Annls Soc. r. zool. Belg. — T. 113 (1983) — fase. 2 — pp. 155-164 — Bruxelles 1983
(Manuscript received on 18 August 1982)
IN T E R N A T IO N A L ST U D Y O N A R T E M I A (1). X V II.
E N ER G Y C O N S U M P T IO N IN C Y ST S AN D EARLY
LAR V AL ST A G E S OF V A R IO U S G E O G R A PH IC AL
S T R A IN S OF A R T E M I A
by
P aul
V A N H A E C K E , P a t r i c k LA YE N S and P a t r i c k SORGELOOS (2)
Artemia Reference Center, State University of Ghent
J. Plateaustraat 22, B-9000 Ghent (Belgium)
SU M M ARY
Variations in dry weight, caloric content and ash content during cyst hatching and
early larval development have been studied for various geographical strains of Artemia.
In general, decapsulated cysts contain 30 to 40 % more energy than freshly hatched
nauplii; for Chaplin Lake and Buenos Aires Artemia this difference amounts to 57 % .
Ash contents increase as decapsulated cysts hatch into instar I and molt into instar II-I II
nauplii. Over a 24 h larval developmental period individual dry weights and energy
contents of the nauplii decrease with 16-34 % and 22-37 % respectively.
A small but significant correlation exists between the survival rate of starved nauplii
and either the energy content of instar I and instar II-I II nauplii or the proportional
energy consumption during metabolism from decapsulated cysts to instar I I-I II nauplii.
The potential impact of these results on the use of Artemia in aquaculture hatcheries
is discussed.
IN T R O D U C T IO N
Artemia only can ingest food from the second instar stage onwards ( B e n e s c h ,
1969). As a result their organic contents decrease from the restart of the cyst’s
metabolism through the hatching of the nauplius and into the instar II larval
stage ( V o n H e n t i g , 1971) ; e.g. in individual nauplii of San Francisco Bay (California)
origin dry weight and energy contents decrease by 2 0 % respectively 27 % as they
molt from the instar I into the instar II-III stage ( B e n i j t s et al., 1976). As a result
Artemia nauplii as food source in aquaculture hatcheries are most efficiently used
as freshly-hatched nauplii. In practice, however, not much attention is paid to this
potential economy in Artemia cyst uses ; e.g. techniques for cyst incubation and
nauplii harvesting are usually not standardized, Artemia nauplii are sometimes
stored for one or more days prior to be fed to the predator larvae, as Artemia nauplii
are distributed only once a day, their retention time prior to being captured by
the predator larvae often exceeds 24 h.
In addition more and more new Artemia cyst sources are used ( S o r g e l o o s ,
1980a) and nothing is known about the potential differences in terms of critical
drops in energy contents during larval developments, or survival rates in culture
tanks in unfed conditions.
(1) International interdisciplinary study on Artemia strains coordinated by the
Artemia Reference Center, State University of Ghent, Belgium.
(2) Research Associate at the Belgian National Science Foundation.
In this regard, we have studied nauplius survival at two different temperatures
as well as energy contents and dry weights of instar I and instar II-III larvae for
the most commonly used Artemia cyst sources.
Since it has recently been shown that decapsulated cysts can be used as a direct
food source for many aquaculture organisms ( B r u g g e m a n et, al., 1980) which could
lead to a further economy in the use of Artemia cysts, we have also analyzed the dry
weight and energy contents of decapsulated cysts for the same geographical Artemia
sources.
M A T E R IA L S
AND
M ETHODS
Details on the geographical origin of the Artemia strains studied are provided
in Table I.
