• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.6
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• pp.593-598
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• 1986

The growth of the pearl oyster, Pinctada fucata was compared between two areas, Hansan Bay and Ilkwang located in southern part and in southeast part of Korean waters respectively, from November 1984 to June 1986. The pearl oysters in Hansan Bay grew from 2.53cm to 6.07 cm in shell length in 17 months, while those in Ilkwang grew from 2.53 cm to 4.07 cm in 19 momths. Shell height, shell breadth and total weight of the pearl oysters in Hansan Bay also showed more rapid growth than those in Ilkwang. The relative growth of shell breadth to shell length in specimens between Hansan Bay and Ilkwang showed a significant difference indicating that the value in Ilkwang is bigger than that in Hansan Bay, It is also suggested that Hansan Bay is a good area for the growth and Ilkwang, an area worth wintering of the pearl oyster.

• ALGAE
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• v.23 no.4
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• pp.317-326
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• 2008

Marine algal flora and community structure were investigated seasonally at three sites in Ilkwang Bay on the southern east coast of Korea from May 2007 to February 2008. Total 103 species including 10 of green algae, 17 of brown algae, 76 of red algae were collected and identified. Among these species, 21 species were found throughout the year. Ulva pertusa, Enteromorpha linza, Grateloupia lanceolata, Chondracanthus intermedia and Caulacanthus ustulatus were distributed dominantly in upper intertidal zone. By contrast, crustose coralline algae, Grateloupia spp., Chondracanthus tenellus, Prionitis cornea and Sargassum spp. occurred predominantly in middle intertidal zone. Grateloupia spp., Sargassum spp., Ecklonia cava and Ulva pertusa were dominant in lower intertidal zone. Annual mean biomass in wet weight was 478.3 g m$^{-2}$. Maximum biomass was recorded in site 1 (731.8 g m$^{-2}$), and minimum was recorded in site 3 (78.5 g m$^{-2}$). The R/P, C/P and (R + C)/P value reflecting flora characteristics were 4.47, 0.59 and 5.06, respectively. Two groups produced by cluster analysis, one including sites 1, 2 and the other including site 3, showed meaningful difference in similarity, each other. Site 3 showed the limited species composition due to inflow of fresh water and absence of solid substratum. However, there was no significant difference between site 1 and site 2. In conclusion, the number of marine algae species and biomass in Ilkwang Bay were markedly reduced comparing with the previous studies. These suggest that a solution for reconstruction of the poor marine algal vegetation is considerably demanded.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.5
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• pp.906-908
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• 1997

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.4
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• pp.178-185
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• 2013

We measured salinity and $^{222}Rn$ concentration to explore submarine spring along the coastal areas (Mundongri, Icheon-ri, Jukseong-ri, Daebyeon-ri, Yeonhwa-ri, and Dadae-po) including Ilkwang Bay of Busan Metropolitan City in 2009 and 2010. Before field observation, we selected the potential and possible locations of submarine spring based on the lineament distribution and rose diagram analysis. Salinity and radon concentration were measured within the 1~2 km from the coastal lines. Radon activity decreased gradually from onshore to offshore. Vertical profiles of salinity at some stations showed lateral transport of water mass characterized by low salinity. Vertical profiles of salinity in the Ilkwang Bay, which is a unique bay in the south-eastern coastal area of Busan Metropolitan City, also showed the occurrence of low salinity in the bottom seawater. Our results suggest the possible occurrence of submarine discharge of fresh groundwater in the coastal areas around Busan Metropolitan City. In the future, intensive research should be conducted for the exploration methods of submarine spring as well for the possible utility of submarine groundwater as alternative water resources.

• Ocean Science Journal
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• v.43 no.4
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• pp.223-232
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• 2008

In order to determine the temporal and spatial variations of nutrient profiles in the shallow pore water columns (upper 30 cm depth) of intertidal sandflats, we measured the salinity and nutrient concentrations in pore water and seawater at various coastal environments along the southern coast of Korea. In the intertidal zone, salinity and nutrient concentrations in pore water showed marked vertical changes with depth, owing to the active exchange between the pore water and overlying seawater, while they are temporally more stable and vertically constant in the sublittoral zone. In some cases, the advective flow of fresh groundwater caused strong vertical gradients of salinity and nutrients in the upper 10 cm depth of surface sediments, indicating the active mixing of the fresher groundwater with overlying seawater. Such upper pore water column profiles clearly signified the temporal fluctuation of lower-salinity and higher-Si seawater intrusion into pore water in an intertidal sandflat near the mouth of an estuary. We also observed a semimonthly fluctuation of pore water nutrients due to spring-neap tide associated recirculation of seawater through the upper sediments. Our study shows that the exchange of water and nutrients between shallow pore water and overlying seawater is most active in the upper 20 cm layer of intertidal sandflats, due to physical forces such as tides, wave set-up, and density-thermal gradient.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.4
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• pp.445-450
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• 2002

