• The Korean Journal of Ecology
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• v.24 no.3
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• pp.149-156
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• 2001

Zostera caespitosa Miki has been identified to be distributed along the seacoasts of Korea and Japan. This study was intended to clarify the morphological characters and the habitat characteristics of Korean Z. caespitosa. It was confirmed that Z. caespitosa is distributed along the seacoasts of South, Yellow and East Seas of South Korea. The habitats were located in the bay and port with the depth varying from 2.5 to 5.2 m. The habitats of Z. caespitosa were rather deeper than that of mixed bed with Z. marina. The sediment in the habitats was composed of well-sorted fine sand or muddy sand. Z. caespitosa showed marked differences in several morphological characters among sites. Morphology of Z. caespitosa varied with water depths, grain size and organic contents of sediments. Flowering shoots occurred by water temperature of 6.0∼13.7℃ from January to early April.

• Ocean and Polar Research
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• v.24 no.4
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• pp.345-357
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• 2002

Ecological characteristics on habitats and morphological features of the seagrass Zostera caulescens Miki in Korea were examined. The biogeographical distribution of Z. caulescens was confirmed in the south coast of the Korea. Zostera caulescens usually inhabits at the inner bay, where is sheltered from wave action and 3.0 to 6.5 m deep. The sediment in habitats is composed of very fine muddy sand or sandy mud. In morphology, Z. caulescens is easily distinguished from other species of the genus by the formation of vegetative canopy on the top of reproductive stems. The number of longitudinal ribs in testa was 24 revealed by scanning electron microscope (SEM) while the number of ribs in Z. marina has been often reported to be 16-20. Purplish anthocyanin spots were displayed on the surface when the testa was removed. We found that the size and shape of leaf epidermal cells in Z. caulescens were very different from those of Z. marina when the leaf cuticles were removed by maceration which could be useful characters for identifying Zostera species. The leaf of Z. caulescens displays two different casts of color when the fresh plant is closely observed. The margins of leaves appear brighter than the center of leaves due to the thickening by the development of paralleled venation in the middle of leaves. The comparison of two populations of Z. caulescens in Korea showed that they were considerably different in their shoot density and biomass. The shoot density and biomass at Gabae population was $367.3 m^{-2}\;and\;725.7g$ dry wt $m^P{-2}$ respectively, while those at Jukrim population were $112.5m^{-2}\;and\;392.0g\;dry\;wt\;m^{-2}$, respectively.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2002.05a
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• pp.573-574
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• 2002

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2001.12a
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• pp.125-125
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• 2001

• ALGAE
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• v.23 no.1
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• pp.83-90
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• 2008

Eelgrass beds are very productive and provide nursery functions for a variety of fish and shellfish species. Management for the conservation of eelgrass beds along the Korean coasts is critical, and requires comprehensive strategies such as vegetation mapping. We suggest a mapping method to spatial distribution and quantify of eelgrass beds using a digital echosounder. Echosounding data were collected from the northeast part of Kwangyang Bay, on the south of Korea, in March, 2007. A transducer was attached to a boat equipped with a DGPS. The boat completed a transect survey scanning whole eelgrass beds of 11.7 km2 with a speed of 1.5-2 m s-1 (3-4 knot). The acoustic reflectivity of eelgrass allowed for detection and explicit measurements of canopy cover and height. The results showed that eelgrass bed was distributed in depth from 1.19 to 3.6 m (below MSL) and total dry weight biomass of 4.1 ton with a vegetation area of 4.05 km2. This technique was found to be an effective way to undertake the patch size and biomass of eelgrass over large areas as nondestructive sampling.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.2
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• pp.122-128
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• 2004

On the basis of monthly samples, we investigated the seasonal variation and feeding habits of amphipods inhabiting Zostera marina beds in Gwangyang Bay. Dominant species $(>1\%$ of the total number of amphipods) consist of 5 gammarids (Gammaropsis japonicus, Jassa slatteryi, Pontogenia rostrata, Atylus collingi and Ceinina japonica) and 1 caprellid (Caprella tsugarensis). Mean densities of amphipods varied from the highest of $63,148\;ind.\;m^{-2}$ in-May to the lowest of $1,247\;ind.\;m^{-2}$ in September. G. japonicus and J. slatteryi dominated in summer whereas C. japonica in autumn and winter. C. japonica was found to be a carnivorous feeder consuming mainly harpacticoid copepods and unidentified crustaceans, whereas G. japonicus, J. slatteryi, and C. tsugarensis consumed both phytoplankton and detritus. Seasonal densities of amphipods were significantly related with the shoot standing crop of the eelgrass and its epiphyte. Also densities of amphipods displayed significant difference in related with the shoot density of the eelgrass among sampling stations. These results suggest that the biological interactions between the eelgrass and amphipods as well as between the carnivorous and the herbivorous amphipods may be important in the seasonal variation of amphipods inhabiting Z. marine beds.

