• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.3
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• pp.287-295
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• 2013

The growth, respiration, ingestion, and ecological efficiencies of Hexagrammos otakii larvae and juveniles reared on different diets and temperatures were estimated. A factorial experiment using two diets [non-enriched hatched Artemia nauplii (NEA) and enriched Artemia nauplii (EA)] crossed with two temperatures [natural seawater temperature (NT, $5.1-8.5^{\circ}C$) and heated seawater (HT, $13{\pm}0.5^{\circ}C$)] was conducted to investigate growth and energy budgets of Hexagrammos otakii larvae and juveniles. The energy used by larvae and juveniles for 6 weeks was calculated using data on ingestion, growth, respiration, excretion, and egestion. In the NT trials, the energy used for growth by larvae and juveniles was 0.121 and 0.129 Kcal in the NEA and EA treatments, respectively. Assimilation efficiency at NT were 78.0% and 80.2% in the NEA and EA trials, respectively. Gross growth efficiency ($K_1$) were 60.5% and 62.3% and net growth efficiency ($K_2$) was 77.56% and 77.71% in the NEA and EA trials, respectively. In the HT trials, the energy used for growth by juveniles was 0.189 and 0.212 Kcal in the NEA and EA trials, respectively. Assimilation efficiency at HT was 86.4% and 95.1% in the NEA and EA trials, respectively. Values of $K_1$ and $K_2$ at HT were 69.5% and 80.43%, respectively, in the NEA trials, and 73.9% and 77.66%, respectively, in the EA trials. These results suggest that enriched Artemia nauplii and higher temperatures ($13{\pm}0.5^{\circ}C$) are effective for rearing larvae and juveniles of H. otakii.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.1
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• pp.21-28
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• 2007

The bioaccumulation of Pb and Cd dissolved in seawater was assessed measuring the concentrations recorded within blue mussel (Mytilus edulis) and oliver flounder (Paralichthys olivaceus) after two weeks exposure period. The Pb and Cd concentration within the whole body of two testing organisms increased according to the exposure concentrations, and the such tendency was clear specially from the mussel. Maximum metal concentration reached $5,260({\pm}70)\;{\mu}g/g$ for Pb reared under 5.0 mg/L Pb, $1,040({\pm}40)\;{\mu}g/g$ for Cd reared under 1.0 mg/L Cd in the mussel, and indicated that the bioaccumulation of Pb and Cd was directly related to the rearing medium concentrations. Bioconcentration factors (BCF) reached very high values for Pb (maximum value: $12,100{\pm}1,400$) in the mussel reared under lowest Pb concentration (0.01 mg/L). The BCF value for Cd in the mussel were also far higher at exposure to low Cd concentration than high Cd concentration. At higher external concentrations, the BCF for Cd and Pb declined. This demonstrated the ability of two testing organisms to rapidly uptake heavy metals particularly when exposed to low external concentration. The mean Pb concentration was slightly higher in the gill of mussel than in the digestive gland, while Cd showed a higher level in the digestive gland than in the gill.

• Fisheries and Aquatic Sciences
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• v.27 no.3
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• pp.180-194
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• 2024

Mass mortalities of mud crab Scylla spp. larvae due to pathogenic Vibrio spp. outbreaks have frequently occurred in hatcheries. To overcome this problem, probiotics containing Bacillus subtilis bacteria are applied to inhibit pathogenic ones. We tested different doses of probiotic-containing B. subtilis (10⁸ CFU/g) on the Scylla tranquebarica larvae and investigated the microbiota population, including Vibrio. Water quality, larvae development, and crablet production were also monitored. The recently hatched larvae were grown in twelve conical fiber tanks filled with 200 L sterile seawater, with a salinity of 30 ppt at a stocking density of 80 ind/L. Four different doses of probiotics were applied in the larvae rearing, namely, A = 2.5 mg/L, B = 5 mg/L, C = 7.5 mg/L, and D = 0 mg/L, with three replicates. Next-generation sequencing analysis was used to obtain the abundance of microbes in the whole body of megalopa and the water media for larvae rearing after applying probiotics. Sixteen Raw Deoxyribonucleic Acid samples (eight from a whole body of megalopa extraction from four treatments of probiotics defined as A, B, C, D, and eight from water media extraction from four treatments of probiotic defined as E, F, G, H) were prepared. Then, they were sent to the Genetics Science Laboratory for NGS analysis. Ammonia, nitrite, total organic matter (TOM), larvae, and crablet production were monitored. Based on the Next-generation sequencing analysis data, the Vibrio spp. decreased significantly (p < 0.05) than control test (D) in megalopa-applied probiotics at the doses of 2.5 mg/L (A) and 7.5 mg/L (C) and in the water media for megalopa rearing treated with probiotics at the dosage of 5.0 mg/L (F). Ammonia in the zoea stage in B treatment and TOM in the zoea and megalopa stage in B and C treatments were decreased significantly (p < 0.05). It impacts the higher number of zoea survival in treatments B and C. Finally, it results in a significantly high crablet production in treatments B and C. Therefore, the dosage of 5 mg/L to 7.5 mg/L improves crablet S. tranquebarica production significantly.

