• 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.

• Korean Journal of Ecology and Environment
• /
• v.38 no.3 s.113
• /
• pp.429-434
• /
• 2005

The dynamics of phytoplankton community after the formatiom of turbidity was assessed at Dam barrage of Lake Imha from May 2003 to July 2004. The maximum turbidity of 1221 NTU during September and October 2003 was well correlated with heavy precipitation caused by Typoon Maemi. A total of 102 phytoplankton taxa was identified and the most abundant phytoplankton group was Bacillariophyceae with 63 taxa, followed by Chlorophyceae with 23 taxa, Cyanophyceae with 9 taxa, 3 taxa each of Synurophyceae and Cryptophyceae and Euglenophyceae with 1 taxon. The total standing crops ranged between 270 indls. $mL^{-1}$ and 4,515 indls. $mL^{-1}$ during the investigation Periods. The three species, Cryptomonas ovata, Cyclotella sp. and Microcystis aeruginosa predominated in sequence after the decrease of turbidity.

• Journal of Korean Society on Water Environment
• /
• v.29 no.3
• /
• pp.428-437
• /
• 2013

Physico-chemical water quality parameters and the phytoplankton communities from 12 sites in Oship-stream, Songchunstream, and Namdae-stream, located Gyeongsangbukdo Uljin-gun, Yeongdeok-gun, and Pyeonghae-eup respectively, were investigated from April 2009 to February 2010. Oship-stream, which is an open estuary, was easily affected by ocean current compared to that of Songchun-stream and Namdae-stream. OS3 and OS4 conductivity was higher with a season average of 3,397 ${\mu}s/cm$. The streams were mesotrophic to hypertrophic. Biological oxygen demand (BOD) was about 3mg/L, which was level 2 on the water quality ratings, but a concentration of 5mg/L in April 2009 indicated increased pollution due to drought. A total of 118, 117, and 124 phytoplankton taxa were found in Oship-stream, Songchun-stream, and Namdae-stream, respectively. The apparent dominant species in the polluted waters included Cryptomonas ovata, Fragilaria construens var. venter, Oscillatoria limnetica, O. limosa, and Phormidium tenue. All of Oship-stream, SC2 and SC4 of Songchun-stream, and ND3 of Namdae-stream were eutrophic as a result of standing crop analysis. BOD was highly correlated with chlorophyll-a content(r=0.52). Phosphorus concentration and proliferation of phytoplankton were thought to most affect BOD concentration in all three streams.

• Journal of Korean Society on Water Environment
• /
• v.29 no.5
• /
• pp.641-647
• /
• 2013

We installed mesocosms including zooplankton, fishs, artificial marshy land and aquatic macrophytes in Kyoungan stream to study the reduction effects of algae from Sep. 16 to Oct. 28, 2011. The control tendency of phytoplankton taxa was compared by analyzing community structure and dominant species in each mesocosm. Under the condition where Bluegill was absent, Daphnia similoides showed good effect of algal control since it has large food area and has high grazing pressure. Bluegill selectively preys upon large zooplankton, Daphnia similoides, as it also preys on small zooplanktons that flow in. In condition that Bluegill was absent, Daphnia similoides preyed selectively large phytoplankton (Cryptomonas ovata). Due to the shading of light, removal of nutrients and providing refuge for small zooplanktons, aquatic macrophytes and artificial marshy land showed high level of algal control. In corrals with aquatic macrophytes and artificial marshy land, the dominancy of genus Coelastrum and Pediastrum, which are difficult for small zooplanktons to feed on, relatively increased. In conclusion, under conditions of small number of predators such as Bluegill, Daphnia similoides is thought to be useful in algal bloom; however, when lots of predators are present, using small sized zooplanktons along with artificial marshy land and aquatic macrophytes is thought to be more useful than using large zooplanktons.

• ALGAE
• /
• v.28 no.4
• /
• pp.331-341
• /
• 2013

Rhinomonas reticulata var. atrorosea G. Novarino is a photosynthetic marine flagellate that is known to have typical characteristics of cryptomonads. We examined the flagellar apparatus of R. reticulata var. atrorosea by transmission electron microscopy. The major components of the flagellar apparatus of R. reticulata var. atrorosea consisted of four types of microtubular roots (1r, 2r, 3r, and mr), a non-keeled rhizostyle (Rhs), mitochondrion-associated lamella (ML), two connections between basal bodies, a striated fibrous root (SR) and a striated fiber-associated microtubular root (SRm). Four types of microtubular roots originated near the ventral basal body and extended toward the left side of the basal bodies. The non-keeled Rhs originated at the Rhs-associated striated fiber, which was located between two basal bodies and extended into the middle of the cell. The ML was a plate-like fibrous structure associated with mitochondria and originating from a Rhs-associated fiber. It split into two parts and extended toward the dorsal-posterior of the cell to a mitochondrion. The SR and SRm extended parallel to the anterior lobe of the cell. The overall configuration of the flagellar apparatus in R. reticulata var. atrorosea was similar to the previously reported descriptions of those of Cryptomonas paramecium, C. pyrenoidifera, C. ovata, Hanusia phi, Guillardia theta, and Proteomonas sulcata. However, the flagellar apparatus system of R. reticulata var. atrorosea was more complex than those of other cryptomonad species due to the presence of an additional microtubular root and other distinctive features, such as a rhizostyle-associated striated fiber and large ML.

• 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.39 no.3 s.117
• /
• pp.390-401
• /
• 2006

This study was conducted to understand the phytoplankton-zooplankton trophic linkage in Lake Paldang ecosystems (Paldang Dam and Kyungan Stream) from April to December 2005. Zooplankton were filtered as two size groups (microzooplankton (MICZ): 60{\sim}20\;{\mu}m$, macrozooplankton (MACZ): >$200\;{\mu}m$), and their clearance rates and C-fluxes on phytoplankton were measured. Grazing experiments were performed in the laboratory with the different zooplankton densities (0, 2, 4, 8x of ambient density, n=2). Diatoms, such as Aulacoseira and Cyclotella were dominant phytoplankton taxa at both sites. Among phytoplankton communities, total carbon biomass of phyflagellates was much higher than others at both sites. Rotifers numerically dominated zooplankton community, while cladocerans dominated carbon biomass. Both phytoplankton and zooplankton density and biomass were high in spring, but decreased markedly after summer monsoon season. plankton biomass at Kyungan Stream was significantly higher than that of Paldang Dam. Zooplankton clearance rate and amount of C-flux were relatively high in the spring and then decreased after summer at both sites. Seasonal change of C-flux was similar to that of zooplankton biomass (P<0.001, n=7). MACZ clearance rate and C-flux were higher than those of MICZ. Water residence time and physical disturbance in summer appeared to affect zooplankton grazing on phytoplankton at the study sites. Our results indicate phytoplankton were an important energy source for zooplankton in Lake Paldang ecosystem. Furthermore, C-flux of plankton food web is affected by not only biological components but also physical parameters.