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Effect of prey density on feeding rates during larval rearing of Palaemon serratus Pennant (Crustacea: Palaemonidae)
31
Aquaculture, 50 (1985) 31-38 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands
EFFECT OF PREY DENSITY ON FEEDING RATES DURING LARVAL REARING OF PALAEMON SERRATUS PENNANT (CRUSTACEA: PALAEMONIDAE)
M. YUFERA
and A. RODRIGUEZ
Instituto de Investigaciones Cbdiz (Spain)
Pesqueras
de
Cidiz
(C.S.I.C.),
Puerto
Pesquero
s/n,
11006
(Accepted 20 August 1985)
ABSTRACT Yiifera, M. and Rodriguez, A., 1985. Effect of prey density on feed rates during larval rearing of Palaemon serratus Pennant (Crustacea: Palaemonidae). Aquaculture, 50: 31-38.
Ingestion rates of Artemia nauplii by Palaemon serratus larvae at different food levels and at two temperatures were determined. Results show higher food consumption at 25” than at 20°C. Ingestion rate increases with increasing food density within the range tested (l-20 naupliimmll’) for all larval stages. Despite a plateau found between zoea III and zoea V-VI, ingestion increased about 1.8-2.8 times from zoea I to zoea VII-IX, depending on temperature and food density. The gross growth efficiency for the total larval development in cultures with a mean food density of 5 nauplii*mll’ was similar (2 25%) at 20” and 25°C.
INTRODUCTION
Palaemon serratus Pennant is a caridean prawn common in coastal regions of Europe and North Africa (Zariquiey, 1968). Recent studies have shown the suitability of this species for extensive culture in the salt-marsh area of Cidiz (S.W. Spain). In this region the larvae can be found from January to June, and the environmental conditions in the salt ponds allow sexually mature animals to be obtained, with a marketable size (7-- 9 cm) and good survival, in 8- 10 months (Rodriguez, 1981; Rodriguez, in prep.). Artemia nauplii are primarily used as food source for rearing the larvae (Reeve, 1969; Wickins, 1972; San Feliii et al., 1976),mainly at densities of 5-10 nauplii. ml- ’ . These food densities are extrapolated from consumption observed in rearing tanks, and from survival obtained at metamorphosis. As with other crustaceans, there is little information concerning the influence of food density on ingestion rates, although some works on this subject have been published in recent years (Gopalakrishnan, 1976; Emmerson, 1980, 1984; YGfera et al., 1984). This information is needed to develop an optimal feeding regime. 0044-8486/85/$03.30
0 1985 Elsevier Science Publishers B.V.
32
The present work investigated the ingestion rates of Artemia nauplii in relation to food density throughout the larval development of P. serratus, at 20 and 25°C. These temperatures are the extreme values which can be maintained in large tanks in our regions without additional costs. From these data, feeding rates (expressed as % body weight) and gross growth efficiencies were estimated, while an attempt was made to obtain further knowledge of the food requirements of this prawn during larval development. MATERIALS
AND METHODS
The larvae were obtained from gravid females collected in the intertidal zone of the Cidiz salt marshes, and maintained in the laboratory at 20°C. Different zoea groups which hatched from February to June were held in 3-1 flasks containing filtered sea water, at 36°/00 salinity, 20” or 25”C, and under permanent illumination. Sea water was renewed every day. Freshly hatched Artemia nauplii (from cysts harvested in Cadiz salt ponds) at a mean food concentration of 5 nauplii. ml-’ (declining from 13 to 2 nauplii-ml-’ approximately every day) were supplied from the first day. P. serratus presents nine larval stages before metamorphosis (Fincham, 1983), though experience shows that the later stages are often ill-defined. Dry weight of the larvae was determined using samples of SO-100 individuals washed with distilled water and dried at 90°C until constant weight was achieved. Dry weight of Artemia was determined as the average between fresh and 24-h-old nauplii (four replicated samples) using an autobalance with 0.1 pg precision. Ash content of the Artemia nauplii was determined from samples incinerated for 4 h at 550°C. Larval length, from rostrum to tail-fan, was determined from 30 individuals at each larval stage. The ingestion experiments were carried out in flasks with 200 ml of gently aerated filtered sea water (36%, salinity) from Cidiz Bay. Each flask contained 20 larvae removed from the stock culture flasks. Attempts were to take all individuals from only one larval stage, but it was not possible to do this after zoea IV due to the gradual loss of synchronism in the development in these later stages. Thus determinations were made for zoea I, zoea II, zoea III, zoea IV, zoea V-VI and zoea VII-IX. For each of these larval groups, several flasks with differeent initial food densities (from 2 to 20 nauplii - ml- ’ approximately) were tested, and the decrease in food density over 24 h was determined. Two series of experiments, at 20” and 25”C, were performed. The ingestion rates (I) were calculated using the equation:
where C, and Ct are the initial and final food concentrations respectively, P is the number of larvae per ml, and K is the rate of food decrease, calculated as the slope of the regression fitted to In of food concentration against time. The mean between the initial and final number of larvae was used
33
when mortality occurred during the experiment. No correction due to mortality of Artemiu was needed because its density in larval-free controls remained constant in all experiments. The ingestion rate was plotted against the mean food concentration (d C, X C,). The results for each larval stage were fitted to a power regression in order to obtain a more precise value of ingestion rate for a given food concentration. 804 ZOEA
I
ZOEA
II
60-
ZOEA
V-VI
ZOEA
VII-IX
60-
5
10
15 FOOD
Fig.
