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1.
Effects of temperature on food consumption, growth and oxygen consumption were estimated for the freshwater prawn Macrobrachium rosenbergii postlarvae at 23 °C, 28 °C and 33 °C in the laboratory. The results showed that the animal's initial body weight had a close linear relationship with food consumption and growth. Food consumption increased directly with temperature. Consumption rates (C; mg day?1 ind?1 ) of the 28 °C and 33 °C groups were much higher than that of the 23 °C group (P < 0.001), and the 33 °C group's consumption rate was higher than that of the 28 °C group (P < 0.05). The relationship of food consumption with temperature and initial body weight (W; mg) could be described as: C = 0.0679W + 0.185t? 3.17. Growth increased significantly with increased temperature. The relationship among specific growth rate, temperature and initial body weight was as follows: SGR = ?0.110W + 0.213t + 0.176. However, temperature showed no effect on growth efficiency. Oxygen consumption increased significantly with temperature (P < 0.01). The weight‐specific oxygen consumption rates (mg O2 g?1 h?1) at 23 °C, 28 °C and 33 °C were 0.83, 1.16 and 1.49 mg O2 g?1 h?1 for 61.92 mg M. rosenbergii.  相似文献   

2.
Pharmacokinetics and residue elimination of marbofloxacin (MBF) were studied in crucian carp (Carassius auratus, 250±30 g) kept at two water temperatures of 15 and 25 °C. Marbofloxacin concentrations in plasma and tissues were analysed by means of high‐performance liquid chromatography using an ultraviolet detector. The limits of detection were 0.02 μg mL?1, 0.02 μg g?1, 0.025 μg g?1, 0.02 μg g?1 and 0.025 μg g?1 in plasma and muscle, skin, liver and kidney respectively. Fish were administered orally at a single dosage of 10 mg kg?1 body weight in the PK group. The data were fitted to two‐compartment open models at both temperatures. At 15 °C, the absorption half‐life () and distribution half‐life (t1/2α) of the drug were 0.36 and 4.48 h respectively. The corresponding values at 25 °C were 0.23 and 0.87 h respectively. The elimination half‐life (t1/2β) was 50.75 h at 15 °C and 25.05 h at 25 °C. The maximum MBF concentration (Cmax) differed little between 15 (6.43 μg mL?1) and 25 °C (8.36 μg mL?1). The time to peak concentration was 1.74 h at 15 °C and 0.78 h at 25 °C. The apparent volume of distribution (Vd/F) of MBF was estimated to be 1.36 and 0.87 L kg?1 at 15 and 25 °C respectively. The area under the concentration–time curve (AUC) was 301.80 μg mL?1 h at 15 °C and 182.80 μg mL?1 h at 25 °C. The total clearance of MBF was computed as 0.03 and 0.05 L h?1 kg?1 at 15 and 25 °C respectively. After repeated oral administration at a dosage of 10 mg kg?1 body weight per day for 3 days, the results showed that the elimination half‐lives () of MBF from all tissues at 15 °C were longer than that at 25 °C. Therefore, water temperature is an important factor to be considered when deciding a reasonable withdrawal time.  相似文献   

3.
Feed requirements were estimated from specific growth rates in standardized soft tissue dry weight (SGRDW’) and atomic O:N ratios for mussels fed seven rations of microalgae (5–735 μg C h?1 ind?1) at 7 and 14°C respectively. The mean oxygen consumption and ammonia‐N excretion rates were significantly higher at 14°C (0.29 μg O2 and 27.3 μg N ind?1 h1) compared with those at 7°C (0.16 μg O2 and 11.4 μg N ind?1 h?1) (P < 0.05), resulting in O:N ratios between 3 and 45 at 7°C and 7 and 28 at 14°C. Low O:N ratios indicate protein catabolism and an unfavourable condition, whereas high ratios indicate that carbohydrate is the primary energy source. The measured SGRDW’ suggests minimum feed requirements of ~240 and ~570 μg C ind?1 h?1 for weight maintenance at 7 and 14°C, with corresponding O:N ratios of 24 and 16, respectively, indicating a more stressed condition at 14°C. A 0.5% SGRDW’ day?1 was obtained by ~565 (O:N = 29) and ~680 (O:N = 23) μg C ind?1 h?1 at 7 and 14°C respectively. A positive and significantly higher SGRDW’, with the lowest feed ration at 7°C compared with a negative SGRDW’ at 14°C (P < 0.05), indicated that storage time can also possibly be prolonged at low temperatures if the mussels are not fed.  相似文献   

