• Korean Journal of Ecology and Environment
• /
• v.42 no.1
• /
• pp.67-74
• /
• 2009

To study the influence of the rotifer Brachionus calyciflorus on harmful algal bloom suppression, we focused on assessing the rotifer's abilities using several prey species : Microcystis aeruginosa, Synechocystis sp., Chlorella vulgaris and Coelastrum sp. of the warm-weather species and the cold-weather centric diatom Stephanodiscus hantzchii. Grazing effects and growth rates of rotifers B. calyciflorus were 94.5% and $1.29d^{-1}$, respectively, for Synechocystis sp., 87.4% and $0.60d^{-1}$, respectively, for M. aeruginosa, 95.2% and $0.65d^{-1}$, respectively, for C. $vulgaris^{TM}$, 78.6% and $0.45d^{-1}$, respectively, for C. vulgaris UTEX., 86.5% and $0.99d^{-1}$, respectively, for Coelastrum sp., and 82.6% and $0.40d^{-1}$, respectively, for S. hantzchii. Of these, although the growth of Synechocystis and Coelastrum was effectively suppressed by rotifer grazing, efficient suppression effects on Stephanodiscus blooms were unexpected. The present study revealed that reproduction of B. calyciflorus was greatly influenced by its food types in the initial stages and the efficiencies of bio-agents as sole food sources vary depending on the target algae and the agent.

• Journal of Korean Society on Water Environment
• /
• v.30 no.5
• /
• pp.539-548
• /
• 2014

This study was carried out to investigate algal community structures and their correlations with environmental factors on five weir areas in the Nakdong River, South Korea. Water qualities, hydrodynamics, meteorological conditions and algal species compositions were observed in studied sites from May 2010 to Dec. 2013. Results showed that average total phosphorus concentration of 2013 was decreased by 52.4% in comparing with that from 2010 to 2011. Chlorophyll.a concentrations were positive significant with water temperature, pH, total phosphorus and total nitrogen, but is not significant with turbidity and suspended solids. Seasonal successions of algae were observed that Stephanodiscus sp. was dominant species with 65.3% of dominant frequency in studied site. Large algal biomass of the low temperature-adapted diatoms were observed during temperature range of $4{\sim}9^{\circ}C$, but large cyanobacterial biomass mainly during high temperature period ranged from $22^{\circ}C$ to $32^{\circ}C$. Microcystis sp. dominated during high water temperature in summer. The yearly correlations of algal biomass with accumulated solar radiations were not significant but seasonal correlations of summer from June to August were significant with correlation coefficient 0.33 (p<0.05). There were not significant correlations between turbidities and algal biomass. Turbidity and suspended solids concentrations were not significant correlation with algal biomass. According to the results, algal communities had strong correlation with water temperature and had partially correlation with solar radiation. For an effective management of algal blooms, water managers should survey with more long-term monitoring of various environmental factors and algal communities.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.34 no.5
• /
• pp.445-456
• /
• 2001

In the 1990s, Cochlodinium polykikoides red tide has been annually occurred in the southern coast of Korea and caused the mass damage to the fisheries with a huge amount of economic loss. The present study was done to establish the biological foundation for the elucidation of the mechanism of C. polykikoiaes red tide. The growth response of C. polykikoides to physico-chemical factors such as temperature, salinity, pH, and light intensity were examined using axenic cultures to evaluate the relative importance of these factors on the dynamics of natural populations, It was found that the highest growth conditions were $25^{\circ}C,\;40\%_{\circ}$, pH 7.5, and 7,500 lux, respectively. The tolerable salinity range of growth was relatively wide at an optimum temperature and was reduced to a much narrower range at a sub-optimum temperature. These findings indicate that C. polykikoides is an eurythermal and euryhaline organism. The organism demanded higher light intensity and oceanic pH narrow in its growth. C. polykikoides utilize inorganic nutrients, such as nitrate and ammonium as N, and phosphate as P. The nutritional requirements of C. polykikoides were $40{\mu}M$ for nitrate, $50{\mu}M$ for ammonium, and $5{\mu}M$ for phosphate. The half saturation constant (Ks) for growth was $2.10{\mu}M$ for nitrate, $1.03{\mu}M$ for ammonium, and $0.57{\mu}M$ for phosphate. These values were comparatively smaller than those of other dinoflagellates reported previously. We confirmed that the organism is characterized as an eutrophic species. However, ammonium Ks value is smaller than that of other eutrophic species, This result indicates that C. polykikoides red tide may outbreak in the waters which eutrophication is in progress rather than eutrophicated waters. C. polykikoides preferred ammonium better than nitrate as a nitrogen source when in a growth stage, Therefore, our results indicate that ammonium is more important nutrient on the growth of the organism in comparison with other inorganic nutrients and C. polykikoides red tide is related with the increased ammonium concentration in the coastal waters.

