• Ocean and Polar Research
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• v.33 no.3
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• pp.235-253
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• 2011

The annual variation of mesozooplankton community in the Jangmok harbor of Jinhae Bay was studied in relation to environmental variables. Sampling was carried out weekly from January to December 2009. During the study periods, mesozooplankton community consisted of 44 taxa and the annual mean abundance was 8308 inds. $m^{-3}$. The maximum abundance was observed to be 50043 inds. $m^{-3}$ in August and the minimum in April with 1013 inds. $m^{-3}$. Of these, Penilia avirostris, cirripedia larvae, Evadne tergestina, Acartia omorii, Oikopleura s, Paracalanus parvus s. l., Eurytemora pacifica, Podon s, Oithona s, and Acartia steueri were observed as dominant species in Jangmok bay and they also contributed to 79% of total mesozooplankton. According to non-metric multidimensional scaling (nMDS) and cluster analysis based on the mesozooplankton community data from each season, the community was divided into three groups. The first group included appearence species in winter and spring season, which is mainly dominated the copepod such as A. omorii and E. pacifica. The second and third group was composed with observed species in summer and autumn, respectively. Based on the SIMPER (similarity percentages), P. avirostris in summer and cirripedia larvae in autumn were significantly dominated. Our results indicate that although the mesozooplankton abundances in Jangmok harbor fluctuated abruptly, its annual variation was strongly influenced by water temperature.

• Ocean and Polar Research
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• v.40 no.3
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• pp.115-125
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• 2018

Production from copepodite IV to adult of two euchaetid species Euchaeta plana and Paraeuchaeta russelli was measured at the southeastern sea of Korea from April to November, 2014. The mean density was $2.0ind\;m^{-3}$ for E. plana and $4.1ind\;m^{-3}$ for P. russelli, with the high contribution of copepodite V to total density. The densities of total individuals, adult females and eggs were highest in November for both species. The mean egg production rate (EPR) was $1.7eggs\;female^{-1}\;d^{-1}$ for E. plana and $3.1eggs\;female^{-1}\;d^{-1}$ for P. russelli. Both of them showed the highest EPR in September but zero EPR in summer. The mean weight-specific EPR was $0.038d^{-1}$ for E. plana and $0.079d^{-1}$ for P. russelli. The mean total production rates of E. plana and P. russelli were $5.3{\mu}g\;C\;m^{-3}\;d^{-1}$ and $17.8{\mu}g\;C\;m^{-3}\;d^{-1}$, respectively, with the largest production in November. The mean Production/Biomass ratio was $0.06d^{-1}$ for E. plana and $0.07d^{-1}$ for P. russelli, with its peak in September for both. The total production of E. plana and P. russelli was positively correlated with the density of a copepod Oncaea venusta, rather than chl-a concentration, indicating that the two copepods might be carnivores. This study evaluates the contribution of euchaetids to the copepod community in the southeastern sea of Korea.

• Korean Journal of Environmental Biology
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• v.33 no.1
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• pp.19-26
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• 2015

Pre-monsoon dynamics of zooplankton community were investigated in the estuary of the Tamjin River flowing into the Doam Bay of the southern coast of Korea. Monthly sampling was carried out to collect zooplankters at five sites in the estuary and the river during the period between March and June 2014. Dissolved oxygen contents were low between $5.0{\sim}7.0mgL^{-1}$ in the estuary and high, 7.0~11.0, in the river. Water temperature increased gradually from 12.0 to $28.0^{\circ}C$ and pH fluctuated between the range 7.4~8.8, respectively. A total of 85 taxa consisted of 25 species of rotifer, 30 kinds of copepod, 8 species of cladoceran, six kinds of aquatic insect larvae, four kinds of decapod and two kinds of Cirripedia larvae and Polychaeta larvae and one kind of Amphipoda, Ispopoda, Appenidicularia, Nematoda and Cnidaria, and Nocticluca scintillans was occurred. Brackish copepods distributed at almost all studied sites with freshwater zooplankters being restricted to upper waters of the river. Monthly succession of Acartia spp. was observed in the estuary with the occurrence of A. hudsonica in March and April then A. omori in May and June. Zooplankton abundance showed to vary from 450 to $87,818ind\;m^{-3}$ due to the explosion of copepodite and copepod nauplius in the estuary. Species diversity indices varied between 0.6~2.3 and generally low in the estuary and high in the river. Sea water input into the river seems to affect the river biota for more than some kilometers of the upper waters of the Tamjin River.