4.
Some metabolic end‐products in tissues and physiological parameters of haemolymph of the Japanese clam Ruditapes philippinarum (Adams & Reeve) were investigated under aerial exposure at 15 °C with low relative humidity (RH) (22%) or high RH (91%). Acclimated clams in water at 15 °C were used as a control and to supply the low or high RH experiment. The low RH experiment was conducted at air exposure for 50 h (LH50), and the high RH experiment for 50 h (HH50) and 100 h (HH100). Accumulation of succinate and alanine in the tissues proved that the clam shifted its metabolism to anaerobiosis. Lactate accumulation did not occur. Glucose concentrations in tissues increased slightly during exposure except for HH50. The total free amino acid contents (363–410 μmol g?1) were higher than those of glucose (530–804 μmol 100 g?1), suggesting that the free amino acids might play a more dominant role in the metabolism. Increase in the haemolymph pco 2 did not influence the acid–base balance in the haemolymph during exposure at both humidity conditions. Increase in the haemolymph ammonia from 48.2 to 57.1 μmol 100 g?1 and to 131.0 μmol 100 g?1 at LH50 and HH100, respectively, suggested that ammonia might function as an important buffering factor during aerial exposure. Retention values of the haemolymph po 2 even at the longest exposure time (16.30 mmHg at LH50 and 14.69 mmHg at HH100) indicated that the clams depend partially on some aerobic manner.  相似文献   

5.
Nile tilapia Oreochromis niloticus (L.) held in timed‐pulse feeding chambers, were provided with algal‐rich water dominated by either green algae (Scenedesmus, Ankistrodesmus, Chlorella and Tetraedron) or cyanobacteria (Microcystis) to determine the effect of temperature and phytoplankton concentration on filtration rates. Green algae and cyanobacteria filtration rates were measured as suspended particulate organic carbon (POC) kg?1 wet fish weight h?1. Ivlev's filter‐feeding model described the relationships between filtration rates and suspended POC concentration of green algae and cyanobacteria. Filtration rates of both green algae and cyanobacteria increased linearly as water temperature increased from 17 °C to 32 °C and were significantly higher in the warm‐water regime (26–32 °C) than in the cool‐water regime (17–23 °C). Filtration rates at 95% saturation POC (FR95) in green algal and cyanobacterial waters were 700 mg C kg?1 h?1 and 851 mg C kg?1 h?1 in the warm‐water regime and 369 mg C kg?1 h?1 and 439 mg C kg?1 h?1 in the cool‐water regime respectively. The FR95 in warm water were achieved at lower POC concentrations than in cool water.  相似文献   

6.
The metabolic physiological response to body mass, temperature (12–28 °C) and salinity (20–36 g L?1) was examined in this paper. Oxygen consumption rate, which is dependent on environmental conditions, was exponentially related to body mass and varied from 0.045 to 1.11 mg h?1 g?1. Oxygen consumption rate increased as salinity increased from 20 to 36 g L?1, and increased with increasing temperature. The effect of temperature gradient between experimental treatments on oxygen consumption rate was evaluated by calculating Q10 (the Arrehenius relationship for increase with temperature). The Q10 value within the temperature range from 12 to 16 °C was much higher than the value within the temperature range from 16 to 20 °C, 20 to 24 °C and 24 to 28 °C, indicating a reduced temperature dependence of ascidian metabolism at a high temperature.  相似文献   

