首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Responses to anaesthesia with essential oil (EO) of Aloysia triphylla (135 and 180 mg L?1) and tricaine methanesulfonate (MS222) (150 and 300 mg L?1) were assessed in silver catfish. Exposure to the anaesthetics elicited a stress response in the species. In the case of MS222, it was displayed as a release of cortisol into bloodstream, elevation in hematocrit and plasma ion loss. The EO presented cortisol‐blocking properties, but increased haematocrit and disturbances of hydromineral balance were observed. Liver antioxidant/oxidant status of EO and MS222‐anaesthetized silver catfish was also estimated. The synthetic anaesthetic induced lipoperoxidation, notwithstanding increased catalase contents, whereas the naturally occurring product was capable of preventing the formation of lipid peroxides, possibly due to combined actions of catalase and glutathione‐S‐transferase. Anaesthetic efficacy was also tested via induction and recovery times. Overall, the promising results obtained for the physiological parameters of the EO‐treated fish counterbalanced the slight prolonged induction time observed for 180 mg L?1. As for 135 mg L?1, both induction and recovery times were lengthy; despite that, the EO was able to promote oxidative protection and mitigate stress. None of the MS222 concentrations prompted such responses concomitantly.  相似文献   

2.
The effects of four anaesthetic agents, tricaine methanesulphonate (MS‐222) (112.5 mg L?1), 2‐phenoxyethanol (400 μL L?1), clove oil (70 mg L?1) and benzocaine (65 mg L?1) on juvenile marbled spinefoot (Siganus rivulatus) of three mean body weights (7.3 g, 19.1 g, 55.5 g) and at three temperatures (20, 25, 30°C) were evaluated. In addition, the relationship between body lipid content and efficacy of the four anaesthetic agents was evaluated in juvenile S. rivulatus. Times necessary for induction and recovery were recorded. Significant effects of temperature on induction and recovery times were observed. Induction and recovery times decreased with increasing water temperature. No uniform relationship between body weight of juvenile marbled spinefoot and anaesthetic efficacy was observed. Body fat content was positively correlated with induction time only when MS‐222 was used but did not affect induction times of fish exposed to 2‐phenoxyethanol, clove oil or benzocaine. Recovery times were generally longer for all fish containing more body fat. Results of the study show that anaesthetic efficiency increases with increasing water temperature but is not strongly affected by body weight for juvenile marbled spinefoot. In addition, body fat in fish affected the efficacy of the various anaesthetic agents tested in this study, generally slowing down recovery.  相似文献   

3.
Anaesthetic agents are very useful for reducing the stress caused by handling, sorting, transportation, artificial reproduction, tagging, administration of vaccines and surgical procedures in fish. The efficacy of two anaesthetics: MS‐222 and AQUI‐S® were tested on rohu, Labeo rohita advanced size fry. The lowest effective doses that produced induction in 3 min or less and recovery times 5 min or less and meet the most criteria of good anaesthetic characteristics were 125 mg L?1 of MS‐222, and 30 mg L?1 of AQUI‐S® in rohu, Labeo rohita advanced size fry. Induction times were significantly decreased with increased in the concentrations of any of the two tested anaesthetic agents. The lowest doses suitable for transportation of rohu advanced size fry observed were: 10–15 mg L?1 of MS‐222 and 2.5 mg L?1 AQUI‐S®. Both anaesthetics showed promising to be used as anaesthetics for handling and transportation in rohu (Labeo rohita) advanced fry.  相似文献   