1. Ingestion
bolds,
DENSITY
rate of Artemia
II) and 25°C
(white
5
20
symbols,
nauplii I).
10
ml-‘1 by Palaemon serratus
15
20
(nauplil
larvae at 20°C
(black
SYm.
34
The gross growth efficiencies (% of food biomass converted in larval growth) were estimated from larvae reared at a mean food density of 5 nauplii*ml-’ (range: 13-Z nauplii=mI-‘). RESULTS
Ingestion rate as a function of food density for each larval stage is shown in Fig. 1. Results show an increase of ingestion with increasing food density for all larval stages. We have not found a satiety level within the range tested (Z-20 nauplii. ml-’ initial food density), but data are well fitted to a power function, and the ingestion rate tends to be constant at higher food densities. The pattern of ingestion rate against food density is similar at both temperatures tested, although values at 20” are only about 60-80% of those obtained from 25°C. The daily consumption (Table 1) was estimated from the ingestion values obtained in the regression lines for food densities of 1, 5, 10 and 15 nauplii*ml-‘, and was converted to dry mass using the values of 2.57 and 2.49 pg*nauplius-’ at 20” and 25% respectively. The ash content was taken as 7.32%. From first larval stage to zoea VII--IX ingestion increased about 1.8--2.8fold (depending on temperature and food density), although a plateau was found between zoea III and zoea IV at 2O”C, and between zoea II and zoea V-VI at 25°C. For further comparison we have considered the value of 0.0237 J*pg-’ ash-free dry weight as the energy content of Artemia nauplii (average of data reported by Benijts et al., 1976; Schauer et al., 1980; and Emmerson, 1984). Thus the daily energy uptake for P. serrutus ranged from 0.79-1.62 J-larva-’ in zoea 1 to 1.983.38 in the later stages at 2O”C, and between 0.92-2.57 J*larvd’ in zoea I TABLE1 Ingestionratesof Palaemon semtus
larvae feedingon Artemia
Larval
Average Ingestionrates
stage
&Y weight
nawlii
(%body weight*d-')
(naupIii*Iarva~'*d~') (~g*larva“*d~')
(Pcrg) Fooddensity (naupIii*mf')
1
6
10
15
1
Temperature: 20°C I 95 II 115 III 160 IV 205 V-VI 276 VII-IX 380
14 12 20 21 26 35
22 26 34 32 44 48
26 37 42 39 56 56
29 45 48 43 63 60
36 31 51 54 61 90
Temperature: 25'C I 95 II 120 III 155 IV 194 V-VI 298 VII-IX 642
17 22 24 35 24 48
31 50 48 63 48 69
41 56 65 64 64 80
47 60 78 71 76 87
42 55 60 87 60 120
5
10
15
1
5
10
15
5'7 67 87 82 113 123
69 95 108 100 141 141
74 116 123 111 162 154
38 27 32 26 24 24
60 58 54 40 41 32
72 83 66 49 51 37
78 101 77 54 59 41
77 125 120 132 120 172
102 137 162 169 169 199
117 149 194 177 189 217
44 46 39 45 20 22
81 104 77 68 60 32
107 114 104 82 53 37
123 124 125 91 63 40
35
and 2.63-4.78 in zoea VII-IX at 25°C (values for 1 and 15 nauplii.ml-’ food density). Table 2 shows the gross growth efficiencies estimated from hatching to each larval stage for larvae reared with a mean food density 5 nauplii*ml-‘. The duration of larval development, and changes in length and weight during development in Fig. 2. At 20°C the first postlarvae appeared at the 20th day post-hatch, attaining a dry weight of 540 pg by the end of larval development. At this stage, gross growth efficiency was calculated to be 25.0%. At TABLE 2 Gross growth efficiencies estimated for Palaemon
larvae
serratus
Increase of larval weight (pg)
Estimated dry matter ingested from hatching (pg)
Gross growth efficiency (%)
Temperature: 20°C II 3 III 6 IV 9 V-VI 13 VII- IX 17 VIII-PL 20
25 53 120 190 295 445
171 372 633 961 1413 1782
14.6 14.2 19.0 19.8 20.9 25.0
Temperature: 25°C II 2 III 4 IV 6 V-VI 8 VII-IX 10 VIII--PL 16
35 51 109 213 277 551
155 405 643 907 1145 2174
22.6 12.6 17.0 23.5 24.2 25.3
Final stage
Days from hatching
_
25”
-0.8
++
0
*’ -
l
: -0.4
* 0
3
0 0
_ 4
0 n’“-
z
>
M,vlll VIP
‘X
PL --0.2
g
O,“E.r----
L,j,,,,,,,,,,,,,,,I
10
16
DAYS
Fig. 2. Larval development: length t SD (black symbols) and weight (white symbols) of serratus larvae reared at 20” and 25°C.
