• ALGAE
• /
• v.30 no.1
• /
• pp.59-66
• /
• 2015

The growth and hole formation of Ulva australis were examined at seven coastal areas of Korea between July and August, 2013. Animal species and weight growing on the Ulva fronds were estimated at Haseom, Pohang, and Woedo. The effects of wave exposure on the morphological features and residential animals of Ulva fronds were investigated at wave-exposed and sheltered sites of Seongsan on October 19, 2013. U. australis had different frond areas ($82-665cm^2$), hole areas ($2.5-6.3cm^2$), and hole numbers (9.8-41.3 holes) at the seven sites. Within $0.1m^2$ of Ulva frond, hole areas ranged from 0.37 to $5.94cm^2$, and between 4.9 and 36.2 holes were observed. Fourteen residential animal species were observed at the three evaluated sites, 75.0 (Haseom) to 408.7 individuals $100g^{-1}$ Ulva (Pohang) per site. The dominant residential species at each site differed with Amphithoe sp. at Haseom, Monodonta spp. at Pohang, and Pagurus sp. at Woedo. The growth (frond area, wet weight) and hole number of Ulva fronds, and the number of residential animals were significantly greater in samples collected from the sheltered shore than the wave-exposed shore of Seongsan. The present results showed U. australis grew well at sheltered shores and had more holes on the fronds due to abundance of residential animals. The dominant residential animals (crabs, gammaridea, and snails) were similar in the Ulva populations of sheltered and wave-exposed shores, but greater species diversity was observed at the exposed shore (18 species ver. 11 species). In conclusion, U. australis is a keystone species providing habitat to various invertebrates and frond holes are positively correlated to the number of residential animals.

• ALGAE
• /
• v.34 no.4
• /
• pp.253-266
• /
• 2019

Several species classified to the genus Ulva are primarily responsible for causing green tides all over the world. For almost two decades, green tides have been resulted in numerous ecological problems along the eastern coast of Jeju Island, Korea. In order to characterize the species of Ulva responsible for causing the massive blooms on Jeju Island, we conducted DNA barcoding of tufA and rbcL sequences on 183 specimens of Ulva from eight sites on Jeju Island. The concatenated analysis identified five bloom-forming species: U. australis, U. lactuca, U. laetevirens, U. ohnoi and a novel species, U. pseudo-ohnoi sp. nov. Among them, U. australis, U. lactuca, and U. laetevirens caused to the blooms coming mainly from the substratum. U. ohnoi and U. pseudo-ohnoi sp. nov. were causative the free-floating blooms. Four species, except U. australis, are characterized by marginal teeth. A novel species, U. pseudo-ohnoi sp. nov., is clearly diverged from the U. lactuca, U. laetevirens, and U. ohnoi clade in the concatenated maximum likelihood analysis. Accurate species delimitation will contribute to a management of massive Ulva blooms based on this more comprehensive knowledge.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.54 no.1
• /
• pp.101-106
• /
• 2021

The marine algal flora and community structure of Dadohaehaesang National Park, the Southwestern coast of Korea, were investigated monthly during May, July and September 2012. As the results, a total of 86 species including 10 greens, 17 browns and 59 reds was identified, except for blue-greens and crustose reds. The seaweeds that commonly appear during the investigation period are the green algae Ulva australis, the brown algae Ishige okamurae, Myelophycus simplex, Sargassum fusiforme and S. thunbergii and the red algae Gelidiophycus freshwateri, Gelidium. elegans, Corallina officinalis, C. pilulifera, Caulacanthus ustulatus, Ahnfeltiopsis flabelliformis, and Chondrus ocellatus. In Jodo district (Yemiri, Changuri), Ulva australis and Gloiopeltis furcata were dominant species in May, Sargassum fusiforme and Ulva australis were dominant in July, and Gelidiophycus freshwateri and Ulva australis were dominant in September. In Soan/Cheongsan district (Hwaheungpo, Jungdori), Gloiopeltis tenax and Chondracanthus tenellus were dominant species in May, and Gloiopeltis tenax and Chondracanthus tenellus were dominant in July as well as in the spring. And the Caulacanthus ustulatus and Corallina sp. were dominant species in September.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.48 no.1
• /
• pp.96-103
• /
• 2015