A series of 29 sampling with a 330 ${\mu}$m and a 64 ${\mu}$m mesh size of nets was conducted at a fixed station in Ilkwang Bay, southeast cost of Korea, from Oct, 2, 1991 to Oct. 10, 1992, to investigate the effects of mesh size of nets on biomass estimation of copepod Acartia steueri. The catch of copepodite and nauplius stages of A. steueli taken by two nets with different mesh size was different, showing that all developmental stages of A. steueri were retained on the 64 ${\mu}$m mesh net, but only $\geq$stage 4 copepodite were caught by the 330 ${\mu}$m mesh net. Abundance and biomass in each developmental stage estimated with the 64 ${\mu}$m mesh net were significantly higher than those of the 330 ${\mu}$m mesh net, except for adult female and stage 5 copepodite in female. The body length as well as the body width is likely to affect the catch of the nets. The mean biomass of A. steueli estimated with the traditional 330 ${\mu}$m net was 2.8 times lower than the value obtained with the 64 ${\mu}$m mesh net. However, the seasonal patterns of the biomass were comparable. These results suggest that accurate sampling strategr of the entire copepods assemblage including nauplii and copepodites are essential when estimating the abundance and biomass of copepods for the better understanding of the role of copepods in marine ecosystem.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.2
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• pp.288-295
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• 1998

Egg production of Acartia steueri was estimated in llkwang Bay, located in the southeastern coast of Korea. The equation, combining fecundity, temperature and chlorophyll a, obtained under the laboratory experiments, was applied to the in situ temperature and chlorophyll a for the estimation of field egg production. Mean egg size was $80.52{\mu}m$. Prosome length of adult females was not correlated with egg size. Egg production of field population ranged from 0.32 to $63.32{\mu}gC\;m^{-3}d^{-1}$ with a mean of $13.33{\mu}gC\;m^{-3}d^{-1}$, which were equivalent to $7.1\~1407.1\;eggs\;m^{-3}d^{-1}$ and $296.1\;eggs\;m^{-3}d^{-1}$, respectively. Fecundity of adult females ranged from 5.4 to $12.5\;eggs\;female^{-1}d{-1}$ with a mean of $8\;eggs\;female^{-1}d^{-1}$. Specific egg production rates ranged from 0.028 to 0.117 $d^{-1}$ with a mean of 0.064 $d^{-1}$. Considering the egg Production ($\%$ female body carbon) as a function of temperature and chlorophlrll a concentration, our results showed rather low fecundity, which might be underestimated. Probable cannibalism of egg by the adults were thought to be pan of the reason for this low estimated fecundity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.6
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• pp.842-851
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• 1998

Development and growth of Acartia steueri from Ilkwang Bay, southeastern coast of Korea, were determined under various temperatures and food condition (Isochrysis galbana and Dunaliella salina) in the laboratory. Relationship between egg hatching time ($D_E$, day) and temperature (T, $^{\circ}C$) was $D_E=744(T+3.5)^{-1.97}$. Mean hatching success was $88.4\%$ in temperature range of $8.4\~26.2^{\circ}C$. This suggests that A. steueri may be adapted to the temperature ranges in temperate regions. Post-embryonic development pattern was equiproportional rather than isochronal, with longer stage duration of copepodites than that of the nauplii. Stage duration of NI was the shortest of all developmental stages, while the duration of NII was the longest in duration of the other nauplii. Male was morphologically distinguished from female in CIV stage, and male was developed faster than female. Median development time at a given temperature was calculated from the Belehradek equation by proper multiplication of proportional constant for embryonic development. Body carbon weight at $19.1^{\circ}C$ was increased exponentially with time. Mean specific growth rate of nauplii (0.200 $d^{-1}$), except for NI stage, was not significantly different from that of copepodites (0.190 $d^{-1}$), with the lowest rate in NVI stage (0.107 $d^{-1}$), probably due to energy consumption for metamorphosis rather than somatic growth. The results suggest that although the development pattern determined in this study was not identical with Uye's result for A. steueri (e.g. Uye, 1980b), median development time may be applicable to calculate the stage duration of A. steueri in this study area.