• Korean Journal of Veterinary Research
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• v.43 no.3
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• pp.449-456
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• 2003

The VP2 gene of aquatic birnavirus, Korean isolate (GC-1) was cloned and expressed using the baculovirus expression system. The VP2 gene and VP2 partial gene, which contained a neutralizing epitope, were constructed for recombinant transfer vectors, for baculovirus expression. The expressed recombinant proteins were confirmed by indirect immuno fluorescence antibody (IFA), SDS-PAGE and Western blot. The level of expression was checked at regular time using IFA and Western blot. To measure the neutralizing activity of recombinant proteins against GC-1 strain, the antisera against recombinant proteins were produced by using guinea pigs. The result showed that the antisera neutralized the GC-1 strain. However, the neutralizing titer was higher in antisera against the VP2 gene expressed recombinant protein than that of VP2 partial gene recombinant protein.

• Journal of Microbiology and Biotechnology
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• v.16 no.8
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• pp.1248-1254
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• 2006

The effect of Spirulina platens is and probiotics as feed additives on the growth of the shrimp Fenneropenaeus chinensis was investigated in comparison with a control. The shrimp were cultured in rearing tanks in a seawater pond for 35 days from September 1, 2004. As regards the water quality, the probiotic treatment (T2, commercial diet and 3% probiotics) produced a lower TDN (total dissolved nitrogen) and TDP (total dissolved phosphorus), making it effective in water quality improvement. Nonetheless, the phytoplankton flora succeeded from diatoms to cyanobacteria, regardless of the feed additives. Treatment T3, including 3% S. platensis, produced the highest mean body weight, which was 39% higher than that for all the other treatments (P<0.05). Accordingly, it was found that the use of Spirulina and probiotics as feed additives increased the shrimp body weight and improved the water quality, respectively.

• Development and Reproduction
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• v.25 no.3
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• pp.157-171
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• 2021

To determine whether the reproductive processes of sea bass, Lateolabrax japonicus, proceed normally after transportation from an outdoor net-cage into indoor tanks, we examined changes in the gonadosomatic index (GSI), histological gonadal tissue, and plasma levels of sex hormones (testosterone and estradiol-17ß) during their annual reproductive cycle. We also measured maturation and spawning across two sea water salinity levels (full and low salinity). Fecundity was estimated by the relationship between egg number and body size in female sea bass. Monthly changes in the GSI, histological gonadal tissues, and oocyte size showed both male and female sea bass reach final maturation in January and February, respectively, indicating that the spermiation of males occurs earlier than the spawning of females. The histological results indicated that the sea bass is a multiple spawner, similar to many marine teleosts, exhibiting group-synchronous oocyte development. Female maturation and spawning were enhanced in lower salinity seawater (29.6-31.0 psu) compared to that of normal salinity (34.5-35.1 psu). These results confirm that sea bass reproduction can occur successfully in captivity and imply that fertilized eggs can be collected from February to March. Additionally, our results show that lower salinity enhances oocyte maturation and spawning of female sea bass.

• Journal of fish pathology
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• v.10 no.2
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• pp.165-176
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• 1997

Water samples collected from marine fish culture system in Korea were compared for their capability to reduce the infectivity titers of HRV (rhabdovirus olivaceus), FBV(flounder birnavirus) and RVS(retrovirus of salmonid). In addition, interaction between viruses and microorganisms present in the rearing seawater was examined. The titer of HRV and RVS were reduced at $15^{\circ}C$ to less than detectable limits within 3 to 5 days using untreated samples of seawater. No reduction of infectivity was noted in bacteria-free water treated by filtration or autoclaving. Bacteria (Pseudomonas and Vibrio sp.) isolated from the water collected from a flounder culture system showed the inactivation activity of HRV.

