Embryonic, larval and postlarval development of Haliotis asinina Linneù 1758 in laboratory condition Item Type Journal Contribution Authors Le, Duc Minh; Le, Thi Hong Download date 28/09/2021 04:19:25 Link to Item http://hdl.handle.net/1834/9310 Collection of Marine Research Works, 2000, X: 190-194 EMBRYONIC, LARVAL AND POSTLARVAL DEVELOPMENT OF HALIOTIS ASININA LINNEÙ, 1758 IN LABORATORY CONDITION Le Duc Minh, Le Thi Hong Institute of Oceanography ABSTRACT A total of 29 abalones Haliotis asinina Linneù was conditioned to photo-period of 12 h. light and 12 h. darkness. About 40-50% of 19 ripe abalones began to spawn 17-20 days after conditioning. The trochophore larvae occurred at 5-7 hours and the late veliger larvae appeared after 24-27 hours. Most of the late veliger metamorphosed to early creeping larvae after 29-32 hours. The first respiratory pore of the juvenile appeared after 30-40 days of rearing. QUAÙ TRÌNH PHAÙT TRIEÅN PHOÂI VAØ BIEÁN THAÙI CUÛA AÁU TRUØNG, AÁU THEÅ BAØO NGÖ VAØNH TAI (HALIOTIS ASININA LINNEÙ, 1758) ÔÛ ÑIEÀU KIEÄN PHOØNG THÍ NGHIEÄM Leâ Ñöùc Minh, Leâ Thò Hoàng Vieän Haûi Döông Hoïc TOÙM TAÉT Trong ñieàu kieän thí nghieäm, 29 caù theå Baøo Ngö Vaønh Tai Haliotis asinina Linneù ñöôïc phaùt duïc baèng caùch chieáu saùng 12 giôø vaø che toái 12 giôø trong moät ngaøy ñeâm. Keát quaû sau 17-20 ngaøy, 40-50% trong soá 19 caù theå thaønh thuïc sinh duïc ñaõ sinh saûn. Aáu truøng baùnh xe (trochophore) ñaõ nôû sau khi tröùng thuï tinh 5-7 giôø vaø sau 24-27 giôø xuaát hieän aáu truøng dieän baøn (veliger). Haàu heát aáu truøng dieän baøn chuyeån qua giai ñoaïn aáu theå baùm sau 29-32 giôø. Baøo Ngö con (juvenile) coù loã hoâ haáp ñaàu tieân treân voû xuaát hieän sau 30-40 ngaøy öông nuoâi. INTRODUCTION (Singhagraiwan and Sasaki, 1991; Capinpin Jr., 1995). Three species of abalone, Haliotis ovina A commercial H. asinina fishery has Gmelin, 1791, Haliotis varia Linneù, 1758 and existed in Khanhhoa province for many years, Haliotis asinina Linneù, 1758 occur in coastal but the production has decreased every year waters of Khanhhoa province (Le Duc Minh, because of stock depletion. 1998). Since 1997 the Department of Among of these three species of abalone, Biotechnology and Aquaculture, Institute of H. asinina has the best potential for Oceanography at Nhatrang has conducted commercial culture due to its large size and researches on reproductive biology and seed body weight. Its maximum shell length and production trials of H. asinina to contribute to body weight are 116.0mm and 166.4 g. re-stock coastal areas of Khanhhoa province. respectively (Le Duc Minh, 1999a). This study aimed to describe embryonic, Recent advances in Thailand and in the larval and postlarval development of H. Philippines have confirmed the potential of asinina in the experiment on the artificial this species for seed production and culture spawning of H. asinina. 190 MATERIALS AND METHOD antibiotics (10ppm Neomicin and Streptomicin, ratio 1:1) was added to the rearing container Broodstock collection and control of and kept until the veliger stage. maturity After the veliger stage finished larvae H. asinina broodstock was collected from entered the creeping stage and were provided rocky reefs in Nhatrang bay. Shell length and with benthic diatoms Navicula spp., Nitzschia total weight ranged from 68.6 to 93.4mm and spp. on transparent polyethylene sheets every from 66.0 to 157.4 g., respectively. two days. Settled abalones were on the diatom Broodstock was transported to the culture sheets during 30-40 days until they laboratory. 29 spawners (10 males and 19 reached 2.4 mm shell length. After reaching females) were placed in a raceway rectangular 2.4 mm shell length, apart from benthic cement tank (capacity 4 tons). Strong aeration diatoms as main food, abalones were was provided to ensure sufficient supply of introduced supplementary seaweed Gracilaria oxygen. To maintain a favourable rearing verrucosa. environment for the broodstock running water Embryonic, larval and postlarval stages at a rate of 5 litres/min. was provided. were monitored and described. Abalones were fed intensively on fresh The temperature in the rearing tank seaweed Gracilaria verrucosa. Fibro-cement ranged from 27.5 to 300C and the salinity was plates were placed at the bottom of the tank from 30 to 34%o. for the animals to hide. Water temperature and salinity in the tank ranged from 27 to 280C and RESULTS AND DISCUSSION from 30 to 34ppt, respectively. Spawning Gonadal condition was determined every week by the methods of Nguyen Van Chung In our study males and females began to and Nguyen Thanh Tung (1998), Le Duc Minh spawn at 17-20 days after conditioning. Males (1999b). When the gonad reached maturity and spawned first and after that females spawned. ripeness stage (dark green for female and Around 40 to 50% of the abalones in the creamy for male) abalones could be taken into container released their gametes. the spawning tank. Duration of spawning was around 30 min. So the artificial photo-period used in this study Artificial spawning was effective and inexpensive. It is not 19 ripe individuals (6 males and 13 understood why the artificial photo-period has females) were selected and placed in a 600 this effect on spawning of the abalone, H. litre composite container for artificial asinina. spawning. Photo-period spawning was induced Recently, H.ovina - another commercial according to the technique of Kikuchi and Uki important abalone species in Vietnam has been (1974). The container was covered with black successfully induced to spawn by the use of cloth in daytime (AM 6.00 to PM 18.00). thermal shock (Nguyen Van Chung et al., During night time the cloth was removed and 1996), thermal shock in combination with lights turned on (PM 18.00 to AM 6.00). ultraviolet- irradiated seawater (Le Duc Minh, 1999c). But it was not effective in inducing H. Egg collection and larval rearing asinina in this experiment to spawn when Fertilised eggs were collected 15 minutes either singly or in combination with other after spawning. They were washed several stimuli. Singhagraiwan and Sasaki (1991) also times with filtered seawater and then unable to spawn H. asinina using ultraviolet distributed to 600 litre composite container. irradiated seawater. The results in our Fertilised eggs were stocked at a density of 5-7 spawning experiment show that the artificial eggs per ml. Mild aeration was provided and 191 photo-period method is the most suitable for H. After 24 to 27 h. the late veliger with asinina. developed operculum, eyes, cephalic tentacles occurred (Fig. 3). After 29 to 32 h. most of the Embryonic, larval and postlarval late veligers metamorphosed to early creeping development of H. asinina postlarvae (spat), the velum disappeared and Eggs of H.asinina were spherical, dark the foot began to grow. The creeping green in colour and had a clear jelly coat. The postlarvae settled on the diatom culture sheets size of fertilised egg was 170-180m. and shifted from planktonic to benthic mode of Egg cleavage was total, unequal, and of life. The creeping larva was characterized by the spiral type. At water temperature of 27.5 - the development of epipodium tentacles and 300C the first polar body was seen after 10 the retractor muscle in the mantle cavity. The min., and the second polar body after 15 min. creeping postlarvae continued to grow on the The first cleavage took place after 20 to 25 diatom culture sheets and became juvenile min. After 30 min. the second cleavage having the first respiratory pore after 30 to 40 occurred. After 40 to 60 min. the third division days (Fig. 4). This juvenile was 2.4mm long took place, yielding four micromeres at the and the epipodium tentacles developed more animal pole and four macromeres at the and more. vegetative pole. In comparison with hatching time of H. The embryo passed through morula and ovina which took 10 to 13h. after fertilization, blastula stages and reached gastrula stage in 70 H. asinina trochophore hatched out in only 5 to to 120 min. 7 h. The spat of H. ovina appeared after 3 to 6 After 5 to 7 h. the embryo reached the days of rearing while it was only 29 to 32 h. for trochophore stage and hatching took place. The H. asinina (Le Duc Minh, 1999c). size of newly hatched larvae was 180 to 190 Generally, the larval and postlarval m. This form of larvae was characterized by periods in H. asinina were much shorter than a prototrochal girdle (Fig. 1). The free- that in other species of abalone in Nhatrang swimming trochophore was phototactic and bay, namely H.ovina (Nguyen Van Chung et tended to move towards the upper water al., 1996). layers. Table 1 shows the age and shell length of After 9 to 10 h. most larvae developed H. asinina at formation of first respiratory transparent larval shells and reached the early pores compared with other abalone species in veliger stage, of which the apical region the world. became flat and the velum was completely developed with long cilia (Fig.2). Table 1: Age and shell length of various abalone species at formation of first respiratory pore Species Age (day) Shell length (mm) Temperature (0C) Reference H. asinina 30-40 2.4 27.5-30 Present study 30 2.1 29-30 Capinpin Jr. 1995 30 2.0 29-30 Singhagraiwan and Doi (1995) H. rufescens 60-70 1.5-1.8 14-18 Leighton (1974) H. fulgens 30-40 1.7-2.0 16-24 Leighton (1974) H.