• Korean Journal of Ecology and Environment
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• v.33 no.2 s.90
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• pp.152-161
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• 2000

Simocephalus mixtus Sars was redescribed and illustrated from Korea. It had been frequently confused with S. vetulus (O.F. M$\"{u}$ller) and S. vetuloides Sars in the Far East. Redescription was based on the materials collected from various freshwater habitats at 97 localities in South Korea during the period from May 1981 to June 1999. Previous records of Simocephalus species from Korea were examined. S. mixtus is well distinguishable from other related species by having short and wide dorso-posterior carapace angle prominence, distally protruding dorsal margin of carapace, deep depression of the ventral head margin near the rostrum, elongate ocellus, and postabdominal claw lacking the basal pecten of denticles.

• The Korean Journal of Pesticide Science
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• v.8 no.2
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• pp.117-128
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• 2004

The influence of different feeding rates of three green algae on growth and reproduction in four Korean cladocera, Daphnia sp., Daphnia obtusa, Moina macrocopa, and Simocephalus vetulus was investigated. The growth and reproduction rates of Daphnia sp. fed Chlorella vulgaris cells were significantly increased than those of daphnid fed Senedesmus subspicatus and Selenastrum carpricornutum. The total offsprings of Daphnia sp. fed $25\times10^4$ and $50\times10^4$ cells Chlorella vulgaris for 21days were $124{\pm}2.8$ and $168{\pm}22.1$, respectively. The Daphnia obtusa fed $25\times10^4$ and $50\times10^4$ cells Selenastrum carpricornutum was shown good reproduction rates, $72.2{\pm}7.9$ and $79.6{\pm}22.9$, respectively. The Moina macrocopa fed $25\times10^4$ and $50\times10^4$ cells Senedesmus subspicatus as well as Simocephalus vetulus and $25\times10^4$ and $50\times10^4$ cells Chlorella vulgaris were shown good reproduction rates. All of algae tested were sufficient as a good diet for Korean Cladocerans in this study. However, the preferred alga was Chlorella vulgaris and the optimal feeding concentrations were $2.5\times10^5\sim5\times10^5$ cells/mL, because the alga was shown most stable and generally high production rates in all cladocerans tested.

• The Korean Journal of Pesticide Science
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• v.10 no.3
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• pp.189-195
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• 2006

The purpose of the current study was to develop a standard method to assess the ecological effect of pesticides using the representative Korean freshwater cladocerans. The indigenous cladocerans, Daphnia obtusa, Daphnia sp., Moina macrocopa, Simocephalus vetulus and Daphnia magna formally endorsed by the major international organizations were tested to select optimal culture media in laboratory condition. All of the Korean water flea tested showed good growth and fecundity in the moderately hard water ($CaCO_3$ ranged 80 to 100 mg $L^{-1}$) and soft water ($CaCO_3$ ranged 40 to 48 mg $L^{-1}$). However, considering that the total hardness of fresh water collected from 5 rivers ranged from 60.2 to 127.2 mg $L^{-1}$ ($CaCO_3$) and Ca deficiency could be a major determinant of species success and community structure among crustacean zooplankton, the present study suggests that the optimal water hardness for growing Daphnia sp., Daphnia obtusa, Moina macrocopa and Simocephalus vetulus is $80{\sim}100$ mg $L^{-1}$ of $CaCO_3$.

• The Korean Journal of Pesticide Science
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• v.9 no.3
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• pp.221-230
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• 2005

Temperature is an important ambient factor affecting the physiology and metabolism of aquatic invertebrates. In this study, we studied about the survival, reproduction and growth effects of 4 different temperatures(16, 20, 24, $28^{\circ}C$) in four Korean cladoceran, Daphnia sp., Daphnia obtusa, Moina macrocopa, Simocephalus vetulus and Daphnia magna as an international standard species. All 5 water flea tested showed that molting time, fecundity and intrinsic rate of natural increase(r) in high temperature condition were higher than those in lower temperature. On the other hand, lower survivals and longer time to start of offspring were showed in high temperature. Our results suggest that the optimal temperatures of Daphnia sp.,, Moina macrocopa and Simocephalus vetulus seem to be about $20^{\circ}C$ except for Daphnia obtusa which as showed good survivals and reproductions in $16^{\circ}C$.

