• Ocean and Polar Research
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• 제32권1호
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• pp.41-52
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• 2010

Daily samples were collected during summer in order to analyse changes in the mesozooplankton community and to identify the major environmental factors that may influence mesozooplankton abundance in Jangmok Bay. A single site in the bay was sampled 47 times from July to September 2003. Mesozooplankton community, hydrographic (watertemperature, salinity, dissolvedoxygen) and biological (chlorophyll-a, ciliates densities, Noctiluca scintillans densities) factors were determined. The mesozooplankton abundance varied remarkably from 954 to $14,816\;inds.\;m^{-3}$. The six taxa of Evadne tergestina, barnacle nauplii and cypris, Paracalanus parvus s.1., Acartia omorii, Penilia avirostris and Sagitta crassa dominated numerically, contributing 86% of total mesozooplankton abundance. Stepwise multiple linear regression analysis was applied to find correlation between environmental factors and fluctuation in the abundance of dominant species and mesozooplankton. A. omorii was significantly correlated with temperature and N. scintillans densities. E. tergestina was correlated with temperature, salinity, and ciliate densities, whereas P. avirostris was correlated with temperature and dissolved oxygen. Among the environmental factors, mesozooplankton abundance correlated most strongly with N. scintillans densities. Accordingly, N. scintillans may be a key player in controlling the fluctuation of mesozooplankton abundance as a strong competitor for same food resources.

• 환경생물
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• 제38권2호
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• pp.231-247
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• 2020

The seasonal variation in the zooplankton community and hydrographic conditions were examined in three regions (inner, central, and outer regions) of Gamak Bay, Korea. Zooplankton samples were collected over a period of 12 months from January to December 2006. The hydrographical parameters of temperature, salinity, chlorophyll-a concentrations, dissolved oxygen, and chemical oxygen demand were measured. The total zooplankton density varied from 411 to 58,485 ind. m^-3, with peaks in early summer. A total of 65 taxa accounted for approximately 86.9% of the annual mean zooplankton density: Noctiluca scintillans (30.9%) Paracalanus parvus s. l.(24.3%), Acartia omorii(11.9 %), Eurytemora pacifica (5.7%), cladocerans (4.1%), cirriped larvae (3.8%), Oithona similis (3.7%), and Pseudevedne tergestina(2.5%). Copepods dominated numerically throughout the year and comprised 54.3% of the total zooplankton. Most of the dominant copepods showed a well-defined seasonal pattern. The density and diversity of zooplankton in Gamak Bay were influenced by the hydrographic environment that was subject to significant spatial and temporal variations. Multivariate statistics showed that seasonal temperature was the most significant predictor of zooplankton taxa, density, and diversity, as well as the density of dominant taxa. Our results suggest that fluctuations in the zooplankton populations, particularly copepods, followed progressive increments in the temperature and COD concentrations.

• 생태와환경
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• 제35권2호통권98호
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• pp.141-144
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• 2002

The construction of river mouth dam has prevented seawater from backwarding to upstream in Kum river estuary since 1990. Field observation on environmental factors, and zooplankton and phytoplankton dynamics have been carried out three times with two month interval in the summer and autumn in 2000 at three selected stations in Kum river estuary. Blockade of seawater flowing backward to upstream caused sharp contrast of zooplankton fauna and phytoplankton flora between upstream and downstream of the river mouth dam. Freshwater cladocerans i.e., Bosmina longisrostris and Daphnia galeata dominated in the upstream, and marine copepods of Acartia omorii and Paracalanus crassirostris occurred abundantly in downstream of the dam. Freshwater diatoms did not distributed in the downstream of the dam except Melosira varians, while marine diatom of Cylidrotheca closterium occurred in benthic waters bath in upstream and downstream of the dam. The construction of the river mouth dam seems to play an ecological role to blockade the input of marine organism into the upstream in Kum river estuary.

• Ocean and Polar Research
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• 제43권4호
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• pp.269-277
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• 2021

We investigated mesozooplankton community in the Yellow Sea in summer immediately after the typhoon passed. Total mesozooplankton density ranged from 1,323 to 6,397 ind. m^-3 and the biomass ranged from 3 to 28 mg C m^-3 by stations. The dominant species of the research area were Paracalanus parvus s.l., Oithona atlantica, Acartia omorii, Oikopleuridae, Sagittoidae juvenile and Calanus sinicus in that order. Mesozooplankton community was divided into two groups by cluster analysis : the stations located in coastal and open seas as one group, and the stations located in the middle into another group. The number of species, density and richness of mesozooplankton were significantly lower in the middle region. Mesozooplankton density and biomass were not significantly correlated with chl-a concentrations, unlike previous studies in spring and autumn. This community characteristic in summer may be due to the passing of the typhoon, or other environmental influences.

