• Ecology and Resilient Infrastructure
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• v.5 no.1
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• pp.54-58
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• 2018

Diet composition of amphibians usually reflects the distribution of potential prey within habitats, as well as their diet preference. We identified the diet items of Japanese tree frog (Hyla japonica) using a stomach flushing method in a rice paddy for the establishment of bio-monitoring systems of landscape changes. During the reproductive period, 71% of calling males had empty stomachs. All prey items in the stomachs belonged to the phylum Arthropoda, from eight orders of Insecta and one order of Arachnida. Among insect prey, the most common items in the stomachs were adults of beetles, flies and bugs, and larvae of butterflies and moths. There was a significant positive correlation between the body mass of Japanese tree frogs and the volume of prey items. Our results can provide a basic framework to guide the monitoring systems using prey identification of Japanese tree frogs.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.1
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• pp.20-28
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• 2019

The feeding habits of Pacific bluefin tuna, Thunnus orientalis were analyzed using samples by large purse seine fishery in Korean waters from 2012 to 2017. The number of samples was 1,274 and the fork-length (FL) ranged from 34.6 to 218.0 cm. According to %IRI, the Important main prey items of immature individuals (below 91.4 cm in FL) were Pisces, Cephalopoda and Euphausiacea and those of mature individuals were Cephalopoda and Pisces. T. orientalis showed ontogenetic changes in prey item that Pisces was dominated in size class of 30-89 cm (FL), Cephalopoda in 90-179 cm (FL), and Pisces above 180 cm. As for seasonal changes in prey item, Cephalopoda was dominant in spring and Pisces was dominant in summer, autumn and winter. %F, %N, %W and %IRI cluster analysis divided area into three groups: Group A was dominated by Pisces; Group B was dominated by Cephalopoda, and Group C was dominated by Euphausiacea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.5
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• pp.728-733
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• 2023

The diet composition of octopus Octopus vulgaris was studied using 392 specimens collected from January to December 2020 in the coastal waters of Yeosu, Korea. The body weight ranged from 86.4 to 3,645.4 g. The most important prey item in the diet of O. vulgaris was decapods, which constituted 43.9% in ranking index (%RI). The second largest prey item was Pisces (%RI=27.9%), and cephalopods (%RI=21.8%) constituted the third largest prey item. The average trophic level of O. vulgaris was 3.97±0.59. Ontogenetic changes were significant among size classes (<400 g, 400-800 g, ≥800 g). The small size class (<400 g) mainly fed on decapods, whereas the medium (400-800 g) and large size (≥800 g) classes mainly fed on cephalopods and Pisces, respectively. The dietary composition varied significantly with season.

• Korean Journal of Ichthyology
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• v.35 no.4
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• pp.347-353
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• 2023

Zenopsis nebulosa were collected by bottom trawl net from 20 areas in the South Sea of Korea during 2021 (February, May, August, November). The range of total length was 10.1~50.2 cm and empty stomach rate was 45.8%. The most important prey of Z. nebulosa was Pisces, with Trichiurus japonicus, Trachurus japonicus and Benthosema pterotum. And the second important prey was Euphausiacea. Z. nebulosa showed dietary shift by size class. In the <20.0 cm size class, Trachurus japonicus was dominant prey item. In the 20.0~25.0 cm size class, Trichiurus japonicus was dominant prey item. In the ≥25.0 cm size class, B. pterotum was dominant prey item. Analysis of the mean weight of preys per stomach (mW/ST) increased with individual size.

• Journal of Ecology and Environment
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• v.37 no.4
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• pp.225-229
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• 2014

Feeding behavior of Temora turbinata was investigated through laboratory experiments with special emphasis on its food preference and consequent clearance rate on diatom and microbial components given as common natural food assemblage of coastal area (Uchiumi, Uwa Sea, Japan). Among available prey items, T. turbinata showed the highest clearance rate for Thalassiosira spp. ($0.23{\pm}0.08L\;Temora^{-1}day^{-1}$) followed by Chaetoceros spp. ($0.11{\pm}0.03L\;Temora^{-1}day^{-1}$), but clearance rates for other diatom, Nitzschia spp. was lower (0.03 to $0.07L\;Temora^{-1}day^{-1}$). Bacterial abundances showed no response against 24-h feeding of T. turbinata. Feeding of T. turbinata on heterotrophic nanoflagellates (HNF) was apparent when clearance rates of T. turbinata on diatoms were relatively low, but T. turbinata did not consume HNF as well as ciliates with Thalassiosira spp. of which clearance rate was highest. The results suggest that HNF and ciliates are possible supplementary prey item for T. turbinata, but their contribution as food sources can be limited by the presence of other prey items such as preferable diatom species.

• Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.435-441
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• 2011

The feeding habits of yellow goosefish Lophius litulon and John Dory Zeus faber were studied by analyzing the stomach contents of specimens collected in the South Sea of Korea. In total, 132 hauls were taken during six experimental trawl survey (Tamgu 1) cruises conducted on a seasonal basis (March 2005-October 2007). The main prey items of the two species were similar. Fishes and crustaceans were the most important prey, with neither species showing ontogenetic changes in preferred species. Specifically, Pennahia argentata was the preferred prey item of L. litulon, whereas Trichiurus lepturus and Engraulis japonicus were preferred by Z. faber. Larger Z. faber (>24 cm) preferred bigger prey such as T. lepturus and Larimichthys polyactis, while smaller Z. faber preferred E. japonicus and Acropoma japonicum.

