Embryonic and larval development of largescaled scorpionfish Scorpaena scrofa (Scorpaenidae)

Abstract

The embryonic and early larval development of the laboratory-reared largescaled scorpionfish, Scorpaena scrofa is described. Fertilized eggs were pelagic and elipsoidal with a homogeneous and unsegmented yolk (no oil globule) surrounded with transparent gelatinous layer. Eggs ranged in diameter from 0.83 to 0.95 mm, with a mean (± SD) of 0.89 ± 0.121 mm. Embryonic development lasted 31 h 45 min at a mean temperature of 25.6°C. Newly hatched larvae measured 2.09 ± 0.07 mm total length in average (range 2.0-2.25 mm). The yolk was completely absorbed by day 4 after hatching. Changes in length and shape of yolk-sac larvae and larvae during the first seven days after hatching are also presented.

Full text

This Corrigendum was requested by the Editorial Board of Cybium when I informed the Editor-in-

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
-
Scorpaena
scrofa

I
Cybium 2008, 32(1): 88.
Corrigendum
 
 .
Embryonic and larval development of largescaled
scorpionsh Scorpaena scrofa (Scorpaenidae)
by
 Ivan 

ABSTRACTScorpaena
scrofa





Embryonic and larval development of largescaled
scorpionfish Scorpaena scrofa (Scorpaenidae)
by
Jakov DUL I(1), Jurica JUG-DUJAKOVI (2), Vlasta BARTULOVI (3), Branko GLAMUZINA (3),
Edhem HASKOVI (4) & Bo ko SKARAMUCA (3)
A B S T R A C T. - The embryonic and early larval development of the laboratory-reared largescaled scorpionfish, S c o r p a e n a
scrofa
is described. Fertilized eggs were pelagic and elipsoidal with a homogeneous and unsegmented yolk (no oil globule)
surrounded with transparent gelatinous layer
. Eggs ranged in diameter from 0.83 to 0.95 mm, with a mean (± SD) of 0.89 ±
0.121 mm. Embryonic development lasted 31 h 45 min at a mean temperature of 25.6°C. Newly hatched larvae measured
2.09 ± 0.07 mm total length in average (range 2.0-2.25 mm). The yolk was completely absorbed by day 4 after hatching.
Changes in length and shape of yolk-sac larvae and larvae during the first seven days after hatching are also presented.
RÉSUMÉ.- Développement embryonnaire et larvaire de la rascasse rouge, Scorpaena scrofa (Scorpaenidae).
Le développement embryonnaire et larvaire en laboratoire de la rascasse rouge, Scorpaena scro f a est décrit. Les œufs
fertilisés sont pélagiques et ellipsoïdaux avec un vitellus homogène et non-segmenté (sans globule lipidique) entouré par
une couche gélatineuse transparente. Le diamètre des œufs varie de 0,83 à 0,95 mm. Le développement embryonnaire a
duré 31 h 45 min à une température moyenne de 25,6°C. Après l’éclosion, les larves ont une longueur totale de 2,09 ±
0 , 0 7 mm. Le vitellus a été complètement absorbé 4 jours après l’éclosion. Des changements de longueur et de forme des
larves pendant les sept premiers jours après l’éclosion sont également présentés.
Key words. - Scorpaenidae - Scorpaena scrofa - Egg - Yolk-sac larvae - Larvae - Embryonic development.
Cybium 2007, 31(4): 465-470.
(1) Institute of Oceanography and Fisheries, POB 500, 21000 Split, CROATIA. [dulcic@izor.hr]
(2) University of Dubrovnik, Research and Development Centre in Mariculture, Ston, CROATIA.
(3) University of Dubrovnik, Department of Aquaculture, ire Cari a 4, 20000 Dubrovnik, CROATIA.
(4) Faculty of Natural Sciences and Mathematics, Sarajevo, BOSNIAAND HERZEGOVINA.
L a rgescaled scorpionfish, Scorpaena scro f a L i n n a e u s ,
1758, is a subtropical species distributed throughout the
Mediterranean Sea (except Black Sea), and in the eastern
Atlantic, from British Isles (rare) to Senegal including
Madeira, the Canary islands, and Cape Verde (Eschmeyer,
1986). It is solitary and sedentary species over rocky, sandy
or muddy bottoms to depths of 500 m. It feeds on fishes,
crustaceans and mollusks (Hureau and Litvinenko, 1986).
L a rgescaled scorpionfish is a highly commercial species in
the coastal fisheries along the Croatian coast (eastern Adriat-
ic) (Jardas, 1996). Information on early development stages
of largescaled scorpionfish is sparse. Description of egg and
larval stages was presented only by Sparta (1942).
This paper presents the data about the embryonic and lar-
val development in aquaria conditions at in situ t e m p e r a t u r e
and the descriptions of early life history stages of S. scro f a.
The objectives are to describe the early life history, to assist
in the identification of planktonic stages of this species and
to compare this species to other scorpaenid taxa in an
attempt to contribute to a taxonomic resolution of the scor-
paenids.
MATERIAL AND METHODS
Samples of S. scro f a were obtained by gill-net from the
P e l j e ac channel (eastern middle Adriatic) on 15 July 2005.
Males (four specimens) were ranged between 24.4 and
2 7 . 7 cm, while females (7 specimens) between 18.0 and
25.6 cm. Specimens were returned alive to laboratory of
Development Research Centre in Aquaculture in Ston (Croa-
tia) and placed in a 250-l tank with the addition of pure oxy-
gen. The fish spawned spontaneously during night (between
00 h 00 and 03 h 00). The fertilized eggs were transferred to
several 150-l incubators (about 350 ml each) with a constant
flow of 100-120% seawater filtered daily through a 50
µ
m
mesh net at in situ s a l i n i t y, temperature and natural photope-
riod. Atemperature range between 24.8 and 27.2°C (mean
25.6
±
0.429°C), salinity 37.6 and 38.2 psu (mean 37.95
±
0.159 psu), oxygen 7.8 and 8.3 mg l-1.
The characteristics of newly-spawned ripe and fertilized
eggs were noted, together with the duration of each embry-
onic stage. Embryonic development was observed under a
binocular microscope. The diameters of the eggs were mea-

