• Journal of Korean Society on Water Environment
• /
• v.26 no.3
• /
• pp.518-524
• /
• 2010

Continuous removal of organic matters (CROM) using freshwater bivalve Anodonta woodiana was operated to evaluate the effect of water current on the water quality improvement (clearance) of eutrophic lake. The CROM system comprised three treatment steps such as flow control, treatment and analysis, and operated at the two different currents ($24L\;h^{-1}$ and $48L\;h^{-1}$) with mussels at density of $312.5indiv.\;m^{-2}$ for 12 consecutive days. Water quality including suspended solids (SS) and chlorophyll-a (Chl-a) was daily measured at the same time. Results indicate that although both the system strongly decreased the concentration of SS and chl-a, a slow CROM system was more effective to diminish the SS contents than a fast CROM system; 82% and 66%, respectively (ANOVA, P<0.0001). Clearance rates, based on chl-a, were also significantly higher in a slow system than a fast system (ANOVA, P<0.0001), although the mussel mortality was conversely. In both systems, there showed a remarkable excretion of dissolved inorganic nutrients (i.e. $NH_3-N$ and $PO_4-P$), while a slow CROM system was higher than a fast system, significantly (ANOVA, P<0.0001). Therefore, it may suggest that a slow current CROM system is more suitable to maximize the efficacy of water quality improvement, but further study is needed to diminish the mortality of mussel and to reuse the nutrient released during the operation.

• Korean Journal of Environment and Ecology
• /
• v.20 no.4
• /
• pp.365-373
• /
• 2006

With a few exceptions, Korean lakes are artificially constructed for multi-purposes throughout the country. In the majority of cases, a lake is in a multiple series of reservoirs along a river or is an estuary Moreover, nutrient supplying activities (including sand extraction) and biomanipulation(esp., overfishing and fish introduction) are omnipresent in most cases. Furthermore, there is an Asian monsoon every year. In brief, europhication and algal blooms break out as a result of complicated causes. However limnological monitoring and scientific working programs are in the course of beginning. The question is what kind of strategy is desirable to establish a solid limnological database for the efficiency of the restoration process in each Korean reservoir We present light monitoring cases on the basis of algal and some physicochemical data in 2005. Do they give some useful informations despite their simplicity. Based on physicochemical factors and phytoplankton data using Utermohl method and Canonical Correspondence Analysis(CCA) were performed for Lake Cheongpyeong, Lake ASan, Lake Namyang, and Lake SapGyo. The results of CCA showed that Lake Cheongpyeong was different from the other three Lakes at estuary. Also each Lake at estuary was slightly different from one other. This result would encourage to initiate building an adequate Korean reservoir-ecosystem understanding and models for better ecological management despite the limited data. However, the results also indicate to sustain collecting ecological data and building database to interpret the Korean ecological reservoir model.

• Korean Journal of Ecology and Environment
• /
• v.36 no.2 s.103
• /
• pp.215-220
• /
• 2003

Three lakes (lake Homanpo, Hyunkum and Daein) were revealed to be brackish by the results of zooplankton fauna and salinities (2.8 ppt and 0.8 at lake Hyunkum in May and October 2002, and 1.5 and 0.5 at the Daein) in Shinpo district, North Korea. Among 34 taxa of zooplankton occurred, copepods and rotifers showed the prosperity in species number with 15 species and 7 species, respectively. Twenty four taxa of freshwater animals, six brackish ones and four marine ones were found, Brackish copepods, Pseudodiaptomus inopinus and Sinocalanus tenellus, were found in all lakes. More than 90% of zooplankton abundances consisted of brackish and marine species in three lakes. The outburst of S. tenellus was observed (59,000 indiv./$m^3$) at lake Hyunkum in May, when the proportion of brackish and marine zooplankton exceeded 99% of total zooplankton abundance. Long-term monitoring appears to be needed to provide basic data to protect brackish lakes in the study area.

