• Applied Microscopy
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• v.46 no.2
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• pp.89-92
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• 2016

The bluegill Lepomis macrochirus is an invasive species, not native to Korea, introduced for aquaculture. This species is ranked as a new top predator due to its massive aquatic carnivorous and herbivorous nature by acute vision and the absence of a natural enemy. The visual cells of the retina of L. macrochirus are composed of short single cones and equal double cones and long and bulky rods by light and electron microscopes. In particular, the cones show a regular square mosaic arrangement. This pattern is widely considered as a strong predator. With regard to the visual system, this mosaic pattern may closely be related to a dynamic visual acuity to track and hunt prey.

• Animal Systematics, Evolution and Diversity
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• v.25 no.3
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• pp.325-329
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• 2009

Lepomis macrochirus from the family Centrarchidae, commonly known as Bluegill sunfish, is an introduced freshwater fish in Korea that thrives in lakes, ponds, reservoirs and rivers. Since its introduction into Korea in 1969, Lepomis macrochirus has rapidly dispersed out and increased in number almost all over the freshwater ecosystems in Korea. Consequently this species causes a severe ecological problem, threatening native fishes due to its omnivorous foraging behaviors upon fish juveniles and many freshwater invertebrates. To address population genetic structure of L. macrochirus, 74 fish samples from 10 populations were collected and compared for their mitochondrial D-loop control region. As the result we found that the genetic diversity of L. macrochirus is extremely low such as resulting only four haplotypes with a few nucleotide differences among them. Analysis of molecular variance (AMOVA) revealed that the source of population genetic variation is largely retained in the comparisons among individuals within populations, while it is relatively low with slight significance at the highest hierarchical group. This distribution pattern differs from what is expected when biogeography is under the influence of natural geographic barriers such as mountain ranges in Korea. Instead the result is accord with the influential role of random spreading events facilitated by local people for aquaculture and fishing, and subsequent dispersals since its single point of introduction into Korea.

• Korean Journal of Ichthyology
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• v.24 no.4
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• pp.278-286
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• 2012

This study was examined for information of management of bluegill, Lepomis macrochirus which is disturbance species of underwater ecosystem in Korea. Research of bluegill population was investigated spring-summer and autumn periods in the Han river system from 2009 to 2012. Bluegill inhabited mostly lakes, and restrictedly lived at still area in downstream. The range of relative abundance were 0.2~18.2% in individual number and 0.2~40.0% in biomass and it was subdominant or superiority species for the most part of the lakes. Population structure were analyzed r-strategy in Lake Soyang and Paldang and K-strategy in Lake Uiam and Cheongpyeong. But Lake Chungju was estimated transition period from K-strategy to r-strategy. Condition factor and body weight-total length relations were presented favorable condition. For the nesting, bluegill was formatted the group. And the water depth and the distance from shore were mean 56.3 cm and 191.9 cm respectively in nesting ground. Diameter and depth of nests were mean 42.4 cm and 9.7 cm respectively. These results are available for research of population dynamics and reproductive ecology of bluegill.

• Journal of Life Science
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• v.31 no.12
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• pp.1066-1071
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• 2021

The aim of this study was to examine the metabolic adjustment of lactate dehydrogenase (EC 1.1.1.27, LDH) isozymes to a change in dissolved oxygen (DO) in bluegill (Lepomis macrochirus). After bluegills were adapted to a constant environment in an aquarium, the DO was changed to investigate the activity of LDH isozyme and the relative ratio of subunits A, B, and C for each tissue. When the DO was decreased from 18 ppm to 6 ppm, LDH in skeletal muscle, heart, and brain tissues recovered to the level of control activity within 12, 12, and 6 hr, respectively. LDH activity changed in accordance with a change in DO. The compensation was performed rapidly and is thought to be an important function of LDH in enabling bluegills to adapt to their environment. In bluegill heart, eye, and brain tissues, the relative ratio of subunit A increased and showed a tendency to recover similarly to the subunit ratio of control groups up to 12 hr. It is thought that the anaerobic metabolism using subunit A was increased in the initial stage when DO was changed. In addition, the results revealed that subunit C was more similar to subunit A than subunit B. In bluegills, subunits A and C of LDH seem to be evolutionarily similar. LDH isozymes, mainly containing subunits A and C, are likely responsible for the function of pyruvate reductase, which plays a role in making the bluegill adapt to a hypoxic environment through anaerobic metabolism.