• Ocean and Polar Research
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• v.24 no.4
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• pp.407-417
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• 2002

Species composition and abundance of zooplankton were investigated around Dokdo in the East/Japan Sea in autumn 1999 and spring 2000. Vertical and horizontal hauls of a bongo net ($300{\mu}m$ mesh size, 60cm diameter) were made to collect zooplankton sample. Surface temperature and salinity ranged from $24.2^{\circ}C\;to\;25.1^{\circ}C$, and from 32.9psu to 33.2psu in September 1999, respectively. In May 2000, surface temperatures were $13.9^{\circ}C\;and\;14.2^{\circ}C$ at stations of A1 and A8, and salinity was 34.5psu at both stations. Zooplankton community was dominated by copepods which comprised 61% (September) and 60% (May) of total numerical abundance, respectively. The next dominant groups were appendicularians (11%) and chaetognaths (9%) in September 1999, and other crustaceans (27%) and appendicularians (4%) in May 2000. The 15.7% (September) and 23.2% (May) of copepods were in the juvenile stage of copepodites. The most dominant copepods were Oncaea media (10.4%) and Clausocalanus sp. (8.2%) which preferred warm water in September. In contrast, cold-water copepods such as Pseudocalanus minutus (9.4%) and Metridia pacifica (8.0%) were dominant in May. The results of cluster analysis based on Bray-Curtis index showed that zooplankton community were classified into two groups which represented different water mass. The average abundance of zooplankton in September was 2.1 times higher than that in May, and species number of them in September outnumbered that in May by 29 species. Zooplankton community varied in associated with a characteristic of warm waters which affected marine ecosystem differently in the study area depending on seasons.

• Korean Journal of Environmental Biology
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• v.27 no.4
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• pp.425-432
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• 2009

Mesozooplankton dynamics were studied in Watan stream which flows into the Yellow Sea in Yeonggwang, Korea. Samples were collected at eight stations bimonthly during April 2006~February 2007. Mesozooplankton community was consisted of 45 taxa (8 cladocerans and 29 cope-pods). The abundance varied between the highest one ($31{\sim}127,587\;indiv.m^{-3}$) in October, and the lowest ($12{\sim}233\;indiv.m^-3$) in December. Diversity index showed to be the highest value in July (0.671) and the lowest one in August (0.368). A euryhaline species, Acartia hongi was dominant in brackish water stations (the highest abundance at $13.4^{\circ}C$ and 14.1 psu). In freshwater stations of the upstream, two cladoceran species of Polyphemus pediculus and Moina weismani occurred in high abundance in August. Dominant taxa of copepod were clustered to two or three groups mainly due to the difference of salinity gradients. Spatial distribution of mesozooplankton revealed to be determined by salinity gradients which were affected by opening and closing of the artificial dam in Watan stream.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.2
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• pp.219-226
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• 1995

A study was made of the concentration of the naturally occurring radionuclide $^{210}Po$ in seawater, plankton and fishes collected from Yongil Bay, Korea, in summer 1993. The mean value of the $^{210}Po$ concentration in sea water was determined to be about 1.9 mBq/l, with the proportion of the dissolved forms being about $46\%$. The mean $^{210}Po$ concentration factor in the centric diatom Skeletonema costatum, comprises > $95\%$ of the total phytoplankton cell number, was $7.6\times10^4$. Of five species of zooplankton examined, four species (two copepods and two mysids) had $^{210}Po$ concentrations in the range of $^{210}Po$ mBq/g dry weight. A copepod Labidocera bipinnata, however, was exceptional with a particularly high $^{210}Po$ level of 2,070 mBq/g. This indicates that L. bipinnata is primarily a raptorial feeder. The concentration of $^{210}Po$ in the pyloric caecum of pelagic fishes was 2,979-3,811 mBq/g, with the concentration factors of $3.4-4.3\times10^6$. The food chain concentration of $^{210}Po$ occurred as follows: phytoplankton < filter feeding copepods < omnivorous mysids < raptorial copepod < pelagic fishes.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.4
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• pp.415-430
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• 1996

Spatio-temporal variations in zooplankton community and ropepod indicator species were investigated along with the interaction between zooplankton distribution and environmental factors in Chinhae Bay. Zooplankton samples were monthly collected at 7 stations from February to September in 1993. A NORPAC net was vertically hauled from bottom to surface, At the same station, environmental factors such as temperature, salinity and COD (chemical oxygen demand) were measured at two different water layers, surface and bottom. In August and September, salinity declined below 30.00‰ , while eutrophic parameters such as COD showed the higher concentrations than those in other months, with higher concentrations at inner bay stations. Salinities were, however, higher at bay mouth areas. These distributional patterns were believed to be caused by input and dispersion of organic matters from nearby land. Zooplankton communities were composed of 7~14. Of these, Noctiluca scintillans was predominant and occupied 90.6‰ of total zooplankton abundance. Cladocera and Copepoda were secondly abundant taxa. Among 6 to 10 copepod species appeared, Acartia omorii and A. hudsonics were most common species during the survey months except March and September. Species diversities were greater, in general, at inner bay than outer bay. The lowest diversity index was observed in February, while the highest in July. Cluster analysis could divide the study area into 2 or 4 zones for each month. Zone 1, mouth area of the bay, was characterized by the influence of offshore waters. Zone II was mixing area. Zone III and IV seemed to be affected by nearby land.

