• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.3
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• pp.364-372
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• 1995

On the outbreak of paralytic shellfish poisoning in April 1993 in most of shellfish harvesting areas in Jinhae Bay, Korea, to clarify the toxin production of causative organism Alexandrium species, 19 axenic clonal isolates established from the benthic resting cysts in three different stations of those culture grounds were subjected to PSP toxin analysis by HPLC. Individual toxin content per cell was highly variable among the strains isolated from a sampling area and originated from an individual cyst. Average toxin contents in those areas revealed higher values of 54-70 fmol/cell. Toxin profiles included C1/C2(epiGTX8/GTX8), GTX1/GTX4 and neoSTX as the major components, and GTX2/GTX3, GTX5, C4, dcSTX and STX as the minor or sporadic ones. neoSTX on the dominant toxins showed not only most diverse compositional changes comprising $5-54 mol\%$ ranges but also no detection on the half of the strains examined, which were implicated in arising of heterogeneity with a genetic trait within a geographical region. When average toxin composition was compared, carbamate toxins comprised large proportions of $57\%,\;54\%\;and\;67\%$ as total toxin in St. 1, St. 2 and St. 4, respectively. These results suggested that an extensive paralytic shellfish toxification in Jinhae Bay could be largely due to the production of highly potent carbamate toxins in the causative dinoflagellate Alexandrium species.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.334-343
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• 2014

BACKGROUND: Shorebirds use a variety of wetlands as their stopover sites to replenish energy and nutrient reserves along the migration route. It is increasingly important to understand how birds use the remaining available habitats during migration period, because shorebird stopover sites are often altered and destroyed. Rice fields serve as a major inland stopover site for migrating shorebirds. However, the information on habitat use patterns of shorebirds in rice fields is very limited in Korea. Therefore, we studied the patterns of shorebird abundance and their habitat use in rice fields during spring migration period in western-central Korea. METHODS AND RESULTS: Surveys were conducted at interval of 2-3 days during the spring migration period of 2014 at rice fields of mid-western Korea. We recorded the location of the observed birds on the rice field map according to the local habitat type. The habitat types were divided by physical structure and cultivation methods. Fifteen shorebird species and 7,852 individuals were recorded during the survey period. The number of shorebird species and their abundance began to increase from the beginning of flooding in late-April, and reached a maximum in early-May. After rice transplantation, the number of shorebird species and their abundance dramatically declined. Shorebirds selectively used paddy and levee rather than road and ditch and most species used shallow depth field type. Plowed field types were less attractive to most species. CONCLUSION: Flooding rice fields were functioned as stopover sites for a variety of shorebird species during spring migration period. Furthermore, these results provide that the appropriate agricultural practices can be improving the habitat quality for shorebirds.

• Korean Journal of Environmental Biology
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• v.18 no.2
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• pp.279-290
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• 2000

To alleviate the harmful effects from contamination, the Sihwa Lake waters have been regularly fluxed out into the ocean to mix and circulate with the oceanic waters, and then allowed to flow back into the lake. In the present study, eco-environmental impacts by the outflowing contaminated lake waters to the benthic communities of the coastal zones along Kyonggi Bay were examined at three separate areas. A total of 22 groups of meiobenthic animals were commonly found in the subtidal zones of the Bay. All groups of the meiobenthic animals on the 1st and 7th days after the outflow were remarkably reduced in numbers from the selected areas examined, as compared to those observed one day before the outflow. It was also found that the community structure of meiobenthos was changed drastically: At the station near the water gate, for example, where the immediate outflow of the lake water was encountered, the benthic harpacticoids, the group observed to be one of the predominant groups before the outflow, were found to have disappeared completely. For an area that was relatively far away from the water gate, the reduction rate of meiobenthos after the outflow events was slower and more gradual than the nearer sites. An area that is the farthest from the water gate, no reduction in any of the meiobenthos group was observed. The ratio between nematodes/copepods (N/C) was remarkably changed by the outflows at the station near the water gate: One day before the outflow, the ratio was 0.7 while the ratio was 19.0 at the station near the water gate. In contrast, at the stations relatively far from the water gate, the ratio decreased one day after the outflow event, but increasing trends were observed one week later. In the tidal flats, Station 1 exhibited the common observed regional values of the ratio whereas Station 2 showed a very high ratio of 191.3. The results suggested that the contaminated lake water outflows directly effect meiobenthos in a relatively short time period and thus the meiobenthos may be a good indicator animal group for examining the effect of pollution. [Lake Sihwa, contaminat water outflow, meiobenthic animals living]

