• Fisheries and Aquatic Sciences
• /
• 제22권1호
• /
• pp.4.1-4.10
• /
• 2019

Russian sturgeon (Acipenser gueldenstaedtii) is commercially important in Korea because its caviar is highly prized. Although the early ontogeny of the species has been described, behavioral modifications in response to various light intensities or diel photoperiodicity patterns have not been studied extensively. The objective of the present study was to examine the behavioral characteristics of hatchery-produced A. gueldenstaedtii prelarvae over a diel photoperiodic cycle. During a diel light cycle comprising 16 h of daylight (450 lx), 4 h of dim light (10 lx), and 4 h of darkness (< 1 lx), newly hatched A. gueldenstaedtii prelarvae exhibited negative phototaxis in daylight (day 0-day 2), and this early behavior was not significantly affected by changes of light intensities. Rheotactic and non-rheotactic aggregation into schools was typical between days 3 and 6. Under the diel light cycle conditions described, rheotaxis was not influenced by environmental light intensity as much as non-rheotactic schooling behavior. Post-schooling behavior, which progressed from day 7 to day 8, did not change significantly during the diel light cycle. The data from the present study could be of practical value in developing a visual guide for assessing the fitness and quality of Russian sturgeon prelarvae under diel light cycle conditions in hatcheries.

• 한국수산과학회지
• /
• 제41권2호
• /
• pp.113-118
• /
• 2008

Diel rhythm of oxygen consumption (OC) of the starry flounder Platichthys stellatus was measured at different water temperatures in a closed recirculating seawater system with a respiratory chamber. The fish consumed 70.5, 79.7, and 90.6 mg $O_2/kg/hr$ at 15, 20, and $25^{\circ}C$, respectively, showing a linear increase in OC with water temperature. The OC of fish showed a clear diel rhythm, with lower values during the day and higher values at night, in accordance with the light (09:00-21:00) and dark (21:00-09:00) phases of the diel cycle (12L:12D) in water at 15 and $20^{\circ}C$. However, the OC of the fish showed an unclear diel rhythm with the light and dark phases of the diel cycle at $25^{\circ}C$. The respective OC at 15, 20 and $25^{\circ}C$ was 63.8, 72.4, and 88.4 mg $O_2/kg/hr$ during the light phases and 77.2, 87.1, and 92.8 mg $O_2/kg/hr$ during the dark phase. The starry flounder is thought to be a nocturnal fish with a higher OC at night, while it rests during the day. Its OC was the most stable in the light, when it did not feed. Consequently, the night-time OC is the active OC and the day-time OC is the resting OC in the starry flounder.

• 한국동물생명공학회지
• /
• 제35권3호
• /
• pp.245-257
• /
• 2020

Behavioral response to a diel photoperiodicity (500 lx for 16 h, 5 lx for 4 h and < 0.5 lx for 4 h) and phototactic characteristics in dark conditions were examined with Siberian sturgeon Acipenser baerii (Chondrostei, Actinopterygii) prelarvae. Siberian sturgeon prelarvae represented both qualitative and quantitative changes in their behavioral patterns according to different light intensities in a diel photoperiodicity. Under daylight conditions (500 lx), prelarvae displayed saltatory changes of behavioral features with ages (Day 0-Day 9) in a general order of swimming-up/drifting, swimming in the upper water column, benthic swimming with rheotaxis, schooling and post-schooling behavior. Compared to daylight conditions, prelarvae tended to show more benthic performances and quantitative reductions of schooling and post-schooling behaviors under dimlight conditions (5 lx). Under dark conditions (< 0.5 lx), prelarvae exhibited a fairly uniform behavioral pattern characterized by the benthic swimming across the bottom of the tank. From phototaxis tests under dark conditions, navigational responses of prelarvae to a spotlight illumination were quantitatively changed as their ages increased. The phototactic responses reached the peak on Day 2, continued until Day 4, and then gradually decreased until Day 8. A partial recovery of positive phototaxis was observed on Day 9. Data from this study suggest that the diel light cycle as well as the light intensity of each interval in the cycle should be considered as important components of a practical guide for evaluating fitness and developmental states of artificially propagated Siberian sturgeon prelarvae.

