• Journal of Environmental Science International
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• v.23 no.9
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• pp.1563-1572
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• 2014

The autecology of the Zostera marina and Z. japonica was studied in populations growing in the same locality (Sagumi Bay, southwestern coast of Korea). Environmental factors and plant characteristics were examined monthly from August 2008 to September 2011. Along intertidal zone, Z. japonica (0.1-0.5 m above mean lower low water, MLLW) occurred above Z. marina (0.5-2.5 m MLLW). Tidal exposure at low tide during day was the highest in the spring and the lowest in the summer. Underwater Irradiance showed seasonal fluctuation that was the highest in spring and summer caused by tidal pattern. Strong seasonal patterns in water temperature appeared to control the seasonal variations in morphology, biomass and leaf growth. The seasonal pattern of Z. japonica resembled that of the Z. marina in morphological characteristics, above-and below-ground biomass, whereas it differed in shoot density and leaf elongation. Despite some similarities in seasonal growth patterns, the patterns of Z. japonica were lagged by 2 month of Z. marina. Seasonal variation in the above biomass of Z. marina was caused by changes in density and plant size, whereas that of Z. japonica was mainly caused by changes in shoot density. Zostera marina was more sensitive to high temperatures than Z. japonica, and the increasing water temperature during the summer became the factor that inhibits the growth of the Z. marina. Zostera Japonica, there is no clear change according to the amount of the light. It is because its habitat locates above that of Zostera marina so that the amount of the light that is necessary to growth is enough and in this condition, any preventing factor does not seem to work at all. Although underwater light getting into Zostera marina's habitat is very low level and there is no any hindrance to the survival of them, it prevents them from their productivity a bit.

• Journal of Ecology and Environment
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• v.41 no.3
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• pp.45-53
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• 2017

Background: There have been many studies on the growth conditions of Zostera marina and Zostera japonica, but few studies have examined how spatial and temporal factors affect growth in established seagrass beds or the distribution range and shoot density. This study aims to clarify the factors that determine the temporal and spatial distribution of Zostera marina and Zostera japonica in the Seto Inland Sea east of Yamaguchi Prefecture. Methods: The study site is in Hiroshima Bay of the Seto Inland Sea, along the east coast of Yamaguchi Prefecture, Japan. We monitored by diving observation to confirm shoot density, presence or absence of both species and observed water temperature, salinity by sensor in study sites. Results: The frequency of occurrence of Zostera marina was high in all seasons, even in water depths of D.L. + 1 to -5 m ($80{\pm}34%$ to $89{\pm}19%$; mean ${\pm}$ standard deviation), but lower (as low as $43{\pm}34%$) near the breakwall, where datum level was 1 to 2 m, and it was further reduced in datum level -5 m and deeper. The frequency of occurrence of Zostera japonica was highest in water with a datum level of +1 to 0 m. However, in datum level of 0 m or deeper, it became lower as the water depth became deeper. Datum level +1 m to 0 m was an optimal water depth for both species. The frequency of occurrence and the shoot density of both species showed no negative correlation. In 2011, the daily mean water temperature was $10^{\circ}C$ or less on more days than in other years and the feeding damage by S. fuscescens in the study sites caused damage at the tips. Conclusions: We considered that the relationship between these species at the optimal water depth was not competitive, but due to differences in spatial distribution, Zostera marina and Zostera japonica do not influence each other due to temperature conditions and feeding damage and other environmental conditions. Zostera japonica required light intensity than Zostera marina, and the water depth played an important role in the distribution of both species.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.4
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• pp.351-361
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• 2010

