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ISSN : 1225-3480
To develop new products for aquaculture, which fishermen at South Sea can get high income, after bay scallop was transplanted from Sandong province in China from October 17, 1996 to March 18, 1997 at Duekrang Bay in Janghung gun and Kamak Bay in Y대녀 City on Chollanam province, Sumjin river estuary in Hadong gun and Gejae Bay in Keoje city on Kyongsangnam proince. Temperature was decreased from 20.5<TEX>$^{\circ}C$</TEX> to 5.1<TEX>$^{\circ}C$</TEX> in February and then it was increased to 12.0 in March. Ranges of salinity, DO and Chlorophyll-a were 22.40-34.70 psu, 5.24-9.77 mg/l and 1.27-22.28 <TEX>$\mu\textrm{g}$</TEX>/l, respectively, and low temperature, sudden changes of salinity and low concentration of chlorophyll-a influenced the growth of bay scallop. bay scallop in the rearing period showed the fastest growth from October 17 to November 18 through the every size rages, while it grew slowly or stopped growing from December 18 to March 18. Among 4 transplanted areas, young scallop at Duekrang Bay showed the fastest growth and then Kamak Bay, Gejae Bay, Sumjin estuary in order. The daily growth rate of young scallop in the middle size range (5.70%) was higher than those in large (2.07%) and small (5.49%) size range. The meat weight index showed the highest in December. Survival rates from October to December were high, not related to the size ranges, but survival rate of the small young scallop from January to March was higher than Those of the rest. As the Result, transplanted bay scallop at South Sea was shown to grow by the middle of December (around 1<TEX>$0^{\circ}C$</TEX> temperature).
The histochemical, cytochemical, and immunocytochemical investigations were conducted to find out the cellulase activity in the accessory glands of the digestive system of the oriental land snail Nesiohelix samarangae under the LM, SEM, and TEM. The cellulase activity was shown in the epithelium of th digestive gland by labelling with the immunogold (protein-A gold) particles. The epithelial cells showing the cellulase activity were Type 1 and Type 3 cells out of five types of the epithelial cells of the digestive gland. None of epithelial cells of the mucus gland and the salivary gland and the salivary gland were not labeled with the immunogold particles.
A histochemical and ultrastructural study on the salivary gland of a freshwater snail Radix auricularia coreana was conducted .The epithelial cells of the salivary gland are composed of 9 types of cells. Two types out of them work as frame cells supporting the epithelium and the secretory cells embedded within the epithelium Seven types of secretory cells are classifiable depend on their histochemical reactions and ultrastructures. The materials secreted by the secretory cells are neutral mucopolysaccharide, acid mucopolysaccharide, and glycogen.
벗굴을 양식산업에 적용하여 그 생산성을 높일 수 있는 방안을 강구하기 위하여 이 종에 대한 자연서식지의 환경특성과 이매패의 자원량을 조사하였다. 벗굴 서식지 주변해역에서 수온은 5.5<TEX>$^{\circ}C$</TEX>-27.4<TEX>$^{\circ}C$</TEX>의 범위였고, 염분은 31.2-33.4 로 평균 32.3 였다. DO, COD, DIN 및 PO<TEX>$_{4}$</TEX><TEX>$^{3}$</TEX>-P은 각각 평균 7.11 mg/L, 0.44 mg/L, 4.55 <TEX>$\mu\textrm{g}$</TEX>-at./L 및 0.36 <TEX>$\mu\textrm{g}$</TEX>-at./L이었다. 표층퇴적물의 입도조성은 사력질, 니사질, 사니질 등으로 다양하게 나타났으며, 퇴적물의 IL, COD 및 AVS는 각각 평균 2.6%, 13.70 mg/g dry 및 0.33 mg/g dry였다. 한편, 식물플랑크톤의 현존량은 90.3(9월)-1,272.0 cell/ml(2월)이었으며, 우점종은 Skeletonema costatum, Paralia sulcata, Eucampia zodiacus, Chaetoceros curvicetus, Chaetoceros affinis, Chaetoceros debilis, Chaetoceros decipiens, Asterionella glacialis, Pseudo-nitzschia longissima, Pseudonitzschia seriata, Ceratium furca, Ceratium fusus 등이었다. 벗굴 서식지에서 출현한 조개류는 벗굴(Ostrea denselamellosa), 참굴(Crassostrea gigas), 바지락(Tapes philippinarum), 새고막(Scaphaca subcrenata), 피조개(Scaphaca broughtonii), 키조개(Atrina pectinata), 새조개(Fulvia mutica), 진주담치(Mytilus edulis), 살조개(Protothaca jedoensis), 갈색이랑조개(Megacardita ferruginosa) 등 모두 10종이었다. 그리고 이매패류의 평균 자원량은 21개체/<TEX>$m^2$</TEX>(479.14 g/<TEX>$m^2$</TEX>)이었고, 벗굴은 0.25 개체/<TEX>$m^2$</TEX>(231.25 g/<TEX>$m^2$</TEX>)로 나타났다.