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.3
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• pp.125-132
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• 2007

We estimated the distribution of predator-prey interaction strengths for 12 species of herbivores (including amphipods, isopods, gastropods, and sea urchins) and made a regression model that may be applicable to other species. Laboratory experiments were used to determine per capita grazing rate (PCGR; g seaweeds/individual/day). Relationship between the biomass of individual grazers and fourth-root transformed PCGR was fitted to power curve ($y=0.2310x^{0.3290}$, r=0.8864). This finding supported that the grazing efficiency was not even as individual grazers increase in size (biomass). Therefore, the biomass-normalized PCGR was estimated and revealed that smaller size herbivores were more effective grazers. Grazing impact considering density of each taxon was calculated. The sea hare Aplysia kurodai had greatest grazing impact on the seaweed bed and the sea urchin Strongylocentrotus nudus and S. intermedius were ranked in descending order of the impact. The amount of seaweed grazed by the amphipod Elasmopus sp. (>4,000 $ind./m^2$) and Jassa falcata (>2,000 $ind./m^2$) were 3.435 and $1.697mg/m^2/day$ respectively. The combined grazing amount of herbivores was $5,045mg/m^2/day$ in the seaweed bed. Although sea hare and sea urchin had strong impacts on seaweeds, the effects of dense, smaller species could not be seen as negligible. Surprisingly, the calculated grazing potential of sea urchins with a mean density of 3 $ind./m^2$ exceeded the mean production of seaweed cultured in domestic coastal waters in Korea (ca., 5 ton/ha). Small crustaceans were also expected to consume up to 16% of the seaweed production if their densities were rising under weak predation conditions. Considering that the population density of herbivores are strongly controlled by fish, human interference like overfishing may have strong negative effects on persistence of seaweeds communities.

• Journal of Korean Society of Forest Science
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• v.30 no.1
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• pp.30-41
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• 1976

The workers involved in breeding the growth of forest trees as well as in the efficiency of breeding work wish to find out the evidence that juvenile-mature correlations are high and that therefore early tests can be profitably employed in relation work. Juvenile-mature correlation denotes in general sense the interdependence between qualitative or quantitative data collected at different intervals during the life cycle. The correlation can also be obtained through the stem analysis if there is the possibility of cutting sample trees needed amount. In the present study, the juvenile-mature correlation coefficients are calculated from the stem analysis data. The every possible values of correlation coefficient between the 5-year age groups as to diameter, height, and volume growth of Pinus koraiensis S. et Z. and Larix leptolepis Gord. grown in the middle district of Korea were calculated. All the sample trees were cut from the man made plantation. The correlation coefficients are presented in tables and figures. In Pinus koraiensis S. et Z., the values of correlation coefficient between the successive age groups of heights growth are lower in general than those values pertaining to diameter growth. This tendencies are indifferent to site quality. In Larix leptolepis Gord., the values were lower thant these of Pinus koraiensis S.etZ. In any species and characteristics studied, the implications that at least 15 years growth character are related to 35 or 40 years size with reliability could be deduced. Through the relative ranking studies of diameter, height and volume growth of Larix leptolepis Gord., the large varieties among individual trees are appeared during 5-year to 35 year old.

• 한국해양학회지
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• v.8 no.1
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• pp.33-45
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• 1973

