• Journal of Life Science
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• v.26 no.4
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• pp.484-489
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• 2016

Living organisms can maintain or extend their territories by producing allelochemicals that influence the growth, survival, and reproduction of other organisms. To identify natural biostimulants of positive allelochemicals, we screened 18 common seaweed extracts for enhancement of rhizoid and blade production in a convenient Porphyra suborbiculata monospore assay. By addition of methanolic extract from the most potent green seaweed, Codium fragile, 100% and 50% enhancement doses reflecting the amount of C. fragile extract required to enhance rhizoid formation (in terms of number of spores with rhizoids per total spores tested) were approximately 100 and 50 μg/ml, respectively, in the P. suborbiculata monospore culture. The C. fragile extract quickly enhanced rhizoid formation, rhizoid numbers per rhizoid-holding spore, rhizoid length, blade formation (in number of spores with blade per total spores tested), and blade length from most monospores at early culture days. The extract enhanced rhizoid formation after 2 days of culture significantly, rhizoid numbers per rhizoid-holding spore after 3 days, rhizoid length after 3 days, blade formation after 2 days, and blade length after 1 day, respectively, from most monospores. The allelochemicals that enhanced favorite seaweed species may be efficacious for new seaweed management technologies, including the development of biostimulant agents based on natural products.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.1
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• pp.49-62
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• 1993

Structure of intertidal algal communities of the islands on the South Sea of Korea was studied in summer of 1987 and 1988. The area includes Manjedo, Ch'ujado, Kwantaldo, Munsom, Yosodo, Komumdo, Soridi, Yokchido, Pijindo and Hongdo. Three biologically distinct zones, were commonly recognized in the intertidal bulk of the all examined islands. In the high intertidal zone, only a few species showing thin, tubular and sheet like forms were observed, and the most abundant species was Gloiopeltis spp.. Corallina pilulifera, Hizikia fusiformis and Chondria crassicaulis were most abundant species of the mid intertidal zone, which was formed near the mean sea level. The structure of the low intertidal zone was much more complex than the high and mid, the most abundant species were Laurencia spp. and Sargassum sagamianum. All of the coarsely branched and articulated calcareous species were distributed below mean sea level.

• Ocean and Polar Research
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• v.26 no.1
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• pp.59-64
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• 2004

As a part of our search for novel antioxidants from the seaweeds, we have investigated radical scavenging effect for their crude extracts using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, authentic peroxynitrite, and 3-morpholinsydnonimine (SIN-1), a peroxynitrite-generating species in vitro. Thirty-four seaweeds were screened for $ONOO^-$ and DPPH radical scavenging activities. A potent inhibitory effect against peroxynitrite generated by SIN-1 at $5{\mu}g/ml$ of methanol extracts was observed in order of Ishige okamurae(95.3%), Sargassum hemiphyllum(90.2%), Symphyocladia latiuscula(89.6%), Porphyra suborbiculata(86.7%), and Gelidium amamsii(85.9%), Also, a significant scavenging effect against direct authentic peroxynitrite was revekaled for methanol extracts of Ishige okamurae(66.2%) and Sargassum hemiphyllum(55.2%) and the acetone/methylene chloride(1:1) extract of Gigatina tenella (61.0%). In our measurement for evaluating the capacity to scavenge the stable free radical of DPPH, acetone/methylene chloride(1:1) extracts of Symphyocladia latiuscula, Gloiopeltis furcata, and Sargassum thunbergii and the methanol extract of Sargassum sp. showed an inhibitory potency of 85.8%, 82.8%, 74.1%, and 64.0%, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.3
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• pp.265-273
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• 1986

The marine algal communities of Yonhwa-do at the southern coast of Korea were investigated in aspects to quantitative analysis of their structure and dynamics. As a result, 114 species, including 2 blue-green, 69 red, 25 brown and 18 green algae, were identified. The R/P value(2.8) is higher than that of other regions of the southern coast of Korea. Sheet and filamentous groups of the functional groups of algae showed higher composition rate in spring and summer than in autumn and winter, but coarsely branched and thick leathery groups showed an opposite tendency. Cluster analysis based on species presence suggested the existence of 5 distinct groups in spring, but 3 groups in the other seasons. The species exhibiting important value above 20 were as follows: Porphyra suborbiculata, Corallina pilulifera, Hizikia fusiforme, Sargassum thunbergii, Undaria pinnatifida, Ishige okamurai, Chondria crassicaulis, and crustose coralline algae. The coverage of algal communities composed only of crustose coralline algal complex was higher than that of other algal complex, but occurrence frequency of these two communities was indifferent. It is suggested that the occurrence in high quantity of crustose coralline algae from this area is related to grazing by herbivorous animals.