This study was measured environmental factors of flat oyster habitats and biomass of flat oyster to improve the productivity of flat oyster. Water temperature and salinity of the flat oyster habitat ranged from 5.5 to 27.4<TEX>$^{\circ}C$</TEX> and from 31.2 to 33.4 , respectively. Average concentrations of DO, COD, DIN and PO<TEX>$\_$</TEX>4/<TEX>$\^$</TEX>3/ -P were 7.11 mg/l, 4.55 <TEX>$\mu\textrm{g}$</TEX>-at./l and 0.36 <TEX>$\mu\textrm{g}$</TEX>-at./l respectively. Surface sediments at the sampling area were composed of coarse sand, sandy silt and silty sand. Average level of IL, COD and AVS in the surface sediments were 2.6%, 13.70 mg/g dry and 0.33 mg/g dry respectively. In each sampling station, total standing crops of phytoplankton showed peaks twice in February and August. Dominant species of phytoplankton occurred in Haechang Bay throughout the year were Skeletonema costatum, Paralia sulcata, Eucampia zodiacus, Chaetoceros curvicetus, C. affinis, C. debilis, C. decipiens, Asterionella glacialis, Pseudonitzschia longissima, Pseudonitzschia seriata, Ceratium furca and C. fusus. Ten species of the bivalves were collected at the flat oyster habitat. Most of bivalves were the eutrophic species Ostrea denselamellosa, Crassostrea gigas, Ruditapes philippinarum, Scaphraca subcrenata, Scapharca broughtonii, Atrina pectinata, Fulvia mutica, Mytilus edulis, Protothaca jedoensis and Megacardita ferruginosa. The mean density of them was 21 inds./㎡ (479.14 g/㎡), while that of the flat oyster was at 0.25 inds./㎡ (231.25 g/㎡).
We investigated the processes of egg and larval developments for aquaculture technique development of seedling production fo the flat oyster, Ostrea denselamellosa. Teo flat oyster of larviparous type was different from the pacific oyser (ovivarous type) because their larvae (trochophore and prodissoconch larvae) in the gill released into the seawater. The process of egg development was observed by artificial fertilization at <TEX>$25^{\circ}C$</TEX>, using a dissecting method. The sizes of Unfertilized eggs ranged from 80 to 90 <TEX>$\mu\textrm{m}$</TEX> and fertilized eggs with globule-shape was 90-100 <TEX>$\mu\textrm{m}$</TEX>. The Polar body appeared after fertilization and egg cleavage began within 1 hour, reaching the blastula stage after 10 hours. The trochophore in the gill appeared 2-3 days after fertilization and grew to the prodissoconch larvae (130 140 <TEX>$\mu\textrm{m}$</TEX>) having a complete shell after 1-2 days. The shell of prodissoconch larvae grew to 205 220 <TEX>$\mu\textrm{m}$</TEX> after 10 hours, and then they became umbo stage larvae showing oval in shape. The velum of umbo stage larvae was degenerated about 17-20 days after fertilization and grew into a pediveliger with a developed foot, at this time, the shell length size was 320 360 <TEX>$\mu\textrm{m}$</TEX>.
The present study aimed to elucidate whether and intestinal fluke, Gymnophalloides sp. exist in Gogunsan-gundo located at western part of Korean Peninsula; about 100 km apart from Gunsan city, Jeollabuk-do, Korea. The survey was carried out Two times each in 1997 and 1998, examining stool samples by means of formalin-ether concentration method. Results are summarized as follows : of 411 fecal samples examined, Gymnophalloides sp. positives were 19 (8.9%); 9.5% inMunyeodo, 1% in Seonyudo, but none in Jangjado. The positive cases did not show any specific clinical complaints. Prevalence rate of Gymnophalloides seoi metacercariae from oysters, Crassostrea gigas were 80.8%
전북 곰소만에 서식하는 바지락의 생리적 리듬을 알아보기 위하여 24시간 동안 1시간 간격으로 산소소비율 및 여수율의 변화를 측정하였다. 바지락의 호흡율 및 여수율에 의한 생리적 리듬은 15<TEX>$^{\circ}C$</TEX>와 <TEX>$25^{\circ}C$</TEX>에서 두 가지 모두 24시간 동안 2번의 peak를 보이는데, 밤-만조시에 최대를 나타내었으며, 낮-간조시에 최소를 나타내어 조석에 의한 일주리듬 현상을 보였다. 24시간 동안 산소소비율 및 여수율의 변화는 수온별로 급격한 특수한 변화를 보이지 않았다.
Changes in Oxygen consumption and filtration rates were investigated to understand physiological rhythms for 24 hours of the Manila clam, Ruditapes philippinarum. physiological rhythms in the oxygen consumption and filtration rates at 15<TEX>$^{\circ}C$</TEX> and 25<TEX>$^{\circ}C$</TEX> were showed diurnal tidal rhythms, appearing two peaks for 24 hours: maximum at night-high tide and minimum at day-low tide. No rapid variations in oxygen consumption and filtration rates for 24 hours appeared at two different water temperatures.