The effects of $CO_2$ concentration, nutrient levels, and irradiance on the growth of germlings and juveniles, and on the photosynthesis of adults were examined in a green tide alga, Ulva australis. We used a factorial experimental design with two $CO_2$ concentrations (380 and 750 ppm), two nutrient levels (control and PES medium), and two irradiance levels (50 and $100{\mu}mol$ photons $m^{-2}s^{-1}$). Germlings grew best ($664.15{\pm}61.45{\mu}m$ in length) under conditions of 750 ppm, PES, and $100{\mu}mol$ photons $m^{-2}s^{-1}$ after 10 days in culture. Relative growth rates (RGR) of the juveniles were greatest (4.41% $day^{-1}$) under conditions of 750 ppm, PES, and $50{\mu}mol$ photons $m^{-2}s^{-1}$ after 5 days in culture. Photosynthetic efficiency ($F_v/F_m$) of the adult discs was $0.73{\pm}0.05$ before the experiment and reached a maximum ($0.83{\pm}0.01$) under conditions of 750 ppm, control, and $50{\mu}mol$ photons $m^{-2}s^{-1}$ after 5 days in culture. Growth (germlings and juveniles) and photosynthesis (adult discs) of Ulva australis increased when $CO_2$ levels were 750 ppm. Additionally, the optimal irradiance for growth and photosynthesis differed among stages, wherein germlings grew best at $100{\mu}mol$ photons $m^{-2}s^{-1}$, juveniles grew best at $50{\mu}mol$ photons $m^{-2}s^{-1}$, and adults photosynthesized most at $50{\mu}mol$ photons $m^{-2}s^{-1}$. The performance of Ulva australis at all examined life stages was enhanced under the PES nutrient treatment. In conclusion, the physiological responses of U. australis to varying $CO_2$, nutrient, and irradiance levels differed slightly among life stages. However, growth and photosynthesis always increased with elevated $CO_2$ and nutrient concentrations. These results indicate that U. australis green tide blooms might occur more frequently in coastal areas if $CO_2$ and nutrient concentrations increase.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.28 no.1
• /
• pp.1-8
• /
• 2022

With the spread of COVID-19 worldwide, non-face-to-face services have grown rapidly, but at the same time, the problem of plastic waste is getting worse. Accordingly, eco-friendly policies such as carbon neutrality and sustainable circular economy are being promoted worldwide. Due to the high demand for eco-friendly products, the packaging industry is trying to develop eco-friendly packaging materials using PLA and PBAT and create new business models. On the other hand, Ulva australis occurs in large quantities in the southern seas of Korea and off the coast of Jeju Island, causing marine environmental problems. In this study, lactic acid was produced through dilute acid pretreatment, enzymatic saccharification, and fermentation processes to utilize Ulva australis as a new alternative energy raw material. In general, seaweeds vary in carbohydrate content and sugar composition depending on the species, harvest location, and time. Seaweed is mainly composed of polysaccharides such as cellulose, alginate, mannan, and xylan, but does not contain lignin. It is difficult to expect high extraction yield of the complex polysaccharide constituting Ulva australis with only one process. However, the fusion process of dilute acid and enzymatic saccharification presented in this study can extract most of the sugars contained in Ulva australis. Therefore, the fusion process is considered to be able to expect high lactic acid production yield when a commercial-scale production process is established.

• Weed & Turfgrass Science
• /
• v.7 no.1
• /
• pp.35-45
• /
• 2018

The seaweed Ulva spp., which is frequently bloomed in coastal areas, have negatively affected on marine ecosystem and industrial activities. Therefore, many researches have been conducted to solve this problem in the worldwide. In this study, we carried out several experiments to develop the methods for effectively controlling Ulva growth through an alone or mixture application of chemical and temperature. Three chemical mixtures ($H_2O_2$+N-vanillylnonanamide; $H_2O_2$+nonanoic acid; $H_2O_2$+sodium citrate), those had a synergistic effect to the death of Ulva australis (ULAUS), were found out. On the other hand, the death of ULAUS was significantly enhanced and accelerated as some chemicals were briefly treated with warm water of $40^{\circ}C$ rather than $25^{\circ}C$, showing that peracetic acid 100 ppm, sodium percarbonate 100 ppm, and hydrogen peroxide 30 ppm has a better activity than that of sodium chlorite 200 ppm and menadione sodium bisulfite 4 ppm. In addition, a strong synergistic effect to the death of ULAUS thallus was also observed when the sodium citrate 1,000 ppm (pH 3.0) or acetic acid 200 ppm (pH 3.5) solution prepared in f/2 medium were treated in a short time at $40^{\circ}C$. However, an additive effect was only appeared as pH values of their solutions were increased to 8.0. Taken together, It seemed that our results could be developed as one of an eco-friendly practical measures useful for alleviating Ulva bloom in the future.

