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1.
Spider crab, Maja brachydactyla, is a crustacean with interesting biological characteristics for intensive aquaculture. However, physiological studies are needed to establish the optimal conditions for its culture and maintenance. We analyzed the oxygen consumption response of spider crab to gradual hypoxia in relation to animal weight (W: 0.42–1.62 kg) and water temperature (T: 17.8–26.3 C), along with its ability to recover. Spider crab behaved as an oxygen regulator, maintaining its oxygen consumption constant until it reached critical oxygen saturation. This value varied between 24.1 and 53.3% oxygen saturation (42.4 ± 7.4% Sat.; 2.95 ± 0.43 mgO2/L), and significantly depended on the temperature (P < 0.01). The lethal oxygen saturation varied from 6.8 to 19.3% Sat. (12.57 ± 4.25% Sat.; 0.88 ± 0.29 mgO2/L) depending on temperature and body weight (P < 0.05). When oxygen levels were re‐established after exposure to acute hypoxia, the animals recovered, oxygen consumption remaining above the routine value for up to 15–20 h. We suggest survival oxygen saturation levels for spider crab of between 100 and 65% in the experimental conditions of this study.  相似文献   

2.
Methemoglobin is hemoglobin containing ferric iron. Methemoglobin cannot bind to oxygen and at high concentrations causes tissue hypoxia. Brook trout (Salvelinus fontinalis) develop significantly greater methemoglobinemia than Atlantic salmon (Salmo salar) or rainbow trout (Oncorhynchus mykiss) following general anesthesia with benzocaine or tricaine methanesulfonate. The objective of this study was to compare the activity of the major methemoglobin reducing enzyme, NADH-dependent cytochrome b5 reductase (CB5R), in brook trout erythrocytes to the activity of CB5R in Atlantic salmon and rainbow trout erythrocytes. Methemoglobin levels were compared using co-oximetry following in vitro incubation of erythrocytes with sodium nitrite (NaNO2). The CB5R activity was measured using a ferricyanide assay. There was significantly greater methemoglobin at time 0 in brook trout erythrocytes than in rainbow trout or Atlantic salmon erythrocytes (2.79 ± 0.29 %, 2.19 ± 0.23 %, 2.08 ± 0.14 %), (P < 0.001). There was significantly greater methemoglobin induction by NaNO2 in brook trout erythrocytes (33.14 ± 3.32 %) than in rainbow trout or Atlantic salmon erythrocytes (28.73 ± 2.92 % and 24.85 ± 1.40 %, respectively), (P < 0.001). The CB5R activity was significantly less in brook trout erythrocytes (median of 3.05 μmol/min/μl) than in rainbow trout erythrocytes (median of 6.73 μmol/min/μl). The CB5R activity in Atlantic salmon erythrocytes (median 4.09 μmol/min/μl) was not significantly different than in brook or rainbow trout erythrocytes. Total methemoglobin at any one time is a balance between induction by oxidants and reduction by antioxidants. Lower CB5R activity in brook trout erythrocytes may contribute to a species-specific sensitivity to methemoglobin induction; however, there are likely additional factors.  相似文献   

3.
During gradual air exposure, Amia calva show no reduction in oxygen consumption, no increase in plasma urea levels or in urea excretion. Blood pH remains constant, and plasma total CO2, PCO 2, HCO3 -. total ammonia and NH3 concentrations all rise significantly. Exposure to 923 μmol/l NH4Cl does not elicit an increase in urea production or airbreathing. Aquatic hypoxia without access to air does not cause a reduction in aerobic metabolism, and moderate levels result in death. These results suggest that Amia are incapable of aestivation, due to an inability to detoxify ammonia to urea and reduce metabolism, and die following three to five days of air exposure.  相似文献   