7.
The effects of acclimation temperature (15, 20, 25 °C) on routine oxygen consumption and post-exercise maximal oxygen consumption rates (MO2) were measured in juvenile shortnose sturgeon (Acipenser brevirostrum LeSueur, 1818). The routine MO2 of shortnose sturgeon increased significantly from 126.75 mg O2 h?1 kg?1 at 15 °C to 253.13 mg O2 h?1 kg?1 at 25 °C. The temperature coefficient (Q 10) values of the routine metabolic rates ranged between 1.61 and 2.46, with the largest Q 10 values occurring between 15 and 20 °C. The average post-exercise MO2 of all temperature groups increased to a peak value immediately following the exercise, with levels increasing about 2-fold among all temperature groups. The Q 10 values for post-exercise MO2 ranged from 1.21 to 2.12, with the highest difference occurring between 15 and 20 °C. Post-exercise MO2 values of shortnose sturgeon in different temperature groups all decreased exponentially and statistically returned to pre-exercise (resting) levels by 30 min at 15 and 20 °C and by 60 min at 25 °C. The aerobic metabolic scope (post-exercise maximal MO2-routine MO2) increased to a maximum value ～156 mg O2 h?1 kg?1 at intermediate experimental temperatures (i.e., 20 °C) and then decreased as the temperature increased to 25 °C. However, this trend was not significant. The results suggest that juvenile shortnose sturgeon show flexibility in their ability to adapt to various temperature environments and in their responses to exhaustive exercise.  相似文献   

8.
The effect of irradiance and temperature on the photosynthesis of two Japanese agarophytes, Gelidium elegans and Pterocladiella tenuis (Gelidiales), was determined using dissolved oxygen sensors and pulse amplitude modulated (PAM) fluorometry. Gross photosynthesis and dark respiration rates were determined over a range of temperatures (8–36 °C). The highest gross photosynthetic rates were 40.3 and 37.0 mg O2 g ww ?1  min?1 and occurred at 24.3 and 25.5 °C [95 % Bayesian credible interval (BCI) 20.7–28.0 and 23.4–28.3 °C], respectively. The dark respiration rate in G. elegans and P. tenuis increased with increasing temperature at a rate of 0.10 and 0.31 mg O2 g ww ?1  min?1 °C?1 , respectively. Modeling the net photosynthesis–irradiance (P–E) responses of G. elegans and P. tenuis at 20 °C revealed that the net photosynthetic rates quickly increased at irradiance levels below the estimated saturation irradiance of 88 and 83 µmol photons m?2 s?1, with a compensation irradiance of 14 and 19 µmol photons m?2 s?1, respectively. The highest value of the maximum effective quantum yield (Φ PSII) occurred at 20.1 °C (BCI 18.9–21.5 °C) and 21.3 °C (BCI 20.2–22.5 °C) for G. elegans and P. tenuis and was 0.49 and 0.45, respectively. These optimal temperatures of Φ PSII were relatively lower than those determined by the photosynthesis–temperature model of oxygen evolution. The temperature response of these species indicates that they are probably well adapted to the current range of seawater temperatures in the study site but that they are near the boundary of their tolerable limits.  相似文献   

9.
Members of heat shock protein 70 (HSP70) are highly conserved proteins of about 70 kDa and play important roles in protein folding. Levels of these proteins increase when cells are under stress. Environmental temperature influences both the basal and induced levels of HSPs. However, studies on HSPs in fishes from a tropical country such as India are lacking. In the present study, Indian major carp (IMC) Cirrhinus mrigala (Ham.) acclimatized at 25±2°C had high levels of HSP70, viz., 1.2–1.3 ng μg?1 total protein in kidney and gill and 4.2–5.3 ng μg?1 total protein in liver and brain tissues, indicating the presence of biochemically significant levels of stress. However, maintenance of acclimatized fish at 17°C for up to 48 h did not lead to a significant decrease in stress protein levels. A heat shock at 37°C for up to 48 h resulted in only two to threefold increase in HSP70 levels in these organs. Although the increase in HSP70 levels was apparent from the first hour of heat stress in all these tissues, the increase was significant from the second hour in the brain, the sixth hour in liver and kidney and the 20th hour in the gills.  相似文献   

