• Korean Journal of Ecology and Environment
• /
• v.45 no.4
• /
• pp.403-411
• /
• 2012

Acoustic telemetry is used to obtain a relatively continuous record of fish movement. This method has several advantages for studying migrating fish populations that are moving from large rivers. The Nakdong River is the longest river in South Korea and the main stream has faced a change, which consists of the installation of the large weirs. In this study, we applied acoustic telemetry to monitor the movement pattern of Erythroculter erythropterus (family Cyprinidae) and identified home range and movement distance in the Nakdong River. A total of fourteen individuals were released at three different locations and around 80 km section from the estuary barrage was investigated. Eight individuals were tagged and released at estuary barrage (N02) utilized up to 15.9 km (home range) upstream from the release site as home range. Four individuals were tagged and released at Samrangjin (N07), most fish moved and stayed within 9.7 km (home range) downstream area, except E12, which did not show any movement. Two individuals were tagged and released at Changnyeong-Haman weir (N10), and all individuals migrated downstream from the release site. Especially, E14 recorded the longest accumulated detected distance, 36.7 km downstream during 32 days after release. There was no correlation identified between movement (accumulated detected distance and home range) and standard length (Spearman rank correlation, p>0.05). Although, this technique could be an available method to monitor behavior and ecology of freshwater fish effectively, increment of number of receivers and tags are required for more detailed results of fish migration.

• Korean Journal of Environment and Ecology
• /
• v.35 no.4
• /
• pp.408-423
• /
• 2021

We established and monitored survey sites in seven regions of Mt. Jiri to investigate population decline and change of the Korean fir (Abies koreana) over a ten-year period from 2009 to 2018. With the exception of one site (Seseok), the six remaining ones all showed a four-layer stratification structure. The importance value of Korean firs in all of the survey areas decreased significantly by 28.5%, from 55.7% in 2009 to 39.8% in 2018. The average population of objects with a diameter at breast height (DBH) of 5cm or more in all survey sites was 711 objects/ha in 2018, and the cumulative death rate from 2009 to 2018 was 10.8%. Among the death types, DS (dead standing) was the most dominant, comprising 82.4% of the total survey area. However, in Banyabong 1, which had a high gradient of 35°, the death types other than DS accounted for 44.2%. We estimate that A. koreana can maintain a stable population as its distribution type for each diameter class in the Saeseokpyeongjeon site showed a reverse-J shape. The average annual ring growth in all survey sites was 1.09 mm/year, with the most abundant growth observed in the Seseokpyeongjeon site, which was formed mainly by a subtree layer. The growth ring survey showed the estimated average age of A. koreana population in the Byeoksoryeong and Banyabong 1 sites to be 102 and 91 years, respectively, a general downward trend of vitality since 2013.

• Korean Journal of Poultry Science
• /
• v.37 no.1
• /
• pp.81-87
• /
• 2010

To estimate the genetic characteristics and cumulative power of discrimination (CPD) Korean Native Chicken. We used a total of 195 genomic DNAs from four breeds population (Korean Native Red chicken: R, Korean Native Yellow chicken: Y, Korean Native Black chicken: L, Ogal chicken: S). Frequencies of microsatellites markers were used to estimate heterozygosities and genetic distances. The lowest distance (0.05) was observed between the R and L strains and the highest distance (0.158) between the L and S strains. Korean native chicken strains (R, Y, K) have each other comparatively near genetic distance. Cumulative power of discriminate (CPD) was 99.999% by including the 10 microsatellites loci individual identification system. And then matching probability in that two different individuals incidentally have same genotype was estimated to $0.36{\times}10^{-7}$. The system employing the 10 markers therefore provided to be applicable to individual identification in Korea native chicken.

