Reyer, R. C.

Rosenthal, Harald

Waller, Uwe

OceanRep

59 RESPIRATION IN MACROBRACHIUM ROSENBERG/I POSTLARV AE AT NORMOXIC AND HYPOXIC LEVELS 1 ** R.C. REYES*, U. WALLER and H. ROSENTI 1/\L • BiologisC'hC' A11sta/1 IIC'lgo/aml. Notkcstra.uc· .i I, 2000 I lt111,/111rg 52. ( 1C'n11011,r "111sti1111 Ji1r Mec•rcs/;1111(!<:. OiistC'mhrookc•n1·1·g 20, 2300 /\'id I. C1'1"111a11_,. ABSTRACT Respiralion pallerns of M11crohrad1i11•11 m.w-nll<'rgii posllarvac (0.16-0. IX g/l'L: 11 = .'iO l'L) wen· dc1er111incd al 75'/'c, oxygen sa1ura1ion levels for 24 and 96 hrs, as well as al decreasing dissolved oxygcn conccn1ra1ion h:\'ds ( :-:�. 75, 65, 45, 35, 25. and \hen raised lo 90%) with each level lasling for 45 minutt·s. Measurcmcnls were conducted within 40-60 days afler meiamorphosis. Those measuremcnls at 75'/c' salllratio11 las1ing 24 hrs showed 1ha1 oxygen consumption rules in darkness were higher than those during the lighled phase: such was also 1he case in an experimenl lasting 96 hrs. which showed a cyclical rcgularily. A decrease in saluration lcvels from X5 lo 65';; "·as accompanied by a slight increase in respiration. As saturation levels further dccreasccl below (15rJ .• rcspirat ion correspondingly decreased. Respiration rates observed at the 90'k· level were lower lhan those in the prc\'ious saturation levels. Growth and survival of Macrohrachiw11 rose11hergii are dependent on the availability of oxygen required to sustain metabolic functions. Fluctuations in saturation levels do occur in nature as well as in intensive cul lure. The high morlalily in pond-reared juveniles (4."i'lt· within lhree days) reported by Green C'I al. ( 1977) was allrihuted to a drop in oxygen concentration to almost 0% during Lhe night (0.5-0.6 ppm 02 was measured early the next day). Good aqaculture practices combined with adequate knowledge in respiration rates at various oxygen saturation levels are required to prevent such massive kills. Previous determinations of postlaraval and juvenile respiration rates (Clifford and Brick, 1983: Nelson and Knight, 1977; Stephenson and Knight, 1980) were conducted only within a specific saturation level, different in each investigation. In the present study, respiration rates of post larvae at various saturation levels and durations were determined. MATERIALS AND METHODS Respiration measurements on Lile post larvae (PL) were conducted wilh the same cnmputer­controlled closed respirometer (fig. I) described previously (Reyes cl al., 1990). Fifty PL 1This paper is based in part 011 the senior author's dissertation al the Facully or Biology or the Univcr�ily or Hamburg. Germany . .I. t1,111a. Trop., 7 ( 1992) 117-124 © Oxford & 1131·1 Publishing C'o. l'vl. Ltd. 118 Reservoir Reservoir 0 2 Wasle water magnot valve Animal chamber Computer Peristaltic pump Pump Oxygen probe Fig. l. Respirometer used in oxygen consumption measurements in post larvae (range of total weight= 7. 95-9. 16 g or 0. 16-0. 18 g/PL) were acclimatized prior to measure­ment to respirometer conditions for 3 hrs at a constant flow of I 00% oxygen- saturated water maintained at 26. I ± O. l 0C. Twenty hours prior to each experiment, the postlarvae were feel with artificial dry feed (Goldfish Tetra Feed) at a ration of I 0% of body wet weight; they were not fed during measurements. Oxygen consumption rates at the 75% oxygen saturation level were measured for 24 and 96 hrs (light:dark cycle at I 2L: 120), with the fonner replicated thrice. In another set of experiments, the postlarval respiration al decreasing oxygen saturation levels from 85 to 25% (at I 0% decrements) were measured for 4.5 minutes/saturation level. After measurements at 25%, the saturation level was raised to 90� and the respiration