• 수산해양기술연구
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• 제42권4호
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• pp.240-258
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• 2006

The potential of ecosystem-based fisheries management is recently recognized to be very important to improve the sustainability of fisheries resources. Under the depressed condition of many fisheries resources, this recognition has been expanded and more effort has been taken to improve this approach. Taking ecosystem concept includes the use of other tools of management in addition to fisheries regulation, such as stock and productivity enhancement, provision of physical structure, or marine protected areas. In the ecosystem-based fisheries management approach, it would require to holistically consider ecological interactions of target species with predators, competitors, and prey species, the effects of climate on fisheries ecology, the complex interactions between fishes and their habitat, and the effects of fishing on fish stocks and their ecosystem. Fisheries management based upon the understanding of these factors can prevent significant and potentially irreversible changes in marine ecosystems caused by fishing. A useful approach for analyzing tropho-dynamic interactions and mass-balance in marine ecosystems is introduced to demonstrate the complexity and usefulness of the ecosystem approach, which was applied to a small ecosystem in Korea. Korea should seriously consider to take the ecosystem-based approach to fisheries management, since most major fish stocks are currently depleted due to many reasons such as overfishing, land reclamation and coastal pollution.

• Journal of Ecology and Environment
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• 제38권3호
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• pp.389-395
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• 2015

The composition of the Martes flavigula diet has been extensively studied, but little is known about its insect component. This study characterized the insect diet and insect nest materials in the feces of M. flavigula. A total of 952 fecal samples were collected in Jirisan National Park from January 2009 to November 2011, and 1379 species or taxonomic groups were identified. M. flavigula fed on insects (8.7%) and bee wax (5.0%), which comprised 2.9% and 4.4% of the dry weight of M. flavigula feces, respectively. A total of 12 insect species belonging to 8 families in 3 orders were identified. The most frequently found insects were Hymenoptera (frequency of occurrence, FO, 89.1), including Vespa simillima simillima (FO, 37.3) and Vespula koreensis koreensis (FO, 20.0). The Vespidae constituted the majority of the insect diet in autumn when the diversity of marten's prey was strongly reduced, probably because the numbers of social insects were sufficient for M. flavigula. In addition, the data suggest that M. flavigula attacks the nests of social wasps in late autumn when males do not have a venomous sting and new queens are less aggressive than workers. Bee wax appeared in all seasons and the highest rate was from spring to early summer. However, the remains of honeybees were not found in feces; thus, M. flavigula presumably eats honey but not honeybees.

• Fisheries and Aquatic Sciences
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• 제11권2호
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• pp.113-123
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• 2008

We modeled fish school movements as a capture process in relation to the purse seine method using the three steps of the stimulus-response process (i.e., input stimuli, central decision-making and output reaction). Input stimuli of the model were categorized as either physical stimuli such as visual stimulus, sound stimulus, water flow, and weather or as biological stimuli such as species and size, swimming performance, sensual sensitivity, and presence of prey or predators. The output process determining the spatial orientation of the fish school for 3-D movements was based on swimming speed and angular change in the fish response, and these movements were animated as the relative geometry between the fish school and the purse seine. Simulations were carried out for skipjack tuna (Katsuwonus pelamis) schools reacting to a pelagic purse seine in the southwest Pacific Ocean. Simulation results showed that escape ratios varied from 20 to 70% by the relevant ranges in the stimulus-response thresholds, swimming speeds, and angular changes of fish schools were similar to those observed in the field. Therefore, with knowledge of relevant parameters, this model can be used to predict capture and escape probabilities of purse seine operations for different fish species or conditions.

• 한국패류학회지
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• 제30권4호
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• pp.437-441
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• 2014

표본은 2010년 7월 12일 부산시 송정주변해역에서 정치망에 어획된 것을 채집하였다. 패각 방사륵은 56개이었다. 제1번 팔은 패각을 붙잡고 있으며, 제1번 팔의 기저부는 팔 전체를 덮을 만큼 매우 큰 편평한 막으로 되어 있었다. 출수기관은 비교적 큰 편이어서 4번 팔의 기저부를 넘어선다. 팔길이식은 4 > $2{\fallingdotseq}3$ > 1이었다. 표본은 암컷이며, 포란수는 155,203 립이었다. 난은 타원형이었다. 조개낙지는 표층 부유성 문어이며, 돌고래의 먹이생물 중 하나이다.