• Korean Journal of Ecology and Environment
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• v.36 no.1 s.102
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• pp.9-20
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• 2003

Response-species of zooplankton on precipitation and temperature were investigat-ed in the tributaries of Han River from May to November, 2002. Total 42 species(Rotifer twenty three species, Cladocera ten species, Copepoda eight species and Protozoa one species) were collected in the target location. The highest abundance and the number of species were observed in May. Due to the summer precipitation the abundance of Rotifer and Cladocera were largely decreased in August. Dominant species of Rotifer appeared Brachionus urceolaris, Euclanis dilatata, Lecane Inua, Brachionus quadridentatus and Brachionus calyciflorus in May, Monostyla bulla and Conochilus unicornis in August and Brachionus quadridentatus, Euclanis dilatata and Lecane Iuna in November. Also, the dominant species of Cladocera were Moina weismanni, Simocephalus vetulus, Scapholebris aucrgnafa, Chydorus sphaericus in May, Chydorus sphaericus, Scapholebris mucronata in August, Chydorus sphaericus and Alona rectangular in November. Nearest neighbour clustering was implemented for classification of zooplankton abundance indifferent month of survey locations. The patterning of May and November appeared similar but August was different.

• Animal Systematics, Evolution and Diversity
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• v.3 no.2
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• pp.175-207
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• 1987

A taxonomic Study was carried out on the freshwater cladocerans from Korea during the period from August 1985 to May 1987. Materials consist of both the specimens deposited at Department of Zoology, College of Natural Sciences, Seoul National University and those collected at the freshwater regions such as rivers, lakes, ponds, bogs, rice fields, etc. During the period. As a result of examining the speciemens collected at the 123 locations in South Korea, 31 species of 7 families were identified and classified. In this paper, the authors submit the figures of the 31 species, of which the following 13 species were descirbed as hitherto unrecorded species in Korea : Diaphanosoma Leuchtenbergianum Fisher, 1858 : Simocephalus vetulus 9O.F.Mller, 1776) ; S. esxpinosus (koch, 1841); Ceriodaphnia reticulata (Jurine, 1820) ; Scapholeberis mucronata (O.F. Mller, 1785) ; Moina weismanni Ishikawa, 1896 : Ilyocryptus agilis Kurz, 1878 ; Biapertura affinis (Leydig, 1860) : Camptocercus rectirostris Schodler, 1862 ; alona costata Sars, 1862 ; Disparalona rostrata (Koch, 1841); Pseudochydorus globosus (Barird, 1843) ; Leptodora kindtii(Focke, 1844)

• Korean Journal of Ecology and Environment
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• v.49 no.4
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• pp.279-288
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• 2016

Stable Isotope Analysis(SIA) of carbon and nitrogen is useful tool for the understanding functional roles of target organisms in biological interactions in the food web. Recently, mixing model based on SIA is frequently used to determine which of the potential food sources predominantly assimilated by consumers, however, application of model is often limited and difficult for non-expert users of software. In the present study, we suggest easy manual of R software and package SIAR with example data regarding selective feeding of crustaceans dominated freshwater zooplankton community. We collected SIA data from the experimental mesocosms set up at the littoral area of eutrophic Chodae Reservoir, and analyzed the dominant crustacean species main food sources among small sized particulate organic matters (POM, <$50{\mu}m$), large sized POM (>$50{\mu}m$), and attached POM using mixing model. From the results obtained by SIAR model, Daphnia galeata and Ostracoda mainly consumed small sized POM while Simocephalus vetulus consumed both small and large sized POM simultaneously. Copepods collected from the reservoir showed no preferences on various food items, but in the mesocosm tanks, main food sources for the copepods was attached POM rather than planktonic preys including rotifers. The results have suggested that their roles as grazers in food web of eutrophicated reservoirs are different, and S. vetulus is more efficient grazer on wide range of food items such as large colony of phytoplankton and cyanobacteria during water bloom period.