rates measured. All measurements at various saturation levels were conducted only under illuminated conditions. Light intensity for all experiments was 1.25 µmol/sq. m/sec. RESULTS Detailed representative examples of respiration pattern in M. rosenhergii post larvae at 75% saturation level measured for 24 hrs and at different levels (90-25%)·are shown in Figs. 2 and 3, respectively. Oxygen consumption levels for.24 hrs al 75% saturation were higher during the period o( total darkness than during the preceding illuminated period: oxygen consumption then slightly decreased when the lights were turned on at 0700 hrs (Fig. 2). In experiments wherein the postlarvae were subjected to various saturation levels, respiration was observed to increase slightly as saturation decreased from 85 to 65%. hut respiration decreased correspondingly as saturation was further reduced from 65 to 25%. Upon return 119 2.50 2.00 .2 1.50 c .Q 1.00 "@ ·5. Ill Q) 0.50 0.00 11 15 19 23 3 7 10 Central European Time (hr) Fig. 2. A representative example of a continuous series of 24 hr oxygen consumption determinations in M. rosenhergii postlarvac at 75% oxygen saturation level (total wet weight = 8.36 g, 11 = 50) Central European Time (hr) 10:00 11 :OC 12 :0 13:00 14:00 15:00 16:00 17:00 18:00 100 2.00 80 1.80 � c 60 1.60 � .Q §. c Ill 40 .Q c 1.40 "@ Q) ·5. )( Q) 0 a: 20 1.20 0 1.00 0 3 5 6 7 8 Experimental lime (hr) Fig. 3. A detailed example (replicate 2) showing respiration patterns in M. rosenbergii post larvae (total wet weight= 8.76 g, 11 = 50) at different oxygen saturation levels. Each small square represents an actual measure­ment within the saturation level studied. to a nonnoxic level of 90%, respiration was lower than at all preceding saturation levels (Fig. 3). Figure 4 shows hourly averages of oxygen consumption determinations at 75% satura­tion levels in three replicates, each lasting 24 hrs. In all replicates, respiration levels for the first nine hours of measurement ( 1100-1900 hrs) did not differ significantly (t test, P > 0.05). In replicates 1 and 2, which were measurements on the same postlarvae, oxygen consump­tions throughout the entire period of darkness were significantly higher Lhan in the lighted phase, but in replicate 3 (consisting of a different batch of postlarvae comparatively in the same weight range, 7.95-8.91 g/50 PL, as the previous replicates) respiration progressively decreased from 2200 hrs onwards, and increased after the lights were turned on at 0700 hrs. In a separate experiment, a comparison of the results obtained in three replicates wherein 120 10:00 2.00 1.90 1.60 1.70 E 1.60 0, 1.50 1.40 .Q 1.30 ·5.. 1.20 QJ 1.10 1.00 0 • � [J Central European nme (hr) 16:00 Repl. I Repl. 2 Repl. 3 6 22:00 12 Experimental lime (hr) 4:00 10:00 2.00 1.90 1.60 1.70 1.60 1.50 1.40 1.30 1.20 1.10 1.00 18 24 Fig. 4. Respiration in M. rosenhergii postlarvae (range of total wet weight= 7.95-8.91 g, 11 = 50) at 75% oxygen saturation level .within a 24 hr period. The thick horizontal line at the upper margin indicates the period of darkness, whereas the vertical lines with horizontal bars are the 95% confidence limits for each hourly computed average. the postlarvae were subjected to different oxygen saturation levels showed no significant differences in the values between 85 and 25% (as indicated by overlapping 95% confidence intervals). Only the respiration rates in replicate I at 90% deviated significantly from the other two replicates (Fig. 5). Postlarval respiration detennined in three replicates at different saturation levels is summarized in Fig. 5 and Table 1. Replicates were not significantly different from each other using ANOV A (P > 0.05), also demonstrated by the overlapping 95% confidence limits. Mean respiration rate at 90% is significantly different from the rates measured at 45-85% level. Average oxygen consumption at 25% was significantly different from those measured between 55 and 85%, but not from the rates at 35 and 45% (Table I). 