Plankton samples used for the present study were collected by the NORPAC net during the CSK cruises in the Korean waters in March and August, 1967. Regional and seasonal variations in the zooplankton biomass (wet weight, mg/㎥) were noticed in the Korean waters. In March the highest biomass, 130mg/㎥ on the average, occurred in the southern part of Japan Sea, but the lowest biomass of less than 50mg/㎥ occurred in the Yellow Sea and the western sea of Cheju Island Contrally, in August, the average biomass of 120mg/㎥ was measured in the Yellow Sea, the western sea of Cheju Island and the coastal waters of southern Korea, while the biomass of Japan Sea was the lowest of the regions surveyed. In comparison with the zooplankton biomass, total number of zooplankton per cubic meter of water strained also showed regional and seasonal fluctuations. In general, variations in the number of zooplankton specimens follows the same trend as in the biomass. The largest number, up to 800mg/㎥ on the average, occurred in the southern part of Japan Sea in March and the lowest number, less than 200mg/㎥ occurred in the Yellow Sea and the western sea of Cheju Island. In August, as shown by the biomass fluctuations, the largest number of zooplankton 850mg/㎥ on the average occurred in the Yellow Sea, the western sea of Cheju Island and the coastal region of southern Korea. But the lowest number of less than 500mg/㎥ was found in the Japan Sea. Among the various groups of zooplankton examined, the following were dominant components of the zooplankton population: Copepoda, Chaetognatha, Siphonophora, Euphausiacea, Cladocera, Appendicularia, and Amphipoda. The zooplankton conposition was significantly differed between the Japan Sea and Yellow Sea. Copepods which usually occupied over 66% in the Japan Sea and thd Korean Strait samples occupied only 42% of the catches in August, while cladocerans and chaetognaths were relatively abundant, i. e., 15 and 18% of the total organisms. The most dominant species of copepods and chaetognaths were Paracalanus parvus, Oithona similis, Acartia clausi, Calanus helgolandicus, Sagitta enflata, S. bedoti, S. elegans and S. crassa.

• Korean Journal of Environmental Biology
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• v.31 no.2
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• pp.105-112
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• 2013

Environmental parameters and phytoplankton community structure were investigated at four sites of Yeongsan River between April 2010 and December 2011. The standing crops of the phytoplankton ranged from $275cells{\cdot}mL^{-1}$ to $58,600cells{\cdot}mL^{-1}$ with an average of $5,850cells{\cdot}mL^{-1}$. The dominant species were Cyclotella sp., Stephanodiscus sp., Aulacoseira granulata, Scenedesmus quadricauda, Pediastrum biwae, Coelastrum sp., Aphnizomenon sp., and Oscillatoria sp.. The most dominant species was Stephanodiscus sp.. The concentration of chlorophyll-a ranged from $2.3mg{\cdot}m^{-3}$ to $164.2mg{\cdot}m^{-3}$. The phytoplankton community structure of the survey area was influenced by temperature and rainfall.

• Korean Journal of Ichthyology
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• v.23 no.4
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• pp.300-304
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• 2011

The reproductive characteristics of Chaenogobius gulosus was examined using 333 specimens collected monthly between October 2008 and September 2009 in the coastal waters of Tongyoung, Korea. Specimens ranged from 2.0 to 12.6 cm in standard length (SL). The gonadosomatic index (GSI) of females was highest in February and decreased until April, with the spawning season lasting from December to April. The monthly ratio of female to male did not significantly differ (${\chi}^2$-test, p>0.05). The size at 50% maturity for females was 7.9 cm SL. Fecundity ranged from 1,112 to 6,059 eggs, with a mean of 3,011 eggs.

• Korean Journal of Environmental Biology
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• v.18 no.4
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• pp.411-424
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• 2000

In order to investigate the population structure and dynamics of halophilous springtails and ants at seashores in Korea, we made quantitative collection from three different sites having different vegetation and environment. The pH, salinity, and electric conductivity of the three sites were measured in order to find environmental factors influencing on their species composition and distribution. In view of the results so far obtained, the species composition and distribution of springtails seemed to depend not so much on pH and vegetation as on soil texture and salinity. On the other side, ant populations seemed to depend on vegetation in sand area and on inundation in both sand area and salt marshes. In all investigated sites, the species diversity in supra littoral zones was higher than in intertidal zones, and among intertidal zones of sand beach and salt marshes it was the highest at the upper zone of the sand beach.

• Korean Journal of Environmental Biology
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• v.29 no.1
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• pp.11-16
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• 2011

Distribution characteristics of two dominant paracalanids of the family Paracalanidae on temperature and salinity were studied in the brackish and coastal waters from the West and South coasts of Korea. Bestiolina coreana mainly occurs in a range of 29.8~31.3 psu salinity and temperature of more than about $20^{\circ}C$, while Paracalanus parvus s. l. mainly occurs in a range $17{\sim}20^{\circ}C$ temperature and more than 30 psu salinity. The fact clearly indicates that temperature and salinity was a major factors in spatio-temporal distribution between these two paracalanids.