sured. One hour after fertilization a sample of 10-15 eggs
was taken every 7-10 min to determine the exact time of first
cleavage. Embryogenesis was examined at different time
intervals. Anaesthetized larvae in live condition were mea-
sured to an accuracy of 0.01 mm using an ocular micrometer
attached to a binocular microscope. The following measure-
ments were taken: total length, the distance along the mid-
line of the body from the tip of the snout to the end of the
caudal fin; notochord length, the distance along the midline
of the tip of the snout to the end of the notochord; preanal
length, distance along the midline of the body from the tip of
the snout to the vent; body depth, the perpendicular depth of
the trunk at the anus; greatest body depth, body depth at its
widest point; length of pectoral fin, yolk-sac volume and
horizontal eye diameter. The mouth width of larvae was also
recorded. About 10-15 living yolk-sac larvae and larvae
were used for each measurement. The time of yolk-sac
resorption as well as to mouth opening were recorded. Car-
diac contraction per minute was also recorded at each mea-
surements. One day before hatching, the flow (40-60%) was
opened through 125-
µ
m mesh outlet filter. Upon resorption
of the yolk-sac and opening of the mouth, the larvae were
fed on A rtemia salina and rotifers, Brachionus plicatilis,
cultured in a thermostatic chamber at 26°C and 25-28 psu.
On day 8 after fertilization, all larvae have died, so observa-
tions and measurements were ended.
RESULTS
Egg characteristics and embryonic development
Fertilized eggs were pelagic and elipsoidal with a homo-
geneous and unsegmented yolk surrounded with transparent
gelatinous layer. Eggs ranged in diameter from 0.83 to
0 . 9 5 mm, with a mean (
±
SD) of 0.89
±
0.121 mm. T h e r e
were no oil globule(s) in the eggs. Table I i l l u s t r a t e s
changes observed during embryonic development at an
average of 25.6°C. The first cleavage occurred at about 1 h
after fertilization, the second after 2 h 15 min, and the third
at 3 h 40 min. At 5 h 15 min, the blastoderm was in
advanced stages of cleavage indicating a “mulberry stage”,
while gastrulation started 11 h 10 min after fertilization.
Neurula stage started 12 h 45 min after fertilization, peri-
blast still not closed. Formation of the embryo began after
16 h, and somatic segmentation after 18 h 15 min. The pres-
ence of Kupffer cells is registered 17 h 10 min after fertil-
ization. Between 20 and 23 h, optic vesicles formed, olfac-
tory lobes differentiated and the pericardial cavity was
developing. After 26 h, somite differentiation was complet-
ed while optic vesicles and olfactory lobules were clearly
visible. The heart was observed beating after 26 h 15 min,
while movements of the embryo were observed 28 h after
fertilization. After 29 h 30 min, the embryo occupied three-
quarters of the yolk-sac circumference. Hatching started
Embryonic and larval development of largescaled Scorpaena scrofa DUL IET AL.
466 Cybium 2007, 31(4)
Figure 1. - Scorpaena scro f a. A: Mull-
bery stage; B: Early gastrula;
C: Somatic segmentation starts and
presence of Kupff e r’s cells (arrow); D:
Stage 30 h. [A: Stade morula ; B:
Stade gastrula ; C: Début de la seg -
mentation somatique et présence de
cellules de Kupffer (flèche) ; D: Stade
à 30 h.]