4.
Haematological parameters are often used as health status and stress indicators in fish. However, information on the effects of artificial photoperiods on these parameters is scarce and ambiguous. The consequences of three different artificial photoperiod regimes [light/day 12 h:12 h (LD 12:12) for 150 days as controls; LD 14:10 and LD 24:0, both for an initial 60 days, and then LD 12:12 for the remaining 90 days] were evaluated in trout. In all fish the haemogram and the erythrocyte production index (EPI) were assessed at days 7, 14, 30 and 60 (phase 1) and at days 90, 120 and 150 (phase 2). At the end of phase 1, photoperiods LD 14:10 and 24:0 induced higher production of immature (late basophilic) erythrocytes (0.06–0.08 × 1012 cells/l, P < 0.05) and elevated EPI (young erythrocytes = 1.6 in LD 14:10, 2.25 in LD 24:0; late basophilic erythrocytes = 4.1–4.9 in LD 14:10, 3.3 in LD 24:0) than in controls (late basophilic erythrocytes = 0.02–0.04 × 1012 cells/l; EPI young erythrocytes = 0.2–1.0; EPI late basophilic erythrocytes = 1.4–2.7). During phase 2, only reduced numbers of lymphocytes and thrombocytes were observed at day 150 in the LD 14:00 group. An increase in the EPI (1.9) of control young erythrocytes was found at day 150.  相似文献   

5.
Methemoglobin is oxidized hemoglobin that cannot bind to or dissociate from oxygen. In fish, it is most commonly caused by exposure to excess nitrites and can lead to abnormal swimming, buoyancy, or death. The methemoglobin concentration in mammals is determined by the balance of oxidizing agents versus reducing enzymes in erythrocytes. The objective of our studies was to characterize the enzymes that reduce methemoglobin in fish erythrocytes. Whole blood was collected from healthy rainbow trout. Methemoglobin was induced in vitro by NaNO2 exposure. Methemoglobin reduction in controls was compared to reduction in samples with added NADH, NADPH, or NADPH and methylene blue. Rainbow trout whole blood was also fractionated into cytosol, microsomal, and mitochondria/plasma membranes/nuclei fractions. The fractions were compared for NADH-dependent cytochrome b5 reductase (CB5R) activity and for nitrite induction of methemoglobin. The CB5R activity in rainbow trout erythrocytes was compared to the CB5R activity in equine, feline, and canine erythrocytes. Rainbow trout erythrocytes had significant NADPH methemoglobin reductase activity in the presence of methylene blue (P < 0.001). The CB5R activity was greatest (P < 0.001) in the plasma membrane/mitochondria/nuclei fraction. The CB5R activity in rainbow trout erythrocytes was not significantly different than canine or equine activity but was significantly lower than feline CB5R activity (P < 0.0001). Methemoglobin in rainbow trout erythrocytes can be reduced by CB5R or NADPH-dependent methemoglobin reductase. Unlike mammalian anuclear erythrocytes, which are dependent on soluble CB5R, the nucleated RBCs of rainbow trout use membrane-bound CB5R to reduce methemoglobin.  相似文献   

6.
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   

7.
The effect of purified macronutrients on specific dynamic action (SDA) was assessed in juvenile southern catfish (39.81 ± 1.35 g) at 27.5 °C by stuffing iso‐energetic (5 kJ) casein, corn oil, corn starch in sections of grass carp intestine (0.25 g). A control (without filler) and mixed diets were also made (each macronutrient provide one‐third energy). The postprandial metabolic response, i.e. the oxygen consumption curve, was markedly different among fish fed different food. The peak postprandial metabolic rate of fish fed mixed diet (76.7 mgO2 h−1) was significantly higher than that of protein group (66.1 mgO2 h−1), while the latter was significantly higher than those of other groups (56.1 mgO2 h−1 for lipid, 54.0 mgO2 h−1 for carbohydrate and 56.1 mgO2 h−1 for control) (P < 0.05). The SDA durations were 32, 32, 30, 14 and 10 h for mixed, casein, corn oil, corn starch and control groups, respectively. The SDA coefficient (energy expended on SDA as per cent of ingested energy) of casein (9.41%) was significantly higher than that of mixed diet (7.43%) (P < 0.05), while the latter was significantly higher than those of corn oil (3.97%) and corn starch (0.84%) (P < 0.05). The results of this study suggested that the method of using casing on investigation of SDA in carnivorous fish was feasible. The SDA response of carnivorous southern catfish fed protein was higher than lipid while latter was higher than carbohydrate (nearly to zero). The result of this study may give interesting information for understanding the physiological mechanism under SDA.  相似文献   

