• Journal of Ecology and Environment
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• v.37 no.4
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• pp.351-363
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• 2014

A study on fresh-water green coccoid algae was carried out at ponds, swamps, reservoirs, lakes and rivers (290 sites) from May 2011 to January 2014. In this study, 4 genera and 13 taxa of the family Radiococaceae having the remnants of cell wall existing for a long time in the colonial gelatinous envelope are classified and identified from 24 sites. Many taxa of this family, however, have not been recorded in Korea yet. Of these 13 taxa, 5 taxa are newly recorded in Korea by this study: 1) Schizochlamydella solitaria, 2) Thorakochloris planktonica, 3) Radiococcus bavaricus, 4) R. nimbatus, and 5) R. planktonicus.

• ALGAE
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• v.28 no.1
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• pp.63-71
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• 2013

Lithothamnion muelleri is reported for the first time as one of the main components of rhodolith beds along the Eastern Pacific Ocean based on samples from Washington State (USA), Pacific Baja California (M$\acute{e}$xico), southern Nicaragua, and Costa Rica. Individual rhodoliths ranged from fruticose to lumpy in morphology, and bi-sporangial, tetrasporangial, and gametangial plants were similar to those described from Australia and Brazil. Our study revealed a surprisingly wide latitudinal distribution of this species along the American continent. Its documentation in the Eastern Pacific will facilitate a more accurate interpretation of the ecology, biology, and biogeography of rhodolith beds worldwide.

• Korean Journal of Ecology and Environment
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• v.38 no.spc
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• pp.31-38
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• 2005

Diel change in urea decomposition activity of epiphytic algae on Phragmites stems and phytoplankton in a shallow littoral reed zone in the south basin of Lake Biwa was investigated with an in situ technique using $^{14}C$-labelled urea. The daily rates of urea decomposition (sum of urea carbon incorporation rate and $CO_2$ liberation rate) by epiphytic and planktonic algae were calculated as 180 ${\mu}$ mole urea surface shoot area $m^{-2}\;day^{-1}$ and 210 ${\mu}$ mole urea $m^{-3}\;day^{-1}$. The chlorophyll a specific urea decomposition rates of epiphytic and planktonic algae were 4.7 to 6.4 and 4.4 to 6.2 ${\mu}$ mole urea mg chl. $a^{-1}$ incubation $time^{-1}$ in daytime and 4.2 to 5.7 and 2.4 to 3.5 ${\mu}$ mole urea mg chl. $a^{-1}\;time^{-1}$ in nighttime, respectively. High values were obtained during 12:00 ${\sim}$ 18:00 and low values during 00:00 ${\sim}$ 06:00 for both epiphytic and planktonic algal communities. A clear diel periodicity in the urea decomposing activity of the planktonic algae was observed. The activity of the epiphytic algae, on the other hand, showed no destinctive variation during a day. The present results indicate that epiphytic algae are one of the significant urea decomposers in a reed zone, and that the diel patterns are quite difference between both algal communities.

• Korean Journal of Ecology and Environment
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• v.34 no.2 s.94
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• pp.98-105
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• 2001

Two-monthold silver carps were cultured with seven algal species and zooplankton (Moina macrocopa) in the laboratory. The carps were reared in 10 L translucent cylindrical aquaria with algae and zooplankton for 8 days. The Moina effectively fed almost cultured algae: perfectly removed Cryptomonas (NIES-282) within 60 min. Both algal diets Cryptomonas and Fragilaria (NIES-391) significantly increased the Moina population ($r^2$>0.93, p<0.005), while Microcystis (MIES-90) and Oscillatoria (NIES-204) reduced the zooplankton ($r^2$=0.97, p<001). Fish removed about 50% of all algae for 52 hrs, even 60% of Microcystis still remained: all algae reduced ca. 5${\sim}$12% of initial weight. Furthermore, a continuous supply of algae with same density resulted in the death of fish, e.g. 11 days in cyanobacteria Microcystis. Therefore, the growth limitation of silver carp by algae indicates that zooplankton is of direct dietary contributor in planktivores feeding behavior.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.57 no.3
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• pp.262-277
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• 2024

