• Korean Journal of Ecology and Environment
• /
• v.38 no.1 s.110
• /
• pp.95-104
• /
• 2005

Using TSI, TSIm and LTSI, we compared physico-chemical water quality and trophic state of 5 stations in Lake Andong from June 2002 to June 2003 and examined the correlation of them. It is difficult to evaluate trophic state of waters by each parameter, TP, Chl-a and SD, because TSI and TSIm in each section show different results, oligo-, meso- and eutrophic state. But three methods, TSI, TSIm and LTSI, show the same result that trophic degree lows as it goes to a lower area of the lake. The correlation among them is closer in the upper shallow waters than in the lower deep waters. The reciprocal application of trophic state indices is possible because the coefficient of mean correlation ranges 0.9117 to 0.9909. In conclusion, it seems that LTSI reflects a characteristic of water quality in each section better than TSI, TSIm and is very effective to simplify trophic state evaluation and minimize researcher's subjectivity.

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

• Korean Journal of Ecology and Environment
• /
• v.36 no.3 s.104
• /
• pp.381-388
• /
• 2003

The fertility of stream water in major streams of the Lake Shihwa Watershed was compared using water analyses and algal growth potential test (AGPT) in typical drought seasons from December 2001 to April 2002, The water quality varied considerably depending on streams. These streams were very rich in inorganic nutrients that the nutrient levels and characteristics of each stream could be easily determined. Through AGPT, 63.6% of growth was observed in the average values of each stream, with non-growth accounting for 36.4%. AGPT results showed that 40.9% of the 22 stations were in hypertrophic condition and 54.5% in eutrophic condition. AGPT values were significantly correlated with TIN, $NH_4$, and SRP (p <0.001); compared to other nutrients, however, they were more related to SRP and $NH_4$. Moreover, the values increased with high concentration of N and P and low N/P ratios. Nonetheless, the values were more dependent on P concentration than N concentration. This suggests that the effect of P on the water quality of lake situated in downstream may serve as a potential indicator of phytoplankton development. Depending on the drainage pattern of streams, the wastewaters of wastewater treatment plant (WwTP) and untreated wastewater (UTW) were found to have 53.4% and 46.6%, respevtively, of TIN, 51.9% and 48.1% of $NH_4$, 62.9% and 37.1% of $NO_3$, 62.6% and 37.4% of SRP, and 44.1% and 55.9% of SRSi. The AGPT value was 51.1% in WwTP wastewater and 48.9% in UTW wastewater, the concentration of WwTP wastewater was slightly higher. For untreated wastewaters flowing into the constructed wetland and into the lake, TIN accounts for 43.0% and 57.0%, respectively, of nitrogen components, $NH_4$ 44.4% and 55.6%, $NO_3$ 39.6% and 60.4%, SRP 53.5% and 46.5%, and SRSi 52.3% and 47.7%, respectively. The AGPT value was 58.0% in the constructed wetland and 42.0% in Lake Shihwa; the concentration in streams flowing into the wetland was slightly higher. Therefore, Persistent and large development of phytoplankton in Lake Shihwa cannot be prevented unless a measure tophytoplankton control is implemented. This is because the concentration of nutrients in specific streams flowing into the lake is very high, even though the inflow of water is low.

• Korean Journal of Ecology and Environment
• /
• v.41 no.3
• /
• pp.338-347
• /
• 2008

Grazing rate (GR) and feces production (FP) of freshwater snail Cipangopaludina chinensis malleata on two hibernal diatom communities were examined in a laboratory. Snail with the similar size (4.2$\sim$5.8 cm) were collected from the Gunsan and Okgu district (Jeonbuk), transferred to the artificial management system in laboratory, and starved for 3 day before the experiment. The feeding experiments were conducted at various conditions such as passage of time (0, 1, 4 and 7 hr), snail density (0.0, 0.5, 1.0, 2.0 and 4.0 ind. $L^{-1}$) and kinds of prey (cold lake and stream water). One prey used in this study is the water of Lake Ilgam, the other is that of Han river. Lake Ilgam water was dominated by Synedra ulna (69.1%) and Scenedesmus sp. (6.6%), while Han river was by Asterionella formosa (69.4%) and Diatoma vulgare (27.7%). With the increment of snail density and time, the Chl-a concentration of two experimental waters were clearly decreased. Chl-a of Han river rapidly was decreased after 1 hour of snail treatment, while that of Ilgam lake was decreased after 4 hour. On the passage of time, a highest GR (1.94 L $g^{-1}\;h^{-1}$) showed at 1 hr, and then, decreased gradually to 0.04 L $g^{-1}\;h^{-1}$ by 7 hr. The highest FP (0.11 mg $L^{-1}$) showed at 7 hr. These results indicate that native snail Cipangopaludina chinensis malleata may be applied as a potential bio-filter to control diatom blooms in the cold lake and stream.