after 30 h 25 min, and after 31 h 45 min all yolk-sac larvae
hatched.
Larval development
The newly hatched yolk-sac larvae were transparent and
floated at the surface with the yolk-sac uppermost and some-
times in a lateral position without significant movement,
except for sporadic tail thrusts (Fig. 2A). Total length varied
between 2.00 and 2.25 mm (average length 2.09 ± 0.07 mm).
The finfold invaded much of the body. The body was seg-
mented into 24-25 myomeres. The eyes were unpigmented.
The mouth was undeveloped, but a short and simple gut was
observed. The anus is situated close behind the posterior of
the yolk-sac. The pectoral fin started to be visible. At the
beginning of day 2 (about 25 h after fertilization) eyes pig-
mentation started (Fig. 2B), and the average length of pec-
toral fin is 0.11
±
0.05 mm. Two thirds of yolk-sac were
absorbed. At the end of the second day, granular pigmenta-
tion had developed in the eyes and formation of the maxil-
laries and lower jaw started. Table II shows changes in
length and shape of yolk-sac larvae during the first seven
days after hatching. About 46 h after hatching, the mouth
was completely opened and functional (Fig. 2C). The mouth
opening was between 250 and 290
µ
m. By the end of day 3
(about 67 h after hatching), the foregut and hindgut were
functional. The anus was open. Pectoral fins (average length
0.25
±
0.04 mm) had three marginal rows of melanophores.
The eye was completely pigmented. By the beginning of day
4, yolk-sac was completely absorbed. Pectoral fins had four
m a rginal rows of melanophores. The body and notochord
were completely straight. The passage of food along the
digestive tract of larvae was clearly visible. Larvae were
mobile at that time, and able to swim at the surface. One row
of melanophores was visible on the ventral contour of the
DUL IET AL.Embryonic and larval development of largescaled Scorpaena scrofa
Cybium 2007, 31(4) 467
Table I. - Embryonic development of
Scorpaena scro f a at mean temperature
25.6°C. [Développement embry o n n a i re
de S. scrofa à la température moyenne
de 25,6°C.]

body from anus to the end of notochord. On the end of day 5,
pigmentation is clearly and strongly visible from the stom-
ach to the end of notochord. Few melanophores were visible
on the peritoneal and anus region. About one-third of pec-
toral fin was covered with melanophores (5-6 rows). Forma-
tion of caudal fin started (visible rays). At day 6, formation
of spinal armature in the cephalic region was visible. Rows
of melanophores started to be visible on the dorsal and ven-
tral contour of the body. Pectoral fins with 18 rays and with
5-6 marginal rows of melanophores. Formation of rays in
caudal fin started. By the end of day 6, formation of head
and opercular spines were clearly visible. Rows of
melanophores were visible on dorsal, ventral and lateral
contour of body (Fig. 2D). At the beginning of day 7, all lar-
vae have died according to presence of the urinary calculi.
DISCUSSION
According to the fact that spawning of S. scrofa occurred
in aquarium conditions, it could be stated that this species
could finish its reproductive cycle in controlled aquarium
conditions without any hormonal treatment. Parental stock
was mature at the end of July, in agreement with statements
of Jardas (1996). Spawning of the specimens occurred dur-
ing the night, that some authors connected with the adapta-
tion of species (spawned eggs are protected from the preda-
tors since the visibility for them is lower during night)
(Colin and Clavijo, 1998). S. scro f a is a partial spawner
(asynchronic development of oocytes) as scorpaenid H e l i -
colenus dactylopterus dactylopteru s (Muñoz and Casade-
vall, 2002) and sparids S p a rus aurata ( K a t a v i , 1984) and
Dentex (Dentex) dentex (Glamuzina et al., 1989).
The egg of largescaled scorpionfish was first described
by Sparta (1942). The egg size described by this author is
smaller (0.88 x 0.68 mm), than in this study (0.95 x
0.83 mm). There is no other data on egg size for this species,
but some exist for other scorpaenids (Tab. III). Jug-
Dujakovi et al. (1995) gave 1.09 to 1.14 mm for egg diame-
ters for Scorpaena porc u s, while Sparta (1941) gave 0.92 x
0.84 mm, what are the values higher then those already
reported for S. scrofa.Tåning (1961) pointed out that the egg
Embryonic and larval development of largescaled Scorpaena scrofa DUL IET AL.
468 Cybium 2007, 31(4)
Figure 2. - Scorpaena scrofa.A: Newly
hatched larva; B: 1 day-old yolk-sac
larva, C: Larva with completely
opened mouth and pectoral fin with
melanophores; D: Pectoral fins with
rows of melanophores and mela-
nophores visible on the dorsal and ven-
tral contours of the body. [A: Larv e
récemment éclose ; B: Larve âgée
d’un jour ; C: Larve avec bouche com -
plètement formée et nageoires pec -
torales pigmentées ; D: Nageoires pec -
torales avec rangées de mélanophore s
et mélanophores visibles sur les bor -
dures dorsale et ventrale du corps.]
Table II. - Changes in length and shape
of Scorpaena scro f a larvae during the
first six days from hatching at mean
temperature 25.6°C. [Changements de
longueur et de forme des larves de S .
s c r o f a pendant les six premiers jours
suivant l’éclosion, à la température
moyenne de 25,6°C.]