4.
The aim of this study was to evaluate the anaesthetic effect of MS‐222 and propofol and determine their optimal concentrations for safe handling of the tetra Astyanax altiparanae in the laboratory. The fish were separated by length into three classes: I (1.5–5.0 cm), II (5.1–8.0 cm) and III (greater than 8.1 cm). Pilot tests were performed to evaluate the appropriate anaesthetic concentrations for inducing the five possible anaesthetic stages: I – sedation; II – light anaesthesia; III – deep anaesthesia; IV – surgical anaesthesia; and V – spinal collapse. After defining the maximum and minimum concentrations required to induce stage IV anaesthesia, the animals were exposed to five intermediate concentrations (n = 10 fish/concentration) of each anaesthetic for 15 min. The animals were then transferred to clean water to evaluate the time required for recovery. In addition, blood glucose levels were measured for class II and class III fish subjected to the previously defined ideal concentrations for each of the tested anaesthetics (n = 10 fish/treatment). Both evaluated substances are suitable to anaesthetize A. altiparanae. The optimal MS‐222 concentration was 90 mg L?1, and this result was similar for all three size classes. The optimal propofol concentrations for inducing surgical anaesthesia in the size classes I, II and III were 0.22, 0.23 and 0.27 respectively.  相似文献   

5.
Anaesthetics are used in aquaculture and fisheries to facilitate routine procedures, such as capture, handling, transportation, tagging, grading and measurements that can often cause injury or induce physiological stress. Two experiments were performed to assess the efficacies of four anaesthetic agents, clove oil, benzocaine, 2‐phenoxyethanol and MS‐222 on juvenile marbled spinefoot rabbitfish (Siganus rivulatus). In the first experiment we tested the lowest effective doses that produced induction and recovery times in 3 min or less and 5 min or less respectively. Dosages were 70 mg L?1 for clove oil, 60–70 mg L?1 for benzocaine, 400 μL L?1 for 2‐phenoxyethanol and 100–125 mg L?1 for MS‐222. In the second experiment, we determined optimal concentrations of the four anaesthetics if they were to be used to transport rabbitfish fry. Anaesthetic concentrations suitable for handling and transport were: 10–15 mg L?1 of MS‐222, 5–10 mg L?1 of benzocaine, 5 mg L?1 of clove oil and 50–100 μL L?1 of 2‐phenoxyethanol. All anaesthetic agents are acceptable for use on S. rivulatus, however, 2‐phenoxyethanol, MS‐222 and clove oil appear to be more suitable than benzocaine. Further studies need to be conducted on effects of high and low doses of anaesthetic agents on physiology of marbled spinefoot.  相似文献   

6.
The anaesthetic potential of menthol was evaluated in lambari Astyanax altiparanae by exposing fingerlings to concentrations 50, 100, 150, 200, 250 and 300 mg L?1 and measuring the induction and recovery times to deep anaesthesia, the mortality rates during and 96 h after procedure and after 6 min of continuous exposure. The effect of menthol on stress responses were evaluated by comparing glucose and cortisol levels of juveniles subjected to anaesthesia (50 mg L?1), stress (air exposure) or pre‐anaesthesia associated to stress. All concentrations induced deep anaesthesia within 0.5 to 1 min, with recovery between 1.83 and 4.16 min, without mortality during the induction or up to 96 h after exposure. Induction time decreased and recovery time increased linearly as the menthol concentration increased. Continuous exposure to 50, 100 and 150 mg L?1 concentrations resulted in mortality rates of 0%, 20% and 80% respectively. Anaesthesia or air exposure increase blood glucose but prior anaesthesia with menthol suppressed the elevation of cortisol caused by stress. Menthol has an anaesthetic effect and attenuates the stress response in lambari and 50 mg L?1 is the most effective concentration for inducing deep anaesthesia in 1.0 min, safe for up to 6 min exposure.  相似文献   

