• Korean journal of applied entomology
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• v.36 no.2
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• pp.166-171
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• 1997

To find out an alternative prey of Orius strigicollis Poppius in the laboratory continuous rearing system, cotton aphid (Aphis gossypii), two spotted spider mite (Tetmnychus urticae) and mold mite (Tyrophagus putrescenriae) were tested as alternative prey. Development and oviposition of 0. strigicollis were observed at 25f l0C, RH 60-80% and 16L:8D. Survival rate and developmental period of the nymphal stages of 0. strigicollis was 81. 6% and 11.6 days when fed on cotton aphid, 56.796, 14.6 days, 42.3% and 16.5 days when fed on two spotted spider mite and mold mite, respectively. Total oviposition of 0. strigicollis was 68.5 eggslfemaie fed on cotton aphid, 46.1 and 26.5 eggsifemale fed on two spotted spider mite and mold mite, respectively. Cotton aphid seems to be most suitable prey for rearing 0 . strigicollis among the three prey species tested.

• ALGAE
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• v.37 no.2
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• pp.149-161
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• 2022

Noctiluca scintillans is a heterotrophic dinoflagellate that causes red-colored oceans during the day (red tides) and glowing oceans at night (bioluminescence). This species feeds on diverse prey, including phytoplankton, heterotrophic protists, and eggs of metazoans. Thus, many scientists have conducted studies on the ecophysiology of this species. It is easy to cultivate N. scintillans at a scale of <1 L, but it is difficult to cultivate them at a scale of >100 L because N. scintillans cells usually stay near the surface, while prey cells stay below the surface in large water tanks. To obtain mass-cultured N. scintillans cells, we developed an automatic system for cultivating N. scintillans on a scale of 100 L. The system consisted of four tanks containing fresh nutrients, the chlorophyte Dunaliella salina as prey, N. scintillans for growth, and N. scintillans for storage, respectively. The light intensities supporting the high growth rates of D. salina and N. scintillans were 300 and 20 µmol photons m^-2 s^-1, respectively. Twenty liters of D. salina culture from the prey culture tank were transferred to the predator culture tank, and subsequently 20 L of nutrients from the nutrient tank were transferred to the prey culture tank every 2 d. When the volume of N. scintillans in the predator culture tank reached 90 L 6 d later, 70 L of the culture were transferred to the predator storage tank. To prevent N. scintillans cells from being separated from D. salina cells in the predator culture tank, the culture was mixed using an air pump, a sparger, and a stirrer. The highest abundance of N. scintillans in the predator culture tank was 45 cells mL^-1, which was more than twice the highest abundance when this dinoflagellate was cultivated manually. This automatic system supplies 100 L of N. scintillans pure culture with a high density every 10 d for diverse experiments on N. scintillans.

• ALGAE
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• v.38 no.1
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• pp.57-70
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• 2023

The mortality rate of red-tide dinoflagellates owing to predation is a major parameter that affects their population dynamics. The dinoflagellates Ansanella granifera and Ansanella sp. occasionally cause red tides. To understand the interactions between common heterotrophic protists and A. granifera, we explored the feeding occurrence of nine heterotrophic protists on A. granifera and the growth and ingestion rates of the heterotrophic dinoflagellate Gyrodinium dominans on A. granifera as a function of prey concentration and those of Oxyrrhis marina at a single high prey concentration. The heterotrophic dinoflagellates Aduncodinium glandula, G. dominans, Gyrodinium moestrupii, Luciella masanensis, Oblea rotunda, O. marina, Polykrikos kofoidii, and Pfiesteria piscicida and the naked ciliate Strombidium sp. were able to feed on A. granifera. With increasing mean prey concentrations, the growth and ingestion rates of G. dominans feeding on A. granifera rapidly increased and became saturated or slowly increased. The maximum growth and ingestion rates of G. dominans on A. granifera were 0.305 d^-1 and 0.42 ng C predator^-1 d^-1 (3.8 cells predator^-1 d^-1), respectively. Furthermore, the growth and ingestion rates of O. marina on A. granifera at 1,700 ng C mL^-1 (15,454 cells mL^-1) were 0.037 d^-1 and 0.19 ng C predator^-1 d^-1 (1.7 cells predator^-1 d^-1), respectively. The growth and ingestion rates of G. dominans and O. marina feeding on A. granifera were almost the lowest among those on the dinoflagellate prey species. Therefore, G. dominans and O. marina may prefer A. granifera less than other dinoflagellate prey species. The low mortality rate of A. granifera may positively affect its bloom formation.

• Korean Journal of Ichthyology
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• v.36 no.1
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• pp.68-76
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• 2024

To reveal the feeding ecology of Rhynchocypris semotilus, the survey was conducted in Songhyeoncheon, Songhyeon-ri, Hyeonnae-myeon, Goseong-gun, Gangwon-do in April 2022. As a result of analyzing the contents of the stomach using the index of relative importance (IRI), the important prey organisms were mainly Trichoptera (46.6%), Ephemeroptera (27.6%), Diptera (12.6%), Odonata (9.7%), Plecoptera (2.8%), Coleoptera (0.6%), and Hemiptera (0.1%) of Class Insecta, Phylum Arthropoda in that order. As a result of analyzing the trend by calculating the index of relative importance (IRI) for each age, it was found that those born in the same year mainly feed on relatively small Ephemeroptera and Diptera, but the proportion of these gradually decreases as they grow. And the proportion of relatively large Trichoptera and Odonata gradually increased, turning them into the most important food source for those over 3 years old. Additionally, prey size was the smallest at 2.8±2.5 (0.6 to 9.0) mm for individuals born in the same year, but gradually increased to 5.1±6.1 (1.1 to 17.0) mm for individuals born more than 3 years. As a result of examining prey selectivity, Plecoptera (+0.78), Trichoptera (+0.66), (+0.66), Coleoptera (+0.66), and Hemiptera (+0.03) showed positive selectivity, while Amphipoda (-1.00), Ephemeroptera (-0.24), Odonata (-0.13) and Diptera (-0.05) showed negative selectivity.

