• 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))$^{3.158/3.158}$

• Journal of Ocean Engineering and Technology
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• v.28 no.3
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• pp.236-244
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• 2014

This study considered a seagrass habitat in order to analyze the characteristics of a marine environment of seagrass located in the Seomjin river estuary, through an analysis of the distribution of the water depth, field observation, and three-dimensional numerical experiments using an EFDC model. The seagrass habitat was usually distributed at D.L(-) 0.5~0.0 m, and was hardly seen in the intertidal zone higher than that range. The distribution of the water temperature was within the range of $7.0{\sim}23.2^{\circ}C$, and the seagrass was demonstrated to have a strong tolerance to changes in the water temperature. In addition, the salinity distribution was found to be 27.2~31.0 psu, with suspended solids of 32.1 mg/L, which were higher than the previous research results (Huh et al., 1998), implying that there may be a reduction in the amount of deposits caused by the suspended solids. As for the sedimentary facies, they were comprised of 62.7% sand, 19.1% silt, and 18.2% clay, indicating that the arenaceous was superior and the sedimentary facies were similar to that of Dadae Bay. According to a numerical experiment, the maximum tidal current was 75 cm/s, while the tidal residual current was 10 cm/s, confirming that it sufficiently adapted to strong tidal currents. The erosion and deposition are predicted to be less than 1.0 cm/year. Thus, it is judged that the resuspension of sediments due to tidal currents and the changes in sedimentary facies are insignificant.

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2003.11a
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• pp.92-97
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• 2003

Community structure of macrobenthos was studied on Angol clam farming ground of Chinhae Bay in the southern coast of Korea. Macrobenthos samples were collected monthly using a quadrate at each station from March 1998. Macrobenthos samples were seived by 1.0mm mesh seive. Mean grain size was 0.267 mm. A total of 111 macrobenthos species were sampled with a mean density of 1,651ind/m$^2$and biomass of 1466.7wwt.g/m$^2$. Annelida was density-dominant faunal group with a mean density of 818ind/m$^2$, comprising of 49.6% of the total density of the macrobenthos. It was followed by Mollusca with 660ind/m$^2$(40.0%). Mollusca was biomass-dominant faunal group. Major dominant species in the number of individual were Ruditapes philippinarum (375ind/m$^2$), Batillaria cumingi (208ind/m$^2$), Cirrformia tentaculata (167ind/m$^2$), Ceratonereis erithraeensis (151ind/m$^2$), Capitella capitata (111ind/m$^2$) and Sigambra tentaculata (91ind/m$^2$). Major dominant species in the biomass were Ruditapes philippinarum (1156.6wwt.g/m$^2$), Batillaria cumingi (111.0wwt.g/m$^2$) and Cyclina sinenis (106.2wwt.g/m$^2$). The species diversity was increased gradually during the study period. Increasing of species diversity was due to not only increasing of number of species but also decreasing of dominance of some polycheates. Contents of silt-clay was increased gradually in the intertidal zone.

• Journal of Wetlands Research
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• v.12 no.2
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• pp.47-57
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• 2010

The purpose of this study is to investigate the seasonal variation of water quality parameters in Suncheon bay. We investigated at fifteen stations from October 2008to July 2009. picoplankton The salinity in the bay ranged from 8.8 to 31.9psu, DO ranged from 6.34 to 11.84 mg/L and the pH ranged from 7.80 to 8.34. The mean concentration of suspended solids ranged from 52.1 to 104.0 mg/L and COD concentration ranged from 2.27 to 5.33 mg/L. The total coliform group ranged from 6 to 37CFU. The concentrations of COD and total coliform group were relatively higher in the upper part of the Suncheon bay than lower one. The concentrations of nutrients such as nitrogen, phosphorus, silicate were also higher in the upper part of the bay, because the large amount of fresh water was inflowed into the bay from the Dong stream and Isa stream. Because the N/P ratio was ranged from 4.54 to 9.61 in this study, the limiting nutrients was nitrogen in the Suncheon bay comparing to the Redfield ratio.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.21 no.3
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• pp.91-102
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• 2016

The spatio-temporal variations of the dissolved methane concentration were investigated and the methane budget was estimated in the Nakdong Estuary in January, September, and November of 2014. Dissolved methane showed seasonal variation (21~874 nM) with high concentration in summer due to enhanced temperature and fresh water discharge. Decreasing trends of dissolved methane from the river to the estuary were consistent in all seasons showing the main source of the estuarine methane is river discharge. However, the decreasing trends were modified seasonally due to the local sources such as organic-rich sediments in intertidal zone or near the estuarine barrage. Dissolved methane concentration in the Nakdong Estuary was high, compared to other estuaries probably due to the well developed wetland in Nakdong-river system and stagnation effect from barrages and dams. Dominant sink for the Nakdong estuarine methane was outflux into the atmosphere. Relatively long residence time (produced by barrier island and estuarine dam) in the estuary might provide the enough time for the outgassing.

