• The Korean Journal of Malacology
• /
• v.15 no.1
• /
• pp.31-39
• /
• 1999

This study was aimed to describe the population dynamics and secondary production of Tapes philppinarum on Chohwa and Toksan tidal flats in Kwangyang Bay, from June 1994 to July 1995. The size distributions in shell length showed bimodal patterns from June 1994 to April 1995. Thereafter the distribution changed to the passage of time, indicating an increase in shell length. The mean densities decreased gradually with month. Chohwa A sustained highestdensity, followed by Chohwa B, Toksan C, and Toksan D. The recruitment of new year class occurred first on the upper tidal flat, and then moved to the lower tidal flat. The mean biomass in flesh dry weight of each year class increased in spring just before the spawning period, and thereafter decreased progressively. Annual mean biomass wasrecorded as 170.7 g m$\^$-2/ at Chohwa A, 220.7 g m$\^$-2/ at Chohwa B, 21.8 g m$\^$-2/ at Toksan C, and 45.2 g m$\^$-2/ at toksan D. Annual productions of Ruditapes philippinarum were estimated as 259.72 g m$\^$-2/ yr$\_$-1/ at Chohwa A, 359.79 g m$\^$-2/ yr$\_$-1/ at Chohwa B, 45.02 g m$\^$-2/ yr$\_$-1/ at Toksan c, 68.88 g m$\^$-2/ yr$\_$-1/ at Toksan D. Annual productions were much higher on Chohwa tidal flat than those on Toksan tidal flat. While P:B ratio were higher on Toksan tidal flat as 1.70 than those on Chohwa tidal flat as 1.58. In conclusion, the Chohwa tidal flat showed higher biomass and producion of Ruditapes philippinarum, whereas the Toksan tidal flat showed higher P:B ratio. The total amount of potential food might influence on the density, biomass nad produciton, whereas the amount of food and space per individual might influence on the growth rate and P:B ratio.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.2 no.1
• /
• pp.33-40
• /
• 1969

1. Physicochemical properties of sea water and soil of Korean tidal flats densely populated with species of Mactra veneriformis, Cyclina sinensis, Meretrix lusoria, and Tapes philippinarum, were investigated in order to find out the index of environmental factors in marine bivalve culture. 2. The turbidity varied with the change in concentrations of organic matter, silicate, and the exchangeable copper in sea water. All of these concentrations in Inchon, Kunsan, and Hansando were higher than those in Yusoo. In the 5 areas investigated the lowest were ditected at Kangnung. 3. The minerals and organic matter content in sea water dia not vary significantly among the different bivalve beds. And it was presumed that the soil texture was one of the most important environmental factors for the density of the bivalves in tidelands. 4. The soil texture index of the different bivalve beds was obtained as follow: 5. There were no significant differences of pH, the exchangeable calcium, and the exchangeable copper contents of bottom soils in the 4 different bivalve beds. As important factors in these areas, it seems that the amount of chemical properties might not affect the distribution of bivalve species. 6. Among the 4 beds the soil organic matter content was highest at the T. philippinarum bed and varied with the total nitrogen content. 7. Among the different bivalve beds, it was significant that the water holding capacity and available phosphorus content were highest at the M. veneriformis bed.

• The Korean Journal of Malacology
• /
• v.15 no.2
• /
• pp.105-113
• /
• 1999

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$^{\circ}C$ and from 31.2 to 33.4 , respectively. Average concentrations of DO, COD, DIN and PO$\_$4/$\^$3/ -P were 7.11 mg/l, 4.55 $\mu\textrm{g}$-at./l and 0.36 $\mu\textrm{g}$-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/㎡).

• Journal of Food Hygiene and Safety
• /
• v.7 no.4
• /
• pp.137-142
• /
• 1992

The distribution of V. parahaemolyticus was surveyed from various kinds of shells in Kunsan Bay from July to September, 1987. 1be morphological, biochemical and serological characteristics of the isolated strains were studied. The results were as follows: 1. 41 strains were isolated from 1,350 specimens of shells (Crassostrea gigas, Tapes philippinarum, Meretrix Iusoria) 2. The isolation rates of V. parahaemolytieus were 3% in July, 3.8% in August, and 2.2% in September, respectively. 3. V. parahaemolytkus was more frequently isolated from Kunsan (20 strains) than Bideukgi (12 strains) and Gae Hwa-do (9 strains). 4. V. parahaemolyticus was more frequently isolated from C gigas (23 strains) than other shells. 5. Kanagawa hemolysis reactions were all negative. 6. 6 Strains positive to K pooled antiserum included K IV, K V, K VI and K vn type.

• Journal of Food Hygiene and Safety
• /
• v.17 no.3
• /
• pp.146-151
• /
• 2002

The contents [average(minimum∼maximum), Unit:mg/kg] of hazardous heavy metals(Hg, Cd and Pb) were estimated from 951 fishery products in Seoul(468 fishes,373 shellfishes, 39 crustaceans and 71 others) from January to December in 2001 by Atomic Absorption Spectrometer. Hg contents showed in shellfishes [0.033(N.D.∼0.19)]>others(0.026(N.D.∼0.11)]>crustaceans[0.026(N.D.∼0.09)]>fishes[0.018(N.D.∼0.19)], Misgurnus mizolepis(0.19) and Tegillarca granosa(0.19) were the highest. Pb content were shellfishes [0.223(N.D.∼l.38)] >fishes[0.213(N.D.∼1.68)]>others[0.15(N.D.∼0.39)]>crustaceans[0.144(N.D.∼0.444)], and Misgurnus mizolepis (1.68)>Hypomesus olidus(1.44)>Tapes philippinarum(1.38)>Anguilla japonica(1.35). Also, Tegillarca granosa(1.85) was the most Cd contents among shellfishes[0.288(N.D.∼1.85)].