of Sebastes viviparu s was slightly smaller than that of
Sebastes marinus, the sizes just before hatching being 2.0 x
1.25 mm and 2.3 x 1.6 mm, respectively. It is clear that eggs
of the above mentioned species are bigger than those of
largescaled scorpionfish and have an oil globule which is not
observed for S. scro f a. The level of relative variation of egg
sizes in marine fish populations is shown to be consistent
across a wide taxonomic range of species and much of this
initial variation appears to be due to maternal eff e c t s .
According to available data, characters for identifying eggs
of largescaled scorpionfish among scorpaenid species could
be diameter and presence/absence of oil globule.
Incubation period was 31.45 hours in this study, while
Sparta (1942) observed between 4 and 5 days in eggs sam-
pled on 15t h S e p t e m b e r. The duration of incubation period
varies with temperature so this difference could be connect-
ed with the period of spawning (in this case: summer or
autumn spawning period). The duration of the egg and larval
phases vary with temperature (Lasker, 1981). In addition to
e ffects on the rate of development, temperature has been
reported to alter the relative timing of the appearance of
morphological characters. In this study temperature ranged
from 24.8 and 27.2°C in July, while during the sampling
period on 15th September in the Gulf of Napoli, the tempera-
ture was probably lower. Sparta (1942) also explains the dif-
ference according to temperature effect, i.e. sampling period
(May and September) of S. scrofa eggs.
The length of newly hatched yolk-sac larvae of S. scro f a
from this study is significantly lower (t-test, p < 0.05) then
those reported by Sparta (1942). This information could
assist in identifying newly hatched yolk-sac larvae of scor-
paenids; however, it should be of limited value since during
the first few hours after hatching yolk-sac larvae grew very
rapidly and the length changed very quickly. However, most
other characteristics, including head and body shapes, char-
acteristic pigmentation, are very similar for most of the
species described in scorpaenids. Spawning period and geo-
graphical distribution of species could also assist in deter-
mining the early life history stages (Glamuzina et al., 1998) ,
since the problems can arise if the spawning season of more
than one species of the scorpaenids overlaps.
Comparisons of embryonic and larval morphologies
m a y, in certain cases, elucidate phylogenetic relationships,
and may therefore contribute to taxonomical clarification
(Cohen, 1985). Such comparisons should be based on larval
characters that exhibit minimal flexibility to environmental
cues. Meristic and morphometric characters and develop-
mental patterns that are extremely plastic, should be avoid-
ed.
Among the characters studied, only the pigmentation pat
-
terns exhibited a considerable stability and thereby were
valid for comparisons with other taxa. Developmental char-
acters displayed higher variability, which was probably
environmentally induced, and therefore could be of limited
comparative value. Even though additional research on this
species and other scorpaenids, now in progress, should off e r
a solution to this situation.
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Reçu le 25 septembre 2006.
Accepté pour publication le 21 septembre 2007.
Embryonic and larval development of largescaled Scorpaena scrofa DUL IET AL.
470 Cybium 2007, 31(4)