• Korean Journal of Ecology and Environment
• /
• v.47 no.1
• /
• pp.1-12
• /
• 2014

Some blue-green algal species such as those in the genus Anabaena causing severe algal blooms can produce akinetes, resting spores, in aquatic ecosystems. Germinated akinetes staying in the sediment as "seed banks" grow into vegetative cells under favorable conditions of light intensity, nutrient, and temperature. Therefore, akinete plays an important role in forming the nuisance bloom. However, little information is available in the ecological study of akinetes compared to that of vegetative cells in Korea. This review reports ecological and physiological characteristics of akinetes, especially of the blue-green algal genus Anabaena. We also suggest the feasible area of akinetes in the freshwater ecosystems. We expect that the suggested studies associated with akinetes will contribute to further understanding the life cycle and ecology of Anabaena and other algae.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.11 no.5
• /
• pp.382-390
• /
• 2006

Various microorganisms were isolated from the surface waters and sediments of eutrophic lakes and reservoirs in Korea to enable an investigation of bacteria having algal lytic activities against Anabaena flos-aquae when water blooming occurs and to study enzyme profiles of algal lytic bacteria. Two bacterial strains, AFK-07 and AFK-13, were cultured, characterized and identified as Acinetobacter johnsonii and Sinorhizobium sp., respectively. The A. johnsonii AFK-07 exhibited a high level of degradatory activities against A. flos-aquae, and produced alginase, caseinase, lipase, fucodian hydrolase, and laminarinase. Moreover, many kinds of glycosidase, such as ${\beta}-galactosidase,\;{\beta}-glucosidase,\;{\beta}-glucosaminidase,\;and\; {\beta}-xylosidase$, which hydrolyzed ${\beta}-O-glycosidic$ bonds, were found in cell-free extracts of A. johnsonii AFK-07. Other glycosidases such as ${\alpha}-galactosidase,\;{\alpha}-N-Ac-galactosidase,\;{\alpha}-mannosidase,\; and\;{\alpha}-L-fucosidase$, which cleave ${\alpha}-O-glycosidic$ bonds, were not identified in AFK-07. In the Sinorhizobium sp. AFK-13, the enzymes alginase, amylase, proteinase (caseinase and gelatinase), carboxymethyl-cellulase (CMCase), laminarinase, and lipase were notable. No glycosidase was produced in the AFK-13 strain. Therefore, the enzyme system of A. johnsonii AFK-07 had a more complex mechanism in place to degrade the cyanobacteria cell walls than did the enzyme system of Sinorhizobium sp. AFK-13. The polysaccharides or the peptidoglycans of A. flos-aquae may be hydrolyzed and metabolized to a range of easily utilized monosaccharides or other low molecular weight organic substances by strain AFK-07 of. A. johnsonii, while the products of polysaccharide degradation or peptidoglycans were more likely to be utilized by Sinorhizobium sp. AFK-13. These bacterial interactions may offer an alternative effective approach to controlling the water choking effects of summer blooms affecting our lakes and reservoirs.

• Journal of Korean Society on Water Environment
• /
• v.25 no.6
• /
• pp.840-848
• /
• 2009

Spatial and temporal distributions of POC and DOC were surveyed in the North Han River system, Korea The proportion of algal cells was calculated in four reservoirs (Lakes Soyang, Paro, Chunchon, and Uiam). Monthly average DOC concentrations ranged from 1.5 to 2.3 mg C/L, and POC showed larger variation than DOC (range 0.3 to 1.9 mg C/L). The average proportion of POC in TOC was higher than those of typical natural lakes. Due to the influence of the Asian summer monsoon, the seasonal variation in POC concentration depended on heavy rain events occurring during the summer. POC concentrations increased during the summer monsoon season due to turbid storm runoff laden with debris, while DOC concentrations did not increase. The highest POC concentrations were observed in Lake Soyang in 2006 when a severe rain event occurred. In two deep stratified reservoirs (Lake Soyang and Paro) storm runoffs formed an intermediate turbidity layer with high POC and chlorophyll concentrations which is thought to originate from terrestrial debris and periphyton transported by inflowing streams. The proportion of algal cells in total POC was much lower than for most natural lakes, and it varied with season; low in the monsoon season and high in dry seasons with algal blooms. An analysis of POC concentration and chlorophyll a concentration showed that the ratio of POC/Chl.a varied from 24 to 80.