• 한국수산과학회지
• /
• 제31권4호
• /
• pp.500-507
• /
• 1998

돌산도 모래해안 쇄파대에서 1993년 1월 소조와 대조때 1조석주기 동안 채집한 저서성 단각류 시료를 가지고. 주야와 조석주기에 따른 Pontogeneia rostrata의 종내 대상분포를 조사했다. p. rostrata의 밀도는 대조보다는 소조때 높았다. 개체군을 성체 암$\cdot$수컷과 미성체로 나누어 보면. 미성체와 수컷의 밀도가 각각 소조와 대조때 가장 높았다. 체장빈도 자료에 따르면. 겨울철에 미성체의 사망이 큰 것 같다. 야간 표층에서 소조때는 미성체 그리고 대조때는 성체암$\cdot$수컷이 유의하게 많았다. 이것은 미성체와 성체의 수직이동 양상이 조석에 따라 다르게 나타난 것으로 여겨 진다. 대조 밀물때 평균해수면 (MSL) 위에 나타난 p. rostrata의 $90\%$ 이상이 성체였다. MSL 위에서 암컷/수컷의 비율이 감소했고. 암컷의 체장은 변동이 없었지만 수컷의 체장은 증가했다. 이것은 몸이 큰 수컷의 활발한 이동습성을 가리킨다. 이런 행동은 큰 수컷의 분포역 확장으로 이어지고, 교미와 섭식경쟁에 있어 큰 수컷에게 유리할 것으로 여겨진다. 성체가 대조 야간에 MSL 위 100cm에서 채집되기도 하지만. 나머지 기간에 p. rostrata 개체군은 대부분 MSL 아래에 머물렀다. 분포중심은 MSL 아래 50cm에서 200cm 사이였다.

• 한국대기환경학회지
• /
• 제12권4호
• /
• pp.495-504
• /
• 1996

The concentrations of dimethylsulfide (DMS) were determined from both seawater and the overlying atmosphere from a station located in the Masan Bay area during a ten-day field campaign period of January 1996. The resulting data were also used to derive saturation ratios (SR) as well as sea-to-air fluxes of DMS. The concentrations and fluxes of DMS for both reservoirs varied extensively over two to three orders of magnitude: DMS in air and seawater were measured at 9 to 4,300 pptv (mean: 600 $\pm$ 1, 170, N=18) and at 0.24 to 10 nM (4.0 $\pm$ 3.4, N=13), respectively, while its fluxes were found from 0.02 to 23 mol $m^{-2} day^{-1} (3.1 \pm 6.8, N=11)$. A comparative analysis between our data and previously reported ones indicate that its atmospheric concentrations are abnormalously high, but its seawater counterparts are slightly lower than expected. In light of high pollution levels of organic-rich materials in and the associated high biological productivity of the study area, the sea-to-air-fluxes derived are notably low relative to those values typically reported from the coastal areas. These complicated features of DMS distributions/fluxes in the study site indicate that the near-by port- based anthropogenic activities from various industrial plants strongly interfere with natural processes leading to the production and release of DMS. It was however striking to find out relatively strong signals of diel cycle in its saturation ratios, concentration gradients between seawater and atmosphere, and the associated fluxes. Although it is yet difficult to provide meaningful explanations for the observed phenomena, the existence of clear diel cycle in some DMS-related parameters suggests that the natural processes may nonetheless exert important controls on the regional cycling of atmospheric sulfur species, of particular DMS.

• 한국수산과학회지
• /
• 제29권4호
• /
• pp.527-536
• /
• 1996

동물플랑크톤이 쇄파대에서 어떻게 적응하여 살아가고 있는가를 연구하면서, 부유성 요각류 일곱 종의 주야 수평이동 양상을 조사하여 비교했다. 동해 영일만 쇄파대에서 수심 1m 되는 곳의 표층과 저층과 해변가 세 곳을 썰매형 네트로 채집했다(총시료수=108개). 쇄파대 요각류 집단은 일곱 종 (Acartia hudsonica, Fseudodiaptomus marinu, Paracalanus indicus, Calanus sinicus, Oithena similis, Sinocalanus tenellus, Labidocera bipinnata)이 우점했다. 쇄파대 요각류의 주${\cdot}$야간 생물량 차는 약 세 배였다. 표층에서 채집한 전체 요각류와 우점하는 일곱 종의 생물량은 주간보다 야간에 모두 유의하게 많았다. 하지만, 저층에서 주${\cdot}$야간 생물량의 차는 모두 유의하지 않았다. 이 연구에서 쇄파대 요각류의 약 $90\%$가 주야 수평이동하는 것을 밝혔다. 조금때 바람이 육지에서 바다쪽으로 불었지만, 표층에서 야간에 요각류 밀도가 높게 나타났다. 요각류가 해류에 따라 수동적으로 운반되지 않더라도 능동적으로 수평 방향을 유지하여 헤엄칠 수 있는 능력을 갖고 있기 때문인 듯하다. 요각류는 상대 조도의 변화에 따라 광반응 행동을 하고, 그래서 야간에 쇄파대에 모였다가 주간에 흩어지게 하는 주야 수평이동이 나타난 것 같다. 주야 수평이동은 요각류가 시각 포식자와 마주칠 기회를 줄일 것이다. A. hudsonica가 개체발생 단계별로 이동시각을 달리한 것은 발생단계에 따라 광반응 행동이 다르기 때문에 나타난 현상인 듯하다. 결과적으로 이것이 먹이를 둘러싼 종내 경쟁을 줄일 것 같다. 요각류 이동 자료에서 A. hudsonica, P. indicus, O. similis, S. tenellus 네종은 한 시간 이상 유영속도를 $20m\;h^{-1}$으로 유지할 수 있는 것으로 나타났다. 쇄파대에서 요각류가 차지하는 중요도를 바로 알려면, 주야 생물량이 매우 다르므로 주간과 야간 채집을 함께 해야 한다.