• 수산해양교육연구
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• 제26권2호
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• pp.421-429
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• 2014

We investigated the feeding ecology of juvenile chum salmon (Oncorhynchus keta) during the critical early life stage prey selectivity of juvenile chum salmon during early marine migration in Korean waters at spring 2011. Salmon juveniles and zooplanktons were collected to draw with $20m{\times}5m$ gill net and $300{\mu}m$ mesh zooplankton net at each station on 11th-13th April n 2011. Collected zooplanktons were classified to 5 Phylum, 6 Class, 9 Order 17 Species in this study. Almost 76.4-100% species were classified to Phylum Arthropoda, dominant species was a species out of Hyperia galba of Order Amphipoda, Acartia spp and Paracalanus parvus of Order Calanoida. Collected salmon juveniles were grew up to average 4.7-5.4 cm fork length and average 1.0-1.5 g wet weight in whole station. Fish stomach content (mg/salmon) was heaver to 97.4, 82.4 and 63.2 mg wet weight/salmon in ST 2, 3, 4 than 20.4, 18.9 mg/salmon of ST 1, 5, because there are fish (sand eel, Hypoptychus dybowskii) and Krill (Euphausia) as prey in salmon stomach in ST 2, 3, 4. And ST 2, 3, 4 and 5 were dominated by Amphipoda as Hyperia galba, Themisto japonica and Gammarus sp., but ST 1 was dominated by copepod, because of absence of Amphipoda in the station. Therefore small Amphipoda as Hyperia galba was good prey for just released salmon juvenile in nature.

• 환경생물
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• 제24권2호
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• pp.126-137
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• 2006

점등 효과에 따른 동물플랑크톤 군집동태의 변화를 관찰하기 위하여 통영 바다목장 해역내 한국해양연구원 가두리 설치 지역에서 2004년 7월부터 2004년 8월까지 채집을 실시하였다. 점등 효과를 알아보기 위한 시료 채집은 야간에 점등구간에서 또한 자연상태의 동물플랑크톤 군집과 비교분석을 위하여 같은 시간에 인접 지역에서 점등에 영향을 받지 않는 장소를 선정하여 점등 시료와 동일한 방법으로 채집하여 비교 분석하였다. 조사기간 중 출현한 동물플랑크톤은 종 수준까지 동정한 21종을 포함하여 총 43개 분류군이었다. 불을 밝힌 점등구에서의 출현 분류군수는 비점등구에 비해 많은 개체수가 나타났으며, 두 구간에서의 동물플랑크톤 평균 출현량에서도 비점등구에 비해 점등구에서 약 $3\sim166$배 높은 출현량을 나타내었다. 본 연구에서 점등(불빛)으로 유집되는 동물플랑크톤 군집의 반응양상은 2개로 대별하여 특정지을 수 있는 것으로 나타났다. "A"그룹은 조사시기별 높은 출현 빈도를 나타낸 종들로 불빛에 명확한 양주광성(photo-positive)종들로 구성됨을 알 수 있었다. "B"그룹에 속하는 종들은 약간의 차이는 있으나, 대부분이 점등(불빛)에 소극적으로 반응하는 음주광성(photo-negative)으로 나타났다.

• 환경생물
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• 제24권4호
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• pp.329-336
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• 2006

하계 완도 연안역에 출현하는 동물플랑크톤의 군집양상을 연구하기 위하여 8월 30일에 6개의 정점에서 NORPAC net를 이용하여 수직 채집한 자료를 사용하였다. 동물플랑크톤은 37개 분류군이 출현하였으며,출현 개체수는 $147{\sim}1696\;indiv.\;m^{-3}$의 범위를 나타냈다. 우점종은 E. tergesrina, A. pacifica, P. parvus s. 1, 십각류 유생, S. crassa로서 전체 출현 개체수에 90%이상을 차지하였다. 동물플랑크톤은 세 개의 군집으로 구분되어졌으며, 소안도 인근해역의 A군집, 소안도와 청산도의 중앙부해역인 B군집, 청산도 북부해역의 C군집으로 구분되었다. 군집으로 구분되는 세 그룹간의 동물플랑크톤의 종조성과 출현 개체수는 유의한 차이를 나타냈다(p<0.05). 결과적으로 하계 완도 연안역의 동물플랑크톤 분포는 대마난류와 황해저층냉수의 확장에 의해 지배되고 있음을 암시하고 있다.

