.05)。研究表明, 团头鲂在急性低氧的水环境中会提高自身的氧化应激水平, 激活凋亡相关基因 Caspase 3、Caspase 8 的活性, 最终促使团头鲂鳃组织发生细胞凋亡。 本研究结果为急性低氧下团头鲂鳃组织的生理状态和细胞凋亡应答情况的研究提供参考。  相似文献   

14.
This study was conducted to determine the effect of dissolved oxygen (DO) levels on growth performance, energy budget and antioxidant responses of yellow catfish Pelteobagrus fulvidraco. Yellow catfish was exposed to four levels of DO, consisting of hypoxia (2.28 mg L?1), moderate hypoxia (4.04 mg L?1), saturation (6.51 mg L?1) and super‐saturation groups (9.11 mg L?1), respectively, for 8 weeks. Specific growth rate and feed efficiency in dry matter were lowest in hypoxia and highest in the saturation and super‐saturation groups. Apparent digestibility coefficients of dry matter and energy increased with increasing DO levels. Gross energy and growth energy were lowest for hypoxia, followed by moderate hypoxia and the highest for other two groups. Faecal energy was highest in hypoxia and lowest in saturation and super‐saturation group. DO levels also significantly influenced activities of antioxidant enzymes and malondialdehyde level in liver and serum. Based on the observation described previously, saturated DO level helps to improve growth performance, feed utilization and antioxidant responses in yellow catfish. Super‐saturation did not increase fish performance. To our knowledge, this is the first study involved in the effect of DO levels on energy budget of fish and provides new insight into aeration regime for yellow catfish culture.  相似文献   

15.
The effects of flow rate on growth and welfare of juvenile turbot (Scophthalmus maximus L.) were investigated in the present study. Fish with same initial weight (102.5 ± 10.6 g) were subjected to four flow rates, equalling to 0.5, 1, 1.5 and 2 tank volumes per hour in twelve 392 L tanks during 80 days. Results showed that specific growth rate of turbots increased (0.40–0.58% day?1) significantly with promoted flow rate (P < 0.05). Total ammonia nitrogen, nitrite nitrogen, unionized ammonia nitrogen, chemical oxygen demand, total bacteria and total vibrio in tanks were affected significantly by flow rate and accumulations were found in low rate (200 L h?1) (P < 0.05). Free carbon dioxide increased significantly with the increased flow rate and ranged between 4.5 and 13.5 mg L?1 (P < 0.05). Both superoxide dismutase activity and lysozyme activity increased significantly with flow rate (P < 0.05), with ranges of 108.51–131.57 U mL?1 and 551.81–869.28 U mL?1. Serum cortisol showed reversed tendency and ranged between 7.39–19.26 ng mL?1. The principal components analysis suggested that increased flow rate promoted fish welfare. It was concluded that increased flow rate promoted the growth of juvenile turbot, possibly explained by fish welfare differences in combination of health, water quality and serum parameters.  相似文献   

16.
In this study, the physiological response and growth performances of Acipenser ruthenus were investigated after a long‐term background colour adaptation (12 weeks). Twelve groups of 10 individuals with initial mean body weight of 183 g were reared in black, dark blue, grey and white tanks (three replicates for each colour). At the end of the experiments, growth (initial body weight, final body weight, weight gain per cent, food efficiency ratio, protein efficiency ratio, specific growth rate), blood (cortisol, glucose, pO2, pCO2, pH, haematocrit, osmolality, triglycerides, cholesterol, total lipids) and liver (hepatosomatic index, total lipids, glycogen) parameters were analyzed. Plasma cortisol in the dark‐adapted sterlet (21.95 ± 3.9 ng mL?1) was significantly lower than those in white‐adapted fish (39.44 ± 6.5 ng mL?1), whereas there were no significant differences in cortisol levels between the grey‐adapted fish (23.05 ± 4.1 ng mL?1) and dark blue‐adapted fish (24.2 ± 3.6 ng mL?1). A remarkable increase in mean of body weight (%) was detected in dark‐adapted sterlet (45.2 ± 3.2) being 27.67%, 12.1% and 11.8% higher than the white, grey and dark blue‐adapted fish respectively. The obtained results verified that different background colours lead to different growth performances and physiological responses of starlet, depending on rearing conditions.  相似文献   