• Ocean and Polar Research
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• 제39권4호
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• pp.257-267
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• 2017

Although Pacific mackerel (Scomber japonicus) is an important commercial species in Korea, its recruitment mechanism remains largely unknown. Diel vertical positioning of larvae in the water column, which is affected by their specific gravity and the surrounding water density, may help to provide an understanding on recruitment success through predator avoidance and prey availability. The specific gravity measurement on Pacific mackerel eggs and larvae would seem to be essential information necessary to learn about the transport process from spawning to nursery grounds, and consequently the recruitment success. Eggs were artificially fertilized, and larvae were fed with rotifer when their mouths opened 3-4 days after hatching. We conducted the experiment using a density gradient water column to measure the ontogenetic changes in specific gravity from fertilization to 10 days after hatching. Egg specific gravity was stable during most of the embryonic period, but a sudden increase to $1.0249g\;cm^{-3}$ happened just before hatching. However, the specific gravity of newly hatched larvae was much lighter ($1.0195g\;cm^{-3}$), and specific gravity tended to increase continuously after hatching. Comparison of specific gravity with seawater density reveals that eggs and newly hatched larvae can float in the surface layer of the ocean. For the later period of the experiment, the specific gravity showed a cyclic diel pattern: the highest in the evening while the lowest at dawn. The fullness of larval stomach may be responsible for the observed differences in specific gravity, because stomach fullness was lower (40-60%) at midnight, and higher (80-85%) in evening. The diel pattern of specific gravity might provide clues regarding how larvae match the diel vertical migration of prey organisms.

• 수산해양기술연구
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• 제46권4호
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• pp.406-415
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• 2010

The forming of fishing ground and the population ecological characteristics of yellowtail, Seriola quinqueradiata, in the coastal waters off Gim-nyeong of Jeju Island were investigated. The stock of yellowtail, Seriola quinqueradiata, between Jeju Island and coastal areas of the East Sea is probably the same. Water temperature probably is a major factor for controlling distribution of yellowtails in deeper, offshore areas off Jeju Island. However, the major factor that determines aggregation of yellowtails in coastal areas of Jeju Island, especially off Gim-nyeong is probably strong tidal currents driven by distribution of yellowtails rather than hydrological conditions such as Yellowtails collected off Jeju Island were from 1 to 4yrs old and about 50% of them were $1^{-yr}$ old, probably indicating overfishing. Jack mackerel was the major prey item for yellowtails off Gim-nyeong from October to March, suggesting concurrence of the two species.

• 한국어류학회지
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• 제23권2호
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• pp.128-134
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• 2011

경남 통영 연안해역에서 채집된 쏨뱅이(Sebastiscus marmoratus) 324개체의 식성을 조사하였다. 쏨뱅이의 표준체장(SL)은 9.8~30.1 cm 범위였다. 쏨뱅이의 위 내용물을 분석한 결과 쏨뱅이는 멸치(Engraulis japonicus), 청어(Clupea pallasii), 망둑어류(Gobiidae)와 같은 어류(Pisces)를 주로 섭식하는 어식성어류였으며, 어류 중에서 멸치를 가장 선호하였다. 어류 다음으로 새우류(Macrura)와 게류(Brachyura)를 섭식하였으며, 그 외에 집게류(Anomura), 갯지렁이류(Polychaete), 이매패류(Bivalvia), 난바다곤쟁이류(Euphausiacea)를 섭식하였지만 그 양은 많지 않았다. 체장이 16 cm 이하의 개체는 새우류와 게류를 주로 섭식하였다. 새우류와 게류의 비율은 체장 증가에 따라 감소한 반면, 어류의 비율은 점점 증가하였다. 어류는 체장 19 cm 이상의 개체에서는 위 내용물 중 대부분을 차지하였다. 쏨뱅이의 위 내용물을 계절에 따라 유의하게 변하였다. 어류는 여름, 가을, 겨울에 중요한 먹이생물인 반면 게류와 새우류는 봄에 주로 섭식되었다.

• 한국해양학회지:바다
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• 제12권2호
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• pp.86-93
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• 2007

양양 남대천에 서식하는 연어 치어의 먹이섭식 생태조사를 위해 환경 중 수서곤충 군집과 연어(Oncorhunchus keta) 치어의 위내용물을 분석하였다. 양양 남대천에 서식하는 수서곤충은 모두 6목 25과 52종으로, 개체수에 있어서는 파리목(Diptera)이 가장 많은 전체의 91.7%를 차지하였으며, 하루살이목(Ephemeroptera)이 3.6%, 날도래목(Tripchoptera)이 3.3%, 강도래목(Plecoptera)이 1.3% 등의 순으로 나타났다. 생중량은 파리목이 전체의 40.9%, 날도래목이 40.3%, 하루살이목이 14.8%, 강도래목이 2.6% 등의 순이었다. 남대천의 수서곤충상과 연어 치어의 위내용물은 개체수나 중량에 있어 대부분 비슷하여 먹이 선택성은 거의 없이 입의 크기에 맞는 모든 살아있는 생물을 섭식하였다. 동소서식어종의 위내용물을 분석한 결과 연어 치어와 가장 유사한 위내용물을 보인 종은 산천어의 치어였다. 연어 치어와 동소적으로 서식하는 어종들의 먹이생물을 분석한 본 연구 결과는 향후 우리나라 연어 치어 방류사업에 있어 하천 수용력에 대한 기초 자료를 제공할 것이다.