The mid-eastern coast of Korea is located at the boundary between cold and warm currents, which causes changes in the distribution and composition of marine organisms in response to fluctuations in the marine environment. To understand the seasonal changes in the seaweed community, we investigated its species composition, biomass, coverage, and frequency from November 2022 to August 2023. A total of 45 species (7 green, 18 brown, and 20 red algae) were found in the study area. In the intertidal zone, the number of species decreased from autumn to summer; the biomass peaked during winter (471.94 g wet weight m^-2). Seaweed groups were the dominant functional groups, which were coarsely branched, filamentous, and sheet-like during autumn, winter, spring, and summer. The morpho-functional group was dominated by turf species. In the subtidal zone, the number of species increased during autumn to spring, whereas the biomass peaked during spring (655.27 g wet weight m^-2). The functional group was dominated by coarsely branched species throughout all four seasons, whereas the morpho-functional group was dominated by canopy species. Consequently, changes in the biomass of brown and red algae are recognized as key drivers of seasonal changes in seaweed communities.

• Journal of Marine Bioscience and Biotechnology
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• v.8 no.1
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• pp.30-38
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• 2016

The objective of this study was to investigate the useful components and potential antioxidant activities of 30 marine algae, collected from Jeju Island in Korea. The contents of bioacitve substance of extracts from marine algae, such total polyphenol and carbohydrate, were determined. The extract of Distromium decumbens had the highest amount of total polyphenol content (21.27%), and that of Gracilaria incurvata Okamura had the highest amount of total carbohydrate content (10.18%). The antioxidant activities of extracts obtained from algae were tested through the evaluation of DPPH radical and hydroxyl radical scavenging activity. The extracts of Distromium decumbens, Sargassum hemiphyllum (Turner) C.Agardh, Sargassum serratifolium (C. Agardh) C. Agardh and Acrosorium yendoi Yamada were found to have more than 80% DPPH radical scavenging activity and that of Dictyota okamurae (Dawson) $H{\ddot{o}}tning$, Schnetter, et Prud'homme van Reine, Myagropsis myagroides (Martens ex Turner) Fensholt, Sargassum serratifolium (C. Agardh) C. Agardh and Cladophora wrightiana Harvey showed more than 50% hydroxyl radical scavenging activity. These results suggest that algae collected from Jeju Island would be good raw materials for antioxidant.

• Journal of Marine Bioscience and Biotechnology
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• v.14 no.2
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• pp.102-111
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• 2022

Beakryoung-do is located in the north along the western coast of South Korea. Owing to its geographical limitations, not many studies have been conducted on marine algae in this region. This study aims to investigate the marine algal flora and the community structure in the intertidal and subtidal zones of Nampo-ri, Beakryoung-myeon, Ongin-gun, Incheon regions of South Korea. The study was conducted from August 2015 to June 2016 during all seasons. A total of 95 algal species, including 7 green algae, 12 brown algae, and 76 red algae were collected and identified; 52 algal species were found in the intertidal zone and 83 in the subtidal zone. The vertical distribution of algae from upper to lower intertidal zone was Neorhodomela aculeata - Caulacanthus okamurae, Gelidiophycus freshwateri - Neorhodomela aculeata, Caulacanthus okamurae - Sargassum thunbergii, Caulacanthus okamurae. Findings indicated that Sargassum thunbergii and Neorhodomela aculeata were the biomass-dominant species in the intertidal zone and Corallina officinalis and Undaria pinnatifida were biomass-dominant in the subtidal zone. Average values of marine algae biomass in the intertidal and subtidal zones were 252.6 g wet weight m^-2 and 291.9 g wet weight m^-2, respectively. Further, 38 new species were found in Beakryoung-do, with 25 of them specifically found in the subtidal zone. More studies on marine algal flora in the subtidal zone are needed to understand the changes in marine flora along the western coast.

