Biological zero point in hybrid Pacific abalone.The biologic zero point (BZP BZP Benzylpiperazine BZP Bionicle Zone Power BZP Bright Zinc Plate ) of hybrid Pacific abalone abalone (ăbəlō`nē), popular name in the United States for a univalve gastropod mollusk of the genus Haliotis, members of which are also called ear shells, or sea ears, as their shape resembles the human ear. Haliotis discus hannai (China) and Haliotis discus discus (Japan) at temperatures of 16[degrees]C, 20[degrees]C, and 22[degrees]C was calculated from the developmental hatching rate, formation of larval larval 1. pertaining to larvae. 2. larvate. larval migrans see cutaneous and visceral larva migrans. retractor retractor /re·trac·tor/ (-trak´ter) 1. an instrument for holding open the lips of a wound. 2. a muscle that retracts. re·trac·tor n. 1. muscle, 90 degree torsion torsion, stress on a body when external forces tend to twist it about an axis. See strength of materials. and formation of epipodial tentacles. BZP for the early development of hybrid Pacific abalone is 6.22[degrees]C, which is an important result for the hybrid breeding of Pacific abalone. KEY WORDS: hybrid, Pacific abalone, biological zero point INTRODUCTION Pacific abalone, Haliotis discus hannai is a key aquaculture aquaculture, the raising and harvesting of fresh- and saltwater plants and animals. The most economically important form of aquaculture is fish farming, an industry that accounts for an ever increasing share of world fisheries production. organism, cultivated in China since the 1980s. Commercial seed production commenced in 1987 and, from this time to 1992, abalone aquaculture grew greatly. Most research was focused on development of hatchery hatchery a commercial establishment dedicated to the hatching of bird eggs to provide day old chicks and poults to the poultry industry. hatchery liquid the contents of unfertilized eggs. Used in petfood manufacture. seed production techniques and grow-out modes. A series of key techniques involving spawning, larval rearing, and juvenile and seed nursing were established, as well as grow-out systems. Disease and abnormal mortality has recently, however, severely disrupted the industry and promoted the hybridization hybridization /hy·brid·iza·tion/ (hi?brid-i-za´shun) 1. crossbreeding; the act or process of producing hybrids. 2. molecular hybridization 3. of Haliotis discus hannai (China) and Huliotis discus discus (Japan). Hybrid [F.sub.1] shows a significant heterosis heterosis (hĕt'ərō`sĭs): see hybrid. heterosis or hybrid vigor Increase in such characteristics as size, growth rate, fertility, and yield of a hybrid organism over those of its parents. in survival and growth and is playing an important role in Chinese abalone culture. A successful culture and high yield are assured by altering rearing conditions at three important stages during larval development: hatching, development of larval shell, and settlement (Hahn 1989). Information on BZP and effective accumulative LEGACY, ACCUMULATIVE. An accumulative legacy is a second bequest given by the same testator to the same legatee, whether it be of the same kind of thing, as money, or whether it be of different things, as, one hundred dollars, in one legacy, and a thousand dollars in another, or whether temperature (EAT) is necessary for the culture of broodstock and hatchery management. BZP is one of the values used to calculate EAT. BZP varies among abalone species, depending on water temperature in each location. The BZP has so far been investigated in seven abalone (Sawateerap et al. 2001) and this study investigates the BZP of hybrid [F.sub.1] of Pacific abalone. MATERIALS AND METHODS Conditioning of Broodstocks Mature broodstock of Haliotis discus hannai and Haliotis discus discus, with a shell length of 8 cm and a weight of 140-180 g, were used. Males and females were separately reared in different nets and placed in 0.7 [m.sup.3] plastic tanks. Filtered seawater was used and changed daily. Rearing temperature was maintained at 20[degrees]C with constant aeration aeration /aer·a·tion/ (ar-a´shun) 1. the exchange of carbon dioxide for oxygen by the blood in the lungs. 2. the charging of a liquid with air or gas. aer·a·tion n. . Broodstock were fed with fresh kelp. The dietary grazing rate was calculated daily and gonad gonad /go·nad/ (go´nad) a gamete-producing gland; an ovary or testis.gonad´algonad´ial indifferent gonad the sexually undifferentiated gonad of the early embryo. maturation was determined by size and color according to Ebert and Houk. (1984). Induced Spawning Spawning was induced in April 2000. Individuals with mature gonads were chosen for spawning. Female abalone was dried in a shade room (24[degrees]C) for 1.5 h, males for 40-60 min. Broodstock were separated, one by one, into 20-L tanks with filtered water irradiated by ultra-violet at 700 mw.L/h. At the same time, abalone for spawning was induced with flow-through seawater at 1-2 L/min and from 24[degrees]C to 22[degrees]C. Spawning occurred after about an hour. Artificial Fertilization Eggs and sperms were collected separately. Eggs were placed in the experimental container at a density of 6 eggs/mL and then maintained at different temperatures (16[degrees]C, 20[degrees]C, 22[degrees]C). Each experiment was performed in triplicate. Rearing