• 한국수산과학회지
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• 제49권1호
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• pp.53-60
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• 2016

Seasonal variations in seaweed communities were examined at Gwanmaedo and Yeongsando, Korea, from May 2014 to February 2015. Eighty-nine species were identified, including 11 green, 20 brown and 58 red algae. Seventy-three and 74 species were identified at Gwanmaedo and at Yeongsando, respectively. Sargassum thunbergii and Myelophycus simplex were the dominant species, comprising 60.89 and 39.50% of total biomass, respectively, and S. fusiforme was subdominant at the two sites. Of six functional seaweed forms, the coarsely-branched form was the most dominant, forming about 43% of the species number at Gwanmaedo and Yeongsando. Seasonal seaweed biomasses ranged between 53.10 and 172.85 g/m² (average 93.57 g dry wt./m²) and between 83.11 and 176.20 g (138.21 g/m²) at Gwanmaedo and Yeongsando, respectively. The vertical distribution from the high to low intertidal zone was S. thunbergii and Gloiopeltis furcata; M. simplex and S. thunbergii; and S. fusiforme at Gwanmaedo. Seaweed zonation was distinct at Yeongsando, with S. thunbergii and Gelidiophycus freshwateri; M. simplex and S. thunbergii; and S. thunbergii and S. fusiforme. Seaweed biomass, evenness index (J'), and diversity index (H') values were greater at Yeongsando (138.21 g/m², 0.51, 2.18 respectively) than at Gwanmaedo (93.57 g/m², 0.48, 2.04), indicating that the seaweed community at Yeongsando is more stable than that at Gwanmaedo.

• 한국수산과학회지
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• 제44권6호
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• pp.740-746
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• 2011

Subtidal benthic macroalgal flora and community structure on barren grounds were examined seasonally along vertical shore gradients on the rocky shore of Hajung, Pohang, on the southeast coast of Korea, from February 2005 to November 2006. Twenty-six seaweed species were identified, including 5 green, 7 brown, and 14 red algae. The number of seaweed species ranged between 7 and 17 among seasons and between 13 and 20 species were found in vertical gradients along the shore. Over the study period, average seaweed biomass (g wet wt/$m^2$) was 299.88 g and it ranged seasonally from 120.99 to 620.00 g. Seaweed biomass declined with increasing seawater depth and ranged between 323.06 and 593.68 g. The dominant seaweed species, in terms of biomass, were Desmarestia ligulata and Sargassum honeri, which grew at depths between 5 and 10 m. The red alga Delisea pulchra was also abundant at a depth of 15 m. No seasonal patterns were found in community indices. Along vertical shore gradients, community indices showed different patterns; the dominance index increased and the richness, evenness, and diversity indices decreased with seawater depth.

• 환경생물
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• 제35권4호
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• pp.595-603
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• 2017

The macroalgal community structure was examined at the subtidal zones of six study sites, on the Southern coast of Korea from between May and August 2015. A total of 132 seaweeds, comprising 10 green, 28 brown and 94 red Seaweed, were identified. The seaweed biomass was $80.32g\;dry\;wt.\;m^{-2}$ in average, and it was maximal at Geomundo ($166.94g\;dry\;wt.\;m^{-2}$) and minimal at Byeongpungdo ($14.52g\;dry\;wt.\;m^{-2}$). On the basis of the biomass, the Ecklonia cava was a representative species, distributed widely in the subtidal zone of the three islands (Yeoseodo, Geomundo, Baekdo). Also, the Sargassum sp. was dominant at Sejondo and Hongdo. The turbidity and light transmittance was divided into two groups. The seaweed community structure of group A (Byeongpungdo, Sejondo, Geomundo) was characterized by high turbidity, low light transmittance and a lower habitat depth than were observed in group B (Hongdo, Baekdo, Yeoseodo). As the water depth increased, the biomass decreased due to the lowered light transmittance. In Byeongpungdo and Sejondo, which showed high turbidity and low light transmittance, the degree of seaweed coverage was decreased with the depth of water. The ESGII ratio of the Ecological Status Group was higher than fourty percentage in Byeongpungdo and Baekdo. Community indices were as follows: dominance index (DI) 0.35-0.90, richness index (R) 7.03-17.93, evenness index (J′) 0.22-0.60, and diversity index (H′) 0.79-2.18. The Macroalgal zonation of the subtidal zone was calculated by the Ecklonia cava and Brown algal population on five islands(Byeongpungdo, Yeoseodo, Geomundo, Beakdo, Hongdo). On the other hand, Undaria pinnatifida and Sargassum sp. dominated at Sejondo. Additionally, the biomass ratio and the species richness of green algae was lower in group A. These differences in the seaweed community structure may have resulted from the effects of turbidity and light transmittance.