• Korean Journal of Ecology and Environment
• /
• v.40 no.1
• /
• pp.61-71
• /
• 2007

The photosynthetic characteristics and primary production by phytoplankton in open waters of two wetlands (the Banwol and the Donghwa wetland) of Sihwa Constructed Wetland with different water chemistry were investigated to provide the information for the wetland management considering the water treatment efficiency. During the study period (from March to October, 2005) the primary productivity in open waters ranged from 481 to 11,275 mgC $m^{-2}$ $day^{-1}$, which is very high compared with the eutrophic level of 600mgC $m^{-2}$ $day^{-1}$. From the analysis of the photosynthesis-irradiance (P-I) model parameters, the photosynthetic characteristics may be affected by different concentration and ratio of nutrient (N and P) between two wetlands. Assimilation number (AN) was higher in the Donghwa wetland (average AN: 8.5gC $gChl^{-1}$ $hr^{-1}$) with high P and low N/P ratio than the Banwol wetland (average AN: 5.8gC $gChl^{-1}$ $hr^{-1}$) with high N and high N/P ratio. This result indicates that AN may be concerned with phosphorus than nitrogen and low NIP ratio. Positive correlation (R=0.81) was observed between the initial slope and AN, implying that AN was high in case of phytoplankton having more active photosynthesis ability under low light. On the other hand, maximum photosynthesis (Pmax) was related positively with chlorophyll a concentration showing correlation coefficient of 0.47. In this study, considering the high primary production through phytoplankton photosynthesis in open waters of Sihwa Constructed Wetland, the produced organic matter by phytoplankton may affect the water quality within wetland and its efficiency of water treatment. Also, the photosynthetic characteristics may be affected by different nutrient enrichment (especially phosphorus) of wetlands. This study suggests that the production by phytoplankton and its characteristics in open water of constructed wetland for water treatment should be considered to improve the removal efficiency of organic matter.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.2 no.2
• /
• pp.92-100
• /
• 1997

Distribution of bacterial abundance and production was investigated during October, 1995-August, 1996 in Lake Shiwha constructed artificially in 1994. Its water column was distinguished by two layers: the brackish surface layer with salinity ranged from 6 to 20‰ and the saline hypoxic/anoxic bottom layer with salinity of 17 to 27‰ Except for samples collected in March, 1996 (on average 13 ${\mu}g\;l^{-1}$), chlorophyll a concentration ranged from 27.6 to 249.5 ${\mu}g\;l^{-1}$ in the euphotic zone, indicating the hypertrophic condition of Lake Shiwha during most of the studied period. In this study, bacterial productions measured by $^3H$-thymidine incorporation method were similar to those by $^{14}C$-leucine incorporation method. In hypertrophic, surface waters of Lake Shiwha, bacterial abundance and production ranged from 1.4 to $19.5{\times}10^9\;cells\;l^{-1}$ and from 1.6 to $126.5{\times}10^7\;cells\;l^{-1}\;h^{-1}$ respectively; 2 to 4 fold and 2 to 30 fold higher than those in eutrophic coastal waters outside of Lake Shiwha, respectively. Turnover times of bacterial community in the surface layer of Lake Shiwha ranged from 0.2 to 8.9 day, indicating that bacteria in the lake seemed to adapt to the hypertrophic condition. In the hypoxic bottom layer, bacterial abundance and production was up to 3 fold and 20 fold lower than those in the surface layer, and showed slow bacterial growth. Significant correlations between the bacterial abundance, production, and community turnover time with water temperature indicate water temperature was the important factor controlling distribution and growth of bacteria. However, during summer season, bacterial production seemed to be regulated by supply of substrates.

• Korean Journal of Ecology and Environment
• /
• v.44 no.1
• /
• pp.31-41
• /
• 2011

To optimize the natural chemical agents against nuisance phytoplankton, we examined algal removal activity (ABA) of Plant-Mineral Composite (PMC), which already developed by our teams (Kim et al., 2010), on various conditions. The PMC are consisted of extracted-mixtures with indigenous plants (Camellia sinensis, Quercusacutissima and Castanea crenata) and minerals (Loess, Quartz porphyry, and natural zeolite), and characterized by coagulation and floating of low-density suspended solids. A simple extraction process was adopted, such as drying and grinding of raw material, water-extraction by high temperature-sonication and filtering. All tests were performed in 3 L plastic chambers varying conditions; six different concentrations ($0{\sim}1.0\;mL\;L^{-1}$), six light intensities ($8{\sim}1,400\;{\mu}mol\;m^{-2}s^{-1}$), three temperatures ($10{\sim}30^{\circ}C$), four pHs (7~10), five water depths (10~50 cm), and three different waters dominated by cyanobacteria, diatom, and green algae, respectively. Results indicate that the highest ABA of PMC was seen at $0.05\;mL\;L^{-1}$ in treatment concentrations, where showed a reduction of more than 80% of control phytoplankton biomass, while $1,400\;{\mu}mol\;m^{-2}s^{-1}$ in light intensity (>90%), $20{\sim}30^{\circ}C$ temperature (>60%), 7~9 in pH (>90%), below 50 cm in water depth (>90%), and cyanobacterial dominating waters (>80%), respectively. Over the test, ABA of PMC were more obvious on the algal biomass (chlorophyll-${\alpha}$) than suspended solids, suggesting a selectivity of PMC to particle size or natures. These results suggest that PMC agents can play an important role as natural agents to remove the nuisant algal aggregates or seston of eutrophic lake, where occur cyanobacterial bloom in a shallow shore of lake during warm season.