1.60 1.80 1.70 1.70 1.60 1.60 .c 1.50 1.50 0, 0, 1.40 1.40 .Q 1.30 1.30 ·5.. 0 Repl. 1 QJ 1.20 a: + Repl. 2 1.20 1.10 0 Rep!. 3 _ Mean 1.10 1.00 1.00 0 20 40 60 60 100 Oxygen saturation (%) Fig. 5. Mean oxygen consumption rates of M. roscnhcrgii postlarvae (range of total wet weights= 8.65-9.16 g. n = 50) at different oxygen saturation levels. Vertical lines with horizontal bars are the 95% confidence limits of the computed average for each saturation level. The thick curye represents the average of three replicates. -E c 0 � '6.. 12 1 Table I .  Respiration rates of M. mscnhcrgii post larvae at various saturation levels Respiration (mg/g/hr) Saturation (%) rep!. I repl. 2 rcpl. 3 Mean 90 1 .566 1 .206 1 .329 I .367c 85 1 .588 1 .544 1 .514 1 .549" 75 1 .603 1 .643 1 .557 1 .60 I a 65 1 .586 1 .619 1 .616 1 .607. 55 1 .507 1 .539 1.554 1 .533" 45 1 .539 1 .472 1 .502 1 .504•b 35 1 .501 1 .453 1 .494 1 .483"1,c 25 1 .438 1.363 1 .374 1 .3921,c Means with the same superscript are not significantly different from each other at 5% level (two-way ANOVA, DMRT: p < 0.05: cv = 4.51 % ). Di fferences between replicates are not signi fie ant (ANOVA, P > 0.05). A continuous series of oxygen consumption determinations lasting for 96 hrs showed a repetition of the rate increase tendency during darkness, with maximal peak values (between I.SO and 1.70 mg/g/hr) when the l ights were turned off at 1900 hrs (Fig. 6). Thereafter, respiration rates decreased to a comparatively lower range ( 1 .05-1.30 mg/g/hr) during the il luminated period, with the exception of four smaller peaks (rates between 1.30 and 1.50 mg/g/hr), the first at 0800 hrs, the second at 1 600 hrs, the third and fourth at 1400 hrs (at 2 1, 30, 52, and 76 hrs from the start of the experiment, respectively). In comparison, the respiration curves on the second, third and fourth days (in this context, the term 'day' refers to a 24 hr interval) have more similarity to each other in terms of relative increase or decrease with reference to time (slope of the curve within a particular time interval) . The first 24 hr period differed from the successive days, as observed in the sudden respiration decrease 2.00 1 .90 1 .80 1 .70 1 .60 1 .50 1 .40 1 .30 1 .20 1 . 1 0  1 .00 0 Central European Time (hr) 1 6 :00 1 6:00 1 6 :00 1 6:00 6 1 2  1 8  24 30 36 42 48 54 60 66 72 78 Experimental time (hr) 2.00 1 .90 1 .80 1 .70 1 .60 1 .50 1 .40 1 .30 1 .20 1 . 1 0  1 .00 84 90 96 Fig. 6. Respiration in M. roscnhergii postlarvae (total wet weight= 8.91 g. 11 = 50) measured continuously for 96 hrs. Venical lines with horizontal bars are the 95% confidence limits for each hourly average of meas­urements. whereas the four thick horizontal lines represent the dark periods within the time frame. 122 from 1.65 to 1. 15 mg/g/hr between 2 100 and 100 hrs. When the l ights were turned on the rates increased, then decreased after 2 hrs, exhibiting a minor peak which was not repeated in  successive days. With reference to maximal and minimum values, the first and second days are comparatively the same; such values were noted to decrease over the third and fourth days. DISCUSSION After metamorphosis in bracki sh water, natural ly occurring M. rosenhergii postlarvae migrate to fresh water, where they grow to maturity. In their natural habitats, upstream movement may be stimulated by less optimal temperature and salinity conditions associated with changing conditions in seasonal weather (John, 1957). In