8.
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   

9.
Immature erythrocytes or polychromatophils are commonly found in low percentages and at different maturational stages in fish peripheral blood. The concentration of these cells is indicative of the erythropoietic status, which can be modulated by environmental factors such as oxygen availability and temperature. To assess the consequences of constant artificial light on erythropoiesis, polychromatophils were quantified in two groups of rainbow trout. At the end of the experiment, fish exposed to two months of constant light showed an increase of immature erythrocytes from 0.07 × 1012 to 0.11 × 1012 cells/l along with a marked decrease in their polychromatophilic intensity, which almost disappeared 5 months after resuming natural photoperiod. In this group after an initial increase, a decrease in immature erythrocyte numbers was observed, suggesting that application of constant light causes a late depression of erythropoiesis in trout. The transient increase of polychromatophils in the same maturity state may be an indicator of a deviation towards other metabolic needs, such as initiation of reproduction.  相似文献   

10.
Respiratory parameters of grass carp were studied during dissolved oxygen (DO) changes from normal DO to hypoxia, then return to normal DO at 15, 25, and 30 °C acclimation, respectively. The results showed that with increases of acclimation temperature at normoxia the respiratory frequency (fR), oxygen consumption rate (VO2), respiratory stroke volume (VS.R), gill ventilation (VG), and VG/VO2 of grass carp increased significantly, but the oxygen extraction efficiency (EO2) of fish decreased significantly (P < 0.05). With declines of DO levels, the fR, VS.R, VG, and VG/VO2 of fish increased significantly at different acclimation temperatures (P < 0.05). A slight increase was found in VO2, and the EO2 of fish remained almost constant above DO levels of 3.09, 2.91, and 2.54 mg l?1 at 15, 25, and 30 °C, while the VO2 and EO2 began to decrease significantly with further reductions in DO levels (P < 0.05). After 0.5 h of recovery to normoxia from hypoxia at three acclimation, the fR, VS.R, VG, and VG/VO2 of the fish decreased sharply; meanwhile, the VO2 and EO2 increased sharply (P < 0.05). The respiratory parameters of fish gradually approached initial values with prolonged recovery time to normoxia, and reached their initial values in 2.5 h at 25 and 30 °C acclimation. The critical oxygen concentrations (Cc) of fish for VO2 were 2.42 mg l?1 at 15 °C, 2.02 mg l?1 at 25 °C, and 1.84 mg l?1 at 30 °C, respectively. The results suggest that grass carp are highly adapted to varied DO and short-term hypoxia environments.  相似文献   

11.
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12.
Yeast is a potential alternative to fish meal in diets for farmed fish, yet replacing more than 50 % of fish meal results in reduced fish growth. In a 4-week experiment, 15 rainbow trout (Oncorhynchus mykiss) were cannulated and fed three diets each week: 30 % fish meal as a control (FM); 60 % replacement of fish meal protein, on a digestible basis, with Saccharomyces cerevisiae (SC); and 60 % replacement with Wickerhamomyces anomalus and S. cerevisiae mix (WA). Blood was collected at 0, 3, 6, 12 and 24 h after feeding. In the final week, fish were exposed to a 1-min netting stressor to evaluate possible diet–stress interactions. Significant increases in pH, TCO2, HCO3 and base excess were found after fish were fed the SC and WA diets compared with FM, which elevated blood alkaline tides. Yeast ingredients had lower buffering capacity and ash content than fish meal, which explained the increase in alkaline tides. In addition, fish fed the WA diet had significantly reduced erythrocyte area and fish fed SC and WA diets had increased mean corpuscular haemoglobin levels, indicating haemolytic anaemia. Higher levels of nucleic acid in yeast-based diets and potentially higher production of reactive oxygen species were suspected of damaging haemoglobin, which require replacement by smaller immature erythrocytes. Acute stress caused the expected rise in cortisol and glucose levels, but no interaction with diet was found. These results show that replacing 60 % of fish meal protein with yeasts can induce haemolytic anaemia in rainbow trout, which may limit yeast inclusion in diets for farmed fish.  相似文献   

