• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.1
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• pp.56-62
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• 1998

Seasonal variations of eelgrass and epiphytic algae in eelgrass beds in Kwangyang Bay were studied from January 1994 to December 1994. A peak of the shoot length and standing crop of eelgrass occurred in summer, but low values were observed in fall and winter. The dominant species of epiphytic algae were Callophyllis rhynchocarpa and Champia sp. In spring and summer, while Polysiphonia japonica and Lomentaria hakodatensis in fall and winter. In contrast to the eelgrass, the standing crop of epiphytic algae showed a minimum in summer. There was a gradual increase in the standing crop of epiphytic algae during fall, and a peak of standing crop occurred in winter. Epiphytic algae accounted for approximately $15\~20\%$ of total plant standing crops of the eelgrass meadows. Correlation analysis with environmental factors indicated that temperature influences on both the standing crop of eelgrass and epiphytic algae. There was a positive relationship between the standing crop of eelgrass and temperature, while there was a reverse relationship between that of epiphytic algae and temperature.

• Korean Journal of Ichthyology
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• v.24 no.3
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• pp.191-200
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• 2012

Fish species composition in eelgrass bed of Punghwa-ri in Tongyeong, Korea was determined using monthly samples collected by a surf net from November 2010 to October 2011. During the study period, a total of 30 species, 5,511 individuals and 6,933.4 g of fishes were collected. The dominant fish species were Pholis nebulosa, Syngnathus schlegeli, Rudarius ercodes, Pseudoblennius cottoides, Sebastes inermis, and Aulichthys japonicus which accounted for 93.4% of total number of individuals collected. Most fishes collected in the eelgrass bed belong mainly to small fish species or juveniles of large fish species. Eelgrass shoot density reached a peak in April 2011, and then decreased to a minimum in January 2011. The seasonal variation of fish assemblage in an eelgrass bed of Punghwa-ri was correlated to the variations in the water temperature, eelgrass density and biomass, and abundances of major prey organisms.

• Korean Journal of Ichthyology
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• v.18 no.3
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• pp.178-183
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• 2006

Diel changes in the feeding habits of Rudarius ercodes were investigated in an eelgrass bed of Jindong Bay, Korea. The main food components for R. ercodes (1.6~ 4.3 cm SL) were gammarid amphipods, eelgrass, polychaetes and urochordates. Most dietary items were inhabitants of an eelgrass bed. Diel variations in diet and feeding activity occurred. The diet of R. ercodes underwent changes from eelgrass and gammarid amphipods (omnivore) at day to mainly gammarid amphipods, polychaetes, and urochordates (carnivore) at night. Rudarius ercodes probably took detached eelgrass leaves and grazed live eelgrass during day, whereas feeding on gammarid amphipods, polychaetes, urochordates, and bivalves were facilitated by nocturnal movement and activity of these prey during night. The feeding activity of R. ercodes was also correlated with periods of high tides.

• ALGAE
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• v.19 no.1
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• pp.39-47
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• 2004

Production dynamics of eelgrass, Zostera marina was examined in Jindong Bay on the south of the Korea peninsula. Eelgrass leaf productivities and environmental factors such as underwater photon flux density, water temperature, and nutrient availabilities in the water column and sediments were monitored from March 2002 to December 2003. While water temperature exhibited a distinct seasonal trend, underwater irradiance and nutrient availabilities exhibited high degree of fluctuation, and did not show a seasonal trend throughout the experimental periods. Eelgrass leaf elongation and production rates showed significant seasonal variations. Leaf productivity was highest in May (30.0 mg dry wt sht$^{-1}$ d$^{-1}$ or 3.7g dry wt m$^{-2}$d$^{-1}$) and lowest in November (3.2 mg dry wt sht$^{-1}$ d$^{-1}$ or 0.12 g dry wt m $^{-2}$ d$^{-1}$). Eelgrass leaf productivities did not show a strong correlation with underwater irradiance or environmental nutrient availabilities. The production rates, however, were positively correlated with water temperature during spring periods, and were correlated negatively at high water temperature exceeded 20℃ during summer months. While relative growth rates were highest in spring and lowest in high water temperature periods, plastochrone interval was longest during summer and shortest during spring. These results imply that seasonal growth dynamics of eelgrass, Z. marina was mainly controlled by water temperature.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.3
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• pp.259-269
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• 2014

The objectives of this study to determine seasonal changes in species composition and abundance of fish and decapod assemblage, and the relationships between environmental factors and their abundance in an eelgrass bed of Jindong Bay. A total of 26 fish species and 29 decapod species were collected by a small beam trawl from an eelgrass bed in Jindong Bay in 2002. The dominant fish species were Hexagrammos otakii, Pholis neulosa and P. fangi and these accounted for 48.4 % in the total number of individuals. Dominant decapod taxa were Palaemon macrodactylus, Charybdis japonica, Pagurus minutus and C. bimaculata. These were primarily small species or early juveniles of larger species. Species composition and abundance varied greatly showing a peak in the number of individuals in April and May, and peak biomass in fish in July and decapods in August. Catch rate was low in winter months both in fish and in decapod. Seasonal changes in the abundance of fishes and decapods corresponded with eelgrass biomass and abundance of food organisms indirectly.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.34 no.2
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• pp.191-199
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• 1998

