• 한국양식학회지
• /
• 제12권4호
• /
• pp.255-266
• /
• 1999

The early development, growth, and morphological changes of Tiger puffer Takifugu rubripes are described on the basis of a seres of a series of reared specimens. Detailed o수 the early developmental stages are illusrtated withe special reference to morphological transformation. Egg and sperm of puffer fish Takifugu rubripes were obtained from mature adults under natural conditions, ferilized artificially and incubated in the laboratory. The incubation period of fertilizd eggs was 160 to 180 hours at a temperature of $15.1~ 18.0^{\circ}C$. Larvae were fed successively with rotifer, Artemia nauplii and artificial food for 90 days. The mean total length of newly-hatched larvae was about 2.8mm. Mouth opening occurred on the 1- day yolk-sac larvae and initial feeding was observed on th 4-5 days after hatching . The morphological transitions from the larvae to juvenile and juvenile and juvenile to young stages occurred when fish reached about 10mm in total length(about 30 days after hatching) and about 32mm in total length(about 60days after hatching) , respectively. The coefficient of variation in total length distribution increased with growth. Following the appearance of its peak at the size of about 18mm in total length, the coefficient value declined. Many changes in proportion of the body parts to total length were observed at about 9~10mm and 30~33mm in total length, corresponding to the transformations from larvae to juvenile and from juvenile to young, respectively. Also one big morphological change was observed at about 18mm in total length that divide the juvenile stage into two sub-stages.

• 한국어병학회지
• /
• 제17권3호
• /
• pp.199-205
• /
• 2004

우리나라 갑각류의 대표적인 양식종인 대하의 초기생활사 동안의 아질산, 암모니아 및 황화수소에 대한 급성독성 수준을 파악하여 각 발달단계에 따른 독성차이를 검토하였다. 아질산에 대한 대하의 mysis, post larva 및 juvenile기의 96시간 반수치사 농도는 각각 18.4, 32.3 및 39.8 mg/L이었고, 암모니아에 대한 대하의 mysis, post larva 및 juvenile기의 96시간 반수치사 농도는 각각 1.43, 3.45 및 3.35 mg/L이었다. 황화수소에 대한 대하의 mysis, post larva 및 juvenile기의 96시간 반수치사 농도는 각각 13.5, 22.7 및 28.5 $\mu{g}/L$이었다. 이들 오염물질에 대한 독성순위는 황화수소>암모니아>아질산 순으로 나타났다. Post larva에 대한 mysis기의 독성수준은 모든 오염물질에서 1.5배 이상을 나타냈고, juvenile에 대한 mysis기의 독성수준은 2배 이상을 나타내어 가장 큰 차이를 보였다. 한편 juvenile에 대한 post larva기의 독성차이는 1.5배 이하를 나타내어 가장 작은 차이를 보였다.

• Fisheries and Aquatic Sciences
• /
• 제17권1호
• /
• pp.75-84
• /
• 2014

To determine a suitable dietary protein/lipid (CP/CL) ratio in the early juvenile stages of hybrid porgy ($F_1$), female red sea bream (RSB) ${\times}$ male black sea bream, five diets with various CP/CL ratios-60/7, 55/12, 51/17, 46/23, and 41/28-were prepared and provided to juveniles in triplicate. At the smaller juvenile stage, $F_1$, weighing 0.32 g, a significantly higher specific growth rate (SGR) and feed efficiency (FE) were seen with 60/7 and 55/12 diets. However, in RSB weighing 0.26 g, SGR and FE were higher with the 60/7 diet than the other diets at $21^{\circ}C$. At the larger juvenile stage, $F_1$, weighing 3.7 g, there was no significant difference in SGR or FE among the diets, but RSB weighing 4.0 g fed 60/7, 55/12, and 51/17 diets had higher SGR and FE than 46/23 and 41/28 diets at $24^{\circ}C$. Moreover, survival and apparent nutrient retention of $F_1$ at both stages were significantly higher than those in RSB. These results indicate that both $F_1$ and RSB weighing ca. 0.3 g require a higher dietary CP/CL than those weighing ca. 4 g. Additionally, $F_1$ in both trials showed the suitability of a lower dietary CP/CL than RSB, indicating that mass production of $F_1$ juveniles will be more economical than RSB.