• Journal of Ecology and Environment
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• 제45권4호
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• pp.203-217
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• 2021

Background: Sea turtles, which are globally endangered species, have been stranded and found as bycatch on the Korean shore recently. More studies on sea turtles in Korea are necessary to aid their conservation. To investigate the spatio-temporal occurrence patterns of sea turtles on the Korean shore, we recorded sampling locations and dates, identified species and sexes and measured sizes (maximum curved carapace length; CCL) of collected sea turtles from the year 2014 to 2020. For an analysis of diets through stomach contents, we identified the morphology of the remaining food and extracted DNA, followed by amplification, cloning, and sequencing. Results: A total of 62 stranded or bycaught sea turtle samples were collected from the Korean shores during the study period. There were 36 loggerhead turtles, which were the dominant species, followed by 19 green turtles, three hawksbill turtles, two olive ridley turtles, and two leatherback turtles. The highest numbers were collected in the year 2017 and during summer among the seasons. In terms of locations, most sea turtles were collected from the East Sea, especially from Pohang. Comparing the sizes of collected sea turtles according to species, the average CCL of loggerhead turtles was 79.8 cm, of green turtles was 73.5 cm, and of the relatively large leatherback turtle species was 126.2 cm. In most species, the proportion of females was higher than that of males and juveniles, and was more than 70% across all the species. Food remains were morphologically identified from 19 stomachs, mainly at class level. Seaweeds were abundant in stomachs of green turtles, and Bivalvia was the most detected food item in loggerhead turtles. Based on DNA analysis, food items from a total of 26 stomachs were identified to the species or genus level. The gulfweed, Sargassum thunbergii, and the kelp species, Saccharina japonica, were frequently detected from the stomachs of green turtles and the jellyfish, Cyanea nozakii, the swimming crab, Portunus trituberculatus, and kelps had high frequencies of occurrences in loggerhead turtles. Conclusions: Our findings support those of previous studies suggesting that sea turtles are steadily appearing in the Korean sea. In addition, we verified that fish and seaweed, which inhabit the Korean sea, are frequently detected in the stomach of sea turtles. Accordingly, there is a possibility that sea turtles use the Korean sea as feeding grounds and habitats. These results can serve as basic data for the conservation of globally endangered sea turtles.

• 한국수산과학회지
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• 제46권6호
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• pp.878-885
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• 2013

Seasonal variation in marine macroalgal community structure was examined at the intertidal zones of Heuksando and Hongdo, Shinan, Korea, from July 2008 to May 2009. In total, 86 macroalgal species were identified, including 12 green, 19 brown, and 55 red algae; 67 species at Heuksando and 70 species at Hongdo, were observed. Annual seaweed biomass was 252.44 g dry $wt/m^2$ at Heuksando and 217.67 g dry $wt/m^2$ at Hongdo. The dominant seaweed in importance value (IV > 15) differed between the sites: Sargassum thunbergii at Heuksando and Corallina pilulifera at Hongdo. The vertical distribution pattern of seaweeds from the upper to lower intertidal zones at Heuksando was Gloiopeltis spp., Ulva spp. - S. thunbergii, S. fusiforme, Hildenbrandia rubra - S. thunbergii, C. pilulifera. On the rocky shore of Hongdo, seaweed zonation was distinct: Porphyra yezoensis, Gloiopeltis spp., Ulva spp. - C. pilulifera, S. fusiforme, Myelophycus simplex - Chondrus ocellatus, C. pilulifera, and Carpopeltis affinis. Annual seaweed coverage, richness index (R), evenness index (J'), and diversity index (H') values were greater at Hongdo (41.35%, 12.82, 0.59, and 2.50 respectively) than at Heuksando (31.54%, 11.93, 0.44, and 1.87 respectively), which may indicate that the seaweed community at Hongdo is more stable relative to the one at Heuksando.

• ALGAE
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• 제35권2호
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• pp.107-121
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• 2020

Mariculture is regarded as the only option to supply the increasing demands for seaweeds as human food, feeds, fodder, and phycolloids in a sustainable manner. Technologies for culturing a range of seaweed species have been developed successively in Korea since the 1970s. In 2017, Korean marine farms produced 1,761,526 t of seaweed. The key focus of the industry is on the production of Pyropia (523,648 t), Undaria (622,613 t), and Saccharina (542,285 t). Pyropia is economically the most important species in Korea, accounting for up to 68% of total production value. As the top exporter of Pyropia in the world, Korea exported up to US $525 million of Pyropia products to 110 countries in 2018. Other economically important genera include Sargassum, Ulva, Capsosiphon, Codium, and Gracilariopsis, all of which are used for food, and Gelidium, Pachymeniopsis, and Ecklonia which are used as raw material for phycocolloid extraction. Significant work has gone into developing more productive strains of key seaweed species, and in 2012 the Korean government began to certify seaweed varieties. To date, 19 seaweed cultivars have been registered including 13 Pyropia, 5 Undaria, and 1 Saccharina. The industry is now seeking not only to increase productivity but also to add value through processing. Convenience foods and snacks have been developed that target health-conscious consumers and utilize the nutritional properties of seaweeds. The industry is also seeking to promote the sustainability of seaweed farming. One seaweed company in Korea obtained the world's first ASC-MSC (Aquaculture Stewardship Council-Marine Stewardship Council) certification in 2019 and more are expected to follow their lead. With continued research support, the Korean seaweed industry plans to continue to expand to meet new market demands at a sustainable pace.

