• Kyungpook Mathematical Journal
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• v.48 no.3
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• pp.503-514
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• 2008

We investigate a three-species food chain system with Lotka-Volterra functional response and impulsive perturbations. In [23], Zhang and Chen have studied the system. They have given conditions for extinction of lowest-level prey and top predator and considered the local stability of lower-level prey and top predator eradication periodic solution. However, they did not give a condition for permanence, which is one of important facts in population dynamics. In this paper, we establish the condition for permanence of the three-species food chain system with impulsive perturbations. In addition, we give some numerical examples.

• ALGAE
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• v.35 no.1
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• pp.61-78
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• 2020

Species belonging to the dinoflagellate genus Prorocentrum are known to cause red tides or harmful algal blooms. To understand the dynamics of a Prorocentrum sp., its growth and mortality due to predation need to be assessed. However, there are only a few Prorocentrum spp. for which heterotrophic protist predators have been reported. We explored feeding by the common heterotrophic dinoflagellates Gyrodinium dominans, Oxyrrhis marina, Pfiesteria piscicida, Oblea rotunda, and Polykrikos kofoidii and the naked ciliate Strombidinopsis sp. (approx. 90 ㎛ cell length) on the planktonic species Prorocentrum triestinum, P. cordatum, P. donghaiense, P. rhathymum, and P. micans as well as the benthic species P. lima and P. hoffmannianum. All heterotrophic protists tested were able to feed on the planktonic prey species. However, O. marina and O. rotunda did not feed on P. lima and P. hoffmannianum, while G. dominans, P. kofoidii, and Strombidinopsis sp. did. The growth and ingestion rates of G. dominans and P. kofoidii on one of the seven Prorocentrum spp. were significantly different from those on other prey species. G. dominans showed the top three highest growth rates when it fed on P. triestinum, P. cordatum, and P. donghaiense, however, P. kofoidii had negative growth rates when fed on these three prey species. In contrast, P. kofoidii had a positive growth rate only when fed on P. hoffmannianum. This differential feeding on Prorocentrum spp. between G. dominans and P. kofoidii may provide different ecological niches and reduce competition between these two common heterotrophic protist predators.

• Applied Microscopy
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• v.45 no.2
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• pp.74-79
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• 2015

This study investigated the tongue movement during prey capture by Rana nigromaculata and the location of the frenulum linguae, which effects tongue movement. The tongue of R. nigromaculata are elliptical at the anterior and concave U-shaped at the posterior. The location of the frenulum linguae of R. nigromaculata is located at the front of the submentalis. This is due to the location of the frenulum linguae, which has significantly effects the movement and the expandability of the tongue. In terms of mobility, the tongue of R. nigromaculata and the expandability of the frenulum linguae allow the tongue to increase in length two or more times compared to immobile tongue in the other species. The time required until the swallowing movement after looking at and capturing the prey was 0.692000 seconds. Filming prey capture with a high speed camera showed that the rear part of the U-shaped tongue captures the prey with an appearance of stretching out longer to the front of tongue and turning in a reverse direction to bring the prey to the mouth.

• Journal of the Korea Society for Simulation
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• v.22 no.3
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• pp.1-6
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• 2013

The ecosystem is the complex system consisting of various biotic and abiotic factors and the factors interact with each other in the hierarchical predator-prey relationship. Since the competitive relation spatiotemporally occurs, the initial state of population density and species distribution are likely to play an important role in the stability of the ecosystem. In the present study, we constructed a lattice model to simulate the three-trophic ecosystem (predatorprey- plant) and using the model, explored how the ecosystem stability is affected by the initial density. The size of lattice space was $L{\times}L$, (L=100) with periodic boundary condition. The initial density of the plant was arbitrarily set as the value of 0.2. The simulation result showed that predator and prey coexist when the density of predator is less than or equal to 0.4 and the density of prey is less than or equal to 0.5. On the other hand, when the predator density is more than or equal to 0.5 and the density of prey is more than or equal to 0.6, both of predator and prey were extinct. In addition, we found that the strong nonlinearity in the interaction between species was observed in the border area between the coexistence and extinction in the species density space.

• Journal of applied mathematics & informatics
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• v.29 no.5_6
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• pp.1193-1204
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• 2011

In the present paper we consider a differential-algebraic prey-predator model with stage structure for prey and harvesting of predator species. Stability and instability of the equilibrium points are discussed and it is observed that the model exhibits a singular induced bifurcation when the economic profit is zero. It indicates that the zero economic profit brings impulse, i.e. rapid expansion of the population and the system collapses. For the purpose of stabilizing the system around the positive equilibrium, a state feedback controller is designed. Finally, numerical simulations are given to show the consistency with theoretical analysis.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.16 no.3
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• pp.151-167
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• 2012

In this paper, we investigate the dynamic behaviors of a one-prey and two-predator system with Holling-type II functional response and defensive ability by introducing a proportion that is periodic impulsive harvesting for all species and a constant periodic releasing, or immigrating, for predators at different fixed time. We establish conditions for the local stability and global asymptotic stability of prey-free periodic solutions by using Floquet theory for the impulsive equation, small amplitude perturbation skills. Also, we prove that the system is uniformly bounded and is permanent under some conditions via comparison techniques. By displaying bifurcation diagrams, we show that the system has complex dynamical aspects.

