[Effects of light intensity on growth, survival, metabolism and related enzyme activities of Sepia pharaonis.] / å ‰ç §å¼ºåº¦å¯¹è™Žæ–‘ä¹Œè´¼ç”Ÿé•¿ã€å­˜æ´»ã€ä»£è°¢åŠç›¸å ³é ¶æ´»æ€§çš„å½±å“.

An experiment with single-factor design was conducted to investigate the effects of light intensity on growth and survival of cuttlefish (Sepia pharaonis). The specific growth rate, survival rate, oxygen consumption rate, ammonia excretion rate, lactic acid content in muscle, respiratory metabolic enzymes (including hexokinase, pyruvate kinase, and lactate dehydrogenase), supero-xide dismutase, and malondialdehyde in liver were measured in five constant light intensity treatments (10, 30, 50, 70, 90 µmol·m-2·s-1). The main results were as follows: The specific growth rate and survival rate remained steady initially and then decreased gradually with the increases of light intensity. There was no significant difference between groups 10 and 30 µmol·m-2·s-1, but they were significantly higher than those of the other groups. Exposed to light intensities of 10 and 30 µmol·m-2·s-1, the specific growth rates were (8.43±0.22)%·d-1 and (8.47±0.17)%·d-1, and the survival rates were (79.2±5.9)% and (80.0±4.9)%, respectively. Oxygen consumption rates and ammonia excretion rates increased first slowly and then sharply, and reached the maximum value when light intensity was 90 µmol·m-2·s-1, which was significantly higher than those of the other groups. Lactic acid content in muscle firstly decreased and then increased, with the minimum value at 30 µmol·m-2·s-1. The acid content of 10 µmol·m-2·s-1 was significantly lower than those of the other groups except 30 and 50 µmol·m-2·s-1. With the increases of light intensity, the activities of HK and PK in gills remained steady initially and then decreased gradually, and reached the highest level when exposed to 10 and 30 µmol·m-2·s-1, which were significantly higher than those of the other groups. LDH activity in muscle had the lowest level at the light intensity of 10 and 30 µmol·m-2·s-1, which was significantly lower than those of the other groups. SOD activity in liver firstly increased and then decreased, and reached the highest level ((104.93±4.17) U·mg-1 pro) when exposed to 70 µmol·m-2·s-1, which was significantly higher than those of the other groups. MDA content in liver first remained steady and then increased gradually, and reached the highest level ((5.06±0.35) nmol·mg-1 pro) when exposed to 90 µmol·m-2·s-1, which was significantly higher than those of the other groups. In conclusion, the optimum light intensities for growth, survival and metabolism of S. pharaonis were 10 and 30 µmol·m-2·s-1, beyond which S. pharaonis would be under stress. Therefore, sunproof measures should be taken to keep weak light condition in culture practice.

[Effects of light intensity and photoperiod on the embryonic development of Sepia pharaonis.] / å ‰ç §å¼ºåº¦ä¸Žå ‰å‘¨æœŸå¯¹è™Žæ–‘ä¹Œè´¼èƒšèƒŽå‘è‚²çš„å½±å“.

