• Ocean and Polar Research
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• v.28 no.2
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• pp.79-94
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• 2006

Spatio-temporal patterns in the zooplankton communities, physicochemical environmental factors, and dominant species were examined in Camak Bay from April, July, September, and November, 2003. A total of 40 taxa were sampled with a mean abundance of total zooplankton ranging from $270{\sim}1,803inds/m^3$. The most abundant species was Acartia erythraea, followed by Eurytemora pacifica, Podon polyphemoides, A. omorii, and Paracalanus parvus s. 1 during the study period. Multivariate analysis revealed significant differences in community structure among three regions: the middle part of the sampling area (B), sites 1, 2 (A) and other sites (C). The number of species and diversity (H') varied significantly among the three regions (p<0.05), but no differences in the mean abundances were observed (p>0.05). In order to investigate factors affecting the correlations between the abundance of dominant species, all zooplankton and environmental factors ware calculated using a correlation analysis. Of these, the abundance of dominant taxon showed positive correlation with seawater temperature, salinity and dissolved oxygen (p<0.05). In statistical analysis showed that the environmental factors influencing the variation of the communities ere predominantly temperature, salinity, and dissolved oxygen.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.22 no.4
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• pp.1-20
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• 1986

Physical, chemical and biological surveys on Nakdong River estuary were made from October, 1985 to September, 1986. 1. For all the seasons except summer, the sea surface temperature in northwest area of the line which linked from Seo Island to Jisim Island was I-2$^{\circ}$C lower than in southeast area, but in summer the sea surface temperature in northwest area was I-2$^{\circ}$C higher than in southeast area. On the contrary, bottom temperature of coastal area was 1$^{\circ}$C higher than that of oceanic area except winter. 2. Surface salinity in summer and fall has minimum value of 1. 9%0 and maximum value of 32.9%0. This large variation was caused by the runoff of the Nakdong River. Effect of less saline Nakdong River water in northwest area of the line which linked from Seo Island to Jisim Island was greater than in southeast area. A strong current rip always formed near this line. 3. The yellowish-green colored zone was observed in the Nakdong River estuary throughout the year by influence of river discharge. The characteristics of the water quality in the zone have shown that the water color was grade 7 by the Forel water-color meter, transparency was less than 4 m, and concentration of suspended solids was more than 5 mg/1. This water body was in the state of eutrophication in terms of chlorophyll-a and inorganic nitrogen concentration during summer season. 4. During the study period, total 276 taxa were identified. Most of them were diatoms and dinoflagellates which consisted of 97.5%. The component ratio of the above two groups was 84.4% and 13.1 % respectively. Diatoms were plentiful in December and dinoflagellates in July. Dominant species were Nitzschia seriata in October, Thalassiosira rotula in December, Skeletoncma costatum in April, and Nitzschia longissima in July. 5. A total of 47 zooplankton taxa was identified from the samples collected. Copepods were numerically the most important components of zooplankton communities in the study area. The domir:ant copepod species were Paracalanus parvus, Acartia clausi and Temora turbinata. Noctiluca scintillans was the next important component. The other zooplankton with minor abundance were Cladocera. Sagitta spp., Cnidaria, Mysidacea, Lucifer spp. and Amphipoda. 6. During the study period, fishes from 47 families and 87 species were sampled in th~ study area. The four most abundant fish species were Rep~mucen//'s valencicnnei, Leiognathus n~cha!is, Amblychaeturicllthys hexanema and Sardirel/a zun:zsi. The fish species of the secondary importance in abundance were Cynoglossus joyneri, Sillago sihama, Engra~lis japonicus, Encdrias nebulos'l, Acanthogobius flavimanus, Trichiurus lepturus, LiParis tanai/ai, Cynagloss//'s interruptus, Aj)ogon line:z!us, Thrissz la 1l.'1la!ensis, and Limanda yokohamac.

• Ocean and Polar Research
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• v.40 no.4
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• pp.213-222
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• 2018

We investigated seasonal variations in the abundance of the adults and the resting eggs of copepods to understand the role of copepod resting eggs for maintaining their population inhabiting the coastal area of Dadaepo, Korea. Adults and resting eggs of copepods were collected bi-monthly with a conical net (45 cm mouth diameter, $330{\mu}m$ mesh size) and van Veen grab ($0.1m^2$ area), respectively, from October 2016 to September 2017. The species of resting eggs were identified using mtCOI gene. The mean abundance of copepods was highest in October ($3686{\pm}1190inds{\cdot}m^{-3}$) and lowest in January ($176{\pm}60inds{\cdot}m^{-3}$) with the dominance of Paracalanus parvus s.l.. Among copepod producing resting eggs, Acartia omorii and Centropages abdominalis were dominant. The mean abundance of resting eggs was the highest in July ($9148{\pm}6787eggs{\cdot}m^{-2}$) and the lowest in October ($530{\pm}348eggs{\cdot}m^{-2}$). Most of the collected resting eggs were identified as A. omorii's. The mean abundances of A. omorii adults and resting eggs were highest in July, and both abundances fluctuated in a similar pattern except in September. In September, A. omorii adults were observed in a state of low abundance, while their resting eggs occurred in a state of high abundance. These results suggest that A. omorii maintain their population by producing a large quantity of resting eggs, particularly diapause eggs, before the seawater temperature rises. These eggs would hatch and be newly recruited to their population when the environmental condition becomes favorable.

• 한국해양학회지
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• v.8 no.1
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• pp.33-45
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• 1973

Plankton samples used for the present study were collected by the NORPAC net during the CSK cruises in the Korean waters in March and August, 1967. Regional and seasonal variations in the zooplankton biomass (wet weight, mg/㎥) were noticed in the Korean waters. In March the highest biomass, 130mg/㎥ on the average, occurred in the southern part of Japan Sea, but the lowest biomass of less than 50mg/㎥ occurred in the Yellow Sea and the western sea of Cheju Island Contrally, in August, the average biomass of 120mg/㎥ was measured in the Yellow Sea, the western sea of Cheju Island and the coastal waters of southern Korea, while the biomass of Japan Sea was the lowest of the regions surveyed. In comparison with the zooplankton biomass, total number of zooplankton per cubic meter of water strained also showed regional and seasonal fluctuations. In general, variations in the number of zooplankton specimens follows the same trend as in the biomass. The largest number, up to 800mg/㎥ on the average, occurred in the southern part of Japan Sea in March and the lowest number, less than 200mg/㎥ occurred in the Yellow Sea and the western sea of Cheju Island. In August, as shown by the biomass fluctuations, the largest number of zooplankton 850mg/㎥ on the average occurred in the Yellow Sea, the western sea of Cheju Island and the coastal region of southern Korea. But the lowest number of less than 500mg/㎥ was found in the Japan Sea. Among the various groups of zooplankton examined, the following were dominant components of the zooplankton population: Copepoda, Chaetognatha, Siphonophora, Euphausiacea, Cladocera, Appendicularia, and Amphipoda. The zooplankton conposition was significantly differed between the Japan Sea and Yellow Sea. Copepods which usually occupied over 66% in the Japan Sea and thd Korean Strait samples occupied only 42% of the catches in August, while cladocerans and chaetognaths were relatively abundant, i. e., 15 and 18% of the total organisms. The most dominant species of copepods and chaetognaths were Paracalanus parvus, Oithona similis, Acartia clausi, Calanus helgolandicus, Sagitta enflata, S. bedoti, S. elegans and S. crassa.