• Ocean and Polar Research
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• v.44 no.3
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• pp.261-267
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• 2022

We derived a length-weight relationship for Calanus sinicus off Busan, Korea in spring to estimate the biomass of the C. sinicus population around Korean waters, and compared it with the previously derived equations. The developmental stages and prosome length of C. sinicus used in the relationship ranged from 1,376-1,540 ㎛ for copepodite 4 (CIV), 1,753-1,971 ㎛ for copepodite 5 (CV), and 2,160-2,283 ㎛ for adults (CVI). Dry weight and carbon content were measured from a total of 26 replicates. Length-weight relationships derived in the present study are as follows: log C = 3.342 log PL - 9.449, log DW = 3.394 log PL -9.219, where C is carbon content (㎍), DW is dry weight (㎍), and PL is prosome length (㎛). When comparing the present regression equation of length-weight for C. sinicus with the previous one, our regression equation showed an average carbon estimate to a given range of mean prosome length. The length-weight relationship of C. sinicus in the present study can be used to better estimate the biomass of the C. sinicus population in the coastal waters of Korea.

• Journal of the korean society of oceanography
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• v.33 no.1-2
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• pp.28-34
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• 1998

Variations in abundance, size and population structure of Calanus sinicus were studied in the southern waters of Korea in connection with hydrographic conditions during 1991-1992. Abundance was high in April and low in August. This species was concentrated inshore of a coastal temperature front, or around the temperature front in April. The 1st-3rd copepodites dominated in February and April, and adults in August. The mean population stages in February and April were younger than those in other survey months. This suggests that this species mainly reproduced during winter-early spring. In prosome length, the 1st-4th copepodites were larger in April than in other survey months, and the 5th copepodite and adult were the largest in February. Mean prosome length of C. sinicus showed weak inverse relationship with sea water temperature, but it was not statistically evidenced.

• Korean Journal of Environmental Biology
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• v.36 no.4
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• pp.456-462
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• 2018

The purpose of this study was to assess cross-generational effects of bisphenol A exposure in benthic copepods, Tigriopus west. Nauplii (<24 hours old) were exposed to graded concentrations of bisphenol A, and toxicity end-points such as survival, development, sex ratio, and fecundity were measured. $F_1$ generations were grown under innoxious conditions, and similarly assessed. Significant differences were observed in development of nauplii and copepodites, between exposed and non-exposed copepods; however, there were no differences in survival of nauplii or copepodites, sex ratio, or brooding rate in parental generation. In contrast, in the $F_1$ generation, there were significant differences between the control group and exposed group in survival and development of nauplii. Length, width, and biomass of parental and $F_1$ generations were reduced in the exposed group compared to the control group. In addition, some deformities, such as swelling of the prosome, abnormally shaped egg sac, and dwarfism were observed after exposure to bisphenol A. So, our study demonstrates that a cross-generation toxicity test and monitoring of morphological deformities in harpacticoid copepods, can be useful for development of potential bioindicators for environmental monitoring, and assessment of chemical impact.

• 한국해양학회지
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• v.28 no.3
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• pp.202-211
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• 1993

SEM and LM studies were made to examine the frustule of the marine epizoic diatom Pseudohimantidium pacificum Hustedt & Krasske and to examine the variability of frustule morphology. The length of the apical axis and the transapical axis were similar to other reports. but Number of labiate processes showed a variation. the Number of striae of Korean specimens were similar to those of other regions, but the areolae shape of striae showed elliptical type. Pseudohimantidium pacificum were palnktonic, tychopelagic or epizoic attached to the prosome, the genital segment and abdomen of corycaeus affinis. this species was newly recorded I Korean waters and the biogeographic boundary of this species can therefore be extended to the northern Pacific Ocean.

• 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.