• The Korean Journal of Malacology
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• v.28 no.1
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• pp.29-35
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• 2012

Growth patterns of the Manila clam, Ruditapes philippinarum in each tidal level were studied in the intertidal zone in Tae-an on the west coast of South Korea from April to August 2009. Environmental factors and the specimens of R. philippinarum were monthly collected at three intertidal locations: low intertidal zone, low-middle intertidal zone and middle intertidal zone. Temperature of sediment in low intertidal zone were lower than those in other intertidal locations. Concentrations of Chl-${\alpha}$ were not significantly different between in each tidal level. Exposure hours in low intertidal zone were shorter than those in other intertidal locations. Density of each year class in low intertidal zone were higher than those in low-middle intertidal zone and middle intertidal zone. Growth factors of R. philippinarum in low intertidal zone were better than those in other intertidal locations. The growth rate of under one year class individuals of low intertidal zone were higher than those in low-middle intertidal zone and middle intertidal zone, before the main recruitment period of R. pilippinarum. Although the growth patterns of R. philippinarum may be affected by various environmental factors, we suggests that the exposure duration is the main affect in the growth patterns of R. philippinarum in intertidal zone.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.3
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• pp.190-193
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• 2001

To investigate the effects of the dissolved oxygen concentration (DO) on Scope for growth (SFG) of the manila clam, Ruditapes philippinarum, we measured $LC_{50}$, filtration, respiration, ammonia excretion, and assimilation rates under $23\pm0.5^{\circ}C$ as a function of DO. The $LC_{50}$ of DO for R. philippinarum, was 2.4 mgDO $L^{-1}$. With decreasing DO, filtration and respiration rates of R. philippinarum decreased, while ammonia excretion rate increased, The assimilation rate was $68.2\%$ at 6.5 mgDO $L^{-1}$, decreased to $29.8\~39.3\%$ at 3.5 mgDO $L^{-1}$. R. philippinarum had positive SFG's at the $DO{\geq}2.5mgDO\;L^{-1}$.

• The Korean Journal of Malacology
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• v.15 no.1
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• pp.21-30
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• 1999

This study was carried out to describe the growth of Ruditapes philippinarum on Chohwa and Toksan tidal flat in Kwangyang Bay, from June 1994 to July 1995. On the Chohwa tidal flat, the mean gran size, organic content and chlorophyll-a of the surface sediment were the range of 2.50-4.46 , 4.99-5.11%, 14.53-19.90 $\mu\textrm{g}$ cm$\^$-3/, and on the Toksan tidal flat, 0.83-1.66 , 2.22-2.34%, 6.20-6.90 $\mu\textrm{g}$ cm$\^$-3/, respectively. The shell length of R. philippinarum increased rapidly from spring to summer, and gently from summer to autumn, and ceased during winter. Fresh weight increased during spring and autumn, and decreased during summer and winter. condition factors also showed the same variations of weights. Synthesized annual growth pattern of 4 year classes in shell length fitted the von Bertalnffy growth model well. The annual growth of weight fitted the Gompertz model relatively well. The values of w, initial shell growth rate, and AGR$\sub$max/, maximum weight growth rate, on the Chohwa tidal flat were lower than those on the Toksan tidal flat. Comparing the growth patterns in the same tidal flat, growth rate was higher on the lover tidal flat than those on the higher tidal flat. In conclusion, the Chohwa tidal flat maintaining higher density showed lover growth rate, because of relatively insufficient food supply and inhabiting space.