Management The zygote zygote: see reproduction. was washed once every hour with sand-filtered seawater. After hatching, healthy larvae Larvae, in Roman religion Larvae: see lemures. were selected for continued rearing and water was changed every 8 h. Observation Larval development was observed microscopically every hour until the epipodial tentacle ten·ta·cle n. An elongated, flexible, unsegmented extension, as one of those surrounding the mouth or oral cavity of the squid, used for feeling, grasping, or locomotion. stage. Development rate of hatch-out, formation of larval retractor muscle, 90 degree torsion and formation of epipodial tentacle were recorded. Data Analysis The relationship of rate (t) of larval development and water temperature was 1/t = AT + B provides the basis for BZP calculation. RESULTS Experiments were repeated three times and data is showed in Table 1. The BZP was calculated at water temperatures of 16[degrees]C, 20[degrees]C and 22[degrees]C. The average BZP was 6.22[degrees]C (Table 2). DISCUSSION BZP provides the day/hour when larvae are best ready for washing, selection, and settling and is necessary, therefore, for the effective handling of fertilized fer·til·ize v. fer·til·ized, fer·til·iz·ing, fer·til·iz·es v.tr. 1. To cause the fertilization of (an ovum, for example). 2. eggs and larvae in abalone seed production. It also provides a means of obtaining synchronously developed material for this species and presumably pre·sum·a·ble adj. That can be presumed or taken for granted; reasonable as a supposition: presumable causes of the disaster. others, for developmental, physiologic, ecologic and biochemical investigations. BZP varies among species, depending on specific geographical location (Table 3). Moreover, the same species in different geographical locations, also has different BZP, hence H. discus hannai of Japan is 7.6[degrees]C and H. discus hannai of China is 4.2[degrees]C (Zhao 1999). In this experiment, abalone larvae were reared at different temperatures. From the equation of the relationship between water temperature and time for larval development, we know that the larval growth rate shows large discrepancies at different temperatures. Lower water temperature leads to slower development rate and higher mortality. Water temperature is an important factor in many stages of larval development (Seki & Kan-no 1977). In this study, reared larva larva, in zoology larva, independent, immature animal that undergoes a profound change, or metamorphosis, to assume the typical adult form. Larvae occur in almost all of the animal phyla; because most are tiny or microscopic, they are rarely seen. were reared at a water temperatures of 13[degrees]C and 14[degrees]C, but the larval mortality was so high that the expected result was not reached. A water temperature of 22[degrees]C is optimum for larval development and, therefore, to reduce mortality and improve larval quality, reared larvae should be transferred as soon as possible to high temperature.
TABLE 1.
Developmental rate of hybrid larvae of Pacific abalone at water
temperature 16, 20, 22[degrees]C.
Time of Larval Development (h)
Larval First
Hatch- Reactor Torsion Epipodial
Group [degrees]C Out Muscle (90[degrees]) Tentacle
1 16 17.6 30.9 44.4 87.1
20 11.8 19.4 31.5 62.5
22 10.4 19.3 27.4 54.8
2 16 17.7 30.8 44.4 87.1
20 11.8 20.2 31.5 65.5
22 10.7 19.8 27.4 54.8
3 16 17.8 31.4 44.4 87.1
20 12.5 20.0 31.5 64.5
22 11.5 19.2 27.4 54.8
TABLE 2.
Relationship between water temperature and time on the formation
of the fourth larval developmental stage (1/time) and BZP of
hybrid abalone.
Larval Development Stage Equation of Relationship BZP
Hatchout 1/t = 0.00604T - 0.0395 6.54
Larval retractor muscle 1/t = 0.00340T - 0.0211 6.21
Torsion(90-degree) 1/t = 0.00232T - 0.0146 6.29
Epipodial tentacles 1/t = 0.00113T - 0.0066 5.84
Average 6.22
t = hours, T = [degrees]C
TABLE 3.
The biological zero degree of some abalones.
Biological Minimum
Species Zero ([degrees]C) References
H. discus hannai 7.6 Seki and Kan-no (1977)
H. gigantea 9.0 Seki and Kan-no (1977)
H. rufescens 8.5 Seki and Kan-no (1977)
H. fulgens 9.9 Leighton (1974)
H. discus 8.5 Hahn (1989c)
H. asinina 15.0 Saowapa (2001)
Hybrid [F.sub.1] 6.22 The present study
LITERATURE CITIED cit·ied adj. Having a city or cities. Ebert, E. E. & J. L. Houk. 1984. Elements and innovation in the cultivation of red abalone, Huliotis rufescens. Aquaculture 39:375-392. Hahn, K. O. 1989. Larval development of abalone. In: K. O. Hahn, editor. Handbook of culture of abalone and other marine gastropods. Boca Raton: CRC (Cyclical Redundancy Checking) An error checking technique used to ensure the accuracy of transmitting digital data. The transmitted messages are divided into predetermined lengths which, used as dividends, are divided by a fixed divisor. Press. pp. 71-98. Sawateerap, S., E. S. Upatham & M. Kruatrachue. 2001. Larval development in Haliotis asinine Linnaeus. J. Shellfish Res. 20:593-602. Seki, T. & H. Kan-no. 1977. Synchronized control of early life in the abalone, Haliotis discus hannai Ino, Haliotidea. Gastropoda. Bull. Tohoku Reg. Fish. Res. Lab. 38:143-153. Zhao, H. 1999. The culture of the abalone. Shenyang Press. (in Chinese) Dalian Aquatic Products Research Institute, Dalian, 116000 China |
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