• 한국어류학회지
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• 제18권3호
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• pp.178-183
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• 2006

진동만 잘피밭에 서식하는 그물코쥐치의 먹이습성의 일별변화를 조사하였다. 출현한 그물코쥐치는 1.6~4.3 cm SL의 범위였으며, 주요 먹이생물은 단각류에 속하는 옆새우류, 잘피, 갯지렁이류, 그리고 미삭동물이었다. 그물코쥐치의 먹이습성의 일별변화는 뚜렷하였다. 낮에는 잘피와 옆새우류를 주로 먹은 잡식성을, 밤에는 옆새우류, 갯지렁이류, 그리고 미삭동물을 주로 먹는 육식성을 나타내었다. 이와 같은 결과는 낮보다는 밤에 이들 먹이생물의 활동이 활발하여 그물코쥐치가 섭이하기가 용이하였던 것으로 판단된다. 또한 그물코쥐치의 섭이활동은 저조보다는 고조에 활발하였다.

• 한국어류학회지
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• 제31권1호
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• pp.54-61
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• 2019

꼬치동자개 Pseudobagrus brevicorpus의 일주기활동과 식성에 관한 연구를 낙동강 지류인 대가천에서 실시하였다. 일주기 활동은 일몰 직후와 일출 전에 2회에 걸쳐 일어났다. 주로 하천의 중층대에서 활동을 하며 먹이생물이 발견하면 접근하여 흡입하는 행동을 취했다. 연령은 3개 그룹으로 구분되었고 위내용물 중 상대중요성지수 (index of relative importance, IRI)가 1%를 초과하는 먹이생물은 하루살이목 (Ephemeroptera) 80.8%, 파리목 (Diptera) 8.6%, 날도래목 (Trichoptera) 8.5% 순으로 나타났다. 또한 모든 연령군에서 하루살이목이 매우 중요한 먹이생물이었고, 성장함에 따라 먹이생물의 크기가 증가하였다.

• Animal cells and systems
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• 제14권4호
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• pp.297-303
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• 2010

To document the basic ecological aspects of Chaoborus species, which has never been reported in Korea, we attempted to identify the species, to monitor seasonal and vertical dynamics, and to elucidate trophic relations of the species in Sang-Chun reservoir. Using morphological characteristics, we identified the collected samples as C. flavicans. Also, we compared the distribution of C. flavicans, Daphnia rosea and chlorophyll a to observed seasonal dynamics. The increase of C. flavicans was observed 1-2 weeks after the increase of D. rosea. Survey of diel vertica migration patterns in the summer season showed that C. flavicans were in hypolimnion at daytime, but moved to the epilimnion at night. Finally, to determine trophic relationships in Sang-Chun reservoir, additional studies on the food web were undertaken by stable isotope analysis. Chaoborus flavicans I-II instars appear to be filter feeders based on carbon isotope values. Trophic levels of C. flavicans III-IV instars were shown to be higher than other zooplankto based on nitrogen isotope values.

• 한국어류학회지
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• 제29권4호
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• pp.267-271
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• 2017

본 연구는 여름철 동해 남부 연안에 출현하는 청어 유어 301개체의 일섭식율 변동을 조사하였다. 어류 시료는 여름철에 3시간 간격으로 24시간 동안 소형 저인망을 이용하여 채집하였다. 청어 유어의 공위율(ratio of empty stomach), 만복도(stomach fullness), 위내용물중량지수(stomach contents index, SCI), 만복도지수(stomach fullness index, IF)는 낮과 밤의 변화에 따라 뚜렷하게 변동하였다. 공위율은 밤에 높았지만, 다른 지수들은 낮에 높아지는 경향을 보였고, 일몰 직전에 가장 높은 값을 보였다. 낮 동안 청어 유어의 위내용물은 요각류(Copepoda)와 난바다곤쟁이류(Euphausiacea)로 구성되어 있었고, 자정 근처에는 거의 소화되어 확인이 어려운 먹이생물로 구성되어 있었다.

• 한국수산과학회지
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• 제48권5호
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• pp.752-759
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• 2015

We examined the feeding habits of larval Konosirus punctatus using 165 specimens collected from May to August 2011 in the Nakdong River estuary, Korea. We found that larval K. punctatus [3.9-8.4 mm notochord length (NL)] are carnivorous, consuming mainly rotifers. Their diet also included small numbers of rhizopods, tintinnids, euglenoids, copepods, larval bivalves, dinoflagellates, diatoms, and unidentified materials. To evaluate ontogenetic changes in dietary composition, we split the larvae into three size groups: < 5 mm, 5-6 mm, and > 6 mm NL. The smallest size group frequently preyed on rhizopods. As NL increased, the number of rotifers increased relative to those of rhizopods. Larvae also showed bimodal feeding for feeding incidence, with peaks in the midafternoon and at midnight, while the mean number of prey per individual peaked at 18:00-19:00 h.