7.
Four alkaloids (Sanguinarine, 6‐Methoxyl‐dihydro‐chelerythrine, Cryptopine and β‐Allocryptopine) were isolated from aerial parts of Macleaya microcarpa (Maxim) Fedde using bioassay‐guided isolation method, and the inhibitory activity of ethanolic extract, various fractions and these four alkaloids against four fish pathogenic bacteria (Aeromonas hydrophila, Aeromonas salmonicida, Vibrio anguillarum and Vibrio harveyi) was assessed in vitro using the agar dilution method and the microdilution assay method respectively. A. hydrophila was the most sensitive strain to all the tested compounds. Minimum inhibitory concentration (MIC) values were lower for sanguinarine against all tested Gram‐negative strains than other three alkaloids, with MIC values of 12.5 mg L?1 for A. hydrophila and 50 mg L?1 to other pathogenic bacteria. Followed by 6‐methoxyl‐dihydro‐chelerythrine, which showed considerable antibacterial activity with MIC values of 80 mg L?1 for A. hydrophila, 100 mg L?1 for V. harveyi, and 125 mg L?1 for both V. anguillarum and A. salmonicida. Cryptopine and β‐allocryptopine revealed similar inhibitory activity with MIC values of 100 mg L?1 for A. hydrophila and 200 mg L?1 for other three bacterial species. These finding provided evidence that extract, as well as isolated compounds from M. microcarpa might be potential sources novel antibacterial agents for the treatment of fish infectious diseases.  相似文献   

8.
Ammonia is a metabolite of aquatic organisms which might reach deleterious levels in intensive fish farms. The aim of the present study was to determine median lethal concentrations (96‐h LC50) of total ammonia nitrogen (TA‐N) on marbled spinefoot rabbitfish (Siganus rivulatus) and chronic effects of TA‐N on survival, growth and behaviour of juvenile rabbitfish over a 50 day period. In the first experiment, fish were exposed to 0, 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 mg L?1 TA‐N for 96 h and survival evaluated. In the second experiment, 12 fish were stocked per 50‐L tank and treated with one of 0, 2, 4, 6, 8, 10 and 12 mg L?1 TA‐N with three replicate tanks per treatment. Survival and growth were determined and histopathological alterations of gills due to chronic ammonia exposure were studied by light and electron microscopy. The 96‐h LC50 values were 16–18 mg L?1 TA‐N. In the chronic exposure experiment, fish reared in water with 0 mg L?1 TA‐N had 100% survival and had 50% weight increase in 50 days. Fish at 2 and 4 mg L?1 TA‐N all died whilst fish in 6, 8, 10 and 12 mg L?1 TA‐N survived and grew albeit less than in treatment 0 mg L?1. Gills from ammonia treated fish displayed severe histological and ultrastructural alterations including hyperplasia, hypertrophy and fusion of secondary lamellae, aneurysms and presence of pleomorphic altered cells. Chronic exposure to ammonia is deleterious to marbled spinefoot rabbitfish and low concentrations of ammonia appear to kill the fish in <50 days whilst fish can survive for more than 50 days at concentrations between 6 and 12 mg L?1 TA‐N.  相似文献   

9.
Anaesthetic efficacy of eugenol was investigated on iridescent shark, Pangasius hypophthalmus. Fish (2, 5, 10 and 20 g) subjected to 20–200 mg L?1 eugenol and behavioural response as well as induction and recovery times were recorded. Induction and recovery times were significantly affected by eugenol concentration as well as fish weight (P < 0.05). Generally, 27–300 s after exposure to 20–200 mg L?1 eugenol, iridescent sharks reached stage 3 anaesthesia (suitable for general handling). Fish entered stage 4 anaesthesia (suitable for surgery and blood sampling) over 54–710 s exposure to such concentrations. Recovery time was 109–600 s in all weight classes as well as eugenol concentrations. Mortality (44–100%) was only observed in 2 g fish when subjected to 110–170 mg L?1 eugenol. This study, for the first time, showed behavioural response of iridescent shark to anaesthesia as well as effectiveness of eugenol as anaesthetic in this important aquaculture‐ornamental species. According to the models obtained in this study, minimum eugenol concentrations to induce anaesthesia over less than 3 min were 53.8–81.5 mg L?1 in 2–20 g fish. Likewise, maximum eugenol concentrations in which fish recovered over less than 5 min were 65.9–105.8 mg L?1 in 2–20 g fish.  相似文献   