• Journal of Korean Society on Water Environment
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• v.23 no.6
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• pp.837-842
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• 2007

This study was conducted to test the effect of residual Al on plankton community after dissolved air flotation (DAF) application. Growth rate of phytoplankton after DAF application ($0.37day^{-1}$) was about 2 times lower than that before DAF application ($0.70day^{-1}$). Under the condition of addition of nitrogen and phosphorus without light, growth rate phytoplankton in treatment without residual Al increased in difference with showing the negative growth rate in treatment with residual Al. Under the condition of light without addition of nutrient, growth rate of phytoplankton was no noticeable difference between the before and after DAF application. The relatively high settling rate (0.47 m/day) was observed in treatment after DAF application. Although the abundance of rotifer decreased, the abundance of copepod and cladoceran such as Daphnia galeata, Diaphanosoma sp. and Bosmina longirostris with relative higher grazing was no noticeable difference between the before and after DAF application. In the treatments before and after DAF application with zooplankton, growth rate of phytoplankton was $0.41{\pm}0.08day^{-1}$, $0.20{\pm}0.03day^{-1}$, respectively. This difference was in treatment after DAF application similar with those in treatments before and after DAF application without zooplankton. Those indicate that the filter-feeding effect of zooplankton on phytoplankton community may be not changed by residual Al after the DAF application. These results suggest that residual Al after DAF application be to improve water quality by inhibition of growth rate as well as increasing settling rate of phytoplankton.

• Korean Journal of Environmental Biology
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• v.20 no.1
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• pp.46-54
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• 2002

We observed zooplankton community to understand variations in the species composition and abundance in Gangjin Bay. Samples were collected bimonthly from February to November 1999 at 10 stations in Gangjin Bay of the southern part of Korea. Zooplankton communities consisted to nine taxa and mean biomass was 2,028 indiv. $m^{-3}$. The maximum abundance was observed to be 5,496 indiv. $m^{-3}$ in February and the minimum in November, 78 indiv. $m^{-3}$. Copepods dominated and most diverse in Gangjin Bay. Seasonal fluctuation in the copepod abundance varied between 42 and 4,159 indiv. $m^{-3}$. Dominant species are Acartia omorii, Centrophages abdominalis, Paracalanus indicus and A. steueri. Cladoceran also dominated and the maximum abundance was 765 indiv. $m^{-3}$ in April. A. omorii and Oithona davisae dominated in February, A. omorii, Eurytemora pacifica, Evadne nordmanni and Podon polyphemoides in April, Tortanus dextrilobatus and decapod nauplius in June, Paracalanus indicus, E. tergestina and Penitia avirostris in August and A. erythraea and P. indicus in October. In November, P. indicus and Sagitta crassa dominated.

• Ocean and Polar Research
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• v.27 no.4
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• pp.463-476
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• 2005

Mesozooplankton samples were collected to investigate the spatial distribution in the Chuuk lagoon of the Federated States of Micronesia through three surveys from 2002 to 2004. Average temperature was $28.70^{\circ}C$ in August 2002, $30.17^{\circ}C$ in October 2003 and $29.18^{\circ}C$ in July 2004 at a water depth of 2rn. Average salinity was 33.95 psu in August 2002, 33.56 psu in October 2003 and 33.77 psu in July 2004. Total rnosozooplankton consisted of 70 taxa during the study period, among which copepods were the most diverse group. Foraminiferans, radiolarians, copepods and appendicularians, which comprised about 70% of total zooplankton abundance, were important components in the zooplankton community. Within the copepod group, Acartia spp., Centropages spp. and Undinula spp. were dominant in August 2002, Acartia spp., Centropages spp., and Oithona spp. in October 2003, and Acartia spp., Undinula spp., and Oithona spp. in July 2004. Total zooplankton abundance was high around Weno Island, while low in stations located in the northern part of Weno Island. High abundances of appendicularians were found in the southern part of weno Island as well as around Weno Island. Appendicularians foraminiferans, radiolarians, Sagitta spp. and immature copepods accounted for most of the distribution pattern of the mesozzoplankton community throughout the study area. These results suggest that appendicularians may be potential food items for fish larvae around Weno Island in the Chuuk lagoon states.