• 한국어류학회지
• /
• 제13권1호
• /
• pp.74-84
• /
• 2001

사육 조건하에서 동자개 Pseudobagrus fulvidraco의 발육에 따른 형태 변화 및 상대성장에 대해 검토하여 발육단계를 구분한 결과를 요약하면 다음과 같다. 1. 수정난은 난경 2.04${\pm}$0.07 mm (n = 100)의 비교적 큰 구형의 분리되는 침성부착난으로서 수조의 바닥 및 기질에 강하게 부착한다. 2. 부화자어는 전장 약 4.92${\pm}$0.33 mm로, 부화 후 1일에 입이 열리고, 부화 2일후에는 항문이 열리고, 부화 후 3일에 섭이를 시작하여 후기자어기에, 부화 후 30일경에 전장 약 32 mm에 유어기에 이른다. 3. 전장에 대한 각 부위의 상대성장에 굴곡점은 전장 7~8 mm, 17~32 mm, 32 mm 전후에 집중적으로 나타났다. 4. 외부형태의 변화 및 상대성장의 굴곡점이 나타나는 어체 크기 등을 종합적으로 고려하여 자어기에서 유어기까지의 발육단계를 구분하면, 자어기는 전장 17 mm 이하, 치어기는 17~32 mm, 유어기는 32 mm 이상으로 사료된다. 상대성장의 측정결과 전기자어기에는 머리부분에 관련된 형질, 후기자어기 이후에는 운동능력에 관련된 형질의 우성장이 뚜렷하였다.

• 한국패류학회지
• /
• 제27권2호
• /
• pp.91-97
• /
• 2011

This study examines the morphological features of larval and postlarval shells of the paedomorphic bivalve Crenella decussata Montagu, 1808 from the Sea of Japan. During the early morphogenesis of the shell of C. decussata the following characteristics appear: prodissoconch I -the anterior and posterior provincular teeth, a broad primary ligament pit located on the chondrophore; nepioconch - the anterior and posterior juvenile teeth,primary lateral teeth, fine commarginal and radial sculpture. Larvae of C. decussata distinctly differ from other mytilid larvae by a D-shaped shell, absence of umbo, astraight hinge margin, and homogeneous fine-grained sculpture without co-marginal lines of growth. These shell characters indicate lecithotrophic development of this species. Some morphostructures are revealed which might be used in crenellin taxonomy.

• ALGAE
• /
• 제38권2호
• /
• pp.151-157
• /
• 2023

Grateloupia turuturu is a red alga with a flat but firm slippery thallus. Throughout its lifetime, this alga experiences a wide range of environmental stresses in the intertidal rocky shores. The aim of this study is to investigate the effect of salinity and irradiance on the early developmental stages of G. turuturu tetrasporophytes. The released carpospores were cultivated at different salinities (S = 15, 25, and 35) and irradiances (50, 100, and 200 μmol photons m^-2 s^-1). Germination of carpospores and development of juvenile tetrasporophytes were observed every 5 days and recorded by a digital camera. Discoid crusts were formed at all conditions within 5 days. The discoid crusts at 200 μmol photons m^-2 s^-1 died within 20 days regardless the salinity. The discoid crusts at S = 35 also died at all irradiance conditions within 25 days. Except for those at S = 35 and 200 μmol photons m^-2 s^-1, the discoid crusts reached about 8,000-9,000 ㎛² by day 20. Regardless of irradiance, the upright thalli formation rate from discoid crusts was 85 and 10% at S = 15 and S = 25, respectively. These results suggest that salinity and irradiance are important factors influencing early developmental stages of G. turuturu.

• 한국양식학회지
• /
• 제12권3호
• /
• pp.185-191
• /
• 1999

A genetic analysis for survival in fry and juvenile stages of masu salmon was described. Data from two year-classes of masu salmon were analyzed to estimate the heritability for survival during the fresh water-rearing period. The overall survival for each year-class during 8 months of freshwater rearing were 17.8 and 11.6%, respectively. Whirling disease virus (WDV) was the main cause of death in all year-classes. Survival data obtained for offspring of 42 sires and 60 dams of masu salmon (two year classes of data) was analyzed. Average survival rates in the observation period ranged 2-87% for 1994; 0-98% for 1995, repectively. In both year-classes, heritabilities for survival derived from the sire components of variance were low(0.13-0.18), except one. Heritabilities derived from the dam components of variance ranged 0.14-0.61, including non-additive genetic and /or common enviromental effects. Correlations between survival in two long-term periods were all positive and medium to high in magnitude(0.345-0.918). Correlations between survival in non-succeeding periods were, in general, low and insignificant. Correlation between long-term survival and growth rate was found in masu salmon. The corresponding correlation in masu salmon was not significantly different from zero. Correlations between sire survival and body weight, length and condition factor of slaughter were not significant, but varied.