10.
This study examined ammonia, urea, creatinine, protein, nitrite, nitrate, and phosphorus (P) excretion at different water hardness, humic acid, or pH levels in silver catfish (Rhamdia quelen) juveniles. The fish were exposed to different levels of water hardness (4, 24, 50, or 100 mg L?1 CaCO3), humic acid (0, 2.5, or 5.0 mg L?1), or pH (5.0, 6.0, 7.0, 8.0, or 9.0) for 10 days. The overall measured nitrogen excretions were 88.1 % (244–423 μmol kg?1 h?1) for ammonia, 10.9 % (30–52 μmol kg?1 h?1) for creatinine, 0.02 % (0.05–0.08 μmol kg?1 h?1) for protein, 0.001 % (0.002–0.004 μmol kg?1 h?1) for urea, 0.5 % (0.64–3.6 μmol kg?1 h?1) for nitrite, and 0.5 % (0.0–6.9 μmol kg?1 h?1) for nitrate, and these proportions were not affected by water hardness or humic acid levels. The overall P excretion in R. quelen was 0.14–2.97 μmol kg?1 h?1. Ammonia excretion in R. quelen usually was significantly higher in the first 12 h after feeding, and no clear effect of water hardness, humic acid levels, and pH on this daily pattern of ammonia excretion could be observed. Water hardness only affected the ammonia and P excretion of R. quelen juveniles in the initial and fifth days after transfer, respectively. The exposure of this species to humic acid increased ammonia excretion after 10 days of exposure but did not affect P excretion. An increase in pH decreased ammonia and increased creatinine excretion but did not change P excretion in R. quelen. Therefore, when there is any change on humic acid levels or pH in the culture of this species, nitrogenous compounds must be monitored because their excretion rates are variable. On the other hand, P excretion rates determined in the present study are applicable to a wide range of fish culture conditions.  相似文献   

11.
To investigate the illuminance requirements for the culture of red algae in finfish effluent, both Chondrus crispus and Palmaria palmata were assessed simultaneously at three irradiances. Apical tips, 3.5 cm length, were stocked at 2 g L?1 in 1-L glass flasks with enriched seawater in two 24-day experiments, at 10 and 14 °C, respectively. Palmaria grew up to 70 % better and up took more nutrients than Chondrus under five of the six experimental conditions, except at 14 °C and low irradiance (daily photon dose of 3.4 mol photon m?2 day?1). Specific growth rate of both species at high irradiance, 13.1 and 17.2 mol photon m?2 day?1, at each trial, 10 and 14 °C, respectively, was 40 and 20 % better than at medium irradiance, but nutrient uptake was similar at both medium and high irradiance. Chondrus growth rate was higher during Experiment 2 (14 °C and 17.2 mol photon m?2 day?1) than during Experiment 1 (10 °C and 13.1 mol photon m?2 day?1), while Palmaria growth rate was similar in both trials, but always significantly higher than Chondrus. In the range 10–14 °C, Palmaria is the best candidate for integration with Atlantic halibut juveniles (Hippoglossus hippoglossus).  相似文献   

12.
Gastrointestinal and serum absorption of astaxanthin was studied in rainbow trout, Oncorhynchus mykiss (Walbaum) (217 ± 2 g) fed diets supplemented with either esterified astaxanthin (from Haematococcus pluvialis) or free astaxanthin (synthetic, as 8% w/w beadlets) at similar levels (50 mg kg?1). After 56 days of feeding, there was a significant difference (P = 0.0582) between steady‐state serum astaxanthin concentrations for fish fed free (2.0 ± 0.3 μg mL?1) or esterified astaxanthin (1.3 ± 0.1 μg mL?1) at the 90% confidence level. However, following ingestion of a single meal supplemented with free or esterified astaxanthin, the rates of astaxanthin absorption into serum were not significantly different (P > 0.1) (0.8 ± 0.2 µg mL?1 h?1 and 1.0 ± 0.4 µg mL?1 h?1 respectively). In fish fed both free or esterified astaxanthin, higher absorption (P < 0.05) of astaxanthin by the ileal (0.8 ± 0.14 μg g?1 and 0.9 ± 0.15 μg g?1 respectively) compared with the posterior (0.2 ± 0.01 μg g?1 and 0.3 ± 0.14 μg g?1 respectively) intestine was recorded. This confirmed the role of the anterior intestine in carotenoid absorption. Non‐detectable levels of esters in digesta taken from the hind intestine suggest the anterior intestine is also the primary region for ester hydrolysis.  相似文献   