Palaemon
36
25”C, the first metamorphosis occurred at the 16th day post-hatch. The larvae obtained a final weight of 650 1.18and had a gross growth efficiency of 25.5%. DISCUSSION
The success of a diet for larval rearing of fish and crustaceans is dependent on other factors besides nutrition~ quality. Catch efficiency, which is related to feeding behavior and food level, is of primary importance. The present study demonstrates increasing ingestion rates with increasing food density. This response has been reported for the larvae of several crustacean species (Gopalakrishnan, 1976; San, Feliti et al., 1976; Emmerson, 1984; Ytifera et al., 1984). As Boehlert and Yoklavich (1984) pointed out, this pattern suggests a feeding strategy based on the m~~ization of ingestion at higher prey densities, and may be related to random high patchers of plankters in natural habitats. Data reported for Macrobruchium larvae (Moller, 1978) indicate that the principal form of food capture for this species depends upon chance encounters with food sources. This fact has a repercussion on culture feeding dynamics, because despite agitation, Arteemia nauplii and larvae then to concentrate by phototaxis in certain areas of the rearing tank. Therefore, food density becomes greater than anticipated, involving a more rapid food consumption. Considering the ingestion rates obtained in this work, at a stocking density of 100 larvae-ml-‘, Artemia nauplii can be exhausted before 24 h if supplied at densities below 2-3 nauplii* ml-’ during zoea I, and below 4-6 nauplii*ml-’ in zoea VII-IX. Starvation for several hours does not presuppose massive mortality, but poor growth is achieved when food is scarce (Reeve, 1969). San Feliu et al. (1976), working on larval rearing of P. serrutus, found a similar pattern of ingestion in relation to prey density (2-10 nauplii*ml-*) and larval stage (zoea I--zoea V), but a more precise comparison with their results was not possible because the experiments conditions and nauplii biomass were not given. According to Reeve (169) the larvae of this species ingest about 25-35 pg*larvdl-d-’ on the first day, and 70-80~g~larva~1~d-1 at 20 days post-hatch, when the first postlarvae appeared (culture conditions were 22”C, 32.5°/00 salinity, 100 1arvae.I’, and 5-10 nauplii*ml-’ of food density). The gross growth efficiency obtained in this period (~57%) was very much higher than those estimated in the present study. We have not a clear explanation for this, but differences in genetic characteristics and/or differences in the yolk reserves between eggs developed in cold water and those developed in temperatre water may be involved, besides the variations due to experimental conditions. The gross growth efficiencies estimated for other decapod species during larval development range between 15% and 30%, although only 3.2% was reported for Curcinus maenas (Dawirs, 1983; Sastry, 1983; Anger and Dietrich, 1984; Yufera and Rodriguez, in press). The increase of temperature from 20” to 25°C results in an acceleration
37
of larval development in Paluemon, as well as increased ingestion. However, the gross growth efficiency is similar at both temperatures tested. These temperatures are within the optimal range for larval growth of this species (Yagi and Ceccaldi, 1984), and variations within this range have probably little influence on growth efficiency. The present results show that Pcdaemon larvae ingest quickly the food supplied in culture. The prey density declines exponentially and can be scarce in several hours. The effort of obtaining food is considerably greater below a certain food level, involving an important energetic cost. However, an excessive initial flood density to prolong the duration of nauplii in the rearing tanks involves problems of water quality and loss of nutritive value in the old nauplii. Thus, a frequent replenishment of nauplii to maintain a moderate food density, or lower stocking density of larvae is recommended. Daily consumption is higher at 25”C, but the larval development, and therefore the dependence on live food, is shorter. The cost in Artemia biomass during this period is similar (Z 2000 pg) at both temperatures: this is about four times the dry weight attained at the end of larval development. ACKNOWLEDGEMENTS
We thank two anonymous proved the manuscript.
