• Korean Journal of Environmental Biology
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• v.31 no.2
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• pp.96-104
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• 2013

The objectives of this study were to analyze chemical the water quality related to the fish community and to evaluate the ecosystem health based on the faunal composition and guild structure in 2007 in Baekma River. Mean concentrations of biological oxygen demand (BOD) and chemical oxygen demand (COD) were 2.8 and $4.0mg\;L^{-1}$, respectively and total nitrogen (TN) and total phosphorus (TP) were $5.0mg\;L^{-1}$ and $158{\mu}g\;L^{-1}$, which is indicating that the river is in an eutrophic state. Especially, organic pollution and eutrophication occurred in the downstream reach of Baekma River. A total of 19 fish species were collected during the study and the most dominant species was Opsariichthys uncirostris amurensis accounted 48% of the total abundances. The proportion of sensitive species was low (2.3%), compared with that of tolerant species (71.8%). These results suggest that tolerant species and the biotic quality of the fish community was severely degraded. According to the multi-metric model, the Index of Biological Integrity (IBI), the mean model value of the fish community in Baekma River was estimated as 14.8 indicating a "poor" condition. The minimum values of the IBI were observed in the downstreams, and this was mainly attributed to chemical pollutions of nutrients (N, P) and organic matters.

• Korean Journal of Ecology and Environment
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• v.40 no.2
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• pp.214-222
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• 2007

This study was conducted to assay the relationship between the characteristics of watershed and water quality, and to evaluate water quality characteristics of the classified types by TSI deviation analysis with the collected data from 490 reservoir. Relatively shallow depth (<5m) reservoirs out of selected 490 appeared to be eutrophic. The mean TP concentration in reservoirs with the PFA+UFA/watershed area of above 30% was ${\geq}0.1$ mg $L^{-1}$. The mean TN concentration in reservoirs with the PFA/watershed area of above 25% was ${\geq}2.6$ mg $L^{-1}$. Based on the TSI deviation analysis, water quality parameters in TYPE III reservoirs were in high concentration compared to other reservoirs types. Characteristics of Type III generally showed eutrophic, small DA/RA ratio, shallow depth, and large paddy field and upland field to watershed ratio compared to other types of reservoirs. Both water quality and morpho-physical parameters, Type I and II reservoirs were similar with the exceptions of BOD and chi. ${\alpha}$ concentration. Phosphorus in Type I reservoirs was not the primary limiting factor on algal growth, but significant decrease chl. ${\alpha}$ concentration with the increasing TN/TP indicated that phosphorus was the possible secondary limiting factor. Overall results indicated that type of land use, such as PFA and UFA area in watershed, was important parameters for the assessment of water quality characteristics, and phosphorus was limiting nutrient on algal growth in 490 reservoirs.

• Korean Journal of Ecology and Environment
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• v.41 no.3
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• pp.402-411
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• 2008

Grazing effects of two freshwater shellfish, Unio douglasiae (UNIO) and Cipangoplaudina chinese malleata (CCM), on the hibernal diatom communities in eutrophic water was examined in a laboratory. Two animals having different feeding types used in the study were collected from Keum River (Boryeong, Korea), acclimatized in the artificial management system in a laboratory over at least one month, and starved in a laboratory for 2 days before the experiment. Experimental waters, which dominated by Synedra ulna-Scenedesmus sp. (ca. 80%), was collected from eutrophic lake, Lake Ilgam (Seoul) in Feb., 19, 2008 at AM 10:00, and used in the study after the filtration with 1 mm Nylon mesh. Feeding experiments were largely divided into three kinds of animal treatments; five densities of UNIO (U0, U1, U2, U3, U4) and CCM (C0, C1, C2, C3, C4), and four combined densities of two shellfish (M0, M1, M2, M3). U0 and C0 were control (no addition of UNIO or CCM), U1 or C1 (each animal density at 0.5 ind. $L^{-1}$), U2 or C2 (1.0 ind. $L^{-1}$), U3 or C3 (1.5 ind. $L^{-1}$), and U4 or C4 (2.0 ind. $L^{-1}$), respectively. Four combined treatments were consisted of M0 (no animals), M1 (U1+C3), M2 (U2+C2), and M3 (U4+C1), respectively. Under the presence of animal, the concentration of Chl-a and algal abundance were clearly decreased with the increase of UNIO density and the treated time, while in combined group a strong decrease of algal density showed with the increase of UNIO density. Total phytoplankton density shifted as the similar patterns to that of Chl-a concentration (r=0.6527, p<0.0001), however, there showed the differences following a species. There were strong decreases of dominant species Synedra ulna, Scenedesmus sp., Ankistrodesmus falcatus in UNIO treatment group, Diatoma vulgare in combined group, while Cryptomonas ovata in high density of CCM increased about 20% in algal density. Grazing rates (GRs) based on the concentration of Chl-a was depend on the kind of shellfish and treatment time; a strong feeding of CCM showed in the initial stage, and four hours later, UNIO and combined group with high UNIO density showed the high GRs. Interestingly, faeces production of shellfish was highest in combined group with high density of CCM, while their size over 60 ${\mu}m$ was much higher in production magnitude than that less 60 ${\mu}m$. Collectively, these results suggest that two domestic shellfish and its combined treatment have a strong potential as an effective biological controller of diatom bloom in cold eutrophic waters.