• Ocean and Polar Research
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• 제23권3호
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• pp.245-253
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• 2001

To investigate the community structures and the their seasonal variation of phytoplankton and zooplankton, a study was conducted at 6 selected stations during the period from April 1999 to October 2000 in the marine ranching ground off Tongyeong. One hundred ninety species of phytoplankton were identified, including 146 diatoms, 38 dinoflagellates, 4 silicoflagellates and 2 euglenophytes. Phytoplankton standing crops varied extensively by months and stations, ranging from $3.0{\times}10^4\;cells/l\;to\;1.0{\times}10^6\;cells/l.$. The dominant species varied from the vertical distribution as well as seasonal changes. In April and July 1999, Skeletonema costatum and Ceratium fusus were predominant in both the surface and the bottom water columns. Leptocylindrus danicus was the dominant species in April and June 2000, and Thalassiosira spp. were also predominant in bottom waters in June 2000. Pseudonitzschia pungens and Chaetoceros spp. were the dominant species at both surface and near bottom waters in August and October 2000, respectively. Zooplankton abundance was comparatively high in April and July in 1999, and April, June, and October in 2000, but extremely low in November 1999. The density of dominant zooplankton was higher in 2000 than in 1999. Copepods were the most predominant group except for July 1999 when the bivalve larvae showed extremely high abundance. Acartia omorii and Oithona similis were the dominant or subdominant copepod species mainly in April 2000, and June/July, while O. davisae and O. plumifera had peaks in August and October 2000. Corycaeus affinis and Paracalanus sp. also showed higher peaks in April and June (or July), even though they occurred in all sampling time. Centropages abdominalis occurred abundantly only in April 1999. Oikopleura dioica, a gelatinous zooplankton, was another important zooplankton, showing high density in all samples except in July 1999.

• 한국환경과학회지
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• 제18권1호
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• pp.21-32
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• 2009

The short-term variations of the mesozooplankton community structure were investigated in Gamak Bay during summer season, 2006. The study was based on a comprehensive survey constituting from 12 stations on June 19, July 28, August 4, and August 29, respectively. Mean of temperature and chlorophyll ${\alpha}$ concentrations in the surface layer were significantly higher than those in bottom layer, and those concentrations were significantly higher in the inner bay than those in the outer bay. A total of 40 taxa including 19 copepods were observed in Gamak Bay during summer season. Mean abundance of total mesozooplankton varied from 1,859 to 26,111 indiv. $m^{-3}$. The dominant species were Noctiluca scintillans, Penilia avirostris, Evadne tergestina, Paracalanus parvus s. 1., Acartia omorii and Cirriped nauplii and cyprii in Gamak Bay, and they contributed 90% of mean abundance of total mesozooplankton. Noctiluca scintillans was high after the rainfall. Cluster analysis showed that the mesozooplankton community could be divided into 4 distinct groups, indicating rapid change of the community in the short-term of this survey. The relative contribution of each group of the N. scintillans, P. avirostris, E. tergestina, and P. parvus s. 1. showed differences during the phytoplankton bloom period. The mesozooplankton community compositions were highly associated with water temperature, and salinity in physical conditions, and food organisms affect short-term variations in mesozooplankton composition. Interestingly, protozoa N. scintillans, and Cladocera appeared to be one of the key organisms to extinguish the phytoplankton bloom. Therefore, this study suggests that N. scintillans, and Cladocera could be a key player to control the mesozooplankton community structure during summer season, 2006.

• 환경생물
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• 제31권3호
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• pp.192-203
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• 2013

금오열도 연안에서 출현하는 동물플랑크톤 계절별 군집의 변동 양상을 이해하기 위해 그들의 출현 양상과 환경인자를 2003년 8월부터 2004년 4월까지 계절별로 실시하였다. 조사기간 동안 출현한 동물플랑크톤은 모두 44개 분류군이 출현하였고, 출현 개체수는 15~$28,183inds.\;m^{-3}$의 범위를 보였으며, N. scintillans가 가장 우점 하는 분류군이었다. 동물플랑크톤 주요 분류군은 N. scintillans를 포함하여 P. parvus s. l., A. omorii, Oithona spp., Aidanosagitta crassa, 십각류 유생, 요각류 전기유생, 요각류 후기유생이었다. 종 다양도 지수는 여름철과 봄철에 낮게 나타난 반면에 가을철과 겨울철에는 높게 나타났다. 결과적으로 금오열도 연안의 동물플랑크톤 출현양상이 계절에 따른 수온, 염분, Chl. a 농도와 함께 일부 내만종들에 기인하여 변동될 수 있음을 시사하고 있다.