• Journal of Ecology and Environment
• /
• v.42 no.4
• /
• pp.240-258
• /
• 2018

Background: Several investigations carried out from large brackish lagoons in South Korea. However, no studies have yet examined phytoplankton in lagoons that changed to freshwater, such as Cheonjin Lake. The present study examined the algae from Cheonjin Lake. Methods: Samples were collected at monthly inetrvals from May 2017 to April 2018, from the surface layer using a plankton net (mesh size $20{\mu}m$), and sequeezing submerged macrophytes. Microscopic examinations were conducted at a magnification of 200 to 1000x using a Zeiss microscope (Axio Imager. A2), and photographs were taken with an AxioCam HRC camera. Silica-scaled samples of Chrysophyta for SEM were placed on coverglass, air dried, coated with gold, and then examined with a Hitachi SV8220 SEM. Results: A total of 376 taxa from six major algal groups (Chlorophyta, Chrysophyta, Euglenophyta, Cyanophyta, Dinophyta, and Cryptophyta) were identified. Among these algae, 28 taxa of desmids, 9 taxa of Euglenophyceae, 4 taxa of Chlorophyceae, 2 taxa of Chrysophyceae, and 1 taxon of Xanthophyceae are reported for the first time in Korea. A new species, Cosmarium hexagonum sp. nov was described. The phytoplankton communities were characterized by an abundance of Desmids (within Charophyceae) accounted for 148 taxa from 22 genera. Species richness were particularly high in the Autumn. Conclusion: In this study, a total 376 taxa of 148 desmids (Charophyceae), Chlorophyceae (103 taxa), Chrysophyceae (53 taxa), Euglenophyta (49 taxa), Dinophyta (8 taxa), and Cryptophyta (2 taxa) were identified from Cheonjin Lake. Twenty-eight taxa of desmids including a new species (Cosmarium hexagonum sp. nov.), 9 taxa of Euglenophyceae, 4 taxa of Chlorophyceae, 2 taxa of Chrysophyceae, and 1 taxon of Xanthophyceae were newly recorded in Korea.

• The Korean Journal of Malacology
• /
• v.14 no.2
• /
• pp.167-172
• /
• 1998

As a preliminary study, effects of environmetal pollutants on propagation of freshwater microalgae, Cryptomonas ovata and feeding rate of Corbicula leana were investigated at 20${\pm}$1$^{\circ}C$, over 20 days after treatment of pollutants, glucose, complex fertilizer and NH4Cl. Number of C. ovata in control group was increased from 38${\times}$104 cell/ml to 1.910${\times}$104 cell/ml after 20 days cultivation in Sorokin-Krauss medium. Increments of cell number in experimental groups treated with glucose, complex fertilizer and NH4Cl were higher than that of control group. The higher propagation rate of C.ovata was observed when 30 mg/l of glucose treated, 120 mg/l of complex fertilizer treated, and 4 mg/l of NH4Cl treated, compared with other concentrations in each pollutant treated group. The feeding rates of large size group of C. leana which fed with a living organism, C. ovata in each experimental group were higher than small size group, and slightly reduced with the increase of pollutant concentrations. The feeding rates were not significantly different between any concentrations of the pollutant, and among experimental groups treated with glucose, complex fertilizer and NH4Cl.

• The Korean Journal of Malacology
• /
• v.2 no.1
• /
• pp.10-12
• /
• 1986

Pettancylus nipponicus (freshwater limpet) collected from the Lake Choon Cheon were cultrued in aquarium and studied in the respects of an egg deposition and the developmental characters of cleavage. The species were collected only in the Lake Uiam and Choon Cheon and easily sampled on the debris like vinyls and cans. Those smooth surfaces were suitalble substrata for attaching. P. nipponicus, about 4 mm in adult, deposited an egg in one calcareous egg-capsule on the aquarium walls, while many eggs are surrounded in a jelly-like egg-envelope in the most gastropods. And another special features was that an egg-capsule was consisted of two valves and the suture was opended as hatching. A diameter of its egg was $55{{\mu}m}$ and the length of an egg capsule was $620{{\mu}m}$ and $510{{\mu}m}$ in long and short diameter, respectively. It took about 8 hours from beginning cleavage to 16-cell stage and about one year to become an adult.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2005.10a
• /
• pp.443-449
• /
• 2005