We investigated the effects of lumination on hatching of fertilized eggs of Sepia pharaonis, to reveal the best light conditions for its embryonic development. A single-factor experiment was carried out to examine the effects of different light intensities (10, 30, 50, 70, 90 µmol·m-2·s-1) and different photoperiod L:D (24 h:0 h, 18 h:6 h, 12 h:12 h, 6 h:18 h, 0 h:24 h) on the embryonic development. The results showed that the effects of light intensity on the hatching rate, fractured yolk sac rate, incubation period, mass of newly hatched larvae and mantle length was significant. There was no significant effect on hatching period and survival rate after hatching 7 days. With the increases of light intensity, the hatching rate, incubation period, mass of newly hatched larvae and mantle length first increased and then decreased, while the fractured yolk sac rate gradually increased. The optimum light intensity was 30 µmol·m-2·s-1. Exposed to this light intensity, the hatching rate, fractured yolk sac rate, incubation period, hatching period, mass of newly hatched larvae, mantle length and survival rate after hatching 7 days were (90.0±4.1)%, (7.3±1.5)%, (25.50±0.35) d, (8.10±0.89) d, (0.213±0.011) g, (1.013±0.022) cm, (97.1±4.0)%, respectively. The effects of photoperiod on the hatching rate, incubation period, hatching period were significant, but there was no significant effect on fractured yolk sac rate, mass of newly hatched larvae, mantle length and survival rate after hatching 7 days. With the increases of illumination time, the hatching rate and hatching period first increased and then decreased. The optimum photoperiod was L:D (12 h:12 h). When exposed to this photoperiod environment, the hatching rate, fractured yolk sac rate, incubation period, hatching period, mass of newly hatched larvae, mantle length and survival rate after hatching 7 days were (88.7±1.8)%, (8.7±1.8)%, (25.00±0.50) d, (7.00±3.20) d, (0.209±0.005) g, (0.998±0.026) cm, (96.8±7.1)%, respectively. In conclusion, embryo hatchability of S. pharaonis preferred to low light intensity (30 µmol·m-2·s-1) and normal photoperiod L:D (12 h:12 h). In production practice, sunproof measures should be taken to keep the eggs in weak light condition.

[Oxygen consumption rate of Sepia pharaonis embryos.] / 虎斑乌贼的胚胎耗氧率.

This research was conducted to unravel the variation of oxygen consumption rate during different developmental stages and the effects of different ecological factors on embryonic oxygen consumption rate of Sepia pharaonis. The oxygen consumption rates were measured at twelve deve-lopmental stages by the sealed volumetric flasks, and four embryonic developmental periods (oosperm, gastrula, the formation of organization, endoskeleton) were selected under various ecological conditions, such as salinity (21, 24, 27, 30, 33), water temperature (18, 21, 24, 27, 30 ℃) and pH (7.0, 7.5, 8.0, 8.5, 9.0). The results showed that the oxygen consumption rate rose along with the developmental progress, and distinctly differed from each other. The oxygen consumption rate was 0.082 mg·(100 eggs)-1·h-1 during oosperm period, and rose to 0.279 mg·(100 eggs)-1·h-1 during gastrula period, which was significantly higher than that of blastula period. Finally, the oxygen consumption rate rose to 1.367 mg·(100 eggs)-1·h-1 during hatching period. The salinity showed a significant effect on oxygen consumption rate during the formation of organization and endoskeleton formation stage (P<0.05), but no significant effect during oosperm and gastrula periods (P>0.05). The oxygen consumption rates of four studied embryonic stages all rose and then declined along with the increase of salinity, and reached the highest values [0.082, 0.200, 0.768 and 1.301 mg·(100 eggs)-1·h-1, respectively] at salinity 30. The water temperature had a significant effect on the embryo oxygen consumption rates of gastrula, and the formation of organization and endoskeleton formation stage (P<0.05), with the exception of oosperm (P>0.05). The oxygen consumption rates of four studied embryonic stages all rose and then declined along with the increase of temperature, and reached the highest values at 27 ℃ [0.082, 0.286, 0.806 and 1.338 mg·(100 eggs)-1·h-1, respectively]. The pH had no significant effect on the oxygen consumption rates of four embryonic stages (P>0.05). The oxygen consumption rates of four studied embryonic stages all rose and then declined along with the increase of pH. The oxygen consumption rates of gastrula, the formation of organization, endoskeleton reached the according highest values [0.281, 0.799 and 1.130 mg·(100 eggs)-1·h-1] at pH 8.5, but that during oosperm period occurred at pH 8.0 [0.116 mg·(100 eggs)-1·h-1].