• Weed & Turfgrass Science
• /
• v.6 no.3
• /
• pp.222-234
• /
• 2017

Green tides, which was mainly caused by Ulva spp., have been increasing in severity and frequency globally, and have negatively affected on marine ecosystems. This study was conducted to investigate effects of various physical and chemical factors on the death of Ulva australis (ULAUS) and to consider a practical measures useful for alleviating Ulva bloom. Soaking of ULAUS thalli in pure water for 8 hr didn't induce a death, but incubation in 1.0-1.5% salinity for 7 d inhibited sporulation by about 70%. Desiccation gave rise to a serious damage when more than 40-50% of initial fresh weight was lost. ULAUS growth was sensitive to temperature and seriously inhibited from more than $30^{\circ}C$. At $35^{\circ}C$, $40^{\circ}C$, $45^{\circ}C$ and $50^{\circ}C$, treatment time required for 90-95% death of ULAUS thalli was 1 d, 10 min, 30 sec, and 1 sec, repectively. ULAUS growth was seriously inhibited at lower than pH 6.0 and completely dead at pH 4.0. Several compounds for ULAUS control was selected and the chemcals causing a rapid death were oxidants such as hydrogen peroxide and sodium percarbonate. Taken together, our results suggest that low salinities, dryness, pH, high temp. and compounds could be selected for Ulva bloom control, and high temperature and compounds seems to be useful for a development of practical control methods.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.25 no.2
• /
• pp.244-250
• /
• 2019

We investigated the relationship between morphological characteristics and individual dry weight to develop a method for estimating the individual dry weight of sheet form macroalgae: Ulva australis, Ulva linza, Pachymeniopsis lanceolata, and Pyropia yezoensis. In Total, 319 thalli of various sizes were collected at six sites from February 2017 to December 2018. An interspecific allometric exponent of 0.28 was found for length-biomass allometry in four sheet form macroalgae, corresponding to a 1/4-power law for primary producers. The relationships between surface area and individual dry weight, as well as between individual fresh weight and individual dry weight, were found to fit significantly using linear regression equations. This explained 94-99 % of individual dry weight, indicating that surface area and individual fresh weight can be used to accurately estimate individual dry weight. We propose the use of this method when experimental processes do not allow individual dry weight to be measured directly, so researchers can save both time and expense.

• Korean Journal of Environmental Biology
• /
• v.39 no.1
• /
• pp.81-87
• /
• 2021

The monthly variability in marine algal flora and community structure was examined in the intertidal zones of Doripo, and the biomass of an edible alga, Ulva prolifera, at Gaip-ri of Hampyong Bay on the southwestern coast of Korea was investigated over one year from April 2008 to March 2009. A total of 22 seaweeds were identified including five green, four brown, and 13 red algae. Based on importance value, Ulva australis was dominant over the year and the subdominant species were Ulva linza and Caulacanthus ustulatus at the Doripo coast of Hampyong Bay. The vertical distribution in terms of importance values was in the order of Ulva linza - C. ustulatus - U. australis - Sargassum thunbergii from the upper to the lower intertidal zones. The biomass of U. prolifera ranged between 2.4-98.2 g dry wt. m^-2, with a maximum in June and a minimal in November. In the field, U. prolifera biomass could be positively related to seawater temperature. However, further research on the association between biomass and other environmental factors such as nutrients and light intensity is required.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.48 no.1
• /
• pp.82-87
• /
• 2015

For the ecological evaluation of marine algal vegetation, flora and their communities were surveyed seasonally at Goseong, on the southern coast of Korea. A total of 102 algal species, comprising 17 green, 18 brown and 67 red algae, was identified. Representative dominant species were assessed as Ulva australis, Sargassum thunbergii, and Gelidium amansii. Of these, Ulva australis was remarkably dominant in all seasons. High biomass of the dominant species were recorded. The total seasonal biomass was highest in winter and lowest in summer. The mean biomass value was $1315.6g/m^2$ across the four seasons. Each species was classified into six functional groups, and two ecological state groups (ESG) were evaluated based on these groups. While ESG I, the late successional species group, formed only 18.6% of the algal community; ESG II, composed of opportunistic species, comprised 81.4%. This suggests that environmental stress has been continuously imposed on the marine algal vegetation of the present study area.