• The Korean Journal of Ecology
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• v.25 no.5
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• pp.305-313
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• 2002

The physico-chemical characteristics of water and sediment, and structures of vegetation of the vascular hydrophytes were investigated in the West Nakdong River. Water quality was eutrophic according to the mean values and the ranges of water properties such as pH, DO, BOD, chlorophyll a, total nitrogen and phosphate, and other nutrients. A few cases were hypereutrophic for chlorophyll a level in summer. Soil reaction was weak acid. Composition of sediment was mainly sand except in SI(Sinan chideung) of which was mainly clay, and SU(Suan chideung) of which was mainly silt. Flora of vascular hydrophyte had 26 species and 1 variety comprising 16 families. Trapa japonica was dominant species in the sites of DU(Dunchido), GA(Garak chideung) and SU. Nymphoides peltata and Hydrocharis dubia dominated in DA and SI, respectively. Species diversity and evenness were relatively high in SI and SU but dominance was high in DA. After June, water lettuce(Pistia stratiotes) and water hyacinth(Eichhornia crassipes) were flowed from tributary to the river. Standing crop of macrohydrophytes was high in DA from April to August, but it showed maximum standing crop (445g·dw/㎡) in DU after disturbance by explosive growth of exotic plants in October. In comparison with those in 1985, total productivities in DU and GA decreased to 33.5%, and the reduction ratio of dominant species, Trapa japonica was 56.7%. Najas marina, N. minor, Myriophyllum spicatum and Nymphoides indica have disappeared ever since the Nakdong barrage was constructed in the Nakdong river. They were divided into three groups (GA-SU-DU, DA, SI) by cluster analysis. Introduction of the exotic species in this river caused decreasing of endemic plants including endangered species Euryale ferox and rare species Hydocharis dubia, and food plants for waterfowl such as Trapa japonica, Vallisneria asiatica and Potamogeton crispus.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.244-250
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• 2000

Algal growth potential (AGP) bioassay were conducted to assess the water quality and fertility in the Kum River from March 1998 to June 1999. AGP values were always the highest at the conjuction site of the Kapchon, which is a tributary of the Kum River. Average value of AGP by Microcystis aeruginosa in the main river and tributary was 17.0 mg dw/l, 48.3 mg dw/l, respectively. AGP values decreased towards the lower part of the river and consisted in the water quality or nutrient analysisresults. Among the tributaries, AGP of the Kapchon, Mihochon and Soksongchon were relatively high, and the average value was 161.2, 50.3 and 125.6 mg dw/l, respectively. AGP value in the Yukuchon was lowest among the study stations with <2.7 mg dw/l. Water quality in the lower part of the Kum River deteriorated in drought season, and the AGP values of this season were higher than those in other seasons. Based on correlation analysis between AGP results and nutrients, limiting nutrient appeared to be P because SRP (r = 0.99) was higher than other nutrients, and N uptake in algal growth was preferred by $NH_4$ rather than $NO_3$. The variation of AGP was different according to localities and seasons, and it was related to nutrient fluctuation in the inlet tributary. Water quality status according to AGP was assessed to be eutrophic.

• Korean Journal of Ecology and Environment
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• v.44 no.4
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• pp.327-336
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• 2011

Temporal and spatial variations of primary productivity were investigated in the estuary of Youngsan River and Mokpo coastal areas in 2009. After heavy rain, concentrations of ammonium, phosphate, and silicate increased at six stations in August. The torrential rainfall may cause an increase in nutrient concentrations during summer. There is no limitation of nutrients (except for February at the mid-Youngsan estuarine region YS2) but a potential phosphate limitation was apparent at all stations. Silicate depletion was observed at YS2 in February due to a massive diatom bloom. The trophic status of the Youngsan estuary and Mokpo coastal areas were inferred from an assessment of the primary productivity. In February and May, YS1 (upper Youngsan estuary site) and YS2, YS3 (near the Youngsan river estuary barrage), MP1 (upper Mokpo coastal region site) were appropriately assigned to the mesotrophic category. MP2 (mid-Mokpo coastal region site) and MP3 (outer site of Mokpo coastal region) were assigned to the oligotrophic category. All stations were classified to the oligotrophic status in November. In August, after heavy rain, Youngsan estuary stations maintained mesotrophic status. On the other hand, MP1 and MP2 were classified in the eutrophic category and MP3 to mesotrophic status. In particular, primary productivities of MP1 and MP2 were 9 and 7 times higher respectively than the standard of eutrophic status ($1,000-mgC\;m^{-2}d^{-1}$). These results suggest that a massive freshwater discharge from the Youngsan River estuary should be considered a main factor in the occurrence of phytoplankton bloom in Mokpo coastal areas during summer. Seasonal variations of primary productivity are closely related with depth-integrated Chl. a.