• 한국수산과학회지
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• 제45권3호
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• pp.262-270
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• 2012

Seaweeds provide habitats in which marine animals can spawn and develop, and serve as a food supply for algaegrazing species such as sea urchins and abalone. Recently, seaweed species have disappeared from coastal ecosystems, leaving barren ground, defined as habitats that have lost their algae forests and where coralline algae containing calcium carbonate components have become encrusted on rocks. The biological causes of barren ground include grazing by herbivores and excessive seaweed harvest. The environmental harm caused by the spread of barren ground includes accelerated eutrophication following the reduction in seaweed, which plays an important role in oceanic purification. In the present study, we identified the relationships between various seaweed species and the occurrence of barren ground. Subtidal benthic macroalgal flora and community structure were observed seasonally on barren ground along vertical transects of rocky shores of Bihwa, Samchuck, and the east coast of Korea from February to November 2006. Fifty-eight seaweed species were identified, including 7 green, 15 brown, and 36 red algae species. There were between 6 and 28 species among seasons. Over the whole study period, average seaweed biomass (g wet wt $m^{-2}$) was 241.90 g, with a seasonal range of 25.26 to 760.34 g. Seaweed biomass declined with increasing seawater depth and ranged between 91.26 and 422.08 g. The vertical distribution of algae was characterized by Undaria pinnatifida and Sargassum honeri at 5 m, S. honeri and U. pinnatifida at 10 m, and U. pinnatifida and Agarum clathratum at 15 m depth. Seasonal patterns in community indices were not found. Community indices showed different patterns along vertical shoreline gradients; the dominance index increased but the richness, evenness, and diversity indices decreased with seawater depth. Sea urchin density was 8 to 24 individ. $m^{-2}$ in Bihwa. These urchin populations had significantly aggregated spatial patterns and recurrent destructive grazing appeared to be occurring.

• ALGAE
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• 제30권2호
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• pp.171-179
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• 2015

Organic light-emitting materials in marine macrophytes from various coastal environments were identified. Twentyeight species from the solvent fractions were examined and identified as candidates for bioorganic light-emitting materials using photoluminescence (PL) spectra and gas chromatography-mass spectrometry. We selected 16 solvent fractions from a total of 1,221 prepared from Ishige okamurae, Sargassum confusum, Grateloupia elliptica, Chondracanthus intermedius, Porphyra yezoensis, Meristotheca papulosa, Gelidium amansii, and Scytosiphon lomentaria. The maximum light-emitting PL spectra appeared at various colors, mainly between blue and green, based on chromaticity coordinates, from solvent fractions of M. papulosa, G. amansii, G. elliptica, P. yezoensis, S. lomentaria, I. okamurae, and C. intermedius. These results will contribute to the development of novel organic light-emitting materials.

• ALGAE
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• 제20권3호
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• pp.251-260
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• 2005

Antioxidative activities of Chlorophyta and Phaeophyta in Jeju Island were measured by superoxide anion ($O_2^{{\cdot}-}$), hydroxyl radical ($HO^{\cdot}$), hydrogen peroxide ($H_2O_2$) and DPPH free radical scavenging assays. Methanolic and aqueous extracts of the seaweeds were prepared at both temperatures, higher (70$^{\circ}C$) and room temperature (20$^{\circ}C$), and screened for the construction of an extract bank from seaweeds in Jeju Island. A variety of extracts showed positive effect against reactive oxygen species (ROS). Especially, Sargassum thunbergii methanolic extract at 70$^{\circ}C$ (70ME, 97.41%), S. fulvellum methanolic extract at 20$^{\circ}C$ (20ME, 84.66%), Codium fragile aqueous extract at 70$^{\circ}C$ (70AE, 96.61%) and S. thunbergii 20ME (97.44%) exhibited the highest scavenging activities against $O_2^{{\cdot}-}$, $HO^{\cdot}$, $H_2O_2$ and DPPH free radicals, respectively. Total phenolic contents also examined but did not show a positive correlation with ROS scavenging abilities (except for a few extracts). These results indicate that further investigation is needed to identify and purify the responsible antioxidative components.

• 한국수산과학회지
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• 제41권1호
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• pp.68-72
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• 2008

The cellular viability of the human keratinocyte cell line HaCaT was compared after adding seaweed extracts to the culture medium. The viability was measured using a quick, quantitative, spectrophotometric crystal violet inclusion method. Of 36 common seaweed species tested, methanol extracts from Sargassum sagamianum and Gigartina tenella enhanced the viability of HaCaT cells by 1.6-fold, as compared to control cells, while methanol extracts from Dictyota dichotoma, Pachymeniopsis elliptica, and Enteromorpha linza decreased the viability to less than half that of controls.