A recent report has showed that potentially toxic benthic dinoflagellates obtained from macroalgae were observed in Jeju waters. These species have been reported to occur only in subtropical waters and are regarded as a producer of ciguatoxin in fishes. This finding of benthic dinoflagellates contributes to improve the monitoring surveillance for the safety of humans and marine food in Korea, which will extend to southern coastal regions. Furthermore, Cochlodinium red tide, which occurs annually each summer, will increase the distribution toward whole coastal waters in Korea because of the more northerly direction of isotherms in SST (Sea Surface Temperature) due to global warming. Consequently, the Korean government should enforce a monitoring programme against biotoxin assessment investing research abilities (i.e. manpower and funds) to better understand Korean marine ecosystem in responding to climate change.
The importance of interaction between surface water and groundwater has been increased for the understanding and analyzing hydrological cycle in natural stream system. In this study, the interaction between surface water and groundwater is qualitatively analyzed by using a field measurement of water level and temperature in Guamcheon stream, South Korea. The results show that temperature measurement is necessary to assess the interaction between surface water and ground water not only water level. The interactions between surface water and groundwater in short stream can be analyzed by using this method and the accuracy of stream-groundwater interactions can be enhanced in the concept of hydrological analysis by adding the temperature variation data. Consequently, this method based on field measurement can be expected as a basic procedure for qualitative study on stream-groundwater interactions.
Clay dispersion has been applied in Korean coasts since 1996 to minimize fisheries impact by Cochlodinium polykrikoides blooms. Understanding of spreading and sedimentation pattern of yellow clay in the sea after dispersion would be helpful for the counter measure of possible impact on marine environment and ecosystem by the clay. Tidal current movement and sedimentation of clay targeted on Obido island, Tongyong, Korea where clay had been frequently introduced to control red tide was calculated based on numerical model. The tidal current in the Obido channel showed northwestward flow during flood tide and southeastward flow during ebb tide with the highest water velocity of 15 cm/s, particularly, in the west mouth of the channel. Overall, the velocity of residual current in Obido channel with the highest value of 10 cm/s was higher than that between Obido and Mireukdo showing 1~3 cm/s of velocity with westward flow. Spreading and sedimentation of clay by the application of numerical model in the Obido channel was calculated under the assumption that 360 tons of clay had been introduced every day for 20 days in the area during red tide period in 2003. Clay particle spreaded toward westward in the channel and subsequently northward in the outside of the channel from the release point located in the center of the channel. It was calculated that 1.5 km2 in total nearby Obido area could be affected by the clay water with more than 1 mg/L of clay concentration within five tidal cycle after dispersion. The majority of the clay particle could be settled within 100 m from the release point with the sedimentation height of 10 mm. Also, it was calculated that the clay could show 0.2 mm of sedimentation height in the west and east mouth of Obido channel.
In this research, we analyzed the relation between agricultural productivity and climatological data in highlands of Pyeongchang, Gangwon-do. Highland agricultural productivity index (HAPI) was developed using existing agriculture climate index and observation data set. Climate modeling system was constructed for simulations over complex mountainous terrain. Additionally a relation between the productivity and spatial HAPI was studied. The result shows a close corelation between temperature, important for vegetable growth, and vegetable productivity. Climate simulation was performed and the computed 10 years data were compared with data from regional meteorological office in Daegwallyeong. Using the result the HAPI was estimated for each grid (1 km) of the model domain.
A method for rapid micropropagation of Ophiopogon japonicus through plant regeneration from leaf, rhizome and root explants derived calli has been developed. Leaf, rhizome and root segments were cultured on Murashige and Skoog (MS) medium supplemented with plant growth regulators (2,4-D, NAA, IAA; 0~3.0 mg/ L) for callus induction. Callus production was highest at 1.0 mg/L 2,4-D where 91%. These calli were transferred to MS medium supplemented with various concentrations of 2,4-D (0, 0.5, 1.0, 3.0 mg/L) in combination with 6-benzyladenine (BA: 0, 0.5, 1.0 and 3.0 mg/L) for adventitious shoot regeneration. The addition of low concentration of 2,4-D into BA containing medium significantly increased the frequency of shoot regeneration in both leaf, rhizome and root derived calli. The highest frequency of adventitious shoot (88%) formation was on MS medium supplemented with 0.5 mg/L 2,4-D and 1.0 mg/L BA. For rooting of the shoots, half-strength MS medium supplemented with different concentrations of plant growth regulators (2,4-D, IBA, NAA) 0, 0.1, 1.0, 3.0 mg/L was tried. The optimal results was observed on half-strength MS medium supplemented with 3.0 mg/L NAA (average of 42.9 roots per explant). In vitro raised plantlets were acclimatized and transferred to soil with 100% success. This in vitro propagation protocol would be useful for conservation as well as mass propagation of this medical plant.
The taxonomy of the Isodon excisus complex, which comprises I. inflexus var. inflexus, var. transiticus, var. macrophyllus, var. microphyllus, and var. canescens, has been ambiguous and problematic because their morphological characters are variable. To elucidate the taxonomic structure of the I. inflexus complex in Korea, 42 characters were measured from 70 OTUs representing the I. inflexus complex and were analyzed by a principle component analysis (PCA). The principle component axes 1, 2, and 3 (PC1, PC2, and PC3) represents 55.7% of the total variance. The characters showing high loading values for PC1, which have of absolute loading values higher than 0.7, were characters related to the leaf base and leaf teeth and the length of corolla tube. The length of the broadest part to the apex in the leaf, the density of non-glandular hairs on the lower surface of the leaf, and the length and width of the calyx were highly related to PC2 with the absolute loading values higher than 0.7. PC3 does not have any characters which have absolute loading values higher than 0.5. Three-dimensional scatter plots of the OTUs for the PC1, PC2, and PC3 axes showed that there are three taxa in the complex. Each area of I. inflexus var. inflexus, var. transiticus, and var. macrophyllus was completely overlapped, demonstrating that this taxon is I. inflexus var. inflexus. Areas for var. microphyllus and var. canescens were separated from that of var. inflexus in both cases. Therefore, we recognized three varieties, which are I. inflexus var. inflexus, var. microphyllus and var. canescens in the I. inflexus complex in Korea. This result also indicates that I. inflexus var. inflexus has a wide range of morphological variation. The recognition of var. microphyllus and var. canescens is also supported by the result of recent SEM studies of the fruit surfaces of Korean Isodon.
Marine algal flora and community structure were investigated seasonally at six sites in the vicinity of Mokpo harbor, on the west-southern coast of Korea from March to December 2004. In total, 88 species including 13 green algae, 20 brown algae, and 55 red algae were collected and identified. Among these species, 21 species were found throughout the year. Gelidium divaricatum and Caulacanthus ustulatus were distributed mostly in the upper intertidal zone. By contrast, Ulva pertusa and Sargassum thunbergii occurred predominantly in the middle intertidal zone. Sargassum fusiforme, S. thunbergii and Chondria crassicaulis were most common in the lower intertidal zone. The annual mean biomass in wet weight was 234.7 g m−2. The maximum biomass was recorded in spring (317.5 g m−2) and minimum was recorded in winter (156.9 g m−2). The R/P, C/P, and (R+C)/P values reflecting the flora characteristics were 2.75, 0.65 and 3.40, respectively. Two groups were produced by cluster analysis, one including group close to inland sites 1, 2, 6 and the other including group in offshore sites 3, 4, 5.