• Journal of Ecology and Environment
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• 제48권3호
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• pp.405-415
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• 2024

Background: Hypersaline environments (> 40 practical salinity units [PSU]) represent some of the most extreme conditions on Earth, supporting a variety of halophilic and halotolerant bacteria, archaea, and protists. The taxon Heterolobosea includes numerous halophilic protists, making it a valuable model for studying eukaryotic adaptation to high salinity. Particularly, the genus Pharyngomonas, a deep-branching lineage within Heterolobosea, comprises mainly obligate halophiles, providing insights into early protist adaptations in hypersaline environments. Additionally, these protozoa play crucial ecological roles as grazers of bacteria and archaea, and are prey for higher trophic levels in hypersaline environments. Results: In the present study, two previously reported amoeboflagellates were isolated for the first time from hypersaline waters (~300 PSU) in two solar salterns in the Republic of Korea. Microscopic observations revealed that both strains exhibited the characteristic morphologies of Pharyngomonas, including amoeboid, flagellate, and cyst forms. Molecular phylogenetic analysis of their 18S rRNA gene sequences confirmed their close relationship to known Pharyngomonas kirbyi strains. The two strains demonstrated growth within a salinity range of 75-200 PSU, with optimal growth observed at 75-100 PSU, confirming their status as true halophiles. All known P. kirbyi strains are obligate halophiles, exhibiting a clear instance of adaptive radiation of halophilic eukaryotes. Additionally, the genus Pharyngomonas has been found in hypersaline environments across multiple continents (Asia, Europe, North America, Australia, and Africa), suggesting that it plays an ecologically significant role as a grazer of prokaryotes or prey for higher trophic levels in these habitats. Conclusions: On the bases of morphological and molecular analyses, two strains identified as P. kirbyi were isolated and characterized for the first time from solar salterns in the Republic of Korea. This discovery highlights the presence and adaptation of halophilic eukaryotes in such extreme environments. The confirmation of these strains as obligate halophiles provides additional evidence for the adaptive radiation of halophilic eukaryotes. Furthermore, the ecological role of Pharyngomonas species underscores their importance as trophic regulators in hypersaline ecosystems. These findings contribute to a deeper understanding of the diversity, adaptation, and ecological functions of halophilic eukaryotes in extreme environments.

• 한국해양학회지:바다
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• 제20권3호
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• pp.151-157
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• 2015

실내 배양체를 이용한 최근의 연구들은 혼합영양성 와편모류 Dinophysis와 종속영양성 와편모류 Oxyphysis oxytoxoides가 둘 다 혼합영양성 섬모류인 Mesodinium rubrum을 먹이생물로 이용하여 잘 성장한다는 점을 보고한 바 있다. 본 연구는 자연 생태계에서 포식자인 D. acuminata 및 O. oxytoxoides와 그들의 먹이인 M. rubrum사이의 상호작용을 연구할 목적으로 2011년 7월말부터 8월말까지 한 달간에 걸쳐 마산만의 한 고정 정점에서 하루 2회씩 개체군 변동을 모니터링 하였다. 본 연구동안 염분은 강수량이 높게 나타난 시기에 최소 5까지 급격하게 낮아지다가 강수량이 감소하는 8월말로 갈수록 약 28까지 점차적으로 증가하는 경향을 나타냈고, 수온은 8월 20일까지는 평균적으로 $26.5^{\circ}C$를 유지하였으나, 이후에는 평균 $21^{\circ}C$를 유지하였다. M. rubrum은 연구기간 동안 지속적으로 출현하였으나 그 변동 폭($13-492\;cells\;mL^{-1}$)이 매우 컸다. D. acuminata와 O. oxytoxoides의 개체수는 각각 $n.d.-19,833\;cells\;L^{-1}$와 $n.d.-100,333\;cells\;L^{-1}$의 범위를 나타냈다. 전반적으로 D. acuminata와 먹이생물인 M. rubrum의 개체수 출현 양상은 시간차를 두고 서로 밀접한 관계를 보이기도 하였으나, M. rubrum이 높은 밀도로 출현함에도 불구하고 D. acuminata의 대번식이 일어나지 않는 경우가 존재하였는데, 이러한 이유는 극심한 염분의 변화 및 포식 등의 결과로 판단된다. 한편, O. oxytoxoides는 M. rubrum이 지속적으로 출현함에도 불구하고 $19-24^{\circ}C$의 수온 범위에서만 출현한 결과로 볼 때, 먹이생물의 부족보다는 수온 등의 환경요인이 O. oxytoxoides의 밀도 변화에 큰 영향을 미쳤을 것으로 판단된다.