• Korean Journal of Environment and Ecology
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• v.34 no.5
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• pp.402-412
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• 2020

This study aims to examine the population characteristics of the fish and the bluegill (Lepomis macrochirus), designated as ecologically disturbing fish, living in four water dams in the Ulsan area and to provide basic data. The survey of fish living in 4 water dams and surrounding tributaries in the Ulsan area from 2016 to 2017 found a total of 1,987 individuals of 28 species of 9 families and identified 6 Korea's endemic species is (21.4% indigenous rate), 4 exotic species, and 2 ecosystem disturbing species. Based on the number of fishes identified, the dominant species was Lepomis macrochirus, and the subdominant species was Hemiculter eigenmanni. The investigation of the age structure of the L. macrochirus found in the 4 water dams in the Ulsan area showed a large population of 1 to 2 old, and the population was growing fast. Moreover, the analysis of the total length-weight relationship and obesity of the L. macrochirus population showed that the regression coefficient b of the total length-weight relationship was greater than 3.0, and the habitat of the L. macrochirus population was in good condition. Obesity had a positive slope, and the growth state was relatively good. The result of this study can be used as useful data to predict the trend of the L. macrochirus fauna inhabiting in 4 water dams in the Ulsan area.

• Korean Journal of Environmental Biology
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• v.37 no.2
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• pp.177-188
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• 2019

The objective of this study was to analyze the distribution patterns of two exotic disturbing fish species (largemouth bass, Micropterus salmoides and bluegill, Lepomis macrochirus), their physical habitat features, and chemical water qualities from 13 sites of Dongjin River. The relationships between the fish distributions and water chemistry and physical habitat characteristics (i.e., bottom substrate) were evaluated by comparing dominant vs. absent regions of largemouth bass and bluegill. The relative abundance of the two species decreased sharply with decreased in the water quality in terms of BOD, PO₄-P and pH, but not with NO₃-N and conductivity. The bluegill showed no difference in habitat preference between the two regions with regard to the bottom structure, while the largemouth bass had significant differences in the bottom structures of silt, coarse gravels and boulders. The dominant species were Zacco platypus (14.6%), Lepomis macrochirus (14.0%), and Micropterus salmoides (9.8%) in the order of relative abundance, indicating that exotic species (24% in total) dominated the fish community, perhaps ensuing large ecological disturbances on the ecosystem. In conclusion, the results of this study suggest that the distribution of the two exotic species may be largely influenced by water quality of organic matter and nutrient pollutions.

• Journal of Life Science
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• v.26 no.10
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• pp.1105-1112
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• 2016

The aim of this study was to examine the metabolic adjustment of lactate dehydrogenase (EC 1.1.1.27, LDH) isozymes to the environmental temperature in bluegill (Lepomis macrochirus). This study included three groups of bluegill collected in April (group Ⅰ), May (group Ⅱ), and September (group Ⅲ). The LDH activities of skeletal muscle, heart, and brain tissues were higher in group Ⅲ than in groups Ⅰ and Ⅱ. The citrate synthase (EC 4.1.3.7, CS) activity was higher in skeletal muscle but lower in heart and brain tissues of group Ⅱ as compared to group Ⅰ. In contrast, the CS activity was lower in skeletal muscle and higher in heart and brain tissues in group Ⅲ than in group Ⅱ. Furthermore, the LDH/CS activity ratio was higher in the skeletal muscle and brain in group Ⅲ than in groups Ⅰ and Ⅱ. Accordingly, anaerobic metabolism was increased in group Ⅲ. LDH A₄, A₂B₂, and B₄ isozymes were expressed in skeletal muscle, heart, liver, and brain tissues. The LDH C hybrid was detected in brain tissue. The LDH A₄ isozyme was successfully purified by affinity chromatography. The molecular weight of the purified LDH A₄ isozyme was 136 kDa and its optimal pH for enzymatic activity was 8.0. The K_m^PYR values of LDH in skeletal muscle were 0.161-0.227 mM using pyruvate as a substrate. These kinetic properties of LDH in skeletal muscle are consistent with the fact that bluegill is a cold-adapted species. These results may be useful for predicting the habitat use of this fish.

