• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.17 no.2
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• pp.112-119
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• 2012

This study investigated the diel and tidal distributions of the two mysids, Archaeomysis kokuboi and Acanthomysis nakazatoi, in relation to their growth stages in the sandy surf zone of Yongil Bay, located on the southeastern part of Korean Peninsula. Sampling was conducted with a sledge net at every two hours for almost 24 hours at three sites: water edge, water surface and sand bottom both in 1-m deep water areas. The abundance of Archaeomysis kokuboi juveniles was too low to count both in day and night samples. While there was no difference in immature A. kokuboi abundance between day and night in the bottom or water edge, that at the water surface was significantly higher at night than daytime. The abundance of A. kokuboi adults, especially of males, in the bottom was significantly higher in daytime than night and no individuals appeared to the water surface either day or night. In comparison, the abundance of Acanthomysis nakazatoi juveniles between day and night did not differ significantly at all the three sites, with the highest number being distributed in the bottom. The abundance of immatures between day and night also did not differ significantly and no individuals appeared to the water surface either day or night. The abundance of A. nakazatoi adults, especially females, in the bottom was significantly higher at night than daytime and there was no significant difference in abundance between day and night in the other sites. There was also no significant difference in abundances of the two species between ebb and flood tides, except for A. kokuboi immatures which appeared significantly more during the ebb tides at the water surface. Overall, the distribution of the two sympatric species, A. kokuboi and A. nakazatoi, was not the same in the sandy surf zone. Its difference seems to depend on their stages of growth, and the change in their abundance may be influenced more by diurnal rhythms than tidal effects. The population density of A. nakazatoi in the sandy surf zone was much higher than that of A. kokuboi, and relatively higher densities in all growth stages of the former were found in the sandy bottom ranging from juveniles to adults. These results indicate that A. nakazatoi has exceedingly better ability of sand burrowing even from the juvenile stage, and thus is an ecologically better adapted species in the sandy surf zone than another sympatric species, A. kokuboi.

• 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.33 no.2
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• pp.110-114
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• 2000

Effects of the combinations of six oxygen concentrations ($control, 0.6, 1.0, 2.0, 3.4 and 7.4 mg DO/l$) and two salinity levels ($20{\%_{\circ}} and 32{\%_{\circ}}$) on the rates of oxygen consumption, ammonia excretion and mortality of the mysid, Neomysis awatschensis were tested at $20{\circ}C$. The lethal level ($96 hr-LC-(50)$) of dissolved oxygen for mysid at $20{\%_{\circ}} and 32{\%_{\circ}} were 2,20 mg DO/l and 1.60 mg DO/l$ respectively, and all mysids died within $24hr at 0.6 mg DO/l$. Oxygen consumption rate of mysid was increased with dissolved oxygen increase at $20{\%_{\circ}} and 32{\%_{\circ}}$, but ammonia excretion rate was high af $1.0 mg DO/l$ during 96h exposure to DO concentration, and significantly greater in $20{\%_{\circ}} than 32{\%_{\circ}}$. $O:N$ ratio of mysid exposed during 96hr with salinity anil dissolved oxygen was below $10 at 20{\%_{\circ}} and 1,0{\~}2.0 mg DO/l, and was 4.4 at 32{\%_{\circ}} and 1.0 mg DO/l$. These results indicated that mysids were capable of changing their energy substrate in response to salinity and DO changes, and obtaining energy from proteins.

• Korean Journal of Ichthyology
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• v.25 no.1
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• pp.17-24
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• 2013

The feeding habits of Repomucenus lunatus were studied using 232 specimens collected from January to December 2006 in the coastal waters off Gori, Korea. The size of R. lunatus ranged from 4.7 to 14.0 cm in standard length (SL). R. lunatus was a bottom-feeding carnivore which consumed mainly amphipods and polychaetes. Its diet also included small quantities of shrimps, cumaceans, bivalvies, gastropods, crabs, copepods, euphausia, mysids, stomatopods, ostracods and sipunculides. Amphipods were eaten predominantly for the smallest size class. The proportions of polychaetes increased gradually with increasing fish size and large size class of R. lunatus mainly consumed polychaetes. The feeding strategy graphical method revealed that R. lunatus is a specialized feeder. The mean number and weight of preys per stomach of larger size classes were higher than those of smaller size classes. The mean weight of preys per stomach ontogenetically changed with size classes.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.1
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• pp.73-77
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• 2009