reviewers for constructive
comments
which im-
REFERENCES K. and Ditrich, A., 1984. Feeding rates and gross growth efficiencies in Hyas L. larvae (Decapoda: Majidae) reared in the laboratory. J. Exp. Mar. Biol. Ecol., 77: 169-181. Benijts, F., Van Voorden, E. and Sorgeloos, P., 1976. Changes in the biochemical composition of the early larval stages of the brine shrimp, Artemia salina L. In: G. Persoone and E. Jaspers (Editors), Proc. 10th Eur. Symp. Mar. Universa Press, Wetteren, Belgium, pp. l-9. Boehlert, G.W. and Yoklavich, M.M., 1984. Carbon assimilation as a function of ingestion rate in larval Pacific herring, Clupea harengus pallasi Valenciennes. J. Exp. Mar. Biol. Ecol., 79: 251-262. Dawirs, R.R., 1983. Respiration, energy balance and development during growth and starvation of Carcinus maenas L. larvae (Decapoda: Portunidae). J. Exp. Mar. Biol. Ecol., 69: 105-128. Emmerson, W.D., 1980. Ingestion, growth and development of Penaeus indicus larvae as a function of Thalassiosira weissflogii cell concentration. Mar. Biol., 58: 65-73. Emmerson, W.D., 1984. Predation and energetics of Penaeus indicus (Decapoda: Penaeidae) larvae feeding on Brachionus plicatilis and Artemia nauplii. Aquaculture, 38: 201-209. of British prawns and shrimps (Crustacea: Fincham, A.A., 1983. Larval development Decapoda: Natantia). 4. Palaemon (Palaemon) serratus (Pennant, 1777) and functional morphology of swimming. Bull. Br. Mus. Nat. Hist. (Zool.), 44(2): 125-161. Gopalakrishnan, K., 1976. Larval rearing of red shrimp, Penaeus marginatus (Crustacea). Aquaculture, 9: 145-154.
Anger,
amneus
38 Moller, T.H., 1978. Feeding behaviour of larvae and postlarvae of Macrobrachium rosenbergii (de Man) (Crustacea: Palaemonidae). J, Exp. Mar. Biol. Ecol., 35: 251-258. Reeve, M.R., 1969. Growth, metamorphosis and energy conversion in the larvae of the prawn, Palaemon serratus. J, Mar. Biol. Assoc. U.K., 49: 77-96. Rodriguez, A., 1981. Growth and sexual maturation of Penaeus kerathurus (Forsklll, 1775) and Palaemon serratus (Pennant) in salt ponds. Aquaculture, 24: 257-266. San Feliti, J.M. Mufioz, F., Amat, F., Ramos, J., Peiia, J. and Sanz, A., 1976. Cultivo experimental de larvas de crustbeos y peees en tanques. Inf. T&n. Inst. Inv. Pesq., 36,47 pp. Sastry, A.N., 1983. Pelagic larval ecology and development. In: F.J. Vernberg and W.B. Vernberg (Editors), The Biology of Crustacea. Vol. 7. Behavior and Ecology. Academic Press, New York, pp. 213-282. Schauer, P.A., Johns, D.M., Qlney, C.E. and Simpson, K.L., 1980. International study on Artemia. IX. Lipid level, energy content and fatty acids composition of the cysts and newly hatched nauplii from five geographical strains of Artemia. In G. Persoone, P. Sorgeloos, 0. Roels and E. Japsers (Editors). The Brine Shrimp Artemia. Vol. 3. Ecology, Culturing, Use in Aquaculture. Universa Press, Wetteren, Belgium, pp. 394405. Wickins, J.F., 1972. The food value of brine shrimp Artemia L., to larvae of the prawn, Palaemon serratus Pennant. J. Exp. Mar. Biol. Ecol., 10: 151-170. Yagi, II. and Ceccaldi, H.J., 1984. Influence combinee des facteurs temperature et salinit& sur la metamorphose et la croissance larvaire de la crevette rose Paiaemon serratus (Pennant) (Crustacea, Decapoda, Palaemonidae). Aquaculture, 37: 73-85. Ytifera, M. and Rodriguez, A., in press. Tasas de alimentacibn y crecimiento de Palaemonetes uarians (Crustacea: Palaemonidae) durante el desarrollo larvario. Inv. Pesq. Yufera, M., Rodriguez, A. and Lubi&n, L.M., 1984. Zooplankton ingestion and feeding behavior of Penaeus kerathurus larvae reared in the laboratory. Aquaculture, 42: 217-224. Zariquiey, R., 1968. Crustaceos decapodos ibericos. Inv. Pesq., 32: I-510.