• Parasites, Hosts and Diseases
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• v.56 no.5
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• pp.509-513
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• 2018

Present study was performed to survey infection status of digenetic trematode metacercariae in 2 alien fish species, Micropterus salmoides (largemouth bass) and Lepomis macrochirus (bluegill), in 2 rivers draining Chungcheongbuk-do, Republic of Korea. A total of 107 largemouth bass and 244 bluegills were caught in Daecheong-ho (ho=lake) and Musim-cheon (a branch of Geum-gang), in Chungcheongbuk-do April-July 2015. Additionally, 68 native fish of 5 species, i.e., Zacco platypus, Hemibarbus longirostris, Carassius auratus, Pseudogobio esocinus and Puntungia herzi, were caught from the same water bodies. All of the fish collected were examined by artificial digestion method. The metacercariae of Centrocestus armatus, Clinostomum complanatum, Metagonimus sp. and Diplostomum spp. were detected from 4 out of 5 native fish species in Daecheong-ho. However, any metacercariae were not found from 87 M. salmoides and 177 L. macrochirus in Daecheong-ho. In Musim-cheon, metacercariae of Exorchis oviformis and Metacercaria hasegawai were detected from 78% Z. platypus and 34% L. macrochirus, but any metacercariae not found in M. salmoides. We report here that the 2 alien fish species were less infected with the metacercariae than the native ones. Surveys on the metacercariae in the alien fish species in geographically various rivers should be undertaken for better understanding on the role of alien fish species in the trematode infections in Republic of Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.1
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• pp.24-32
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• 1987

Bluegill, Lepomis macrochirus RAFINESQUE, has bred widely in the various districts of Korea since the Office of Fishery transplanted it into our country from Japan in December, 1969. On August 17, 24 in 1985, bluegill were caught in the reservoir of Habuk-Myon, Yangsan-Gun, $Ky\breve{o}ngsangam-Do$, Korea. They spawned in the rearing aquarium on July 13 and August 2 in 1986. The eggs of this species are adhesive and demersal. The size of the egg diameters were varied from 1.18 to 1.30 mm. Hatching took place in 40 hours after fertilization at the water temperature of $24.3-25.4^{\circ}C$. The newly botched larvae were 3.75-4.05 mm in total length possessing yolk sac, and 29-30 mytomes. Many melanophores were evenly distributed on the entire body. Ten days after hatching, the postlarvae attained 6.05-6.35 mm in total length. The yolk sac was completely absorbed and the width of the pectoral finfold had reached the maximum size. One month fifteen days after hatching, the juvenile attained 25.20 mm in total length.

• Korean Journal of Environment and Ecology
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• v.34 no.6
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• pp.543-550
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• 2020

This study aimed to identify the characteristics of fish inhabiting Hapcheon Dam and surrounding rivers and the Bluegill population, an invasive species, and provide basic data. The survey of fish living in Hapcheon Dam and surrounding tributaries in the Ulsan area from 2016 to 2017 identified a total of 1,785 individuals of 30 species of 10 families and identified 8 Korea's endemic species (21.8% indigenization rate), 3 exotic species, and 2 ecosystem disturbance species. The comparison of this study with the past survey showed that 36 species of 12 families were reported in the past survey, but 14 species of them were not found in this study. We believe that a more detailed survey of Lake Hapcheon should identify most of them. The analysis of the length-weight relationship for the Bluegill population, identified as the dominant species in the Hapcheon Lake, showed that a large number of populations was in the stage of rapid growth as a large number of populations aged 1 to 2 years was found. Since the obesity level and the length-weight relationship were confirmed to be in good condition, it was necessary to prepare a plan to control the Bluegill population. We expect that this study's results can be useful data for understanding the growth and trends of the Bluegill population inhabiting the Hapcheon Dam and surrounding rivers.