17.
The effect of sublethal hypoxia exposure on stress and immune responses and susceptibility to Edwardsiella ictaluri infection in juvenile channel catfish, Ictalurus punctatus, was investigated. Fish were monitored for temporal changes in glucose and cortisol concentrations before, during, and after 2 h exposure to sublethal hypoxia (<2 mg/L dissolved oxygen [DO]) and when maintained under normoxic conditions (6.0 ± 0.3 mg/L DO). Both blood glucose and plasma cortisol increased significantly in response to hypoxic conditions. Fish exposed to hypoxic or normoxic conditions were challenged with a high dose (1.3 × 107 colony‐forming units [CFU]/mL) or a low dose (1.3 × 105 CFU/mL) of E. ictaluri or sterile culture broth by 30‐min immersion bath. Approximately 1% of fish in both the normoxic and the hypoxic groups died when challenged with the low dose of E. ictaluri. However, when challenged with the high dose of E. ictaluri, catfish exposed to hypoxic conditions had significantly higher cumulative mortality (36 ± 12.1%) than those maintained under normoxic conditions (12 ± 1.1%). Total hemolytic complement and bactericidal activities and antibody response were lower in hypoxia‐exposed channel catfish, indicating that increased susceptibility of channel catfish to E. ictaluri may be the result of the immunosuppressive effects of the stress response to hypoxia.  相似文献   

18.
We investigated the efficacy of praziquantel (PZQ) and fenbendazole (FBZ), each administered by bath and orally, against the monogenean Lepidotrema bidyana Murray, a gill parasite of the freshwater fish silver perch, Bidyanus bidyanus (Mitchell). PZQ and FBZ were each administered by bath at 10 mg L?1 for 48 h and on surface‐coated feed pellets at 75 mg kg?1 per body weight (BW) per day for 6 days. Bath treatments of PZQ and FBZ had an efficacy of 99% and 91%, respectively, against adult L. bidyana. Oral treatments of PZQ and FBZ had an efficacy of 79% and 95%, respectively, against adult L. bidyana. Fish rejected feed pellets surface‐coated with PZQ, suggesting that palatability of surface‐coated PZQ‐medicated feed is poor, which undermined efficacy. In all trials, some juvenile parasites were present on fish after treatment during efficacy assessment, indicating that efficacy may be lower against juvenile parasites or that recruitment occurred post‐treatment, demonstrating that repeat treatments are necessary to effectively control L. bidyana in aquaculture.  相似文献   

19.
Gill respiratory surface area and oxygen consumption during aquatic respiration were measured in the facultative air-breathing loricariid fish,Hypostomus plecostomus. The fish did not surface to breathe atmospheric air in normoxic water; air-breathing was evoked by environmental hypoxia (water oxygen tension=35±2, mmHg) and did not show size-related threshold differences for air breathing.During gradual hypoxia, without access to atmospheric, air,H. plecostomus was found to be an oxyregulator and showed a reduced range of water oxygen tension in which the oxygen consumption remained constant in smaller fish. The critical oxygen tensions were 55 and 33 mmHg at 25°C for fish of 14–30 g and 31–80g body weight, respectively.The gill respiratory surface area (total lamellae area) is reduced, however, the lamellar frequency per mm of gill filament is high which facilitates the gas exchange. Moreover, the increase of gill respiratory surface area (b=0.666) is higher than the increase in routine VO2 (b=0.338) showing a positive relationship between the gill respiratory surface area /VO2 ratio and body mass (b=0.328); this indicates that the fish have greater gill respiratory surface area per unit of routine VO2 as they grow.  相似文献   

20.
This study aimed to determine whether dietary carotenoid (CD) supplements could affect the antioxidant capacity of characins Hyphessobrycon callistus upon hypoxia stress at live transportation. Two types of CD [astaxanthin (AX), β‐carotene (BC)] and their 1:1 combination (MX) at three concentrations (10, 20 and 40 mg kg?1) were supplemented, resulting in nine CD diets. After 8 weeks' rearing, the resulting fish were divided into two subgroups and exposed to hypoxia or normoxia. Hypoxia involved a gradual decrease in dissolved oxygen (DO) from 6.5 to <1.0 mg L?1. Normoxia was DO kept in saturation. Hypoxia led to an increase in the total antioxidant status (TAS), superoxide dismutase (SOD), glutathione peroxidases (GPx) and aspartate aminotransferase (AST) activity of blood serum in fish, but had no effect on alanine aminotransferase (ALT). Under hypoxia, fish fed CD diets had lower SOD, GPx and ALT activity than control fish, showing that dietary CD could increase the antioxidant capacity and protection of the liver. Dietary AX was more effective for antioxidant capacity than BC and MX when under hypoxia stress, because GPx, ALT and AST were lower in AX‐fed fish. Except TAS, the other four enzyme activities showed decreasing trends with increasing dietary CD concentrations.  相似文献   

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