• The Korean Journal of Malacology
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• v.27 no.1
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• pp.1-7
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• 2011

Age and growth of the short-necked, Ruditapes philippinarum were collected from Goheung coast in Korea. Relative growth equations among SL, SH, SW and TW of Ruditapes philippinarum were ranged from 0.8059 to 0.8859. The ring radius were estimated from a von Bertalanffy method with the values of $SL_{1.58}=12.51{\pm}2.55\;mm$, $SL_{2.58}=20.27{\pm}3.08\;mm$, $SL_{3.58}=26.90{\pm}2.49\;mm$, $SL_{4.58}=31.35{\pm}3.62\;mm$, $SL_{5.58}=35.45{\pm}3.54\;mm$, $SL_{6.58}=38.78{\pm}4.04\;mm$. Back calculated total weight at the formation of annual ring on the shell of Ruditapes philippinarum with the values $TW_{1.58}$=0.35 g, $TW_{2.58}$ = 4.62 g, $TW_{3.58}$ = 5.84 g, $TW_{4.58}$ = 6.71 g, $TW_{5.58}$ = 7.50 g, $TW_{6.58}$ = 8.14 g. Growth curves for shell height and total weight fitted to the von Bertalanffy equation were expressed as: $SL_t= 51.01(1-e^{-0.1738(t+1.07)})$ $TW_t = 11.65(1-e^{-0.1738(t+1.07)})^{2.9519}$.

• The Korean Journal of Malacology
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• v.26 no.3
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• pp.227-234
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• 2010

A comparative analysis of size and age structures of coastal subfossil shell assemblages of the shortnecked clam Ruditapes philippinarum from open and protected bays of Cheju Island (Korea) was carried out. On the whole, taking into account the damage of small fragile shells, size and age structures of the shell assemblages corresponded to the classical curve of bivalve population distribution when its mortality diminishes with age increase up to a certain threshold. It was found that shell samples from open bays of the western, southern and eastern coasts included shells of smaller and younger individuals (L ${\leq}$ 40 mm, ${\leq}$ 4 years) than samples from the eastern protected bay (L ${\leq}$ 54.5 mm, ${\leq}$ 6 years). Evidently, strong wave activity was the reason for a short life-span of the clams from the open areas. Growth was investigated retrospectively by annual growth rings on the shells. Growth rates of the clams from the various coasts of Cheju Island differed. However, growth rates of the clams from different biotopes at the same (eastern) side of the Island were similar. Shell height/length and width/length ratios statistically significantly increased with the clam age increase. Most likely, the reason for such shell shape alteration is that more conglobated individuals more survive being more energy-optimal than oblong specimens.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.5
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• pp.511-518
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• 2019

Evaluating the habitat suitability of potential aquaculture sites for cultured species is critical to the sustainable use of tidal flats. This study evaluated the habitat suitability index (HSI) of 12 sites in a tidal flat aquaculture farm at Geunso Bay, Taean, in June 2016. The parameters used to model the suitability index were Growth (water temperature, chlorophyll ${\alpha}$, hydrodynamics), Survival (sediment-sand, mean size, air exposure), and Environment (DO, salinity). The HSI was calculated using weighted and No weighted geometric means. The results showed high habitat suitability at the bay's entrance (HIS; No weighted, 0.60-0.70; weighted, 0.60). Hydrodynamics, air exposure, sediment-sand and mean size are thought to have a significant impact on habitat selection by Manila clams Ruditapes philippinarum. This study explored the optimum habitat for Manila clams by calculating the HSI, providing basic data for tidal flat management.

• The Korean Journal of Malacology
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• v.24 no.1
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• pp.25-32
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• 2008

In order to estimate the necessity of refrigerated storage of fresh seafood for short-term storage, and evaluate the effect of refrigerated storage on pen shell Atrina pectinata and clam Ruditapes philippinarum collected from Jang-su of Deukryang Bay and I-mok of Sunchen Bay in South Korea, the counts of coliform, Escherichia coli and total aerobic bacteria in A. pectinata and R. philippinarum under non-refrigerated $(28{\pm}1^{\circ}C)$ and refrigerated storage conditions $(4{\pm}1^{\circ}C)$ were determined. The results indicated that the storage at temperature of $4^{\circ}C$ possessed significant effects on inhibiting bacterial growth in live seafood. And refrigerated storage had different effect on A. pectinata and R. philippinarum. Different species and culture environments significantly influenced the initial and ultima bacteria counts. This study confirmed that refrigerated storage for short-term storage of live seafood was necessary, and indicated that the effect of refrigerated storage was influenced by comprehensive effectors.