• Korean journal of applied entomology
• /
• v.58 no.4
• /
• pp.347-354
• /
• 2019

Temperature-dependent traits of Laodelphax striatellus, rice stripe virus vector, were investigated at 10 constant temperatures (12.5, 15.0, 17.5, 20.0, 22.5, 25.0, 27.5, 30.0, 32.5, and 35.0 ± 1℃) under a fixed photoperiod (14/10-hr light/dark cycle). Unit functions for the oviposition model were estimated and implemented into a population dynamics model using DYMEX. The longevity of L. striatellus adults decreased with increasing temperature (56.0 days at 15.0℃ and 17.7 days at 35.0℃). The highest total fecundity (515.9 eggs/female) was observed at 22.5℃, while the lowest (18.6 eggs/female) was observed at 35.0℃. Adult developmental rates, temperature-dependent fecundity, age-specific mortality rates, and age-specific cumulative oviposition rates were estimated. All unit equations described adult performances of L. striatellus accurately (r² =0.94~0.97). After inoculating adults, the constructed model was tested under pot and field conditions using the rice-plant hopper system. The model output and observed data were similar up to 30 days after inoculation; however, there were large discrepancies between observed and estimated population density after 30 days, especially for 1^st and 2^nd instar nymph densities. Model estimates were one or two nymphal stages faster than was observed. Further refinement of the model created in this study could provide realistic forecasting of this important rice pest.

• Journal of the Korean GEO-environmental Society
• /
• v.8 no.5
• /
• pp.15-21
• /
• 2007

This study was investigated to evaluate the effect of electric fields application for the reduction of membrane fouling, the inactivation of microorganisms and the enhancement of particle coagulation in microfiltration/coagulation. Cumulative permeate in the case with electric field treatment showed high value compared to the case without electric field. Particularly, the increase of HRT (Hydraulic retention time) showed the increase of cumulative permeate as well as the decrease of total resistance. By electric field treatment, the amount of small particle size less than 100 ${\mu}m$ is increased and the survival fraction is reduced by the increase of electric field intensity. This may be attributed to the cleavage of particle or cytological destruction resulting from the inactivation of microorganism. Coagulant dosage of PAC compared with no electric field application could also be saved about 75% for the 95% of turbidity removal at 10 kV/cm.

• Korean Journal of Environmental Biology
• /
• v.20 no.3
• /
• pp.256-262
• /
• 2002

This research investigated experimentally on the population growth in the aquatic microcosm with the wastewater of plating factory. The purpose of this study was to evaluate the effect of culture conditions of the characteristic growth pattern of the examined species. Population of the system is consists of three organisms; Chlorella vulgaris as a producer, Cyclidium glaucoma as a consumer and Pseudomonas putida as a decomposer. The different growth patterns of each population are followed by surfactant type; Especially C. glaucoma was sensitive, Ch. uvlgaris was maintained population size stably even at high level of surfactant and p. putida was not significantly affected. After treatment of waste water from plating factory, it began to be affected at 1.0% solution treatment to Ch. vulgaris which the cell number was decreased prominently after 2 days, and C. glaucoma was disappeared at 2.5% solution treatment. P. putida was showed increasing pattern according to treatment concentration, at 2.5% solution and population size grew double. The result from current microcosm study indicates that this model system can be applied to environmental assessment method for various pollutants.

• Journal of Korean Society of Forest Science
• /
• v.108 no.4
• /
• pp.663-674
• /
• 2019

Birds are effective ecological indicators but there is no national protocol in place to monitor population dynamics of forest birds in Korea. To support the establishment of future monitoring protocols, we compared the results of two generally used monitoring methods for forest bird surveys in two temperate mixed forests in central Korea. There was no statistical difference in the number of species and individuals detected per unit survey effort when comparing line transects and point counts. The number of species and individuals were higher in a five-minute count than in a three-minute point count, but the total accumulated number of expected observed species showed no difference between the two count durations. The number of observed species and individuals increased in both methods as plot radius or transect width increased, suggesting that multi-layer or multi-band surveys may be useful for quantitative and qualitative objectives. The decreasing number of observed species and individuals after sunrise suggested that bird monitoring should be conducted earlier in the morning, within four hours after sunrise. To detect 70% of the total number of species, 7.0 to 7.6 survey hours, equivalent to 42 three-minute counts (95% confidence interval [CI]: 26 to 61) or 33 five-minute counts (95% CI: 19 to 53) were needed for unlimited radius point counts. On the other hand, 4.8 survey hours, equivalent to 26 line transect counts (95% CI: 15 to 45) using 200-m transects with unlimited width, were required to achieve the same level of species detection. Therefore, the line transect method may be more effective than the point count method, at least in terms of local species richness assessment. For national forest bird monitoring, our data indicated that one or both survey methods can be selected as a basic protocol, based on the goals and scales of monitoring, forest types, and the conditions of the target areas.