• Fisheries and Aquatic Sciences
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• v.12 no.3
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• pp.219-226
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• 2009

Seasonal variation in the biomass of eelgrass (Zostera marina) and epiphytic algae in two eelgrass beds (Dongdae and Aenggang Bay) around Namhae Island was investigated throughout 2005. Shoot density and eelgrass biomass differed across months and locations. Peak shoot density occurred from April to August 2005, whereas eelgrass biomass was higher in July and August 2005. Shoot density as well as eelgrass biomass were higher in Dongdae Bay compared to Aenggang Bay. A total of 21 epiphytic algal species (4 Chlorophyta, 2 Phaeophyta, and 15 Rhodophyta) were collected, and dominant species included Polysiphonia japonica, Lomentaria hakodantensis, Symphyocladia latiuscula, Champia sp., and Heterosiphonia japonica. Seasonal variation in both the species composition and biomass of epiphytic algae was substantial: peak epiphytic algal biomass occurred in January and December 2005. We also observed high epiphytic algal biomass in the eelgrass bed of Dongdae Bay. Seasonal changes in the biomass of eelgrass and epiphytic algae were primarily influenced by water temperature, whereas those of the epiphytic algal community were also correlated with eelgrass (substrate) morphology and growth, the life cycle of epiphytic algae, and physical characteristics within eelgrass beds. The spatial variation of eelgrass density and biomass were also limited by sediment characteristics.

• Fisheries and Aquatic Sciences
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• v.12 no.1
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• pp.60-69
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• 2009

Fish community structure between eelgrass beds and an adjacent unvegetated area was investigated. Fishes were collected monthly from two eelgrass beds (Gamak and Yeoja Bays) and one adjacent unvegetated area in the southern sea of Korea between February 2006 and February 2007. The number of species for the Gamak and Yeoja Bays were 33, 28, respectively, while 28 species were identified from the unvegetated area. Leiognathus nuchalis was dominant in both Gamak and Yeoja Bays, while Engraulis japonicus was dominant in the unvegetated area. Cluster analysis conducted on total number of individuals for each species produced 3 groups; group A (appeared only in winter regardless of eelgrass), group B (appeared in eelgrass beds during all seasons except winter) and group C (appeared in the unvegetated area during all seasons except winter). The most important differentiating species between eelgrass beds and the unvegetated area were Lateolabrax japonicus, L. nuchalis, Takifugu niphobles and Pholis nebulosa. Based on the results of this study we can assume that eelgrass beds function as a nursery ground for young fishes from spring to fall, but not in winter.

• Journal of Aquaculture
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• v.21 no.4
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• pp.278-284
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• 2008

Artificially-produced juvenile black sea bream Acanthopagrus schlegeli (total length $8.3{\pm}1.0\;cm$, body weight $11.2{\pm}4.2\;g$) were released in eelgrass, Zostera marina bed and their initial food organism and changes of body compositions were investigated for one month after release. Predation rates in fish sampled on 1st and 3rd days were 79%, increased up to 100% on 7th and 10th days, and then decreased on 30th days as 75%. Major prey organisms was composed of mainly Amphipoda and Gastropoda. Ratio of Amphipoda and Gastropoda in stomach were highest in fish sampled on 15th and 1st days after release, respectively. Crustacea and Algae were maintained about 20% during a sampling period. Visceral weight index (VWI) offish sampled 20th and 30th after release were significantly higher than that of initial. Carcass crude protein and lipid contents of released fish were showed significantly decreasing; however carcass n-3 HUFA composition was showed increasing tendency with the passage of time after release. Eelgrass bed was supposed to be helpful for the released fish to adjust their feeding habits and biochemical metabolism to the natural environment within a short period after release.

• Korean Journal of Environmental Biology
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• v.29 no.4
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• pp.362-372
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• 2011

The relationships among total epiphytes, algal epiphytes and eelgrass ($Zostera$ $marina$ L.) were studied at eelgrass medows from July, 1998 to July, 1999 in Yulim-ri, Yeosu, Korea. Epiphytic diatoms on eelgrass leaves were observed from July to December 1998. From the results of this study, we inferred the following three (3) conclusions : 1) As eelgrass grew older, biomass of epiphytes increased, according to relationships between the leaf length and area of eelgrass and biomass (DW, AFDW and Chl. $a$) of epiphytes. 2) According to the ratio of dry weight, ash-free dry weight and Chlorophyll of epiphytes, the algae with calcareous or siliceous skeletons, such as coralline algae or diatoms, were dominated in the epitphytic algae community. 3) The autotrophic index (AI) calculated from AFDW and Chl. $a$ of epiphytes varied from 151 to 375. However, the period of autotrophic community was shorter than heterotrophic community and the value of AI was high. From these results, we inferred that heterotrophic community, including detritus or microorganisms were dominated in the most of research period.