13.
Hypoxia results in elevated circulating epinephrine for many fish species, and this is likely important for maintaining cardiac function. The aims of this study were to assess how hypoxia impacts contractile responses of ventricular compact and spongy myocardium from rainbow trout (Oncorhynchus mykiss) and to assess how and if epinephrine may protect myocardial performance from a depressive effect of hypoxia. Work output and maximum contraction rate of isolated preparations of spongy and compact ventricular myocardium from rainbow trout were measured. Tissues were exposed to the blood PO2 that they experience in vivo during environmental normoxia and hypoxia and also to low (5 nM) and high (500 nM) levels of epinephrine in 100% air saturation (PO2 20.2 kPa) and during hypoxia (PO2 2 kPa, 10% air saturation). It was hypothesized that hypoxia would result in a decrease in work output and maximum contraction rate in both tissue types, but that epinephrine exposure would mitigate the effect. Hypoxia resulted in a decline in net work output of both tissue types, but a decline in maximum contraction rate of only compact myocardium. Epinephrine restored the maximum contraction rate of compact myocardium in hypoxia, appeared to slightly enhance work output of only compact myocardium in air saturation but surprisingly not during hypoxia, and restored net work of hypoxic spongy myocardium toward normoxic levels. These results indicate hypoxia has a similar depressive effect on both layers of ventricular myocardium, but that high epinephrine may be important for maintaining inotropy in spongy myocardium and chronotropy in compact myocardium during hypoxia.  相似文献   

14.
The mudskipper Scartelaos gigas is expected to experience repeated severe hypoxia in its environment. Hence, we conducted experiments on the oxygen consumption rate (OCR) and OCR rhythm of S.?gigas at low graded dissolved oxygen (DO) levels, without access to atmospheric air, to estimate its tolerance to hypoxia. A dominant circadian OCR rhythm was observed at the control DO level of 6.96?C7.78?mg?O2/l. This rhythm was unchanged until 2.06?mg?O2/l, even though the amplitude of the peak was somewhat diminished at 2.06?C2.87?mg?O2/l. The OCR rhythm amplitude was greatly diminished and the rhythm period was also greatly changed at 1.23?C2.05?mg?O2/l. Nevertheless, the mean OCR (0.11?ml?O2/g WW/h) at 1.23?C2.05?mg O2/l was similar to that of control (0.12?ml O2/g?WW/h). Thus, the weakness and period change of the OCR rhythm kept the metabolic rate level similar to control. These results suggest that S.?gigas does not have normal metabolic activity at 1.23?C2.05?mg O2/l but barely manages to endure this DO level as a pre-emergency state. This species could be inhibited under a longer maintenance period at DO level of 1.23?C2.05?mg?O2/l or still lower. It can be concluded that S.?gigas is quite tolerant to low DO environment and may have a specific strategy for such tolerance.  相似文献   