TABLE I
List of « Artemia » sources studied
Geographical source
of cysts
San Francisco Bay (Ca-USA)
San Pablo Bay (Ca-USA)
Macau (Brazil)
Barotac Nuevo (Philippines)
Chapfin Lake (Canada)
Buenos Aires (Argentina)
Bahia Salinas (Puerto Rico)
Great Salt Lake (Ut-USA)
Shark Bay (Australia)
Margherita di Savoia (Italy)
Tientsin (People’s Republic of
China)
Lavalduc (France)
batch num­
ber or year
of harvest
mode of
reproduction
abbreviation
(B : bisexual;
used
P : parthenogenetic)
n° 288-2596
n° 1628
May 1978
n» 871172
1978
1978
1977
—
1977
n» 114
1977
B
B
B
B
P
P
SFB
SPB
MAC 1
MAC 2
PHIL
CHA
ARG
PR
GSL
SB
MS
1978
1979
P
P
T IE N
LAV
B
B
B
B
B
Cysts were incubated in natural seawater (35 % 0 salinity) at a temperature
of 25° i 0 .5 ° C and an illumination of 1,000 lux. A homogenous population of
instar I nauplii was obtained by harvesting the nauplii when 90 % hatching was
attained or, for the slow hatching strains, 8 to 1 0 h after the appearance of the first
nauplii. The nauplii were separated from their hatching debris with a separator
box ( P e r s o o n e and S o r g e l o o s , 1972). Half of the nauplii was analyzed immediately,
the other half was incubated in an Erlenmeyer flask, containing 1 1 natural seawater
at 25° i 0 .5 °C that was aerated by gentle air-bubbling and illuminated at 1,000 lux.
After 24 h incubation, the nauplii had molted into the instar II and some even
in the instar ITT stage. They were separated from their exuviae and a few dead
nauplii with the separator box and were analyzed.
Cysts that had been cleaned following the procedure of S o r g e l o o s et al. (1978)
were decapsulated according to the technique of B r u g g e m a n et al. (1980).
Dry-weight analyses of nauplii and cysts were carried out following the method
described by V a n h a e c k e and S o r g e l o o s (1980). Ash weights were determined on
dried samples that had been incinerated for 4 h at 550° C.
Energy contents were analyzed on six replicate samples of approximately
25 mg dry material per strain following the wet oxidation technique of M a c i o i .e c
(1962).
The data obtained were analyzed for statistical significance with a one way
analysis of variance (Model I ; S o k a l and R o h l f , 1969). For comparisons among
means, Duncan’s Multiple Range test was used ( S n e d e c o r and C o c h r a n , 1967).
The survival experiments were carried out in glass petri dishes. Per strain,
three dishes each containing 1 0 freshly hatched nauplii in 1 0 ml filtered natural
seawater were incubated in darkness at temperatures of 20° C and 30° C respectively.
Two replicate survival tests were conducted for each Artemia strain. Once a day
for the 20° C run and twice a day for the 30° C run, mortality was checked and
dead larvae removed. LT 50 values were calculated according to the method of
Litchfield (1949) and compared for statistical differences following the technique
of Litchfield and Wilcoxon (1949).
r e s u l t s
From Table II it appears that the individual dry weights of decapsulated cysts
vary considerably from one strain to another ; i.e. overall variation exceeding
100 % . No significant differences could be noted among batches from the same strain
nor between cysts originating from the same parental material but produced at
different localities, e.g. Macau, Barotac Nuevo and San Francisco Bay.
The variation in ash content between Artemia strains is rather small (3.785.36 %).
Differences in energy content between the strains studied are low, the maximal
range being 9.3 % . Statistical analyses revealed, however, that the energy content
of decapsulated cysts from the parthenogenetic strains of Margherita di Savoia,
Tientsin and Lavalduc is significantly lower than for most other sources. Shark
Bay Artemia make, however, an exception, being a parthenogenetic strain with
a cyst energy-content similar to the values obtained for most bisexual strains.
As a result of the differences in individual dry weights, the individual caloric
contents vary widely from one strain to another.
From the Tables III and IV it is clear that for the instar I respectively instar 11III nauplii variations in individual dry weight, ash content and energy content are
similar to those of decapsulated cysts. As the embryos have developed from cyst
to instar I and instar II or III, the ash contents have increased, whereas the individual
dry weights and individual energy contents have dropped.