10.
The nitrite toxicity was estimated in juveniles of L. vannamei. The 24, 48, 72 and 96 h LC50 of nitrite‐N on juveniles were 8.1, 7.9, 6.8 and 5.7 mg L?1 at 0.6 g L?1; 14.4, 9.6 8.3 and 7.0 mg L?1 at 1.0 g L?1; 19.4, 15.4, 13.4 and 12.4 mg L?1 at 2.0 g L?1 of salinity respectively. The tolerance of juveniles to nitrite decreased at 96 h of exposure by 18.6% and 54.0%, when salinity declined from 1.0 to 0.6 g L?1 and from 2.0 to 0.6 g L?1 respectively. The safe concentrations at salinities of 0.6, 1.0 and 2.0 g L?1 were 0.28, 0.35 and 0.62 mg L?1 nitrite‐N respectively. The relationship between LC50 (mg L?1), salinity (S) (g L?1) and exposure time (T) (h) was LC50 = 8.4688 + 5.6764S – 0.0762T for salinities from 0.6 to 2.0 g L?1 and for exposure times from 24 to 96 h; the relationship between survival (%) and nitrite‐N concentration (C) for salinity of 0.6–2.0 g L?1, nitrite‐N concentrations of 0–40 mg L?1 and exposure times from 0 to 96 h was as follows: survival (%) = 0.8442 + 0.1909S – 0.0038T – 0.0277C + 0.0008ST + 0.0001CT–0.0029SC, and the tentative equation for predicting the 96‐h LC50 to salinities from 0.6 to 35 g L?1 in L. vannamei juveniles (3.9–4.4 g) was 96‐h LC50 = 0.2127 S2 + 1.558S + 5.9868. For nitrite toxicity, it is shown that a small change in salinity of waters from 2.0 to 0.6 g L?1 is more critical for L. vannamei than when wider differences in salinity occur in brackish and marine waters (15–35 g L?1).  相似文献   

11.
Argyrosomus regius (3.0 ± 0.9 g) were exposed to different concentrations of ammonia in a series of acute toxicity tests by the static renewal method at three temperature levels (18, 22 and 26°C) at a pH of 8.2. Low temperature clearly increased the tolerance of the fish to total ammonia nitrogen (TAN) and unionized ammonia (NH3) (P < 0.05). While the 96‐h LC50 values of TAN were 19.79, 10.39 and 5.06 mg L?1, the 96‐h LC50 of NH3 were 1.00, 0.70 and 0.44 mg L?1 at 18, 22 and 26°C respectively. The safe levels of NH3 for A. regius was estimated to be 0.10, 0.07 and 0.04 mg L?1 at 18, 22 and 26°C respectively (P < 0.05). This study clearly indicates that A. regius is more sensitive to ammonia than other marine fish species cultured on the Mediterranean and Eastern Atlantic coasts.  相似文献   

12.
Anaesthetic efficacy of eugenol was investigated on Flowerhorn (Amphilophus labiatus × Amphilophus trimaculatus). A total of 104 fish with average weights of 12 ± 2.5, 28 ± 5 and 53 ±5.1 g were subjected to 25–200 mg L?1 eugenol and behavioural responses as well as induction and recovery times were recorded. Induction and recovery times were significantly affected by eugenol concentration as well as fish weight (P < 0.05). Generally, 49.9–127.3 s after exposure to 50–200 mg L?1 eugenol, fish reached stage 3 anaesthesia (suitable for general handling). Fish entered stage 4 anaesthesia (suitable for surgery and blood sampling) over 57.3–140.4 s post exposure to such concentrations. Recovery time was 91.7–312 s in all weight classes for all eugenol concentrations. Mortality (23%) was only observed in 12‐g fish when were subjected to 200 mg L?1 eugenol. This study showed the behavioural response of Flowerhorn to anaesthesia and eugenol efficacy as an anaesthetic in this important ornamental species. The general quadratic equation revealed that concentrations of eugenol and fish size along with their interactive effects have significantly contributed to the model, with concentration recording the highest beta value in all models (β = ?0.809, ?0.818 and ?0.909, P = 0.000). According to the results, minimum eugenol concentration to induce anaesthesia in less than 3 min was 50 mg L?1.  相似文献   