Feeding habits of Lateolabrax Japonicus collected from the eelgrass bed in Kwangyang Bay from January 1994 to December 1994 were studied. L. Japonicus was a carnivore which consumed mainly amphipods (gammarid amphipods and caprellid amphipods), crabs, caridean shrimps and copepods. Its diets included small quantities of fishes, mysids, polychaetes, tanaids and isopods. Three distinct ontogenetic feeding groups were noted : (1) 1~2 cm SL individuals preyed heavily on copepods. (2) 2~15 cm SL individuals preyed heavily on amphipods. (3) individuals over 15 cm SL preyed heavily on crabs, caridean shrimps and fishes. L. Japonicus showed seasonal changes in prey composition. These changes were not caused by seasonal changes in food availability, but by changes in the size composition of L. Japonicus occurred in the eelgrass bed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.45 no.1
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• pp.65-75
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• 2012

To study the difference in growth characteristics between intertidal and subtidal eelgrass Zostera marina populations, environmental factors and changes in tissue carbon (C) and nitrogen (N) contents in eelgrass from the lower intertidal and upper subtidal zones were surveyed monthly in the Seomjin Estuary from May 2003 to December 2004. Water temperatures, water column nutrient concentrations, sediment pore water, and ammonium and phosphate concentrations showed no significant differences between intertidal and subtidal zones. Sediment pore water nitrate+nitrite concentrations were slightly higher in the intertidal zone than in the subtidal zone. Average monthly exposure times in the intertidal and subtidal zones were $42.4{\pm}5.8h\;month^{-1}$ and $15.3{\pm}3.5h\;month^{-1}$, respectively. Eelgrass leaf N content decreased from March to August and increased from September to February in the subtidal zone, whereas these trends were not observed in the intertidal zone. Eelgrass rhizome C content increased from April to September and decreased from October to March in the subtidal zone, whereas those tendencies were not recorded in the intertidal zone. Eelgrass rhizome C:N ratios showed a strong reverse trend to leaf C:N ratios in the subtidal zone, but these tendencies were not observed in the intertidal zone. The effects of exposure appeared to cause no seasonal trend in eelgrass tissue C and N content or C:N ratios in the intertidal zone in the Seomjin Estuary.

• Journal of the korean society of oceanography
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• v.38 no.2
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• pp.68-79
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• 2003

Although seagrasses are relatively abundant, few studies have been conducted on seagrass physiology and ecology in Korea. Zostera marina is the most abundant seagrass species, widely distributed throughout all coastal areas of the Korean peninsula. To examine seasonal dynamics and spatial variations of eelgrass, Zostera marina distributed on the coast of Korea, morphological characteristics, biomass, tissue nutrient constituents, leaf productivity and environmental factors were monitored monthly from the eelgrass beds in Kabae Bay and Kosung Bay on the south coast of the Korean peninsula from June 2001 to June 2002. Eelgrass density, biomass, morphological characteristics, leaf productivities, and tissue nutrient constituents exhibited clear seasonal variations, and these seasonal trends reflected seasonal changes in water temperature. Eelgrass shoot density and biomass at Kabae Bay site showed more obvious seasonal trends than Kosung Bay. No strong seasonality in Kosung Bay site appeared to be caused by high water temperature ($>30{\circ}C$) during summer months at this site. Despite differences in nutrient availabilities between two study sites, eelgrass biomass and leaf productivities were not significantly different between study sites, and this lack of spatial variations implies that the ambient nutrient availabilities at the present study sites are in excess of seagrass nutrient demand. Eelgrass tissue N content and sediment pore water DIN concentrations exhibited reverse relationship at the present study. This reverse relationship suggests in situ nutrient concentrations are not good indicator of nutrient availabilities, and regeneration and turnover rates of sediment nutrients are also important factors to determine nutrient availabilities at the site.

• 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.18 no.2
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• pp.119-128
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• 2006

Fish assemblages associated with eelgrass beds and unvegetated area were compared based on specimens collected every month in Jindong Bay. The common fish species were Hexagrammos otakii, Acanthopagrus schlegeli, Lateolabrax japonicus, Pholis nebulosa, P. fangi, Leiognathus nuchalis, Repomucenus valenciennei, and Acanthogobius flavimanus. H. otakii, A. schlegeli, P. nebulosa and L. japonicus were higher abundance in an eelgrass bed than unvegetated area, whereas P. fangi, R. valenciennei and A. flavimanus were higher in unvegetated area. Sillago japonicus, Hippocampus japonica, Takifugu niphobles, Pseudoblennius percoides, Sebastes inermis, Syngnathus schlegeli, Sebastes schlegeli were found in an eelgrass bed, but not in unvegetated area. Most of fish species were primarily small fish species or juveniles of fish species in an eelgrass bed, while larger fish species were found in unvegetated area. The eelgrass bed in Jindong Bay seem to play a nursery role for fishes. Seasonal variations in both species composition and abundance were large in two habitats; higher number of species and individuals occurred May 2002, and April 2002 to July 2002, while biomass was the highest in April 2002 and July 2002. Fish numbers as well as biomass were lowest in January 2002. Species richness, number of individuals and biomass of fishes in an eelgrass bed were significantly higher than those of in unvegetated area. These result suggest that differences in fish species richness and abundances are primarily related to habitat structure. Different habitat preferences were evidenced for the juveniles and adult of several fish species.