[Effects of starvation and re-feeding on survival rate, growth and digestive enzyme activities of juvenile Sepia pharaonis.] / é¥¥é¥¿å’Œå†æŠ•å–‚å¯¹è™Žæ–‘ä¹Œè´¼å¹¼ä½“å­˜æ´»ã€ç”Ÿé•¿å’Œæ¶ˆåŒ–é ¶æ´»åŠ›çš„å½±å“.

To investigate the effects of starvation and re-feeding on survival rate, behavior, growth and digestive enzyme activities of juvenile Sepia pharaonis, the manipulative laboratory experiments were conducted with 0-6 days of starvation and 15 days of re-feeding to reveal the mechanism of compensatory growth. The results showed that starvation exerted a significant negative effect on the survival rate, growth, hepatosomatic index and digestive enzyme activities (P<0.05). The survival rate and digestive enzyme activities declined during the whole starvation process. After 3 days, the survival rate began to decline significantly, the decrease rate of body mass increased obviously and juveniles experienced some abnormal behaviors, such as inkjet, fighting and so on. The effects of starvation on digestive enzyme activities of juveniles were significant, and the digestive enzyme activities declined and then rose during the whole starvation process. The lowest amylase activity occurred after 4 days of starvation (0.07±0.02 U·mg-1·prot-1). The lowest lipase activity occurred after 2 days of starvation (18.47±2.07 U·g-1·prot-1), and the highest after 6 days (57.60±3.98 U·g-1·prot-1). The lowest pepsin and trypsin activities occurred after 5 days (1.98±0.59 U·mg-1·prot-1) and 4 days (186.68±20.72 U·mg-1·prot-1) of starvation, respectively. The effects of re-feeding on survival rate, growth, hepatosomatic index and digestive enzyme activities of juveniles were significant. The survival rate, specific growth rate, hepatosomatic index and feeding rate were negatively correlated with hunger processing duration. The survival rate, specific growth rate and hepatosomatic index showed no significant difference between 1 day starvation group and 2 days starvation group (P>0.05). The survival rate, specific growth rate and hepatosomatic index of 3 days to 6 days starvation groups were significantly lower than the control group. The feeding rates of 1 day and 2 days starvation groups were obviously higher than that of the control group. The feeding rate of 6 days starvation group was significantly lower than that of the control group. The amylase and lipase activities were not significantly different among different starvation treatments, whereas the pepsin and trypsin activities were significantly different, with the highest value in the control group (pepsin 7.06±0.64 U·mg-1·prot-1, trypsin 914.67±26.54 U·mg-1·prot-1) and the lo-west value in the group with 6 days of starvation (pepsin 3.21±0.57 U·mg-1·prot-1, trypsin 660.04±37.92 U·mg-1·prot-1). Six days of starvation would be the point of no-return for the juveniles, without any compensatory effect after starvation and re-feeding.

[Effects of temperature on the embryonic development and larval growth of Sepia lycidas].

A single-factor experiment was conducted to study the effects of different temperature (15, 18, 21, 24, 27, 30, and 33 degrees C) on the embryonic development and larval growth of Sepia lycidas, aimed to search for the optimum temperature for the development and growth of S. lycidas. The results showed that temperature had significant effects on the embryonic development and larval growth of S. lycidas (P < 0.05). The suitable temperature for hatching ranged from 21 degrees C to 30 degrees C, and the optimum temperature was 24 degrees C. At the optimum temperature, the hatching rate was (93.3 +/- 2.9)%, incubation period was (24.33 +/- 0.58) d, hatching period was (6.00 +/- 1.00) d, completely absorked rate of yolk sac was (96.4 +/- 3.1)%, and newly hatched larvae mass was (0.258 +/- 0.007) g. The effective accumulated temperature model was N = 284.42/(T-12.57). The suitable temperature for the larval survival and growth ranged from 21 degrees C to 30 degrees C, and the optimum temperature was from 24 degrees C to 27 degrees C. At the optimum temperature, the survival rate ranged from 70.0% to 73.3%, and the specific growth rate was from 2.4% to 3.8%.