ponds, movement of post lar­vae is rather restricted and stressful conditions may be detrimental. This has been demonstrated in reported cases of juvenile mortal ities associated with oxygen depiction in ponds (Green et al., 1977; Scott et al., 1988). Data from the present study indicate that postlarval respi ration is oxygen-dependent, in contrast to oxygen-independent aduJ t respira­tion (Reyes et al . ,  1990). Knight ( 1976) suggested that a 60% oxygen saturation level is wel l in excess of the critical level at which the respiration rate becomes oxygen-dependent. Our findings showed that at saturation levels below 65% respiration rates and saturation rates decreased paral lel to each other; such declines became significant at 25% (Table I). During the experiments hypoxia-related mortalities were not observed even at 25%, indicating that the postlarvae can tolerate hypoxic levels within a brief period. Based on the signific;antly lower mean respiration rate upon return to nonnoxia (90%), it appears that the oxygen debt ensuing from hypoxia was not paid back. Ranges of observed values at 75% detennined for 24 and 96 hrs were within 1.0- 1.9 mg/g/hr, wel l  above the adult respiration rates (0.2-0.7 mg/g/hr) (Reyes et al. , 1990). Observed respiration trends (Figs. 6 and 7) not only confirm findings by Nelson et al. ( 1977) that oxygen consumption significantly increases during the dark period, but also suggest that photoperiod-related cyclical fluctuations are characteristic of the postlarval metabolism. Elevated respiration rates in darkness coincide with the nocturnal activity of the postlarvae. Computed mean respiration rates for every 24 hrs were 1.304, 1.387, 1.3 12 and 1.2 10 rng/g/hr for the first, second, third and fourth days, respectively, indicating a s l ight increase 30 20 day 2 10 � 0 c · 10  ·20 30 c .Q 20 ·;; 10 0 · 1 0  ·20 11 15 19 23 3 7 11 15 19 23 3 7 Central European Time (hr) Fig. 7. Percentage deviation from the 24 hr mean respiration rate at 75% oxygen saturation for four consecutive days. The 24 hr averages are 1 .304, 1 .387, 1 . 3 12  and 1 .210  mg./g/hr for days I .  2. 3 and 4, respectively. The thick dark horizontal l ine at the upper margin of each graph represents the dark period of the l ight regime. 1 2.1 in  rates during the second day, after which respi rat ion rates decreased. These averages arc lower than the first ( 1 .46 1 ± 0. 1 93 mg/g/hr) and second ( 1 .6 1 9  ± 0.230 mg/g/hr) replicates of measurements lasting for 24 hrs only. The third replicate (from an ent i rely di fferent set of' individuals, but oJ' the same number and weight range) was also considered as the measurement for the fi rst day of the 96 hr experiment s ince the same condi t ioning as for the foregoing two replicates was met .  The mean 24 hrs respi rat ion rate for the third replicate ( 1 .304 ± 0. 1 32 mg/g/hr) overlapped the lower deviat ion of the other two, but the respi rat ion decreased more rapidly during the night (Fig. 4). Stat ist ical analysis of' the three replicates showed that 24 hr averages were significantly different from each other (/ test and Kol­gomorov-Smirnov test, P < 0.05), but as could be seen in Fig. 4. respi rat ion rates were w i thin the same levels prior to 2000 hrs in all the replicates conducted. Thi s  suggests that act i v i ty during the light phase falls within a narrow rnngc. but d iffers from one /!roup of indi v idu;ils lo another during darkness, even when al the same saturat ion level. Since the postlarvac were not fed during measurements, oxygen consumpt ion rates in the 96 hr measurement also reflected mctabol ism in fast ing individuals. Th is fast ing e !Teel was eviclenl in the comparat ively lower peak rates after 48 hrs; by the 96th hr. the respi rat ion range was approx imately 1 .05- 1 . 