• Korean Journal of Environmental Biology
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• v.23 no.4
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• pp.367-373
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• 2005

We conducted a year-long survey in 2000 to examine seasonal fluctuations in the abundance of the demersal copepod Pseudodiaptomus sp., the dominant copepod in the Seomjin River estuary, where the spring tide strongly affects changes in salinity gradients. Pseudodiaptomus sp. was found throughout the year in the entire range of salinities measured, but most individuals appeared at oligohaline conditions below 5.0 psu, and less than $2\%$ were observed in polyhaline conditions above 18.0 psu. The peak abundance occurred during autumn in oligohaline waters, and the density was relatively low during the rainy season in summer. In spring and autumn, copepodites were most abundant in oligohaline waters, although they were also fairly abundant in mesohaline conditions $(5\~18\;psu)$. Females with egg sacs appeared in oligo- and mesohaline waters during spring and autumn but were seldom found in polyhaline conditions throughout the year. Our results indicate that, despite the strong physical influence of the tide, Pseudodiaptomus sp. can manipulate its position to remain at its preferred salinity. We also found that spawning mainly occurred in oligohaline waters twice a year.

• Journal of the korean society of oceanography
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• v.38 no.4
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• pp.211-215
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• 2003

A huge freshwater reservoir (ca. 12,000 ha) will be created when the construction of a 33­km dike on a huge mud flat of the Saemankeum areas is established. A large quantity of freshwater will emerge to the adjacent sea from the reservoir through two big gates. Marine organisms outside the dike are expected to frequently experience low salinity waters. To investigate the salinity effects on the dominant metazooplankton in the coastal waters off Saemankeum areas, we measured the survival (Survival 1H and Survival 24H) of 11 different taxa (the copepods Acartia omorii, A. pacifica, Calanus sinicus, Centropages abdominalis, Paracalanus indicus, Pseudodiaptomus inopinus, Tortanus forcipatus, and a hydromedusa, and barnacle nauplius, polychaeta larva, and a chaetognath Sagitta sp.) at salinities of 0, 5, 10, 15, 20, 25, 30, 35, and 40 psu when the organisms were exposed for 1 and 24 h, respectively. Survival 1Hs of P. inopinus and barnacle nauplius were 100% between 5 and 35 psu, while they were 0% at salinities of 0 and 40 psu. Survival 1Hs of A. omorii and A. pacifica, P. indicus, T. forcipatus, and polychaeta larva were 100% at $salinities\;\geq\;10$ psu, while they were 0% at lower salinities. Survival 1Hs of a hydromedusa and Sagitta sp. were 100% at $salinities\;\geq\;15$ psu, while they were 0% at lower salinities. Survival 1H of C. abdominalis and C. sinicus was 100% at $salinities\;\geq\;20$ psu, while they were 0% at lower salinities. Survival 24Hs of A. omorii, A. pacifica, C. abdominalis, barnacle nauplius, and polychaeta larva were the same as Survival 1 Hs at the same salinity, while those of the other metazooplankton were lower than Survival 1Hs. The results of the present study suggest that low salinity water emerging from big gates may cause the death of the metazooplankton, but the salinities at which death of the metazooplankton occurs may differ by species.

• Korean Journal of Environmental Biology
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• v.36 no.4
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• pp.525-537
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• 2018

The Korean coast is divided into the West Korea Coastal zone (WKC), the South Coastal zone of Korea (SCK), the East Korea Coastal zone (EKC), and Jeju Coastal zone of Korea (JCK). Each coastal zone has different marine environment characteristics. This study analyzed zooplankton data of KOEM (Korea Environment Management Corporation) collected in the Korean coastal waters the spring and summer of 2015 and 2016. In spring, water temperature was lowest in the JCK, and gradually increased in the order of EKC, SCK, and WKC, while in summer lowest in WKC and increased in the order of EKC, SCK, and JCK. Salinity was lowest in WKC which had many rivers flowing inland, and increased in the order of SCK, EKC and JCK in spring. In summer it was lowest in JCK and increased toward WKC, SCK, and EKC. In summer, Chlorophyll-a concentrations were generally low, but was lowest in JCK in spring. In the study area, a total of 77 species occurred, of which 50 species did in spring and 65 species in summer. The number of species was lowest in JCK and highest in SCK in spring and summer, respectively. Paracalanus parvus s. l. was the most dominant species or the second dominant species in Korean coastal areas in spring, but it was predominant in summer. In addition, in spring Acartia hongi, Calanus sinicus, Oithona similis were predominant in WKC, Oithona similis and Corycaeus affinis in SCK, O. similis and Corycaeus sp. in EKC, C. affinis and O. setigera in JCK. In summer Corycaeus spp., O. similis, A. hongi, Tortanus forcipatus were predominant in WKC, C. affinis, Pseudodiaptomus marinus in SCK, O. similis, A. omorii, Corycaeus sp. in EKC, and A. steueri, A. pacifica, Oithona sp., C. sinicus in JCK. The copepod community in the Korean coastal areas were classified into four areas, WKC-western SCK, eastern SCK, EKC and JCK according to differences in environmental factors such as water temperature, salinity, Chl-a concentration, and suspended matter concentration of each coastal area.