• ALGAE
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• v.25 no.1
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• pp.37-44
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• 2010

A tide-simulating apparatus was developed for culturing marine macroalgae. The objective of this study was to introduce a novel tide-simulating apparatus that can simulate a diurnal or semi-diurnal tidal cycle in the laboratory. In this apparatus, the seaweeds are move up and down and the water level remains the same during the simulated tidal cycle. The apparatus consists of 18 cylindrical culture tanks (3 blocks $\times$ 6 culture tanks) with 12 cm diameter and 24.5 cm long containing up to 2.5 L of seawater. There is a horizontal plate which covered all 18 culture tanks, and it is raised and lowered by a programmable motor that can regulate exposure time. In one application, seaweeds are attached to braided twine hung on Plexiglas air-tubing. The air-tubing is attached to a lid that is set on a horizontal plate. This apparatus is made of colorless Plexiglas to maximize light transmittance. This apparatus is easily disassembled and transportable to any indoor laboratory, wet laboratory, greenhouse, etc. This apparatus also offers considerable flexibility in terms of design. The size of culture tank can be redesigned by either increasing the height of cylinder or/and using a different diameter of cylindrical Plexiglas, therefore, larger/taller thalli can be cultivated. Growth rates of three eulittoral Porphyra species from different tidal elevations have been compared using this device.

• ALGAE
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• v.35 no.1
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• pp.1-15
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• 2020

Two strains isolated from a subtropical region in China, were morphologically identified as a Nostoc-like species, but its taxonomic identity was unknown. In this study, these two strains were taxonomically and phylogenetically characterized based on polyphasic approach combining morphological and genetic characteristics. Though both were virtually indistinguishable from Nostoc in field and cultured material, these two strains were phylogenetically distinct from Nostoc based on 16S rRNA phylogeny. The 16S-23S internal transcribed spacer rRNA secondary structure of these strains showed the unique pattern of D1-D1', Box-B, and V3 helix, which distinguished them from other Nostoc-like heterocytous genera. A unique cluster separated from Nostoc sensu stricto supports the establishment of Violetonostoc gen. nov. with the type species as Violetonostoc minutum sp. nov.

• The Korean Journal of Malacology
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• v.26 no.1
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• pp.19-31
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• 2010

Seogundo is a small island adjacent to the southern coast of Jeju Island and connected to it by a boulder beach at low tide Surveys of this area were conducted from 2001 to 2009 to enumerate the mollusks there and also to examine their diversity, relative abundance, and ecological relationships. Both the boulder beach itself and several large tide pools were studied, including the coarse sand substrate and several species of seaweed and coralline algae found in the tide pools. Of the 121 species obtained or observed, there were 97 gastropods, 16 bivalves, and 8 polyplacophorans. Live specimens were obtained for about half of those species. About one third were found on rocky substrate, with the most common species being Nodilittorina radiata and Nerita japonica in the upper intertidal zone, N. radiata and Littorina brevicula in the middle intertidal, and Turbo (Lunella) coronata coreensis and Acanthopleura japonica in the lower intertidal and shallow subtidal. The seaweeds and coralline algae contained about 40% of all mollusk species. The most common mollusks in two species of brown seaweed were Ittibittum parcum, Musculus nanus, and Euplica scripta. In a species of red seaweed, Komaitrochus pulcher was the most frequent, as in the coralline algae, along with M. nanus. The coarse sand in the tidepools contained about 25% of the species, with the Cerithiidae having the largest number. A sample of beach drift contained 17 species, with Bittium aleutaceum and Rissoina (Phosinella) pura being most common. Most species, about 60%, were found in a variety of habitats, especially the marine flora; few species exhibited any habitat preferences. Biographically, Jeju Island is part of the Warm Temperate Northwest Pacific Province and the East China Sea ecoregion with a strong faunal affinity with southern Japan, eastern China, and northeastern Taiwan. Zonal-geographical groupings reveal that the fauna is mainly subtropical-low boreal, preferring moderately warm water, with a somewhat smaller number of tropical-subtropical species.