• Ocean and Polar Research
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• v.34 no.1
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• pp.65-71
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• 2012

Gambierdiscus toxicus, Adachi et. Fukuyo, is a benthic ciguatoxin-producing armored dinoflagellate, often attached to macroalgae. This organism is the primary causative agent of ciguatera fish poisoning which occurs in tropical and subtropical regions. However, regardless of the fact that the population of Gambierdiscus spp. has expanded to such temperate areas from sub-trophic and trophic areas, monitoring of G. toxicus has been lacking in the Korean coastal waters of temperate areas. This study was performed at the uninhabited Baekdo Islands off the southern coast of Korea and at Seopsom Island in the vicinity of Seogwipo, Jeju Province during April and May, 2011. Cell densities of Gambierdiscus spp. on macroalgae at Baekdo and Jeju Island ranged from zero to 56.4 cells $g^{-1}$. Maximum density was recorded on the brown alga Cladophora japonica at St. 3 of Jeju Island. In particular, the cell densities of Gambierdiscus spp. were influenced by the substrate characteristics of macroalgae. In the future, the continuous monitoring of toxic benthic dinoflagellate is necessary to predict and prevent ciguatera poisoning in Korean coastal waters.

• 한국약용작물학회:학술대회논문집
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• 2011.09a
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• pp.406-407
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• 2011

• Korean Journal of Environmental Biology
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• v.35 no.4
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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.

• Animal Systematics, Evolution and Diversity
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• v.36 no.4
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• pp.330-335
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• 2020

The sea spider genus Cilunculus Loman, 1908 comprises 33 species having short chelifores, separate lateral processes, and a hood structure on the cephalic segment. A pycnogonid species, Cilunculus armatus(Böhm, 1879), was collected from Baekdo Island and Chujado Island, Korea. This species is characterized by having a hood structure on the cephalic segment, separate lateral processes, a low ocular tubercle without eyes, and 3-segmented chelifores. In the examined material, chela shape, arrangement of compound spines on strigilis, and number of heel spines at propodus were different from the previous literatures. Here, we examined C. armatus collected in Korean waters and provided illustrations and pictures in detail.

• Animal Systematics, Evolution and Diversity
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• v.34 no.3
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• pp.143-151
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• 2018

A marine ciliate Amphisiella milnei (Kahl, 1932) $Horv{\acute{a}}th$, 1950 was discovered from the tidal pool of Baekdo Island, South Korea. The existence of extra cirri between leftmost frontal cirrus and buccal cirrus discriminates this species from its congeners. Its morphological features are described as follows: body size in vivo $110-130{\times}35-45{\mu}m$; elongate rectangular to elliptical in shape; two large and several small ring-shaped structures; yellowish cortical granules arranged irregularly on ventral side but longitudinally along dorsal kineties on dorsal side; 34-40 adoral membranelles, 3 frontal cirri, 1 buccal cirrus, 1 parabuccal cirrus, usually 2 extra cirri behind leftmost frontal cirrus, and 3 frontoventral cirri; amphisiellid median cirral row composed of 25-31 cirri with 27-36 left and 27-44 right marginal cirri; usually 5 transverse cirri and 2 pretransverse cirri with 7 dorsal kineties; two macronuclear nodules. In addition to, 18S rDNA sequence of A. milnei was analyzed to understand its phylogenetic relationship.

• Animal Systematics, Evolution and Diversity
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• v.20 no.2
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• pp.201-214
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• 2004

Some actiniarians were collected from the coasts of Jejudo and Baekdo Islands in Korean waters from 1971 to 2004. They are identified into three species within three families, which are newly recorded to Korean actiniarian fauna: Halcampella maxima Hertwig, 1888 within the tribe Athenaria, and also Aulactinia coccinea (Verrill, 1866) and Stichodactyla tapetum (Ehrenberg, 1834) within the tribe Thenaria. They are described in detail with figures and tables together with the distribution and size of cnidae. In preserved specimens, mature oocytes of H. maxima were observed in winter. Also oocytes and sperm sacs of S. tapetum were surveyed at separate individuals in summer. The unique feature of A. coccinea is a body wall with simple adhesive verrucae extended from margin to limbus in longitudinal rows. In the genus Stichodactyla, the smallest species, S. tapetum is distinguished from S. haddoni by short bulbous tentacles, less than 1.0 mm long, densely packed on the oral disc and also conical marginal ones, 1.5-2.0 mm long. As a result of this study, the Korean actiniarian fauna consists of four athenarian and 23 thenarian species in suborder Nynantheae