• The Korean Journal of Malacology
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• v.10 no.1
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• pp.38-48
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• 1994

Gonadal developmint, age and growth of Ruditapes philippinarum were investigated using samples from the intertidal zone of Simpo on the coast of Kimje, Korea, which were collected onthly for one year from Februaty 1993 to January 1994.Ruditapes philippinarum is diecious in sex. The gonads are located between the subregion of the midintestinal glands and reticular connective tissue of the foot. The ovary is composed of a number of ovarian sacs, and the testis is composed of numerous seminiferous tubules. The clam spawns once a year from early June to darly October, and the main spawning occurred between July and August when the water temperature went above 23$^{\circ}C$. Ripe oocytes are about 65-70${\mu}{\textrm}{m}$ in diameter. Gonadal phases of this species can be divided into five successive stages; multiplicative(February to March), growing (April to May), mature(Aprilto Septimber), spent(June to October), and degenerative and resting(july to March). Spawning is closely related to the sea water temperature. Based on the monthly variations of marginal index (MI')of the shell, it was suggested that the annual ring mark formation occurred in March once a year and took approximately 8 months (0.67 year) for first ring to be formed on the shell. The relationship between the shell length(SL) and the total weight (TW) was represented by nonlinear equation; TW=1.208 x 10/ sup -4/ S $L^{3.158}$, and also in the relationship be-tweenthe shell length (SL) and the shell height(SH), the shell length and the shell width (SW) were represented by the linear equations; SH=0.726 SL-0.483, SW=0.542 SL-0.803.Growth curves for shell length and total weight fitted to von Bertalanffs equation were expressed as: S $L_{t}$ =68.34(1- $e^{0.221}$(t+0.418)) T $W_{t}$ =75.16(1- $e^{0.221}$(t=0.418))$^{3.158/3.158}$

• Development and Reproduction
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• v.16 no.3
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• pp.177-183
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• 2012

This study attempts to propose the possibility of the sex reversal in Tegillarca granosa and Ruditapes philippinarum by confirming the changes in the sex ratio with the shell length (SL) in the same population level. For analysis of sex ratio with SL, 1500 individuals of T. granosa (SL 10.1-45.0 mm) and 712 individuals of R. philippinarum (SL 15.1-70.0 mm) were used. Sex was analyzed histologically. The average sex ratios (F:M) of T. granosa and R. philippinarum were 1:1.22 and 1:0.96, respectively. However, sex ratio was found to differ when the clams were divided into groups according to SL in 5.0 mm intervals. Both species displayed the tendency of increase in the proportion of female with increase in SL. In this study, changes in the sex ratio in accordance with the growth of T. granosa and R. philippinarum are determined to be indirect evidence that signifies their sex reversal.

• The Korean Journal of Malacology
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• v.26 no.1
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• pp.91-95
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• 2010

Density-dependant growth and mortality rate of Manila clam Ruditapes philippinarum reared in net cages was investigated in Gomso Bay, Korea where unusually high mortality of clams has been reported. For the experiment, four groups of clam cages were set up with a density of $2,000clams/m^2$ (group A), $1,000clams/m^2$ (group B), $500clams/m^2$ (group C) and $100clams/m^2$ (group D). Mortality and growth of clams in each experimental cage was monitored biweekly from May 2001 to September 2001. Highest mortality in group A was observed in late August, while highest mortality of rest groups was observed in early September. In September, the cumulative mortality in group A was 99%, while it was 93.2% in group B, 91.2% in group C and 88% in group D. Shell growth rate of clams in thecages was found to be density dependent; monthly shell length increase was 0.67 mm in group A, 1.33 mm in group B, 1.63 mm in group C and 1.71 mm in group D. Our study indicated that clam growth and mortality in the Bay is density dependent and the growth and survival rate is negatively correlated with the density.