• Fisheries and Aquatic Sciences
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• v.26 no.5
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• pp.355-365
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• 2023

The Pacific abalone, Haliotis discus hannai, is a highly valued and industrially important aquaculture species with growing demands of the expanding abalone aquaculture industry. To explore the feasibility of using the brown alga, Sargassum horneri, as a potential substitute for abalone feed, it is important to identify the feed preference and attractant effect of S. horneri on Pacific abalone. Our experiments indicated that the feeding-associated movement of abalone could be detected using a video tracking system under indirect illumination with dim red light. To further analyze the attraction potentials of various test materials, preference analysis was performed using Avicel-coated glass plates with ground powders of various seaweeds (e.g., S. horneri, Saccharina japonica, and Undaria pinnatifida) and commercial abalone feed, together with coffee waste. Heat map analysis indicated greater attraction by the kelp S. japonica than by S. horneri and commercial feed, which showed similar preference levels. Feeding preference based on the area of Avicel eaten by abalone showed a significant preference for U. pinnatifida over S. horneri (feeding area: 68.6 ± 20.1% vs. 37.5 ± 22.4%, p < 0.05). Additionally, the feeding area was significantly greater for plates with S. japonica than for plates with S. horneri (44.0 ± 16.6% vs. 22.6 ± 15.4%, p < 0.05). There was no significant difference in feeding area between commercial feed and S. horneri (31.7 ± 11.6% vs. 31.6 ± 20.2%, p > 0.05). The methanol extracts attracted abalone in the following order: U. pinnatifida > S. horneri > S. japonica > commercial feed > coffee waste. To determine the attractive effects of the components of methanol extracts, mixtures of methanol extracts of commercial feed with increasing amounts of S. horneri were examined. The results showed a significant increase in feeding preference upon addition of S. horneri up to 50% and 75%, suggesting its potential for use as an appetite-enhancing feed additive. This study identified conditions that can be successfully used to monitor the movement of Pacific abalone; the results of preference analysis confirmed that abalone exhibited similar attraction and feeding preference for S. horneri, compared with commercial feed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.5
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• pp.560-564
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• 2011

Two feeding experiments were conducted to investigate the effects of dietary inclusion of genetically modified (GM) soybean and corn on the growth performance, feed utilization and body composition of juvenile abalone Haliotis discus hannai. Four isonitrogenous (31% crude protein) and isolipidic (6% crude lipid) diets (designated as nGM-soya, GM-soya, nGM-corn and GM-corn) were formulated to contain 20% non-GM (nGM) and GM soya and corn. Fifty juvenile abalone (initial body weight, 2.0 g) were distributed in each 50 L tank in a flow-through system. Each experimental diet was fed to duplicate groups of abalone to satiation once a day for 10 weeks. No effects of GM feedstuffs on survival were observed. Dietary inclusion of GM feedstuffs did not affect either growth performance or feed utilization of abalone. Body composition was not altered by the inclusion of GM feedstuffs. These results indicate that dietary inclusion of GM soybean and corn could have no effect on the growth performance and body composition of juvenile abalone. Further studies to investigate the effects of GM feedstuffs on transgenic fragment residues in ambient environments and in animals are necessary for the safe use of such ingredients in aquaculture.

• Development and Reproduction
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• v.15 no.4
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• pp.301-308
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• 2011

The tolerance evaluation for abalone Haliotis discus hannai embryos was performed using different concentrations of cryoprotective agents (CPAs): dimethyl sulfoxide, ethylene glycol and propylene glycol added to 0.2 M sucrose, respectively. 4-cell, trochophore and veliger were exposed in each CPA with different concentration for 10, 20 and 30 minutes of immersion time. Developmental rates were increased with decreased concentration of every CPA and decreased immersion time, and differed from types of CPA. Developmental rates of veliger in all the CPAs were higher than those of 4-cell and trochophore. The developmental rates and larval activity indices in ethylene glycol were comparatively higher than those in other CPAs and the effective CPA and its concentration for the cryopreservation of the abalone embryos was suggested as 2.0 M ethylene glycol with equilibration time of 30 minutes.