1 5 mg/g/hr. This  range is nevertheless not significantly d i fferent from those observed at the 24th, 48th and 72nd hrs. Clifford and B rick ( 1 983) studied substrate metabolism in fast ing juveni les (mean weight = 0.68 g) and obtained weight-normalized oxygen consumpt ion rates o f  1 .450 and 1 .348 mg/g/hr after starvation periods of four and eight days, respect ively. The 7% depression produced by doubling the fasting t ime was, however, found to be stat is t ically ins igni ficant (covariance analysis, P > 0.05). On the basis of high RQ and O:N values, the authors suggested that the juveniles relied more heavily upon carbohydrate reserves for immediate energy requi rements during the f i rst four clays of fasting, but noted a subsequent two-fold increase in l ipid and protein oxidation as the fast ing t ime doubled. They est imated that 0. 1 g juveniles (weight range of post larvae in  the present study) fas ting for four days catabolized 0.9% body protein per clay and pointed out that the h igher weight-specific metabolism in small individuals would prec ipi tate a more rapid  deplet ion of carbohydrate reserves, hastening the t ransi t ion lo increased protein and l ipid catabolism. Weight-spec i fic  oxygen consumpt ion rates wi thin the specified t ime frames and con­d i t ions presented herein provide further bas ic biological informat ion, useful not only in pond culture per se, but also in planning postlarval t ransport to grow-out ponds. On the basis of the mean respi rat ion rates provided, one can make a good est imate of stocking dens i t ies which would m inimize hypoxia-related mortal i t ies. REFERENCES Cli fford, 1-1.C. , Ill, and Brick, R.W. ( 1983). Nutritional physiology of the freshwater shrimp /llt1ff1 1hruchi11111 rosc11hergii (de Man). I .  Substrate metabolism in fasting.juvenile shrimp. Comp. Biochc111. l'hysiol .. 7-tA(3) :  56 1-568. Green. J.P .. Richards. T.L.. and Singh, T. ( 1977). A massive kill of pond-reared Mac'J'<1/m1chi11111 rnsc11hl'l'gii. Aq1wrn/r11rc, 1 1 :  263-272. John. C'.M. ( 1957). Bionomics and I ifc of Macmhrnchi11111 rosr11hc1;i:ii ( de Man). Bull. Cent. Rcs. !11sr .. I S: lJ.1- 1 02. Knight. A.W. ( 1976). Laboratory studies on selected nutritional. physical and chemical factors affecting the growth. survival. respiration and bioenergetics of the giant freshwater prawn (Macmhrad1i11111 r11sc11hcrgiil. Paper 450 I .  Department of Land. Air and Water Resources. Water Sci. and Engr. University of California. Davis. California. 1 24 Nelson, S.G., L i ,  H.W., and Knight, A.W., (1977). Calorie. carbon and nitrogen metabolism of juvenile Mal 'l'o· hrachium rose11hffgii (de Man) (Crustacea, Palaemonidae) w ith regard to trophic position. Comp. lliochcm. Physiol . . SBA: 3 1 9-327. Reyes, R.C., Waller, U., and Rosenthal, H. ( 1 990). Respiration and hchavior of Ma!'mhmd1i11111 mse11hergii at different levels of oxygen saturation. ICES C.M. 1990/F 22, 7 pp. Scott, G., Guthrie Perry, W., Jr., and A vault, J. W., Jr. ( 1988). Polyculture of the giant Malaysian prawn and the golden shiner in Southwestern Lou isiana . .!. World A quarnlt. Soc., 1 9(3): 118-12(1. S tephenson, M.J., and Knight, A.W. ( 1980). The effect of temperature and salinity on oxygen consumption of post larvae of  Macrohrachi11111 rose11bergii (de Man) (Crustacea: Palaemonidae). Co11111. lliochcm. l'hysiol .. 67A: 699. 

Respiration in Macrobrachium Rosenbergii Postlarvae at Normoxic and Hypoxic Levels

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Respiration in Macrobrachium Rosenbergii Postlarvae at Normoxic and Hypoxic Levels

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