• Journal of Marine Life Science
• /
• v.4 no.2
• /
• pp.91-95
• /
• 2019

The changes of plasma cortisol concentration to high water temperature on common carp, Cyprinus carpio were studied. 20℃, 24℃ and 28℃ groups showed significantly increased plasma cortisol levels until 6 hours, and decreased plasma cortisol levels after 24 hours. Cortisol levels of 20℃ and 24℃ groups decreased to values close to the cortisol content before the experiment. However, 32℃ group showed significantly increased plasma cortisol levels until 24 hours, and maintained plasma cortisol level until 48 hours. The Cumulative mortality rates of 20℃, 24℃ and 28℃ groups increased until 12 hours, and maintained until 48 hours. Cumulative mortality rate of 32℃ group increased continuously until the end of the experiment. Using the results of this study, it could be used as a method to confirm the risk of mass perish in a specific area through hormone analysis.

• Korean journal of applied entomology
• /
• v.50 no.3
• /
• pp.235-245
• /
• 2011

Temperature-related parameters of Panonychus citri (McGregor) (Acarina: Tetranychidae) development were estimated and a stage-structured matrix model was developed. The lower threshold temperatures were estimated as $8.4^{\circ}C$ for eggs, $9.9^{\circ}C$ for larvae, $9.2^{\circ}C$ for protonymphs, and $10.9^{\circ}C$ for deutonymphs. Thermal constants were 113.6, 29.1, 29.8, and 33.4 degree days for eggs, larvae, protonymphs, and deutonymphs, respectively. Non-linear development models were established for each stage of P. citri. In addition, temperature-dependent total fecundity, age-specific oviposition rate, and age-specific survival rate models were developed for the construction of an oviposition model. P. citri age was categorized into five stages to construct a matrix model: eggs, larvae, protonymphs, deutonymphs and adults. For the elements in the projection matrix, transition probabilities from an age class to the next age class or the probabilities of remaining in an age class were obtained from development rate function of each stage (age classes). Also, the fecundity coefficients of adult population were expressed as the products of adult longevity completion rate (1/longevity) by temperature-dependent total fecundity. To evaluate the predictability of the matrix model, model outputs were compared with actual field data in a cool early season and hot mid to late season in 2004. The model outputs closely matched the actual field patterns within 30 d after the model was run in both the early and mid to late seasons. Therefore, the developed matrix model can be used to estimate the population density of P. citri for a period of 30 d in citrus orchards.

• Journal of Bio-Environment Control
• /
• v.12 no.1
• /
• pp.1-6
• /
• 2003

This study was conducted under the condition of greenhouse to investigate the relationships between the period of long day (LD) treatment before short day treatment, the dry matter production and flower quality of cut chrysanthemum (Indicum group) cv. Reagan Improved at Wagenigen University in the Netherlands. Rooted cuttings of chrysanthemum (Indicum group) cv. Reagan Improved were transplanted on 6th, 13th, loth of September and all of them were treated with short-days (SD) on 21th September. The periods from planting until final harvest were 70, 77, 84 days after being planted for 1, 2, and 3 week-LD period, respectively. The time of flower initiation was similar in all treatments. The number of flowers per plant was greater in the plot of 3 week-LD period than that in the plot of 1 or 2 week-LD period. The fresh weight and dry weight of flowers also increased more in the plot of 3 week-LD period than that in the 1 week-LD period by 4g and 0.4g, respectively. The final dry matter production ($g{\cdot}m$^{-2}$ ) was greater in the treatment of 3 week-LD period than 1 or 2week-LD period. In this study, LD period before short day treatment did not affect the time of flower initiation and flower quality. As a result, 3 week-LD period before short day treatment was strongly recommanded for producing high quality cut flowers of greenhouse-grown chrysanthemum.