• The Korean Journal of Malacology
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• v.30 no.4
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• pp.353-361
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• 2014

In order to investigate the effects of copper alloy on abalone physiology, we studied survival rate, respiration, excretion rate, and heavy metal accumulation in each organ of adults and spats. The survival rate of spats and adults showed 27-60% and 63-83% respectively, higher survival rate in adults. In particular, 100% of copper panel led to lowest survival rate and there was no sharp distinction according to copper alloy composition. The respiration rate and excretion rate of ammonia nitrogen was $1.81mgO_2/g$ D.W./h and 0.43 mg $NH_4-N/g$ D.W./h respectively at 100% of copper panel. In other words, there was a high significant difference at the level, but no significant difference at other test levels (P < 0.05). The atomic ratio (0: N) hit the lowest at the 100% of copper panel showing 3.79 and no significant differences were seen among other test groups with 6.57-7.18 of a very low range. This means that the species might have undergone nutritional stress. In case of copper accumulation, the 100% copper panel group showed the highest level in hepatopancreas and muscle showing 6.91 mg/kg and 1.60 mg/kg respectively but the rest of groups showed similar levels. Zinc accumulation raised at Cu-Zn alloy panel had high significance showing 18.50 mg/kg and 1.10 mg/kg in hepatopancreas and muscle respectively (P < 0.05). To sum up, a cage net made of 100% pure copper is expected to have a negative effect on abalone in light of survival rate, heavy metal accumulation, and atomic ratio (0: N). Moreover, given that the substratum used for the high adhesive species and nutritious stress that is represented through the atomic ratio need to be considered, the copper alloy net is thought not to be suitable for abalone aquaculture.

• Fisheries and Aquatic Sciences
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• v.20 no.7
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• pp.9.1-9.13
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• 2017

Background: Metal-responsive transcription factor-1 (MTF-1) is a key transcriptional regulator playing crucial roles in metal homeostasis and cellular adaptation to diverse oxidative stresses. In order to understand cellular pathways associated with metal regulation and stress responses in Pacific abalone (Haliotis discus hannai), this study was aimed to isolate the genetic determinant of abalone MTF-1 and to examine its expression characteristics under basal and experimentally stimulated conditions. Results: The abalone MTF-1 shared conserved features in zinc-finger DNA binding domain with its orthologs; however, it represented a non-conservative shape in presumed transactivation domain region with the lack of typical motifs for nuclear export signal (NES) and Cys-cluster. Abalone MTF-1 promoter exhibited various transcription factor binding motifs that would be potentially related with metal regulation, stress responses, and development. The highest messenger RNA (mRNA) expression level of MTF-1 was observed in the testes, and MTF-1 transcripts were detected during the entire period of embryonic and early ontogenic developments. Abalone MTF-1 was found to be Cd inducible and highly modulated by heat shock treatment. Conclusion: Abalone MTF-1 possesses a non-consensus structure of activation domains and represents distinct features for its activation mechanism in response to metal overload and heat stress. The activation mechanism of abalone MTF-1 might include both indirect zinc sensing and direct de novo synthesis of transcripts. Taken together, results from this study could be a useful basis for future researches on stress physiology of this abalone species, particularly with regard to heavy metal detoxification and thermal adaptation.

• Journal of Marine Life Science
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• v.2 no.2
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• pp.39-48
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• 2017

This study was carried out to investigate the stress response of pacific abalone exposed to various water temperatures (4, 6, 8, and 10℃) and salinities (26, 30, and 34 psu) for 7 days, with the aim of finding optimum conditions for long-distance ocean transport of pacific abalone. At the end of the experiments, the survival rate was ranged from 98.7~100% at 8 and 10℃ but dropped to 25~55% at 4℃ in all salinity levels. The levels of SOD and glutathione in hemolymph were significantly higher at 4 and 6℃ than the control in all salinity groups, indicating that these temperatures induce severe stress in pacific abalone. It was found that THC was lowest at 6℃ in the 26 psu groups. The study showed that the hemocyte of pacific abalone populations mostly consisted of blast-like cells and hyalinocytes with the ratio of hyalinocytes being significantly lower at 4 and 6℃ than the other temperatures in the 26 psu groups. Percentages of apoptotic cells and necrotic cells were higher in the 26 psu group and 4 and 6℃ temperature groups. These results explicit that pacific abalone was exposed to greater stress at 26 psu and at 4 and 6℃ but experienced no significant higher stress at 30 and 34 psu and 8 and 10℃. It was therefore concluded that the optimum temperature and salinity for the long distance transport of pacific abalone range from 8~10℃ and 30~34 psu, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.6
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• pp.601-605
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• 2003

This study investigated the effect of dietary pigment sources on growth and shell color of juvenile abalone(Haliotis discus hannai). Three replicate groups of the abalone (average weight 173 mg) were fed diets containing various pigment sources such as Porphyra powder, Spirulina, yeast astaxanthin, and paprika extract for 16 weeks. Survival and weight gain were not affected by dietary pigment sources (P>0.05). Shell color of abalone fed diets containing Porphyra powder and Spirulina approached the yellow-red and orange, colors similar to wild abalone. However, shell color of abalone fed the diets containing yeast astaxanthin and paprika extract were similar to the bright green control group. These results should be useful for changing the shell color of abalone in aquaculture.

• Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.339-345
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• 2011

Although culture techniques for the abalone Haliotis discus hannai are well known, mass culture of the benthic microalgae that are essential live food for the abalone larvae is still not practiced. This study was conducted to identify the microalgal species suitable for the growth of early larvae of H. discus hannai. The growth and attachment rates of 31 microalgal species were examined. Acrylic plates were used as the substrate. Among the 31 microalgal species, nine showing high growth and attachment rates were selected and tested for their dietary values via factors including settlement, metamorphosis, and survival rates of abalone larvae. Tetraselmis hazeni and Rhaphoneis sp. induced the highest settlement rate (65-69%) in abalone larvae. The metamorphosis rate was highest (57%) in larvae fed Rhaphoneis sp. and was also significantly higher in larvae fed Oscillatoria splendida (29%) and T. hazeni (22%) than in those fed other species. The highest survival rate of the larvae during the 15 days after metamorphosis was 67% in those fed Rhaphoneis sp., followed by T. hazeni (42%) and O. splendida (35%). In conclusion, Rhaphoneis sp. is the most suitable diatom for use as a live food for the culture of early larvae of H. discus hannai. In addition, T. hazeni and O. splendida are also potential species to be further developed and utilized in larval culture.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.44-44
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• 2003

Gene expression in five tissues of the abalone (Haliotis discus hannai) was investigated using an expressed sequence tag (EST) analysis. Randomly selected clones were obtained from cDNA libraries constructed with gill (GI), digestive diverticula(DD), hepatopancreas (HP), foot/mucus (FM) and rectangular muscle (RM). Of 1,235 clonesanalyzed (288 clones for GI, DD, HP each,166 for FM, and 205 for RM), 741 (60.0%) clones in total turned out to share significant similarity with the sequences from NCBI GenBank (less than 10/sup -3/ of e-values), 423 sequences showed poor similarity (> 10/sup -3/), and 71 sequences didn't match with any sequences in GenBank. The percent unique sequence (singleton) was ranged from 56.1% (RM) to 74.7% (FM) among libraries. On the other hand, overall percent singleton was 55.3% when all the ESTs from five libraries were assembled into contigs. Analysis of the organisms represented by the best hit for each EST (e-values < 10/sup -3/) showed that 23.8% matched with mammalian entries, 24.0% with mollusks, 14.4% with insects, 11.6% with fish and 26.2% with others. The expressed patterns differed among the tissues when judged by the categorization of the sequences from each library into 10 broad functional classes. In all the libraries, the class I (no hit o. poor similarity) was the largest category with an average of 40.1%. This largest class was followed by class V (general metabolisms) in DD (21.9%), GI (14.6%) and HP (16.7%), while the 'cell structure and motility'(class VI) was the second largest class in remaining two libraries (31.2% for RM and 9.6% for FM). The class IX (cell division and proliferation) was the smallest class in all the libraries (less than 3%). This report provides the first tissue-specific lists of expressed abalone genes, which could be a fundamental basis for genomics program of abalone species.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.5
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• pp.565-570
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• 2013

Physiological studies on the salinity tolerance with respect to survival rate and body composition changes of the abalone Haliotis discus hannai were conducted by rapidly changing the salinity in an indoor rearing system. The survival rate of the control (35 psu), 30 and 25 psu groups at $15^{\circ}C$ was 100%. The survival rate of the 20 psu group was $35{\pm}5.0%$. Survival rate of the 15 psu group was 0%. At $15^{\circ}C$ and 35, 30, 25, 20, 15 psu, the moisture contents of abalone muscle were $82.1{\pm}0.7$, $82.5{\pm}0.7$, $84.9{\pm}0.5$, $86.9{\pm}0.3$ and $86.6{\pm}0.4%$, respectively. Crude lipid contents were $0.47{\pm}0.03$, $0.47{\pm}0.03$, $0.47{\pm}0.09$, $0.77{\pm}0.09$ and $0.63{\pm}0.03%$, respectively and crude ash contents were $1.30{\pm}0.12$, $1.33{\pm}0.15$, $1.13{\pm}0.23$, $1.87{\pm}0.15$ and $1.40{\pm}0.31%$, respectively. At salinity below 20 psu, these values increased compared with the control. The general components of abalone muscles significantly increased below 20 psu, while amino acid composition showed no significant difference with salinity and water temperature.