• Korean Journal of Ichthyology
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• v.28 no.1
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• pp.41-46
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• 2016

The feeding habits of juvenile (14.0~29.0 mm SL) of Gymnogobius heptacanthus were examined based on 229 individuals, that collected from June to August 2011 in the coastal water of Geoje, Korea. G. heptacanthus fed mainly on copepods which constituted 96.74% in IRI. Barnacle larvae were the second largest dietary component. Its diet also included small quantities of tintinnids, cladocerans and decapods. Graphical analysis of the diet composition showed that G. heptacanthus is a specialized predator characterized by strong individual feeding specialization. Especially copepods were heavily selected by of juvenile G. heptacanthus regardless of prey availability.

• Korean Journal of Ichthyology
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• v.22 no.1
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• pp.65-77
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• 2010

To use the precise scientific name of the genus Gymnogobius from Korea, a taxonomic review of the genus Gymnogobius was made based on specimens collected in streams and estuaries of Korea from 1982 to 2007. The genus Gymnogobius in Korea includes 7 species: Gymnogobius breunigii (Steindachner), G. heptacanthus (Hilgendorf), G. macrognathos (Bleeker), G. mororanus (Jordan and Snyder), G. opperiens Stevenson, G. petschiliensis (Rendahl), G. urotaenia (Higendorf). A key to species of the genus Gymnogobius from Korea is provided, with description of their morphological characteristics and their distribution.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.4
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• pp.227-233
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• 2013

A total of 25 species, 3,880 individuals and 3,145.1 g of fishes were collected by a surf net from the eelgrass bed in Minyang. Most fishes collected in the eelgrass bed belong mainly to small fish species or juveniles. The dominant fish species were Gymnogobius heptacanthus, Rudarius ercodes, Pholis nebulosa, Chaenogobius gulosus, and Gymnogobius castaneus which accounted for 89.1% of total number of individuals collected. The number of individuals and biomass were higher from June to September when the water temperature was high. However, both the number of individuals and species showed the lowest from January and February. Highest species diversity index (H') was observed in April, 2012.

• Korean Journal of Ichthyology
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• v.23 no.3
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• pp.225-233
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• 2011

This is the attempt to study the fish assemblages in eelgrass bed of Jeogu on Geoje Island, Korea. Samples were collected by surf net monthly from August 2009 to July 2010. A total 38 species, 2,335 individuals, and 5,289.8g of fishes were collected. The dominant species were Chaenogobius annularis, Gymnogobius heptacanthus, Rudarius ercodes, Siganus fuscescens, Ditrema temminckii, Takifugu niphobles, Aulichthys japonicus, Pseudoblennius cottoides, Syngnathus schlegeli, Sebastes schlegelii, Pterogobius elapoides, Urocampus nanus, Takifugu pardalis, Hypodytes rubripinnis which accounted for 94.2% of total number of individuals of fish collected. Eelgrass biomass showed a peak in August (DW 121.5g/m$^2$), low values in November (DW 74.9 g/m$^2$) to February (DW 49.3g/m$^2$), and started growing from May (DW 112.8g/m$^2$). Gymnogobius heptacanthus, Sebastes schlegeli, Takifugu niphobles, Syngnathus schlegeli, Urocampus nanus were collected year-round with no clear relationship to the biomass of eelgrass bed.

• Korean Journal of Ichthyology
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• v.23 no.2
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• pp.119-127
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• 2011

Fish species composition in eelgrass bed of Geoje island, Korea was determined using monthly samples collected by a surf net from August 2009 to July 2010. A total of 31 species, 1,387 individuals and 4,776.5 g of fishes were collected. The dominant species were Rudarius ercodes, Gymnogobius heptacanthus, Ditrema temminckii, Takifugu niphobles, Hypodytes rubripinnis, Chaenogobius annularis, Aulichthys japonicus, Syngnathus schlegeli, Pterogobius elapoides which accounted for 89.3% of total number of individuals of fish collected. Eelgrass biomass showed a peak in August (DW 154 g/$m^2$), low values in November (DW 31 g/$m^2$) to February (DW 41 g/$m^2$), and started growing from May (DW 78 g/$m^2$). The biomass of fish increased by the catch of a large number of Gymnogobius heptacanthus, Chaenogobius annularis, Pterogobius elapoides, Rudarius ercodes and Pseudoblennius percoides in May and September when the eelgrass grew fast. Meanwhile, Syngnathus schlegeli, Urocampus nanus and Aulichthys japonicus were collected year-round with no clear relationship to the biomass of eelgrass bed.