• Journal of The Geomorphological Association of Korea
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• v.25 no.1
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• pp.1-17
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• 2018

The characteristics and burial ages of sand sediments on the Jiduri coast in Daechung-myeon, Ongjin-gun, Incheon were investigated. Daecheong Island is the area where the characteristics of the rocky coast and sand coast are shown. Various studies have been conducted on the Okjukdong sand dune that appears in the north of the island. However, there has been no study on the sandy sedimentary topography of the Jiduri and Moraewul area in the south. The sandy sedimentary terrain of Jiduri is divided into sandy beaches, sand dunes and sand deposits along the slope including climbing dune. Overall, the depth of sandy sediments in Jiduri is not deep. The characteristics of sandy sediments and burial ages were investigated at an elevation of about 23 m above sea level at the back of Jiduli Beach and 46 m above sea level at the ridge line between Jiduri and Moraewol. From the Jiduri coast to the hillside behind, the average grain size decreases and the sorting becomes better as it moves from the intertidal zone to the beach and the foredune. This indicates the selective sand transport by the wind and can be judged by the terrain formed under the current sedimentation environment. The average grain size at the upper part of the section of JD-1 (elevation of about 23m MSL) was $1.6918{\varphi}$ of medium sand. The sorting was $0.4584{\varphi}$, skewness was -1.0491 and kurtosis was -1.2411, respectively. Particularly, the average particle size of the crosssection issomewhat uniform, but the color of the constituent material changes from brown to black. In the case of JD-2 (about 46 m MSL), the mean grain size of the section was $1.7943{\varphi}$, the sorting was 0.4931, the skewness was -1.1163, and the kurtosis was 1.2133. On the other hand, the brown and black layers of JD-1 exhibited a burial age of $0.1{\pm}0.0ka$ and the JD-2 had a burial age of $0.7{\pm}0.0ka$.

• Journal of Practical Agriculture & Fisheries Research
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• v.17 no.1
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• pp.45-56
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• 2015

The distribution of seaweed was examined in Jeonnam archipelago marine ranching area, the coastal of geumo-do, Yosu. Abundance and distribution of seaweed in dropping site of artificial reef were sampled at 6 station at October 2007. Seaweed community were investigated with quadrat method at line-transect by scientific SCUBA divers. as a result, 30 species in total, 4 green, 9 brown and 15 red seaweed were identified. Range of seaweed biomass in all sampling stations were about 1,600~4,000 g/m². At intertidal zone, appearance of individuals and dominance rate were showed higher than below the subtidal line and at depth from 4m to 6m, individuals, dominance rate and biomass were represented low level. characteristic of water in marine ranching area is turbidity and also compensation depth is low. For that reason, individuals of seaweed community were smaller from depth of 4 meters. Therefore, when equip the artificial reef for preparation of seaweed beds need consider that equipment periods(early spring; before releasing marine seaweed spore) and suitable water depth(3~6m).

• Korean Journal of Environmental Biology
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• v.40 no.3
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• pp.275-280
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• 2022

Suspended solids play an important role in the growth and survival of aquatic organisms. The marine zooplankton species tested in this study were Tigriopus west (Copepoda) and Haustorioides koreanus (Amphipoda) sampled from the intertidal zone, including Artemia nauplii(Branchiopoda) hatched from cysts. The study design included six concentrations (0, 50, 100, 250, 500, and 1,000mg L^-1) of the suspended test particles assayed in triplicate. Experimental cultures in 500 mL-round polycarbonate bottles were subsampled after 96 h to count dead zooplankton. The culture bottles were agitated at 4 RPM on a rotating wheel at 23℃ and 30 PSU. The survival rates of Artemia nauplii and T. west were not affected by suspended solid concentrations higher than 50.0 mg L^-1, whereas the survival rate of H. koreanus decreased with increasing concentrations (p<0.05). In conclusion, H. koreanus and T. west, which were continuously exposed to suspended solid concentrations higher than 50.0 mg L^-1, were affected by low-intensity ecological stress. However, in the case of H. koreanus, a concentration of 50.0 mg L^-1 may be considered to be the limit of tolerance to suspended solids, suggesting that the number of individuals who eventually die will increase if continuously exposed.

• Korean Journal of Ichthyology
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• v.35 no.1
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• pp.44-49
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• 2023

A single specimen of the genus Bothus (family Bothidae) was collected for the first time at the intertidal zone of Moseulpo Port, Daejeong-eup, Seogwipo-si, Jejudo Island, on 14 August 2022. The specimen was identified as Bothus pantherinus in having following morphological traits: dark spots and ring-shaped patterns near eyes and the pectoral fins, one distinct spot in the center of the lateral line, 75 lateral line scales, and seven hourglass shaped supracranial pterygiophores. As a result of analyzing 603 bp of mitochondrial DNA COI sequences, our specimen was perfectly matched to those of B. pantherinus registered in NCBI. It has been known that the species is widely distributed throughout the Indo-Pacific Ocean from Red Sea to Hawaiian (32 degrees north to 32 degrees south), but this study revealed that its distribution expanded to the waters of Jejudo Island (33 degrees north), Korea. We propose its new Korean name "Beot-kkoch-mu-nui-dung-geul-neob-chi".

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.29 no.1
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• pp.42-55
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• 2024

To discover unrecorded diatoms, seawater, sand, and pebbles were collected from the intertidal zone of five tidal flats from 2016 to 2023. Diatoms were isolated from the collected samples, cultured, and the ultrastructure of the cells was observed using a scanning electron microscope. 7 species of unrecorded diatoms, consisting of 3 orders, 5 families, and 7 genera, were discovered: Gomphoseptatum aestuarii, Rhoiconeis pagoensis, Seminavis exigua, Plagiolemma distortum, Staurotropis seychellensis, Biremis sigmoidea, Liriogramma sarcophagus. Among these, four genera, Rhoiconeis, Plagiolemma, Staurotropis, and Liriogramma, are reported for the first time in Korea. L. sarcophagus was separated from the central diatom Asteromphalus and transferred to Liriogramma, but its phylogenetic position has not yet been clearly established.