• Journal of fish pathology
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• v.12 no.1
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• pp.32-41
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• 1999

Ozonization for rearing seawater in land-based culture system has recently been utilized for disinfection of pathogenic microorganisms and improvement of water quality. This study was conducted to examine the effects of total residual oxidants (TRO) in ozone-treated seawater on survival, blood parameters, osmolality and oxygen consumption, and gill tissue of the flounder. Paralichthys olivaceus. Experiments were carried out with the starved flounder of 12~19 cm in total length at $20^{\circ}C$. The 48-hr and 96-hr $LC_{50}$ for the flounder amounts to 26.4 ppb and 22.3 ppb, respectively. With increase of TRO concentration from 24 to 39 ppb, the values of hematocrit, hemoglobin concentration, red blood cell count and osmolality of the flounder with respect to exposure time were significantly elevated, however, the oxygen consumption rates decreased. In the case of the fish exposed to 13 ppb for 96 hrs, blood glucose increased with an elapse of exposure time, while survival rate was 100%. Death apparently resulted by massive destruction of gill lamellar epithelium, severe osmotic imbalance and the lack of oxygen uptake. The results of this experiment indicated that to protect aquaculture organisms, the ozone-treated seawater should not contain any residual oxidants, and that relatively long-term exposure to TRO of low concentration can impact on survival and physiological conditions of the flounder.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.6
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• pp.595-600
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• 2002

Comparison of blood properties in juvenile black seabream (Acanthopans schlegeli) between transfer from seawater to freshwater (sFW) and transfer from freshwater to seawater (fSW) were investigated for 60 days. Plasma cortisol levels in sFW were significantly increased from 34.2 $\pm$ 28.6 ng/mL at the beginning to 365.6 $\pm$ 136.0 ng/mL at 3 hours, and decreased to the beginning level at 24 hours. However, in fSW, no significant differences in the cortisol levels were recognized throughout experimental period. No significant difference was found in the glucose levels between sFW and fSW. The transfer from seawater to freshwater of juvenile black seabream resulted in reduced $Na^{+}\;and\; Cl^{-}$ concentrations for 24 hours (decreasing from 165.3 $\pm$ 2.5, 146.0$\pm$ 2.2 to 118.3 $\pm$ 12.3, 78.0$\pm$ 7.0 mEq/L, respectively), but these were completely recovered the beginning levels at 30 days. Total protein and AST showed no significant differences between the two rearing conditions, while ALT was markedly elevated at 3 hour in sFW and at 24 hours in fSW. Ht in sFW was increased from 18.5 $\pm$ $0.6\%$ at the beginning to 25.3 $\pm$ $4.0\%$ at 12 hours, and was decreased to the beginning level at 24 hours. Ht, RBC and Hb in fSW were also significantly higher at 12 hours, but recovered to their initial levels at 24 hours. All fish were dead until 50 days in sFW while survival rate in fSW was $85\%$ at the end of experiment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.5
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• pp.465-472
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• 2001

The effects of water level reduction in rearing tank and fish transference during fish selection process on the stress response (hematological factors, cortisol, glucose, lactic acid and osmolality) of tank-reared olive flounder Paralichthys olivaceus of large (FL), small (FS) and Japanese croaker, Nibea japonica (JC) were examined in running seawater culture system. The water level of rearing unit was lowered from 33 cm to 8 cm in the course of 2 minutes in the water level reduction experiment. The fish were removed from rearing tank (12 ton) to 450 L tank in 30 seconds after capture in the fish transference experiment, In water level reduction, the hematocrit of FL was significantly increased from $14.6\%$ at beginning to $23.5\%$ after 10 hours, However, it decreased to the value of beginning after 46 hours. Plasma cortisol concentration of FL was the highest concentration (13.7 ng/mL) after 22 hours, but it decreased to 4.0 ng/mL at the end of experiment. Cortisol concentration of FS did not show any significant difference during the experiment. The cortisol concentration of JC were significantly higher at 4 hours (282.3 ng/mL) and 22 hours (350.5 ng/mL), Glucose concentration of JC was the highest (138.0 mg/dL) at 22 hours. Lactic acid concentration was not different between experimental groups. In the fish transference experiment, red blood cell of FL was increased from $1.9\times10^6\;cell/{\mu}\;L\;to\;4.2\times10^6\;cell/{\mu}L$ in 24 hours. Blood hemoglobin of JC were significantly elevated in 24 hours. At 1 hour after transference, plasma cortisol concentrations in both fish species were increased to 95.3 ng/mL in FL and 175.5 ng/mL in JC. Glucose concentration of JC was increased to 132.5 mg/dL at 1 hour, 129.5 mg/dL at 3 hours after transference.