Aquaculture, 50 (1985) 31-38 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands
EFFECT OF PREY DENSITY ON FEEDING RATES DURING LARVAL REARING OF PALAEMON SERRATUS PENNANT (CRUSTACEA: PALAEMONIDAE)
M. YUFERA
and A. RODRIGUEZ
Instituto de Investigaciones Cbdiz (Spain)
Pesqueras
de
Cidiz
(C.S.I.C.),
Puerto
Pesquero
s/n,
11006
(Accepted 20 August 1985)
ABSTRACT Yiifera, M. and Rodriguez, A., 1985. Effect of prey density on feed rates during larval rearing of Palaemon serratus Pennant (Crustacea: Palaemonidae). Aquaculture, 50: 31-38.
Ingestion rates of Artemia nauplii by Palaemon serratus larvae at different food levels and at two temperatures were determined. Results show higher food consumption at 25” than at 20°C. Ingestion rate increases with increasing food density within the range tested (l-20 naupliimmll’) for all larval stages. Despite a plateau found between zoea III and zoea V-VI, ingestion increased about 1.8-2.8 times from zoea I to zoea VII-IX, depending on temperature and food density. The gross growth efficiency for the total larval development in cultures with a mean food density of 5 nauplii*mll’ was similar (2 25%) at 20” and 25°C.
INTRODUCTION
Palaemon serratus Pennant is a caridean prawn common in coastal regions of Europe and North Africa (Zariquiey, 1968). Recent studies have shown the suitability of this species for extensive culture in the salt-marsh area of Cidiz (S.W. Spain). In this region the larvae can be found from January to June, and the environmental conditions in the salt ponds allow sexually mature animals to be obtained, with a marketable size (7-- 9 cm) and good survival, in 8- 10 months (Rodriguez, 1981; Rodriguez, in prep.). Artemia nauplii are primarily used as food source for rearing the larvae (Reeve, 1969; Wickins, 1972; San Feliii et al., 1976),mainly at densities of 5-10 nauplii. ml- ’ . These food densities are extrapolated from consumption observed in rearing tanks, and from survival obtained at metamorphosis. As with other crustaceans, there is little information concerning the influence of food density on ingestion rates, although some works on this subject have been published in recent years (Gopalakrishnan, 1976; Emmerson, 1980, 1984; YGfera et al., 1984). This information is needed to develop an optimal feeding regime. 0044-8486/85/$03.30
0 1985 Elsevier Science Publishers B.V.
32
The present work investigated the ingestion rates of Artemia nauplii in relation to food density throughout the larval development of P. serratus, at 20 and 25°C. These temperatures are the extreme values which can be maintained in large tanks in our regions without additional costs. From these data, feeding rates (expressed as % body weight) and gross growth efficiencies were estimated, while an attempt was made to obtain further knowledge of the food requirements of this prawn during larval development. MATERIALS
AND METHODS
The larvae were obtained from gravid females collected in the intertidal zone of the Cidiz salt marshes, and maintained in the laboratory at 20°C. Different zoea groups which hatched from February to June were held in 3-1 flasks containing filtered sea water, at 36°/00 salinity, 20” or 25”C, and under permanent illumination. Sea water was renewed every day. Freshly hatched Artemia nauplii (from cysts harvested in Cadiz salt ponds) at a mean food concentration of 5 nauplii. ml-’ (declining from 13 to 2 nauplii-ml-’ approximately every day) were supplied from the first day. P. serratus presents nine larval stages before metamorphosis (Fincham, 1983), though experience shows that the later stages are often ill-defined. Dry weight of the larvae was determined using samples of SO-100 individuals washed with distilled water and dried at 90°C until constant weight was achieved. Dry weight of Artemia was determined as the average between fresh and 24-h-old nauplii (four replicated samples) using an autobalance with 0.1 pg precision. Ash content of the Artemia nauplii was determined from samples incinerated for 4 h at 550°C. Larval length, from rostrum to tail-fan, was determined from 30 individuals at each larval stage. The ingestion experiments were carried out in flasks with 200 ml of gently aerated filtered sea water (36%, salinity) from Cidiz Bay. Each flask contained 20 larvae removed from the stock culture flasks. Attempts were to take all individuals from only one larval stage, but it was not possible to do this after zoea IV due to the gradual loss of synchronism in the development in these later stages. Thus determinations were made for zoea I, zoea II, zoea III, zoea IV, zoea V-VI and zoea VII-IX. For each of these larval groups, several flasks with differeent initial food densities (from 2 to 20 nauplii - ml- ’ approximately) were tested, and the decrease in food density over 24 h was determined. Two series of experiments, at 20” and 25”C, were performed. The ingestion rates (I) were calculated using the equation:
where C, and Ct are the initial and final food concentrations respectively, P is the number of larvae per ml, and K is the rate of food decrease, calculated as the slope of the regression fitted to In of food concentration against time. The mean between the initial and final number of larvae was used
33
when mortality occurred during the experiment. No correction due to mortality of Artemiu was needed because its density in larval-free controls remained constant in all experiments. The ingestion rate was plotted against the mean food concentration (d C, X C,). The results for each larval stage were fitted to a power regression in order to obtain a more precise value of ingestion rate for a given food concentration. 804 ZOEA
I
ZOEA
II
60-
ZOEA
V-VI
ZOEA
VII-IX
60-
5
10
15 FOOD
Fig.