15.
Soft water acclimated (Ca2+ 0.02 mM; Na+ 0.03 mM; K+ 0.01 mM; pH 7.0), cannulated brown trout (Salmo trutta) were exposed to various pH and aluminium (Al) regimes (pH 7.0, pH 5.0, pH 5.0 plus Al: 50, 25, and 12.5 g l–1) for up to 5 days in order to determine (i) the sublethal concentration of Al at pH 5.0 for this species (ii) their ionoregulatory and respiratory status. No mortality or physiological disturbances were evident at pH 7.0 or pH 5.0. All trout died within 48 h at pH 5.0 in the presence of Al at 50 g l–1 and 67% died over the 5 day period at pH 5.0 in the presence of Al at 25 g l–1. Fish at these lethal Al concentrations showed significant decreases in arterial blood oxygen content (CaO2) but no changes in plasma osmolarity or the concentrations of plasma Na+, K+ and Cl–. Physiological disturbance was more marked at the 50 g l–1 Al concentration. The surviving fish at 25 g l–1 showed few signs of physiological recovery while continually exposed to this regime. No fish died during the exposure to water of pH 5.0 containing 12.5 g l–1 Al, but physiological disturbance was still apparent. These sublethally-stressed trout showed a transient decline in the plasma concentrations of Na+ and Cl–1. Although CaO2 decreased, recovery was evident. The data suggest that in the brown trout, environmental Al concentration is as important as pH and calcium concentration in determining the physiological status of the fish.  相似文献   

16.
《水生生物资源》1998,11(2):87-92
This work studied some of the metabolic responses of Nephrops norvegicus to a progressive reduction in water oxygen tension (PwO2) at 12 °C. Experiments were designed to simulate water quality conditions that may occur during the trade of live crustaceans. Oxygen consumption rates and ammonia efflux rates were found to be constant over a wide range of PwO2 values (20.4–5.9 kPa). A similar result was found for the difference between post-branchial and pre-branchial oxygen concentrations (20.4–2.6 kPa), obtained from a separate experiment. Anaerobic pathways, however, were activated after PwO2 reached 6.3 kPa, as blood lactate and glucose concentrations increased from 1.24 ± 0.08 and 1.17 ± 0.19 (T0 values) to 10.55 ± 8.99 and 3.63 ± 0.89 mg · 100 mL−1 respectively. N. norvegicus was able to maintain blood pH levels at relatively constant values despite a drop in water pH levels and the accumulation of lactate observed at low PwO2. Heart rates also remained stable during PwO2 reductions, but scaphognathite beat rate increased considerably, probably as an attempt to maintain steady weight-specific oxygen consumption rates. N. norvegicus appeared to be well adapted to cope with progressive hypoxia as may occur during holding and transportation procedures.  相似文献   

17.
Although thermal influences on the physiology of rainbow trout (Oncorhynchus mykiss) have been widely studied, there is little information about the responses of different genetic strains to temperatures. The effects of water temperature (10, 14, 19, 22, and 25 °C) on food consumption rate, growth rate, gross conversion efficiency, resting routine oxygen consumption rate, upper critical thermal tolerance and critical swimming velocity were investigated in juvenile rainbow trout of the Eagle Lake (O. m. aquilarum) subspecies and the Mt. Shasta strain. No strain-related differences in conversion efficiency, oxygen consumption rates, thermal tolerance or swimming performance were observed in 1995 (19, 22, and 25 °C) or 1996 (10, 14, and 19 °C), but Mt. Shasta strain trout grew faster at highest temperatures than did Eagle Lake trout. Food consumption rates, growth rates, conversion efficiency, and oxygen consumption rates declined at the extreme temperatures (10 and 25 °C) in both Eagle Lake and Mt. Shasta trout. Swimming performance was temperature-independent between 10 and 19 °C (overall mean: 5.43 body lengths s–1).  相似文献   