13.
Marbled rabbitfish, Siganus rivulatus, is an economically valuable herbivorous fish and a potential candidate for warmwater aquaculture. This study was carried out to: (1) assess the effect of various oxygen concentrations on survival and behaviour of S. rivulatus fingerlings and (2) investigate the response of S. rivulatus to hypoxia and determine its critical oxygen tension (Pcrit). In the first experiment, groups of rabbitfish (15 fish per group) were maintained for 1 h in waters of various oxygen concentrations. They were then transferred to well‐aerated tanks and observed for 72 h. Survival was recorded, fish behaviour at low oxygen concentrations observed, and LC50 after 1‐h hypoxia and 72‐h recovery evaluated. In the second experiment, a series of stop‐flow respirometry experiments were performed during which dissolved oxygen was allowed to drop to 0.5 mg L?1 and respiration rate recorded at various oxygen concentrations. In the first experiment, all fish survived for 1 h at oxygen concentration of 1.44 mg L?1 and greater, but started dying at oxygen concentrations below 0.65 mg L?1 (16% survival). The LC50 of S. rivulatus fingerlings was 0.6 mg L?1. Results of the second experiment showed that S. rivulatus is an oxyregulator until Pcrit (1.7 mg L?1 O2) is reached, becoming an oxyconformer below this concentration. Findings allow for a better understanding of environmental oxygen tolerances and minimum acceptable oxygen concentration in rabbitfish aquaculture.  相似文献   

14.
Piaractus mesopotamicus juveniles (total length 12 ± 0.5 mm) were exposed to different concentrations of ammonia‐N (un‐ionized plus ionized ammonia as nitrogen), using the static renewal method at different temperature levels (15, 20 and 25°C) at pH 7. The 24, 48, 72, 96 h LC50 values of ammonia‐N in P. mesopotamicus juveniles were 5.32, 4.19, 3.79 and 2.85 mg L?1 at 15°C; 4.81, 3.97, 3.25 and 2.50 mg L?1 at 20°C; and 4.16, 3.79, 2.58 and 1.97 mg L?1 at 25°C respectively. The 24, 48, 72, 96 h LC50 values of NH3‐N (un‐ionized ammonia as nitrogen) were 0.018, 0.014, 0.013, 0.009 mg L?1 at 15°C temperature; 0.023, 0.019, 0.016 and 0.012 mg L?1 at 20°C; 0.029, 0.026, 0.018 and 0.014 mg L?1 at 25°C. The temperature increase from 15 to 25°C caused an increase of ammonia‐N susceptibility by 21.80%, 9.55%, 31.92% and 30.87%, after 24, 48, 72 and 96 h exposure respectively. Furthermore, we found that exposure of fish to ammonia‐N caused an elevation in total haemoglobin and blood glucose with an increase of 2 mg L?1 concentration. Ammonia levels tolerated, especially in different temperatures levels, have important implications for the management of aquaculture.  相似文献   

15.
A 75‐day experiment was conducted with juvenile gibel carp (Carassius auratus gibelio) (4.80 ± 0.01 g) to evaluate effects of dietary chitosan on fish growth performance, haematology, intestine morphology and immune response. Six isonitrogenous (crude protein: 383 g kg?1), isolipid (97.5 g kg?1) and isocaloric (gross energy: 16.7 kJ g?1) diets were formulated to contain 0, 1800, 4000, 7500, 10 000, 20 000 mg kg?1 chitosan, respectively. The results showed that the growth was depressed when the fish fed with 10 000 mg kg?1 chitosan. Serum cholesterol, triglyceride and low‐density lipoprotein decreased in 10 000 and 20 000 mg kg?1 chitosan. On day 75, blood leucocyte phagocytic activity respiratory burst and alternative pathway of complement haemolytic activity were enhanced in 4000 mg kg?1 chitosan. The number of goblet cell, intraepithelial lymphocyte of mid‐intestine and microvilli height of distal intestine increased at 4000 mg kg?1 dietary chitosan. Dietary chitosan modulated intestine microbiota, depressed pathogen bacteria Aeromonas veronii‐like and improved Cellulomonas hominis‐like, Bacillus oceanisediminis‐like and two uncultured bacterium‐like species on day 75. Dietary 7500 and 10 000 mg kg?1 chitosan enhanced the protection against Aeromonas hydrophila infection. In conclusion, oral administration of dietary 7500 mg kg?1 chitosan for 75 days is recommended for the survival of gibel carp.  相似文献   