1. Ingestion
bolds,
DENSITY
rate of Artemia
II) and 25°C
(white
5
20
symbols,
nauplii I).
10
ml-‘1 by Palaemon serratus
15
20
(nauplil
larvae at 20°C
(black
SYm.
34
The gross growth efficiencies (% of food biomass converted in larval growth) were estimated from larvae reared at a mean food density of 5 nauplii*ml-’ (range: 13-Z nauplii=mI-‘). RESULTS
Ingestion rate as a function of food density for each larval stage is shown in Fig. 1. Results show an increase of ingestion with increasing food density for all larval stages. We have not found a satiety level within the range tested (Z-20 nauplii. ml-’ initial food density), but data are well fitted to a power function, and the ingestion rate tends to be constant at higher food densities. The pattern of ingestion rate against food density is similar at both temperatures tested, although values at 20” are only about 60-80% of those obtained from 25°C. The daily consumption (Table 1) was estimated from the ingestion values obtained in the regression lines for food densities of 1, 5, 10 and 15 nauplii*ml-‘, and was converted to dry mass using the values of 2.57 and 2.49 pg*nauplius-’ at 20” and 25% respectively. The ash content was taken as 7.32%. From first larval stage to zoea VII--IX ingestion increased about 1.8--2.8fold (depending on temperature and food density), although a plateau was found between zoea III and zoea IV at 2O”C, and between zoea II and zoea V-VI at 25°C. For further comparison we have considered the value of 0.0237 J*pg-’ ash-free dry weight as the energy content of Artemia nauplii (average of data reported by Benijts et al., 1976; Schauer et al., 1980; and Emmerson, 1984). Thus the daily energy uptake for P. serrutus ranged from 0.79-1.62 J-larva-’ in zoea 1 to 1.983.38 in the later stages at 2O”C, and between 0.92-2.57 J*larvd’ in zoea I TABLE1 Ingestionratesof Palaemon semtus
larvae feedingon Artemia
Larval
Average Ingestionrates
stage
&Y weight
nawlii
(%body weight*d-')
(naupIii*Iarva~'*d~') (~g*larva“*d~')
(Pcrg) Fooddensity (naupIii*mf')
1
6
10
15
1
Temperature: 20°C I 95 II 115 III 160 IV 205 V-VI 276 VII-IX 380
14 12 20 21 26 35
22 26 34 32 44 48
26 37 42 39 56 56
29 45 48 43 63 60
36 31 51 54 61 90
Temperature: 25'C I 95 II 120 III 155 IV 194 V-VI 298 VII-IX 642
17 22 24 35 24 48
31 50 48 63 48 69
41 56 65 64 64 80
47 60 78 71 76 87
42 55 60 87 60 120
5
10
15
1
5
10
15
5'7 67 87 82 113 123
69 95 108 100 141 141
74 116 123 111 162 154
38 27 32 26 24 24
60 58 54 40 41 32
72 83 66 49 51 37
78 101 77 54 59 41
77 125 120 132 120 172
102 137 162 169 169 199
117 149 194 177 189 217
44 46 39 45 20 22
81 104 77 68 60 32
107 114 104 82 53 37
123 124 125 91 63 40
35
and 2.63-4.78 in zoea VII-IX at 25°C (values for 1 and 15 nauplii.ml-’ food density). Table 2 shows the gross growth efficiencies estimated from hatching to each larval stage for larvae reared with a mean food density 5 nauplii*ml-‘. The duration of larval development, and changes in length and weight during development in Fig. 2. At 20°C the first postlarvae appeared at the 20th day post-hatch, attaining a dry weight of 540 pg by the end of larval development. At this stage, gross growth efficiency was calculated to be 25.0%. At TABLE 2 Gross growth efficiencies estimated for Palaemon
larvae
serratus
Increase of larval weight (pg)
Estimated dry matter ingested from hatching (pg)
Gross growth efficiency (%)
Temperature: 20°C II 3 III 6 IV 9 V-VI 13 VII- IX 17 VIII-PL 20
25 53 120 190 295 445
171 372 633 961 1413 1782
14.6 14.2 19.0 19.8 20.9 25.0
Temperature: 25°C II 2 III 4 IV 6 V-VI 8 VII-IX 10 VIII--PL 16
35 51 109 213 277 551
155 405 643 907 1145 2174
22.6 12.6 17.0 23.5 24.2 25.3
Final stage
Days from hatching
_
25”
-0.8
++
0
*’ -
l
: -0.4
* 0
3
0 0
_ 4
0 n’“-
z
>
M,vlll VIP
‘X
PL --0.2
g
O,“E.r----
L,j,,,,,,,,,,,,,,,I
10
16
DAYS
Fig. 2. Larval development: length t SD (black symbols) and weight (white symbols) of serratus larvae reared at 20” and 25°C.
