• Journal of Life Science
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• v.16 no.6
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• pp.1044-1051
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• 2006

The barren ground is an abnormal phenomenon of coastal ecosystem in which seaweeds, are destroyed and mostly replaced by the coralline algae containing the calcium carbonate components. To restore the seaweed forest, We have exerted an effort in the local areas, Samchuck, Korea, where barren phenomena are profound. Two methods of seaweed forest construction developed in the present study are underwater longline and seed transplantation for the brown seaweed Costaria costata, a fast growing edible seaweed. The sizes of C. costata attached on the underwater longline were $96.7{\pm}2.2mm$ of blade length and $83.6{\pm}7.7g$ of blade weight in April. Thereafter the sizes declined from May. Similar pattern was obtained from in the transplantation method with maxima of $90.4{\pm}15.8mm$ and $70.1{\pm}31.7g$ for blade length and weight, respectively in April. It appeared totality maturation from two methods in May. This maturation time is the same like that of wild C. costata.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.5
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• pp.323-331
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• 2007

Barren ground is an abnormal phenomenon in coastal ecosystems where seaweeds are destroyed and largely replaced by coralline algae containing calcium carbonate components. To restore the seaweed forest, we attempted reconstruction in an area of Samcheok, Korea, where barrenness is extensive. We developed two methods of seaforest construction underwater longline and seed transplantation for the brown seaweed Laminaria japonica, a fast-growing edible seaweed. The blade length of L. japonica attached to an underwater long line was $93.9{\pm}38.2cm$ and blade weight $7.6{\pm}2.1g$ in February 2004. Seaweed size declined after August 2004. A Similar pattern was observed using the transplantation method with maxima of $179.3{\pm}40.3cm\;and\;14.9{\pm}3.2g$ for blade length and weight, respectively in July 2004. The transplanted seaweeds matured in October as did a wild population. These results indicate that transplanted seaweed acclimate to new environments.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.5
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• pp.607-618
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• 2013

Marine macroalgal community structures and characteristics of ocean environmental factors were examined seasonally at four sites in Jeju Island, Korea, from March to November 2012. A total of 71 macroalgal species were identified, including 9 green, 7 brown, and 55 red algae. Peyssonnelia capensis occurred at all study sites and in all seasons. The average annual biomass of seaweed was 991.84 g wet $wt/m^2$, with seasonal variations from 543.80 g in autumn to 1,284.17 $g/m^2$ in summer. A green alga, Codium coactum, was the dominant species, occupying 21.31% (211.39 $g/m^2$) of the total algal biomass in Jeju Island. Subdominant species were Ecklonia cava and Lithophyllum okamurae, comprising 20.85% (206.75 $g/m^2$) and 19.64% (194.75 $g/m^2$), respectively, of the total algal biomass in Jeju Island. The vertical distribution of subtidal seaweeds was represented by L. okamurae at 5 m depth, C. coactum at 10 m depth, E. cava at 5-10 m depth and P. capensis at the 20 m depth level. In the present study, crustose coralline algae, which predominated on barren ground, were subdominant species at all study sites. Community indices varied between 0.51-0.63 for dominance index (DI), 5.53-8.14 for richness index (R), 0.51-0.63 for evenness index (J'), and 2.04-2.32 for diversity index (H'). On the basis of seaweed biomass and community indices, Sinchang was the best preserved coastal area, showing maximal values in biomass, and evenness- and diversity-indices, and minimal value in the dominance index, representing stable environmental conditions. In contrast, the Onpyung and Topyeong sites, located near tourist venues such as Udo and Seogwipo were relatively poor habitats based on community indices and biomass. The present results could imply that climate changes alter seaweed community structure, and long-term monitoring of the study sites is required.

• Korean Journal of Environment and Ecology
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• v.31 no.6
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• pp.529-536
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• 2017

The study is intended to investigate the proliferation of whitening, the impact of climate change (sea temperature rise) on the proliferation of whitening, and the reproduction and growth of crustose coralline algae, which causes the whitening, in the coast of Jeju Island. The size of the whitening-affected area in the coast of Jeju was 2,931ha in 1998 and increased to 4,541ha in 2003. The whitening occurred mainly in the southern coast of Jeju in 1998 but spread across the whole coast of Jeju by 2003, except in the coast of Jocheon-eup (eup refers to an administrative district in Korea) and Gujwa-eup. The average sea water temperature in February from 1992 to 2004 was $15.1^{\circ}C$ in the whitening affected area and $13.9^{\circ}C$ in the marine forest area, showing a clear difference, but there was no difference in the average temperature in August. The long-term (37-year period) average of the sea temperature was $15.3^{\circ}C$ in the whitening affected area and $14.1^{\circ}C$ in the marine forest area, showing $1.2^{\circ}C$ higher in the whitening area. The annual rate of sea temperature rise was $0.038^{\circ}C$ in the whitening area and $0.024^{\circ}C$ in the marine forest area, indicating the higher long-term variation of sea temperature in the water affected by whitening. The results indicate that the continuous increase in winter water temperature due to climate change is expanding proliferation of whitening in the Jeju island.