Among common estuarine submerged plants, seagrasses are the most extensively studied due to their ecological importance in estuarine ecosystems. Seagrass meadows are important biological habitats for a wide variety of marine animals and plants. They are a source of organic carbon for commercially important animals. Furthermore, seagrasses act as nutrient filters in estuarine and coastal marine ecosystems. As such, mapping the distribution of seagrass beds is important for management and conservation strategies. In order to survey the seagrass distribution within the Seomjin Estuary, We directly observed seagrass beds in Kwangyang and Hadong using SCUBA. The distribution area, species composition, morphology, density, biomass and productivity of seagrass meadows were examined. Seagrass meadows were distributed in the intertidal and subtidal zones of the Galsa tidal flats, and in the subtidal zone of the neighboring POSCO area. Patches of Zostera japonica was found at patches at the Galsa tidal flats intermediate point. The total estimated seagrass distribution area of the Seomjin Estuary was $1.84\;km^2$. Of the total, $1.83\;km^2$ was Zostera marina (eelgrass) and $0.01\;km^2$ was Zostera japonica (dwarf eelgrass). Zostera japonica was found in intertidal zones. Zostera marina was found from the intertidal to subtidal zones at a 2 m mean sea level (MSL) depth. The leaf productivity of Zostera marina was $4.47g\;DW\;m^{-2}\;day^{-1}$. The annual production of eelgrass was $1,632\;g\;DW\;m^{-2}\;yr^{-1}$, which corresponds to $731g\;C\;m^{-2}\;yr^{-1}$. The total production of eelgrass was $3,002\;tons\;DW\;yr^{-1}$, which corresponds to $1,343\;tons\;C\;yr^{-1}$.

• Korean Journal of Oriental Medicine
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• v.13 no.3
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• pp.11-20
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• 2007

Haedae(海帶, haidai) is representative herb from seaweeds, but its origin is still confusing. Thus we analyzed its origin on the basis of classics of oriental medicine. The scientific name of Haedae corresponds to Zostera marina, according to the folkloric use. But, it is Laminaria japonica, according to its habitat, morphological feature, and the korean name on the medical books in Joseon since 17c. In the remote past, it seemed that two groups were segragated by the name of Zostera marina Haedae and Laminaria japonica Haedae. However, it is thought that this two trends were mixed up when medical knowledge was compiled in Song Dynasty era. Documental support inclined to Laminaria japonica, but it is too early to conclude that Laminaria japonica is the Haedae. To prove this hypothesis, further study is required to investige whether Laminaria japonica or Zostera marina has mentioned efficacies of Haedae used for the treatment of wen, San syndromes, edema, scrofula, etc. And we have need of research that solve the origin problem of Gonpo(Laminariae thallus) on the assumption that Laminaria japonica is Haedae.

• ALGAE
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• v.23 no.1
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• pp.75-81
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• 2008

The epiphytic diatom flora living on leaf tissues of Zostera marina, Z. japonica and Z. caespitosa at three study sites (Dadae, Gabae, and Jangmok) located in Geoje Island has been examined from July 2001 to March 2002 bimonthly. Total 81 species in 26 genera of diatoms have been observed on leaf tissues of the 3 Zostera species throughout the present study. Cocconeis spp. were predominant on Z. japonica, whereas Navicula spp. and Nitzschia spp. were predominant on Z. marina and Z. caespitosa. The community structure of the diatom assemblages varied according to the seagrass species. Species compositions of epiphytic diatoms appear to be closely related to morphology and lifespan of seagrasses.

• KSBB Journal
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• v.29 no.4
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• pp.271-277
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• 2014

In this study, crude extract of the seagrass Zostera japonica, and its solvent-partitioned fractions were evaluated for their antioxidant activity. The crude extract was successively fractionated into n-hexane, 85% aqueous methanol (85% aq.MeOH), n-butanol (n-BuOH), and water fractions by liquid-liquid partition. These include DPPH radical scavenging, hydroxyl radical scavenging in HT-1080 cells, peroxynitrite scavenging, and protective effect on DNA damage caused by hydroxyl radicals generated. In all assays, except for DPPH radical, 85% aq.MeOH and n-BuOH fraction showed the strong antioxidant activity. These results suggest that Z. japonica may be used as a potential source of natural antioxidants for the development of cosmetic product or functional food in the future.