Palaemon
36
25”C, the first metamorphosis occurred at the 16th day post-hatch. The larvae obtained a final weight of 650 1.18and had a gross growth efficiency of 25.5%. DISCUSSION
The success of a diet for larval rearing of fish and crustaceans is dependent on other factors besides nutrition~ quality. Catch efficiency, which is related to feeding behavior and food level, is of primary importance. The present study demonstrates increasing ingestion rates with increasing food density. This response has been reported for the larvae of several crustacean species (Gopalakrishnan, 1976; San, Feliti et al., 1976; Emmerson, 1984; Ytifera et al., 1984). As Boehlert and Yoklavich (1984) pointed out, this pattern suggests a feeding strategy based on the m~~ization of ingestion at higher prey densities, and may be related to random high patchers of plankters in natural habitats. Data reported for Macrobruchium larvae (Moller, 1978) indicate that the principal form of food capture for this species depends upon chance encounters with food sources. This fact has a repercussion on culture feeding dynamics, because despite agitation, Arteemia nauplii and larvae then to concentrate by phototaxis in certain areas of the rearing tank. Therefore, food density becomes greater than anticipated, involving a more rapid food consumption. Considering the ingestion rates obtained in this work, at a stocking density of 100 larvae-ml-‘, Artemia nauplii can be exhausted before 24 h if supplied at densities below 2-3 nauplii* ml-’ during zoea I, and below 4-6 nauplii*ml-’ in zoea VII-IX. Starvation for several hours does not presuppose massive mortality, but poor growth is achieved when food is scarce (Reeve, 1969). San Feliu et al. (1976), working on larval rearing of P. serrutus, found a similar pattern of ingestion in relation to prey density (2-10 nauplii*ml-*) and larval stage (zoea I--zoea V), but a more precise comparison with their results was not possible because the experiments conditions and nauplii biomass were not given. According to Reeve (169) the larvae of this species ingest about 25-35 pg*larvdl-d-’ on the first day, and 70-80~g~larva~1~d-1 at 20 days post-hatch, when the first postlarvae appeared (culture conditions were 22”C, 32.5°/00 salinity, 100 1arvae.I’, and 5-10 nauplii*ml-’ of food density). The gross growth efficiency obtained in this period (~57%) was very much higher than those estimated in the present study. We have not a clear explanation for this, but differences in genetic characteristics and/or differences in the yolk reserves between eggs developed in cold water and those developed in temperatre water may be involved, besides the variations due to experimental conditions. The gross growth efficiencies estimated for other decapod species during larval development range between 15% and 30%, although only 3.2% was reported for Curcinus maenas (Dawirs, 1983; Sastry, 1983; Anger and Dietrich, 1984; Yufera and Rodriguez, in press). The increase of temperature from 20” to 25°C results in an acceleration
37
of larval development in Paluemon, as well as increased ingestion. However, the gross growth efficiency is similar at both temperatures tested. These temperatures are within the optimal range for larval growth of this species (Yagi and Ceccaldi, 1984), and variations within this range have probably little influence on growth efficiency. The present results show that Pcdaemon larvae ingest quickly the food supplied in culture. The prey density declines exponentially and can be scarce in several hours. The effort of obtaining food is considerably greater below a certain food level, involving an important energetic cost. However, an excessive initial flood density to prolong the duration of nauplii in the rearing tanks involves problems of water quality and loss of nutritive value in the old nauplii. Thus, a frequent replenishment of nauplii to maintain a moderate food density, or lower stocking density of larvae is recommended. Daily consumption is higher at 25”C, but the larval development, and therefore the dependence on live food, is shorter. The cost in Artemia biomass during this period is similar (Z 2000 pg) at both temperatures: this is about four times the dry weight attained at the end of larval development. ACKNOWLEDGEMENTS
We thank two anonymous proved the manuscript.