13.
A study was conducted to establish whether a particulate form of ascorbic acid (AA), ascorbyl‐2‐phosphate (A2P), could be used to enrich Artemia. In the first experiment, we examined the efficiency of A2P conversion to and maintenance of AA by juvenile Artemia (1.5 mm, 5‐day‐old) held at 9000 L?1 and 28 °C for 24 h. Maximal uptake and assimilation was >10 000 μg AA g?1 dry weight (dw) (representing >1%Artemia dw) at enrichment rates of ≥1.2 g A2P L?1. In the second experiment, a similar biomass of instar II/III nauplii (1 mm, 2‐day‐old) and juvenile (2.5 mm, 8‐day‐old) Artemia were enriched for 6 or 24 h at 28 °C before starvation for 6 or 24 h at 18 or 28 °C. At 0 h and after 6 and 24 h enrichment, AA levels were 485, 3468 and 11 080 μg g?1 dw in nauplii and 122, 4286 and 12 470 μg g?1 dw in juveniles. When Artemia nauplii or juveniles were enriched for 6 h and starved for 6 h at 18 or 28 °C, there was no significant reduction in AA. Continuation of starvation to 24 h at 18 and 28 °C reduced the level of AA to 3367 and 2482 μg g?1 dw in nauplii and 3068 and 2286 μg g?1 dw in juveniles. After 24 h enrichment, 6 h of starvation at 18 and 28 °C reduced AA to 8847 and 7899 μg g?1 dw in nauplii and to 9053 and 8199 μg g?1 dw in juveniles. Continuation of starvation to 24 h at 18 and 28 °C further reduced AA levels in nauplii to 6977 and 4078 μg g?1 dw and to 7583 and 5114 μg g?1 dw in juveniles. This study demonstrated that A2P could be assimilated as AA in the body tissue of different‐sized Artemia in a dose‐dependant manner and AA was depleted during starvation depending on time and temperature.  相似文献   

14.
Three cooling rates of 1.26±0.09°C h?1 within 8 h (slow, T1), 2.52±0.18°C h?1 within 4 h (moderate, T2) and 5.04±0.36°C h?1 within 2 h (fast, T3) were tested to cold‐anaesthetize farm raised Macrobrachium rosenbergii (De Man) (45–52 g) in each case from 25°C down to 15±1°C in a refrigerated chilling tank, provided with aeration. The cold‐anaesthetized prawns subjected to each chilling rate were packed in an insulated cardboard box (triplicate) between two layers of moist and chilled (2–3°C) sawdust, and kept inside a chilled storage cabinet at 15±1°C, for set durations of 6, 9, 12, 15 and 18 h. Survival was determined by revitalizing the prawns in aerated water with an initial temperature of 20°C, which was raised to 29±1°C within 3 h. The experiment was repeated using berried females acclimated to brackishwater of 12 g L?1 salinity and the percentage survival recorded after live storage for durations ranging from 6 to 24 h at intervals of 3 h. Statistically valid safe durations for obtaining 100% survival of the cold anaesthetized and live stored prawns were determined using probit analysis at the three chilling rates tested, and were found to be 7.39, 6.98 and 4.54 h in the case of adult prawns, and 7.87, 8.17 and 6.43 h for berried females for T1, T2 and T3 respectively. For practical purposes, the durations that yielded 95% survival rates were computed to be 16.47, 12.14 and 8.35 h in the case of adult prawns and 18.49, 19.02 and 11.11 h for berried females for T1, T2, and T3 respectively. The berried prawns revitalized after live storage were incubated in tanks and the zoea larvae reared up to postlarvae (PL‐5), and compared against a control. No significant difference was found in larval hatch fecundity, survival rate and the production of PL L?1 between the treatment and control, indicating that the method of cold anaesthetization and live storage of berried prawns could be used for successful transportation of broodstock.  相似文献   