• Journal of Ecology and Environment
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• v.47 no.4
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• pp.168-176
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• 2023

Background: Many insectivorous bats have flexible diets, and the difference in prey item consumption among species is one of the key mechanisms that allows for the avoidance of interspecies competition and promotes coexistence within a microhabitat. In Korea, of the 24 bat species that are known to be distributed, eight insectivorous bats use forest areas as both roosting and foraging sites. Here, we aimed to understand the resource partitioning and coexistence strategies between two bat species, Myotis ikonnikovi and Plecotus ognevi, cohabiting the Mt. Jumbong forests, by comparing the differences in dietary consumption based on habitat utilization. Results: Upon examining their dietary composition using the DNA meta-barcoding approach, we identified 403 prey items (amplicon sequence variants). A greater prey diversity including Lepidoptera, Diptera, Coleoptera, and Ephemeroptera, was detected from M. ikonnikovi, whereas most prey items identified from P. ognevi belonged to Lepidoptera. The diversity index of prey items was higher for M. ikonnikovi (H': 5.67, D: 0.995) than that for P. ognevi (H': 4.31, D: 0.985). Pianka's index value was 0.207, indicating little overlap in the dietary composition of these bat species. Our results suggest that M. ikonnikovi has a wider diet composition than P. ognevi. Conclusions: Based on the dietary analysis results, our results suggests the possibility of differences in foraging site preferences or microhabitat utilization between two bat species cohabiting the Mt. Jumbong. In addition, these differences may represent one of the important mechanism in reducing interspecific competition and enabling coexistence between the two bat species. We expected that our results will be valuable for understanding resource partitioning and the coexistence of bats inhabiting the Korean forests.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.6
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• pp.740-744
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• 2019

Pacific white-sided dolphins Lagenorhynchus obliquidens inhabit cool temperate waters; in Korean waters, they concentrate near the coast of Gangwon and Gyeongbuk from late autumn to early spring. We collected 15 individuals from Yeongduk, Gyeongju, Ulsan, and Busan between December 2018 and February 2019 and analyzed their stomach contents. Fresh prey items were identified to the species level, and residual stomach contents that were unidentified due to digestion were filtered through a sieve to find fish otoliths and cephalopod beaks. The most important prey items of Pacific white-sided dolphins were cephalopods, composing 68.0% of the diet by occurrence. Fishes were the second largest dietary component, making up 32.0% of the diet by occurrence. Of the cephalopod species consumed, Watasenia scintilans was the principal prey item.

• Fisheries and Aquatic Sciences
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• v.25 no.1
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• pp.20-30
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• 2022

The present study was carried out to investigate the food and feeding habits of Oreochromis niloticus in Lake Shala to manage this species in this high Soda Lake. Stomachs of 226 fish (65.9%) had different food items, while those of 117 fish (34.1%) were empty. Phytoplankton was the dominant food categories occurring in 90.3% of the stomachs estimated and contributed 75.5% of the total volume. Bacillariophyceae (Nitzschia, Anomoeoneis, Navicula and Melosira) were identified as the most desired phytoplankton item. The prey items of O. niloticus differed among size classes (ANOVA, p < 0.05). The main prey items were zooplankton by the smaller-size class, and phytoplankton in fish of the larger-size class. Seasonal variation in the diet composition was evident (t-test, p < 0.05) and zooplankton, chironomids, nematodes, fish scales and detritus were important during the wet season, while phytoplankton predominates during the dry season. This study concludes that O. niloticus had a phytoplanktivores feeding mainly on phytoplankton and their feeding habits influenced by season and fish size in Lake Shala.

• Korean Journal of Environmental Biology
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• v.31 no.4
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• pp.275-287
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• 2013

The Japanese anchovy Engraulis japonicus is a widespread species in the western North Pacific and major fishery resource. To understand the spatio-temporal variation of anchovy prey items in the coastal waters of southern Korea, the stomach contents of anchovy and the structure of the zooplankton community were analysed at three sites (Jindo, Yeosu and Tong-yeong) from July 2011 to February 2012. The main prey items in Yeosu and Jindo were cyprid stage of barnacle (>35%) and copepod Calanus sinicus (>22%) in July, respectively, while, predominant ones in Tongyeong were small copepods, Paracalanus parvus s.l. (41%) and Corycaeus affinis (22%). During this period, the dominant zooplankton were cladoceran Evadne tergestina (39%) in Yeosu, small copepod, P. parvus s.l. (28%) in Jindo and cladoceran E. tergestina (14%) in Tongyeong. The dominant prey items were barnacle larvae and copepods in summer, phytoplankton and Pseudodiaptomus marinus in autumn and P. parvus s.l. and cold water copepod, Centropages abdominalis in winter. Anchovy prefer the prey item C. sinicus (3%) over E. tergestina (39%), which was a dominant species in the catching site in summer. P. marinus (0.5%) and C. abdominalis (0.9%) were preferred over P. parvus s.l. (30%, 21%) in autumn and winter, respectively. Prey items varied with area and season in the coastal waters of southern Korea. These results suggest that the prey selectivity of anchovy showed high flexibility and adaptability in the study waters.