reviewers for constructive
comments
which im-
REFERENCES K. and Ditrich, A., 1984. Feeding rates and gross growth efficiencies in Hyas L. larvae (Decapoda: Majidae) reared in the laboratory. J. Exp. Mar. Biol. Ecol., 77: 169-181. Benijts, F., Van Voorden, E. and Sorgeloos, P., 1976. Changes in the biochemical composition of the early larval stages of the brine shrimp, Artemia salina L. In: G. Persoone and E. Jaspers (Editors), Proc. 10th Eur. Symp. Mar. Universa Press, Wetteren, Belgium, pp. l-9. Boehlert, G.W. and Yoklavich, M.M., 1984. Carbon assimilation as a function of ingestion rate in larval Pacific herring, Clupea harengus pallasi Valenciennes. J. Exp. Mar. Biol. Ecol., 79: 251-262. Dawirs, R.R., 1983. Respiration, energy balance and development during growth and starvation of Carcinus maenas L. larvae (Decapoda: Portunidae). J. Exp. Mar. Biol. Ecol., 69: 105-128. Emmerson, W.D., 1980. Ingestion, growth and development of Penaeus indicus larvae as a function of Thalassiosira weissflogii cell concentration. Mar. Biol., 58: 65-73. Emmerson, W.D., 1984. Predation and energetics of Penaeus indicus (Decapoda: Penaeidae) larvae feeding on Brachionus plicatilis and Artemia nauplii. Aquaculture, 38: 201-209. of British prawns and shrimps (Crustacea: Fincham, A.A., 1983. Larval development Decapoda: Natantia). 4. Palaemon (Palaemon) serratus (Pennant, 1777) and functional morphology of swimming. Bull. Br. Mus. Nat. Hist. (Zool.), 44(2): 125-161. Gopalakrishnan, K., 1976. Larval rearing of red shrimp, Penaeus marginatus (Crustacea). Aquaculture, 9: 145-154.
Anger,
amneus
38 Moller, T.H., 1978. Feeding behaviour of larvae and postlarvae of Macrobrachium rosenbergii (de Man) (Crustacea: Palaemonidae). J, Exp. Mar. Biol. Ecol., 35: 251-258. Reeve, M.R., 1969. Growth, metamorphosis and energy conversion in the larvae of the prawn, Palaemon serratus. J, Mar. Biol. Assoc. U.K., 49: 77-96. Rodriguez, A., 1981. Growth and sexual maturation of Penaeus kerathurus (Forsklll, 1775) and Palaemon serratus (Pennant) in salt ponds. Aquaculture, 24: 257-266. San Feliti, J.M. Mufioz, F., Amat, F., Ramos, J., Peiia, J. and Sanz, A., 1976. Cultivo experimental de larvas de crustbeos y peees en tanques. Inf. T&n. Inst. Inv. Pesq., 36,47 pp. Sastry, A.N., 1983. Pelagic larval ecology and development. In: F.J. Vernberg and W.B. Vernberg (Editors), The Biology of Crustacea. Vol. 7. Behavior and Ecology. Academic Press, New York, pp. 213-282. Schauer, P.A., Johns, D.M., Qlney, C.E. and Simpson, K.L., 1980. International study on Artemia. IX. Lipid level, energy content and fatty acids composition of the cysts and newly hatched nauplii from five geographical strains of Artemia. In G. Persoone, P. Sorgeloos, 0. Roels and E. Japsers (Editors). The Brine Shrimp Artemia. Vol. 3. Ecology, Culturing, Use in Aquaculture. Universa Press, Wetteren, Belgium, pp. 394405. Wickins, J.F., 1972. The food value of brine shrimp Artemia L., to larvae of the prawn, Palaemon serratus Pennant. J. Exp. Mar. Biol. Ecol., 10: 151-170. Yagi, II. and Ceccaldi, H.J., 1984. Influence combinee des facteurs temperature et salinit& sur la metamorphose et la croissance larvaire de la crevette rose Paiaemon serratus (Pennant) (Crustacea, Decapoda, Palaemonidae). Aquaculture, 37: 73-85. Ytifera, M. and Rodriguez, A., in press. Tasas de alimentacibn y crecimiento de Palaemonetes uarians (Crustacea: Palaemonidae) durante el desarrollo larvario. Inv. Pesq. Yufera, M., Rodriguez, A. and Lubi&n, L.M., 1984. Zooplankton ingestion and feeding behavior of Penaeus kerathurus larvae reared in the laboratory. Aquaculture, 42: 217-224. Zariquiey, R., 1968. Crustaceos decapodos ibericos. Inv. Pesq., 32: I-510.