15.
Oxygen consumption (OC) and ammonia excretion rates (AE) of perch were measured under commercial‐like conditions (temperature 23.3 °C) in both fed (F) and feed‐deprived groups (D). Measurements were taken in triplicate in six sized batches of perch ranging from 44.8 to 336.2 g. The mean daily OC was 288.3–180.6 mg O2 kg?1 h?1 for group F fish ranging in size from 44.8 to 279.4 g body weight. The mean daily AE expressed as total ammonia nitrogen (TAN) was 13.8–5.2 mg TAN kg?1 h?1 in the same groups. Daily peaks of OC in group F perch were observed 6 h after the onset of feeding for each size group with relatively stable values up to the end of feeding. Peaks of daily AE in group F perch were observed 10 h after the onset of feeding in each size group, with a rapid decrease up to 16 h after onset. In group D, OC was 181.1–110.5 mg O2 kg?1 h?1 in the weight range 57.9–336.2 g. The daily mean AE was 1.7–0.5 TAN kg?1 h?1 in this group. No dramatic peaks of OC and AE were observed in group D perch.  相似文献   

16.
Galaxias maculatus is an osmeriform native fish of the Southern Hemisphere, in which the crystalline larvae is considered as a luxury delicacy, for this reason, it has been commercially exploited in Chile, Argentina and New Zealand. However, the fisheries have been rapidly decreasing due to the overexploitation and the predation of introduced species. Because of these events, there is a need to determine a carrying capacity for an intensive fish culture. In order to optimize stocking densities for fish culture, this paper proposes objectives to determine oxygen consumption (OC) rates, dissolved oxygen concentrations that produce signs of hypoxia and the average time elapsed between food intake and peak OC in G. maculatus. In the oxygen experiments under routine metabolism conditions, we found that G. maculatus adults and whitebait showed signs of asphyxia at dissolved oxygen concentrations between 1.3 and 2.2 mg L?1 and that adults tolerated dissolved oxygen levels as low as 1.3 mg L?1. The results showed that G. maculatus individuals with an average weight of 0.04 g consumed 0.048 mg O2 h?1, whereas individuals with an average weight of 1.4 g consumed 0.345 mg O2 h?1. Galaxias maculatus increased the OC rate by 31%, from 0.39 to 0.51 mg O2 h?1 g?1, occurring 14 min after food intake. The carrying capacities for industrial cultures of G. maculatus, were estimated using an allometric equation (OC=0.2363 ×W 0.612 ), a water flow rate of 1 m3 h?1 and an input oxygen concentration of 10 mg L?1 at 12 °C. The density culture of whitebait (4 g) can be allowed to reach 8–11 kg m?3; therefore, these stocking densities reduce the risk of hypoxia and mortality, ensuring the appropriate growth and feed conversion rates.  相似文献   

17.
This study examined the effects of acclimation temperature (10, 15, 20, or 25 °C) and an acute exposure to various temperatures on the routine metabolism of juvenile (~11 g) shortnose sturgeon (Acipenser brevirostrum). For the acclimation experiment, the minimum, mean, and maximum routine metabolic rates were established for sturgeon at each temperature. Mean routine metabolic rates for 10, 15, 20, and 25 °C were 134, 277, 313, and 309 mg O2 kg?1 h?1, respectively, with significant differences occurring between 10 and 15, 10 and 20, and 10 and 25 °C. For the acute exposure, similar patterns and significant differences were observed. Temperature quotient (Q 10) values indicate that the greatest effect of temperature occurred between 10 and 15 °C for both the acclimation and acute temperature experiments. In addition, the effect of temperature on the metabolic rate of sturgeon was nearly negligible between 15 and 25 °C. These results suggest that juvenile shortnose sturgeon are sensitive to temperature changes at the lower end of the range, and less sensitive in the mid-to-upper temperature range.  相似文献   