• Korean Journal of Ichthyology
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• v.22 no.3
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• pp.179-185
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• 2010

This is a study of the fish assemblages in eelgrass beds of Geoje Bay on Geoje Island, Korea. Samples were collected by surf net monthly from June 2006 to May 2007. A total 26 species, 1,825 individuals, and 4,483.1 g of fishes were collected. The dominant species were Acentrogobius pflaumii, Aulichthys japonicus, Gymnogobius heptacanthus, Rudarius ercodes, Chaenogobius annularis, Gymnogobius urotaenia, Syngnathus schlegeli, Pterogobius elapoides, Zoarchias glaber, Takifugu niphobles, Zoarchia suchidai. These species accounted for 90.6% of the total number of individuals and 76.2% of the biomass of the fishes collected. The fish assemblages in the eelgrass beds showed clear seasonal changes; the number of fish species and individuals increased in March and were highest in September, whereas the biomass attained its highest level in May and subsequently decreased. Meanwhile the species diversity indices showed their highest value in December.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.3
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• pp.278-285
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• 2018

Monthly variation in species composition of fishes in the eelgrass bed of Jangpyeong in Tongyeong, Korea was determined using monthly samples from a seine net from May 2016 to April 2017. A total of 32 species, 2,042 individuals and 3,991.1 g of fishes were collected during the study period. The dominant species were Takifugu niphobles, Rudarius ercodes, Gymnogobius heptacanthus, Zoarchias glaber, Pholis nebulosi and Leucopsarion petersii. These species accounted for 79.5% of the total number of individuals. The fish assemblages in the eelgrass bed showed clear seasonal changes: the number of fish species increased in March and was highest in October, while the number of individuals increased in December and was highest in July.

• Korean Journal of Ichthyology
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• v.30 no.1
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• pp.55-64
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• 2018

Fish assemblages in a sandy shore and an eelgrass bed were compared based on monthly samples in the southern coastal water of Korea. Samples were collected by a beam trawl in the sandy shore and a surf net in the eelgrass from March to February 2012. The common fish species were Syngnathus schlegeli, Pseudoblennius cottoides, Pholis nebulosa, Favonigobius gymnauchen, Gymnogobius heptacanthus, Pseudopleuronectes yokohamae, Takifugu niphobles. Among them S. schlegeli, Urocampus nanus, P. cottoides, P. nebulosa, T. niphobles were high abundance in the eelgrass bed than in the sandy shore, whereas Acanthogobius flavimanus, Acentrogobius pflaumi, F. gymnauchen, G. heptacanthus, P. yokohamae were high in the sandy shore. Aulichthys japonicus, Hippocampus coronatus, Sebastes inermis, Lateolabrax japonicus, Siganus fuscescens were found in the eelgrass bed, and Thryssa hamiltoni, Mugil cephalus, Inimicus japonicus, Platycephalus indicus, Hexagrammos otakii, Furcina ishikawae, Liparis tanakae, Repomucenus curvicornis, and Eutaeniichthys gilli were observed in the sandy shore. Species composition and abundance varied seasonally in two habitats; The number of species and abundance was high in August and September, while biomass was the highest in April and September. Fish numbers as well as biomass were lowest in February. Number of individuals and biomass of fish in the eelgrass bed were significantly higher than those of in the sandy shore. Some fish preferred to live in the eelgrass were collected in the sandy shore, while fish preferred to live in the sandy shore were rarely collected in the eelgrass.

• Korean Journal of Ichthyology
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• v.28 no.4
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• pp.249-259
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• 2016

Monthly variation in species composition was determined using fish samples collected by a beach seine between October 2013 and September 2014 in the eelgrass bed in Aenggang Bay, Namhae, Gyeongsangnamdo. A total of 3,174 individuals of 35 species, amounting to 3,137 g were collected. The dominant species was Gymnogobius heptacanthus, followed by Pholis nebulosa, Rudarius ercodes, Favonigobius gymnauchen and Hypodytes rubripinnis. Almost all fish collected were small in size or juveniles. Seasonal variation of species composition showed that the dominant species, used the shallow area of the eelgrass bed as a nursery ground and moved to a deeper water as they grew. Saurida elongata, Inimicus japonicus, Sphyraena pinguis, and Arothron hispidus, were first reported in an eelgrass bed in the southern coastal water.

• Korean Journal of Ichthyology
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• v.29 no.2
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• pp.130-138
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• 2017

Fish species composition in eelgrass bed of Bongam on Hansando island, Korea was determined using monthly samples collected by a surf net from August 2009 to July 2010. A total of 30 species, 3,237 individuals and 6,850.1g of fish were collected. The dominant species were Gymnogobius heptacanthus, Rudarius ercodes, Takifugu niphobles, Chaenogobius annularis, Pterogobius elapoides and Syngnathus schlegeli which accounted for 86.7% of total number of individuals of fish collected. Eelgrass started growing from May ($DW61.9g/m^2$) showing a peak biomass in August ($DW81.6g/m^2$), and low values in November ($DW57.23g/m^2$) to February ($DW15.41g/m^2$). The fish assemblages in the eelgrass beds showed clear seasonal changes; the number of fish species and individuals were low from September to December 2009, and high from December 2009 to July 2010. Seasonal variation in species composition and abundance was related to the water temperature and standing crops of eelgrass.