• ALGAE
• /
• 제34권2호
• /
• pp.153-162
• /
• 2019

Anthropogenic disturbances, including coastal habitat modification and climate change are threatening the stability of kelp beds, one of the most diverse and productive marine ecosystems. To test the effect of temperature and irradiance on the microscopic gametophyte and juvenile sporophyte stages of the rare kelp, Saccharina angustissima, from Casco Bay, Maine, USA, we carried out two sets of experiments using a temperature gradient table. The first set of experiments combined temperatures between $7-18^{\circ}C$ with irradiance at 20, 40, and $80{\mu}mol\;photons\;m^{-2}\;s^{-1}$. The second set combined temperatures of $3-13^{\circ}C$ with irradiance of 10, 100, and $200{\mu}mol\;photons\;m^{-2}\;s^{-1}$. Over two separate 4-week trials, in 2014 and again in 2015, we monitored gametogenesis, the early growth stages of the gametophytes, and early sporophyte development of this kelp. Gametophytes grew best at temperatures of $8-13^{\circ}C$ at the lowest irradiance of $10-{\mu}mol\;photons\;m^{-2}\;s^{-1}$. Light had a significant effect on both male and female gametophyte growth only at the higher temperatures. Temperatures of $8-15^{\circ}C$ and irradiance levels of $10-100{\mu}mol\;photons\;m^{-2}\;s^{-1}$ were conditions for the highest sporophyte growth. Sporophyte and male gametophyte growth was reduced at both temperature extremes-the hottest and coldest temperatures tested. S. angustissima is a unique kelp species known only from a very narrow geographic region along the coast of Maine, USA. The coupling of global warming with high light intensity effects might pose stress on the early life-history stages of this kelp, although, as an intertidal species, it could also be better adapted to temperature and light extremes than its subtidal counterpart, Saccharina latissima.

• 한국패류학회지
• /
• 제32권2호
• /
• pp.133-139
• /
• 2016

The incubation time required for hatching of O. ocellatus were investigated through the processes of egg and embryonic developments by the dissecting microscopic and visual observations. And differences in ecological characteristics of the plankton mode of life or the benthic mode of life according to total numbers of the suckers on each short arm of the hatched juvenile larvae of O. ocellatus were studied by comparisons with other octopodidae species. Compared with the recent a few results reported by other researchers associated with the incubation time required for hatching by female adult mother of O. minor (73-90 days after spawning at $20.9-21.5^{\circ}C$ ranges), in this study, the incubation time required for hatching by female adult mother of O. ocellatus was 56-57 days after spawning at $11.0-20.4^{\circ}C$. Therefore, the incubation time required for hatching by female adult mother varied with Octopodidae species. In this studies, each ovarian egg laid by a female was connected to an egg string attaching to the surface of the wall or bottom of vacunt shell of Rapana venosa. Egg and embryonic developments of this species were studied in the indoor aquaria, in the specific gravity ranging 1.024-1.025. the hatched juvenile of O. ocellatus is 10.3 mm in the mean total length and 4.5 mm in mantle length, and each of its short arms has 18-20 suckers. The just hatched juvenile larvae of O. ocellatus enter the benthic mode of life (benthic larval stage) after hatching. In particular, regarding differences in ecological characteristics of the mode of life according to total numbers of the suckers, O. vulgaris may not need to have many suckers because they enter the planktonic mode of life after hatching, however O. ocellatus may need to have many suckers, because they should adapt to the benthic mode of life. And also the just hatched juvenile larvae of O. minor (bearing many suckers more than O. ocellatus) enter the benthic mode of life (benthic larval stage) after hatching. Therefore, the total number of the suckers on each short arm of the hatched juvenile larvae can be used for determining whether an octopus species has planktonic larval stages or benthic larval stage (benthic mode of life). In particular, The intracohort cannibalism phenomena appeared at the hatched juvenile larval stage because the larval stage of O. ocellatus and O. minor enter into the benthic larval stage in the early stage, unlike entering into the plaktonic larval stage in other Octopus species such as O. vulgaris: at this time, the early hatched larvae fed the late hatched larvae (they are the same species and almost same ages). Therefore, the intracohort cannibalism pheneomena occur in the just hatched juvenile stage of only O. ocellatus and O. minor.

• 생명과학회지
• /
• 제12권4호
• /
• pp.407-415
• /
• 2002

동남참게 초기유생에 대한 다양한 먹이를 공급하여 먹이에 따른 어린게까지 소요 일수와 생존율을 수온 22$\pm$1$^{\circ}C$ 및 염분 24$\pm$1% 상태에서 조사한 결과는 다음과 같다. 무투여구에서는 5일만에 조에아 I~2기 상태에서 모두 사멸하였고, 살아있지 않은 먹이인 삶은 계란 난황 건조분말, 삶은 대두 건조분말, 인공배합사료 분말, 삶은 수수 건조분말, 새우 생육세편, 담치 외투막 생육세편를 공급한 실험구에세는 7~9일 까지 생존하였으며 유생의 형태는 조에아 2~3기 상태였다. 식물성 단세포인 C. ellipsoid, S. costatum, 및 C. gracilis를 각각 단독으로 공급하였을 때 각각 10, 18과 19일 까지 생존하였고, 유생의 형태는 조에아 3~5기 상태였고, 동물성 플랑크톤인 Artemia nauplii and rotifer를 공급하였을 때 각각 24일과 25일만에 치게로 변태하였고 이때의 생존율은 각각 43%와 25%이었다. 한편, 조류와 동물성 먹이를 혼합하여 공급하였을 때 단독공급시보다 모든 실험구에서 생존율이 높게 나타났고, 치게까지 도달하였다. 그 중에서 가장 효과가 좋았던 실험구는 규조류인 C. gracilis, Artemia nauplii and rotifer를 혼합공급한 실험구 이었고, 22일만에 치게로 변태하였으며 이때 생존율은 73%였다.