• Kyungpook Mathematical Journal
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• v.48 no.3
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• pp.515-527
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• 2008

We investigate a three species food chain system with a Holling type IV functional response and impulsive perturbations. We find conditions for local and global stabilities of prey(or predator) free periodic solutions by applying the Floquet theory and the comparison theorems.

• Journal of Ecology and Environment
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• v.44 no.1
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• pp.54-61
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• 2020

Background: Most fish undergo prey switch from juvenile to adult. It is thought that slightly different feeding habits occur among adult fishes due to growth, spawning, habitat change, and so on. Therefore, the diet of the John Dory Zeus faber (≥ 24 cm TL) was studied in the coastal waters of Korea by analysis of stomach contents, with comparison by season and size class of diet composition and prey diversity. Monthly samples were taken from February 2017 to January 2018. Results: The results showed that the John Dory was a piscivorous predator, and pisces had occupied 82.3% of IRI%. Trichiurus lepturus and Trachurus japonicus were important preys in all size classes and seasons. Diet composition differed among the size classes and seasons (Chi-square test, P < 0.05). As body size of Z. faber increased, the occurrence of benthic fish (Glyptocephalus stelleri) tended to increase. The seasonal prey composition also changed depending on the abundant species of each season. Conclusions: Z. faber is a piscivorous predator. The consumption habits of Z. faber appear to different results by their size and seasons. This study suggests that Z. faber could be considered an opportunistic predator.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.5
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• pp.541-546
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• 2017

Feeding habits of dolphinfish Coryphaena hippurus, were analyzed. Fish samples were collected by using a purse seine, fishing and set net in the southern sea of Korea from January to December 2015. The size of C. hippurus ranged from 23.8 to 127.4 cm in fork length. The species with the highest percent index of relative importance (%IRI; the most important prey taxa) in the diets of C. hippurus were teleosts and cephalopod, including Engraulis japonicus, Thamnaconus modestus and Trachurus japonicus, Loligo edulis was the most frequently consumed cephalopods. Coryphaena hippurus also ate small amounts of amphipods and carid shrimp. The dietary compositions of C. hippurus was not significantly different among size classes or seasons (ANOSIM, P>0.05). As body size of C. hippurus increased the mean number of prey per stomach (mN/ST) tended to decrease, but the opposite trend was evident for mean weight of prey per stomach (mW/ST). The mN/ST and mW/ST also significantly varied with season (one-way ANOVA, P<0.05).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.6
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• pp.982-987
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• 2015

During the study period, a total of 158 individuals of Synechogobius hasta were collected. The range of body length (BL) was 15.4-44.5 cm. The stomachs of 26.6% of the individuals were empty. The most abundant prey was shrimp. Among shrimp, Exopalaemon orientis was the most abundant species, being present in 27% in %IRI (index of relative importance). Fishes and crabs were also abundant prey. Analysis of ontogenetic changes, suggested that shrimp were the main prey of S. hasta of two size classes (<20 and 20-25 cm). The proportion of shrimp decreased, but that of fishes and crabs increased, with increasing body length, beginning at the 25-30 cm size class. In spring, fishes were the dominant prey, while shrimps, and crabs and fishes dominated in autumn and winter, respectively.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.1
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• pp.29-34
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• 2003

Recent reports on the phagotrophic feeding of M. rubrum are based on cultivation experiments with novel isolates of this ciliate species from Gomso Bay, Korea. Photo-adapted cryptophyte(CR-MAL01) cultures at high light of 100 $\mu$mol photons m$^{-2}$ s$^{-1}$ (HL) and low light of 10 $\mu$mol photons m$^{-2}$ s$^{-1}$ (LL) were fed to M. rubrum (MR-MAL01) cultures under HL and LL conditions, respectively. Absorbance spectrum by LL M. rubrum showed the same peak at wavelengths around 542nm as that by LL cryptophyte prey, which was not showed in HL M. rubrum. This result supports the implication that light utilization and absorption pattern of M. rubrum population must depend on the status of photo-adaptation of the co-existing population of prey cryptophyte. Consequences of the present research results were discussed in relation to the function of the prey cryptophyte and phagotrophic M. rubrum in marine microbial ecosystem.

• Bulletin of the Korean Mathematical Society
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• v.57 no.3
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• pp.677-690
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• 2020

In this article, we study a reaction-diffusion system with homogeneous Dirichlet boundary conditions, which describing a three-species food chain model. Under some conditions, the predator-prey subsystem (u₁ ≡ 0) has a unique positive solution (${\bar{u_2}}$, ${\bar{u_3}}$). By using the birth rate of the prey r1 as a bifurcation parameter, a connected set of positive solutions of our system bifurcating from semi-trivial solution set (r₁, (0, ${\bar{u_2}}$, ${\bar{u_3}}$)) is obtained. Results are obtained by the use of degree theory in cones and sub and super solution techniques.