橘色海菊蛤人工繁育技术研究

Artificial breeding of Spondylus aurantius

中文关键词: 橘色海菊蛤  人工繁育  胚胎发育  稚贝  附着基

英文关键词: Spondylus aurantius  Artificial breeding  Embryonic development  Juvenile stage  Substrate

中文摘要:

      本研究以野生橘色海菊蛤(Spondylus aurantius)为材料，观察了橘色海菊蛤的亲体催熟、胚胎及稚贝的发育过程，比较了不同温度条件下胚胎发育速度及不同材质和采苗深度对海菊蛤附着效果的影响。结果显示，野生橘色海菊蛤在养殖池经自然催熟后性腺饱满，发育成熟；采用“晾干+流水+高温”刺激获得了橘色海菊蛤优质精卵，并成功完成了受精；受精卵通过不均等卵裂，依次发育为多细胞卵裂期、囊胚、担轮幼虫、D形幼虫、壳顶幼虫、匍匐幼虫和稚贝，累计耗时25~27 d。受精卵在温度为28 ℃和32 ℃时均可发育至稚贝，且在水温为32 ℃时，胚胎各个阶段发育速度均快于28 ℃。室内不同水层采苗结果显示，底层采苗器附着密度要显著高于上层(P<0.05)；不同附着基材质附着密度结果显示，室内采苗阶段黑蝶贝壳附着效果最好，而后依次为海菊蛤壳＞牡蛎壳＞混凝土饼＞黑色遮阳网＞绿色聚乙烯网片。在自然海区养殖30 d后，海菊蛤壳和牡蛎壳附着及生长效果最优。本研究首次成功开展了橘色海菊蛤人工繁育，获得了其胚胎和稚贝发育规律，研究结果可为该物种在南海人工规模化养殖提供支撑。

英文摘要:

      Spondylus aurantius, a member of the Mollusca phylum, Bivalvia class, Pterioida order, and Spondylidae family, is an important economic marine bivalve species that is widely distributed along the warm-water coastal region in Guangdong and Hainan Province in China, and the Philippines. As an important marine commercial bivalve, wild S. aurantius individuals are often captured by local fishermen for their large adductor muscle, which makes delicious seafood, and for their beautiful shells, which are used for displays. According to the China Fishery Statistical Yearbook for 2022, the annual production of cultured mollusks exceeded 15 million tons, with oysters, scallops, and clams accounting for 78.23% of the total aquaculture yield. In southeast coastal provinces, such as Guangdong, Guangxi, and Hainan, the most common cultured mollusks include Hong Kong oysters (Crassostrea hongkongensis), Suminoe oysters (Crassostrea ariakensis), pearl oysters (Pinctada fucata martensii), and noble scallops (Chlamys nobilis). Generally, Hong Kong and Suminoe oysters cannot tolerate high salinity conditions and are often cultured near estuaries; the P. f. martensii industry is rapidly declining because of high mortality rates and nucleus rejection after transplantation in the process of pearl production; and noble scallop rearing, which is primarily practiced in net cages, and a considerable amount of labor is required to clean attachments. Therefore, there is an urgent need to investigate the cultivation of new bivalve species that can adapt to coastal areas with high temperatures and high salinity. Though S. aurantius is traditionally regarded as an edible mollusk, few studies have reported the artificial breeding of this species. In this study, wild adult S. aurantius with shell length of (12.00±1.25) cm and wet body weight of (100.00±5.04) g were selected as the research subjects to artificially ripen mature individuals, observe and compare the development of the embryo and juveniles at different temperatures (28 ℃ and 32 ℃), and study the effects of different substrates and water depths on the adhesion efficiency of juveniles. Our results were as follows: (1) Under artificial conditions, adult S. aurantius gonads could continue to develop and mature, with testes and ovaries filled with milky spermatozoa and orange eggs, respectively; (2) The method of “dry in the shade + flowing water + high temperature” successfully induced spawning and fertilization of S. aurantius; (3) The diameters of fertilized eggs were (130.1±0.3) µm, and the first unequal cleavage was observed 95 min after fertilization. These eggs then developed into multicellular stages (cleavage occurred at approximately 30-min intervals), blastula (after 4–5 h of fertilization), trochophore (after 10–12 h of fertilization), D-shaped larvae (after 25–28 h of fertilization), umbo larvae (after 6–7 d of fertilization), pediveliger (after 14–15 d of fertilization), and juvenile (after 25–27 h of fertilization); (4) Fertilized eggs could develop into the juvenile stage at both 28 ℃ and 32 ℃; however, the survival rates of fertilized eggs under higher temperatures were lower than of those cultured at 28 ℃, although the speed of S. aurantius embryonic development at 32 ℃ was higher than that at lower temperatures; (5) The density of juvenile S. aurantius in deep water (1–1.5 m depth) was evidently higher than that in shallow water (0–0.5 m depth) in an indoor seedling pond (P<0.05); (6) Furthermore, the densities of juvenile S. aurantius were highest on the surfaces of Pinctada margaritifera shells, followed by S. aurantius shells > oyster shells > concrete reels > black shading nets > green polyethylene mesh sheets under indoor conditions, while the densities and growth rate of juvenile S. aurantius attached itself and oyster shells were better after one month culture in the natural coastal area of Wuzhizhou Island, Sanya. In this study, embryonic development in S. aurantius was observed for the first time. Furthermore, the breeding technology of S. aurantius, including the induction of gonadal maturation and spawning, the incubation of fertilized eggs, and the selection of substrates, was established for the first time under artificial conditions, which could contribute to the future large-scale breeding and cultivation of this species.