Feeding habits of released Sebastes inermis obtained in daily and monthly collections from August 2007 to December 2007 in coastal waters off Jam Island in Jinhae Bay, Korea were assessed. A total 151 individuals of S. inermis (6.3-9.7 cm TL) were recaptured during the study period. Initial food intake of released S. inermis occurred within three days of released. Stomach content index increased with time, however, the percentage of stomachs devoid of contents decreased. Sebastes inermis mainly consumed gammarid and caprellid amphipods, gastropods and mysids. Diet also included small quantities of bivalves, shrimps, copepods and ostracods. Amphipods were mainly consumed at all size groups and consumption of gastropods, bivalves and shrimps increased with increasing fish size.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.4
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• pp.372-377
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• 2011

The feeding habits of the redbanded searobin Lepidotrigla guentheri were studied using 186 specimens collected from September to November, 2006, in the coastal waters off Gori, Korea. The sizes of L. guentheri ranged from 7.1 to 16.7 cm total length(TL). L. guentheri is a bottom-feeding carnivore that consumes mainly shrimp, especially Leptochela sydniensis, amphipods, and crabs. Its diet also includes small quantities of stomatopods, mysids, cumaceans, euphausiids, polychaetes, and copepods. Our feeding-strategy graphical method reveled that L. guentheri is a specialized feeder, with a narrow niche width. L. guentheri mainly consumed shrimp of all size classes and did not show significant ontogenetic changes in feeding habits. Smaller individuals(7-11 cm TL) secondly consumed amphipods, with the portion of amphipods in the total diet decreasing as body size increased. Prey size increased significantly as the fish grew in size.

• Korean Journal of Ichthyology
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• v.9 no.2
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• pp.221-227
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• 1997

Feeding habits of Leiognathus nuchalis collected from the eelgrass bed in Kwangyang Bay from January 1994 to December 1994 were studied. Leiognathus nuchalis was a carnivore which mainly consumed copepods and crab larvae. Its diets included small quantities of polychaetes, amphipods, mysids, caridean shrimps. It showed ontogenetic changes in feeding habits. In an initial feeding stage, copepods were major food organisms. However, crab larvae and polychaetes were heavily selected with increasing fish size. Although copepods and crab larvae were major prey organisms for all seasons, the relative proportion of these two food items changed with season.

• Korean Journal of Ichthyology
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• v.11 no.2
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• pp.191-197
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• 1999

Stomach contents of hairtail, Trichiurus lepturus collected in the Nakdong River Estuary were examined quantitatively. T. lepturus was a carnivore which consumed mainly fishes, crustaceans (such as copepods, euphausiids and shrimps) and chaetognaths. Its diets included small quantities of small squids. T. lepturus showed ontogenetic progression of three feeding stages : an initial feeding stage was a planktivorous stage in which copepods were the major food item, followed by a mixed feeding stage in which euphausiids, mysids, shrimps, chaetognaths and fishes were the major food items, and finally a piscivorous stage in which fishes were the major food item. Especially anchovies were heavily selected by large T. lepturus.

• Korean Journal of Ichthyology
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• v.10 no.2
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• pp.176-183
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• 1998

Spawning ecology and feeding habits of Maurolicus muelleri in the Korean waters were studied. M. muelleri spawned continuously throughout the year showing a peak in August. Major spawning ground of this species was the southeastern sea of Korea. The fecundity observed from the ovaries of M. muelleri showed a range of 5,072 to 32,117, and the average number of eggs per one spawning time was approximately 250. M. muelleri was a zooplanktivore which fed mainly on copepods. Its diets also included various crustaceans such as amphipods, euphausiids, shrimps and mysids.

• Korean Journal of Ichthyology
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• v.20 no.2
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• pp.112-116
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• 2008

Feeding habits of Hippocampus mohnikei (4.1~10.4 cm SL) collected from an eelgrass bed in Dongdae Bay, Korea were studied. H. mohnikei was a carnivore fish which consumed mainly gammarid amphipods. Its diets also included a small amount of caprellid amphipods, tanaids, copepods, mysids, and eelgrass. Gammarid amphipods were the most important prey organisms to the diet of all size classes of H. mohnikei despite smaller H. mohnikei (<4.5 cm SL) fed copepods. H. mohnikei fed on larger sizes of prey as their size increased. The dietary breadth of H. mohnikei were decreased with increasing their size.