• Korean Journal of Ecology and Environment
• /
• v.43 no.3
• /
• pp.437-450
• /
• 2010

Ecological influences of indigenous freshwater bivalve Unio douglasiae on the water quality and epilithic diatom community was examined with artificial stream (AST), which constructed in a laboratory daily receiving the eutrophic lake water. For the colonization of new periphyton community, forty commercial slide glasses were deposited as a substrate into the lowest part of each AST. Prior to 1 week, the AST was operated to induce the freely-colonization of the algal community in the absence of mussels. After the mussels was introduced at 435 indiv. $m^{-2}$ between step 1 and step 5, the passed water and substrates were daily collected to analysis the change of water quality and lotic and lentic algae abundance for 10 days. Compared to the control, turbidity (60.0% of control), suspended solids (62.5%), and chlorophyll-$\alpha$ (72.2%) in mussel-passed waters were decreased significantly, while a strong increase of ammonia (up to 800% of control) was companied with the decrease of dissolved oxygen (19.5% of control) and total phosphorus (23.9%), respectively. On average, the concentrations of suspended solids (67.0% of control) and chlorophyll-$\alpha$ (89.4%) in mussel-treated substrates were remarkably increased, however algal abundance in its water simultaneously decreased. These results indicate that incidentally or purposely mussel introductions can decrease organic matter of the stream and increase transparency of stream water, however, mussel-mediated nutrient and pseudofeces release may stimulate the adverse growth of periphyton or phytoplankton community in the lower stream or reservoir.

• Korean Journal of Ecology and Environment
• /
• v.41 no.2
• /
• pp.237-246
• /
• 2008

Filtration rates and fecal production of freshwater bivalve, Unio douglasiae on two kinds of hibernal diatom communities were measured simultaneously in a laboratory. One community is the Han River (HAN), which dominated by Asterionella Formosa. Stephanodiscus hantzschii (ca. 98% of total phytoplankton). The other community is the Ilgam Lake (IL), which dominated by Synedra ulna, Scenedesmus sp. Microcystis aeruginosa (ca. 82%). The HAN water has higher concentrations of nutrient (TN and TP) and chlorophyll $\alpha$ (Chl-$\alpha$), lower turbidity and conductivity than the IL water. Water sampling for the feeding experiment was conducted in the same day (Jan 15, 2008) and similar time (AM 10:00 for HAN, AM 11:00 for IL). Mussels with the similar size ($0.0{\pm}0.5\;cm$) were collected from the Gunsan and Okgu district (Jeonbuk), and starved in a laboratory for 2 days before the experiment. The experiment comprised CON (no addition of mussel), LOW (addition of mussel at 0.3 indiv. $L^{-1}$), MID (1.0 indiv. $L^{-1}$) and HIGH (2.0 indiv. $L^{-1}$), respectively. With the increment of mussel density and time, the concentration of Chl-$\alpha$ in two diatom communities were clearly decreased; Chl-$\alpha$ of HAN gradually decreased after 1 hour of mussel treatment, while that of IL decreased as soon as mussel introduction. In 7 hours of treatment, the former was removed finally up to about 90% of control, while the later was remained as about 50%. Under the presence of mussel, total phytoplankton density was shifted as the similar patterns to that of Chl-$\alpha$ (r=0.705, P<0.0001), however, there showed the drastic differences following a species. Based on the concentration of Chl-$\alpha$, filtration rate of U. douglasiae averaged 0.266 $L\;g^{-1}\;h^{-1}$ (0.115 to 0.442) on HAN and $0.577\;L\;g^{-1}\;h^{-1}$ (0.146 to 1.428) on IL water, respectively. There were no differences in feces production among the mussel density in the HAH water (ANOVA, P>0.5), while in IL water, including lots of seston, the HIGH mussel produced the higher fecal materials, over one hundred times of LOW. These results suggest that freshwater bivalve Unio douglasiae have the alternative potential, as a filter-feeder of seston in turbid lake, and a biological controller of diatom bloom in cold stream.

• 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.