• Journal of applied mathematics & informatics
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• v.40 no.5_6
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• pp.1199-1215
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• 2022

This article aims to study the dynamical behaviours of a two species model in which non-selective harvesting of a prey-predator system by using a reasonable catch-rate function instead of usual catch-per-unit-effort hypothesis is used. A system of two ordinary differential equations(ODE's) has been proposed and analyzed with the predator functional response to prey density is considered as Hassell-Varley type functional responses to study the dynamics of the system. Positivity and boundedness of the system are studied. We have discussed the existence of different equilibrium points and stability of the system at these equilibrium points. We also analysed the system undergoes a Hopf-bifurcation around interior equilibrium point for a various parametric values which has very significant ecological impacts in this work. Computer simulation are carried out to validate our analytical findings. The biological implications of analytical and numerical findings are discussed critically.

• Korean Journal of Environment and Ecology
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• v.29 no.2
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• pp.210-220
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• 2015

We quantified temporal and spatial changes in the habitat for fish populations, the distribution of mandarin fish(Siniperca scherzeri) and an introduced species, largemouth bass(Micropterus salmoides) in Lake Paro and inflowing streams. The number of fish species identified in Lake Paro and the tributary streams included 10 families, 24 species and 10 families 30 species, respectively. The dominant fish species in Lake Paro were Zacco platypus, Hemibarbus labeo, Squalidus gracilis majimae, S. scherzeri and Tridentiger brevispinis, Z. platypus, Z. koreanus, and S. gracilis majimae in the inflowing streams. Although the habitat segregation for S. scherzeri and M. salmoides occurs, these two species showed the use of the fishes of the family Gobiidae as an important prey item based on IRI analysis. S. scherzeri and M. salmoides preyed mainly on T. brevispinis(67.4 %) and R. brunneus(84.0 %), respectively. The species preyed on by S. scherzeri and M. salmoides were benthic fishes that inhabit shallow water depths around the lake and have little swimming ability.

• ALGAE
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• v.34 no.2
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• pp.127-140
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• 2019

The species in the dinoflagellate order Suessiales have 5-24 latitudinal paraplate series and include many fossil and extant species. There have been a few studies on the ecophysiology of the phototrophic species Biecheleriopsis adriatica, and no study on its predators. Thus, we explored the feeding occurrence by common heterotrophic protists on B. adriatica and the growth and ingestion rates of the heterotrophic dinoflagellate Oxyrrhis marina on B. adriatica BATY06 as a function of prey concentration. The common heterotrophic dinoflagellates Aduncodinium glandula, O. marina, Gyrodinium dominans, Gyrodinium moestrupii, Luciella masanensis, Pfiesteria piscicida, and Oblea rotunda and two naked ciliates Strombidinopsis sp. and Pelagostrobilidium sp. were able to feed on B. adriatica, but the heterotrophic dinoflagellate Polykrikos kofoidii was not. However, B. adriatica supported the positive growth of O. marina, but did not support that of G. dominans and O. rotunda. With increasing prey concentrations, the growth and ingestion rates of O. marina on B. adriatica increased and became saturated. The maximum growth rate of O. marina on B. adriatica was $0.162d^{-1}$. Furthermore, the maximum ingestion rate of O. marina on B. adriatica was $0.2ng\;C\;predator^{-1}\;d^{-1}$ ($2.0cells\;predator^{-1}\;d^{-1}$). In the order Suessiales, the feeding occurrence by common heterotrophic protists on B. adriatica is similar to that on Effrenium voratum and Biecheleria cincta, but different from that on Yihiella yeosuensis. However, the growth and ingestion rates of O. marina on B. adriatica are considerably lower than those on E. voratum and B. cincta, but higher than those on Y. yeosuensis. Therefore, B. adriatica may be less preferred prey for O. marina than E. voratum and B. cincta, but more preferred prey than Y. yeosuensis.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.1
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• pp.95-104
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• 1997

Stomach contents of 518 specimens of the yellow goosefish, Lophius litulon caught by the off-shore stownet in the southern waters of Korea were examined by means of the calculation of the frequency of occurrence number and weight percentages, and index of relative importance (IRI) in each prey organisms. Prey organisms of the yellow goosefish consist of fishes, crustaceans, cephalopods. Fishes were dominant prey group, and occupied $98.8\%$ in IRI of prey organisms. Four species of fish, Pseudosciaena manchurica Collichthys niveatus, Engraulis japonica, Trichiurus lepturus were dominant as to the IRI and occupied $87.2\%$ of the total IRI. P. manchurica was a dominant prey organism in predator's stomach through the year, and the other dominant prey organisms occurred intermittently with seasonal progress. P. manchurica was a dominant prey organism to all fish size, too. C. niveatus and E. japonica decreased in importance in the diet as the fish size increased concomitant with an increase in importance of T. lepturus. Mean species number and mean individual number of prey organisms increased with the fish size.