As sustainable development and environment-friendly efforts in large-scale development projects emerge as major interests at home and abroad, man-made wetlands and eco-park facilities have been newly planned or created when developing reclamation districts recently. In this study, based on findings from a comprehensive review of relevant studies and planning cases, the basic direction and objectives of the plan were developed. A comprehensive analysis on the status of ecological environment and demographic and social environment showed that the planned site is in a process of migrating from early stages of reclamation to middle stages. It was planned for the eco-park to function as a major base along an ecological network consisting a freshwater lake and rivers and streams flowing into the lake in Hwaong District. Through a master plan and sectoral plans were planned according to desalination levels after reclamation. Then, habitats for livings organisms were also planned. The eco-park, the planned site, is also in a process of migrating from the early stages to middles stages. By creating an eco-park that considers post-reclamation ecological environment changes, natural succession processes will be preserved, which is expected to help local ecosystems to restore their functions on their own over a relatively long period of time and enable to observe the restoration process.

• Korean Journal of Ecology and Environment
• /
• v.41 no.3
• /
• pp.367-373
• /
• 2008

A freshwater bivalve (Unio douglasiae) was examined to assess the filtering rate (FR) on the cyanobacterial assemblage in a hypertrophic lake. Animal U. douglasiae used in the present study was collected using a hand-operated dredge from the North Han River (Gapyeong, Korea). The FR was measured at different feeding conditions such as feeding interval (1, 4, 7, and 24 h), mussel size (4.2$\sim$8.1 cm, n=23), prey concentration (506.7, 409.8, 327.5, 199.7 and 88.6 ${\mu}g\;L^{-1}$), and mussel density (0.5, 1.0 and 1.5 indiv. $L^{-1}$). On the applied feeding interval, the maximum FR (0.21 L $g^{-1}h^{-1}$) and minimum feces production (FP, 0.12 mg $g^{-1}h^{-1}$) were observed at 1 and 24 hr, respectively. Both weight-based FR and FP were not correlated with the mussel size, and the values lied in a limited range with some degree of variation. Likewise, no significant relations between FR and FP were observed in the mussel size. The FR values were negatively correlated with food concentration, but positively with FP. For the food concentrations, the maximum FR (0.41 L $g^{-1}h^{-1}$) and FP (0.16 mg $g^{-1}h^{-1}$) were 88.6 ${\mu}gL^{-1}$ and 327.5 ${\mu}gL^{-1}$, respectively. These results indicate that U. douglasiae collected from the North Han River, although the filtering rate were slightly less than Keum River mussel, may be applied as a strategic bio-filter to mitigate cyanobacterial bloom in eutrophic lake.

• Korean Journal of Ecology and Environment
• /
• v.47 no.spc
• /
• pp.83-99
• /
• 2014

Fish community of eight lagoons in the east seashore, Korea were investigated from 2007 to 2008. Total 66 species caught during the period were belonged to 34 families, and total biomass was 2,024.8 kg. Also, similarity analysis results of each lagoon were divided three major groups. On the other hand, result of a comparison of the composition ratio of freshwater fish, brackish water fish, and seawater fish which is divided into separate each age data of previous studies has emerged in this study, since the 1990's, freshwater fish is reduced, seawater fish and increase, some changes in the fish community had changed dynamically in the lagoon. These changes considered that against the natural hydrach succession will change to freshwater lake from brackish water lake. Therefore, we considered to ecological characteristics of lagoon and process of hydrach succession when conservation, management, and restoration of the lagoons.

• Korean Journal of Ichthyology
• /
• v.19 no.1
• /
• pp.24-34
• /
• 2007

After releasing more than 1,000,000 fertilized eggs of Plecoglossus altivelis into Lake Okjeong, Jeollabuk-do, on October, 2001 by KOWACO, they seem to be land-locked. Study on the distribution and ecology of a land-locked ayu, P. altivelis, was performed from Lake Okjeong to upper streams as Jowon, Churyeong, Oknyedong where consisted of rocky bottom with fast current freshwater system during April to October. The hatched larva and juveniles descended from streams to Lake Okjeong and inhabit Lake Okjeong from November to next March. The sex ratio of female to male was 1 : 2.70, and the size in standard length of females and males was similar, in $90{\sim}220(142{\pm}29.3)mm$. During the middle September to the middle October, they laid eggs on the pebbly bottom of the rapids which are $20{\sim}22^{\circ}C$ in water temperature and 30~70 cm in depth. The number of full-grown eggs was greatly various from 14,283~91,500.