Statistical analysis of the survival data shown in Fig. 1 reveals a great similarity
in response among Artemia from different geographical origin exposed to 20° C
and 30° C. The nauplii of Chaplin Lake and Buenos Aires always die off earliest,
whereas Shark Bay Artemia have the longest mean lethal time.
TA B LE II
Individual dry weight, ash content, and energy content of decapsulated « Artemia » cysts
from various geographical origin
Source of cysts
individual
dry weight
(in (Jtg)
San Francisco Bay
San Pablo Bay
Macau (May 1978)
Macau (Batch 871172)
Barotac Nuevo
Chaplin Lake
Buenos Aires
Bahia Salinas
Great Salt Lake
Shark Bay
Margherita di Savoia
Tientsin
Lavalduc
ash
content
(in % of
dry
weight)
2.15
2.48
2.25
2.30
2.21
3.05
2.66
2.87
3.23
3.42
4.51
4.17
3.98
4.37
4.28
4.31
4.21
4.09
5.36
5.26
4.82
4.51
3.78
4.49
5.09
4.25
energy
individual
content
energy
(in joules/g
content
dry
(in joules)
weight)
23
23
22
22
23
23
22
22
22
23
21
21
21
250
160
650
540
370
010
290
640
900
050
380
740
890
0.0500
0.0574
0.0510
0.0523
0.0516
0.0702
0,0593
0,0650
0,0740
0.0788
0.0964
0.0907
0.0871
TA B LE III
Individual dry weight, ash content and energy content of instar I « Artemia » nauplii
from various geographical origin
Source of cysts
individual
dry weight
(in |xg)
San Francisco Bay
San Pablo Bay
Macau (May 1978)
Macau (Batch 871172)
Barotac Nuevo
Chaplin Lake
Buenos Aires
Bahia Salinas
Great Salt Lake
Shark Bay
Margherita di Savoia
Tientsin
Lavalduc
1.63
1.92
1.68
1.74
1.68
2.04
1.72
2.10
2.42
2.47
3.33
3.09
3.08
ash
content
(in % of
dry
weight)
6.33
6.17
5.83
5.88
6.07
6.59
6.32
5.51
5.69
5.28
6.17
6.63
6.03
individual
energy
energy
content
content
(in joules/g
(in
dry
joules)
weight)
22 480
22 330
22 710
22 520
22 740
21 940
22 020
22 390
22 350
22 330
21 760
22 050
21 760
0.0366
0.0429
0.0381
0.0392
0,0382
0.0446
0.0379
0.0470
0.0539
0.0576
0.0725
0.0681
0.0670
TA B LE IV
Individual dry weight, ash content and energy content of instar I I -I I I « Artemia » nauplii
from various geographical origin
Source of cysts
individual
dry weight
(in (ig)
San Francisco Bay
San Pablo Bay
Macau (May 1978)
Macau (Batch 871172)
Barotac Nuevo
Chaplin Lake
Buenos Aires
Bahia Salinas
Great Salt Lake
Shark Bay
Margherita di Savoia
Tientsin
Lavalduc
ash
content
(in % of
dry
weight)
1.25
1.36
1.15
1.21
1.21
1.59
1.13
1.68
1.59
2.07
2.51
2.37
2.20
10.35
10.20
10.11
10.21
10.08
11.12
9.75
9.87
9.61
8.54
9.10
9.84
9.33
individual
energy
energy
content
content
(in joules/g
(in
dry
joules)
weight)
21
21
20
21
21
19
20
21
21
21
20
19
20
520
110
880
120
470
450
370
810
310
680
840
940
150
0.0269
0.0287
0.0240
0.0256
0.0260
0.0311
0.0233
0.0366
0.0339
0.0449
0.0523
0.0473
0.0443
D IS C U S S IO N
T h e d a ta rep orted in th is stu d y clea rly d em on stra te th a t in Artemia b o th the
in d iv id u a l w eig h t a n d th e e n erg y c o n te n t co n s id e ra b ly d r o p as a resu lt o f th e h a tch in g
m eta b o lis m (see F ig . 2). S in ce th e en erg y c o n te n ts ex p ressed p er g ra m o rg a n ic
w eig h t d o n o t ch a n ge sig n ifica n tly as e m b ry o s d e v e lo p in to free-sw im m in g n a u p lii,
it is h ig h ly lik e ly th a t th e fa t-p r o te in -c a r b o h y d r a te ra tios rem a in a p p r o x im a te ly
co n s ta n t d u rin g th is d ev e lo p m e n ta l p eriod .