16.
The marine centric diatom Chaetoceros muelleri has been widely used as live feed in fish and shellfish aquaculture due to its excellent nutritional properties. The growth of microalgae is affected by various nutritional and environmental parameters, and species specific optimization of these parameters is essential for the development of cost‐effective biomass production process. In this study, the growth of C. muelleri, was optimized using response surface methodology (RSM). The variables nitrate, phosphate, silicate, temperature, pH, salinity and agitation speed were initially screened for biomass production in C. muelleri using Plackett–Burman experimental design, and it was found that nitrate, phosphate, silicate, temperature and pH significantly influenced the biomass production. These variables were further optimized by central composite design of RSM for biomass production and nutrient composition, and the medium was re‐constituted accordingly to have 180 mg L?1 nitrate, 7.5 mg L?1 phosphate, 30 mg L?1 silicate, with optimum growth conditions of temperature at 31°C and pH 6.46. At the end of 10 days culture period under the above conditions, biomass, protein, lipid and carbohydrate significantly increased from 0.360 ± 0.01 mg L?1, 9.41 ± 0.02%, 18.11 ± 0.01%, 0.6 ± 0.02% to 1.16 ± 0.01 mg L?1, 11.02 ± 0.01%, 19.58 ± 0.01% and 0.77 ± 0.01% respectively. The biomass production of C. muelleri could be increased 3.2‐fold with an improved nutrient profile by modifying the growth factors, the study thus offering an optimized process for biomass production of C. muelleri.  相似文献   

17.
The effects of ditch size on growth and production of mono‐sex tilapia, Oreochromis niloticus in rain fed concurrent rice–fish system were technically and economically evaluated for a period of 4 months. Three different ditch sizes were tried: 5%, 10% and 15% of the total cultivable rice field. The fish fingerlings stocking density (5000 ha?1) and management practices were similar in all plots. The water temperature, dissolve oxygen, pH, Secchi disc visibility, ortho‐phosphate, ammonia nitrogen and alkalinity were found to be in the range of 31.5–31.9°C, 5.10–5.27 mg L?1, 7.56–7.62, 34.81–35.41 cm, 0.88–0.96 mg L?1, 0.014–0.021 mg L?1 and 66.23–69.76 mg L?1, respectively, and all the values were found suitable for tilapia fish farming. Sediment organic matter, available nitrogen and phosphorous were increased significantly (P < 0.05) in all plots after cultivating the fish. Larger ditch size (15% of the total land area) resulted in significantly (P < 0.05) higher specific growth rate, survival and fish production compared with the smaller (5%) and medium (10%) ditch sizes. However, significantly (P < 0.05) higher net income and benefit–cost ratio were obtained in medium ditch size with the values of 2.6% and 3.6% higher than the smaller and larger ditch sizes respectively. It is concluded that rice–fish farming in a rain fed ecosystem of Bangladesh with medium ditch size and stocking density of 5000 ha?1 mono‐sex tilapia can achieve better economic return.  相似文献   