• 환경생물
• /
• 제27권3호
• /
• pp.285-291
• /
• 2009

본 연구는 밀폐식 순환여과 시스템의 호흡측정실내에서 해수 및 담수사육 강도다리의 산소소비에 미치는 수온 영향을 조사하였다. 실험에 사용한 어류는 해수 및 담수에 각각 순화시킨 해수사육 강도다리(9마리, 평균체중 $263.0{\pm}40.4$ g)와 담수사육 강도다리(9마리, 평균체중 $265.8{\pm}34.8$ g)를 사용하였다. 수온 15, 20, $25^{\circ}C$에서 해수사육 강도다리의 산소소비량은 각각 $74.4{\pm}17.0,\;85.9{\pm}15.8,\;98.3{\pm}11.4\;mg\;O_2\;kg^{-1}hr^{-1}$, 담수사육 강도다리는 $46.7{\pm}12.0,\;63.3{\pm}7.5,\;82.6{\pm}5.3\;mg\;O_2\;kg^{-1}hr^{-1}$로 수온 상승 비례하여 증가하였다. 또한 수온 $15^{\circ}C$와 $20^{\circ}C$에서는 명기(09:00~21:00 hr)와 암기(21:00~09:00 hr)로 나누어진 광주기(12L : 12D)의 조건에서 해수 및 담수사육 강도다리 모두 명기에는 산소소비가 적고, 암기에는 산소소비가 많은 뚜렷한 일주리듬을 보였다. 하지만 수온 $25^{\circ}C$에서는 해수 및 담수사육 강도다리 모두 명기와 암기의 뚜렷하지 않은 산소소비 일주리듬을 보였으며, 수온 $20^{\circ}C$ 이상에서는 대사리듬이 흐트러지는 것으로 판단된다. 해수 및 담수사육 강도다리의 호흡률을 비교했을 때 담수사육 강도다리가 해수사육 강도다리보다 높았으나, 산소소비량은 해수사육 강도다리가 많았다.

• 환경영향평가
• /
• 제21권6호
• /
• pp.879-891
• /
• 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.

• 한국수산과학회지
• /
• 제30권1호
• /
• pp.39-45
• /
• 1997

쿠마류 Bodotria biplicata의 조하대 대상분포를 돌산도 모래해안의 쇄파대에서 조사했다. 1993년 1월 소조와 대조때 수심 1m의 표층과 저층, 그리고 바닷가에서 쿠마류를 1조석주기 동안 한 시간마다 썰매 네트로 3회 반복 채집했다(시료수=225개). 조하대에서 가장 우점한 B. biplicata는 저층에서 밀도가 가장 높았고 표층에서는 전체 생물량의 약 $0.6\%$가 채집되었다. 소조때 평균 밀도는 대조때보다 조금 높았다. 채집 생물량은 조하대 수심의 영향을 받았다. 밀도 변화는 주야주기나 밀물-썰물보다 조하대 수심과 더 관련이 있었다. 조사기간에 주야 수직 이동은 뚜렷하지 않았다. 소조와 대조때 모두 B. biplicata 개체군은 낮은 저조 (LLW) 아래 약 90cm 되는 곳에서 밀도가 가장 높았다. 그러므로 이 종은 2주 주기로 해안쪽과 바다쪽으로 수평이동하는 듯하다. B. biplicata가 조하대 모래바닥을 이동하는 속도와 거리는 모래해안의 기울기와 조차에 따라 달라질 것이다. 개체발생 단계별로 분포양상이 달랐고 미성체와 만카유생이 성체보다 깊은 곳에 분포했다. 이것은 먹이를 둘러싼 종내경쟁을 줄이는데 기여할 것 같다.

• 한국수산과학회지
• /
• 제50권5호
• /
• pp.534-540
• /
• 2017

This study was conducted to determine the circadian rhythm and the effect of starvation for the health assessment of olive flounder Paralichthys olivaceus, reared under 12:12 LD (light:dark) cycle and fed 1% of their body weight once a day. The blood collection was implemented from 10 fish every 3 hours for a day, and analyzed to serval health parameters of the experimental fish. Plasma cortisol, glucose and total protein concentration reflected diel rhythms with high level of photophase and low level of scotophse despites of glutamic oxalacetic transaminase (GOT) and glutamic pyruvate transaminase (GPT) showing no rhythmicity, while electrolyte (sodium, potassium and chloride ion) concentrations arrived at the peak 18 hour and then slowly down. In the experiment of starvation, the result showed that there were no significant differences of the health parameters between the starved group and the fed. In short, our findings described the existence of circadian cortisol with glucose in flat fish, and indicated that the starvation does not almost affect the health of fish.