• Korean Journal of Ecology and Environment
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• v.45 no.1
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• pp.82-92
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• 2012

In this study, we identified spatial and temporal patterns of reservoir trophic state within Keum-river watershed and analyzed correlations between chlorophyll-$a$ (Chl-$a$) and water quality parameters including conductivity and total phosphorus (TP). The reservoirs were separated into three trophic categories by the criteria of TP: 2 oligotrophic (9.3~9.4 ${\mu}g\;L^{-1}$), 15 mesotrophic (10.3~19.2 ${\mu}g\;L^{-1}$), and 14 eutrophic reservoirs (38.9~117.1 ${\mu}g\;L^{-1}$). Water quality parameters such as conductivity, TP, and Chl-$a$ reflected rainfall patterns, and the patters of annual mean TP were similar to the variation of annual mean Chl-$a$. Empirical models of Chl-$a$ against TP in reservoirs showed that statistical significance ($p$ <0.05) occurred in only some seasons and the trophic relations were modified by a washing-out effect or high non-algal light attenuation.

• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.78-83
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• 2012

Man-made reservoirs over 95% in Korea are shallower than 10 meters in depth, which is apt to cause eutrophication. This study has characterized long-term trends in water quality factors for the selected six reservoir points in the Kum River watersheds, and then estimated the seasonal trophic state index for each reservoir. The reservoir trophic state was evaluated at four trophic levels using the Korean trophic state index, TSIKO. It is observed from seasonal results for six reservoirs that the highest value of the trophic state index is estimated in summer while the trophic state index value is low in spring and winter seasons. Especially, the Boryeong Lake has a relatively lower trophic state index since this reservoir has been managed properly for water withdrawal and irrigation. It is expected that the seasonal trophic state index resulted from this study can contribute toward long-term water quality improvement plans for reservoirs.

• Journal of Korean Society on Water Environment
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• v.26 no.4
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• pp.673-680
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• 2010

Environmental factors and phytoplankton community in Lake Doam were monthly investigated at 3 stations from April 2009 to November 2009. During the study period, the concentrated rainfalls occurred at between July and August and then the TP and turbidity were sharply increased in in-lake. A total of 91 phytoplankton species was classified and these were consisted of 38 Bacillariophyceae, 35 Chlorophyceae, 10 Cyanophyceae, and 8 other species. Bacillariophyceae and Chlorophyceae were dominated during the seasonal succession of phytoplankton community, especially summer season. Bacillariophyceae was dominated from spring season to summer season and Chlorophyceae was dominated at summer season and autumn season. However, the dominance of Cyanophyceae generally developed at summer season in eutrophic water was not observed. From the analysis of correlation coefficient between environmental factors and phytoplankton cell number, we confirmed that there was a negative correlation between turbidity and cyanobacteria cell number (P<0.01). This result indicated that turbid water acts as the inhibitor of the cyanobacteria growth than other phytoplankton community.

• Journal of Korean Society on Water Environment
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• v.29 no.1
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• pp.7-18
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• 2013

We compared the structure of fish community and condition of major fish species in Lake Chungpyung and Lake Paldang, which are relatively shallow, meso-eutrophic, cascading dam reservoirs on the North Han River. Two lakes have wide littoral zone in the lakeside providing similarly good habitat for fishes, whereas fishery and water recreational activities such as motorboating, water skiing are allowed in Lake Chungpyung but are prohibited in Lake Paldang. The average lengths of large size fishes in Lake Chungpyung are shorter than those of same species in Lake Paldang, resulting in the slight distortion of generation distribution of those species in Lake Chungpyung, possibly owing to the active fishery such as fixed shore net fishing, gill net fishing and angling. Meanwhile the condition of fishes represented by the length-weight relationship of fish species did not show the significant differences between two lakes and showed normal condition. To evaluate the impact of physical disturbance such as loud noise and turbulent wave from water recreational activities to fishes precisely, further studies including physiological responses to stress an spawing activity should be needed.