F o r m o s t Artemia strains stu d ied , th e rela tiv e d ifferen ce in w e ig h t a n d en erg y
co n te n t b etw een e m b r y o s a n d in sta r I n a u p lii is fa ir ly co n s ta n t w ith in th e ran ge
o f 30 -40 % ; C h ap lin L a k e a n d B u en os A ires Artemia, h ow ev er, con su m e su b sta n tia lly
m ore en erg y fo r h a tch in g , rela tiv e differen ces in in d iv id u a i en erg y c o n te n t a m ou n tin g
u p to 57 % . I t is n o t clear i f th is is rela ted to th e p h y s ic o -ch e m is tr y o f th e b io to p e s ,
e.g. C h ap lin L a k e Artemia is th e o n ly su lp h ate stra in stu d ied h ere ( H a m m e r , 1978),
or th e g e n o ty p ica l orig in o f th e brin e sh rim p strain , e.g. B u en os A ires Artemia is
th e o n ly rep resen ta tive o f th e Artemia persimilis sib lin g sp ecies w h ereas th e oth er
strains stu d ie d b elon g to eith er Artemia franciscana (7 sou rces) o r Artemia parthenogenetica (4 sou rces) ( B o w e n et al., 1978 ; A b r e u - G r o b o i s a n d B e a r d m o r e , 1980).
T h e h ig h est in creases in h a tch in g o u tp u t a t lo w sa lin ity (5 0/ 00 in stea d o f 35 ° / 00)
bein g o b s e rv e d fo r p recisely th e sam e tw o strain s ( V a n h a e c k e a n d S o r g e l o o s ,
1983) p ro v id e s fu rth e r su p p o rt fo r th e h y p o th e s is o f S o r g e l o o s (19 80 b) th a t th e
in crease in h a tc h a b ility a t lo w salin ities is rela ted to en ergy.
I n v ie w o f th e d a ta p resen ted, it is clear th a t in stea d o f fr e sh ly -h a tch e d n a u p lii,
the use o f d eca p su la ted cy s ts o f Artemia as a d ir e c t fo o d sou rce ca n lea d to a su bsta n -
CHA
BA
GSL
It
GSL1
SPB
MAC 1
TIEN
MAC 2
MS
LAV
SFB
PR
PHIL
SB
—r -
—1—
—I—
—r-
20
40
60
80
—
100
I----------- 1------------1—
120
140
LT50 (in hours)
160
B
CHA
BA
SFB
LAV
PHIL
SPB
MS
PR
MAC 2
TIEN
MAC 1
GSL
GSL1
SB
10
LT50 (in hours)
—r—
— r20
30
40
50
60
70
80
90
result of a replicate test in time
Fig. 1. — LT 50 values for unfed Artemia nauplii from different geographical origin
incubated at 20° C (A) and 30° C (B). Strains connected by the same vertical line are
not significantly different at the P < 0.05 level.
II
Fig. 2. — Comparison of the individual energy contents and individual dry weights of
decapsulated cysts, instar I and instar II-I II nauplii from different geographical strains
of Artemia.
tial e c o n o m y in a q u a cu ltu re h atch eries. D eca p su la ted cy s ts n o t o n ly co n ta in 30 %
to 40 % m ore en erg y as co m p a re d t o fre sh ly -h a tch e d n a u p lii b u t th eir m ean v o lu m e
is o n th e a v era g e 30 % sm aller (ca lcu la te d fr o m v o lu m e tr ic d a ta b y V a n h a e c k e
an d S o r g e l o o s , 1980 a n d V a n h a e c k e et al., 1980). T h is m eans th a t d ca p su la ted
cy s ts ca n be offe re d t o th e fish a n d cru sta cea n la rvae a t an earlier life stage. T h e
p rom isin g p ossib ilities in th is reg a rd h a v e a lrea d y b een d em o n s tra te d fo r several
p red a tors (see
B ru ggem an
et al., 1980).