• Korean Journal of Ecology and Environment
• /
• v.48 no.4
• /
• pp.238-252
• /
• 2015

The effect of weir construction (2009~2011) was investigated on algal bloom dynamics and surrounding conditions in the Youngsan River by analyzing the long-term (2001~2014) data provided by the Water Information System, Ministry of Environment. The data include chlorophyll a and water properties such as total suspended solids (TSS), ammonium ($NH_4{^+}$), nitrate ($NO_3{^-}$), orthophosphate ($PO{_4}^{3-}$), total nitrogen (TN), total phosphorus (TP) and DIN/DIP molar ratio collected from 12 stations along the channel of the river. Temporal variations were examined using data collected monthly from 2001~2014 and Box-Whisker plot was used to examine the difference in algal bloom dynamics between before (2006~2008) and after (2012~2014) the weir construction. Pearson's correlation analysis was also used to analyze the correlation of parameters. The results showed that TSS affecting water turbidity increased during the construction but decreased especially at the stations located in the upper and middle regions of the river after the construction. Ammonium concentrations increased whereas the concentrations of other nutrients decreased after the construction inducing an increase in N:P molar ratio. Chlorophyll a decreased suddenly during the construction but increased clearly after the construction at the stations where TSS decreased. This indicates that algal blooms can develop in the Youngsan River due to a decrease in turbidity that increases light penetration in water column although the concentrations of nutrients such as orthophosphate were reduced after the weir construction.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.22 no.3
• /
• pp.10-20
• /
• 2019

Irregular rainfall caused by climate change, in combination with non-point pollution, can cause water systems worldwide to suffer from frequent eutrophication and algal blooms. This type of water pollution is more common in agricultural prone to water system inflow of non-point pollution. Therefore, in this study, the correlation between Unmanned Aerial Vehicle(UAV) multi-spectral images and total phosphorus, total nitrogen, and chlorophyll-a with indirect association of algal blooms, was analyzed to identify the usability of UAV image to identify water quality characteristics in agricultural streams. The analysis the vegetation index Normalized Differences Index (NDVI), the Normalized Differences Red Edge(NDRE), and the Chlorophyll Index Red Edge(CIRE) for the detection of multi-spectral images and algal blooms collected from the target regions Yang cheon and Hamyang Wicheon. The analysis of the correlation between image values and water quality analysis values for the water sampling points, total phosphorus at a significance level of 0.05 was correlated with the CIRE(0.66), and chlorophyll-a showed correlation with Blue(-0.67), Green(-0.66), NDVI(0.75), NDRE (0.67), CIRE(0.74). Total nitrogen was correlated with the Red(-0.64), Red edge (-0.64) and Near-Infrared Ray(NIR)(-0.72) wavelength at the significance level of 0.05. The results of this study confirmed a significant correlations between multi-spectral images collected through UAV and the factors responsible for water pollution, In the case of the vegetation index used for the detection of algal bloom, the possibility of identification of not only chlorophyll-a but also total phosphorus was confirmed. This data will be used as a meaningful data for counterplan such as selecting non-point pollution apprehensive area in agricultural area.

• Korean Journal of Ecology and Environment
• /
• v.36 no.4 s.105
• /
• pp.467-472
• /
• 2003

In this study, an algal fence was developed and applied to reduce the input of algal scum into the water intake facility. The effectiveness of vertical algal fences(overlapped three types of meshes, (312 ${\mu}m$ ${\times}$ 375 ${\mu}m$, 390 ${\mu}m$ ${\times}$ 450 ${\mu}m$, and 0,7 cm ${\times}$ 1cm; vertical depth, 1.5 m; length of fence, about 120 m)) was experimentally tested at a water intake facility (Mulgum, lower Nakdong River). The application of the fence resulted in the statistically significant difference of algal biomass between inside and outside of the fence. According to ANOVA test, chi. a concentration in Day-1showed large difference at each depth of 0, 1, 2 m (0.001> p at each depth, n = 16 respectively). Especially large difference was observed at 0 and 1 m depth. However, the fence was only effective for a short period and its efficiency declined by Day-5after the installation. When better maintenance options for the fence are prepared, e.g. mechanical installation and periodic backwashing of the fence, the performance of algal fence may be sustained. In addition, reliable models for bloom prediction are required to provide an advanced indication of the optimal timing for the installation so that effective operation would be achieved.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.19 no.3
• /
• pp.241-247
• /
• 2013

Yellow clay dispersion has been applied to minimize fisheries impact by the red tide Cochlodinium polykrikoides blooms in Korean coasts since 1995. The present preliminary study documents the effect of yellow clay on Korean rockfish, Sebastes schlegelii, in terms of oxygen consumption rate (OCR). The OCR in the low clay suspension (0.05 and 0.23 %, w/w) showed normal level compared to the control. In contrast, the OCR for each one of three replicates in the high clay suspension (1.16 and 5.58 %, w/w) was not returned to the previous level that clay was not treated, indicating that high clay suspension (${\geq}1.16%$, w/w) might give negative effect on Korean rockfish. Overall, this result suggests that field application of clay to control Harmful Algal Blooms (HABs) may not give impact on Korean rockfish once the clay is dispersed in a low concentration (${\leq}0.23%$). In order to understand the changes of OCR in the repeated exposure to clay, it is required to do further studies on the changes of OCR when the fish is exposed to clay repeatedly after recovery in the normal seawater.