• The Korean Journal of Pesticide Science
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• v.10 no.3
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• pp.196-200
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• 2006

In this study we investigated fecundity and survivorship of four staple Korean freshwater cladocerans for their whole life to develop a new standard method used for ecological risk assessment of pesticide. The tested Korean freshwater cladocerans were Daphnia obtusa, Daphnia sp., Moina macrocopa and Simocephalus vetulus. In addition, standard test species, Daphnia magna endorsed formally by the major international organizations was tested together in order to compare with the reproductive characteristics of Korean cladocerans. A total of 358 young was produced by D. magna, whereas, 297 young was reduced by Daphnia sp. throughout the entire life. The average life span of Daphnia magna was 50 days much longer than any other Korean species. Nevertheless all of the Korean water flea tested showed good fecundity, produced over 60 young for 21 days as the validation criterion for reproduction toxicity test in Ecological Effects Test Guidelines published by USEPA. Especially Moina macrocopa produced their first brood in 4 days. Therefore 10 day reproduction test with Moina macrocopa may be an alternative good method to save cost and time to elucidating the effects of hazardous substances on the reproduction of aquatic invertebrates.

• Korean Journal of Ecology and Environment
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• v.40 no.3
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• pp.357-369
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• 2007

Water fleas are very important organisms in aquatic ecosystem because they are key constituents of food webs as either glazers or foods for predators. Daphnia magna is a representative test species and it has been extensively used in ecotoxicity evaluation. However, Daphnia magna has not been found yet in Korean water environment. There are limitations of using the foreign species such as Daphnia magna to reflect domestic situations in Korea. Consequently it is mandatory to find domestic species suitable for bioassay, and to develop corresponding toxicity test methods using the domestic species. In this study, we widely collected the domestic and foreign toxicity test methods performed by using domestic water fleas in Korea. The 58 test methods were collected from the standard methods (OECD, US EPA, ASTM), government reports, SCI papers and domestic papers. Ten domestic water fleas selected were Bosmina longirostris, Ceriodaphnia dubia, Ceriodaphnia reticulata, Daphnia obtusa, Daphnia puex, Moina macrocopa, Moina micrura, Simocephalus mixtus, Simocephalus serrulatus, and Simocephalus vetulus. We suggested the domestic ecotoxicity test methods using domestic water fleas in Korea through providing a range of test conditions, and future directions for toxicity test using water flea. This study could be a useful basis for establishing the aquatic toxicity test methods with domestic organisms in Korea.

• The Korean Journal of Pesticide Science
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• v.14 no.1
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• pp.10-15
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• 2010

Most pesticides are poorly soluble in water and must be dissolved in a solvent carrier before being added to the test medium on aquatic toxicity test. The concentration of solvent is critical to the success of a test. This study were conducted to recommend possible organic solvents which have good solubility for pesticides and low toxicity to Korean native water flea to establish new standard toxicity test methods using Korean native water flea for ecological risk assessment of pesticide. Four Korean freshwater cladocerans, Daphnia obtusa, Daphnia sp., Moina macrocopa and Simocephalus vetulus were exposed to 10 different organic solvents during 48 hours to evaluate their toxic response to solvents. Ethyl acetate was the most toxic to cladocerans tested. Although ethyl ether was the least toxic to cladocerans tested, it may not adequate as possible solvent in aquatic toxicity test due to high volatility and low water solubility. In conclusion, acetone, methanol, ethanol and acetonitrile which has low toxicity as well as good water solubility are recommended as optimal organic solvent to use in aquatic toxicity tests with Korean native cladocerans tested.