Individual biomass and energy content further decrease as the free-swimming
Artemia nauplii develop into instar 11 larvae (see Fig. 2). The data presented in this
study for the S an Francisco B ay strain are in accordance with the results o f B e n ijt s
et al. (1976) : e.g. 23 respectively 20 % decrease in individual dry weight ; 26 respec­
tively 27 % drop in individual energy content. Large variation, however, is found
among the Artemia strains studied, i.e. from 16 to 34 % for dry weights and from
22 to 37 % for individual caloric contents. N o correlation could be found with
biotope differences nor with genotypical characteristics. Artemia nauplii from the
same parental stock (San Francisco Bay, Macau and Barotac Nuevo) metabolize
in fact at different rates. A possible source o f strain differences might be attributed
to the different swimming speeds o f the nauplii as reported for at least some o f the
strains studied here by M i l l e r et al. (1979). The data reported for the different
Artemia cyst sources provide further evidence for the critical need to standardize
the hatching procedures as to always assure feeding with the most energetic form
o f brine shrimp when using Artemia nauplii in fish and crustacean hatcheries
(B e n ijt s
et al., 1976).
W h erea s a 24 h a g in g o f th e n a u p lii has a sig n ifica n t im p a c t o n th eir en erg y
c o n te n t, n a u p lia r v ia b ilit y d oes n o t seem to ch a n ge m u ch a fter 1 o r 2 d a y s o f
stora ge. A g a in sig n ifica n t v a r ia tio n ex ists a m on g strains. S in ce C o l l i n s (1978)
o b s e rv e d a correla tion b etw een n a u p lia r su rv iv a l a n d n a u p lia r size w e h a v e p e rform ed
a d eta iled correla tion an alysis b etw een th e su rv iv a l o f th e n a u p lii an d th eir v a riou s
stra in ch a ra cteristics re p o rte d in th is stu d y . S u rv iv a l a t 20 ° C a n d 3 0 ° C d oes n ot
sig n ifica n tly correla te w ith n eith er th e d r y w eig h t n o r in d iv id u a l en erg y c o n te n t
o f c y s ts a n d inst ar I n a u p lii n or w ith th e a m o u n t o f en erg y con su m ed d u rin g h a tch in g
an d e a rly d e v e lo p m e n t. S u r v iv a l a t b o th tem p era tu res, seem s, h ow ev er, t o be sig n i­
fic a n tly corre la te d (P < 0.0 5) w ith th e en erg y c o n te n t (ex p ressed in jo u le /g d r y
w e ig h t) o f in star I (r = 0.5 5 - 0.7 2) an d in star 1L -H I n a u p lii (r = 0.61 - 0.6 4 ). A
sig n ifica n t co rre la tio n (P < 0.0 5) also o c cu rs b etw een th e m o r ta lity rate o f th e
n a u p lii a n d th e g lo b a l p ercen tu a l en erg y c o n s u m p tio n fr o m cy s t to in star 11-111
n a u p liu s (r = 0.8 2 a t 20 ° C ; r = 0.62 a t 30° C). A lth o u g h som e rela tion sh ip m a y
e x ist b etw een th e e n e rg y c o n te n t a n d en erg y c o n s u m p tio n o f th e n a u p lii an d th eir
su rviv a l, th e r e la tiv e ly low v a lu e fo r th e correla tion coefficien t suggests th a t still
oth er p a ra m eters m a y in terfere.
a c k n o w l e d g e m e n t
T h is stu d y w as su p p o r te d b y th e B elgia n
(N .F .W .O .) th r o u g h G ra n t F .K .F .O . 2.0010.78.
W e are v e r y in d e b te d t o D r. ir. E .
.J a sp e rs
N a tio n a l
S cien ce
F o u n d a tio n
fo r p ro o fre a d in g th e m a n u scrip t.
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