18.
The pollution loading from Øxna Bruk, a trout farm with an annual fish production of 200–250 tons, and the influence on the water quality of River Figgjo, a mediumsized watercourse, was studied. The feed used was dry pellets. The loadings were estimated to be 0.3–0.8 g N/kg fish.24h; 0.05 g P/kg fish.24h; and 1.6–4.6 g O/kg fish.24 h as BOD7 (biochemical oxygen demand, 7 days). As a result of the fish farming activities, moderate chemical alterations were registered in the river downstream of the farm at low river flow: decreased oxygen concentration (÷ 1 mg/l) and increased concentrations of total-N (+ 0.2 mg N/l), NH3 + NH4+ (+ 0.1 mg N/l), total-P (+ 0.03 mg P/l) and ortho-P (+ 0.02 mg P/l). Compared with the receiving water, BOD7 increased maximally 1 mg O/l downstream of the farm. The salmonid stocks in the river were not affected by the effluents from the trout farm.  相似文献   

19.
Changes in heart rate, ventilatory activity and oxygen consumption were determined in trout (Salmo gairdneri) and brown bullhead catfish (Ictalurus nebulosus) during exposure to a steadily increasing concentration of waterborne cyanide selected to produce death in 8–9 hours for each species. The lethal cyanide concentration for the bullheads was an order of magnitude higher than for trout. Trout developed an immediate and gradually increasing bradycardia throughout the exposure period. Cyanide produced tachycardia in the bullhead followed by a gradual onset of bradycardia as the concentration of cyanide was raised. Pericardial injection of atropine (a muscarinic cholinergic antagonist) indicated that bradycardia in the trout was due initially to increased vagal tone but later due to the direct effect of cyanide on the heart. Hyperventilation in the trout persisted throughout the exposure period, although the rate and amplitude fluctuated and was variable between individual fish. During the last hour of exposure (highest cyanide concentration), ventilation was characterized by rapid, shallow breaths followed by a sudden respiratory arrest. The bullheads exhibited hyperventilation during the first 3 hours of exposure followed by a gradual, linear drop in ventilation rate and amplitude until death occurred. Cardiac and ventilatory responses in both species were attributed to stimulation of central and peripheral chemoreceptors by cyanide. Evidence is presented which suggests the initial response in the bullheads was due, at least in part, to gustatory stimulation by the cyanide. Oxygen consumption of the trout remained above pre-exposure levels for the majority of the test period. Oxygen consumption in the bullhead paralleled the changes in heart and ventilatory rates. Whole-body lactate levels of fingerlings of both species during cyanide exposure were measured to estimate the extent of anaerobiosis. Whole-body lactate levels were much greater in the bullheads than the trout, indicating a higher capacity for anaerobiosis, possibly due to a greater fuel supply. Overall, the trout responded to cyanide in a manner similar to that produced by environmental hypoxia whereas the bullheads experienced a gustatory stimulus which masked the hypoxia-like response.  相似文献   

20.
Effects of adrenaline on the equilibrium distributions of Na+ , K+ , H+ , Cl– , and H2O across the cell membrane of rainbow trout (Salmo gairdneri) erythrocytes were determinedin vitro, as a function of P CO2 (1.76–7.77 torr). CO2-carrying capacity of the blood was also examined. Plasma catecholamine concentrations inunanaesthetized, unrestrained trout were 3.1 nM adrenaline and 1.2 nM noradrenaline. Elevation of the plasma adrenaline concentrationin vitro to 4.6 × 103 nM resulted in net gains of Na+ , Cl– and H2O by red cells, a net loss of H+ from red cells, and a pronounced red cell swelling. Adrenaline also reduced the CO2-carrying capacity of trout bloodin vitro. The magnitudes of these effects increased with PCO2 and, thus, were sensitive to blood HCO3 – concentrations. The distribution of K+ between red cells and plasma was unaffected by adrenaline. Adrenergic-mediated ion movements and red cell swelling were sensitive to both propranolol and SITS. These results are consistent with the symport NaCl uptake model for adrenergic-mediated swelling of Baroinet al. (1984). The adrenergic response of fish erythrocytes may function to ameliorate the effects of blood acidoses on O2-carrying capacity by maintaining red cell pH in the face of a decrease in plasma pH.  相似文献   

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