• Fisheries and Aquatic Sciences
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• v.7 no.2
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• pp.84-89
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• 2004

Feeding habits of Sillago japonica collected from in an eelgrass (Zostera marina) bed in Jindong Bay, Korea were studied. S. japonica was a carnivore which consumed mainly gammarid amphipods, polychaetes, bivalves, caridean shrimps and crabs. Its diets also included a small amount of fishes, copepods and caprellid amphipods. The diet of S. japonica underwent significant size-related changes; small individuals (<5cm SL) fed mainly on gammarid amphipods and crab larvae, while proportion of polychaetes and bivalves increased with increasing fish size and gammarid amphipods were also important prey for medium size individuals (5.1-9.9cm SL). The large individuals (>10cm SL) ate polychaetes, caridean shrimps and crabs. The dietary breadth of S. japonica were varied with size. The diet of S. japonica also underwent seasonal changes that could be related to differences in prey availability; gammarid amphipods were mainly consumed in spring and polychaetes in summer.

• Ocean and Polar Research
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• v.34 no.4
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• pp.385-394
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• 2012

In this study, crude extracts of the marine eelgrass Zostera japonica and their solvent-partitioned fractions were evaluated for their inhibitory effect against AGS, HT-1080 and MCF-7 human cancer cells using MTT assay. Each of the crude extracts (acetone/methylene, chloride, and methanol) of Z. japonica showed a significant inhibitory effect on the growth of human cancer cells. The combined crude extracts were partitioned between $CH_2Cl_2$ and water. The organic layer was further partitioned between 85% aq. MeOH and n-hexane, and the aqueous layer was then fractionated into n-BuOH and $H_2O$, successively. Growth inhibition effects of solvent-partitioned fractions from Z. japonica on human cancer cells increased in a dose-dependent manner. Among these tested samples, the 85% aq. MeOH fraction revealed good inhibitory effects on the growth of AGS and HT-1080 human cancer cells, while the n-hexane fraction exhibited good inhibitory effects on the growth of AGS and MCF-7 human cancer cells. In addition, 85% aq. MeOH and n-hexane fractions enhanced mRNA expression of p53 gene. These results suggest that there is further scope for the isolation of active compounds from Z. japonica, which should show much stronger anticancer activity.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.406-407
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• 2000

한반도에 서식하는 해초(Seagrass) 중 거머리말속(Zostera, Zosteraceae)은 거머말(Zostera marina), 애기거머리말(Z. japonica), 왕거머리말(Z. asiatica), 수거머리(Z. caulescens), 포기거머리말(Z. caespitosa) 5종이 기재되었다 (Miki, 1932). 이 해들은 연안의 사질 또는 사니질에 서식하며 생태계에 중요한 역할을 담당하고 있다. 그러나 연안의 매립과 개발로 인해 이들 해초지의 감소와 연안생태계의 붕괴가 진행되고 있으나 해초에 대한, 특히 Zostera속에 대한 연구는 미진하다.(중략)

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.4
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• pp.535-544
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• 1998

Seasonal variation of the crab community in the eelgrass (Zostera marina) bed in Kwangyang Bay was studied based on the monthly collections through a year of 1994. The crab community in the eelgrass bed was composed of 21 species representing 12 families. The community was dominated by Charybdis Japonica, Telmessus acutidens, Hemigrapsus penicillatus, and Pugettia quadridens. Crabs collected in the study area were primarily small-sized species or early juveniles of large crab species. Most individuals had carapace width smaller than 25 mm except C. japonica and T. acutidens which had maximum carapace width over 85 mm. More than 5 species were collected every month except January and February (4 and 3 species, respectively). The peak abundance occurred in August and low abundances in autumn and winter. Species diversity indices showed that more diverse crabs were collected In spring and summer, and lesser ones in autumn and winter. The crabs in the study area can be grouped into three groups on the basis of their occurrence patterns: resident species, seasonal species, and temporary species. More abundant and more diverse crabs were collected during nighttime than daytime.