• 수산해양기술연구
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• 제53권1호
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• pp.107-113
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• 2017

The feeding habits of larval (5.0~27.0 mm SL) Clupea pallasii were examined and 1,523 individuals were collected from November 2010 to March 2011 in the coastal water of Eastern Jinhae Bay, Korea. Larval C. pallasii were fed mainly on copepods that constituted 55.2% in IRI. Monogeneans were the second largest prey component, another prey items tintinnids, cladocerans and ostracoda. The results of analysis in ontogenetic changes exhibit high during the daytime, two small size classes (${\leq}10mm$, 10~15 mm) mainly fed copepods. while the percentage of coperpods decreased, monogeneans ratio increased in 15~20 mm size class. Feeding rate in diel difference of larval C. pallasii were high during the daytime.

• 한국수산과학회지
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• 제48권4호
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• pp.498-506
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• 2015

We examined the feeding habits of larval Clupea pallasii using 148 specimens collected from December 2010 to April 2011 in the Nakdong River estuary, Korea. We found that larval C. pallasii [8.3-26.0 mm NL (notochord length)] are carnivorous, consuming mainly copepods, rotifers, cirripeds, and free-living flatworms (Macrostomida). Their diet also include small quantities of shrimp nauplii, tintinnids, cladocerans, and larval bivalves, among other food sources. To evaluate ontogenetic changes in dietary composition, we split larvae into four size groups: 8-12 mm, 12-16 mm, 16-20 mm, and > 20 mm NL. Rotifers were the most important prey items for the smallest group, but all other groups predominantly consumed copepods. The largest group frequently preyed on rotifers, cirripeds and flatworms, in addition to copepods. Larvae also showed bi-modal feeding, with peaks in the late afternoon and at midnight, wherein the mean number of prey per individual peaked at 1,800-1,900 h.

• 한국해양학회지
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• 제27권1호
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• pp.11-18
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• 1992

요각들은 Calanus sinicus와 Acartia clausi(A. omorii)의 먹이섭취 양상을 파악 하기 위하여 식물 플랑크톤의 농도변화와 시간경과에 따른 먹이섭취율 및 여과율의 변 화를 실험실에서 조사하였다. 두종의 요각류들의 여과율은 먹이농도가 증가에 따라서 감소했으며, 평균 여과율은 C. sinicus가 2.42 ml/copepod/hr,이고, A. clausi가 3.37 ml/copepod/hr. 이였다. 먹이섭취율은 먹이농도의 증가에 따라 다소 변동은 있지만 수 평적으로 일정하게 유지되는 경향을 보였다. 시간에 따른 요각류들의 여과율은 주기성 을 보이지 않고 전반적으로 감소하는 경향을 보였으나 A. clausi 는 어떤 시간의 경과 후 증가하는 경향을 보였다. 결과적으로 신물플랑크톤의 농도변화에 따른 요각류의 먹 이섭취율과 여과율의 경향은 유사하게 나타났지만, 측정된 값들은 다소 차이를 보였 다. 그리고 시간경과에 따른 조사에서 두종의 요각류들은 불연속적인 포식활동을 전개 하는 것으로 나타났다.

• Fisheries and Aquatic Sciences
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• 제14권4호
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• pp.411-416
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• 2011

We investigated the nutritional status of the melania snail (Semisulcospira gottschei) using RNA/DNA ratios to evaluate the effect of feeding conditions (artificial versus natural) on the reaction times of the snails in a time course following starvation. In the short experiments (48 h), the RNA/DNA ratios of the artificial feeding groups were significantly higher than those of the natural groups. While two RNA/DNA ratio peaks were observed in the artificial food group during daytime, the natural food group showed a higher ratio at night. Under starvation conditions, the RNA content decreased whereas the DNA content was constant. The RNA/DNA ratios of the freshwater snail in both groups dramatically decreased after starvation and remained constant until the end of the experiment. We verified that the RNA/DNA ratio serves as an index of nutritional condition with respect to the effect of dietary differences. These results are important for understanding optimized aquaculture rearing conditions for this important commercial freshwater snail.

• 환경영향평가
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• 제21권6호
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• pp.879-891
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• 2012

The objective of this study was to evaluate seasonal patterns and diel variations of fish movements in the Juksan Weir which was constructed in 2010 at the down-stream of Yeongsan-River watershed. For this study, we monitored day-and-night movement(24 Hr cycle) and seasonal fish migration(June ~ August) patterns in 2011 along with species compositions and abundances depending on the locations of the traps within the fishway. Total number of species sampled was 14 and the total number of individuals was 1,263 with only the size-fractions(as total length) of the fish < 20 cm during the study. Seasonal analysis of fish movement in the fish way showed that highest frequency in the movement occurred in June - July, which is closely associated with a spawning peak season. The most dominant species using the fishway was Squalidus chankaensis tsuchigae, and this species turned out to be 26.9% of the total in the use rate of fishway. Daily monitoring of fish movements showed that most frequent movements occurred between 18:00 PM and 21:00 PM when the fish have a feeding time generally. The migratory fish were not found in the fishway during the study. Mean current velocity during the study $0.42{\pm}0.02ms^{-1}$(n = 42), and there were no significant statistical differences(p > 0.05) among the daily and monthly velocities in the fishway. The use rate of fish passage, in terms of fish species, was 48%, compared with total sampling of fish species(29 species) at the down-river regions during the same period, indicating a low use rate. Further continuous long-term monitoring should be conducted to evaluate the impacts of the weir construction in the river.