18.
A 12‐week growth trial was conducted in a flow‐through system to determine dietary selenium (Se) requirement for on‐growing gibel carp (initial body weight: 76.2 ± 0.05 g, mean ± SEM). Selenomethionine was supplemented to the basal diet to formulate seven semi‐purified diets containing 0.26, 0.58, 0.72, 1.14, 1.34, 1.73 and 2.09 mg Se kg?1 diet. The results showed that plasma superoxide dismutase (SOD) activity significantly increased when fish were fed with 0.58 mg Se kg?1 diet (P < 0.05) and then decreased at 2.09 mg Se kg?1 diet (P < 0.05). Plasma T‐AOC activity was higher in fish fed with 0.72 mg Se kg?1 diet (P < 0.05) and plasma malondialdehyde (MDA) was higher in fish fed with 0.26 mg Se kg?1 diet (P < 0.05). When fish were fed 1.14 mg Se kg?1 diet, hepatic GSH‐Px, T‐AOC, GSH and CAT activities were significantly higher than those fed with 0.26 mg Se kg?1 diet (P < 0.05). Hepatic superoxide dismutase (SOD) activity was higher at 1.34 mg Se kg?1 diet (P < 0.05). Fish liver Se concentrations were significantly higher when fed with 0.72 mg Se kg?1 diet (P < 0.05) and then kept constant when Se ≥ 0.72 mg kg?1 (P > 0.05). Whole‐body and muscle Se concentrations were higher when fed with 1.34 mg Se kg?1 diet (P < 0.05) and kept a plateau when Se ≥ 1.34 mg kg?1 (P > 0.05). In conclusion, based on broken‐line regression of hepatic Se concentrations, hepatic SOD activity and hepatic T‐AOC activity, dietary Se requirements for on‐growing gibel carp was 0.73 mg kg?1, 1.12 mg kg?1 and 1.19 mg kg?1 diet respectively.  相似文献   

19.
An optimal chemical shell marking protocol was developed for the New Zealand green‐lipped mussel, Perna canaliculus with a view to its future use in larval tracking experiments. Larval P. canaliculus aged either 10, 15 or 19 days post fertilization were immersed in treatments of 50, 100 and 200 mg L?1 of calcein for a period of 24 h before measurements of shell mark brightness were taken. There was 100% marking success in all calcein treatments for all age classes, with 19‐day larvae immersed in 200 mg L?1 calcein producing the brightest mark. Growth was not affected by calcein immersion; however, 10‐day larvae exhibited significantly higher levels of mortality compared with 15‐ and 19‐day larvae suggesting a reduced resilience to the marking protocols in younger larvae. In a mass staining experiment, a solution of 100 mg L?1 calcein was used to successfully stain15.6 million hatchery reared P. canaliculus larvae. Calcein, therefore, offers a low impact method with which to stain the sensitive early life stages of this species thus providing a rapid method for identifying individuals of interest, i.e. individuals released in the wild or specific family lines within a hatchery environment.  相似文献   

20.
A 9‐week feeding trial was conducted to determine the optimal dietary vitamin C requirement and its effects on serum enzymes activities and bacterial resistance in the juvenile yellow drum Nibea albiflora (initial weight 33.2 ± 0.10 g). Six practical diets were formulated containing vitamin C 2.1, 45.3, 89.6, 132.4, 178.6 and 547.1 mg kg?1 diet supplied as l ‐ascorbyl‐2‐monophosphate. The fish fed 547.1 mg kg?1 diet showed a significantly higher survival than that fed 2.1 mg kg?1 diet. The weight gains and specific growth rate of the fish fed 2.1 mg kg?1 diet were significantly lower than those of the fish fed 89.6–547.1 mg kg?1 diets. The liver vitamin C concentration firstly increased with increasing dietary vitamin C supply from 2.1 to 178.6 mg kg?1 diet and then stabilized. The serum superoxide dismutase activities of the fish fed 547.1 mg kg?1 diet were significantly lower than those of the fish fed 2.1–89.6 mg kg?1 diet. The fish fed 2.1 mg kg?1 diet had a significantly higher alkaline phosphatase activity than those in the other groups except the 45.3 mg kg?1 group. Fish that received diets containing vitamin C at 547.1 mg kg?1 had significantly higher nitro blue tetrazolium and lysozyme activity, and fish that received diets containing vitamin C at 45.3–547.1 mg kg?1 exhibited resistance against Vibrio alginolyticus infection. The dietary vitamin C requirement of the juvenile yellow drum was established based on broken‐line model of weight gain to be 142.2 mg l ‐ascorbyl‐2‐monophosphate kg?1 diet.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号