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.2
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• pp.174-180
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• 2016

This study suggests a navigation route for maritime tourism cruise sail yacht that sails off from Yeosu, and passes by Baekdo and Geomundo with their live island culture, to Kimnyeonghang of the Jeju islands. Recently, there are increasing number of accidents in proportion to vitalizing marine leisure. That's why it should be examined by region and sea when developing safe sea route considering characteristics of the sailing yacht. Thus, it is needed to introduce marine culture, hold international sailing yacht race and develop multi-functional sea port according to the case of Geomundo. Also additional analysis for navigation ruote patterns and density of the fairway is required. This information will improve safe sailing level of sailing yacht that will help the local tourism industry.

• Korean Journal of Environmental Agriculture
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• v.25 no.3
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• pp.276-283
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• 2006

To evaluate the effectiveness of the foliar spray of calcium on "Baekdo" peach fruit, we carried out experiments in the orchards. The sprays were applied with $CaCl_2\;(Ca:\;400mg.kg^{-1})\;and\;CaCl_2$ with adjuvants (amino acid, $2g.kg^{-1}$; phytic acid, $2ml.kg^{-1}$ and wood vinegar, $2ml.kg^{-1}$) for four times from June 12 through July 4 at weekly intervals. The fruits and leaves were evaluated for Ca content, firmness and incidence of Brown rot caused by Monilinia fructicola at harvest To evaluate fruit quality included Ca content, firmness natural decay during the storage, the fruits were stored at room temperature for 14 days. The Ca content in leaf and fruit flesh at harvest was significantly increased (P=0.05) in $CaCl_2$ + amino acid treatment among $CaCl_2$ treatments. However, there was not significant Ca content in fruit peel. The firmness of flesh increased significantly (P=0.05) in $CaCl_2$ + amino acid treatment. The natural decay (Rhizopus stolonifers) during storage at the room temperature for 14 days, the fruit treated with $CaCl_2$ + wood vinegar exhibited lowest (P=0.05) incidence. Also, the firmness of the fruit during storage was firmer with treated $CaCl_2$ than untreated fruit. In the treatments of $CaCl_2$ + phytic acid and $CaCl_2$ + amino acid, it was possible to reduce incidence of Brown rot caused by M. fructicola most effectively in the field. In addition, inoculation with M. fructicola in fruits was also the most effective treatment for inhibiting disease development in vitro. These results suggested that the foliar spray of $CaCl_2$ with adjuvants increased the content of Ca and firmness of the fruits positively. It also inhibited the natural decay and the Brown rot effectively.

• Korean Journal of Environment and Ecology
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• v.36 no.4
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• pp.433-441
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• 2022

Light pollution is one of the factors that disturb coastal and island ecosystems. This study examined the factors causing light pollution in the islands in Daedohaehaesang National Park using nighttime satellite images. This study selected 101 islands with an area of 100,000 m² or more in Daedohaehaesang National Park, and measured the levels of light pollution of the selected islands by calculating mean nighttime radiance recorded in VIIRS DNB monthly images for January, April, August, and October 2019. Of seven districts of the park, The highest mean nighttime radiance was recorded in Geumodo district (17,666nW/m²/sr), followed by Geonumdo·Baekdo, Narodo, Soando·Cheongsando districts. By season, mean nighttime radiance in October was the highest at 9,509nW/m²/sr, followed by August, January, and April. Regression analyses show that the total floor area and the number of lighthouses in a 5 km buffer area had a statistically significant effect on mean nighttime radiance at all times, but those within the island did not, indicating that light pollution in islands in a national park where land development is strictly restricted is influenced by artificial lights in nearby areas. However, the total floor area of an island significantly affected mean nighttime radiance only in August, which appears to be attributed to the impact of intensive use of artificial light by visitors during summer vacation. The size of an island had a negative (-) effect on nighttime radiance. This negative effect suggests that light pollution is a type of ecological edge effect, i.e., the smaller island is more likely to have a relatively larger proportion of edge area that is affected by light emitted from the neighboring areas. The results of this study indicate that managing artificial lights in nearby areas is necessary to mitigate light pollution in islands in marine and coastal national parks.