18.
This study examined the pharmacokinetics and bioavailability of oxolinic acid (OA) in black tiger shrimp Penaeus monodon Fabricius, in brackish water (salinity 10 g L?1) at 28–29°C, after intra‐sinus (10 mg kg?1) and oral (50 mg kg?1) administration and also investigated the net changes of OA residues in the shrimp after cooking (boiling, baking and frying). The haemolymph concentrations of OA after intra‐sinus dosing were best described by a two‐compartment open model. The distribution and elimination half‐lives were 0.84 and 17.7 h respectively. The apparent volume of distribution at a steady state and the total body clearance were estimated to be 2061 mL kg?1 and 90.1 mL kg?1 h?1 respectively. The bioavailability of OA after an oral administration was 7.9%. The peak haemolymph concentration, the time to peak haemolymph concentration and the elimination half‐life after oral administration were 4.20 μg mL?1, 4 h and 19.8 h respectively. Oxolinic acid muscle and shell levels increased to a maximum (muscle 1.76 μg g?1 and shell 8.17 μg g?1) at 4 h post administration and then decreased with the elimination half‐life value of 20.2 and 21.9 h respectively. Residual OA in muscle and shell was reduced by 20–30% by each cooking procedure examined.  相似文献   

19.
We determined through morphological and rbcL phylogenetic analyses that a previously unidentified, but introduced species of macroalga, which has been easily cultivated in indoor tanks in Japan, is Agardhiella subulata (Solieriaceae). Additionally, the photosynthetic biology of this alga was examined by inducing photosynthetic activity under a variety of water temperatures and photosynthetic active radiation (PAR) to clarify the optimal conditions needed for its efficient cultivation. Photosynthetic activity was evaluated by using both dissolved oxygen (DO) and pulse amplitude modulated-chlorophyll fluorometric (PAM) techniques, and focused on elucidating temperature and PAR levels that would potentially maximize productivity. The DO method revealed that the net photosynthetic rates at 24 °C quickly increased as PAR increased, and approached a P max of 27.8 mg O2 g ww ?1  min?1 (95 % Bayesian credible interval, BCI 23.8–32.1). The maximum gross photosynthetic rate occurred at 26.7 °C (BCI 24.4–28.3 °C). However, PAM experiments indicated that for the maximum quantum yield, the optimal temperature was 23.7 °C (BCI 22.7–24.6) and the maximum relative electron rates occurred when the water temperature was 31.0 °C (BCI 30.6–31.5). This study suggests that the broad tolerance of maximal photosynthetic activity to temperature (22.7–31.5 °C) is one of the main reasons why this alga can be successfully cultivated year-round.  相似文献   

20.
Effects of eugenol (AQUI‐S®20E, 10% active eugenol) sedation on cool water, yellow perch Perca flavescens (Mitchill), and warm water, Nile tilapia Oreochromis niloticus L. fish metabolic rates were assessed. Both species were exposed to 0, 10, 20 and 30 mg L?1 eugenol using static respirometry. In 17°C water and loading densities of 60, 120 and 240 g L?1, yellow perch controls (0 mg L?1 eugenol) had metabolic rates of 329.6–400.0 mg O2 kg?1 h?1, while yellow perch exposed to 20 and 30 mg L?1 eugenol had significantly reduced metabolic rates of 258.4–325.6 and 189.1–271.0 mg O2 kg?1 h?1 respectively. Nile tilapia exposed to 30 mg L?1 eugenol had a significantly reduced metabolic rate (424.5 ± 42.3 mg O2 kg?1 h?1) relative to the 0 mg L?1 eugenol control (546.6 ± 53.5 mg O2 kg?1 h?1) at a loading density of 120 g L?1 in 22°C water. No significant differences in metabolic rates for Nile tilapia were found at 240 or 360 g L?1 loading densities when exposed to eugenol. Results suggest that eugenol sedation may benefit yellow perch welfare at high densities (e.g. live transport) due to a reduction in metabolic rates, while further research is needed to assess the benefits of eugenol sedation on Nile tilapia at high loading densities.  相似文献   

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